Patent ID: 9657838
Date: 2017-05-23
CPC Classifications: F16J

Claim:
1. A combined oil control ring comprising: an annular upper side rail and an annular lower side rail; and an axially corrugated one piece annular spacer expander located between the upper side rail and the lower side and having a plurality of upper and lower portions, the upper and lower portions alternating in a circumferential direction of the combined oil control ring, wherein: a plurality of leg portions, the leg portions connecting each upper portion of said spacer expander to each adjacent lower portion of said spacer expander, each leg portion has a substantially straight main portion having an inclination angle θ of 25-50° from an axial direction, which is a direction along a main axis around which the combined oil control ring is formed, each of said upper and lower portions has a tab pressing an inner peripheral surface of one of said side rails, a projection supporting said one of said side rails, and an intermediate portion directly radially between said tab and said projection and of lower axial height than the tab and projection, a ratio (L/P) of an overall circumferential length (L) of each of said intermediate portions to a corrugation pitch (P), which is the circumferential distance between adjacent most upper portions or adjacent most lower portions, is 40% or less, and oil sludge accumulation is substantially reduced due to the inclination angle and ratio (L/P) during operation on a piston of an internal combustion engine.