FLUID BEARING DEVICE

摘要

PROBLEM TO BE SOLVED: To prevent working fluid from leaking and increase supporting rigidity of a rotor by forming a fluid backflow preventing part continuously on the same level with a dynamic pressure generating part, so that fluid flowing in the dynamic pressure generating part does not flow backward. SOLUTION: The upper surface of a bearing main body 220 is formed with a first virtual concentric circle C larger than the inner diameter A and smaller than the outer diameter B, a second concentric circle D larger than the circle C and smaller than the outer diameter B, and the circle D is formed with many first dynamic pressure generating grooves 250. Backflow preventing dynamic pressure generating grooves 300 are formed inside the circle C corresponding to the grooves 250 contacted with the circle C. At rotation, fixed fluid flows in the bent parts 250a from both ends of the grooves 250, it is gradually accelerated as the lapse of a time, and the working fluid is apt to flow backward in the direction of centrifugal force from the grooves 250 by the inertia force and the centrifugal force of the fluid. The grooves 300 pump the working fluid only in the fixed direction from the inner diameter A to the outer diameter B, and send out the fluid to the end part side of the grooves 300 and the grooves 250. Hence rigidity loss due to fluid flowing backward from the grooves 250 can be minimized.