Patent Application
20080184971
The present disclosure relates to placement of a check valve and a pressure regulator in a fuel pump module of an electronic returnless fuel system.
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. Modern fuel systems in vehicles, such as automobiles, may employ an electronic returnless fuel system (“ERFS”) to deliver fuel to an engine. Regarding such electronic returnless fuel systems, only a fuel supply line from a fuel tank to an engine is utilized; therefore, no return fuel line from the engine to the fuel tank is necessary. As a result of such a configuration, in an ERFS only the exact volume of fuel required by an engine is delivered to the engine, regardless of the varying degree of the volume of fuel required by the engine.
While current electronic returnless fuel systems have generally proven to be satisfactory for their applications, each is associated with its share of limitations. One limitation of current ERFS is their inability to supply liquid fuel to an engine in a volume and at a pressure that meets or exceeds engine demand. Another limitation is the general inability of current ERFS systems to accept more than one fuel pump within a fuel pump module while utilizing only a single check valve within the fuel pump module. Another limitation is that current ERFS fuel pump module jet pumps are not configured to operate using filtered fuel from a separate area of the fuel pump module fuel filter, and because of this limitation, jet pump interference with the pressurized fuel flowing to the engine during pump on and off conditions is possible. Still yet another limitation is that with current ERFS, because jet pumps begin functioning when the pressure regulator permits fuel to flow to the jet pumps when the fuel pressure reaches a set amount to open the regulator, during high fuel demand situations, such as wide open throttle, the fuel pressure may not permit the regulator to open and begin jet pump operation.
What is needed then is a device that does not suffer from the above limitations. This, in turn, will provide a device that utilizes a check valve between a fuel module fuel filter and a fuel pressure relief regulator.
A fuel pump module within a fuel tank employs one or more fuel pumps. In the case of more than one fuel pump, a manifold receives all pumped fuel and directs it into a fuel filter that surrounds the fuel pumps and that lies within a surrounding filter case. A check valve attaches to or is integrally molded to an exterior surface of the filter case at a first filter case location while a pressure regulator attaches to or is integrally molded to the check valve. From the check valve, an engine supply line delivers fuel to an internal combustion engine. With the check valve located between the filter case and the pressure regulator, high fuel pressures may be maintained in the engine supply line when the engine is not operating, while during engine operation, the pressure regulator may still relieve excessive fuel pressure and deliver fuel to the engine. A jet pump supply line attaches to or is integrally molded into the filter case at a second filter case location and supplies fuel to one or more jet pumps, such as a fuel pump module reservoir jet pump and a fuel transfer jet pump, if a vehicle is equipped with an auxiliary fuel tank or saddle fuel tank.
Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.
The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. With reference to
More specifically, in an electronic returnless fuel system (“ERFS”), only a fuel supply line 14 carries fuel between the fuel pump module 18 and the common rail 24, if a vehicle is so equipped. Once the fuel reaches the common rail 24, the fuel passes into individual fuel injectors 22 just before being sprayed or injected into individual combustion cylinders of the internal combustion engine 12. The fuel supply system 20 has no fuel return line from the common rail 24 to the fuel tank 16, as in some systems, and because there is no return line, one or more electric fuel pumps within the fuel pump module 18 has its supply voltage varied to vary the amount of fuel supplied to the common rail, as dictated by the fuel demand from the engine 12.
With reference to
The fuel pump module 30 of
Continuing with
The jet pump feed line 64 is depicted as being attached to or integrally molded into a different location of the filter case 66 than the check valve 60, which may also be attached to or integrally molded into the filter case 66. Because the jet pump feed line 64 receives fuel directly from the filter case 66, the jet pumps, advantageously, are supplied with fuel that has passed through the filter 54, which removes any particulate matter. Upon fuel passing into and moving though the jet pump feed line 64 in accordance with flow arrows 68, it moves into either a fuel module reservoir jet pump tube 70 or a transfer jet pump tube 72. The reservoir jet pump tube 70 delivers fuel 74 to a reservoir jet pump 76, while the transfer jet pump tube 72 delivers fuel 78 to a transfer jet pump 80. The reservoir jet pump 76 receives fuel 74 with the pressure supplied by the fuel pump 50 to cause fuel 82 within the fuel tank 16 to enter the fuel pump module reservoir 34. The transfer jet pump 80 receives fuel 78 with the pressure supplied by the fuel pump 50 to cause fuel 84 in a secondary tank area 86, such as with a saddle tank, to be drawn into the main tank area 88 by a fuel transfer line 90. Alternatively, the transfer jet pump 80 may be located in the position of the reservoir jet pump 76 to directly transfer fuel from the secondary tank area 86 and put it into the fuel pump module reservoir 34. The jet pumps 76, 80 operate on the same Venturi principle as is known in the art; that is, as the fuel increases in speed at a nozzle, or jet, within the jet pump, pressure is lowered thereby creating a partial vacuum that draws surrounding fuel into the jet stream.
The fuel tank 16 depicted in
Continuing with the check valve 60, when the pressure in the filter case 66 is such that the valve element 118 permits fuel to flow to the engine 12, such as when the fuel pump 50 or fuel pumps 50, 102 are operating, fuel flows through the check valve 60 and into the pressure regulator 62, where the fuel flow either continues toward the engine 12 in accordance with fuel flow path 56, or exits the pressure regulator 62 when the fuel pressure at the pressure regulator 62 exceeds a predetermined limit. The pressure at the pressure regulator may exceed the predetermined limit when the fuel pumps 50, 102 create such fuel pressure based on engine demand or during a dead soak event. A dead soak event may occur when the engine is turned off on a hot summer day but the engine compartment and fuel line temperatures continue to rise. Such a rise in temperature with no fuel movement causes the fuel pressure to rise. With the check valve 60 closed, pressure and fuel can not escape into the filter case 66, but instead escapes through the pressure regulator when the pressure forces the pressure plate 122 and spring 124 to move and release fuel and pressure 126 from the pressure regulator 62, such as through the bottom 128 of the pressure regulator 62. If the engine compartment or fuel supply system 20 overheats or a situation is created such that the pressure in the engine supply line 120 is greater than the pressure in the filter case 66, the check valve 60 will close and then fuel may also exit the pressure regulator 62 if the predetermined pressure setting of the pressure regulator is exceeded. In such a situation, fuel pressure is preserved in the engine supply line 120 to aid in instantaneous engine restarting while also alleviating pressures in excess of the pressure regulator setting.
There are many advantages to the teachings of the present invention. The teachings provide placement of a check valve between a fuel filter and a fuel pressure regulator and allow: fuel pressure to remain in the engine supply line 120 when the engine 12 is not operating while also permitting the fuel pressure regulator 62 to relieve fuel pressure when the engine is operating and when the engine is not operating, such as during a dead soak event; the jet pump(s) to operate using sufficiently pressurized and filtered fuel yet disallow the jet pumps to relieve any pressure within the engine supply line 120, that is, pressure within the engine supply line 120 will not escape through the jet pumps 76, 80 and into the fuel tank 16, where a vapor vent valve may permit its release.
Continuing with advantages of the teachings of the present invention, the fuel filter case 66 and accompanying fuel filter 54 possess the ability to accept more than one fuel pump 50, 102 to supply the engine 12 with the required volume flow rate of fuel while maintaining engine supply line pressure between the check valve 60 and the engine 12 after the fuel pump(s) cease operation, such as when the engine 12 is not operating. Another advantage of the present teachings is that the fuel pumps 50, 102 may be manufactured without their own, individual check valves, thus lowering the cost and complexity of the fuel pump. Still yet, another advantage is that a single check valve may be utilized regardless of how many fuel pumps are used within the filter case 66. Such an advantage also decreases part cost and permits a check valve to be repaired or replaced, if necessary, without disposing of or replacing a fuel pump. Still yet, another advantage is that the volume flow rate of fuel to the engine 12 may be increased with an increase in the number of known and existing pumps without designing, as an alternative, a new, larger fuel pump. Such volume flow rate increases may be necessary for applications such as larger engines, higher engine RPMs, or to meet racing performance requirements. Finally, the teachings of the present invention permit the addition of fuel pumps with minimal changes to the surrounding fuel pump module components while maintaining the aforementioned advantages.
