Ferrofluid seal apparatus

Details Ferrofluid seal apparatus Ferrofluid seal apparatus

1980-11-19

1982-07-20

Ward, Jr., Robert S.

Seal for a joint or juncture

Seal between relatively movable parts

Relatively rotatable radially extending sealing face member

277 80, 308 10, F16J 1540, F16J 1554

Patent

active

043402330

ABSTRACT:
A ferrofluid rotary-shaft seal apparatus of extended seal life particularly adapted for use as an exclusion seal with a computer-disc-drive spindle, which seal apparatus comprises: an annular permanent magnet; first and second pole pieces of unequal length at the one end, and which one end of each pole piece extends into a close, noncontacting relationship with the surface of the shaft, to form a small-gap width and a large-gap width between the one end of the pole piece and the surface of the shaft; and a ferrofluid in the small- and large-gap widths to form a ferrofluid O-ring seal at each gap width, whereby, during rotation of the shaft, the ferrofluid at the small-gap width evaporates and forms an air gap, while the ferrofluid at the large-gap width provides extended seal life.

REFERENCES:
patent: 4304411 (1981-12-01), Wilcock et al.

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