| 摘要 |
PROBLEM TO BE SOLVED: To provide a cylinder capable of reducing reciprocating motion friction between a piston and the inner wall face of the cylinder, and maintaining an effect of the reduction. SOLUTION: The cylinder on the inner wall face of which the piston slides has a plurality of recessed portions formed in a stroke center region between the lower face position of a ring groove of a piston ring at the lowest position of the top dead center of the piston and the upper face position of the ring groove of the piston ring at the highest position on the bottom dead center of the piston. On at least part of the inner peripheral face of each of the recessed portions, a surface treatment layer is formed which contains one or both copper metal and fluororesin or which is subjected to phosphate film treatment. COPYRIGHT: (C)2011,JPO&INPIT |
