Stabilized bearing structure for supporting a crankshaft in an internal combustion engine, and engine including same

Abstract

An internal combustion engine includes a split crankcase with spaced-apart journal walls. Each journal wall has a bearing hole formed therein. The engine also includes rotary bearings for supporting rotary movement of a crankshaft. A backlash-absorbing mechanism is situated proximate a first one of the rotary bearings, for cushioning radial movement of an outer bearing race. Axial movement-restraining structure is also provided adjacent the outer race, for limiting axial movement thereof. The axial movement-restraining structure may include an engaging groove provided in an inner circumferential surface of the outer race, and a restraining clamp member operatively attached to a surface of the crankcase. The restraining clamp member may include a hook portion which engages with the engaging groove of the outer race. The axial movement-restraining structure allows at least one of the crankshaft support bearings to be a roller bearing or a needle bearing, instead of a ball bearing.