JPH08170689A - Vibration resistant device - Google Patents

Abstract

PURPOSE: To generate a natural frequency in a horizontal direction in a specific frequency Hz or less without worsening stability, by providing a spherical member between load supporting load disk and a load, in an air spring. CONSTITUTION: An air spring 1 comprises a diaphragm 8 of sealing an upper part of a case 7 with an upper surface opened, piston 10 having a cylindrical extension part 9 fixed to a diaphragm upper surface central part to be suspended in the case, strut 11 suspended down perpendicularly from a load disk 5 of supporting a load 2 further made positioning by an O ring 13 in the center of a bottom part 9a of the cylindrical extension part 9 to be engaged pivotally movably with the cylindrical extension part 9 and a steel ball 12 provided in a lower end of the strut 11. In an upper surface of the load disk 5, a spherical member 3 is fixed so as to position its spherical surface center 4 on a downward extension line of a center shaft 6 of the load disk 5. Horizontal direction displacement of the load 2 is converted into rocking of the piston 10, and a low horizontal direction spring constant is synthesized in series, to obtain a horizontal direction natural frequency of 1Hz or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-vibration device for supporting precision instruments and the like by means of an air spring, and in particular, the natural frequency in the horizontal direction can be made extremely low (1 Hz or less) without impairing stability. The present invention relates to an air spring vibration isolation device.

[0002]

2. Description of the Related Art Conventionally, precision equipment such as a semiconductor exposure apparatus and an electron microscope has been supported by a vibration isolation device using a diaphragm type air spring in order to insulate microvibrations from the installation floor and keep them at a fixed position. Is commonly done. However, the diaphragm type air spring has a problem in that it is soft in the vertical direction and a good vibration isolation effect can be obtained, but on the other hand, it is relatively rigid in the horizontal direction, so that a sufficient vibration isolation effect cannot be obtained.

Therefore, various horizontal vibration isolation devices have been devised in order to solve this problem. For example, as shown in FIG. 10, a case 7 having an open upper surface, a diaphragm 8 that seals the upper part of the case, and a piston 10 that is fixed to the central portion of the upper surface of the diaphragm and has a cylindrical extension 9 that hangs inside the case, A load disc 5 that supports the load 2, and a load disc 5 that hangs vertically from the load disc 5 and is positioned by an O-ring 13 at the center of the bottom portion 9a of the tubular extension portion 9 so as to be pivotable with the tubular extension portion 9. A strut 11 to be engaged,
An air spring 1 including a steel ball 12 provided at the lower end of the column 11 is disclosed in Japanese Patent Publication No. 62-7409. In this device, the displacement of the load 2 in the horizontal direction is converted into the locking of the piston 10, but the torsional rigidity of the diaphragm 8 is low, and as a result, the natural frequency in the horizontal direction can be lowered. In that case, the longer the length of the tubular extension 9 is, the lower the natural frequency is obtained.

However, in the conventional horizontal vibration isolator, the supporting point of the load 2 is the steel ball 12 and the tubular extension portion 9.
It becomes a contact point 14 (pivot point) with the bottom surface 9a of the above, and supports the load 2 at a position considerably lower than the center of gravity of the load 2. Therefore, if the cylindrical extension portion 9 is lengthened to obtain a low natural frequency, the center of gravity becomes relatively high, which causes instability. Therefore, in reality, the length of the tubular extension portion 9 is limited, and it is impossible to set the natural frequency in the horizontal direction to 1 Hz or less.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned drawbacks, and provides an air spring vibration isolator capable of reducing the natural frequency in the horizontal direction to 1 Hz or less without impairing the stability. The purpose is to do.

[0006]

In order to achieve the above object, the description will be made with reference to the reference numerals in the drawings which are embodiments of the present invention.
The above object is achieved by providing the spherical member 3 between the load disk 5 supporting the load 2 and the load 2.

That is, the first means for solving the above problems (the invention according to claim 1) is a vibration isolation device for supporting a load 2 by means of an air spring 1, which is a case 7 having an open upper surface and a case upper portion. And a cylindrical extension 9 that is fixed to the center of the upper surface of the diaphragm and hangs down inside the case.
A piston 10 having a load, a load disc 5 supporting the load 2, and a support 11 vertically hung from the load disc 5, and the tubular extension 9 and the support 11 are provided.
And so that the air spring 1 pivotally engaged at a position lower than the diaphragm 8 and its spherical center 4 are located on the downward extension line of the central axis 6 of the load disc 5.
The spherical member 3 is fixed to the upper surface of the load disk.

Since the spherical member 3 comes into point contact with the bottom surface 2a of the load 2 and stress concentrates, it is preferable to use carbon steel with a surface hardening treatment.

A second means for solving the above problem (claim 2)
The invention according to claim 1) embodies the first means, wherein the tubular extension 9 and the column 11 are pivoted by a steel ball 12 and an O-ring 13 provided at the lower end of the column. It is movably engaged.

A third means for solving the above problems (claim 3)
The invention described in 1) is a simplification of the first means, in which the load disk 5 and the spherical member 3 are integrated.

A fourth means for solving the above problems (claim 4)
The invention described in 1) is a development of the first means, in which a plate member 16 having the same hardness as the spherical member 3 is fixed to the bottom surface 2a of the load 2. .

A fifth means for solving the above problems (claim 5)
The invention described in 1) is a further development of the first means, in which the spherical member 3 is provided on the bottom surface 2a of the load 2.
The member 17 having a concave spherical surface 17a having a radius larger than the radius of the sphere is fixed.

Sixth means for solving the above problems (claim 6)
The invention described in 1) is a further development of the first means, in which the positioning plate 18 is provided on the bottom surface 2a of the load 2.
Is fixed between the positioning plate 18 and the spherical member 3,
A holding member 19 made of an elastic material such as rubber is provided.

Seventh means for solving the above problems (claim 7)
The invention described in 1) partially differs in configuration from the first means. That is, a vibration isolation device that supports a load 2 with an air spring 1, a case 7 having an open upper surface, a diaphragm 8 that seals the upper part of the case, and a cylindrical shape that is fixed to the center of the upper surface of the diaphragm and that is suspended in the case. It is composed of a piston 10 having an extension 9, a load disc 5 supporting the load 2, and a support 11 vertically hung from the load disc 5, and the tubular extension 9 and the support 1 are provided.
1 is an air spring 1 pivotally engaged at a position lower than the diaphragm 8 (same as the first means), and its spherical center 4 is on an extension line above the central axis 6 of the load disc 5. And a spherical member 3 fixed to the bottom surface 2a of the load 2 so as to be located at.

Here, in the fifth means to the seventh means, it is preferable that the member or the portion which comes into contact with the spherical portion of the spherical member 3 has the same hardness as the spherical member 3.

[0016]

FIG. 1 is a diagram for explaining the principle of the first and second means. In FIG. 1, the spherical member 3 is
The spherical center 4 is fixed to the upper surface of the load disk 5 so that the spherical center 4 is located on the downward extension line of the central axis 6 of the load disk 5. When the load 2 is displaced in the horizontal direction XY,
The action of the prior art translates into locking of the piston 10 resulting in a low horizontal spring constant. In addition to that, a steel ball 12 provided at the lower end of a column 11 vertically hung from the load disc 5 and a bottom 9a of the tubular extension 9 are provided.
Using the contact point 14 (pivot point) as a fulcrum, a low horizontal spring constant due to the rolling of the load disk 5 and the load 2 can be obtained. Then, these spring constants are combined in series, and a very low horizontal spring constant (natural frequency of 1 Hz or less) is obtained.

At this time, the condition for stably supporting the load 2 is R> A in FIG. 1, while the condition for lowering the natural frequency in the horizontal direction is to make R close to A. is there. Therefore, the numerical values of R and A may be set to optimum values in terms of both stability and natural frequency.

In the prior art, the supporting point for the load 2 is
In contrast to the contact point 14 (pivot point) between the steel ball 12 and the bottom portion 9a of the tubular extension portion 9, in the present invention, the support point is the contact point 15 between the spherical member 3 and the load 2. Therefore, even though a very low horizontal spring constant (natural frequency of 1 Hz or less) is obtained, the center of gravity of the load 2 and the supporting point are
It will be considerably closer than the prior art and stability will be greatly improved.

In the fourth means, either the bottom surface 2a of the load 2 or the spherical member 3 is not deformed,
This allows for smooth rolling.

In the fifth means, the member 1 having the concave spherical surface 17a having a radius larger than the radius of the sphere of the spherical member 3.
Reference numeral 7 is a means for returning the relative positional deviation between the load 2 and the load disk 5 caused by the rolling of the spherical member 3 to the original position, and also for returning the load disk 5 to the original position. It is also a means. Therefore, the relative displacement between the load 2 and the load disk 5 is prevented, and the rocking motion of the piston 10 is stably performed for a long period of time.

By the way, in the air spring 1 of the prior art, the action of converting the horizontal displacement of the load 2 into the rocking of the piston 10 is stably performed, and the natural horizontal low natural frequency of the air spring 1 is maintained. In order to obtain it, it was necessary to perform a setting operation in which the central axis 6 of the load disk 5 was made to coincide with the central axis of the piston 10 having the tubular extension 9 before use. That is, the column 11 vertically hung from the load disk 5 and provided with the steel ball 12 at the lower end thereof is positioned by the O-ring 13 at the center of the bottom portion 9 a of the tubular extension portion 9 and This is because they are engaged so as to be pivotally movable, but they are not configured so that the above-mentioned respective central axes coincide with each other.

Therefore, in the sixth means, the positioning plate 18 of the load disk 5 is fixed to the bottom surface 2a of the load 2. On the other hand, the holding member 19 made of a rubber-like elastic body is a means for preventing relative displacement of the load 2 and the load disk 5 caused by rolling without hindering rolling of the spherical member 3, and , Is also an additional means for returning the load disk 5 to the original position. Therefore, between the positioning plate 18 of the load disc 5 and the spherical member 3,
By providing the holding member 19 made of an elastic material such as rubber, relative displacement between the load 2 and the load disk 5 can be prevented, setting work before using the air spring can be omitted, and a predetermined low natural vibration can be omitted. The number can be stably maintained over a long period of time.

The seventh means operates in the same manner as the first means.

[0024]

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

<First Embodiment> The configuration of this embodiment is shown in FIG.
Is shown in. In FIG. 2, 1 is an air spring, 2
Is a load of precision equipment and the like, and 3 is a spherical member.

2, the air spring 1 also has a case 7 whose upper surface is open, a diaphragm 8 which seals the upper part of the case, and a cylindrical extension 9 which is fixed to the center of the upper surface of the diaphragm and hangs down inside the case. The piston 10, the load disc 5 supporting the load 2, and the load disc 5 hanging vertically from the load disc 5 and positioned at the center of the bottom portion 9a of the tubular extension portion 9 by an O-ring 13 to form the tubular extension portion 9. It consists of a pillar 11 that is pivotally engaged and a steel ball 12 provided at the lower end of the pillar 11. The spherical member 3 is fixed to the upper surface of the load disk 5 such that the spherical center 4 thereof is located on the downward extension line of the central axis 6 of the load disk 5.

FIGS. 3 and 4 show the horizontal vibration transmissibility (dB) of each of the conventional vibration isolator shown in FIG. 10 and the vibration isolator of the first embodiment of the present invention shown in FIG. The data obtained by actual measurement are shown. In the measurement, the transfer function of the horizontal vibration acceleration between the floor under the slight vibration and the upper surface of the load 2 such as precision equipment was obtained by the FFT analyzer. The result of the conventional vibration isolator is shown in FIG. 3, and the result of the vibration isolator of the first embodiment of the present invention is shown in FIG. According to the figure, the natural frequency is 1.3 Hz in the conventional example, but is 0.5 Hz in the first example of the present invention. This supports the effect of rolling operation of the spherical member 3 provided between the load disc 5 supporting the load 2 and the load 2.

<Second Embodiment> The configuration of this embodiment is shown in FIG.
Is shown in. The difference from the first embodiment is that the load disk 5 and the spherical member 3 are integrated.

<Third Embodiment> FIG. 6 shows the configuration of this embodiment.
Is shown in. The difference from the first embodiment is that the plate-shaped member 1 having the same hardness as the spherical member 3 on the bottom surface 2a of the load 2.
This is the point where 6 is fixed.

<Fourth Embodiment> The configuration of this embodiment is shown in FIG.
Is shown in. The difference from the first embodiment is that a member 17 having a concave spherical surface 17a having a radius larger than the radius of the sphere of the spherical member 3 is fixed to the bottom surface 2a of the load 2 so that the concave spherical surface 17a and the spherical member 3 are in contact with each other. That is the point.

<Fifth Embodiment> The configuration of this embodiment is shown in FIG.
Is shown in. The difference from the first embodiment is that the positioning plate 18 of the load disk 5 is fixed to the bottom surface 2a of the load 2, and a holding member made of an elastic material such as rubber is provided between the positioning plate 18 and the spherical member 3. 19 is provided.

<Sixth Embodiment> The configuration of this embodiment is shown in FIG.
Is shown in. The difference from the first embodiment is that the spherical member 3
The spherical member 3 is fixed to the bottom surface 2a of the load 2 so that the spherical center 4 of the load disk 5 is located on the extension line above the central axis 6 of the load disk 5.

In the first to sixth embodiments, the tubular extension 9 and the support 11 are the steel balls 1 provided at the lower end of the support.
2 and the O-ring 13 are pivotally engaged with each other, but are not limited thereto. That is, it suffices if it is pivotally engaged at a position lower than the diaphragm 8,
A structure using anti-vibration rubber or the like is also possible.

In the first to sixth embodiments, one air spring 1 is used for description, but normally, three or more air springs 1 are used to support the load 2. .

[0035]

As described above, according to the first means or the seventh means, the horizontal displacement of the load is converted into the locking of the piston, and a low horizontal spring constant is obtained. With the pivot point provided on the cylindrical extension below the piston as a fulcrum, a low horizontal spring constant can be obtained by rolling the load disk and the load. By combining these spring constants in series, a horizontal natural frequency of 1 Hz or less is obtained.

Moreover, the center of gravity of the load and the supporting point come close to each other, and the stability can be greatly improved.

According to the second means, with a simple structure,
Moreover, there is an advantage that the pivot mechanism can be configured without requiring much space.

According to the third means, the number of parts can be reduced and the structure can be simplified.

According to the fourth means, smooth rolling is possible, and the performance of the vibration isolation device can be stably maintained for a long period of time.

According to the fifth means, the relative displacement between the load and the load disk can be prevented, and the performance of the vibration isolator can be maintained stably for a long period of time.

According to the sixth means, by providing the positioning plate of the load disc and the holding member made of a rubber-like elastic body, the setting work before using the air spring can be omitted, and moreover, the load and the load disc can be eliminated. Relative displacement can be prevented, and the performance of the vibration isolator can be stably maintained for a long period of time.

According to the seventh means, even if the precision equipment equipped with the air spring vibration isolator is already installed, the spherical member is formed on the bottom surface of the precision equipment (load) without modifying the air spring vibration isolator. By attaching the, the performance of the vibration isolation device can be easily improved.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining the principle of the present invention.

FIG. 2 is a sectional view showing a first embodiment of the present invention.

FIG. 3 is a graph showing a horizontal vibration transfer characteristic of a conventional vibration isolator.

FIG. 4 is a graph showing horizontal vibration transfer characteristics of the first embodiment of the present invention.

FIG. 5 is a sectional view showing a second embodiment of the present invention.

FIG. 6 is a sectional view showing a third embodiment of the present invention.

FIG. 7 is a sectional view showing a fourth embodiment of the present invention.

FIG. 8 is a sectional view showing a fifth embodiment of the present invention.

FIG. 9 is a sectional view showing a sixth embodiment of the present invention.

FIG. 10 is a cross-sectional view showing a conventional vibration isolator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Air spring 2 Load 2a Bottom surface 3 Spherical member 4 Spherical center 5 Load disk 6 Center axis 7 Case 8 Diaphragm 9 Cylindrical extension 9a Bottom 10 Piston 11 Strut 12 Steel ball 13 O-ring 16 Plate member 17 Member having concave spherical surface 17a concave spherical surface 18 positioning plate 19 holding member

Claims (7)

[Claims] 1. A vibration isolator supporting a load with an air spring, a case having an open upper surface, a diaphragm for sealing an upper part of the case, and a cylindrical extension fixed to a central portion of the upper surface of the diaphragm and suspended in the case. A piston having a portion, a load disc for supporting the load, and a column vertically hung from the load disc, and the tubular extension and the column are pivotally engaged at a position lower than the diaphragm. An anti-vibration device comprising: an air spring to be fitted; and a spherical member fixed to the upper surface of the load disk such that the center of the spherical surface is located on an extension line below the central axis of the load disk. 2. The vibration isolation device according to claim 1, wherein the cylindrical extension and the support are pivotally engaged by a steel ball and a rubber elastic body provided at a lower end of the support. 3. The vibration isolator according to claim 1, wherein the load disk and the spherical member are integrated. 4. The vibration isolator according to claim 1, wherein a plate-shaped member having a hardness equivalent to that of the spherical member is fixed to the bottom surface of the load. 5. The vibration isolator according to claim 1, wherein a member having a concave spherical surface having a radius larger than the radius of the sphere of the spherical member is fixed to the bottom surface of the load. 6. A positioning plate is fixed to the bottom surface of the load,
The vibration isolator according to claim 1, wherein a holding member made of a rubber-like elastic body is provided between the positioning plate and the spherical member. 7. A vibration isolator supporting a load with an air spring, a case having an open upper surface, a diaphragm for sealing the upper part of the case, and a cylindrical extension suspended in the central part of the upper surface of the diaphragm and suspended in the case. A piston having a portion, a load disc for supporting the load, and a column vertically hung from the load disc. The tubular extension and the column are pivotally engaged at a position lower than the diaphragm. And a spherical member fixed to the bottom surface of the load so that the spherical center of the air spring is located on an extension line above the central axis of the load disk.