| 摘要 |
PROBLEM TO BE SOLVED: To provide a combination of a piston ring and a piston which correctly retains force for projecting the piston ring toward the outside periphery and improves the sealing performance in the upside of the ring-groove in the piston. SOLUTION: An urging means 5 presses the back of the piston ring 1 from the diagonally down part. The urging means 5 is inserted in a recess 6 formed in the bottom face 3a of the ring groove 3 of the piston 2. Beside a second ring, the piston ring includes an oil-ring provided with a coil expander. In the case of the oil-ring provided with the coil expander, the biassing means presses the coil expander in the diagonally down part. As biassing means, used are a leaf spring which has a plurality of humps formed circumferentially at intervals in contact with the bottom face of the recess formed in the ring groove bottom, an expander corrugate in the axial direction, an expander corrugate in the radial direction, or a coil expander. COPYRIGHT: (C)2008,JPO&INPIT
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