US Patent 7513506 Plunger seal for pump

There is provided a plunger seal (1) for a fuel injection pump for a direct-injection gasoline engine, in which, even if a resin material is used for a fuel seal member (12), the plunger seal can be made compact, sealing ability is increased, and assembling man-hours can be reduced, and in which set sealing performance can be achieved when a U-shaped elastic member (33) for applying an energizing force in a diametrical direction is used in a groove (41) formed in the fuel seal member (12). The resin fuel seal member (12) and an oil seal member (13) are assembled to form one seal system. Further, when the U-shaped elastic member (33) is installed in the groove (41), an axial position (L1) of an end surface (44a) at the side opposite to the sealed object of a fixing collar (44) formed on an inner peripheral surface of the groove (41) is positioned at the side (B) opposite to the sealed object than the axial position (L2) of a leading end portion (15b) of a seal lip (15) of the fuel seal member (12).