JPH0343467Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a magnetic bearing used in high-speed rotating equipment. FIG. 1 is a longitudinal sectional view showing an example of a conventional magnetic bearing. In Figure 1,
The rotating body 2 is attracted upward or downward due to the attractive force generated by the upper and lower permanent magnets 5a and 5b. In order to eliminate this unbalanced force, the position detector 1
0, the position of the rotating body is known, and a control current corresponding to the position is passed through the coils 7a, 7b, so that the thrust direction is always maintained at a constant position. Furthermore, by making the shape of the yoke into a mutually concentric annular tooth shape, when the rotating body 2 moves in the radial direction, a magnetic restoring force acts to return it to the original position concentric with the fixed body. The magnetic bearing of FIG. 1 thus produces thrust and radial bearing effects.

Magnetic bearings are usually equipped with ball bearings 3a and 3b as shown in Figure 1 as a safety measure against abnormal vibrations at the resonance point of the shaft, power outages, and other unexpected situations. This ball bearing is called a touch-down bearing because it applies braking force when dropped (touch-down). However, with conventional touch-down bearings, if a touch-down occurs during high-speed rotation, the impact force cannot be absorbed much and the rotating body and stationary body are hit hard.
There were drawbacks such as the rotating body becoming unbalanced and the mechanical precision before touch down becoming impossible to reproduce.

The purpose of this invention is to eliminate such drawbacks, absorb the impact force of the rotating body when touched down during high-speed rotation, and make it possible to reproduce the mechanical accuracy after touching down.

FIG. 2 is a longitudinal sectional view showing an embodiment of this invention, in which upper and lower touch-down bearings 3a, 3b are provided with shock absorbers (shock absorbers) 13a, 1.
3b, 13c, and 13d, shock absorbers 13a, 13 absorb the impact force of the rotating body 2 when touched down during high-speed rotation.
b in the thrust direction and radial direction, 13c,
13d can be dispersed and absorbed in the radial direction, making it possible to safely touch down. This has great practical effects, such as making it possible to reproduce the mechanical accuracy of the bearing before it was touched down. Furthermore, although this invention has been described with respect to a uniaxially controlled magnetic bearing, it goes without saying that the same effect can be obtained when it is used in a multiaxially controlled magnetic bearing.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of a conventional magnetic bearing, and FIG. 2 is a longitudinal sectional view showing an embodiment of a magnetic bearing according to this invention. In the figure, 1 is a fixed body, 2 is a rotating body, 3a,
3b is the upper and lower touch down bearing, 4a, 4b
are the upper and lower yokes of the rotating body, 5a and 5b are the upper and lower permanent magnets, 6a and 6b are the upper and lower yokes of the fixed body, and 7a and 7
b is its excitation coil, 8 is a stator of the motor, 9 is a rotor of the motor, 10 is a position detection device, 11 is a position control device, 12 is its amplifier, 1
3a, 13b are vertical thrust shock absorption devices, 13
c, 13d are upper and lower radial shock absorbers.
Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] In a magnetic bearing that levitates a rotating body relative to a stationary side using magnetic force and receives the bearing, when the magnetic bearing becomes uncontrollable, the touch-down bearing that supports the rotating body is moved in the thrust direction and the radial direction. What is claimed is: 1. A magnetic bearing comprising: a shock absorbing device for holding the rotating body so as to be movable;