Patent ID: 7261301

Claim:
Oil wiping ring for pistons of internal combustion engines, consisting of a lamella ( 1 ) whose working surface (h) has a barrel-shaped asymmetrical shape, having a vertex line ( 3 ) that extends over the circumference of the lamella, whereby the lamella ( 1 ) is disposed in a ring groove ( 7 ) of the piston, having one ring groove wall ( 6 ) facing away from the piston crown side and one ring groove wall ( 5 ) facing the piston crown side, disposed parallel to one another, in each instance, wherein the lamella walls ( 2 , 2 ′) run radially outward up to the working surface (h), at an angle (α), converging towards one another in such a manner that when one of the walls makes contact with the ring groove wall ( 5 ) that faces the piston crown side, the lamella stands in contact with the cylinder wall ( 8 ) of the engine only with the vertex line ( 3 ), and when one of the lamella walls makes contact with the ring groove wall ( 6 ) that faces away from the piston crown side, the lamella stands in contact with the cylinder wall only with the first segment (I) of the working surface (h), whereby the working surface (h) of the lamella ( 1 ), in cross-section, follows the asymmetrical shape of a polynomial of the second order in a first segment (I), with h(x)=ax+bx 2 , whereby x=working surface coordinates in the Cartesian coordinate system in mm, and a, b are coefficients, with a being defined by the ratio of the axial wall play of the lamellae relative to the width of the lamellae; b being defined as the amount of the working surface curvature; a supporting vertex (II) h(x=0) configured as an edge, and in a third segment (III) follows the asymmetrical shape of the function h(x)=cx 2 , with c as a multiple of b.