Patent ID: 6886521

Claim:
A sliding structure for an automotive engine, comprising: a sliding member being one selected from the group consisting of a piston ring, a piston pin, a piston skirt, a cam lobe, a cam journal, a plain bearing, a rotary vane and a timing chain, and including a sliding portion; and a lubricant applied to the sliding portion so that the sliding portion can make sliding contact with a counterpart member via the lubricant, wherein the sliding portion has a base made of either a steel material or an aluminum material and a hard carbon film formed on the base to coat the sliding portion, and the hard carbon film has a thickness of 0.3 to 2.0 Î¼m, a Knoop hardness of 1500 to 4500 kg/mm 2 , a surface roughness Ry (Î¼m) satisfying the following equation: Ry <{(0.75âˆ’ Hk/ 8000)Ã— h+ 0.07/0.8} where h is the thickness (Î¼m) of the hard carbon film; and Hk is the Knoop hardness (kg/mm 2 ) of the hard carbon film.