Thrust magnetic bearing for bias compensation

Abstract

The present invention relates to a thrust magnetic bearing for bias compensation, and more particularly, to a thrust magnetic bearing for bias compensation in which annular permanent magnets and electromagnets are disposed to face each other with respect to a levitated member and the permanent magnets are formed to be asymmetrical in lengths thereof in an axial direction to thus exert an attractive force for compensating for a bias by the difference in the lengths of the permanent magnets in the axial direction to compensate for the bias, and a current supply for bias magnetic flux is not required, saving energy.

Claims

1. A thrust magnetic bearing in which a rotor is supported by enabling a plate-like levitated member protruding in a direction perpendicular to a rotational shaft to float by means of the rotational shaft, the rotor including the rotational shaft, and an annular magnet unit surrounding the rotational shaft, wherein the magnet unit comprises: a first magnet unit having a first annular electromagnet provided on an upper surface and spaced apart from the levitated member by a predetermined distance and a first annular permanent magnet provided on one side of the first electromagnet; and a second magnet unit having a second annular electromagnet provided in a position facing the first electromagnet on a lower surface with respect to the levitated member and a second annular permanent magnet provided in a position facing the first permanent magnet, wherein a direction of magnetization of the first annular permanent magnet and second annular permanent magnet is parallel to a longitudinal direction of the rotational shaft, wherein a portion of the first permanent magnet, which is facing the second permanent magnet, has a length D1 in an axial direction, the second permanent magnet has a length D2 in the axial direction, and the length D1 is greater than the length D2, wherein an outer circumferential surface of the first annular permanent magnet contacts an inner circumferential surface of the first annular electromagnet, wherein an outer circumferential surface of the second annular permanent magnet contacts an inner circumferential surface of the second annular electromagnet, and an inner circumferential surface of the first annular permanent magnet directly faces the rotational shaft.

2. The thrust magnetic bearing of claim 1, wherein the magnet unit is formed of at least one material selected from among carbon, a resin, a metal, a porous metal, and a metal mesh.

3. The thrust magnetic bearing of claim 1, further comprising a space measurement sensor provided on one side of the magnet unit and configured to measure spaces between the levitated member, provided in a space between the first magnet unit and the second magnet unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a view illustrating a related art electromagnet thrust magnetic bearing.

(2) FIG. 2 is a view illustrating a related art electromagnet thrust magnetic bearing including permanent magnets.

(3) FIG. 3 is a view illustrating a related art rotor in which a permanent magnet cannot be provided in an upper portion thereof.

(4) FIG. 4 is a view illustrating a thrust magnetic bearing for bias compensation according to an exemplary embodiment of the present invention.

(5) FIG. 5 is a view illustrating an example of the thrust magnetic bearing for bias compensation according to an exemplary embodiment of the present invention.

DESCRIPTION OF SYMBOLS

(6) 1000: thrust magnetic bearing for bias compensation

(7) 100: magnet unit

(8) 110: first magnet unit

(9) 120: second magnet unit

(10) 11: electromagnet

(11) 11-1: first electromagnet

(12) 11-2: second electromagnet

(13) 12: permanent magnet

(14) 12-1: first permanent magnet

(15) 12-2: second permanent magnet

(16) D1: length of first permanent magnet in axial direction

(17) D2: length of second permanent magnet in axial direction

(18) 1: magnetic flux based on electromagnet

(19) 2: magnetic flux based on permanent magnet

(20) 200: rotor

(21) 210: rotational shaft

(22) 220: levitated member

DETAILED DESCRIPTION OF THE EMBODIMENTS

(23) Hereinafter, a thrust magnetic bearing for bias compensation according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

(24) Terms or words used in the specification and claims should not be limited and construed as common or dictionary meanings, and should be construed as meanings and concepts according to the technical spirit of the present invention based on the principle that the inventor can appropriately define the concept of each term for describing the invention in the best way.

(25) The exemplary embodiment described in the present disclosure and the configuration illustrated in the drawings are merely the most preferred embodiment of the present invention, rather than representing all the technical concepts of the present invention, so the present invention is meant to cover all modifications, similarities, and alternatives which are included in the spirit and scope of the present invention at the time of filing of the present invention.

(26) FIG. 1 is a view illustrating a related art electromagnet thrust magnetic bearing, FIG. 2 is a view illustrating a related art electromagnet thrust magnetic bearing including permanent magnets, FIG. 3 is a view illustrating a related art rotor in which a permanent magnet cannot be provided in an upper portion thereof, FIG. 4 is a view illustrating a thrust magnetic bearing for bias compensation according to an exemplary embodiment of the present invention, and FIG. 5 is a view illustrating an example of the thrust magnetic bearing for bias compensation according to an exemplary embodiment of the present invention.

(27) In a thrust magnetic bearing 1000 for bias compensation according to an exemplary embodiment of the present invention, in a case in which a shaft is disposed in a longitudinal direction and permanent magnets 12 for compensating for the gravitational force of a rotor 200 supported by the magnetic bearing cannot be attached to an upper portion of the rotor 200, attractive force is generated by a difference in thicknesses between the permanent magnets 12 to thereby compensate for the gravitational force of the rotor 200.

(28) As illustrated in FIG. 4, in the thrust magnetic bearing 1000 for bias compensation according to an exemplary embodiment of the present invention, a plate-shaped levitated member 220 protruding in a direction perpendicular to a rotational shaft 210 floats by the rotational shaft 210, the rotor 200 including the rotational shaft 210, and an annular magnet unit 100 surrounding the rotational shaft 210 to support the rotor 200, and here, the magnet unit 100 may include a first magnet unit 110 and a second magnet unit 120.

(29) The first magnet unit 110 includes a first electromagnet 11-1, as an annular electromagnet 11, provided on one surface of the magnet unit 100 and spaced apart from the levitated member 220 by a predetermined distance, and a first permanent magnet 12-1, as an annular permanent magnet 12, provided on one side of the first electromagnet 11-1.

(30) The second magnet unit 120 is formed on the other surface of the magnet unit 100 with respect to the levitated member 220, and includes a second electromagnet 11-2, as an annular electromagnet 11, provided to face the first electromagnet 11-1, and a second permanent magnet 12-2, as an annular permanent magnet 12, provided in a position facing the first permanent magnet 12-1.

(31) An operation of the thrust magnetic bearing for bias compensation according to an exemplary embodiment of the present invention described above will now be described. When power is supplied, magnetic flux is generated in the first electromagnet 11-1 and the second electromagnet 11-2.

(32) The levitated member 220 is under force of magnetic flux 2 based on the permanent magnets generated by the first permanent 12-1 and the second permanent magnet 12-2 and magnetic flux 1 based on electromagnets generated by the first electromagnet 11-1 and the second electromagnet 11-2, and the levitated member 220 floats in a space between the first magnet unit 110 and the second magnet unit 120 of the magnet unit 100 by virtue of the magnetic flux 2 based on the permanent magnets and the magnetic flux 1 based on the electromagnets.

(33) This is based on a magnetic levitation principle, and the thrust magnetic bearing 1000 for bias compensation according to an exemplary embodiment of the present invention supports the rotor 200 by using the magnetic levitation principle such that the levitated member 220 floats.

(34) Here, a position of the levitated member 220 floating between the first magnet unit 110 and the second magnet unit 120 of the magnet units 100 may be controlled by adjusting strength, direction, period, and the like, of power supplied to the first electromagnet 11-1 and the second electromagnet 11-2.

(35) That is, in the thrust magnetic bearing 1000 for bias compensation according to an exemplary embodiment of the present invention, the magnetic flux 2 based on the permanent magnets including the first permanent magnet 12-1 and the second permanent magnet 12-2 is used as bias magnetic flux, biased magnetism, and the magnetic flux 1 based on the electromagnets including the first electromagnet 11-1 and the second electromagnet 11-2 is formed as a position controlling magnetic flux 1 for controlling a position of the levitated member 220, whereby a current supply for bias magnetic flux is not required, enhancing economical efficiency and saving energy, and having a low temperature increase.

(36) Here, the first permanent magnet 12-1 has a thickness, namely, a length D1 in an axial direction, and the second permanent magnet 12-2 has a length D2 in the axial direction, and when the lengths D1 and D2 in the axial direction are asymmetrical, a bias acting on the rotor 200 may be compensated.

(37) In other words, in the thrust magnetic bearing 1000 for bias compensation according to an exemplary embodiment of the present invention, since the length D1 of the first permanent magnet 12-1 in the axial direction and the length D2 of the second permanent magnet 12-2 in the axial direction are formed to be asymmetrical, an amount of bias magnetic flux, i.e., the magnetic flux 2, based on the permanent magnets formed by the first permanent magnet 12-1 and the second permanent magnet 12-2, may be varied.

(38) This is to generate attractive force sufficient for compensating for a bias by a difference between the lengths D1 and D2 of the first permanent magnet 12-1 and the second permanent magnet 12-2 in the axial direction, and the bias acting on the rotor 200 may be compensated by the attractive force.

(39) FIG. 5 is a view illustrating an example for compensating for gravitational force as a bias acting on the rotor 200 supported by the magnetic bearing.

(40) The contents described above will be described in more detail. The exemplary embodiment illustrated in FIG. 5 is a device in which the rotor 200 is disposed in a longitudinal direction and supported by a magnetic bearing, but it is a device such as a turbo machine in which an impeller is attached to an upper portion or a centrifugal separator in which a bucket is attached to an upper portion thereof, so that the permanent magnet 12 for compensating for gravitational force cannot be disposed above the rotor 200.

(41) The rotor 200 above which the permanent magnet 12 for compensating for gravitational force as described above cannot be disposed is illustrated in FIG. 3, and as illustrated in FIG. 3, the permanent magnet 12 for compensating for gravitational force acting on the rotor 20 cannot be disposed above the rotor 200.

(42) Thus, in the thrust magnetic bearing 1000 for bias compensation according to an exemplary embodiment of the present invention, the length D1 of the first permanent magnet 12-1 formed in the upper portion with respect to the levitated member 220 is set to be greater than the length D2 of the second permanent magnet 12-2 formed in the lower portion with respect to the flowing member 200 to increase an amount of the magnetic flux 2 based on the permanent magnet formed by the first permanent magnet 12-1 to be more than an amount of the magnetic flux 2 based on the permanent magnet formed by the second permanent magnet 12-2, thus allowing an attractive force to act upwardly by bias magnetic flux formed by the difference in lengths D1 and D2 in the axial direction.

(43) In other words, the length D1 of the upper first permanent magnet is set to be greater than the length D2 of the lower second permanent magnet to allow an attractive force to act in the upward direction by the difference in the lengths of the permanent magnets in the axial direction to compensate for the gravitational force acting on the rotor 200.

(44) Thus, there is no need to continuously supply a current, which leads to a reduction in energy loss and prevents a significant temperature increase, compared with the related art bearing to which a current for compensating for gravitational force needs to be continuously supplied because the permanent magnet 12 for compensating for gravitational force cannot be disposed.

(45) In addition, the thrust magnetic bearing 1000 for bias compensation according to an exemplary embodiment of the present invention may further include a space measurement sensor (not shown) provided on one side of the magnet unit 100 to measure a space between the first magnet unit 110 and the second magnet unit 120 of the magnet unit 100 and the levitated member 200.

(46) That is, in the thrust magnetic bearing 1000 for bias compensation according to an exemplary embodiment of the present invention, since the space measurement sensor is provided on one side of the magnet unit 100, a space may be measured by the space measurement sensor to smoothly control an operation of the bearing and a position of the levitated member 220.

(47) Also, the thrust magnetic bearing 1000 for bias compensation according to an exemplary embodiment of the present invention is a magnetic bearing free from frictional contact with respect to the rotor, eliminating the necessity of a lubricant, and a housing in which the first electromagnet 11-1, the second electromagnet 11-2, the first permanent magnet 12-1, and the second permanent magnet 12-2 of the magnet unit 100 are provided is formed of a metal such as carbon, a resin, a metal, a porous metal, or a metal mesh.

(48) The housing of the magnet unit 100 including the first permanent magnet 12-1 and the second permanent magnet 12-2 having different lengths in the axial direction may be easily manufactured with the foregoing material and a position in which the foregoing space measurement sensor is to be provided on the magnet unit 100 may be freely selected, increasing a degree of freedom of design.

(49) While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.