JPH09310428A - Damping device for pole - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remarkably damp vibration of a pole by fitting a container having swing frequency nearly conformed to the natural frequency of the pole in which viscous fluid is enclosed to the upper half part of the pole. SOLUTION: A damping device 8 in which viscous fluid such as silicone oil is enclosed in a cylindrical container 6 and having swing frequency nearly conformed to the natural frequency of a pole 1 such as lighting pole is provided, is fitted to the upper half part of the pole 1. Next, if necessary, the device 8 is fitted to the vicinity of the upper end part of the pole 1 where the amplitude becomes maximum by external vibration, so as to attain sure damping. In the case of a pole and the like in which a pair of pillars are combined together through a combined beam, the horizontal section of the container 6 is made, for example, into a rectangle, and the direction of higher natural frequency of the pole is set shorter than the direction of lower frequency. The swing frequency of the device 8 is set high in the extending direction of the combined beam, and low in the direction squarely crossing with the combined beam. Hereby, vibration of the pole can be remarkably reduced, plastic deformation and breakdown can be prevented, and the sectional area can be minified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration damping device for a pole such as a power distribution pole, a mobile telephone receiving / transmitting pole, and an illumination pole.

[0002]

2. Description of the Related Art In general, poles vibrate under external forces such as earthquakes, winds, and traffic vibrations, and in some cases, may cause plastic deformation or fatigue failure. Therefore, techniques for suppressing this type of vibration have been conventionally proposed.
This type of damping technology can be mainly classified into two types.

That is, a technique for optimizing the natural frequency of a pole by appropriately designing the weight, shape, and rigidity of the pole, and reducing a resonance phenomenon by attaching a damping device having a damping effect to the pole. There is technology.
As the former technique, for example, it is possible to set the cross-sectional shape (wall thickness, diameter) of the pole according to the installation location of the pole, but it is not practical because the design value of the pole will be changed for each installation location. Absent. Therefore, in general, the latter technique is often applied.

[0004]

By the way, as a vibration damping device, as shown in FIG. 15, a plurality of weight bodies 2 such as metal balls are arranged inside a pole 1 to prevent vibration of the pole 1. It is considered that the weight body 2 is converted into a collision between the weight bodies 2 and absorbs the vibration (Japanese Utility Model Laid-Open No. 4-131806).
However, in this configuration, since the weight body 2 collides, there are inconveniences such as collision noise and damage to the weight body 2, and additional measures are required to eliminate these inconveniences. .

Further, as shown in FIG. 16, a container 4 containing a fluid substance 3 such as silicon oil, water, sand and iron sand is provided inside the pole 1 and the container 4 is connected to the pole 1. There is also a proposal to suppress the vibration of the pole 1 (Japanese Utility Model Laid-Open No. 2-6835). Since this configuration adds viscous damping mainly for the purpose of reducing the vibration due to Karman vortices that occur during strong winds, the vibration of the pole 1 caused by the irregular and large amplitude external vibration such as the earthquake vibration. It is not possible to expect the effect of sufficiently suppressing (the first vibration mode becomes an extremely large shake. Earthquake response).

The present invention has been made in view of the above circumstances, and an object thereof is to obtain a large vibration damping effect against external vibration that cannot be sufficiently suppressed by the conventional technology, particularly external vibration due to an earthquake. The purpose is to provide a vibration damping device for a pole.

[0007]

According to a first aspect of the present invention, there is provided a vibration damping device attached to an upper half of a pole, wherein a viscous material is provided so that the vibration frequency substantially matches the natural frequency of the pole. The fluid that is contained therein is enclosed in a container. With this configuration, when the container vibrates due to the vibration of the pole, the fluid enclosed in the container swings to cancel the vibration of the pole, and as a result, the vibration of the pole can be suppressed. Here, the swing frequency is a frequency at which the center of gravity of the liquid moves when the liquid in the container is swung, and can be theoretically derived from Housner's theory. Then, if the oscillation frequency is made to approximately match the natural frequency of the pole, the natural vibration component of the pole is reduced, so the vibration of the pole is greatly reduced, and the plastic deformation and damage of the pole are prevented. can do.

According to a second aspect of the present invention, in the first aspect of the invention, the liquid is silicon oil, which is physically and chemically stable and is unlikely to vaporize or coagulate in an outdoor environment. Since it has excellent long-term durability, and its viscosity is relatively large, it is possible to obtain a low-frequency oscillation frequency with a small capacity, and there is little change in viscosity due to temperature changes, and oscillation frequency changes due to changes in the external environment. It has the advantage of being small.

According to a third aspect of the present invention, in the first or second aspect of the invention, the container is arranged near the upper end of the pole where the amplitude due to external vibration is maximized, and the amplitude is maximized. By arranging the container at a different portion, the vibration damping effect can be surely obtained. According to the invention of claim 4, in the inventions of claims 1 to 3, the inner dimension of the horizontal cross section of the container is set so that the direction in which the natural frequency of the pole is high is shorter than the direction in which it is low. hand,
Even if the cross-section of the pole is irregular and the natural frequency is directional, by giving directionality to the inner dimension of the horizontal cross section of the container, vibration in each direction can be suppressed by using only one container. Will be possible. For example, if the cross-sectional shape of the pole is square, the natural frequency differs between the extension direction of each side and the diagonal direction, and the natural frequency is lower in the diagonal direction than in the extension direction of each side, but the horizontal section is square. If the direction of each side of the pole and the container is made to coincide with using the container of, the oscillation frequency in the diagonal direction can be made lower than the oscillation frequency in the extension direction of each side (from the diagonal line rather than each side). As a result, a high damping effect can be obtained in any direction. In addition, in the case where the pole has a rectangular cross section or the structure in which two columns are connected by a connecting beam, the natural frequency in the longitudinal direction of the cross section (or the direction of the connecting beam) is the direction orthogonal to that direction. Therefore, if a container with a rectangular horizontal cross section is used and the short side direction of the horizontal cross section of the container is aligned with the longitudinal direction of the pole cross section, a high damping effect is obtained in any direction. It is possible.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) In this embodiment, as shown in FIG. 1, a lamp 5 is provided at each end of an arm 1a that extends horizontally in the upper end of a cylindrical pole 1 standing on the ground E. The illumination column is illustrated. Two damping devices 8 in which a viscous liquid 7 is enclosed in a cylindrical container 6 are attached to the upper end of the pole 1 as shown in FIG. This damping device 8
Has a swing frequency that substantially matches the natural frequency of the pole 1.

That is, the natural frequency of the pole 1 is determined by the equivalent mass of the pole 1 and the rigidity of the pole 1 against bending. For example, when the equivalent mass is 11.6 kg and the bending rigidity is 2860 N / m, according to the experiment,
The natural frequency of the pole 1 is 2.5 Hz. The characteristic marked with a circle in FIG. 3 shows the frequency response of the pole 1 under the above conditions when the vibration damping device 8 is not provided, and the amplitude shows a peak value near 2.5 Hz.

On the other hand, in the vibration damping device 8, the liquid 7 is enclosed in a cylindrical container 6 having an inner diameter of 140 mm so that the liquid surface has a height of 43 mm. According to Hausner's theory, the vibration condition when using the two damping devices 8 is 0.65 kg (fluctuation of oscillation) of the fluid at 2.3 Hz, which is approximately equal to 2.5 Hz which is the natural frequency of the pole 1. Mass) will oscillate. The frequency response when water is selected as the liquid is shown by an X mark in FIG. 3, and the frequency response when silicon oil is selected as the liquid is shown by a □ mark in FIG.

Here, the liquid 7 contains a non-oscillating mass that does not become the above-mentioned oscillating mass, and the non-oscillating mass is 0.
It will be 5 kg. This non-oscillating mass is included in the vibration condition of the pole 1, and the total equivalent mass of the pole 1 is 12.1
It will be kg. As is clear from FIG. 3, the vibration damping device 8
The amplitude becomes smaller when (1) is used, and particularly when silicon oil is used as the liquid 7, the amplitude becomes very small. Further, although water may be solidified or vaporized due to changes in temperature, silicone oil has less possibility of solidification and vaporization in the normal operating temperature range and is excellent in environmental resistance as compared with water. Moreover, silicone oil is superior to mineral oil in terms of viscosity and temperature characteristics, and is also excellent in physical and chemical stability, so that it is superior in long-term durability performance. Therefore, the liquid used for the vibration damping device 8 is preferably silicone oil.

FIG. 4 shows an experimental result concerning the vibration of the pole 1 when the external force is removed after the external force is applied to the upper end of the pole 1 to give the initial displacement. 4A shows the case where the vibration damping device 8 is not provided, and FIG. 4B shows the vibration damping device 8
The results when (liquid 7 is silicone oil) are provided are shown. As is clear by comparing the two, the vibration of the pole 1 can be rapidly attenuated by providing the vibration damping device 8.

Further, FIG. 5 shows a simulation result in which the vibration of the pole 1 against an earthquake is numerically calculated.
5 (a) shows the applied external vibration (simulation of an earthquake), FIG. 5 (b) shows the vibration of the pole 1 without the vibration damping device 8, and FIG. 5 (c) shows the vibration damping device 8 provided. The vibrations of the pole 1 are shown. From this simulation result, it can be seen that the vibration damping effect of this embodiment is extremely large.

Here, in this embodiment, two vibration damping devices 8 are provided.
However, even if only one damping device 8 is effective, three or more damping devices 8 may be provided. (Embodiment 2) In the first embodiment, the lamp 5 is attached to the tip of the arm 1a extending horizontally at the upper end of the pole 1, but in the present embodiment, as shown in FIG. Two arms 1a projecting diagonally upward
A lamp 5 is attached to the tip of the lamp. That is, the lamp 5 is attached to the substantially Y-shaped pole 1. The vibration damping device 8 is preferably the upper end portion of the pole 1 where the amplitude at the time of vibration becomes the largest, but the upper half portion of the pole 1 can provide a large damping effect. You may provide in a position other than a part. Therefore, in the present embodiment, the vibration damping device 8 is provided not in the upper end portion which is the tip of the arm 1a but in a portion between the arms 1a. Other configurations and effects are similar to those of the first embodiment.

(Embodiment 3) In this embodiment, as shown in FIG. 7, one lamp 5 is attached to the upper end of a pole 1, and a vibration damping device 8 is attached to the lamp 5. It is provided in the shape. Now, the equivalent mass of the pole 1 is 87.4 kg,
If the rigidity with respect to the bending direction is 9030 N / m, the natural frequency is 1.618 Hz. That is, the vibration damping device 8
The frequency response in the case where is not provided has the characteristic shown by the broken line in FIG.

On the other hand, as the vibration damping device 8, a cylindrical container 6 having an inner diameter of 440 mm is used, and one container in which silicone oil is sealed as the liquid 7 so that the height of the liquid surface is 168 mm is used. The oscillation frequency of the liquid 7 under this condition is 1.3.
6 Hz and the oscillating mass is 11.1 kg. Also,
The non-oscillating mass is 13.6 kg. Therefore, the total equivalent mass of the pole 1 was 101.0 kg.

When such a vibration damping device 8 was added, a frequency response as shown by the solid line in FIG. 8 was obtained. That is, as compared with the case where the vibration damping device 8 is not provided, the amplitude greatly occurs and a high vibration damping effect can be obtained. (Embodiment 4) In each of the above-described embodiments, it is assumed that the pole 1 has a circular cross-sectional shape, but in the present embodiment, the case where the pole 1 has a rectangular cross-sectional shape will be described. If the cross-sectional shape of the pole 1 is circular, the natural frequency is considered to be almost constant regardless of the vibration direction in the horizontal plane, but if the cross-sectional shape is square, the natural frequency will vary depending on the vibration direction in the horizontal plane. It will be different. That is, if the cross-sectional shape is square, the natural frequency differs between the vibration in the direction along each side and the vibration in the diagonal direction (that is, the direction forming 45 degrees with respect to each side). In this way, when the natural frequency of the pole 1 changes depending on the vibration direction, it is necessary to use the vibration damping device 8 whose oscillation frequency changes according to the vibration direction.

Therefore, in this embodiment, as shown in FIG. 9, the vibration damping device 8 is constructed by using the prismatic container 6 whose bottom surface is substantially similar to the cross-sectional shape of the pole 1. Here, only one vibration damping device 8 is used. According to Hausner's theory, the larger the inner size of the container 6, the more liquid 7
Since the rocking frequency becomes low, the rocking frequency can be made different in the direction along each side of the bottom surface of the container 6 and in the diagonal direction by using the container 6 having a square bottom surface. Therefore, the vibration damping device 8 using the container 6 having the bottom surface shape that is substantially similar to the cross-sectional shape of the pole 1
By configuring the above, when the natural frequency of the pole 1 has directionality, the oscillation frequency of the vibration damping device 8 can have the same directionality. It is possible to obtain a high damping effect. Other configurations and operations are the same as those of the first embodiment.

(Embodiment 5) This embodiment is an example in which a plurality of vibration damping devices 8 are used for a pole 1 having a rectangular cross section, as shown in FIG. Here, five vibration damping devices 8 each having a prismatic container 6 having a square bottom are used, and the other four vibration damping devices 8 are closely attached to each side of the central vibration damping device 8. They are arranged in a glyph.

When a plurality of vibration damping devices 8 are used in this way, the size of each vibration damping device 8 is smaller than that in the case where only one vibration damping device 8 produces a vibration damping effect. can do. That is, as compared with the case where only one large vibration damping device 8 is provided, the small size facilitates the attachment, and thus the pole 1 can be easily provided with versatility as a retrofit component. Other configurations and operations are the same as those of the first embodiment.

(Embodiment 6) This embodiment is an example in which the pole 1 has a rigid frame structure as shown in FIG. 11, and the pole 1 has a pair of support columns 1c and a pair of support columns 1c. And a connecting beam 1d. The pole 1 having such a structure has a high rigidity in the extending direction of the connecting beam 1d in the horizontal plane and a low rigidity in the direction orthogonal to the connecting beam 1d. That is, the natural frequency becomes higher in the extending direction of the connecting beam 1d.

Therefore, the vibration damping device 8 has a structure in which the oscillation frequency in the extending direction of the coupling beam 1d is higher than the oscillation frequency in the direction orthogonal to the coupling beam 1d. That is,
As described in the fourth embodiment, the larger the inner size of the container 6 is, the lower the oscillation frequency is. Therefore, the rectangular shape of the bottom surface makes the direction of the short side coincide with the extension direction of the coupling beam 1d. The oscillation frequency of the vibration device 8 can be set high in the extending direction of the connecting beam 1d and low in the direction orthogonal to the connecting beam 1d. With this configuration, it is possible to obtain a high damping effect even for the pole 1c whose natural frequency greatly differs depending on the vibration direction.

Also in this embodiment, it is possible to use a plurality of vibration damping devices 8 as shown in FIG.
The arrangement and the number of the vibration damping devices 8 can be appropriately selected according to the shape of the pole 1. (Embodiment 7) This embodiment shows an example in which the pole 1 has a circular cross-sectional shape, and one spherical lamp 5 is attached to the upper end of the pole 1 as shown in FIG. In such a structure, since the natural frequency of the pole 1 hardly causes directionality, it is desirable that the vibration damping device 8 also has substantially no directionality. Therefore, a donut-shaped vibration damping device 8 as shown in FIG. 14 is used so that the vibration damping device 8 is positioned around the tip of the pole 1. Since the vibration damping device 8 having this structure can be easily attached to the pole 1 having no arm, it is highly versatile as a retrofit component.

[0026]

According to a first aspect of the present invention, there is provided a vibration damping device mounted on an upper half of a pole, wherein a fluid having a viscosity so as to have a rocking frequency substantially equal to a natural frequency of the pole is contained in a container. When the container vibrates due to the vibration of the pole, the fluid enclosed in the container swings to cancel the vibration of the pole, and as a result, the vibration of the pole can be suppressed. There are advantages. In other words, by making the oscillation frequency substantially equal to the natural frequency of the pole, the natural vibration component of the pole is reduced, so that the vibration of the pole is significantly reduced, and the vibration resistance of the pole is improved. There is an effect that it is possible to prevent plastic deformation and damage of the pole. As a result, even if the strength of the pole is reduced, the pole is not damaged by external vibration, the cross-sectional area of the pole can be reduced, and the appearance of the pole can be improved. Further, since the vibration is damped by utilizing the swing of the liquid, there is also an advantage that no abnormal noise such as impact noise is generated.

When silicon oil is used as the liquid as in the second aspect of the present invention, the silicone oil is physically and chemically stable and is hard to vaporize and coagulate in an outdoor environment, and has excellent long-term durability. Moreover, since the viscosity is comparatively large, it is possible to obtain a low-frequency oscillation frequency with a small capacity, and it is possible to obtain an effect that there is little variation in the viscosity with respect to temperature changes and little variation in the oscillation frequency due to changes in the external environment. In other words, it has the advantage that it does not change over time and requires almost no periodic maintenance.

According to the third aspect of the present invention, in the case where the container is arranged near the upper end of the pole where the amplitude due to the external vibration is maximized, the vibration is suppressed by disposing the container in the region where the amplitude is maximized. There is an advantage that the effect can be surely obtained. According to the invention of claim 4, in which the inner dimension of the horizontal cross section of the container is set so that the direction in which the natural frequency of the pole is high is shorter than the direction in which the natural frequency is low, the cross-sectional shape of the pole is irregular. Even if the natural frequency has directivity, by giving directivity to the inner dimension of the horizontal cross section of the container, it is possible to suppress vibration in each direction by using only one container. . That is, there is an effect that a high damping effect can be obtained in any direction.

[Brief description of drawings]

FIG. 1 shows Embodiment 1 of the present invention, (a) is a front view,
(B) is a plan view.

2A and 2B show a vibration damping device used in the above, wherein FIG. 2A is a sectional view and FIG. 2B is a plan view.

FIG. 3 is an operation explanatory diagram of the above.

FIG. 4 is an operation explanatory view of the above.

FIG. 5 is an operation explanatory view of the above.

FIG. 6 shows Embodiment 2 of the present invention, (a) is a front view,
(B) is a plan view.

FIG. 7 shows Embodiment 3 of the present invention, (a) is a front view,
(B) is a plan view.

FIG. 8 is an operation explanatory view of the above.

FIG. 9 shows Embodiment 4 of the present invention, (a) is a front view,
(B) is a plan view.

FIG. 10 shows Embodiment 5 of the present invention, (a) is a front view and (b) is a plan view.

FIG. 11 shows Embodiment 6 of the present invention, (a) is a front view and (b) is a plan view.

FIG. 12 shows another configuration example of the sixth embodiment of the present invention,
(A) is a front view, (b) is a side view, and (c) is a plan view.

FIG. 13 is a front view showing a seventh embodiment of the present invention.

FIG. 14 shows a vibration damping device used in the same as above, (a) is a cross-sectional view, and (b) is a plan view.

FIG. 15 is a horizontal sectional view showing a conventional example.

FIG. 16 shows another conventional example, in which (a) is a longitudinal cross-sectional view of a main part,
(B) is a horizontal cross-sectional view of a main part, and (c) is a cross-sectional view of a container in which a liquid used therein is sealed.

[Explanation of symbols]

 1 Pole 5 Lighting 6 Container 7 Liquid 8 Vibration control device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shin Kobayashi 1048, Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works Co., Ltd.

Claims (4)

[Claims] 1. A vibration damping device attached to the upper half of a pole, wherein a viscous fluid is enclosed in a container so as to have a rocking frequency that substantially matches the natural frequency of the pole. Vibration control device for poles. 2. The vibration damping device for a pole according to claim 1, wherein the liquid is silicone oil. 3. The vibration damping device for a pole according to claim 1, wherein the container is arranged near an upper end portion of the pole where the amplitude due to external vibration is maximum. 4. The pole control device according to claim 1, wherein the inner dimension of the horizontal cross section of the container is set so that the direction in which the natural frequency of the pole is high is shorter than the direction in which the natural frequency is low. Shaking device.