Patent ID: 9013829
Filing Date: 2015-04-21
Classification: F16C,G11B,H02K

Abstract:
1. A spindle motor comprising: a stationary portion; a rotating portion that is rotatable about a central axis extending in a vertical direction; and a lubricating fluid provided between the stationary portion and the rotating portion; wherein the stationary portion includes: the shaft portion includes: a radial distance between the upper outer circumferential surface and the central axis decreases with decreasing height; a radial distance between the lower outer circumferential surface and the central axis decreases with increasing height; the rotating portion includes: the sleeve includes: a radial distance between the upper inner circumferential surface and the central axis decreases with decreasing height; a radial distance between the lower inner circumferential surface and the central axis decreases with increasing height; the shaft portion, the sleeve, and the lubricating fluid together define a fluid dynamic bearing; the fluid dynamic bearing includes: both the upper bearing portion and the lower bearing portion are filled with the lubricating fluid; and a radial distance between a lower end portion of the upper dynamic pressure generating groove and the central axis is shorter than a radial distance between an upper end portion of the lower dynamic pressure generating groove and the central axis.