US Patent 8177237 Gastight piston ring arrangement

A segmented piston ring assembly includes piston ring segments 2 having stepped ends 5, 6, at least one piston ring segment 2 including a radial step on a radially inner peripheral surface 9 over a part of the width of the piston ring segment 2, and a single-cut sealing ring 3, which bears radially against the inside of the peripheral surface 9 of the piston ring segments 2, the sealing ring 3 including an axial recess 10, 12 which cooperates with the radial step 4 of the piston ring segment 2 to prevent relative rotation therebetween.