| 摘要 |
PROBLEM TO BE SOLVED: To provide a piston ring which can maintain satisfactory seal property for a long period and is easy to incorporate. SOLUTION: A backup ring 12 is incorporated to the inside of a seal ring 11 having a joint having a step-cut shape, and elastically brought into contact with the inside diameter surface of the seal ring 11. A swollen portion 17 is provided on the outside diameter surface of the backup ring 12, and cutout portions 18 are formed on both end surfaces in the ring circumferential direction of the swollen portion 17. Lip portions 15 forming the joint of the seal ring 11 are engaged with the cutout portions 18, and the relative rotation of the seal ring 11 and the backup ring 12 is prevented by the engagement so that the joints of the seal ring 11 and the backup ring 12 are never overlapped to each other. The seal ring 11 and the backup ring 12 are relatively positioned in the axial direction by the engagement of the lip portions 15 with the cutout portions 18 to dispense with relative axial position adjustment operation of both the rings 11, 12 after incorporation of the piston ring to a ring groove of a piston. COPYRIGHT: (C)2011,JPO&INPIT
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