| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve the reliability.SOLUTION: A piston 40 includes: a roller 41 having an annular roller body 44 and a bearing metal 47 disposed at an inner peripheral part of the roller body 44; and a blade extending from an outer peripheral surface of the roller 41. In the piston 40, an oil passage 48 provided between the roller body 44 and the bearing metal 47, an inflow part 48b opening on an inner peripheral surface of the roller 41 and where a lubrication oil L flows in toward the oil passage 48, and an outflow part 48c opening on an upper end surface of the roller 41 and where the lubrication oil L from the oil passage 48 flows out are formed.</p> |
