Abstract: A lower link (6) is provided with an oil hole (30) in a crank pin bearing portion (11) in order to supply a jet of oil to a connecting portion between an upper pin (4) and an upper link (3). Oil hole (30) is composed of a first oil hole (31) linearly extending from the inner peripheral surface of crank pin bearing portion (11) outwardly in the radial direction, and a second oil hole (32) linearly extending from the outer surface of lower link (6) so as to intersect a distal end portion of first oil hole (31). An inclination angle (?) of first oil hole (31) with a divided surface (14) set as a reference becomes relatively small, and hence the position of an oil inlet (31b) involving a problem of stress concentration becomes closer to divided surface (14) exhibiting a relatively low stress. Consequently, the stress concentration at oil inlet (31b) is alleviated.

Abstract: A bearing cap (1) is attached to a bulkhead (22) of a cylinder block (21) made of a light metal through a pair of bolts (24). The bearing cap (1) has a frame (2) made of an iron-based metal and a cast light-alloy part (3). The frame (2) has a pair of pillar parts (9) through which the bolts (24) extend and a circular-arc-shaped arch section (10). At high temperatures, the span of the pair of the bolts (24) increases due to thermal expansion of the light-alloy material, and the pair of the pillar parts (9) expand. This causes the middle part of the arch section (10) to shift upward, thereby suppressing an increase in bearing clearance.

Abstract: A crankshaft of an in-line, four-cylinder internal combustion engine has five journal portions. The journal portions are each supported by a main bearing unit. Each of the main bearing units includes a cylinder block side bearing part and a bearing cap. The No. 1, No. 2, No. 4 and No. 5 main bearing units employ an iron-based bearing cap, and the No. 3 main bearing unit at the center employs a bearing cap made of an aluminum alloy having a relatively high thermal expansion coefficient. At high temperatures, the bearing clearance of the No. 3 main bearing unit is configured to expand so as to reduce bearing load.

Abstract: A bearing cap (1) is attached to a bulkhead (22) of a cylinder block (21) made of a light metal through a pair of bolts (24). The bearing cap (1) has a frame (2) made of an iron-based metal and a cast light-alloy part (3). The frame (2) has a pair of pillar parts (9) through which the bolts (24) extend and a circular-arc-shaped arch section (10). At high temperatures, the span of the pair of the bolts (24) increases due to thermal expansion of the light-alloy material, and the pair of the pillar parts (9) expand. This causes the middle part of the arch section (10) to shift upward, thereby suppressing an increase in bearing clearance.

Abstract: A crankshaft of an in-line, four-cylinder internal combustion engine has five journal portions. The journal portions are each supported by a main bearing unit. Each of the main bearing units includes a cylinder block side bearing part and a bearing cap. The No. 1, No. 2, No. 4 and No. 5 main bearing units employ an iron-based bearing cap, and the No. 3 main bearing unit at the center employs a bearing cap made of an aluminum alloy having a relatively high thermal expansion coefficient. At high temperatures, the bearing clearance of the No. 3 main bearing unit is configured to expand so as to reduce bearing load.