Dual seal for optimized performance
View Patent ↗A fluid dynamic bearing having a hub, a sleeve, and a sealing arrangement comprising a first capillary seal substantially retaining a first fluid and a second capillary seal comprising a second fluid. The second capillary seal is located between the first capillary seal and an opening between the hub and the sleeve.
1. A fluid dynamic bearing including a hub, a sleeve, and a sealing arrangement comprising:
a first capillary seal substantially retaining a first fluid; and
a second capillary seal comprising a second fluid and located between the first capillary seal and an opening at a protrusion between the hub and the sleeve.
2. The fluid dynamic bearing of claim 1 , wherein the first fluid is different than the second fluid.
3. The fluid dynamic bearing of claim 1 , wherein the first fluid comprises a lubricant.
4. The fluid dynamic bearing of claim 1 , wherein the second fluid has a lower evaporation rate than the first fluid.
5. The fluid dynamic bearing of claim 1 , wherein the second capillary seal acts as a plug to prevent evaporation of the first fluid.
6. The fluid dynamic bearing of claim 1 , further comprising an insert attached to a wall of the hub, the insert having a vent therethrough.
7. The fluid dynamic bearing of claim 1 , wherein the protrusion extends from the sleeve.
8. A spindle motor having a fluid dynamic bearing including a sealing arrangement, comprising:
a sleeve and a hub, wherein one of the sleeve and the hub rotate relative to the other;
a first fluid disposed between the hub and the sleeve;
a first capillary seal substantially retaining the first fluid; and
a second capillary seal comprising a second fluid and located between the first capillary seal and an opening between the hub and the sleeve, wherein the sleeve includes a protrusion and the second capillary seal is formed at the protrusion.
9. The spindle motor of claim 8 , wherein the spindle motor further comprises an insert attached to a wall of the hub, the insert having a vent therethrough.
10. The spindle motor of claim 8 , wherein an insert is attached to the hub and the second capillary seal is formed between the protrusion and the insert.
11. The spindle motor of claim 10 . wherein the second capillary seal has an inner surface and an outer surface, the insert comprising a vent providing substantially equivalent pressure on the inner and outer surfaces of the second capillary seal.
12. The spindle motor of claim 8 , wherein the first fluid is different than the second fluid.
13. The spindle motor of claim 8 , wherein the first fluid comprises a lubricant.
14. The spindle motor of claim 8 , wherein the second fluid has a lower evaporation rate than the first fluid.
15. The spindle motor of claim 8 wherein the second capillary seal acts as a plug to prevent evaporation of the first fluid.
16. A method for sealing a fluid dynamic bearing, the method comprising:
filling the fluid dynamic bearing with a first fluid retained by a first capillary seal; and
forming a second capillary seal at a protrusion between a hub and a sleeve, the second capillary seal being positioned between the first capillary seal and an opening in the fluid dynamic bearing, the second capillary seal comprising a second fluid.
17. The method of claim 16 , wherein the first fluid is different than the second fluid.
18. The method of claim 16 , wherein the first fluid comprises a lubricant.
19. The method of claim 16 , wherein the second fluid has a lower evaporation rate than the first fluid.
20. The method of claim 16 , wherein the second capillary seal acts as a plug to prevent evaporation of the first fluid.
21. The method of claim 16 , wherein the second capillary seal has an inner surface and an outer surface, the inner surface contacting the first capillary seal.
22. The method of claim 16 , wherein the protrusion extends from the sleeve.