JPH08219157A - Magnetic bearing device - Google Patents

Abstract

PURPOSE: To ensure a large load capacity, and enable stable operation. CONSTITUTION: A superconductive magnet bearings 23, 23 and a passive type magnet bearing 24 are arranged between a flange 15 fixed to a rotary shaft 2 and a bearing housing 17. The superconductive magnet bearings 23, 23 consist of first permanent magnets 16a to 61d, 16a' to 16d' which are fixed to a flange 15 side, and superconductors 13, 13 which are fixed to a bearing housing 17 side. The passive type magnet bearing 24 consists of aferromagnetic body such as a plate 20 which is fixed to the flange 15 side, and a second permanent magnet 21 which is fixed to the bearing housing 17 side. Bearing rigidity of the superconductive magnetic bearing 23 is strengthen more than that of the passive type magnet bearing 24 so as to suppress unstable factor by the passive type magnet bearing 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The magnetic bearing device according to the present invention comprises:
For example, a state in which surplus power at night is converted into kinetic energy and stored, and during the daytime this kinetic energy is converted into electric energy and is taken out to form an electric power storage device, such as a superconducting flywheel device, etc. Used in.

[0002]

2. Description of the Related Art A flywheel with a large moment is fixed to a rotary shaft as a device which can be installed in a small-scale business office or a general household to store surplus power at night, and a motor also serving as a generator is attached to the rotary shaft. Power storage devices are being researched. In the case of this power storage device, by supplying surplus power to the generator / motor at night, the rotary shaft and the flywheel are rotated, the surplus power is converted into kinetic energy, and the rotary motion of the flywheel is performed. Store as energy. Then, during the daytime, based on this rotational kinetic energy, the electric generator / motor is used to generate electric power, and the electric power is taken out and used.

In order to improve the efficiency of a power storage device using such a flywheel, a bearing device for rotatably supporting the flywheel is used which has a low rotational resistance and a low energy required for operation. There is a need to. Therefore, a power storage device using a superconducting magnetic bearing device as a bearing device has been conventionally proposed as described in Japanese Patent Laid-Open No. 5-248437. Figure 2
Shows a power storage device incorporating the superconducting magnetic bearing device described in this publication.

A rotary shaft 2 is arranged vertically in the central portion of a vacuum housing 1 which is hermetically sealed. A holding cylinder 3 is fixed inside the vacuum housing 1 so as to surround the rotary shaft 2. Then, active magnetic bearings 6, 6 composed of magnetic rings 4, 4 and electromagnets 5, 5 are provided between the inner peripheral surface of the lower half of the holding cylinder 3 and the outer peripheral surface of the intermediate portion of the rotary shaft 2, respectively. The rotary shaft 2 is provided so as to be positioned in the radial direction. A rotor 7 is provided between the inner peripheral surface of the upper half of the holding cylinder 3 and the upper end of the rotary shaft 2.
A generator-combined motor 9 including a stator 8 and a stator 8 is provided.

A flywheel 10, which is a rotating member, is fixed to the lower end of the rotary shaft 2, and an annular permanent magnet 11 is fixed to the lower surface of the flywheel 10.
The permanent magnet 11 is magnetized in the axial direction (vertical direction in FIG. 2) and is fixed concentrically with the rotary shaft 2 which is the rotation center of the flywheel 10. Furthermore,
A cooling jacket 12, which also serves as a fixing member, is fixed to the bottom surface of the vacuum housing 1, and the upper surface of a superconductor 13 provided on the upper surface of the cooling jacket 12 is connected to the permanent magnet 11
Facing the underside of. It is desirable that the superconductor 13 has an annular shape similar to the permanent magnet 11 and is arranged concentrically with the permanent magnet 11. However, if it is difficult to make the annular shape, a plurality of superconductors each made of a disk shape, an arc shape, or the like are arranged at equal intervals on an arc concentric with the permanent magnet 11. A coolant such as liquid nitrogen is allowed to flow freely in the cooling jacket 12 so that the superconductor 13 can be brought into a superconducting state. Superconductor 13
Is superconducting, the pinning effect prevents the distance between the superconductor 13 and the permanent magnet 11 from changing. Therefore, the superconductor 13 and the permanent magnet 11 form a non-contact type superconducting thrust magnetic bearing 14.

The operation of the conventional power storage device constructed as described above is as follows. When the surplus power is stored at night, etc., by supplying the surplus power to the stator 8 of the generator / motor 9, the rotary shaft 2 and the flywheel 10 are provided.
To rotate. At this time, by the active magnetic bearing 6,
Positioning of the rotating shaft 2 in the radial direction
A coolant is sent into the cooling jacket 12 to cool the superconductor 13. When the superconductor 13 is cooled and becomes in the superconducting state, the magnetic flux emitted from the permanent magnet 11 is transferred to the superconductor 1.
Due to the so-called pinning effect, which is constrained within 3, the force that prevents the permanent magnet 11 from moving in the axial and radial directions with respect to the superconductor 13 acts. By this force, thrust force and radial force acting on the rotary shaft 2 and the flywheel 10 are supported. In this way, with the active magnetic bearing 6 and the superconducting thrust magnetic bearing 14 functioning, the rotary shaft 2 and the flywheel 1 are
0 is supported in a floating state. Therefore, the resistance against the rotation of these two members 2 and 10 is extremely small.

Since the rotational speeds of the rotary shaft 2 and the flywheel 10 gradually increase with the energization of the stator 8, the electric power can be stored in the state of being converted into mechanical kinetic energy. Since the rotating shaft 2 and the flywheel 10 are provided in the vacuum housing 1, the surface of the rotating member and the air do not rub against each other, and once the rotating speed of the flywheel 10 rises, the rotating speed of the generator is increased. Unless the electric power is taken out by the dual-purpose motor 9, there is almost no decrease. When the stored energy is taken out and used in the daytime, the stator 8 is connected to a load (electric equipment). As a result, electric power is generated in the stator 8 based on the rotational movement of the flywheel 10.

Although not shown, the non-contact type radial bearing for preventing the radial displacement of the rotary shaft 2 may be a superconducting magnetic bearing. In this case,
The magnetic rings 4, 4 are provided on the outer peripheral surface of the intermediate portion of the rotating shaft 2.
In place of the electromagnets 5 and 5, a superconductor is fixed to the inner peripheral surface of the lower half of the holding cylinder 3 while fixing a diametrically or axially magnetized annular permanent magnet.
A cooling jacket for cooling the superconductor is provided inside the holding cylinder 3.

[0009]

By the way, for example, when the weight of the flywheel 10 is made large (heavy) in order to improve the electric power storage capacity of the electric power storage device configured and operated as described above, the superconducting thrust is increased. Magnetic bearing 1
It is necessary to increase the load capacity of No. 4. Also, when supporting a large thrust load applied to the rotary shaft of various mechanical devices, a large load capacity is still required. However,
At present, there is a limit to the load capacity of the superconducting thrust magnetic bearing 14 that can be practically used, and the flywheel 10 that can be supported only by the superconducting thrust magnetic bearing 14 is used to improve the performance of the power storage device, or a large capacity is required. It was difficult to support the rotating shaft to which the thrust load is applied.

In order to make up for the lack of load capacity of the superconducting thrust magnetic bearing 14 as described above, in addition to the superconducting thrust magnetic bearing 14 between the rotating member such as the flywheel 10 and the fixed member such as the housing, the passive magnetic It is also possible to incorporate a bearing. However, the spring constant of the passive magnetic bearing, which is composed of the ferromagnetic portion and the permanent magnet and has only the action of attracting the ferromagnetic portion toward the permanent magnet, is inherently negative, and the passive type magnetic bearing has a negative spring constant. The bearing action of the magnetic bearing becomes unstable. Therefore, it is difficult to stably support the rotating member simply by adding the passive magnetic bearing to the superconducting thrust magnetic bearing 14. The magnetic bearing device of the present invention was invented in view of such circumstances.

[0011]

SUMMARY OF THE INVENTION A magnetic bearing device of the present invention comprises a rotating member, a fixed member facing the rotating member, and a superconducting magnet provided between the rotating member and the fixed member. A bearing and a passive magnetic bearing. The superconducting magnetic bearing among them is a ring-shaped or disc-shaped first permanent magnet fixed to a part of the rotary member concentrically with the rotation center of the rotary member, and faces the first permanent magnet. And a superconductor supported in part by the fixing member. In the passive magnetic bearing, a part of the rotating member that is concentric with the rotating member at a portion deviated from the first permanent magnet, and a part of the fixed member are the superconducting parts. And a second permanent magnet fixed to a portion separated from the body. Further, the bearing rigidity of the superconducting magnetic bearing is larger than that of the passive magnetic bearing.

[0012]

According to the magnetic bearing device of the present invention configured as described above, a rotating member that is heavy can be stably supported. That is, since the weight of the rotating member is supported by both the superconducting magnetic bearing and the passive magnetic bearing, the load capacity of the entire magnetic bearing can be sufficiently secured. Further, since the bearing rigidity of the superconducting magnetic bearing is larger than that of the passive magnetic bearing, the instability of the passive magnetic bearing can be suppressed. That is,
The spring constant of the superconducting magnetic bearing that prevents the distance between the permanent magnet and the superconductor from changing due to the so-called pinning effect that keeps the magnetic flux emitted from the permanent magnet by the superconductor is positive. The bearing tends to stabilize the rotating member. In the case of the magnetic bearing device of the present invention,
The bearing rigidity of the superconducting magnetic bearing is larger than that of the passive magnetic bearing, and therefore the spring constant K of the passive magnetic bearing is K.
The absolute value of _J | K _J | is an absolute value of the spring constant K _T of the superconducting magnetic bearings | K _T | smaller than _{(| K J | <| K} T |).
As a result, the spring constant of the magnetic bearing device as a whole becomes positive, and the rotating member becomes stable during operation.

It should be noted that the load capacity of the passive magnetic bearing is ensured,
Moreover, in order to reduce the bearing rigidity of this passive magnetic bearing, for example, the facing area between the ferromagnetic portion and the second permanent magnet is increased, and the distance between the ferromagnetic portion and the second permanent magnet is increased. To increase. By increasing the facing area, the magnetic attraction force acting between the ferromagnetic material portion and the second permanent magnet increases, and the load capacity increases. Increasing the strength of the permanent magnet (increasing the magnetic flux density) is also effective in increasing the load capacity. Further, by increasing the distance between the ferromagnetic part and the second permanent magnet, this distance, that is, the load capacity due to the change in the bearing clearance (the magnetic attraction force acting between the ferromagnetic part and the second permanent magnet). ) Changes less and the bearing rigidity decreases.

[0014]

FIG. 1 shows an embodiment of the present invention. A flange 15 that constitutes a rotating member together with the rotating shaft 2 is fixed to the outer peripheral surface of the intermediate portion of the rotating shaft 2 that is the rotating member.
On each of the upper and lower surfaces of the inner peripheral side half of the flange 15, a plurality of first permanent magnets 16a to 16d and 16a ', each of which is formed in an annular shape (four in total in the illustrated example, eight in total) are formed.
16d 'is supported and fixed. Each of these first permanent magnets 1
6a to 16d and 16a 'to 16d' are magnetized in the axial direction (vertical direction in FIG. 1). The magnetizing directions of the respective first permanent magnets 16a to 16d and 16a 'to 16d' are the first permanent magnets 16a to 16d, 1 at the same position in the diametrical direction.
6a 'to 16d' have upper and lower surfaces in opposite directions. Also, when viewed from the same plane, the first permanent magnets 16a, 16b (or 16
a ', 16b') have the same magnetizing directions, and the two first permanent magnets 16c, 16d (or 16 ') located in the middle.
c ', 16d') are magnetized in the opposite direction.
Therefore, the two first permanent magnets 16b, 16d (or 16b ', 16) on the outer peripheral side are formed on the upper and lower surfaces of the flange 15.
The two first permanent magnets 16 on the inner peripheral side are provided between the end faces of d ').
High-density magnetic flux flows between the end faces of a and 16c (or 16a ′ and 16c ′).

On the other hand, a bearing housing 17 which is a fixing member is provided around the rotary shaft 2 and the flange 15. Inside the bearing housing 17, a bearing space 1 having an inner dimension slightly larger than the outer dimension of the flange 15 is provided.
8 are provided. The annular superconductors 13, 13 are formed on the upper and lower surfaces of the inner half of the bearing space 18, respectively.
Is fixed. The lower surface or the upper surface of each of these superconductors 13, 13 is connected to each of the first permanent magnets 16a to 16d
A pair of upper and lower superconducting magnetic bearings 23, 23 are formed so as to face the upper end surface or the lower end surface of a'-16d 'via the first bearing gaps 19a, 19b. Although not shown, a cooling jacket is provided in the bearing housing 17 so that the superconductor 13 can be cooled to a temperature at which it is in a superconducting state.

Further, an annular plate 20 made of a ferromagnetic material such as a steel plate is fixed to a portion of the flange 15 near the outer periphery of the upper surface, and the portion near the outer periphery of the upper surface serves as a ferromagnetic material portion. Then, an annular second permanent magnet 21 is fixed to a portion of the bearing space 18 near the outer periphery of the upper surface, and the lower surface of the second permanent magnet 21 and the upper surface of the plate 20 are opposed to each other via a second bearing gap 22. Let's take a passive magnetic bearing 2
Make up 4. The thickness dimension T of the second bearing gap 22
₂₂ is larger than the thickness dimension T ₁₉ of the upper first bearing gap 19a (T ₂₂ > T ₁₉ ).

When the magnetic bearing device of the present invention having the above-described structure is operated, for example, the superconductor 13 is not cooled, and the superconductor 13 is raised to the rotary shaft 2 while being in the normal conduction state. A directional force is applied to bring the upper surface of the flange 15 closer to the upper surface of the bearing space 18. Next, the superconductor 1
After cooling 3 to bring this superconductor 13 into a superconducting state, the force in the levitation direction applied to the rotating shaft 2 is released. As a result, the rotating shaft 2 and the flange 15 are floated by the force acting between the superconductors 13 and 13 and the first permanent magnets 16a to 16d and 16a 'to 16d' based on the pinning force of the superconductor 13. Supported by the state. The amount of magnetic flux flowing between the end faces of the first permanent magnets 16a to 16d and 16a 'to 16d' and pinned in the superconductors 13 and 13 is large, and the bearing rigidity of the superconducting magnetic bearing is sufficient. growing.

Further, as described above, the rotary shaft 2 and the flange 15
The force for supporting the above in a floating state can also be obtained by the magnetic attraction force acting between the plate 20 and the second permanent magnet 21. Therefore, it is possible to sufficiently secure the load capacity of the magnetic bearing as a whole, to support a heavy flywheel, or to support a rotating shaft to which a large thrust load is applied.

Furthermore, the bearing rigidity of the superconducting magnetic bearings 23, 23, which are respectively composed of the superconductors 13, 13 and a plurality of permanent magnets 16a-16d, 16a'-16d ',
It is larger than the bearing rigidity of the passive magnetic bearing 24 constituted by the plate 20 and the second permanent magnet 21. That is, since the facing area between the plate 20 and the second permanent magnet 21 is large, the magnetic attraction force acting between the plate 20 and the second permanent magnet 21 is large, and the load capacity of the passive magnetic bearing 24 is large. Although sufficiently large, since the thickness T ₂₂ of the second bearing gap 22 existing between the plate 20 and the second permanent magnet 21 is large, the bearing rigidity of the passive magnetic bearing 24 is reduced. Therefore, the instability of the passive magnetic bearing can be suppressed by the mechanism as described above. still,
As shown in FIG. 2, when the present invention is applied to a structure in which the flywheel 10 is fixed to the end of the rotary shaft 2, the first permanent magnet and the superconductor may be disc-shaped.

[0020]

Since the magnetic bearing device of the present invention is constructed and operates as described above, a sufficiently large load capacity can be secured and a large load applied to the rotating portion can be supported, and stable operation can be achieved. This makes it possible to improve the performance of various mechanical devices having rotating parts.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a power storage device incorporating a conventionally known superconducting magnetic bearing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum housing 2 Rotating shaft 3 Holding cylinder 4 Magnetic ring 5 Electromagnet 6 Active magnetic bearing 7 Rotor 8 Stator 9 Generator / motor 10 Flywheel 11 Permanent magnet 12 Cooling jacket 13 Superconductor 14 Superconducting thrust magnetic bearing 15 Flange 16a-16d , 16a 'to 16d' First permanent magnet 17 Bearing housing 18 Bearing space 19a, 19b First bearing gap 20 Plate 21 Second permanent magnet 22 Second bearing gap 23 Superconducting magnetic bearing 24 Passive magnetic bearing

Claims (1)

[Claims] 1. A rotary member, a fixed member provided to face the rotary member, and a superconducting magnetic bearing and a passive magnetic bearing provided between the rotary member and the fixed member. The superconducting magnetic bearing of the above, the annular or disc-shaped first permanent magnet fixed to a part of the rotary member concentrically with the rotation center of the rotary member, and the fixed member in a state of facing the first permanent magnet. And a superconductor supported on a part thereof, wherein the passive magnetic bearing is a ferromagnetic part provided concentrically with the rotating member at a part of the rotating member that is deviated from the first permanent magnet. And a second permanent magnet fixed to a part of the fixing member which is separated from the superconductor, and the bearing rigidity of the superconducting magnetic bearing is larger than the bearing rigidity of the passive magnetic bearing. .