Vapor temperature controlled exhaust gas heat exchanger

Page 1 — bibliographic record

Page 2

Drawing sheet — no readable text.

Page 3

chambers through a plurality of intake manifold con

WAPORTEMPERATURE CONTROLLED duits. The advent of federally mandated internal com EXHAUST GAS HEAT EXCHANGER bustion engine exhaust emission standards has resulted CROSS REFERENCE TO RELATED in the investigation of techniques to substantially reduce APPLICATION the quantity of pollutants produced by an internal com This application is related to copending commonly bustion engine. One technique proposed to reduce the assigned patent application Ser. No. 660,281, filed on quantity of atmospheric pollutants generated by an Feb. 23, 1976 in the names of J. E. Auiler et al. and titled internal combustion engine has been to prevaporize the "Vaporized Liquid Fuel Delivery and Metering Sys 10 liquid fuel prior to delivery to the air stream. The basis tems'. of this proposal is the improved ability to control, from

BACKGROUND OF THE INVENTION

cylinder-to-cylinder within any one internal combus tion engine, the air/fuel ratio of the combustion mix 1. Field of the Invention ture. Experimental results have indicated that to the The present invention is directed to the field of inter 15 extent to which the air/fuel ratio may be controlled nal combustion engine fuel delivery and metering sys more accurately, the ability to implement techniques for tems. In particular, the present invention is directed to the reduction of atmospheric pollutants generated by that portion of the above-noted field which is con the internal combustion engine may also be increased. cerned with the delivery and metering of a liquid fuel to The prior art contains a substantial number of sugges provide a combustible air/fuel mixture for an internal 20 tions directed to the vaporization of a liquid fuel for use combustion engine. More particularly still, the present in a fuel delivery system for an internal combustion invention is directed to that portion of the above-noted engine. These prior art solutions have generally cen field which is concerned with the delivery and metering of a liquid fuel which has been vaporized prior to mix tered around using the exhaust gases of the internal ture with an air stream. More particularly still, the pres 25 combustion engine as a source of heat for heating a ent invention is directed to that portion of the above liquid fuel stream. However, the prior art suggestions noted field which is concerned with the vaporization of have not been wholly technically feasible in terms of a liquid fuel in quantities sufficient to maintain the oper providing a vaporized liquid fuel to an internal combus ation of an internal combustion engine in an automotive tion engine in an automotive environment. In particular, vehicle environment. More particularly still, the present 30 the automotive environment requires that fuel be deliv invention is directed to that portion of the above-noted ered to the internal combustion engine with mass flow field which is concerned with the provision of an inter rates which may vary by a factor of 20:1. Any liquid nal combustion engine waste heat operated liquid fuel fuel vaporizing system must therefore be capable of vaporizer operative to provide quantities of vaporized accommodating vaporization of liquid fuel which may liquid fuel sufficient to maintain operation of the inter 35 consumed by the engine with mass flow rates which nal combustion engine. More particularly still, the pres be vary by 20:1.

ent invention is directed to that portion of the above A further problem which has not been adequately noted field which is concerned with the provision of an addressed by the prior art involves the recognition that internal combustion engine exhaust gas system situated commercially available gasolines can be expected to be heat exchanger communicating with a source of liquid 40 completely vaporized attemperatures above about 425 fuel and operative, under normal engine operating con ditions, to transfer sufficient quantities of heat from the F. The temperature of the exhaust gases produced by an exhaust gas to the liquid fuel within the heat exchanger internal combustion engine can readily be substantially to provide sufficient quantities of vaporized liquid fuel in excess of this value. It is therefore a specific object of to sustain engine operation. More particularly still, the 45 the present invention to provide a liquid fuel vaporiza present invention is directed to that portion of the tion apparatus for insertion within the exhaust gas sys above-noted field which is concerned with the provi tem of an internal combustion engine which apparatus sion of means for modulating the temperature of an includes means to vary the temperature of the vaporiza exhaust gas actuated liquid fuel vaporizer. More partic tion apparatus. It is also an object of the present inven ularly still, the present invention is directed to that 50 tion to provide liquid fuel vaporization apparatus which portion of the above-noted field which is concerned is adapted to accommodate vaporization of a liquid fuel with the provision of a liquid fuel vaporizer positionable having a mass flow rate which may vary by a factor of within the exhaust gas conduit of an internal combus 20:1. In accommodating an engine which may consum tion engine having means responsive to the temperature masses of fuel which may vary by a substantial margin, of a vaporized liquid fuel to modulate the quantity of 55 the exhaust gas being supplied to the liquid fuel vaporizer. patentcross referenced copending commonly assigned application teaches the use of a variable volume 2. Description of the Prior Art vapor reservoir. It is therefore a further and specific It is well known in the prior art to provide a fuel in object of the present invention to provide a liquid fuel liquid form to a moving air stream for delivery to the combustion chambers of an internal combustion engine. 60 vaporization apparatus for charging a vapor reservoir. The prior art systems generally have utilized mechani BRIEF DESCRIPTION OF THE DRAWING cal or electromechanical fuel delivery and metering apparatus to provide metered quantities of liquid fuel in FIG. 1 illustrates a vaporized liquid fuel delivery and proximity to, and in some cases into, the combustion metering system with which the present invention is of chambers of an internal combustion engine. The prior 65 utility.

art has also taught that a quantity of liquid fuel may be FIG. 2 illustrates the liquid fuel vaporizer according added to a quantity of moving air upstream from, and to the present invention in a partly schematic, partly for ultimate delivery to, a plurality of combustion sectional view.

Page 4

DETAILED DESCRIPTION OF THE within the vapor delivery nozzle 42 and is controlled by PREFERRED EMBODIMENT servomechanism means 48. Carburetor means 40 in cludes mixing section 47 which intercommunicates the

Referring now to the drawing wherein like numerals metering venturi means 44 with the throttle body 17 and designate like structure throughout the various views the intake manifold 12.

thereof, FIG. 1 illustrates a vaporized liquid fuel deliv Servomechanism 48 may be for example a conven ery and metering system 10. The vaporized liquid fuel tional servomotor operated electrically or by electro delivery and metering system 10 is arranged to provide mechanical means. Servomechanism 48 receives an a combustible air/fuel mixture to the intake manifold 12 input command signal from servomechanism control of an internal combustion engine 14. Internal combus 10 means 50. As here illustrated, servomechanism control tion engine 14 is provided with combustion by-product means 50 are arranged to be responsive to an exhaust exhaust gas system or conduit means 16. Intake mani gas sensor 52 which may for example, a titania exhaust fold 12 is provided with throttle body 17. As illustrated, gas sensor according to U.S. Pat. No. 3,886,785. Ac internal combustion engine 14, intake manifold 12, cording to FIG. 1, fuel delivery and metering system 10 throttle body 17 and exhaust conduit means 16 are sub 15 is also provided with temperature control means 54. stantially conventional. For purposes of illustration, it Temperature control means 54 are arranged to be re will be considered that internal combustion engine 14 is sponsive to the vapor temperature' in vapor delivery of the type adapted for installation and use in powering conduit 38 in order to control an exhaust gas flow di an automotive vehicle, not shown. verter valve 56 which is described in greater detail System 10 is arranged to receive liquid fuel from a 20 hereinbelow with reference to FIG. 2. conventional liquid fuel reservoir or tank, not shown, Referring now to FIG. 2, the primary liquid fuel through conduit 18. Conduit 18 communicates with heater means 26 according to the present invention is intermediate liquid fuel reservoir 20. The communica illustrated in a partly schematic, partly sectional, partly tion between conduit 18 and intermediate reservoir 20 diagrammatic view. Primary heater means 26 comprise may be controlled, for example, by a pivoted float valve 25 a helical coil 260 of fuel conduit which is disposed 22 in the conventional manner. As will be appreciated, within heating chamber 262 of a bi-chambered housing liquid fuel could be pumped through conduit 18 by 264. Housing 264 is here shown to be formed as a por conventional pumping means such as the conventional tion of exhaust gas conduit 16. In order to achieve a mechanical or electrical fuel pump normally used in high surface-to-volume ratio for heat exchanger coil or automotive vehicles. 30 helix 260, consonant with rapid liquid vaporization of Liquid fuel contained in intermediate reservoir 20 liquid fuel within coil 260, a plurality of fuel conduits may be provided by coarse liquid fuel delivery means 24 260a, 260b and 260c are shown as being utilized in fabri to the primary heating means 26 according to the pres cating heat exchanger coil or helix 260. Each fuel con ent invention. Coarse liquid fuel delivery means 24 may duit 260a, 260b, 260c is preferably fabricated out of a include, for example, an electrical or mechanical liquid 35 thin walled material having good heat transfer capabil pump 28 and/or a liquid flow control valve 30. An ity and the ability to withstand the corrosive environ auxiliary heating means 32 is arranged in fluid serial ment of the exhaust system 16. We have found stainless flow relationship with respect to the primary heating steel tubing to be suitable. The coil 260 may be formed means 26 so that fuel provided from intermediate reser on a mandrel by any of the well known techniques. The voir 20 would flow serially through the primary heating individual conduits 260a, 260b, and 260c are would in means 26 and thence through auxiliary heating means side-by-side alignment and may be welded or otherwise 32. The auxiliary heating means 32 are shown to be bonded together to equalize the temperature gradients communicated via conduits 34 to vapor reservoir 36. between individual coils. Housing portion 264 includes As illustrated in FIG. 1, the primary and auxiliary a generally centrally disposed baffle means 268 to define heating means 26, 32 are connected in serial fluid flow 45 an exhaust gas flow chamber 266 which is separated relationship. In order for efficient operation of the auxil from the heat exchanger chamber 262. iary heating means 32, it should be designed for rela The flow of exhaust gases, in the direction of arrow tively low fuel flow consonant with operation of the D, through heat exchanger chamber 262 within ex associated engine 14 at idle. As such, however, the changer housing 264 is here controlled by exhaust gas auxiliary heating means 32 could present a high impe 50 flow diverter valve 56. Exhaust gas flow diverter valve dance to fluid flow and could impede engine operation 56 is pivotally connected as at 270 to the central baffle under high fuel consumption conditions. It is therefore 268 and is positioned in response to the vapor tempera contemplated that the primary and auxiliary heating ture responsive valve control means 54. Temperature means could be connected in parallel fluid flow. It is responsive valve control means 54 include a conven also contemplated to provide a fluid by-pass valve 55 tional vacuum motor means 272, vacuum valve 280 and downstream from primary heating means 26 and up temperature control circuit means 281.

stream from the auxiliary heating means 32 to place the Exhaust gas flow diverter valve 56 is mechanically primary heating means 26 in direct fluid communication linked or coupled to vacuum motor 272. Vacuum motor with the vapor reservoir 36 when the auxiliary heating 272 is operative to pivotally rotate diverter valve 56 means 32 are not required as a vapor supply source. between the positions denoted by stops 274, 276 on the Vapor reservoir 36 is communicated by way of con side wall of housing 264. Vacuum motor 272 is commu duit 38 with carburetor means 40. As used herein "car nicated by vacuum hose 278 to vacuum valve 280. Vac buretor' means any device for mixing fuel with air to uum valve 280 communicates with source of vacuum establish a combustible air/fuel mixture. As illustrated through vacuum conduit 282. The vacuum source may in FIG. 1, the vapor delivery nozzle 42 of vapor deliv 65 conveniently be an appropriate portion of the engine 14. ery conduit 38 is positioned within the low pressure Vacuum valve 280 may be, for example, a solenoid zone formed by the metering venturi means 44 of the operated valve to selective communicate vacuum carburetor means 40. A movable pintle 46 is situated motor 272 with a vacuum source in response to electri

Page 5

cal signals applied by temperature control circuit means section, coil 260, of about 1% of the displacement of the 281. Vacuum valve 280 is responsive to temperature associated engine. We have also found that sufficient control circuit means 281 to command vacuum motor heat will be present within chamber 262 after about 20 272 to actuate exhaust valve 56. By actuating exhaust seconds of engine operation (at an ambient temperature flow control valve 56 to a position in substantial abut of about 70 F) to fully vaporize liquid fuel flowing ment with stop 276, the flow of exhaust gas will be through fuel conduits 260a, 260b, 260c. It will be appre diverted from passage through chamber 262 which ciated that heat-up time will be, at least in part, a func includes heat exchanger coil 260 to passage through tion of the proximity of the primary heating means 26 to chamber 266. Temperature control circuit means 281 the engine 14 and the ambient temperature. may be arranged to be responsive to a thermistor 58. 10 We claim:

Thermistor 58 may be located, for example, within 1. The method of providing a vaporized liquid fuel to vapor conduit 38. Alternatively, thermistor 58 could be an internal combustion engine, comprising the steps of: in thermal exchange contact with the vapor within providing a closed flow of fluid fuel from a liquid fuel vapor reservoir 36 or with any other convenient struc reservoir means to a fuel vapor storage means; tural member having a temperature which is indicative 15 generating a flow of heated gaseous medium; of the temperature of the vapor within the vapor deliv causing said gaseous medium to flow in heat ex ery portion of the fuel delivery and metering system 10. change relation to the flow of fluid fuel at a loca By way of example, temperature responsive circuit tion intermediate the storage means and the reser means 281 may include an electrical bridge circuit voir means and at a temperature sufficient, consid which includes, as a portion thereof, the thermistor 58 20 ering minimum fluid fuel dwell time, to heat and and an electronic comparator circuit to establish the completely vaporize the liquid fuel; minimum desired vapor temperature. Such circuits are sensing a fuel temperature downstream, in the fuel well known in the art. As thus described, vacuum motor flow direction, from the fuel heating location; 272 and exhaust diverter valve 56 may be cooperative to modulating the heat exchange transfer rate between cause substantially all of the exhaust gas flow to pass 25 the gaseous medium flow and the fluid fuel in re through the chamber 262 and hence over heat ex sponse to sensed temperature whereby the temper changer coil 260 or to pass through by-pass chamber ature of the generated fuel vapor may be main 266. With the diverter valve 56 in an intermediate posi tained within a desired range; tion, a portion of the exhaust flow may pass through sensing the quantity of fuel vapor resident in the each chamber. Since placement of the diverter valve 56 30 vapor storage means; and in the extreme positions could ordinarily be expected to modulating the heat exchange transfer rate between result in substantial temperature variation of the vapor the fluid fuel flow and the gaseous medium flow in being provided to vapor reservoir 36, the thermal iner response to sensed vapor quantity whereby the tia of the heat exchanger coil 260, the central baffle 268 quantity of fuel vapor within the vapor storage and the thermal coupling between the two chambers of 35 means may be maintained within a desired range. the housing may be selected to give adequate tempera 2. The method according to claim 1 wherein the step ture smoothing commensurate with acceptable heat of modulating the heat exchanger transfer rate in re exchanger warm-up and good transient response times. sponse to sensed vapor quantity comprises the step of We have found that good results can be obtained with modulating the rate of delivery of liquid fuel to the a primary heater means 26 according to the present 40 heating location. k k . k k invention having a fuel volume within the vaporizer