| 摘要 |
PROBLEM TO BE SOLVED: To provide a level control means without requiring expensive replacement parts such as bellows or the like, in a fluid injection apparatus of fluid dynamic pressure bearings using a vacuum injection method and having the liquid level control means. SOLUTION: The fluid injection apparatus of this invention comprises: a bearing holding base 203 having an O-ring on which fluid dynamic pressure bearings (201, 202) seat; a bearing fixing means 211; a vacuum pump 216 for reducing the pressure in the fluid dynamic bearings; a reservoir 206 for storing lubricating fluid 207; a fluid injection tube 204 for injecting the lubricating fluid 207; and the level control means for controlling the level of the lubricating fluid to be a first level spaced from the tip of the fluid injection tube 204 at the time of reducing the pressure in the fluid dynamic pressure bearings, and to be a second level at which the tip of the fluid injection tube sinks in the liquid at the time of injecting the lubricating fluid. Further, the level control means is constituted by an inner circumferential face of the reservoir 206 as a cylinder, a piston 208 fitted in the inner circumferential face thereof, and a hydraulic or pneumatic cylinder 210 for driving the piston.
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