JP2002242931A - Magnetic bearing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem in a conventional magnetic bearing apparatus using an inductance type sensor, in which flux for controlling the magnetic bearing apparatus leaks to the inductance type sensor to cause the degradation of a sensor signal, resulting in lowering position control accuracy of a rotational shaft. SOLUTION: The inductance type sensor 13a (13b) is provided to detect a position of the rotational shaft 3. The inductor type sensor 13a (13b) comprises: a sensor target ring 35a (35b) integrally fixed with the rotational shaft 3 through a non-magnetic member 37a (37b); and a sensor core 33a (33b) disposed oppositely to the sensor target ring 35a (35b).

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 having improved controllability in detecting the position of a rotating shaft and having good controllability.

[0002]

2. Description of the Related Art A magnetic bearing device includes a bearing rotor fixed to a rotating shaft, mutually orthogonal electromagnetic poles (controlling electromagnetic poles) arranged opposite to the bearing rotor, and an exciting coil provided on the electromagnetic poles. The magnetic flux is generated in the electromagnetic pole by the current flowing through the excitation coil, and a magnetic circuit is formed between the bearing rotor and the electromagnetic pole so that the magnetic flux forms a closed loop, thereby generating a magnetic attraction and holding the rotating shaft in a non-contact manner. ing. The magnetic bearing device is provided with a position detecting sensor for the rotating shaft, and the position detecting sensor is provided near the control electromagnetic pole to detect a displacement of the rotating shaft. The shaft position control device, based on the signal from the sensor, balances the magnetic attraction force of each control electromagnetic pole and flows the excitation coil of each control electromagnetic pole so as to maintain the rotating shaft at the target position. Controlling the current. Eddy current sensors, inductance sensors, optical sensors, and the like are used as position detection sensors. In particular, in a magnetic bearing device used in a corrosive working fluid atmosphere such as argon fluoride for excimer laser excitation, the control electromagnetic pole, the position detection sensor, and the motor stator are separated from the rotating shaft by a nonmagnetic shield partition. It has a structure to isolate. For this reason, since it is necessary to detect the displacement of the rotating shaft through a shield partition (for example, stainless steel, etc.), an eddy current sensor or an optical sensor cannot be used as the position detection sensor, and an inductance sensor is used. ing. A magnetic bearing device using an inductance type sensor is disclosed in, for example, US Patent No. 4180946.

[0003]

In order for the magnetic bearing device to maintain high position control accuracy with respect to the rotating shaft, the position detecting sensor needs to accurately detect the displacement of the rotating shaft. However, the above-mentioned US Patent No.4180946
In the magnetic bearing device disclosed in the above, a part of the control magnetic flux of the control electromagnetic pole may leak to the inductance type sensor and give noise to the sensor signal. As a result, the magnetic bearing device disclosed in the above-mentioned US Patent No. 4180946 has a problem that the sensor signal is deteriorated and it becomes difficult to perform good control of the position of the rotating shaft.

The present invention solves the inconvenience of the conventional example and suppresses a part of the control magnetic flux of the electromagnetic pole for radial control from leaking to the inductance type sensor in the magnetic bearing device using the inductance type sensor. Accordingly, it is an object of the present invention to provide a magnetic bearing device that can sufficiently reflect the displacement of the rotating shaft, does not deteriorate controllability of the rotating shaft position, and can perform good control.

[0005]

In order to solve the above-mentioned problems, according to the present invention, a magnetic circuit is formed with a gap between the rotating shaft and the rotating shaft in order to rotatably support the rotating shaft on a housing. In a magnetic bearing device having a magnetic circuit forming means and floating the rotating shaft by a magnetic force formed by the magnetic circuit, an inductance sensor is provided for detecting an axial position of the rotating shaft, and the inductance type sensor is provided. A magnetic bearing device comprising: a sensor, a sensor target ring integrally fixed to the rotation shaft via a non-magnetic material, and a sensor core provided to face the sensor target ring. provide.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing a magnetic bearing device according to a first embodiment of the present invention cut along an axis. FIG.
(A) is a cross-sectional view obtained by cutting along the A1-A1 (A2-A2) line in FIG. 1 and shows a cross-sectional structure of the radial magnetic bearing. FIG. 2B is a cross-sectional view of FIG.
FIG. 4 is a cross-sectional view obtained by cutting along the line 2-B2), showing a cross-sectional structure of the inductance sensor.

[0008] The magnetic bearing device of the first embodiment includes a rotating shaft 3
Radial magnetic bearings 7a, 7b and a thrust magnetic bearing 9 for supporting the rotating shaft 3 in a non-contact manner, the stationary portions being fixed to the housing 5 holding the rotating shaft 3, respectively;
Touchdown bearing 11 that supports rotating shaft 3 at the beginning of rotation
a, 11b, inductance type sensors 13a, 13b for detecting the axial position of the rotating shaft 3, and a high-frequency motor 15 for driving the rotating shaft 3.

The high-frequency motor 15 is installed at one end of the housing 5 that holds the rotating shaft 3.
5, an inductance sensor 13 a, a radial magnetic bearing 7 a, a touch-down bearing 11 a, and a thrust magnetic bearing 9 are arranged from the other end side of the rotating shaft 3, respectively. On the opposite end side, the inductance type sensor 13 is moved from the end face side of the housing 5 toward the high frequency motor 15 side.
b, radial magnetic bearing 7b, and touchdown bearing 1
1b are arranged respectively.

Here, a radial magnetic bearing 7a, an inductance type sensor 13a, a touch-down bearing 11a,
Radial magnetic bearing 7b, inductance sensor 13
b and the touch-down bearing 11b have the same structure and the same cross-sectional structure. Therefore, one of the reference numerals will be described with parentheses.

As shown in FIGS. 1 and 2A, a radial magnetic bearing 7a (7b) is a control electromagnetic pole (hereinafter referred to as a stator core) 17a (17b) formed of a laminated magnetic steel sheet fixed to a housing 5. ) And status core 17
a (17b), and a bearing rotor (hereinafter referred to as a rotor core) 19a (19b) made of a magnetic steel sheet laminate fixed to the outer periphery of the rotating shaft 3 so as to face the a (17b). The stator core 17a (17b) and the rotor core 19a (19
b) forms a radial magnetic circuit with a gap between them. Eight stator cores 17a (17b) are arranged at equal intervals in the circumferential direction. Stator core 17a
Around each of (17b), the control magnetic flux 23a
(23b) and the radial excitation coil 21a (21
b) is wound. Stator core 17a (17
In b), the surface facing the rotor core 19a (19b) is a magnetic pole surface.

As shown in FIG. 2A, the eight stator cores 17a (17b) are paired with one adjacent stator core 17a (17b) and function as one control magnetic pole. Therefore, the eight stator cores 17a (17
In b), four control poles are formed. From these four control magnetic poles, two control magnetic pole pairs facing each other with the rotating shaft
The control magnetic pole pairs are formed in pairs and are arranged along axes (X, Y axes) orthogonal to each other.

The control magnetic flux 23a (23b) generated by the radial excitation coil 21a (21b) wound on the stator core 17a (17b) passes through the control magnetic pole, the rotor core 19a (19b), and the gap between them. Respectively to form closed loops.

As shown in FIG. 1, the thrust magnetic bearing 9
Is a flange 25 provided on the rotating shaft 3 and extending in a disk shape in the radial direction, and an annular ring of a magnetic body having a U-shaped cross section which is concentrically installed facing both axial side surfaces of the flange 25. Body 2
7a, 27b and thrust exciting coils 29a, 2 wound around annular grooves of annular bodies 27a, 27b having a U-shaped cross section.
9b. Here, the thrust excitation coil 29
The annular members 27a and 27b including the support members 3a and 29b
It is fixed to the housing 5 via 1, 32.

As shown in FIGS. 1 and 2 (b), the inductance type sensor 13a (13b) includes a sensor core 33a (33b) made of a laminated magnetic steel sheet and a rotating shaft opposed to the sensor core 33a (33b). The non-magnetic body 37a (3b) is provided on the outer periphery of the
7b) and a sensor target ring 35a (35b) made of a laminated magnetic steel sheet. The sensor core 33a (33b) and the sensor target ring 35a (35b) form a sensing magnetic circuit via a gap between them. Eight sensor cores 33 a (33 b) are arranged at equal intervals in the circumferential direction and are fixed to the housing 5. Sensing coils 39a (39b) are wound around these sensor cores 33a (33b), respectively. The surface of the sensor core 33a (33b) facing the sensor target ring 35a (35b) is a magnetic pole surface.

As shown in FIG. 2B, the eight sensor cores 33a (33b) are paired with one adjacent sensor core 33a (33b) and function as one sensing magnetic pole. Therefore, the eight sensor cores 33a (3
In 3b), four sensing poles are formed. From these four sensing magnetic poles, two pairs of sensing magnetic pole pairs facing each other across the rotation axis 3 are formed, and these magnetic pole pairs are arranged along axes (X and Y axes) orthogonal to each other.

The sensing magnetic flux 41a (41b) generated by the sensing coil 39a (39b) wound around the sensor core 33a (33b) passes through the sensing magnetic pole, the sensor target ring 35a (35b), and the gap between them. A sensing magnetic circuit which forms a closed loop is formed through each of the sensing magnetic circuits.

The operation of the inductance type sensor 13a (13b) shown in FIGS. 1 and 2 will be described. The inductance type sensor 13a (13b) is provided with a sensing coil 39a (39) of the sensor core 33a (33b).
b) to supply a high-frequency current to the sensing magnetic flux 41a (4
1b), and a change in the gap between the sensor core 33a (33b) and the sensor target ring 35a (35b) is detected by a detection circuit (not shown) as a change in the inductance of the sensing magnetic circuit.

Next, the operation of the magnetic bearing device will be described. Eight upper and lower stator cores 17a (17b)
The rotating shaft 3 surrounded by
It is attracted by an appropriate magnetic force due to the control current flowing through the radial exciting coil 21a (21b) of (17b), and is rotatably supported in the radial direction without contact.

The flange portion 25 sandwiched between the pair of annular members 27 is attracted by an appropriate magnetic force by a control current flowing through the thrust exciting coils 29a, 29b in the annular members 27a, 27b. The rotatable member 3 is rotatably supported in a non-contact manner in the thrust direction. As a result, the magnetic bearing device can support the rotating shaft 3 in a non-contact manner.

Next, the position control of the rotating shaft 3 will be described. When the rotating shaft 3 is shifted from the target position in the radial direction, the amount of the shift is determined by the inductance sensor 13a
(13b) is detected by a detection circuit (not shown) as a change in inductance of the sensing magnetic circuit. In such cases,
The detection circuit sends a signal (for example, the sensor core 33a (33b)) corresponding to the amount of displacement of the rotating shaft 3 to a control device (not shown).
From the magnetic pole surface of the sensor target ring 35a (35
b) a signal corresponding to the distance to the outer peripheral surface).
The control device supplies a control current to the radial excitation coil 21a (21b) via an amplifier (not shown) so as to return the rotating shaft 3 shifted from the target position to the target position. The control device performs a so-called feedback control that controls the current flowing through the radial excitation coil 21a (21b) so that the displacement detected by the inductance sensor 13a (13b) becomes zero. As a result, the rotating shaft 3 is held at the target position.

In the axial position control in the thrust direction, the control current supplied to the thrust excitation coils 29a and 29b is appropriately adjusted by a thrust control device (not shown) based on the output of a thrust direction position sensor (not shown). Done.

Here, the inductance type sensor 13a
(13b) is provided near the radial magnetic bearing 7a (7b). Therefore, the control magnetic flux 23a (23
Part b) leaks to the sensing magnetic circuit via the rotor core 19a (19b) and the sensor target ring 35a (35b), and the sensing magnetic flux 41a (4
1b) is superimposed as noise. As a result, the quality of the sensor signal deteriorates, and the position detection accuracy of the rotating shaft 3 deteriorates.

In the magnetic bearing device according to the first embodiment of the present invention, the sensor cores 33a (33b)
Target ring 35a provided opposite to
(35b) is formed integrally with the rotating shaft 3 together with the nonmagnetic body 37a (37b) via the nonmagnetic body 37a (37b). Therefore, the non-magnetic material 37a (37
b) can prevent the control magnetic flux 23a (23b) from leaking to the sensing magnetic circuit. As a result,
The magnetic bearing device according to the first embodiment of the present invention can prevent deterioration of the sensor signal quality, and can maintain and improve the position detection accuracy of the rotating shaft 3. [Second Embodiment] FIG.
FIG. 4 is a longitudinal sectional view showing a homopolar type magnetic bearing device according to a second embodiment of the present invention, cut along an axis thereof. FIG. 4A is a diagram illustrating the C1-C1 (C2
FIG. 4 is a cross-sectional view obtained by cutting along a line −C2), showing a cross-sectional structure of the radial magnetic bearing. FIG. 4B is a cross-sectional view obtained by cutting along the line D1-D1 (D2-D2) in FIG. 3, and shows a cross-sectional structure of the inductance sensor. FIG. 5 is a longitudinal sectional view schematically showing a magnetic circuit of the radial magnetic bearing.

The magnetic bearing device according to the second embodiment includes a rotating shaft 5
1, a radial magnetic bearing 55a, 55b and a thrust magnetic bearing 57 for supporting the rotating shaft 51 in a non-contact manner, the stationary portions being fixed to a housing 53 holding the rotating shaft 51, respectively; , Touch-down bearings 59 a and 59 b for supporting the rotating shaft 51, inductance sensors 61 a and 61 b for detecting the axial position of the rotating shaft 51, and a high-frequency motor 62 for driving the rotating shaft 51.

The high-frequency motor 62 is installed at one end of a housing 53 that holds the rotating shaft 51, and moves from the high-frequency motor 62 toward the other end of the rotating shaft 51.
Inductance sensor 61a, radial magnetic bearing 5
5a, touchdown bearing 59a, thrust magnetic bearing 57
On the other hand, on the end side of the housing 53 opposite to the high-frequency motor 62, an inductance sensor 61b, a radial magnetic bearing 55b, and a touch panel are provided from the end face of the housing 53 toward the high-frequency motor 62. Down bearings 59b are arranged respectively.

Here, a radial magnetic bearing 55a, an inductance sensor 61a, a touch-down bearing 59a
And the radial magnetic bearing 55b, the inductance sensor 61b, and the touch-down bearing 59b have the same structure, and have the same cross-sectional structure.

As shown in FIGS. 3 and 4A, the radial magnetic bearing 55a (55b) has a pair of rotor cores 63a (6
3b) is fixed, and radial magnetic bearings 55a (55b) are radially outward of each rotor core 63a (63b).
Four stator cores 65a (65b), each composed of a magnetic steel sheet laminate forming part of b), are arranged at equal intervals in the circumferential direction and fixed to the housing 53. These four stator cores 65a (65b) form two sets of control magnetic pole pairs facing each other with the rotating shaft 51 interposed therebetween.
They are arranged along axes (X, Y axes) orthogonal to each other.

Further, the stator core 65a (65b)
Is a main body member 71a (71b) having an L-shaped cross section including a base 67a (67b) extending in the axial direction and a yoke 69a (69b) extending inward in the radial direction.
9a (69b), the yoke member 73a (73) having an I-shaped cross section and extending radially inward from the base 67a (67b).
b), and has a U-shape as a whole. Between the base 67a (67b) and the yoke member 73a (73b), a flat permanent magnet 75a for generating bias magnetic flux is provided.
(75b) is arranged. Yoke 69a (69
A radial excitation coil 77a (77b) for generating a control magnetic flux is wound around the b) and the yoke member 73a (73b). Rotor core 63a (63b) of yoke part 69a (69b) and yoke member 73a (73b)
Is a magnetic pole surface.

As shown in FIG. 3, the thrust magnetic bearing 57
Is a flange portion 81 provided on the rotating shaft 51 and extending in a disk shape in the radial direction, and an annular ring of magnetic material having a U-shaped cross section, which is installed concentrically opposite to both axial side surfaces of the flange portion 81. Bodies 83a and 83b and annular bodies 83a and 83b having a U-shaped cross section
Thrust excitation coil 85a wound around the annular groove of
85b. Here, the thrust excitation coil 85
The annular members 83a and 83b including the supporting members 8a and 85b
It is fixed to the housing 53 via 7, 89.

As shown in FIGS. 3 and 4B, the inductance type sensor 61a (61b) includes a sensor core 91a (91b) made of a magnetic steel sheet laminate and a rotating shaft opposed to the sensor core 91a (91b). Non-magnetic material 95a is provided on the outer peripheral portion of
(95b) and a sensor target ring 93a (93b) made of a laminated magnetic steel sheet. The sensor core 91a (91b) and the sensor target ring 93a (93b) form a sensing magnetic circuit via a gap between them. Eight sensor cores 91 a (91 b) are arranged at equal intervals in the circumferential direction and are fixed to the housing 53. Around these sensor cores 91a (91b), sensing coils 97a (97b) are wound. The surface of the sensor core 91a (91b) facing the sensor target ring 93a (93b) is a magnetic pole surface.

As shown in FIG. 4B, the eight sensor cores 91a (91b) form a pair with one adjacent sensor core 91a (91b) and function as one sensing magnetic pole. Therefore, the eight sensor cores 91a (9
In 1b), four sensing poles are formed. From these four sensing magnetic poles, two pairs of sensing magnetic pole pairs facing each other with the rotating shaft 51 interposed therebetween are formed.
They are arranged along axes (X, Y axes) orthogonal to each other.

The sensing magnetic flux 99a (99b) generated by the sensing coil 97a (97b) wound around the sensor core 91a (91b) passes through the sensing magnetic pole, the sensor target ring 93a (93b), and the gap between them. A sensing magnetic circuit which forms a closed loop is formed through each of these.

The operation of the inductance type sensor 61a (61b) shown in FIGS. 3 and 4 will be described. The inductance type sensor 61a (61b) is provided with a sensing coil 97a (97) of the sensor core 91a (91b).
b) to apply a high-frequency current to the sensing magnetic flux 99a (9
9b), and a change in the gap between the sensor core 91a (91b) and the sensor target ring 93a (93b) is detected by a detection circuit (not shown) as a change in the inductance of the sensing magnetic circuit.

Next, the operation of the magnetic bearing device will be described. The rotating shaft 51 surrounded by the four stator cores 65a (65b) is attracted by these stator cores 65a (65b) with an appropriate magnetic force, and is rotatably supported in a radial direction without contact.

The flange portion 81 sandwiched between the pair of annular bodies 83a, 83b is formed by these annular bodies 83a, 83b.
The rotating shaft 51 is attracted by an appropriate magnetic force due to a control current flowing through the thrust exciting coils 85a and 85b inside, and rotatably supports the rotating shaft 51 in the thrust direction without contact. As a result,
The magnetic bearing device can support the rotating shaft 51 in a non-contact manner.

Next, the position control of the rotating shaft 51 will be described. The rotating shaft 51 has a permanent magnet 75a in the radial direction.
When the magnetic attraction force from (75b) deviates from the balance position, the amount of the deviation is determined by the inductance sensor 61a.
(61b) detects a change in the inductance of the sensing magnetic circuit by a detection circuit (not shown). In such a case, the detection circuit supplies a signal (for example, the sensor core 91a (91
The sensor target ring 93a (9)
3b) is output. The control device supplies a control current to the radial excitation coil 77a (77b) via an amplifier (not shown) so that the rotating shaft 51 shifted from the target position is returned to the target position. In addition, the said control apparatus is an inductance type sensor 61a (61)
When the current position of the rotary shaft 51 matches the position where the attraction force of the permanent magnets 75a (75b) is balanced based on the deviation amount detected in b), the radial excitation coil 77a ( The so-called feedback control for controlling the current flowing through the block 77b) is performed. As a result, the rotating shaft 51 returns to the position where the attractive force of the permanent magnets 75a (75b) is balanced, and the control current in that state is
Becomes a very small current only for the differential operation for suppressing the minute fluctuation of.

The homopolar type magnetic bearing device is characterized in that the polarity of each magnetic pole is the same in the circumferential direction and there is no polarity alternation when the rotating shaft 51 rotates, so that bearing loss due to eddy current loss is small. Have. Further, the permanent magnets 75a (7
When 5b) is also used, there is no need to apply a bias magnetic flux required for control by the radial excitation coil 77a (77b), so that the control current is small. Further, the permanent magnet 75a (75b) may not be provided in the stator core 65a (65b), and the position control of the rotating shaft 51 in that case is the same as that of the first embodiment.

The axial position control in the thrust direction is performed by appropriately adjusting the control current supplied to the thrust excitation coils 85a and 85b based on the output of a thrust direction position sensor (not shown).

FIG. 5 shows a radial magnetic bearing 55a (55
b) is a longitudinal sectional view along the axial direction of the rotating shaft 51,
Stator core 65a (65b) made of magnetic steel sheet laminate
And a magnetic circuit formed between the permanent magnet 75a (75b), the radial excitation coil 77a (77b), and a pair of rotor cores 63a (63b) arranged on the outer periphery of the rotating shaft 51. . The arrow indicates the control magnetic flux 101 generated by the radial excitation coil 77a (77b).
a (101b) (the permanent magnet 75a (75
The bias magnetic flux from b) is omitted). The control magnetic flux 101a (101b) is applied to the stator core 65a (65b).
And a closed loop is formed with the rotor core 63a (63b) and a gap therebetween.

Here, the inductance type sensor 61a
(61b) is provided near the radial magnetic bearing 55a (55b). Therefore, the control magnetic flux 101a (1
01b) leaks to the sensing magnetic flux 99a (99b) via the rotor core 63a (63b) and the sensor target ring 93a (93b), and is superimposed on the sensing magnetic flux 99a (99b) as noise. As a result, the quality of the radial sensor signal deteriorates,
There is a possibility that the detection accuracy of the axis position 1 is deteriorated.

In the magnetic bearing device according to the second embodiment of the present invention, the sensor core 91a (91
sensor target ring 9 provided opposite to b)
3a (93b) is formed integrally with the rotating shaft 51 together with the non-magnetic material 95a (95b) via the non-magnetic material 95a (95b). Therefore, the non-magnetic material 95a
(95b) makes it possible to suppress the control magnetic flux 101a (101b) from leaking to the sensing magnetic flux 99a (99b). As a result, the magnetic bearing device according to the second embodiment of the present invention can prevent deterioration of sensor signal quality,
It is possible to maintain and improve the detection accuracy of the position of the rotating shaft 51.

The configuration and shape in the embodiment of the present invention are not limited to the above description, but can be appropriately modified and changed to those having a known structure within the scope of the present invention.

The material interposed when the sensor target ring is mounted on the rotating shaft is, for example, SUS30.
In addition to the austenitic non-magnetic material such as 3,304,316, etc., a material having a smaller magnetic permeability than the rotor core or the sensor target ring material can be used.

[0045]

As is clear from the above description, the magnetic bearing device of the present invention uses an inductance type sensor as a position detecting sensor of the rotating shaft, and is disposed on the outer peripheral portion of the rotating shaft facing the sensor core. The sensor target ring is formed integrally with the rotating shaft via a non-magnetic material. Therefore, the non-magnetic material can suppress the magnetic flux leakage from the stator core of the radial magnetic bearing. As a result, in the magnetic bearing device, the signal quality of the inductance sensor can be improved, and the accuracy of shaft position control of the rotating shaft can be maintained and improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating an internal structure of a magnetic bearing device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the apparatus shown in FIG. 2A is a cross-sectional view taken along the line A1-A1 (A2-A2) of FIG. 1, and FIG. 2B is a cross-sectional view taken along the line B1-B1 (B2-B2) of FIG. is there.

FIG. 3 is a longitudinal sectional view illustrating an internal structure of a homopolar type magnetic bearing device according to a second embodiment of the present invention.

4 is a cross-sectional view of the device shown in FIG. 4A is a cross-sectional view taken along the line C1-C1 (C2-C2) of FIG. 1, and FIG. 4B is a cross-sectional view taken along the line D1-D1 (D2-D2) of FIG. is there.

5 is a sectional view schematically showing a magnetic circuit of the radial magnetic bearing of the device shown in FIG.

[Explanation of symbols]

 3, 51 Rotary shaft 5, 53 Housing 7, 55 Radial magnetic bearing 9, 57 Thrust magnetic bearing 11, 59 Touchdown bearing 13, 61 Inductance sensor 15, 62 High frequency motor 17, 65 Stator core 19, 63 Rotor core 21, 77 Radial Excitation coil 23, 101 Control magnetic flux 25, 81 Flange part 27, 83 Toroid 29, 85 Thrust excitation coil 31, 32, 87, 89 Support member 33, 91 Sensor core 35, 93 Sensor target ring 37, 95 Non-magnetic Body 39,97 Sensing coil 41,99 Sensing magnetic flux 67 Base 69 Yoke 71 Body member 73 Yoke member 75 Permanent magnet

Continuation of the front page (72) Inventor Hiromasa Fukuyama 1-5-50 Kugenuma Shinmei, Fujisawa-shi, Kanagawa F-term in NSK Ltd. (reference) 2F063 AA02 BA03 BB05 BC04 BD01 DA01 DA05 DD05 GA05 GA33 GA42 GA47 GA50 KA01 KA04 ZA04 3J102 AA01 CA11 DA09 DB01 DB05

Claims (1)

[Claims] 1. A magnetic circuit forming means for forming a magnetic circuit through a gap between the rotating shaft and the rotating shaft so as to rotatably support the rotating shaft in the housing, and a magnetic force formed by the magnetic circuit. In the magnetic bearing device for levitating the rotating shaft, an inductance sensor is provided to detect an axial position of the rotating shaft, and the inductance sensor is integrally formed on the rotating shaft via a non-magnetic material. A magnetic bearing device comprising: a fixed sensor target ring; and a sensor core provided to face the sensor target ring.