JPS6327577B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic bearing having a radial damping function.

A rotating device that is supported in the thrust direction by a controlled magnetic bearing and in the radial direction by a repulsion magnetic bearing (uncontrolled) can have a damping effect because the thrust direction is controlled as it is. However, it does not have a damping function in the radial direction.

Therefore, when vibration occurs in the radial direction due to resonance or disturbance, the amplitude of the vibration becomes extremely large, causing damage to the rotating body.

FIG. 1 shows a conventional magnetic bearing.

11 is a repulsion type radial magnetic bearing (uncontrolled), 2
1 is a thrust direction control type magnetic bearing, and 31 is a rotating shaft.

Conventionally, in order to have a damping effect in the radial direction, a conductor like A was attached and an eddy current damping mechanism was installed, but with this eddy current damping mechanism, the damping force is proportional to the amount of change in magnetic flux. Therefore, the effect is unsatisfactory especially when the bearing has a low resonance point, such as a magnetic bearing.

The present invention aims to improve the above-mentioned conventional drawbacks, and one of its objectives is to have an effective damping effect even at low frequencies, to have a relatively simple mechanism, and to use a compact magnetic bearing. It's about getting.

An embodiment of the present invention will be described below with reference to FIG. The thrust bearing part is the same as before, 1 is a permanent magnet, 2 is a control coil, 3 is a yoke on the rotor side, 4
is the yoke on the stator side. 3 and 4 are magnetic materials. 5 is a permanent magnet fixed to the rotating shaft 8 of a repulsion type radial magnetic bearing (uncontrolled). Among the three permanent magnets 6 on the stator side, the central magnet 6' is movable in a radial direction perpendicular to the rotating shaft 8. The remaining two permanent magnets 6'' are fixed to a fixture 7. This fixture 7 is a non-magnetic material.The arrangement of the respective permanent magnets 6' and 6'' is such that they repel each other as shown in Figure 2. Furthermore, the magnet 5 on the rotating shaft 8 side and the magnet 6 on the stator side are also arranged to naturally repel each other. The radius of the movable magnet 6' is set larger than the radius of the fixed magnet 6''. This is so that the magnet 6' can exist stably. The difference in radius between the magnets 6' and 6'' is According to theory, the resonant frequency of the entire rotating shaft is determined to match the resonant frequency of the magnet 6'. 8 is a rotating shaft made of a non-magnetic material. A viscous substance 9 such as oil is sealed between the fixing fitting 7 and the fixed magnet 6'' to adjust the damping force. However, even without this viscous substance 9, air acts as a viscous substance and the magnet 6' Since it is supported, the same effect can be obtained.

According to the present invention, the movable magnet, which has a natural frequency that matches the resonance frequency of the rotating body, is repulsively supported between the fixed magnets with the viscous body interposed, so that the movable magnet is at the resonance point of the rotating body. It moves smoothly, and the vibration energy of the rotating shaft of the rotating body is transferred to the vibration energy of the movable magnet 6', and the energy is consumed by the friction between the fixed bracket 7 and the movable magnet 6' and the viscosity of the viscous body 9 between them, resulting in damping. A damping force is generated, which dampens the resonance vibration of the rotating body in particular, and has the effect of suppressing the vibration to a small level.The damping force, which is a drawback of conventional eddy current damping mechanisms, is weak (especially at low frequencies). can be improved. Also, since the mechanism is simple, it is possible to use a small bearing.

Although it is a known technique, it goes without saying that the effect can be further improved by providing a damping improver on the fixing fitting.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a conventional magnetic bearing, and FIG. 2 is a longitudinal sectional view of a magnetic bearing having a radial bearing and a damping mechanism according to the present invention. 1... Permanent magnet, 2... Coil, 3... Yoke, 4... Yoke, 5... Permanent magnet, 6, 6',
6″...Permanent magnet, 7...Fixing metal fitting, 8...Rotating shaft, 9...Viscoelastic body.

Claims (1)

[Claims] 1. In a rotating body bearing having a controlled magnetic bearing in the thrust direction and an uncontrolled repulsion magnetic bearing in the radial direction, the stationary side magnet of the radial bearing is fixed to the stationary side by a fixing member. It has a fixed magnet and a movable magnet having a natural frequency that matches the resonance frequency of the rotating body, and a viscous body is interposed between the movable magnet and the fixed member, and the movable magnet is connected to the rotating body using the fixed magnet. What is claimed is: 1. A magnetic bearing characterized in that it is configured to be movable in a direction perpendicular to the rotation axis of a rotating body, and to enhance a damping effect in the radial direction.