Patent ID: 7270047

Claim:
A fuel injection pump for delivering high pressure fuel to an internal combustion engine comprising; a drive shaft driven by the internal combustion engine; an eccentric cam attached to the drive shaft and rotatable together therewith; a cam ring member whose inner circumferential face is in slidable contact with an outer circumference of the eccentric cam; a cylinder formed in a pump housing; a housing bore formed in the pump housing; a cup-shaped drive force transmission member having a side wall slidably and reciprocatingly held in the housing bore, a bottom outer surface of the drive force transmission member being in slidable contact with an outer circumferential face of the cam ring member; and a plunger slidably housed in the cylinder, an axial end face of the plunger being in slidable contact with a bottom inner surface of the drive force transmission member and fuel being sucked and compressed in the cylinder on a side of the other axial end of the plunger according to a reciprocating movement of the plunger caused by a transmitting force from the drive shaft via the eccentric cam and the cam ring member, wherein at least one of the drive force transmission member and the cam ring member is provided on an axial center line of the plunger with a hollow whose depth is gradually deeper from an outer periphery to a center thereof at least in an axial direction of the cam ring member so that the transmitting force skirts around the hollow and diameter of the hollow becomes smaller due to resilient deformation thereof as the transmitting force becomes stronger, and wherein the diameter of the hollow is larger than that of the plunger at the axial end thereof when the transmitting force is not applied.