FUEL INJECTION PUMP FOR INTERNAL COMBUSTION ENGINE

摘要

In a fuel injection pump (1) which is constituted so as to control incoming and outgoing of fuel to a suction-and-overflow hole (8) in which an early stage control groove (10) is formed with an upper-side control edge portion (11) and a lower-side control edge portion (12) of a pump plunger (4) reciprocating in the inside of a pump plunger bushing (3), a suction-and-overflow hole (8) includes a small-diameter hole (81) having an opening surface (14) to observe the inside of the pump plunger bushing (3) and a large-diameter hole (82) which is communicated with another end (81B) of the small-diameter hole (81), and a bottom portion (10A) of the early stage control groove (10) extends in an upwardly inclined manner in the direction away from the opening surface (14), and an inner surface of a communicating end portion of the large-diameter hole (82) with the small-diameter hole (81) is formed into a spherical surface portion (82C). The high-pressure fuel which is fed to the inside of the large-diameter hole (82) can ensure a large distance between the fed high-pressure fuel and a wall surface of the large-diameter hole (82) due to a spherical surface portion (82C) of the large-diameter hole (82) thus reducing a cavitation erosion effect.