Compact magnetic fluid low pressure seal.

摘要

A bearing and magnetic fluid seal assembly includes a shaft mounted by axially spaced-apart bearings (52-54) for rotation relative to a housing (50). A magnetic fluid seal includes an annular magnet (60) axially positioned between the bearings (52-54) in the space (58) that is wasted and not utilized for any purpose, and a thin, disk-like annular polepiece (162) positioned between one of the bearings (52-54) and the environment to be protected by the seal. Magnetic flux from the magnet (60) is conducted by a magnetically permeable housing (50) or shaft (42) to an annular gap between the outside diameter of the polepiece (162) and the housing (50). A magnetic fluid (164) is retained in the gap by the magnetic flux, thereby providing an exclusion seal. Embodiments utilizing radially and axially polarized magnets are provided. A magnetic fluid seal can be provided at each end of the assembly. The bearings (52-54) supporting the shaft (42) can be magnetically permeable or nonmagnetic. The seal(s) can be electrically conducting or nonconducting depending upon the type of ferrofluid (164) used.