Magnetic bearing apparatus

• US 5,530,306 A
• Filed: 04/14/1994
• Issued: 06/25/1996
• Est. Priority Date: 04/14/1993
• Status: Expired due to Term

• Current Assignee: Koyo Seiko Co., Ltd. (Toyota Motor Corporation)
• Original Assignee: Koyo Seiko Co., Ltd. (Toyota Motor Corporation)
• Inventors: Ueyama, Hirochika
• Primary Examiner(s): Stephan, Steven L.
• Assistant Examiner(s): ENAD, ELVIN GENARGUE
• Application Number:
  US08/227,462
• Time in Patent Office: 803 Days
• Field of Search: 310/90.5, 310/90, 361/146, 324/207.11
• US Class Current: 310/90.5
• CPC Class Codes: F16C 32/0444 Details of devices to control the actuation of the electromagnets

Abstract

In a magnetic bearing apparatus, a rotating member having an axis of rotation along the horizontal direction is supported by a pair of radial magnetic bearings each including a plurality of electromagnets in the radial direction with clearances with the rotating member in two portions in the axial direction. The apparatus comprises a pair of position detecting sensors for detecting the displacement in the radial direction of the rotating member in the two positions in the axial direction of the rotating member and a control device for controlling magnetic attraction forces produced by the electromagnets on the basis of output signals from the respective sensors. The control device calculates the magnetic attraction force produced by each of the radial magnetic bearings on the basis of the output signal from each of the sensors, a value of a control current supplied to the electromagnets in the radial magnetic bearing, and an attraction force coefficient of the electromagnets in the radial magnetic bearing, to calculate the position of the center of gravity of the rotating member on the basis of comparison of the operated magnetic attraction forces.

Claims

1. A magnetic bearing apparatus comprising:

first and second radial magnetic bearings each including a plurality of electromagnets for exerting magnetic attraction forces produced by said electromagnets on a rotating member having an axis of rotation along a horizontal direction in two positions spaced apart from each other in an axial direction of said rotating member and respectively supporting said rotating member in a radial direction with clearances with said rotating member;

first and second position detecting means for respectively detecting positions in the radial direction of said rotating member in the two positions in the axial direction of said rotating member; and

a control device for adjusting said magnetic attraction forces respectively produced by said electromagnets in said first and second radial magnetic bearings based upon output signals of said first and second position detecting means to hold said rotating member in a predetermined position in the radial direction,

said control device comprising;

magnetic attraction force calculating means for calculating said magnetic attraction force produced by each of said radial magnetic bearings based upon said output signal of each of said position detecting means, a value of a control current supplied to said electromagnets in said radial magnetic bearings, and an attraction force coefficient of said electromagnets in said radial magnetic bearings, and

center of gravity position calculating means for calculating a position of a center of gravity of said rotating member based upon comparison of said calculated magnetic attraction forces produced by both of said radial magnetic bearings, and

means or adjusting said magnetic attraction forces based upon output signals of said first and second position detecting means and said calculated position of said center of gravity of said rotating member.

2. The magnetic bearing apparatus according to claim 1, wherein:

said output signal of each of said first and second position detecting means is corrected by adding a correction signal so set that a result of the calculation performed by said magnetic attraction force calculating means becomes zero at an unloading time.

3. A magnetic bearing apparatus comprising:

first and second radial magnetic bearings each including a plurality of electromagnets for exerting magnetic attraction forces produced by said electromagnets on a rotating member having an axis of rotation along a horizontal direction in two positions spaced apart from each other along an axial direction of said rotating member and respectively supporting said rotating member in a radial direction with clearances with said rotating member;

first and second position detecting means for respectively detecting positions in the radial direction of said rotating member in the two positions in the axial direction of said rotating member;

magnetic attraction force calculating means for calculating said magnetic attraction force produced by each of said radial magnetic bearings based upon an output signal of each of said position detecting means, a value of a controlled current supplied to said electromagnets in said radial magnetic bearings, and an attraction force coefficient of said electromagnets in said radial magnetic bearings, and

center of gravity position calculating means for calculating a position of a center of gravity of said rotating member based upon comparison of the calculated magnetic attraction forces produced by both of said radial magnetic bearings;

displacement amount calculating means for calculating an amount of radial displacement of said calculated position of said center of gravity of said rotating member based upon said output signals of said first and second position detecting means;

tilt amount calculating means for calculating an amount of tilt around said calculated position of said center of gravity of said rotating member based upon said output signals of said first and second position detecting means;

translation motion control means for outputting such a translation motion control signal that said amount of radial displacement of said calculated position of the center of gravity of said rotating member becomes zero;

tilt motion control means for outputting such a tilt motion control signal that the amount of tilt around said calculated position of said center of gravity of said rotating member becomes zero; and

first and second electromagnetic driving means for respectively driving said electromagnets in said first and second radial magnetic bearings based upon outputs of said translation motion control means and said tilt motion control means.

4. Magnetic bearing apparatus according to claim 3, wherein:

said output signals of each of said first and second position detecting means are corrected by adding a correction signal so set that a result of the calculation executed by said magnetic attraction force calculating means becomes zero at an unloading time.