| 摘要 |
PURPOSE:To uniformize clearances at both end surfaces of a piston and reduce the amount of leakage by a method wherein a slanted groove, located in the manner that the lower end opening is positioned in an advanced direction further than the upper end opening with respect to the rotating direction of a shaft and communicated with both end openings, is provided on the inner peripheral surface of the piston. CONSTITUTION:The inner peripheral surface of the piston 7 is provided with the slanted groove 31, located so that the lower end opening is positioned in the advanced direction than the upper end opening with respect to the rotating direction of the shaft 5 and communicated with both end openings. The piston 7 rotates with a speed slower than an eccentric pin 6 at all times, therefore, oil which flows on a sliding surface, collides against the slanted groove 31 and the flow thereof is curved as shown by an arrow sign 32 in the diagram. On the other hand, the oil receives a force shown by the arrow sign 33 as the reaction therefor, therefore, an upward component or a force in a direction to lift up the piston 7 is received by the oil as the component of the force shown by the arrow sign 33 as shown by the arrow sign 34 in the diagram. The upward component can be selected arbitrarily by changing a slant angle 35, therefore, the angle, in which the component 34 balances with the gravity of the piston 7, may be selected. According to this method, the clearances of both end surfaces of the piston 7 may be uniformized to reduce the amount of leakage and the performance coefficient of the piston may be improved.
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