| 摘要 |
A self-activating ferrofluid seal apparatus and method, which seal apparatus comprises a permanent-magnet ring and a pair of pole pieces which form a cavity therebetween, and which seal apparatus includes magnetically permeable, extending elements in the cavity to form a ferrofluid-retaining gap therebetween, the pole pieces forming a radial gap with the surface of the shaft to be sealed, the ferrofluid-retaining gap having a magnetic-field intensity sufficient to retain the ferrofluid therebetween and sufficiently larger in gap width than the radial gap, whereby, on insertion of the shaft element, the ferrofluid, based on the change in magnetic flux path, will move from the retaining gap to the radial gap to form a ferrofluid seal about the shaft element.
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