Internal-combustion engines – Starting device – With fuel or intake air control
Reexamination Certificate
2000-03-13
2001-05-22
Miller, Carl S. (Department: 3747)
Internal-combustion engines
Starting device
With fuel or intake air control
C123S447000
Reexamination Certificate
active
06234128
ABSTRACT:
TECHNICAL FIELD
This invention relates to fuel injection systems and more particularly to a system for providing a volume of fuel to the fuel injectors at engine start-up.
BACKGROUND OF THE INVENTION
Internal combustion engines utilize many types of fuel injection such as manifold injection, port injection and direct injection. Direct injection engines have a fuel feed system that injects fuel directly into the combustion chamber of the engine. Direct injection engines employ high pressure fuel systems in order to more fully atomize the fuel in the combustion chamber. At start-up of the engine, it is desirable to have the operating pressure of the fuel system be at a sufficient level to achieve proper atomization to sustain low emission levels. It generally requires a number of engine revolutions before the fuel system attains the desired pressure level. This delays the engine start-up.
To alleviate this condition, it has been proposed to install a passive high pressure accumulator to the fuel system such that fuel is stored at the desired pressure between engine shut-off and the next engine start-up. These systems have two drawbacks. The storage of high pressure fuel is undesirable and the accumulators often “leak down” between shut-down and start-up, if the period is long, thereby defeating the purpose of the accumulator.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved direct injection fuel system having an accumulator.
In one aspect of the present invention, an accumulator stores fuel at a low pressure between engine shut-down and engine start-up. In another aspect of the present invention, the fuel stored in the accumulator is delivered to the fuel injectors at a high pressure at engine start-up. In yet another aspect of the present invention, a stored force is applied to the fuel in the accumulator to eject the fuel therefrom and rapidly pressurize the fuel system at the injectors. In still another aspect of the present invention, a spring-loaded piston is employed to force the fuel from the accumulator during engine start-up.
In yet still another aspect of the present invention, the accumulator is filled and the spring-loaded piston is reset by the pressurized fuel supplied from a fuel pump during engine operation. In a further aspect of the present invention, a solenoid-actuated piston is employed to provide the force used to expel the fuel from the accumulator. In a yet further aspect of the present invention, a pressure-on-demand system is provided to assist rapid engine starting by producing a high pressure fuel charge, from low pressure accumulator stored fuel, to the fuel injectors of the engine only at the beginning of the engine-starting operation but prior to pressurized fuel from the normal fuel injection pump becoming available.
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General Motors Corporation
Grove George A.
Miller Carl S.
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