MULTI-LINK PISTON-CRANK MECHANISM FOR INTERNAL COMBUSTION ENGINE

摘要

A lower link (13) is formed such that the outsides of end sections of a crankpin through-hole (21) are stiffer than a middle section of said crankpin through-hole (21), i.e. the bifurcation section of the bifurcated shape thereof. The end sections of the crankpin through-hole (21) are formed such that with no load input on the lower link (13), the inside surfaces (22a) of said end sections are curved with a prescribed radius of curvature in the axial direction of a crankshaft. The middle section of the crankpin through-hole (21) is formed such that with no load input on the lower link (13), the inside surface (22b) of said middle section is located inwards of the inside surfaces (22a) of the end sections and is straight in the axial direction of the crankshaft.