| 摘要 |
<P>PROBLEM TO BE SOLVED: To secure a passage area of a back passage compatibly with suppressing an oil ring from being broken during piston assembly. <P>SOLUTION: Within an oil ring groove 21, regulation parts 28 and 29 are provided which are brought into contact with an oil ring body 41 to regulate the move of an oil ring 40 to the inside of a radial direction. A position of an inner peripheral surface 44 of the oil ring body 41 most approaching an inner bottom surface 24 of the oil ring groove 21 in the state of bringing the oil ring body 41 expanded to a free diameter into contact with the regulation parts 28 and 29 is defined as a second most approaching position 51. In a land 26 being adjacent to a combustion chamber side with respect to the oil ring groove 21 on an outer circumferential surface of a piston 20, a position opposed to the second most approaching position 51 with a center axial line CL of the piston 20 interposed therebetween is defined as a second opposite-side position 32. A distance L2 between both the positions 51 and 32 is set larger than a diameter D of the inner peripheral surface 44 of the oil ring body 41. <P>COPYRIGHT: (C)2013,JPO&INPIT |
