| 摘要 |
PURPOSE:To prevent the axial looseness of a bearing with a rotational shaft by coupling a boss for securing a rotor and the shaft through a key in such a manner that the rotor is axially slidable, thereby moderating an impact by the rotor to the bearing at the starting time. CONSTITUTION:A rotational shaft 29 is rotatably supported by a ball bearing 22 engaged with a stator 21, and coupled through a key 30 with a rotor 25. The key 30 is formed integrally substantially in a cross shape with the shaft 29 to transmit the rotation to a boss 26 in such a manner that the boss 26 may be axially rotatable. In case of starting, when the coil 24 of the stator 21 is energized, the rotor 25 braked by a brake surface 28 and a brake shoe (not shown) is attracted to a stator core 23 to be released from the brake, start rotating to rotate the shaft 29 through the key 30. An impact caused by the attracting force is applied by the inner surface 34 of the boss 26 to the top 35 of the key 30 against the tension of a spring 33. In this manner, the axial displacement between the ball bearing 22 and the shaft 29 can be prevented. |
