| 摘要 |
A motor unit has a stationary member, a rotatable member rotatable relative to the stationary member, a stator provided on the stationary member, a rotor provided on the rotatable member, and at least two bearings disposed between the stationary member and the rotatable member. The rotor and stator are constructed so that the rotor is electromagnetically attracted toward the stator during the energization of the motor. One of the bearings is a ball bearing having an outer race with preload applied by the electromagnetic attraction of the rotor and an inner race formed on the rotatable member, and the other bearing is a hydrodynamic pressure type radial bearing.
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