To provide a cylinder reducing reciprocating friction with a piston, and avoiding longitudinal scratch and excessive friction that possibly occur between a piston skirt portion and a cylinder.
In a stroke central part region which is a region ranging from a lower surface position of a ring groove of a lowermost piston ring in a top dead center of the piston, to an upper surface position of a ring groove of an uppermost piston ring in a bottom dead center of the piston, a plurality of recessed portions are formed so that at least one recessed portion in all cross-sections in a circumferential direction of cylinder exists, and the recessed portion is not formed in a region except for the stroke central region, out of inner wall surfaces of the cylinder. A total of areas of all recessed portions is to be within a range of 1 to 80%, when an area of the stroke central region is assumed to be 100%. Out of a region that slides with a piston skirt at a thrust side of the piston used in combination with the cylinder, in the stroke central region, at least 1/4 or more thereof is to be a region where the recessed portion is not formed.
COPYRIGHT: (C)2011,JPO&INPIT
MURATA TAIICHI
JP2007132247A | 2007-05-31 | |||
JP2005090442A | 2005-04-07 | |||
JP2007002989A | 2007-01-11 | |||
JP2002235852A | 2002-08-23 | |||
JPS6158656U | 1986-04-19 | |||
JPS6259743U | 1987-04-14 |
WO2009044824A1 | 2009-04-09 |
Yoshinori Ishibashi