JPS6230565A - Magnetic bearing apparatus - Google Patents

Abstract

PURPOSE:To facilitate the correction of a balance without performing the grinding of unbalanced quantity or the re-bending of out of roundness, by allowing the unbalance of a primary dangerous speed to be well-balanced by the magnetic eccentricity of the permanent magnet mounted to a rotor. CONSTITUTION:It is assumed that there is predetermined unbalance quantity 10 in the rotor 1 of a magnetic bearing apparatus when the axis theta thereof is set to center of rotation. Herein, when there is magnetic eccentricity (e) in the permanent magnet 3 in the side of the rotor 1, the center of rotation of the rotor 1 shifts by a distance X from the axis theta and unbalance quantity of U=MX (wherein M is integral dm: total mass of rotor) is generated in the rotor 1. If the magnet 3 having magnetic eccentricity quantity such that the unbalance quantity becomes equal to the unbalance quantity 10 of the rotor 1 itself is used, the unbalanced quantity 10 of the rotor 1 itself is offset.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a magnetic bearing device in which an imbalance in the primary critical speed of a rotating body is balanced by the magnetic eccentricity of a permanent magnet attached to the rotating body. .

([(lE[[fi,!=+(7)I!m!!ri
.

A shaft that supports the radial load of a high-speed rotating body
□A magnetic bearing device is known as a bearing. FIG. 5 shows an example of this type of device. In the figure, 1 is a vertical rotating body, and a reinforcing ring 1'j is attached to the upper end of this rotating body 1.
2 @ f'r L T 1! (t, 2” W e
1lfk (7);jC'A11E (11(7)
'Permanent magnet) 3 is fixed. Reinforcement ring 2 is
It is made of a non-magnetic material, and the permanent magnet 3 is fitted by means such as press-fitting or shrink-fitting.

On the other hand, at a position facing the upper end surface of the permanent magnet 3, a permanent magnet (second permanent magnet) 4 magnetized so as to be attracted to the magnet 3 is fixed to a stationary body 9. In addition, 5 in the figure
is a position sensor 1 that detects the horizontal position of the rotating body 1;
1 indicates a screw that fixes the reinforcing ring 2 to the rotating body 1.

Incidentally, the rotating body 1 generally has an unbalance, and this unbalance causes an imbalance in the primary critical speed of the rotating body 1. For this reason, the unbalance of the rotating body 1 is measured in the field or the like, and the balance is achieved by cutting the upper end plate of the rotating body 1 or bending the straightness of the rotating body 1.

However, the above balancing method may have the following problems. That is, when the rotational speed of the rotating body 1 increases, the shaved portion of the upper end plate becomes weak, and there is a risk that this portion will be destroyed by centrifugal force. In addition, if the balance is performed by correcting the straightness of the rotating body 1, it will affect other critical speeds,
If the rotating body 1 is corrected by compositional deformation, the thin wall portion may be destroyed during the correction, or the balance may be lost due to returning to the original straightness direction. Also, if you repeat this method many times,
The strength decreases and it may break during high-speed rotation.

In other words, the above-mentioned method is time-consuming and requires careful attention, resulting in the problem that it takes too much time to correct the balance.

(Object of the Invention) The present invention has been made in consideration of the above circumstances, and its purpose is to correct the balance of a rotating body without the need for unbalance grinding or straightness rebending. It is an object of the present invention to provide a magnetic bearing device that can easily perform the following steps, improve balance accuracy, and improve productivity.

[Summary of the invention]

The gist of the present invention is to compensate for the amount of unbalance that occurs in the rotating body using the magnetic eccentricity of the permanent magnet on the rotating body side.

That is, the present invention provides an annular first permanent magnet coaxially attached to a rotating body and an annular second permanent magnet attached to a stationary body that generates a magnetic attraction force between the first permanent magnet and the first permanent magnet. In a magnetic bearing device comprising a magnet and restraining the radial position of the first permanent magnet by the magnetic attraction force, an amount of unbalance of the rotating body caused by magnetic eccentricity (2) of the first permanent magnet. (which can be determined in advance) and the unbalance l of the rotating body itself are balanced.

〔Effect of the invention〕

According to the present invention, the unbalance of the rotating body can be compensated for by the magnetic eccentricity of the permanent magnet on the rotating body side.

In other words, select a magnet with a magnetic eccentricity and phase angle commensurate with the amount of unbalance that occurs in the rotating body, and position this magnet so that its center of magnetization is on the opposite side of the axis of the rotating body from where the unbalance occurs. By attaching it to a rotating body, the dynamic balance can be easily corrected. Therefore, there is no need to re-bend the straightness of the unbalanced rotating body or to eccentrically process the permanent magnet on the rotating body side, making it easy to correct dynamic balance and improve mass productivity.

[Embodiments of the invention]

Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIG. 1 is a schematic diagram for explaining the balance correction principle of a magnetic bearing device according to an embodiment of the present invention. The basic structure is the same as that shown in FIG. 5, except that the permanent magnet 3 is made of a magnetically decentered magnet.

It is assumed that an unbalance 110 occurs in the rotating body 1 when its rotation center is around the axis θ. Here, if there is a magnetic eccentricity e in the rotating body side permanent magnet 3 (first permanent magnet),
The rotation center of the rotating body 1 is shifted by a distance X from the axis θ. In this case, one rotating body 1 has U″″MX.

An unbalance amount (imbalance correction amount) occurs. In addition,
'□In the above equation, M is /dm: the total mass of the rotating body, and U: represents the amount of unbalance. Therefore,
The above unbalance correction amount and the unbalance amount of the rotating body itself10. !
:#lL, .

If a magnet 3 with a magnetic eccentricity such that
□The unbalance 110 of the rotating body itself is canceled out28, 1 Figure 2 shows the response amplitude due to the influence of the magnetic eccentricity of the permanent magnet 3 (3 balanced degrees) when the rotating body 1 is dynamically balanced. Quantity/imaging amplitude)') Phase I/actual'''#').

FIG. establish such a relationship in advance
If this is determined, when manufacturing a large number of rotating bodies, the dynamic balance can be corrected by simply selecting and assembling permanent magnets 3 with a phase angle of 1111'''1118° and 11°1181.

Here, as a means for measuring the amount of magnetic eccentricity of the permanent magnet 3, as shown in FIG. The magnet 3 may be placed and the position sensor 5 may actually measure the magnetic eccentricity and phase of the permanent magnet 3. Furthermore, as shown in FIG. 4, the above measurement may be performed with the permanent magnet 3 suspended by air 7 or the like.

When actually installing the permanent magnets 3, first, the magnetic eccentricity and phase of various permanent magnets are measured by the method shown in FIG. 3 or 4, and a magnet 3 suitable for the unbalance m10 is selected. Then, this magnet 3 is arranged above the rotating body 1 coaxially with the rotating body 1, and arranged so that the magnetization center of the magnet 3 is located on the side opposite to the side where the unbalance 110 of the rotating body 1 occurs. Fix it. As a result, the center of rotation of the rotating body 1 is shifted from its axis θ by a distance X corresponding to the magnetic eccentricity e of the magnet 3, and the unbalance 10 is compensated for.

Thus, according to this embodiment, the rotating body 1 is ground.

Rebending the straightness of the rotating body 1 and rotating body 1 and permanent magnet 3
The dynamic balance can be easily corrected in a short time without any corrections such as eccentric processing. Therefore, work balance correction work can be facilitated, and economical efficiency and mass productivity can be improved. In addition, structurally, the conventional device can be applied as is, and there are advantages that it can be easily realized by simply selecting the rotating side permanent magnet 3 and setting the arrangement angle.

Note that the present invention is not limited to the embodiments described above, and can be implemented with various modifications without departing from the gist thereof. For example, the means for measuring the amount of magnetic eccentricity of the permanent magnet is not limited to the method shown in FIG. do it. Further, the diameter, magnetization strength, etc. of the permanent magnet may be adjusted as appropriate depending on the specifications.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for explaining the balance correction principle of a magnetic bearing device according to an embodiment of the present invention, and FIG. 2 is a characteristic showing the relationship between the response amplitude between the rotating body unbalance amount and the magnetic eccentricity amount. , S, and 4 are schematic diagrams showing a method of measuring the amount of magnetic eccentricity of a permanent magnet, respectively, and FIG. 5 is a sectional view showing a schematic configuration of an example of a magnetic bearing device. DESCRIPTION OF SYMBOLS 1... Rotating body, 2... Reinforcement ring, 3... Rotating body side permanent magnet (first permanent magnet), 4... Stationary side permanent magnet (second permanent magnet), 5... Position sensor, 6...
Ball bearing, 7... Air, 9... Stationary body,
10...Unbalance amount, θ... Axis center of rotating body, e...
・Magnetic eccentricity of permanent magnet]. Applicant's agent/patent attorney Takehiko Suzue Figure 1 Figure 2 M4 Figure 5

Claims (2)

[Claims] (1) An annular first permanent magnet coaxially attached to a rotating body and an annular second permanent magnet that is attached to a stationary body and generates a magnetic attraction force between the first permanent magnet and the first permanent magnet. In the magnetic bearing device, which restrains the radial position of the first permanent magnet by the magnetic attraction force, the amount of unbalance of the rotating body caused by the amount of magnetic eccentricity of the first permanent magnet and the amount of unbalance of the rotating body caused by the amount of magnetic eccentricity of the first permanent magnet are A magnetic bearing device characterized in that the amount of unbalance of the rotating body itself is balanced. (2) The first permanent magnet has a magnetic eccentricity corresponding to the unbalance of the rotating body itself, and this magnet has a center of magnetization that is closer to the axis of the rotating body than the axis of the rotating body. The magnetic bearing device according to claim 1, wherein the magnetic bearing device is located on a side opposite to the side where the amount of unbalance occurs.