Patent ID: 6158419
Filing Date: 2000-12-12
Classification: F02M

Abstract:
A pump for a fuel injection system, the pump comprising:a pump body having a pumping chamber, a fuel inlet for supplying fuel to the pumping chamber, an outlet port, and a valve chamber between the pumping chamber and the outlet port, the valve chamber defining a valve seat and having an axial guiding portion with a central axis;a plunger disposed in the pumping chamber;a valve body disposed in the valve chamber for controlling fuel, the valve body having a valve stem defining a seating surface, the valve stem having a step adjacent to the seating surface, the step extending a limited distance away from the seating surface, the valve body further having a valve guide that is received in the valve chamber guiding portion, and the valve body being axially moveable with respect to the guiding portion over a stroke range including a closed position in which the seating surface engages the valve seat, an intermediate position in which the seating surface is spaced from the valve seat and the step is aligned with the valve seat to provide limited pressure relief, and an open position in which the seating surface and the step are spaced from the valve seat to provide full pressure relief;a valve spring arrangement biasing the valve body toward the open position;an armature at the valve body; anda stator near the armature and including an actuator operative to urge the valve body toward the closed position against the bias of the valve spring.