| 摘要 |
PURPOSE:To improve the stabilizing accuracy of rotation in a rotating mechanism by inserting a stationary supporting shaft into a hollow part passed axially through a rotational shaft and utilizing the gas pressure of gas flowing axially at the air gap between the outer periphery of the shaft and the inner wall of the hollow part of the shaft as a bearing. CONSTITUTION:A rotational shaft 20, to which a permanent magnet 2 is fixed, is provided in a casing 1 which fixedly contains a core 11 and a coil 12 therein, and a stationary supporting shaft 30 formed with a flange 31 at the lower end is inserted via a slight air gap into the hollow part 15 passed axially through the shaft 20. Dynamic pressure generating means which is made of a groove for generating pressure gradient of air upon rotating operation is, for example, formed at the end 20a at the lower part of the shaft 20, the upper end 20b is opposed in the vicinity to the plane seat 4 fixed to the shaft 30 and operated as a thrust bearing, and many spiral grooves are formed as dynamic pressure generating auxiliary means on the inner wall of the hollow part of the shaft 20. An air suction hole 38 is formed at the seat 13 formed at the lower part of the casing 1. |
