Piston assembly and piston ring structure

Abstract

The invention relates to a piston and piston ring assembly in which the piston ring assembly fitted to the piston includes the first compression ring, the second compression ring, the third compression ring and the oil ring. When the axial width of the first compression ring is h1(1), the axial width of the second compression ring is h1(2), the axial width of the third compression ring is h1(3) and the axial width of the oil ring is h1(4), hl(l) > hl(2) and hl(l) > hl(3), and when h1(TOTAL) = hl(l) + hl(2) + hl(3) + hl(4), hl(TOTAL) > 3.1 mm.