Abstract:
A fuel vaporizer for an internal combustion engine having a closed pressure chamber defining a volume, to be heated, and a liquid fuel supply system disposed to emit a liquid fuel spray. The closed pressure chamber may be constructed and arranged relative to the heat-transfer surface to establish between the at least one outlet and the heat-transfer surface a mixing domain in which the fuel spray, as it progresses through the volume from the outlet, is substantially heated and vaporized by mixing with re-circulated, heated fuel vapor that previously has moved over and received heat from the heat transfer surface. The fuel vaporizer may be associated with a vapor outflow passage through which pressurized vapor exits the closed pressure chamber for supply to said at least one combustion region. The heat-transfer surface may be arranged to be heated by engine coolant circulating around the exterior of the closed pressure chamber.

Description:
CROSS-REFERENCE 
     This application claims priority to U.S. Utility patent application Ser. No. 12/652,986, filed Jan. 6, 2010, and U.S. Provisional Patent Application Ser. No. 61/251,913, filed Oct. 15, 2009, both incorporated in their entireties herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a system that transforms liquid fuel into fuel vapor in order to improve combustion in internal combustion engines. 
     2. Prior Art 
     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. 
     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. 
     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. 
     Notwithstanding the foregoing, there is considerable room to improve fuel efficiency and decrease emissions in internal combustion engines. 
     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. 
     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. 
     Additionally, it would be desirable to provide a closed loop fuel vapor system that restricts entry of atmospheric air therein. 
     SUMMARY OF THE INVENTION 
     A fuel vaporizer for an internal combustion engine includes a first closed chamber defining a first volume, a heat transfer surface within the first closed chamber, a second closed chamber at least partially surrounding the first closed chamber defining a second volume, a liquid fuel supply system comprising a liquid fuel supply line, and a fuel spray nozzle disposed to emit into the first volume under super-atmospheric pressure an expanding pattern of liquid fuel spray. A thermal fluid system introduces heated fluid into the second volume and transfers heat from the heated fluid through the first closed chamber. A vaporized fuel outlet is configured to direct vaporized fuel from the first closed chamber to a combustion fuel supply line that supplies fuel to at least one combustion region of the engine. 
     In some embodiments, the heat transfer surface of the first closed chamber is a wall of the first closed chamber. Optionally, the heat transfer surface may be a member of increased surface area that is in thermal communication with the wall of the first closed chamber. 
     The vaporizer system may also include an optional pressure relief valve that may be configured to open when the pressure inside the first closed chamber exceeds a predetermined threshold and direct vaporized fuel to the liquid fuel supply system. 
     The present invention also provides a method of supplying fuel to at least one combustion region of an internal combustion engine including introducing heated coolant fluid into a volume, the volume at least partially surrounding a vapor chamber, transferring heat from the heated coolant fluid to the vapor chamber, supplying fuel to the vapor chamber via a liquid fuel supply line, emitting into the vapor chamber a substantially liquid fuel at super-atmospheric pressure, vaporizing the substantially liquid fuel in the vapor chamber, and expelling the vaporized fuel from the vapor chamber to a combustion chamber fuel supply line. 
     The present invention may further include the steps of receiving, at a liquid fuel bypass valve, a signal indicating that the vaporized fuel from the vapor chamber is not sufficient to meet the fuel demands of the combustion region of the engine, at least partially opening the liquid fuel bypass valve, and bypassing the vapor chamber by diverting liquid fuel from the liquid fuel supply line to the combustion chamber fuel supply line. The present invention may also include returning liquid fuel from the vapor chamber to the liquid fuel supply line. Further methods may include opening a pressure relief valve upon the pressure in the vapor chamber exceeding a predetermined threshold. 
     The present invention may include a fuel vaporizer for an internal combustion engine comprising a closed pressure chamber defining a volume, a heat transfer surface associated with the volume to be heated, and a liquid fuel supply system to emit into the volume under super-atmospheric pressure an expanding pattern of liquid fuel spray from at least one orifice, the liquid fuel supply system emitting fuel into the volume for vaporization. The closed pressure chamber may be constructed and arranged relative to the heat-transfer surface to establish between the at least one outlet and the heat-transfer surface a mixing, in which the fuel spray, as it progresses through the volume from the outlet, is substantially heated and vaporized by mixing with heated fuel vapor that previously has moved over and received heat from the heat transfer surface. Through a vapor outflow passage, pressurized vapor exits the closed pressure chamber for supply to said at least one combustion region. The heat-transfer surface may be arranged to be heated at least partially by a fluid coolant circulating around the exterior of the closed pressure chamber. 
     The present invention may further include a second closed chamber that at least partially surrounds the closed pressure chamber and defines a volume through which the engine coolant is circulated. The engine coolant entering through an engine coolant inlet is or a higher temperature than an engine coolant exiting through the engine coolant outlet. 
     The present invention may also include a flow control associated with the vaporizer outflow passage, the flow control including at least one fuel vapor spray nozzle communicating directly or indirectly with at least one combustion region adapted to be actuated in response to requirements, the fuel vaporizer constructed and arranged to enable flow of pressurized fuel vapor to the engine while maintaining substantial super-atmospheric pressure within the volume in which the vapor is generated. 
     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 
         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; 
         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; 
         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 
         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 PREFERRED EMBODIMENTS 
     The embodiments discussed herein are merely illustrative of specific manners in which to make and use the invention and are not to be interpreted as limiting the scope of the instant invention. 
     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 is not limited to the embodiments set forth herein for purposes of exemplification. 
     Preferred embodiments of the present invention are illustrated in  FIGS. 1 through 4  wherein engine coolant is used to heat a vapor chamber.  FIG. 1  illustrates a simplified schematic of the present invention in relation to a known internal combustion engine and fluid coolant system. 
     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). 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 . 
     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. 
     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 . 
     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. 
     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 to the fuel in the vapor chamber. The coolant chamber  905  may be made of an insulative material or material with a low thermal conductivity to promote retention of heat within the coolant chamber  905 , further promoting heat transfer to the vapor chamber  900 . 
     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. 
     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 . 
     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 . 
     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. 
     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 . 
     A secondary drain outlet  949  controlled by a valve may also be provided to remove liquid fuel. 
     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 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. 
     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 . 
     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. 
       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 . 
     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. 
     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 . 
     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. 
     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 up hill 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. 
     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. 
     Fuel efficiency and gas mileage were tested on three separate vehicles over a period of five months utilizing the present invention. In each case, addition of the present invention to the internal combustion engine of each vehicle resulted in increases in the miles per gallon of over 125%. 
     Recent testing of emissions from vehicles utilizing the present invention show marked improvement in the following areas of governmental emissional requirements—lowered hydrocarbon (HC) content of at least 25%, lowered nitrous oxide (NOx) content of at least 70% and raised oxygen (O 2 ) content of at least 75%. 
     As shown on the chart below, the emissions of nitrous oxide and hydrocarbon resulting from testing were significantly reduced. 
     
       
         
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
               
               
                 Emissions: 
                 Vapor System 
                 Raw Gasoline 
                 Improvement 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 NOx (Nitrous-Oxide) 
                 42 
                 ppm 
                 158 
                 ppm 
                 73.4% 
               
               
                 HC (Hydro-Carbon) 
                 6 
                 ppm 
                 8 
                 ppm 
                   25% 
               
               
                 O2 
                 .08 
                 ppm 
                 .39 
                 ppm 
                 79.5% 
               
               
                 Co2 
                 14.28 
                 ppm 
                 14.06 
                 ppm 
                   (0%) 
               
               
                   
               
             
          
         
       
     
     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.