Patent ID: 6845681

Claim:
A starter motor for cranking an internal combustion engine, the starter motor comprising: a housing containing an electric motor therein, the housing including a front end wall; a rolling bearing having an outer ring fixedly supported in a cylindrical space formed at a front side of the housing; a pinion shaft rotatably supported by the rolling bearing; and a seal member for sealing a front end of the housing, the seal member being disposed in an annular space formed between the front end wall and the cylindrical space, a diameter of the annular space being smaller than that of the cylindrical space, wherein: the seal member is solely made of rubber in a form of a cup having an outer wall, a bottom wall and a sealing lip, the outer wall of the seal member is press-fitted in the annular space and tightly held between the front end wall of the housing and the outer ring of the rolling bearing without interposing anything therebetween, the sealing lip slidably contacts the pinion shaft to seal the front end of the housing, the bottom wall has a depressed portion that faces the rolling bearing and enlarges a space between the rolling bearing and the bottom wall of the seal member, and lubricant is retained in the enlarged space, and the bottom wall of the seal member has an S-shaped cross-section so that the sealing lip flexibly contacts the pinion shaft.