Seagate Technology Incorporated

Tan Hung Pham

Donald James Macleod

Klaus Dieter Kloeppel

Robert Michael Pelstring

Jeffry Arnold LeBlanc

Marten Fredrick Byl

Michael James Whittome

Robert Alan Notingham

An apparatus and method are provided for sealing an outer surfaceof a shaftto an inner surfaceof a hubThe seal includes a magnetwith top and bottom pole piecesand a ferrofluidmagnetically held in a gapbetween the pole piecesand the hubor the shaftThe top pole piecehas a cross-section that is L-shaped, with a horizontal portionparallel to the magnetand a shorter vertical portionfacing the shaftIn one version, the vertical portionor the portion of the shaftfacing it is contoured to provide a flux gradient that axially concentrates the ferrofluidin the gapIn another aspect, a catcheris provided to reduce loss of ferrofluidwhen the ferrofluidic sealused to form an outside seal. In yet another aspect, a stationary ferrofluidic sealis provided for sealing a stationary shaftto a rotating hub

Apparatus and method for forming a rotatable ferrofluidic seal between a shaft and a hub

The tooth saturation level is improved and electromagnetic harmonics reduced by reducing the path cross-section of area in the tooth with a geometrical means such as punched holes through the stator laminations. The punched holes alter the magnetic flux pattern by forcing the flux to go around the holes, providing a greater concentration of the flux within regions of the teeth, as well as, depending on the position of the hole along the long axis of the tooth, redistributing the flux density in the air gap. This redistributed flux density will also reduce the harmonics to improve the electromechanical device electromagnetic performance.

Tooth saturation for reduced electromagnetic harmonics

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San Marcos, CA, United States of America

Tan Hung Pham