Patent Publication Number: US-4649884-A

Title: Fuel rail for internal combustion engines

Description:
FIELD OF INVENTION 
     Devices for furnishing fuel to a multiple cylinder internal combustion engine with an electric pump fuel source. 
     BACKGROUND AND OBJECTS OF THE INVENTION 
     In furnishing fuel to a multiple cylinder engine utilizing a multiple point injection unit, that is, one injector at each cylinder, it is common to use a fuel manifold with a fuel inlet near one end and a fuel outlet near the other end. Fuel is furnished to the inlet from a fuel pump and is discharged to a pressure regulator which returns fuel to the tank. 
     It has been found that pressure pulses in the fuel manifold due to the fuel injection action have interfered with the furnishing of fuel to the respective cylinders in equal quantities. Also, these pressure pulsations created by the injectors cause a noise called &#34;injector rap&#34; which travels back through the fuel supply line and proves to be objectionable to passengers in a vehicle. 
     It is an object of this invention to provide a fuel rail which will materially reduce the undesirable pulsations in the fuel available to the individual fuel injectors and smooth out the fuel flow to make it available at each injector in suitable quantity and at a proper pressure to insure the maximum efficiency of the fuel supply system, as well as reduce noise in the vehicle. 
     Other objects and features of the invention will be apparent in the following description, accompanying drawings, and claims in which the invention is described together with details to enable persons skilled in the art to practice the invention, all in connection with the best mode presently contemplated for the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     DRAWINGS accompany the disclosure and the various views thereof may be briefly described as: 
     FIG. 1, a diagrammatic depiction of the fuel system including the fuel rail. 
     FIG. 2, a sectional view on line 2--2 of FIG. 1. 
     FIG. 3, a plan view of a fuel rail. 
     FIG. 4, a side elevation of an enlarged view of a fuel rail. 
     FIG. 5, a sectional view of a modified diaphragm seal. 
     FIG. 6, a plan view of a modified fuel rail. 
     FIG. 7, a side view of the modified rail shown in FIG. 6. 
     FIG. 8, a sectional view on line 8--8 of FIG. 6. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION AND THE MANNER AND PROCESS OF USING IT 
     WITH REFERENCE TO THE DRAWINGS, in FIG. 1, a fuel tank 20 of standard construction is illustrated having an intank pump 22 of a type illustrated in my U.S. Pat. No. 4,540,354  issued Sept. 10, 1985. A fuel line 24 carries fuel from the pump 22 to a fuel inlet collar 26 at one end of a fuel rail 30. A fuel outlet collar 32 at the other end of the fuel rail is connected to a fuel by-pass line 34 leading to a pressure regulator 36 which dumps into return line 38 leading to the fuel tank 20. 
     The fuel rail 30 has four fuel injector connecting collars 42, 44, 46 and 48 which carry fuel injectors 52, 54, 56 and 58, each associated with the engine manifold 60. These fuel injectors are of standard construction operated electronically utilizing, for example, solenoid actuated valves. 
     Each fuel injector is located adjacent the intake valve of a cylinder so that it feeds directly into the engine fuel manifold at the proper location. The fuel rail 30 is actually connected to the engine manifold by the fuel injectors, but it is also supported on the engine by suitable brackets (not shown) to eliminate mechanical vibration. 
     A sectional view in FIG. 2 illustrates the construction for the fuel rail 30. An elongate body 62 forms an elongate channel 64 with continuous flanges 66 which carry an oval O-ring 68 in a formed groove 70. 
     A diaphragm 80 overlies the channel 64 with a continuous peripheral edge 72 extending over a portion of the continuous flange 66. This diaphragm is preferably formed of a thin stainless steel having a thickness of about 0.010&#34;. The result is an elongate chamber 64 on the fuel-side (wet side) of the diaphragm. 
     A domed cover element 82 has a peripheral edge 74 which overlies the edge 72 of the diaphragm. The flange 66 is formed over the cover and the diaphragm under pressure to seal the parts together in conjunction with the O-ring 68. This leaves an elongate sealed pressure chamber 84 above the diaphragm. If by some chance the diaphragm should rupture, the sealed chamber 84 would contain the fuel. 
     In a modified construction, illustrated in FIG. 5, the edges of the diaphragm 80 are coated around with a stable sealant material 90 which in assembly is compressed between flanges of the body 62 and the cover 82 to form a seal. The material 90 is a synthetic rubber or plastic which is inert to hydrocarbon fuels. 
     IN THE OPERATION, fuel is furnished from the pump 22 to the chamber 64 where it flows the length of the chamber and reaches each of the fuel injector ports. The pressure regulator 36 in the outlet line 34 maintains a reasonably steady fuel pressure in the chamber 64. The pulses in the chamber resulting from the pump surges and the residual injector reaction are absorbed to a significant degree by the flexing of the elongate diaphragm 80 so that there is a steady pressure in the chamber, and the objectable &#34;injector rap&#34; noise is avoided. 
     It has been found that the pulse magnitude has been reduced by a factor of 10 in actual testing. 
     In FIGS. 6 and 7, a modified fuel rail is illustrated in which in the chamber 64 a flow shield 100 is provided at each end overlying the respective inlet and outlet collars 26 and 32. These shields are open at the extreme ends as at 102. The shields serve to move the incoming fuel to the full length of the rail to insure that the end injector ports are not starved of fuel.