Combined oil control ring

摘要

To provide a combined oil control ring with a function of preventing the separate rotation of side rails for a long period of time even under fretting fatigue, seating tabs of a spacer expander are provided with substantially longitudinal projections and recesses on their side-rail-pushing surfaces in a circumferential direction, the width m of a bottom surface being larger than the circumferential length m′ of the top surface in each projection, and a surface connecting the top surface to a recess surface having a bulging shape.

主权项

1. A combined oil control ring comprising two upper and lower side rails, and a spacer expander sandwiched thereby,
said spacer expander having seating tabs on the inner side for pushing inner surfaces of said side rails; a side-rail-pushing surface of each of said seating tabs having a plurality of substantially longitudinal projections and recesses, the projections and recesses alternately arranged in a circumferential direction; the width m of a bottom surface being larger than the circumferential length m′ of a top surface in each projection; and a surface connecting said top surface of each projection to said recess surface having a bulging shape.