| 摘要 |
PURPOSE:To elevate pressure in an annular pocket section on a compression stroke, and to prevent the intrusion of combustion residue by forming the pocket section between a top ring and a second ring for the piston and communicating the pocket section with a top ring groove. CONSTITUTION:The pocket section 5 into which piston rings are not inserted is formed between the top ring 3 and the second piston ring 4 of the piston 2, a communicating hole 6 is formed between the groove of the top ring 3 and the pocket section 5, and the bottom of the top ring and pocket section 5 are communicated. A flat groove 7 for increasing a pressure area so that the bottom of the top ring is easily subject to the pressure of the pocket section 5 in a large amount from the communicating hole 6, is formed to the top ring 3, and a diametrical concave groove 8 for discharging a pure gas in the pocket section 5 in an expansion stroke is formed at a proper position in an upper surface. |
