| 摘要 |
PROBLEM TO BE SOLVED: To provide a piston structure for an engine materializing smooth oil return by providing oil return passages releasing oil swept therein by an oil ring on a wide area in a ring groove. SOLUTION: Hollows 16, 17 forming spaces opening downward are formed on a ring groove back surface side of a land part toward an outside of side wall parts 9, 10. Oil return holes 15a, 15b, 15c, 15f, 15g, 15h releasing oil swept into the ring groove 5 (oil ring groove) are provided with using the hollows 16, 17. Consequently, swept oil can be smoothly released without receiving pressure of oil injection for cooling from a lower part. COPYRIGHT: (C)2008,JPO&INPIT
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