| 摘要 |
PROBLEM TO BE SOLVED: To provide a piston structure which can retain a cooling effect of an outer edge of a piston as before and which can improve the cooling effect of the midsection of the piston without having any influence on fuel efficiency. SOLUTION: A cooling channel (an oil passage for cooling the piston) of the piston structure 10 is provided with an annular circulating passage 11 and a center passage 12. The annular circulating passage 11 is provided to the back of the top surface of the piston along the outer edge of the piston, and the oil injected from an oil jet flows in the annular circulating passage 11. The center passage 12 temporarily branches off from the circulating passage 11 and passes through the back of the midsection of the top surface of the piston. After that, the center passage 12 merges with the circulating passage 11 again. COPYRIGHT: (C)2010,JPO&INPIT
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