JPH045771Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a bearing that uses magnetic repulsion to support a rotating body, that is, a magnetic bearing device, and particularly relates to a magnetic bearing device that has a balancing function.

[Conventional technology]

Bearings are mechanical elements that perform important functions such as holding rotary or reciprocating mechanical parts, guiding their movements, and minimizing friction and wear.
In addition to general mechanical bearings, there are magnetic bearing devices in which magnets are placed on the rotating side and the stationary side and magnetic repulsion is used as a supporting force. Used in machine tool spindles, etc.

[The problem that the invention attempts to solve]

This type of magnetic bearing device is required to have more functionality than a general bearing due to the functional requirements of the mechanical device to which it is applied. One example is the balancing of rotating bodies.

The only difference between conventional magnetic bearing devices and other magnetic bearing devices is that they use magnetic repulsion as a supporting force, and they are still used as bearings for rotating bodies, where balancing is particularly important to achieve smooth rotation. It wasn't satisfying.

Therefore, the purpose of this invention is to perform normal balancing (balancing machine, field balancing)
It is an object of the present invention to provide a magnetic bearing device that achieves stable rotation by eliminating unbalances that cannot be removed by other methods, as well as unbalances that occur due to wear of the rotating body during rotation, attachment of artifacts, etc.

[Means for solving problems]

That is, the present invention is a magnetic bearing device in which an annular permanent magnet is arranged on the rotating body side and an annular permanent magnet or an electromagnet is arranged on the stationary side, and the annular permanent magnet on the rotating body side is arranged in the circumferential direction. By dividing the segment into a plurality of segments and forming gaps between the segments that allow mutual movement in the circumferential direction on the rotating body, each segment can move in the circumferential direction relative to the rotating body, and this movement is possible. The feature is that a balancing function is obtained through segments.

[Effect]

By taking such measures, the annular permanent magnet segment on the rotating body side is
By making it slightly movable in the circumferential direction, an auto-balancing function is created in this part, which removes the unbalance left by normal balancing and the unbalance that occurs during rotation.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

Prior to explaining this embodiment, an automatic balancing function (auto-balancing) based on self-synchronization in a whirling vibration system of a rotating body will be outlined. That is, according to the document "'About self-synchronization of vibrating machines (second report)'" by Inoue et al. (Nikkiron vol. 33. No. 246), the following is explained.

(A) Figure 2 shows a model of the rotor system (rotation speed Nrpm). Reference numeral 1 denotes a rotor main body, and its shaft 2 is supported by a bearing 3 and rotates. Although a vertical rotor will be described here, it may be in other orientations. 4 is a part of the rotor 1, which is a hollow circular groove arranged concentrically and at right angles to the rotation axis CC. 5 is a hole drilled at the top (often ring-shaped), 7
is a cover that extends inward from the outer periphery of the hollow circular groove 4 in an overhanging manner. Inside the hollow circular groove 4,
There are two balls 6 that can move freely within the hollow circular groove 4. Ball 6 is an unbalance automatic compensation element. (In the following, we will explain the case where two of the same balls 6 are included with reference to Figure 2, but the same applies even if there are two or more balls with different diameters.Furthermore, the shape of the balls 6 is not spherical. (In both cases, it is sufficient to move freely within the hollow circular groove 4.) In the above, members 4 to 7 having the same functions as members 4 to 7 are collectively referred to as automatic balancing elements. 8 shows a model in which the unbalance of the rotor is concentrated (mass Mo).

In order to simplify the explanation below, the auto-balancing function will be outlined in the case where the rotor system is represented by a one-degree-of-freedom vibration system.

() In Fig. 2, when the rotor 1 is rotated without the balls 6 inserted, a centrifugal force MoRω ² acts on the rotor 1 due to the unbalance 8, and the vibration amplitude of the rotor 1 is as shown by the solid line in Fig. 3. become.
(R; Radius of Mo's center of gravity, ω=2πN/60,
Nrpm). In other words, the maximum value occurs when N≒No (critical speed), and the amplitude does not become 0 even when N≫No.
Vibrations remain due to the eccentricity of the rotor center of gravity. In order to reduce this to 0, it is possible to set Mo to 0, but as a practical matter, this is not possible, and the size of Mo will fluctuate due to local wear of the rotor 1, adhesion of foreign matter, etc. during use. .

() In Fig. 2, when the ball 6 is inserted and rotated by taking advantage of the function of the automatic balancing element, the ball 6 follows the outer circumference of the hollow circular groove 4, and the vibration amplitude a of the rotor 1 is as shown by the dashed line in Fig. 3. It can become like that. That is, when N>No, balancing is automatically performed by the automatic balancing effect by self-synchronization, and the amplitude a becomes 0. At this time, the ball 6 is stopped relative to the rotor as shown in Fig. 2b,
In the case of FIG. 2, the following equation is satisfied.

MoR=2mrcosθ ₀ m: Mass of one ball r: Distance between the center of gravity of the ball and the center of rotation of the rotor In other words, the material rotating with the rotor 1 has a degree of freedom that allows it to move in the circumferential direction relative to the rotor 1. It is known that when two or more of these exist, an auto-balancing function occurs above the natural frequency (critical speed) of the rotor system.

(B) When permanent magnets are used as bearings in a rotor system, at least a permanent magnet is often used on the rotating body side for power supply reasons, as illustrated in Figure 1. In this case, the permanent magnet on the rotating body side is often arranged in a ring shape, but the end faces of each segment are brought into close contact with each other, and the fit with the rotor side is tight so that the magnet does not touch the rotor. I try not to move as much as possible.

The present invention applies the above auto-balancing principle to a magnetic bearing member, and uses a permanent magnet segment provided on the rotating body side as a member corresponding to the ball 6 to perform auto-balancing of the rotating body in addition to the magnetic bearing function. It also has functions.

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 1a illustrates a case where a repulsion type magnet is used as a radial bearing. Center of rotation C on rotor 1
A ring-shaped groove 10 concentric with -C is provided, and the divided permanent magnets 9 are arranged in the ring-shaped groove. The magnets 3 are also arranged in a ring shape on the stationary side (with a radial gap of generally 1 to 2 mm or less relative to the rotor 1). The magnet 3 may be a permanent magnet or an electromagnet, but by facing the permanent magnet 9 with the same polarity, a repulsion type magnetic bearing 3 is formed in this part. 11 is a cover of the permanent magnet 9.

FIG. 1b shows only the rotating side of the section BB in FIG. 1a. The permanent magnet 9 is circumferentially divided into a plurality of segments (six in FIG. 1b), and an average gap is provided between each segment in the circumferential direction. Usually 0.5~1
Although it is often less than mm, there is no particular limitation. Furthermore, the permanent magnet 9 has a gap δ in the radial direction with respect to the ring-shaped groove 10, and a gap similar to δ is also provided with respect to the cover 11. (δ is usually 0.1 to 0.5 mm or less.) Furthermore, lubricating oil may be injected and sealed into the gap between the ring-shaped groove 10 and the permanent magnet 9. From the above, it can be said that the segments of the permanent magnet 9 are movable relative to the rotor 1 within the ring-shaped groove 10.
If the magnet 9 rotates relative to the rotor 1, it will lose its balance, so either glue at least one of the segments to the rotor side (outside wall) or
A stopper is often placed at at least one location on the circumference of 0. 8 is an unbalance similar to that shown in FIG.

The effect of the above configuration is as follows. That is, when the rotor 1 is rotated in the state shown in FIG.
Since the segments of the permanent magnets 9 are movable at least slightly in the circumferential direction with respect to the rotor 1, an auto-balancing effect is produced in the region where N>No as shown by the dashed-dotted line in FIG. At this time, permanent magnet 9
Each segment automatically performs balancing by moving in the direction opposite to the imbalance, as illustrated in FIG. 1c.

Furthermore, if the gap δ in Fig. 1 is made smaller to make it a little more difficult for the permanent magnets 9 to move relative to the rotor 1, the balance can be achieved little by little each time it rotates, and at the same time, even if N<No, the balance becomes difficult to collapse, and the rotor amplitude approaches the state indicated by the broken line in FIG.

Although the magnets on the rotating side and the stationary side face each other in the radial direction in FIG. In this case, similar structures, actions, and effects can be expected. The same applies to the case where the rotating side and the stationary side are arranged at an angle with respect to the rotation axis.

[Effect of idea]

As detailed above, the magnetic bearing device according to the present invention divides the annular permanent magnet on the rotating body side into a plurality of segments in the circumferential direction, and the segments can be mutually movable in the circumferential direction on the rotating body. By forming a gap, each segment is movable in the circumferential direction relative to the rotating body, and the movable segments provide a balancing function.

According to this configuration, the annular permanent magnet segment on the rotating body side can be moved slightly in the circumferential direction with respect to the rotor, so that an auto-balancing function is created in this part, and the unbalance that remains after normal balancing is eliminated. This eliminates the unbalance that occurs during rotation and provides a magnetic bearing device that achieves stable rotation.

[Brief explanation of the drawing]

Figures 1a, b, and c show an embodiment of the present invention,
Figure 1a is a front view, Figures 1b and c are respectively Figure 1a
Fig. 2a and b show autobalance, Fig. 2a is a front view, and Fig. 2b is a sectional view taken along the A-A direction of Fig. 2a. , FIG. 3 is a diagram of the vibration characteristics of the rotor. 1... Rotor, 2... Rotor shaft, 3... Bearing (magnet), 4... Hollow circular groove, 5... Hole, 6... Ball,
7...Cover, 8...Unbalance, 9...Permanent magnet, 10...Ring-shaped groove, 11...Cover.

Claims (1)

[Scope of utility model registration request] In a magnetic bearing device in which an annular permanent magnet is arranged on the rotating body side and an annular permanent magnet or an electromagnet is arranged on the stationary side, the annular permanent magnet on the rotating body side is divided into a plurality of segments in the circumferential direction, By forming gaps between the segments that are movable relative to each other in the circumferential direction on the rotating body, each segment is movable in the circumferential direction relative to the rotating body, and the movable segments provide a balancing function. A magnetic bearing device characterized by: