| 摘要 |
PURPOSE:To prevent a relative movement caused between a piston ring and a piston main unit, by mounting the piston ring of tetrafluoroethylene resin engaging with a peripheral surface of the piston main unit equipping an engaging means. CONSTITUTION:A piston main unit 1 provides both a through hole 1a in a direction of the axial center and plural strips of engaging grooves 3 fully over a peripheral surface of the piston main unit in its circumferential direction. A piston ring 2, being formed in a cylindrical shape and providing on its internal peripheral surface annular protrusions 2a formed profiling a shape of the engaging grooves 3, engages said annular protrusion 2a with the engaging groove 3 of the piston main unit 1. |
