Importance

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Abstract

A long-life, stacked pole-piece magnetic fluid seal for sealing between a housing and magnetically permeable shaft, in one embodiment is comprised of an annular magnet, having poles of opposite polarity on first and second end surfaces thereof, an annular, magnetically permeable primary pole-piece axially abutting the first end surface of the magnet, and one or more annular, magnetically permeable secondary pole-pieces stacked axially adjacent the primary pole-piece and separated therefrom and from each other by one or more annular spacers which define intermediate spaces between the pole-pieces. The pole-pieces are in a closely-spaced, non-contacting relationship with the shaft to define one or more radial gaps which, in conjunction with the intermediate spaces collectively form an annular ring in which a magnetic fluid is disposed and retained. In a second embodiment, the annular magnet is separated from the primary pole piece by a spacer which defines an intermediate space therebetween. The magnet and primary pole-piece are in closely-spaced, non-contacting relationships with the shaft to define first and second gaps respectively, which, in conjunction with the intermediate space, collectively form an annular ring in which a magnetic fluid is disposed and retained.

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First Claim