JPH02114834A - Magnetic bearing device - Google Patents

Abstract

PURPOSE:To reduce the size, to facilitate assembling and to improve the reliability by providing a sensor for detecting radial displacement of a rotary body, control and bias electromagnets, non-control and control magnetic poles, a radial control magnetic bearing and a motor. CONSTITUTION:Sensors 2, 5 for detecting radial displacement of a rotary body 1, control electromagnets 8, 9 and bias electromagnets 10, 11 are provided. Furthermore, non-control magnetic poles 14, 15 having two or more teeth and control magnetic poles 12, 13 are provided. When two or more radial control magnetic bearings 3, 4 and a motor 6 for driving the rotary body 1 are provided, thrust discs are not required for the bearings 3, 4.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a magnetic bearing device for a turbomachine or the like in which the rotating body is relatively light in weight, and is capable of passively stabilizing the radial axis direction only. The present invention relates to a magnetic bearing device that stabilizes and supports a rotating body in a non-contact manner through control.

[Prior art]

FIGS. 12 to 14 are side sectional views showing the structure of a spindle supported by a conventional shaft-controlled magnetic bearing device;
Figure 3 is a sectional view taken along line I-I in Figure 12, and Figure 14 is a cross-sectional view taken along line I-I in Figure 12.
2 is a sectional view taken along the line ■-■ in FIG. 2. FIG.

In the figure, a rotating shaft 31 is driven by an electric motor C provided with a motor stator 38 and a motor rotor 39 arranged in the center of a casing 37, and the rotating shaft 31 is arranged on both sides of the motor C. two radial magnetic bearings A,
A and one of the radial magnetic bearings adjacent to A)
~Magnetic bearing B and 4. It is supported by m.

The radial magnetism 441 + receiver A is stator: Iil 35
radial bearing stator 33 and rotating shaft 31 with
It consists of a raised radial bearing die 34 and a radial displacement sensor 36. The thrust magnetic bearing B is composed of a bearing stator 41 and a thrust bearing yoke 40 attached (-) to the rotary shaft 31 to the shaft 1 having a fixed -r coil 42. Also, reference numeral 32 in the figure
t” is an emergency rolling bearing.

The conventional stator magnetic pole arrangement and displacement sensor arrangement are the 13th
As shown in Fig. 14 and Fig. 14, the directions of the magnetic attraction force are two orthogonal directions, the X direction and the It is detected by displacement sensors 36a and 36b disposed in both the direction and the X direction, and control is performed based on the detection signals. Control of the rotating shaft in the X direction is performed by applying a predetermined current to the stator coil 35A or stator coil 35C based on the output of the displacement sensor 36a in the This is done by controlling the magnetic bow force generated.

FIGS. 15 and 16 are circuit diagrams showing the configuration of a control circuit for supplying a predetermined current to stator coil 35, respectively. In the control circuit of FIG. 15, the current from the bias power supply 53' is simultaneously applied to the radial displacement sensor 36.
The control current generated by the power amplifier 53 is sent to the stator coils 35A, 35B, 3.
Flow to 5C and 35D.

In the control circuit shown in FIG. 16, the signal from the radial displacement sensor 36 is guided to the phase compensation circuit 51, a constant voltage v8 is added to its output and the inverted output, and the output is further applied to the linear detection circuit 52a, 52c, stator coil 35
A predetermined current is obtained to flow through A and 35C.

[Problem to be solved by the invention]

In the case of the above conventional magnetic bearing device, the active radial magnetic bearings A, A and the thrust magnetic bearing B are provided separately;
The number of axes to be controlled to support the rotating body increases, and the rotating body requires a thrust bearing yoke 40.
There was a problem in that the assembly and disassembly of the device was complicated.

The present invention has been made in view of the above points, and by passively stabilizing the direction of the thrust axis, the number of control axes is reduced, the structure of the magnetic bearing is made smaller and simpler, and its disassembly and assembly are facilitated. Another object of the present invention is to provide a magnetic bearing device that stably supports a rotating body while improving the reliability of both mechanical and electrical systems and reducing cost and power consumption.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a magnetic bearing device that includes a displacement sensor that detects the radial displacement of a rotating body, a control electromagnet that generates a control magnetic flux that controls the magnetic attraction force in the radial direction, and a bias magnetic flux. A non-contact 11-Louis 8-pole bias magnet consisting of an electromagnet or a permanent magnet that gives and a control magnetic pole for using the control magnetic flux as a magnetic attraction force in the radial direction, and at least two radial control magnetic bearings that control only the radial axis direction and support the rotating body in a non-contact manner; It is characterized by consisting of a motor for driving.

[Effect]

By configuring the magnetic bearing device as described in 1., the bias magnetic flux can be used as the magnetic flux that generates the restoring force in the thrust axis direction, so the thrust 1-disc required for the thrust axis direction magnetic bearing as in the conventional case can be used. This eliminates the need for the magnetic bearing device, resulting in a magnetic bearing device that is easy to disassemble and assemble. Furthermore, since the number of control axes is reduced, it is possible to reduce costs, reduce the size of the device, and improve reliability.

〔Example〕

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

FIG. 1 is a side sectional view showing the configuration of a magnetic bearing device according to the present invention. As shown in the figure, this magnetic bearing device includes a rotating body 1, displacement sensors 2 and 5 for detecting the radial position of the rotating body 1, and a magnetic bearing for stably supporting the rotating body 1 in a non-contact manner. 3, 4, a fixed shaft 7, and a motor 6 for applying driving force to the rotating body 1. Displacement sensors 2 and 5 are placed near magnetic bearings 3 and 4, respectively. The magnetic bearings 3 and 4 each have an electromagnet 8 for controlling the magnetic attraction force in the radial direction.
,9, Electromagnetic yoke 16.1? , a bias magnet 10 consisting of an annular electromagnet or a permanent magnet that provides a bias magnetic flux λ
, 11, control magnetic poles 12.13, non-control magnetic poles 14.15 and rotor magnetic poles 18.19.

FIG. 2 is a block diagram showing the circuit configuration of a control device for controlling the magnetic bearing 3. As shown in FIG. Displacement [′! signal 2 of antenna 2
a, 2b as inputs, the displacement signal is sent to the control circuit 23 through the differential amplifier 22, and after phase compensation with and, it is sent to the current amplifier 24. A current is supplied to 8a and 8b to control the magnetic attraction force generated from the electromagnet 8. Note that since the control device that controls the magnetic bearing 4 also has the same circuit configuration,
The explanation thereof will be omitted here.

FIG. 3 is a diagram showing the structure and operation of the magnetic bearing 3, in which FIG. 3(a) is a plan view and FIG. 3(b) is a partially cutaway perspective view. The magnetic bearing 3 has a controller 1, an electromagnet 8 that generates a roll magnetic flux and controls magnetic attraction, and a bias magnet 10 that is made of an electromagnet or a permanent magnet that generates a bias magnetic flux.
Therefore, the control device does not require a circuit (linearization circuit) for applying bias. The electromagnets 8 and 9 that generate control magnetic flux are connected in series (8cm8d-8e) with electromagnetic coils 8a and 8b that face each other (with the same control axis), and the magnetic flux is transmitted from the electromagnetic coil 8a to the control magnetic pole as shown in FIG. 12, flows through the teeth 12a of the magnetic pole, and the rotating body 1
The magnetic pole teeth 12b1 of the magnetic pole 12, the electromagnetic coil 8a, and the electromagnetic yoke 16b.

16a to form a closed loop magnetic path. In addition, a closed loop magnetic path flows from the control magnetic pole 12 of the bias magnet 10 that generates bias magnetic flux through the magnetic pole teeth 12a, 12b, the rotor magnetic poles 18a, 18b of the rotating body 1, the non-control magnetic pole 14, and the magnetic pole teeth 12a, 12b. form. As a result, in the control magnetic pole 12, the relationship between the force Fc and the magnetic flux density Bi is linearized by the bias magnetic flux BO as shown in the following equation. (See Figure 4) F=A/2μ((Bo+△Bo-Bi)"-(Bo-Δ
Bo+Bi)') = 2A/μ(noΔBo−BoBi) However, A: Area of the magnetic pole μ: Air gap permeability Note that the structure and operation of the magnetic bearing 4 are the same as the magnetic bearing 3 above, so the explanation will be omitted. .

The non-control magnetic pole 14 has two or more mouth-shaped teeth 14.
a, 14b are provided to increase the magnetic flux density Bu in this part, and when the rotating body 1 moves in the thrust axis direction due to its own weight, etc., the rotor magnetic poles corresponding to the U-shaped teeth 14a, 14b as shown in FIG. A magnetic flux in the thrust axis direction is generated between the 18 teeth 18c and 18d, and as a result, a restoring force Fu is generated in the thrust axis direction, and the thrust axis direction can be passively supported.

As described above, in this magnetic bearing, the bias magnetic flux of the bias magnet 10 is used as a magnetic flux for linearizing the magnetic attraction force and passively supporting the thrust axis direction. Therefore,
Since it is possible to stably support a rotating body by controlling only the radial axis direction, a thrust disk (the thrust in Fig. 12) like a conventional thrust magnetic bearing is used.
・Bearing yoke 40) becomes unnecessary.

Note that the bias magnetic flux of the electromagnet 11 (or permanent magnet) is also used as magnetic flux for linearizing the magnetic attraction force and passively supporting the thrust axis direction, as in the case of the electromagnet 10 described above.

Electromagnet that generates control magnetic flux8. The electromagnet 9 is arranged perpendicularly to the radial control axis as shown in Figs. 1 and 3, and by reducing the radial dimension, it is configured so that it can be applied even when there are restrictions in the radial direction of the stator. Leeru. At this time, the cross-sectional area of the electromagnet (yoke) is also restricted, which may cause saturation of the magnetic flux. To solve this problem, as shown in FIGS. 6(a) and 6(b), the cross section of the electromagnet 16 is made such that one side is a straight line and one side is an arc. By doing this, it is possible to increase the surface area of the magnetic path in a limited space. In this case, it would be difficult to make it from silicon steel, so materials such as magnetic soft iron and permalloy, which can be easily shaped, are used. In this magnetic bearing, bias magnetic flux is supplied by bias magnets 10 and 11 made of electromagnets or permanent magnets, and the magnetic flux density in the air gap is controlled by magnetic poles 12 and 11.
4 (0, 4 (T) ~ 0, 6 (T)), and the non-control magnetic pole is set to 0, 8 (T > ~ 1, 2 (I). This is the control magnetic pole 8ii12.
14, the magnetic flux density generated by the electromagnet is -0, 5 (T) ~ +
0 to 5 (T), and for non-controlled magnetic poles, the tip of the magnetic pole is almost saturated to increase the restoring force in the thrust axis direction. This setting is performed using parameters such as the surface area of the magnetic poles, the length of the magnetic path, the air gap between the magnetic poles, the coercive force of the magnet, the residual magnetic flux density (for permanent magnets), and the magnetomotive force (for electromagnets).

FIG. 7 is a diagram showing calculation results representing the distribution of magnetic flux density in the air gap. ，
It shows the change in magnetic flux density when 0 (A>, +2.0 (A)) is applied.As can be seen from this figure, the electromagnet 8,
When a current is passed through the magnetic pole 9, the magnetic flux density of the control magnetic pole 12.13 is changed (controlled) without affecting the magnetic flux density of the non-control magnetic pole 14.15.

Further, in order to prevent the control magnetic flux for varying the magnetic flux density from flowing into the adjacent control magnetic pole in order to vary the magnetic flux density in this way, as shown in the eighth factor, a radial notch 12a is provided in the control magnetic pole 12. , so that the bias magnetic flux is saturated at the magnetic pole part P between the control magnetic poles, and the control 1~roll magnetic flux does not flow into it.

As a current amplifier for passing a current through the electromagnet 10, a push-pull type current amplifier 25 as shown in FIG. 9 is used since the coils 8a and 8b of the opposing electromagnets 8 are connected in series. This push-pull type current amplifier 25 does not select opposing coils using 0N10FF, but simply changes the direction of the current flowing through the coils 8a and 8b of the electromagnet 8, reducing the number of circuit parts, reducing costs and circuit The reliability of the system is also improved.

In this magnetic bearing, the bias magnetic flux 10.11 is given by an annular electromagnet or a permanent magnet, but as shown in Fig. 10, when a permanent magnet 20 is used, the magnet is very easily damaged or broken, and iron particles are generated during handling. etc. are adsorbed, so the first
As shown in Figure 0, a ring 21 of non-magnetic material made of aluminum or the like can be placed around the outer periphery of the permanent magnet 20 for protection. These facilitate the assembly of magnetic bearings and prevent accidents. In addition, the wooden bearing part is the electromagnetic yoke 1
6. Since it consists of an electromagnet 8, a control magnetic pole 12, an electromagnet 10 (permanent magnet), and a non-control magnetic pole 14, and has many parts, it is shown in FIG. Yoyo Tyroc 1
~3a to fix it integrally. This not only improves work efficiency, but also improves positioning and dimensional accuracy between the magnetic poles of the bearing.

〔Effect of the invention〕

As explained above, according to the present invention, the following excellent effects can be obtained.

In other words, since the rotating body is supported in a non-contact manner by controlling only the radial axis direction using at least two radially controlled magnetic bearings, there is no need for the thrust stiffness required for conventional magnetic bearings in the thrust axis direction. The magnetic bearing device can be easily disassembled and assembled, and since the number of control axes is reduced, it is possible to reduce costs, reduce the size of the device, and improve reliability.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing the configuration of a magnetic bearing device of the present invention, FIG. 2 is a block diagram showing a circuit configuration of a control device for controlling the magnetic bearing of the present invention, and FIG. 3 is a magnetic bearing of the present invention. FIG. 5 is a diagram showing the structure and operation of the magnetic bearing, in which FIG. 4A is a plan view, FIG. 4B is a partially cutaway perspective view, FIG. 6 is an explanatory diagram of the thrust restoring force generation mechanism of the magnetic bearing of the invention, and FIG. 6 is a diagram showing the shape of the electromagnet yoke of the magnetic bearing of the invention. ) is a side view, FIG. 7 is an explanatory diagram of the magnetic flux density of the magnetic pole of the magnetic bearing of the present invention, FIG. 8 is a plan view showing the control magnetic pole of the magnetic bearing of the wooden invention, and FIG. 9 is the magnetic bearing of the present invention. FIG. 10 is a diagram showing the bias magnet structure of another magnetic bearing according to the present invention, and FIG.
11 is a sectional view, FIG. 11(b) is a plan view, FIG. 11(c) is a sectional view showing the structure of a magnetic bearing incorporating this bias magnet structure, and FIG. 12 is a cross-sectional view showing the magnet structure; FIG. 12 is a side cross-sectional view showing the structure of a spindle supported by a conventional shaft-controlled magnetic bearing device;
Figure 3 is a sectional view taken along the ■-I line in Figure 12, and Figure 14 is a cross-sectional view of Figure 1.
[-n line arrow sectional view of FIG. 2, FIGS. 15 and 16]
FIG. 3 is a circuit diagram showing a configuration of a control circuit for supplying predetermined currents to stator coils 35. FIG. In the figure, 1...Rotating body, 2...Displacement sensor, 3
...Magnetic bearing, 4...Magnetic bearing, 5...Displacement sensor, 6...Motor, 7...Fixed shaft, 8.
9...Electromagnet, 10.11...Bias magnet, 12゜13...Control? 1KL14.15
...Non-control magnetic pole, 16.17...Electromagnetic yoke, 18.19...Rotor magnetic pole, 20...
- Permanent magnet, 21... A non-magnetic ring made of aluminum, etc. Applicant: Ebara Research Institute, Inc.

Claims (8)

[Claims] (1) A displacement sensor that detects the displacement of the rotating body in the radial direction, a control electromagnet that generates a control magnetic flux that controls the magnetic attraction force in the radial direction, and a bias magnet that is an electromagnet or a permanent magnet that provides a bias magnetic flux. , a non-control magnetic pole having two or more teeth for using the bias magnetic flux from the bias magnet as a restoring force in the thrust axis direction of the rotating body, and a non-control magnetic pole for using the control magnetic flux as a magnetic attraction force in the radial direction. at least two radial control magnetic bearings that control only the radial axis direction and support the rotating body in a contactless manner;
A magnetic bearing device comprising a motor for driving the rotating body. (2) A control electromagnet for controlling the radial axis direction of the rotating body is provided so as to be positioned perpendicular to the radial axis direction, a magnetic path for the control magnetic flux and a magnetic path for the bias magnetic flux are separately provided, and these two 2. The magnetic bearing device according to claim 1, wherein the magnetic poles are configured so that the control magnetic poles have a common magnetic path. (3) Adjust the magnetic flux density of the bias magnetic flux to be in the range of 0.4 (T) to 0.6 (T) for the control magnetic pole and 0.8 (T) to 1.2 (T) for the non-control magnetic pole. The magnetic bearing device according to claim 1 or 2, wherein the magnetic bearing device is set to . (4) The control magnetic pole is ring-shaped, and the ring-shaped control magnetic pole is provided with four notches radially. Magnetic bearing device. (5) Claims (1) to (1) characterized in that the magnet providing the bias magnetic flux is a ring-shaped permanent magnet, and the outer periphery of the ring-shaped permanent magnet is protected by a ring made of a non-magnetic material such as alumina. The magnetic bearing device according to any one of 4). (6) The magnetic bearing device according to any one of claims (1) to (5), wherein the magnetic pole and the magnet are integrated with a tie rod. (7) Claim (1) characterized in that, in order to increase the surface area of the control electromagnet that generates the control magnetic flux, one section of the electromagnet is formed in a straight line and the other section is formed in an arc shape.
The magnetic bearing device according to any one of (6) to (6). (8) Claim (1) characterized in that a push-pull type current amplifier is used as the current amplifier that excites the electromagnet.
) to (7). The magnetic bearing device according to any one of (7).