Connecting rod bearing in internal combustion engine

A connecting rod bearing for an internal combustion engine being constituted such that lubricant oil, which has been supplied onto an inner surface of a connecting rod bearing for supporting a crankshaft, is supplied onto the inner surface of the connecting rod bearing, rotatably supporting a crankpin connecting a connecting rod to the crankshaft, from a lubricant oil outlet port at a surface of the crankpin through an oil passage in the crankshaft, the connecting rod bearing consisting of a pair of semi-cylindrical bearings one of which is an upper semi-cylindrical bearing which is disposed on a connecting rod side of a big end housing of the connecting rod, and the other one of which is a lower semi-cylindrical bearing which is disposed on a cap side of the big end housing of the connecting rod, each of the semi-cylindrical bearings having a circumferential center part and the upper semi-cylindrical bearing being assembled so that the circumferential center part of the upper semi-cylindrical bearing is in alignment with an axis of the connecting rod,

• wherein at least one of the semi-cylindrical bearings is provided with a circumferential groove on an inner surface of the at least one of the semi-cylindrical bearings, the circumferential groove extends from at least one of two abutting ends with respect to the other semi-cylindrical bearing toward the circumferential center part of the at least one of the semi-cylindrical bearings, and is in alignment with the lubricant oil outlet port, the at least one abutting end being oriented toward the same direction as a direction of relative rotation of the crankpin with respect to the connecting rod bearing, and
• wherein the circumferential groove has a depth of 0.1 to 0.8 mm;
• a circumferential length which is not less than a diameter of the lubricant oil outlet port, the diameter being measured in a circumferential direction of the at least one of semi-cylindrical bearings, and wherein the circumferential groove extends around the at least one of the semi-cylindrical bearings to a maximum angle of 45 degrees measured from the at least one abutting end as a start point, and which does not include a length of a groove region adjacent to a terminal end of the circumferential groove on a side of the circumferential center part of the at least one of the semi-cylindrical bearings;
• and a width of which is not less than one half of the diameter of the lubricant oil outlet port, the diameter being measured in an axial direction of the at least one of the semi-cylindrical bearings, and a maximum width being defined by widths of inner surface regions locating on both axial sides of the circumferential groove, each of the widths being 2 mm.