In-line four cylinder engine for vehicle and vehicle provided with the engine

摘要

A two-plane type crankshaft is provided. The weight of crank webs for the respective cylinders is divided between left and right half webs and balance ratios kL and kR of the half webs for the respective cylinders are set so as to be (kL−0.25)·(0.25−kR)≅DR/DL to form a track of a vector of a primary inertial couple into a substantial circle. A primary balancer offsets the primary inertia couple.