Main bearing for crankshaft of internal combustion engine

A main bearing for a crankshaft of an internal combustion engine for rotatably supporting a journal section of the crankshaft, the journal section including a lubricating oil path extending therein, and an inlet opening of the lubricating oil path that is formed on an outer circumferential surface thereof, wherein

• the main bearing is composed of a pair of semi-cylindrical bearings, and any one of the semi-cylindrical bearings has an oil groove formed on an inner circumferential surface thereof,
• the oil groove extends in a circumferential direction at least through a central portion of the one semi-cylindrical bearing in the circumferential direction and is arranged so that the center of the width of the oil groove in an axial direction aligns with the center of the inlet opening of the journal section, and an end portion of the oil groove in the circumferential direction does not extend to an end surface of the one semi-cylindrical bearing in the circumferential direction and therefore the inner circumferential surface extends between the end portion of the oil groove in the circumferential direction and the end surface of the one semi-cylindrical bearing in the circumferential direction to form a separation inner circumferential surface therebetween,
• the end surface of the one semi-cylindrical bearing in the circumferential direction to which the oil groove does not extend, and an end surface of the other semi-cylindrical bearing in the circumferential direction which is joined to the end surface of the one semi-cylindrical bearing each comprise inclined surfaces on an inner circumferential surface side that extend throughout an entire length in the axial direction, so that an axial direction groove is formed at a joint portion of the pair of semi-cylindrical bearings, and the separation inner circumferential surface extends between the axial direction groove and the oil groove, and
• a length L1 of the separation inner circumferential surface in the circumferential direction is smaller than a length L2 of the inlet opening of the journal section in the circumferential direction, so that the oil groove is communicable with the axial direction groove via the inlet opening of the lubricating oil path.