Fuel injection apparatus for internal combustion engines

Claim 1

A fuel injection apparatus for internal combustion engines, comprising at least one pump piston guided inside a pump housing of a fuel injection pump in an axially and rotationally movable manner in a pump cylinder and acting upon a pump work chamber between said pump piston and a supply pressure valve, said piston being actuated by a cam drive, the pump piston being provided with first and second control locations axially offset from one another, of which said first control location is embodied by an oblique control edge and in order to terminate the effective supply stroke opens an overflow conduit disposed separately from an inflow opening in the pump cylinder and upon the return stroke of the pump piston enables a refilling of the return-flow fuel quantity that had been diverted from said chamber following the end of supply and thereby fixes the instant of supply onset; a fuel reservoir connectable with the pump work chamber via the overflow conduit; said pressure supply valve closing off the pump work chamber on the supply side; an adjusting device serving to rotate the pump piston and actuatable by a mechanical adjusting member; an electromechanically actuatable metering valve supplying the pump work chamber with fuel via the inflow conduit, said metering valve, with its opening duration, determining a fuel injection quantity pre-stored in the pump work chamber; said fuel reservoir embodied as a refill reservoir receiving the entire return-flow fuel quantity diverted after the end of supply and forcing the entire return-flow fuel quantity back into the pump work chamber prior to the next subsequent supply stroke, the refill reservoir including a reservoir chamber and a reservoir piston displaceable therein counter to the force of a restoring spring; said reservoir piston including a bottom facing towards said pump work chamber and filling an end portion of said reservoir chamber facing said pump work chamber when in its nondisplaced position; said overlow conduit representing the sole and direct connection between the refill reservoir and the pump work chamber and openable by said first and second control locations of the pump piston; the pump housing comprising two housing parts threaded together in a plane of division extending at right angles to the longitudinal axis of the pump piston, said two housing parts being, respectively a lower housing part which receives at least the adjusting device, and a cylinder head which receives at least the pump cylinder and the supply pressure valve; and the cylinder head also, including a first receiving bore connected to the overflow conduit which receives the refill reservoir and, a second receiving bore which communicates with the inflow conduit, and contains the metering valve.