| 摘要 |
PROBLEM TO BE SOLVED: To provide a combined oil ring capable of holding performance of a low tensile strength oil ring from the initial time and maintaining it for a long time. SOLUTION: This combined oil ring is composed of the oil ring 1 and a coil expander 2 for pressing it outward in the radial direction. An amorphous hard carbon system coating 10 is formed in a part in contact with the coil expander 2 on an inner peripheral face of the oil ring 1. An inner peripheral side edge of an oil return hole 6 provided in the oil ring 1 has a circular arc shape. Hardness of the amorphous hard carbon system coating 10 is HV 700 to 2000, and thickness of the coating is 0.8 to 10μm. COPYRIGHT: (C)2007,JPO&INPIT
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