| 摘要 |
PURPOSE:To reliably prevent the leakage of a combustion gas, by forming an annular groove for isolating the inside from the outside at the peripheral portion of a suction and exhaust opening. CONSTITUTION:To enhance the gas tight at the slide contact portion between a suction and exhaust opening 15 and a head portion 14 when a cylinder 7 is in a suction air compression stroke and an explosion and expansion stroke, a thrust ring 59 with a seal ring 58 is fitted at an opening shoulder of the suction and exhaust opening 15. Accordingly, the pressure in the cylinder 7 is operated to a front gap 60 of the thrust ring 59, thereby tightly contacting the thrust ring 59 with the head portion 14. Furthermore, the head portion 14 is formed at its end surface with an annular groove 61 for recovering a gas leaked from the suction and exhaust through a passage 62 to a suction hole 17. Therefore, the gas recovered by the groove 61 is returned together with the suction air to the cylinder 7. |
