On-site fillable ferrofluidic seal

摘要

An on-site fillable ferrofluidic seal comprises a ferrofluidic seal having at least one ferrofluid conducting channel extending through either the magnet, through one of the pole pieces which sandwich the opposing pole ends of the magnet, or through both the magnet and a pole piece. The conducting channel extends to a location where deposited ferrofluid will be drawn to the gaps between the pole pieces and the shaft. In another embodiment a multi-stage seal is filled by displacing the pole piece/magnet assembly axially relative to the shaft so that each pole piece projection falls halfway axially between two shaft projections. The displacement alters the normal magnetic field pattern to create a substantially uniform magnetic field throughout the pole piece/shaft interface region such that ferrofluid can be drawn through the region. When the shaft is returned to its original position with respect to the pole piece/magnet assembly, that is, when the pole piece projections are re-aligned axially with the shaft projections, a series of stages of the multi-stage hermetic "O-ring" seal are created.