JPH11101233A - Magnetic bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a magnetic bearing device itself by integrally installing a control device in a magnetic bearing assembly. SOLUTION: A control part 80 covered with a control part case 82 having the same diameter as a housing 60 is installed on one end of a magnetic bearing assembly 70 covered with the housing 60 as a control device of a magnetic bearing. When a rotary shaft 1 is dislocated from an attraction force balanced position of a permanent magnet group 32 of a stator core in the radial direction, a radial directional displacement sensor 2 detects its dislocation. In such a case, the radial directional displacement sensor 2 outputs a position detecting signal corresponding to a dislocation quantity of the rotary shaft 1 to a driver 84 arranged in the control part 80. A control circuit part 85 flows a control current to an exciting coil 33 through a power amplifier 86 so as to return the rotary shaft 1 to a target position by receiving the position detecting signal from the driver 84. As a result, the rotary shaft 1 returns to an attraction force balanced position of the permanent magnet group 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic bearing device for rotatably supporting a rotating body in a non-contact manner by utilizing a magnetic attraction force.

[0002]

2. Description of the Related Art There is known a magnetic bearing which rotatably supports a rotating body in a non-contact manner by utilizing a magnetic attraction force. Since such a magnetic bearing can support a rotating body in a non-contact state, it has many advantages such as low bearing loss, maintenance-free, low noise, no lubrication oil, and use in a vacuum.

FIG. 5 is a sectional view of a magnetic bearing disclosed in Japanese Patent Laid-Open No. 4-171316. In the figure,
The magnetic bearing is mainly composed of two members, a shell 301 and a rotating shaft 302. A motor stator 303 is disposed on the inner peripheral surface of the shell 301, and a motor rotor 304 is disposed on the outer peripheral surface of the rotating shaft 302 so as to face each other.

A set of electromagnetic attraction stators 305 a and 305 b is provided on the inner peripheral surface of the shell 301 in the axial direction, and electromagnetic attraction rotors 306 a and 306 are provided on the outer peripheral surface of the rotating shaft 302.
b are arranged so as to face each other, and constitute a radial bearing using electromagnetic attraction.

A disk-shaped thrust plate 307 is arranged on the outer periphery of the rotating shaft 302, and an electromagnetic attraction stator 308 is arranged on the inner peripheral surface of the shell 301 so as to sandwich the thrust plate 307. It constitutes a thrust bearing.

Further, a rotating shaft 302 is provided inside the shell 301.
Are provided with position detecting displacement sensors 309a, 309b, 310 for detecting the positions in the radial direction and the thrust direction. Further, a tool 311 is attached to the tip of the rotating shaft 302.

The rotating shaft 302 is generally made of a ferromagnetic material so that the magnetic efficiency of the motor rotor 304 and the thrust plate 307 does not decrease. In addition, each rotor 30
4, 306a and 306b are made of a silicon steel plate, and the silicon steel plate is fitted on the rotating shaft 302.

Further, a control device for supporting the rotating shaft 302 at a center position of the magnetic bearing is separately provided in the magnetic bearing as shown (not shown). Such a control device includes displacement sensors for position detection 309a, 309b, 31
0 driver and position detecting displacement sensor 309a,
A control circuit for generating a control signal for controlling the magnetic bearing based on the detection outputs of 309b and 310; a power amplifier (power amplifier) for amplifying the control signal and supplying the power to the magnetic bearing; And a DC power supply unit for performing the operation.

[0009]

However, in the conventional device, since the magnetic bearing main body and the control device are separately provided, there is a disadvantage that a large space is required for installing the magnetic bearing device.

Accordingly, an object of the present invention is to reduce the size of the magnetic bearing device and expand the applications of the magnetic bearing device.

[0011]

In order to solve the above-mentioned problems, a magnetic bearing device according to the present invention provides a radial magnetic bearing for supporting a rotating shaft and the rotating shaft in a radial direction, and a radial magnetic bearing for supporting the rotating shaft in an axial direction. A magnetic bearing assembly having a thrust magnetic bearing and a displacement sensor for detecting the position of the rotating shaft; and a control device for supplying a control current to the radial magnetic bearing and the thrust magnetic bearing based on a detection output of the displacement sensor. The control device is characterized in that the control device is integrally assembled to the magnetic bearing assembly.

In the above-mentioned magnetic bearing device, the radial magnetic bearing and the thrust magnetic bearing may be of a combined magnet type. That is, the stator core of the radial magnetic shaft is configured by disposing a permanent magnet on a partial cross section of a magnetic steel sheet laminated body on which a radial coil for excitation is wound. A permanent magnet may be arranged in a partial cross section of the body, and an exciting thrust coil wound along the recess of the annular body may be provided.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view showing the magnetic bearing device according to the first embodiment cut along an axis thereof. FIG. 2 is a cross-sectional view obtained by cutting along the line II-II in FIG.

The magnetic bearing assembly 70 includes a radial magnetic bearing, a thrust magnetic bearing,
It has a structure incorporating a mechanism such as a drive motor.

The rotating shaft 1 accommodated in the cylindrical housing 60 at the axial center position is rotatably supported at the illustrated position as described later. The rotating shaft 1 is formed with a flange portion 11 extending in a radial direction from substantially the center.

A radial rotor core 12, which constitutes a radial magnetic bearing, is fitted to the outer periphery of both ends in the axial direction of the rotating shaft 1. The radial rotor core 12 is an axially laminated body of annular magnetic steel plates.

As shown in FIG. 2, the radial rotor core 1
Two magnetic steel sheet laminates 31 as U-shaped stator cores constituting a radial magnetic bearing are arranged at equal intervals in the circumferential direction with respect to the housing 60 on the outer side in the radial direction. This magnetic steel sheet laminate 3 is sufficient if three or more.
1 has a first portion 31a having an L-shaped cross section and a second portion 31b having an I-shaped cross section, and a permanent magnet 32 is interposed between the two portions 31a and 31b. Also, both parts 31
An excitation coil 33 is wound around a and 31b.

Returning to FIG. 1, substantially at the center of the rotary shaft 1, a flange portion 11 constituting a thrust magnetic bearing is provided extending in the radial direction. An annular body 5 of a magnetic material having a U-shaped cross section is provided at a position opposed to both axial sides of the flange portion 11 as a stator core constituting a thrust magnetic bearing.
1 is held by the thrust housing 50 and arranged concentrically with the rotation axis of the rotation shaft 1. The annular body 51 is formed of an annular permanent magnet 52 concentrically interposed in a part of its cross section.
And an exciting coil 53 is wound around the groove.

A radial displacement sensor 2 for detecting a radial position of the rotary shaft 1 and outputting a position signal is provided near both ends of the rotary shaft 1 in the axial direction. An axial displacement sensor 5 that senses the axial position of the flange 11 and outputs a position detection signal is provided near the outer periphery of the flange 11.

Touch-down bearings 65 which are not normally in contact with the small diameter portions 1a formed at both ends in the axial direction of the rotary shaft 1 are arranged and fixed to the housing 60. A stator 44 is disposed substantially at the center of the housing 60, and a rotor 4
5 are arranged, and the stator 44 and the rotor 45
A drive motor is constituted by the above.

At one end of the magnetic bearing assembly 70 covered by the housing 60, a control unit 80 covered by a control unit case 82 having the same diameter as the housing 60 is provided as a magnetic bearing control device.
Is attached. In the case 82, a driver 84 that drives the radial displacement sensor 2 and the axial displacement sensor 5 to receive a position detection signal, and a magnetic bearing assembly based on the position detection signal received via the driver 84 A control circuit section 85 for generating a control signal for controlling the position of the radial magnetic bearing and the thrust magnetic bearing constituting 70 by PID control or the like, and a power amplifier 86 for power amplifying the control signal output from the control circuit section 85
And a DC power supply 87 that supplies power to the driver 84, the control circuit 85, and the power amplifier 86 for driving them.

Next, the operation of this embodiment will be described.
First, the radial position control of the rotating shaft 1 will be described.
When the rotating shaft 1 is displaced in the radial direction from the position where the attraction force of the permanent magnet group 32 of the stator core is balanced, the displacement is detected by the radial displacement sensor 2. In such a case, the radial displacement sensor 2 outputs a position detection signal corresponding to the amount of displacement of the rotating shaft 1 to a driver 84 provided in the control unit 80.

The control circuit unit 85 of the control unit 80 receives the position detection signal from the driver 84 and returns the exciting coil 3 via the power amplifier 86 so as to return the rotating shaft 1 to the target position.
A control current is passed through 3. The control circuit 85 detects the control current flowing through the exciting coil 33, and sets the target position signal as a control system to match the position where the attractive force of the permanent magnet group 32 is balanced so that the control current becomes zero. A feedback control operation for changing the position signal is performed. As a result, the rotating shaft 1 returns to the position where the attractive force of the permanent magnet group 32 is balanced, and the control current in that state becomes a minute current only for the differential operation for suppressing the minute fluctuation of the rotating shaft 1.

Next, control of the thrust position of the rotating shaft 1 will be described. When the rotating shaft 1 is displaced in the axial direction from the position where the attractive force of the permanent magnet 52 of the stator core is balanced, the displacement is detected by the axial displacement sensor 5. In such a case, the axial displacement sensor 5 outputs a position detection signal corresponding to the amount of displacement of the rotating shaft 1 to the driver 84 of the control unit 80.

The control circuit unit 85 of the control unit 80 receives the position detection signal from the driver 84 and returns the exciting coil 5 via the power amplifier 86 to return the rotating shaft 1 to the target position.
A control current is passed through 3. The control circuit unit 85 detects the control current flowing through the exciting coil 53 and sets the target position signal so that the control current becomes zero when the target position signal as the control system matches the position where the attractive force of the permanent magnet 52 is balanced. A feedback control operation for changing a signal is performed. As a result, the rotating shaft 1 returns to the position where the attractive force of the permanent magnet 52 is balanced,
The control current in that state is a minute current only for the differential operation for suppressing the minute fluctuation of the rotating shaft 1.

According to the magnetic bearing device of the first embodiment described above, since the control unit 80 is integrated with the magnetic bearing assembly 70, the size of the magnetic bearing device itself can be reduced. Further, it is possible to easily handle the magnetic bearing device as a unit, so that the use of the magnetic bearing device can be expanded. Furthermore, in the magnetic bearing device of the present embodiment, both the radial and thrust bearings have a magnetic bearing structure in which the permanent magnets 32 and 52 are used together, so that the bias current of the magnetic bearing becomes almost unnecessary and the control current capacity becomes small. In addition, the control power supply can be downsized. That is, the driver 84, the control circuit unit 85, the power amplifier 8
6. The control device 80 including the DC power supply unit 87 and the like can be easily integrated with the magnetic bearing main body 70, and the magnetic bearing device as a whole can be small. [Second Embodiment] A second embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a longitudinal sectional view showing the magnetic bearing device according to the second embodiment cut along the axis thereof. FIG. 4 is a cross-sectional view obtained by cutting along the line III-III in FIG.

The magnetic bearing device according to the second embodiment is a modification of the magnetic bearing device according to the first embodiment, and the same parts are denoted by the same reference numerals and the description thereof will not be repeated.

The magnetic bearing device of the second embodiment also includes a magnetic bearing assembly 70 and a control unit 80. In the former magnetic bearing assembly 70, the structure of the radial magnetic bearing is changed from the structure shown in FIGS. 1 and 2 to that shown in FIGS. 3 and 4, and the control unit 80 in the latter is shown in FIG. 1 is the same as that shown in FIG.

As shown in FIGS. 3 and 4, the radial magnetic bearing in the second embodiment has a magnetic pole arrangement in the axial direction. On the radially outer side at both axial ends of the radial rotor core 12, an electromagnetic steel sheet laminate 131 as a U-shaped stator core constituting a radial magnetic bearing is provided.
Are arranged at equal intervals in the circumferential direction with respect to the housing 60. This electromagnetic steel sheet laminate 131 has a cross section L
-Shaped first portion 131a and I-shaped second portion 13 in cross section
1b, and a permanent magnet 132 is interposed between the two portions 131a and 131b. Both parts 131a, 13
An excitation coil 133 is wound around 1b. Note that, in the case of the magnetic bearing device of the present embodiment, the radial rotor core 12 is a circumferentially laminated body of I-type magnetic steel sheets and prevents generation of eddy current.

The magnetic bearing assembly 70 of the first embodiment
In this case, since the electromagnetic pole polarity of the radial magnetic bearing alternates in the rotation direction, relatively large hysteresis loss and eddy current loss occur in the radial rotor core 12, which is a laminate of annular plates provided on the rotating shaft 1. Easy to do,
It can be said that the rotating shaft 1 easily generates heat. On the other hand, the second
In the magnetic bearing assembly 70 of the embodiment, the polarities of the electromagnetic poles of the radial magnetic bearing do not alternate in the rotation direction, and the occurrence of hysteresis loss and eddy current loss can be suppressed. Thus, the control current can be further reduced as compared with the radial magnetic bearing of the first embodiment, and the size of the control unit 80 can be reduced more effectively.

[0031]

As is apparent from the above description, in the magnetic bearing device according to the present invention, since the control device is integrated with the magnetic bearing assembly, the size of the magnetic bearing device itself can be reduced. In addition, since the magnetic bearing device can be handled as a unit, the handling of the magnetic bearing device can be simplified and its use can be expanded.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of a magnetic bearing according to the present invention, cut along an axis thereof.

FIG. 2 is a cross-sectional view obtained by cutting along a line II-II in FIG.

FIG. 3 is a longitudinal sectional view showing a second embodiment of the magnetic bearing of the present invention, cut along an axis thereof.

FIG. 4 is a cross-sectional view obtained by cutting along a line II-II in FIG.

FIG. 5 is a sectional view showing a magnetic bearing according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotation shaft 2 Radial displacement sensor 5 Axial displacement sensor 11 Flange part 12 Radial rotor core 31, 131 Magnetic steel sheet laminated body 32, 132 Permanent magnet 33, 133 Excitation coil 40 Ring body 44 Stator 45 Rotor 60 Housing 65 Touch-down bearing

Claims (1)

[Claims] 1. A magnetic bearing set comprising: a rotating shaft; a radial magnetic bearing that supports the rotating shaft in a radial direction; a thrust magnetic bearing that supports the rotating shaft in an axial direction; and a displacement sensor that detects a position of the rotating shaft. In a magnetic bearing device comprising: a solid and a control device that supplies a control current to the radial magnetic bearing and the thrust magnetic bearing based on a detection output of the displacement sensor, wherein the control device is integrated with the magnetic bearing assembly. A magnetic bearing device which is assembled.