Patent ID: 7138738

Claim:
Axial magnetic bearing apparatus comprising: a casing; a rotating shaft; a rotary disc made of a magnetic material which is fixedly attached to the rotating shaft, said rotary disc having a groove which extends in a radial direction of the disc such that an air layer having magneto resistance is provided in the groove, said groove only opening to an outer radial circumference of the rotary disk; a pair of electromagnetic stators which are fixed to the casing and located on opposite sides of said rotary disc, each of the stators having a coil slot; ring-like electromagnetic coils which generate magnetomotive force, said electromagnetic coils being respectively inserted into the coil slots, wherein on the basis of an output signal of a displacement sensor for measuring axial displacement of said rotating shaft, magnetic attraction force is made to act between said rotary disc and each of said electromagnetic stators so as to bear said rotating shaft in a target position distant from said electromagnetic stators and in non-contact therewith.