| 摘要 |
<p>PROBLEM TO BE SOLVED: To control deformation due to the abrasion of a piston ring to secure stable sealing performance extending over a long term. SOLUTION: A ring groove 32 and a rider ring groove 33 are formed on the outer periphery 31A of a piston 31. In the ring groove 32, a piston ring 34 is attached between the inner periphery 6A of a cylinder 6 and the groove 32. In addition, in a piston ring 34, a tapered part 35 is formed between a lower side face 34B and an outer periphery 34D, and the piston ring 34 is formed thinner from the inner peripheral end 35A of the tapered part 35 toward its outer periphery 34D because of the tapered part 35. When the lower side face 34B of the piston ring 34 is pressed against the lower wall face 32B of the ring groove 32 in a compression stroke, a state where the tapered part 35 separates from the corner part C of the ring groove 32 can therefore be kept.</p> |
