Diagnostics and control of an on board hydrogen generation and delivery system

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Modes of Operation for an Ideal CHC System

sk Safety monitoring :k System status sk Sleep

START

k System status sk Converter temperature

sk Start air pump }k Release H2 until: O time

O temperature

O volume (pressure) sk Safety monitoring

REST

sk Safety monitoring sk System status

RESTORE H2 SUPPLY

sk Electrolyze

Control current draw Safety monitoring System status

Monitor:

o Pressure o Temperature

SYSTEM MAINTENANCE

sk Recover cathode water sk System status sk Safety monitoring

RETURN TO PRE-START

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AR PUMP VALVE

SWITCH VALVE

BUBBLE 5/2 343 SERAL DETECTOR PORT

ELECTROLYZER 3O4 5/O HYDROGEN POWER PRESSURE SOURCE SENSOR

CONDUCTIVITY 3/9 3O8 WATER LEVEL SENSORS SENSOR

CONTROLLER

CELL VOLTAGE 323

SENSOR VALVE

CURRENT VALVE

SENSOR

CATHODE 3.31 339 AMBENT PRESSURE HYDROGEN SENSOR DETECTOR

ELECTROLYZER 335

TEMPERATURE

SENSOR

FIG 16

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PRELMINARY

CHECKS

STACK POWER

MAINTENANCE

MONITOR H2

PRODUCTION

FLASH PNL.

INDICATOR

WATER

PRESENT IN

H2 TAN

YES

RECOVER VLVS

YES

OFF

ELECTROLYZER SHUT DOWN

RETURN

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UBBL

FREQUENCY SET ERROR

YES

SET ERROR

FLAG (E1)

S-lis 6O2 6O4 6IO

SET ERROR

SET ERROR

OFF

AR PUMP

RETURN

OFF

ELECTROLYZER

TO DLE

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DLAGNOSTICS AND CONTROL OF AN ON being converted as they pass through the catalyst. The time BOARD HYDROGEN GENERATION AND period between “cold start” and reaching the light off DELIVERY SYSTEM temperature is generally referred to as the light-off time.

BACKGROUND OF THE INVENTION

The conventional method of heating the catalytic con verter is to heat the catalyst by contact with high temperature 1. Field of the Invention exhaust gases from the engine. This heating, in conjunction The present invention relates generally to the field of with the exothermic nature of the oxidation reaction occur catalysis for the reduction of emissions from internal com ring at the catalyst, will bring the catalyst to light-off bustion engines. More particularly, the present invention temperature. However, until the light-off temperature is relates to a method and apparatus for producing hydrogen reached, the exhaust gas passes through the catalyst rela and oxygen, Storing hydrogen and delivering hydrogen into tively unchanged. In addition, the composition of the engine a catalytic converter on a vehicle in order to heat the catalyst exhaust changes as the engine heats from the cold Start through catalytic combination of the hydrogen with oxygen temperature, and the catalyst monolith is typically designed provided or from the air or Stored oxygen. This spontaneous 15 to work best with the composition of the exhaust stream catalytic combination releases Sufficient heat to rapidly bring produced at the normal elevated engine operating tempera the catalytic converter to operating temperatures. ture.

2. Background of the Related Art There have been several attempts to shorten or avoid the The control and Suppression of unwanted emissions cre light-off time of the catalytic converter. Current techniques ated by the operation of an internal combustion engine is a employ one or more of the following methods: electrical primary consideration for engine designers and vehicle heating of the exhaust gases and/or of the catalytic converter manufacturers because of nearly world-wide governmental itself; thermal insulation; multi-chambered configurations of requirements regarding acceptable emission levels. Over the catalytic converter, and/or placing the catalytic converter eighty percent (80%) of the unacceptable emissions or drawbacks adjacent to the engine for heating. All of these methods have pollutants created by internal combustion engines equipped 25 and limitations.

with catalytic converters occur during cold Start operations. Placing the catalytic converter almost immediately adja These pollutants are emitted for a period of one to three cent to the engine is not desirable because of the tendency minutes after cold engine Starting, in large part because that to overheat the catalyst with resulting accelerated degrada is the time period required for the catalyst to reach an tion of the catalyst. Thermal insulation is also not a desirable efficient operating temperature. Therefore, even though the option because of the same problems, especially during engine exhaust is flowing through the catalytic converter, operation under maximum operating temperature ranges. until the exhaust heats the catalytic converter to its operating Electrical heating of catalytic converters (“EHC) has range from engine Start up, the engine emissions are only been a popular proposed method of attempting to preheat the Slightly catalyzed during that time period. catalyst monoliths. Limitations on the equipment and In order to meet governmental emission Standards for 35 process, however, affect the utility of this method. The internal combustion engine exhaust a catalytic converter is primary limitation on electrical preheating is the electrical located in the exhaust Stream of the engine. The converter energy required by the heater. The typical car battery is not typically includes a canister holding a Suitable catalyst, Such a practical power Source to Supply the electrical power as a three-way catalytic converter (TWC) catalyst monolith, because the electrical load on the vehicle battery during the that will oxygenate unburned, unacceptable components in 40 period required may exceed the rated battery output. In any the exhaust stream including hydrocarbons (HC), their par event, the load placed on a typical 12 volt vehicle battery tially oxidized derivatives Such as aldehydes and carbon will shorten the lifetime of the battery. Also, there is a monoxide (CO), and at the same time reducing nitrogen measurable delay between the time the operator of the oxides (NO), after almost stoichiometric fuel burn with vehicle places the ignition Switch in the “on” position and oxygen in the cylinders of the engine. The exhaust gas is 45 the time the heater brings the catalyst to light-off tempera passed through the catalyst monolith, thereby completing ture.

the oxygenation of unburned HC and CO, and the reduction Typically, in the interval between Start up and light-off, of NO in the exhaust to convert these unacceptable emis the exhaust Stream is oxygen deficient. Because the catalyst Sions into acceptable emissions. Certain unacceptable emis requires oxygen to complete the catalytic reaction, Supple Sions in the exhaust Stream, including unburned hydrocar 50 mental air must be blown over the catalyst. Even when using bons and carbon monoxide, require an oxidation reaction to a Secondary air flow to overcome oxygen deficiency, the destroy them So that they end up as the corresponding Secondary air flow must be closely controlled to avoid an oxides, e.g., water and carbon dioxide. On the other hand, excess of oxygen, in which case the catalytic converter is NO requires a reduction reaction to develop N2 and O. In less effective in reducing NO. However, it should be noted fact, the O product of this reduction contributes to the 55 that NO contributes a very small portion of unacceptable oxidation of the HC and CO in the exhaust. emissions when an engine is cold; most of the cold Start TWC catalysts are currently formulated and designed to emissions that must be dealt with comprise HC, CO and the be effective over a specific operating range of both lean and like.

rich fuel/air conditions and a specific operating temperature An alternative to battery powered electrical heating has range. These particular catalyst compositions enable opti 60 been to decrease the Strain on the power Supply by Supplying mization of the conversion of HC, CO, and NO. This the power directly from an alternator rather than directly purification of the exhaust Stream by the catalytic converter from the vehicle battery. An alternator powered, electrically is dependent on the temperature of the exhaust gas and the heated catalyst (“APEHC”) still requires a 5 to 10% increase catalytic converter works optimally at an elevated in battery capacity to cope with the EHC Start-up Scenario. temperature, generally at or above about 300° C. Light-off 65 Even with the APEHC system, there is still a concern with temperature is generally defined as the temperature at which respect to battery capacity because electric heating is needed fifty percent (50%) of the emissions from the engine are for an extended period of time, i.e., more than 25-30

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Seconds. In addition, the maximum alternator power output Storage vessel and a bubble detector disposed adjacent the required in the APEHC System requires a complicated upwardly sloping passage to detect the production of gases Switching mechanism and an altered alternator Speed by the electrolyzer. It is also preferred that the system between 2,000 and 4,500 rpm during the heating up time include a check valve disposed in fluid communication period, and the alternator must be oversized. between the cathode and the hydrogen Storage vessel to The multi-chamber configurations of catalytic converters prevent backflow from the hydrogen Storage vessel to the generally conform to one or two theories. In one multi cathode.

chamber configuration, a Small portion of catalyst known as The water reservoir, Such as a dedicated reservoir, a a “starter catalyst” is positioned upstream from the primary windshield wiper fluid reservoir or a hydrogen Storage catalyst. This “starter catalyst” is generally closer to the vessel, may communicate with the anode through an anode exhaust manifold. This location, in conjunction with a flowfield and/or through the proton exchange membrane. Smaller thermal mass associated with its Smaller size and The Source of electrical current may comprise a battery or an materials of construction, causes the catalyst to heat much alternator. The hydrogen Storage vessel preferably includes more quickly than a single catalyst. This configuration, a pressure and a water recycle line communicating water however, is generally unacceptable because the Starter cata 15 from the hydrogen Storage vessel to the water reservoir. lyst in the exhaust Stream creates a higher back pressure The invention also provides an automobile, comprising an which reduces the Overall engine efficiency and robs the internal combustion engine having an exhaust System; a engine of power output. catalytic converter disposed within the exhaust System; an Another method of providing multiple chambers in the electrolyzer having an anode in fluid communication with a exhaust flow includes a first catalyst having low temperature water reservoir, a cathode, and a proton exchange membrane characteristics used only during cold Start conditions, and, disposed between the anode and the cathode; a Source of after the catalyst temperature rises to a certain elevated level, electrical current having a positive terminal coupled to the the exhaust gas flow is Switched to pass through the con anode and a negative terminal coupled to the cathode; and a ventional catalytic converter configuration. A variation of 25 preSSure vessel in communication with the cathode. The this approach is to run all cold Start emissions through a automobile will preferably further comprise a controller in Separate absorber (Such as a Zeolite or a metal sieve-type electronic communication with the Source of electrical Substance) where unacceptable emissions are captured and current, a Source of oxygen gas in communication with the later released back into the exhaust Stream. This method, catalytic converter and a flow control member disposed however, is impractical because of the complicated Switch between the preSSure vessel and the catalytic converter for ing mechanism used to divert flow to the absorber, the size delivering a cathode product to the catalytic converter. and Space requirements of the absorber, and the impracti Wherein the flow control member provides pulsed flow of cality of releasing the unacceptable emissions from the the cathode product. In one embodiment, the automobile absorber back into the exhaust stream. will include an ignition System in electronic communication Finally, one additional method for reducing cold Start 35 with the internal combustion engine and the flow control emissions runs the engine excessively rich in the cold Start member.

condition and ignite the resulting Super-rich mixture to The invention further provides a method of monitoring directly heat the catalyst. This approach has proved wholly the performance of an electrolyzer, comprising the Step of unreliable and has other Serious drawbacks, including detecting gas bubbles passing through an electrolyzer outlet reduced engine and catalyst life. 40 passage or channel.

To date, there has not been a catalytic converter heating The invention also provides an apparatus for pulsed System which gives almost instantaneous heating of the delivery of hydrogen from a preSSurized hydrogen Source to catalytic converter without the inherent drawbackS Stated a Vehicle exhaust System, comprising a gas passageway above. Thus, there remains a need for an improved catalytic communicating between the hydrogen Source and the converter System that reduces ineffective catalytic action 45 exhaust System; first and Second isolation Valves disposed in immediately after cold Start-up of an engine. Such a System the gas passageway, the Second Valve being downstream must be simple and must not reduce the rated lifetime of the from the first valve; and a region between the first and engine, the catalytic converter, or the battery components of Second isolation valves having a defined volume. the vehicle. Alternatively, the invention provides an apparatus for pulsed 50 delivery of hydrogen from a preSSurized hydrogen Source to

SUMMARY OF THE INVENTION a vehicle exhaust System, comprising a turnstile Valve dis The present invention provides an on-board System for the posed in a conduit between the hydrogen Source and the generation of hydrogen, comprising an electrolyzer having exhaust an anode in communication with a water reservoir, a An electrolyzer is also provided, the electrolyzer com cathode, and a proton eXchange membrane disposed 55 prising a first electrode compartment comprising Substan between the anode and the cathode; a Source of electrical tially incompressible components, a Second electrode com current having a positive terminal coupled to the anode and partment comprising a compressible member; and a flexible a negative terminal coupled to the cathode; and a controller membrane disposed between the first and Second electrode in electronic communication with the Source of electrical compartments. This electrolyzer is particularly advanta current. The System may also comprise a hydrogen Storage 60 geous where the first electrode compartment operates at a vessel having an inlet in communication with the cathode lower preSSure than the Second electrode compartment. This and an outlet in communication with a catalytic converter. differential preSSure may occur where the first electrode is an Preferably, the cathode comprises a cathode flowfield and anode and the Second electrode is a cathode. In one cathode product outlet communicating with an upper portion embodiment, the Substantially incompressible components of the cathode flowfield. In one embodiment, an upwardly 65 include an anode flowfield and a porous anodic electrocata sloping passage may be incorporated to provide communi lyst Substrate. Particularly, the anode compartment may cation between the cathode product outlet and the hydrogen comprises a flattened expanded metal flowfield and the

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S 6 cathode compartment may comprise a non-flattened FIG. 4 is a croSS-Sectional Side view of a catalytic expanded metal flowfield. Furthermore, the anode flowfield converter monolith Showing air and hydrogen flow in the and porous anodic electrocatalyst may be molded into a cell axial direction.

frame. The electrolyzer is beneficial for assuring that the FIG. 5 is a cross-sectional front view of the catalytic proton eXchange membrane does not deform under fluid converter monolith in FIG. 4; preSSure forcing the proton exchange membrane against the rigid, porous electrocatalyst Substrate. FIGS. 6(A-D) are graphs of the catalyst temperature Another aspect of the invention provides a hydrogen in measured at axial positions within the monolith as indicated delivery System of the vehicle comprising a controller for FIG. 4.

controlling the performance of the System. The controller 1O FIGS. 7(A-D) are graphs of the catalyst temperature Sends the command Signals to cause the System to release measured at radial positions within the monolith as indicated hydrogen and provide oxygen to the vehicle's exhaust in FIG. 5.

System or catalytic converter. FIG. 8 is a schematic diagram of a system for the The controller Sends a command to a valve or System of combustion of hydrogen in an internal combustion engine. valves in the delivery system to open the valve or valves. 15 FIG. 9 is a Schematic diagram of a System having oxygen This command may be a Sequence of commands or signals recovery and Storage equipment and means for injecting that cause the valves to cycle in Such a way as to deliver oxygen into the catalytic converter.

hydrogen according to one of Several delivery modes. The FIGS. 10(a-b) are graphs of the catalyst temperature at modes may be time, Volume, or converter temperature various axial and radial distances in the catalyst monolith dependent. Further, the modes may include a continuous over a period of 50 Seconds using a pulsed release of delivery, packetized delivery, pulsed delivery or continu ously varying delivery of hydrogen. hydrogen into an air Stream. The hydrogen delivery System may have Sensors placed in FIG. 11 is a Schematic diagram of an electrolyzer having appropriate parts of the System for Sensing various param dummy cells for heating or cooling the electrolyzer using eters of the System and Sending Signals to the controller 25 liquid from a vehicle radiator.

indicating the value of these parameters. If the parameters FIGS. 12(a-b) are catalyst monoliths having hydrogen fall within a certain window, then the System is working injection distributors.

properly. Otherwise, Some error may have occurred in the FIG. 13 is a Schematic diagram of a catalytic converter System, and an appropriate response may have to be having isolation valves allowing hydrogen or oxygen to executed, which may just present a warning indicator, or diffuse evenly throughout the monolith before delivery of may actually shut down the System. another gas to provide a combustible mixture. The vehicle may generate one or more trigger signals to FIGS. 14 (a-e) are schematic diagrams of alternative the controller to instruct the controller to cause the release of electrical systems for providing electrical power to the hydrogen. Additional Signals, Such as temperature Sensors, electrolyzer.

may instruct the System to Slow or Stop the release of 35 FIG. 15 is a flowsheet showing the modes of operation for hydrogen. an ideal chemically heated catalyst (CHC) system. The controller also sends the command to the hydrogen FIG. 16 is a block diagram of a control system for a generating part, or electrolyzer, of the System to turn on hydrogen hydrogen generation. A signal from the hydrogen Storage invention. production and delivery System of the present vessel that the vessel is full may prompt the controller to turn 40 the hydrogen generator off. Additional Signals, Such as low FIG. 17 is a flow chart for the main procedure for a battery Voltage or high power demand on the engine, may invention. System and on-board-diagnostics for the present controller temporarily Signal the System to Stop electrolyzing.

Examples would be to slow or Stop generation when the FIG. 18 is a flow chart for the process that the control vehicle is at idle with the air conditioner turned on, or when 45 System goes through while it is waiting for ignition of the the vehicle is passing or accelerating. Likewise, the System vehicle.

could be designed to increase the hydrogen production rate FIG. 19 is a flow chart showing the process that the to take advantage of vehicle energy when coasting or the System goes through to determine if hydrogen is to be like. released in response to a key trigger release or a post key 50 trigger release.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the features and advantages of the present inven System FIG. 20 is a flow chart showing the process that the tion can be understood in detail, a more particular descrip goes through while it waits for a crank trigger Signal. tion of the invention, briefly summarized above, may be had FIG. 21 is a flow chart showing the process that the by reference to the embodiments thereof which are illus 55 System goes through to determine if hydrogen is to be trated in the appended drawings. It is to be noted, however, released in response to a crank trigger release or a post crank that the appended drawings illustrate only typical embodi trigger release.

ments of this invention and are therefore not to be consid FIG.22 is a flow chart showing the process by which the ered limiting of its Scope, for the invention may admit to System produces hydrogen through electrolysis. other equally effective embodiments. 60 FIG. 23 is a flow chart showing the procedure that the FIG. 1 is a Schematic diagram of a hydrogen production System goes through to check whether any error flags are Set. and delivery System of the present invention for heating a FIG. 24 is a flow chart showing the procedure that the catalytic converter. System goes through in a check for a hydrogen leak from the FIG. 2 is an exploded view of a preferred electrolyzer that System.

may be employed in the present invention. 65 FIG. 25 is a flow chart showing the procedure that the FIG. 3 is a Schematic of an alternate hydrogen Storage System goes through to release hydrogen to the vehicle's System of the present invention. exhaust System.

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FIG. 26 is a flow chart showing the procedure that the oxygen gas bubbles generated in the anode to rise out of the System goes through to check certain parameters of the electrolyzer and into the water reservoir and/or oxygen/ System prior to producing hydrogen. water Separator. The water reservoir preferably also Serves FIG. 27 is a flow chart showing the procedure that the as an oxygen/water Separator wherein the Oxygen may be System goes through to maintain the power to the Stack of released or Stored and the water may be recycled to the cells within the electrolyzer. anode. By disposing the water reservoir inlet above the FIG. 28 is a flow chart showing the procedure that the anode flowfield or manifold outlet and providing a flow line System goes through to monitor certain parameters during that has a Substantially continuous upward Slope, the natural the production of hydrogen. buoyancy of the gas bubbles lifts water from the anode and FIG. 29 is a flow chart showing the procedure that the causes a natural circulation of water into and out of the System goes through to shut down the electrolyzer and both anode. This arrangement may eliminate the need for a water oxygen and hydrogen delivery equipment. pump, yet provides for water delivery and cooling to the FIG. 30 is a flow chart showing the procedure that the anode and cathode.

System goes through to release hydrogen in timed packets 15 In a further aspect of the invention, the flow line between for a specified time period. the anode flowfield outlet and the water reservoir inlet is FIG. 31 is a flow chart showing the procedure that the equipped with a bubble detector which indicates that there is System goes through to release hydrogen in timed pulses for sufficient water being Supplied to the anode. The bubble a specified time period. detector may be used alone or in combination with other FIG. 32 is a flow chart showing the procedure that the Sensors to verify proper production, collection, delivery and System goes through to release hydrogen in timed packets integrity of the System or its components. A Similar bubble for a specified Volume of hydrogen. detector could be placed between the cathode flowfield and FIG. 33 is a flow chart showing the procedure that the the hydrogen Storage tank.

System goes through to release hydrogen in timed pulses for Another aspect of the invention provides for water level a specified Volume of hydrogen. 25 management in the System to avoid hydrogen leaks. The hydrogen Storage

FIG. 34 is a flow chart showing the procedure that the Sensor in order to maintain tank preferably includes a water level at least a minimum amount of

System goes through to Set the current delivered to the Stack water in the bottom of the vessel where various instruments of cells.

FIG. 35 is a flow chart showing the procedure that the and pipes interface with the vessel. Similarly, it is preferred System goes through to periodically update the parameters in that the anode and cathode manifolds be configured So that the electrolyzer is always full of water. The presence of the System. water assists in maintaining a Seal between adjacent com FIGS. 36 and 37 are schematic diagrams of two alternate ponents.

embodiments of the System of FIG. 1, wherein the water A further aspect of the invention provides a hydrogen recovery System in the vessel is eliminated.

35 delivery System designed to Supply pulses of hydrogen gas

DETAILED DESCRIPTION OF THE to the catalytic converter or any other desired component of PREFERRED EMBODIMENTS the automobile, Such as the engine. The hydrogen delivery The present invention provides a method and apparatus System comprises a pair of valves with a region therebe for chemically heating a catalyst bed by feeding hydrogen to tween having a known volume. The region is filled with the catalyst. The invention also provides a method and 40 hydrogen under pressure by opening the first hydrogen valve apparatus for thermally conditioning a catalyst in order to communicating with the hydrogen Storage vessel. The first enhance the conversion of unacceptable emissions Valve is then closed and the Second valve is opened to (emanating from an internal combustion engine) into water release the pressurized hydrogen into the catalytic converter, and other acceptable emissions. In one aspect of the exhaust manifold or engine, as desired. While the region invention, hydrogen is Supplied from an electrolyzer or other 45 may be of any useful Volume and configuration, a typical hydrogen Source and injected into the monolith of a catalytic automobile will preferably have a region Suitable to contain converter to more rapidly bring the catalyst to a light-off about 5 cubic centimeters (cc) at about 400 pounds per temperature. Square inch (psi), which is released as about 100 cc at about In another aspect of the invention, an apparatus is pro 1 atmosphere (atm). The invention also provides for a Vided for producing, Storing and delivering hydrogen to an 50 turnstile Valve as an alternative to the hydrogen delivery automotive catalytic converter. The apparatus is simple and system just described. It is believed that the turnstile valve compact and includes a minimal number of moving parts. may be more reliable. A third delivery design may consist of The apparatus includes a water Source, an electrolyzer, a flow a Solenoid value for on/off control in Series with a variable hydrogen Storage vessel, and a valve for controlled delivery restriction valve for flow control. of the hydrogen to the catalytic converter. The apparatus 55 Another aspect of the invention provides for a hydrogen preferably also includes an oxygen/water Separator in com flow path to be maintained under pressure to prevent the munication with the anode flowfield, a hydrogen/water infiltration of oxygen therein. While minute amounts of Separator in communication with the cathode flowfield, oxygen may enter the System or Small amounts of hydrogen and/or a check valve to prevent backflow of hydrogen from may leak out of the System, the invention maintains Safe the storage vessel to the cathode flowfield. It may also be 60 hydrogen and oxygen concentrations throughout the System. preferred to include an oxygen Source in communication The invention also provides for the use of a low carbon with the catalytic converter to facilitate the oxidation of containing alcohol, e.g., methanol, ethanol or propanol, in hydrogen. The electrolyzer must be electronically coupled to the water throughout the System in order to depress the a power Source and the electrolyzer may be operated in freezing point of the water. An alcohol, Such as methanol, various manners. 65 may be provided in any useful concentration, but preferably In yet another aspect of the invention, the electrolyzer and at an alcohol:Water molar ratio of between Zero and about water reservoir are provided in a relationship that allows the 1:1. The alcohol is carried with the water throughout the

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System and may be oxidized at the anode to carbon dioxide communication with one or more additional hydrogen Stor gas (CO), Six hydrogen ions (H), and Six electrons (e). age vessels 36. The use of more than one hydrogen Storage The hydrogen ions, or protons, and electrons are recombined vessel is not necessary to the operation of the invention, but at the cathode to form three molecules of molecular hydro may be desirable to provide Sufficient Storage capacity while gen (H2). making accommodation for Space limitations on board the The invention further provides an electrolytic cell and vehicle. The Storage vessel may be made from various method of making an electrolytic cell having a flowfield and materials, Such as aluminum, carbon Steel, StainleSS Steel or catalyst Substrate molded together within a common frame. hydrogen Storageplastic a noncorrosive vessel material. It is preferred that the 24 or combination of vessels 24.36

While typical cell components are merely held together have a total hydrogen Storage capacity that is Sufficient to under pressure between two end plates, a one piece, molded heat up the catalyst to a light off temperature at least one cell would enhance the performance and extend the life of an time. By Storing Such amount, the rate of hydrogen produc electrolytic cell in applications in which the cathode and tion from the electrolyzer can be reduced Substantially anode are operated at different preSSures, particularly at high below the rate of hydrogen consumption by the catalytic differential preSSures approaching 400 psi or more. converter during the Start up period. Furthermore, the elec The invention preferably includes a check valve between 15 trolyzer may be controlled to refill the storage vessel with the electrolyzer and the hydrogen Storage vessel. The check hydrogen at various times, preferably when the vehicle is Valve prevents the pressurized hydrogen in the vessel from operating efficiently.

flowing back into the electrolyzer, Specifically the cathode. The System preferably also includes a water recycle line Therefore, if the electrolyzer has any Small leaks, the elec with valves 38, 39 to capture and reuse most of the entrained trolyzer may depressurize down to atmospheric pressure water from the hydrogen exiting the electrolyzer 22, a check without a Substantial loSS of hydrogen. valve 40 to prevent back flow of hydrogen from the storage FIG. 1 is a schematic flow diagram of a system 10 of the vessel 24 into the electrolyzer 22, and a pressure relief valve present invention installed on a vehicle to deliver hydrogen 42 to protect the System against over pressurization. Because to the exhaust System. The vehicle includes a catalytic 25 the Storage vessel 24 may be designed to operate at a much converter 12 located in an exhaust line 14 from a vehicle's higher pressure than the water reservoir 20 or the Supply line exhaust manifold, as shown. The exhaust line 14 is provided 32, the mere opening of the recycle valve 38 causes water to with hydrogen from a hydrogen inlet line 16 and, preferably, flow out of the vessel 24. Valves 38 and 39 are alternately air from an air pump 18. The air pump could be any Suitable cycled to allow Small, well controlled amounts of water out air Source for injecting air into the exhaust line at Suitable of the cathode reservoir. As valve 38 opens, water flows into preSSure and Volumetric flow rate to achieve any desired the tubing between the valves and compresses the headspace air/hydrogen ratio mixture. The air pump may be replaced in the vertical stub 41. Valve 38 closes and valve 39 opens by a Venturi wherein the pressurized hydrogen gas provides allowing the compressed hydrogen in the Stub 41 to push the a motive force Sufficient to draw in ambient air. captured water into the anode reservoir. The recycle Valves The system 10 includes a water reservoir 20, an electro 35 38 and 39 are preferably controlled to maintain the water lyZer 22, a hydrogen Storage vessel 24 and a hydrogen level in the vessel 24. A preferred water level will be high delivery system 25. The electrolyzer 22 may preferably enough to cover most or all of the pipe and instrument comprise a plurality of Stacked identical cells 26 between couplings along the bottom of the vessel yet not So high that end plates 28. The water reservoir 20 preferably serves not the hydrogen Storage capacity of the vessel is wasted. only as a water Storage chamber but also as a separator for 40 FIGS. 36 and 37 are schematic diagrams of two alternate oxygen gas and water and means of dissipating heat. The embodiments of the system of FIG. 1, wherein the water reservoir 20 may be a vehicle's windshield washer fluid recovery system in the vessel 24 is eliminated. Both alter Storage container, but is preferably a dedicated reservoir/ nate Systems 220, 240 utilize a proton exchange membrane Separator, optionally allowing collection and Storage of with the cell 22 which, when operated at sufficiently low oxygen via port 30. Water flows by gravity drain or is 45 current density, will provide the necessary reaction water to pumped from the reservoir 20 to the anodes of the electro the anode when that water is provided at the cathode. The lyZer 22 via a Supply line 32. AS the anodes produce oxygen system 220 of FIG. 36 includes a pressurized cathode and entrained water rises naturally back to the reservoir 20 (hydrogen) reservoir 222 with means 224 for releasing the via a return line 34. preSSure and refilling the reservoir with water. Alternatively, A bubble detector 37 is preferably disposed adjacent or 50 the reservoir 222 could be filled using pressurized water, around the return line 34 in order to Sense the passage of gas which would allow manufacturing control over filling if the bubbles therein. A suitable type of bubble detector is an System requires Specialized equipment. optical transmission type detector. The electronic Signal To eliminate the complexity and Safety issues involved, from the bubble detector 37 is preferably transmitted to a the system 240 shown in FIG. 37 uses an anode reservoir controller 134 and the Signal indicates that at least certain 55 242 and a cathode reservoir 244. This system 240 still aspects of the electrolyzer 22 are operating properly. utilizes osmotic movement of the water from the cathode to Conversely, if the Signal indicates the absence of gas bubbles the anode in normal operating mode but new water is in the return line 34, then the electrolyzer 22 may have a provided at the anode (at ambient pressure) and this water is problem, Such as a ruptured proton eXchange membrane transferred to the cathode Via electroosmosis during the (PEM), depleted or blocked water supply, etc. Furthermore, 60 initial operation of the electrolyzer 22 after filling the anode the controller 134 receiving the signal from the bubble reservoir 242. Once all the anode water is depleted, elec detector 37 may analyze the number of gas bubbles passing troosmosis between the reservoirs 242,244 ceases and, once through the line 34 over a period of time as Some indication again, all process water is provided through the cathode. of the electrolyzer's operating efficiency. Referring back to FIG. 1, the hydrogen is delivered out of The hydrogen produced at the cathodes of the electrolyzer 65 the Storage vessel 24, preferably through a Standpipe 44, or 22 is delivered under pressure to a hydrogen Storage System from the top of the vessel 44 or 36 in accordance with the 23 comprising a hydrogen Storage vessel 24 alone or in operation of a hydrogen delivery System 25. The hydrogen

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delivery system 25 determines the manner in which the vessel 24. The hydrogen Storage vessel 24 is preferably hydrogen is introduced into the catalytic converter and may equipped with a water level Sensor 146, most preferably a be as Simple as a single Solenoid valve. While hydrogen may Sensor without any moving parts Such as an optical Sensor. be introduced through various valves or orifice plates as a When the water level is too high, the water outlet valve 38 slow, continuous stream, it has been found (as described in is opened so that the pressure in the vessel 24 will drive relation to FIG. 10) that introduction of hydrogen pulses or water out of the vessel into the reservoir 20 or supply line 32. packets to the catalytic converter provides Similar heating, When the water level is within an acceptable range, the yet requires less hydrogen. One preferred delivery System 25 Valve 38 is closed. Again, it is preferred to maintain a for providing hydrogen pulses or packets comprises a first sufficient level of water in the vessel 24 in order to provide hydrogen valve 46, a Second hydrogen valve 48 and a central 1O additional protection against hydrogen leaks. Other various region 50 disposed between the first and second valves 46,48 control Schemes and considerations may be employed as having a defined volume. The central region 50 is filled with will be readily recognized by those with skill in the art which preSSurized hydrogen from the Storage vessel 24, 36 by are within the Scope of the present invention. For example, opening the first hydrogen valve 46 communicating with the the microprocessor may also be programmed to carry out hydrogen storage vessel 24, 36. The first hydrogen valve 46 15 timed control functions apart from responding to Sensory is then closed and the Second hydrogen Valve 48 is opened inputs, and may also serve various Safety functions. to release the pressurized hydrogen from the central region 50 into the catalytic converter 12, exhaust manifold 14 or thatFIG. 2 is an exploded view of a preferred electrolyzer 22 may be employed in the present invention. In the engine, as desired. While the region 50 may be of any useful following description of the electrolyzer 22, the materials of Volume and configuration, a typical automobile will prefer ably have a region Suitable to contain about 5 cubic centi construction referred to as "preferred” are the materials meters (cc) at about 400 pounds per Square inch (psi), which actually used in a test device to prove that the invention is released as about 100 cc at about 1 atmosphere (atm). would work for its intended purpose. In commercial pro Alternatively, the hydrogen delivery System 25 may com duction models of the present invention, where possible, leSS prise a turnstile valve. It is believed that the turnstile valve expensive materials may be used throughout, Such as carbon may be more reliable over a period of extended use. 25 Steel replacing titanium where possible, and plastics, Such as The ignition switch 132 is preferably electronically polypropylene, where heat and StreSS will permit the use of coupled to a controller 134 which controls the operation of Such materials.

the hydrogen valves 46, 48 of the hydrogen delivery system The electrolyzer 22 may be referred to herein as a proton 25. In one preferred method of operation, the hydrogen exchange membrane (PEM) electrolyzer. The proton valves 46, 48 provide pulses of hydrogen to the manifold 14 eXchange membrane 72 may itself prove corrosive in this until the temperature Sensor 136 reads a temperature equal environment in contact with certain Substances, thus requir to or greater than the light-off temperature. The temperature ing the careful Selection of the material of construction of the Sensor provides feedback to the controller So that adjust electrolyzer. For example, the PEM 72 should only come in ments in the manner of operating the hydrogen valves 46, 48 contact with carbon, graphite, valve metals (Such as titanium can be made. It should be recognized that any number of 35 or tantalum), noble metals (Such as platinum or palladium) temperature Sensors could be used and that the controller or gold. However, those of skill in the art will readily may take account of any number of conditions in determin recognize where less exotic materials than those listed in the ing the appropriate operation of the valves 46, 48, or other following discussion that are located away from the PEM hydrogen delivery Systems 25 Such as a rotary valve. It is material itself and the oxygen electrode catalyst can be anticipated that refinements in the hydrogen delivery may 40 readily employed without penalty. For example, graphite include pulses of varying frequency and/or Volume over will be the material of choice in certain Structural elements, time to compensate for increasing catalytic converter tem and not Some obvious candidates Such as copper, aluminum, perature or decreasing pressure in the hydrogen Storage or iron, which can corrode thus forming ions that can poison reservoir. the anode and/or cathode electrocatalysts. The electrolyzer 22 receives power from a source 138. It 45 The electrolyzer 22 includes an anodic electrocatalyst is preferred that the electrolyzer produce hydrogen when the Substrate and/or current collector 70 and a flattened hydrogen pressure in or near the hydrogen Storage vessel 24, “expanded' titanium flow field 68 held within an anodic cell as indicated by preSSure Sensor 144, falls below a setpoint frame 66 made of polychlorotrifluoroethylene (PCTFE) pressure between about 100 psig and about 400 psig. It sheet (such as KEL-F available from the 3M Company, St. should be recognized that the power to the electrolyzer 22 50 Paul, Minn.). The preferred anode substrate and/or current should be turned off when the pressure exceeds a high collector is a thin Sheet of porous titanium made by Sintering preSSure setpoint, Such as 400 psig. It should also be Small diameter titanium spheres and is available from recognized that many other conditions may be considered in AstroMet, Cincinnati, Ohio. A more preferred anode sub controlling the electrolyzer 22, Such as Signals from the Strate and/or current collector is a thin sheet of porous engine management unit, the length of time that the vehicle 55 titanium made by Sintering Small diameter titanium fibers has been running, the characteristics of the power Supply and and is available from Porous Metal Products, Jacksboro, the volume of the storage vessel. The other conditions TeX.

mentioned may be relevant to the efficient operation of the The electrolyzer 22 further includes a cathode substrate vehicle and the timely replenishment of the hydrogen Supply and/or current collector 76 and an expanded Stainless Steel for use during the next cold start. However, in order for the 60 flow field 78 retained in a cathodic cell frame 80 formed of System to account for multiple conditions, it is preferred that polysulfone. The preferred cathode Substrate and/or current the System communicate with a microprocessor controller collector is a carbon paper consisting of pressed carbon 134, whether the controller is dedicated to the system 10 or fibers or a carbon cloth made from a weave having a provided as part of the vehicle (Such as the engine manage cathodic electrocatalyst layer on one Side containing poly ment controller.) or Some combination of controllers. 65 tetrafluoroethylene (PTFE)-bonded high surface area colloi The microprocessor controller 134 may also be used to dal platinum or palladium, Supported on carbon black or monitor and control the water level in hydrogen Storage preferably an electrolessly deposited or electroplated thin

Page 35

film of platinum or palladium, most preferably having a distilled/deionized water for 24 hours. The product is then platinum or palladium loading of at least 0.1 mg/cm. isolated using vacuum filtration, washed with copious Alternatively, the cathode may be constructed using a Semi amounts of deionized water, and dried in a heated vacuum compressible Stainless Steel felt, Suitably Supported, having OWC.

high porosity and Sufficient catalytic activity. To ensure that Surface atoms of platinum and ruthenium The various components of the PEM electrolyzer are in the Pt-RuO crystallites are activated completely, the Stacked together and retained with a plurality of tie rods 82, catalyst is Subjected to a heated reduction Step. The catalyst preferably 16 Such tie rods. StainleSS Steel tubes, Such as is placed into a cool ceramic heating tube which is housed SS316, are then screwed into four threaded ports on one of in a muffle furnace and equipped for the external Supply of the titanium end plates. The ports are the anode water inlet gaseous reactant. Initially, argon is allowed to flow for one port 56, the anode water/oxygen outlet port 58, and a pair of hour in the tube to remove potential oxidizing species from cathode hydrogen/water outlet ports 84. To minimize elec the ceramic. Hydrogen is then introduced into the ceramic trical contact resistance between components, the titanium tube and the temperature of the furnace/ceramic tube is end plates 60 and 62 and the expanded titanium metal increased slowly to 200 C. This environment is maintained current collectors 68 and 78 may be electroplated with a thin 15 for six hours. The resulting catalyst is a very fine powder film of gold or noble metals, Such as platinum. which displayS catalytic activity toward methanol oxidation The cathode and the anode of the electrolyzer are of in the presence of air.

Special construction. The cathodic electrode Structure for An even more preferred anodic electrocatalyst consists of hydrogen evolution may be fashioned from a commercially a homogenous mixture of high Surface area iridium and available fuel cell gas diffusion layer on a carbon cloth ruthenium oxides with either high Surface area platinum backing (such as ELAT available from E-TEK, Inc., Natick, ruthenium metal alloy powder or high Surface area Mass.), which acts as a Support for the active hydrophilic Pt-RuO. In each case, the mole ratio of iridium and electrocatalyst layer. This active layer contains high Surface ruthenium oxides to platinum-ruthenium metal alloy or to area colloidal platinum (about 100 m/g), Supported on Pt-RuO should preferably be 1:1.

carbon black (between about 10 and about 50 wt % Pt on C), 25 The anodic eletrocatalysts described above are applied to yielding a platinum loading of at least about 0.1 mg/cm. one side of a proton exchange membrane in the form of a The cathodic electrode Structure may be hot-pressed onto catalyst ink that is prepared using the following procedure. one Side of a Segment of a precleaned PEM material. The catalyst is first dispersed into distilled water using a Hot-pressing of the cathodic electrode and PEM is prefer water:catalyst ratio of approximately 1:1 by weight. The ably carried out between the plates of a hot-press elevated to mixture is then Sealed into an appropriate container to about 200 C. for about 60 seconds, and using a force of prevent Solvent evaporation and agitated using high energy about 15,000 pounds. Sonication for one hour or more until complete dispersion is One Suitable anodic electrocatalyst layer contains mixed achieved. Following dispersion and wetting of the catalyst, iridium and ruthenium dioxides at a molar ratio of about 1:1. a quantity of commercially-available, dissolved ionomer, The layer is prepared by dissolving iridium and ruthenium 35 Solution, Such as the 5 wt % Nafion(E) Solution available from chlorides in about 8 ml of concentrated HCl and heating the Solution Technologies, Mendenhall, Pa., is added to the mixture to almost dryneSS. The resulting chlorides are then dispersion Such that the final concentration of ionomer is dissolved in isopropanol to make an ink-line coating. A approximately 15 wt %.

porous titanium plate (such as a 0.05" thick plate available This mixture is resealed into a container to minimize from Astro Met of Cincinnati, Ohio) is etched in 12% HBF 40 evaporation and Subjected to high energy Sonication until a for about 60 seconds and rinsed with isopropanol. This homogenous, well-dispersed catalyst ink is achieved. The Substrate is then coated with the ink-like mixture and the ink is applied directly to the Surface of a dry membrane as solvent evaporated under low heat of about 90° C. This a Single layer or as a multilayer coating using a brush coating and drying procedure is repeated Several times, then technique. For multilayer coatings, the Solvent of the pre the electrode is heated in a furnace at 400° C. for 10 minutes 45 viously applied layer is evaporated to dryneSS prior to the in ambient air. The coating, drying, and furnace treatment is application of the next coat. The procedure could be modi repeated twice more, but with a final baking time of two fied to make use of other coating application techniques Such hours instead of 10 minutes. A preferred anodic electrocata as air Spraying or Spin coating which are more amenable to lyst consists of high Surface area platinum-ruthenium metal mass production.

alloy powder having an atomic ration of 1:1, platinum:ru 50 After the catalyst ink has been applied Successfully to one thenium and which is available from E-TEK, Inc., Natick, side of the membrane the membrane and electrode (M&E) Mass. A more preferred anodic electrocatalyst consists of assembly is Subjected to a hot press Step. In this step, the high Surface area platinum-ruthenium oxide (Pt-RuO) electrodes and membranes are fused under elevated tem powder having an atomic ratio of 1:1, platinum:ruthenium. perature and pressure in a hydraulic press equipped with The synthesis of the Pt-RuO electrocatalyst employs 55 resistively-heated platens. To press the M&E, a “press anhydrous chloride Salts of platinum and ruthenium. Quan package' is created which consists of the M&E and various tities of the two salts are utilized Such that the Pt-Ru atomic insulative and Support layers to facilitate the release of the ratio is 1:1. The Salts are ground together with NaNO using M&E from the package after the press Step. In this package, a mortar and pestle until a homogenous powder is obtained. the M&E assembly is sandwiched typically between two The resulting mixture is then deposited in a crucible, placed 60 thin Teflon sheets to protect the electrode Surface(s), and this into a 500 C. oven, and fired in ambient atmosphere for 10 Sandwich is placed between two thin, flat metal plates that minutes. After heating, the crucible is removed from the provide Support and heat transfer between the platens and oven and allowed to cool to room temperature. Ashiny black the M&E during the press step. The complete M&E, Teflon, crystalline solid is observed in the crucible which consists of and metal plate preSS package is positioned quickly between the desired Pt-RuO product dispersed in a salt matrix. To 65 the two preheated platens (ca. 150 to 200° C), and pressure dissolve the salt and liberate the insoluble catalyst product (1000 to 1500 psi) is applied to the package for 60 to 120 from the matrix, the crucible is placed into a beaker of seconds to finish the M&E fabrication process.

Page 36

For the longest component lifetime it is important to The hydrogen storage system 25 of FIG. 3 is designed for prevent the movement of internal electrolyzer components relatively short term operation. The system 25 may be as the cathode (hydrogen) pressure is changed. This is designed for longer term operations, for example 100,000 accomplished by Selecting an anode flowfield and a porous miles or more, utilizing other methods of water removal electrocatalyst Substrate that are noncompressible and known in the art. A Satisfactory metal hydride hydrogen Selecting cathode components which provide Sufficient elas Storage unit is available from Hydrogen Consultants of ticity such that the PEM is pressed firmly against the anode Littleton, Colo. Such an available unit can store 30 liters of regardless of the cathode pressure. hydrogen which can be delivered at 30-45 psig, with In the preferred structure the anode flowfield consists of recharging using hydrogen gas at 100-200 psig. Still, the flattened “expanded” metal and the cathode flowfield most preferred hydrogen Storage means is a pressure vessel, includes at least one piece of non-flattened (as expanded) Such as vessel 24 of FIG. 1, made of a composite Structure, metal to provide compression. involving the use of aluminum or ferrous-based alloys. A An alternative flow field would be perforated corrugated Suitable hydrogen Storage vessel of this type is available Steel. The corrugates could be designed to provide more 15 from Harless Specialties of Irwin, Pa. rigidity on the low pressure Side and more elasticity and FIG. 4 is a simplified cross-sectional view of a catalytic resiliency on the high pressure Side of the membrane. converter monolith Showing air and hydrogen flow in the In mass production, where components Such as the cell axial direction through the monolith 13. The temperature of frames are molded, the anode flowfield components could be the monolith is measured with a thermocouple at points molded into the cell frame. This would increase the rigidneSS 31(a)-(e) along the central axis, with point 31(a) being on of the noncompressible Side as well as Simplify assembly. the front face where the gases first contact the catalyst and the other points 31(b)-(e) located at positions Successively

FIG. 3 is an alternative hydrogen storage system 25 which further utilizes a metal hydride type storage vessel 52. Prior to measurements into the monolith. The results of these temperature operation, the System 25 of FIG. 3 permits purging all air rate containing at3%, 40 liters per minute (lpm) total gas flow 5%, 8.5% and 17% hydrogen is shown from the System with an inert gas, Such as nitrogen, by 25 in FIGS. 6(a)-(d). FIGS. 6(a)-(d) are graphs of the catalyst attaching a nitrogen gas feed line at a purge gas inlet 54 temperature measured at axial positions within the monolith downstream of the check valve 40. During the purging as indicated in FIG. 4.

operation, the metal hydride vessel 52 is detached at a quick disconnect 86. This operation effectively seals both the Now referring to FIG. 5, a simplified cross-sectional view vessel 52 and a gas line 88, to keep the purge gas out of the of the catalytic converter monolith 13 of FIG. 4 is presented. vessel 52. The remainder of the system 25 is then purged The temperature of the monolith 13 is measured with a from the purge gas inlet 54 through a back pressure regulator thermocouple at points 33(a)-(c) along the monolith radius, 90. with point 33(c) being in the center of the monolith and the other points 31(b) and (a) located at greater distances from

To charge the system 25 with hydrogen, a needle valve 92 the center. The results of these temperature measurements at between the Storage vessel 52 and the back pressure regu 35 40 liters per minute (lpm) total gas flow rate containing 3%, lator 90 is shut. Hydrogen gas generated by the electrolyzer

(See FIG. 1) is preferably processed through a four-stage 5%, 8.5% and 17% hydrogen is shown in FIGS. 7(a)-(d). process to remove entrained water (liquid or vapor) and any FIGS. 7(a)-(d) are graphs of the catalyst temperature mea oxygen contaminant from the hydrogen Stream before Stor Sured at radial positions within the monolith as indicated in

age in the vessel 52. The first step involves removal of a 40

Small amount of entrained liquid water coming from the The face of the monolith should be noted as the beginning electrolyzer in the hydrogen gas. The entrained liquid water of the active catalyst Sites, not the physical front of the brick. is removed without a pressure loSS by means of the entrained Using this definition, the face will move as the catalyst ages. liquid water trap 94. The second step involves cooling the It has been found that the introduction of a relatively small hydrogen gas Stream from the electrolyzer temperature to 45 percentage of hydrogen in an air Stream within a typical ambient in a condensing coil 96. The electrolyzer typically automobile exhaust System provides nearly Spontaneous operates at between about 20 and about 60° C. above heating of a major portion of a face 35 (see FIG. 4) of the ambient, with the exact temperature depending on Specific catalyst material almost immediately following ignition in electrolyzer operating conditions. This Second Step con the internal combustion engine providing the exhaust gas. denses a Substantial portion of the water vapor in the 50 This heating along the face 35 of the converter is fortuitous hydrogen gas Stream. This condensed water could absorb a because it has been found that the most effective site for Significant amount of alcohol, which may be present during providing local heating is along and near the upstream face operation using windshield washer fluid as the electrolyzer 35 of the catalyst monolith 13. In fact, where the monolith reactant feed. The condensate is collected in a condensate 13 is made of a material that heats slowly when used in collector 98 and removed through the drain valve 38. 55 asSociation with the present invention, the face 35 may At this point, the hydrogen gas Stream is Still Saturated comprise a more reactive catalytic material to bring the with water vapor, but now at a lower temperature. This entire catalytic converter to light-off more quickly. In Saturated gas Stream is next passed into a Zeolite addition, the heat Supplied by the Spontaneous combination filledabsorbs water. This drier absorbs water vapor and any of hydrogen with oxygen or air in the presence of the alcohol vapor present when using a windshield washer fluid 60 catalyst monolith 13 produces only a Small quantity of water feed. Any oxygen contaminant present in the hydrogen gas as a product of the reaction, which does not degrade the Stream is then eliminated in a catalytic recombiner or performance of the catalytic converter.

oxygen eliminator 102 to reduce it to water. Final clean-up The air flow rate through the monolith 13, depending on of the hydrogen gas Stream is accomplished in a Second engine size and tuning parameters, typically falls in the Zeolite absorber bed in a polishing drier 104. The polishing 65 range between about 40 and about 400 liters per minute drier removes traces of water produced by the catalytic (lpm). The ideal range is between 80 and 300 lpm, depend recombiner 102. ing on engine size. Effective concentrations of hydrogen for

Page 37

these flow rates are between about 1 and about 28 volume Another aspect of the invention provides oxygen recovery percent, with a preferred range between about 5 and about from the electrolyzer. FIG. 9 is a schematic diagram of a 18 Volume percent. The most preferred range of hydrogen System 140 providing equipment for oxygen recovery, Stor concentration, again depending on engine size, is between age and injection into the catalytic converter. The oxygen about 8 and about 15 volume percent. For example, at an air Separated from water in the water reservoir 20, passes flow rate of about 150 lpm across the catalytic converter, the through the port 30 and is collected in a Storage vessel or ideal range of hydrogen concentration in that flow is cylinder 55. During ignition, and perhaps during all opera between about 12 and about 13 volume percent. Under those tion of the vehicle, the oxygen may be released from the conditions, light-off temperature at the face 35 is reached in vessel 55 by opening a valve 57 and input into the intake of about one second. At an air flow rate of about 90 lpm and a the air pump 18. In this manner, the oxygen enriches the air hydrogen concentration between about 8.5 and about 11 and provides more efficient combustion of the hydrogen or Volume percent, light-off is achieved in about two Seconds. exhaust gases within the catalytic monolith 13. It should be The energy consumption to heat the catalyst varies recognized that the pump 18 of FIGS. 1 and 9 may be depending on the air flow rate and the concentration of replaced with a venturi for drawing air into the catalytic hydrogen. For example, at an air flow rate between about 30 15 COnVerter.

and about 50 lpm and a hydrogen concentration between Now referring to FIGS. 10(a) and (b), graphs are provided about 10 and about 11% volume percent, the chemical showing the catalyst temperature at various axial distances energy required to heat the monolith to light-off is approxi and radial distances in the catalyst monolith over a period of mately 1.5 Watt-hours. An electrically heated catalyst (EHC) 50 Seconds using a pulsed release of hydrogen into an air unit requires between about 10 to about 15 Watt-hours to Stream. The graphs show the temperature rise in the catalytic heat the same monolith at the air flow rate of 30 to 50 lpm. converter monolith at an air flow rate of 90 lpm and pulsed The present invention is also suitable for use in low hydrogen flow controlled by a microprocessor. The pulsed ambient temperature conditions, for example where the hydrogen flow was provided by opening the hydrogen outside temperature is as low as -7°C. or lower. Depending 25 release valves 46 and 48 (see FIG. 1) for 0.01 seconds and on the active catalyst compositions used, these extremely closing the valves for 0.66 Seconds, Successively 10 times. low temperatures may cause the amount of time required to Comparing the temperature profiles of FIG. 10(a) with achieve light-off to double. In those conditions, it may be those of FIGS. 6(a)-(d) and the temperature profile of FIG. desirable to add a small electrical heater, which would be 10(b) with those of FIGS. 7(a)-(d) it is shown that light-off much Smaller than an EHC heater and require only about temperatures of between about 400° C. and about 600 C. 200 Watts of power, in order to achieve the results similar to can be readily attained even with pulsed hydrogen flow. One those achieved at typical ambient temperatures. advantage of pulsed flow is the better utilization of the Now referring to FIG. 8, one aspect of the invention hydrogen and therefore conservation of the hydrogen Sup provides an on-board hydrogen ignition assist System 110. A ply.

Source of hydrogen, Such as the electrolyzer described above 35 FIG. 11 is a schematic diagram of an electrolyzer 150 or any Suitable means, fills the hydrogen Storage cylinder 24. having non-gas producing cells 152 used for heating or An ignition Supply line to a control valve 122 controls the cooling the electrolyzer using liquid from a vehicle radiator Supply of hydrogen into an engine ignition 124. The engine 154. These cells 152 may be comprised of plates providing ignition 124 includes the fuel, air, and electrical components a passage for the radiator fluid between electrolytic cells 156 for an internal combustion engine 126. Thus, the hydrogen 40 in order to absorb or deliver heat to the electrolyzer. Because can be Supplied at any convenient location So that it is electroly ZerS operate most efficiently at elevated injected into the cylinders of the engine 126. For example, temperatures, the radiator may be used to warm the elec hydrogen under pressure can be Supplied to the intake trolyzer in cold weather conditions. Alternately, the radiator manifold where there is already a fuel/air mixture (during fluid may be used to cool the electrolyzer after an extended the inlet cycle), or the hydrogen can be mixed with air before 45 period of use.

it goes to the engine's fuel injection System, or other means. FIGS. 12(a) and (b) are two catalytic converters 12 having The system 110 of FIG. 8 turns the internal combustion different hydrogen injection means 160. In each of the engine 126 into a hydrogen fuel injected engine for the first figures, the converters 12 have multiple monoliths 164 few Seconds of Start-up, before any gasoline is introduced Separated by a region 166 for hydrogen introduction and into the engine. This way, the catalytic converter can be 50 diffusion. In FIG. 12(a), the injection means 160 is primarily brought to light-off temperature before the engine begins external to the converter 12 with a plurality of injection producing undesirable emissions. Then, when gasoline is tubes 162 delivering hydrogen into the gaps 166. finally injected into the System, the catalytic converter has Conversely, in FIG. 12(b) the injection means 160 passes already been heated to a more efficient operating through the monoliths 164 with a plurality of holes or ports temperature, preferably the light off temperature. 55 168 for hydrogen delivery into the gaps 166. In a very Expended fuel gases are collected in an output manifold Similar manner, air or air/oxygen may be introduced in 128 and flow into the exhaust line 14. An ignition controller multiple locations to improve mixing, distribution, or hydro 130 provides control signals to the control valve 122 for the gen and oxygen combination characteristics Such as unifor introduction of hydrogen to the engine ignition 124 to mity acroSS the face of the catalyst.

coordinate hydrogen introduction during cold Start opera 60 FIG. 13 is a schematic diagram of a catalytic converter 12 tions. The on-board hydrogen ignition assist System 110 having an upstream isolation valve 170 and a downstream functions with or without the hydrogen delivery system 25 isolation valve 172. When the valves 170, 172 are closed, for introducing hydrogen directly into the catalyst monolith, hydrogen can be injected into the monolith 13 and allowed but the system 110 is preferably used in combination with to diffuse evenly throughout the monolith. After only a hydrogen delivery to the catalyst. When using both Systems 65 fraction of a second for diffusion, the valve 172 is opened 25, 110, the hydrogen generation and on-board Storage can and oxygen is delivered to provide a combination mixture. be used for both. Alternatively, because oxygen is a larger molecule and

Page 38

diffuses more slowly, it may be similarly advantageous to as appropriate. The control outputs from controller 134 first diffuse oxygen into the isolated monolith, then intro include lines 300, 302 to dual valve subsystem 46, 48 for duce hydrogen while opening valve 172. controlling the turning on and turning off of the valves 46, Now referring to FIG. 14(a)-(e) which are schematic 48, thus controlling the delivery of hydrogen to the exhaust diagrams outlining four possible topologies for the powering manifold 14, catalytic converter 12 or engine as desired. Controller 134 also has a control output line 304 to the of the electrolyzer system 200. In FIG. 14(a) the primary electrolyzer

Source of electrolyzer power is drawn directly from the power to thepower source 138 for controlling the Supply of electrolyzer 22.

vehicle battery 201 as well as from the alternator 203. FIG. The controller 134 has control output lines 306,307 to the 14(b) eliminates the electrical draw on the battery 201 by valves 38, 39 in order to control when to open and close placing diode 202 between the alternator 203 and the battery valves 38, 39 in order to recycle the water in storage vessel 201. Diode 202 allows current flow from the alternator to the 24. Controller 134 also has a sensor input line 308 from battery and other vehicle loads 205 but stops current flow water level sensor 146. The input from water level sensor from the battery to the electrolyzer 200. the current limiting 146 tells controller 134 to cycle valves 38, 39 when the circuit 206 protects the electrical system from over currents water level is too high and the water needs to be removed that could be drawn by the electrolyzer as the electrolyzer 15 from the cathode and recycled to the anode. Alternative resistance changes. FIG. 14(c) is shown having an alternator means of water recovery would include a float valve, 204 having an additional winding in which the magnetic electroosmosis, wicking, or operation of the Stack with the circuit provides current limiting to the electrolyzer 200. This anode dry and water provided by the cathode. Second winding would also allow higher Voltages to be Controller 134 has a sensor input line 310 from hydrogen delivered to the electrolyzer 200, allowing the number of preSSure Sensor 144. A high or low Signal from Sensor 144 cells within the stack to be increased. FIG. 14(d) shows a will tell controller 134 when to turn off or on the electrolyzer System in which the vehicle alternating current is drawn 22 through control output line 304 to electrolyzer power from the alternator 207 before the vehicle regulator 209 and Source 138. The controller 134 also has a sensor input line a separate current control/regulator 208 provides electrical power to the electrolyzer 200. This topology is able to 25 312 from bubble detector 37, an input signal line 314 from current limit the electrolyzer load and provide higher Volt pump 18switch ignition

132, and an output control line 316 to air control the turning on and off of air pump 18.

ages to the electrolyzer while using a conventional alterna The electrolyzer 22 may be provided with multiple per tor.

formance verifications and abnormal performance indicators

FIG. 14(e) shows a method of controlling the electrolyzer for on-board diagnostics. Some of these Sensors are not current while maintaining overall electrical conversion effi shown in FIG. 1 for ease of viewing the drawing and because ciency. In this mode of operation, the full potential of the a skilled person will readily understand where these Sensors vehicle's electrical System is placed acroSS the electrolyzer need to be placed. However, FIG. 16 shows these elements 200. Individual cells are then bypassed by external mechani in an abstract block diagram. Controller 134 may be used to cal or Solid state Switches 210, to lower the effective collect, Store and interpret the data from these Sensors and resistance of the electrolyzer, in Steps, until a current close 35 performance indicators and take appropriate corrective to the desired current is achieved. Cells may be switched in action including shutting the System 10 down and/or warn and out as desired to maintain the current within a window. ing the driver. When these operating parameters fall within The apparatus of the present invention, described above, acceptable ranges they indicate that the production and may be operated in any number of ways as will be recog 40 Storage of hydrogen is proceeding normally. The importance nized by those in the art. One preferred mode of operating of Some of these parameters, and the devices and methods a System of the present invention, including an electrolyzer, used to determine Some of the parameters, and the accept is described in FIG. 15. FIG. 15 is a flowsheet showing the able ranges for Some of them will now be discussed. modes of operation for an ideal chemically heated catalyst Conductivity Sensors 317, perhaps two independent Sen (CHC) system. 45 Sors placed at different heights within the anode reservoir, Control System and On-Board Diagnostics are used to measure the conductivity of the anode water and send a signal indicative thereof on sensor input line 319 to

The Control System and the On-Board Diagnostics are controller 134. These sensors will also establish the water illustrated in FIG. 16. The controller 134 may be the level Since a dry conductivity Sensor shows abnormally high vehicle's existing built-in controller System, i.e., engine 50 resistance.

management unit, or it may be a separate microprocessor A cell Voltage Sensor 321 may be placed in electrolyzer 22 controller System, or even just a State machine. At a mini to measure the Voltage drop acroSS each cell or Stack of cells mum the controller 134 would need to have a processing unit 26 and Send a Signal indicative thereof on Sensor input line (state machine), I/O pins or ports, and a memory. The 323 to controller 134. A stack voltage measurement may memory system may be an EEPROM or other suitable 55 provide the controller 134 with the voltage drop occurring System. The controller 134 may also have various registers across all of the cells within the electrolyzer stack 26. Under for Storing data. normal operation, this Voltage will fall within a narrow range A preferred controller 134 has multiple outputs for send that is characteristic of the electrolyzer 22, the temperature ing control signals to operate various parts of the hydrogen of the Stack, the Stack current, and the anode feed fluid (e.g., delivery system 10 (shown in FIG. 1), such as the hydrogen 60 alcohol concentration).

release Subsystem 25, the hydrogen Storage Subsystem 23, Stack current sensor 325, like cell voltage sensor 321, and the hydrogen generation subsystem 20, 22, 138. The may be placed in electronic communication with electro controller 134 also has multiple inputs for receiving Sensor lyZer 22 to measure the current through the Stack of cells 26 information and other Signals to control its own operation. and Send a signal indicative thereof on Sensor input line 327 These inputs may actually go into controller 134, or they 65 to controller 134. The stack current may be measured for may be distributed to the engine management unit, any other both performance verification as well as feedback for lim controllers or any combination of controllers in the vehicle iting the maximum current demand of the electrolyzer 22.

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Anode gas generation may be indicated by a bubble and oxygen. The rupture and leak may be determined by the detector 37 in the anode return line 34 to the water storage ambient hydrogen detector 337, a hydrogen pressure drop or reservoir 20. This bubble detector should indicate gas gen low rate of pressure increase in the Storage vessel 24, and eration within a window related to the current. Additionally, possibly a reduced cell Voltage. this detector will detect any gas leakage from the cathode to An electrolyzer mechanical leak may leak hydrogen to the the anode when the electrolyzer is off. ambient atmosphere and increase the time required to gen A cathode pressure sensor 329 may be placed in fluid erate hydrogen. This leak may be determined by the ambient communication with the cathode of electrolyzer 22 to mea hydrogen detector 337 or a low rate of pressure rise in the Sure the pressure of the gas at the cathode and Send a signal Storage vessel 24. Any leak situation will result in the indicative thereof on sensor input line 331 to controller 134. venting of hydrogen into the air where it will readily The change in cathode pressure may provide a direct reading disperse. The hydrogen Storage tank is at elevated pressure, of the hydrogen production rate. thereby preventing oxygen from leaking into the tank. A cathode water recovery system 38, 39, 146 may quan A restriction in the flow of water through the anode may tify the amount of water passing through the membrane in 15 limit the production of hydrogen due to overheating. This electrolyzer 22 from the anode to the cathode due to elec flow restriction may be indicated by a decrease in gas bubble troosmosis. The operation of the two valves 38, 39 will generation detected at the bubble detector 37 or by a rise in recover a known volume of water that controller 134 could temperature measurement in the electrolyzer 22. keep track of to determine whether the volume of water that Freezing of the electrolyzer 22 may slow the rate of has passed through electrolyzer 22 is within acceptable hydrogen production until the electrolyzer 22 can be thawed. limits. A Sufficiently low clectrolyZcr temperature measurement An electrolyzer temperature Sensor 333 may be placed may indicate freezing, but So may an elevated cell Voltage within electrolyzer 22 to measure the temperature of elec measurement.

trolyzer 22 and Send a signal indicative thereof on Sensor A reversal of polarity between the anode and cathode may input line 335 to controller 134. An electrolyzer, or stack, 25 potentially result in the release of hydrogen, from the System temperature measurement may be an abnormal operation 10. Shut-down of the hydrogen delivery system 10 may be indicator that will typically fall within a range around the required to prevent the release. The ambient hydrogen ambient temperature during normal operation. Abnormal detector 337 may indicate this failure, as will the cell voltage operation of the electrolyzer will result in extreme tempera measurements, the current measurement and the bubble ture readings, Such as temperatures greater than about 100 detector Since twice as much hydrogen gas will be produced. C The quantity of Stored hydrogen may be measured with An ambient hydrogen detector 337 may be placed near the any Suitable preSSure Sensor based on the fixed volume of the delivery system 10 to detect the presence of abnormally high vessel 24. One good Sensor is a Silicon Strain type preSSure levels of hydrogen in the ambient atmosphere and send a Sensor. The hydrogen pressure Sensor 144 provides the signal indicative thereof on sensor input line 339 to con 35 primary data for triggering the shutdown of the electrolyzer troller 134. 22 when the hydrogen storage vessel 24 is full. The con Improper readings in any of these measurements may troller 134 is preprogrammed with the desired maximum indicate more than one possible failure mode having differ preSSure which it compares with the Signal received from ing effects on Safety and performance as will now be sensor input line 310. The sensor 144 also provides the data 40 for triggering the closing of the valves 46, 48 when releasing described.

A loSS of water in the anode will Stop hydrogen hydrogen on a Volume basis during cold Start, because the production, but should not cause any permanent damage to controller 134 may calculate the volume released from the the electrolyzer 22. Such a loss of anode water would change in pressure. The Volume release methods will be normally be indicated by the cell or Stack Voltage measure described later.

ment being elevated or current reduced. The loSS of anode 45 For data from the hydrogen pressure sensor 144 to be water could also be indicated by an increase in the Stack accepted as reliable, the hydrogen delivery System 10 must temperature measurement, or by an indication from the provide predictable responses to Several conditions. For bubble detector 37 of a lack of anode gas bubble generation. example when no hydrogen is being released from the vessel A contamination of the anode water may decrease the 24, hydrogen generation should result in a steadily increas efficiency of the electrolyzer and result in higher cell volt 50 ing pressure reading in the hydrogen pressure Sensor 144 at ages and reduced hydrogen production. Conductivity Sen a rate proportional to the measured Stack current. Controller SorS 317 may indicate contaminated water by a change in or 134 may collect this data and make this comparison. improper level of conductivity. Additionally, cathode water recovery is performed by A Small leak in the proton eXchange membrane may risk transferring fixed quantities of water from the hydrogen a combination of hydrogen and oxygen in the anode reser 55 Storage vessel 24 to the anode water reservoir. Therefore, voir as well as an increase in the amount of time necessary during each transfer cycle, as the water is removed, the to produce a given quantity of hydrogen. The ambient available Volume for the hydrogen gas increases, resulting in hydrogen detector may directly detect the leak of hydrogen Step drops in pressure, which can be counted by controller if that leak is to outside the electrolyzer or Sense the 134 to determine the volume of water removed. hydrogen coming from the anode reservoir if the hydrogen 60 Hydrogen released from the hydrogen reservoir or Storage leak is internal to the electrolyzer. An increase in bubble vessel 24 during delivery of hydrogen to the vehicles production in the anode is also indicative of a hydrogen leak exhaust System provides the Simplest test of whether the as hydrogen escapes through the anode. delivery System 10 is functioning properly. In other words, A rupture of the membrane may cause a venting of hydrogen pressure must drop when the valves 46, 48 are hydrogen gas and should require a shutdown of the hydro 65 opened, or cycled.

gen delivery System 10 to prevent further hydrogen release, Ambient temperature Swings during times when the deliv which could lead to undesirable concentrations of hydrogen ery System 10 is idle provide an opportunity to measure the

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linearity of the hydrogen pressure Sensor 144 Since the If one valve 46, 48 is stuck open, then there is a potential hydrogen gas follows the ideal gas law. Controller 134 may for over release of hydrogen, but the hydrogen delivery keep track of corresponding temperatures and preSSures and System 10 may remain functional in Some delivery modes. calculate the expected changes. An unexpected hydrogen pressure drop in Vessel 24 may be A drift in absolute accuracy of the hydrogen pressure indicative of this failure.

Sensor 144 could possibly result in an over pressure or under If both valves 46, 48 are stuck open, then all of the preSSure of the hydrogen. It is the over pressure that could hydrogen will be released into the vehicle's exhaust System. have catastrophic effects. The drift in accuracy could also The system 10 will work one final time, albeit inefficiently, result in a proportional drift in the charge and discharge of and then fail completely. Total pressure loSS in Storage vessel the reservoir.

A drift in the linearity in the readings of the pressure 24 is a good indicator of this type of failure as is the temperature of the converter and response from the oxygen sensor 144 has the possible effect of an over release of Sensor(s) in the exhaust System.

hydrogen as well as an over pressure. It could also result in an under release of hydrogen, but that is just a performance If a valve 46, 48 is merely slow to respond, then there is problem, rather than a Safety problem. Additionally, there 15 the potential for over release of hydrogen. There is also a could be a corresponding drift in the charge and discharge of reduced accuracy during pulsed release, described below. the reservoir 24. This linearity drift may be detected by Unexpected pressure drop in Storage vessel 24 during pulsed measuring an unexpected time period required to charge or release is the most obvious indicator of this type of failure discharge the Storage vessel 24. There would also be an as is overheating of the catalytic converter. incorrect temperature response of the preSSure Sensor 144 The existing oxygen and lambda Sensors may also provide along the lines of the above described ambient temperature feedback to the control system. The exhaust face of the Swings. Sensor contains a highly catalytic Surface, Such as porous A total electronic failure of the hydrogen pressure Sensor platinum, which will react with the hydrogen and oxygen 144 could have the possibility of a hydrogen over pressure, during the preheating period. The response from the Sensor Since it is the pressure Sensor that provides the primary data 25 will be a combination of effects including direct heating of for shutting down the electrolyzer 22. Such a failure could the Sensor bringing it to operating temperature, reducing the result in the complete loSS of operation of the hydrogen oxygen partial pressure in the exhaust Stream due to com delivery system 10 even though the signal from the sensor bination with the hydrogen, and third, reduction of the is within normal range. When the sensor 144 indicates no Sensor output Voltage due to the presence of the hydrogen in change in the hydrogen pressure under conditions that the exhaust Stream.

should produce a change in hydrogen pressure (Such as a The use of the existing onboard oxygen Sensor would release or generation of hydrogen) then total electronic allow closed loop control of the CHC system without failure of the sensor 144 may have occurred. requiring any additional Sensors in this corrosive environ A mechanical failure of the hydrogen preSSure Sensor 144 ment. The Oxygen Sensor, which is generally heated to could lead to a hydrogen leak to the ambient atmosphere 35 operating temperature by the exhaust gas, produces a signal along with a complete loSS of operation of the System 10. corresponding to the oxygen content within the exhaust gas. The pressure Signal may remain within a normal range when A cold oxygen Sensor, however, produces a low Signal that it should be abnormal, and this would be detected as a fairly may easily be discriminated from a Sensor at operating Stable hydrogen pressure reading during hydrogen genera temperature.

tion or delivery when there should be a Significant change. 40 The release of hydrogen and availability of oxygen from During CHC operation, or hydrogen delivery, hydrogen the Secondary air pump will have two effects on the oxygen may be released into the vehicle's exhaust System and the Sensor depending upon its temperature. Both effects may be catalytic converter via two valves 46, 48, e.g., Solenoid used to establish the operation of the CHC system and used valves, operated by the CHC control system, or controller within the feedback to control the hydrogen release. 134. In this embodiment, the valves are in Series, so both 45 If the oxygen Sensor is at operating temperature, indicated must be opened, either together or alternatingly, before by a signal above a threshold value, and hydrogen is released hydrogen is released. Performance verification is concerned into the exhaust Stream, the Signal from the Sensor will be with the complete opening, closing, and response time of depressed due to the presence of hydrogen. The extent of the both valves 46, 48. Hydrogen pressure stability in storage Signal depression during each release pulse will correspond vessel 24, as shown by the hydrogen pressure Sensor 144, 50 to the quantity of hydrogen released from the CHC system during idle times may provide the leak rate of both valves and detected by the oxygen Sensor. Self heating oxygen 46, 48 in series or of each valve individually if the other Sensors, wherein a resistive heater is placed in the Sensor to Valve is left open. An expected hydrogen pressure drop in bring it to operating temperature Sooner, could be utilized for Storage vessel 24 during continuous opening may indicate closed loop control before the engine has started. The Sensor that each valve 46, 48 is opening as designed. The hydrogen 55 may also be hot when the vehicle has been operated recently preSSure drop may also quantify the response time of each enough that the Sensor is still hot, providing an opportunity valve 46,48. The controller 134 may be set for the valves 46, to test the CHC System even when the preheating may not 48 to typically respond to a 25 mS open pulse during which be necessary. Alternatively, this test may be performed after they release a fairly predictable amount of hydrogen gas. the engine has reached operating temperature and the release Therefore, a Significant unexpected drop in hydrogen pres 60 of hydrogen is only to verify the operation of the CHC Sure during gas release would be indicative of a delay in System. In another mode of operation the Sensor closest to Valve response time in either opening or closing. the engine is monitored during the period of the CHC If either valve 46, 48 is stuck closed, then there is a total preheat where the engine is running and the Sensor is just failure of the hydrogen delivery system 10, but this failure coming to operating temperature and providing a signal. alone does not present a Safety problem, because with no 65 During this time the Sensor will respond in a sinusoidal or drop in hydrogen preSSure, there is no trigger for turning on Sem-Square wave manner as each cylinder fires and the the electrolyzer, and the System 10 Stays in a Static State. exhaust is Swept past the Sensor. The release of hydrogen

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could be timed to the firing of the engine So the difference catalyst. This sensor would respond to the colors of the in Signal may be maximized. Additionally, timing the release catalyst face as the System is preheated. of hydrogen to the release of exhaust gas may further This optical sensor could be used for real time feedback improve the utilization of the hydrogen in the converter, e.g., during hydrogen release to minimize the preheating time by releasing the hydrogen between exhaust Strokes when the maximizing the hydrogen release. The controller would most Oxygen is present or utilizing the “back and forth” release H and slow or stop the release if a portion of the motion of the exhaust gas in the System while the engine is catalyst were to approach the hydrogen light off temperature. running. He release would be controlled to maintain catalyst face In a completely different mode of operation, a cold Sensor temperature as close to but below this light-off temperature. may be rapidly brought to operating temperature due to the The sensor could be provided with an optical filter that only allows colors near the light off temperature to be detected by presence of hydrogen and oxygen in the exhaust Stream. The the sensor. This would simplify the electronics since all face of the Sensor generally exposed to the exhaust consists colors below the threshold temperature would be ignored of a porous platinum catalyst that will Serve as an oxygen automatically. The Sensor could be integrating, i.e., respond hydrogen combination catalyst. The design of the Sensor and to the entire face and produce one signal, or Segmented, i.e., the placement of the Sensor with respect to the hydrogen 15 provide Signals for each area of catalyst. A Segmented Sensor inlet(s) and oxygen inlet(s) may be further optimized to could be used with multiple injection points to actively provide the best Signal and to eliminate any damaging or modify the hydrogen/oxygen distribution within the con aging affects due to this mode of heating. During the Verter.

operation of the CHC system before the cranking of the During hydrogen generation in the electrolyzer 22, water engine the initially cold Sensor will be monitored. AS it heats is transferred from the anode side of the electrolyzer 22 over (due to hydrogen-oxygen combination) its signal will cor to the cathode Side due to electroosmosis through the proton respond to the temperature of the Sensor face, and therefore eXchange membrane. This water eventually collects in the to the amount of hydrogen in the exhaust stream. When the bottom of Storage vessel 24 and is withdrawn and/or recov Sensor is fully heated its signal will become representative of ered using one or two valves 38, 39, e.g., Solenoid valves. If the oxygen content in the exhaust. AS the hydrogen release 25 two valves 38, 39 are used, then they may be plumbed in is varied or pulsed and the oxygen Stream is fixed, the Sensor Series and have a captive gas chamber between them. The will provide a real time Signal as to the amount of hydrogen, valves in part being depressed due to the presence of hydrogen. A amount38, 39 may be opened one at a time with a fixed of water being pushed from the reservoir 24 and sensor located after the first brick (or further downstream) in compressing the headspace in the Stub during the first half of the converter would respond not the presence of hydrogen (since it will have reacted on the brick) but the lowering of the cycle and transferred to the anode water reservoir during the oxygen concentrations resulting from combination with until only ahalf the Second of the cycle. This sequence may be continued hydrogen. Following this response will allow the conversion 24. The water levelamount

Small of water remains in the reservoir is Sensed using a Sensor 146, e.g., an efficiency, albeit only directly for hydrogen but possibly electro-optic liquid level Sensor. Performance Verification of correlated to other gases, of the catalytic converter to be 35 this cathode water recovery System is concerned with the monitored. This downstream Sensor will provide a real time complete opening and closing of the valves 38, 39 and of the response to a release of hydrogen Since that release and accurate detection of the water level.

combination with the Secondary air will cause a significant The rate of hydrogen preSSure increase during hydrogen dip in the oxygen content measured by the downstream generation is dependent upon the hydrogen Storage vessel 24 SCSO. 40 size. Failure of the cathode water recovery System to remove

This response from the Sensor can be characterized and water from the hydrogen Storage vessel 24 will result in a used to establish the performance of the CHC system (OBD Smaller effective Volume for Storing hydrogen and a faster II) as well as used for closed loop feedback during hydrogen rate of rise of hydrogen gas pressure during electrolysis. A release.

45 hydrogen pressure drop of known magnitude during water

Furthermore, on vehicles equipped with Sensors before recovery indicates that the valves 38, 39 are cycling cor and after the converter, the relative response of these two rectly. Additionally, the quantity of water recovered must Sensors during preheating and possibly in a special “perfor fall within a range that is directly proportional to the quantity mance evaluation mode” (when both sensors are at operating of hydrogen generated.

temperature) where H is released into the exhaust stream 50 If a valve 38 or 39, or in some cases both valves 38, 39, during Steady State operation of the engine and the calcu fail to open, there is no effect on Safety, but the hydrogen lated difference in hydrogen and oxygen content in the Storage capacity is reduced. This failure may be detected exhaust is compared to the measured values. when the hydrogen Storage vessel pressure fails to decrease The use of the oxygen and lambda Sensors may require during an attempted water recovery cycle. Additionally, an additional hydrogen injection points So only a partial flow of 55 abnormally high pressure increase during hydrogen genera H is seen by the O. Sensor (to prevent the Sensor from tion may indicate this type of failure. The most obvious overheating for example). result is the water level not falling. In a similar manner, a catalyst coated temperature Sensor If one of the valves 38 or 39 fails to close, there may be could be used as a direct measurement of the CHC perfor a release of hydrogen into the anode water reservoir 20. In mance. This Sensor would Serve as a representative Sample 60 this condition, the system 10 may continue under limited of the catalytic converter, providing a temperature response operation until maintenance can be performed. A Sudden as its surface combines the H and O. It would be more preSSure drop as hydrogen gas escapes during a water effective at evaluating the actual catalyst temperature on the recovery Step may indicate this type of failure. The ambient converter than a temperature Sensor Simply placed in the air hydrogen detector 337 may also detect the hydrogen that has Stream responding to hot air. 65 escaped.

Another feedback device would be an optical Sensor If the valves 38, 39 leak, then there may be a release of placed So it is exposed to the front Surface of the main hydrogen into the anode water reservoir, and the System 10

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will have to be shut down. A preSSure loSS during idle mode can be well characterized by providing the air flow as a may indicate this type of failure, and So may the ambient function of current draw. Measurement of the current Sup hydrogen detector 337. plied to air pump 18 provides the Status of the electronics If the water level detector 146 fails such that it indicates Supporting air pump 18 and the quantity of air being the vessel 24 to be dry, then storage vessel 24 will just 5 delivered to the vehicle's exhaust system. This current may continue to Store water, thus reducing the capacity for be measured using a shunt or Voltage drop across the Solid hydrogen. This failure condition may be indicated by the State Switch. If there is no air Supplied to the exhaust System, recovered cathode water Volume being outside the appro then the hydrogen will have nothing with which to combine priate range. Also, the rate of increase of the hydrogen to preheat the catalytic converter, so the system 10 will have preSSure may be abnormal, Since the available Volume of the to be shut down.

hydrogen Storage reservoir is reduced. If there is a blown fuse or other electrical failure of air If the water level detector 146 fails indicating that the pump 18 or motor thermal overload of air pump 18, then vessel 24 is wet, then there may be a release of hydrogen into shut-down of the system 10 may be required. A lack of any the anode water reservoir. The system 10 may continue current to air pump 18 may indicate this type of failure. under limited operation until maintenance can be performed. 15 A reduced air flow due to a restriction or back pressure in A bubble detector (not shown) in the recovered water path air pump 18 may mean that there is not enough oxygen to may detect this failure. The ambient hydrogen detector 337 combine with the hydrogen to preheat the catalytic converter may also detect this failure if hydrogen gas is allowed into 13, So exceSS hydrogen may be released through the vehi the vented anode water tank. cle's exhaust System. This condition may result in reduced AS the eventual Source of the hydrogen, it is preferred the heating of the catalytic converter 13. Current draw in air quantity and quality of the anode water must be monitored. pump 18 may indicate this failure. The ambient hydrogen Water level and quality monitoring is provided by conduc detector 337 described earlier will not help in this case tivity Sensors 317, perhaps having dual conductivity probes because it is not positioned to detect hydrogen coming out mounted at the middle and bottom of the anode reservoir. of the exhaust.

The temperature of the electrolyzer 22 is a function of the 25 If there is a partial failure of the motor or wiring harneSS ambient temperature, water quality, water quantity and elec or mechanical failure in air pump 18, then a shut-down of the trolyzer efficiency. A compromised water delivery System system 10 will be required. Current draw in air pump 18 may will result in an elevated operating temperature. Water indicate this failure. Other, more conventional means of quality is continuously monitored using the conductivity detecting air flow, e.g., hot wire, Vane Switches, etc., could probes. When both conductivity probes are immersed, a also be utilized.

direct comparison between the probes provides linearity and In the present embodiment, there are Several flags that relative accuracy measurements. The conductivity Sensors indicate problems, or errors, of varying degrees of Serious also provide a means of measuring the water level. ness within the hydrogen delivery system 10. Various When all of the anode water is consumed or lost, elec 35 procedures, described below, Set these flags and/or take trolyzer 22 will be unable to generate hydrogen. High cell appropriate action, Such as flashing an indicator light for the Voltage measurements and an eventual drop in Stack current driver, Shutting the hydrogen delivery System down, or other may indicate this failure mode. A reduced number of gas appropriate response. When an error is detected, the con bubbles detected by the bubble detector 37, slow pressure troller may alert the driver immediately, or may wait to See rise in the Storage vessel and a high electrolyzer temperature 40 if the flag goes away after a period of time or following a may also indicate this type of failure. particular event. For example, the controller may wait for a When anode water flow is interrupted, the electrolyzer 22 few driving cycles to see if the flag goes away. A driving may overheat requiring shut-down of the System 10. A high cycle includes Starting the vehicle, bringing the vehicle up to electrolyzer 22 temperature may indicate this failure mode. normal operating conditions, and Stopping the vehicle. For A reduced rate of gas bubbles occurring at the bubble 45 another flag, the controller may cause itself to re-initialize detector 37 and a temperature dependent cell Voltage mea and then check to see if the flag is still present. The Surement may also indicate this type of failure. programmed response depends on the Seriousness of the When the conductivity sensors 317 fail, whether they indicated problem. The flags may be kept in any convenient indicate the reservoir to be wet or dry, the system 10 may Storage, Such as an EEPROM, Special registers or the continue operation, but with a panel indicator if necessary. 50 memory used by the controller. The error, or total operating In either case, the conductivity must be within certain history, of the CHC system may be provided using fault predetermined limits. Increased cell Voltage measurements codes and interfaces similar to existing SAE Standards. and increased temperature are indicative of a dry reservoir or The operation of a controller System and on-board a wet reservoir having a high conductivity fluid. diagnostics is illustrate in FIG. 17 which shows a general If the conductivity sensors 317 fail or drift, then possible 55 operating flow for the main procedure for a controller damage may occur to electrolyzer 22 due to poor water System and on-board-diagnostics. There may be concur quality. There may also be a false panel indicator concerning rently running procedures. In other words, controller 134 water quality. Again, the conductivity must be within certain may be multithreading, or there may even be another con limits. Increased cell Voltage measurements and increased troller. Concurrent threads may be required to monitor the temperature may be used to Verify or identify poor water 60 system 10 for any errors. Therefore, although the below quality. described procedures may not show a means to monitor for A Source of oxygen, in air, for combination with the errors while a procedure is performing a task that could be electrochemically generated hydrogen to preheat the cata hampered or made dangerous by an error, the skilled perSon lytic converter may be provided by means of the electrically will understand that concurrent processes are readily appar activated air pump 18. Performance verification of the 65 ent that could maintain the system 10 at all times. hydrogen delivery system 10 preferably includes quantify The first step is to initialize the controller 134 in step 400 ing the amount of air delivered by the pump. The air pump to bring the System up to a known State, wherein all controls

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and flags are initially turned off. This step may be done upon may be read from the Serial port may be any information that powering up the System when the vehicle's battery is the off-board diagnostic device or Service technician needs attached to the vehicle, or by a Service technician, or after a to Send to the vehicle. For example, the Service technician certain number of driving cycles, or in response to an error. could adjust operating parameters or threshold values that Control then proceeds to Step 402 to wait for a key trigger change the performance of the vehicle. In addition to receiv or key-on signal. This Step is also known as the idle State. In ing data over the Serial port 341, the controller may send data this State, the controller 134 is waiting for a signal over input to the off-board diagnostic device. For example, all of the Signal line 314 that the engine is about to Start, which means Same Sensor Signals that are described herein could be sent that hydrogen delivery may Soon be necessary. In the to the off-board diagnostic device for a thorough diagnosis meantime, while the controller 134 is waiting for a key-on of the error within the vehicle, so that the service technician Signal, it may be monitoring certain System parameters. This may make repairs to the vehicle, Specifically System 10. step will be described in more detail below with reference to Additionally, all of the flag data could be sent to the FIG. 18. off-board diagnostic device. The driver of the vehicle may Control then proceeds to step 404 wherein the controller 15 not be able to repair whatever error occurs within the 134 checks for a Signal indicating that hydrogen is actually vehicle, So many errors or flags will generate nothing more to be released. This step will also do the hydrogen release if than a generic warning to the driver that the vehicle needs to it is called for. This step will be described in more detail be serviced. The Service technician, on the other hand, below with reference to FIG. 19. would need very detailed error information, including a Control then proceeds to step 406 wherein the controller mileage erable log before and after the error or flag, So a consid amount of data sent may be sent over serial port 341.

134 checks to see if the engine is actually cranking over The flags and Sensor data are used in the diagnostic proce before proceeding further. This step will be described in dures described herein.

more detail below with reference to FIG. 20.

Control then proceeds to step 408 wherein the controller Control then proceeds to step 420, wherein the controller 134 checks for another Signal to actually release hydrogen. 25 134 stores any data from the serial port 341 in memory. This This step will also do the hydrogen release if it is called for. there are may memory be an EEPROM, although it is recognized that

This step will be described in more detail below with data Storage. types of memory devices that could provide many reference to FIG. 21.

Control then proceeds to step 410 wherein the controller Control then proceeds to step 422, wherein the controller 134 will cause the electrolyzer 22 to produce hydrogen if it 134 checks for any hydrogen in the atmosphere, which could is needed to refill the hydrogen vessel 24 after any hydrogen in indicate a leak in the system 10. This step will be described more detail below with reference to FIG. 24.

releases in steps 404 and 408. This step will be described in more detail below with reference to FIG. 22. Control then Control then proceeds to step 424, wherein the controller proceeds to step 412, wherein the controller 134 will check 134 checks to see if the current tank pressure (Pc) is less than to see if the key-on Signal is still asserted or if any errors 35 50 psi. The data for the tank pressure (Pc) is read from occurred in any of the previous Steps. This Step will be hydrogen pressure sensor 144. If Pe-50 psi, then the con described in more detail below with reference to FIG. 23. troller 134 will set flag (Ee) in step 426. FIG. 18 describes the process that the controller 134 goes After the flag (Ee) is set or if Pc is not less than 50 psi, through while it is waiting for a key-trigger or key-on signal then control proceeds to step 428, wherein the controller 134 from the ignition during step 402 of the main procedure. The 40 checks to see if the tank pressure (Pc) is less than the tank key trigger is any kind of a pre-indication signal that the Setpoint pressure (PSp). If the answer is yes, then the driver is likely to try to start the engine Soon. For example, controller 134 sets the hydrogen leak flag (Ed) in step 430. it could be a signal that the driver has turned the key in the The tank Setpoint pressure is the pressure to which the ignition to the first position, or accessory position. It could Storage vessel 24 should be pressurized, and the System be a Signal that the driver has turned the key all the way to 45 should not lose this pressure while idle. crank the engine with a delay built in before the engine After the flag (Ed) is set or if Pc is not less than Psp, then actually Starts to crank. control proceeds to wherein the controller checks to see if The controller 134 enters the process at step 414, Begin. the key-on, or key trigger, Signal is asserted. If not, then Control proceeds to step 416, wherein the controller 134 control returns to Step 416 to begin the above procedure reads the current tank pressure (Pc) from the hydrogen 50 again. Otherwise, control proceeds to Step 434. pressure sensor 144 through sensor input line 310. In step 434, the controller 134 checks to see if the engine Control then proceeds to step 418, wherein the controller temperature (Te) is greater than the engine threshold tem 134 receives data from serial port 341. This port can be any perature for hydrogen release (Teth). If TexTeth, then the type of I/O device, not just a serial port. If controller 134 is vehicle is deemed to have been operated recently So the part of the vehicle's built-in engine management unit, then 55 catalyst will still be at the light-off temperature and does not that System will have its own Serial port which can be used. need hydrogen to be released to heat up the catalyst, So the The I/O device may be whatever link is required for com procedure returns to Step 416 to continue waiting and munication with off-board diagnostic equipment. The off monitoring.

board diagnostic equipment is a machine or computer that a If Te is not greater than Teth, then control proceeds to Step Service technician may use to diagnose problems with 60 436, wherein the controller 134 sends a signal on output vehicles brought in for service. If the vehicle is not attached control line 316 to air pump 18 to direct air pump 18 to turn to an off-board diagnostic device, then the controller 134 on in anticipation of a hydrogen release in one of the next will receive nothing from serial port 341 in step 418 and the steps. Control then proceeds to step 438, wherein the pro procedure will just continue on past this step. An alternative cedure returns to the main procedure in FIG. 17 and pro embodiment could have the procedure on FIG. 18 check to 65 ceeds to step 404.

See if the Serial port is attached to the off-board diagnostic FIG. 19 describes the process that the controller 134 takes device before attempting to read data from it. The data that the system 10 through in step 404 to determine if hydrogen

Page 44

is to be released in response to a key trigger release or a post FIG. 21 describes the process that the system 10 goes key trigger release. The trigger releases may be Software through in step 408 to determine if hydrogen is to be generated Signals depending on how many release Steps the released in response to a crank trigger release or a post crank controller is programmed to perform. FIGS. 19 and 21 show trigger release. The controller 134 enters the proceSS at Step a total of four release Steps; however, more or fewer Steps 464, begin. Control proceeds to step 466, wherein the may actually be programmed into the controller. These controller 134 checks to see if a crank trigger release Signal figures are merely illustrative of an embodiment of the has been received.

invention. It may even be possible to change the number of If there has not been a crank trigger release signal, then release Steps that the controller is programmed to perform, control proceeds to step 470. Otherwise, control proceeds to Such as through the data received over Serial port 341. step 468, wherein controller 134 orders hydrogen to be The controller 134 enters the process at step 440, begin. released. The hydrogen release step will be described below Control proceeds to step 442, wherein the controller 134 in more detail with reference to FIG. 25. Control then checks to See if a key trigger release signal has been proceeds to step 470.

received. In step 470, controller 134 checks to see if a post crank If there has not been a key trigger release Signal, then 15 trigger release Signal has been received. If there has not been control proceeds to Step 446. Otherwise, control proceeds to a post crank trigger release signal, then control proceeds to step 444, wherein controller 134 orders hydrogen to be step 474. Otherwise, control proceeds to step 472, wherein released. The hydrogen release step will be described below controller 134 orders hydrogen to be released. As stated in more detail with reference to FIG. 25. Control then above, the hydrogen release step will be described below in proceeds to Step 446. more detail with reference to FIG. 25. Control then proceeds In step 446, controller 134 checks to see if a post key to step 474 wherein the procedure returns to the main trigger release Signal has been received. If there has not been procedure in FIG. 17 and proceeds to step 410. a post key trigger release signal, then control proceeds to FIGS. 18-21 showed two possible triggers for indicating step 450. Otherwise, control proceeds to step 448, wherein 25 that hydrogen may soon be required to be released: (1) at controller 134 orders hydrogen to be released. As stated key-on, and (2) at crank of the engine. It is possible to above, the hydrogen release step will be described below in conceive of other ways to Signal an impending need for more detail with reference to FIG. 25. Control then proceeds hydrogen. For example, the vehicle could even be equipped to step 450 wherein the procedure returns to the main with a separate trigger button that the driver could manually procedure in FIG. 17 and proceeds to step 406. operate to Signal that the vehicle will Soon be started. FIG. 20 describes the process that controller 134 goes FIG. 22 describes the process by which the system 10 through in Step 406 while it waits for a crank trigger Signal. produces hydrogen through electrolysis in Step 410. Con Crank trigger is the Signal that the driver has turned the key troller 134 enters the process at step 476, begin. Control all the way to actually start cranking the engine. Controller proceeds to Step 478, wherein the controller goes through a 134 enters the process at step 452, begin. Control proceeds 35 Series of preliminary checks to determine certain parameters to step 454, wherein controller 134 checks to see if the of the system 10 and the vehicle. These preliminary checks elapsed time since the air pump was started is greater than will be described in more detail below with reference to FIG. the air pump idle time (Tpi), e.g., 15 Seconds. If So, then 26.

controller 134 sends a signal on output control line 316 to air Control proceeds to step 480, wherein controller 134 pump 18 to direct air pump 18 to turn off since it is better 40 performs a routine to maintain electrical power to the Stack not to leave the air pump on if the crank trigger Signal is of cells 26 within electrolyzer 22. This routine will be taking a long time to arrive. described in more detail below with reference to FIG. 27. After the air pump is directed to Stop, or if elapsed time The first time the procedure goes through this Step, it turns is not greater than Tpi, then control proceeds to Step 458, on the electrolyzer by Sending a signal to start hydrogen wherein controller 134 checks to see if the crank trigger 45 generation. In an alternative embodiment, this procedure Signal has been received. If not, then control returns to Step may also start a timer to time how long it takes to generate 454 to continue this process while waiting. Otherwise, hydrogen. An unusually long time period may indicate a control proceeds to step 460. An alternative embodiment problem with the hydrogen generation System. may have another step if the answer in step 458 was “no', Control then proceeds to step 482, wherein controller 134 wherein the procedure checks to See if the key-on signal is 50 monitors certain parameters in the production of hydrogen. still asserted. If not, then the driver may have aborted the Monitoring of the parameters will be described in more attempt to Start the engine, So the procedure should jump detail below with reference to FIG. 28.

back out to the main procedure. The System may be pro Control then proceeds to step 484, wherein controller 134 grammed to perform a limited number of pre-crank hydro reads the current tank pressure (Pc) data over Sensor input gen releases if the driver does not actually start the vehicle. 55 line 310 from hydrogen pressure sensor 144. Controller 134 For example, the system would allow the driver to turn the compares current tank pressure with the tank Setpoint pres key on and off again three times, releasing hydrogen each sure (Psp). If Pc is not greater than or equal to Psp, then time the converter is cold. The system would then not release control returns to step 480 to continue maintaining the hydrogen on the fourth attempt. This “false start” counter power to the electrolyzer 22 and monitoring the production could be reset by a Successful start or timeout period. 60 of hydrogen. If Pee Psp, then control leaves this loop and In step 460, controller 134 sends a signal on output proceeds to step 486. When PcePsp the storage tank is full. control line 316 to air pump 18 to direct the air pump 18 to In step 486, controller 134 checks water level sensor 146 turn on. If the air pump 18 was never turned off because the over sensor input line 308 to determine if there is water process never reached Step 456, then this signal will have no present in the hydrogen tank, or Storage vessel 24. If the effect on the air pump 18. Control then proceeds to step 462, 65 water level is too high, then control proceeds to step 488, wherein the procedure returns to the main procedure and wherein controller 134 Sends a command Sequence over continues at step 408. control output lines 306, 307 to the water outlet valves 38,

Page 45

39 to cycle and let some water out of storage vessel 24. The procedure at step 508, begin. Control proceeds to step 510, valves 38, 39 are cycled open and closed alternately in order wherein controller 134 checks the signal from ambient to draw out a packet of water of known volume, So hydrogen hydrogen detector 337 to determine whether hydrogen is will not be accidentally let out, too. This step may be present in the atmosphere. If hydrogen is not detected in the repeated until the water level Sensor 146 no longer Senses a atmosphere, then control proceeds to Step 512, wherein the water level that is too high. Then control proceeds to Step procedure returns control to whichever procedure called it. 490 wherein controller 134 checks the current tank pressure If hydrogen is detected in step 510, then control proceeds (Pc) again and compares it with the tank setpoint pressure to step 514, wherein controller 134 sets the hydrogen leak (Psp). If Pc is still not greater than or equal to Psp, which can flag (Ef). Control then proceeds to step 516, wherein con happen whenever water is recovered in step 488, then troller 134 calls the routine to shut down the hydrogen control returns to the hydrogen production loop Starting at delivery system. The shut-down routine will be described in the maintenance of electrical power to the stack in step 480. more detail below with reference to FIG. 29. Although this Otherwise, if Pc is still greater than or equal to Psp, then shut-down procedure shows the procedure returning to its control proceeds to Step 492, because at that point the calling procedure, there may be certain types of errorS/flags hydrogen pressure Sensor 144 has provided the Signal to the 15 that require a complete and immediate Shut-down of the controller 134 that the storage vessel 24 is full. system 10, including the controller 134, so that no procedure If when completing Step 486 water is not found in Storage continues running.

vessel 24, and the total water transferred is found within an FIG. 25 shows the procedure that the hydrogen delivery acceptable range, then control proceeds to Step 492. System 10 goes through to release hydrogen to the vehicle's When control reaches step 492, this condition indicates exhaust system. Control enters the procedure at step 518, that the preSSure of the hydrogen in Storage vessel 24 is at begin. Control then proceeds to step 520, wherein controller a maximum, i.e., the tank is fall, and there is no excess water 134 waits for a hydrogen release delay (tra) time period. in storage vessel 24. Therefore, controller 134 can turn off Control then proceeds to step 522, wherein controller 134 electrolyzer 22 in this Step by Sending a stop hydrogen 25 determines which mode, either timed release mode or Vol generation Signal Over control output line 304 to the elec ume release mode, is requested. If a timed release mode is trolyzer source 138 to turn off. Control then proceeds to step requested, then control proceeds to Step 524. If a Volume 494, wherein the process returns control to the main proce release mode is requested, then control proceeds to Step 526. dure at step 412. The mode may be programmed into the controller 134 such FIG. 23 describes the test complete procedure in step 412 that controller 134 requests a mode based upon where this of the main procedure. Control enters this procedure at Step procedure was called. For example, controller 134 may be 496, begin. Control then proceeds to step 498, wherein programmed to request one mode for the key trigger release controller 134 checks whether the key-on signal is asserted. Step 442, and it may be programmed to request another If so, then this signal indicates that the driver of the vehicle mode for the post key trigger release step 446, or the crank is either Still trying to Start the car or the car is actually 35 trigger release Step 466, or the post crank trigger release Step running, So the procedure must continue to Step 500, 470. The choice of modes may even be reprogrammed wherein control returns to the main procedure at Step 402 in through the data received from Serial port 341, Self tuning, order to proceed with the above described routines. or based on other parameters (Such as ambient temperature, If the key-on signal is not asserted in step 498, then driving habits and preferences, etc.). Additional release control proceeds to step 502, wherein controller 134 reads 40 modes, Such as closed loop modes based on Sensor data Such the variables from the various Sensors and flags. as exhaust oxygen Sensors, temperature Sensors, optical temperature

Control then proceeds to step 504, wherein controller 134 easily envisioned Sensors, etc., are not fully described but may be checks whether any error flags are Set. These flags may have and implemented. been Set by any of the other Steps in the main procedure, or In step 524, controller 134 determines which type of by an independently running thread that is monitoring 45 timed release method is requested; continuous release, System conditions. In either case, the indicated errors may packet release or pulsed release. AS with the choice of not have required immediate shut-down of the system 10. If modes, the choice of release methods is also programmed no error flag is Set, then controller 134 continues looping into controller 134 depending on where the hydrogen release back through step 498. If an error flag is set, then control procedure was called from.

proceeds to step 506 wherein controller 134 sends a signal 50 For a timed continuous release, control proceeds to Step to the panel indicator light to flash on and warn the driver of 528, wherein both valves 46, 48 are held open for a certain the vehicle that an error has occurred and the vehicle's amount of hydrogen release time (tvr). Afterwards, control hydrogen injection System may need Servicing. The proceeds to Step 534. For a timed packet release, control warning, however, may just be a low priority Service warn proceeds to Step 530, wherein packets of hydrogen are ing. After the procedure has given this warning, control 55 released over a period of time. This timed packet release returns to step 498 to continue the loop. Thus, the system method will be described in greater detail below with continues to monitor itself while the vehicle is turned off. reference to FIG. 30. Afterwards, control proceeds to step The exact timing of when the panel indicator is activated and 534. For a timed pulsed release, control proceeds to step the mode of indication are variables that can be changed as 532, wherein pulses of hydrogen are released over a certain desired. 60 period of time. This timed pulsed release method will be FIG. 24 shows the procedure that hydrogen delivery described in greater detail below with reference to FIG. 31. System 10 goes through in a check for a hydrogen leak from Afterwards, control proceeds to step 534. the system. This procedure is shown to be called by another In step 526, controller 134 determines which type of procedure and to return to the other procedure; however, in Volume release method is requested; continuous release, an alternative embodiment, this procedure continues to run 65 packet release or pulsed release. For a Volume continuous independently of any other procedures as an independent release, control proceeds to step 536, wherein both valves thread in the controller 134. Control is shown to enter this 46, 48 are held open until a certain volume of hydrogen is

Page 46

release (Vr). This volume may be calculated by controller water may be contaminated. If so, then controller 134 sets an 134 based on the change in preSSure in the Storage vessel 24 error flag (E6) in step 568, and then control proceeds to step as measured by hydrogen pressure Sensor 144. Afterwards, 570. If not, then control proceeds directly to step 570. control proceeds to Step 534. For a Volume packet release, In step 570, controller 134 checks to see if there is water control proceeds to Step 538, wherein packets of hydrogen in the anode reservoir. If there is no water, then controller are released until a certain Volume of hydrogen is released. 134 sets an error flag (E8) in step 572, and control proceeds This volume packet release method will be described in to step 574. If there is water, then controller 134 proceeds greater detail below with reference to FIG. 32. Afterwards, directly to step 574, wherein the procedure returns control to control proceeds to step 534. For a volume pulsed release, the procedure that called it, Such as the electrolyze procedure control proceeds to Step 540, wherein pulses of hydrogen are in FIG. 22 at step 478.

released until a certain Volume of hydrogen is released. This FIG. 27 shows the routine, or procedure, that hydrogen Volume pulsed release method will be described in greater delivery System 10 goes through to maintain the power to the detail below with reference to FIG. 33. Afterwards, control stack of cells 26 within electrolyzer 22. Control enters the proceeds to step 534. procedure at step 576, begin, and proceeds to step 578, In step 534, controller 134 reads the current tank pressure 15 wherein controller 134 sets the current Supplied to the stack (Pc) and compares it to the tank pressure at the beginning of of cells 26 by adjusting the duty cycle of the pulse width the hydrogen release (Pbr). If Pc is not less than Pbr, then modulator (PWM). This procedure to set the stack current controller 134 sets an error flag (E7) and control proceeds to will be described in greater detail below with reference to step 544. If Pe is less than Pbr, then control proceeds to step FIG. 34.

544. In step 544, controller 134 returns control to whichever Control then proceeds to step 580, wherein controller 134 procedure called for this hydrogen release procedure. checks to see if the individual cell voltages (Vc) are within FIG. 26 shows the preliminary checks procedure that a specified range, Such as between about 1.5 volts and about hydrogen delivery System 10 goes through to check certain 2.5 volts. If not, then controller 134 sets an error flag (E9) parameters of the System prior to producing hydrogen. 25 in step 582, and control proceeds to step 584. Control enters the procedure at step 546, begin. Control In step 584, controller 134 checks to see if the duty cycle proceeds to step 547, wherein a timer is started. Control of the PWM is less than 50%, indicating that the stack proceeds to step 548, wherein controller 134 checks to see current required Some adjustment to get it to the proper if the time elapsed (time) since starting the timer in step 547 level. If so, then controller 134 sets an error flag (Eb) in step exceeds a certain time period after which the air pump 586, and control proceeds to step 588. If the PWM's duty should be turned off (tpoff). If so, then control proceeds to cycle was not less than 50%, then control proceeds directly step 550, wherein controller 134 can go ahead and turn off to step 588.

air pump 18 by Sending a signal over output control line 316, In step 588, controller 134 checks to see if the current of and then control proceeds to step 552. If “time” is not greater the Stack (Istik) is less than 20 Amps and the temperature of than tpoff, then control returns back to step 548. 35 the water (Tw) is greater than or equal to 50° C. If both In step 552, controller 134 waits for a hydrogen release conditions are true, then there is an efficiency problem in the delay time (tra). Then control proceeds to step 554, wherein Stack because the water temperature should be closer to controller 134 checks to see if the temperature of the engine ambient temperature when the current is that low, So con (Te) is greater than the engine threshold temperature for troller 134 sets an error flag (E4) in step 590, and control electrolyzing (Tethe). If Te is not greater than Tethe, then 40 proceeds to step 592. If one condition is false, then control control loops back to this step to wait for the temperature to proceeds directly to step 592, wherein the procedure returns come up high enough for electrolyzer to begin production of control to the electrolysis process in FIG.22 at step 482. hydrogen. If Tea Tethe, then control proceeds to step 556. In FIG. 28 shows the procedure that hydrogen delivery an alternative embodiment, if TesTethe, then there may be system 10 goes through in step 482 of the electrolysis an additional Step wherein the procedure checks to See if the 45 process in FIG. 22 to monitor certain parameters during the key turns off, So the procedure can jump out and go to idle. production of hydrogen. Control starts at step 594 with the In step 556, the controller 134 checks to see if the system monitoring of the gas bubble frequency in return line 34 volts (Es) of the vehicle's electrical System is greater than through sensor input line 312. If the bubble frequency is not the minimum system volts (Esmin) required for operation of within the proper range, Such as between about 20 and about the electrolyzer. If not, then controller 134 waits for a battery 50 100 bubbles per minute, then controller 134 sets an error flag recovery time (tbr) in step 558 and then checks to see if the (ES) in step 596, and control proceeds to step 598. If the System volts (ES) is still not greater than the minimum bubble frequency is within the proper range, then control system volts (Esmin) in step 560. If ES is still not greater proceeds to step 598.

than Esmin, then controller 134 sets an error flag (E3) in step In step 598, controller 134 checks to see if the temperature 562 and then returns to the idle state in step 564. The 55 of the water (Tw) is greater than 20° C., and if not, then independently running procedure mentioned above for controller 134 sets an error flag (El) in step 600 indicating monitoring errors and flags may be able to take the appro that the water is too cool considering that the temperature priate action for this error flag, Since the preliminary checks should rise during electrolysis, So Something may not be procedure is returning to idle. If ES was greater than ESmin working right if the temperature is too low. If the tempera in either step 556 or step 560, then control proceeds to step 60 ture of the water is greater than 20 C., or after flag El is set, 566. In an alternative embodiment, if Ess Esmin in step 560, control proceeds to step 602.

then the procedure could loop back to step 558 and continue In step 602, controller 134 checks to see if the temperature to wait for the System Volts to come up. In the same loop, the of the water (Tw) is greater than 85 C, and if not then procedure could monitor the key-on signal to see if the control proceeds to step 612. Otherwise, controller 134 sets vehicle is ever turned off, So the procedure could go to idle. 65 an error flag (Ea) in step 604 and proceeds to check whether In step 566, controller 134 checks to see if the resistivity Tw is even greater than 95 C. in step 606, and if not, then of the water is less than 1 M ohm.cm, indicating that the the water is hot, but not too hot, So control can proceed on

Page 47

to step 612. Otherwise, the temperature of the water is too troller 134 proceeds to open Valve 46 for a time period, e.g., hot, so controller 134 sets error flag (Ea), which may be a 50 ms, and then closes it in step 658. Then controller 134 different flag than the one set in step 604, in step 608 and waits for another time period, e.g., another 50 ms to let the then goes to the Shut down procedure in Step 610 Since valve seat, in step 660 before opening valve 48 for a time Something must be wrong with the System if the water period, e.g., 50 ms again, in Step 662. Then controller 134 temperature is So high. This shut down procedure is waits for another time period in step 664, another 50 ms is described in greater detail below with reference to FIG. 29. sufficient to let the valve seat, and then checks in step 666 In step 612, controller 134 checks to see if the change in to see if the volume of hydrogen released for the duration of this packet release procedure has reached the desired hydro pressure over time (dP/dt) is greater than Zero or within a gen release Volume (Vr). The volume of hydrogen released window. Controller 134 may save the current pressure and may be calculated by the controller 134 from the pressure time Since the last reading in memory in order to calculate change of the Storage vessel and Summing the Volume of the change. If the pressure is not increasing, then controller each packet. If Volume released-Vr, then the procedure 134 sets an error flag (Ec) in step 614. Afterwards or continues back at Step 658 to release another packet. otherwise, the procedure returns in step 616 to step 484 in Otherwise, the procedure returns in step 668 to the hydrogen the electrolysis process in FIG. 22. 15 release procedure in FIG. 25 at step 534.

FIG. 29 shows the procedure that the hydrogen delivery FIG. 33 shows the procedure that the hydrogen delivery system 10 goes through to shut down the system 10, usually System 10 goes through to release hydrogen in timed pulses in response to an error in the System 10 that could cause for a specified volume of hydrogen in step 540 of FIG. 25. Serious problems if the System 10 continued to operate. Control enters the procedure at Step 670, begin, and con Control enters the procedure at Step 618, begin, and then troller 134 opens one of the valves 46, 48, e.g., valve 48, in controller 134 proceeds to Send a signal Over output control step 672 and holds it open. Controller 134 then opens the line 316 to turn off (close) the air pump 18 in step 620, to other valve, e.g., valve 46, for valve on time (tvon) and send a signal over output control line 304 to turn off the closes it in step 674. Controller 134 waits for valve off time electrolyzer 22 in Step 622, and to Send Signals over output 25 (tvoff) in step 676 before checking in step 678 to see if the control lines 306, 300 and 302 to turn off all valves 38, 46 Volume of hydrogen released during this entire Volume and 48 in step 624. Then in step 626, the procedure returns pulsed release procedure has reached the desired hydrogen the System 10 to the idle State in the main procedure at Step release volume (Vr). If not, then the procedure continues 402 in FIG. 17. back at Step 674 to release pulses of hydrogen, until the FIG. 30 shows the procedure that the hydrogen delivery hydrogen release volume (Vr) has passed, and controller 134 System 10 goes through to release hydrogen in timed packets can close valve 48 in step 680. In step 682, the procedure for a specified time period in step 530 of FIG. 25. Control returns to the hydrogen release procedure at step 534 in FIG. enters the procedure at step 628, begin, and controller 134 25.

proceeds to open valve 46 for a time period, e.g. 50 ms, and FIG. 34 shows the procedure that hydrogen delivery then closes it in step 630. Then controller 134 waits for 35 system 10 goes through to set the current (Istk) delivered to another time period, e.g. another 50 ms, in Step 632. This the Stack of cells 26. Control enters the procedure at Step extra wait Step gives the valve a chance to close and become 684, begin, and controller 134 proceeds to set the duty cycle Seated before opening valve 48 for a time period, e.g., 50 ms of the pulse width modulator (PWM) to 50% in step 686. again, in step 634. Then controller 134 waits for another Then controller 134 determines in step 690 whether the time period in step 636, another 50 ms is sufficient for the 40 Stack current (Istik) is less than, equal to, or greater than the valve to become seated, and then checks in step 638 to see maximum stack current (Istikma). The System prefers for Istk if the elapsed time (time) for the duration of this packet to be in a range fairly close to Istkma, so the controller 134 release procedure has reached the desired hydrogen release will increment the PWM's duty cycle by about 1% in step time (tvr). If not, then the procedure continues back at Step 692 if Istk is too low, or decrement the PWM's duty cycle 630 to release another packet. Otherwise, the procedure 45 by about 1% in step 696 if Istk is too high, and either way returns in step 640 to the hydrogen release procedure in FIG. return to step 690. When Istik finally is close enough to 25 at step 534. Istkma, the procedure returns control in step 694 to the stack FIG. 31 shows the procedure that the hydrogen delivery power maintenance procedure at step 580 in FIG. 27. Istkma System 10 goes through to release hydrogen in timed pulses may depend on the configuration of the Stack, the condition for a specified time period in step 532 of FIG. 25. Control 50 of the battery or the ambient temperature. If Istik is too high, enters the procedure at Step 642, begin, and controller 134 it could damage the vehicle's alternator. If Istk is too high or opens one of the valves 46, 48, e.g., valve 48, in step 644 and low, then there may be Something wrong with the hydrogen holds it open. Controller 134 then opens the other valve, e.g., delivery System and/or it will take too long to restore the valve 46, for valve on time (tvon) and closes it in step 646. hydrogen Supply.

Controller 134 waits for valve off time (tvoff) in step 648 55 FIG. 35 shows the procedure, running as an independent before checking in step 650 to see if the elapsed time (time) thread, that the controller 134 may go through to periodi during this entire timed pulsed release procedure has cally update data to Send via the Serial port 341 in case an reached the desired hydrogen release time (tvr). If not, then off-board diagnostic device or computer is attached to the the procedure continues back at Step 646 to release pulses of vehicle. A timer is started in step 698. Then in step 700, the hydrogen, until the hydrogen release time (tvr) has passed, 60 controller 134 waits for a time period, e.g., 2 Sec. Then in and controller 134 can close valve 48 in step 652. In step step 702, the controller 134 takes the current data and sends 654, the procedure returns to the hydrogen release procedure it on the serial port 341 to the off-board diagnostic device. at step 534 in FIG. 25. Then the timer is reset in step 704, and the procedure returns FIG. 32 shows the procedure that hydrogen delivery to step 698 for a continuous loop through these steps, so the System 10 goes through to release hydrogen in timed packets 65 Status of the Sensors are captured every two Seconds or So. for a specified volume of hydrogen in step 538 of FIG. 25. While the foregoing is directed to the preferred embodi Control enters the procedure at Step 656, begin, and con ment of the present invention, other and further embodi

Page 48

ments of the invention may be devised without departing 12. The controller of claim 9 wherein the sequence of from the basic Scope thereof, and the Scope thereof is Signals causes the first valve and the Second valve to open determined by the claims which follow. and close in a cycle, wherein the first valve opens and closes What is claimed is: and then the Second valve opens and closes, the cycle 1. An apparatus for purifying exhaust gas of an internal repeating for a specified time period resulting in a packet combustion engine comprising: delivery of hydrogen to the exhaust System during the a vehicle exhaust System; Specified time period.

a hydrogen delivery System; and 13. The controller of claim 8 wherein the controller sends a controller for controlling the hydrogen delivery System a Sequence of Signals to the first valve and the Second valve to Supply hydrogen to the vehicle exhaust System and resulting in a Volume release mode delivery of hydrogen to the internal combustion engine, wherein the controller the vehicle exhaust System.

comprises an output electrically connected to the 14. The controller of claim 13 wherein the sequence of hydrogen delivery System for Sending a signal to the Signals causes the first valve and the Second valve to open at hydrogen delivery System to release hydrogen to the Substantially the same time and to remain open until a vehicle exhaust System and the internal combustion 15 specified volume of hydrogen has been delivered to the engine. exhaust System resulting in a continuous delivery of the 2. The controller of claim 1, wherein the vehicle exhaust

System has a catalyst for catalytically combining the hydro Specified 15. The

Volume of hydrogen to the exhaust System.

controller of claim 13 wherein the sequence of gen with Oxygen. Signals causes the Second valve to open and to remain open 3. The controller of claim 2, wherein the hydrogen is released to the vehicle exhaust to preheat the catalytic while a causing the first valve to cycle open and closed until specified Volume of hydrogen has been delivered to the

COnVerter.

exhaust System resulting in a pulsed delivery of the Volume 4. The method of claim 3, wherein the exhaust system of hydrogen to the exhaust System.

includes a three-way catalytic converter. 16. The controller of claim 13 wherein the sequence of 5. The apparatus of claim 1, wherein the hydrogen deliv 25 Signals ery System comprises a variable flow control valve for and closecauses in a the first valve and the Second valve to open cycle, wherein the first valve opens and closes releasing hydrogen to the vehicle exhaust System. and then the Second valve opens and closes, the cycle 6. The apparatus of claim 1, wherein the hydrogen deliv repeating until a specified Volume of hydrogen has been ery System comprises a variable flow control valve for delivered to the exhaust System resulting in a packet delivery releasing hydrogen to the internal combustion engine.

7. The apparatus of claim 1, wherein the hydrogen deliv of 17. the Volume of hydrogen to the exhaust System. ery system comprises a first variable flow control valve for deliveryThe controller of claim 8, wherein the hydrogen System includes at least one Sensor is detecting at releasing hydrogen to the vehicle exhaust System and a least one parameter of the hydrogen delivery System and Second variable flow control valve for releasing hydrogen to Sending a signal to the controller indicating the valve of the the internal combustion engine. 35 at least one parameter, the controller further comprising at 8. An apparatus for purifying exhaust gas of an internal least one input for receiving the Signal indicating the value combustion engine comprising: of the at least one parameter.

a vehicle exhaust System; 18. An apparatus for purifying exhaust gas of an internal hydrogen delivery System; and combustion engine comprising:

a controller for delivery of hydrogen to the vehicle 40 a vehicle exhaust System;

exhaust System, the controller comprising an output a hydrogen deliverS System; and electronically connected to the hydrogen delivery Sys tem for Sending a signal to the hydrogen delivery a controller for delivery of hydrogen to the vehicle System to release hydrogen to the vehicle exhaust exhaust System, the controller comprising an output

electrically connected to the hydrogen delivery System the hydrogen delivery System comprising first and Second for Sending a signal to the hydrogen delivery System to Valves electrically connected to the controller; wherein release hydrogen to the vehicle exhaust System; the controller Sends a Signal to the first and Second wherein the hydrogen delivery System includes at least Valves to instruct the first and Second valves to open or one Sensor capable of detecting at least one parameter close, thereby permitting hydrogen to flow to the 50 of the hydrogen delivery System and Sending a Signal to vehicle exhaust System corresponding to Signals from the controller indicating the value of the at least one the controller. parameter, the controller further comprising at least one 9. The controller of claim 8 wherein the controller sends input for receiving the Signal indicating the value of the a Sequence of Signals to the first valve and the Second valve at least one parameter;

resulting in a timed release mode delivery of hydrogen to the 55 wherein each of the at least one parameter indicates a vehicle exhaust System. performance level of a part of the hydrogen delivery 10. The controller of claim 9 wherein the sequence of System, a value of the at least one parameter falling Signals causes the first valve and the Second valve to open at within a predetermined window indicating a normal Substantially the same time for a Specified time period performance level of the part of the hydrogen delivery resulting in a continuous delivery of hydrogen to the exhaust 60 System, and a value of the at least one parameter falling System during the Specified time period. Outside the predetermined window indicating an abnor 11. The controller of claim 9 wherein the sequence of mal performance level of the part of the hydrogen Signals causes the Second valve to open and to remain open delivery System.

while causing the first valve to cycle open and closed for a 19. A System for delivering hydrogen to an exhaust System Specified time period resulting in a pulsed delivery of 65 of a vehicle, the hydrogen delivery System comprising: hydrogen to the exhaust System during the Specified time a controller having an output for Sending a release Signal period. and a release Subsystem connected to the exhaust

Page 49

System and electrically connected to the controller for 30. The vehicle of claim 25 further comprising: receiving the release signal, the release Subsystem means for opening the first valve;

releasing hydrogen to the exhaust System in response to means for closing the first valve after a first predetermined the release signal; time period;

a hydrogen generation Subsystem connected to the release

Subsystem and electrically connected to the controller, means for opening the Second valve; and the hydrogen generation Subsystem generating hydro means for closing the Second valve after a Second prede gen for release to the exhaust System; termined time period;

wherein the controller has an output for Sending a start whereby the hydrogen delivery System releases hydrogen hydrogen-generation signal and the hydrogen genera 1O to the exhaust System in packets during a third prede tion Subsystem has an input for receiving the Start termined time period.

hydrogen-generation Signal, the hydrogen generation 31. The vehicle of claim 25 further comprising: Subsystem generating hydrogen in response to the

Start-hydrogen-generation signal. means for opening the Second valve; 20. The hydrogen delivery system of claim 19 wherein the 15 means for opening the first valve; vehicle generates a trigger Signal and the controller has an means for closing the first valve after a first predetermined input for receiving the trigger Signal, the controller Sending time period after opening the first valve; and the release Signal in response to receiving the trigger Signal. means for closing the Second valve after a Second prede 21. The hydrogen delivery system of claim 19 further termined time period;

comprising a hydrogen generation Subsystem connected to the release Subsystem and electrically connected to the whereby the hydrogen delivery System releases hydrogen controller, the hydrogen generation Subsystem generating to the exhaust System in timed pulses during the Second hydrogen for release to the exhaust System. predetermined time period. 22.The hydrogen delivery system of claim 19 further 32. The vehicle of claim 25 further comprising: comprising a hydrogen Storage Subsystem connected to the means for opening the first valve; release Subsystem and to the hydrogen generation Subsystem 25 means for opening the Second valve; and electrically connected to the controller for Storing the generated hydrogen. means for closing the Second valve after a predetermined 23. The hydrogen delivery system of claim 22 wherein the Volume of hydrogen has been released; and hydrogen Storage Subsystem has an output for Sending a means for closing the first valve; Storage-full Signal and the controller has an input for receiv whereby the hydrogen delivery System releases hydrogen ing the Storage full Signal, the controller Sending a stop to the exhaust System in a continuous flow until the hydrogen-generation signal to the hydrogen generation Sub predetermined Volume of hydrogen has been released. System upon receiving the Storage-full Signal. 33. The vehicle of claim 25 further comprising: 24. The apparatus of claim 19, wherein the release Sub

System comprises a variable flow control valve for releasing 35 means for opening the first valve; hydrogen to the vehicle exhaust System. means for closing the first valve after a first predetermined 25. A vehicle having an engine, an electrical System time period;

connected to the engine and an exhaust System connected to means for opening the Second valve; and the engine, the vehicle comprising a hydrogen delivery means for closing the Second valve after a Second prede System connected to the exhaust System; termined time period;

a controller electrically connected to the hydrogen deliv 40 whereby the hydrogen delivery System releases hydrogen ery System wherein the hydrogen delivery System includes a dual to the exhaust System in packets until a predetermined Valve Subsystem having a first valve and a Second Volume of hydrogen has been released. Valve, the dual valve Subsystem controlling the release 45 34. The vehicle of claim 25 further comprising: of hydrogen to the exhaust System. means for opening the Second valve; 26. The vehicle of claim 25 wherein the hydrogen deliv means for opening the first valve; ery System releases hydrogen into the exhaust System in means for closing the first valve after a predetermined response to the controller Sending a release signal to the time period after opening the first valve; and hydrogen delivery System. 50 means for closing the Second valve after a predetermined 27. The vehicle of claim 25 wherein the hydrogen deliv Volume of hydrogen has been released; ery System includes a valve for controlling the release of whereby the hydrogen delivery System releases hydrogen hydrogen to the exhaust System, the valve releasing hydro to the exhaust System in timed pulses until the prede gen into the exhaust System in response to a valve-on signal termined Volume of hydrogen has been released. from the controller. 35. The vehicle of claim 25 further comprising a hydrogen

28. The vehicle of claim 25 wherein the dual valve generation System electrically connected to the controller Subsystem releases hydrogen to the exhaust System in and connected to the hydrogen delivery System for gener response to a release Signal Sequence from the controller. ating hydrogen to be released.

29. The vehicle of claim 25 further comprising: 36. A vehicle having an engine, an electrical System means for opening the first valve; 60 connected to the engine and an exhaust System connected to means for opening the Second valve; the engine, the vehicle comprising a hydrogen delivery means for closing the Second valve after a predetermined System connected to the exhaust System; time period after opening the Second valve; and a controller electrically connected to the hydrogen deliv means for closing the first valve; ery System; and whereby the hydrogen delivery System releases hydrogen 65 a hydrogen generation System electrically connected to to the exhaust System in a continuous flow during the the controller and connected to the hydrogen delivery predetermined time period. System for generating hydrogen to be released,

Page 50

wherein the controller has an output for Sending a start (d) closing the first valve;

hydrogen-generation signal and the hydrogen genera (e) opening a second valve;

tion System has an input for receiving the Start (f) closing the Second valve; and hydrogen-generation Signal, the hydrogen generation

System generating hydrogen in response to the Start (g) repeating Steps (c)-(f) for a specified time period; hydrogen-generation Signal. whereby hydrogen is delivered to the vehicle exhaust 37. The vehicle of claim 36 further comprising a hydrogen System in packets during the Specified time period. Storage System connected to the hydrogen delivery System 46. A method of controlling delivery of hydrogen to a and to the hydrogen generation System and electrically vehicle exhaust System comprising:

connected to the controller for Storing the generated hydro 1O (a) receiving a release signal to deliver hydrogen to the gen. exhaust System;

38. The vehicle of claim 37 wherein the hydrogen storage (b) delivering hydrogen to the exhaust System; System has an output for Sending a storage-full Signal and the (c) opening a first valve and a second valve; and controller has an input for receiving the Storage full Signal, the controller Sending a stop-hydrogen-generation signal to 15 (d)specified closing the first valve and the Second valve after a volume of hydrogen has been delivered to the the hydrogen generation System upon receiving the Storage vehicle exhaust system; whereby the volume of hydro full signal. gen is delivered to the vehicle exhaust System continu 39. The apparatus of claim 36, wherein the hydrogen ously.

delivery comprises a variable flow control valve for releas 47. A method of controlling delivery of hydrogen to a ing hydrogen to the vehicle exhaust System. vehicle exhaust System comprising: 40. A method of controlling use of hydrogen onboard a (a) receiving a release signal to deliver hydrogen to the vehicle having an internal combustion engine and an exhaust exhaust System;

System, comprising:

(a) receiving a release signal to deliver hydrogen to the (b) delivering hydrogen to the exhaust System; exhaust System and the internal combustion engine; 25 (c) opening a second valve;

(b) delivering hydrogen to the exhaust System; and (d) opening a first valve;

(c) delivering hydrogen to the internal combustion engine. (e) closing the first valve;

41. The method of claim 40, wherein the exhaust system (f) repeating steps (d) and (e) until a specified volume of includes a three-way catalytic converter, and further com hydrogen has been delivered to the vehicle exhaust prising: System; and (d) catalytically combining the hydrogen with oxygen on (g) closing the Second valve; whereby the Volume of the three-way catalytic converter. hydrogen is delivered to the vehicle exhaust system in 42. A method of controlling delivery of hydrogen to a pulses.

vehicle exhaust System comprising: 35 48. A method of controlling delivery of hydrogen to a (a) receiving a release signal to deliver hydrogen to the vehicle exhaust System comprising:

exhaust System; and (a) receiving a release signal to deliver hydrogen to the (b) delivering hydrogen to the exhaust System; exhaust System;

(c) opening a first valve and a second valve; and (b) delivering hydrogen to the exhaust System;

(d) closing the first valve and the Second valve after a (c) opening a first valve;

Specified time period; (d) closing the first valve;

whereby hydrogen is delivered to the vehicle exhaust system (e) opening a second valve; continuously during the Specified time period. (f) closing the Second valve; and 43. The method of claim 42 comprising the further step of 45 (g) repeating Steps (c)-(f) until a specified volume of receiving a Signal indicating a need to deliver hydrogen to hydrogen has been delivered to the vehicle exhaust the vehicle exhaust System. system; whereby the volume of hydrogen is delivered 44. A method of controlling delivery of hydrogen to a to the vehicle exhaust System in packets. vehicle exhaust System comprising: 49. A method of controlling delivery of hydrogen to a (a) receiving a release signal to deliver hydrogen to the 50 vehicle exhaust System comprising:

exhaust System; (a) receiving a release signal to deliver hydrogen to the (b) delivering hydrogen to the exhaust System; exhaust System;

(c) opening a second valve; (b) delivering hydrogen to the exhaust System; and (d) opening a first valve; (c) cycling a valve System to release the hydrogen during

(e) closing the first valve; a predetermined time period. (f) repeating steps (d) and (e) for a specified time period; 50. A method of controlling delivery of hydrogen to a and vehicle exhaust System comprising:

(g) closing the Second valve; whereby hydrogen is deliv (a) receiving a release signal to deliver hydrogen to the ered to the vehicle exhaust System in pulses during the exhaust System;

Specified time period. (b) delivering hydrogen to the exhaust System; and 45. A method of controlling delivery of hydrogen to a (c) cycling a valve System to release a predetermined vehicle exhaust System comprising: Volume of hydrogen.

(a) receiving a release signal to deliver hydrogen to the 51. A method of controlling delivery of hydrogen to a exhaust System; 65 vehicle exhaust System comprising:

(b) delivering hydrogen to the exhaust System; (a) receiving a release signal to deliver hydrogen to the (c) opening a first valve; exhaust System; and

Page 51

(b) delivering hydrogen to the exhaust System; generating an error Signal when the at least one parameter (c) producing the hydrogen by electrolyzing water; and is detected not to be within the specified window; and (d) storing the produced hydrogen prior to delivering the executing a predetermined response to the error Signal. produced hydrogen. 61. The method of claim 60, wherein the step of executing 52. The method of claim 51, wherein a hydrogen delivery 5 a predetermined response includes the Step of presenting a System delivers the hydrogen to the vehicle exhaust System, warning indicator.

the method comprising the further Step of monitoring at least 62. The method of claim 60, wherein the step of executing one parameter of the hydrogen delivery System. a predetermined response includes the Step of Shutting off 53. A method of controlling delivery of hydrogen to a the hydrogen delivery System.

vehicle exhaust System comprising: 63. An apparatus, comprising:

(a) receiving a release signal to deliver hydrogen to the a first variable flow control valve in fluid communication exhaust System; and between a hydrogen delivery System and a vehicle (b) delivering hydrogen to the exhaust System exhaust System;

wherein a hydrogen delivery System delivers the hydro 15 a controller in communication with the first variable flow gen to the vehicle exhaust System, the method com control valve for controlling the flow of hydrogen prising the further Step of monitoring at least one through the first variable flow control valve to the parameter of the hydrogen delivery System Vehicle exhaust System and in communication with the hydrogen delivery System for delivering hydrogen to a detecting that the at least one parameter is not within a Vehicle engine.

Specified window; 64. The apparatus of claim 63, further comprising: generating an error Signal when the at least one parameter a second variable flow control valve in fluid communi is detected not to be within the specified window; and cation between the hydrogen delivery System and the executing a predetermined response to the error Signal. Vehicle engine, wherein the controller is in communi 54. The method of claim 53, wherein the step of executing 25 cation with the second variable flow control valve for a predetermined response includes the Step of presenting a controlling the flow of hydrogen through the Second warning indicator. variable flow control valve to the vehicle engine. 55. The method of claim 53, wherein the step of executing 65. The apparatus of claim 63, further comprising: a predetermined response includes the Step of Shutting off a third valve in fluid communication with the hydrogen the hydrogen delivery System. delivery System; and 56. A method of controlling hydrogen onboard a vehicle having an exhaust System and an internal combustion engine a third valve output in communication with the third valve comprising the Steps of: for instructing the third valve to open and close, electrolyzing water to produce hydrogen; wherein hydrogen flows to the vehicle engine when the third valve and the second variable flow control valve

Storing the produced hydrogen; 35 are open.

delivering hydrogen to the exhaust System; and 66. The apparatus of claim 65, wherein the third valve is delivering hydrogen to the internal combustion engine. downstream of the second variable flow control valve. 57. A method of providing hydrogen within a vehicle for 67. The apparatus of claim 65, wherein the third valve is a hydrogen delivery System for delivering hydrogen to the 40 upstream of the second variable flow control valve. vehicle's exhaust System comprising the Steps of: 68. An apparatus comprising: electrolyzing water to produce hydrogen; and a controller having an output for Sending a hydrogen flow Storing the produced hydrogen; control Signal and a hydrogen generation Signal; wherein the produced hydrogen is Stored in a storage a variable hydrogen flow control valve in communication vessel having a hydrogen pressure Sensor, 45 with the controller for receiving the hydrogen flow control Signal, wherein the variable hydrogen flow detecting a desired pressure from the hydrogen pressure control valve is in fluid communication with a vehicle Sensor; and exhaust System for releasing hydrogen to the vehicle Stopping the electrolyzing of water in response to detect exhaust System in response to the hydrogen flow con ing the desired pressure. trol Signal;

58. The method of claim 57, further comprising the step 50 a hydrogen generator in communication with the control of delivering hydrogen to the exhaust System. ler for receiving the hydrogen generation Signal, 59. The method claim 58, wherein the hydrogen is deliv wherein the hydrogen generator is in fluid communi ered to the exhaust System using a variable flow control cation with the variable hydrogen flow control valve; valve. and

60. A method of performing diagnostics on a hydrogen a Second valve in fluid communication between the delivery System for delivering hydrogen to a vehicle exhaust hydrogen generator and a vehicle engine, wherein the System comprising the Steps of: controller is in communication with the Second valve monitoring at least one parameter of the hydrogen deliv for controlling the flow of hydrogen through the Second ery System; 60 Valve to the vehicle engine.

detecting that the at least one parameter is not within a

Specified window; k k k k k