JPH11166533A - Magnetic bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic bearing device capable of easily and correctly judging the quality of protective bearings without disassembling the device. SOLUTION: This magnetic bearing device is provided with plural sets of magnetic bearings 3, 4, 5; a position detecting device 6 for a rotor 2; an electromagnet control device; an electric motor 7; and protective bearings 10, 11 comprising rolling bearings. The rotor 2 in a rotation stop state is brought into contact with the inner peripheral surfaces of inner rings 10b, 11b of the protective bearings 10, 11, and contact points are moved in order in the circumferential direction of the inner peripheral surfaces of the protective bearing inner rings 10b, 11b. The radial position of the center of the rotor 2 is detected from the position detected result of the position detecting device 6 in a plurality of points in this moving process, and the quality of the protective bearings 10, 11 is judged on the basis of the detected result of the radial position of the center of the rotor 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a magnetic bearing device,
More specifically, the present invention relates to a magnetic bearing device in which a rotating body is supported by a plurality of sets of magnetic bearings in a non-contact manner in an axial direction (axial direction) and a radial direction (radial direction) and is rotated by an electric motor.

[0002]

2. Description of the Related Art As a magnetic bearing device of this kind, a plurality of sets of magnetic bearings having a plurality of electromagnets for supporting a rotating body in a non-contact manner in an axial direction and a radial direction, and detecting the axial and radial positions of the rotating body. Position detecting means having a plurality of position sensors to perform, electromagnet control means for controlling the electromagnet of each of the magnetic bearings based on a position detection result by the position detecting means,
An electric motor that rotationally drives the rotating body, and a protective bearing that includes a rolling bearing that mechanically supports the rotating body at an extreme position of the movable range by regulating the movable range in the axial direction and the radial direction of the rotating body. What is provided is known.

[0003] Such a magnetic bearing device is used, for example, in a turbo-molecular pump or the like, and drives the motor in a state where the rotating body is supported in a non-contact manner at a predetermined target position by a magnetic bearing, so that the rotating body is driven at a high speed. By rotating the motor and stopping the driving of the motor, the rotating body is stopped from rotating. Then, after the rotation of the rotating body is stopped, when the driving of the magnetic bearing is stopped to eliminate the supporting force of the magnetic bearing, the rotating body is supported by the protective bearing.

When the rotating body is stopped and then supported by the protective bearing, the rotating body does not rotate when the rotating body is received by the protective bearing. Does not occur.

[0005] However, a rotating body that is rotating at a high speed may come into contact with the protective bearing due to a mistake in use or an abnormality in the control system. Also, when the power supply to the magnetic bearing and the motor is stopped due to a power failure while the rotating body is rotating,
The rotating body that is rotating at high speed is received by the protective bearing, gradually decelerates, and eventually stops rotating. In such a case, the protective bearing comes into contact with the rotating body rotating at high speed, rotates at high speed, and receives a large force from the rotating body. Therefore, the protective bearing is greatly worn and may be damaged. Therefore, in general, the life of a protective bearing is short, and its use is limited to several uses. For this reason, before stopping the rotation and rotating the rotating body supported by the protection bearing again by the magnetic bearing, it is necessary to inspect the quality of the protection bearing, that is, whether the life of the protection bearing has expired. . However, in the conventional magnetic bearing device, it is necessary to disassemble the magnetic bearing device in order to know the state of the protective bearing, which is inconvenient.

[0006] In order to solve such a problem, the time from when the protective bearing receives the rotating body when the operation is stopped to when the rotation speed of the rotating body decelerates to a predetermined value is shorter than normal. A magnetic bearing device that detects and detects an abnormality of the protective bearing (see Japanese Patent Application Laid-Open No. 3-115796).
However, it has been difficult to accurately determine the quality of the protective bearing in any case.

In view of this, the present applicant has proposed that the rotating body be attracted in one radial direction by the electromagnet of the magnetic bearing and pressed against one of the bearing rings of the protective bearing, and the rotating body and the protection pressed against the rotating body be pressed by the motor. A magnetic bearing device that rotates a bearing ring of a bearing, detects a change in a radial position of a rotating body by a position detecting unit, and determines the quality of a protective bearing based on the detection result (see Japanese Unexamined Utility Model Publication No. 43346).

With this magnetic bearing device, the quality of the protective bearing can be determined fairly accurately without disassembling the device.

However, since the rotating body is rotated by the motor at the time of inspection of the protective bearing, it is necessary to rotate the motor at a low speed different from the normal rotation at this time. It is necessary to separately provide the inverter for driving the motor, and there is a problem that the structure of the magnetic bearing device is complicated. Further, since the rotating body is simply rotated by the motor, if there is an abnormality only at a specific position in the circumferential direction of the protective bearing, the position cannot be specified.

The magnetic bearing device includes an inner rotor type in which a rotating body rotates inside a casing, which is a fixed portion, and an outer rotor type in which a rotating body rotates outside a fixed portion. Has the above-mentioned problem.

The magnetic bearing device includes a horizontal type in which the rotating body is supported horizontally and a vertical type in which the rotating body is supported vertically. is there.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a magnetic bearing device capable of easily and accurately determining the quality of a protective bearing without disassembling the device.

[0013]

A magnetic bearing device according to the present invention comprises a plurality of sets of magnetic bearings having a plurality of electromagnets for supporting a rotating body in a non-contact manner in an axial direction and a radial direction, and a shaft of the rotating body. Position detecting means having a plurality of position sensors for detecting the position in the direction and the radial direction, electromagnet control means for controlling the electromagnets of the respective magnetic bearings based on the result of position detection by the position detecting means, and rotationally driving the rotating body Bearing device comprising: an electric motor to be driven; and a protection bearing comprising a rolling bearing for restricting the movable range of the rotating body in the axial and radial directions and mechanically supporting the rotating body at an extreme position of the movable range. In this case, one position in the circumferential direction of the peripheral surface of the rotating body in the rotation stopped state is brought into contact with one position in the peripheral direction of the peripheral surface of the protective bearing facing the rotational body, and this contact point is moved forward. Means for sequentially moving the circumferential surface of the protective bearing in the circumferential direction, means for detecting a radial position of the center of the rotating body from a result of position detection by the position detecting means at a plurality of points in the moving process, and the moving It is characterized by comprising means for judging the quality of the protective bearing based on the detection result of the radial position of the center of the rotating body at each point in the process.

Normally, the magnetic bearing includes an axial magnetic bearing for supporting the rotating body in the axial direction and a radial magnetic bearing for supporting the rotating body in the radial direction. For example, the quality of the protection bearing is determined in a state where the rotating body is supported at a predetermined position in the axial direction by the axial magnetic bearing.

The range of movement of the rotating body along the peripheral surface of the protective bearing is desirably substantially all around the peripheral surface of the protective bearing, but may be a part of the peripheral surface of the protective bearing.

In the case where the protective bearing is normal, when the rotating body is moved in the circumferential direction of the protective bearing in a state of being in contact with the peripheral surface of the protective bearing, the center of the rotating body becomes one of the concentric centers with the peripheral surface of the protective bearing. It moves on a circle, and the radius of the circle becomes a constant value corresponding to the size of the gap between the rotating body and the protective bearing. If this circle is assumed to be the normal circle, if the protective bearing has an abnormality such as excessive wear or damage, the radial position of the center of the rotating body at multiple points in the moving process of the rotating body can be detected. Some values are far away from the normal circle. Therefore, based on the detection result of the position of the center of the rotating body at each point in the moving process of the rotating body, the quality of the protective bearing can be easily and reliably determined.

For example, the radius of a circle passing through the center of the rotating body at each point in the moving process of the rotating body is determined. When this radius is smaller than a predetermined value, it is determined that the gap between the rotating body and the protective bearing is abnormally small. On the contrary, when this radius is larger than the predetermined value, it is determined that an abnormality such as excessive wear or damage has occurred in the protective bearing.

When the gap between the rotating body and the protective bearing becomes abnormally small, the radius of the circle passing through the center of the rotating body at each point in the moving process of the rotating body becomes smaller than the radius of the normal circle. Further, when an abnormality such as excessive wear or damage occurs in the protective bearing, the radius of a circle passing through the center of the rotating body at each point in the moving process of the rotating body is larger than the radius of the circle in a normal state. Therefore, by doing the above,
It is possible to reliably detect that the gap between the rotating body and the protection bearing is abnormally small and that the protection bearing has an abnormality such as excessive wear or damage.

For example, in the detected value of the center of the rotating body at each point in the moving process of the rotating body, the distance from the center of the circle passing through the center of the rotating body is abnormally different from the value of the radius of the normal circle. If there is a point, it is determined that the protective bearing is abnormal.

In the case where there is an abnormality at one place in the circumferential direction of the protective bearing, the radial position of the center of the rotating body when the rotating body is in contact with the place largely deviates from the normal circle. Therefore, by performing the above, even if there is an abnormality at only one location in the circumferential direction of the protective bearing,
This can be reliably detected.

For example, by appropriately controlling the exciting current supplied to each electromagnet of the radial magnetic bearing, the exciting current of each electromagnet is gradually changed to bring the peripheral surface of the rotating body into contact with the peripheral surface of the protective bearing. In this state, the contact points are sequentially moved in the circumferential direction of the peripheral surface of the protective bearing.

When the radial magnetic bearing includes two pairs of electromagnets facing each other in two control axis directions, for example, the exciting current of each electromagnet is controlled as follows. First, an exciting current is supplied only to the first electromagnet, and the rotating body is attracted to one extreme position in one control axis direction. Next, the exciting current of the first electromagnet is gradually reduced to 0, and the exciting current of the adjacent second electromagnet is gradually increased. Move to one extreme position in the axial direction. Then, between the second electromagnet and the next third electromagnet, between the third electromagnet and the next fourth electromagnet, and between the fourth electromagnet and the first first electromagnet. Similarly, the exciting current is controlled. This allows the rotating body to make substantially one revolution along the peripheral surface while being in contact with the peripheral surface of the protective bearing.

Further, since the rotating body can be moved in the circumferential direction by controlling the exciting current of the electromagnet of the magnetic bearing, there is no need to rotate the rotating body with a motor as in the prior art, and an inverter for driving the motor is required. It is not necessary to separately provide a special rotation speed control circuit. That is, the protection bearing can be inspected only by changing the control method of the electromagnet of the magnetic bearing without changing the structure of the magnetic bearing device at all. Also, when the rotating body is moved in the circumferential direction by controlling the exciting current of the electromagnet of the magnetic bearing, it is possible to detect the position of the rotating body in the circumferential direction of the protective bearing from the state of the exciting current of each electromagnet. Even when there is an abnormality only at a specific position in the circumferential direction of the protective bearing, the position can be specified and the abnormality can be detected more accurately.

According to the magnetic bearing device of the present invention, as described above, the quality of the protective bearing can be easily and accurately determined without disassembling the device.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a partially cutaway perspective view showing a main part of a magnetic bearing device, FIG. 2 is a longitudinal sectional view, FIG. 3 is a transverse sectional view thereof, and FIG. 4 is a block diagram showing an example of an electrical configuration thereof. FIG.

This magnetic bearing device is of a horizontal type in which a horizontal shaft-shaped rotating body (2) rotates inside a horizontal cylindrical casing (1). In the following description, the axial control axis (axial control axis) of the rotating body (2) is the Z axis, and one radial control axis (radial control axis) orthogonal to the Z axis is the X axis, the Z axis, and the X axis. The other radial control axis orthogonal to the axis is defined as the Y axis. In addition, the right side in FIG. 2 is the front, the left side is the rear, and the left and right when the front is viewed from the rear is the left and right. In this example, the Z-axis direction coincides with the front-rear direction, the X-axis direction coincides with the left-right direction, the Y-axis direction coincides with the up-down direction, the front side is the Z-axis positive side, the right side is the X-axis positive side, and the upper side is the Y-axis positive side. ing.

The magnetic bearing device comprises a set of axial magnetic bearings (3) for supporting the rotating body (2) in a non-contact manner in the axial direction, and the rotating body (2).
Two sets of radial magnetic bearings that support the shaft radially in a non-contact manner
(4) (5), a position detecting device (6) as position detecting means for detecting the axial and radial positions of the rotating body (2), the rotating body (2)
Built-in type electric motor (7) for rotating the
An electromagnet control device (8) as electromagnet control means for controlling the magnetic bearings (3) (4) (5) based on the position detection result by the position detection device (6), and the axial direction of the rotating body (2) and Rotating body (2) with magnetic bearings (3) (4) (5)
And two sets of front and rear protection bearings (10) and (11) as regulating means for mechanically supporting the rotating body (2) at the extreme position of the movable range when it cannot be supported.

The position detecting device (6) has one axial position sensor (1) for detecting the axial position of the rotating body (2).
2), front and rear 2 to detect the radial position of the rotating body (2)
A set of radial position sensor units (13) and (14) and a position calculation circuit (15) for calculating the axial position and the radial position of the rotating body (2) from these outputs are provided. The position calculation circuit (15) calculates the position of the center (A) of the rotating body (2) whose origin is the center position with respect to the sensor described later. Note that the position of the center (A) of the rotating body (2) whose origin is the center position of the sensor is simply referred to as the position of the rotating body (2).

The axial magnetic bearing (3) is composed of a pair of axial electromagnets (16) arranged so as to sandwich a flange (2a) integrally formed on the front part of the rotating body (2) from both sides in the Z-axis direction.
a) (16b) is provided. Axial electromagnets are collectively referred to by the reference numeral (16).
(16a) is the first axial electromagnet, electromagnet on the negative side of the Z axis (16b)
Is referred to as a second axial electromagnet.

The axial position sensor (12) includes a rotating body (2)
And a distance signal proportional to the distance (gap) from the front end face of the rotating body (2) to the front end face (position detection end face) from the positive side in the Z-axis direction. And an arithmetic circuit
An axial position sensor (21) is calculated from a predetermined value (a value equal to the distance signal of the axial position sensor (12) when the position of the rotating body (2) in the Z-axis direction becomes 0). By subtracting the distance signal, the position of the rotating body (2) in the Z-axis direction is calculated and output to the electromagnet controller (8).

The two sets of radial magnetic bearings (4) and (5) are arranged at predetermined intervals in the front-rear direction on the rear side of the axial magnetic bearing (3), and the motor (7) is located between them. Are located. The radial magnetic bearing (4) on the front side
A pair of radial electromagnets (17a) and (17b) arranged to sandwich (2) from both sides in the X-axis direction, and a pair of radial electromagnets (17a) and (17b) arranged to sandwich the rotating body (2) from both sides in the Y-axis direction Radial electromagnets (17c) and (17d) are provided. These radial electromagnets are collectively referred to by reference numeral (17), and when it is necessary to distinguish them, the electromagnet on the positive side in the X-axis direction (17a) is the first X-axis electromagnet, and the electromagnet on the negative side (17b) is the second X-axis electromagnet. , The positive electromagnet (17
c) is referred to as a first Y-axis electromagnet, and the negative electromagnet (17d) is referred to as a second Y-axis electromagnet. Similarly, the rear radial electromagnet
(5) also includes a first X-axis electromagnet (18a), a second X-axis electromagnet (18b),
A first Y-axis electromagnet (18c) and a second Y-axis electromagnet (18d) are provided. These radial electromagnets (18a) to (18d) also
(18).

Front radial position sensor unit (13)
Are arranged in the vicinity of the radial magnetic bearing (4) on the front side, and are arranged in the vicinity of the X-axis electromagnets (17a) (17b) so as to sandwich the rotating body (2) from both sides in the X-axis direction. Radial position sensors (19a) and (19b), and a pair of radial position sensors (19c) arranged so as to sandwich the rotating body (2) from both sides in the Y-axis direction in the vicinity of the Y-axis electromagnets (17c) and (17d). (19d). These radial position sensors are collectively referred to by reference numeral (19), and when it is necessary to distinguish them, a sensor (19a) on the positive side in the X-axis direction is a first X-axis sensor, and a sensor (19b) on the negative side is a second X-axis sensor.
The axis sensor, the sensor (19c) on the positive side in the Y-axis direction is referred to as a first Y-axis sensor, and the sensor (19d) on the negative side is referred to as a second Y-axis sensor. Similarly, the rear radial position sensor unit (1
4) is also disposed near the rear radial magnetic bearing (5), and includes a first X-axis sensor (20a), a second X-axis sensor (20b), a first Y-axis sensor (20c), and a second Y-axis sensor (20). 20d). These radial position sensors (20a) to (20d) are also collectively referred to by reference numeral (20). Each radial position sensor (19) (20)
It outputs a distance signal proportional to the distance from the outer peripheral surface of the rotating body (2). Then, the position calculation circuit (15) is connected to the unit (1
By subtracting the distance signal of the first X-axis sensor (19a) from the distance signal of the second X-axis sensor (19b) in 3), the X-axis direction of the rotating body (2) in the vicinity of the front radial magnetic bearing (4) Is calculated, and the distance signal of the first Y-axis sensor (19c) is subtracted from the distance signal of the second Y-axis sensor (19d) of the same unit (13), so that the Y of the rotating body (2) at the same position is obtained. The position in the axial direction is calculated and output to the electromagnet controller (8). Similarly, the position calculation circuit (15) is connected to the rear unit (14).
The distance signal of the second X-axis sensor (20b) and the first X-axis sensor (20b).
The position of the rotating body (2) in the X-axis direction in the vicinity of the rear radial magnetic bearing (5) is obtained from the difference in the distance signal of (a), and the position of the second Y-axis sensor (20d) of the unit (14) is determined. From the difference between the distance signal and the distance signal of the first Y-axis sensor (20c), the position of the rotating body (2) at the same position in the Y-axis direction is obtained and output to the electromagnet controller (8).

Electromagnets (16) (17) (18) and position sensor (12)
(19) and (20) are fixed to the casing (1).

The front protection bearing (10) is made of a rolling bearing such as a deep groove ball bearing, and can receive both an axial load and a radial load. The outer ring (10a) of this bearing (10) is fixed to the casing (1) and the inner ring (1
0b) faces an annular groove (21) formed on the outer peripheral surface of the rotating body (1) with an appropriate gap in the axial and radial directions. The rear protective bearing (11) is made of, for example, a rolling bearing such as a deep groove ball bearing, and can receive a radial load. The outer ring (11a) of the bearing (11) is fixed to the casing (1), and the inner ring (11b) is arranged to face the outer peripheral surface of the rotating body (1) with an appropriate gap. The axial movable range of the rotating body (1) is regulated by the size of the axial gap between the inner ring (10b) of the front bearing (10) and the rotating body (1). Due to the size of the radial gap between the inner ring (10b) (11b) of the (10) and (11) and the rotating body (1), the rotating body
The movable range in the radial direction of (1) is regulated. And the rotating body
Even when (2) is supported by the protective bearings (10) and (11) at the extreme position of the movable range, the rotating body (2) and the electromagnet (16)
There is a gap between (17) (18) and the position sensors (12) (19) (20), and the rotating body (2) has electromagnets (16) (17) (18) and position sensors (12) ( 19) No contact with (20).

The rotating body (2) and the inner ring (10) of the protective bearings (10) and (11)
b) (11b), electromagnets (16) (17) (18) and position sensors (12) (1
Although the gap with 9) and (20) is at most about several mm, this is exaggerated in the drawings.

The control device (8) controls the position of the rotating body (2) in the Z-axis direction obtained as described above by the position detection device (6) and the two sets of radial magnetic bearings (4) and (5). The magnitude of the exciting current flowing through each of the electromagnets (16), (17), and (18) is controlled based on the positions of the rotating body (2) in the X-axis direction and the Y-axis direction in the vicinity, whereby the rotating body (2 ) Is held at a constant target position described later.

In the above magnetic bearing device, protective bearings (10) (1)
Axial and radial center positions (mechanical center positions) of the rotating body (2) with respect to the movable range by (1), and magnetic bearings (3) (4)
Axial and radial center positions (magnetic center positions) with respect to the positions of the electromagnets (16), (17), and (18) in (5), and a position detecting device
There is an axial and radial center position (with respect to the sensor center position) with respect to the position of the position sensors (12), (19), and (20) of (6).
The mechanical center position is the position of the center of the movable range regulated by the protective bearings (10) and (11) .In the axial direction, the inner ring (10b) of the front protective bearing (10) is rotated by the rotating body (2). It is a position where the axial gap between the end face of the inner ring (10b) and the side face of the groove (21) opposed thereto comes to be equal to each other on both sides, Is a rotating body (2)
Center (A) coincides with the center of the two sets of protective bearings (10) and (11), and the radial direction between the rotating body (2) and the inner rings (10b) and (11b) of the protective bearings (10) and (11) Is a position where the gap becomes equal over the entire circumference. The magnetic center position is the position of the center of each pair of electromagnets (16), (17), (18) facing each control axis direction of each magnetic bearing (3) (4) (5). The center position with respect to the sensor is such that, in the axial direction, the distance between the front end face of the rotating body (2) and the axial position sensor (12) becomes the above-mentioned predetermined constant value. Is the radial position sensor unit
(13) This is the center position of each pair of radial position sensors (19) and (20) opposed to each control axis direction of (14). The center position of the sensor in the radial direction is O1, and the mechanical center position in the radial direction is O2.

The magnetic bearing device is designed so that the mechanical center position, the magnetic center position, and the center position with respect to the sensor are all the same, but errors may occur between them due to manufacturing errors and assembly errors. is there.

In the conventional magnetic bearing device, the rotating body is held at the designed center position with respect to the sensor, that is, the center of the rotating body is aligned with the sensor center position. The electromagnet is controlled. For this reason,
If the center position with respect to the sensor does not match the mechanical center position, the rotating body cannot be held at the mechanical center position. In this case, if the error between the mechanical center position of the rotating body and the center position with respect to the sensor is large, the gap between the rotating body and the protective bearing is partially reduced when the rotating body is held at the center position with respect to the sensor. This causes various problems. In order to avoid such a problem, as described in, for example, Japanese Patent Application Laid-Open No. 2-107815, the output of the position sensor when the rotating body is moved to both extreme positions of the movable range with respect to each control axis is used as a machine. A magnetic bearing device has been proposed in which a magnetic center position is determined, and the rotating body is magnetically levitated at the mechanical center position.

However, in the magnetic bearing device as described above, the exciting current is suddenly supplied to only one electromagnet of each radial magnetic bearing, and the rotating body is moved to the extreme position in the direction of the electromagnet. Collides with the protective bearing, and at this time, a large reaction or vibration occurs, which may damage the protective bearing. In addition, since the exciting current of the electromagnet is rapidly changed, the rush current of the power amplifier that drives the electromagnet is increased, and the life of the power amplifier is shortened.

For this reason, in the above-described magnetic bearing device, when starting operation for the first time, the mechanical center position is obtained as follows, and thereafter, this mechanical center position is set as the target position and the magnetic center position is determined. The control of the bearings (3), (4) and (5) is performed.

FIG. 5 is a diagram showing a state where the excitation current of each electromagnet (17) and (18) of the radial magnetic bearings (4) and (5) when the mechanical center position is obtained is set to the lower side, and the rotating body (2) and the protective bearing ( The positional relationship between the inner ring (11b) and the inner peripheral surface of (11) is shown on the upper side. Although FIG. 5 shows only the relationship between the rotating body (2) and the rear protective bearing (11), the relationship between the rotating body (2) and the front protective bearing (10) is the same. .

Before the operation of the magnetic bearing device is started, the magnetic bearings (3), (4), (5) and the motor (7) are not driven, and the rotating body (2) is protected by the protective bearings (10), (11). ) Is stopped by being supported by the inner rings (10b) and (11b).

From such a state, the same exciting current is first supplied to the pair of axial electromagnets (16a) (16b), whereby the rotating body (2) is radially protected by the protective bearing.
While being mechanically supported by (10) and (11), it is axially supported by the axial magnetic bearing (3) at the axial center position of the sensor.

Next, as shown as T1 in FIG.
A constant exciting current I1 is supplied to the Y-axis electromagnets (17d) (18d). As a result, the rotating body (2) is attracted to the Y axis negative side, contacts the lower limit point Ym of the inner peripheral surface of the protective bearing inner ring (10b) (11b), and is held at the Y axis negative side limit position. Is done. At this time, the rotating body (2) that has stopped in contact with the vicinity of the lower limit point Ym is merely attracted by the electromagnets (17d) and (18d) and brought into contact with the point Ym. ) Hardly moves, and no impact is applied to the protective bearings (10) and (11). Next, the exciting current of the second Y-axis electromagnets (17d) and (18d) is gradually decreased in a stepwise manner, and the exciting current of the second X-axis electromagnets (17b) and (18b) adjacent to the clockwise direction is increased from 0. It is gradually increased stepwise, and as shown as T3 in FIG.
The exciting current of the shaft electromagnets (17d) and (18d) is set to 0, and the exciting current of the second X-axis electromagnets (17b) and (18b) is set to the maximum value I1. Thus, the second Y-axis electromagnets (17d) and (18d) and the second
By changing the exciting current of the shaft electromagnets (17b) (18b), as shown in T1, T2 and T3, the protection bearings (10b) (1
The contact point of the rotating body (2) with the inner peripheral surface of 1b) is the lower limit point Y
gradually move clockwise from m to the left limit point Xm side,
At T3, the rotating body (2) is attracted to the negative side of the X axis, contacts the left limit point Xm, and is held at the extreme position on the negative side of the X axis. Next, the exciting current of the second X-axis electromagnets (17b) and (18b) is gradually decreased stepwise, and the exciting current of the first Y-axis electromagnets (17c) and (18c) adjacent in the clockwise direction is increased from 0. As shown by T5 in FIG. 5, the exciting current of the second X-axis electromagnets (17b) (18b) is reduced to 0,
The exciting current of the Y-axis electromagnets (17c) (18c) is set to the maximum value I2, and T
As shown at 3, T4 and T5, the rotating body (2) is moved in the clockwise direction along the inner peripheral surface of the protective bearing inner ring (10b) (11b) in the Y-axis positive side contacting the upper limit point Yp. To the extreme position. Next, similarly to the above, the first Y-axis electromagnet (17c) (18c)
And the first X-axis electromagnet (17
a) By changing the exciting current of (18a), the rotating body (2)
From the extreme position on the Y axis positive side to the right extreme point Xp
Move clockwise to the extreme position on the positive side of the axis. Next, similarly to the above, by changing the exciting current of the first X-axis electromagnets (17a) (18a) and the second Y-axis electromagnets (17b) (18b) adjacent in the clockwise direction, the rotating body (2 ) Is moved clockwise from the extreme position on the positive side of the X axis to the extreme position on the negative side of the Y axis. As a result, the rotating body (2) makes one round in the clockwise direction along the inner circumferential surface of the inner race (10b) (11b) of the protective bearing.

The first and second X-axis electromagnets (17a) and (18a), the second X-axis electromagnets (17b) and (18b) and the second Y-axis electromagnets (17d) and (18d) have the same change pattern of increasing and decreasing the exciting current. The change in the exciting current of the first Y-axis electromagnets (17c) and (18c) is obtained by adding an amount corresponding to the gravity acting on the rotating body (2) to this change pattern (the portion shown by hatching in FIG. 5). It is a pattern.

At a plurality of points in the moving process of the rotating body (2), the position of the radial position sensor unit (13) (14) of the rotating body (2) is determined based on the output of the position detecting device (6). The positions in the axial direction and the Y-axis direction are obtained and stored.

When the detection of the position of the rotating body (2) at each point in the moving process of the rotating body (2) is completed in this manner, the radial position sensor units (13) (1)
The mechanical center position in the radial direction at the portion 4) is obtained.

As described above, the rotating body (2) is connected to the protective bearing inner ring.
(10b) When the inner peripheral surface of the rotating body (2) is moved in the circumferential direction while being in contact with one portion of the inner peripheral surface of (11b), the center (A) of the rotating body (2) becomes
It moves on a circle centered on the radial mechanical center position O2. Therefore, if the center of a circle passing through the center (A) of the rotating body (2) at each point in the moving process of the rotating body (2) is obtained, that becomes the mechanical center position O2 in the radial direction.

FIG. 6 shows the detection result of the position of the rotating body (2) in the rear radial position sensor unit (14) in XY coordinates with the origin relative to the sensor center position O1. From such a detection result, for example, a circle (C) passing through the center (A) of the rotating body (2) and its center are obtained by the least square method, and the center of the circle (C) is located on the rear side. This is the radial mechanical center position O2 of the radial position sensor unit (14). At the same time, the center of the rotating body (2)
The radius Rx in the X-axis direction and the radius Ry in the Y-axis direction of the circle (C) passing through (A) are also obtained. Radial position sensor unit on the front side
The same applies to the part (13).

After obtaining the mechanical center position in the radial direction as described above, the abnormality of the protection bearings (10) and (11) is detected as follows.

For example, the rotating body obtained as described above
When the radii Rx and Ry of the circle (C) passing through the center (A) of (2) are smaller than predetermined values, it is considered that the gap between the rotating body (2) and the protective bearings (10) and (11) is abnormally small. to decide. Conversely, the radii Rx, Ry
Is larger than a predetermined value, it is determined that an abnormality such as excessive wear or damage has occurred in the protective bearings (10) and (11). In addition, in the detected value of the center (A) of the rotating body (1) at each point in the moving process of the rotating body (2), the distance from the mechanical center position O2 in the radial direction is the value of the radii Rx and Ry. Also in the case where there is an abnormal difference, it is determined that the protective bearings (10) and (11) are abnormal.
In this case, it is determined that there is an abnormality in the circumferential position of the protection bearings (10) and (11) with respect to this abnormal point. The position of the rotating body (2) in the circumferential direction of the protective bearings (10) and (11) can be detected from the state of the exciting current of each of the radial electromagnets (17) and (18). Each radial electromagnet (1
7) An abnormal position can be identified from the state of the exciting current in (18).

When such an abnormality is detected, an alarm is issued and the magnetic bearing device is not started.

In determining the mechanical center position in the radial direction, the rotating body (2) is kept in contact with the inner peripheral surfaces of the inner rings (10b) and (11b) of the protective bearings (10) and (11). Protect contact point Inner ring of bearing (1
0b) Since the inner peripheral surface of (11b) is sequentially moved in the circumferential direction, the rotating body (2) does not collide with the inner races (10b) and (11b) of the protective bearing. Therefore, no large reaction or vibration occurs in the protection bearings (10) and (11), and damage to the protection bearings (10) and (11) is prevented. Also, instead of suddenly changing the exciting current of the electromagnets (16) (17) (18) to attract the rotating body (2) to the extreme position, the electromagnets (16) (17) (18) The magnetizing current is gradually changed to move the rotating body (2) along the inner peripheral surface of the protective bearing inner ring (10b) (11b), so that the electromagnets (16) (17) (18) are driven. The rush current of the power amplifier can be reduced, and the life of the power amplifier can be extended.

When the radial mechanical center position is determined as described above and there is no abnormality, the radial mechanical bearing is set with the determined radial mechanical center position as a target position.
(4) The excitation current of each electromagnet (17) (18) in (5) is controlled to
(2) is supported in a non-contact manner in the radial direction. Then, in such a state, the mechanical center position in the axial direction is obtained as in the related art. For example, the exciting current of the second axial electromagnet (16b) is set to 0, and the rotating body (2) is attracted to the limit position on the positive side of the Z axis by the first axial magnetic bearing (16a). Find the position in the axial direction. Next, the first axial electromagnet
At the same time as setting the exciting current of (16a) to 0, a constant exciting current is supplied to the second axial electromagnet (16b), and the rotating body (2) is moved to the Z-axis negative side limit by the second axial magnetic bearing (16b). Then, the position of the rotating body (2) in the Z-axis direction is obtained. Then, the midpoint of the position of the rotating body (2) in the Z-axis direction at both extreme positions is determined, and this is set as the mechanical center position in the axial direction.

Also in this case, the rotating body in the both extreme positions
An abnormality of the protection bearing (10) can be detected from the position in the Z-axis direction of (2). That is, when the difference between the positions of the rotating body (2) in the Z-axis direction at the extreme positions is smaller than a predetermined value, it is determined that the axial gap between the rotating body (2) and the protective bearing (10) is abnormally small. On the contrary, if the difference is larger than the predetermined value, it is determined that the protection bearing (10) has an abnormality such as excessive wear or damage.

When such an abnormality is detected, an alarm is issued and the magnetic bearing device is not activated.

If the mechanical center position in the axial direction is obtained as described above and there is no abnormality, the obtained mechanical center position in the axial direction is set as the target position, and the axial magnetic bearing is used.
The exciting current of each electromagnet (12) of (3) is controlled. Thereby, the rotating body (2) is supported in a non-contact manner at the mechanical center position.

In the case of the horizontal magnetic bearing device as in this embodiment, the gravitational force is applied to the rotating body (2) downward (toward the Y-axis negative side).
Act on. For this reason, in the process of obtaining the mechanical center position O2 in the radial direction, when the rotating body (2) is located at the lowermost position (the negative side of the Y axis), the rotating body (2) is
(10) The downward force acting on the Y-axis in (11) is the electromagnet (17d).
It becomes larger than the magnetic attraction force of (18d) by the amount of gravity, and the rotating body
In a state where (2) is located at the upper limit position (positive side of the Y-axis), the upward force of the rotating body (2) on the protective bearings (10) and (11) in the Y-axis direction is an electromagnet (17c) ( It becomes smaller by the gravity than the magnetic attraction force of 18c). Therefore, assuming that the exciting currents of the electromagnets (17d) (18d) (17c) (18c) in the above two states are equal, the rotating body (2) is located at the upper and lower extreme positions.
(10) There is a large difference in the force in the Y-axis direction exerted on (11), and as a result, a difference occurs in the amount of deformation of the protective bearings (10) and (11) in the radial direction. Therefore, an error occurs in the detection of the mechanical center position O2.

On the other hand, in the magnetic bearing device described above, the exciting current of the first Y-axis electromagnets (17c) (18c) is made larger than that of the remaining Y-axis electromagnets by the amount of gravity acting on the rotating body (2). Therefore, the above problem does not occur.

As described above, the rotating body (2) is a magnetic bearing (3) (4)
By driving the motor (7) in a state where it is supported in a non-contact manner at the mechanical center position by (5), the rotating body (2) can be rotated, and by stopping the driving of the motor (7), The rotation of the rotating body (2) can be stopped.
After the rotation of the rotating body (2) stops, the magnetic bearing (3)
(4) By stopping the driving of (5) and setting the exciting current of each electromagnet (16) (17) (18) to 0, the support by the magnetic bearings (3) (4) (5) is lost, The rotating body (2) is supported by protective bearings (10) (11). Also, when the rotating body (2) supported and supported by the protective bearings (10) and (11) is rotated in a non-contact manner, the mechanical center position obtained first is set as a target position. Control of the magnetic bearings (3), (4) and (5) is performed.

When the rotation of the rotating body (2) is stopped as described above and then supported by the protective bearings (10) and (11), the protective bearing
(10) There is no wear or damage on (11).

However, the rotating body (2) that is rotating at high speed is protected by the protective bearings (10) (11) due to a mistake in use or an abnormality in the control system.
May contact the inner rings (16b) and (17b). Also, the rotating body
If the power supply to the magnetic bearings (3), (4), (5) and the motor (7) is stopped due to a power failure during the rotation of (2), the rotating body (2) rotating at high speed is protected. The gears are received by the bearings (10) and (11), gradually decelerate, and eventually stop rotating. In such a case, the inner rings (16b) and (17b) of the protective bearings (10) and (11) come into contact with the rotating body (2) rotating at a high speed, rotate at a high speed, and furthermore, from the rotating body (2). Protective bearings (10) (1
The wear of 1) is large and may be damaged.

For this reason, in the above-described magnetic bearing device, the rotation is stopped, and the rotating body (2) supported by the protective bearings (10) and (11) is again rotated by the magnetic bearings (3), (4) and (5). Before supporting and rotating, abnormality detection of the protection bearings (10) and (11) is performed. This is almost the same as the abnormality detection after obtaining the radial mechanical center position described above. That is, first, the rotating body (2) is supported at the mechanical center position in the axial direction initially determined by the axial magnetic bearing (3), and the radial direction of the protective bearings (10) and (11) described above is used. Is detected. As a result, if there is no abnormality, the rotating body (2) is supported at the radial mechanical center position initially determined by the radial magnetic bearings (4) (5), and the protective bearing (10) described earlier is supported. (11)
Is detected in the axial direction of. Then, only when there is no abnormality in any case, the rotating body (2) is non-contactly supported at the mechanical center position first determined and rotated.

It is to be noted that the mechanical center position can be obtained again as described above, if necessary, even when the magnetic bearing device is not first started.

In the above embodiment, the inner rotor type magnetic bearing device has been described, but the present invention is also applicable to the outer rotor type magnetic bearing device.

Further, in the above embodiment, the horizontal magnetic bearing device is shown, but the present invention can be applied to a vertical magnetic bearing device. In the case of a vertical magnetic bearing device, the X axis and the Y axis as the radial control axes are arranged horizontally, and the Z axis as the axial control axis is arranged vertically. Therefore, when determining the mechanical center position in the radial direction, it is not necessary to consider the gravity acting on the rotating body, and it is not necessary to provide such a difference in the exciting current of the electromagnet of the radial magnetic bearing.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of a main part of a magnetic bearing device according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the same.

FIG. 3 is a cross-sectional view of the same.

FIG. 4 is an electrical configuration of the magnetic bearing device of FIG. 1;
It is a block diagram showing an example.

FIG. 6 is an explanatory diagram showing an example of a method for determining a radial mechanical center position of the magnetic bearing device.

FIG. 6 is a view showing the position of the center of the magnetic bearing device with respect to the sensor in the method of FIG. 5 and the position of the rotating body detected at each point in the moving process of moving the rotating body along the inner peripheral surface of the inner ring of the protective bearing; It is explanatory drawing which shows the radial position of the center, and the radial mechanical center position calculated | required from these.

[Explanation of symbols]

 (2) Rotating body (3) Axial magnetic bearing (4) (5) Radial magnetic bearing (6) Position detector (7) Electric motor (8) Electromagnet controller (10) (11) Protective bearing (10a) (11a ) Outer ring (10b) (11b) Inner ring (12) Axial position sensor (16a) (16b) Axial electromagnet (17a) (17b) (17c) (17d) Radial electromagnet (18a) (18b) (18c) (18d) Radial Electromagnet (19a) (19b) (19c) (19d) Radial position sensor (20a) (20b) (20c) (20d) Radial position sensor

Claims (1)

[Claims] 1. A plurality of sets of magnetic bearings having a plurality of electromagnets for supporting a rotating body in a non-contact manner in an axial direction and a radial direction, and a position having a plurality of position sensors for detecting the axial and radial positions of the rotating body. Detecting means, electromagnet control means for controlling the electromagnets of the respective magnetic bearings based on the result of position detection by the position detecting means, an electric motor for driving the rotating body to rotate, and axial and radial movement of the rotating body A magnetic bearing device comprising a protection bearing composed of a rolling bearing for mechanically supporting the rotating body at an extreme position of the movable range by regulating the range, wherein a rotation of the rotating body in a circumferential direction of a circumferential surface of the rotating body is stopped. Means for contacting one location with one location in the circumferential direction of the peripheral surface of the protection bearing facing the location and sequentially moving the contact point in the circumferential direction of the circumference of the protection bearing; Means for detecting the radial position of the center of the rotating body from the position detection results by the position detecting means at a number of points, and detecting the radial position of the center of the rotating body at each point in the moving process A magnetic bearing device comprising means for judging pass / fail of the protective bearing on the basis of the following.