| 摘要 |
PURPOSE:To prevent the generation of seizure between a sleeve and a piston skirt part during operation by reducing the fastening portion of the lower part from a scavenging port within the range of piston transfer among the fitting region of the sleeve for a cylinder block. CONSTITUTION:Among the insertion region for a cylinder sleeve 13 for a cylinder block 11, the lower part from a scavenging port 26 is set as a fastening- portion reducing region L1. The outer surface 28 of the sleeve 13 corresponding to said region L1 is formed into a small-diameter part 28, and a step difference is formed between the outer surface 30 corresponding to other fastening-portion providing region. Therefore, in an internal-combustion engine 10, the outer surface 30 of the sleeve 13 is press-fitted into the insertion hole 12 on the cylinder block 11 with a prescribed press-fitting fastening portion, and a gap is formed in the fastening-portion reducing region on the outer surface 28 of the sleeve 13. Therefore, even in the state where the cylinder block 11 and the sleeve 13 generate the thermal expansion during operation, seizure is not generated between the sleeve 13 and a piston skirt part. |
