Patent ID: 7306233

Claim:
A combined oil control ring consisting of: an oil ring body which is integrally formed of upper and lower rails which bring outer peripheral surfaces thereof into slide contact with an inner surface of a cylinder and a web which connects said upper and lower rails and includes a plurality of windows, and a coil expander which pushes said oil ring body in the direction toward said inner surface of said cylinder, said coil expander being housed in an inner-peripheral groove portion of said oil ring body, wherein projecting portions which extend toward a center line in the thickness direction are formed at inner peripheral sides in the radial direction than a position where an axial distance between inner peripheries of said inner-peripheral groove portion of said oil ring body becomes maximum, wherein the axial distance between inner-peripheries of said inner-peripheral groove portion of the oil ring body is smaller than a maximum distance L 2 , in an inner portion than the position of L 2 , and wherein a minimum distance L 1 and the maximum distance L 2 satisfy a relationship of 0.03≦(L 2 −L 1 )/L 1 ≦0.15, said minimum distance L 1 being said axial distance between inner-peripheries of the inner-peripheral groove portion of said oil ring body.