Abstract:
A fuel vaporizer system for an internal combustion engine including a first closed chamber defining a first volume, the first closed chamber having a heat transfer surface; a second closed chamber at least partially surrounding the first closed chamber and defining a second volume; and a third closed chamber at least partially surrounding the second closed chamber and defining a third volume. A liquid fuel supply system including a liquid fuel supply line emits fuel into the first volume in an expanding pattern of liquid fuel spray from at least one orifice. A thermal fluid system from said engine is configured to circulate fluid, which may be engine coolant, through the second volume and transfer heat from the fluid through the first closed chamber and vaporize said liquid fuel. An exhaust system from said engine is configured to circulate exhaust through the third volume and transfer heat from the exhaust through the second closed chamber and heat said fluid. A vaporized fuel outlet is configured to direct vaporized fuel from the first closed chamber to supply fuel to at least one combustion region of the internal combustion engine via a combustion fuel supply line.

Description:
CROSS REFERENCE 
       [0001]    This application claims priority to U.S. Utility patent application Ser. No. 12/791,624, filed Jun. 1, 2010, which claims priority to U.S. Utility patent application Ser. No. 12/652,986, filed Jan. 6, 2010, now U.S. Pat. No. 7,886,725, and U.S. Provisional Patent Application Ser. No. 61/251,913, filed Oct. 15, 2009, all incorporated in their entireties herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates generally to a system that transforms liquid fuel into fuel vapor in order to improve combustion in internal combustion engines. 
         [0004]    2. Description of the Related Art 
         [0005]    The manner in which fuel is provided to an engine significantly affects both fuel efficiency and exhaust emissions. In a piston engine with a carburetor, liquid gasoline is introduced centrally to a flow of combustion air, following which the air-fuel mixture is divided and distributed to the engine cylinders. In a piston engine with fuel injectors at the cylinders, pressurized liquid fuel is forced through nozzles of the injectors to inject sprays of liquid fuel particles. The sprays are injected into combustion air at the inlet ports of the cylinders or directly into the combustion regions. Incomplete combustion of the fuel in these and other engines detrimentally affects fuel economy and produces harmful emissions. 
         [0006]    Over many decades, suggestions have been made to pre-vaporize fuel as a way to improve fuel efficiency and decrease emissions of internal combustion engines. 
         [0007]    Cooke (U.S. Pat. No. 5,746,188) and Shetley (U.S. Pat. No. 6,758,194) illustrate examples of fuel vaporization systems using electric heating elements. 
         [0008]    Notwithstanding the foregoing, there is considerable room to improve fuel efficiency and decrease emissions in internal combustion engines. 
         [0009]    It would be desirable to provide a fuel economizer fuel vapor system that may be adapted for new vehicles and may be adapted to add to existing vehicles. 
         [0010]    Additionally, it would be desirable to provide a fuel economizer fuel vapor system that includes a specially designed pressurized container for vaporization of liquid gasoline. 
         [0011]    Additionally, it would be desirable to provide a closed loop fuel vapor system that restricts entry of atmospheric air therein. 
       SUMMARY OF THE INVENTION 
       [0012]    A fuel vaporizer system for an internal combustion engine comprises: a first closed chamber defining a first volume, said first closed chamber having a heat transfer surface; a second closed chamber at least partially surrounding the first closed chamber and defining a second volume; and a third closed chamber at least partially surrounding the second closed chamber and defining a third volume. A liquid fuel supply system comprising a liquid fuel supply line emits fuel into the first volume in an expanding pattern of liquid fuel spray from at least one orifice. A thermal fluid system from said engine is configured to circulate fluid, which may be engine coolant, through the second volume and transfer heat from the fluid through the first closed chamber and vaporize said liquid fuel. An exhaust system from said engine is configured to circulate exhaust through the third volume and transfer heat from the exhaust through the second closed chamber and heat said fluid. A vaporized fuel outlet is configured to direct vaporized fuel from the first closed chamber to supply fuel to at least one combustion region of the internal combustion engine via a combustion fuel supply line. 
         [0013]    The first closed chamber may be a pressure chamber having a cylindrical center, an upper spherical end, and a lower spherical end. The at least one orifice may be proximate the upper spherical end. The at least one orifice may be spaced from the heat-transfer surface. The heat transfer surface may comprise a wall, and may further comprise a member of increased surface area in thermal communication with a wall of the first closed chamber. The vaporized fuel outlet may be located proximate the upper end of the first closed chamber. 
         [0014]    The fuel vaporizer system may further comprise a pressure relief configured to open when pressure inside the first closed chamber exceeds a predetermined threshold and to direct vaporized fuel to the liquid fuel supply system. The fuel vaporizer system may further comprise a valve in the exhaust system configured to open when the fluid is below a predetermined temperature to allow exhaust to circulate through the third closed chamber and close when the fluid is at or above a predetermined temperature to prevent exhaust from circulating through the third closed chamber. The fuel vaporizer system may further comprise a liquid fuel bypass configured to allow liquid fuel to pass from the liquid fuel supply line to the combustion fuel supply line. The liquid fuel bypass may be configured to be opened only when the first closed volume cannot supply sufficient vaporized fuel to satisfy demands of the internal combustion engine. The fuel vaporizer system may further comprise a liquid fuel return drain outlet configured to return non-vaporized fuel to the liquid fuel supply system. 
         [0015]    Fuel may be supplied to at least one combustion region of an internal combustion engine through a method comprising: circulating exhaust through an exhaust chamber that at least partially surrounds a fluid chamber; transferring heat from the exhaust to the fluid chamber; circulating a fluid through the fluid chamber, which at least partially surrounds a vapor chamber; transferring heat from the fluid to the vapor chamber; supplying substantially liquid fuel to the vapor chamber via a liquid fuel supply line; vaporizing the substantially liquid fuel in the vapor chamber to create a super-atmospheric pressurized fuel vapor; and expelling the super-atmospheric pressurized fuel vapor from the vapor chamber to a combustion chamber fuel supply line. The method may further comprise opening a pressure relief valve and directing vaporized fuel to the liquid fuel supply line if pressure in the vapor chamber exceeds a predetermined threshold. The method may further comprise ensuring sufficient fuel to meet fuel demands of the combustion region by receiving an electrical signal at a liquid fuel bypass valve if the super-atmospheric pressurized fuel vapor from the vapor chamber is not sufficient to meet fuel demands of the combustion region; opening, at least partially, the liquid fuel bypass valve upon receiving the signal; and bypassing, at least partially, the vapor chamber by diverting liquid fuel from the liquid fuel supply line to the combustion chamber fuel supply line through the liquid fuel bypass valve. The method may further comprise measuring the fluid&#39;s temperature upon entering the fluid chamber and closing a valve if the temperature exceeds a predetermined threshold, where closing the valve stops the exhaust from circulating through the exhaust chamber. 
         [0016]    The details of selected designs within the scope of the invention are set forth in the accompanying drawings and the description below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a simplified schematic illustration of a fuel vapor system of the present invention in relation to an internal combustion engine and its fluid coolant system and exhaust system; 
           [0018]      FIG. 2  is a cross-sectional view of a fuel vaporizer system for an internal combustion engine according to an exemplary embodiment of the present invention; 
           [0019]      FIG. 3  is a cross-sectional view of a fuel vaporizer system for an internal combustion engine according to another exemplary embodiment of the present invention; and 
           [0020]      FIG. 4  is a simplified schematic illustration of a fuel system including a fuel vaporizer system according to an exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    The embodiments discussed herein are merely illustrative of specific manners in which to make and use this invention and are not to be interpreted as limiting in scope. 
         [0022]    While the invention has been described with a certain degree of particularity, it is to be noted that many modifications may be made in the details of the invention&#39;s construction and the arrangement of its components without departing from the spirit and scope of this disclosure. It is understood that the invention are not limited to the embodiments set forth herein for purposes of exemplification. 
         [0023]    Preferred embodiments of the present invention are illustrated in  FIGS. 1 through 4  wherein engine coolant is used to heat a vapor chamber and exhaust is available to heat the engine coolant.  FIG. 1  illustrates a simplified schematic of the present invention in relation to a known internal combustion engine and its fluid coolant system and exhaust system. 
         [0024]    A vapor chamber  900  (to be described in detail below) is at least partially surrounded by a coolant chamber  905  (to be described in detail below), which in turn is at least partially surrounded by an exhaust chamber  1100 . In known liquid cooled internal combustion engines, a liquid such as a coolant is delivered to and through channels running through the engine and cylinder head. The liquid may be water but is commonly a mixture of water and anti-freeze, such as ethylene glycol or propylene glycol. Fluid coolant from a vehicle thermal fluid system is circulated from an internal combustion engine  800  through a radiator  805  and then returned to the engine. The fluid coolant is also circulated from the engine  800  into the coolant chamber  905 . After passing through the coolant chamber, the coolant fluid is returned to the engine  800 . The coolant is circulated in a closed loop through the coolant system by a pump  810 . 
         [0025]    The coolant is thereafter delivered and returned to and through the radiator  805 , so that heat is transferred from the fluid inside to the atmospheric air outside. A pump, such as a centrifugal pump  810 , circulates the coolant through the system. The coolant operates in a closed system and is recirculated. 
         [0026]    The internal combustion engine  800  also produces exhaust as a result of fuel combustion. The exhaust is discharged from the internal combustion engine  800  into the atmosphere through an exhaust system  815 . The exhaust may be circulated from the engine  800  into the exhaust chamber  1100 . Whether exhaust is circulated into the exhaust chamber  1100  or bypasses, the exhaust chamber  1100  may be regulated by a valve  1105 . Valve  1105  may be an ERG valve. 
         [0027]    In the embodiment illustrated in the sectional view of  FIG. 2 , a vapor chamber  900  is at least partially surrounded by a coolant chamber  905  thereby creating a coolant cavity  910 . The coolant chamber  905  is at least partially surrounded by the exhaust chamber  1100  thereby creating an exhaust cavity  1110 . 
         [0028]    In a preferred embodiment in  FIG. 2 , relatively hot liquid coolant from the engine enters through a coolant inlet  915  into the coolant cavity  910  as shown by arrow  917 , flows around the exterior of the vapor chamber  900 , and exits the coolant cavity  910  at a coolant exit  920 . The hot coolant serves to heat the vapor chamber  900  by transferring heat from the coolant to the relatively cooler vapor chamber  900 . As the fuel inside the vapor chamber is heated, the fuel will expand and be converted to its gaseous form. The vapor chamber  900  is a closed pressure vessel and preferably is designed with a cylindrical center and a pair of spherical ends for optimal strength. 
         [0029]    When the coolant is not hot, such as upon starting the engine, the valve  1105  allows relatively hot exhaust from the engine to enter through an exhaust inlet  1015  into the exhaust cavity  1110  as shown by arrow  1117 , flow around the exterior of the coolant chamber  905 , and exit the exhaust cavity  1110  at an exhaust exit  1120 . The hot exhaust serves to heat the coolant chamber  905  by transferring heat from the exhaust to the relatively cooler coolant chamber  905 , effectively heating the coolant inside the coolant chamber  905  and allowing the coolant to, in turn, heat the vapor chamber  900  as described above. When the coolant is sufficiently hot, the valve  1105  may prevent exhaust from circulating through the exhaust chamber  1100 . 
         [0030]    In various embodiments, the exterior of the vapor chamber  900  may include fins or other surface-enhancing elements (not shown) to increase the amount of heat transfer from the coolant to the vapor chamber  900 . Further, the vapor chamber  900  may be made of a material with a high thermal conductivity to promote heat transfer from the coolant through the walls of the vapor chamber  900  to the fuel in the vapor chamber  900 . The coolant chamber  905  may likewise be made of a material with a high thermal conductivity to promote heat transfer from the exhaust through the walls of the coolant chamber  905  to the coolant in the coolant chamber  905 . The exhaust chamber  1100  may be made of an insulative material or material with a low thermal conductivity to promote retention of heat within the exhaust chamber  1100 , further promoting heat transfer to the coolant chamber  905 . 
         [0031]    In the preferred embodiment of  FIG. 2 , the coolant may be drawn from a standard thermal fluid cooling system of a vehicle as is well known in the art, preferably when the coolant is at or near its highest temperature such as after passing through the engine and at or near the thermostat entering the radiator. Directing the highest temperature coolant available to the vaporize the fuel provides more efficient operation. 
         [0032]    Further to the embodiment illustrated in  FIG. 2 , a fuel inlet  925  for the vapor chamber  900  may include a spray nozzle  927 . The force of the existing fuel pump (not shown) of the internal combustion engine moves fuel into the vapor chamber  900 . Fuel entering the vapor chamber is substantially liquid in form. Application of heat will cause the liquid fuel to be converted to gaseous form. After vaporization, vaporized fuel outlet  930  is provided to allow vaporized fuel to exit the vapor chamber  900  for supplying to at least one combustion region of an internal combustion engine  800 . The vaporized fuel outlet  930  is shown as being at the same end of the vapor chamber  900  as the fuel inlet  925  so that the vaporized fuel outlet is not generally aligned with the fuel inlet along the direction in which fuel is injected. This arrangement helps to promote recirculation of fuel vapor in the vapor chamber before the vapor exits the chamber through the vaporized fuel outlet  930 . 
         [0033]    A baffle  935  or baffles may be provided to discourage newly injected, substantially liquid fuel from being expelled through the vaporized fuel outlet  930 . The baffle  935  may further serve as a heat sink to aid in the vaporization of the new fuel entering through the fuel inlet  925 . 
         [0034]    In at least one non-limiting embodiment, approximately 150 lbs of pressure is generated within the vapor chamber by expansion of the fuel into its gaseous form. 
         [0035]    A drain or liquid fuel outlet  940  may be provided in the vapor chamber  900  to allow any liquid fuel which is not vaporized to exit the vaporization volume  901 . Liquid fuel remaining in the vapor chamber  900  may be detrimental to the generation of vapor in the chamber  900  as the liquid fuel may absorb heat from the coolant and the liquid fuel compromises the volume available for the fuel entering the vapor chamber to be vaporized. The liquid fuel drain outlet  940  is preferably at the base of the vapor chamber  900  so that any liquid will migrate to the base by gravity. The liquid fuel outlet  940  may be controlled by a valve (not shown). The liquid fuel drain outlet  940  may be isolated from the coolant cavity  910  by a cylindrical shield  945  to prevent any exiting liquid fuel from further removing heat from the system. The liquid fuel removed from the vapor chamber  900  may be returned to the fuel tank or to the fuel line supplying the vaporizer as shown by line  947 . 
         [0036]    A secondary drain outlet  949  controlled by a valve may also be provided to remove liquid fuel. 
         [0037]    Another exemplary embodiment of the present invention is illustrated in the cross sectional view in  FIG. 3 . A vapor chamber  950  is substantially surrounded by a coolant chamber  955  forming a coolant cavity  960 . The coolant cavity  960  includes both a coolant inlet  965  and a coolant outlet  970 . The coolant chamber  955  is substantially surrounded by an exhaust chamber  1155  forming an exhaust cavity  1160 . The exhaust cavity  1160  includes both an exhaust inlet  1165  and an exhaust outlet  1170 . The illustrated embodiment further includes a fuel inlet  975 , shown with a spray nozzle, a vaporized fuel outlet  980  for supply to at least one combustion region as shown by arrow  983 , and a liquid fuel drain outlet  985  for return to the fuel system. 
         [0038]    A heat-exchange element  990  promotes efficient heat transfer between the vapor chamber  950  and the incoming fuel spray. The heat-exchange element  990  may be mesh or a finned member, but generally includes a region of greater surface area than would be available without the heat exchange element  990 . The increased surface area provides a heat-exchange surface available to the incoming fuel surface providing more complete and efficient vaporization of the liquid fuel. The heat-exchange element may be of any material but is preferably of a material with a high thermal conductivity to promote heat exchange between the vapor chamber  950  wall and the heat-exchange element  990 . 
         [0039]    The fuel vaporization system of the present invention may further include provisions to ensure that the combustion regions are adequately supplied with fuel under varying conditions, such as cold start and heavy load scenarios. 
         [0040]      FIG. 4  is a schematic illustration of an additional exemplary embodiment of the present invention including exempt cold-start and high load provisions. Electrical paths are represented by dashed lines  996  while fluid paths are represented by solid lines  998 . The vaporizer system  1000  represented diagrammatically includes a coolant inlet  1005  and a coolant outlet  1010 , as well as an exhaust inlet  1180  and an exhaust outlet  1190 . 
         [0041]    The vaporizer  1000  further includes a liquid fuel inlet  1015  as shown by arrow  1017  and a vaporized fuel outlet  1020  as shown by arrow  1019 . A drain or liquid fuel outlet  1022  may be included. Liquid fuel is supplied from the fuel tank via a fuel line  1025  and a fuel line  1030  supplies fuel in liquid and/or vapor form to at least one combustion region of an engine  800 . A high-load liquid fuel and cold start liquid fuel by-pass valve  1045  are illustrated. 
         [0042]    Referring again to  FIG. 4 , under normal operating conditions (i.e., the engine coolant is at operating temperature, the engine under normal load conditions) the heated engine coolant enters the vaporizer system through the coolant inlet line  1005  and exits the vaporizer system through the coolant outlet line  1010 . The liquid fuel is introduced from the fuel tank, along the liquid fuel line  1025 , through a valve  1085 , and into the vaporizer liquid fuel inlet  1015 . Vaporized fuel exits the vaporizer chamber at the vaporized fuel outlet  1020 , through a valve  1055 , and to the at least one combustion region of the engine through the fuel line  1030 . 
         [0043]    With the engine under cold start conditions, the temperature sensor  1070  in communication with the coolant circulating into the vaporizer chamber  1000  indicates that the coolant is not at the normal operating temperature, generally between 180° F. and 220° F. An electrical signal is sent from the temperature sensor  1070  to the cold-start liquid fuel bypass valve  1045  opening the valve, allowing liquid fuel to pass from the fuel line  1025  to line  1030  in liquid form to ensure the at least one combustion region receives the necessary fuel for proper operation. Further, when the coolant temperature is below normal operating temperature, the temperature sensor  1070  sends a signal to the valve  1085  and valve  1055  to close, or to remain closed. This prevents liquid fuel from entering the vaporizer chamber which would fill the vaporizer with liquid fuel and delay or prevent the vaporizer from reaching the temperature necessary to vaporize the fuel. Alternately, when the temperature sensor  1070  indicates that the coolant is not at the normal operating temperature, the valve  1105  opens, allowing exhaust to enter the vaporizer system through the exhaust input line  1180  and exit the vaporizer system through the exhaust outlet line  1190 . 
         [0044]    While operating under normal conditions as defined above, an internal combustion engine  800  may experience demand for high power, which may occur in a vehicle engine while accelerating, passing, or going uphill or in a generator engine when the wattage demand is increased by an added electrical load. Under these conditions, an instantaneous spike in fuel demand may not be sufficiently accommodated by a vaporizer chamber sized for optimum efficiency for the application; therefore additional fuel may be required. As shown in  FIG. 4 , a high-load liquid fuel bypass valve  1040  is provided to allow liquid fuel to pass the vaporizer  1000  sending liquid fuel from fuel line  1025 , through the high-load liquid fuel by-pass valve  1045 , and through fuel line  1030  to the combustion region. In such a scenario, valve  1085  and valve  1055  may or may not be closed as the liquid fuel bypassing through valve  1045  may supplement the vaporized fuel produced by the vaporizer. The high-load liquid fuel bypass valve control signal  1080  may be provided by an electrical signal from a control module, such as from a vehicle&#39;s power control module (PCM) or a generator&#39;s engine controller, or a vacuum switch using increased intake manifold vacuum as an indication of increased power demand. 
         [0045]    Referring again to the schematic diagram of  FIG. 4 , after the vaporizer system has been operating at steady-state operating temperatures for a time, the vaporizer will retain a significant amount of heat. When the engine is turned off, the coolant flow to the vaporizer may also cease, though generation of vapor within the chamber may continue for some time, particularly if any fuel puddling had previously occurred within the vapor chamber. In the illustrated example, a blow-off valve  1050  is provided to allow excess pressure built up in the vaporizer chamber to be returned safely to the fuel system while limiting the maximum pressure in the vapor chamber. A fuel-pressure regulator  1075  may provide a signal to a valve, or the valve may be configured to open upon reaching a pre-determined threshold pressure. 
         [0046]    Whereas, the present invention has been described in relation to the drawings attached hereto, it should be understood that other and further modifications, apart from those shown or suggested herein, may be made within the spirit and scope of this invention.