JPH06346631A - Magnetically levitated structure - Google Patents

Abstract

PURPOSE:To properly restrain vibration at low cost by means of a simple structure regardless of changes in movable loads. CONSTITUTION:A staircase 2 is provided vertically swingably with respect to a floor 3a of an upper story and a permanent magnet 5 is interposed between a floor 3b of a lower story and the staircase 2 to impart a levitating force to the staircase 2. And a damping device 7 with a vibration body is attached to the staircase 2 through a compression coil spring and a damper for damping.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention is applied to floors for mounting semiconductor manufacturing equipment such as stairs and clean rooms or floors for mounting various processing equipments, and suppresses the vibration by using an attached vibrating body. A magnetic levitation structure.

[0002]

2. Description of the Related Art As a magnetic levitation structure using a magnet as described above, if the structure is simply levitated by magnetic force, the damping performance against vibration is low.
The second structure is provided to be movable up and down in the first structure, the electromagnet is attached to the first structure, and the magnetic body is attached to the second structure.

A flying height sensor for measuring the flying height of the second structure with respect to the first structure is provided, and
A vibration sensor for measuring the vibration is provided in the second structure, and the flying height sensor and the vibration sensor are connected to a control circuit such as a microcomputer, and the flying height measured in response to changes in the load and vibration. Also, the current flowing through the electromagnet is controlled based on the vibration, and the magnetic force is controlled to suppress the vibration.

[0004]

However, in the case of the above-mentioned conventional example, it is necessary to constantly supply electric power to the electromagnet, which increases the running cost and is uneconomical. There was a drawback that could not be suppressed.

The present invention has been made in view of the above circumstances, and provides a magnetic levitation structure which has a simple structure and is inexpensive, and which is capable of excellently suppressing vibration regardless of changes in the load. The purpose is to do.

[0006]

In order to achieve the above-mentioned object, a magnetic levitation structure according to the present invention is provided with a second structure movably up and down in a first structure,
A permanent magnet that gives a levitation force to the second structure is interposed between the first structure and the second structure, and a spring and a damping damper are interposed in the second structure. It is configured with a vibrator attached.

[0007]

[Function] As a result of intensive studies by the present inventors, for example, the first
In the case of elastically supporting the second structure by interposing a metal spring such as a compression coil spring or a leaf spring or an air spring with respect to the structure, the load applied to the second structure changes. At the same time, since the natural frequency changes significantly (for example, it changes about 30% when the loading load increases or decreases by a factor of 2), the spring of the vibrator to be added may be changed,
While it is necessary to replace the vibrating body with a different weight, when the magnetic force of the permanent magnet is used to levitate the second structure with respect to the first structure, the loading load is increased as described above. Two
The natural frequency changes only about 6% even if it is increased or decreased by a factor of two, and the change in the natural frequency is small. Therefore, the adjustment structure for tuning the natural frequency of the vibrating body to be added with respect to the change in the loading load. In addition, it has been found that it is possible to cope with changes in the payload without performing adjustment work. According to the configuration of the magnetic levitation structure according to the present invention which focuses on this, the levitation force is exerted by the repulsive force utilizing the magnetic force of the permanent magnet to support the second structure on the first structure, and the magnet The magnetic levitation by the permanent magnet that the damping performance is low by adding the vibration configuration of the vibrating body by the spring and the damping damper while naturally responding to the change in the load on the second structure due to the characteristics of the Second to make up for the drawbacks of the configuration
The vibration of the structure can be effectively cancelled.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings.

<First Embodiment> FIG. 1 is an overall side view of a first embodiment of a magnetic levitation structure according to the present invention, FIG. 2 is a plan view thereof, and a second structure having a landing 1 in the middle thereof. The upper end of the stairs 2 as the body is the floor 3 of the upper floor as the first structure.
a is swingably connected about a horizontal axis P, while the lowermost step plate 4a of the step plates 4 of the stairs 2 ...
The permanent magnets 5 ... Are interposed so as to apply a levitation force to the stairs 2 with the lower floor 3b as the structure of FIG.

A vibration damping device 7 is attached to each of the lower portion of the floor frame 6 of the landing 1 of the stairs 2 and the lower surface of a predetermined step plate 4b on the lower side in the longitudinal direction. As shown in the vertical sectional view of FIG. 3, the exploded perspective view of FIG. 4, and the horizontal sectional view of FIG. 5, the vibration damping device 7 is a support frame that is attached to and supported by the floor frame 6 or the step plate 4 of the landing 1. 8, a compression coil spring 9 as a spring and a damping damper 1
0 and 10 are attached, and a heavy vibration body 11 is elastically supported by the compression coil springs 9 and the damping dampers 10 and 10.

Each of the damping dampers 10 and 10 accommodates viscous silicone oil in a cylinder 12 having an upper opening provided in the support frame 8, and a piston 14 having a communication port 13 formed therein can be moved up and down. And the piston 14 and the vibrating body 11 are connected to each other.

As shown in the front view of FIG. 6 and the bottom view of FIG. 7, the permanent magnets 5 have comb teeth on the lowermost step plate 4a and the floor 3b on the lower floor opposite thereto. The stairs 2 are mounted side by side, and the stairs 2 can be levitated by the repulsive force.

With the above-mentioned structure, the lower end side of the stairs 2 is made to act on the lower end side of the stairs 2 by the repulsive force utilizing the magnetic force of the permanent magnets 5 regardless of the change in the weight of a person walking on the stairs 2. The vibration of the vibrating body 11 due to the compression coil springs 9 and the damping dampers 10, 10 can be effectively cancelled.

<Second Embodiment> FIG. 8 is an overall side view of a second embodiment of the magnetic levitation structure according to the present invention, and FIG. 9 is a plan view thereof, showing a recess 15a formed in the floor 15, A device mounting table 16 on which a semiconductor manufacturing device or the like is mounted is provided so as to be able to move up and down, and the device mounting table 16 and the recessed portion 15 are regulated so as to restrict displacement in a horizontal direction and a vertical direction above a predetermined level.
a is connected via a wire 17. Permanent magnets may be used instead of the wires 17 for horizontal displacement regulation.

A heavy vibrating body 20 is elastically supported on the bottom frame 16a of the apparatus mounting base 16 via compression coil springs 18 as springs and a damping damper 19. The structure of the damping damper 19 is the same as that of the first embodiment, and the description thereof is omitted by giving the same reference numerals.

Permanent magnets 21 are attached to the lower surface of the apparatus mounting table 16 and the bottom surface of the recess 15a facing it, and the apparatus mounting table 16 can be floated by its repulsive force. With these configurations, the vibration of the device mounting table 16 can be satisfactorily canceled regardless of the weight change of the device mounted on the device mounting table 16.

Next, the experimental results which are the basis of the present invention will be described. The test body used in the experiment was constructed as follows. That is, as shown in each of the side view of FIG. 10, the partially omitted plan view of the upper part of FIG. 11, and the front view of the main part of FIG. 12, the first support frame 22 as the first structure is shown. A second support frame 23 as a second structure is provided via a bearing B so as to be swingable around a horizontal axis P1.

First and second support frames 22, 23
The permanent magnets 24 ... Are interposed in a comb shape at one end side in the longitudinal direction of the.

One end of a leaf spring 26 is attached to a support bracket 25 provided upright on the second support frame 23, and a vibrating body 27 is attached to the other end of the leaf spring 26. Frame 23 and vibrating body 27
A damping damper 28 is interposed between the and. The damping damper 28 is configured by immersing the resistance plate 30 integrally attached to the vibrating body 27 in the silicone oil contained in the container 29 provided in the second support frame 23.

Using the above test body, first, in a state in which the support bracket 25, the leaf spring 26, the vibrating body 27, and the damping damper 28 were removed, as a static experiment, in an unloaded initial load state (11.8 kg). The upper and lower permanent magnets 24 were set to be in a horizontal state (flying height: 70 mm), and a load or a pulling force was applied within a range of ± 40 mm to measure the flying height.

A load-flying height curve was obtained with the loading load (kg) on the vertical axis and the flying height (mm) on the horizontal axis.
The results shown in the graph are obtained, and as an example of free vibration experiment, after a small forced displacement of about 4% (2 mm) of the flying height is applied to the floating part of the test body under a load of 27.3 kg. When released, the free vibration waveform was obtained, and the result shown in the waveform chart of FIG. 14 was obtained.

And each load (11.8kg, 27.3kg, 4
2.8kg) flying height (mm), spring constant (tangential slope: k
g / cm), natural frequency (Hz), and damping constant (%) were obtained, and the following results were obtained. Loading load Levitation amount Spring constant Natural frequency (Hz) Damping constant (kg) (mm) (tangential slope: kg / cm) Experimental value Calculated value (%) 11.8 70 3.9 2.90 2.86 0.5 27.3 48 10.5 3.13 3.09 0.3 42.8 38-3.25-0.2 The tangential gradient is the load that is obtained by dividing the constant α calculated from the balance under the initial load condition by the square of the flying height d, as shown in the following equation. It is a calculated value assuming that there is. W = α / d ² where W: load, d: flying height, α = 11.8 × 7 ² =
578.2

From these results, it is clear that the load-levitation curve is non-linear, that the smaller the flying height is, the larger the spring constant is, and the damping constant is as small as 0.5% or less. it is obvious. Also, for example, the first
A metal spring such as a compression coil spring or a leaf spring or an air spring is interposed between the supporting frame 22 of
If the support frame 23 of No. 2 is elastically supported,
When the load on the support frame 23 of the
Along with that, the natural frequency changes significantly by about 30%, so the supporting position of the leaf spring that supports the additional vibration body is changed, or the vibration frequency is changed. However, as a result of the above experimental example, if the magnetic force of the permanent magnet 24 is used to levitate the second support frame 23 with respect to the first support frame 22, for example, the load is doubled. Even if it increases or decreases, the natural frequency changes by only about 6%, and it is clear that the adjustment structure and the adjustment work for synchronizing the natural frequency of the added vibration body with respect to the change in the load can be eliminated. Is.

Next, an experiment and a linear simulation at the time of seismic wave excitation were carried out in a state where the support bracket 25, the leaf spring 26, the vibrating body 27 and the damping damper 28 described above are attached and before the attachment. Will be described.

FIG. 15 shows the input acceleration waveform [(a) of FIG. 15] when the vibrating body 27 is not added, and
The response acceleration waveforms [(b) of FIG. 15] are shown respectively, and the input acceleration waveform [(a) of FIG. 16] and the response acceleration waveform [FIG. (B)] of each.

Then, when the seismic wave was excited under the condition that the load was 27.3 kg and the flying height was 48 mm, when the vibrator 27 was not added, the maximum input acceleration was 68.6 cm / sec ² ,
The maximum response acceleration is 294 cm / sec ² , and the ratio of the maximum input acceleration to the maximum response acceleration is about 4.29 times. On the other hand, when the vibrator 27 is added, the maximum input acceleration is 83.8 cm / se.
The maximum response acceleration was 152 cm / sec ² with respect to c ² , and the ratio of the maximum input acceleration to the maximum response acceleration was about 1.81 times.

From the above results, when only a permanent magnet is provided to levitate magnetically, the damping performance is low and the nonlinear vibration causes unstable vibration characteristics. However, a vibration damping structure using a vibrating body must be added. By this, it is possible to improve the damping performance, reduce the response value, and obtain stable vibration properties. While magnetically levitating the structures such as the stairs 2 and the device mounting table 16 described above, it is possible to change the loading load there. Nevertheless, it is clear that vibration can be effectively suppressed.

Although the compression coil springs 9 and 18 and the leaf spring are used as springs in the above-described embodiments and test bodies, an air spring or the like may be used in the present invention.

[0029]

As described above, according to the magnetic levitation structure of the present invention, the vibration damping performance, which is small with only the magnetic force of the permanent magnet, is compensated for by the vibration of the vibrating body by the spring and the damping damper. In such a case, it is possible to reduce the vibration damping performance for the second structure at a low cost and to improve the vibration satisfactorily, and to suppress the vibration satisfactorily even during an emergency such as a power failure, without the need for constant energization. It was

In addition, for example, when the second structure is elastically supported by interposing a metal spring such as a compression coil spring or a leaf spring or an air spring with respect to the first structure, the second structure is used. When the load on the structure changes,
Along with that, the natural frequency changes greatly (for example,
If the load is increased or decreased by about 2 times, it will change about 30%).
Changing the support position of the spring that supports the added vibration body,
Although it is necessary to replace the vibrating body with a different weight, according to the present invention, the magnetic force of the permanent magnet is used to levitate the second structure with respect to the first structure. Even if the load increases or decreases by a factor of 2, the natural frequency changes by only about 6%, and the change in natural frequency is small, so the natural frequency of the added vibration body is synchronized with the change in the load. Since the adjustment configuration and the adjustment work are unnecessary, it has an advantage that the configuration can be simplified and the handling can be facilitated.

[Brief description of drawings]

FIG. 1 is an overall side view of a first embodiment of a magnetic levitation structure according to the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a vertical cross-sectional view of a main part of the vibration damping device.

FIG. 4 is an exploded perspective view of a vibration damping device.

FIG. 5 is a transverse cross-sectional view of the main part of the vibration damping device.

FIG. 6 is a front view of a main part.

FIG. 7 is a bottom view of the main part.

FIG. 8 is an overall side view of a second embodiment of the magnetic levitation structure according to the present invention.

9 is a plan view of FIG. 8. FIG.

FIG. 10 is a side view of the test body.

FIG. 11 is a partially omitted plan view of the test body.

FIG. 12 is a front view of a main part of a test body.

FIG. 13 is a graph.

FIG. 14 is a waveform diagram.

FIG. 15 is a waveform diagram.

FIG. 16 is a waveform diagram.

[Explanation of symbols]

 2 ... Stairs as a second structure 3a ... Upper floor as a first structure 3b ... Lower floor as a first structure 5, 21, 24 ... Permanent magnet 9, 18 ... As a spring Compression coil springs 10, 19, 28 ... Damping dampers 11, 20, 27 ... Vibrating body

Front page continued (72) Inventor Kazuki Katayama 2-5-14 Minamisuna, Koto-ku, Tokyo Inside the Takenaka Corporation Technical Research Institute (72) Inventor Hirokazu Yoshioka 2-5-14 Minamisuna, Koto-ku, Tokyo Incorporated Takenaka Corp. Technical Research Institute (72) Inventor Tatsuo Okamoto 4-13 Hommachi, Chuo-ku, Osaka No. 1-13 Takenaka Corporation Osaka Main Store (72) Inventor Ji Ji ▲ 興 ▼ 4-1, Honmachi, Chuo-ku, Osaka City Takenaka Corporation Osaka Main Store (72) Inventor Teruo Segawa Takenaka Engineering Co., Ltd., Osaka Main Store, 4-13 Hommachi, Chuo-ku, Osaka

Claims (1)

[Claims] 1. A first structure is provided with a second structure so that the second structure can be displaced up and down, and the second structure is floated between the first structure and the second structure. A magnetic levitation structure characterized in that a vibrating body is attached to the second structure through a spring and a damping damper, with a permanent magnet for applying a force interposed.