Combined oil ring
AssigneeTeikoku Piston Ring Co., Ltd.
InventorsAkira Harayama, Kazuyoshi Aruga
Life of this patent
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Abstract
A combined oil ring is comprised of a steel oil ring having a generally I-shaped section consisting of upper and lower rails and a web connecting the both rails and a coil expander for forcing the oil ring outwardly. Each of the outer circumferential sliding surfaces of the circumferential outer projecting portions in the upper and lower rails forms a nitrided surface with a hardness of Hv 900 or more, at least one of the upper and lower surfaces in the circumferential outer projecting portion forms a surface with a hardness of lower than Hv 700, and a width of the outer circumferential sliding surface is smaller than 0.25 mm. The other surface of the upper and lower surfaces forms a nitrided surface with a hardness of Hv 900 or more or a surface with a hardness of lower than Hv 700.
Claims10
A combined oil ring for a piston engine comprising a steel oil ring having a generally I-shaped section consisting of upper and lower rails and a web connecting the upper and lower rails and a coil expander for forcing the oil ring outwardly, wherein each outer projecting portions in said upper and lower rails is coated with a nitrided layer having a hardness of Hv 900 or more, at least one of an upper and a lower surface connecting with the outer circumferential sliding surface at said circumferential outer projecting portion forms a surface lacking said nitrided layer and having a hardness lower than Hv 700, and an axial width of said outer circumferential sliding surface is smaller than 0.25 mm.
Dependencies are inferred from the claim text.