JP3039671B2 - Anti-vibration device - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a vibration isolator, and in particular, a dynamic vibration absorber for reducing vibration of a specific frequency is installed on a mounting table on which anti-vibration equipment is mounted. The present invention relates to an improvement of a vibration isolator having a structure having a structure described above.

[Conventional technology]

In general, a building constructed on soft ground has a poor micro-vibration environment. For example, an anti-vibration device that requires high precision, such as an electron microscope, needs to use a vibration isolation device.

As this vibration isolator, for example, the one shown in FIG. 11 is known. The vibration isolator 1 in FIG.
And a spring mechanism 3 for supporting the mounting table 2 at a plurality of support points.
And a damping mechanism 4. Each of the spring mechanisms 3 includes a multi-stage laminated rubber 5 having a horizontal spring function and a diaphragm type air spring 6 having a vertical spring function connected in series. Each of the damping mechanisms 4 is configured by an oil damper provided between the installation floor and the mounting table 2 and configured to generate a damping force in a horizontal direction and a vertical direction. An anti-vibration device 7 is mounted on the upper surface of the mounting table 2. The mounting table 2 has a sufficiently heavy additional mass, center of gravity G ₁ of Iyafu device 7, to the center of gravity G ₂ of the mounting table 2, so as to lower the position of the combined center of gravity G ₁₂ of the entire vibration isolation system Is set to As a result, the vibration mode of the vibration isolation system is stabilized, and the vibration isolation device has a low natural frequency such as 0.5 Hz.

However, in the vibration isolator 1 described in FIG.
The higher the vibration isolation performance, the higher the combined center of gravity
G ₁₂ is not a Senebanara so as to be positioned below the anti-vibration system. For this purpose, it is necessary to increase the added weight of the mounting table 2, the height of the inevitably device 1 is increased. Therefore, in order to avoid such an increase in height, the floor is usually dug down to install the vibration isolator 1, but there is a problem that the construction cost of this excavation work is high. In addition, when the vibration isolator 1 becomes large, it is necessary to produce it at the installation site in order to avoid the trouble of carrying in. However, in this case, the production method is limited due to the problem of manufacturing equipment and the like, and the accuracy is low. High processing becomes difficult.

The natural frequency in the three-dimensional direction in the vibration damping device 1 having the structure described in FIG. 11 is set sufficiently low as conventionally known.
It is set to use a high range of the vibration isolation level, which is a region of a frequency higher than the natural frequency. However, even in such a case, when there is a rejection frequency component particularly required for the anti-vibration device, it is essential to use the anti-vibration device shown in FIG. 12 in order to strengthen the reduction of the specific frequency component. Has become.

The vibration damping device 8 shown in FIG. 12 has a structure in which a main vibration damping system is provided with a dynamic vibration absorber for reducing vibration of a specific frequency. That is, as in FIG. 10, the vibration isolator 8 includes a mounting table 9, a plurality of spring mechanisms 10,..., And a plurality of damping mechanisms 11,. A dynamic vibration absorber 12 as a secondary vibration isolation system is provided below. This dynamic vibration absorber
Reference numeral 12 denotes a mass body 12a, a plurality of springs 12b,..., 12b supporting the mass body 12a between the mounting table 9, and a viscous damper.
12c. The dynamic vibration absorber 12 absorbs and supplements vibrations that cannot be completely absorbed by the main primary vibration isolation system. Reference numeral 13 denotes an anti-vibration device mounted on the mounting table 9.

[Problems to be solved by the invention]

However, in the conventional vibration isolator 8 described above with reference to FIG. 12, the vibration of the specific frequency selected in advance can be attenuated by the provision of the dynamic vibration absorber 12, but the micro vibration environment is complicated. In some cases, the target micro-vibration component is not properly absorbed, and a part with a low vibration insulation level may remain, and its detection is often found for the first time in a field test. Adjusting the frequency was very cumbersome.

Further, in the vibration damping device 8, the dynamic vibration absorber 12 needs to be attached to the lowest point of the vibration damping system so that its performance can be exhibited most effectively. In other words, in the structure of FIG.
It is desirable to place 12 at the lowest point of the mounting table 9 as shown in the figure, but in such a case, the height of the mounting table 9 is increased by the space of the dynamic vibration absorber 12, and when the weight is the same. However, the center of gravity G ₂ of the mounting table 9, that is, the overall combined center of gravity G ₁₂ is also increased,
There is a problem that the vibration mode becomes unstable and the influence of locking increases.

In this case, the anti-vibration device 8 is installed by digging below the floor,
Although the height of the mounting table 9 can be lowered to lower the position of the composite center of gravity, there is a problem such as an increase in cost due to the excavation work as described above.

The present invention has been made in view of the above-described problems of the related art, and a first problem to be solved is that the center of gravity of the vibration isolator can be easily adjusted without increasing the weight of the set mounting table. In addition to reducing the size, it is possible to eliminate the size increase due to the addition of the dynamic vibration absorber. A second problem is to solve the first problem and to provide a dynamic vibration absorber at a position where the vibration absorbing effect is highest, and to simultaneously perform three-dimensional vibration absorption by a single dynamic vibration absorber. further,
A third problem is to solve the second problem and make it possible to easily adjust the vibration absorption frequency of the dynamic vibration absorber.

[Means for solving the problem]

In order to solve the first problem, in the invention according to claim (1), the mounting table is attached to a mounting table on which the anti-vibration device is mounted and a vibration isolation system in which the mounting table is supported via a spring mechanism and a damping mechanism. In a vibration isolator provided with a dynamic vibration absorber that reduces vibration of 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 connecting columns, The dynamic vibration absorber is disposed in a space between the upper and lower stages.

In order to solve the second problem, in the invention according to claim (2), a vibration isolation system in which a mounting table on which an anti-vibration device is mounted is supported via a spring mechanism and a damping mechanism; In a vibration damping device provided with a dynamic vibration absorber for reducing vibration of 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 connecting columns. The dynamic vibration absorber, a mass, a rod for suspending the mass from the upper stage or a portion rigidly connected to the upper stage, a spring interposed between the rod and the mass, A damper interposed between the mass body and the lower stage or a portion rigidly connected to the lower stage.

Further, in order to solve the third problem, the dynamic vibration absorber of the invention according to (3) of the inventions according to claims (3) to (5) is configured so that at least the mass of the mass body can be increased or decreased. And Further, the dynamic vibration absorber described in (4) is configured so that at least a spring constant of the spring can be adjusted. Furthermore, the dynamic vibration absorber described in (5) is at least
A hanging distance variable mechanism capable of changing a hanging distance of the rod with respect to the mass body is provided.

[Action]

In the invention described in claim (1), since the mounting table is divided into the upper stage and the lower stage by the connecting column, even when the set weight of the entire mounting table is the same, the center of mass of the upper and lower stages is lowered, and Even if the additional mass is not increased to increase the size, the moment of inertia substantially increases.
At this time, by changing the specific gravity, the weight of the lower stage can be formed larger than the weight of the upper stage. In this case, the center of gravity of the entire mounting table can be efficiently lowered with a smaller occupied space, and the moment of inertia can be set large. . As a result, a large inertia effect is exhibited, and the influence of rocking vibration can be reduced. Also, since a space is formed between the upper and lower stages, this space can be used for arranging the dynamic vibration absorber, compared with a case where the dynamic vibration absorber is simply arranged below the single-structured mounting table. Enlargement of the whole vibration damping device can be avoided.

According to the invention described in claim (2), in addition to the above-described effects, in the dynamic vibration absorber, the mass body is vertically supported via a damper and a spring, and is horizontally supported via a damper and a rod. Since it is supported in a vertical direction, it has a natural frequency in each of the vertical direction and the horizontal direction. This makes it possible to simultaneously obtain a three-dimensional vibration damping effect while using a single dynamic vibration absorber, and to obtain vibration isolation performance to which the vibration absorbing characteristics of the dynamic vibration absorber are added as a whole of the vibration isolator. That is, significant space saving can be achieved as compared with the case where the dynamic vibration absorbers are individually installed in each direction. Also, since this dynamic vibration absorber is connected to the upper stage rigidly connected to the lower stage, it is substantially attached to the lowest point of the main vibration isolation system,
Its vibration absorption effect is the highest.

Further, in the inventions according to claims (3) to (5),
In the device described in (3), at least the mass of the mass body can be increased or decreased, so that the natural frequency in the vertical direction and the horizontal direction of the dynamic vibration absorber can be adjusted. In the description of (4),
At least, the vertical natural frequency of the dynamic vibration absorber can be adjusted by changing the spring constant of the spring. further,
In (5), the horizontal natural frequency of the dynamic vibration absorber can be adjusted by changing at least the hanging distance of the rod with respect to the mass body by the hanging distance variable mechanism.

〔Example〕

Next, an embodiment of the present invention will be described with reference to FIGS.

In the figure, reference numeral 20 denotes a vibration isolator, and reference numeral 22 denotes a vibration isolator 20.
An anti-vibration device such as an electron microscope mounted above. Anti-vibration device
Reference numeral 20 denotes a mounting table 24 on which the anti-vibration device 22 is mounted, spring mechanisms 26, ..., 26 for supporting the mounting table 24 at a plurality of support points, and a mounting table 24.
A primary system comprising oil dampers 28,..., 28 as damping mechanisms installed at a plurality of points between the floor and the floor, and a dynamic vibration absorber 30 as a secondary system attached to the mounting table 24. I have.

Each spring mechanism 26 has a structure in which a multi-layer laminated rubber 32 having a horizontal spring function and a diaphragm type air spring 34 having a vertical spring function are connected in series. Mounting table
24 is divided into an upper stage 24a and a lower stage 24b,
The lower stage 24b is rigidly connected to the upper stage 24a by a plurality of connecting columns 24c,..., 24c and hangs down, so that a space of a predetermined height is formed between the two stages 24a, 24b. In the present embodiment, both stages 24a, 24b and the coupling column 24c,
, 24c ensure a predetermined weight, but a light and highly rigid member is used for the upper stage 24a, and a heavy material is used for the lower stage 24b. In the center of the lower stage 24b, there is formed a punched hole A having a rectangular shape as viewed from above, into which a part of a dynamic vibration absorber 30 described later can be loosely inserted.

Each oil damper 28 is provided on the floor and the lower stage 24.
It is provided so as to generate the damping force in the horizontal and vertical directions between b.

The dynamic vibration absorber 30 is provided in a space between the two stages 24a and 24b, as shown in the figure, and has a fixed mass body 30 located at the lowermost end.
a and the adjusting mass 30b placed on this fixed mass 30a
And a plurality of oil dampers 3 connected to the fixed mass body 30a
0c,..., 30c, and a plurality of suspension rods 30d,.
…, 30e and suspension rod clamp (variable suspension distance mechanism)
30f, ..., 30f.

More specifically, the mass body 30a has a fixed mass, is arranged in the punched hole A of the lower stage 24b in a loosely inserted state, and the adjustment mass body 30b is fixedly mounted on the mass body 30a so that the mass can be adjusted. You. The upper end of each suspension rod 30d is attached to a predetermined position on the lower surface of the upper stage 24a, and the lower end is attached to the fixed mass body 30a via a spring 30e in series. One end of each suspension rod clamp 30f is attached to the adjacent connecting column 24c so as to be vertically movable, and the other end is vertically movable at an intermediate position of the suspension rod 30d. Is rigidly connected to the mounting table 24. Furthermore, each oil damper 30c is interposed between the fixed mass body 30a and the lower stage 24b to generate a damping force in the horizontal and vertical directions, thereby making it possible to adjust the vibration damping effect of the dynamic vibration absorber 30. ing.

That is, the dynamic vibration absorber 30 of the present embodiment is supported in the vertical (up and down) direction by a plurality of springs 30e and an oil damper 30c, and is supported in the horizontal direction by a plurality of rods 30d and an oil damper 30c having a spring function. Even though it is a single vibration absorber, it constitutes a vibration absorbing system in three dimensions.

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

The dynamic vibration absorber 30 (secondary system) has a function of adding an anti-resonance point and a resonance point to the attached vibration isolation system (primary system).
Therefore, in the present embodiment, the frequency of the anti-resonance point is matched with the frequency of the specific vibration input (cases 2 and 3 described later), or the anti-resonance point is matched with the resonance point of the primary vibration isolation system ( This is intended to improve the vibration insulation performance.

The anti-resonance point of the secondary system that contributes to the improvement of the insulation performance is:
The resonance point frequency of the secondary system, which is determined by the attenuation ratio and the mass ratio.

Now, assuming the mass M _{1 of the} primary system, the spring constant K ₁ , and the damping constant C ₁ ,
The secondary system mass M ₂ , spring constant K ₂ , and damping constant C ₂ are used. Also,
The natural frequency of the primary system is ω ₁ = (K ₁ / M ₁ ) ^1/2 , and the natural frequency of the secondary system is ω ₂ = (K ₂ / M ₂ ) ^1/2 , and the primary system and the secondary system減 衰₁ , ζ ₂ , mass ratio μ, ratio u ₁ , u ₂ between the natural frequency and input frequency of the primary and secondary systems, and the complex variables A and B of the primary and secondary systems Ζ ₁ = C ₁ / (2M ₁ ω ₁ ) ζ ₂ = C ₂ / (2M ₂ ω ₂ ) μ = M ₂ / M ₁ u ₁ = ω / ω ₁ , u ₂ = ω / ω ₂ A = _{1 + j2ζ 1 u 1 B =} 1 + j2ζ 2 u 2 and putting the primary system, the secondary system vibration transmissibility tau ₁ alone, tau
₂ is It is represented by Then, the secondary system of the transmissibility τ ₂ (dynamic vibration absorber)
When mounting the primary system transmission rate τ _1, τ ₁ is affected by tau _2. The vibration transmissibility τ ₁ ′ of the primary system affected by the It is represented by

By substituting the specific numerical values of the various parameters in the vertical direction shown in Table A below into the equation of the vibration transmissibility τ ₁ ′ and simulating, the characteristics shown in FIG. 3A are obtained. Similarly, Table B below
When the simulation is performed by substituting specific numerical values of the respective parameters in the horizontal direction shown in FIG. 3, the characteristics shown in FIG. 3B are obtained.

3 (a) and 3 (b), the horizontal axis represents the frequency of the disturbance vibration input, and the vertical axis τ ₁ ′ represents the vibration transmissibility represented by the above equation (1).

First, in each of Cases 1 to 4 in Table A, the vertical numerical value of the primary system is set to the natural frequency F ₁ = 1 Hz, and the natural frequency F _{2 of the} secondary system is set for this fixed primary system. And F ₂ = 1H
z (Case 1) and 2.5 Hz (Cases 2 and 3) are set. In Case 2 and 3, the natural frequency F ₂ are identical value is set larger at the attenuation constant of the case 3. Case 4 is a case where a secondary system is not added. And the third
As can be seen from the simulation results in FIG. 7A, in case 1, the transmissivity in the vicinity of a disturbance frequency of 1 Hz where the vibration transmissibility of the primary system deteriorates is improved, and in cases 2 and 3, the damping constant thereof is reduced. The transmission rate is improved in the 2.5 Hz region according to the above. That is, cases 2 and 3 are effective when the disturbance frequency to be absorbed is 2.5 Hz.

On the other hand, in the cases 1 and 2 of Table B, horizontal numbers of the primary system is set to the natural frequency F ₁ = 0.5 Hz, the natural frequency F ₂ of the secondary system with respect to the primary system, F ₂ = 0.8Hz
(Case 1). Case 2 is a case where a secondary system is not added.

Here, in order to see the improvement rate at u ₂ = 1, τ ₁ ′
/ Τ ₁ Here, assuming that the vibration input frequency is high and u ₁ is large, It is expressed as

According to this, in a vibration isolator with a secondary system added,
Increase the degree of improvement for vibration input of a specific frequency (ie,
The "τ _{1 '/} τ _1' to large) is understood that there may be small damping factor zeta ₂ secondary system, damping factor zeta ₂
Is smaller, the amplification factor of the adjacent area is also increased. Therefore, the attenuation rate is adjusted to す る₂ which satisfies both conditions appropriately.
Further, in order to have a certain width in the specific frequency to be improved, the mass ratio μ may be increased.

By the way, the acceleration spectrum (peak hold spectrum) on the floor where the vibration isolator 20 is installed was measured in order to set the specifications of the vibration isolator 20 in the present embodiment. The characteristics of FIGS. (A) to (c) were obtained. From this characteristic, 2.5Hz in the vertical (Z-axis) direction,
It has been found that there is a large micro-vibration at 0.8 Hz in the horizontal (X, Y-axis) direction, which is difficult to remove with the conventional vibration isolator. For this reason, the natural frequency of the primary system is set to 0.5 Hz in the horizontal direction and 0.9 Hz in the vertical direction, and 0.8 Hz in the horizontal direction by the dynamic vibration absorber 30.
The z, 2.5Hz micro vibration in the vertical direction is suppressed.

Therefore, the specifications of the primary system and the secondary system in the vertical direction are set to the same values as those of Case 2 in Table A described above. The specifications of the primary system and the secondary system in the horizontal direction were the same as those in case 1 in Table B described above.

Consider the vibration isolation performance of the entire vibration isolator 20 by setting the numerical values. Based on the above equation (1), the vibration transmissibility τ ₁ ′
Is obtained, and the vertical vibration isolation level (= 20 · logτ)
The frequency and phase characteristics of ₁ ') are shown in FIGS.
Are obtained. In other words, vertical vibration input 2.
An anti-resonance point of the dynamic vibration absorber 30 is added at a point of 5 Hz, and a valley (about −21 dB) having a low vibration isolation level is formed. On the other hand, the horizontal vibration transmissibility τ ₁ ′ is obtained based on the above equation (1), and the frequency and phase characteristics of the horizontal vibration isolation level are as shown in FIGS. 6 (a) and 6 (b). Can be
In other words, at the point where the horizontal vibration input is 0.8 Hz, the dynamic vibration absorber 30
Is added, and the valley with low vibration isolation level (about-
5dB) is formed.

 Next, the operation and effect of this embodiment will be described.

When the vibration having the acceleration characteristic shown in FIG. 4 described above is input from the installation floor to the vibration isolator 20, the vibration isolator 20 exerts the insulation performance shown in FIGS. That is, the vertical vibration component shown in FIG. 4 (c) is generated by the mounting table 24, each spring mechanism 26, and each oil damper 28 of the vibration isolation system (primary system).
Due to the damping effect of the above, the frequency is greatly reduced mainly on the high frequency side after about 1 Hz (see the area of the negative insulation level in FIG. 5), and the anti-resonance point added by the dynamic vibration absorber 30 (secondary system) is absorbed. The effect reduces the 2.5 Hz component intensively.

On the other hand, the horizontal component shown in FIGS. 4 (a) and 4 (b) is about 0.6 Hz due to the damping action of the mounting table 24 of the vibration isolation system (primary system), each spring mechanism 26, and each oil damper 28. After that, the frequency decreases around the high-frequency side (see the area of the negative insulation level in FIG. 6), and the 0.8 Hz component concentrates due to the anti-resonant vibration absorbing action added by the dynamic vibration absorber 30 (secondary system). Decrease. As a result, a high level of vibration isolation performance including vibration components of a specific frequency (2.5 Hz in the vertical direction and 0.8 Hz in the horizontal direction) that cannot be sufficiently removed by the vibration isolation system alone is exhibited.

Thus, the vertical acceleration spectrum (peak hold spectrum) on the upper stage 24a has the characteristics shown in FIG. 7C, and the horizontal acceleration spectrum (peak hold spectrum) has the characteristics shown in FIGS. 7A and 7B. ). As described above, even if the vibrations shown in FIGS. 4A to 4C are input, the vibration characteristics on the upper stage 24a are as shown in FIGS. 7A to 7C, respectively.
Good vibration isolation in the use area is achieved centering on the vibration of the target frequency.

In this embodiment, the vibration is removed as described above.
Since the lower stage 24b 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, the position of the center of gravity can be efficiently lowered in a smaller space than when the specific gravity of the upper and lower stages is the same. Since the moment can be set larger than before, the influence of rocking vibration can be significantly reduced. In addition, the dynamic vibration absorber 30 can be installed by utilizing the space between the two stages 24a and 24b, and it is possible to prevent the entire vibration isolator from being enlarged as compared with the conventional case where the dynamic vibration absorber 30 is provided below the mounting table. The position of the center of gravity of the mounting table 24 does not rise. Further, the dynamic vibration absorber 30 is substantially a mounting table.
Because it is connected to the lower part of 24, it is the most effective installation position for the mode you want to control, and its vibration absorbing effect is most effectively exhibited. Therefore, three-dimensional vibration and rocking vibration transmitted to the anti-vibration device 22 are minimized, and high-precision work in the device 22 can be performed.

On the other hand, the dynamic vibration absorber 30 has three directions (X, Y,
Z) damping can be performed simultaneously. Also, each oil damper 30c
By changing the characteristics of the above, the damping effect can be adjusted. As a result, the installation space can be reduced as compared with the conventional case where the dynamic vibration absorber is individually provided in each direction, and the large mass ratio is achieved by integrating the mass bodies conventionally installed separately in each direction. Can be obtained, which is advantageous in terms of the vibration absorbing effect of the dynamic vibration absorber.

Also, the dynamic vibration absorber 30 adjusts the natural frequency F _{2 in the} vertical direction and the horizontal direction by adjusting the mass of the adjusting mass body 30b based on the above-mentioned equation of ω ₂ = (K ₂ / M ₂ ) ^1/2. can be adjusted by adjusting the clamping position against the suspending rod 30d of more suspending rod clamp 30f, it changes the horizontal direction of the spring constant K _2, thereby the natural frequency of the horizontal
F ₂ can be adjusted. Therefore, at the installation site in response to the test results of the vibration isolation device 20, the vertical natural frequency is adjusted by adjusting the mass, and then the horizontal natural frequency is adjusted by changing the clamp position. There is an advantage that fine adjustment can be easily performed.

Further, in the configuration of the present embodiment, the dynamic vibration absorber 30 can be used to reduce the amplification factor near the natural frequency of the primary vibration isolation system. In this case, the primary vibration damping system to reduce the zeta _1, there is a merit that it is possible to suppress the amplification at resonance while improving insulation properties at high frequencies.
In this case, ω ₂ and ζ ₂ of the dynamic vibration absorber 30 can be optimized under the following conditions using μ as a parameter.

ω ₂ = 1 / (1 + μ) ζ ₂ = ｛3μ / 8 (1 + μ) ³ ｝ ^1/2 The maximum amplitude magnification at this time is It is. Here, X _ST is the maximum amplitude in the absence of the dynamic vibration absorber.

In the above embodiment, the upper and lower stages 24a,
The specific gravity of 24b is made larger in the lower part, but even if the specific gravity is the same, the effect of lowering the center of mass of the rigid system, that is, the center of gravity, by the distance is achieved by using a two-stage structure. And the effect of rocking vibration can be reduced.

On the other hand, the above-described embodiment is modified as shown in FIGS. 8 and 9 (the same reference numerals are used for the same configuration as the above-described embodiment).
Can be implemented. 8, the lower stage 24b of the mounting table 24 described in the above embodiment is set at a fixed position, whereas the lower stage 24b of FIG. It is movable up and down along each connecting column 24c. This allows
The position of the center of gravity can be adjusted, and the position _R0 of the rotation center shown in FIG.

The allowable vibration value of the anti-vibration device 22 is given for the installation floor of the device (in this case, the mounting table 24).
From the point of view of the internal structure of 22, the site where the vibration conditions are the most severe is not necessarily the installation floor. For example, if the anti-vibration device 22 is an electron microscope, the position of the sample table in the device is the most sensitive part to vibration. Considering this, in the modification shown in FIG. 8, the position of the center of rotation _R0 is controlled by moving the lower stage 24b up and down, and the most sensitive part to vibration is set in the rigid body mode of the vibration isolation system. It can be brought to a node point, thereby minimizing the effect of rotational vibration on the device 22. As described above, in the example of FIG. 8, the rotational vibration can be suppressed by focusing on the control of the position of the center of gravity, and the rotational vibration can be avoided by focusing on the control of the rotational center position. In addition, there is an advantage that the range of choices of the vibration isolation method is expanded, and the vibration environment and the required characteristics of the anti-vibration device can be flexibly dealt with.

On the other hand, in the modification shown in FIG. 9, the upper and lower stages 24a and 24b and the connecting column 24c shown in FIG. 1 are combined into a single mounting table 24, which is used as a spring mechanism 26, …, 26
, 28, and the hanging position of the suspension rod 30d of the dynamic vibration absorber 30 and the mounting position of the suspension rod clamp 30f are the lower surface and the side surface of the mounting table 24 as shown in the figure.

In such a configuration, the position of the center of gravity and the position of the rotation center are fixed, but the advantage of the dynamic vibration absorber 30 itself can be enjoyed as it is, such as three-dimensional simultaneous vibration absorption by a single dynamic vibration absorber 30. Therefore, depending on the weight of the anti-vibration device 22 and the height of the center of gravity, the configuration shown in FIG. 9 can be simplified and a high-level vibration can be removed.

In addition, in the above-described embodiment and modified examples, as an example of the configuration for adjusting the natural frequency of the dynamic vibration absorber, an example in which the rigid connection point of the mass and the suspension rod clamp is changed has been described, but the present invention is not necessarily limited to such a configuration. Without limitation, for example, only adjustment of the mass body may be performed as necessary, or only adjustment of the rigid connection point of the suspension rod clamp may be performed.

Further, a configuration may be employed in which the spring constant of the spring having a vertical spring function can be changed as shown in FIG. The configuration in the figure is a leaf spring that can be displaced vertically.
40, between the lower end of the suspension rod 30d and the lower surface of the fixed mass body 30a, and the position of attachment to the mass body 30a can be adjusted so as not to compete with the same suspension rod clamp as in FIG. It was done. Thereby, the leaf spring 40 functions as an auxiliary spring capable of changing the spring constant with respect to the coil spring 30e, and the vertical spring constant can be changed by adjusting the distance l between the fulcrums of the leaf spring 40, and the natural frequency in the vertical direction can be reduced. Can be adjusted.

The means for adjusting the natural frequency in the vertical direction and the horizontal direction as described above may be appropriately combined as needed.

Furthermore, the damper of the dynamic vibration absorber in the above embodiment
Although 30c is mounted between the primary system and the lower stage 24b, it may be, for example, the upper stage 24a or the coupling column 24c, depending on the structure of the entire vibration isolator. On the other hand, the mounting position of the suspension rod clamp 30f with respect to the primary system is not limited to the connecting column 24c as described in the embodiment.For example, when the suspension rod 30d is suspended from an arm rigidly connected to the connecting column 24c. The upper stage 24
a, It may be attached to the lower stage 24b.

Still further, the suspension distance variable mechanism of the dynamic vibration absorber according to the invention described in claim (5) is not limited to the one described in the above-described embodiment and the modified example. For example, the position of the suspension rod clamp 30f is fixed. Alternatively, with the clamp 30f removed, the support position of the mass bodies 30a, 30b may be raised and lowered, and the suspension distance of the suspension rod 30d with respect to the mass bodies 30a, 30b may be changed. Thus, in terms of the adjustment of the spring constant in the horizontal direction, this is equivalent to the above, and the degree of freedom in design is improved.

Furthermore, the dynamic vibration absorber in the above embodiment and the modified example has a structure capable of simultaneously absorbing three-dimensional vibration with a single vibration absorber.
In the invention described in claim (1), a dynamic vibration absorber capable of absorbing vibration only in the vertical direction or the horizontal direction may be used.

〔The invention's effect〕

As described above, according to the invention described 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 to each other through a gap in the vertical direction. The dynamic vibration absorber is installed in the, and the position of the center of gravity can be effectively lowered to increase the moment of inertia without making the mounting table unnecessarily heavy, and the effect of rocking vibration is suppressed by the large inertia effect. On the other hand, the specific gravity can be changed in the upper and lower stages, for example, and the specific gravity of the lower stage is made larger than that of the upper stage. This, combined with the ability to install a dynamic vibration absorber in the space between stages, has the effect of achieving significant space savings for the entire device. .

Further, according to 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 via a vertical gap.
Install a single dynamic vibration absorber in the gap, this dynamic vibration absorber,
The invention according to claim 1, wherein the rigid system including the upper stage is connected to the rigid system including the lower stage via a rod and a spring, and the rigid system including the lower stage is connected to the rigid system via a damper. In addition to obtaining the same effect,
Since the dynamic vibration absorber is supported via a spring component and a damping component in each of the vertical direction and the horizontal direction, and can simultaneously perform three-dimensional vibration suppression, it is significantly different from the case where the dynamic vibration absorber is individually set in the three directions. In addition to the space saving, the dynamic vibration absorber is installed substantially below the mounting table, so that the vibration absorbing performance is exhibited most effectively.

Further, according to the inventions set forth in claims (3) to (5), in addition to the effects described in claim (2) above, the mass of the mass body, the spring constant of the spring, and the suspension distance variable mechanism are changed. The natural frequency in the vertical direction and the horizontal direction can be adjusted by one or any combination of the changes in the hanging distance of the rod, so that fine adjustment on site can be easily performed.

[Brief description of the drawings]

1 to 7 are views showing an embodiment of the present invention, and FIG. 1 is a partially cut-away schematic configuration view showing the entire configuration.
FIG. 2 is a vibration control model diagram according to the configuration example of FIG. 1, FIG. 3 (a) is a vertical vibration transmissibility characteristic diagram based on the model configuration of FIG. 2, and FIG. FIG. 4 (a) to FIG. 4 (c) are diagrams showing horizontal vibration transmissibility characteristics based on the model configuration shown in FIG.
Fig. 5 (a) and Fig. 5 (b) respectively show the frequency characteristics of the vibration insulation level and phase in the vertical direction, and Figs. 6 (a) and 6 (b) respectively show the acceleration spectrum diagrams in the horizontal and vertical directions on the installation floor. Frequency characteristics diagram of horizontal vibration isolation level and phase,
7 (a) to 7 (c) are horizontal and vertical acceleration spectrum diagrams on the mounting table, respectively. FIGS. 8 and 9 are schematic diagrams showing modified examples, respectively. FIG. 10 is a vertical diagram. FIG. 11 is a partial configuration diagram of a spring mechanism capable of changing a spring constant,
FIG. 12 is a schematic configuration diagram showing a conventional example. The main symbols in the figure are 20: anti-vibration device, 22: anti-vibration device,
24 mounting table, 24a upper stage, 24b lower stage, 24c coupling column, 26 spring mechanism, 28 oil damper (damping mechanism), 30 dynamic absorber, 30a Fixed mass, 30b Adjustment mass, 30c Oil damper (damper), 30d Hanging rod (rod), 30e
Spring, 30f: hanging rod clamp (variable hanging distance mechanism), 40: leaf spring.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masashi Yasuda 5-17-43 Minamitsukaguchi-cho, Amagasaki-shi, Hyogo Patent Equipment Co., Ltd. (58) Field surveyed (Int. Cl. ⁷ , DB name) F16F 15 / 02 E04H 9/02 341

Claims (5)

(57) [Claims] An anti-vibration system comprising a mounting table on which an anti-vibration device is mounted via a spring mechanism and a damping mechanism, and a dynamic vibration absorber attached to the mounting table to reduce vibration of a specific frequency. In the vibration isolator, the mounting table is divided into an upper stage and a lower stage, and the upper and lower stages are rigidly connected via connecting columns, and the dynamic vibration absorber is arranged in a space between the upper and lower stages. An anti-vibration device characterized by being provided. 2. A vibration damping system comprising a mounting table on which a vibration-reducing device is mounted via a spring mechanism and a damping mechanism, and a dynamic vibration absorber attached to the mounting table for reducing vibration of a specific frequency. In the vibration damping device, the mounting table is divided into an upper stage and a lower stage, and the upper and lower stages are rigidly connected via connecting columns. The dynamic vibration absorber includes a mass body and the mass body. A rod suspended from the upper stage or a part rigidly connected to the upper stage, a spring interposed between the rod and the mass body, and a part rigidly connected to the mass body and the lower stage or the lower stage And a damper interposed between the vibration damper and the damper. 3. The vibration damping device according to claim 2, wherein the dynamic vibration absorber is configured to be capable of increasing and decreasing at least the mass of the mass body. 4. The vibration damping device according to claim 2, wherein the dynamic vibration absorber is configured to change at least a spring constant of the spring. 5. The vibration damping device according to claim 2, wherein the dynamic vibration absorber includes at least a hanging distance variable mechanism capable of changing a hanging distance of the rod with respect to the mass body.