JP2006214527A - Damping device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a damping device capable of simply and accurately adjusting natural frequencies at an installed site. <P>SOLUTION: The damping device has a weight 12, a main spring 16 which is arranged between the weight 12 and a frequency reducing target 14 and supports the weight 12, and an auxiliary spring 18 arranged to bring into contact with a side face of the weight 12. The auxiliary spring 18 gives an extra load onto the weight 12. The weight 12 has a natural frequency almost same with the natural frequency of the frequency reducing target 14 whose frequency is to be controlled, and a steel material is used for the weight 12 which generates a resonant phenomenon. For example, there are a floor and a beam of a concrete building as the frequency reducing target 14. A coil spring 44 is preferable as the main spring 16 and auxiliary spring 18, but a rubber elastomer can be also applicable as the main spring 16 and auxiliary spring 18. Auxiliary compression and auxiliary tension are also included as the auxiliary load given to the weight 12 by the auxiliary spring 18. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vibration damping device that reduces vibrations of, for example, floors and beams of a building using the principle of dynamic vibration absorption.

  Conventionally, in order to reduce floor vibration of a building, it is known to install a floor vibration control device including a dynamic vibration absorber under the floor (see Patent Document 1). This floor vibration control device has an arm attached to a beam member of a building via a spring member, and a weight and a damper attached to this arm. When the floor vibrates, the weight resonates to reduce floor vibration. It is. However, this device does not change the natural frequency of the device unless the spring member and weight are replaced.

  When using a dynamic vibration absorber to reduce floor vibration of a building, it is necessary to make the natural frequency of the building that is the object of vibration reduction equal to the natural frequency of the dynamic vibration absorber. However, there are many cases where the natural frequency of the building is different from the actual value after installation or the actual value after installation. There are times when you have to do.

As a method of changing the natural frequency of the dynamic vibration absorber, there is a method of changing the spring constant of the spring member that supports the weight of the dynamic vibration absorber (see Patent Document 2). In this method, both sides of the weight are supported by a spring member and an air spring, and the spring constant is adjusted by the air pressure of the air spring.
JP-A-6-257321 Japanese Utility Model Publication No. 5-42789 Editor Spring Technology Study Group, “Spring Design”, 2nd edition, published on January 20, 1985, 3rd edition, p. 72-73

By the way, the above technique has the following problems to be solved.
The above-described method of adjusting the spring constant by the air pressure of the air spring to change the natural frequency of the dynamic vibration absorber has problems such as a complicated structure and maintenance of air or the like. As a method of changing the natural frequency of the dynamic vibration absorber, there is a method of changing the mass of the weight of the dynamic vibration absorber. However, in this case, it is necessary to prepare a number of weights having different masses in advance, and the natural frequency cannot be adjusted steplessly, and is stepwise according to the mass of the prepared weights.
The present invention has been made paying attention to the above points, and an object of the present invention is to provide a vibration damping device capable of easily and accurately changing the natural frequency at the installation site.

In each embodiment of the present invention, the above-described problems are solved by the following configurations.
<Configuration 1>
A weight, a main spring disposed between the weight and the vibration reduction object, and supporting the weight; and an auxiliary spring disposed so as to contact a side surface of the weight. A vibration damping device for adjusting a natural frequency by variably adding a load.

  The spring constant in the shear direction of the spring changes due to the deflection (compression or tension) in the direction perpendicular to the shear stress of the spring. Therefore, it is possible to easily and accurately change the natural frequency of the device at the installation site by providing an auxiliary spring on the side of the vibration direction of the weight and adjusting the preload applied to the auxiliary spring while the auxiliary spring is deformed in the shear direction. And can respond immediately to changes in the vibration mode of the object to be reduced. That is, an optimum natural frequency corresponding to the vibration mode of the object to be reduced in vibration can be obtained by adding a suitable preload to the auxiliary spring at the installation site to change the spring constant in the shear direction of the auxiliary spring. Further, the natural frequency can be adjusted steplessly, which is convenient for fine adjustment at the installation site.

<Configuration 2>
The vibration damping device according to Configuration 1, wherein a base plate having a bottom portion on which the main spring is placed and a side portion that holds one end of the auxiliary spring is provided.

  By using the base plate, the main spring and the auxiliary spring can be attached at predetermined positions.

<Configuration 3>
In the vibration damping device according to Configuration 1 or 2, in a cavity provided in a central portion of the weight, a piston portion locked to the weight, and provided on the vibration reduction object side, the piston portion and A vibration damping device comprising a damper having a cylinder portion for storing a viscous fluid.

  The vibration damping effect can be increased by the damper.

<Configuration 4>
4. The vibration damping device according to claim 1, wherein the main spring is housed in a through-hole provided in the vertical direction on the weight, and a lid having an upper end detachably provided in the through-hole. A vibration control device characterized by being held by the body.

  By removing the lid, the main spring can be easily replaced.

<Configuration 5>
5. The vibration damping device according to any one of configurations 2 to 4, wherein the auxiliary spring includes an adjustment bolt screwed into a side portion of the base plate and a coil spring connected to one end of the adjustment bolt. A vibration damping device characterized by being.

  The specific form of the means to variably add the preliminary load in an auxiliary spring is shown. By rotating the adjusting bolt, the preload force of the coil spring against the weight can be easily adjusted. The auxiliary spring restores the weight displacement.

<Configuration 6>
6. The vibration damping device according to any one of Structures 3 to 5, wherein the piston portion is eccentric to the axis of the cylinder portion and is fitted in the cylinder portion in a rotatable state. Damping device.

  Since the cross-sectional shape of the flow path of the viscous fluid is changed by displacing the piston portion at an arbitrary angle with respect to the cylinder, the damping constant can be changed. Therefore, even when the vibration frequency is slightly deviated from the natural frequency of the object to be reduced, the desired vibration damping effect can be obtained by adjusting the mounting angle of the piston portion.

<Configuration 7>
7. The vibration damping device according to any one of Structures 3 to 6, wherein a ring-shaped seal is detachably provided in a gap between the upper portion of the cylinder portion and the piston portion.

  It is possible to prevent leakage of viscous fluid in the cylinder during transportation.

<Configuration 8>
8. The vibration damping device according to claim 1, wherein a concave portion is provided on an upper surface of the weight, and a plurality of weights for fine adjustment are accommodated in the concave portion.

  The natural frequency can be adjusted stepwise by appropriately adjusting the number of weights for fine adjustment. By using together with the stepless natural frequency adjustment by the auxiliary spring, the stepless natural frequency can be adjusted over a wide range.

<Configuration 9>
9. The vibration damping device according to claim 1, wherein the weight has a flat plate shape and is supported by a plurality of the main springs arranged at a predetermined interval. .

  By making the weight flat, it can be installed in a narrow space such as under the floor.

<Configuration 10>
The vibration damping device according to any one of Configurations 1 to 9, wherein a plurality of the auxiliary springs are respectively provided at a plurality of locations of the weight.

  By adjusting the preload of each of the plurality of auxiliary springs, the spring constant can be finely adjusted, that is, the natural frequency can be finely adjusted.

  The present invention uses the principle of dynamic vibration absorption and obtains the optimum natural frequency corresponding to the vibration mode of the object to be reduced in the installation site. Hereinafter, embodiments of the present invention will be described using specific examples.

1 is a plan view showing the vibration damping device of the first embodiment, FIG. 2 is a side view thereof, FIG. 3 is a cross-sectional view taken along the line AA in FIG. 1, and FIG. 4 (b) is a cross-sectional view taken along the line CC of FIG.
In these drawings, the vibration damping device 10 according to the first embodiment includes a weight 12, six main springs 16 that support the weight 12, and six auxiliary springs that are disposed so as to press the side surfaces of the weight 12. 18 and a base plate 26 on which the weight 12 is placed, and an appropriate preload for the weight 12 is applied to the auxiliary spring 18. This preliminary load includes preliminary compression and preliminary tension.

  The vibration damping device 10 is installed, for example, between a concrete slab (hereinafter referred to as a slab) 14 that is a vibration reduction target and a flooring 15 for a double floor provided above the slab. At this time, a rubber sheet 27 is interposed to prevent the slab 14 and the base plate 26 from rattling. For example, the distance between the slab 14 and the flooring 15 is about 60 mm.

  The weight 12 is made of steel and is formed in a substantially flat plate shape, and is supported by six main springs 16 arranged in a circle on the base plate 26 at a predetermined interval. The base plate 26 has a bottom portion 22 on which the main spring 16 is placed and a side portion 24 that holds one end of the auxiliary spring 18, and has a shape in which both side edges of the flat plate are bent.

  The six main springs 16 are coil springs, and are accommodated in through holes 28 provided in the weights 12 respectively. The through hole 28 is a hole penetrating the weight 12 in the vertical direction, and its upper surface is closed by a lid body 30 provided at the top. The lower end of each main spring 16 is disposed on the base plate 26, and the upper end is pressed by the lid 30. The lid 30 is held by a step 32 provided at the upper part of the through hole 28 and is detachably fixed by screwing. The lid 30 can be easily replaced by removing the main spring 16 from the upper portion of the through hole 28. As the main spring 16, for example, seven types of spring constants of 5.1, 6.4, 10.9, 14.6, 18.7, 23.3, 27 (N / mm) are prepared. Replace as needed. By combining with adjustment of a preload for the auxiliary spring 18 described later, the natural frequency can be adjusted steplessly in a wide range.

  The auxiliary spring 18 includes an adjustment bolt 36 and a coil spring 44 connected to one end of the adjustment bolt 36, and is disposed in a state of being housed in a notch 34 provided on the side surface of the weight 12. The auxiliary spring 18 is attached by screwing an adjusting bolt 36 into a fixing nut 40 disposed on the side portion 24 of the base plate 26, and is fixed by a locking nut 42. A square columnar adjustment knob 38 is fixed to the outer end surface of the adjustment bolt 36. The tip of the coil spring 44 abuts on the side surface in the notch 34 of the weight 12 and is pre-compressed. That is, the preload force on the weight 12 of the coil spring 44 can be adjusted by rotating the adjustment bolt 36 by using the adjustment knob 38 to advance and retract.

  A cavity 46 is provided in the center of the weight 12. A damper 54 is provided in the cavity 46. The damper 54 includes a piston portion 48 that is locked to the weight 12, and a cylinder portion 52 that houses the piston portion 48 and the viscous fluid 50. The piston portion 48 has a flange portion provided at an upper portion thereof fitted into a step portion 47 provided in the cavity 46 of the weight 12 and is detachably fixed by screwing. The cylinder part 52 is formed in a cylindrical shape by a partition wall 53 erected on the base plate 26. Silicone oil is used as the viscous fluid 50.

  In order to prevent leakage of the viscous fluid 50 in the cylinder portion 52 during transportation, a seal 56 formed in a ring shape with a rubber material or the like can be peeled in the gap between the upper portion of the cylinder portion 52 and the piston portion 48. Placed in. The seal 56 is used when the vibration damping device 20 is transported, and is removed when installed on the site.

A recess 58 is provided in the center of the upper surface of the weight 12. A plurality of fine adjustment weights 60 having a mass of 1 kg per sheet are stacked and stored in the recess 58. These fine adjustment weights 60 are fixed by fixing screws 61. The number of fine adjustment weights 60 is determined according to the situation.
It should be noted that holes for attaching eyebolts 62 used during transportation and jack-up taps 64 are provided at appropriate intervals at several positions on the upper surface of the weight 12.

FIG. 5 is a plan view showing a situation in which a plurality of vibration damping devices 10 are installed on a slab 14 of a building.
As shown in FIG. 5, it is preferable that 5-6 units | sets are intensively arrange | positioned at the center part with the largest vibration amplitude on the slab 14, for example. In a double floor adopted for a so-called OA floor in a recent intelligent building or the like, a plurality of panels constituting the double floor are provided with support columns provided on the slab 14 at predetermined intervals (broken line intersections in the figure). Are arranged like a grid (broken line in the figure) and supported by all supporting columns. One vibration damping device 10 is attached to one panel. Therefore, for the convenience of the installation work, the vibration damping device 10 has a size slightly smaller than the size of the panel constituting the double floor.

When installing the damping device 10, the adjustment bolt 36 is rotated to change the spring constant in the shear direction of the auxiliary spring 18 so as to match the vibration mode of the vibration reducing object such as the slab 14, or The optimum natural frequency corresponding to the vibration reduction object such as the slab 14 is set by performing an operation such as appropriately adjusting the number of the fine adjustment weights 60 in the concave portion 58 of the weight 12.
The vibration damping device 10 reduces the vibration of the vibration reducing object such as the slab 14 by the dynamic vibration absorbing action of the weight 12. At this time, vibration is attenuated by the damper 54.

6 is a plan view showing the vibration damping device of the second embodiment, FIG. 7 is a sectional view taken along line BB in FIG. 6, and FIG. 8 is a sectional view taken along line AA in FIG. In these drawings, the same parts as those shown in FIGS. 1 to 3 are denoted by the same reference numerals, and redundant description will be omitted as much as possible.
6 to 8, the vibration damping device 10 </ b> A according to the second embodiment is disposed so as to contact the weight 12 disposed on the base plate 26, the main spring 16 that supports the weight 12, and the side surface of the weight 12. The auxiliary spring 18 and the base plate 26 on which the weight 12 is placed are basically composed of substantially the same components as those of the vibration damping device 10 of the first embodiment. The vibration damping device 10A of the second embodiment is substantially different from the vibration damping device 10 of the first embodiment in the number of main springs 16 installed, the installation position of the fine adjustment weight 60, and the installation position of the piston portion 48. .

  As shown in FIGS. 6 to 8, the eight main springs 16 are respectively housed in through holes 28 provided at eight locations near the outer edge of the weight 12. The fine adjustment weight 60 is provided with recesses 58A at four locations outside the damper 54A provided at the center of the weight 12, and within these recesses 58A, for example, a fine weight of 0.5 kg per sheet is provided. About ten adjustment weights 60 are stored.

9 and 10 are explanatory views showing the damper 54A provided in the center of the weight 12 of the vibration damping device 10A in a plan view.
As shown in FIG. 9, the piston portion 48 of the damper 54 </ b> A is fitted in the cylinder portion 52 in a state where the rotation axis O <b> 1 is eccentric with respect to the center axis O <b> 2 of the cylinder portion 52 and is rotatable. Installed. FIG. 9 shows a state when the piston portion 48 is not rotating.

  FIG. 10 shows a state where the piston portion 48 is rotated 180 degrees. As shown in FIG. 10, the damping constant can be changed by changing the cross-sectional ratio of the flow path of the viscous fluid 50 by attaching the piston portion 48 by rotating it in the range of 0 to 180 degrees around the axis O <b> 1. it can. Therefore, it is possible to adjust to an optimum damping constant even at a position slightly deviating from the natural frequency of the vibration reduction object 14.

  In the present invention, the vibration reduction object can be applied to a structure such as a beam in addition to a building slab. The main spring and the auxiliary spring are not limited to coil springs, and rubber elastic bodies are used. It can also be used.

〔Consideration〕
Here, since the present inventors examined the vibration damping device for slab structures, it demonstrates.

[Configuration of specimen]
As test specimens, five vibration damping devices having the same configuration as that shown in FIGS. 6 to 8 were manufactured under the following conditions.
Vibration reduction target: Primary natural vibration mode of slab Target effective mass: 6000kg
Natural frequency: 10 Hz
Specimen size: width 400mm, length 388mm, height 55mm
Total specimen weight: 225 kg
Specimen weight: 45 kg / unit Specimen vertical clearance: 3 mm
(Assuming that the maximum acceleration of the slab is 0.2 G, the maximum acceleration of the specimen mass is 1.0 G, and the one-side amplitude r when the vertical natural frequency is 10 Hz is r = 2.48, 3 mm Set.)
Spring constant of the main spring: 8.5 N / mm → 68 N / mm (8 pieces)
Spring constant of the auxiliary spring: 24.0 N / mm → 96 N / mm (4 pieces)

[Adjustment of natural frequency of specimen]
(1) Ten pieces of 0.5 kg ring-shaped weights for fine adjustment were installed on the upper part of the test body, and the natural frequency was adjusted by removing the weights one by one.
The fluctuation values of the natural frequency are as follows.
Number of installed weights for fine adjustment Natural frequency (Hz)
10 sheets 9.6
8 sheets 9.7
7 sheets 9.8
5 sheets 9.9
3 sheets 10.0
2 sheets 10.1
0 sheets 10.2

(2) The natural frequency was adjusted by installing auxiliary springs at four locations on the side of the test body and turning the adjustment knob of each auxiliary spring to apply a preload and changing the shear spring constant of the auxiliary spring.
The fluctuation values of the natural frequency are as follows.
Auxiliary spring adjustment (mm) Natural frequency (Hz)
-8 9.6
-6 9.7
-4 9.8
-2 9.9
± 0 10.0
+2 10.1
+4 10.2
+6 10.3
+8 10.4
+10 10.5

By adjusting the natural frequency in the above (1) and (2), the optimum natural frequency can be set according to the installation conditions, and the maximum vibration suppression effect can be obtained.
It is known that the spring constant in the shear direction of a spring changes due to deflection (compression or tension) in a direction perpendicular to the shear stress of the spring (see Non-Patent Document 1). As a reference, FIG. 11 shows the result of calculating the numerical value of each shearing spring constant when the compression allowance (mm) of the auxiliary spring is changed in an example different from that used above. It can be seen from FIG. 11 that the shear spring constant increases as the compression allowance of the auxiliary spring increases.

[Confirmation of vibration suppression effect of specimen]
A one-degree-of-freedom vibration model was constructed from the natural frequency and effective mass of the slab, and the response magnification of the external force excitation system was analyzed. A two-degree-of-freedom vibration model in which the natural frequency, mass, and damping corresponding to the above-mentioned test body were added to the model was constructed, and response analysis of the external force excitation system was performed. These results were compared to confirm the vibration control effect (response magnification reduction effect).
The conditions at this time were as follows.
Effective mass of slab: 6000kg
Natural frequency of slab: 10Hz
Slab damping constant: 0.02 (assumed)
Mass ratio of test specimens (5 units): 3.75%
Effective mass of 5 specimens: 225kg
Optimal natural frequency (f2) of specimen: 9.6 Hz
Optimal damping constant (ζ) of test specimen: 0.11

FIG. 12 shows the response magnification when no vibration damping device is provided. FIG. 13 shows the response magnification when the above-described test body (the vibration damping device of the present invention) is provided.
From the above, the frequency response at the slab natural frequency of 10 Hz is 25 times when the vibration control device is not provided and five times when the vibration control device of the present invention is provided, and the oscillation due to the slab natural vibration is 5 minutes. It is clear that the number can be reduced to 1.

FIG. 3 is a plan view showing the vibration damping device of the first embodiment. The same side view. Sectional drawing which follows the AA line of FIG. (A) is a B arrow line view of FIG. 1, (b) is sectional drawing which follows CC line of FIG. The top view which shows the condition which installed the damping device on the slab of a building. FIG. 6 is a plan view showing a vibration damping device of Embodiment 2. Sectional drawing which follows the BB line of FIG. Sectional drawing which follows the AA line of FIG. Explanatory drawing which shows the damper provided in the damping device of Example 2 planarly. Explanatory drawing which shows the state which rotated the piston part of the damper 180 degree | times. Explanatory drawing which shows the change of each shear spring constant obtained when the compression allowance of an auxiliary spring is changed. Explanatory drawing which shows the response magnification at the time of not providing a damping device. Explanatory drawing which shows the response magnification at the time of providing a damping device.

Explanation of symbols

12 Weight 14 Slab 15 Flooring 16 Main Spring 18 Auxiliary Spring 22 Bottom 24 Side 26 Base Plate 28 Through Hole 30 Lid 34 Notch 36 Adjustment Bolt 38 Adjustment Knob 40 Fixing Nut 42 Loosening Nut 44 Coil Spring 48 Piston 50 Viscosity Fluid 52 Cylinder 54 Damper 60 Fine adjustment weight 62 Eye bolt 64 Jack up tap

Claims (10)

Weight,
A main spring disposed between the weight and the vibration reduction object and supporting the weight;
An auxiliary spring disposed to contact the side surface of the weight,
A vibration damping device that adjusts the natural frequency by variably adding a preliminary load to the auxiliary spring. The vibration damping device according to claim 1,
A vibration damping device comprising a base plate having a bottom portion on which the main spring is placed and a side portion that holds one end of the auxiliary spring. The vibration damping device according to claim 1 or 2,
In the cavity provided in the center of the weight,
A damper comprising: a piston portion locked to the weight; and a damper that is provided on the vibration reduction object side and includes the piston portion and a cylinder portion that stores viscous fluid. The vibration damping device according to any one of claims 1 to 3,
The said main spring is accommodated in the through-hole provided in the up-down direction in the said weight, and the upper end is pressed by the cover body provided in the said through-hole detachably. The vibration damping device according to any one of claims 2 to 4,
The damping device according to claim 1, wherein the auxiliary spring includes an adjustment bolt screwed into a side portion of the base plate, and a coil spring connected to one end of the adjustment bolt. The vibration damping device according to any one of claims 3 to 5,
The vibration damping device according to claim 1, wherein the piston part is fitted in the cylinder part so as to be eccentric and rotatable with respect to an axis of the cylinder part. The vibration damping device according to any one of claims 3 to 6,
A vibration damping device, wherein a ring-shaped seal is detachably provided in a gap between the upper portion of the cylinder portion and the piston portion. The vibration damping device according to any one of claims 1 to 7,
A vibration damping device, wherein a concave portion is provided on an upper surface of the weight, and a plurality of fine adjustment weights are accommodated in the concave portion. The vibration damping device according to any one of claims 1 to 8,
The weight is formed in a flat plate shape and is supported by a plurality of the main springs arranged at a predetermined interval. The vibration damping device according to any one of claims 1 to 9,
A plurality of the auxiliary springs are provided at a plurality of locations of the weight, respectively.

Images