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US 7,024,982 B2Granted
Combination of piston and piston ring
AssigneeNippon Piston Ring Co., Ltd.
InventorsTakeshi Aizawa, Manabu Kishida, Makoto Kajiwara
Life of this patent
Estimating the term…
Abstract
A combination of piston and piston ring includes a piston having a piston ring groove in which at least the groove portion of the piston is made of steel, a piston ring made of cast iron and fitted into the piston ring groove, and a hard coat film formed to at least an outer peripheral sliding surface of the piston ring.
Claims12
A combination of piston and piston ring, comprising:
- a piston having a piston ring groove in which at least the piston ring groove is made of SKD6, SUS305 or SUS630, said piston reciprocally moving in a cylinder bore;
- a piston ring made of flake graphite cast, iron or spheroidal graphite cast iron, having an elastic modulus ranging from 130000 to 170000 MPa, in which at least a lower surface of the piston ring is formed with irregularity on the surface due to an existence of the graphite and the tower surface of the piston ring is fitted to contact the lower surface of the piston ring groove;
- and
- a hard coat film formed to at least an outer peripheral sliding surface of the piston ring.
1 more element
A method for reducing the tendency of a piston ring to adhere to a piston ring groove made of SKD6, SUS305 or SUS630 in a reciprocating piston of an internal combustion engine, said method comprising:
- applying a hard coat film to at least an outer peripheral sliding surface of a piston ring made of flake graphite cast iron or spheroidal graphite cast iron, having an elastic modulus ranging from 130000 to 170000 MPa, in which at least a lower surface of the piston ring is formed with irregularity on the surface due to an existence of the graphite;
- and
- fitting said surface-coated cast iron piston ring into said steel piston ring groove so that said lower surface is fitted to contact the lower surface of the piston ring groove.
Dependencies are inferred from the claim text.