| 摘要 |
An apparatus and method are provided for sealing and electrically coupling an outer surface 170 of a shaft 175 to an inner surface 165 of a hub 160 disposed about the shaft. The invention is particularly useful for spindle motors 155 used in disc drives 100. In one embodiment, a seal 185 having a pair of annular pole pieces 270a, 270b, coupled to opposite poles of a magnet 265 is positioned between the shaft 175 and the hub 160. A nonmagnetic, electrically conductive ring 275 electrically couples the pole pieces 270a, 270b to one another and to the hub 160. In one version, the electrically conductive ring 275 includes an annular disk 300 with tabs 305 projecting from the exterior radius. The disk 300 abuts one pole piece 270b and the tabs 305 are folded over to electrically couple to the other 270a. An electrically conductive ferrofluid 280 is magnetically held between the pole pieces 270a, 270b, and the shaft 175 to form a pair of axially separated seals 290a, 290b, and to establish parallel electrical pathways.
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