Internal-combustion engines – Charge forming device – With fuel pump
Reexamination Certificate
1994-11-01
2002-05-28
Miller, Carl S. (Department: 3747)
Internal-combustion engines
Charge forming device
With fuel pump
C123S496000
Reexamination Certificate
active
06394072
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a fuel injection device for an engine and more particularly to an improved arrangement for controlling the amount of fuel supplied by the fuel injector of an internal combustion engine.
The advantages of fuel injection for internal combustion engines are well known. One particularly popular type of fuel injector is the so called “accumulator type” in which fuel is supplied to the injector under pressure and then is injected when the injection valve is opened. This type of injector is extremely efficient and advantageous. However, the amount of fuel required per injection cycle varies widely with engine running conditions such as speed and load. Even the accumulator type of fuel injector can have some difficulties in providing the appropriate fuel control under all running conditions.
There is disclosed in U.S. Letters Pat. No. 4,969,442, entitled High Pressure Fuel Injection Device For Engine, issued Nov. 13, 1990 and assigned to the assignee hereof, an arrangement for controlling the amount of fuel supplied by an accumulator type of injector through varying the pressure at which the fuel is delivered to the injector. Varying the pressure at which the fuel is supplied to the injector is more effective, under some conditions, than varying the duration of injection so as to control the amount of fuel supplied. In the construction shown in U.S. Pat. No. 4,969,442 the pressure of the fuel supplied to the injector is varied by varying the phase of the injector or high pressure pump. Although this method is highly effective, it does require a mechanical adjustment of the phase of the pump and can, in some regards, be more costly than desirable.
It is, therefore, a principal object of this invention to provide an improved arrangement for controlling pressure of the fuel supplied to a fuel injector.
It is a further object of this invention to provide a fuel supply system for a fuel injector wherein the pressure of the fuel supplied to the injector is controlled so as to control the amount of fuel injected per cycle.
It is another object of this invention to provide a fuel injection device for an engine wherein the amount of fuel injected can be controlled by controlling the pressure at which the fuel is supplied to the injector.
In accordance with one feature of the invention, the fuel pressure is controlled by providing a selectively operable relief valve which is controlled to vary the fuel pressure by relieving it with the amount of relief being dependent upon the engine running condition. Although such a device is extremely effective, there are certain running conditions during which it may be desirable to provide full pressure to the injector and yet limit the pressure supplied to the injector under other conditions. That is, it is desirable to provide a greater fuel pressure during starting and also at maximum load condition. This cannot always be accomplished as efficiently as possible solely through the use of pressure control of the outlet of the high pressure pump.
It is, therefore, a still further object of this invention to provide an improved arrangement for controlling the amount of output of a high pressure fuel injection pump.
It is a further object of this invention to provide an arrangement for controlling the output pressure of a high pressure pump in a simple and highly effective manner.
SUMMARY OF THE INVENTION
A first feature of this invention is adapted to be embodied in a fuel injection system for an internal combustion engine that is comprised of a high pressure pump and a fuel injector. Means are provided for communicating the output pressure of the high pressure pump to the fuel injector for injection into the engine. In accordance with this feature of the invention, a return line is provided in the conduit connecting the output of the high pressure pump with the fuel injector. A pressure controlling valve is provided in this return line for controlling the pressure at which the fuel is supplied to the injector from the high pressure pump. The pressure of the supply is controlled in response to engine running conditions.
Another feature of the invention is adapted to be embodied in a high pressure pump for a fuel injection system having a plunger slidable in a bore for pressurizing fluid in the bore. A return passage intersects the bore at a point intermediate the ends of the stroke of the plunger. Selectively operable valve means are provided for opening and closing the return line for controlling the pressure generated by the high pressure pump.
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Hirai Ryoichi
Nakamura Yoshikazu
Suzuki Minoru
Yoshida Takeo
Beutler Ernest A.
Miller Carl S.
Yamaha Hatsudoki Kabushiki Kaisha
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