System for improving fuel utilization

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US 2007/0277790 A1 Dec. 6, 2007

SYSTEM FOR IMPROVING FUEL benefits of improved fuel economy under conditions such UTILIZATION that the conventional catalyst is capable of reducing NOx emissions.

CROSS-REFERENCE TO RELATED 0008 Liquid fuel may be viewed as being comprised of APPLICATION fractions that may vaporize at different temperatures. This vaporization can be achieved by initial heating of liquid fuel 0001. This application is a continuation-in-part of prior at a first temperature (e.g. 70°F) and Subsequently increas U.S. application Ser. No. 11/421,698, filed Jun. 1, 2006, ing the temperature as the differing fractions of the liquid entitled SYSTEM FOR IMPROVING FUEL UTILIZA fuel are vaporized and/or decreased vaporization of the fuel TION. is detected. Referred to as fractionation, applicants have learned that generally sequentially supplying fractions of

FIELD OF INVENTION vapors to the combustion chamber may improve efficiency. 0009 Further, through observation and testing, appli 0002 This invention relates to a system for providing cants have discovered that vaporized fuel being conveyed to vaporized fuel to engines. the engine's combustion chamber may be subject to con densation during Such conveyance. This can happen, for

BACKGROUND AND BRIEF DESCRIPTION example, as a result of ambient air that has a temperature below that of the liquid fuel vaporization temperature being 0003 Vehicles powered by vaporized fuel, such as gaso mixed with the fuel vapors to lean out the mixture to achieve line, have been the Subject of numerous patents over many the desired air to fuel ratio. This may cause the fuel vapors years. Examples include co-owned U.S. Pat. Nos. 6,681,749 to in part condense and form liquid droplets. To help achieve and 6,907.866. The disclosures of such patents are incorpo improved performance, embodiments of the present inven rated herein by reference. tion may help to avoid Such condensation by elevating the 0004 Vaporizing the fuel prior to entrance to the cylinder temperature of the vapor and air mixture to a point above can lead to improved performance, particularly with respect that required for vaporization so that the fuel remains in a to Substantially improved fuel economy. Running an engine vaporized form. In other embodiments, the ambient air that “lean' (i.e., at an air to fuel ratio of greater than 15:1) can is to be mixed with the vaporized fuel may be preheated. lead to improved fuel economy. Accordingly, vaporizing the 0010 Further such heating of the air supply, vaporized fuel prior to entering the combustion chamber of the engine fuel, and/or air-vaporized fuel mixture may also further allows the engine to run at much higher air to fuel ratios than enhance the flame speed of the fuel/air mixture. This in turn a conventional engine, which in turn leads to improved fuel can extend the “lean limit” (i.e., the highest air:fuel ratio economy. where the engine can perform satisfactorily, without exces 0005. It has been learned, however, that a potential issue sive loss of power, misfire, and/or unacceptable hydrocarbon may arise with operating at the higher air-to-fuel ratios, in emissions). This extension of the lean limit may have several that an undesired increase in NO emissions may result. This advantages, including, but not limited to: (1) improving fuel is due in part to the fact that the conventional catalytic economy. (2) decreasing the amount of NOX produced. converters and catalyst on an automobile with a gasoline 0011. It is further helpful to elevate the temperature of the engine is designed to remove NO, with the engine operating ambient air that is mixed with and conveys the fuel vapors between about 13.5:1 and 16:1, with the optimal ratio being from the vaporization chamber prior to entry into the com about 14.7:1. bustion chamber of the engine. As will be discussed more 0006. However, applicants have found that the amount of fully hereafter, the mixed air/fuel from the vaporization NO, actually produced by the engine decreases as the chamber may be further diluted with air, and such further air air/fuel ratio increases, and the increase in emissions is a may also be heated whereby the diluted vaporized fuel result of the fact that the catalyst cannot reduce even the mixture, upon entering the combustion chamber, is elevated smaller amount of NO produced under these conditions. above the temperature of the non-diluted mixture conveyed Thus, applicants have learned that by operating an engine at from the vaporization chamber. As described above, this a sufficiently high air/fuel ratio, the amount of NO, formed heating of the air/fuel mixture may help to achieve some of the benefits that improve engine performance, including would be sufficiently low such that the engine could meet preventing condensation of the fuel and increasing the flame emissions requirements, even with a catalyst that was not speed.

operating at its optimal conditions (e.g. about 14.7:1 air to fuel ratio). BRIEF DESCRIPTION OF THE DRAWINGS 0007 Embodiments of the present invention disclose ways to operate a combustion engine at these higher air-fuel 0012 Embodiments in accordance with the present ratio (e.g., about greater than 21:1) such that the level of invention will be more fully understood and appreciated by NOx emitted can satisfy existing regulations. One of the reference to the following detailed description and the advantages of Such operation may be that the high air-fuel accompanying drawings.

ratio can allow for substantial improvements in fuel 0013 FIG. 1 is a schematic illustration of a vaporized economy. As catalyst technology employed in vehicles fuel engine including a source of heated ambient air in improves, however, the embodiments of the present inven accordance with the invention; and tion may be used to improve fuel economy with other 0014 FIG. 2 is a compilation of charts demonstrating the air-fuel ratios (e.g., between 15:1 and 21:1) and still meet benefits of the invention.

emission standards. Moreover, it has recently been found that using embodiments of the present invention with an air DETAILED DESCRIPTION OF EMBODIMENTS to fuel ratio at or generally near the standard ratios that are OF THE INVENTION optimal for today's catalytic converters (e.g. ranging between about 13.5:1 and 16:1, with about 14.7:1 being 0015. In the following detailed description, reference is optimal)) also improves fuel economy. Thus one has the made to the accompanying drawings which form a part

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hereof and in which is shown by way of illustration embodi direct airflow from conduit 20 through the vaporization ments in which the invention may be practiced. It is to be chamber and into conduit 42. Liquid fuel 23 may be drawn understood that other embodiments may be utilized and from a fuel tank 32 via conduit 34. Heating element 25 may structural or logical changes may be made without departing be coupled to vaporization chamber 26 and adapted to from the scope of the present invention. Therefore, the controllably heat the liquid fuel to generate fuel vapors 40. following detailed description is not to be taken in a limiting A number of heating sources may be used to controllably sense, and the scope of embodiments in accordance with the heat the liquid fuel, including, but not limited to engine present invention is defined by the appended claims and component proximity, engine fluids (water, oil, etc.), elec their equivalents. trical circuits, and other independent heating devices. 0016 Various operations may be described as multiple (0025. The vapors 40 may be carried by the air flow from discrete operations in turn, in a manner that may be helpful air conduit 20, such that the air-fuel vapor mixture may be in understanding embodiments of the present invention; directed out through conduit 42 to the mixing chamber 30. however, the order of description should not be construed to In one embodiment, the flow of the air-fuel vapor through imply that these operations are order dependent. conduit 20 may be controlled by valve 44. 0017. The description may use orientation and/or per 0026. In one embodiment, the air-fuel vapor mixture of spective-based descriptions such as up/down, back/front, conduit 42 may be more rich than desired, and can be further and top/bottom. Such descriptions are merely used to facili leaned with air. When this is the case, the air-fuel mixture tate the discussion and are not intended to restrict the may be intermixed (e.g. further leaned) in mixing chamber application of embodiments of the present invention. 30 with air from conduit 18, and further directed through the 0018. The description may use phrases such as “in an intake port 10 and from there into the combustion chamber embodiment,” or “in embodiments.” Such phrases may each of the engine. The desired air to fuel ratio being supplied to refer to one or more of the same or different embodiments. the combustion engine may thus be controlled in several Furthermore, the terms “comprising,” “including,” “hav ways, including, but not limited to controlling the air Supply ing, and the like, as used with respect to embodiments of to the combustion chamber, controlling the air Supply to the the present invention, are synonymous. mixing chamber, and/or increasing the rate of vaporization 0019. The phrase “A/B” means “A or B.’ The phrase “A of the liquid fuel.

and/or B means “(A), (B), or (A and B). The phrase “at 0027. In one embodiment, it may be desirable to achieve least one of A, B and C’ means “(A), (B), (C), (A and B). an air to fuel ratio of at or above 26:1, which should yield (A and C), (B and C) or (A, B and C).” The phrase “(A) B' NOx emissions that are substantially lower than those means “(B) or (AB), that is, A is optional. obtained at a lower air to fuel ratio and will meet today's 0020. The terms “coupled' and “connected,” along with emission standards. In another embodiment, operating with their derivatives, may be used. It should be understood that an air to fuel ratio below 26:1 will likely yield NOx these terms are not intended as synonyms for each other. emissions above today's acceptable emission standards. Rather, in particular embodiments, “connected may be used However, as catalyst technology or engine improvements to indicate that two or more elements are in direct physical (e.g., EGR) are employed, the air to fuel ratio achieved by or electrical contact with each other. “Coupled may mean embodiments of the present invention may be lower, yield that two or more elements are in direct physical or electrical ing acceptable NOx levels, while still resulting improved contact. However, “coupled may also mean that two or fuel economy. Yet in other embodiments, where the air to more elements are not in direct contact with each other, but fuel ratio is kept in line with standard ratios used on many yet still cooperate or interact with each other. current vehicles, such as between about 13.5:1 and 16:1, the 0021 Reference is made to FIG. 1, which provides a catalytic conversion systems in Such vehicles may generally schematic overview of the components of a system in be able to reduce the NOx emissions to below the acceptable accordance with some embodiments of the present inven limit.

tion. A powered engine as labeled, may include an intake 0028 Assuming a specific hydrocarbon emission is port 10 connected to the engine's throttle body. The engine, desired, a reading of the emissions sensor may help to verify when operating, may draw air and fuel through port 10. The that the desired air to fuel ratio is achieved. However, it can engine may also includes an exhaust pipe 12 that is equipped be appreciated that a fixed setting will not likely achieve the with a senor 14 adapted to detect O2 and/or other emissions. optimum performance over any given period of time. Any 0022. In one embodiment, air box 16 may allow the temperature change, any elevational change and even dif Supply of air to the system when operating the engine. Air ferences in fuel make up may skew the vapor/fuel mixture conducting conduits 18 and 20 coupled to air box 16 may flowing from the tank 26 to the mixing chamber 30. bifurcate the inflow of air and provides the desired air supply 0029. Accordingly, the valves 22, 28, and 44 may be to the remainder of the system. In other embodiments, the operated by, for example, stepper motors (not shown) con conduits 18 and 20 may be coupled to separate air supplies. trolled by computer C. Computer C may monitor the emis Conduit 20 may include a valve 22 which controls the sions in exhaust 12 and should those readings indicate that volume of air directed through conduit 20. Conduit 20 may the levels of hydrocarbons are too high or too low, the be further coupled to vaporizing chamber 26 via, e.g., the top computer may activate the appropriate stepper motors to or cover 24, and thus configured to Supply air to vaporizing change the relative fluid volumes of air from conduit 18, air chamber 26. from conduit 20 and the air-fuel vapor mixture of conduit 42. 0023 Conduit 18 may be coupled to a mixing chamber Should the reading show a too high hydrocarbon level, the 30 and include a valve 28 that may be configured to control vapor/air flow of conduit 44 may need to be lessened, e.g., the volume of air supplied to mixing chamber 30. Mixing the valve 44 may be closed, the valve 28 opened, and or both chamber 30 may be any volume where air and vapor fuel are closing of valve 44 and opening of valve 28. brought together, Such as a chamber, confluence, and the 0030 These adjustments may take place in stages (e.g., a like. partial closing of valve 44, a rereading of the emissions 0024. In one embodiment, vaporization chamber 26 may sensor followed by repeated further partial closing of valve include a flow control apparatus e.g. baffles, which can 44, or alternatively the partial opening of valve 28, or a

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combination of both). In one embodiment, valve 22 can also mixing chamber and/or the combustion chamber. Such a be a factor, as restricting air flow into conduit 20 will slow heat source may be controlled to in order to keep the the flow of air to the tank 26, thus to conduit 42, while also temperature of the mixture sufficiently elevated and to resist diverting more air flow through valve 28. condensation. In Such a case, the air-vapor fuel mix may be 0031 Embodiments of the present invention may include Subjected to a further temperature increase without concern one or more additional heat Sources that can allow for for impacting the fractionation process. heating 1) the air that may be supplied to the vaporization 0038. In one embodiment, the temperature of the air tank, 2) the air that may be Supplied to the mixing chamber, supply to the mixing chamber 30 may be elevated by heat 3) the air and vaporized fuel mixture exiting the vaporizing source 46 in order to further heat the air-fuel mixture prior chamber, and/or 4) the air and/or air/vaporized fuel mixture to being conveyed into the combustion chamber of the at any time prior to entering the combustion chamber. engine via intake port 10. This may help to improve burning 0032. In one embodiment, a heat source 46 may control efficiency as well as prevent condensation in the mixing the temperature of the air flow 48 and elevate the tempera chamber itself.

ture of the air Supply as deemed necessary based on the content of the emissions. As illustrated, heat source 46 may 0039 Elevation of the temperature of vapor fuel mixture be heating coils 50 disposed within the air flow 48. How being directed through intake port 10 can be achieved and/or ever, embodiments of the present invention may include a augmented in a variety of ways that are separate from, variety of heat sources, including heat generated from dif complementary to and/or in addition to those described ferent components of the engine (e.g. the engine's manifold above. In one embodiment, the relationship of the heat and/or engine fluids), as well as independent heat sources. Sources to the vaporization chamber and the mixing chamber 0033. However provided, upon traversing the heat source can impact the heating of the air-fuel vapor mixture. For 46, the air inflow 48 may be controllably elevated in example, if the relationship of the heat source 46 to the temperature (e.g., controllably raising the typical ambient air vaporization chamber 26, as compared to the mixing cham temperature from a range of about 60° to 80° F. to a ber 30 results in a longer conveyance path to the vaporiza temperature of about 100° to 120°F). Again, the amount the tion chamber, this may result in an undesired drop in the temperature of the air Supply may vary depending on temperature. A shorter distance through conduit 18 into emission content and conditions, and may be controlled mixing chamber 30 may thus provide the desired elevation based thereon.

in temperature to the vaporized fuel conveyed to the com 0034. In one embodiment, control 27 may control the bustion chamber.

heat generation of heat element 25. Control 27 may also be coupled to and controlled by the computer C depending on 0040. In various other embodiments, heat may be applied the response in part to the emission detections by sensor 14. to various components of the system to help elevate the In one embodiment, the liquid fuel in the vaporization tank temperature of the air-fuel mixture prior to entering the 26 may be vaporized and mixed with the air supply from combustion chamber to help improve efficiency and/or to conduit 20. This mixture may be directed to the mixing help prevent condensation. Further, other alternatives are chamber 30 and further to the combustion chamber of the available and of course separate heat sources may be utilized engine. As discussed above, the temperature of the liquid at different locations in the system. fuel may be increased enough to vaporize one fraction of the 0041 Reference is now made to FIG. 2 illustrates some fuel 23 at a time. The temperature of the fuel 23 may then of the beneficial result that may be achieved by employing be raised to initiate vaporization of a second fraction, which embodiments of the present invention. An example of the in turn may be carried out of the vaporization chamber with combustion of vaporized fuel without the added heat is the air Supply, and so on. shown in Solid lines in graph 1 and the heated fuel is shown 0035. While the air-fuel mixture is being conveyed to the in dashed lines. By increasing the temperature of the vapor, combustion chamber and/or the mixing chamber, there may the ratio of air to fuel can be increased substantially without be the possibility that a part of the mixture may condense to materially sacrificing the desired fuel economy. A distinct liquid form prior to entering the combustion chamber. In one benefit of such elevation is the reduction of nitrogen oxide embodiment, to prevent condensation from taking place as demonstrated in graph 4. Graphs 2 and 3 illustrate the (e.g. in the path through conduit 42 and mixing chamber 30), comparable reduction of CO and increase in O. the air from conduit 20 may be elevated e.g. by heat source 0042. As set forth in the embodiments above, applicants 46 to establish a temperature of the air at or above the have learned heating the vaporized fuel, the air/vaporized temperature of the vapor 40. This may prevent condensation fuel mixture, the air that is mixed with the vaporized fuel, as the fuel is carried through conduit 42 and into the mixing and/or any combination thereof prior to combustion results chamber 30. A too high temperature of air from conduit 20, in a measurable improvement in fuel efficiency. This mea however, could undesirably overheat the liquid fuel 23 Surable improvement occurs in systems operating at a range producing an undesired high rate of vaporization, which in of air to fuel ratios from the current standard ratios up to certain embodiments, may affect the fractionation of the much leaner ratios in the area of greater than 30:1. In liquid fuel and alter the characteristics of the mixture. Thus particular, applicants have found that using a mixture falling the temperature of the air entering the vaporization chamber within the standard ratio (e.g. between about 13.5:1 and may be controlled to avoid this occurrence. 16:1) has led to efficiency improvements of up to 20%, and 0036 Because the air temperature may drop as it is in Some cases even more.

conveyed from the heat Source 46 and because the process 0043. While the engine-out NOx emissions from the of vaporization itself extracts energy, in one embodiment, combustion of vaporized fuels at these more standard ratios there may be a balancing of the elevation of the air tem may be higher than the allowable emission standards and perature. This may be monitored and controlled by tempera higher than the emissions from leaner ratios, this has been ture probes and controls. found to not be a significant problem because the current 0037. In one embodiment, a heat source may be coupled catalytic converters used are capable of reducing these to the conduit coupling the vaporization chamber and the emissions to meet the emission requirements.

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0044. In addition to the reasons and discussion set forth Supplying fuel to a combustion chamber in a desired fuel above, applicants attribute Such improvements to a number amount;

of potential factors, some of which may include the follow mixing air with the fuel in a desired air amount to result 1ng: in a desired air to fuel ratio; and 0045 (1) The mixture of the air and vapor fuel is preheating the air prior to mixing with the fuel and prior relatively homogenous prior to entering the combustion to combustion.

chamber, thus a more consistent burning of the fuel and 2. The method of claim 1, wherein supplying the fuel improved flame speed may be achieved; includes injecting a liquid fuel into the combustion chamber 0046 (2) The temperature of the fuel/air mixture can and mixing the preheated air with the injected fuel in the be reduced in a port fuel injection system due to the combustion chamber.

energy required to vaporize the fuel. Vaporization out 3. The method of claim 1, wherein supplying the fuel side the combustion chamber, as practiced in the cur includes providing a vaporized fuel and mixing the air with rent invention, allows the fuel/air mixture time to the vaporized fuel prior to supplying the vaporized fuel to recover from this temperature drop. This higher tem the combustion chamber.

perature within the combustion chamber can then result 4. The method of claim 1, further comprising further in a higher flame speed and more efficient combustion. heating the mixture of the air and vaporized fuel prior to 0047. In recognizing and appreciating the improvements Supplying the mixture to the combustion chamber. resulting from heating the air, vapor, and/or a mixture of the 5. The method of claim 1, wherein the desired air to fuel two prior to entering the combustion chamber, led applicants ratio is approximately between 13.5:1 and 16:1. to discover that similar embodiments may be used with 6. The method of claim 1, wherein the desired air to fuel current fuel injection systems used in vehicles. Applicants ratio is greater than 15:1.

have been able to produce efficiency improvements in miles 7. An engine, comprising per gallon, albeit somewhat less that those realized with the a combustion chamber, vapor systems in accordance with embodiments of the a liquid fuel Source coupled to the combustion chamber present invention. and adapted to inject liquid fuel into the combustion 0.048. In various embodiments, air that is to be mixed with the injected liquid fuel in the combustion chamber may chamber; and be preheated prior to mixing. Such preheating can help an air source coupled to the combustion chamber and counter the temperature drop that may result when the liquid adapted to Supply a preheated air Supply to the com fuel is converted to a vapor. In such embodiments, the higher bustion chamber in order to achieve a desired air to fuel air/fuel temperature within the combustion chamber mixture.

increases the flame speed after ignition, which in turn may 8. The engine of claim 7, wherein the desired air to fuel help improve the efficiency of the system. ratio is approximately between 13.5:1 and 16:1. 0049 Again, embodiments of the invention can improve 9. A vapor fuel supply system for a combustion chamber, the fuel efficiency of vehicles, whether they use current comprising:

liquid fuel injection systems or use vaporized fuel systems. a vaporized fuel source coupled to the combustion cham Further embodiments may be used with a variety of different ber, the vaporized fuel Source including a vaporization air to fuel ratios ranging from systems running richer chamber and a liquid fuel heat Source adapted to mixtures at or below the standard ratio to systems running generate the vaporized fuel; the standard ratios of about 14:1 to systems running leaner one or more air sources coupled to the system and adapted mixtures that may be as high as more than 30:1. to provide an air supply to the vaporized fuel to form 0050 Although certain embodiments have been illus a desired air to fuel mixture ratio; and trated and described herein for purposes of description of the wherein the mixture is of a temperature that is at or above preferred embodiment, it will be appreciated by those of the vaporization temperature of the liquid fuel prior to ordinary skill in the art that a wide variety of alternate and/or combustion.

equivalent embodiments or implementations calculated to achieve the same purposes may be substituted for the 10. The vapor fuel supply system of claim 9, wherein the embodiments shown and described without departing from desired air to fuel ratio is approximately between 13.5:1 and the scope of the present invention. Those with skill in the art 16:1.

will readily appreciate that embodiments in accordance with 11. The vapor fuel supply system of claim 9, wherein the the present invention may be implemented in a very wide air source is adapted to Supply heated air prior to mixing variety of ways. This application is intended to cover any with the vaporized fuel.

adaptations or variations of the embodiments discussed 12. The vapor fuel supply system of claim 9, further herein. Therefore, it is manifestly intended that embodi comprising a mixture heat Source adapted to heat the mix ments in accordance with the present invention be limited ture prior to combustion.

only by the claims and the equivalents thereof. 13. The vapor fuel supply system of claim 9, wherein the What is claimed is: desired air to fuel ratio is greater than 15:1. 1. A method for improving fuel efficiency of combustion engines, comprising: k k k k k