| 摘要 |
<p>PROBLEM TO BE SOLVED: To suppress in low level the sliding resistance by the piston reciprocation by grinding an inner circumferential surface of a cylinder bore approximately in the direction along the axis of the cylinder bore. SOLUTION: A working joint 39 of an inner circumferential surface of cylinder bores 11a, 12a is provided so as to be directed approximately along the axis of the cylinder bores 11a, 12a, and extended in a gradually spiral manner along the rotational direction of a piston 28. The spiral angle of the working joint 39 is appropriately selected in the range of 5-30 deg. relative to the axial direction of the cylinder bores 11a, 12a. The sliding resistance becomes smaller as the spiral angle is the smaller, and the amount of the refrigerant gas to blow by in the compression becomes smaller as the spiral angle is the larger. Because the working joint 39 of the inner circumferential surface of the cylinder bores 11a, 12a is provided so as to be extended in the direction along the reciprocating motion of the piston 28, the sliding resistance is reduced corresponding to the natural movement of the piston 28. The working joint 39 is provided in a spiral manner, the oil can be stored in the working joint 38 to further reduce the sliding resistance.</p> |
