Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
1999-11-05
2001-07-17
Yuen, Henry C. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S447000
Reexamination Certificate
active
06260538
ABSTRACT:
BACKGROUND OF THE INVENTION
A fuel system typically comprises a fuel pump arranged to charge a volume, accumulator or common rail to an appropriate fuel pressure, and a plurality of individually actuable fuel injectors arranged to receive fuel under high pressure from the volume, accumulator or common rail. It has been found that, due to the hydraulics of the system, the fuel pressures applied to the various injectors may differ from one another, and the injection of fuel through one injector or the discharge of the fuel pump into the system may have a detrimental effect upon subsequent injections of fuel through others of the injectors due to the transmission of pressure waves from one injector to another. It is an object of the invention to provide a fuel system in which these effects are reduced.
SUMMARY OF THE INVENTION
According to the present invention there is provided a fuel system comprising a fuel pump having an outlet which communicates with a fuel volume, the volume communicating with the inlets of a plurality of fuel injectors, wherein the fuel flow paths between the pump outlet and the inlet of each injector form substantially equal restrictions to the flow of fuel.
Such an arrangement is advantageous in that each injector will have applied thereto, in use, substantially the same fuel pressure, and as a result injector to injector variations can be reduced. Further, pressure waves within the fuel system will be incident upon all of the injectors at substantially the same synchronised times, thus variations between the operation of the injectors are further reduced.
It will be appreciated that the restriction to flow formed by each flow path is dependent upon a number of factors, for example the path length and diameter, the number of bends in the flow path and the tightness of such bends.
The fuel volume conveniently comprises a common rail which includes an inlet for connection to the pump outlet and a plurality of outlets for connection to respective injectors.
The inlet and/or the outlets may be provided with regions of reduced diameter. Such an arrangement is advantageous in that the transmission of pressure waves within the fuel system can be damped, and as a result injection to injection variations can be reduced.
The invention will further be described, by way of example, with reference to the accompanying drawing which illustrates a fuel system in accordance with an embodiment of the invention.
REFERENCES:
patent: 4132205 (1979-01-01), Merritt
patent: 5109822 (1992-05-01), Martin
patent: 5592968 (1997-01-01), Nakashima et al.
patent: 5752486 (1998-05-01), Nakashima et al.
patent: 6095119 (2000-08-01), Maier et al.
patent: 6186119 (2001-02-01), Ciecko
Gimie Mahmoud M
Lucas Industries
Wells, St. John, Roberts Gregory & Matkin P.S.
Yuen Henry C.
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