JP2005076792A - Magnetic bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic bearing device capable of improving the sensitivity of a displacement sensor, with respect to the magnetic bearing device wherein an electromagnet and the displacement sensor share magnetic poles. <P>SOLUTION: Radial magnetic pole parts 43 are composed of rectangular iron core pieces 32, 33 respectively having grooves 37, 38 on their axial central parts. The iron core piece 32 is divided into a magnetic pole part 39 and a magnetic pole part 40 by the groove 37, similarly the iron core piece 33 is divided into the magnetic pole part 41 and the magnetic pole part 42 by the groove 38. Radial electromagnetic coils 34a, 34b are respectively wound on the iron core pieces 32, 33. A radial sensor coil 36a is wound over the magnetic pole part 39 and the magnetic pole part 41, and similarly a radial sensor coil 36b is wound over the magnetic pole part 40 and the magnetic pole part 42. The radial sensor coils 36a, 36b are mounted on a radial magnetic pole part 43 through a shield plate 35 with respect to the radial electromagnetic coils 34a, 34b. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a magnetic bearing device that supports a rotating shaft in a non-contact manner by magnetically levitating.

As an apparatus in which a rotating shaft is supported by a magnetic bearing device, for example, there is a molecular pump installed in a clean room of a semiconductor manufacturing apparatus.
The magnetic bearing device used in such a bearing device such as a molecular pump is provided with a sensor for detecting the displacement of the rotating shaft, and based on the position information of the rotating shaft detected by this sensor. Control is in progress.
Generally, in the molecular pump as described above, an electromagnetic displacement sensor is used. The electromagnetic displacement sensor detects the displacement of the rotating shaft by measuring the change in the inductance of the coil wound around the magnetic pole.
Conventionally, the magnetic pole for the sensor constituting the displacement sensor has been provided separately from the magnetic pole of the electromagnet used for levitating the rotating shaft.

In a magnetic bearing device in which such a displacement sensor and an electromagnet are configured using dedicated magnetic poles, the following problems may occur.
Since dedicated magnetic poles have to be arranged, it is necessary to secure a space for arranging the magnetic poles, which makes it difficult to reduce the size.
Therefore, even if the length of the rotating shaft is reduced, a restriction is imposed, so that it is difficult to increase the natural frequency of the rotating shaft, and the rotating shaft cannot be rotated at high speed.
Furthermore, since the displacement sensor and the electromagnet cannot be arranged at the same position, there is a possibility that the detection point of the position of the rotating shaft and the point of action of the magnetic force by the electromagnet will be displaced, which may hinder the stable floating of the rotating shaft. It was.

In order to eliminate such problems, a magnetic bearing device in which a displacement sensor is formed on a magnetic pole of an electromagnet is disclosed in the following patent document.
Japanese Patent No. 3315428

Patent Document 1 proposes a radial magnetic bearing device in which a part of a magnetic pole of an electromagnet is shared with a magnetic pole of a displacement sensor.
Specifically, the displacement sensor is configured on the magnetic pole of the electromagnet by winding a coil of the displacement sensor in a groove provided in parallel to both ends of the rectangular magnetic pole of the electromagnet. Thus, by sharing a part of the magnetic pole of the electromagnet, it is possible to configure the displacement sensor without providing a dedicated magnetic pole. Thereby, since the detection point of the position of a rotating shaft and the action point of the magnetic force by an electromagnet can be made into the same position, the magnetic levitation stability of a rotating shaft can be ensured.

However, in the magnetic bearing device proposed in Patent Document 1, a part of both ends of the magnetic pole of the electromagnet is used as the magnetic pole of the coil of the displacement sensor, so that a sufficient magnetic pole area cannot be secured. It was.
In order to increase the sensor sensitivity in such a displacement sensor having a narrow magnetic pole area, it is necessary to increase the number of turns of the coil of the displacement sensor. However, the number of turns of the coil has been limited by the structure of the magnetic bearing device.
In addition, when the magnetic pole area of the displacement sensor is small, the magnetic pole, which is a magnetic material, easily reaches a magnetic saturation state, and it is difficult to improve the sensitivity of the sensor.

  Accordingly, an object of the present invention is to provide a magnetic bearing device that can improve the sensitivity of the displacement sensor in a magnetic bearing device that shares the magnetic poles of the electromagnet and the displacement sensor.

According to the first aspect of the present invention, there is provided a magnetic bearing device that supports a rotating shaft in a non-contact manner by magnetically levitating using a magnetic force, the electromagnetic coil constituting an electromagnet that generates magnetic force, and the electromagnetic coil together A displacement sensor that constitutes the electromagnet and has an electromagnetic pole around which the electromagnetic coil is wound and has at least two magnetic pole portions, and a displacement sensor that is wound around the magnetic pole portion and detects a displacement of the rotating shaft. And achieving the object by making the area of the magnetic pole end face of the electromagnetic pole wound with the electromagnetic coil equal to the area of the magnetic pole end face of the magnetic pole portion wound with the displacement sensor coil. To do.
According to a second aspect of the present invention, there is provided a magnetic bearing device for supporting the rotating shaft in the axial direction according to the first aspect of the invention, wherein the disk-shaped armature is fixed perpendicularly to the rotating shaft. The electromagnetic pole is provided with an annular groove and a plurality of radial grooves extending in a radial direction provided on a surface facing the armature, and the magnetic pole portion is disposed between the adjacent radiation grooves. The object is achieved by forming, winding the electromagnetic coil along the annular groove, and disposing a part of the displacement sensor coil in the radiation groove.
According to a third aspect of the present invention, in the first aspect of the present invention, the magnetic bearing device supports the rotating shaft in a radial direction, and the electromagnetic pole is provided with a groove extending in a circumferential direction or an axial direction. The object is achieved by forming the magnetic pole portions on both sides of the groove and disposing a part of the displacement sensor coil in the groove.
According to a fourth aspect of the present invention, in the third aspect of the present invention, the electromagnet includes a pair of the electromagnetic poles having different electromagnetic polarities, and the displacement sensor coils are each of the electromagnetic poles having different electromagnetic polarities. The object is achieved by winding over the two magnetic pole portions provided on the surface.
According to a fifth aspect of the present invention, in the first aspect of the present invention, the magnetic bearing device supports the rotating shaft in the radial direction, and is nonmagnetic disposed between the magnetic pole portions adjacent in the axial direction. The magnetic poles comprising body members, the electromagnet having a pair of electromagnetic poles having different electromagnetic polarities, and the displacement sensor coils being adjacent to each other in the circumferential direction provided on the electromagnetic poles having different electromagnetic polarities The above-mentioned object is achieved by winding each of the parts so as to have different sensor magnetic polarities.
According to a sixth aspect of the invention, in the fifth aspect of the invention, the electromagnetic sensor includes an electromagnetic shielding member disposed on a side surface of the magnetic pole portion so as to cover the displacement sensor coil. The object is achieved by winding around the electromagnetic pole through a shielding member.
According to the invention described in claim 7, in the invention described in any one of claims 1 to 6, at least two of the electromagnets are provided, and the displacement sensor is provided for each of the electromagnets. The object is achieved by connecting the displacement sensor coils constituting the same displacement sensor in parallel.
According to an eighth aspect of the present invention, in any one of the first to seventh aspects, the rotating shaft side end of the magnetic pole portion or the electromagnetic coil and the sensor coil The object is achieved by providing a shield member disposed at least in the middle and whose outer edge is short-circuited.

  According to the present invention, the sensitivity of the displacement sensor can be improved by sufficiently securing the area of the magnetic pole surface used for the displacement sensor in the magnetic bearing device that shares the magnetic poles of the electromagnet and the displacement sensor.

Hereinafter, preferred embodiments of the magnetic bearing device of the present invention will be described in detail with reference to FIGS. 1 to 9.
The magnetic bearing device shown in the present embodiment is used, for example, as a bearing device for a rotary shaft of a molecular pump used for clean room exhaust processing. A control system called a 5-axis control type or a 3-axis control type is adopted for the rotation axis of such a molecular pump.

FIG. 1 is a diagram showing a configuration of a molecular pump 1 using a magnetic bearing device according to the present embodiment.
Here, the structure of the molecular pump 1 will be described as an example of the structure of the 5-axis control type magnetic bearing device. In the present embodiment, as an example of the molecular pump 1, a so-called composite wing type molecular pump including a turbo molecular pump unit and a thread groove type pump unit will be described as an example.

The casing 2 forming the exterior body of the molecular pump 1 has a substantially cylindrical shape, and constitutes a housing of the molecular pump 1 together with a disc-shaped base 3 provided at the bottom of the casing 2. In the casing 2, a structure that allows the molecular pump 1 to perform an exhaust function is housed.
These structures that exhibit the exhaust function are roughly composed of a rotor portion 4 that is rotatably supported and a stator portion that is fixed to the casing 2.
Further, when viewed from the type of pump, the intake port 5 side is constituted by a turbo molecular pump part, and the exhaust port 6 side is constituted by a thread groove type pump part.

The rotor unit 4 is a rotating member disposed on a shaft 7 rotated by a motor, and includes a rotor blade 8 provided on the intake port 5 side (turbo molecular pump unit) and an exhaust port 6 side (screw groove pump). The cylindrical member 9 provided in the part), the shaft 7 and the like.
The shaft 7 is a columnar member that constitutes the rotation axis, that is, the axis of the rotor portion 4, and a member composed of the rotor blade 8 and the cylindrical member 9 is attached to the upper end portion thereof by a bolt or the like.

In the middle of the shaft 7 in the axial direction, a permanent magnet is fixed to the outer peripheral surface, and the rotor of the motor unit 10 is configured. A magnetic pole formed by the permanent magnet on the outer periphery of the shaft 7 is an N pole over the half circumference of the outer peripheral surface and an S pole over the remaining half circumference.
Further, on the intake port 5 side and the exhaust port 6 side with respect to the motor portion 10 of the shaft 7, radial magnetic bearing devices 11 and 12 for supporting the shaft 7 in the radial direction (radial direction), the shaft 7. An axial magnetic bearing device 13 for supporting the shaft 7 in the axial direction (axial direction) is provided at the lower end of the shaft.

A stator portion is formed on the inner peripheral side of the casing 2. This stator portion is composed of a stator blade 14 provided on the intake port 5 side (turbo molecular pump portion), a thread groove spacer 18 provided on the exhaust port 6 side (screw groove pump), and the like.
In the turbo molecular pump section, the stator blades 14 are formed in a plurality of stages alternately with the rotor blades 8 in the axial direction.
The stator blades 14 of each stage are separated from each other by a cylindrical spacer 15.

The thread groove spacer 18 is a cylindrical member having a spiral groove 16 formed on the inner peripheral surface. The inner peripheral surface of the thread groove spacer faces the outer peripheral surface of the cylindrical member 9 with a predetermined clearance (gap) therebetween. The direction of the spiral groove 16 formed in the thread groove spacer 18 is the direction toward the exhaust port 6 when the gas is transported in the spiral groove 16 in the rotational direction of the rotor portion 4.
The depth of the spiral groove 16 becomes shallower as it approaches the exhaust port 6, and the gas transported through the spiral groove 16 is compressed as it approaches the exhaust port 6.
These stator portions are made of a metal such as stainless steel or aluminum alloy.

The base 3 is a member having a disk shape, and a stator column 17 having a cylindrical shape concentric with the rotation axis of the rotor is attached in the direction of the intake port 5 at the center in the radial direction.
The stator column 17 supports the motor unit 10 and the radial magnetic bearing devices 11 and 12.
In the motor unit 10, a stator coil having a predetermined number of poles is arranged at equal intervals on the inner peripheral side of the stator coil so that a rotating magnetic field can be generated around the magnetic pole formed on the shaft 7.

The radial magnetic bearing devices 11 and 12 are composed of control magnetic pole portions disposed every 90 degrees around the rotation axis. The radial magnetic bearing devices 11 and 12 magnetically levitate the shaft 7 in the radial direction by attracting the shaft 7 with a magnetic field generated by these coils. Details of the radial magnetic bearing devices 11 and 12 will be described later.
An axial magnetic bearing device 13 is formed at the bottom of the stator column 17. The axial magnetic bearing device 13 is composed of a disk-shaped armature 19 projecting vertically from the shaft 7 and coils disposed above and below the armature 19. The magnetic field generated by these coils attracts the armature 19 so that the shaft 7 is magnetically levitated in the axial direction.

As described above, the 5-axis control type magnetic bearing device includes the axial magnetic bearing device 13 that controls the magnetic levitation in the axial direction and the radial magnetic bearing devices 11 and 12 that control the magnetic levitation in the radial direction. Is provided.
Therefore, the magnetic bearing device according to the present embodiment will be described separately for the axial magnetic bearing device 13 and the radial magnetic bearing devices 11 and 12.

As shown in FIG. 1, the axial magnetic bearing device 13 is a device for levitating the shaft 7 in the axial direction via an armature 19 provided perpendicular to the shaft 7.
The axial magnetic bearing device 13 is constituted by a pair of axial magnetic bearing portions 20 in which axial electromagnets are formed.
The armature 19 receives an attractive force attracted in the direction of each axial magnetic bearing portion 20 by the magnetic force of the axial electromagnet of the axial magnetic bearing portion 20.
The axial magnetic bearing device 13 supports the shaft 7 in a non-contact state in the axial direction via the armature 19 by controlling these attractive forces.

FIG. 2 is a diagram showing the configuration of the axial magnetic bearing portion 20 that constitutes the axial magnetic bearing device 13.
The axial magnetic bearing portion 20 includes an axial electromagnet portion 21 and an axial sensor portion 22.
The axial electromagnet portion 21 constitutes an electromagnet that generates a magnetic force for applying an attractive force to the armature 19.

The axial direction sensor unit 22 constitutes an axial direction sensor that detects the displacement of the armature 19, that is, the axial displacement of the shaft 7.
The axial sensor unit 22 recognizes the displacement of the armature 19 by detecting the distance (gap length) between the armature 19 and the axial magnetic bearing unit 20.
The axial sensor unit 22 measures the amount of displacement of the armature 19 using an inductance type displacement sensor.
The inductance-type displacement sensor is a displacement sensor that detects a displacement from a change in inductance by using a characteristic that the inductance of a coil wound around the magnetic pole changes in conjunction with the air gap of the magnetic pole.
In the axial magnetic bearing device 13, the axial sensor portions 22 of the pair of axial magnetic bearing portions 20 are arranged so as to face each other.

The axial electromagnet portion 21 includes a first axial electromagnetic yoke 23 and an axial electromagnetic coil 24.
The first axial electromagnetic yoke 23 constitutes an iron core that forms an electromagnet of the axial electromagnet portion 21, that is, an electromagnetic pole.
The first axial electromagnetic yoke 23 includes a disc portion 231 in which concentric circular holes are formed, a cylindrical outer edge portion 232 having a peripheral portion of the disc portion 231 as a bottom surface, and a circle formed in the disc portion 231. It consists of a cylindrical inner edge 233 with the hole as the bottom.

When the disk portion 231 is a bottom surface, the inner edge portion 233 is higher than the outer edge portion 232 by the height of a second axial electromagnetic yoke 25 described later.
The first axial electromagnetic yoke 23 has a U-shaped groove 234 formed by a disk portion 231, an outer edge portion 232, and an inner edge portion 233. That is, the groove 234 is an annular groove provided so that the open end portion faces the armature 19.
On the end face of the inner edge 233, four grooves 235a to 235d extending in the radial direction are formed at intervals of 90 degrees.
The end portions of the inner edge portion 233 are divided into four magnetic pole portions 236a to 236d by the grooves 235a to 235d.

The axial electromagnetic coil 24 is a winding wound several turns around the inner edge 233 as an axis. The axial electromagnetic coil 24 is disposed inside the groove 234.
Accordingly, the maximum outer diameter dimension of the axial electromagnetic coil 24 when rolled up is at least smaller than the inner diameter dimension of the outer edge portion 232.
When the axial electromagnetic coil 24 is energized, a current flows inside the axial electromagnetic coil 24 and a magnetic flux 27 is generated.
Then, the first axial electromagnetic yoke 23 functions as a magnetic pole of the electromagnet, and a magnetic force is generated in the axial electromagnet portion 21. This magnetic force causes an attractive force to act on the armature 19.

The axial sensor unit 22 includes a second axial electromagnetic yoke 25 and an axial sensor coil 26.
Similar to the first axial electromagnetic yoke 23, the second axial electromagnetic yoke 25 constitutes an iron core that forms an electromagnet of the axial electromagnet portion 21, that is, an electromagnetic pole. Accordingly, the second axial electromagnetic yoke 25 functions as a magnetic pole of an electromagnet, like the first axial electromagnetic yoke 23, when the axial electromagnetic coil 24 is energized.
The second axial electromagnetic yoke 25 includes a disc portion 251 in which concentric circular holes are formed, a cylindrical outer edge portion 252 having a peripheral portion of the disc portion 251 as a bottom surface, and a circle formed in the disc portion 251. It consists of a cylindrical inner edge 253 with the hole as the bottom.
The disk portion 251 has a shielding function for reducing the influence of the leakage magnetic flux of the axial electromagnetic coil 24 on the axial sensor coil 26.

The first axial electromagnetic yoke 23 and the second axial electromagnetic yoke 25 are combined so that the inner edge portion 233 of the first axial electromagnetic yoke 23 is fitted into the hollow portion of the inner edge portion 253.
Therefore, the inner diameter of the inner edge portion 253 of the second axial electromagnetic yoke 25 is at least larger than the outer diameter of the inner edge portion 233 of the first axial electromagnetic yoke 23.
The height of the inner edge portion 253 and the outer edge portion 252 is the height of the end face of the inner edge portion 233 of the first axial electromagnetic yoke 23 when the first axial electromagnetic yoke 23 and the second axial electromagnetic yoke 25 are combined. Are equal.

In the second axial electromagnetic yoke 25, a disk portion 251, an outer edge portion 252, and an inner edge portion 253 form a U-shaped groove 254.
On the end surface of the inner edge 253, four grooves 255a to 255d extending in the radial direction are provided at intervals of 90 degrees.
The end portions of the inner edge portion 253 are divided into four magnetic pole portions 256a to 256d by the grooves 255a to 255d.
When the first axial electromagnetic yoke 23 and the second axial electromagnetic yoke 25 are combined, the grooves 255a to 255d are arranged on the radial extension lines of the grooves 235a to d. Here, a groove 235a is provided on the extension of the groove 255a, a groove 235b is provided on the extension of the groove 255b, a groove 235c is provided on the extension of the groove 255c, and a groove 235d is provided on the extension of the groove 255d.

The axial sensor coil 26 includes coils 261a to 261d.
The coil 261a is a winding wound around the magnetic pole part 236a and the magnetic pole part 256a several turns around the magnetic pole part 236a and the magnetic pole part 256a.
The coil 261a is wound so as to be disposed on the magnetic pole portion 236a and grooves 235a, 235b, 255a, 255b formed on the side surfaces of the magnetic pole portion 256a, the inner side surface of the magnetic pole portion 236a, and the outer side surface of the magnetic pole portion 256a. Yes.
The coils 261b to 261d have the same configuration as the coil 261a.
Note that the polarities described in the coils 261a to 261d in the drawing are examples of polarities generated at the ends of the magnetic pole portions around which the coils 261a to 261d are wound.

The coils 261a to 261d of the axial sensor coil 26 are all connected in parallel.
The axial sensor coil 26 generates a magnetic flux 28 when energized with a high frequency current, and constitutes an axial displacement sensor together with the second axial electromagnetic yoke 25.
When a high frequency current flows through the coils 261a to 261d, the magnetic pole portions 236a to 236d and the magnetic pole portions 256a to 256d act as magnetic poles of the axial displacement sensor. That is, a magnetic pole is formed in each magnetic pole part 236a-d and the magnetic pole part 256a. Then, the magnetic flux 28 is generated in each of the magnetic pole portions 236a to 236d and the magnetic pole portion 256a.
The inductance type axial displacement sensor detects the displacement of the armature 19, that is, the axial displacement of the shaft 7 by detecting the amount of change of the magnetic flux 28.

  In the present embodiment, the axial sensor coil 26 is arranged in a portion divided into four by the grooves 235a to d and the grooves 255a to 255d. The axial sensor coil 26 is displaced by arranging the axial sensor coil 26 in the magnetic pole portion divided into two sections, six sections, etc., that is, even sections, within a range in which a magnetic path can be formed by a pair of coils. You may make it comprise a sensor coil.

Next, a modified example of the axial magnetic bearing portion 20 will be described.
FIG. 3 is a view showing a modification of the axial magnetic bearing portion 20.
In addition, the same code | symbol is used for the same part (overlapping part) as embodiment shown in FIG. 2 mentioned above, and detailed description is abbreviate | omitted.
Four grooves 237a to 237d extending in the radial direction are formed at intervals of 90 degrees in the outer edge portion 232 ′ and the inner edge portion 233 of the first axial electromagnetic yoke 23 ′. By the grooves 237a to 237d, the distal end portions of the outer edge portion 232 and the inner edge portion 233 are divided into four magnetic pole portions 238a to 238d.
Then, the coil 261a is wound around the two magnetic pole portions of the magnetic pole portion 238a and the magnetic pole portion 236a, that is, across the magnetic pole portion 238a and the magnetic pole portion 236a. The coils 261b to 261d are configured similarly to the coil 261a.

Thus, the axial sensor coil 26 is not provided without the second axial electromagnetic yoke 25 by winding the axial sensor coil 26 directly around the inner edge portion 233 and the outer edge portion 232 ′ of the first axial electromagnetic yoke 23 ′. Can be arranged.
In this case, a shield member 29 is disposed between the axial electromagnetic coil 24 and the axial sensor coil 26 in order to suppress the influence of the leakage magnetic flux of the axial electromagnetic coil 24.
As shown in FIG. 3, the shield member 29 includes an annular shield part 291 and a shield part 292.
The shield part 291 is disposed along the outer edge part 232 ′ of the first axial electromagnetic yoke 23 ′. Further, the shield part 291 is provided with rectangular shielding parts 291a to 291d extending from the inner periphery of the shield part 291 toward the center along the grooves 237a to 237d.
The shield part 292 is disposed along the inner periphery of the inner edge part 233 of the first axial electromagnetic yoke 23 '.
As the shield member 29, for example, a metal plate such as copper, a metal stay, a member obtained by solidifying metal powder, or the like is preferably used.
In this way, by forming the shield member 29 into an annular (short-circuited) shield part 291 and a shield part 292, interlinkage magnetic flux (leakage magnetic flux or the like) can be consumed as a short-circuit current.

The conventional axial sensor has been arranged near the lower end of the shaft 7.
Specifically, the axial sensor is composed of a target made of a magnetic material such as ferrite attached to the lower end of the shaft 7 and a sensor coil provided at a position facing the target on the base 3 side. And the displacement of the axial direction of the shaft 7 was detected by detecting the change of the inductance in a target and a sensor coil.
The relationship between the change amount of the inductance of the sensor and the change amount of the air gap is non-linear, and has a characteristic that the change amount of the inductance increases rapidly as the air gap becomes smaller.
Therefore, in order to obtain appropriate sensitivity, it is necessary to adjust the air gap with high accuracy in a specific range. In order to realize this, it is difficult to reduce costs because it is required to use high-precision parts, improve adjustment accuracy, and the like.
Therefore, in the present embodiment, the two sensor coils are arranged to face each other so as to sandwich the armature 19. In the sensor coil arranged in this manner, by using a differential configuration similar to the conventional one, the non-linear characteristic of the relationship between the change amount of the sensor inductance and the change amount of the air gap is relaxed and approaches the linear characteristic. Therefore, it is not necessary to adjust the air gap with high accuracy, so that it is not necessary to adjust the position of the sensor.

Further, according to the present embodiment, the displacement of the rotor shaft, specifically the displacement of the armature 19 can be detected at a position close to the object, so that the detection sensitivity of the displacement sensor can be improved. it can.
Furthermore, by arranging the axial sensor coil 26 in the first axial electromagnetic yoke 23 or the second axial electromagnetic yoke 25 in this way, the magnetic pole for acting the axial electromagnet can be shared with the axial sensor.
As a result, the detection point of the object by the axial sensor and the action point of the electromagnet of the axial magnetic bearing can be matched, so that the control accuracy of the axial magnetic bearing device 13 can be improved.

Next, details of the radial magnetic bearing devices 11 and 12 will be described.
FIG. 4 is a cross-sectional view of the radial magnetic bearing devices 11 and 12 according to the present embodiment. Since the radial magnetic bearing device 11 and the radial magnetic bearing device 12 have the same structure, the structure of the radial magnetic bearing device 11 will be described here.
In the radial magnetic bearing device 11, four control magnetic pole portions 31a to 31d are arranged at intervals of 90 degrees around the rotation axis.
Each of the control magnetic pole portions 31 a to 31 d includes a core pair in which a core piece 32 and a core piece 33 provided on the inner peripheral wall of a cylindrical annular core 30 concentric with the shaft 7 are paired. The annular iron core 30, the iron core piece 32, and the iron core piece 33 are made of a magnetic member.
As the magnetic member, for example, a laminated silicon steel plate or ferrite is used.

The iron core piece 32 and the iron core piece 33 are electromagnetic poles, and a radial electromagnetic coil 34 is wound thereon. When the radial electromagnetic coil 34 is energized, the iron core piece 32 and the iron core piece 33 are magnetized to have different polarities, and act as magnetic poles of an electromagnet that applies an attractive force for attracting the shaft 7.
A radial sensor coil 36 is wound around the core pieces 32 and 33 at both ends of the core pieces 32 and 33. Then, when the radial sensor coil 36 is energized, the iron core piece 32 and the iron core piece 33 also function as a radial displacement sensor that detects the displacement of the shaft 7.
A shield plate 35 is provided between the radial electromagnetic coil 34 and the radial sensor coil 36.
Details of the control magnetic pole portions 31a to 31d will be described later.

The shaft 7 is attracted in the positive direction in the X-axis direction by the control magnetic pole portion 31b, in the negative direction in the X-axis by the control magnetic pole portion 31d, and further, in the positive direction in the Y-axis direction by the control magnetic pole portion 31a. Is sucked in the negative direction of the Y-axis.
Thus, the shaft 7 is supported in a non-contact state in the radial direction by controlling the magnetic force of the electromagnet so that the gap length (gap distance) between the shaft 7 and the control magnetic pole portions 31a to 31d is uniform.
Note that the displacement of the gap length between the shaft 7 and the control magnetic pole portions 31a to 31d is detected by a radial displacement sensor.

FIG. 5 is a diagram showing the configuration of the control magnetic pole portions 31a to 31d.
Since the control magnetic pole portions 31a to 31d all have the same structure, the structure of the control magnetic pole portion 31a will be described here.
The control magnetic pole portion 31 a is configured by a radial magnetic pole portion 43, a radial electromagnetic coil 34, a shield plate 35, and a radial sensor coil 36.
A rectangular iron core piece 32 and an iron core piece 33 are formed adjacent to the radial magnetic pole portion 43 so as to protrude from the inner peripheral wall of the annular iron core 30 in the direction of the shaft 7.
The iron core piece 32 and the iron core piece 33 are formed of a rectangular magnetic member extending in the axial direction.

The iron core piece 32 and the iron core piece 33 are each provided with a single groove 37, 38 extending in the circumferential direction at the center in the axial direction.
The core piece 32 is divided into a magnetic pole part 39 and a magnetic pole part 40 by the groove 37. Similarly, the iron core piece 33 is divided into a magnetic pole part 41 and a magnetic pole part 42 by the groove 38.
In addition, let the surface which opposes the shaft 7 of the front-end | tip part of the magnetic pole parts 39-42 be magnetic pole surface 39a, 40a, 41a, 42a.

The radial electromagnetic coil 34 includes a coil 34a and a coil 34b.
The coil 34a is wound several turns around the core piece 32 as an axis. The coil 34b is wound several turns around the iron core piece 33 as an axis.
The coil 34a and the coil 34b are connected in parallel.
In this way, the radial electromagnetic coil 34 is disposed in the radial magnetic pole portion 43.
When the coil 34a and the coil 34b are energized, the iron core piece 32 and the iron core piece 33 are magnetized to have magnetic poles having different polarities, and act as magnetic poles of an electromagnet that applies an attractive force for attracting the shaft 7.

The shield plate 35 is an electromagnetic shielding plate for shielding (blocking) the leakage magnetic flux of the radial electromagnetic coil 34. By providing the shield plate 35, the influence of the magnetic flux generated from the radial electromagnetic coil 34 on other portions can be reduced.
The shield plate 35 is formed of a conductor plate or a conductor net, and is grounded to a ground level potential of a control circuit provided in the magnetic bearing device.
The shield plate 35 is configured by a continuous annular member that is formed so as to surround the iron core pieces 32 and 33 and has no break at the edge. That is, the outer edge portion is constituted by a shorted member.
That is, the shield plate 35 is configured to constitute a short ring (short-circuit ring) so that the interlinking magnetic flux (leakage magnetic flux or the like) can be consumed as a short-circuit current.

The inner edge of the shield plate 35 has a shape along the side surfaces of the iron core pieces 32 and 33. Further, the shield plate 35 is provided with rectangular shielding portions 35a and 35b extending in the center direction from the outer edge portion along the gap between the iron core piece 32 and the iron core piece 33.
Thus, by providing the shielding portions 35a and 35b, the magnetic flux leaking from between the iron core piece 32 and the iron core piece 33 can be appropriately shielded.
The shield plate 35 is preferably formed of, for example, a copper foil or a copper plate. When shielding a high-strength magnetic flux, several of these members are used.

The radial sensor coil 36 includes a coil 36a and a coil 36b.
The coil 36 a is wound several turns around the magnetic pole part 39 and the magnetic pole part 41.
The coil 36 b is wound several turns around the magnetic pole part 40 and the magnetic pole part 42, with the two magnetic pole parts of the magnetic pole part 40 and the magnetic pole part 42 as axes. The coils 36 a and 36 b are wound so as to be disposed in the grooves 37 and 38.
Therefore, both windings of the coil 36a and the coil 36b are disposed on the side surfaces of the magnetic pole portions 39 to 42 using the common grooves 37 and 38, respectively.
The coil 36a and the coil 36b are connected in parallel.

The coils 36a and 36b are disposed at the tip portions of the magnetic pole portions 39 to 42. The arrangement portion of the radial sensor coil 36 and the arrangement portion of the radial electromagnetic coil 34 on the magnetic pole portions 39 to 42 are arranged so as not to overlap.
The shield plate 35 is disposed between the radial sensor coil 36 and the radial electromagnetic coil 34.

In this way, the radial sensor coil 36 is disposed on the radial magnetic pole portion 43 where the radial electromagnetic coil 34 is disposed via the shield plate 35.
The radial sensor coil 36 generates a magnetic flux when energized with a high-frequency current, and constitutes a radial displacement sensor with the magnetic pole portions 39 to 42.
When a high frequency current flows through the coils 36a and 36b, the magnetic pole portions 39 to 42 act as magnetic poles of the radial displacement sensor. That is, a magnetic pole is formed in each magnetic pole part 39-42. Then, a magnetic flux is generated in each of the magnetic pole portions 39 to 42.

The inductance-type radial displacement sensor detects the axial displacement of the shaft 7 by detecting the amount of change in the magnetic flux.
When a high-frequency current flows through the radial sensor coil 36, an eddy current is generated on the surfaces of the magnetic pole portions 39 to 42 and the loss increases.
In order to suppress the generation of this eddy current, grooves (slits) extending in the axial direction are formed on the magnetic pole surfaces 39a, 40a, 41a, 42a of the magnetic pole portions 39 to 42 in the axial direction of the magnetic pole surfaces 39a, 40a, 41a, 42a. A groove (slit) extending in the radial direction is provided on the magnetic pole surface.
Moreover, you may make it use the member formed by sintering the magnetic pole parts 39-42, ie, the iron core piece 32, and the iron core piece 33 instead of performing such slit processing.
The details of the polarities of the magnetic poles of the radial magnetic bearing devices 11 and 12 according to the present embodiment will be described later.

  According to the present embodiment, by arranging the radial electromagnetic coil 34 and the radial sensor coil 36 on the iron core pieces 32, 33 using the grooves 37, 38, the iron core pieces 32, 33 are arranged with the magnetic poles of the electromagnet and the diameter. It can be shared with the magnetic pole of the direction displacement sensor. That is, the magnetic pole of the electromagnet can be used as the magnetic pole of the radial displacement sensor at the same time. Accordingly, the radial displacement sensor can be configured without providing a dedicated magnetic pole separately.

In the present embodiment, all portions except for the grooves 37 and 38 of the magnetic poles 32 and 33 of the electromagnet for applying the attractive force to the shaft 7 are shared with the magnetic poles of the radial displacement sensor. Therefore, the areas of the magnetic pole surfaces 39a, 40a, 41a, and 42a of the magnetic poles 39 to 42 used in the displacement sensor can be sufficiently secured.
Since such a wide magnetic pole surface can be ensured for the radial displacement sensor, the detection sensitivity of the sensor can be easily increased. Furthermore, by ensuring a wide magnetic pole surface, the magnetic poles 39 to 42 are less likely to be saturated, and the adjustment range of the detection sensitivity of the radial displacement sensor can be expanded.

  In addition, by securing such a wide magnetic pole surface, even if there are variations in the magnetic poles 39 to 42 (variations in the magnetic pole area, magnetic pole volume, etc.) in the radial magnetic bearing portion, the error is sufficiently absorbed. be able to. That is, these variations can be suppressed to such an extent that they can be ignored.

  Furthermore, by securing such a wide magnetic pole surface, the number of turns of the radial sensor coil 36 for obtaining a predetermined inductance can be reduced. By reducing the number of turns of the radial sensor coil 36, the radial sensor coil 36 can be formed on a sheet-like printed board, for example, a flexible board. This makes it possible to reduce the manufacturing process.

According to the present embodiment, since the magnetic flux of the electromagnet for causing the attractive force to act on the shaft 7 and the magnetic flux of the radial displacement sensor are generated in different directions, the respective magnetic fluxes can be prevented from interfering with each other.
Specifically, the magnetic flux generated by the radial electromagnetic coil 34 flows between the iron core piece 32 and the iron core piece 33 via the shaft 7. On the other hand, the radial sensor coil 36 is disposed so as to straddle the iron core piece 32 and the iron core piece 33. Magnetic flux generated by the radial electromagnetic coil 34 is not linked to the radial sensor coil 36. Therefore, the magnetic flux generated by the radial electromagnetic coil 34 does not enter the radial sensor coil 36 as noise.
That is, the value of the magnetic flux of the electromagnet entering the displacement sensor coil and the value of the magnetic flux exiting are substantially the same. Therefore, since the magnetic flux of the electromagnet hardly overlaps the magnetic flux of the radial displacement sensor, the radial displacement sensor can be operated without being affected by the magnetic flux of the electromagnet.

Moreover, according to this Embodiment, the coil 36a and the coil 36b which comprise the radial direction sensor coil 36 are connected in parallel.
Here, assuming that the number of turns of the coil 36a and the coil 36b is N, the terminal voltages are Ea and Eb, the magnetic flux is φa and φb, and the time is t, the relationship of Ea = Ndφa / dt and Eb = Ndφb / dt is established. . Since both coils are connected in parallel, Ea = Eb. Therefore, dφa = dφb, and the amount of change in magnetic flux between the coils 36a and 36b becomes equal. For this reason, it can suppress that the magnetic flux of the coil 36 interferes with another coil.
Thus, by connecting the coil 36a and the coil 36b constituting the radial sensor coil 36 in parallel, the influence of the magnetic flux of the displacement sensor on the other can be reduced, and the radial magnetic bearing devices 11 and 12 can be reduced. Accuracy can be improved.

Next, modified examples 1 to 3 of the control magnetic pole portions 31a to 31d will be described.
(Modification 1)
FIG. 6 is a diagram showing a configuration of Modification 1 of the control magnetic pole portion 31a.
In addition, the same code | symbol is used for the same part (overlapping location) as Embodiment shown in FIG. 5 mentioned above, and detailed description is abbreviate | omitted.
The control magnetic pole portion 31a (Modification 1) is configured by the radial magnetic pole portion 50, the radial electromagnetic coil 34, the shield plate 35, and the radial sensor coil 58.

The radial magnetic pole part 50 includes an annular core 57 and an annular iron core 52 obtained by dividing the annular iron core 30 into two in the circumferential direction.
The annular spacer 57 is formed of a non-magnetic annular member and is sandwiched between the annular iron core 51 and the annular iron core 52.
As the nonmagnetic member forming the annular spacer 57, for example, aluminum or reinforced plastic is used.
A rectangular magnetic pole portion 53 and a magnetic pole portion 54 are formed adjacent to the annular iron core 51 so as to protrude in the direction of the shaft 7 from the inner peripheral wall.
Similarly, a rectangular magnetic pole portion 55 and a magnetic pole portion 56 are formed adjacent to the annular iron core 52 so as to protrude from the inner peripheral wall in the direction of the shaft 7.
In addition, let the surface which opposes the shaft 7 of the front-end | tip part of the magnetic pole parts 53-56 be the magnetic pole surfaces 53a, 54a, 55a, 56a.

The radial electromagnetic coil 34 includes a coil 34a and a coil 34b.
The coil 34 a is wound several turns around the magnetic pole part 53 and the magnetic pole part 55, with the two magnetic pole parts 53 and 55 as the axis. The magnetic pole portion 53 and the magnetic pole portion 55 constitute an electromagnetic pole around which the coil 34a is wound.
The coil 34 b is wound several turns around the magnetic pole part 54 and the magnetic pole part 56, with the two magnetic pole parts of the magnetic pole part 54 and the magnetic pole part 56 as the axis. The magnetic pole portion 54 and the magnetic pole portion 56 constitute an electromagnetic pole around which the coil 34b is wound.
The coil 34a and the coil 34b are connected in parallel.
In this way, the radial electromagnetic coil 34 is disposed in the radial magnetic pole part 50.
By energizing the coil 34a and the coil 34b, the magnetic pole portions 53 and 55 and the magnetic pole portions 54 and 56 are magnetized to have different polarities, and act as magnetic poles of an electromagnet that applies an attractive force for attracting the shaft 7.

The shield plate 35 is an electromagnetic shielding plate formed of a conductor plate or a conductor net, and is constituted by the same shield plate 35 as that used in the embodiment shown in FIG.
The inner edge of the shield plate 35 has a shape along the side surfaces of the magnetic pole portions 53 to 56. Further, the shield plate 35 is provided with rectangular shielding portions 35 a and 35 b extending in the central direction along the gap between the magnetic pole portion 53 and the magnetic pole portion 54 and between the magnetic pole portion 55 and the magnetic pole portion 56.
By providing the shielding portions 35a and 35b in this manner, magnetic flux leaking from between the magnetic pole portion 53 and the magnetic pole portion 54 and between the magnetic pole portion 55 and the magnetic pole portion 56 can be appropriately shielded.

The radial sensor coil 58 includes a coil 58a, a coil 58b, a coil 58c, and a coil 58d.
The coil 58a is wound several turns around the magnetic pole portion 53 as an axis.
Similarly, the coil 58b is wound around the magnetic pole portion 55, the coil 58c is wound around the magnetic pole portion 54, and the coil 58d is wound several turns around the magnetic pole portion 56 as an axis.
The coil 58a, the coil 58b, the coil 58c, and the coil 58d are all connected in parallel.
The coil 58a, the coil 58b, the coil 58c, and the coil 58d are disposed at the tip portions of the magnetic pole portions 53 to 56. The arrangement part of the radial sensor coil 36 on the magnetic pole parts 53 to 56 and the arrangement part of the radial electromagnetic coil 34 are arranged so as not to overlap.
The shield plate 35 is disposed between the radial sensor coil 58 and the radial electromagnetic coil 34.

(Modification 2)
FIG. 7 is a diagram showing a configuration of Modification 2 of the control magnetic pole portion 31a.
In addition, the same code | symbol is used for the same part (overlapping location) as Embodiment or the modification 1 shown in FIG. 5 mentioned above, and detailed description is abbreviate | omitted.
The control magnetic pole part 31 a (Modification 2) is configured by the radial magnetic pole part 50, the radial sensor coil 58, the shield part 61, the radial electromagnetic coil 34, and the shield plate 62.

The radial magnetic pole part 50 has the same structure as that of the first modification.
The radial sensor coil 58 includes a coil 58a, a coil 58b, a coil 58c, and a coil 58d. The coil 58a is wound several turns around the magnetic pole portion 53 as an axis.
Similarly, the coil 58b is wound around the magnetic pole portion 55, the coil 58c is wound around the magnetic pole portion 54, and the coil 58d is wound several turns around the magnetic pole portion 56 as an axis.
In this manner, the radial sensor coil 58 is disposed on the radial magnetic pole portion 50.
In the second modification, the arrangement location of the coil 58a, the coil 58b, the coil 58c, and the coil 58d is not limited to the tip portion of the magnetic pole portions 53 to 56, but is an arbitrary location on the side surface of the magnetic pole portions 53 to 56. You may make it arrange | position to. For example, you may make it arrange | position so that the center part of the side surface of the magnetic pole parts 53-56, or the whole side surface may be covered.

The shield part 61 is composed of shield rings 61a, 61b, 61c and 61d.
The shield rings 61a, 61b, 61c and 61d are electromagnetic shielding members for shielding magnetic flux leaking from the radial sensor coil 58, and are formed by a member obtained by processing a strip-like metal plate (for example, a copper plate) having a high shielding effect. Yes. Although the winding start and winding end portions of the belt-like shield ring overlap each other, they are not in electrical contact.
The shield ring 61a is disposed on the side surface of the magnetic pole portion 53 so as to cover the wound coil 58a.
Similarly, the shield ring 61b covers the coil 58b so as to cover the side surface of the magnetic pole portion 55, the shield ring 61c covers the coil 58c so as to cover the coil 58d, and the shield ring 61d covers the coil 58d so as to cover the coil 58d. Is arranged.

Moreover, although the shield ring 61a, 61b, 61c, and 61d uses the member which processed the metal plate, you may make it use metal foil (copper foil) instead of a metal plate.
When such a metal foil is used, the shape can be easily deformed and processed. However, since the member is very thin, a plurality of layers are arranged in order to obtain a sufficient shielding effect.

The radial electromagnetic coil 34 includes a coil 34a and a coil 34b.
The coil 34a is wound around the magnetic pole part 53 and the magnetic pole part 55 through the shield rings 61a and 61b with the two magnetic pole parts of the magnetic pole part 53 and the magnetic pole part 55 as an axis, that is, across the magnetic pole part 53 and the magnetic pole part 55. The magnetic pole portion 53 and the magnetic pole portion 55 constitute an electromagnetic pole around which the coil 34a is wound.
The coil 34b is wound several turns through the shield rings 61c and 61d with the two magnetic pole portions of the magnetic pole portion 54 and the magnetic pole portion 56 as the axis, that is, across the magnetic pole portion 54 and the magnetic pole portion 56. The magnetic pole portion 54 and the magnetic pole portion 56 constitute an electromagnetic pole around which the coil 34b is wound.
The coil 34a and the coil 34b are connected in parallel.

In this way, the radial electromagnetic coil 34 is disposed in the radial magnetic pole part 50 via the radial sensor coil 58 and the shield part 61.
By disposing a shield portion 61 between the radial electromagnetic coil 34 and the radial sensor coil 58, both the radial electromagnetic coil 34 and the radial sensor coil 58 are arranged at the tip portions of the magnetic pole portions 53 to 56. Is possible. Thereby, the control accuracy of the radial magnetic bearing devices 11 and 12 can be improved.
Further, by arranging the shield part 61 between the radial electromagnetic coil 34 and the radial sensor coil 58, the arrangement positions of both the radial electromagnetic coil 34 and the radial sensor coil 58 are not limited. That is, since both coils can be arranged at arbitrary positions, the degree of freedom in design can be improved.
By energizing the coil 34a and the coil 34b, the magnetic pole portions 53 and 55 and the magnetic pole portions 54 and 56 are magnetized to have different polarities, and act as magnetic poles of an electromagnet that applies an attractive force for attracting the shaft 7.

The shield plate 62 is an electromagnetic shielding plate formed of a conductor plate or a conductor net, and is grounded to a ground level potential of a control circuit provided in the magnetic bearing device.
The shield plate 62 is formed of a continuous annular member that is formed so as to surround the magnetic pole portions 53 to 56 and has no break at the edge portion. It is comprised by the member by which the outer edge part was short-circuited. That is, the inner edge of the shield plate 62 has a shape along the side surfaces of the magnetic pole portions 53 to 56.
That is, by forming a short ring (short-circuit ring) with the shield plate 62, interlinkage magnetic flux (leakage magnetic flux, etc.) can be consumed as a short-circuit current.

By arranging the shield plate 62 at the tip portions of the magnetic pole portions 53 to 56 as described above, the influence of the leakage magnetic flux on the shaft 7 can be reduced.
The shield plate 62 is desirably formed of, for example, a copper foil or a copper plate. When shielding a high-strength magnetic flux, several of these members are used.

(Modification 3)
FIG. 8 is a diagram showing a configuration of Modification 3 of the control magnetic pole portion 31a.
In addition, the same code | symbol is used for the same part (overlapping part) as Embodiment or the modification 1, 2 shown in FIG. 5 mentioned above, and detailed description is abbreviate | omitted.
The control magnetic pole portion 31a (Modification 3) is configured by the radial magnetic pole portion 70, the radial electromagnetic coil 34, the shield plate 72 in the radial direction, and the sensor coil 36.

The radial magnetic pole portion 70 includes an annular spacer 57, an annular core 51 and an annular core 52 obtained by dividing the annular core 30 into two in the circumferential direction, and magnetic members 71 and 72.
The annular spacer 57 is formed of a non-magnetic annular member and is sandwiched between the annular iron core 51 and the annular iron core 52.
A rectangular magnetic pole portion 53 and a magnetic pole portion 54 are formed adjacent to the annular iron core 51 so as to protrude in the direction of the shaft 7 from the inner peripheral wall.
Similarly, a rectangular magnetic pole portion 55 and a magnetic pole portion 56 are formed adjacent to the annular iron core 52 so as to protrude from the inner peripheral wall in the direction of the shaft 7.

The magnetic member 71 is formed of a rectangular member made of a magnetic material, and is sandwiched between the magnetic pole part 53 and the magnetic pole part 55.
Similarly, the magnetic member 72 is formed of a rectangular member made of a magnetic material, and is sandwiched between the magnetic pole portion 54 and the magnetic pole portion 56.
The magnetic members 71 and 72 are made of, for example, a laminated silicon steel plate or ferrite.
In addition, let the surface which opposes the shaft 7 of the front-end | tip part of the magnetic pole parts 53-56 be the magnetic pole surfaces 53a, 54a, 55a, 56a.

The radial electromagnetic coil 34 includes a coil 34a and a coil 34b.
The coil 34 a is wound several turns around the magnetic pole part 53 and the magnetic pole part 55, with the two magnetic pole parts 53 and 55 as the axis. The magnetic pole portion 53 and the magnetic pole portion 55 constitute an electromagnetic pole around which the coil 34a is wound.
The coil 34 b is wound several turns around the magnetic pole part 54 and the magnetic pole part 56, with the two magnetic pole parts of the magnetic pole part 54 and the magnetic pole part 56 as the axis. The magnetic pole portion 54 and the magnetic pole portion 56 constitute an electromagnetic pole around which the coil 34a is wound.
The coil 34a and the coil 34b are connected in parallel.
In this manner, the radial electromagnetic coil 34 is disposed on the radial magnetic pole portion 70.
By energizing the coil 34a and the coil 34b, the magnetic pole portions 53 and 55 and the magnetic pole portions 54 and 56 are magnetized to have different polarities, and act as magnetic poles of an electromagnet that applies an attractive force for attracting the shaft 7.

The shield plate 72 is an electromagnetic shielding plate for shielding (blocking) the leakage magnetic flux of the radial electromagnetic coil 34. By providing the shield plate 72, the influence of the magnetic flux generated from the radial electromagnetic coil 34 on other portions can be reduced.
The shield plate 35 is formed of a conductor plate or a conductor net, and is grounded to a ground level potential of a control circuit provided in the magnetic bearing device.
The shield plate 72 is configured by a continuous annular member that is formed so as to surround the magnetic pole portions 53 to 56 and has no break at the edge portion.
That is, the shield plate 72 constitutes a short ring (short-circuit ring), so that interlinkage magnetic flux (leakage magnetic flux or the like) can be consumed as a short-circuit current.

The inner edge of the shield plate 72 has a shape along the side surfaces of the magnetic pole portions 53 to 56. Further, the shield plate 72 is provided with rectangular shielding portions 72 a and 72 b extending in the central direction along the gap between the magnetic pole portion 53 and the magnetic pole portion 55 and the gap between the magnetic pole portion 54 and the magnetic pole portion 56. Yes.
Thus, by providing the shielding portions 72a and 72b, the magnetic flux leaking from the gap between the magnetic pole portion 53 and the magnetic pole portion 55 and the gap between the magnetic pole portion 54 and the magnetic pole portion 56 can be appropriately shielded.
The shield plate 72 is desirably formed of, for example, a copper foil or a copper plate. When shielding a high-strength magnetic flux, several of these members are used.

The radial sensor coil 36 includes a coil 36a and a coil 36b.
The coil 36 a is wound several turns around the magnetic pole part 53 and the magnetic pole part 54, with the two magnetic pole parts 53 and 54 as the axis.
The coil 36 b is wound several turns around the magnetic pole part 55 and the magnetic pole part 56, with the two magnetic pole parts 55 and 56 as the axis.
The coil 36a and the coil 36b are connected in parallel.

The coils 36a and 36b are disposed at the tip portions of the magnetic pole portions 53 to 56. The arrangement part of the radial sensor coil 36 on the magnetic pole parts 53 to 56 and the arrangement part of the radial electromagnetic coil 34 are arranged so as not to overlap.
The shield plate 72 is disposed between the radial sensor coil 36 and the radial electromagnetic coil 34.

In this way, the radial sensor coil 36 is disposed on the radial magnetic pole portion 70 where the radial electromagnetic coil 34 is disposed via the shield plate 72.
The radial sensor coil 36 generates a magnetic flux when energized with a high-frequency current, and constitutes a radial displacement sensor with the magnetic pole portions 53 to 56.
When a high frequency current flows through the coils 36a and 36b, the magnetic pole portions 53 to 56 act as magnetic poles of the radial displacement sensor. That is, a magnetic pole is formed in each magnetic pole part 53-56. Then, magnetic flux is generated in each of the magnetic pole portions 53 to 456.
The inductance-type radial displacement sensor detects the axial displacement of the shaft 7 by detecting the amount of change in the magnetic flux.

According to the first, second, and third modifications of the radial magnetic bearing portion, the four magnetic pole portions constituting the control magnetic pole portion 31a are formed by a simple shape member without providing a groove in the magnetic pole portion. Since it can comprise, manufacturing cost can be reduced.
In particular, in a radial magnetic bearing device, the magnetic pole is often constituted by a silicon steel plate or the like. Since this silicon steel plate is a very thin member, it is easy to cause burrs and deformations when processing the shape, but by forming the magnetic pole with such a simple magnetic pole part, it is possible to suppress the occurrence of such problems. it can.

Next, the polarity of the magnetic poles in the control magnetic pole portions 31a to 31d of the radial magnetic bearing devices 11 and 12 and the radial magnetic bearing devices 11 and 12 shown in the first to third modifications will be described.
FIG. 9 is a diagram showing the polarity state of each magnetic pole when the radial magnetic bearing devices 11 and 12 are deployed in the AA ′ portion shown in FIG. 4. Since the radial magnetic bearing devices 11 and 12 have a target structure, only half of the radial magnetic bearing devices 11 and 12 will be described here.

FIG. 9 simply shows only the magnetic polarity at the tip of each magnetic pole, and the polarity of the electromagnet has the same polarity in both the upper and lower stages, so only a development view seen from the direction of the intake port 5 is shown. Show. Moreover, about the polarity of the displacement sensor, the expanded view seen from the direction of the shaft 7 is described. In addition, in order to distinguish this Embodiment shown in FIG. 5 from the modifications 1-3, it shows as a "representative form."
In FIG. 9, the magnetic pole provided on the intake port 5 side of the radial magnetic bearing portion is represented as the upper stage, and the magnetic pole provided on the exhaust port 6 side is represented as the lower stage.

9A shows the radial magnetic bearing devices 11 and 12 according to the present embodiment and the radial magnetic bearing portions (hereinafter referred to as “representative form and deformation”) in the radial magnetic bearing devices 11 and 12 shown in the third modification. It is the figure which showed the state of the polarity of each magnetic pole of (example 3).
FIG. 9B shows the polarities of the magnetic poles of the radial magnetic bearing portions (hereinafter referred to as “Modification 1 and Modification 2”) in the radial magnetic bearing devices 11 and 12 shown in Modification 1 and Modification 2. It is the figure which showed the state of.
Further, since the displacement sensor is driven by a high frequency current, the magnetic pole is not constant but always changes, that is, the polarity is switched. Therefore, the state at a certain time is shown in the figure.

  As shown in FIGS. 9A and 9B, the radial magnetic bearing devices 11 and 12 according to the present embodiment and the control magnetic pole portions of the radial magnetic bearing devices 11 and 12 shown in the first to third modifications. In 31a to 31d, the electromagnets have a common magnetic property, and the direction in which the magnetic flux is generated, that is, the direction in which the magnetic path 93 and the magnetic path 94 of the electromagnet are formed is the same.

On the other hand, the magnetic pole characteristics of the radial displacement sensor have different characteristics in FIGS. 9A and 9B, and the direction in which the magnetic flux is generated, that is, the direction in which the magnetic path is formed, is also different.
As shown to Fig.9 (a), the coil is wound so that the magnetic pole property in each step may become the same in the radial direction displacement sensor in a representative form and the modification 3. FIG. The upper and lower stages always have different magnetic polarities, and the magnetic flux of the displacement sensor is generated so that the magnetic paths 95 to 98 of the radial displacement sensor are formed between the magnetic poles adjacent in the vertical direction. ing.
In the third modification, magnetic paths 95 to 98 are formed via magnetic members 71 and 72 interposed between the magnetic poles.
As shown in FIG. 9B, in the displacement sensors in the first and second modifications, the coils are wound so that the polarities of the magnetic poles adjacent in the vertical direction are always different. The magnetic flux of the displacement sensor is generated so that magnetic paths 99 to 102 are formed between adjacent magnetic poles on the same stage.

In the first and second modifications described above, the radial sensor coil 58 is configured by the coils 58a, 58b, 58c, and 58d, and these four coils are connected in parallel. However, instead of connecting all four coils in parallel, the coils 58a and 58b connected in series and the coils 58c and 58d connected in series may be connected in parallel. Good.
By connecting the four coils in series and parallel in this way, the number of turns of each coil necessary to obtain a predetermined inductance value can be reduced to one-fourth of the number of turns when all the coils are connected in parallel. it can.

It is the figure which showed the structure of the molecular pump using the magnetic bearing apparatus which concerns on this Embodiment. It is the figure which showed the structure of the axial direction magnetic bearing part which comprises an axial direction magnetic bearing apparatus. It is the figure which showed the modification of the axial direction magnetic bearing part. It is the figure which showed the cross section of the radial direction magnetic bearing apparatus which concerns on this Embodiment. It is the figure which showed the structure of the control magnetic pole part. It is the figure which showed the structure of the modification of a control magnetic pole part (modification 1). It is the figure which showed the structure of the modification of a control magnetic pole part (modification 2). It is the figure which showed the structure of the modification of a control magnetic pole part (modification 3). It is the figure which showed the state of the polarity of each magnetic pole at the time of developing a radial direction magnetic bearing apparatus in the A-A 'part shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Molecular pump 2 Casing 3 Base 4 Rotor part 5 Intake port 6 Exhaust port 7 Shaft 8 Rotor blade 9 Cylindrical member 10 Motor part 11 Radial direction magnetic bearing apparatus 12 Radial direction magnetic bearing apparatus 13 Axial direction magnetic bearing apparatus

Claims (5)

A magnetic bearing device that supports a rotary shaft in a non-contact manner by magnetically levitating using a magnetic force,
An electromagnetic pole that constitutes an electromagnet that generates the magnetic force, and whose tip is divided into a plurality of magnetic poles,
A sensor coil disposed in all regions of the magnetic pole portion;
Comprising
A magnetic bearing device characterized in that all regions of the magnetic pole portion are shared with a sensor magnetic pole constituting a displacement sensor for detecting a displacement amount of the rotating shaft. A magnetic bearing device for supporting the rotating shaft in a radial direction,
The electromagnet is constituted by a pair of two divided electromagnetic poles,
2. The magnetic bearing device according to claim 1, wherein the sensor coil is disposed so that each of the two divided electromagnetic poles acts as a magnetic pole of a different polarity of the displacement sensor. A magnetic bearing device for supporting the rotating shaft in the axial direction,
The magnetic bearing device according to claim 1, wherein the electromagnetic pole is formed in a circular shape and divided into a plurality of regions by a groove extending in a radial direction. 3. The magnetic bearing device according to claim 2, wherein the sensor coil is disposed across both the electromagnetic poles. The magnetic bearing device according to claim 1, wherein the sensor coil is connected in parallel.

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