Disk drive system with hydrodynamic bearing lubricant having charge-control additive comprising dioctyldiphenylamine and/or oligomer thereof
View Patent ↗An improved disk drive system that employs a lubricant with improved charge control is provided. The disk drive system is comprised of a rotatably mounted magnetic disk. A rotor is coupled to the disk and rotatably retained by a stator. A bearing is formed that serves as an interface between the stator and the rotor. A motor coupled to the rotor rotates the magnetic disk via the rotor. Located in the bearing is a lubricant having a low relative electrical permittivity.
1. A disk drive system comprising:
a rotatably mounted magnetic disk;
a rotor coupled to the magnetic disk;
a stator for rotatably retaining the rotor;
a bearing that serves as an interface between the stator and the rotor, wherein the bearing is selected from a journal bearing, a thrust bearing, a spiral groove bearing, a herringbone groove bearing, or wherein the bearing is formed from surfaces that are embossed with grooves to create an internal pressure within a lubricant;
a motor coupled to the rotor for rotating the magnetic disk via the rotor; and
the lubricant disposed in the bearing, wherein the lubricant is comprised of a lubricating medium and a charge-control additive for reducing charge accumulation in the bearing, and wherein the charge-control additive is comprised of dioctyldiphenylamine, an oligomer comprising dioctyldiphenylamine, or a combination of the foregoing.
2. The disk drive system of claim 1 , comprising a plurality of rotatably mounted and spaced-apart magnetic disks mounted on the rotor, such that the motor rotates the magnetic disks via the rotor.
3. The disk drive system of claim 1 , wherein the motor is constructed to rotate the rotor at a rate greater than 3,500 revolutions per minute.
4. The disk drive system of claim 1 , wherein the bearing is a journal bearing.
5. The disk drive system of claim 1 , wherein the bearing is a thrust bearing.
6. The disk drive system of claim 1 , wherein the bearing is a spiral groove bearing.
7. The disk drive system of claim 1 , wherein the bearing is a herringbone groove bearing.
8. The disk drive system of claim 1 , wherein the bearing is formed from surfaces that are embossed with grooves to create an internal pressure within the lubricant.
9. The disk drive system of claim 1 , wherein the lubricating medium is comprised of an oil.
10. The disk drive system of claim 1 , wherein the charge-control additive is solubilized or dissolved in the lubricating medium.
11. The disk drive system of claim 1 , wherein the charge-control additive further comprises phenylnaphthylamine, an oligomer thereof, or a combination of the forgoing.
12. The disk drive system of claim 1 , wherein the charge-control additive is comprised of an oligomer of phenylnaphthylamine and dioctyldiphenylamine.
13. The disk drive system of claim 1 , wherein the lubricant is further comprised of a conductivity-enhancing additive for enhancing the electrical conductivity of the lubricant.
14. The disk drive system of claim 13 , wherein the conductivity-enhancing additive is solubilized or dissolved in the lubricating medium.
15. The disk drive system of claim 13 , wherein the conductivity-enhancing additive is comprised of an aniline, an oligomer thereof, a polymer thereof, or a combination of the forgoing.