| 摘要 |
PURPOSE:To prevent a shaft from coming into contact with a bearing in a low-speed rotation range by supplying pressure air to a bearing clearance from an accumulator, and controlling the supply of pressure air according to an operating condition. CONSTITUTION:A lot of oblique grooves 3 and crests 4 are disposed on right and left at a bearing portion 2 on the outer periphery of a shaft 1. A bearing 7 formed by a porous material and held by a case 8 is provided in such a manner as to confront with the bearing portion 2. Holes 17 of the bearing 7 form a let of passages, which are connected to an introduction port 9 of the case 8 by an outer peripheral groove 5, and the inner periphery thereof is connected to a bearing clearance 6. An accumulator 10 is adapted to store pressure air, and the pressure air is supplied to the bearing clearance 6 according to an operating condition by a control device 19. In this arrangement, a bearing portion 2 comprising the groove 3 and crests 4 and the bearing 7 form a dynamic pressure air bearing, and the bearing portion 2, the bearing 7, the passages 17 and the accumulator 10 form a static pressure air bearing, both of which are hydridized.
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