Patent ID: 7905019

Claim:
A working fluid injection apparatus for a fluid dynamic pressure bearing, the apparatus being used for injecting a working fluid into a gap between a housing and a shaft in a bearing unit of the fluid dynamic pressure bearing with the housing having an opening portion, the shaft being held in the housing with an end of the shaft exposed from the opening portion, and the gap forming a ring-shaped open portion in the opening portion of the housing, the working fluid injection apparatus comprising: an adapter configured to support the bearing unit in a state in which the ring-shaped open portion of the bearing unit housing opens upwards; a cover member having an upper opening, a lower opening larger than the ring-shaped open portion of the bearing unit housing, and a tapered inner surface with a radial dimension that increases gradually from the lower opening to the upper opening, the cover member being configured to be mounted in contact with an upper surface of the bearing unit housing when the bearing unit is supported by the adapter so that the lower opening of the cover member surrounds the ring-shaped open portion of the bearing unit housing and so that an outer peripheral surface of the exposed end of the bearing unit shaft and the tapered inner surface of the cover member form a reservoir portion that communicates with the ring-shaped open portion of the bearing unit housing and that is configured to store a working fluid; a chamber that sealably holds the bearing unit onto which the cover member is mounted; a valve device that opens and closes an internal space of the chamber with respect to a surrounding external space thereof; an exhaust device that exhausts air from the internal space of the chamber to place the internal space of the chamber in a predetermined decompressed state; and a dispenser that dispenses a working fluid into the reservoir portion when the chamber sealably holds the bearing unit and the internal space of the chamber is in the predetermined decompressed state.