| 摘要 |
PURPOSE:To seal/up the inside of a spindle motor reliably and thereby to prevent impure air from leak outside by fitting a magnetic fluid seal and a filter member. CONSTITUTION:A magnetic fluid seal 10 so provided as to be interposed between a magnetic ring 25 and a spacer member 6 is fitted on the outside in the direction of the 29 of rotation of a lower-side ball bearing 8. On the outside in the direction of the axis 29 of rotation of an upper-side ball bearing 7, a filter member 9 is provided in such a manner that it is stuck on the top side of a stepped part 40 in the small-diameter part 22 of a hub member 1. By the magnetic fluid seal 10 and the filter member 9 provided in this way, impure air existing in an internal space 41 of a spindle motor can be prevented from leaking out into an external space 42 of the spindle motor. Since no air pressure difference occurs between the inside and the outside of the spindle motor, in addition, a burst or scattering of a magnetic fluid in the magnetic fluid seal does not occur even when the environment of the operation of the spindle motor changes. |
