| 摘要 |
PROBLEM TO BE SOLVED: To improve airtightness between a piston and a piston ring. SOLUTION: The piston ring 21 is fitted in a ring groove 8a provided on an outer periphery of the piston 8 reciprocating in a cylinder 9, and a ring back-up seal 20 is provided on the inside of the piston ring 21. An outward flange 20c interposed between an inside surface part 8b of the ring groove 8a facing the compressing and moving direction of the piston 8 and an outside surface part 20c of the piston ring 20 confronting the inside surface part 8b is integrally provided on a peripheral edge of the back-up seal 20. COPYRIGHT: (C)2008,JPO&INPIT
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