Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
1999-11-10
2001-02-13
Yuen, Henry C. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S456000, C123S449000, C417S525000, C417S549000
Reexamination Certificate
active
06186118
ABSTRACT:
TECHNICAL FIELD
This invention relates to fuel systems for supplying fuel at elevated pressures to an internal combustion engine.
BACKGROUND OF THE INVENTION
Some modern vehicles employ a high pressure fuel injection system to improve the efficiency and operation of the engine. These systems include an intank supply pump and a high pressure pump that supplies fuel at an elevated pressure to a fuel rail. The fuel rail distributes the high pressure fuel to fuel injectors mounted either directly at the combustion chamber the.
The supply pump is generally located in a fuel tank and the high pressure pump is situated on the engine at a distance from the fuel rail. Thus the high pressure fuel has some distance to travel at an elevated pressure between the high pressure pump and the injectors. Since most fuel pumps displace more fuel than is needed by the engine, a fuel return is necessary. The fuel return may be by way of a regulator valve at the high pressure pump to the engine.
In some fuel systems, a continuous flow rotary type pump is used and in other systems, a single acting reciprocating pump is used. The reciprocating pump has a plunger that draws fluid into a cylinder when stroked in one direction and expels fluid from the cylinder when stroked in the other direction. Thus the pump delivers a single charge of fuel during each stroking cycle. Systems using either type of pump still utilize a fuel rail for distributing fuel to the individual injectors on the engine.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved fuel rail and fuel pump in a vehicle fuel supply system having a direct injection engine.
In one aspect of the present invention, a fuel pump and a fuel rail are integrated in a single assembly. In another aspect of the present invention, the fuel pump is a double acting single piston pump. In yet another aspect of the present invention, the fuel rail is incorporated into one of the pumping chambers of the double acting pump.
In still another aspect of the present invention, the fuel rail portion of the integrated assembly has an outlet port for each fuel injector in the fuel system. In a further aspect of the present invention, the pump has a large cylinder portion and a small cylinder portion with the large cylinder portion being connected with a fuel inlet port and a high pressure regulator having an outlet connected with a return fuel line. In yet a further aspect of the present invention, the pump piston has incorporated therein a valve assembly for controlling the flow of fuel between the cylinder portions and for relieving high pressure in the small cylinder portion.
The present invention provides a fuel system that incorporates a fuel pump directly into a fuel rail. The pump is a double acting piston pump having one piston. The pump is disposed in a housing that includes a cylindrical cavity in which the piston is disposed. A piston rod, attached to the piston, is also disposed in the cylindrical cavity. One side of the piston cooperates with the cylinder cavity to establish a first pumping chamber and the other side of the piston cooperates with the cylinder cavity and piston rod to establish a second chamber having a volume equal to one-half of the first chamber. Thus for each stroke of the piston, the pump produces an output flow substantially equal to the volume of the second chamber.
The second chamber has connected therewith a plurality of fuel outlet ports equal in number to the number of injectors on the engine. The second chamber, therefore, provides a fuel rail for the fuel system. The piston rod is driven by the engine or by an electric motor, at a speed commensurate with the engine speed, such that the pump output flow is proportional the speed of the engine.
The first chamber has an inlet port adapted to receive fuel from a fuel reservoir, and a system pressure regulator adapted to return excess fuel to the fuel reservoir. The piston has disposed thereon a plurality of control valves that control the flow of fuel between the chambers. dr
DESCRIPTION OF THE DRAWINGS
The drawing is a diagrammatic representation of a fuel system with a sectional elevational view of a fuel rail and pump incorporating the present invention.
REFERENCES:
patent: 5163706 (1992-11-01), Maguran, Jr. et al.
patent: 5238372 (1993-08-01), Morris
patent: 5249933 (1993-10-01), Moody
patent: 5282645 (1994-02-01), Spakowski et al.
patent: WO 99/22135 (1999-05-01), None
Castro Arnold
Delphi Technologies Inc.
VanOphem John A.
Yuen Henry C.
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