Patent ID: 6703735
Filing Date: 2004-03-09
Classification: F16C,H02K

Abstract:
A magnetic bearing for producing an axially attractive force to support a rotating body, comprising:a rotor having an axially-facing surface supported for rotation about an axis of rotation; and a stator, axially separated from said rotor surface by an air gap, and magnetically supporting said rotor axially; said stator having an annular electromagnetic coil attached thereto, and an annular ferromagnetic body having two radially spaced-apart concentric ring poles spaced apart from said rotor surface and defining therewith two annular axial air gaps on a single axial side of said rotor, an annular ferromagnetic region axially aligned with said stator poles that cooperates magnetically with said stator to produce said attractive force of said bearing; a permanent magnet in said stator for producing a bias flux through firs and second bias flux paths; said first path including portions of both of said ring poles, both of said axial air gaps and said annular ferromagnetic region of said rotor, said second path including a shunt that is magnetically in parallel with said annular ferromagnetic region of said rotor and bypass said axial air gaps; said second path having a reluctance to said flux from said permanent magnet that is comparable with magnetic reluctance of said first path; said electromagnetic coil lies between said ring poles of said stator and has an axis that is oriented co-axially with said axis of rotation and, said coil having leads for connection to a source of electrical power and, when energized by said electrical power, provides a control flux through both air gaps and around said permanent magnet through said shunt.