Patent ID: 8317402

Claim:
A connecting rod bearing for crankshafts of internal combustion engines for rotatably supporting a crankpin of a crankshaft having an internal lubricant-oil passage, the connecting rod bearing consisting of a pair of semi-cylindrical bearings, one of which is an upper semi-cylindrical bearing positioned on a connecting rod side of a big end housing of a connecting rod, and the other of which is a lower semi-cylindrical bearing positioned on a cap side of the big end housing of the connecting rod, wherein the upper and lower semi-cylindrical bearings are provided with a reduced wall thickness region as a crush relief on a bearing inner surface adjacent to each of circumferential ends of the upper and lower semi-cylindrical bearings, wherein the upper semi-cylindrical bearing is so assembled to the big end housing of the connecting rod that a circumferential center of the upper semi-cylindrical bearing is aligned with an axis of the connecting rod, and wherein a circumferential groove is formed on the bearing inner surface so as to extend from each of circumferential ends of the upper and lower semi-cylindrical bearings toward the circumferential center of the bearings within a maximum circumferential angle range of 45 degrees and to divide the reduced wall thickness region into two sections, a width center line of the circumferential groove being in alignment with an opening center of a lubricant-oil outlet port of the internal lubricant-oil passage in the crankpin, which lubricant-oil outlet port exists on an outer surface of the crankpin, wherein a corner edge of the respective circumferential end continuous to the bearing inner surface is chamfered to form a slant surface, thereby two axial grooves being in fluid communication with the four circumferential grooves are defined over an entire axial width of the upper and lower semi-cylindrical bearings along the circumferential ends abutting against each other in a state that the pair of semi-cylindrical bearings are combined with circularly, wherein a circumferential length of the circumferential groove is larger than a circumferential length of the reduced wall thickness region, wherein a depth of the circumferential groove is made gradually smaller from the circumferential end toward the circumferential center, wherein a width of the circumferential groove is not smaller than one-quarter of a diameter of the lubricant-oil outlet port of the internal lubricant-oil passage in the crankpin and less than the diameter of the lubricant-oil outlet port, and wherein cross-sectional areas of the circumferential groove and the axial groove at a connection portion thereof satisfy the following equation (1): cross-sectional area of the circumferential groove>cross-sectional area of the axial groove (1).