JPH0434245A - Vibration removing device - Google Patents

Abstract

PURPOSE:To suppress an influence of rocking vibration so as to attain also substantial space saving by dividing a mounting bed into upper and lower part stages, providing rigid connection between both the stages through a coupling pillar and arranging a dynamic vibration absorber in space between both the stages. CONSTITUTION:When vibration of acceleration character is input from a set up floor, a vibration remover 20 removes vibration by displaying insulation performance. That is, a vibratory component in a perpendicular direction is substantially reduced with a high frequency side after about 1Hz serving as the center by damping action of a vibration removing system mounting bed 24, each spring mechanism 26 and each oil damper 28 and also concentrically reducing a component of 2.5Hz by vibration absorbing action in an antiresonance point given by a dynamic vibration absorber 30. On the other hand, a component in a horizontal direction is reduced with a high frequency side after about 0.6Hz serving as the center by damping action of the mounting bed 24, spring mechanism 26 and each oil damper 28 in a vibration removing system and also concentrically reducing a component of 0.8Hz by vibration absorbing action in the antiresonance point applied by the dynamic vibration absorber 30.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vibration isolator, and in particular, a dynamic vibration absorber that reduces vibrations at a specific frequency is auxiliary installed on a mounting table on which anti-vibration equipment is mounted. This invention relates to an improvement of a vibration isolator having a structure in which:

[Conventional technology]

Generally, buildings constructed on soft ground have a poor microvibration environment, and it is necessary to use vibration isolators when installing anti-vibration equipment that requires high precision, such as electron microscopes.

As this vibration isolator, for example, the one shown in FIG. 11 is known. The vibration isolator 1 in the same figure is a mounting table 2.
and (20) a spring mechanism 3 that supports the mounting table 2 at a plurality of support points.
and a damping mechanism 4.

Each of the spring mechanisms 3 is made up of a multi-stage laminated rubber 5 that performs a horizontal spring function and a diaphragm type air spring 6 that performs a vertical spring function, which are connected in series.

Each of the damping mechanisms 4 includes an oil damper that is provided between the installation floor and the mounting table 2 and is responsible for generating damping force in the horizontal and vertical directions. Anti-vibration equipment 7 is mounted on the top surface of the mounting table 2.
is listed. This mounting table 2 has a sufficiently heavy additional mass.1. The position of the composite center of gravity G, 2 of the entire vibration isolation system is set to be lowered with respect to the center of gravity Gt of the anti-vibration device 7 and the center of gravity G of the mounting table 2. This stabilizes the vibration mode of the vibration isolation system, resulting in a vibration isolation device having a low natural frequency of, for example, 0.57.

However, in the vibration isolator 1 shown in FIG. 11 described above,
The further you try to obtain higher vibration isolation performance, the lower the composite center of gravity G+z must be located in the vibration isolation system.
For this purpose, it is necessary to increase the additional weight of the mounting table 2, which inevitably increases the height of the apparatus 1. Therefore, in order to avoid such an increase in height, the vibration isolator 1 is usually installed by digging into the floor, but there is a problem in that the construction cost of this excavation work is high. In addition, when the vibration isolator 1 becomes larger, it needs to be manufactured at the installation site to avoid the hassle of transporting it, but in this case, manufacturing methods are limited due to problems such as manufacturing equipment, and accuracy is limited. High processing speed becomes difficult.

The natural frequency in the three-dimensional direction of the vibration isolator 1 having the structure shown in FIG. 11 is set sufficiently low as is conventionally known.
It is set to use a range with a high vibration isolation level, which is a frequency range higher than its natural frequency. However, even in such cases, if there is a frequency component that is particularly required to be removed from vibration-absorbing equipment, it is essential to use the vibration-isolating device shown in Figure 12 in order to firmly reduce that specific frequency component. It has become.

The vibration isolator 8 shown in FIG. 12 has a structure in which a main vibration isolator system is provided with a dynamic vibration absorber that reduces vibrations at a specific frequency. In other words, the vibration isolator 8 includes the mounting table 9,
Multiple spring mechanisms 10. ...10, and a plurality of damping mechanisms 11. . . , 11 constitute a primary vibration isolation system, and a dynamic vibration absorber 12 as a secondary vibration isolation system is installed below the mounting table 9. The dynamic vibration absorber 12 includes a mass body 12a, a plurality of springs 12b, . This dynamic vibration absorber 12 absorbs and supplements vibrations that cannot be absorbed by the main primary vibration isolation system. Reference numeral 13 denotes an anti-vibration device placed on the mounting table 9.

[Problems to be Solved by the Invention] However, in the conventional vibration isolator 8 shown in FIG. , Due to the complexity of the micro-vibration environment, the targeted micro-vibration components may not be absorbed properly, leaving areas with low vibration isolation levels. In such cases, it is extremely troublesome to adjust the vibration absorption frequency of the dynamic vibration reducer.

Furthermore, in the vibration isolator 8, the dynamic vibration absorber 12 must be installed at the lowest point of the vibration isolator system to maximize its performance. In other words, in the structure shown in FIG. 12, it is desirable to install the dynamic vibration reducer 12 at the lowest point of the mounting table 9 as shown in the figure, but in this case, only the space of the dynamic vibration absorber 12 is required. The height of the mounting table 9 becomes higher, and even if the weight is the same, the center of gravity of the mounting table 9 G2. That is, the overall composite center of gravity CtZ also becomes high, which causes a problem that the vibration mode becomes unstable and the influence of rocking increases.

In the second case, it is possible to dig down to the bottom of the floor and install the vibration isolator 8 and lower the height of the mounting table 9 to lower the composite center of gravity, but as mentioned above, there are problems such as increased costs due to excavation work. be.

The present invention has been made in view of the problems of the prior art described above, and the first problem to be solved is to easily make the center of gravity of the vibration isolator possible without increasing the weight of the set mounting table. The object of the present invention is to make it possible to lower the height of the vibration absorber and to eliminate the need for increasing the size due to the installation of a dynamic vibration absorber. Also, the second
The problem is to solve the first problem, to be able to install a dynamic vibration absorber at the position where the vibration absorption effect is highest, and to simultaneously perform three-dimensional vibration absorption with a single dynamic vibration absorber. Furthermore, a third object is to solve the second problem and to make it possible to easily adjust the vibration absorption frequency of the dynamic vibration reducer.

[Means to solve the problem]

In order to solve the first problem, the invention according to claim (1) includes a vibration isolation system in which a mounting table is supported via a spring mechanism and a damping mechanism, and a vibration isolation system that is attached to the mounting table and that vibrates at a specific frequency. In a vibration isolator equipped with a dynamic vibration absorber that reduces The dynamic vibration absorber is arranged in the space of .

In addition, in order to solve the second problem, the invention according to claim (2) includes a vibration isolating system in which the mounting table is supported via a spring mechanism and a damping mechanism, and a vibration isolation system that is attached to the storage table and that generates a specific frequency. In a vibration isolator equipped with a dynamic vibration absorber for reducing vibration, the mounting table is divided into an upper stage and a lower stage, the upper stage and the lower stage are rigidly connected via a coupling column, and the dynamic vibration absorber is , a mass body, a rod for suspending the mass body from the upper stage or a portion rigidly connected to the upper stage, a spring inserted between the rod and the mass body, and the mass body and the lower stage. Alternatively, it has a damper inserted between the lower stage and a portion rigidly connected to the lower stage.

Furthermore, in order to solve the third problem, among the inventions described in claims (3) to (5), the dynamic vibration absorber according to the invention described in (3) at least has a configuration in which the mass of the mass body can be increased or decreased. It is said that In addition, the dynamic vibration absorber described in (4) has a small
The spring constant of the spring is adjustable. Furthermore, the dynamic vibration reducer described in (5) includes at least a suspension distance variable mechanism that can change the suspension distance of the rod with respect to the mass body.

[Function] In the invention described in claim (1), the mounting table is divided into an upper stage and a lower stage by a connecting column, so! Even if the set weight of the entire mount is the same, the center of mass due to the upper and lower stages is lowered, and the moment of inertia becomes substantially larger even without increasing the additional mass of the mount to increase its size.

At this time, by changing the specific gravity, the weight of the lower stage can be made larger than the weight of the upper stage. In this way, it is possible to efficiently lower the center of gravity of the entire mounting table and set a large moment of inertia while occupying a smaller space. . This provides a large inertial effect and reduces the effects of rocking vibrations. Also, the top.

Since a space is formed between the lower stages, this space can be used to install a dynamic vibration absorber, and compared to simply installing a dynamic vibration absorber at the bottom of a single-layer structure mounting table, the entire vibration isolator is It is possible to avoid the increase in size.

In addition to obtaining the above-mentioned effects, the invention as claimed in claim (2) also provides a dynamic vibration absorber in which the mass body is supported in the vertical direction via a damper and a spring, and in the horizontal direction via a damper and a rod. Since it is supported by the oscillator, it has a natural frequency in both the vertical and horizontal directions. This results in
Even though it is a single dynamic vibration absorber, it is possible to obtain a three-dimensional vibration damping effect at the same time, and the vibration isolator as a whole can obtain vibration isolation performance that has the vibration absorption characteristics of a dynamic vibration absorber. In other words, a significant space saving can be achieved compared to the case where dynamic vibration absorbers are installed individually in each direction. Further, since this dynamic vibration absorber is connected to the upper stage which is rigidly connected to the lower stage, it is substantially attached to the lowest point of the main vibration isolation system, and its vibration absorption effect is the highest.

Furthermore, among the inventions described in claims (3) to (5), (3)
), since at least the mass of the mass body can be increased or decreased, the natural frequencies of the dynamic vibration absorber in the vertical and horizontal directions can be adjusted. Furthermore, in the configuration described in (4), the natural frequency of the dynamic vibration absorber in the vertical direction can be adjusted by changing at least the spring constant of the spring. Furthermore, in the configuration described in (5), the horizontal natural frequency of the dynamic vibration absorber can be adjusted by changing at least the suspension distance of the rod with respect to the mass body using the suspension distance variable mechanism.

〔Example〕

Next, an embodiment of the present invention will be described based on FIGS. 1 to 7.

In the figure, 20 is a vibration isolator, and 22 is an anti-vibration device such as an electron microscope placed on the vibration isolator 20. The vibration isolator 20 includes a mounting table 24 on which the anti-vibration device 22 is placed, and a spring mechanism 26 that supports the mounting table 24 at a plurality of support points.・
. . , 26, and oil dampers 28 as damping mechanisms installed at multiple points between the mounting table 24 and the floor. ..., 2
8, and a dynamic vibration reducer 30 as a secondary system, which is attached to the mounting table 24.

Each spring mechanism 26 has a structure in which a multi-stage laminated rubber 32 that performs a horizontal spring function and a diaphragm air spring 34 that performs a vertical spring function are connected in series. The mounting table 24 is divided into an upper stage 24a and a lower stage 24b, and the lower stage 24b is connected to a plurality of connecting columns 2.
4c,... 24c are rigidly connected to the upper stage 24a and are suspended from both stages 24a, 24b.
A space of a predetermined height is formed between them. In this example,
Both stages 24a, 24b and connecting columns 24c,...2
4c, a light and highly rigid member is used for the upper stage 24a, and a heavier material is used for the lower stage 24b. Further, in the center of the lower stage 24b, there is formed a punched hole A, which is rectangular when viewed from the top surface, into which a part of a dynamic vibration absorber 30, which will be described later, can be loosely inserted.

In addition, each oil damper 28 is connected to the floor and lower stage 2.
4b to generate damping force in the horizontal and vertical directions.

As shown in the figure, the dynamic vibration absorber 30 has both stages 24a.

24b, a fixed mass body 30a located at the lowest end, an adjustment mass body 30b placed on this fixed mass body 3a, and a plurality of oils connected to the fixed mass body 30a. dampers 3°C2..., 30c, a plurality of hanging rods 3°d, -, 30d supporting the image bodies 30a, 30b, and a spring 30e.
, -30e and hanging rod clamps (hanging distance variable mechanism) 30f, . . . , 30f.

To explain this in detail, the mass body 30a has a fixed mass and is loosely inserted into the punched hole A of the lower stage 24b,
An adjustment mass body 30b is fixedly mounted on the mass body 30a so that its mass can be freely adjusted. The upper end of each hanging rod 30d is attached to a predetermined position on the lower surface of the upper stage 24a, and the lower end is connected to the fixed mass body 30 through a spring 30e in series.
attached to a. Each hanging rod clamp 30f
is attached at one end to the adjacent connecting column 24c so as to be vertically movable, and the other end grips a midway position of the hanging rod 30d so as to be vertically movable. It is rigidly connected to the stand 24. moreover,
Each oil damper 300 is inserted between the fixed mass body 30a and the lower stage 24b, and generates damping force in the horizontal and vertical directions, making it possible to adjust the vibration damping effect of the dynamic vibration absorber 30. .

That is, the dynamic vibration absorber 30 of this embodiment is supported in the vertical (up and down) direction by a plurality of springs 30e and oil dampers 30c, and in the horizontal direction by a plurality of rods 30d and oil dampers 30c having spring functions. Although it is a single vibration absorber, it forms a vibration absorption system in three dimensions.

Here, the vibration isolation model diagram of the vibration isolation system in which the primary system and the secondary system are linked as described above is shown as shown in FIG. 2, and the operating principle will be explained based on this model.

The dynamic vibration absorber 30 (secondary system) is attached to the vibration isolation system (-
It has the function of adding an anti-resonance point and a resonance point to the next system).

Therefore, in this embodiment, the frequency of the anti-resonance point is made to match the frequency of the specific vibration input (in cases 2 and 3 described later), or the anti-resonance point is made to match the resonance point of the primary vibration isolation system ( Case 1, which will be described later), is intended to improve the vibration insulation performance.

The anti-resonance point of the secondary system that contributes to improving the insulation performance is the resonance point frequency of the secondary system, and is determined by its damping ratio and mass ratio.

Now, the mass of the -order system M3. Spring constant KI, damping constant C1
and the mass of the secondary system M2. Depends on the spring constant.

The damping constant is set to 02. Also, the natural frequency of the -order system is ωt
= (Kt /Mt) ””, the natural frequency of the secondary system is ω! = (Kt /Mt)”t, − order system,
Damping ratio of secondary system ←, ζ3, mass ratio μ, -order system, ratio of natural frequency to input frequency to secondary system u I + u t,
And complex number variables A, B of − order system, quadratic system, ζ + =
C+ / (2M1ωI) ζz =Ct / (2Mz a)! )μ−M, /M
.

13, = ω/ω1 l ul = ω/ω2A=1+j
2 ζI ul B=1+j2 ζt ul If we set 2 ζI ul B=1+j2 ζt ul , then the vibration transmissibility τ of the -order system and the quadratic system alone.

τ2 is expressed as follows. Therefore, the second-order system (dynamic vibration reducer) with the transmissibility τ,
When is attached to a primary system with a transmissibility τ1, τ1 is influenced by τ2. Vibration transmissibility τ1 of the primary system affected by it
′ is (A ul”) (B uz”) II ut
"B... (1) Represented by:

When simulation is performed by substituting specific numerical values for each dimension in the vertical direction shown in Table A below into the equation for the vibration transmissibility τ,', the characteristics shown in FIG. 3(a) are obtained. Similarly, when simulation is performed by substituting specific numerical values for each dimension in the horizontal direction shown in Table B below, the characteristics shown in FIG. 3(b) are obtained.

Table A Table B Note that the horizontal axis in FIGS. 3(a) and 3(b) is the frequency of disturbance vibration input, and the vertical axis τ1' is the vibration transmissibility expressed by the above equation (1).

First, in all cases 1 to 4 in Table A, the vertical value of the -order system is set to the natural frequency F+ = IHz,
For this fixed-order system, let us define the natural frequency F2 of the second-order system as F
2=IHz (Case 1), 2.511z (Case 2.
3) is set. In cases 2 and 3, the natural frequency F2 has the same value, but the damping constant is set larger in case 3. Incidentally, case 4 is a case in which no secondary system is added.

As can be seen from the simulation results in FIG. 3(a), in case 1, the transmissibility in the vicinity of the disturbance frequency I Hz, where the vibration transmissibility of the primary system deteriorates, is improved;
In case 2.3, the transmissibility is improved in the region of 2.57 depending on the attenuation constant.

In other words, Case 2.3 is valid when the disturbance frequency to be damped is 2.5 Hz.

On the other hand, in case 1.2 of Table B, the horizontal value of the -order system is set to the natural frequency F, = 0.5H2, and the natural frequency F of the second-order system is set for this -order system. ! ,F,
= 0.8 Hz (case 1). Case 2 is a case where no secondary system is added.

Here, in order to see the improvement rate when u2=1, τ,′
/τ1 is calculated as follows.Here, assuming that the vibration input frequency is high and u is large, it is expressed as follows.

According to this, in a vibration isolator with a secondary system added, the degree of improvement for vibration input at a specific frequency is increased (i.e., "
It can be seen that in order to increase τ1'/τ1), it is necessary to decrease the attenuation rate ζ2 of the secondary system, but if the attenuation rate ζ2 is decreased, the amplification degree of the adjacent region also increases. The attenuation rate ζ2 is adjusted to suitably satisfy both conditions. Furthermore, in order to give a certain range to the specific frequency to be improved, the mass ratio μ may be increased.

By the way, in order to set each specification of the vibration isolator 20 in this example, when the acceleration spectrum (peak hold spectrum) on the floor on which the vibration isolator 20 is installed was measured, it was found that the fourth The characteristics shown in Figures (a) to (C) were obtained. From this characteristic, 2.
57. It was found that there was a large micro-vibration at 0.8 Hz in the horizontal (X, Y-axis) direction that was difficult to remove with conventional vibration isolators. For this reason, the natural frequency of the -order system is set to 0.5 Hz in the horizontal direction and 0.9 Hz in the vertical direction, and the natural frequency is set to 0.8 Hz in the horizontal direction and 2.5 Hz in the vertical direction by the dynamic vibration absorber 30.
It is assumed that Hz minute vibrations are suppressed.

Therefore, the specifications for the vertical direction of the -order system and the quadratic system are as follows:
The same value as Case 2 in Table A mentioned above was used. Also,
- Each horizontal dimension of the second-order system and the second-order system was set to the same value as Case 1 in Table B described above.

Let us examine the vibration isolation performance of the entire vibration isolator 20 based on these numerical settings. Based on the above formula (1), the vibration transmissibility τ1'
is required, and the vibration isolation level in the vertical direction (-20・lo
The frequency and phase characteristics of g τ1') are shown in Figure 5(a).
The characteristics shown in (b) are obtained. In other words, the anti-resonance point of the dynamic vibration absorber 30 is added to the point of vibration input 2.57 in the vertical direction, and a valley (approximately -21 dB) with a low vibration isolation level is formed. On the other hand, the horizontal vibration transmissibility τ,' is determined based on the above equation (1), and the frequency and phase characteristics of the horizontal vibration isolation level are as shown in Figures 6(a) and (b). It will be done. In other words, the horizontal vibration input is 0.8 H
The anti-resonance point of the dynamic vibration reducer 30 is added to the point z, and a valley (approximately -5 dB) with a low vibration isolation level is formed.

Next, the effects of this embodiment will be explained.

When vibration having the acceleration characteristic shown in FIG. 4 described above is input to the vibration isolator 20 from the installation floor, the vibration isolator 20
The insulation performance shown in the figure is demonstrated to provide vibration isolation. In other words, the vertical vibration component shown in Fig. 4(C) is the vibration isolation system (
-Next system) mounting table 24° each spring mechanism 26. The damping effect of each oil damper 28 significantly reduces the vibration mainly on the high frequency side after about IHz (see the area of negative insulation level in Figure 5), and it is added by the dynamic vibration reducer 30 (secondary system). 2.5Hz due to the vibration absorption effect of the anti-resonance point
components are intensively reduced.

On the other hand, the horizontal component shown in FIGS. 4(a) and 4(b) is the vibration isolation system (-order system) mounting table 24. Due to the damping action of each spring mechanism 26° and each oil damper 28, it decreases mainly on the high frequency side after about 0.6 seconds (refer to the area of negative insulation level in Fig. 6), and the dynamic vibration reducer 30 (secondary 0.0 due to the vibration absorption effect of the anti-resonance point added by the system).
The 8 Hz component decreases intensively. As a result, a high level of vibration isolation performance is exhibited, including vibration components of specific frequencies (2.5 Hz in the vertical direction and 0.8 Hz in the horizontal direction) that could not be sufficiently removed by the vibration isolation system alone.

As a result, the vertical acceleration spectrum (peak hold vector) on the upper stage 24a has the characteristics shown in FIG. 7(C), and the horizontal acceleration spectrum (peak hold spectrum) has the characteristics shown in FIG. 7(a). The characteristics shown in b) are obtained. In this way, even if the vibrations shown in FIGS. 4(a) to (C) are input, the vibration characteristics on the upper stage 24a are as shown in FIGS. 7(a) to (C), respectively. Excellent vibration isolation is achieved in the area of use, centering on vibrations at the targeted frequency.

In this embodiment, vibration is isolated as described above, but the mounting table 2
4 is divided into upper and lower parts, and the specific gravity of the lower stage 24b is made larger than that of the upper stage 24a, so the center of gravity can be lowered efficiently in a smaller space than when the upper and lower stages have the same specific gravity, and the inertia Since the moment can be set larger than before, the effects of rocking vibration can be significantly reduced. In addition, both stages 24a and 24b
The dynamic vibration absorber 30 can be installed using the space between them, which prevents the entire vibration isolator from increasing in size compared to the conventional case where it is installed at the bottom of the mounting table, and also raises the center of gravity of the mounting table 24. I won't let you.

Furthermore, since the dynamic vibration absorber 30 is substantially connected to the lower part of the mounting table 24, this is the most effective installation position for the mode to be controlled, and its vibration absorption effect is most effectively exhibited. Therefore, the three-dimensional vibration and rocking vibration transmitted to the anti-vibration device 22 are minimized, allowing the device 22 to perform highly accurate work.

On the other hand, the dynamic vibration reducer 30 has a single structure in three directions (X,
Y, Z) vibration can be suppressed at the same time. Further, by changing the characteristics of each oil damper 30c, the damping effect can be adjusted. This makes it possible to reduce the installation space compared to conventional systems in which dynamic vibration absorbers are installed individually in each direction, and also allows for a large mass ratio by integrating the mass bodies that were previously installed separately in each direction. can be obtained, which is advantageous in terms of the vibration absorption effect of the dynamic vibration absorber.

In addition, the dynamic vibration reducer 30 has the above-mentioned ωz = (Kz/M
! )"" Based on the formula, the vertical and horizontal natural frequencies F2 can be adjusted by adjusting the mass of the adjustment mass body 30b, and the hanging rod clamp 30f can also be adjusted.
By adjusting the clamp position with respect to the hanging rod 30d, the horizontal spring constant changes to 2, thereby making it possible to adjust the horizontal natural frequency F2. For this reason, in response to the test results of the vibration isolator 20, at the installation site, the natural frequency in the vertical direction is adjusted by adjusting the mass, and then the natural frequency in the horizontal direction is adjusted by changing the clamp position. This has the advantage that fine adjustments can be easily made.

Furthermore, in the configuration of this embodiment, the dynamic vibration absorber 30 can be used to reduce the amplification factor near the natural frequency of the -order vibration isolation system. At this time, the negative-order vibration isolation system has the advantage of being able to reduce ζ and suppress amplification at the resonance point while improving insulation characteristics in the high frequency range.

In this case, ω2 and ζ2 of the dynamic vibration reducer 30 can be optimized under the following conditions using μ as a parameter.

ωz=t/(10μ) ζ2=(3μ/8(1+μ) 3 ) l/1 The maximum amplitude magnification at this time is as follows. Here, XST is the maximum amplitude when there is no dynamic vibration reducer.

Note that in the above embodiment, the upper and lower stages 24a
, 24b is made to have a higher specific gravity at the bottom, but even though the specific gravity is the same, by using a two-stage structure, the center of mass of the rigid system, that is, the center of gravity is lowered by the distance. It is effective and can reduce the effects of rocking vibration.

On the other hand, the above-mentioned embodiment is modified as shown in Fig. 8.9 (the same reference numerals are used for the same configuration as the above-mentioned embodiment).
It can be implemented by Of these, to explain the modification shown in FIG. 8, the lower stage 24b of the mounting table 24 described in the above-mentioned embodiment is set at a fixed position, whereas the lower stage 24b of FIG. It is made movable up and down along each connecting column 24C. This makes it possible to adjust the position of the center of gravity and also to adjust the position R0 of the center of rotation shown in the figure.

The vibration tolerance value of the anti-vibration device 22 is given for the floor on which the device is installed (in this case, the mounting table 24), but from the perspective of the internal structure of the anti-vibration device 22, the part with the most severe vibration conditions is not necessarily the It is not the installation floor. For example, if the anti-vibration device 22 is an electron microscope, the position of the sample stage within the device is the most sensitive part to vibrations. Considering this,
In the modification shown in FIG. 8, the position of the center of rotation R6 can be controlled by moving the lower stage 24b up and down to bring the part most sensitive to vibration to the node point of the rigid body mode of the vibration isolation system. This allows the influence of rotational vibration on the equipment 22 to be minimized. In this way, in the example shown in Fig. 8, rotational vibration can be suppressed by focusing on controlling the center of gravity position, or rotational vibration can be avoided by focusing on controlling the rotational center position. This has the advantage of widening the range of vibration isolation methods to choose from and being able to flexibly deal with the vibration environment and required characteristics of vibration-absorbing equipment.

On the other hand, in the modification shown in FIG. 9, the upper and lower stages 24a, 24b and the connecting column 24c shown in FIG.
are combined into a single mounting table 24, and this is used as a spring mechanism 26. ..., 26 and oil damper 28. ...
, 28, and the hanging position of the hanging rod 30d of the dynamic vibration absorber 30 and the hanging rod clamp 30f.
As shown in the figure, the mounting positions are the bottom and side surfaces of the R mounting base 24.

When configured in this way, the center of gravity position and the center of rotation position are fixed, but the advantages of the dynamic vibration absorber 30 itself can be enjoyed as is, such as the ability to perform three-dimensional temporal vibration absorption with a single dynamic vibration absorber 30. Therefore, depending on the height of the double center of gravity of the vibration damping device 22, even the configuration shown in FIG. 9 can be simplified and a high level of vibration isolation can be achieved.

Furthermore, in the above-described embodiments and modifications, an example was given in which the mass and the rigid connection point of the hanging rod clamp were changed as a configuration for adjusting the natural frequency of the dynamic vibration absorber, but the present invention does not necessarily apply to such a configuration. Without limitation, for example, only the mass body may be adjusted, or only the rigid connection point of the hanging rod clamp may be adjusted, if necessary.

Furthermore, the spring constant of the spring that performs the vertical spring function may be changed as shown in FIG. 10. The configuration in the figure includes a temporary spring 4 that can be displaced in the vertical direction.
0 to the lower end of the hanging rod 30d and the fixed mass body 30a so as not to conflict with the hanging rod clamp similar to that shown in FIG.
It is attached between the lower surface of the body 30a and the attachment position to the mass body 30a can be adjusted. As a result, the leaf spring 40 functions as an auxiliary spring whose spring constant can be changed for the coil spring 30e, and the vertical spring constant can be varied by adjusting the distance l between the supporting points of the leaf spring 40, and the natural frequency in the vertical direction can be changed. Can be adjusted.

The vertical and horizontal natural frequency adjustment means described above may be combined as appropriate.

Furthermore, the damper 3 of the dynamic vibration absorber in the above embodiment
0c is attached between the lower stage 24b and the -order system, but it may be the upper stage 24a or the coupling column 24c, for example, depending on the structure of the entire vibration isolator. On the other hand, the mounting position of the hanging rod clamp 30f with respect to the primary system is also the same as that of the connecting column 24 as described in the embodiment.
For example, the suspension rod 30d may be attached to the upper stage 24a and the lower stage 24b when the suspension rod 30d is suspended from an arm rigidly connected to the connecting column 24c.

Furthermore, the variable suspension distance mechanism of the dynamic vibration absorber according to the invention described in claim (5) is not limited to the above-described embodiments and modifications, and can be used, for example, when the suspension rod clamp 30f is is fixed or the clamp 30f is removed, and the support positions of the mass bodies 30a and 3Qb are moved up and down, and the mass bodies 30a and 3Q of the hanging rod 30d are
A configuration may be adopted in which the hanging distance with respect to 0b is changed, and this also becomes equivalent to the above-described one from the perspective of adjusting the spring constant in the horizontal direction, and the degree of freedom in design is improved.

Furthermore, although the dynamic vibration absorber in the above embodiments and modified examples has a structure capable of absorbing vibration in three dimensions with a single vibration absorber, in the invention described in claim (1), A dynamic vibration absorber that can absorb only vibrations may be used.

〔Effect of the invention〕

As explained above, in the invention recited in claim (1), the mounting table is divided into an upper stage and a lower stage, and the upper and lower stages are rigidly connected through a gap in the vertical direction. Since we decided to install a dynamic vibration absorber in
It is possible to effectively lower the center of gravity and set a large moment of inertia without making the mounting table unnecessarily heavy.The large inertia effect suppresses the effects of rocking vibration, while also making it possible to The specific gravity can be changed, and by making the specific gravity of the lower stage larger than that of the upper stage, the space occupied by the lower stage is narrowed by the increased specific gravity, and the space occupied by the upper stage is
Coupled with the ability to install a dynamic vibration absorber in the space between the lower stages, this has the effect of achieving significant space savings for the entire device.

In addition, in the invention described in claim (2), the mounting table is divided into an upper stage and a lower stage, and the upper and lower stages are rigidly connected through a gap in the vertical direction, and a single A dynamic vibration absorber is installed, and this dynamic vibration absorber is connected to a rigid body including an upper stage via a rod and a spring, and has a mass body connected to a rigid body including a lower stage via a damper. Therefore, in addition to obtaining the same effect as the invention described in claim (1), the dynamic vibration absorber is supported in the vertical and horizontal directions via a spring component and a damping component, and three-dimensional vibration damping can be achieved simultaneously. This allows for a significant space saving compared to setting up dynamic vibration absorbers in each of the three directions, and since the dynamic vibration absorber is essentially installed below the mounting table, its vibration absorption performance can be improved. most effectively demonstrated.

Furthermore, in the invention described in claims (3) to (5),
In addition to obtaining the effect described in claim (2) above, by one or any combination of changing the mass of the mass body, changing the spring constant of the spring, and changing the hanging distance of the rod by the variable hanging distance mechanism, Vertical direction.

Since the natural frequency in the horizontal direction can be adjusted, fine adjustments can be easily made on site.

[Brief explanation of drawings]

1 to 7 are diagrams showing one embodiment of the present invention, in which FIG. 1 is a partially cutaway schematic configuration diagram showing the overall configuration;
Figure 2 is a vibration isolation model diagram based on the configuration example in Figure 1, Figure 3 (a) is a vertical vibration transmissibility characteristic diagram based on the model configuration in Figure 2, and Figure 3 (b) is a vibration isolation model diagram based on the example configuration in Figure 2. Horizontal vibration transmissibility characteristic diagram based on the model configuration shown in Figure 4 (a) to (C)
5(a) and 5(b) are vertical vibration isolation level and phase frequency characteristic diagrams, respectively. Frequency characteristics diagram of horizontal vibration isolation level and phase,
Figures 7(a) to (C) are horizontal and vertical acceleration spectrum diagrams on the mounting table, Figures 8 and 9 are schematic configuration diagrams showing modified examples, respectively, and Figure 10 is the vertical acceleration spectrum diagram. FIGS. 11 and 12, which are partial configuration diagrams of a spring mechanism capable of changing a spring constant, are schematic configuration diagrams showing conventional examples, respectively. The main symbols in the diagram are 20...Vibration isolator, 22...Vibration damping equipment, 24...Iz table, 24a...Upper stage, 24b...Lower stage, 24c...Coupling column ,2
6... Spring mechanism, 28... Oil damper (damping mechanism), 30... Dynamic vibration absorber, 30a... Fixed mass body,
30b... Adjustment mass body, 30c... Oil damper (damper), 30d... Hanging rod (rod), 3
0e... Spring, 30f... Hanging rod clamp (hanging distance variable mechanism), 40... Leaf spring.

Claims (5)

[Claims] (1) In a vibration isolator equipped with a vibration isolating system in which a mounting table is supported via a spring mechanism and a damping mechanism, and a dynamic vibration absorber that is attached to the mounting table and reduces vibrations at a specific frequency, as described above. The stand is divided into an upper stage and a lower stage, the upper and lower stages are rigidly connected via a connecting column, and the dynamic vibration absorber is disposed in the space between the upper and lower stages. Shaking device. (2) In the vibration isolator described above, the vibration isolator includes a vibration isolator in which a mounting table is supported via a spring mechanism and a damping mechanism, and a dynamic vibration absorber that is attached to the mounting table and reduces vibrations at a specific frequency. The mounting table is divided into an upper stage and a lower stage, and the upper and lower stages are rigidly connected via a coupling column. a rod suspended from the tied part; a spring inserted between the rod and the mass body; and a spring inserted between the mass body and the lower stage or a part rigidly connected to the lower stage. A vibration isolator comprising a damper. (3) Claim (2) characterized in that the dynamic vibration reducer is configured such that at least the mass of the mass body can be increased or decreased.
The vibration isolator described. (4) The vibration isolator according to claim 2, wherein the dynamic vibration absorber is configured to be able to change at least a spring constant of the spring. (5) The vibration isolator according to claim 2, wherein the dynamic vibration absorber includes at least a suspension distance variable mechanism that can change the suspension distance of the rod with respect to the mass body.