Fuel injection pump of the distributor type with a magnetically actuated valve member of a switching valve connected to a low-pressure piston

A fuel injection pump of the distributor type for supplying at least one injection nozzle of an internal combustion engine, comprising, at least one pump piston (17), driven in a reciprocating stroke motion, which defines a pump work chamber (18) that is connected to a fuel inlet and upon each pumping stroke, pumps fuel at injection pressure to one of the plurality of injection nozzles;

• a rotating distributor shaft (11), which upon its rotation, via a distributor bore (19), establishes a communication between the pump work chamber (18) and the plurality of injection nozzles;
• and having a switching valve (25) for metering the fuel injection quantity, a valve member (35) which controls a valve opening (33), a valve seat (34) between a first valve chamber (36) that communicates with the distributor bore (19), and a second valve chamber (24) that communicates with a relief bore (27), said valve member lifted away from the valve seat (34) by means of a valve spring (44) acting in the valve opening direction and is displaced upon valve opening counter to the flow of fuel flowing out via the valve opening (33), further comprising an electromagnet (16) with a magnet armature (54) for actuating the valve member (35) in the valve closing direction, and a low-pressure piston (43) coaxial with the valve member (35) is rigidly connected to said valve member via a reduced-diameter tang (56), which protrudes into the second valve chamber (24) and is axially guided with minimal radial play, by its end remote from the valve opening (33), in a cylindrical wall segment (26) adjoining the second wall chamber (24), the valve spring (44) is received in a leakage fluid collecting chamber (23) connected to a fuel return line, which has a spring on its face end adjoining the low-pressure piston (43) following the cylindrical wall segment (26), where one end of the spring is braced against the bottom of the leakage fluid collecting chamber (23) and with another end against the face end of the low-pressure piston (43), and the two valve chambers (36, 24), the valve opening (33) with the valve seat (34), and the cylindrical wall segment (26), as well as the leakage fluid collecting chamber (23) together with the valve member (35) and the low-pressure piston are embodied in a central blind bore (22) in the distributor shaft (11), which blind bore is closed from an outside by the valve member, and the magnet armature (54) of the electromagnet (16) comes to act upon an outward-pointing face end of the valve member (35).