Patent ID: 6890104

Claim:
A dynamic pressure bearing apparatus comprising: a shaft member; a thrust plate having a larger diameter than the shaft member and being integrated with the shaft member; a bearing member surrounding the shaft member and the thrust plate from a radial direction and an axial direction respectively; and a radial dynamic pressure bearing portion and a thrust dynamic pressure bearing portion generating a dynamic pressure to a lubricating fluid filled in a bearing gap between the shaft member and the thrust plate, and the bearing member, the radial dynamic pressure bearing portion and the thrust dynamic pressure bearing portion being formed so as to be separated from each other, wherein one end side of the bearing gap in the axial direction is closed while the other end side is opened, a capillary seal portion on the opened side at the other end of the bearing gap, the capillary seal portion is formed in such a manner that an angle formed by opposed surfaces of the shaft member and the bearing member is large on a boundary with the bearing gap and continuously or discontinuously smaller as distanced from the boundary, the lubricating fluid is continuously filled in the entire bearing gap from the capillary seal portion so that a gas-liquid interface of the lubricating fluid is at a position where the angle is small in the capillary seal portion before the shaft member and the thrust plate relatively float, the apparatus includes fluid pressure applying means for giving the lubricating fluid an inward pressure application force directed from the opened side toward the closed side of the bearing gap, a quantity of the lubricating fluid to be filled is set to a quantity that the lubricating fluid fills the fluid pressure applying means even if the gas-liquid interface moves to the bearing gap side, which is generated when the shaft member and the thrust plate relatively float in the thrust direction.