| 摘要 |
PROBLEM TO BE SOLVED: To reduce a contact surface pressure with a piston, and improve durability of a bearing by forming a contact part of a rotary ring on a recessed circular cone surface, in a rolling bearing which is slantly arranged with respect to a plurality of pistons capable of sliding in an axial direction in a cylinder block, and which is provided with a plurality of rolling elements. SOLUTION: When a rotary shaft 1 is rotatively driven, a cylinder block 2 and each piston 3 are rotated. During this rotation, each piston 3 is moved in reciprocation being brought into contact with a rotary ring 5a of a thrust rolling bearing 5 which is slantly arranged with respect to an axis of the cylinder block 2. Oil sucked into an oil chamber 6 by passing a suction port 11 is boosted up, and is discharged from a discharge port 12. The thrust rolling bearing 5 is composed of the rotary ring 5a, a fixing ring 5b, and a plurality of rolling elements 5c interposed between the rings 5a, 5b. In this case, at least a contact part with the piston 3 in end surfaces 5a2 of the bearing outer side of the rotary ring 5a, is formed on a recessed circular cone surface so as to reduce contact surface pressure of the contact part.
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