JP2012021650A - Dynamic vibration absorber using rocking - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dynamic vibration absorber using rocking by which specific vibration frequency can be easily adjusted in a wide range in a small and simple structure, which can have attenuation performance without using a damper and can be easily installed in existing structures.SOLUTION: The dynamic vibration absorber using rocking is characterized in that the absorber has an arcuate bottom surface, a position of the center of gravity is located below the center of the curvature radius of the arc, the absorber has an attenuation mechanism for attenuating the rocking vibration of the bottom surface, the attenuation mechanism includes an attenuator arranged between the bottom surface and the setting surface, and the attenuator includes two bags which are arranged between the bottom surface and the setting surface at both ends of the bottom surface respectively and in the inside of which liquid is sealed and a tube communicating and connecting the bags themselves so as to allow the flowing of the liquid between the two bags.

Description

  The present invention relates to a dynamic vibration absorber for suppressing vibrations that occur in a structure due to strong winds, earthquakes, vehicle passages, mechanical vibrations, and the like, and more particularly to a dynamic vibration absorber that uses rocking.

A so-called pendulum type dynamic vibration absorber is well known as a dynamic vibration absorber used for suppressing vibrations generated by an earthquake or the like in a structure such as a high-rise building.
In the pendulum type dynamic vibration absorber, the vibration period of the pendulum is synchronized with the structure, and the vibration of the structure is transmitted to the attenuator via the vibration of the pendulum, thereby exhibiting a vibration damping action.

で表される。（ｇ：重力加速度、Ｌ：振り子の長さ） In such a pendulum dynamic attenuator, the natural frequency f _n is approximately

It is represented by (G: gravitational acceleration, L: pendulum length)

  Therefore, in order to realize a low natural frequency like a high-rise building, it is necessary to make the length of the pendulum very long, and there is a problem that the dynamic vibration absorber becomes large.

  In view of such problems, various mechanical devices for reducing the length of the pendulum have been tried (for example, see Patent Document 1 below), but the structure has a structure in which the natural frequency depends on the length of the pendulum. Since it has not changed, it has been difficult to achieve significant downsizing. In addition, since an additional mechanism is provided, there is a problem that the structure becomes complicated.

In general, the following problems also exist in the dynamic vibration absorber.
First, since a damper for dissipating energy is necessary, the number of parts constituting the device increases, and the device becomes large or complicated.
Furthermore, although it can be installed on a new structure, it is often difficult to install on an existing structure.

JP 2002-188680 A

  The present invention has been made to solve the above-mentioned problems of the prior art, and is capable of easily adjusting the natural frequency in a wide range with a small and simple structure. It is possible to provide a dynamic vibration absorber using a rocking mechanism that can have a damping performance without using a rocking member and can be easily installed on an existing structure.

  The invention according to claim 1 has an arc-shaped bottom surface, the center of gravity is located below the center of curvature radius of the arc, and has a damping mechanism that attenuates rocking vibration of the bottom surface. The mechanism includes an attenuator disposed between the bottom surface and the installation surface, and the attenuator is disposed between the bottom surface and the installation surface at both ends of the bottom surface and has liquid inside. The present invention relates to a dynamic vibration absorber using locking, characterized in that it comprises: two bags with a bag sealed therein and a tube that communicates and connects the bags to allow fluid flow between the two bags .

  The invention according to claim 2 relates to a dynamic vibration absorber using locking according to claim 1, wherein an orifice is provided in the pipe.

  In the invention according to claim 3, a receiving member for receiving the dynamic vibration absorber is fixedly provided outside the dynamic vibration absorber when slippage occurs between the bottom surface and the installation surface and the dynamic vibration absorber moves. 3. A dynamic vibration absorber using locking according to claim 1, wherein an impact absorbing material for absorbing an impact at the time of collision of the dynamic vibration absorber is disposed on a surface of the receiving member. About.

According to the first aspect of the present invention, the natural frequency can be obtained only by changing the relationship between the radius of curvature and the position of the center of gravity by having an arc-shaped bottom surface and the position of the center of gravity being below the center of the radius of curvature of the arc. Can be greatly changed. Therefore, it is possible to easily adjust the natural frequency in a wide range with a small and simple structure. In particular, the natural frequency can be lowered as much as possible by bringing the position of the center of gravity closer to the center of curvature radius. It becomes possible to realize the natural frequency.
In addition, since the damping mechanism that attenuates the rocking vibration of the bottom surface is provided, the vibration of the structure can be transmitted to the damping mechanism via the rocking vibration of the bottom surface, thereby exhibiting a damping action.
Further, since the damping performance can be obtained without using a damper, the apparatus can be downsized and simplified.
Moreover, since performance can be demonstrated only by putting on what wants to suppress a vibration, it can also install easily with respect to the existing structure.

  In addition, since the damping mechanism includes an attenuator disposed between the bottom surface and the installation surface, the energy of the rocking vibration of the bottom surface can be absorbed by the attenuator to attenuate the vibration.

  Further, an attenuator is disposed between the bottom surface and the installation surface at both ends of the bottom surface, and two bags having liquid filled therein, and the flow of liquid between the two bags. By including the tube that connects the bag bodies so as to allow, the energy of the rocking vibration of the bottom surface can be consumed by the fluid flow between the two bag bodies to attenuate the vibration.

  According to the invention which concerns on Claim 2, the fluid resistance in a pipe | tube becomes large and the vibration damping effect can be heightened by providing the orifice in the pipe | tube.

  According to the third aspect of the present invention, the receiving member for receiving the dynamic vibration absorber is fixed to the outside of the dynamic vibration absorber when the dynamic vibration absorber moves when slippage occurs between the bottom surface and the installation surface. The surface of the receiving member is provided with a shock absorber that absorbs the shock when the dynamic vibration absorber collides, so that when the dynamic vibration absorber slides due to a large vibration such as an earthquake, The impact energy generated by receiving this with the receiving member can be dissipated by the impact absorbing material. That is, it is possible to effectively attenuate the vibration by giving the impact absorbing member the role of an impact damper.

It is the schematic which shows the reference form of the dynamic vibration damper which concerns on this invention. It is explanatory drawing of the principle of the vibration attenuation | damping in the dynamic vibration absorber of a reference form. It is a figure which shows the modification of the dynamic vibration damper of a reference form. It is the schematic which abbreviate | omitted and showed the whole structure of embodiment of the dynamic vibration damper which concerns on this invention. It is a figure which shows the structure of the attenuator of the dynamic vibration damper of embodiment. It is a figure which shows another example of a structure of the attenuator of the dynamic vibration damper of embodiment. It is a figure which shows another modification of the dynamic vibration damper of embodiment. It is a figure which shows another embodiment of the dynamic vibration damper which concerns on this invention.

DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments and reference embodiments of a dynamic vibration absorber (hereinafter simply referred to as a dynamic vibration absorber) using locking according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view showing a reference form of a dynamic vibration absorber according to the present invention.
The dynamic vibration absorber (1) of the reference form has a polygonal bottom surface (2), and its gravity center position (G) is lower than the center of curvature radius (O) of the arc (A) circumscribing the polygon. It is configured to be in. In the figure, (R) is the radius of curvature of the circumscribed circle of the bottom surface (2).

  In the present invention (including all disclosed embodiments and reference embodiments), the radius of curvature (R) of the arc (A) may or may not be constant. The case where the radius of curvature is not constant is a case where the radius of curvature of the ground contact portion is set larger than that of other portions in advance so as to cope with a large vibration, as will be described later. In this specification and the accompanying drawings, a case where the radius of curvature is constant will be described as an example of the present invention.

  The bottom surface (2) is installed on the installation surface (3) such as the ground so that the arc (A) is directed downward. Then, by receiving the vibration, the rocking vibration in which the right end and the left end alternately rise and fall alternately on the installation surface (3) with the center of curvature radius (O) as the rotation center.

For an object that has an arc-shaped bottom surface with a constant radius of curvature, such as rising up, and whose center of gravity is located below the center of curvature radius of the arc, ignoring the effect of the moment of inertia If the amplitude is not so large, the natural frequency f _n is approximately expressed by the following equation. (R: distance from center O to center of gravity G)

  As the amplitude increases, the natural frequency slightly decreases when the radius of curvature (R) is constant. In the present invention, in order to cope with the case where the amplitude becomes large, the curvature radius of the portion that comes in contact with the installation surface is made slightly larger than the other portions in advance to prevent the natural frequency from decreasing. Is also possible.

From the above equation, the natural frequency varies greatly depending not only on the radius of curvature R but also on the distance r.
That is, when r approaches 0, the natural frequency approaches 0, and when r approaches R, the natural frequency increases.
Therefore, the natural frequency can be changed greatly only by adjusting the relationship between r and R. In particular, by shortening r (making the center of gravity position G closer to the radius of curvature center O), the natural frequency can be lowered as much as possible, so that gravity is used as a restoring force in the same manner as a pendulum dynamic vibration absorber. Therefore, it is possible to realize a low natural frequency by downsizing the whole.

However, there is no element that attenuates vibration in the structure that has an arc-shaped bottom surface with a certain radius of curvature and the center of gravity is below the center of the radius of curvature of the arc. It is insufficient.
Therefore, in the dynamic vibration absorber according to the reference embodiment, the bottom surface has a polygonal shape along an arc having a certain radius of curvature in order to add an element for damping vibration.

When an object having a polygonal bottom surface (2) as shown in FIG. 1 performs rocking vibration, a large collision energy is generated instantaneously due to collision of the polygonal corners with the installation surface (3). The collision energy is dissipated outside as waves.
Therefore, as the rocking vibration continues, the vibration energy is reduced by being converted into impact energy and dissipated, and the vibration can be attenuated without using a general attenuator.

Hereinafter, the principle of vibration damping by the dissipation of impact energy as described above will be described.
When a rigid body having a flat bottom surface rocks and vibrates (see FIG. 2), it is expressed by the following equation (1) mainly based on the relationship between the width of the bottom surface and the height of the center of gravity.

In this case, the attenuation in free vibration is determined, and the larger the width (or β), the larger the attenuation. Therefore, the attenuation can be adjusted by the width.
However, the frequency of free vibration when the bottom surface is flat varies greatly depending on the amplitude, and is not suitable for use as a general dynamic vibration absorber.

Therefore, in the reference embodiment of the present invention, as shown in FIG. 1, a polygonal bottom surface (2) along an arc (A) having a constant radius of curvature (R) is employed. (However, as described above, the radius of curvature (R) of the arc (A) may not be constant.) Here, one interior angle (α) of the polygon is 90 ° <α <180. Set in the range of °. The sizes of the inner angles are preferably equal, but may be different.
By using such a polygonal bottom surface, the amplitude dependence of the natural frequency is reduced as compared with the case where the bottom surface is flat. Further, unlike the case where the bottom surface is an arc, attenuation can be secured.
Furthermore, from the above equation (1), the attenuation becomes smaller as the length of one side of the polygon is reduced (inner angle (α) is increased), so that the magnitude of the attenuation can be adjusted. The magnitude of attenuation can be calculated by repeatedly using the above equation (1).
Therefore, the dynamic vibration absorber of the reference form can exhibit a function as a dynamic vibration absorber just by placing it without using a spring or an attenuator.

FIG. 3 is a diagram illustrating a modification of the dynamic vibration absorber of the reference embodiment.
In this modification, an absorbing material (4) that absorbs collision energy generated when a corner portion of the bottom surface collides with the installation surface (3) is disposed below the bottom surface (2).
The absorbent material (4) is made of a sheet-like member having elasticity and damping properties such as a viscoelastic body, and is laid between the bottom surface (2) and the installation surface (3).
As the viscoelastic body, for example, a material such as an acrylic, urethane, silicone, or styrene resin foam or a gel material is used.

  In this way, the noise generated when the corner collides with the installation surface is reduced by disposing the absorber that absorbs the collision energy generated when the corner of the bottom collides with the installation surface. can do.

  Note that when the absorbent material (4) is laid between the bottom surface (2) and the installation surface (3) as in the modification, the attenuation is not the same as when the absorbent material (4) is not laid. It is preferable to design by performing numerical analysis (multibody analysis) using the spring and damping characteristics of the material.

As described above, the dynamic vibration absorber of the reference form can dissipate energy by using a collision caused by rocking, and therefore exhibits a damping performance without using a damper like a conventional dynamic vibration absorber. Is possible.
However, since problems such as noisy collision noise occur, a method of damping with a material (FIG. 3) can be employed instead of adding an absorbing material to mitigate the impact.

FIG. 4 is a schematic view showing an embodiment of a dynamic vibration absorber according to the present invention.
The dynamic vibration absorber (1) of this embodiment has an arc-shaped bottom surface (2) having a constant radius of curvature (R), and its center of gravity (G) is the center of curvature radius of the arc (A) ( It is configured to be below O). However, also in this embodiment, as described above, the radius of curvature (R) of the arc (A) is not necessarily constant.
That is, in the reference embodiment, the bottom surface is polygonal, but in this embodiment, the bottom surface is arcuate. However, the attenuator described later is omitted in FIG.

  The bottom surface (2) is installed on the installation surface (3) such as the ground so that the arc (A) is directed downward. Then, by receiving the vibration, the rocking vibration in which the right end and the left end alternately rise and fall alternately on the installation surface (3) with the center of curvature radius (O) as the rotation center.

As described above, the influence of the moment of inertia is ignored for an object that has an arc-shaped bottom surface with a certain radius of curvature, such as rising up, and whose center of gravity is located below the center of curvature radius of the arc. In this case, the natural frequency f _n is approximately expressed by the following expression if the amplitude is not so large. (R: distance from center O to center of gravity G)

  In this embodiment as well, it is possible to prevent the natural frequency from decreasing by slightly increasing the radius of curvature of the portion that contacts the installation surface when the amplitude increases.

From the above equation, the natural frequency varies greatly not only with the radius of curvature R but also with the distance r. When r approaches 0, the natural frequency approaches 0, and when r approaches R, the natural frequency increases. .
Therefore, also in the dynamic vibration absorber of the embodiment, the natural frequency can be changed greatly only by adjusting the relationship between r and R. In particular, by shortening r (making the center of gravity position G closer to the radius of curvature center O), the natural frequency can be lowered as much as possible, so that gravity is used as a restoring force in the same manner as a pendulum dynamic vibration absorber. Therefore, it is possible to realize a low natural frequency by downsizing the whole.

However, as described above, a structure having an arc-shaped bottom surface having a constant radius of curvature and having a center of gravity located below the center of the radius of curvature of the arc has no element to attenuate vibrations. It is insufficient for use.
Therefore, in the dynamic vibration absorber according to this embodiment, a damping mechanism for damping the rocking vibration of the bottom surface (2) is provided in order to add an element for damping the vibration.
By adding the damping mechanism, the vibration of the structure can be transmitted to the damping mechanism via the rocking vibration of the bottom surface, and the damping action can be exhibited.

In the example shown in FIG. 5, the damping mechanism includes an attenuator (5) disposed between the bottom surface (2) and the installation surface (3). In this figure, only the bottom surface (2) of the dynamic vibration absorber is shown, and the portion above the bottom surface is omitted because it is the same as FIG.
In the illustrated example, the attenuator (5) includes two bag bodies (51) disposed between the bottom surface and the installation surface (3) at both ends of the bottom surface (2), and these two bag bodies. (51) and the pipe | tube (52) which connects and connects.

Liquids such as water and oil are sealed inside the two bags (51), and the liquid can flow between the two bags through the pipe (52). Specifically, when the bottom surface (2) is tilted to the right, the right bag body (51) is stepped on the bottom surface (2), and the liquid inside the bag body passes through the pipe (52) and the left bag body. Move to (51). Conversely, when the bottom surface (2) is tilted to the left, the left bag body (51) is stepped on the bottom surface (2), and the liquid inside the bag body passes through the pipe (52) and the right bag body (51). ).
Therefore, when the bottom surface (2) rocks and vibrates, the left and right bags (51) are stepped on by the bottom surface (2) alternately, and the liquid inside moves alternately to the left and right bags. Thereby, the energy of the rocking vibration of the bottom surface is consumed by the fluid flow between the two bags, and the vibration can be attenuated.
In the illustrated example, the damping effect is enhanced by providing an orifice (53) inside the pipe (52) to increase the fluid resistance.

In the reference example shown in FIG. 6, the attenuator (5) is made of a damping material disposed between the bottom surface (2) and the installation surface (3). In this figure, only the bottom surface (2) of the dynamic vibration absorber is shown, and the portion above the bottom surface is omitted because it is the same as FIG.
The damping material is a sheet-like member having a certain thickness laid on the installation surface (3), and the bottom surface (2) is placed on the upper surface of the damping material. As the damping material, a material having a high damping capability such as fluorine rubber or silicon rubber is used.
By using such a damping material as the attenuator (5), the energy of the rocking vibration of the bottom surface (2) can be absorbed by the damping material, so that the vibration can be effectively damped with a simple configuration. it can.

In the reference example shown in FIG. 7, the damping mechanism is composed of a large number of particles (7) accommodated movably in the internal space (6).
That is, in this reference example, a space (6) is provided in the interior along the bottom surface (2) of the dynamic vibration absorber, and a large number of particles (7) are accommodated in the internal space (6).
The shape of the granule (7) is not particularly limited, but it is preferably a spherical shape that can smoothly move in the internal space (6) with the rocking vibration of the bottom surface (2). Further, the number and size of the granules (7) are set in a range in which the internal space (6) is not filled with the granules (7) in order to secure a space in which the granules (7) can move.
The internal space (6) is preferably formed as a space extending in the direction along the bottom surface (2) as shown in the example so that the granule (7) moves greatly with rocking vibration, but is particularly limited. It may be formed in another position instead of the dynamic vibration absorber.
By providing such a damping mechanism, the vibration can be attenuated by the movement of a large number of particles (7) accompanying the rocking vibration of the bottom surface (2).

  In the dynamic vibration absorber of the embodiment, the problem of the collision sound can be solved by making the bottom surface into an arc shape. However, since energy dissipation due to collision can hardly be expected, a method using a means for setting damping separately (FIGS. 5 to 7) utilizing the feature that rocking can freely adjust the natural frequency is adopted. can do.

FIG. 8 is a view showing still another embodiment of the dynamic vibration absorber according to the present invention.
In this embodiment, when the dynamic vibration absorber moves when slippage occurs between the bottom surface (2) and the installation surface (3) outside the dynamic vibration absorber (1), the dynamic vibration absorber is received. A member (8) is fixed.
The receiving member (8) is a wall-like shape that is fixed upright with respect to the installation surface (3) so as to surround the whole or part of the periphery of the dynamic vibration absorber at a position slightly away from the dynamic vibration absorber (1). It is a member.
On the surface of the receiving member (8) (the surface facing the dynamic vibration absorber), an impact absorbing material (81) that absorbs an impact when the dynamic vibration absorber collides is disposed.
The shock absorber (81) is made of a material having elasticity and damping properties such as a viscoelastic body. For example, a material such as an acrylic, urethane, silicone, styrene resin foam or gel material is used. Used.

According to the embodiment shown in FIG. 8, when a slip is generated between the bottom surface (2) and the installation surface (3) of the dynamic vibration absorber (1) under a very large external force such as an earthquake, the dynamic vibration absorber (1) collides with the receiving member (8) and is received, and the impact energy generated at this time is dissipated by the impact absorbing material (81) on the surface of the receiving member (8). That is, the shock absorbing material (81) plays the role of an impact damper and can effectively attenuate the vibration.
This embodiment can be suitably applied to an embodiment in which the bottom surface (2) has an arc shape, but can also be applied to a reference form in which the bottom surface (2) has a polygonal shape.

  The dynamic vibration absorber according to the present invention has been described above with reference to the drawings. However, the drawings schematically show the configuration of the present invention, and the present invention is applied to shapes other than the bottom surface (2). It can be designed to have any shape as appropriate according to the type of structure.

  INDUSTRIAL APPLICABILITY The present invention can be used as a dynamic vibration absorber for suppressing vibrations that occur in structures such as buildings, bridges, and machines due to strong winds, earthquakes, vehicle passing, mechanical vibrations, and the like.

DESCRIPTION OF SYMBOLS 1 Dynamic vibration absorber 2 Bottom surface 3 Installation surface 4 Absorber 5 Attenuator 51 Bag body 52 Pipe 53 Orifice 6 Inner space 7 Granule 8 Receiving member 81 Shock absorber A Arc G Center of gravity O Center of curvature radius R Curvature radius

Claims (3)

Having an arc-shaped bottom,
The center of gravity is below the center of curvature radius of the arc,
It has a damping mechanism that attenuates the rocking vibration of the bottom surface,
The damping mechanism comprises an attenuator disposed between the bottom surface and the installation surface,
The attenuator is disposed between the bottom surface and the installation surface at both ends of the bottom surface, and two bags each having a liquid sealed therein, and the flow of the liquid between the two bag bodies. A dynamic vibration absorber using locking, characterized in that it comprises a tube that connects the bag bodies in communication with each other.   The dynamic vibration absorber using rocking according to claim 1, wherein an orifice is provided in the pipe. A receiving member for receiving the dynamic vibration absorber is fixed to the outside of the dynamic vibration absorber when the dynamic vibration absorber moves due to slippage between the bottom surface and the installation surface.
3. The dynamic vibration absorber using rocking according to claim 1 or 2, wherein a shock absorbing material for absorbing an impact at the time of collision of the dynamic vibration absorber is disposed on a surface of the receiving member.

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