PURPOSE: To shorten the length of a crankshaft by offsetting a crank pin journal which axially supports the connecting rod of at least one cylinder among the cylinders at both the edge parts in the crankshaft direction, inward for an engine in the crank axis direction for a cylinder bore.
CONSTITUTION: In a series type four-cylinder engine, the center line m1 of a crank pin journal 7A which axially supports the connecting rod 6A of a cylinder at the front edge is set off by the distance L1 inward (rearward) from an engine in the axis line 3a direction of a crankshaft 3 for the center line l1 of the cylinder bore 2A of the cylinder. Oppositely to the crank pin journal 7A, the connecting rod 6A is bent at a position 11A. Further, a web part 12A between the crank pin journal 7A of the crankshaft 3 and a pin journal 5B behind the crank pin journal 7A is formed thin in thickness in correspondence with the rearward offset of the crank pin journal 7A. Further, also the similar processing is carried out also on the cylinder side at the rear edge.
OSHIMA HIROBUMI
KAWABE YASUAKI
