FUEL INJECTION PUMP FOR INTERNAL COMBUSTION ENGINE

摘要

A fuel injection pump (1) for an internal combustion engine so formed that the access of a fuel into at least one suction and overflow hole (8) formed in a pump plunger bush (3) can be controlled by a pump plunger (4) reciprocating in the pump plunger bush (3), wherein an early control groove (10) is formed in the wall part of the suction and overflow hole (8). The suction and overflow hole (8) comprises a small diameter hole (81) having, at its one end (81A), an opening face (14) for observing the inside of the pump plunger bush (3) and a large diameter hole (82) communicating with the other end (81B) of the small diameter hole (81). The bottom part (10A) of the early control groove (10) is extended to the diagonal upper side in the direction apart from the opening face (14). The inner surface of the communication end part of the large diameter hole (82) with the small diameter hole (81) is formed in a curved surface part (82C), and the opened end part of the large diameter hole (82) is formed in a chamfered end edge (82M). Since the shape of the suction and overflow hole (8) can be optimized, the occurrence of cavitation erosion can be further reduced.