Patent ID: 7086362

Claim:
A shim or a valve lifter for an automotive engine valve driving system that slides against a cam lobe of a camshaft to drive an intake/exhaust valve of an internal combustion engine, the shim or lifter having the top of a sliding surface thereof opposing the cam lobe and being coated with a hard carbon film, said hard carbon film having a surface hardness of 1500 to 4500 kg/mm 2 in terms of Knoop hardness, a thickness of 0.3 to 2.0 μm and a surface roughness Ry (μm) satisfying the following equation (A): Ry<{( 0.75 −Hk/ 8000)× h+ 0.07/0.8} (A) where h is the thickness (μm) of the hard carbon film, and Hk is the knoop hardness (kg/mm 2 ) of the hard carbon film.