JP2002372096A - Pneumatic spring type vibration isolator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve vibration isolating performance by providing spring characteristics as soft as possible while retaining vertical and horizontal positioning accuracy in an isolator 2 having a vertical pneumatic spring S1 vertically supporting a mount board 3 (support counter-body) and a horizontal pneumatic spring S2 horizontally supporting it. SOLUTION: The vertical and horizontal pneumatic springs S1 and S2 in the isolator 2 are provided with either of a gimbal piston or a dome gimbal piston. This device may perform an active isolating control changing and controlling pneumatic pressures of the pneumatic springs S1 and S2 according to vibration states of a top plate 21 and positively applying controlled vibration counterbalancing the vibration relative to the top plate 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for supporting a load such as a semiconductor manufacturing apparatus or a precision measuring apparatus via a gas spring in order to install the apparatus in a state substantially insulated from floor vibration. To a vibration isolator.

[0002]

2. Description of the Related Art Conventionally, as a vibration isolator of this type, for example, as disclosed in Japanese Patent Application Laid-Open No. H11-132286, a load of a precision instrument or the like is placed at the center of a substantially rectangular casing in plan view. Is provided, and a bellows type air spring (hereinafter simply referred to as bellows) is provided around the diaphragm type air spring to receive a horizontal load. In this device, the diaphragm of the center air spring is formed by a thin elastic film with extremely low rigidity called a rolling actuation film in order to improve the horizontal vibration isolation performance, and the horizontal load is supported by a separately provided bellows. I am trying to do it.

In general, in a gas spring type vibration isolator, the actual vibration state of a supported member is detected by a sensor, and the vibration of the gas spring is changed by changing the gas pressure of the gas spring in accordance with the detected value. There is a device having a so-called active vibration damping function of adding a control vibration having an opposite phase that cancels out (see, for example, JP-A-3-219141). As the horizontal actuator for applying a horizontal control vibration to the supported member, a bellows as in the former conventional example is often used.

[0004]

However, when a bellows is used as a horizontal spring or actuator as in the above-mentioned prior arts, there is a possibility that the vertical vibration isolation performance of the vibration isolation device is impaired. . That is, in general, the bellows has a very soft spring characteristic in the axial direction, but the spring characteristic in the direction perpendicular to the axis (hereinafter also referred to as the axis orthogonal direction) mainly depends on the material and shape of the rubber film. It depends greatly. For this reason, in the vibration isolator in which the bellows are arranged in the horizontal direction, if the vertical spring characteristics are to be sufficiently softened, the rubber film of the bellows must be made to have low rigidity.

[0005] However, if the rigidity of the rubber film of bellows is reduced in such a manner, the restoring force in the direction perpendicular to the axis is reduced, so that the problem of positional displacement due to hysteresis increases. On the other hand, if the rigidity of the rubber film of the bellows is increased in order to secure the positioning accuracy, it is inevitable that the spring characteristics in the direction perpendicular to the axis become harder, and accordingly, the springs in the vertical direction as a whole also correspond to the vibration isolator as a whole. The characteristics become hard, which leads to a decrease in vibration isolation performance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a gas spring type vibration damping device having vertical and horizontal gas springs, in which the structure of the gas springs is reduced. The purpose of the present invention is to improve the vibration isolation performance of the gas spring while keeping the positioning accuracy in the vertical and horizontal directions while making the device more flexible.

[0007]

In order to achieve the above object, according to a solution of the present invention, a gimbal mechanism is incorporated into a piston of a diaphragm-type gas spring (hereinafter, also referred to as a gimbal piston), so that the gas spring is provided. Focusing on the fact that the spring characteristics can be made very soft not only in the axial direction but also in the direction perpendicular to the axis, the gas springs in the vertical and horizontal directions in the vibration isolator are both constituted by gimbal pistons.

Specifically, according to the first aspect of the present invention, a vertical gas spring for supporting a supported member in a vertical direction with respect to a fixed base and a horizontal gas spring for supporting the supported member in a horizontal direction are provided. A gas spring type vibration damping device provided with a spring is assumed. And, as the gas spring, a recess provided so as to open outward on the fixed base, a piston disposed near the opening of the recess, and a gap between the piston and the opening periphery of the recess. And a diaphragm that closes and partitions a gas chamber, and further comprising:
A load receiving member disposed on one side relatively distant from the concave portion in the direction of the central axis, and swinging around an arbitrary orthogonal axis which is separated from the load receiving member on the other side in the axial direction and is orthogonal to the central axis; A cylindrical piston body member movably elastically held by the diaphragm, and then, from the load receiving member toward the other axial direction so as to pass through the center hole of the piston body member. The piston body member is provided with a bottomed cylindrical extension extending toward the other side in the axial direction so as to surround the support pillar, and the support portion is provided at the bottom of the extension. The tip of the column is pivoted.

With the above configuration, in the gas spring type vibration damping device according to the present invention, first, the supported member is supported by the vertical gas spring, and the original characteristic of the gas spring is the axial direction, that is, In this case, since the natural frequency in the vertical direction (resonance frequency unique to the system) is extremely low, an excellent vibration isolation effect over a wide frequency range with respect to the vertical vibration can be obtained with this gas spring.

In the above vertical gas spring,
With respect to vibration in the direction perpendicular to the axis, that is, horizontal vibration, the piston body member swings around any axis in the horizontal plane,
The load receiving member pivotally supported at the bottom of the extending portion of the piston main body via the support column is displaced in the horizontal direction, whereby the vibration is absorbed. At this time, since the supporting point of the support column by the piston body member is at a position lower than the holding position of the piston body member by the diaphragm, the spring characteristic of the diaphragm with respect to the horizontal displacement of the load receiving member is very soft. Thus, the natural frequency in the horizontal direction can be sufficiently reduced.

Further, a vertical load (axial load of the gas spring) acting on the piston body member that swings through the support column to suppress the swing of the piston body member, It becomes a restorative force that tries to return to the neutral position,
Thereby, the positioning accuracy of the load receiving member is sufficiently obtained.

In the above structure, the horizontal gas spring supporting the supported member in the horizontal direction has the same structure as the above-described vertical gas spring, so that only the axial direction of the horizontal gas spring is used. In addition, the spring characteristics can be made extremely soft in the vertical direction, which is one of the directions perpendicular to the axis, and sufficient positioning accuracy can be obtained.

In other words, according to the vibration damping device of the present invention, by using a gas spring having a gimbal piston as the vertical and horizontal gas springs, it is possible to eliminate the disadvantages such as bellows and eliminate the problem of bellows. It is possible to achieve both excellent vibration isolation performance and high positioning accuracy in both the vertical and horizontal directions.

According to the second aspect of the present invention, the lower surface of the load receiving member of the piston is supported in contact with the upper end surface of the support column, and the upper end surface of the support column is formed by a spherical surface. It shall be configured.

Thus, in the vertical gas spring, not only the swing movement of the piston main body member but also the relative rotation of the load receiving member and the support column with respect to the horizontal vibration can be achieved. Since the load receiving member is displaced in the horizontal direction, thereby absorbing vibration,
The horizontal spring characteristics of the vibration damping device are further softened. Further, the horizontal restoring force of the vertical gas spring is reduced, but the restoring force can be obtained by the horizontal gas spring, so that the positioning accuracy of the entire vibration isolator is sufficient. Become.

According to a third aspect of the present invention, the horizontal gas springs according to the second aspect of the present invention are arranged so as to face each other so that the central axes thereof substantially coincide with each other at both horizontal portions sandwiching the fixed base. As a result, the load receiving member is supported at a plurality of locations separated in the horizontal direction by the pair of gas springs, whereby the load on the supported member can be stably supported.

According to a fourth aspect of the present invention, in the third aspect of the present invention, a communication passage is provided for communicating the gas chambers of a pair of gas springs arranged in a horizontal direction.

Since the gas chambers of the pair of gas springs facing each other in the horizontal direction are communicated with each other by the communication passage, each of the pair of gas springs has an extremely small spring constant in the axial direction. As a result, the spring constant of the entire anti-vibration device in the axial direction can be minimized, so that the anti-vibration performance can be improved as much as possible.
Even in such a case, since the restoring force in the direction perpendicular to the axis is not lost in the horizontal gas spring, it is possible to prevent the displacement.

According to a fifth aspect of the present invention, in any one of the first to third aspects of the present invention, detecting means for detecting the vertical or horizontal acceleration of the load receiving member, and the gas pressure of the vertical or horizontal gas spring. Adjusting means for adjusting, and control means for changing and adjusting the gas pressure of the gas spring by the adjusting means so as to suppress vertical or horizontal vibration of the load receiving member based on a detection result by the detecting means. Is provided.

In this configuration, the vibration of the supported member can be actively suppressed by changing and adjusting the gas pressure of the vertical or horizontal gas spring by operating the adjusting means (active vibration suppression control). ). On the other hand, in this case, since a gas spring in the horizontal direction as well as the vertical direction is an essential component, if a bellows or the like is used as the gas spring in the horizontal direction, the spring characteristic of the bellows in the direction orthogonal to the axis is hard. Where the decline in vibration isolation performance cannot be avoided,
The gas spring provided with the gimbal piston in the horizontal direction as in the inventions of claims 1 to 3 of the present application is particularly effective in that the spring characteristic in the direction perpendicular to the axis can be made very soft. It will be.

[0021]

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

(Embodiment 1) FIG. 1 shows an example of a precision anti-vibration table A using a gas spring type anti-vibration apparatus according to the present invention.
The precision anti-vibration table A has, for example, mounted thereon precision equipment such as a semiconductor inspection device, an electron microscope, and an optical measurement device (not shown), and is used to install those devices in a state substantially insulated from vibration from the floor. Things. That is, the precision anti-vibration table A
As shown in the figure, a schematic structure of a lower structure 1 installed on a floor surface and air spring type isolators 2, 2,... Disposed at four corners of the upper surface of the lower structure 1 are respectively shown. And a mounting board 3 mounted on the upper part of the four isolators 2, 2,....

The lower structural portion 1 is formed by assembling a structural member of a steel square pipe into a substantially rectangular parallelepiped shape, and has four legs 4, 4,.
, The lower beams 5, 5, ... extending in the horizontal direction so as to connect the two adjacent legs 4, 4 at the lower end, and the upper ends of the four legs 4, 4, ... Are arranged so as to form a substantially rectangular frame shape in plan view around the outer periphery, the inner side surfaces are respectively joined to the outer side surfaces of the legs 4, 4,. The upper beam part is located on the same plane as the upper end face. And each leg 4
Are arranged from the upper end surface of the upper beam to the upper surfaces of the upper beams 6, 6 surrounding the outside, and the isolator 2 is arranged on each of the horizontal plates 7. . Further, two lower beam portions 5 extending in the longitudinal direction of the lower structural portion 1 are provided.
, Two moving casters 8, 8,... Are arranged on the lower surface of each leg 5, and levelers 9, 9,. ing.

(Structure of Isolator) As shown in FIGS. 2 and 3, the isolator 2 is a substantially rectangular parallelepiped inner casing 10 (fixed base) fixed to the lower structure 1 of the precision anti-vibration table A. And an outer casing 20 formed in a box shape with a lower opening, and arranged to cover the inner casing 10 from above. The outer casing 20 is provided on the upper portion and on both left and right sides of the inner casing 10 respectively. It is supported by the provided diaphragm type air springs S1, S2, S2. Hereinafter, in this specification, the illustrated X direction is referred to as a left-right direction, the Y direction is referred to as a front-rear direction, and the Z direction is referred to as a vertical direction.

The inner casing 10 has front and rear left and right steel side wall members 10a, 10a, 10b, and 10b each having a lower end joined to an upper surface of a steel bottom plate member 10c and an adjacent side wall member 10a. , 10b are joined together to form an integral part. Each of the left and right side wall members 10b, 10b is a block-like member having a large thickness, and has a concave section 11, 1 having a circular cross section so as to open outward in an intermediate portion in the vertical direction.
1 (shown only in FIG. 3), and a semicircular extending portion extending to face each other is formed at the upper edge portion. 4, a circular opening 12 is formed.

The opening 12 is provided in the inner casing 10.
A donut-shaped piston main body 13 constituting a piston of the air spring S1 is inserted therein. The piston body 13 is made of an aluminum alloy, and a center hole 13a having a circular cross section penetrates in the up-down direction along the axis Z. On the other hand, the lower half of the outer periphery has a tapered surface slightly reduced in diameter toward the lower end. 13b is formed. And, it extends from the lower end surface 13c of the piston body 13 to the outer peripheral side while covering the outer peripheral side tapered surface 13b,
An annular diaphragm 14 is provided so as to close the periphery of the opening 12 from there. That is, the upper end opening 12 of the inner casing 10 is closed by the diaphragm 14 and the piston main body 13, and an air chamber 15 is defined therein.
The lower end surface 13c faces the air chamber 15 and receives air pressure, thereby forming a vertical air spring S1 that supports a vertical load.

The diaphragm 14 is composed of a rubber elastic film embedded with a woven fabric of polyester fibers as a reinforcing material.
As shown by the imaginary line in FIG. 4, once formed in a hat shape with a round hole at the center, the peripheral wall portion of the hat is curved midway and turned downward, and is shown by a solid line in the same figure. It has a deep dish shape. That is, the diaphragm 14 is formed with an annular roll portion 14b that is curved upward and protrudes continuously from the inner circumferential edge of the outer circumferential flange portion 14a corresponding to the hat flange portion, and the inner circumferential edge of the roll portion 14b. An edge portion extends below the outer peripheral flange portion 14a, and an inner peripheral flange portion 14c is formed so as to further surround the round hole toward the inner peripheral side.

As shown in the figure, the inner peripheral flange portion 14c of the diaphragm 14 is adhered to the lower end surface 13c of the piston body 13, and the washer 16
Thus, it is firmly pressed against the piston body 13. On the other hand, the outer peripheral flange portion 14a of the diaphragm 14
Are adhered to the upper surface of the inner casing 10, and the lower surface of the tightening ring 17 and the inner casing 1 are fastened to the upper surface of the inner casing 10 by bolts (not shown).
0.

Thus, the diaphragm 14 arranged in such a manner is largely flexed substantially uniformly so that the annular roll portion 14b undulates between the piston body 13 and the tightening ring 17 over the entire circumference. The piston body 13
Has great flexibility with respect to vertical displacement of. Further, the diaphragm 14 flexes in opposite directions at the right and left roll portions 14b sandwiching the piston main body 13, so that the piston main body 13 can easily swing around an arbitrary horizontal axis (see FIG. 1). (See FIG. 7). on the other hand,
The diaphragm 14 has extremely low flexibility with respect to the horizontal displacement of the piston main body 13, so that the piston 13 hardly displaces in the horizontal direction.

A cylindrical piston well 18 (extending portion) is attached to the lower end surface 13c of the piston body 13 so as to extend substantially vertically downward from the inner peripheral side. This piston well 18 is used for the piston body 1.
3 is made of the same aluminum alloy, and its upper end is slightly reduced in diameter to form a reduced diameter portion 18a that is screwed into the center hole 13a of the piston body 13. A male screw threaded on the outer periphery of the reduced diameter portion 18a is screwed with a female screw threaded on the inner periphery of the center hole 13b, thereby forming the piston well 18A.
Is firmly fastened to the piston body 13 together with the washer 16. The piston well 1
8 is the center hole 1 of the piston body 13
3a, the hollow portion 18b of the piston well 18
Communicates with the center hole 13a while the hollow portion 18b
The lower end is closed by a disc-shaped steel cap 19, and the upper surface of the cap 19 has a well slag subjected to heat treatment for increasing the surface hardness in order to support the lower end of the support rod 24 as described later. 19a are formed.

On the other hand, above the piston body 13,
The top plate 21 (load receiving member) that is in contact with the mounting board 3 is disposed apart from the piston body 13. The top plate 21 is formed in a substantially rectangular plate shape and forms a ceiling portion of the outer casing 20 of the isolator 2, and has an outer peripheral edge on each of upper edges of four side plates 22, 22. Are connected, and the lower end edge of each side plate 22 extends to near the upper surface of the bottom plate member 10c of the inner casing 10.

An upper end of a vertically extending support rod 24 (support column) is fastened to a substantially central portion of the lower surface of the top plate 21. The support rod 24 is connected to the center hole 13a of the piston body 13 and the piston well. 18
Extending substantially vertically downward through the hollow portion 18b of the well, and the steel ball 25 disposed at the lower end thereof is connected to the well slug 19.
a is rollingly contacted with a. Further, a rubber elastic ring 26 in which a core body 26a is embedded is externally inserted at the lower end side of the support rod 24, so that the lower end of the support rod 24 is always positioned on the axis Z. That is, the top plate 21 is pivotally supported by the bottom of the piston well 19 via the support rod 24, and is rotatable around an arbitrary axis in the horizontal direction with respect to the piston body 13.

Then, as shown in FIG.
In a state where an appropriate air pressure is supplied, the lower surface of the top plate 21 is separated from the upper surface of the tightening ring 17 therebelow and vertically opposed, while, for example, the air in the air chamber 15 escapes, When the air pressure is significantly reduced, the lower surface of the top plate 21
And is supported by the inner casing 10 via the tightening ring 17.

As described above, the isolator 2 of this embodiment is supported by the vertical air spring S1 so that the top plate 21 and the piston main body 13 are vertically displaced as a unitary body. 21 is pivotally supported by the support rod 24 with respect to the piston body 13, and the piston body 13 is swingably supported by the diaphragm 14. The top plate 21, the support rod 24 and the piston body 13
This constitutes a so-called gimbal piston.
First, as a characteristic of the air spring, with respect to the vibration in the vertical direction, which is the axial direction, the air spring has a vibration transmission characteristic as shown in an example in FIG.
In addition to appearing in a frequency range as low as z, excellent vibration isolation performance can be obtained over a wide frequency range.

As shown in FIG. 7, when the outer casing 20 and the support rod 24 are displaced in the horizontal direction, the piston body 13 is held by the diaphragm 14 and the horizontal About the axis, thereby absorbing the vibration. At this time, the diaphragm 14 of the piston body 13
Since the lower end of the support rod 24 is pivotally supported by the well slug 19a at a lower position than the holding position of the support rod 24, the spring characteristic of the diaphragm 14 is very soft. As shown in the figure, the vibration isolation performance in the horizontal direction by the isolator 2 is excellent as in the vertical direction.

Further, a vertical load (axial load) acting on the oscillating piston body 13 via the support rod 24 as shown in FIG. 7 suppresses the oscillating movement of the piston body 13. And neutral state (state shown in FIG. 2)
It is a resilience to return to. Then, when the piston body 13 is returned to the neutral state by the restoring force and the support rod 24 is extended in the vertical direction, the top plate 21 also returns to the predetermined origin position before being displaced in the horizontal direction. . That is, this isolator 2
The gimbal piston of the air spring S1 in the up-down direction has a mechanical self-centering action different from that of the spring force of the elastic member or the like, so that required positioning accuracy can be obtained.

Further, in the isolator 2 of this embodiment, the left and right side walls 1 of the inner casing 10 serve as actuators for active vibration suppression control described later.
0b and a side air spring S2 between the opposing side plates 22, 22 of the outer casing 20, respectively.
S2 is provided. A feature of the present invention resides in that the pair of left and right air springs S2 and S2 each include a gimbal piston similarly to the vertical air spring S1.

That is, as shown, the left and right side wall members 10b, 10b of the inner casing 10 have:
Each piston body has a center hole 28a similar to the vertical air spring S1 so as to be inserted in the concave portion 11 opened on the outer surface thereof and to be separated in the left-right direction from the side plate 22 (load receiving member). 28 are arranged. An annular diaphragm 29 is disposed between each of the piston bodies 28 and the peripheral edge of the opening of the concave portion 11.
1, an air chamber 30 is defined, and a pressure-receiving surface 28b (a surface on the other side in the axial direction) of the piston body 28 facing the air chamber 30 receives air pressure, thereby supporting a load in the left-right direction. Is configured.

The inner peripheral flange of the diaphragm 29 is fixed to the pressure receiving surface 28b of the piston body 28 by a washer 31, while the outer peripheral flange of the diaphragm 29 is connected to the side wall member 11a of the inner casing 10, the fastening ring 32, And the piston 28
The diaphragm 3 is located between the outer periphery of the
Two annular rolls are located. Then, the annular roll portion is flexibly deformed so as to undulate, so that the piston main body 28 is largely displaced in the left-right direction which is the axial direction,
In addition, it swings around an arbitrary axis orthogonal to the axial direction. Further, a cylindrical piston well 33 (extending portion) is attached to the piston main body 28 so as to extend in the left-right direction, and the hollow portion 33a communicates with the center hole 28a of the piston main body 28, A steel cap 34 is disposed on the tip side of the piston well 33 so as to close the hollow portion 33a.
A well slag is formed on the inner surface of 4, that is, on the bottom surface of the piston well 33.

Further, a support rod 35 (support column) is provided which penetrates through the hollow portion 33a of the piston well 33 and extends coaxially with the piston well 33 in the left-right direction.
The base end of the support rod 35 is the outer casing 2
A steel ball 36 is disposed at the end of the support rod 35 so as to be rotatably abutted on the well slag, and a rubber elastic ring 37 is externally inserted. I have.

As described above, in short, the horizontal air spring S2
, The side plate 2 of the outer casing 20
2 is pivotally supported at the bottom of the piston well 33 via a support rod 35, and a piston body 28 integral with the piston well 33 is swingably held by a diaphragm 29. The rod 35 and the piston main body 28 constitute a gimbal piston. Then, as shown in FIG. 2, in a state where an appropriate air pressure is supplied to the air chamber 30, the side plate 22 and the piston main body 28 are supported substantially in the left and right direction which is the axial direction of the air spring S2. , Very soft spring characteristics can be obtained in the axial direction, and like the vertical air spring S1,
Due to the function of the gimbal piston, extremely soft spring characteristics are obtained also in the vertical direction and the front-rear direction, which are orthogonal to the axis, and thereby excellent vibration isolation performance is obtained.

Further, in the horizontal air spring S2, an axial (left-right) load acting on the swinging piston body 28 from the support rod 33 suppresses the swinging of the piston body 28. The horizontal air spring S2.
Similarly, the vertical air spring S1 has a mechanical self-centering effect similarly to the above-described vertical air spring S1, thereby obtaining a required positioning accuracy.

The reference numerals 38, 38, 38 shown in FIG.
Each of the bottom plate members 10c of the inner casing 10
Are air passages provided so as to individually communicate with the air chambers 15, 30, 30. Reference numerals 39, 39,
Numeral 39 denotes air valves which are individually connected to the air passages 38, 38,..., Respectively. Each of the air valves 39 is connected to each of the air chambers 15, 30,. (See FIG. 8) are individually connected to adjust the supply and discharge flow rates of air to and from.

(Control of Air Pressure) The precision anti-vibration table A according to this embodiment has four isolators 2, 2,.
In addition to preventing the transmission of vibration from the floor, the controller 40 controls the pressure of the air springs S1, S2 in each of the isolators 2, 2,. The so-called active vibration damping function that actively suppresses the vibrations generated from the devices on the mounting board 3 by adding.

That is, as schematically shown in FIG. 8, each of the isolators 2 has a non-contact type displacement sensor 41 and an acceleration sensor 42 for detecting the vertical displacement and acceleration of the top plate 21, respectively. A displacement sensor 43 and an acceleration sensor 44 for respectively detecting the horizontal displacement and acceleration of the side plate 22 are provided, and output signals from the sensors 41 to 44 are input to the controller 40, respectively. On the other hand, the control signal from the controller 40 corresponds to each air spring S of the isolator 2.
Are output to the servo valves 45, 45,.
The operation of each servo valve 45 receiving this control signal adjusts the supply / discharge flow rate of air to / from the air chambers 15, 30,... Of each air spring, and the pressure of each air spring is quickly changed. It has become. Although not shown, the servo valve 45 is connected to a reservoir tank for storing compressed air, and the air pressure in the reservoir tank is maintained at a predetermined value by the operation of an electric pump similarly connected to the reservoir tank. It is supposed to be.

The servo valve 45 by the controller 40
The contents of the control are, for example, as shown in the block diagram of FIG. 9 for each of the isolators 2 for the control in the horizontal direction. The controller 40 includes information on a preset reference position and a horizontal displacement sensor. The duty ratio of the servo valve 45 is calculated based on the signal from the acceleration sensor 43 and the signal from the acceleration sensor 44, and this is output as a control signal. The air pressure of the air spring S2 in the horizontal direction of the isolator 2 is adjusted by the servo valve 45 receiving this control signal,
The vibration from the floor and the vibration generated by the equipment on the mounting board 3 become disturbance f, and the outer casing 2 of the isolator 2
0 vibrates. At this time, the horizontal acceleration (X ″) of the top plate 21, which is a control target surrounded by a virtual line in FIG.
And the acceleration (X ″)
The displacement (XX) of the top plate 21 in the horizontal direction corresponding to the square of is detected by the displacement sensor 43 and fed back to the controller 40.

Based on the signal from the acceleration sensor 42, the horizontal vibration of the top plate 21 is canceled, that is, the horizontal direction of the top plate 21 is substantially the same as that of the horizontal vibration and opposite in phase. Horizontal air springs S2 and S2 that impart control vibration
Is determined, and the displacement sensor 43
From the reference position of the top plate 21 is calculated, and the duty ratio of the servo valve 45 is calculated so as to satisfy the two conditions as much as possible. .

Since the control of the air pressure is limited to the response of the air spring and cannot follow the vibration of a very high frequency, the above-mentioned active vibration suppression control generally has two steps.
This is performed in response to vibration of a frequency of 00 Hz or less. For calculating the duty ratio of the servo valve 45, various well-known methods may be used, and a specific description is omitted here. For example, PID control can be applied. Alternatively, state feedback control using information on the vertical acceleration, velocity, and position of the top plate 21 as a state variable can be applied.
If the vibration generated by the device on the mounting board 3 is known, feedforward control may be performed using this as a reference signal.

Then, by the active vibration damping control, according to the precision anti-vibration table A of this embodiment, the mounting board 3
It is possible to suppress vibrations generated from the above devices and the like, and to eliminate the resonance phenomenon of the isolator 2 with respect to insulation of vibrations from the floor.
As shown by an example at 0, the vibration isolation performance can be further improved. That is, the graph (P) shown by a broken line in FIG. 5 shows the transmission characteristics of the horizontal vibration of a type without active vibration suppression control (hereinafter referred to as a passive type) on a logarithmic scale, and is shown in FIG. As in the graph, the resonance point R1 appears in an extremely low frequency range. On the other hand, if the active vibration damping control as in this embodiment is performed, the resonance point R1 can be eliminated as shown by the graph (A) shown by the solid line in FIG. It can be seen that even better vibration isolation performance can be obtained from the range.

Therefore, according to the precision anti-vibration table A according to the first embodiment, first, a gimbal piston is used as the vertical air spring S1 of each isolator 2 supporting the mounting board 3. With this air spring, an excellent vibration isolation effect over a wide frequency range in the vertical and horizontal directions can be obtained. Further, a pair of air springs S2 and S2 are disposed to oppose each other on both the left and right sides of the isolator 2 so as to support a horizontal load, and the air pressure of each air spring S2 is changed together with the vertical air spring S1. Thus, an active vibration damping function of actively adding control vibration to cancel the vibration to the top plate 21 is obtained, and the vibration isolation performance is further improved.

As a feature of the present invention, in the isolator 2 according to this embodiment, the horizontal air spring S2 is provided with a gimbal piston similarly to the vertical air spring S2, so that the bellows and the like are used. In the isolator 2 as a whole, high positioning accuracy is ensured both in the vertical direction and in the horizontal direction without causing problems such as deterioration of spring characteristics in the direction perpendicular to the axis of the air spring and deterioration of positioning accuracy. In addition, a very soft spring characteristic can be obtained in all directions, and the vibration isolation performance can be improved sufficiently. In addition, this makes it possible to maximize the effects of the active vibration suppression control.

(Modification) FIG. 11 shows a modification in which a so-called dome gimbal piston is used as an air spring in the isolator 2. This dome gimbal piston is different from the gimbal piston described in the above embodiment in that a rolling element is further interposed between the top plate 21 or the side plate 22 and the support rods 24, 33 to form air springs S1, S2. When a load in the direction perpendicular to the axis perpendicular to the axial direction of the
Alternatively, the vibration can be absorbed by relatively rolling the side plate 22 and the rolling element.

More specifically, the gas bubbles in the vertical direction will be described. As shown in the drawing, a thick disk-shaped rolling element 48 is disposed at the upper end of the support rod 24 supporting the top plate 21. The upper surface of the rolling element 48 is formed in a spherical shape, and the lower surface of the top plate 21 is in contact with the rolling element 48 and is rotatably supported. For this reason, in the vertical air spring S1, not only the swing motion of the piston body 13 but also the top plate 21 against the horizontal vibration.
The vibration is also absorbed by the rolling motion between the rotor and the rolling element 48, whereby the horizontal spring characteristic of the isolator 2 is further softened, and the vibration isolation performance is improved. Further improvement is achieved.

Similarly, a pair of left and right air springs S2, S
By using the dome gimbal piston for 2, the spring characteristics in the direction perpendicular to the axis, such as the vertical direction and the front-back direction, can be further softened.
Vibration isolation performance can be further improved.

As described above, if a dome gimbal piston is used for the vertical air spring S1, for example, the horizontal spring constant decreases and the horizontal restoring force also decreases. For example, in the left-right direction, since the restoring force can be obtained by the air springs S2, S2 in the left-right direction, the positioning accuracy is sufficiently high. Also, the four isolators 2, 2,.
Of these, the two isolators 2 are provided with a pair of air springs S2 and S2 in the left-right direction.
If the remaining two isolators 2 are provided with a pair of air springs S2 and S2 in the front-rear direction, the anti-vibration table A can obtain accurate positioning accuracy in the entire horizontal direction.

(Embodiment 2) FIGS. 12 and 13 show the structure of an isolator 50 according to Embodiment 2 of the present invention. As is clear from FIG. Since it has the same configuration as that of the modification, the same members are denoted by the same reference numerals, and description thereof will be omitted.

The isolator 5 of the second embodiment
Numeral 0 is a passive type that does not perform active vibration suppression control, unlike the first embodiment, and has a feature that a horizontal air spring S2 is connected to the isolator 50 as shown in FIG. The air chambers 30 of the gas springs at the front and rear or at the left and right as well as the front and rear as well as the left and right are communicated with each other.

More specifically, in the isolator 50 according to the second embodiment, a dome gimbal piston is employed as the air spring S1 in the vertical direction, similarly to the modification. In the vertical air spring S1, the mechanical restoring force of the gimbal mechanism can be adjusted by setting the curvature of the upper surface of the rolling element 48.
The spring constant in the horizontal direction of the vertical air spring S1 can be substantially zero.

As shown in FIG. 12, the air chambers 30, 30,... Of the horizontal air springs S2, S2,.
2 and each of the communication passages 52
Is provided with an orifice 53 for reducing the amount of air flow. Since the air chambers 30 of the respective air springs S2 communicate with each other, the air springs S2 have extremely small spring constants in the axial direction. In combination with the reduction in the horizontal spring constant of the isolator 50, the horizontal spring constant of the isolator 50 as a whole can be reduced as much as possible.

Therefore, according to the precision anti-vibration table A according to the second embodiment, the dome gimbal piston is used for the vertical air spring S1 and the horizontal air spring S1 is used.
The air springs 30, 30,... Of S2, S2,... Communicate with each other to reduce the horizontal spring constant of the isolator 50 as much as possible.
Hz, it is possible to obtain an ideal anti-vibration performance having substantially no resonance point despite being a passive type anti-vibration device.

Moreover, even if such a configuration is adopted, the air chambers 30, 3 in the horizontal air springs S2, S2,.
If the pressures of 0,... Are increased to some extent, an axial pressing force can be obtained in each of the air springs S2, and by providing a tapered portion of an appropriate shape on the outer peripheral side of the piston 28, A difference is generated in the pressing force of the left and right air springs with respect to the displacement in the horizontal direction, whereby a restoring force in the direction perpendicular to the axis is obtained, so that the positioning accuracy of the isolator 50 as a whole in the horizontal direction can be secured. The orifices 53, 53,... Are provided in the communication passages 52, 52,... So that a damping force due to air flow resistance can be obtained. However, the orifices 53 may not be provided. It is possible.

(Other Embodiments) The present invention is not limited to the configurations of the first and second embodiments and the like, but includes other various configurations. That is, the anti-vibration device according to the present invention may be of the active type as in the first embodiment, or may be of the passive type as in the second embodiment. The vertical and horizontal air springs S1 and S2 may be provided with either a gimbal piston or a dome gimbal piston.

As the air spring S2 in the horizontal direction,
A pair of air springs S2 and S2 facing each other as in the first embodiment may be provided.
.. May be provided, or only one horizontal air spring S2 may be provided.

Further, instead of the air springs S1 and S2,
For example, a gas spring filled with nitrogen gas or the like can be used.

In addition, in each of the above-described embodiments, the vibration isolator A is configured by using the four isolators 2 and 50. However, the present invention is not limited to this. For this purpose, three or four isolators (isolators) can be used to support a mounting board designed specifically for these devices, or a movable floor to be embedded in a grating floor of a clean room can be similarly provided by an isolator. It can be configured to support.

[0066]

As described above, according to the gas spring type vibration damping device according to the first aspect of the present invention, the gas spring for supporting the supported body in the vertical and horizontal directions with respect to the fixed base, respectively, By adopting a gimbal piston not only in the vertical direction but also in the horizontal direction, without deteriorating the spring characteristics in the direction perpendicular to the axis like bellows
Excellent vibration isolation performance and high positioning accuracy can be achieved both in the vertical and horizontal directions of the vibration isolation device.

According to the second aspect of the present invention, the lower surface of the load receiving member of the piston is rotatably abutted against the upper end surface of the support column by the vertical gas bubbling, so that the horizontal direction is achieved. Can be further softened so that the vibration isolation performance can be further improved.

According to the third aspect of the present invention, by arranging the gas springs in the horizontal direction to face each other so that the central axes thereof substantially coincide with each other, the load on the supported member can be more stably supported.

According to the fourth aspect of the present invention, the gas chambers of the gas springs facing each other in the horizontal direction are communicated with each other, thereby minimizing the axial spring constant of the pair of gas springs, thereby isolating the gas springs in the horizontal direction. Performance can be improved as much as possible.

According to the fifth aspect of the invention, the vibration of the supported member can be actively suppressed by controlling the gas pressure of the gas spring, and a gimbal piston is provided as a horizontal actuator which is an essential component in this case. The effect of adopting the gas spring is particularly effective.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an entire configuration of a precision vibration isolation table A according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a schematic configuration of an isolator (gas spring type vibration damping device) without an outer casing.

FIG. 3 is a vertical sectional view of the isolator.

FIG. 4 is an exploded perspective view showing an attachment structure of a piston body and a diaphragm to a casing.

FIG. 5 is a graph showing an example of a vertical vibration isolation performance of an isolator.

FIG. 6 is a graph showing an example of horizontal vibration isolation performance of an isolator.

FIG. 7 is equivalent to FIG. 3 in a state where the outer casing is displaced in the horizontal direction.

FIG. 8 is a schematic configuration diagram of an active damping control system for an isolator.

FIG. 9 is a block diagram of active vibration suppression control.

FIG. 10 is a graph showing the horizontal vibration isolation performance by active vibration suppression control in comparison with a passive type.

FIG. 11 is a diagram corresponding to FIG. 3 showing a configuration of an isolator provided with a dome gimbal piston according to a modification.

FIG. 12 is a diagram corresponding to FIG. 3, illustrating a configuration of a passive type isolator according to a second embodiment.

FIG. 13 is a longitudinal sectional view illustrating a configuration of an isolator according to a second embodiment.

[Explanation of symbols]

 A Precision anti-vibration table S1, Air spring (Gas spring) Z Vertical axis 2 Isolator (Vibration isolator) 3 Mounting board (Supported body) 10 Inner casing (Fixed base) 11 Recess 12 Opening 13, 28 Piston main body (piston main body member) 14, 29 Diaphragm 15, 30 Air chamber (gas chamber) 18, 33 Piston well (extending portion) 19 Well slag (bottom portion of extending portion) 18b, 33a Hollow portion 20 Outer casing 21 Top plate (Load receiving member) 22 Side plate (Load receiving member) 24, 35 Support rod (Support column) 40 Controller (Control means) 42, 44 Acceleration sensor (Detecting means) 45 Servo valve (Adjusting means) 48 Roller 52 Continuous aisle

Claims (5)

[Claims] 1. A gas spring type comprising: a fixed base, a vertical gas spring for supporting a supported member in a vertical direction, and a horizontal gas spring for supporting the supported member in a horizontal direction. In the vibration damping device, the gas spring has a concave portion provided to open outward on the fixed base, a piston disposed near the opening of the concave portion, and an opening peripheral edge of the piston and the concave portion. A load receiving member disposed on one side of the piston that is relatively far from the recess in the direction of the center axis, and the load receiving member. A cylindrical piston body member elastically held by the diaphragm so as to be able to swing around any orthogonal axis orthogonal to the central axis, and separated from the other side in the axial direction from the load receiving member. Of the piston body member A support column extending toward the other side in the axial direction is provided so as to penetrate the center hole. On the other hand, the piston body member has a bottomed cylindrical extension extending toward the other side in the axial direction so as to surround the support column. A gas spring type vibration damping device, wherein an extension is provided, and a tip of the support column is pivotally supported at a bottom of the extension. 2. The vertical gas spring according to claim 1, wherein the lower surface of the load receiving member of the piston is supported in contact with the upper end surface of the support column, and the upper end surface of the support column is formed of a spherical surface. A gas spring type vibration damping device, characterized in that: 3. The gas spring type according to claim 2, wherein the horizontal gas springs are disposed so as to face each other so that the central axes thereof substantially coincide with each other at both horizontal portions sandwiching the fixed base. Anti-vibration device. 4. A gas spring type vibration damping device according to claim 3, wherein a communication passage is provided for communicating the gas chambers of a pair of gas springs disposed to face each other in the horizontal direction. 5. A detecting means for detecting vertical or horizontal acceleration of a load receiving member, and an adjusting means for adjusting gas pressure of a vertical or horizontal gas spring. And control means for changing and adjusting the gas pressure of the gas spring by the adjusting means so as to suppress vertical or horizontal vibration of the load receiving member based on the detection result by the detecting means. A gas spring type vibration damping device characterized by the above-mentioned.