US Patent 7597079 Starting device of engine

In a starting device of an engine, a starter clutch is provided with an outer race that rotates with a rotor (starter member), and a cam interposed between the outer race and a starter gear. A through hole is formed in the rotor so as to face the outer race axially. A stepped section is provided between a radially outer portion of the outer race, the portion facing a radially outer edge of the through hole, and a radially inner portion of the outer race. The stepped section causes the radially outer portion to be thinner than the radially inner portion. The starting device is capable of ensuring a cooling capability of a stator coil even though the rigidity of the outer race is increased.