KR20130057331A

KR20130057331A - Magnet bearing system

Info

Publication number: KR20130057331A
Application number: KR1020110123184A
Authority: KR
Inventors: 이재형; 김희동
Original assignee: (주)대주기계
Priority date: 2011-11-23
Filing date: 2011-11-23
Publication date: 2013-05-31
Also published as: KR101291577B1

Abstract

PURPOSE: A magnetic bearing system for a movement at a constant velocity is provided to control vibration by providing high rigidity and to increase a rotating speed up to a rigid body mode of a rotary shaft itself. CONSTITUTION: A magnetic bearing system(10) for a movement at a constant velocity comprises a rotator(20), a motor(30), a main magnetic bearing unit(40), and a sub-magnetic bearing unit(100). The motor rotates the rotator. The main magnetic bearing unit is fixed along the circumferential direction of the rotator, thereby supporting the rotator rotated by the motor. The sub-magnetic bearing unit is fixed along the circumferential direction of the rotator, thereby improving rigidity for supporting the rotating rotator. The main magnetic bearing unit includes a main stator(42), a main coil unit(44), and a sensor member(46).

Description

Magnetic Bearing System {MAGNET BEARING SYSTEM}

The present invention relates to a magnetic bearing, and more particularly, to include a driver consisting only of passive elements that do not require a separate power source to improve the support rigidity of the rotating shaft in the existing magnetic bearing, and to provide additional displacement between the rotating shaft and the stator. A magnetic bearing system that can be measured.

Non-contact bearings, such as magnetic bearings, are being applied to overcome the limitations of contact bearings in machines requiring high rotational speeds, such as turbomolecular pumps.

In particular, active magnetic bearings (AMB) are widely used in many industrial machines because of their unique advantages such as non-contact characteristics, easy controllability of the actuator and non-lubrication characteristics.

Because of these advantages, active magnetic bearings are used as essential components in high-speed rotating equipment including turbomolecular pumps, high-speed machining centers, etc., and recently used in small devices such as portable hard disk drives, cardiovascular pumps and audio speakers. have.

This general active magnetic bearing consists of an actuator consisting of an electromagnetic coil, a displacement sensor, a power amplifier and a feedback controller.

Unlike passive bearings, active magnetic bearings achieve bearing forces by controlling electronic circuits. Here, the spring force and the damping force are important factors for determining the magnitude of the response and the first resonant frequency in the frequency response of the displacement to the external force of the bearing. The higher the spring force, the lower the magnitude response and the higher the first resonant frequency. The higher the damping force, the lower the resonance width can be obtained. That is, high stiffness is required to have a low magnitude response, a high resonance frequency, and a low resonance width, which are characteristics of an ideal bearing.

As for the magnetic bearing, a magnetic bearing device and a vacuum pump having the same have been proposed in Korean Patent Registration No. 10-0574079.

In the conventional mechanical bearings, high rigidity is ensured by increasing the resonance point of the magnetic bearing system by ensuring high rigidity.However, in the magnetic bearing, both the spring force and the damping force are in the form of electromagnets, especially power amplifiers that supply current to the electromagnets. As determined by the performance of, a high capacity power amplifier is used to achieve high stiffness. However, due to the limitations of power amplifier output, stiffness is lower than mechanical bearings, which can cause vibration problems for high frequency inputs. In addition, the use of high capacity power amplifiers has the effect of raising the price of the entire system and needs to be compensated for this. On the other hand, electromagnetic induction, which provides higher bearing capacity than the suction type electromagnet according to the existing magnetizing power, was not used well in magnetic bearings because the size varies depending on the frequency of the alternating magnetic field and the distance to the conductor. Control is required. Therefore, there is a high need for improvement.

The present invention has been made to solve the above problems, the rigidity of the existing magnetic bearings with a minimum cost by using a module integrated with a driver and a sensor made of only passive elements that can be implemented at a low price without the need of a separate power source It is an object of the present invention to provide a magnetic bearing system capable of increasing the speed and providing additional position information of a rotating shaft.

The magnetic bearing system according to the present invention includes: a rotating body, a motor for rotating the rotating body, a main magnetic bearing part fixed in the circumferential direction of the rotating body to support the rotating body rotating by the motor, and the rotation It includes a sub-magnetic bearing for improving the rigidity for the support of the rotating body fixed and rotated along the entire circumferential direction.

The main magnetic bearing part is formed in a ring shape for axially inserting the rotating body, the main stator is fixedly installed, the main stator is arranged to be spaced along the inner surface of the main stator to provide a driving force between the rotating body and the main stator. And a coil member and a sensor member provided on a circumferential surface of the rotating body to measure a distance from the surface of the rotating body to the main stator.

The sub-magnetic bearing part has a magnet member provided to be spaced apart by a set distance such that different polarities are adjacent to each other on the circumferential surface of the rotating body, and has a ring shape for axially inserting the rotating body and is fixed at a position consistent with the magnet member. And a sub stator to be installed, and a conductor provided on the inner side of the sub stator to generate a repulsive force against the magnet member.

Preferably, the main stator and the sub stator are disposed in a straight line with the main coil part and the conductor in the axial direction of the rotor.

The sub magnetic bearing part further includes a sub coil part provided inside the sub stator to be disposed between adjacent conductors to measure a distance between the rotor and the sub stator.

The sub-stator through the installation hole communicated to both sides in the circumferential surface, the conductor is screwed to the knob inserted into the installation hole is a distance from the rotating body is variable to maintain the support force for the rotating body, The knob preferably forms a clamping member at the end.

The rotating body is preferably determined by the interaction with the main magnetic bearing portion the initial position.

As described above, the magnetic bearing system according to the present invention has a higher rigidity in the existing magnetic bearings only by passive elements that do not require additional power in the magnetic bearings that support the rotating shaft in a non-contact manner for rotating machines, unlike the prior art. Vibration can be suppressed and the rotation speed can be increased up to the rigid mode of the rotating shaft itself.

In addition, the present invention can measure the displacement in the elastic vibration of the rotating shaft by the high speed rotation by providing an additional sensor configured in the form of a driver and a module, it is possible to more precise monitoring of the rotating shaft and at the same time more precise position and attitude control of the rotating shaft Can be enabled.

1 is a perspective view of a magnetic bearing system according to an embodiment of the present invention.
Figure 2 is an enlarged perspective view of the main portion showing the configuration of the sub-magnetic bearing portion of the magnetic bearing system according to an embodiment of the present invention.
3 is a cross-sectional view showing a state for improving the rigidity of the sub-magnetic bearing portion of the magnetic bearing system according to an embodiment of the present invention.
Figure 4 is a plan sectional view showing a displacement measurement state of the sub-magnetic bearing portion of the magnetic bearing system according to an embodiment of the present invention.
FIG. 5 is a perspective view illustrating a state in which a conductor position is changed in a sub magnetic bearing part of a magnetic bearing system according to an exemplary embodiment of the present invention. FIG.
6 is a view showing a magnetic field applied to a conductor by a magnet attached to the rotating body of the magnetic bearing system according to an embodiment of the present invention.
7 is a view showing the relationship between the frequency of the alternating magnetic field of the magnetic bearing system according to an embodiment of the present invention and the force according to the distance between the magnet member and the conductor.
8 is a view showing a voltage induced in the coil of the magnetic bearing system according to an embodiment of the present invention.
9 is a block diagram for converting an electrical signal generated from a coil of a magnetic bearing system according to an exemplary embodiment into displacement information.

Hereinafter, an embodiment of a magnetic bearing system according to the present invention will be described with reference to the accompanying drawings. In this process, the thicknesses of the lines and the sizes of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. In addition, the terms described below are defined in consideration of the functions of the present invention, which may vary depending on the intention or custom of the user, the operator. Therefore, definitions of these terms should be made based on the contents throughout this specification.

1 is a perspective view of a magnetic bearing system according to an embodiment of the present invention, Figure 2 is an enlarged perspective view of the main portion showing the configuration of the sub-magnetic bearing portion of the magnetic bearing system according to an embodiment of the present invention.

3 is a cross-sectional view showing a state for improving the rigidity of the sub-magnetic bearing portion of the magnetic bearing system according to an embodiment of the present invention, Figure 4 is a displacement of the sub-magnetic bearing portion of the magnetic bearing system according to an embodiment of the present invention This is a cross-sectional view showing the measurement state.

FIG. 5 is a perspective view illustrating a state in which a conductor position is changed in a sub magnetic bearing part of a magnetic bearing system according to an exemplary embodiment of the present invention. FIG.

6 is a view showing a magnetic field applied to a conductor by a magnet attached to a rotating body of a magnetic bearing system according to an embodiment of the present invention, Figure 7 is a magnetic field of the alternating magnetic field of the magnetic bearing system according to an embodiment of the present invention The relationship between the frequency and the force according to the distance between the magnet member and the conductor.

8 is a view showing a voltage induced in the coil of the magnetic bearing system according to an embodiment of the present invention, Figure 9 is to replace the electrical signal generated from the coil of the magnetic bearing system according to an embodiment of the present invention into displacement information It is a block diagram.

Referring to FIG. 1, a magnetic bearing system 10 according to an exemplary embodiment of the present invention includes a rotating body 20, a motor 30, a main magnetic bearing part 40, and a sub magnetic bearing part 100. .

In particular, the rotating body 20 is provided with a main magnetic bearing part 40 and a sub magnetic bearing part 100 on the circumferential surface, but the number of the sub magnetic bearing parts 100 is not limited.

At this time, the main magnetic bearing part 40 is provided at the upper side and the lower side of the rotating body 20, respectively.

Rotating body 20 is made of a cylindrical shape, made of a metal material to be affected by the electric and magnetic fields. The diameter and length of the rotating body 20 are not limited.

In addition, the motor 30 serves to forcibly rotate the rotor 20 in a non-contact state with the rotor 20. That is, when the motor 30 is operated, the rotating body 20 is rotated by receiving the rotational force. At this time, the method of rotating the rotor 20 by the motor 30 can be variously applied. For example, the motor 30 is provided to surround the circumferential surface of the rotating body 20.

On the other hand, the main magnetic bearing portion 40 is fixed along the circumferential direction of the rotating body 20 serves to support the rotating body 20 that is rotated by the motor (30).

In particular, the main magnetic bearing part 40 includes a main stator 42 and a main coil part 44.

The main stator 42 is formed in a ring shape in which the rotor 20 is axially inserted, and is fixed to an arbitrary fixture such as a motor 30 housing (not shown). The main stator 42 may be fixedly installed on any fixture in various ways. In addition, the main stator 42 may be any fixture itself. Of course, the main stator 42 may be modified in various shapes. The main stator 42 is made of a magnetic body.

In particular, a plurality of main coil parts 44 are provided along the inner surface of the main stator 42. For convenience, the main coil part 44 is shown to be provided with four at equal intervals on the inner surface of the main stator (42). At this time, the inner surface of the main stator 42 refers to the inner surface of the main stator 42 facing the circumferential surface of the rotating body 20.

The main coil part 44 may be provided in various ways on the inner surface of the main stator 42.

By way of example, the main coil portion 44 includes a main coil 45 and a main core 47. The main core 47 is provided on the inner surface of the main stator 42 to fix the position of the main coil 45, and the magnitude of the magnetic force of the main coil 45 is changed according to the material. The main coil 45 supports the rotating body 20 by forming a magnetic field by the supplied current. That is, the main coil part 44 is provided in plurality so as to be spaced apart at regular intervals along the inner surface of the main stator 42. In addition, as a bearing force by the magnetic field generated by each main coil 45, the central axis in the axial direction of the rotating body 20 is to be coincident with the central axis of the main stator 42.

In addition, the main magnetic bearing part 40 includes a sensor member 46. One or more sensor members 46 are provided on the circumferential surface of the rotating body 20 corresponding to the main coil part 44 to measure the displacement between the rotating body 20 and the main stator 42. Here, the displacement means the distance between the surface of the rotor 20 and the main stator 42 corresponding to the closest distance. Of course, the sensor member 46 is applicable to various types, it is fixed to the circumferential surface of the rotating body 20 by a variety of ways.

In addition, the sub-magnetic bearing part 100 is composed of only the passive element is fixed along the circumferential direction of the rotating body 20 serves to improve the rigidity for the support of the rotating body 20 to rotate.

That is, the sub magnetic bearing part 100 may improve the rigidity of the rotating body 20 with a simple structure by using only a passive element having high rigidity for suppressing vibration generated during the high speed rotation of the rotating body 20. Here, 'stiffness' refers to an action force to maintain a state in which the central axis of the rotating body 20 is rotated and the central axis of the main stator 42 is consistent, and the central axis of the whole and the central axis of the main stator 42. This misalignment means the force to return to the coincidence state.

In addition, the "passive element" means a component provided to maintain the rigidity of the rotating body 20 without any external force (driving force) applied to the rotating body 20 or the like.

For example, as shown in FIG. 2, the sub magnetic bearing part 100 includes a magnet member 110, a sub stator 120, and a conductor 130.

The magnet member 110 is provided on the circumferential surface of the rotating body 20 so as to be spaced apart by a predetermined distance such that the polarities are adjacent to each other. That is, the magnet member 110 is disposed on the circumferential surface of the rotating body 20 by alternating the 'N' pole and the 'S' pole. For convenience, the magnet member 110 is shown to be disposed at intervals of 90 degrees at the same height along the circumferential direction of the rotating body 20.

Of course, the magnet member 110 may be formed in various shapes, it is not limited to the number. In addition, the magnet member 110 may be attached to the circumferential surface of the rotating body 20 simply by magnetic force, or may be fixed to the rotating body 20 by various methods such as bolting.

In addition, the sub stator 120 is formed in a ring shape for inserting the rotor 20 into the shaft, and is fixedly installed at a position corresponding to the magnet member 110.

In other words, the sub stator 120 is formed in a ring shape in which the rotor 20 is axially inserted, and is fixed to an arbitrary fixture such as a motor 30 housing (not shown). The sub stator 120 may be fixedly installed to any fixture in various ways. In addition, the substator 120 may be any fixture itself. Of course, the sub stator 120 may be modified in various shapes. The sub stator 120 is made of a magnetic body.

In addition, the conductor 130 is provided on the inner surface of the sub-stator 120 so as to correspond to the magnet member 110 radially from the center of the rotating body 20 serves to generate a repulsive force against the magnet member 110. .

The conductor 130 has a number corresponding to the magnet member 110 one-to-one or different from the magnet member 110, and is disposed inside the sub stator 120. At this time, it is preferable that the magnet member 110 is provided in a larger number than the conductor 130. This is because the magnetic field can be quickly changed even if the amount of rotation of the rotating body 20 is small by narrowing the circumferential interval of the magnet member 110.

In particular, the conductor 130 is preferably made of copper or aluminum. In particular, when the sub stator 120 and the conductor 130 are heterogeneous, the conductor 130 is fixed to the inner surface of the sub stator 120 by various methods such as bolting. Of course, when the sub stator 120 and the conductor 130 are the same type, the sub stator 120 and the conductor 130 are preferably manufactured integrally.

As a result, the sub-magnetic bearing part 100 is attached to the rotating body 20 as a rotating element to generate a plurality of magnet members 110, and the sub-stator 120 and the rotating body (as a fixed element) It consists of a conductor 130 for generating a magnetic force by interaction with the magnet member 110 attached to 20.

Thus, the magnet members 110 attached to the rotating body 20 are alternately attached to each other along the circumferential direction of the rotating body 20.

When the rotating body 20 rotates under the driving force of the motor 30, an alternating magnetic field is applied to each of the conductors 130 (see FIG. 6).

In addition, a eddy current is generated in the conductor 130 attached to the sub stator 120 by the alternating magnetic field, and a force that repels each other is generated between the rotor 20 and the sub stator 120. At this time, the generated force is determined by the rotational speed of the rotor 20, the distance between the magnet member 110 and the conductor 130 (see Fig. 7).

Therefore, in order to provide stable supporting force to the rotating body 20, the distance between the rotating member and the magnet member 110 and the conductor 130 attached to the rotating body 20 must be kept constant.

In particular, the present invention is not intended to be used alone as the sub-magnetic bearing portion 100 as the purpose of improving the rigidity in addition to the existing main magnetic bearing portion 40 and for the purpose of simply realizing the structure. Since it is used together with the main magnetic bearing portion 40, the distance between the magnet member 110 and the conductor 130 is applied in a constant state.

At this time, the power for maintaining a constant rotational speed uses the existing motor 30 for rotating the rotor 20.

Meanwhile, the sub magnetic bearing part 100 further includes a sub coil part 140.

The subcoil unit 140 is provided inside the sub stator 120 to be disposed between neighboring conductors 130 to measure the distance between the rotor 20 and the sub stator 120. Thus, the sub-coil section 140 is composed of four that are uniformly spaced on the inner surface of the sub-stator 120.

In particular, the sub coil unit 140 serves to fix the position of the sub coil 142 and the sub coil 142 to measure the displacement of the rotating body 20 by the interaction with the magnet member 110. The coil 142 is made of a sub core 144 that varies in magnitude of the voltage induced according to the material.

In addition, the main stator 42 and the sub stator 120 are arranged to match the main coil part 44 and the sub coil part 140 along the axial direction of the rotating body 20. This is to improve rigidity so that the rotor 20 is positioned on the central axis of the main stator 42 and the central axis of the sub stator 120.

As shown in FIG. 4, when the rotating body 20 is rotated, and each of the magnet members 110 faces the corresponding conductor 130, the conductor 130 generates a eddy current, thereby causing the rotating body 20 to be rotated. And a force repulsing between the sub stator 120 is generated.

Therefore, in a state in which a separate power source is not required, due to the repulsive force generated between the corresponding conductor 130 and the magnet member 110, the rotation body 20 prevents the movement of the sub stator 120 from moving out of the center. The stiffness to be improved is improved.

In addition, as shown in FIG. 3, when the rotor 20 is rotated so that each of the magnet members 110 faces the corresponding subcoil 140, the direction perpendicular to the tangential direction of the surface of the rotor 20. The distance between the rotor 20 and the sub stator 120 may be measured. That is, whether the central axis of the rotating body 20 and the central axis of the sub-stator 120 coincide with each other can be accurately detected through the sensor member 46 and the subcoil part 140.

8 shows voltage values induced in each of the subcoils 142 by alternating magnetic fields. According to this voltage value electromagnetic induction principle, it is determined by the frequency of the alternating magnetic field, that is, the rotational speed of the rotor 20 and the distance between the corresponding magnet member 110 and the subcoil 142 attached to the rotor 20. . However, since the rotation speed of the rotating body 20 is kept constant by an external controller (not shown), it is determined by the distance between the magnet member 110 and the subcoil 142. Therefore, the distance between the rotor 20 and the sub stator 120 may be measured based on the voltage generated in the sub coil 142.

In addition, in a device that is not a rotating device that constantly changes the rotation speed, and maintains a constant speed step by step, the conductor 130 is moved in the radial direction of the rotating body 20 to obtain a constant bearing force at the step-by-step rotation speed It is preferred to be provided as possible. This is to change the distance between the corresponding magnet member 110 and the conductor 130 according to the change in the rotational speed of the rotor 20.

For example, as shown in FIG. 5, the sub stator 120 passes through a positive hole-shaped installation hole 210 communicating with both sides of the circumferential surface, and the conductor 130 is a knob 220 inserted into the corresponding installation hole 210. Screwed). In addition, the knob 220 is provided with a clamping member 230 at the end. Thus, the clamping member 230 varies the extent to which the knob 220 is screwed to the conductor 130 according to the rotation direction and the amount of rotation in contact with the circumferential surface of the sub stator 120. Accordingly, the distance between the conductor 130 and the rotating body 20 is passively changed, whereby the conductor 130 is controlled to maintain a bearing force for the rotating body 20 to be decelerated or accelerated.

In particular, the relationship between the rotational speed of the rotor 20 and the distance between the magnet member 110 and the conductor 130 for the rotor 20 to obtain a constant bearing force (stiffness) can be obtained through experiments and simulations. By using this relationship, when changing the position of the conductor 130 according to the rotational speed of the rotating body 20, it is possible to provide a constant bearing force even for a rotating device (not shown) of variable speed.

Of course, the knob 220 may be automatically adjusted to the degree of being inserted into the conductor 130 and fastened.

Therefore, the sub-coil 142 attached to the sub stator 120 and the sub-coil 142 and the sub through the magnitude of the voltage induced by the magnetic field alternated by the magnet member 110 attached to the rotating body 20, The spacing between the stators 120 is measured.

9 is an example of a circuit for converting an electrical signal generated from the subcoil 142 into displacement information. The bridge circuit 141 is used to measure a change in inductance of the subcoil 142 attached to the sub stator 120. After that, a signal amplifier 143 for amplifying the signal and a band pass filter 145 for measuring only the frequency components synchronized to the rotational speed are configured. Next, a rectifying circuit 147 for rectifying the AC signal to DC is configured, and a low pass filter 149 for removing the high frequency noise signal generated at this time is configured.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. I will understand. Therefore, the true technical protection scope of the present invention will be defined by the claims below.

10: bearing system 20: rotating body
30: motor 40: main magnetic bearing part
42: main stator 44: main coil part
45: main coil 47: main core
100: sub magnetic bearing part 110: magnet member
120: sub-stator 130: conductor
140: sub-coil part 142: sub-coil
144: subcore 210: mounting hole
220: knob 230: clamping member

Claims

A rotating body;
A motor for rotating the rotating body;
A main magnetic bearing part fixed along the circumferential direction of the rotor to support the rotor rotated by the motor; And
And a sub-magnetic bearing part for improving rigidity for supporting the rotating body which is fixed and rotated along the circumferential direction of the rotating body.

The method of claim 1, wherein the main magnetic bearing portion,
A main stator configured to have a ring shape for axially inserting the rotating body;
A main coil part disposed along the inner surface of the main stator so as to be spaced at a predetermined interval to provide a driving force between the rotor and the main stator; And
And a sensor member provided on a circumferential surface of the rotating body to measure a distance from the surface of the rotating body to the main stator.

The method of claim 2, wherein the sub-magnetic bearing part,
A magnet member provided on the circumferential surface of the rotating body so as to be spaced apart from each other by a predetermined distance so as to be adjacent to each other;
A sub-stator made of a ring shape for axially inserting the rotating body and fixedly installed at a position coinciding with the magnet member; And
And a conductor provided on an inner surface of the sub stator to generate a repulsive force against the magnet member.

The method of claim 3, wherein
And the main stator and the sub stator are disposed in a straight line with the main coil portion and the conductor in the axial direction of the rotating body.

The method of claim 3, wherein
The sub magnetic bearing part further includes a sub coil part provided inside the sub stator to be disposed between adjacent conductors to measure a distance between the rotor and the sub stator.

The method of claim 3, wherein
The sub stator through the installation hole communicated to both sides on the circumferential surface;
The conductor is screwed to a knob inserted into the installation hole to vary a distance from the rotating body to maintain a bearing force on the rotating body;
And the knob forms a clamping member at an end thereof.

3. The method according to claim 1 or 2,
The rotating body is a magnetic bearing system, characterized in that the initial position is determined by the interaction with the main magnetic bearing portion.