| 摘要 |
PURPOSE:To effectively prevent noise and vibration and to attain effective temperature compensating action by providing a synthetic resin layer on the outer peripheral surface of a piston, which comprises portions which are brought into sliding contact with the inner peripheral surface of a cylinder at the normal temperature and portions which are separated from the inner peripheral surface of the cylinder at the normal temperature. CONSTITUTION:The thickness (t) of a synthetic resin layer 5 disposed on the outer peripheral surface of a piston 3 is uniform, and the outer peripheral surface of the cylinder resin layer 5 is substantially quadrilateral. Four corners of the substantial quadrilateral are formed in a circular-arc to construct portions 5a brought into sliding contact with the inner peripheral surface of a cylinder 1, and the other portions thereof construct separate portions 5b separated from the inner peripheral surface of the cylinder 1. Thermal expansion is larger in the peripheral direction, and the thermal expansion is consumed by clearances at the separate portions 5b. Accordingly, at the sliding portions 5a, thermal expansion in direction of thickness (t) may be considered, so that the clearances can be reduced to reliably prevent vibration and noise. |
