JPH09303395A - Magnetic bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the stabilized non-contact floating condition even in the case of single unit without using a displacement sensor and a control unit by forming a magnetic closing circuit of a magnetic bearing unit main body and a projecting part inside of a rotary cylinder, and generating the eddycurrent in a magnetic flux diaphragm. SOLUTION: In this magnetic bearing device, in the case where a rotary cylinder 2 is displaced in the radial direction in relation to a fixed shaft 1, bearing spaces 8, 8 between the peripheral edge of a pair of projecting parts 5a, 5a in the vertical direction in both ends of a magnetic bearing unit main body 3 fixed to the fixed shaft 1 and the inner peripheral edge of a pair of projecting parts 7, 7 in the vertical direction fixed to the inner peripheral surface of the rotary cylinder 2 are changed. Density of magnetic flux in the magnetic closing circuit is changed. In response to a change of the magnetic flux density, eddycurrent proportioned to the time differential of change is flowed in a thin film made of the excellent electrical conductor, which forms the magnetic flux diaphragm 6. Sufficient strong eddycurrent is obtained by laminating multiple pieces of thin film so as to work in the direction for hindering the displacement of the rotary shaft 2 in the radial direction. Consequently, the fixed shaft 1 and the rotary shaft 2 are maintained in the non-contact floating condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The magnetic bearing device according to the present invention comprises:
It is used to rotatably support a rotating shaft or rotor that rotates at ultra-high speed in various experimental devices in a non-contact state.

[0002]

2. Description of the Related Art In order to support a rotating shaft or a rotor that rotates at an extremely high speed, a general rolling bearing may be insufficient in capacity. As a bearing used in such a case, for example, a control type magnetic bearing device as described in Japanese Patent Publication No. 32868/1990 or a passive magnetic bearing device as described in Japanese Patent Laid-Open No. 55-57716. There is a device. Among them, the control type magnetic bearing device uses a plurality of electromagnets and a displacement sensor, and controls the energization state to each electromagnet according to the displacement of the rotating body, thereby supporting the rotating body in a non-contact state. . Further, the passive magnetic bearing device uses a plurality of permanent magnets, and supports the rotating body in a non-contact state by utilizing the attractive force or repulsive force of the permanent magnets.

[0003]

The controlled magnetic bearing device is sufficiently satisfactory in performance, but it requires a displacement sensor and a controller with excellent responsiveness, and is based on energization of an electromagnet. Since the posture of the rotating body is controlled by this, it is inevitable that the manufacturing cost and running cost increase.
In addition, the passive magnetic bearing device, according to Earnshow's theorem,
A single unit cannot maintain a stable non-contact floating state. Therefore, it is necessary to use the bearing together with other bearings, and the bearing device as a whole is complicated and expensive. The magnetic bearing device of the present invention has been invented in view of such circumstances, and has a structure capable of maintaining a stable non-contact floating state without using a displacement sensor or controller that causes high cost. It was invented to realize it.

[0004]

A magnetic bearing device of the present invention comprises a first member and a second member which are arranged concentrically with each other and rotate relative to each other around a predetermined center of rotation; A magnetic bearing unit main body fixed to an annular space portion having its center as its center, a part of the second member faces both ends of the magnetic bearing unit main body, and the center of rotation is its center. A pair of protrusions fixed to the first member in a state of protruding toward the first member is provided on the circular portion.
The magnetic bearing unit body includes at least one permanent magnet and at least one permanent magnet, which are arranged in series along the magnetization direction of the permanent magnet and are each made of a ferromagnetic material. It is composed of a yoke and a magnetic flux diaphragm. Further, both ends of the magnetic bearing unit main body project toward the pair of projecting portions to form a bearing gap between the projecting portions. Further, in the second member, at least the pair of protrusions and a portion between the two protrusions are made of a ferromagnetic material, and include the magnetic bearing unit main body and the pair of protrusions. It is assumed that a magnetic closed circuit is constructed. Further, the magnetic flux restrictor is constructed by laminating thin films made of a good electric conductor.

It is preferable to employ one or more of the following constitutions. At least a part of the first member on which the magnetic bearing unit body is mounted is made of a non-magnetic material. A thin film made of a good electric conductor that constitutes the magnetic flux restrictor is divided into a plurality of pieces in the circumferential direction. An initial centering auxiliary bearing for aligning the central axes of the first and second members between the first member and the second member in a state where the relative rotation of the two members is stopped. To provide.

[0006]

In the magnetic bearing device of the present invention constructed as described above, the relative displacement between the first member and the second member is prevented by the eddy current flowing in the magnetic flux restrictor body constituting the magnetic bearing unit body. That is, when the first member and the second member are about to be displaced relative to each other, the gap between the both ends of the magnetic bearing unit main body fixed to the first member and the pair of protrusions fixed to the second member. The thickness dimension of the bearing clearance changes. Then, due to this change, the magnetic flux density in the magnetic closed circuit including the magnetic bearing unit main body and the pair of protrusions changes. Corresponding to this change in the magnetic flux density, an eddy current proportional to the time derivative of the change flows in the thin film made of a good electric conductor that constitutes the magnetic flux restrictor. Since the magnetic flux restrictor is made by laminating thin films made of a good electric conductor, the eddy current is sufficiently strong. Also, this eddy current acts in a direction to prevent relative displacement between the first member and the second member. Therefore, the first member and the second member are held in the non-contact floating state.

If at least a part of the first member on which the magnetic bearing unit main body is mounted is made of a non-magnetic material, the magnetic flux flowing between both end faces of the permanent magnet in the magnetizing direction is It prevents flow inside the member, increases the density of the magnetic flux flowing in the magnetic closed circuit, and helps strengthen the eddy current. Further, if the thin film made of a good electric conductor that constitutes the magnetic flux restrictor is divided into a plurality of pieces in the circumferential direction, the thickness of the bearing gap tends to be uneven in the circumferential direction. If it becomes, the eddy current acts in a direction to prevent this tendency. Further, between the first member and the second member, in the state where the relative rotation of these both members is stopped, initial centering for matching the central axes of these first and second members If an auxiliary bearing is provided, the central axes of these two members can be made to coincide with each other when stopped or at low speed rotation.

[0008]

1 and 2 show a first embodiment of the present invention. In this example, the present invention is applied to a radial bearing. The fixed shaft 1, which is the first member,
It is made of non-magnetic material such as copper and aluminum alloy, and is supported and fixed vertically. In addition, the rotary cylinder 2 which is the second member
Are made of a ferromagnetic material such as steel, and are arranged concentrically with the fixed shaft 1 around the intermediate portion of the fixed shaft 1. Therefore,
The central axis of the fixed shaft 1 becomes the center of rotation of the rotary cylinder 2.

A magnetic bearing unit body 3 is externally fitted and fixed to the outer peripheral surface of the intermediate portion of the fixed shaft 1. Therefore, the magnetic bearing unit main body 3 is fixed to the annular space (virtual space) centering around the rotation center. Such a magnetic bearing unit main body 3 is arranged in the axial direction of the fixed shaft 1 (see FIG.
(A top-bottom direction of) and one permanent magnet 4 magnetized,
A pair of yokes 5 and 5 and a magnetic flux diaphragm body, which are arranged in series along the magnetizing direction of the permanent magnet 4 (the vertical direction in FIG. 1) and are each made of a ferromagnetic material such as mild steel. 6
It is composed of In the case of this example, each of the yokes 5 and 5 is
Has an L-shaped cross section and is entirely formed in an annular shape. The two yokes 5 and 5 are arranged on both upper and lower sides of the permanent magnet 4 in a state in which a part of each of them is projected outward in the diametrical direction. The lower end surface of the one yoke 5 (upper part in FIG. 1) is directly brought into contact with the upper end surface of the permanent magnet 4.
Further, the magnetic flux throttle body 6 is sandwiched between the upper end surface of the other yoke 5 (downward in FIG. 1) and the lower end surface of the permanent magnet 4.

As shown in FIG. 2, the magnetic flux restrictor body 6 is formed by laminating a large number of thin films 9, 9 each made of a good electric conductor such as aluminum or copper. Each of the thin films 9 and 9 is formed in an arc shape, and is arranged in an annular shape with a gap between the thin films 9 and 9 adjacent to each other in the circumferential direction. Further, the thin films 9 and 9 adjacent to each other in the stacking direction are stacked with an insulating layer interposed therebetween, and the phases thereof are the same. Therefore, the thin films 9 and 9 that are adjacent to each other in the circumferential direction are insulated from each other.

On the other hand, on the inner peripheral surface of the rotary cylinder 2, the respective yokes 5, which are both end portions of the magnetic bearing unit body 3,
A pair of projecting portions 7, 7 is formed on the portion of 5 facing the projecting portions 5a, 5a over the entire circumference. The amount of protrusion of each of these protrusions 7, 7 from the inner peripheral surface does not change over the entire circumference. Therefore, the inner peripheral edge of each of the projecting portions 7, 7 is fixed to a circular portion having the center of rotation as its center so as to project toward the fixed shaft 1. Then, the yokes 5 and 5 which are both ends of the magnetic bearing unit main body 3.
The outer peripheral edges of the projecting portions 5a, 5a and the pair of projecting portions 7,
Bearing gaps 8 and 8 are respectively formed between the inner peripheral edge and the inner peripheral edge of 7. Since the rotary cylinder 2 having the pair of protrusions 7, 7 is made of a ferromagnetic material, a magnetic closed circuit including the magnetic bearing unit main body 3 and the pair of protrusions 7, 7 is formed. Composed.

In the magnetic bearing device of the present embodiment constructed as described above, the relative displacement between the fixed shaft 1 and the rotary cylinder 2 is prevented by the eddy current flowing in the magnetic flux throttle body 6 which constitutes the magnetic bearing unit body 3. . That is, when the rotary cylinder 2 is to be displaced in the radial direction with respect to the fixed shaft 1, a pair of upper and lower protrusions 5a existing at both ends of the magnetic bearing unit body 3 fixed to the fixed shaft 1. Outer peripheral edge of 5a and rotating cylinder 2
The thickness dimension of the bearing gaps 8, 8 between the inner peripheral edges of the pair of upper and lower protrusions 7, 7 fixed to the inner peripheral surface of the bearing changes. And
Due to this change, the magnetic bearing unit body 3 and the
The magnetic flux density in the magnetic closed circuit including the pair of protrusions 7, 7 changes.

Corresponding to this change in the magnetic flux density, an eddy current proportional to the time derivative of the above change flows through the thin films 9 and 9 made of a good electrical conductor which constitute the magnetic flux diaphragm 6. Since the magnetic flux restrictor 6 is made by laminating a large number of thin films 9 made of a good electrical conductor, the eddy current is sufficiently strong. Further, the eddy current acts in a direction to prevent the rotary cylinder 2 from being displaced in the radial direction. Therefore, the fixed shaft 1 and the rotary cylinder 2 are held in a non-contact floating state. Particularly, in the illustrated example, the thin films 9 and 9 forming the magnetic flux restrictor body 6 are divided into a plurality of pieces in the circumferential direction, so that the force to be blocked can be sufficiently increased.
That is, when the rotary cylinder 2 is about to be displaced in the radial direction, the thickness dimension of each of the bearing gaps 8, 8 becomes large on one side in the circumferential direction, and the thin film 9 facing this one side portion,
The density of the magnetic flux flowing through the thin film 9 becomes low and becomes small on the other side in the circumferential direction, and the density of the magnetic flux flowing through the thin films 9, 9 facing the other side part becomes high. Therefore, the eddy current generates a resistance force for increasing the bearing gaps 8 on one side in the circumferential direction and a resistance force for decreasing the bearing gaps 8 on the other side in the circumferential direction. As a result, the force for blocking is sufficiently increased.

In the case of the structure of this example, the rotary cylinder 2
Is prevented from being displaced in the thrust direction by a magnetic attraction force acting between the protrusions 5a of the yokes 5 and 5 and the protrusions 7 of the inner peripheral surface of the rotary cylinder 2.

FIG. 3 shows a second embodiment of the present invention.
An example is shown. In the case of this example, between the pair of upper and lower yokes 5 and 5 forming the magnetic bearing unit body 3a,
A pair of upper and lower permanent magnets 4 and 4 are provided. Magnetic flux diaphragm 6
Is sandwiched between these two permanent magnets 4, 4.
Other configurations and operations are similar to those of the above-described first example.

Next, FIGS. 4 to 5 show a third example of the embodiment of the present invention. In this example, the present invention is applied to a thrust bearing. A flange 10 made of a non-magnetic material is fixed to the outer peripheral surface of the intermediate portion of the fixed shaft 1 which is the first member. The magnetic bearing unit main body is provided on one surface (lower surface in FIG. 4) of the flange 10 in an annular space (virtual space) whose center is the central axis of the fixed shaft 1 which is the rotation center of the rotating plate 11 described later. 3b is fixed. In the case of the present example, the magnetic bearing unit main body 3b is composed of a pair of permanent magnets 12a and 12b, yokes 13a and 13b, and one magnetic flux diaphragm 14. Of these, the pair of permanent magnets 12a and 12b are each formed in an annular shape and are magnetized in the axial direction of the fixed shaft 1 (vertical direction in FIG. 4), and on a concentric circle centered on the central axis. It is located in the part. The pair of yokes 13a and 13b are each formed in a circular ring shape and are arranged on a concentric circle having the central axis as its center. Also, the yoke 1 on the inner diameter side
One surface of 3a (the lower surface in FIG. 1) near the inner diameter is on one end surface (the upper end surface in FIG. 1) of the permanent magnet 12a on the inner diameter side in the magnetization direction, and the outer surface of the yoke 13b on the outer diameter side is on the outer diameter side. Are abutted on one end surface of the permanent magnet 12b in the magnetizing direction. Further, as shown in FIG. 5, the magnetic flux restrictor body 14 is constituted by laminating a large number of thin films 9a, 9a each formed in a strip shape. Each of these thin films 9a, 9
“A” is arranged in a cylindrical shape with a gap between the thin films 9a, 9a adjacent to each other in the circumferential direction. Further, the thin films 9a, 9a adjacent to each other in the diametrical direction are laminated with an insulating layer interposed therebetween, and the phases thereof are the same. Therefore, the thin films 9a, 9a adjacent to each other in the circumferential direction are
They are insulated from each other.

On the other hand, it is a second member, and is one surface (upper surface in FIG. 4) of the rotating plate 11 which is made of a ferromagnetic material such as a mild steel plate and has a ring shape as a whole, and at both ends of the magnetic bearing unit body 3b. A pair of protrusions 7 is provided in a portion facing the other end surface (lower end surface in FIG. 4) of the permanent magnets 12a and 12b in the magnetization direction.
a and 7a on a concentric circle whose center is the above-mentioned central axis,
It is formed all around. These protrusions 7a, 7a
The amount of protrusion from the above-mentioned one surface does not change over the entire circumference.
Then, bearing gaps 8a and 8a are formed over the entire circumference between the other end faces of the permanent magnets 12a and 12b in the magnetization direction and the upper end faces of the pair of protrusions 7a and 7a, respectively. There is. Rotating plate 11 formed with the pair of protrusions 7a, 7a
Since is made of a ferromagnetic material, a magnetic closed circuit is formed including the magnetic bearing unit body 3b and the pair of protrusions 7a, 7a.

Also in the magnetic bearing device of the present example configured as described above, as in the case of the above-described first example, the fixed shaft 1 is caused by the eddy current flowing in the magnetic flux restrictor body 14 constituting the magnetic bearing unit body 3b. And relative displacement between the rotary plate 11 and the rotary plate 11 is prevented.
That is, when the rotary plate 11 is about to be displaced in the thrust direction with respect to the fixed shaft 1, the rotary plate 11 is present at both ends of the magnetic bearing unit body 3b fixed to the flange 10.
The thickness dimensions of the bearing gaps 8a and 8a between the other end faces of the pair of permanent magnets 12a and 12b in the magnetizing direction and the inner peripheral edges of the pair of protrusions 7a and 7a fixed to one surface of the rotating plate 11 are changed. To do.
Then, the fixed shaft 1 and the rotary plate 11 are held in the non-contact floating state by the same action as in the case of the first example described above.

Also in the case of this example, since the thin films 9a, 9a constituting the magnetic flux restrictor body 14 are divided into a plurality of pieces in the circumferential direction, the rotary plate 11 is arranged with respect to the central axis. If there is a tendency to tilt, there is a force that prevents this. That is, when the rotating plate 11 tends to incline, the bearing gaps 8a, 8a tend to be large in part in the circumferential direction and small in other parts. Therefore, the eddy current flowing in the magnetic flux restrictor 14 generates a resistance force for increasing the bearing gaps 8a, 8a in a part in the circumferential direction, and a resistance for decreasing the same in the other parts. As a result, the rotary plate 11 is prevented from inclining with respect to the central axis.

Next, FIG. 6 shows a fourth embodiment of the present invention.
An example is shown. In this example, the structure of the second example shown in FIG. 3 is applied to a thrust bearing. That is, in the case of this example, between the pair of yokes 13a 'and 13b' on the inner diameter side and the outer diameter side that form the magnetic bearing unit body 3c, each of which is magnetized in the diameter direction, A pair of permanent magnets 12a 'and 12b' on the outer side and the outer diameter side are provided. The magnetic flux diaphragm 14 is composed of both permanent magnets 12a ′, 1
It is sandwiched between 2b's. Other configurations and operations are similar to those of the above-described third example.

Next, FIG. 7 shows a fifth embodiment of the present invention.
An example is shown. In this example, the structure of the above-described first example is improved to strengthen the force for preventing the displacement in the thrust direction, and the magnetic bearing unit body 3'is fixed to the fixed housing 15 made of a non-magnetic material which is the first member. It is fixed to the inner peripheral surface of the and the protrusions 7 ′ and 7 ′ are attached to the rotary shaft 1 made of a ferromagnetic material which is the second member.
6 is fixed to the outer peripheral surface. Each of the yokes 5 ', 5'constituting the magnetic bearing unit body 3'has a plurality of recessed grooves 17, 17 on the inner peripheral surface thereof, and each of the projecting portions 7', 7'has a plurality of recessed grooved surfaces. By forming 18, 18 respectively, the cross-sectional shape of each peripheral surface portion is made uneven. Further, these two peripheral surfaces are arranged so that their respective convex portions face each other. By making the shape of these both peripheral surfaces as described above, the bearing gap 8 between these both peripheral surfaces,
8, the density of the magnetic flux existing in 8 is partially increased, and the magnetic attraction force acting between these peripheral surfaces is increased.
The force that prevents 6 from displacing in the thrust direction is increased.

Next, FIG. 8 shows a sixth embodiment of the present invention.
An example is shown. In this example, the structure of the third example described above is improved to enhance the force for preventing the displacement in the radial direction, and the magnetic bearing unit body 3b 'is fixed to the fixed housing made of the non-magnetic material which is the first member. A flange 10 made of a ferromagnetic material, in which protrusions 7a 'and 7a' are fixedly provided on the outer peripheral surface of the rotating shaft 16 which is the second member, on one surface (upper surface in FIG. 8) of 15a.
It is fixed to one surface (a lower surface in FIG. 8) of a. A plurality of recessed grooves 20, 2 are formed on the tip surfaces of the respective auxiliary yokes 19a, 19b constituting the magnetic bearing unit body 3b '.
By forming a plurality of concave grooves 21, 21 on the tip surface of each of the protrusions 7a ', 7a', the cross-sectional shape of each tip surface portion is made uneven. Further, both of these tip surfaces are made to face each other with their respective convex portions. By making the shapes of both of these tip surfaces as described above, the bearing gaps 8a, 8a between these two tip surfaces are formed.
The density of the magnetic flux existing in the part of the rotary shaft 1 is increased to partially increase the magnetic attraction force acting between the two end surfaces.
The force that prevents 6 from being displaced in the radial direction is increased. Further, in the case of this example, the area of the magnetic flux restrictor body 14 is increased by devising the shapes of the yokes 13a 'and 13b' constituting the magnetic bearing unit body 3b ',
The force that prevents the displacement in the thrust direction based on the eddy current generated in the magnetic flux throttle body 14 is also increased.

Next, FIGS. 9 to 10 show a seventh example of the embodiment of the present invention. In this example, the housing 23 that is the first member and one end portion of the rotary shaft 16 that is the second member (see FIGS.
10) and an electric motor 22 for rotatably driving the rotating shaft 16 and an initial centering auxiliary bearing 24 between the housing 23 and the rotating shaft 16. is there. The magnetic bearing which is the object of the present invention is the fourth bearing shown in FIG. 6 between the lower surface of the top plate 25 of the housing 23 and the upper surface of the flange 10 fixed to the outer peripheral surface of the upper end portion of the rotary shaft 16. A thrust type magnetic bearing in which the structure of the example is turned upside down is provided. Further, between the inner peripheral surface of the intermediate portion of the housing 23 and the outer peripheral surface of the intermediate portion of the rotary shaft 16, a radial type magnetic bearing having the structure of the second example shown in FIG. It is provided. Since the structure and operation of each of these magnetic bearings are the same as the structures of the above-mentioned fourth and second examples, the corresponding parts will be denoted by the same reference numerals and redundant description will be omitted. Incidentally, at least a part of the housing 23 where the magnetic bearings are mounted is preferably covered with a non-magnetic material.

The electric motor 22 has a top plate 25.
A stator 27 externally fitted and fixed to a cylindrical portion 26 hanging down from the central portion of the lower surface of the rotor, and a rotor 29 internally fitted and fixed to a cylindrical portion 28 fixed to the upper end surface of the rotary shaft 16. . To rotate the rotary shaft 16, the stator 27 is energized.

Further, the auxiliary bearing 24 for initial centering is
With the rotation of the rotary shaft 16 stopped, the rotary shaft 1
6 and the housing 23 have their central axes aligned with each other, and are composed of an upper pivot 30 and a lower pivot 31. Of these, the upper pivot 30 is an upper spherical concave portion 32 formed in the central portion of the lower end surface of the cylindrical portion 26.
And an upper spherical convex portion 33 formed on the upper end surface of the rotating shaft 16. When the upper spherical concave portion 32 and the upper spherical convex portion 33 are fitted together as the rotary shaft 16 moves up, the upper end of the rotary shaft 16 and the housing 23 are centered.

The lower pivot 31 has a lower spherical projection 34 formed at the center of the lower end surface of the rotary shaft 16,
It is composed of a lower spherical concave portion 36 formed in the central portion of the upper surface of a centering plate 35 which is fitted in the lower portion of the housing 23 so as to be able to move up and down. This centering plate 35 has springs 37, 3
7 gives downward elasticity. Further, an electromagnet 38 is provided on a portion of the centering plate 35 near the outer periphery of the upper surface,
The electromagnet 38 is opposed to the lower surface of the step 39 formed inside the housing 23. The lower surface of the step 39 is covered with a magnetic material. This electromagnet 3 when energized
The magnetic attraction force generated by 8 sufficiently overcomes the total of the weight of the centering plate 35, the elastic forces of the springs 37, 37, and the weights of the rotary shaft 16 and the flange 10. Therefore, when the centering plate 35 is moved up with the energization of the electromagnet 38, the lower spherical concave portion 36 and the lower spherical convex portion 34 are fitted to each other, and the lower end portion of the rotary shaft 16 and the above-described Centering with the housing 23 is performed. When the centering plate 35 is further raised from this state, the upper pivot 30 centers the upper end of the rotary shaft 16 and the housing 23.

When operating the structure of the present example configured as described above, first, by energizing the electromagnet 38,
The upper and lower ends of the rotary shaft 16 and the housing 23 are centered. By energizing the stator 27 of the electric motor 22 in this state, the rotating shaft 16 is rotationally driven, and then the energization of the electromagnet 38 is stopped. As a result, the centering plate 35 has its own weight and each spring 3
It moves down due to the elasticity of 7, 37. In this state, the rotating shaft 16 is supported inside the housing 23 in a non-contact state by the thrust type magnetic bearing and the radial type magnetic bearing.

In the case of the present example, due to the above-described structure, not only when the displacement of the rotary shaft 16 is fast (in the case of AC displacement), but also when the displacement of the rotary shaft 16 is slow (in the case of DC displacement). In the case), a restoring force for the displacement of the rotating shaft 16 can be generated. That is, when the radial magnetic bearing as shown in FIGS. 1, 3 and 7 is provided alone or the thrust magnetic bearing as shown in FIGS. A restoring force is generated for displacement,
Restoration force does not occur for direct current displacement in a specific direction. That is, in the case of the structure shown in FIGS. 1, 3 and 7, the restoring force is generated for the direct current displacement in the thrust direction, but the restoring force is not generated for the direct current displacement in the radial direction. . Further, in the case of the structure shown in FIGS. 4, 6 and 8, a restoring force is generated with respect to the direct current displacement in the radial direction, but no restoring force is generated with respect to the direct current displacement in the thrust direction.

On the other hand, in the case of the seventh example shown in FIGS. 9 to 10, with respect to the direct current displacement in the radial direction, the yokes 13a ', 13' constituting the thrust magnetic bearing are formed.
Due to the magnetic attraction force acting between the b'and the protrusions 7a, 7a, the protrusions 5a, 5 of the yokes 5, 5 constituting the radial magnetic bearing are prevented against a direct current displacement in the thrust direction.
By the magnetic attraction force acting between a and the protrusions 7, 7,
Resilience occurs respectively. Therefore, according to the structure shown in FIGS. 9 to 10, the rotary shaft 16 is not used in combination with other bearings.
Can be rotatably supported in a non-contact state.

Next, FIG. 11 shows an eighth example of the embodiment of the present invention. In this example, the thrust magnetic bearing shown in FIG. 6 and the superconducting magnetic bearing 40 are combined to rotatably support the rotating plate 11a as the second member in a non-contact state. A superconductor 42 is fixed to the outer peripheral surface and the upper end surface of a cylindrical convex portion 41 formed in the central portion of the bottom surface of the housing 23a to form the superconducting magnetic bearing 40. A cooling jacket (not shown) is provided on the convex portion 41 so that the superconductor 42 can be cooled. A cylindrical portion 43 concentric with the center of rotation of the rotary plate 11a is formed on the lower surface of the rotary plate 11a. Then, inside the cylindrical portion 43, annular permanent magnets 44, 44, each of which is magnetized in the axial direction (vertical direction in FIG. 11), are placed inside with the same poles facing each other. It is fitted and fixed.

Further, in the central portion of the lower surface of the rotary plate 11a surrounded by the cylindrical portion 43, a disk-shaped permanent magnet 45 and an annular permanent magnet, which are magnetized in the axial direction, respectively. 46 and 46 are supported concentrically with each other and with their magnetization directions reversed. Each of the permanent magnets 44 to 46 has its inner peripheral surface or lower surface opposed to the outer peripheral surface or upper surface of the superconductor 42. Incidentally, the rotating plate 11
The permanent magnets 44 to 46 are formed by a part of a and the cylindrical portion 43.
The part where the is installed is made of non-magnetic material,
The magnetic fluxes from 4 to 46 are guided to the superconductor 42 side. The upper surfaces of the disk-shaped permanent magnet 45 and the ring-shaped permanent magnet 46 have the back yoke 4 made of a ferromagnetic material.
It is made to contact the lower surface of 7 to enhance the strength of the magnetic flux emitted to the superconductor 42 side.

Superconducting magnetic bearing 40 constructed as described above
The magnetic flux emitted from each of the permanent magnets 44 to 46 is pinned to the superconductor 42, so that each of the permanent magnets 4 to
A force is generated to keep the distance between 4 to 46 and the superconductor 42 constant. The upper surface of the rotating plate 11a and the housing 23a
The thrust magnetic bearing provided between the lower surface of the top plate 25 and the superconducting magnetic bearing 40 serves to ensure sufficient bearing rigidity. In the example shown in FIG. 11, as the superconducting magnetic bearing 40, a radial,
A thrust bearing having a bidirectional bearing structure is shown. However, because the superconducting magnetic bearing exerts a restoring force in both radial and thrust directions (although the rigidity differs depending on the structure) due to the pinning force of the superconductor, only one bearing structure may be used depending on the operating conditions. It is also possible to use one that has.

[0033]

Since the magnetic bearing device of the present invention is constructed and operates as described above, it does not require a displacement sensor or controller which causes a high cost, and can achieve a stable non-contact floating state by itself. A structure that can be maintained can be realized.

[Brief description of drawings]

FIG. 1 is a partially cut side view showing a first example of an embodiment of the present invention.

FIG. 2 is a perspective view of a magnetic flux restrictor incorporated in the first example.

FIG. 3 is a partially cut side view showing a second example of the embodiment of the present invention.

FIG. 4 is a partially cut side view showing the third example.

FIG. 5 is a perspective view of a magnetic flux throttle body incorporated in the third example.

FIG. 6 is a partially cut side view showing a fourth example of the embodiment of the present invention.

FIG. 7 is a partially cut side view showing the fifth example.

FIG. 8 is a partially cut side view showing the sixth example.

FIG. 9 is a cross-sectional view showing the seventh example in an operating state of an initial centering auxiliary bearing.

FIG. 10 is a sectional view showing the initial centering auxiliary bearing in a non-operating state.

FIG. 11 is a sectional view showing an eighth example of an embodiment of the present invention.

[Explanation of symbols]

 1 Fixed shaft 2 Rotating shaft 3, 3a, 3b, 3c, 3a 'Magnetic bearing unit main body 4 Permanent magnet 5, 5'Yoke 5a Projection part 6 Magnetic flux throttle body 7, 7a, 7', 7a 'Projection part 8, 8a Bearing Gap 9,9a Thin film 10, 10a Flange 11, 11a Rotating plate 12a, 12b, 12a ', 12b' Permanent magnet 13a, 13b, 13a ', 13b' Yoke 14 Flux restrictor 15, 15a Fixed housing 16 Rotating shaft 17, 18 Grooves 19a, 19b Auxiliary yokes 20, 21 Grooves 22 Electric motors 23, 23a Housing 24 Initial centering auxiliary bearing 25 Top plate 26 Cylindrical part 27 Stator 28 Cylindrical part 29 Rotor 30 Upper pivot 31 Lower pivot 32 Upper spherical recess 33 Upper side Spherical convex portion 34 Lower spherical convex portion 35 Centering plate 36 Lower spherical concave portion 37 Spring 38 Electrode Magnet 39 Step 40 Superconducting magnetic bearing 41 Convex 42 Superconductor 43 Cylindrical 44, 45, 46 Permanent magnet 47 Back yoke

Claims (1)

[Claims] 1. A first member and a second member which are concentrically arranged and relatively rotate around a predetermined rotation center, and a part of the first member is fixed to an annular space portion having the rotation center as its center. And the magnetic bearing unit main body and a part of the second member that face both end portions of the magnetic bearing unit main body, and project toward the first member at a circular portion centered on the rotation center. And a pair of protrusions fixed in a state of being formed, the magnetic bearing unit main body includes at least one permanent magnet, and the permanent magnets are arranged in series with each other in a magnetization direction of the permanent magnet. Is composed of at least one yoke and a magnetic flux restrictor made of a ferromagnetic material, and both ends thereof project toward the pair of projecting portions, so that a bearing gap is formed between these projecting portions. To form the second member Then, at least the pair of protrusions and a portion between these protrusions are made of a ferromagnetic material, and a magnetic closed circuit is configured to include the magnetic bearing unit main body and the pair of protrusions. The magnetic flux limiting body is a magnetic bearing device configured by laminating thin films made of a good electric conductor.