JPS62194025A - Magnetic bearing - Google Patents

Abstract

PURPOSE:To provide a less expensive magnetic bearing of a smaller outside diameter and to permit it to be assembled and disassembled with ease, by preventing damage due to defective operation by mounting three or more radial roller bearings with a small outside diameter for abnormality on mounting members at a clearance smaller than that of the magnetic baring in a circumferential direction. CONSTITUTION:Three bearings 11 for abnormality are mounted on mounting plates 13a, 13b divided into two portions in a radial direction through elastic bars 12 and respective clearances 7-9 between a magnetic bearing unit, a mounting plate 13 of a bearing unit for abnormality and a rotary shaft 4 are set to 7>9>8, respectively. When the magnetic bearing runs normally, the clearances 7, 8 between a bearing yoke 1 and the rotary shaft 4 are held normally by a radial direction displacement detector 5. In defective operation the rotary shaft 4 is supported by the roller bearings 11 for abnormality at first. When the degree of the defective operation is increased, the elastic bar 12 is displaced so that the rotary shaft 4 is made contact with the mounting plate 13 for being applied with a braking force. With such an arrangement, the outside diameter of the bearings is made smaller, they are assembled and disassembled with ease and a maintenance cost is saved.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is directed to a magnetic bearing yoke having an excitation winding wound thereon, which is attached to a bearing box, and which is disposed integrally with the shaft inside the bearing yoke. The radial magnetic bearing is widely used as a radial bearing, and is designed to perform a bearing action by exerting a magnetic attraction force between the rotor and the rotor. This type of magnetic bearing is equipped with a radial displacement detector, and the output signal of the displacement detector is introduced into a control circuit, and a control current is supplied to the excitation winding. It's designed to make you feel that way.

(Prior Art) As shown in FIG. 3, in a conventional radial magnetic bearing, an excitation winding 2 is connected to a bearing yoke 1 installed inside a bearing box 10.
wrapped around the bearing yoke 1, keeping a gap 7 inside the bearing yoke 1,
A rotor 3 is disposed integrally with a rotating shaft 4, and a bearing action is performed by the magnetic attraction between the bearing yoke 1 and the rotor 3.

A radial displacement detector 5 for measuring the relative displacement between the rotor 3 and the yoke 1 is installed on the side of the bearing yoke 1 in the bearing box 10.
On the other side (on the right side in the figure), there is also an abnormality bearing 6, which maintains a gap 8 with the rotating shaft 4 and supports the rotating shaft when the magnetic bearing malfunctions, in the bearing box 10. installed on. The air gap 8 is set smaller than the air gap 7 of the magnetic bearing section, and when the magnetic bearing malfunctions, the abnormality bearing 6 supports the rotating shaft 4, and the bearing yoke 1
This prevents damage to the magnetic bearing due to contact between the rotor 3 and the rotor 3.

The radial displacement detector 5 is connected to a control circuit (not shown) comprising a displacement detection circuit, a phase j+li compensation circuit, a current amplification circuit, an excitation current detection circuit, etc.
The output signal of the displacement detector 5 is introduced into the control circuit, and a control current is supplied to the excitation winding 2 to generate a magnetic attraction force between the bearing yoke l and the rotor 3, thereby achieving smooth bearing action. I'm letting it go.

(Problems that the invention attempts to solve) In the conventional magnetic bearing described above, the abnormality bearing 6 is composed of one integrally formed rolling bearing, so the outer diameter of the rotating shaft 4 is large. Accordingly, the dimensions of the abnormality bearing 60 also increase accordingly.

Moreover, these bearings are used under conditions of relatively high dmN values, ie, high speeds and large diameters, and there are often restrictions on lubrication methods, making them expensive or impossible to manufacture.

In addition, when the rotation +1114 becomes thicker, the bearing yoke 1 is manufactured in half), so having the bearing 6 for use in case of an abnormality in one piece has the problem of being very inconvenient for assembly and disassembly. Ta.

The technical problem of the present invention is to use a small-diameter rolling bearing as a bearing for emergency situations, and to facilitate the procurement, assembly, and disassembly of the bearing.

(Means for Solving the Problems) In order to solve the problems and technical problems of the prior art described above, the present invention provides a radial magnetic bearing that prevents damage to the magnetic bearing and rotating shaft due to malfunction of the magnetic bearing. to prevent
It is characterized in that three or more radial rolling bearings for use in abnormal situations with small outer diameters are arranged in the circumferential direction with gaps smaller than the magnetic bearing gaps and are attached to the mounting body. In addition, regarding implementation.

The mounting body to which the radial rolling bearing for emergency situations is attached is preferably constructed of a mounting plate divided into upper and lower halves.

(Function) Since the present invention is configured as described above, when the magnetic bearing is operating normally, the radial displacement detector 5 detects a normal value, and the distance between the bearing yoke and the rotor is detected. A normal magnetic attraction force acts on the bearing, and the gap value is kept at a normal value, and therefore, the gap value between the abnormality bearing and the rotating shaft is also kept at a normal value.

Further, when the magnetic bearing is malfunctioning, the rotating shaft is first supported by the abnormality bearing and rotates, so the bearing yoke and the rotor do not come into contact with each other. In addition, if the force applied from the rotating shaft to the emergency bearing is abnormally large, it is recommended to bring the rotating shaft into direct contact with the support of the emergency bearing.
The braking force acts on the rotating shaft, and the bearing yoke and the rotating shaft do not come into contact with each other.

(Example) Next, implementation example 11 of the present invention will be described with reference to the drawings.

FIG.
) is a front view, in which the same reference numerals as in FIG. 3 indicate the same or similar parts. That is, in the figure, 1 is the bearing yoke, 2 is the excitation winding, 3 is the rotor, and 4 is the rotating shaft%.
5 is a radial displacement detector that measures the relative displacement between the bearing yoke 1 and the rotor 3, and is equipped with a known control circuit (not shown) consisting of a displacement detection circuit, a phase compensation circuit, a current amplification circuit, a pressure magnetic current detection circuit, etc. The fact that it is connected to is no different from the conventional one.

In this embodiment, three abnormality bearings 11 for use in case of magnetic bearing malfunction are arranged at equal intervals in the circumferential direction, and are supported by mounting plates 13VC through elastic rods 12. ing. The mounting plate 13 is made up of two mounting plates 13a and 13b that are divided into two parts, each of which is mounted on the bearing box 10 while holding the rotating shaft 4 and the air gap 9.One mounting plate 13a has a , 2 small outer diameter circular rolling bearings 1
1.11, and one similar rolling bearing 11 is mounted on the other mounting plate x3b via the rotating shaft 4 and the gap 8, respectively.

The gap 7 in the magnetic bearing section, the gap 8 in the abnormal bearing section J), and the gap 9 between the mounting &13 and the rotating shaft 4 are as follows: maximum amplitude).

Next, to explain the operation, when the magnetic bearing is operating normally, that is, when the force applied to the magnetic bearing by the rotating shaft 4 is within the normal range, the radial displacement detector 5 detects a normal value. When a normal magnetic attraction force is exerted between the bearing yoke 1 and the rotor 3, and the magnetic bearing is malfunctioning, the rotating shaft 4 is first supported by three rolling bearings 11 for emergency use. If the force from the rotating shaft 4 to the bearing 11 is abnormally large, the elastic rod 12 supporting the bearing 11 is deformed and the rotating shaft 4 and the mounting plate 13 are are in direct contact with each other, and a braking force acts on the rotating shaft 4. Therefore, even if the magnetic bearing malfunctions, the bearing yoke 1 and the rotor 3 do not come into contact with each other.

According to this embodiment, since the abnormality bearing is constructed using three or more small diameter rolling bearings 11, the degree of freedom in selecting the outer diameter of the bearing to be used is increased, and the bearing is inexpensive and easily available. Bearings can now be used.

In addition, the bearing for abnormality is attached to the mounting plates 13a and 13, which are divided into two.
Since a large number of bKs are arranged and installed, it is no longer necessary to penetrate the end of the rotating shaft and fix the integrated rolling bearing in a predetermined position. The only replacement part, the bearing for emergency situations, is easier to assemble and disassemble, reducing maintenance costs.

In the above-mentioned embodiment, the structure in which the abnormality bearing is configured using three rolling bearings has been described, but it goes without saying that more than three rolling bearings may be used, and in that case,
They can be distributed and installed as appropriate on the two-piece mounting plate.

(Effects of the Invention) As explained above, according to the present invention, the bearing for use in abnormal situations such as magnetic bearing malfunction is constructed by arranging three or more Ginoal rolling bearings in the circumferential direction. The degree of freedom in selecting a bearing for use in abnormal situations is increased, and a bearing with a small outer diameter that is inexpensive and easily available can be used. At the same time, assembly and disassembly become easier, and maintenance costs can be reduced.

[Brief explanation of drawings]

Figure 1 shows an embodiment of the present invention:) A vertical cross-sectional view of a radial magnetic bearing, Figure 2 is a cross-sectional view of the main part taken along the line ■-■ in Figure 1, and Figure 3 is a cross-sectional view of a conventional radial magnetic bearing. FIG. 2 is a longitudinal cross-sectional view similar to FIG. 1; 1--Single bearing yoke, 2-m-excitation winding, 3-m-rotor, 4-m-rotating shaft, 5-m-radial displacement detector, 71--magnetic bearing gap, 8 ---1 Bearing gap during abnormality, 9--1 Mounting plate gap, 10--h
IT receiving box, 11-11 Rolling bearing for emergency use, 1
2-m-elastic rod, 13, 13a, 13b-m-mounting plate. L□ Figure 2

Claims (1)

[Claims] 1. A bearing yoke, an excitation winding, and a rotor radial displacement detector are provided, the output signal of the displacement detector is introduced into a control circuit, and a control current is supplied to the excitation winding. In the radial magnetic bearing that performs a bearing action between the bearing yoke and the rotor, a radial rolling bearing with a small outer diameter for use in abnormal situations is used to prevent damage to the magnetic bearing and rotating shaft due to malfunction of the magnetic bearing. 3 in the circumferential direction with a gap smaller than the magnetic bearing gap.
A magnetic bearing characterized in that more than one magnetic bearing is arranged and attached to a mounting body. 2. The magnetic bearing according to claim 1, wherein the radial rolling bearing for use in abnormal situations is attached to a mounting plate divided into upper and lower halves.