| 摘要 |
PURPOSE:To improve gas tightness of a piston ring, by providing a groove in an internally peripheral intermediate part simultaneously equipping the piston ring, provided with vertically different positioned two matings, and fitting a different ring to said groove in a mating part of the before said ring. CONSTITUTION:The first ring 1, having a sliding surface in its periphery and a groove 19 in its internally peripheral side, is arranged, while the second ring 2 is arranged throughout said groove 19 and a groove 41 provided in the bottom 43 of a piston ring groove. The second ring 2 is provided with externally acting tension and contacted to an internally peripheral part 113 of the groove 19. Mating of the first ring 1 is formed to shape provided at least axially with a step difference to obtain upper and lower matings 151, 152, and a position of their step difference 150 is located not higher than the second ring upper surface 22 while not lower than the second ring lower surface 24. In this way, gas intruding from the upper mating 151 can be blocked its leak because the second ring 2 is adapted to a side of the internally peripheral surface 113 of the first ring groove. |
