Internal combustion engine

A journal of a crankshaft is rotatably supported by a journal-supporting portion of a cylinder block and a bearing cap. An arcuate oil guide groove is defined in a side face of the bearing cap, and coils which are portions of a stator of a generator or motor are fitted into an oil guide groove. Oil flowing down from an oil return passage provided in the cylinder block and oil flowing down from a blow-by gas passage, flow downwards from an upper end of the oil guide groove and return through an opening to an oil pan. In this process, the oil is brought into contact with the coils to cool the stator. Therefore, even if the stator is located above the oil stored in the oil pan, the stator having a raised temperature can be cooled efficiently, to thereby prevent degradation of the performance of the generator or motor.