JPS595175B2 - magnetic bearing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic bearing used in a rotating body such as a separation device.

As shown in FIG. 1, a conventional magnetic bearing of this type has rotor teeth 2, a, and 2b integrally formed on the outside of a rotor yoke 2 made of magnetic material 10, which is attached to a rotatably provided shaft 1. stator yokes 4a, 4 having stator teeth 5a, 5b arranged to sandwich the rotor teeth 2a, 2b;
b are respectively attached to both ends of the permanent magnet 3, and a non-magnetic conductor 6a is attached so as to surround the stator teeth 5a, 5b.
6b are attached to the stator yokes 4a and 4b, respectively.

In the bearing configured as described above, as shown in FIG.
A, 2b - stator teeth 5b - stator yoke 4b - permanent magnet 3 form a circulation circuit.

Now, when the shaft 1 vibrates, the rotor teeth 2a and 2b also vibrate, so the magnetic flux T also changes 25 due to the vibration of the magnetic path. At this time, an eddy current is generated due to a change in the amount of magnetic flux passing through the nonmagnetic conductors 6a and 6b, and this acts as a damping force to damp the vibration of the rotating body. The vibration damping effect due to the eddy current will be explained with reference to FIG. 2. The vibration of the rotor yoke 2 causes eddy currents 11 to occur in the non-magnetic conductors 30 and the heavy bodies 6a, 6b.

The magnitude of the eddy current 11 related to the damping effect is determined by the rapid change in the magnetic flux T passing through the non-magnetic conductors and the heavy bodies 6a, 6b, and the amount of magnetic flux. In particular, the recessed portions 9a, 9b of non-magnetic conductive material,
Passing 35 more magnetic fluxes T through 10a, 10b and their vicinity increases the eddy current 11. However, in the conventional system (FIG. 1), the magnetic flux T is caused by magnetic stator teeth 5a, 5b and rotor teeth 2a, 5b. Since the amount of magnetic flux concentrated in 2b and passing through the recessed portions 9a, 9b, 10a, and 10b of the nonmagnetic conductor is small, the generation of eddy current 11 is also reduced, and the damping effect is reduced. Because it is impossible to suppress the vibration of the rotating body, it is impossible to operate the rotating body stably at high speed, and to prevent the whirling phenomenon at low speeds that is promoted by the residual magnetism of the rotor teeth. I can't.

As a countermeasure for this, in order to increase the vibration damping effect, an inner auxiliary ring 8a having the same height as the height h1 of the rotor teeth 2a and 2b is attached to the inside of the rotor yoke 2, as shown in Fig. 3. It is something. If configured like this, the conventional one (
(Fig. 1), from the stator tooth 5a to the inner auxiliary ring 8a.
Since a magnetic flux passing through the magnetic conductor is generated, the eddy current generated near the recessed portion 9a of the non-magnetic conductor increases, so that the vibration damping effect is increased compared to the conventional one. b. With the structure shown in FIG. 3, it is not possible to obtain a vibration damping effect sufficient to stably rotate the rotating bodies 1 and 2. That is, in the conventional example shown in FIG. 3, although the rotating shaft 1 extends beyond the height of the rotor teeth 2a and 2b, this does not provide a sufficient vibration damping effect.

The part where the rotating shaft 1 exceeds the rotor teeth 2a is called the upper protruding part 1a.
In this case, if the rotating shaft 1 is made of a magnetic material, magnetic flux will certainly pass between the stator teeth 5a and the upper protrusion 1a. However, since the gap length t between the stator teeth 5a and the upper protrusion 1a of the rotating shaft 1 is large, the amount of passing magnetic flux is small, and the vibration damping effect is also small, which is not sufficient. In view of the above, it is an object of the present invention to provide a magnetic bearing with a large vibration damping effect, in which an auxiliary ring is provided at one or both of the inner and outer ends of a rotor yoke having rotor teeth. The auxiliary ring is characterized in that the height of the auxiliary ring is greater than the height of the rotor teeth. Embodiments of the present invention will be described below with reference to the drawings.

The same reference numerals as in FIGS. 1 and 3 indicate the same parts behind the reference numerals shown in FIGS. 4 to 12. The embodiment shown in FIG. 4 differs from the embodiment shown in FIG. 3 in that the height H2 of the inner auxiliary ring 8b formed integrally with the rotor yoke 2 is higher than the height h1 of the rotor teeth 2a and 2b. With this configuration, as shown in FIG. 5, the magnetic flux 7 generated by the permanent magnet or electromagnet 3 will reach the rotor teeth 2a from the stator 4a through the stator teeth 5a, as in the conventional case. Child tooth 5a
Two magnetic flux paths are formed from the inner auxiliary ring 8b through the non-magnetic conductor 6a. Since the height H2 of the inner auxiliary ring 8b is larger than the height h1 of the rotor teeth 2a and 2b, the inner auxiliary ring 8b made of magnetic material is provided close to the stator teeth 5a. , from the stator tooth 5a through the non-magnetic conductor 6a to the inner auxiliary ring 8b.
The amount of magnetic flux that reaches this increases compared to the conventional one. Similarly to the above, the magnetic flux naturally forms a flux path from the rotor teeth 2b and the inner auxiliary ring 8b, through the stator yoke 4b, and back to the permanent magnet 3. Therefore, the amount of magnetic flux passing through the recessed portions 9a, 10a of the non-magnetic conductors 6a, 6b increases compared to the conventional one, and the eddy current generated due to changes in the magnetic flux 7 due to vibration of the shaft 1 increases. , it is possible to obtain a greater vibration damping effect than conventional ones. FIG. 13 shows the results of actually measuring the difference in damping effect between the embodiment shown in FIG. 4 and the conventional example shown in FIG. 3. Graph I in Figure 13 shows the damping effect of the conventional example in Figure 3, which is 10
It is set at 0%. A graph shows the vibration damping effect of this embodiment shown in FIG. As is clear from FIG. 13, in the example of the present invention, a damping effect of about 140 (fl) can be obtained. This shows that the eddy current loss generated in the nonmagnetic conductor is 1.4 times larger in the embodiment shown in FIG. 4 than in the conventional example shown in FIG. 3. Therefore, in this embodiment, the vibration damping effect is increased, so that the vibration of the rotating body can be strongly suppressed. In another embodiment shown in FIG. 6, magnetic rings 12a and 12b are attached to the upper and lower parts of the inner auxiliary ring 8a of the rotor.
The height H3 of the rotor teeth 2a and 2b is higher than the height h1 of the rotor teeth 2a and 2b. Further, as shown in FIG. 7, only the upper side (or lower side) of the inner auxiliary ring 8b is made higher,
Alternatively, the inner auxiliary ring 8b may be formed in the shape shown in FIG. Further, as shown in FIG. 9, an outer auxiliary ring 8d having the same height as the inner auxiliary ring 8b may be provided at the outer peripheral end of the rotor yoke 2. Another embodiment shown in FIG. 10 is provided with an inner auxiliary ring 8b that is higher than the height of the rotor teeth 2a and 2b, and has auxiliary stator teeth on both (or one of) the inner and outer sides of the stator teeth 5a and 5b. 5
, 5S, 5chi, 5~ are provided.

In another embodiment shown in FIG. 11, stator teeth 14a, 2c of rotor yoke 2 are arranged opposite to rotor teeth 2a, 2c through a non-magnetic conductor 6a. 14b and the permanent magnet 3, and the height of the inner auxiliary ring 8c is set to the rotor tooth 2a. It is formed higher than the height of 2e.

Further, as shown in FIG. 12, the stator teeth 14a, 14b
Auxiliary stator 1 on the outside (or inside, inside, outside) of
4c and 14d may be provided respectively. It goes without saying that the embodiments shown in FIGS. 6 to 12 described above have the same effects as the embodiment shown in FIG. 4.

As explained above, according to the present invention, it is possible to obtain a large vibration damping effect, so that the vibration of the rotating body can be suppressed, the rotating body can be operated stably at high speed, and it is possible to suppress the vibrations of the rotating body, which is facilitated by residual magnetism. It is possible to prevent the whirling phenomenon at low speeds.

[Brief Description of the Drawings] Figures 1 and 3 are cross-sectional views of conventional magnetic bearings, Figure 2 is an explanatory diagram of the magnetic action of the bearing, and Figure 4 is an embodiment of the magnetic bearing of the present invention. FIG. 5 is a diagram illustrating the magnetic effect of the bearing, and FIGS. 6 to 12 are sectional views of main parts of other embodiments of the present invention. FIG. 13 is a graph for explaining the anti-vibration effect of the embodiment shown in FIG. 1...Rotation axis, 2...
・Rotor yoke, 2a, 2b...Rotor tooth, 5
a, 5b...Stator tooth, 3...Permanent magnet, 5a, to 5, 51' 5b, 5b, 5''b...
...Auxiliary stator tooth, 8b. 8c, 8d... Auxiliary ring.

Claims (1)

[Scope of Claims] 1. A rotating body consisting of a rotating shaft and a rotor yoke fixed to the shaft and having rotor teeth; A stator is constituted by stator teeth arranged to face the teeth, and a permanent magnet or an electromagnet that holds the stator teeth and is arranged at the other end, so as to wrap around the rotor teeth and stator teeth. In a magnetic bearing equipped with a non-magnetic conductor arranged in A magnetic bearing characterized by its large size. 2. The magnetic bearing according to claim 1, wherein only either the upper side or the lower side of the auxiliary ring is increased in height. 3. The magnetic bearing according to claim 1, characterized in that auxiliary stator teeth are provided on either or both of the inside and outside of the stator teeth.