Patent ID: 8157268

Claim:
A piston ring ( 10 ) for an internal combustion engine, comprising a ring-shaped body ( 11 ) having a ring joint ( 13 ) formed by butt ends ( 14 a , 14 b ), said ring-shaped body ( 11 ) further having a ring contact face ( 12 ) along its perimeter, for contacting a cylinder wall in operation, wherein said ring contact face ( 12 ) has a barrel-shaped profile, said barrel-shaped profile having in any of its cross-sections an area of maximum curvature, whose radius of curvature increases in the direction of the butt ends ( 14 a , 14 b ), such that the piston ring ( 10 ) has a larger contact area in the regions of the butt ends 14 a , 14 b than in other regions of the piston ring, for contacting a cylinder wall in operation.