JP2002257136A - Magnetic bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic bearing by which a large control force necessary at the time of start and stop of a rotor is obtained and high speed responsiveness necessary at the time of high revolution is obtained and which is small in rotational loss and power consumption. SOLUTION: In the magnetic bearing, a rotor 2 is held in noncontact support with respect to a casing 1. The magnetic bearing is provided with a first supporting part 3 bearing the rotor 2 by the magnetic attraction force of a plurality of electromagnet 6 and a second supporting part 4 bearing the rotor 2 by Lorentz force generating in the coils 11, 12 in the magnetic field. The rotor 2 is supported by the first supporting part 3 at the time of start and stop of the rotor 2 and the rotor 2 is supported by the second supporting part 4 at the time of high speed rotation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control type magnetic bearing device for supporting a rotating body in an axial direction and a radial direction without contact in an energy storage flywheel, an ultra-high speed rotating body, and the like. The present invention relates to a control type magnetic bearing which supports in a non-contact direction or in a radial direction.

[0002]

2. Description of the Related Art A control type magnetic bearing device in which a rotating body is magnetically levitated and supported in a non-contact manner can greatly reduce a loss caused by rotation, and is therefore widely used in many applications. .

In general, a control type magnetic bearing device includes a set of control type axial magnetic bearings that support a rotating body in a non-contact manner in a fixed portion such as a casing in an axial direction, and a non-contact support in a radial direction. And two sets of controlled radial magnetic bearings.

An axial magnetic bearing is a pair (two) of axial magnetic bearings which are arranged so as to sandwich a rotor disk portion provided integrally with a rotating body from both sides in the axial direction and magnetically attract the rotor disk portion in the axial direction. It has an electromagnet. Each radial magnetic bearing is provided with a plurality (normally two pairs (four)) of radial electromagnets arranged at equal intervals in the circumferential direction of the rotating body and magnetically attracting the rotor portion of the rotating body in the radial direction. . Each of the electromagnets is wound with a coil for flowing an exciting current that is a combination of a constant bias current and a control current controlled according to the displacement of the rotating body.

On the other hand, there has been proposed a radial magnetic bearing which supports the rotating body in a non-contact manner by Lorentz force generated between a permanent magnet provided on the rotating body side and a coil provided on the fixed portion side. Yes (Japanese Patent Application 2000-20
No. 3179).

[0006]

In the case of a conventional magnetic bearing that supports a rotating body by the magnetic attraction of an electromagnet, a large control force can be obtained, but the rotation causes eddy current loss (rotation loss due to eddy current). As a result, there is a problem that high-speed response is reduced. In particular, in a radial magnetic bearing, a large change in magnetic flux density in the circumferential direction of the rotating body causes a large eddy current. Radial magnetic bearings include a heteropolar type and a homopolar type, depending on the structure of the radial electromagnet.
Compared with the heteropolar type radial magnetic bearing, the change in the magnetic flux density in the circumferential direction of the rotating body is small and the eddy current is small, but some eddy current is still generated. Eddy currents are usually
By using laminated steel sheets for the rotor of the rotating body facing the electromagnet, it can be considerably reduced, but it is still impossible to eliminate eddy current, and in recent years, such as energy storage flywheels and ultra-high speed rotating bodies As described above, even when laminated steel sheets are used for the rotor portion of the rotating body, applications in which eddy current loss becomes a practical problem have increased. On the other hand, in the case of the axial magnetic bearing, a laminated steel plate cannot be used in order to secure strength against rotation of the rotor disk portion. Further, since an exciting current is always supplied to the coil of the electromagnet, there is a problem that power consumption is large.

In the case of a magnetic bearing that supports a rotating body with Lorentz force, there is no eddy current loss due to rotation and high frequency response is obtained, but there is a problem that the control force is small.

An object of the present invention is to solve the above problems,
It is an object of the present invention to provide a magnetic bearing which can obtain a large control force required at the time of starting and stopping a rotating body, obtain a high-speed response required at a high speed rotation, and have a small rotation loss and low power consumption.

[0009]

SUMMARY OF THE INVENTION A magnetic bearing according to the present invention is a magnetic bearing which supports a rotating body in a non-contact manner in an axial direction or a radial direction with respect to a fixed portion. A first support unit that supports the rotating body by a force, and a second support unit that supports the rotating body by a Lorentz force generated in a coil in a magnetic field,
At the time of starting and stopping of the rotating body, the rotating body is supported by the first support portion, and at the time of high-speed rotation, the rotating body is supported by the second support portion.

When the rotating body is started and stopped, the rotating body is supported by the first support using the magnetic attraction of the electromagnet. Therefore, a large control force required at the time of starting and stopping is obtained.

When the rotating body rotates at high speed, the rotating body is supported by the second support using the Lorentz force. Therefore, there is no eddy current loss, and a high frequency response can be obtained.
Further, in the magnetic bearing using the Lorentz force, current needs to be supplied to the coil only when displacement of the rotating body occurs, so that current consumption is small.

When starting and stopping the rotating body, high-frequency response is not required. Therefore, there is no problem even if the rotating body is supported by the first supporting portion using the magnetic attraction force of the electromagnet. When the rotating body rotates at a high speed, the position of the rotating body is stable, so that a large control force is not required, and there is no problem even if the rotating body is supported by the second support using the Lorentz force. In addition, when the rotating body is started and stopped, the rotating body is supported by the first supporting portion using the magnetic attraction of the electromagnet, so that eddy current loss occurs and current consumption is large. On the other hand, since the time for starting and stopping the rotating body is very short, eddy current loss and power consumption are extremely small as a whole.

According to the magnetic bearing of the present invention, as described above, it is possible to obtain a large control force required at the time of starting or stopping the rotating body, and to obtain a high-speed response required at the time of high-speed rotation. In addition, eddy current loss and power consumption can be reduced.

A magnetic bearing according to the present invention is, for example, a magnetic bearing for supporting a rotating body in a non-contact manner with respect to a fixed portion in an axial direction, wherein a first support portion is provided integrally with the rotating body. A pair of electromagnets fixedly provided on the fixed portion so as to be located on both axial sides of the portion and magnetically attracting the rotor disk portion, and the second support portion includes:
A cylindrical portion provided concentrically and integrally outside the outer peripheral surface of the rotating body or inside the inner peripheral surface of the rotating body, and fixed so as to be concentrically located between the cylindrical portion and the opposed peripheral surface of the rotating body. An annular coil fixedly provided in the portion and through which an electric current flows, and an annular permanent magnet fixed to at least one of the cylindrical portion and the opposing peripheral surface of the rotating body and having magnetic poles on the inner peripheral surface and the outer peripheral surface; It has.

In this case, in the second support portion, a cylindrical portion,
At least the opposing peripheral surface portions of the rotating body and the portion connecting them are made of a magnetic material.

In the second support portion, since the annular permanent magnet has magnetic poles on the inner peripheral surface and the outer peripheral surface, an annular magnetic path passing through the cylindrical portion, the rotating body and the space therebetween is formed. Then, in the space between the cylindrical portion where the coil is arranged and the rotating body, the magnetic flux is directed in the radial direction. The magnetic field generated by the permanent magnet is uniform in the direction of rotation of the rotating body. In the space between the cylindrical part where the magnetic field oriented in the radial direction is formed and the rotating body, a circumferential current flows through the coil, so that a Lorentz force is generated in the coil in the radial direction and in the axial direction orthogonal to the circumferential direction. However, since the coil is fixed to the fixed portion, an axial force acts on the rotating body as a reaction. Therefore, by controlling the direction and magnitude of the current flowing through the coil in accordance with the axial displacement of the rotating body detected by the appropriate axial displacement detecting means, the axial position of the rotating body can be controlled. . When the axial displacement of the rotating body is 0, it is not necessary to supply current to the coil. Since the magnetic field generated by the permanent magnet is uniform in the rotation direction of the rotating body, the magnetic flux density does not change in the rotating direction of the rotating body. Therefore, no eddy current is generated by the rotation of the rotating body, and the rotation loss is extremely small. Further, since it is not necessary to always supply a current to the coil, power consumption is small.

In the magnetic bearing of the present invention, for example,
A magnetic bearing for supporting a rotating body in a non-contact manner in a radial direction with respect to a fixed part, wherein the first supporting part is fixed to the fixed part such that the first supporting part is located at equal intervals in a circumferential direction around the rotating body. A second support portion provided with at least three electromagnets for magnetically attracting the rotating body, wherein the second support portion is provided with two rotor disk portions provided concentrically and integrally at predetermined intervals in the axial direction; At least three coils fixedly provided on a fixed portion so as to be positioned at equal intervals and having a circumferential current flowing through a portion located between the two rotor disk portions; And a ring-shaped permanent magnet fixed to at least one of the opposed surfaces and having magnetic poles at both ends in the axial direction.

In this case, in the second support portion, at least the peripheral surface portions of the two rotor disk portions and the rotating body connecting them are made of a magnetic material.

In the second support portion, the annular permanent magnet has magnetic poles at both ends in the axial direction, so that the annular permanent magnet has an annular shape passing through the space between each rotor disk portion, the rotating body and the two rotor disk portions. A magnetic path is formed,
In the space between the two rotor disk portions where the coils are arranged, the magnetic flux is directed in the axial direction. The magnetic field generated by the permanent magnet is uniform in the direction of rotation of the rotating body.
In the space between the two rotor disk portions in which the magnetic field oriented in the axial direction is formed, a current in the circumferential direction is caused to flow through the coil portion, so that the coil portion is axially and radially orthogonal to the circumferential direction. Although a Lorentz force is generated, since the coil is fixed to the fixed part, a radial force acts on the rotating body as a reaction. Therefore, by controlling the direction and magnitude of the current flowing through the coil in accordance with the radial displacement of the rotating body detected by the appropriate radial displacement detecting means, the radial position of the rotating body can be controlled. . When the radial displacement of the rotating body is 0, it is not necessary to supply a current to the coil. Since the magnetic field generated by the permanent magnet is uniform in the rotation direction of the rotating body, the magnetic flux density does not change in the rotating direction of the rotating body. Therefore, no eddy current is generated by the rotation of the rotating body, and the rotation loss is extremely small. Further, since it is not necessary to always supply a current to the coil, power consumption is small.

[0020]

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

FIGS. 1 to 3 show a first embodiment.

FIG. 1 shows a vertical section of a radial magnetic bearing portion of a magnetic bearing device, and FIG. 2 shows one horizontal section thereof. This magnetic bearing device is of a vertical type in which a vertically rotating body (2) is supported in a non-contact manner at the center of a cylindrical casing (1), which is a vertically disposed fixed part, in a non-contact manner and rotates. In the description of the first embodiment, the left and right of FIG. 1 are left and right, the front side of the sheet of FIG. The vertical control axis in the axial direction (axial direction) of the rotating body (2) is the Z axis, and the control axis in the left-right direction (radial direction) orthogonal to the Z axis is the X axis. The control axis in the direction (radial direction) is defined as the Y axis. The upper, right, and rear sides are defined as positive sides in the Z-axis, X-axis, and Y-axis directions.

The radial magnetic bearing includes an upper first support portion.
(3) and a lower second support portion (4).

The first support portion (3) supports the rotating body (2) by using the magnetic attraction of the electromagnet, and supports the rotor portion (5) formed on the outer periphery of the rotating body (2). It has four electromagnets (6) fixed to the inner peripheral surface of the surrounding casing (1). These electromagnets (6) are arranged at equal intervals in the circumferential direction. Further, a coil (7) for flowing an exciting current is wound around each electromagnet (6). The first support portion (3) can have the same configuration as that of the above-described conventional radial magnetic bearing, and a detailed description thereof will be omitted.

The second support part (4) supports the rotating body (2) using Lorentz force, and is configured as follows.

A yoke (8) made of a magnetic material, in which rotor disk portions (8a) and (8b) each having a perforated disk shape are integrally formed at upper and lower ends of a cylindrical portion (8c), is concentric with the rotating body (2). It is fixed in the shape.
The upper disk portion (8a) is referred to as a first disk portion, and the lower disk portion (8b) is referred to as a second disk portion. yoke
The cylindrical portion (8c) of (8) forms a part of the outer periphery of the rotating body (2).

An annular permanent magnet (9) is fixed to at least one of the opposing surfaces of the two disk portions (8a) and (8b), in this example, the lower surface of the first disk portion (8a). permanent magnet
(9) has magnetic poles at both ends in the Z-axis direction. In this example, the upper end face is an N pole and the lower end face is an S pole. Casing corresponding to the intermediate position between the permanent magnet (9) and the second disk portion (8b)
A coil unit (10) is fixedly provided on the inner peripheral surface of (1). The coil unit (10) includes four sets of coils (11), (12), (13), and (14) arranged at equal intervals in the circumferential direction. As shown in detail in FIG. 2, each of the coils (11) to (1)
4) is wound around the Z-axis at a portion corresponding to 1/4 of the circumference to form a double arc, and the four coils (1
The whole of 1) to (14) forms a double circle concentric with the casing (1). Then, the arc-shaped inner winding portions (11a) (12a) (13a) (14a) of the coils (11) to (14) are located between the permanent magnet (9) and the second disk portion (8b). They are located with an appropriate gap in the Z-axis direction. The two coils (11) and (12) facing in the X-axis direction and the two coils (13) and (14) facing in the Y-axis direction form a pair, respectively. A pair of coils (11) (1
2) is an X-axis coil and a pair of coils (13) opposed in the Y-axis direction.
(14) is called a Y-axis coil. Two X-axis coils
(11) and (12) are connected in series, and when a current flows through them, as shown by arrows in FIG.
a) A current flows in (12a) in the same direction as the Y-axis direction. Two Y-axis coils (13) and (14) are also connected in series,
When an electric current is applied to these, as shown by arrows in FIG. 2, the electric current flows through the two inner winding portions (13a) and (14a) in the same direction in the X-axis direction.

In the vicinity of the two support portions (3) and (4), a rotating body (2)
An X-axis displacement detecting device for detecting the displacement in the X-axis direction and a Y-axis displacement detecting device for detecting the displacement in the Y-axis direction are provided. Known and appropriate configurations can be adopted for these displacement detection devices, and thus illustration and description are omitted.

Although not shown, the radial magnetic bearing has a control means for controlling the first support portion (3) and the second support portion (4) based on the radial displacement of the rotating body (2). A controller is provided.

In the first support portion (3), as in the prior art,
According to the displacement of the rotating body (2) in the X-axis direction and the Y-axis direction,
By controlling the exciting current flowing through the coil (7) of each electromagnet (6), the rotating body (2) is supported in a non-contact manner in the radial direction,
The position in the radial direction is controlled.

In the second support portion (4), as shown by arrows in FIG. 1, the first disk portion (8a), the cylindrical portion (8c) and the second disk portion of the yoke (8) are moved by the permanent magnet (9). An annular closed magnetic path is formed through the portion (8b) and the space between the second disk portion (8b) and the permanent magnet (9). 1st disk part (8a)
Then, the magnetic flux faces inward in the radial direction,
In (8b), the magnetic flux faces outward in the radial direction. Also, the second
Between the disk portion (8b) and the permanent magnet (9), the magnetic flux faces upward and is orthogonal to the inner winding portions (11a) to (14a) of the coils (11) to (14). The rotating body (2) is supported in a non-contact manner in the radial direction as described below, and the position in the radial direction is controlled.

As will be described in detail with reference to FIG. 3, the control of the position in the X-axis direction is carried out in accordance with the displacement of the rotating body (2) in the X-axis direction. This is performed by controlling the direction and magnitude of the current flowing through the device.

As shown in FIG. 3A, the X-axis coils (11) (1)
When a current in the negative direction of the Y-axis (forward) is applied to the inner winding portions (11a) and (12a) of 2), the Lorentz force Fc in the negative direction of the X-axis (left) flows through the inner winding portions (11a) and (12a). Occurs, but the coil (1
Since 1) and (12) are fixed to the casing (1), as a reaction, a force Fr in the X-axis positive direction (rightward) is applied to the rotating body (2).
Works. Conversely, as shown in FIG.
(11) When a current in the Y-axis positive direction (rearward direction) is applied to the inner winding portions (11a) and (12a) of the (12), the Lorentz force Fc in the X-axis positive direction flows through the inner winding portions (11a) and (12a). Is generated, and similarly, a force Fr in the negative direction of the X-axis acts on the rotating body (2) as a reaction. When no current is flowing through the inner winding portions (11) and (12a) of the X-axis coils (11) and (12), no Lorentz force is generated on the inner winding portions (11a) and (12a), and the rotation is reduced. No X-axis force is generated on the body (2). When the rotating body (2) is not displaced in the X-axis direction, the controller controls the inner winding portion (1).
1a) When current does not flow through (12a) and displacement of the rotating body (2) in the negative direction of the X axis occurs, current flows through the inner winding portions (11a) and (12a) in the direction of FIG. 3 (a). When a force Fr in the positive X-axis direction is applied to the rotating body (2), and the rotating body (2) is displaced in the positive X-axis direction, the inner winding portions (11) and (12a) are moved to the positions shown in FIG. The current in the direction of
A force Fr in the negative direction of the X axis is applied to the rotating body (2). Also, depending on the magnitude of the displacement of the rotating body (2), the inner winding portions (11a) (12
By controlling the magnitude of the current flowing through a), the magnitude of the force Fr acting on the rotating body (2) is controlled. Thereby, the position of the rotating body (2) in the X-axis direction is controlled, and the rotating body (2) is supported in a non-contact manner at the target position in the X-axis direction.

The same applies to the control of the position in the Y-axis direction.

The controller switches between the two support portions (3) and (4) depending on the operating condition of the rotating body (2). That is, when the rotating speed of the rotating body (2) at the time of starting and stopping the rotating body (2) is low, the rotating body (2) is supported using only the first support portion (3), and When rotating, the second support (4)
The rotating body (2) is supported by using only the rotating body (2).

In the second support portion (4), the magnetic field generated by the permanent magnet (9) is uniform in the rotation direction of the rotating body (2), so that the magnetic flux density changes in the rotating direction of the rotating body (2). Does not occur. Therefore, no eddy current is generated by the rotation of the rotating body (2), and the rotation loss is extremely small. Further, since it is not necessary to always supply a current to the coils (11) to (14), power consumption is small.

When the rotating body (2) is started and stopped, the rotating body (2) is supported by the first support portion (3) using the magnetic attraction of the electromagnet (6). The required large control force is obtained.

When the rotating body (2) rotates at a high speed, the rotating body (2) is supported by the second support portion (4) using Lorentz force, so that there is no eddy current loss and high frequency response is obtained. Also, only when the displacement of the rotating body (2) occurs, the coils (10) to
Since current only needs to flow through (14), current consumption is small.

When starting and stopping the rotating body (2), high-frequency response is not necessary. Therefore, the rotating body (2) is supported by the first support portion (3) using the magnetic attraction of the electromagnet (6). No problem. When the rotating body (2) rotates at high speed, the position of the rotating body (2) is stable, so that a large control force is not required, and the rotating body (2) is rotated by the second support portion (4) using Lorentz force. There is no problem even if you support. Further, when the rotating body (2) is started and stopped, the rotating body (2) is supported by the first support portion (3) using the magnetic attraction force of the electromagnet, so that eddy current loss occurs and current consumption is reduced. Large, but for the whole operation time of the rotating body (2),
Since the time for starting and stopping the rotating body (2) is very short,
Overall, eddy current loss and power consumption are extremely small.

In the above embodiment, four sets of coils (11) to
(14), a pair of coils (1
1) While (12) is connected in series, a pair of coils (13) and (14) in the Y-axis direction are connected in series, and the X-axis direction is changed according to the displacement of the rotating body (2) in the X-axis direction. The direction and magnitude of the current flowing through the coils (11) and (12) are controlled, and the direction of the current flowing through the coils (13) and (14) in the Y-axis direction according to the displacement of the rotating body (2) in the Y-axis direction. Rotating body by controlling the size and
(2) The position in the radial direction can be controlled, and control is easy.

However, the number of coils may be three or more. When three sets of coils are provided, X of the rotating body (2)
According to the displacements in the axial direction and the Y-axis direction, the direction and magnitude of the current flowing through the three sets of coils are individually controlled.

In the above embodiment, the permanent magnet (9) is
Although it is provided only on the disk portion (8a) side, it may be provided only on the second disk portion (8b) side, or may be provided on both disk portions (8a) and (8b). Both disc parts (8a)
When provided in (8b), the polarities of the magnetic poles on the same side in the axial direction are the same for both permanent magnets.

In the first embodiment, the radial magnetic bearing in the vertical magnetic bearing device is shown. However, the radial magnetic bearing according to the present invention is applied to a horizontal magnetic bearing device in which a rotating body is horizontally arranged. Can also be applied.

FIGS. 4 to 6 show a second embodiment.

FIG. 4 shows a vertical longitudinal section of the axial magnetic bearing portion of the magnetic bearing device, and FIG. 5 shows one vertical transverse section thereof. This magnetic bearing device is of a horizontal type in which a horizontal shaft-like rotating body (21) is supported in a non-contact manner at the center of a cylindrical casing (20) which is a fixed portion arranged horizontally, and rotates. In the description of the second embodiment, the left side of FIG. 4 is the front, the right side is the rear, the front side of FIG. 4 is left, and the back side of FIG. 4 is right. The horizontal control axis in the axial direction (axial direction) of the rotating body (21) is the Z axis, and the horizontal control axis in the horizontal direction (radial direction) orthogonal to the Z axis is the X axis, Z axis, and X axis.
The control axis in the vertical direction (radial direction) orthogonal to the axis is defined as the Y axis. The front side, right side, and upper side are defined as positive sides of the Z axis, X axis, and Y axis.

The axial magnetic bearing has a first support portion on the front side.
(22) and a rear second support portion (23).

The first support portion (22) supports the rotating body (21) by using the magnetic attraction of an electromagnet, and includes a rotor disk portion (24) formed on the outer periphery of the rotating body (21). The front and rear 1 fixed to the inner peripheral surface of the casing (20) so as to be positioned before and after
A pair of annular electromagnets (25) and (26) are provided. Each electromagnet (25) (2
6) is an annular yoke (27) fixed to the casing (20)
And an annular coil (28) wound inside the yoke (27) to allow the excitation current to flow. 1st support
(22) can have a configuration similar to that of the conventional axial magnetic bearing described above, and thus a detailed description is omitted.

The second support portion (23) supports the rotating body (21) using Lorentz force, and is configured as follows.

A concentric outer cylindrical portion (29a) is attached to the rotating body (21).
A yoke (29) made of a magnetic material and having a shape in which the front ends of the inner cylindrical portion (29b) are connected to each other by a flange portion (29c) is concentrically fixed. The inner cylindrical portion (29b) forms a part of the outer periphery of the rotating body (21).

An annular permanent magnet (30) is fixed to at least one of the opposing peripheral surfaces of the two cylindrical portions (29a) (29b), in this example, the outer peripheral surface of the inner cylindrical portion (29b). permanent magnet
(30) has magnetic poles on the inner peripheral surface and the outer peripheral surface. In this example, the outer peripheral surface is an N pole and the inner peripheral surface is an S pole. Casing (20)
An annular coil unit (31) is fixedly provided on the inner peripheral surface of the coil unit. The coil unit (31) has a flange (32) fixed to the inner peripheral surface of the casing (20), and is fixedly provided at a portion extending forward from the inner peripheral edge of the flange (32) to form an outer cylindrical portion (29a ) And an annular coil located between the permanent magnet (30)
(33). A current flows through the coil (33) in the circumferential direction, that is, clockwise or counterclockwise as viewed from the rear side.

In the vicinity of the two support portions (3) and (4), the rotating body (2)
Is provided with a Z-axis X-axis displacement detecting device for detecting the displacement in the Z-axis direction. As the Z-axis displacement detecting device, a known and appropriate configuration can be adopted, illustration and description are omitted.

Although not shown in the drawings, the axial magnetic bearing has a first rotation based on the axial displacement of the rotating body (21).
A controller is provided as control means for controlling the support part (22) and the second support part (23).

In the first support portion (22), as in the prior art,
According to the displacement of the rotating body (21) in the Z-axis direction, each electromagnet (25) (2
By controlling the exciting current flowing through the coil (28) of 6),
The rotating body (21) is supported in a non-contact manner in the axial direction, and its position in the axial direction is controlled.

In the second support portion (23), as shown by arrows in FIG. 4, the outer cylindrical portion (29a), the flange portion (29c) and the inner cylindrical portion (29c) of the yoke (19) are moved by the permanent magnet (30). 29b), as well as an annular closed magnetic path through the space between the permanent magnet (30) and the outer cylinder (29b) is formed, and in the space between the permanent magnet (30) and the outer cylinder (29a), The magnetic flux faces outward in the radial direction and is orthogonal to the coil (33). As described below, the rotating body (21) is supported in a non-contact manner in the axial direction, and the position in the axial direction is controlled.

The control of the position in the Z-axis direction is performed by controlling the direction of the current flowing through the coil (33) in accordance with the displacement of the rotating body (21) in the Z-axis direction, as will be described in detail with reference to FIG. And by controlling the size.

As shown in FIG. 6A, when a clockwise current is applied to the coil 33 when viewed from the rear side, a Lorentz force Fc in the negative Z-axis direction (rearward direction) is generated in the coil 33. However, since the coil (33) is fixed to the casing (20), as a reaction, a force F in the positive Z-axis direction (forward) is applied to the rotating body (21).
r works. Conversely, as shown in FIG.
When a counterclockwise current is passed through the coil (33)
, A Lorentz force Fc in the positive direction of the Z-axis is generated. Similarly, as a reaction, a force Fr in the negative direction of the Z-axis acts on the rotating body (2). When no current is flowing through the coil (33),
No Lorentz force is generated on the coil (33), and the rotating body (2
No force is generated in the Z-axis direction for 1). When no displacement in the Z-axis direction occurs in the rotating body (21), the controller does not supply current to the coil (33), and when a displacement in the negative Z-axis direction occurs in the rotating body (2), the coil (33) 6), a current is applied in the direction of FIG. 6 (a) to apply a force Fr in the positive direction of the Z-axis to the rotating body (21).
An electric current is applied to (33) in the direction of FIG.
A force Fr in the negative axial direction is applied. Further, the magnitude of the current flowing through the coil (33) is controlled by the magnitude of the displacement of the rotating body (21) to control the magnitude of the force Fr acting on the rotating body (21). Thereby, the position of the rotating body (21) in the Z-axis direction is controlled, and the rotating body (21) is supported in a non-contact manner at the target position in the Z-axis direction.

Also in the case of the second embodiment, the controller
Two support parts (22) (23) depending on the operating condition of the rotating body (21)
Switch to use. That is, when the rotating speed of the rotating body (21) at the time of starting and stopping the rotating body (21) is low, the rotating body (21) is supported using only the first support portion (22),
During high-speed rotation, the rotating body (2
Support 1).

In the second support portion (23), the magnetic field generated by the permanent magnet (30) is uniform in the rotation direction of the rotating body (21), so that the magnetic flux density changes in the rotating direction of the rotating body (21). Does not occur. Therefore, no eddy current is generated by the rotation of the rotating body (21), and the rotation loss is extremely small. Further, since there is no need to constantly supply a current to the coil (33), power consumption is small.

When the rotating body (21) is started and stopped, the rotating body (21) is supported by the first support portion (22) using the magnetic attraction force of the electromagnets (25) and (26). And a large control force required at the time of stop is obtained.

When the rotating body (21) rotates at a high speed, the rotating body (21) is supported by the second support portion (23) using Lorentz force, so that there is no eddy current loss and high frequency response is obtained.
In addition, only when displacement of the rotating body (21) occurs, the coil (33)
The current consumption is small because the current only needs to be passed through.

When starting and stopping the rotating body (21), high-frequency response is not required. Therefore, the first supporting part (22) using the magnetic attraction of the electromagnets (25) and (26) is used to rotate the rotating body (21). Even if you support
There is no problem. When the rotating body (21) rotates at high speed, the rotating body (21)
No large control force is required because the position of the rotary body (21) is stable by using the Lorentz force.
There is no problem even if you support. In addition, when the rotating body (21) is started and stopped, the rotating body (21) is supported by the first support portion (22) using the magnetic attraction force of the electromagnets (25) and (26). And the current consumption is large, but the starting and stopping time of the rotating body (21) is very short with respect to the entire operating time of the rotating body (21), so that eddy current loss and power consumption are extremely low as a whole. small.

FIG. 7 shows a third embodiment.

FIG. 7 shows a vertical longitudinal section of an axial magnetic bearing portion of the magnetic bearing device. As in the second embodiment, this magnetic bearing device is provided with a horizontal shaft-shaped rotating body at the center in a cylindrical casing (20) which is a horizontally arranged fixed portion.
(21) is a horizontal type that rotates while being supported in a non-contact manner. Also in the description of the third embodiment, the front, rear, left, right, and control axes are defined as in the case of the second embodiment.

The axial magnetic bearing is provided with only the same support portion (23) as the second support portion (23) of the second embodiment, and the rotary body (2) is always provided only by this support portion (23). Are supported in a non-contact manner in the axial direction.

The other parts are the same as those in the second embodiment, and the same parts are denoted by the same reference numerals.

In the support portion (23), the magnetic field generated by the permanent magnet (30) is uniform in the rotation direction of the rotating body (21), so that the magnetic flux density changes in the rotating direction of the rotating body (21). Absent. Therefore, no eddy current is generated by the rotation of the rotating body (21), and the rotation loss is extremely small. Further, since there is no need to constantly supply a current to the coil (33), power consumption is small.

In the case of the horizontal type magnetic bearing as in the third embodiment, since gravity does not act in the axial direction, the control force in the axial direction by the axial magnetic bearing may be relatively small. In particular, when a conventional radial magnetic bearing that supports the rotating body in the radial direction by the magnetic attraction of an electromagnet is used for radial support, the rotating body is also supported to some extent in the axial direction by the radial magnetic bearing. It is not necessary to increase the control force in the axial direction by the magnetic bearing. Therefore, even if the rotating body (21) is always supported by the support portion (23) using Lorentz force as in the third embodiment,
The necessary control force in the axial direction can be obtained when the rotating body (21) is started or stopped, and at the time of high-speed rotation, the rotating body (21) is supported by the support portion (23) using Lorentz force. No eddy current loss, high frequency responsiveness, and coil only when displacement of rotating body (21) occurs
Since current only needs to be supplied to (33), current consumption is small.

In the second and third embodiments, the axial magnetic bearing in the horizontal type magnetic bearing device has been described.
The axial magnetic bearing according to the present invention can also be applied to a vertical type magnetic bearing device.

In the above three embodiments, a magnetic bearing device of a type in which a shaft-like rotating body arranged concentrically inside a casing as a fixed portion rotates is shown.
The present invention can also be applied to a magnetic bearing device of a type in which a cylindrical rotating body concentrically arranged outside a shaft as a fixed portion rotates.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a radial magnetic bearing portion of a magnetic bearing device according to a first embodiment of the present invention.

FIG. 2 is a horizontal sectional view taken along the line II-II in FIG.

FIG. 3 is an explanatory diagram illustrating an operation of a second support unit.

FIG. 4 is a vertical longitudinal sectional view of an axial magnetic bearing portion of a magnetic bearing device according to a second embodiment of the present invention.

FIG. 5 is a vertical cross-sectional view taken along line VV of FIG. 4;

FIG. 6 is an explanatory diagram illustrating an operation of a second support unit.

FIG. 7 is a vertical longitudinal sectional view of an axial magnetic bearing portion of a magnetic bearing device according to a third embodiment of the present invention.

[Explanation of symbols]

 (1) Casing (2) Rotating body (3) First support (4) Second support (6) Electromagnet (8a) Rotor disk (9) Permanent magnet (11) (12) (13) (14) Coil (20) Casing (21) Rotating body (22) First support (23) Second support (24) Rotor disk (25) (26) Electromagnet (29a) Outer cylinder (30) Permanent magnet (33 ) Coil

Claims (3)

[Claims] A magnetic bearing for supporting a rotating body in a non-contact manner in an axial direction or a radial direction with respect to a fixed portion, wherein the first bearing supports the rotating body by magnetic attraction of a plurality of electromagnets.
A supporting portion, and a second supporting portion for supporting the rotating body by Lorentz force generated in a coil in a magnetic field. When the rotating body is started and stopped, the rotating body is supported by the first supporting portion. A rotating body supported by the second support portion. 2. A magnetic bearing for supporting a rotating body in a non-contact manner with respect to a fixed portion in an axial direction, wherein first supporting portions are located on both axial sides of a rotor disk portion provided integrally with the rotating body. A pair of electromagnets fixedly provided on the fixed portion to magnetically attract the rotor disk portion, wherein the second support portion is concentric with the outside of the outer peripheral surface of the rotating body or the inside of the inner peripheral surface of the rotating body. A cylindrical portion provided integrally and integrally, an annular coil fixedly provided on a fixed portion so as to be concentrically located between the cylindrical portion and the opposing peripheral surface of the rotating body and through which an electric current flows, and a cylinder. 2. The magnetic bearing according to claim 1, further comprising an annular permanent magnet fixed to at least one of the portion and the opposing peripheral surface of the rotating body and having an inner peripheral surface and an outer peripheral surface having magnetic poles. 3. A magnetic bearing for supporting a rotating body in a non-contact manner in a radial direction with respect to a fixed portion, wherein the first supporting portion is fixed so as to be positioned at equal intervals in a circumferential direction around the rotating body. At least three electromagnets fixedly provided on the portion and magnetically attracting the rotating body, and two rotor disks provided with a second support concentrically and integrally at a predetermined interval in the axial direction. And at least three sets of coils, which are fixedly provided on the fixed portion so as to be positioned at equal intervals in the circumferential direction and in which a current in the circumferential direction flows through a portion located between the two rotor disk portions, 2
2. The magnetic bearing according to claim 1, further comprising an annular permanent magnet fixed to at least one of the opposing surfaces of the two rotor disk portions and having magnetic poles at both ends in the axial direction.