| 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 (3), which has seating tabs (6) for pushing inner surfaces of the side rails (3) on the inner side, a side rail-pushing surface of each seating tab (6) 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 having micro-Vickers hardness HV0.1 of 700 or more meeting the relation of the 0.05 ‰¤ 1000 x d/(h x t) ‰¤ 0.45. |
