System and method to electrically ground fluid dynamic bearings
View Patent ↗A spindle motor assembly that utilizes a fluid dynamic bearing electrically grounded to provide a conductive path through the spindle motor assembly. In one embodiment, the fluid dynamic bearing includes a liquid metal that is conductive and of low electrical resistance that provides the conductive path between the spindle and the spindle housing.
1. A hard disk drive comprising:
a housing comprising grooved regions surrounding portions of a central shaft;
a disk pack coupled with the central shaft disposed within a fluid dynamic bearing, said disk pack defining an axis of rotation and a radial direction relative to said axis; and
an electrical grounding material coupled to the central shaft to provide a conductive path through the fluid dynamic bearing to the disk pack;
wherein the electrical grounding material comprises a liquid metal; and
wherein a thrust washer is swaged and glued or laser welded to the housing, and the liquid metal is trapped in a liquid state in a captive nest in the thrust washer.
2. The hard disk drive as recited in claim 1 , wherein the captive nest is adjacent a base of the central shaft interfacing with the thrust washer.
3. The hard disk drive as recited in claim 2 , wherein the fluid dynamic bearing comprises lubricating oil.
4. The hard disk drive as recited in claim 3 , wherein the grounding material further comprises a material dispersed within the lubricating oil to provide a conductive path to the central shaft and the housing.
5. The hard disk drive as recited in claim 1 , wherein the liquid metal is of electrically low resistance.
6. The hard disk drive as recited in claim 1 , wherein the liquid metal is Galinstan.
7. The hard disk drive as recited in claim 1 , wherein the liquid metal comprises Indium.
8. The hard disk drive as recited in claim 1 , wherein the liquid metal comprises Stannum.