Abstract:
An improved carburetor arrangement includes a low-capacity fuel/air regulator for efficiently vaporizing rich mixtures of fuel and delivering them to a heat exchange vaporizer for heating and completely vaporizing the rich mixture prior to delivery to an engine intake. An existing conventional fuel atomization system is eliminated and replaced with main combustion air gallery. The air gallery forms a low pressure for drawing heated rich mixture from the vaporizer and subsequently mixing it with a larger amount of incoming fresh air from the gallery for forming a stoichiometric mixture. Preferably the mixture is passed through a mixing chamber before delivery to the engine intake. Preferably the fuel/air regulator is a low-capacity carburetor, such as that used for motorcycles, snowmobiles and the like.

Description:
FIELD OF THE INVENTION 
     The present invention relates to an arrangement incorporating a carburetor discharging a rich fuel mixture to a heat exchange vaporizer prior to mixing with main combustion air for fueling an engine. More particularly, the vaporizer utilizes waste heat from the exhaust of the engine. 
     BACKGROUND OF THE INVENTION 
     It is known that gasoline-type internal combustion engines consume a significant amount of gas and produce noxious emissions. Such engines typically utilize a conventional carburetor or fuel injection systems. Such systems require a liquid fuel which is atomized and mixed with air to render it suitable for combustion. Carbureted or injected systems further dictate the proportions of gasoline and air required for varying engine operation. Such systems provide the desired amount of gasoline and air for conditions including normal driving, acceleration, hill climbing and sustaining speeds. 
     Successful and complete vaporization of the liquid fuel has been a goal sought by many. Incomplete vaporization result in raw liquid being ingested into the engine&#39;s combustion chamber resulting in poor efficiency and pollution. This situation is further exacerbated in low operations such as under low engine speed where air flow is low and energy to vaporize fuel is lowest. Fuel injection has gone a long way to maximize atomization, however there has been little relief for the large number of carbureted vehicles still in service. 
     In the group of carbureted fuel delivery systems, there have been attempts to maximize vaporization through means other than mere atomization and mixing with the stream of combustion air. Such technology includes that disclosed in U.S. Pat. No. 4,469,077 to Wooldridge illustrates a carburetor in which the entire fuel and air mixture is sent through an exhaust gas heat exchanger prior to reaching the engine rich mixture intake. The carburetor is conventional with only the resulting mixture being piped from the carburetor, to the heat exchanger adjacent the exhaust and back to the intake engine. 
     Further, in U.S. Pat. No. 5,140,966 to Wong, fuel enters a reservoir upon which an ultrasonic plate vaporizes the fuel and a fan blows a small amount of air and the fuel vapor through a heat exchanger heated by exhaust gas. The resulting heated fuel and air is finally commingled with a main air steam before reaching the engine&#39;s intake. Both ultrasonic agitation and heat are used to improve fuel vaporization and are located remote from the engine intake. 
     Prior art systems are characterized by independent, large and expensive systems for adapting existing carburetors or replacing carburetors. 
     There is a demonstrated need for a carburetor which is capable of substantially complete vaporization of the liquid fuel and resulting in even distribution between engine cylinders so as to completely burn the fuel mixture, reduce emissions and reduce liquid fuel consumption. 
     SUMMARY OF THE INVENTION 
     An improved carburetor arrangement is provided which improves gas mileage and decreases exhaust emissions. The arrangement is suitable for fitting to substantially any gasoline-burning engine. The arrangement vaporizes substantially all elements in the fuel, and then forming a nearly perfect mix of vapor and air resulting in a balanced distribution to each combustion chamber of the engine. In a preferred arrangement, the vaporizer, the mixing chamber and heat control are all assembled into one unit, fit directly to the intake manifold. As a result, gas mileage is improved, oil stays cleaner longer, engine runs cooler, and fuel emissions are almost nil. As a result of the cooler running engine and cleaner oil the wear and tear on the engine is less and the life of the engine should be longer. 
     The carburetor arrangement comprises a heat exchanger or vaporizer which conditions the fuel to produce the maximum allowable power and a minimum amount of emissions. One disadvantage in the prior art, as pointed out by Wooldridge, is that conventional carburetors are inefficient at lower fuel demands; lower fuel demand being exactly the objective when reducing gas consumption in a stock power train. The present arrangement uses a low-capacity fuel/air regulator or carburetor for efficiently vaporizing rich mixtures of fuel and subsequently later mixing the rich mixture with more air to obtain stoichiometric amounts for combustion. The rich mixture is fed into the vaporizer to allow this small amount of air and fuel to be heated and completely vaporized. Simply, the low-capacity carburetor allows this efficiently mixed, rich vapor to be heated for subsequent mixing with a larger amount of incoming fresh combustion air, at a regulated amount, and which is then which distributed. The main air and rich mixture preferably pass through a mixing chamber before the engine intake. Further, the carburetor arrangement is conveniently and simply contained in one sealed annular unit which connects to the engine intake at the conventional intake manifold. 
     In a broad aspect of the invention, a carburetor arrangement is provided for admitting fuel and stoichiometric amounts of air to an engine having an engine fuel mixture intake having a throttle regulator and discharging hot exhaust gas, the carburetor arrangement comprising: a main combustion air gallery connected to the engine intake having a main air regulator for admitting a substantially stoichiometric amount of air; a vaporizer having an exhaust gas passage therethrough connected to the engine&#39;s exhaust gas, and a fuel passage therethrough and having a fuel intake and a rich mixture discharge into the main combustion air gallery, the exhaust and fuel passages being isolated by a heat exchange barrier; and a fuel/air regulator connected to the fuel intake, the fuel/air regulator metering fuel and a carrier air into the fuel passage, the amounts of carrier air being less than a stoichiometric amount and only enough to carry the fuel through the fuel passage to the main air gallery. 
     Preferably the fuel/air regulator is a low-capacity carburetor, such as that used for motorcycles and snowmobiles. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates a side cross-sectional view of one embodiment of the present invention; 
     FIG. 2 illustrates a plan cross-sectional view of the arrangement according to FIG. 1; 
     FIG. 3 illustrates a side view of an embodiment of the present invention adapted to a V-8 gasoline-fueled internal combustion engine; 
     FIG. 4 illustrates a plan view of the arrangement of FIG. 3; 
     FIG. 5 is a side cross sectional view of an exhaust diverter for intercepting exhaust gas and directing; 
     FIGS. 6 a  and  6   b  are schematic diagrams of two embodiments of the invention wherein the heat exchanger is concentric about the main air gallery and remote therefrom respectively; and 
     FIGS. 7 a - 7   c  are various embodiments of the throttle and rich fuel mixture exit to main air gallery. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to FIG. 1, an engine  10  has an intake  11  which is fit with one embodiment of a carburetor arrangement  12 . A flow of a hot vaporized fuel  13  and stoichiometric air  14  is regulated as a mixture  17  through an intake throttle regulator  15  and throttle body  16 . The throttle regulator  15  is illustrated in a partially-throttled orientation. 
     The stoichiometric fuel/air mixture  17  to the engine intake  11  is a result of the action of the novel carburetor arrangement  12  which comprises a main combustion air gallery  20  connected to the engine intake  11 ; a heat exchanger or vaporizer  21 ; and a fuel/air regulator  22  (best seen in FIGS. 3 and 4 connected through a flange to the vaporizer. 
     The fuel/air regulator is a conventional low-capacity carburetor for precise control and metering of a rich mixture of fuel  24   a  and a carrier air  24   b  as a rich mixture  25  through a fuel passage  26  into the vaporizer  21 . The amounts of carrier air  24   b  admitted through the fuel/air regulator  22  are less than a stoichiometric amount normally required for operation of the engine  10 , relying instead upon on commingling with a majority of main combustion air  14  being admitted through the main air gallery  20 . Commingled air from the main air gallery  14   v  and the carrier air supply  24   b  stoichiometric amounts of air for the operation of the engine  10 . 
     The carrier air  24   b  from the fuel/air regulator  22  is sufficient to carry the rich fuel mixture  25  through the fuel passage  26 . The engine intake  11  is provided with a 300-micron stainless steel screen  30  as a precautionary measure for arresting and flame or flareback. 
     With reference to FIGS. 1 and 2, the vaporizer  21  is a heat exchanger that enables transfer of heat from hot engine exhaust gases  31  to the cooler rich fuel mixture  25 . One embodiment of the vaporizer  21  comprises an annular fuel chamber  32  fit about the main air gallery  20  (See also FIG. 6 a ). Another embodiment finds the vaporizer  21  located adjacent yet separate from the main air gallery  20  (See FIG. 6 b ). The fuel chamber  32  has an inlet flange  23  for connection to the fuel/air regulator  22  for forming the rich fuel mixture  25  which flows into the fuel chamber  32 . The fuel chamber  32  also has an exit  33 , preferably annular, into the main air gallery  20 . 
     Within the fuel chamber  32 , and also preferably formed about the main air gallery  20 , is formed an independent hot exhaust chamber  34  for giving up heat to the fuel chamber  32 , yet remaining sealed therefrom. The exhaust chamber  34  is provided with a plurality of parallel fuel tubes  35  passing independently therethrough and spaced circumferentially about the gallery  20 . Hot exhaust gas  31  enters the exhaust chamber  34  at a tangential exhaust inlet  36  and circulates about the fuel tubes  35 , exiting at a tangential and opposing exhaust exit  37  for return to the engine  10 . The orientation of the exhaust inlet and exit  36 , 37  can vary, however with the objective to maximize contact of hot exhaust gas  31  and the surface area provided by the fuel tubes  35 . The fuel tubes  35  are open to the fuel chamber  32  at a feed head  38  to admit the cool rich fuel mixture  25  and are open at a discharge head  39  to collect a hot rich fuel mixture  13  from each tube  35 . 
     As illustrated in both FIGS. 1 and 2, the flow of rich fuel mixture  25  is preferably directed in through the fuel passage  26  to the fuel chamber  32 , around and down an outside annulus between the fuel and exhaust chambers  32 , 24  to the bottom of the fuel chamber  32  for distribution to each of the fuel tubes  35 . The rich fuel mixture  25  is then directed up the fuel tubes  35  for receiving conductive heat from the hot exhaust gases  31 . The discharge head  39  collects and directs the vaporized fuel  13  through the annular exit into the main air gallery  20 . This particular arrangement, having the hot rich fuel mixture  13  exiting adjacent the top of the vaporizer  21  aids in minimizing the height of main air gallery  20  and the carburetor arrangement  12  overall. 
     A main air sleeve  40  projects substantially concentrically into the main air gallery  20 . As the sleeve  40  is smaller in diameter than the main air gallery, the fuel chamber&#39;s annular exit  33  is formed for admitting hot vaporized fuel mixture  13  from the fuel chamber  21  and into the gallery  20 . The flow of the majority of the air  14  through the sleeve  40  and into main air gallery  20  forms a low pressure at the annular exit  33 , inducing and drawing the vaporized and hot rich fuel mixture  13  into the main air gallery. Other means for forming a draft or suction are possible as illustrated with a venturi arrangement shown in FIG. 7 c.    
     As shown in FIGS. 3-5, a hot exhaust pipe  50  from the engine  10  is connected to the exhaust chamber  34 . Means such as a “Y” junction  51  and diverter gate  52  (FIG. 5) control the flow of hot exhaust gases  31 . The diverter gate  52  is operable between a heating position (down in FIG. 5) where at least a portion of the hot exhaust  31  is diverted to the vaporizer  21 , and a bypassing position (up) where most exhaust gas  31  bypasses the vaporizer  31 . In the heating position, hot exhaust gas  31  circulates through the exhaust chamber  34  and around the tubes  35  for heating and vaporizing any rich fuel mixture  25  passing therethrough. Preferably, a substantially co-current heat exchange between hot exhaust gas  31  is formed through a flow of cool rich fuel mixture  25  up the inside of the tubes  35  and hot exhaust gas  31  up the outside of the tubes  35 . 
     With reference to FIGS. 3 and 4, the vaporizer  21  is adapted for connection to one or more exhaust manifolds  53  of the engine  10 . The amount of heat to the vaporizer  21  is controlled by the diverter gate  52  mounted in the exhaust pipe  50 . Ideally, the vaporized fuel mixture  25  is raised to a temperature of about 250° F. as measured at a probe  60  in the discharge head  39  as it leaves as hot vapor  13  at the top of the fuel tubes  35 . The vaporized fuel mixture  13  is then aspirated through the annular exit  33  and is mixed with warm, filtered main combustion air  14  to form a stoichiometric fuel mixture  17 . The amount of fresh air being mixed with the hot vapor is controlled by a feed butterfly valve  61  mounted inside sleeve  40 . The stoichiometric fuel mixture  17  is directed through a mixing chamber  62  comprising multi-directional blades or vanes  63  to further mix the fuel mixture  17  before reaching the engine intake. 
     A majority of the air required for operation of the engine  10  enters the engine as fresh main combustion air  14  directly into the main air gallery  20 . A conventional air filter  64  is fit to the sleeve  40 . The feed butterfly  61  in the sleeve  40  provides a gross level of control for regulating the quantity of main combustion air  14  in proportion to the rich mixture  25  regulated by the fuel/air regulator  22 . The throttle regulator  15  at the engine intake  11  is controlled through a connection to the gas pedal (not shown). The throttle regulator  15  is coordinated with the fuel/air regulator  22  to vary engine output. 
     Various other embodiments of the control of main air  14  and rich fuel mixture  13  are illustrated in FIGS. 7 a - 7   c.    
     As described above, the feed butterfly  61  grossly controls the main air proportions through the sleeve. In FIG. 7 b , the sleeve  40  may simply comprise a self regulating venturi, without a butterfly. In FIG. 7 c , a venturi  66  can be formed at an inlet to the main air gallery  20 , the venturi having a throat  67  so that the resulting venturi effect may be combined for both proportioning of the air  14  and for creating the low pressure used for drawing the rich fuel mixture  13  into the main air gallery  20 . 
     Typically the vaporizer  21  is fitted with a small low-capacity fuel/air regulator  22  such as a Mikuni™ carburetor available from Mikuni American Corporation of Northridge, Calif. Such a carburetor is typically implemented for use with motorcycles and snowmobiles, and normally not to larger automobiles and the like, including a Mikuni HSR42/45 series carburetor. As stated, the carburetor provides a rich fuel mixture  25  to the vaporizer  21  for heating by the exhaust gases  31 . The amount of carrier air  24   b  in the fuel mixture  25  is non-stoichiometric, that is, the Mikuni™ carburetor does not provide enough carrier air  24   b  to provide efficient or complete combustion in the engine  10 . The main air gallery  20  provides the greatest amount of air  14 . The butterfly  61  on the main air gallery regulates the mixture of main air  14  to supplement the rich fuel mixture  25 , 13  provided by the Mikuni. 
     In an example a Mikuni™ carburetor was fit to a 350 cu.in. V-8 engine in a pre-1990 ½ ton Chevrolet™ truck. The truck had a conventional fuel consumption of 14 miles per gallon (mpg) prior to installation of the current invention. Afterwards, the performance was increased to 72 mpg.