Main bearing for crankshaft of internal combustion engine

摘要

A main bearing 19 for a crankshaft of an internal combustion engine is composed of a pair of semi-cylindrical bearings 17, 18. An oil groove 17a extending in a circumferential direction is formed on an inner circumferential surface 17S of one semi-cylindrical bearing. The oil groove has the depth gradually decreasing toward a circumferential end surface 17A of the one semi-cylindrical bearing, and defines a circumferential end portion 17E on the circumferential surface without extending to an axial groove 24A formed in a joint portion of the pair of semi-cylindrical bearings. An extension portion 17S' of the inner circumferential surface extends between the circumferential end portion and the axial groove, and a plurality of circumferential grooves 17m extending in the circumferential direction is formed on the extension portion from the oil groove to the axial groove over an entire width of the circumferential end portion of the oil groove.