FIELD: mechanical engineering; internal combustion engines. SUBSTANCE: piston ring is fitted in one of several ring grooves on peripheral surface of piston arranged along common axis. Each ring groove has upper and lower surfaces and groove bottom. Height of piston ring along axis is less than distance between upper and lower surfaces of groove along axis in corresponding groove. Piston ring has gap providing expansion of ring diameter when fitting ring in ring groove. Several leak slots made on lower surface of piston ring are spaced over ring periphery. These slots are made in form of cut whose width is pointed to ring periphery being several times larger than height of slot passing in axial direction. When surface of piston bottom adjoins lower surface of groove, gas can leak through leak slots which reduces pressure differential on piston ring. EFFECT: improved reliability and increased service life of piston ring. 9 cl, 7 dwg
