JPS61124724A - Magnetic bearing - Google Patents

Abstract

PURPOSE:To obtain the magnetic support force of a rotor even during the failure of power supply by disposing magnetic flux supply means at a portion rotating in relative to a conductive member mounted on a fixed body, and producing induced electromotive force in the conductive member by the magnetic flux supply means. CONSTITUTION:A fixed body1 comprises a case 4 which is shaped like a flat hollow cylinder and formed by non-magnetic material. A support 5 comprising a column made of magnetic material having high magnetic permeability is fixed at the axis of the case 4. Annular permanent magnets 6, 7 are fixed at both end potions of the outer peripheral surface of the support 5 in such a manner as to closely adhere to the inner surfaces of the axial both ends of the case 4. The permanent magnets 6, 7 function as magnetic flux supply means for generating induced electromotive force in a conductive member 30 fixed to a rotor 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a magnetic bearing that uses magnetic force to support an object in a non-contact manner.

(Technical background of the invention and its problems) Magnetic bearings have conventionally been known as bearings that support objects in the air almost completely without contact.Magnetic bearings are difficult to support with mechanical bearings such as ball bearings. For example, it is often used to hold a high-speed rotating body with low loss.Such magnetic bearings generally use electromagnets to obtain the magnetic force for magnetically supporting the rotating body. This is because magnetic force control for stable support control of the rotating body is performed by adjusting the amount of current applied to the electromagnet.

By the way, in the above-mentioned magnetic bearing, since the magnetic force for supporting the rotating body is obtained by an electromagnet, if the power supply to the electromagnet is cut off due to a power outage accident, for example,
The magnetic force for supporting the rotating body is lost. Therefore, in this type of magnetic bearing, a ball bearing for emergency support is prepared, and the rotating body is supported by this ball bearing in an emergency.

However, there is a limit to the number of rotations that ball bearings can support, and supporting the above-mentioned high-speed rotating bodies with ball bearings even in emergencies poses safety concerns, considering the extremely large inertia of the rotating body. There was a bow problem.

Moreover, in general, such magnetic bearings have a structure in which power is supplied independently to the electromagnetic coil for magnetically supporting the rotating body and to the motor that applies rotational force to the rotating body, so the magnetic bearing If the current to the supporting coil is interrupted and the current to the motor is not interrupted,
The load placed on emergency ball bearings has increased dramatically, and the above-mentioned problems have become even more pronounced.

[Purpose of the invention]

The present invention has been made based on such problems, and its purpose is to prevent the magnetic bearing force of the rotating body in a high-speed rotation state from being lost even during a power outage, thereby improving safety. Our objective is to provide extremely high magnetic bearings.

[Summary of the invention]

The present invention provides a conductive member on a rotating body or a stationary body that is stationary with respect to the rotating body, and a magnetic flux supply means is provided on a portion that rotates relative to the conductive member, and the magnetic flux is supplied by the magnetic flux supply means and the Generating an induced electromotive force inside the conductive member by a magnetic flux that moves relative to the conductive member,
The present invention is characterized in that the coil is energized by this induced electromotive force to obtain an electromagnetic force for non-contact support of the rotating body.

(Effect of the invention) With the above configuration, the electromagnetic force for non-contact support of the rotating body is obtained by the induced electromotive force caused by the rotation of the rotating body, so even if the power is cut off, However, as long as the rotating body is rotating, the electromagnetic force for supporting the rotating body is not lost.

Therefore, even if the power supply is cut off due to an accident or the like, it is possible to stably support the rotating body even at low rotational speeds, and safety can be dramatically improved.

According to the present invention, the induced electromotive force increases in accordance with the rotational speed of the rotating body, and the electromagnetic force for supporting the rotating body also increases accordingly. Therefore, when the rotation speed of the rotating body is low, ball bearings require support by mechanical bearings, but in this case, the rotation speed does not exceed the permissible rotation speed of the ball bearing, and at high speeds exceeding this. Once rotation is reached, stable non-contact support can be achieved with extremely high magnetic rigidity.

(Embodiments of the Invention) Hereinafter, a high-speed rotation device using a magnetic bearing according to an embodiment of the present invention will be described with reference to the drawings.

As shown in Fig. 1, this high-speed rotation device is divided into two main parts: a fixed body, a rotating body 2- which is supported without contacting the fixed body during rotation, and a rotating body 2-. It is composed of an induction motor 1 that provides rotational driving force.

The fixed body 1 is configured as follows. That is, 4 in the figure is a case 4 which has a flat hollow cylindrical shape and is made of a non-magnetic material. A column 5 made of a permeable magnetic material is fixed to the axial center of the case 4. An annular permanent magnet 6.degree. 7 is fixed on the outer circumferential surface of the support column 5 and at both ends thereof so as to be in close contact with the inner surfaces of both axial end walls of the case 4, respectively. These annular permanent magnets 6, 7
serves as a magnetic flux supply means for generating an induced electromotive force in a conductive member 30, which will be described later, which is fixed to the rotating body 2-. Annular yokes 8.9 made of a high permeability magnetic material are attached to the outer peripheries of the annular permanent magnets 6, 7, respectively. These annular yokes 8, 9 protrude in the axial direction toward the rotating body 2 in order to guide the magnetic flux generated from the annular permanent magnet 6.7 in the axial direction. On the other hand, an annular permanent magnet 11 magnetized in the axial direction is fixed to the inner surface of the side wall of the case 4. At both axial ends of the annular permanent magnet 11, annular yokes 12 and 13, also made of a high magnetic permeability magnetic material, are fixed so as to be in close contact with the inner surfaces of both axial end walls of the case 4. . This annular yoke 12, 13 has protruding peripheral portions 12a that protrude in the axial direction and radial direction, respectively, in order to radiate the magnetic flux from the annular permanent magnet 11 toward the rotating body stop in the axial direction and radial direction.
, 13a, 12b, 13b.

The annular permanent magnet 11 is an electric magnet 1G42 which will be described later.
The interaction with the magnetic flux from 3 generates a repulsive force on the rotating body 2-. Incidentally, annular support plates 14 and 15 are attached to the support column 5 at a predetermined interval in the axial direction, and the outer circumferential portions of these annular support plates 14 and 15 are provided with the support plates 14 and 15, respectively, to prevent the rotation during low speed rotation. ball bearing 1 supporting the body 2-
6.17 is installed.

The rotating body 2- includes an annular yoke 21, an annular support 22,
The annular electromagnet 23 is sequentially externally mounted in this order, and a voltage induction part 24 is attached to the annular yoke 21. The annular yoke 21 is made of a high magnetic permeability magnetic material, and is arranged such that both ends thereof face the annular yoke 8 and 9 of the fixed body 1 with a predetermined magnetic gap P in between during rotation. . The annular support body 22 is made of a non-magnetic and non-conductive material. The electromagnet 23 is composed of an annular coil core 26 formed with a circumferentially extending groove having a predetermined width on its outer periphery, and a coil 27 wound circumferentially around the groove of the coil core 26. ing. The coil core material 26 is formed of a high magnetic permeability magnetic material, and when the rotating body 2 rotates, the outer circumferential surfaces of both ends in the axial direction form a predetermined magnetic gap Q of 1.
The projecting peripheral walls 12b are opposed to each other through the projecting peripheral wall 12b, and both end surfaces thereof are the projecting peripheral walls 12b.

13b with a predetermined magnetic gap R in between. Further, the voltage induction section 24 is connected to the annular yoke 2
The electrodes 28 and 29 arranged on the inner and outer circumferential surfaces of the electrode 1 and the rod-shaped conductive member 30 connecting the two electrodes 28 and 29, as extracted and shown in FIG.

The electrodes 28 and 29 are electrically connected to both terminals of the coil 27, respectively, as shown.

The induction motor β- is mounted on the outer peripheral surface of the support column 5 of the fixed body 1 and between the annular support plates 14.15'':
The stator 31, the rotating body, and the annular yoke 21 of 2-
A rotor 3 is provided on the inner circumferential portion of the rotor 3 so as to cover the electrode 29 and is provided at a position facing the stator 31.
It is composed of 2. This rotor 32 has a stator 31
The annular yoke 21 has a predetermined thickness such that the magnetic flux supplied from the annular yoke 21 does not affect the annular yoke 21.

Next, the operation of the high-speed rotating device according to the present embodiment configured as described above will be explained.

That is, assuming that the rotating body 2- is now stationary, the rotating body 2- is supported on the fixed body by ball bearings 16, 17. The magnetic flux supplied from the annular permanent magnet 6.7 is applied to the ms permanent magnet 6 to the annular yoke 8 to 11 gap P.
- Annular yoke 21 - N & air gap P - Annular yoke 9 - Annular permanent magnet 7 - Support column 5 - A magnetic loop M1 passing through the path of annular permanent magnet 6 is formed. When the induction motor 1 is energized in this state, the rotating body starts rotating and gradually increases its speed. When the rotating body 2- rotates in this way, the conductive member 30 crosses the magnetic loop M1 in the circumferential direction, so that an electromotive force proportional to the rotation speed of the rotating body 2- is generated in the conductive member 30. induced. When an electromotive force is induced in the conductive member 30, a potential difference is generated between the electrodes 28 and 291J electrically connected to both ends of the conductive member 30, so a current flows through the coil 27 connected thereto. This causes the electromagnet 23 to be energized. In this example, the electromagnet 23 is magnetized in a direction repulsive to the annular permanent magnet 11. Therefore, a magnetic repulsive force is generated between the electromagnet 23 and the annular permanent magnet 11, and this repulsive force acts in a direction to reduce the gravity acting on the rotating body 2- and the external force applied to the rotating body 2-. . This magnetic repulsive force is proportional to the speed of the rotating body 2-, so when the rotating body 2- is driven to rotate at an even higher speed by the induction motor 3-, the rotating body 2- will eventually be driven by the ball bearing. 16.17
It will float up from the ground and be completely supported in the air without contact. When the rotational speed of the rotating body 2- further increases, the rigidity of the magnetic bearing further improves, and stable support of the rotating body 2- can be realized.

In this case, the electromagnet 23 that supplies the magnetic force for magnetic support of the rotating body 2- is attached to the rotating body 2-, rather than being energized by electric power supplied from another power system. The magnetic force is energized by the electromotive force induced in the conductive member 30, and the magnetic force depends on the rotation speed of the rotating body 2-, so even if the power is cut off due to an accident, the rotating body 2- Magnetic support is possible while the rotating body 2- is rotating at high speed due to the inertial force of. If the rotational speed decreases and the magnetic bearing force decreases, the rotational speed has already reached a level that can be safely supported by the ball bearings 16, 17, so danger can be sufficiently avoided. Note that in this case, the current flowing through the conductive member 30 can contribute to braking the rotating body. Moreover, in this case, since the rotating body 2- is magnetically supported using magnetic repulsion, the rotating body 2- can be stably supported without any control.

FIG. 3 shows a high-speed rotating device according to another embodiment of the present invention, and the same parts as in FIG. 1 are given the same reference numerals. Therefore, the explanation of the overlapping parts will be omitted.

This embodiment differs from the previous embodiments in the magnetic support means of the fixed body. That is, an annular yoke 41 is attached to the inner surface of the side wall of the case 4. This annular yoke 41 is made of a high permeability magnetic material, and the electromagnet 23
an annular portion 42 having approximately the same axial length as the annular portion 42; and radial support magnetic poles 43a, 43b, which are arranged with a phase difference of 90° in the circumferential direction.
43c, 43d.

44a, 44b, 44C, 44d (However,
43d and 44d (not shown) and these radial supporting magnetic poles 43a to 43d and 44a to 44d are arranged with a phase difference of 45 degrees, respectively, and the annular portion 42
An axially supporting magnetic pole 45a extends from both end edges of the case 4 along the inner surface of both end walls of the case 4 toward both ends of the electromagnet 23, and faces the electromagnet 23 in the axial direction through a magnetic gap.
, 45b.

45c, 45cl, 46a, 46b,
46c, 46d (However, 45C, 45d,
46c and 46d are not shown).

And these 11 poles 43a to 43d, 44a to 4
4d, 45a ~ 45d, 46a ~ 46d
Coils 47 and 48 for stabilization control are wound there.

In the high-speed rotating body configured in this way, the rotating body, 2
- When rotated, the electromagnet 23 is energized as described above, and the magnetic flux generated thereby is transmitted, for example, to the annular portion 42 to
Magnetic pole 43a - Magnetic gap S - Coil core material 26 - Magnetic gap S - Magnetic pole 44a - Penetrates cylindrical part 42 to form a magnetic loop M2 for axial stabilization,
For example, the annular portion 42 ~ magnetic 1i 45b ~ magnetic gap T ~
Coil core material 26 - 11 air gap T - magnetic pole 46b - passes through cylindrical part 42 and magnetic loop M for radial stabilization
form 3. As a result, magnetic attraction force moves in the axial and radial directions of the rotating body 2-. This magnetic attraction force is
If left as is, it is inherently unstable. Therefore, in this case, the rotating body,? - detect at least one of the radial and axial displacement and velocity of - by a known detection means (not shown), and based on this detected value,
By appropriately energizing the coils 47, 48, stable support in two orthogonal directions to the rotating body l is realized.

In this case, the power consumption of the controller and detection means for stabilization control is extremely small, and so-called zero power control is possible, so that the power for stabilization control can be provided by a small battery. Since the magnetic force for obtaining magnetic rigidity, which requires a relatively large amount of electric power, is obtained based on the rotation of the rotating body, safety in the event of a power outage can also be improved with this embodiment.

Note that the present invention is not limited to the two embodiments described above. For example, in the above embodiment, one rod-shaped body was used as the conductive member to connect the two electrodes 28, 29, but as shown in FIG. Alternatively, a rod-shaped conductive member 50 may be used. With such a configuration, a larger current can flow, so the magnetic force obtained can also be increased.

Further, in the above embodiment, the conductive member is provided on the rotating body side and the magnetic flux supply means is provided on the fixed body side, but conversely, the magnetic flux supply means is provided on the rotary body side and the conductive member is provided on the fixed body side. Also good. Further, the force for obtaining the supporting force of the rotating body 2- may be one that utilizes the electromagnetic force generated in the coil itself when a current is passed through the coil placed in a magnetic field.

As described above, the present invention can be implemented with various modifications without departing from the gist thereof.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a high-speed rotation device using a magnetic bearing according to an embodiment of the present invention, FIG. 2 is a perspective view showing a part of the same high-speed rotation device, and FIG. 3(a) (b) is a diagram showing a high-speed rotation device using a magnetic bearing according to another embodiment of the present invention, and FIG. A longitudinal cross-sectional view taken in the direction of the arrow, Figure (b) shows the high speed rotating device at B in Figure (a)
FIG. 4 is a cross-sectional view taken along the line -B and viewed in the direction of the arrow, and a perspective view showing a voltage induction section according to still another embodiment of the present invention. , 1 piece...Fixed body 1. ? -... Rotating body, 3-... Induction motor, 4... Case, 5... Support column, 6.7.1
1... Annular permanent magnet, 8, 9.12.41.21...
・Annular yoke, 14.15... Annular support plate, 16.17
... Ball bearing, 22 ... Annular support body, 23 ... Electromagnet, 24 ... Voltage induction part, 26 ... Coil core material, 2
7.47°48... Coil, 28.29... Electrode,
30.50... Conductive member, 31... Stator, 32...
...rotor.

Claims (6)

[Claims] (1) In a magnetic bearing that includes a rotating body and a fixed body that is stationary relative to the rotating body, a conductive member fixed to the rotating body or the fixed body rotates relative to the conductive member. a magnetic flux supply means that is provided at a portion where the conductive member is connected and generates a magnetic flux that crosses the conductive member, and generates an induced electromotive force inside the conductive member by relative movement between the magnetic flux and the conductive member; A magnetic bearing comprising: a coil that is energized by the induced electromotive force generated in the conductive member and generates a magnetic force for non-contact magnetic support of the rotating body. (2) The rotating body is supported by a magnetic repulsion force between it and the fixed body, and the electromagnetic force generated by biasing the coil is provided to the magnetic repulsion force. A magnetic bearing according to claim 1, characterized in that: (3) The rotating body is supported by a magnetic attraction force between it and the fixed body, and the electromagnetic force generated by urging the coil is provided to the magnetic attraction force. A magnetic bearing according to claim 1, characterized in that: (4) The magnetic bearing according to claim 1, wherein the rotating body is supported by magnetic repulsion and magnetic attraction between the rotating body and the fixed body. (5) The magnetic bearing according to claim 1, wherein the magnetic flux supply means is provided on the fixed body, and the conductive member and the coil are provided on the rotating body. (6) The magnetic bearing according to claim 1, wherein the magnetic flux supply means is provided on the rotating body, and the conductive member and the coil are provided on the fixed body.