Crank mechanism of reciprocating internal combustion engine of multi-link type

摘要

A paired counterweights of a crankshaft have projected inner surfaces which protrude toward each other defining a given space therebetween. A plurality of links are arranged to convert a reciprocating motion of a piston to a rotational motion of the crankshaft. One of the links is pivotally connected to other links through link connecting portions and swingably disposed on a crank pin of the crankshaft so that upon rotation of the crankshaft, a peripheral portion of the link passes through the given space. At least one of the link connecting portions is placed within an imaginary circle which would be described by a radially innermost part of the projected inner surfaces of the paired counterweights when the paired counterweights turn about an axis of the crank pin.