Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1986-11-21
1987-09-15
Wong, Peter S.
Electrical generator or motor structure
Dynamoelectric
Rotary
184 618, 310 905, 384133, 415175, 416174, H02K 5124, H01F 702, F16J 1540, F16C 3204
Patent
active
046942130
ABSTRACT:
A ferrofluid seal for a bearing application with a stationary shaft about which a hub rotates. The seal consists of a permanent magnet and one or more annular pole pieces which form a magnetic circuit with the bearing shaft. The magnetic circuit includes an annular gap between the shaft and the pole pieces in which the magnetic flux traps a magnetic fluid which bridges the gap to form a seal. The shaft is tapered in the gap area to form a wedge-shaped gap which accommodates changes in the magnetic fluid volume due to temperature variations while holding the fluid within the magnetic field to maintain the seal. The pole piece which forms the gap has a straight annular face located at a constant radial distance from the shaft axis. At high operating temperatures expansion of the magnetic fluid causes the fluid to fill the taper of the shaft, but, since the shaft is stationary, fluid spash is eliminated. The straight surface of the pole piece controls fluid splash caused by centrifugal force.
REFERENCES:
patent: 4565379 (1986-01-01), Ballhaus
patent: 4630943 (1986-12-01), Stahl et al.
Bloom Frank
Cheever Charles J.
Gowda Hanumaiah L.
Ferrofluidics Corporation
Rebsch D. L.
Wong Peter S.
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