| 摘要 |
A ball bearing (18) that carries a rotor side portion of a rotor shaft (16) includes an inner race (23), an outer race (24), and a plurality of balls (25). The inner race has an enlarged end face (S1) which supports a supporting part (22) of a rotor (13). The enlarged end face has a diameter (D1) which is at least as large as a reference diameter (D3) minus 34% of a diameter of the balls (25). The flexural strength of the rotor shaft is increased at the location of the ball bearing (18). The natural bending frequency also increases and is caused to be above an operating frequency of the rotor shaft. Resonances are also avoided. |
