Fuel injection pump for internal combustion engines
AssigneeRobert Bosch GmbH
InventorsFranz Eheim, Gerald Hofer, Helmut Laufer
Life of this patent
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Abstract
A fuel injection system is proposed which has a high-pressure pump, a fuel reservoir determining the injection pressure, and an intermediate piston, during whose first half-stroke meters fuel under low pressure and during a second half-stroke, driven by the reservoir, injects the metered fuel. In order to vary the duration of injection, the pressure in the reservoir is determined either by means of the supply quantity of the high-pressure pump or by means of an appropriate pressure control valve in an outflow conduit.
Claims29
In a fuel injection system, having a fuel injection nozzle for internal combustion engines including:
- a fuel supply
- an intermediate piston having a front face and a rear face, which is actuated back and forth synchronously to the cycles of the fuel injections and which front face in fluidly connectable to an injection line of said fuel nozzle;
- a low pressure supply pump which is connected to supply fuel to the injection system;
- control means for timely connecting the fuel supply to the front face of said intermediate piston initiating its backmovement;
- a high pressure pump having a work chamber which forces fuel into a fuel reservoir, said control means controlling the fuel quantity forced into said fuel reservoir
- and further controlling the period of a fluid connection between the fuel reservoir and the rear face of the intermediate piston thereby initiating the forth moving and the injection stroke of the intermediate piston;
- a relief conduit fluidly connecting the rear face of the intermediate piston stroke on its backmovement to the low pressure supply pump;
- said fuel reservoir receiving fuel from the work chamber when the high pressure pump is in a compression stroke, such that the pressure of the reservoir is related to the difference between the fuel quantity received from the work chamber and the fuel quantity withdrawn to the rear face on the forward movement of the intermediate piston and
- a check valve located between the reservoir and the work chamber to fluidly disconnect the reservoir and the work chamber when the high pressure pump is in an intake stroke.
Dependencies are inferred from the claim text.