| 摘要 |
A combined oil control ring comprising a pair of circular side rails (3) each having a gap, and a spacer expander (2) longitudinally sandwiched by the side rails, which has seating tabs (6) for pushing inner surfaces of the side rails on the inner side, a side rail-pushing surface (60) of each seating tab being provided with one or more grooves extending substantially longitudinally; each of the side rail-pushing surfaces including the grooves being provided with a nitride layer, and the depth d (µm) of the grooves, the surface hardness h (micro-Vickers hardness HV0.1) of the nitride layer, and the thickness t (µm) of the nitride layer meeting the relation of the formula 0.05 ‰¤ 1000 x d/(h x t) ‰¤ 0.45, wherein the surface hardness (h) of said nitride layer is 1100-1450. |
