Combined oil ring with spacer/expander having Cr.sub.2 N coating thereon
AssigneeTeikoku Piston Ring Co., Ltd.
InventorsShoji Tanaka, Nobuyuki Yamashita, Hiroto Fukutome
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Abstract
A combined oil ring is comprised of paired upper and lower side rails, and a spacer expander. The side rails are made of martensitic stainless steel and are subjected to gas nitriding. The spacer expander is made of austenitic stainless steel, with a substantially U-shaped cross section, and has an under layer formed by soft nitriding, and has a Cr.sub.2 N film. The Cr.sub.2 N film has a hardness of HV1300 to HV2000 and a thickness of 3 .mu.m to 30 .mu.m. The Cr.sub.2 N film is formed by ion plating on the soft-nitrided layer of the outer circumferential surface.
Claims4
A combined oil ring comprising one spacer expander and two side rails, said spacer expander having side rail pressing portions for pressing said side rails, said side rail pressing portions having a Cr.sub.2 N film at the portion contacting said side rail, and said Cr.sub.2 N film having a Vickers hardness of HV1300 to HV2000.
Dependencies are inferred from the claim text.