Fluid dynamic bearing with an immiscible fluid barrier
View Patent ↗A fluid dynamic bearing with an immiscible fluid barrier deposited on the bearing oil is disclosed. One embodiment provides the fluid dynamic bearing having a seal gap to define a seal cavity. The seal cavity is filled with the bearing oil for lubricating the fluid dynamic bearing. The immiscible fluid is disposed on the bearing oil to prevent the bearing oil from evaporating from the seal cavity. In one embodiment, the immiscible fluid is insoluble in the bearing oil.
1. A hard disk drive, comprising:
an enclosure; and
a disk rotatably mounted to the enclosure and having magnetic media;
an actuator pivotally mounted to the enclosure and having a transducer for reading data from the magnetic media;
a fluid dynamic bearing that is lubricated with bearing oil and a seal for retaining the oil, the seal having a seal gap; and
a barrier comprising a bearing-oil-immiscible fluid disposed as a homogeneous layer only comprising said bearing-oil-immiscible fluid on top of the bearing oil for preventing the bearing oil from leaking through the seal gap, such that only said bearing-oil-immiscible fluid of said barrier is in contact with said seal gap.
2. The hard disk drive of claim 1 , wherein the bearing-oil-immiscible fluid has lower vapor pressure than the bearing oil.
3. The hard disk drive of claim 1 , wherein the bearing oil is an ester oil.
4. The hard disk drive of claim 1 , wherein the bearing-oil-immiscible fluid is a perfluoropolyether.
5. The hard disk drive of claim 1 , wherein the bearing-oil-immiscible fluid is a polyaromatic.
6. The hard disk drive of claim 5 , wherein the polyaromatic is Santovac 5.
7. The hard disk drive of claim 1 , wherein the bearing-oil-immiscible fluid is polyphenylene oxide.
8. The hard disk drive of claim 1 , wherein the bearing-oil-immiscible fluid is in a range of approximately 50 nm to 500 microns thick.
9. The hard disk drive of claim 1 , wherein the bearing-oil-immiscible fluid has a higher viscosity than the bearing oil.
10. The hard disk drive of claim 1 , wherein the bearing-oil-immiscible fluid is insoluble in the bearing oil.
11. A data storage device, comprising:
a housing;
at least one disk mounted to the housing and rotatable relative to the housing;
an actuator mounted to the housing and being movable relative to the disk, the actuator having a suspension for reaching over the disk, the suspension having a slider coupled therewith, the slider having a read/write head element on a trailing edge (TE) portion of the slider;
a fluid dynamic bearing having bearing oil; and
a seal cap adjacent to a shaft of the fluid dynamic bearing, the seal cap having an outside end proximal such that an air-gap is provided between the outside end of the cap to define a bearing cavity; and
a barrier comprising a bearing-oil-immiscible fluid disposed as a homogeneous layer only comprising said bearing-oil-immiscible fluid on top of the bearing oil to prohibit the bearing oil from evaporating from the bearing cavity, such that only said bearing-oil-immiscible fluid of said barrier is in contact with said seal gap.
12. The data storage device of claim 11 , wherein the bearing-oil-immiscible fluid is coated on an oil air interface in the bearing cavity.
13. The data storage device of claim 11 , wherein the bearing-oil-immiscible fluid is a low vapor pressure liquid.
14. The data storage device of claim 11 , wherein the air-gap is a horizontal opening between the outside end of the cap and a rotor.
15. The data storage device of claim 11 , wherein the bearing-oil-immiscible fluid is a perfluoropolyether.
16. The data storage device of claim 11 , wherein the bearing oil is an ester oil.
17. The data storage device of claim 11 , wherein the bearing-oil-immiscible fluid is a polyaromatic.
18. A fluid dynamic bearing, comprising:
a seal gap to a fluid dynamic bearing, the seal gap for preventing oil leakage in the fluid dynamic bearing;
bearing oil for lubricating a drive hub in the fluid dynamic bearing; and
a barrier comprising a bearing-oil-immiscible fluid disposed as a homogeneous layer only comprising said bearing-oil-immiscible fluid on top of the bearing oil for prohibiting evaporation of the bearing oil through the seal gap, such that only said bearing-oil-immiscible fluid of said barrier is in contact with said seal gap.
19. The fluid dynamic bearing of claim 18 , wherein the bearing oil is ester oil.
20. The fluid dynamic bearing of claim 18 , wherein the bearing-oil-immiscible fluid is insoluble in the bearing oil.
21. The fluid dynamic bearing of claim 18 , wherein the bearing-oil-immiscible fluid is polyphenylene oxide.
22. The fluid dynamic bearing of claim 18 , wherein the bearing-oil-immiscible fluid is a non-functional perfluoropolyether.
23. The fluid dynamic bearing of claim 18 , wherein the bearing-oil-immiscible fluid is approximately 50 nm to 500 microns thick.
24. The fluid dynamic bearing of claim 18 , wherein the bearing-oil-immiscible fluid is a high viscosity fluid.
25. The fluid dynamic bearing of claim 18 , wherein a viscosity of the bearing-oil-immiscible fluid is higher than that of the bearing oil.