| 摘要 |
PROBLEM TO BE SOLVED: To provide a lightweight cam shaft for an internal combustion engine capable of suppressing wear of a cam lobe in sliding and also suppressing attacking to a counterpart when the cam lobe made of aluminum alloy is used. SOLUTION: This light weight cam shaft for the internal combustion engine is formed with the cam lobe made of an aluminum alloy containing 16.0 wt.% or more of Si where an average particle size of Si in a structure of the alloy is 10μm or less. Roughness of a sliding surface of the cam lobe is Ra 0.1μm or less, and 0.5 wt.% of SiC hard particle is contained in the cam lobe made of the aluminum alloy. A lifter shim or a valve lifter covered with hard thin film of the roughness of surface of Ra 0.05μm or less is assembled with the cam lobe made of the aluminum alloy to make the lightweight cam shaft for the internal combustion engine, and the hard thin film covering the lifter shim or the valve lifter is a hard coat selected from TiN, CrN, Cr2N, DLC (diamond like carbon).
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