JPS63111311A - Magnetic bearing device - Google Patents

Abstract

PURPOSE:To make the device in the caption compact and light by forming the magnetic pole surfaces of radial control electromagnets into taper shape, and generating suction forces in the radial and axial directions with the same electromagnet. CONSTITUTION:The magnetic pole surfaces of radial control electromagnets 3a-3d are processed into taper forms, and the outer circumferential surface of annular portions on the rotor side facing to the above-mentioned magnetic pole surfaces are formed into cones corresponding to the taper forms. The signals of radial displacement gages 5a, 5b supply current to the electromagnets 3a-3d through control circuits 9a-9d respectively. The magnetic pole surface of the electromagnets are inclined and as well the circular portions on the rotor side facing to the above-mentioned magnetic pole surfaces have suitable forms and thereby generated suction forces are compensated with each other in the radial direction so that only restoring force in the vertical direction can be obtained. Accordingly, without any axial control electromagnet, it is possible to correct the axial displacement so as to make the rotor floatable, and then a compact and light magnetic bearing device can be secured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic bearing device for, for example, a vacuum pump, and in particular to the arrangement of electromagnets thereof.

[Conventional technology]

FIG. 3 is a sectional view showing a conventional turbomolecular pump using magnetic bearings. In the figure, (1) is the rotor, (2) is I.Using, and (3a) and (3b).

(3c), (3d) are radial control electromagnets (4a) that control the radial displacement of the rotor (1);

(4b) is an axial control electromagnet that controls the axial displacement of the rotor (1), (5a) and (5b) are radial displacement meters that detect the radial displacement of the rotor (1), and (6) is the rotor (
1) is an axial displacement meter that detects axial displacement; (10) is a rotary drive motor;

Next, the operation will be explained. Referring to FIG. 4, the radial displacement meter (5a) is connected to the radial control electromagnet (3a) through the control circuit (7a), and the control circuit (
7b) to the radial control electromagnet (3b). Similarly, the radial displacement meter (5b) is connected to the control circuit (7
c).

(7d) through the radial control electromagnet (3c).

(3d). The axial displacement meter (6) is connected to the axial control electromagnet (4a) through the control circuit (8a) and to the axial control electromagnet (4b) through the control circuit (8b).
connected to. Then, when the rotor (1) is floating and rotating at a desired position, the radial displacement meter (5a).

(5b) and the axial displacement meter (6) are adjusted to zero. Therefore, for example, when the rotor (1) is slightly displaced in the radial direction to the right in the figure, the amount of displacement is detected by the radial displacement meter (5a), and the control circuit (7a) connected to this is detected by the radial displacement meter (5a). Supply current to the electromagnet (3a). The rotor (1) is thus pulled back to the desired position. Conversely, if the rotor (1) is displaced to the left in the figure, the control circuit (7b) has an input with the opposite sign, so
1, the magnet (3b) is excited, and the displacement of the rotor (1) is also corrected. Further, although not shown, the preceding and following controls are performed in the same manner. Lower radial displacement meter (5b)
Likewise, the electromagnet (3d) is connected through the control circuits (7c) and (7d).

(3d) is excited. Similarly, the axial displacement meter (6) is connected to the electromagnets (4a), (
4b) to levitate the rotor (1) to a desired position.

In this way, no matter how the rotor (1) is displaced, the error is corrected and the rotor (1) can maintain floating rotation.

[Problem that the invention seeks to solve]

Since the conventional magnetic bearing device is configured as described above, it has many electromagnets (including one not shown in Fig. 4).
0 pieces), the weight and shape are large, and there are problems in that a large number of control circuits are required.

This invention was made to solve the above-mentioned problems, and it is possible to levitate the rotor to a desired position without requiring an axial direction control electromagnet and its control circuit, and therefore a small and lightweight magnetic bearing device. The purpose is to obtain.

[Means for solving problems]

In the magnetic bearing device according to the present invention, the magnetic pole face of the radial control electromagnet is tapered so that the attractive force of the radial control electromagnet also includes an axial component, and the corresponding annular portion on the rotor side is also made conical. The axial displacement signal of the rotor is also added to the radial direction control circuit and inputted thereto.

[Effect]

The magnetic bearing device according to the present invention uses the tapered shape of the magnetic pole surface of the radial direction control electromagnet and the corresponding conical surface of the annular portion on the rotor side to maintain the rotational axis of the rotor at the center, while at the same time using the axial component. Raise the rotor.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure (3a) and (3b).

(3c) and (3a) are radial direction control electromagnets whose magnetic pole faces are machined into a tapered shape. The outer peripheral surface of the annular portion on the rotor side corresponding to these is also formed into a conical shape corresponding to the taper. (9a).

(9b), (9c), and (9d) are control circuits that supply current proportional to the sum or difference of two electrical signals. Note that the same members as in the conventional example are given the same reference numerals.

Next, the operation will be explained. Referring to FIG. 2, the signals from the radial displacement meters (5a) and (5b) are sent to the electromagnets (3, a) to (3a) through control circuits (9a) to (9a), respectively, similarly to the conventional one. Feedback is provided to supply current.

The radial displacement of the rotor (1) is thus corrected in exactly the same way as before, and the axis of rotation is kept in the center of the bearing.

On the other hand, the rotor, whose axis of rotation is arranged vertically, has a strong gravitational force and cannot levitate in this state. Therefore, the axial displacement meter (6) detects the axial displacement of the rotor and calculates its magnitude. All electromagnets (3a) to (3d
) to supply current to the control circuit ( ).
9a) to (9d) are added in the same phase. Therefore, when the rotor (1) is lowered below the floating position, the attractive force of all the radial control electromagnets increases, but the magnetic pole faces of the electromagnets are inclined and the corresponding annular part on the rotor side Since they are shaped accordingly, the generated suction forces cancel each other out in the radial direction, and only a restoring force in the vertical direction is obtained. Therefore, by using a radial control electromagnet with tapered magnetic poles, it is possible to correct the axial displacement and levitate the rotor without the need for a conventional axial control electromagnet.

Therefore, as shown in FIG. 1, it becomes possible to arrange the motor (10) etc. in the space where the axial direction control electromagnet is normally located, and it becomes possible to obtain a small and lightweight magnetic bearing device.

In the above embodiments, an inner rotor type in which the rotor is located inside the electromagnet has been described, but a similar method can be applied to an outer rotor type in which the rotor is located outside the electromagnet.

〔Effect of the invention〕

As described above, according to the present invention, since the magnetic pole surface of the radial direction control electromagnet is tapered, it is possible to generate attraction forces in both the radial direction and the axial direction with the same electromagnet, and with fewer electromagnets and control circuits. Rotor levitation control becomes possible,
This has the effect that the device can be made smaller, lighter, and cheaper.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a magnetic bearing device according to an embodiment of the present invention, and FIG. 2 is a block diagram showing the operation of the present invention.
FIG. 3 is a sectional view showing a conventional magnetic bearing device, and FIG. 4 is a block diagram showing its control. In the figure, (3a) to (3d) are electromagnets, (5a)
, (5b) = (61 is a displacement meter, (9a) ~ (
9d) is a control circuit. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Patent Attorney Masuo Oiwa Figure 1 Figure 2 Figure 9d: Ya 1-Circuit Figure 3 Figure 4U! J 7a-Book 1 circuit δb, tl & 1 circuit

Claims (3)

[Claims] (1) In a magnetic bearing device with a vertical axis of rotation, the magnetic pole surface of the electromagnet that controls the radial displacement of the rotor is tapered, and the outer peripheral surface of the annular portion on the rotor side is also shaped into a corresponding cone shape. A magnetic bearing device characterized in that a generated attractive force has a component in the direction of the rotation axis, thereby eliminating the need for a dedicated electromagnet for controlling the direction of the rotation axis. (2) The magnetic bearing device according to claim 1, wherein the rotor is an inner rotor type in which the rotor is located inside the electromagnet. (3) The magnetic bearing device according to claim 1, wherein the rotor is an outer rotor type in which the rotor is located outside the electromagnet.