| 摘要 |
PROBLEM TO BE SOLVED: To provide a two-piece piston ring capable of retaining a more stable attitude when a piston reciprocates. SOLUTION: In an internal combustion engine, a first to third ring grooves are formed in an order from the top on the outer peripheral surface in the piston 10 reciprocating in a cylinder 50. A compression ring is disposed in the first and second rings. An oil ring 16 is disposed in the third ring groove 13. The oil ring 16 is provided with a coil expander 21 disposed in a ring main body 17 and the inner peripheral side of the ring main body 17 to urge the ring main body 17 radially outward. In the longitudinal section containing the central axis of the piston 10, a gravity center B of the ring main body 17 agrees with a gravity center A of the coil expander 21 with respect to the radial direction of the piston 10. COPYRIGHT: (C)2008,JPO&INPIT
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