Patent Document

CROSS-REFERENCE TO RELATED APPLICATION DATA 
   This application claims the benefit of priority of U.S. Patent Application Ser. No. 60/672,348, filed Apr. 18, 2005. 

   BACKGROUND OF THE INVENTION 
   The present invention pertains to a supplemental fuel pump system. More particularly, the present invention pertains to a supplemental fuel pump system for use in conjunction with, and that is driven by, a supplemental oxygen supply for an internal combustion engine. Nitrous oxide injection systems are known for use in providing an additional “shot” of power for internal combustion engines. Most nitrous oxide systems are relatively rudimentary, and include only sufficient systems and components to inject nitrous oxide gas into the engine intake to increase the oxygen available for combustion and the intake pressure in the manifold. 
   However, problems can arise due to a number of factors. First, because nitrous oxide is a liquid stored gas, the equilibrium pressure in the storage vessel can vary significantly as the ambient temperature varies. This can result in the amount of nitrous oxide delivered to the engine varying by as much as 30 percent, within the normally expected operating environments. 
   In addition, the increased amount of oxygen requires a commensurate increase in fuel fed to the combustion system. Without supplemental fuel, the fuel mixture in the engine is far too lean (an excess of oxygen over stoichiometric proportions) which can result in engine overheating, improper detonation, and ultimately failure of piston, crankshaft, and valve components. 
   Accordingly, there is a need for a nitrous oxide precision variable restrictor that reduces (regulates) the supply pressure for a nitrous oxide injection system. Desirably, such a restrictor is used in conjunction with a nitrous oxide assist supplemental fuel pump system. 
   BRIEF SUMMARY OF THE INVENTION 
   A supplemental fuel supply system is configured for use with an internal combustion engine to supply an on-demand supplemental oxygen supply and a supplemental fuel supply. The system includes a supplemental fuel pump having a fuel supply and a fuel discharge. The pump including a supplemental oxygen supply inlet and is driven by a portion of the supplemental oxygen supply such that when a demand is made on the on-demand supplemental oxygen supply to supplement oxygen to the engine, a portion of the supplemental oxygen is introduced into the fuel pump to drive the fuel pump. A present system is contemplated for use with a supplemental nitrous oxide supply to the internal combustion engine. 
   The fuel pump includes a piston having a fuel chamber with the fuel supply and fuel discharge in flow communication with the fuel chamber. The piston includes a gas-side chamber with the portion of the nitrous oxide supply in flow communication with the gas-side chamber. In this manner, when demand is made on the on-demand nitrous oxide supply, the nitrous oxide pressurizes the gas-side chamber to drive the piston to discharge the fuel. 
   The piston is biased away from the fuel supply to draw fuel into the fuel chamber when there is little or no demand made on the on-demand supplemental oxygen supply. A present system includes a regulating device for regulating the flow of nitrous oxide from a nitrous oxide source to the fuel pump and to the internal combustion engine. 
   The regulating device simultaneously supplies nitrous oxide to the fuel pump and to the internal combustion engine such that the supply of nitrous oxide to the fuel pump serves to drive the pump to discharge fuel therefrom to the internal combustion engine. 
   A present regulating device includes a body and a piston (within the body) that has a bore therein. The piston is disposed to move between an inlet and an outlet to close down flow through the device as pressure in the device increases and to move away from between the inlet and the outlet when pressure in the device decreases. 
   These and other features and advantages of the present invention will be apparent from the following detailed description, in conjunction with the appended claims. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The benefits and advantages of the present invention will become more readily apparent to those of ordinary skill in the relevant art after reviewing the following detailed description and accompanying drawings, wherein: 
       FIG. 1  is a schematic diagram of a nitrous oxide assist supplemental fuel pump system embodying the principles of the present invention; and 
       FIG. 2  is a cross-sectional illustration of a precision variable restrictor embodying the principles of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described a presently preferred embodiment with the understanding that the present disclosure is to be considered an exemplification of the invention and is not intended to limit the invention to the specific embodiment illustrated. 
   It should be further understood that the title of this section of this specification, namely, “Detailed Description Of The Invention”, relates to a requirement of the United States Patent Office, and does not imply, nor should be inferred to limit the subject matter disclosed herein. 
   Referring to  FIG. 1  there is shown a schematic illustration of a nitrous oxide assist supplemental fuel pump system  10  embodying the principles of the present invention. The fuel supply system  10  is configured to supply a supplement or boost of nitrous oxide as indicated by the arrow at  12 ), for an internal combustion engine (not shown), in a pressure regulated manner. In addition, such a system  10  supplies a supplemental supply of fuel (as indicated by the arrow at  14 ) to prevent the engine from operating too lean, that is with an excess of oxygen (or a shortage of fuel) over stoichiometric proportions, which can result in engine overheating, improper detonation, and ultimately failure of piston, crankshaft, and valve components. 
   The supplemental fuel supply system  10  includes a nitrous oxide supply  16 , and a supplemental fuel pump  18 . The supplemental fuel pump  18  is a biased, single acting cylinder having a fuel side  20  that holds a captive quantity of fuel, which is delivered to the engine under pressure and a gas side  22  that receives nitrous oxide and drives a piston  24  to pump the fuel. The bias can be provided by a spring  26 , conical washers or the like. 
   The pump  18  includes a fuel chamber  28 , a fuel inlet  30  that feeds fuel into the chamber  28 , and a fuel outlet  32  that directs the supplemental fuel to the combustion system. Both the inlet  30  and the outlet  32  are fitted with one-way flow devices, such as the illustrated inlet and outlet check valves  34 ,  36 . 
   The piston  24  is configured with a fuel side  37  (in the fuel circuit) which is a driven side, and a smaller gas side  39  (which is in the gas circuit) that is the driving side. The fuel side  37  of the piston  24  has a larger surface area and thus is within the lower pressure circuit and the gas side  39  of the piston  24  has a smaller surface area and thus is within the higher pressure circuit. The spring  26  returns the piston  24  to its at rest position, as illustrated in  FIG. 1 , in which the fuel chamber  28  is expanded and filled with fuel. Seals, such as the illustrated O-rings  41  isolate the higher pressure regions from the lower pressure regions and provide seals at the various interfaces (gas/piston and fuel/piston). 
   The nitrous oxide supply  16  includes a tee or split  38  with one branch  40  routing nitrous oxide to the fuel pump  18  and the other branch  42  directing nitrous oxide to the combustion system (as at  12 ). 
   In the at rest state ( FIG. 1 ), fuel is present in the fuel chamber  28 . As nitrous oxide is charged to the combustion system, nitrous oxide is simultaneously directed into the cylinder gas side  22 . This applies a force against the gas side  39  of the piston  24  which forced the piston  24  into the fuel chamber  28  (as indicated by the directional arrow at  44 ), against the bias. Fuel is pumped or expelled from the chamber  28 , through the discharge check valve  36  and into the combustion system (as at  14 ). Thus, there is a simultaneous supply of supplemental fuel and nitrous oxide. 
   When the supply of nitrous oxide to the combustion system is terminated, the nitrous oxide (applied pressure) to the fuel pump  18  is also terminated. When this occurs, the fuel pump piston  24  is drawn back to its rest position by the return spring  26 . This action draws in additional fuel to the chamber  28  to replace the fuel previously expelled or pumped from the chamber  28 . The inlet and discharge check valves  30 ,  32  direct the high pressure fuel delivery, and the low pressure fuel recharge (into the chamber  28 ). Essentially, the supplemental fuel pump system  10  supplies an internal combustion engine with the simultaneous delivery of a precision charge of nitrous oxide  12 , and the additional fuel  14  required to maintain a stoichiometric fuel/oxygen ratio. 
   The precision variable restrictor (PVR)  50 , as seen enlarged in  FIG. 2 , accepts high pressure nitrous oxide (as at  52 ) from a control or charge valve (not shown) through an inlet  54 , and delivers the pressure regulated stream, through an outlet  56 , to the engine being served and to the supplemental fuel pump  18 . 
   As set forth above, pressure regulation is desired because nitrous oxide is a liquid stored gas, and as such, the equilibrium pressure in the storage vessel can vary significantly as the ambient temperature varies. Without regulation, the amount of nitrous oxide delivered to the engine could vary by as much as 30 percent within the normally expected operating environment when the system is used, for example, to supply nitrous oxide to an internal combustion engine of a snowmobile. 
   The operating principle of the PVR  50  is similar to other preset regulators, such as that disclosed in Carroll, U.S. Pat. No. 6,948,520, which is commonly assigned with the present application and is incorporated herein by reference. The present PVR  50  includes a body  58  having the inlet  54  and outlet  56 . A piston  60  resides in the body  58  and reciprocates between an open and a restricted position (rather than a “closed” position), in that there is no resilient regulator seat to isolate flow from the regulator  50 . Rather, the PVR  50  is principally concerned with regulating a dynamic flow, and static bubble-tight performance is not necessary. 
   The PVR  50  is biased by, for example a spring  62 , that is positioned in the PVR body  58  to bias the piston  60  to the open position (as seen in  FIG. 2 ). A bore  64  in the piston  60  provides a flow path or flow communication (as indicated by the arrow at  66 ) from the inlet  54  to the backside  68  of piston  60 . As will be appreciated from  FIG. 2 , the backside  68  of the piston  60  has a relatively large surface area. In this manner, as gas flows into the inlet  54 , it also flows (as indicated by the arrow at  66 ) to the backside  68  of the piston  60 . Because of the large area over which the gas exerts pressure on the piston backside  68 , the piston  60  is urged to the restricted position, as indicated by the arrow at  70 . 
   As downstream pressure increases (that is, the pressure between the PVR  50  and the combustion system and fuel pump  18 , as at  72 ), the pressure on the piston backside  68  increases which closes down or restricts flow through the PVR  50 . Conversely, as the downstream pressure declines, pressure on the piston backside  68  likewise declines and the spring  62  urges the PVR  50  to the open position. 
   When the PVR  50  is in the restricted position, a taper  74  on the piston  60  engages a taper  76  in the body  58  (near the outlet  56 ), to restrict or close down flow. However, as set forth above, because the PVR  50  is configured to regulate dynamic flow control (as opposed to static flow control or shut-off), a bubble-tight seal at the piston-body interface (as at  78 ) is not needed. Accordingly, there is no traditional seat in the PVR  50  that would provide a bubble-tight seal or shut-off capability. 
   As will be appreciated from a study of the figures, the PVR  50  includes a non-pressurized region  80  around the spring  62  and the piston  60 . The non-pressurized region  80  is isolated from the pressurized regions by seals, such as the illustrated O-rings  82 . In addition, a vent  84  is present in the non-pressurized region  80  of the PVR  50  to prevent pressurizing this area. 
   Advantageously, the present supplemental fuel pump system  10  and PVR  50  provide a regulated nitrous oxide delivery in conjunction with an injection of supplemental fuel that allows stoichiometrically accurate fuel/oxygen ratios to be calculated and delivered. In addition, the fuel pump  18  is powered by the output from the PVR  50  which is provided by the flowing nitrous oxide, thus providing truly simultaneous delivery of the required fuel  14  with the nitrous oxide charge  12 . Moreover, the present system  10  provides this regulated, simultaneous nitrous oxide and fuel flow using compact components that operate without power other than the gas pressure provided by the nitrous oxide source. 
   Although the present invention is described with respect to a nitrous oxide enhanced internal combustion engine, it will be appreciated that the pressurized gas can be any of a number of oxygen-containing gases are contemplated. 
   All patents referred to herein, are hereby incorporated herein by reference, whether or not specifically done so within the text of this disclosure. 
   In the present disclosure, the words “a” or “an” are to be taken to include both the singular and the plural. Conversely, any reference to plural items shall, where appropriate, include the singular. 
   From the foregoing it will be observed that numerous modifications and variations can be effectuated without departing from the true spirit and scope of the novel concepts of the present invention. It is to be understood that no limitation with respect to the specific embodiments illustrated is intended or should be inferred.

Technology Category: 2