JPH1113308A - Vibration control device for pole - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a vibration control effect to external vibrations such as an earthquake by installing a vessel, in which a fluid is sealed, to the upper half section of a pole, acquiring oscillation frequency approximately coinciding with the natural frequency of the pole and forming a projecting piece to the inner circumferential surface of the vessel. SOLUTION: A fluid 2 is sealed into a cylindrical vessel 3, and projecting pieces 4 are formed to the inner circumferential surface of the vessel 3 at regular intervals and the fluid 2 is rocked in a well-balanced manner. Length in the horizontal direction of the projecting piece 4 is formed in one fifth or less of the inside diameter of the vessel 3, and the rotary motion of the fluid 2 in the vicinity of the inner circumferential surface of the vessel 3 is inhibited. A vibration control effect is improved by forming the projecting pieces 4 near the level height of the fluid 2. Consequently, the fluid sealed into the vessel 3 is rocked by the vibrations of the pole 1 and the vibrations of the pole 1 are suppressed, and oscillation frequency coincides with the natural frequency of the pole 1 and a natural frequency component is reduced. Accordingly, the earthquake-resistant strength of the pole 1 is increased, and the rotary motion of the fluid 2 is lowered by the projecting pieces 4 and the vibration control effect to external vibrations can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Generally, a pole vibrates under external force such as earthquake, wind, traffic vibration and the like, and in some cases, composition deformation or fatigue failure may occur. Therefore,
Techniques for suppressing this type of vibration have been conventionally proposed.

[0003] That is, a technique for optimizing the natural frequency of the pole by appropriately designing the weight, shape, and rigidity of the pole, and mounting a damping device having a damping effect on the pole to reduce the resonance phenomenon. There is technology to make it.
As the former technique, for example, it is conceivable to set the cross-sectional shape (thickness, diameter) of the pole according to the installation location of the pole. However, since the design value of the pole is applied to each installation location, it is not practical. Absent. Therefore, generally, the latter technique is often applied.

[0004]

As shown in FIG. 5, as a vibration damping device, a plurality of weights 8 such as metal balls are arranged inside a pole 1 so that the vibration of the pole 1 is reduced. A device that converts the collision into a collision between the weight bodies 8 and absorbs vibration has been considered. (Japanese Utility Model Laid-Open No. 4-131806).
However, in this configuration, since the weight body 8 collides, there are inconveniences such as a collision sound being generated and the weight body 8 being damaged, and additional measures are required to solve these inconveniences. .

As shown in FIG. 6, a container 3 in which a fluid 2 such as silicon oil, water, sand or iron sand is provided inside a pole 1 and the container 3 is connected to the pole 1 One that suppresses the vibration of 1 is also considered. (Japanese Unexamined Utility Model Publication No. Hei 2-6835) In this configuration, a viscous marshal is added for the main purpose of reducing vibrations caused by Karman vortices generated in strong winds. The effect of sufficiently suppressing the vibration of the pole 1 caused by the large external vibration (the primary vibration mode becomes an outstanding large shaking; earthquake response) cannot be expected.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a large vibration damping effect against external vibrations which cannot be sufficiently suppressed by the prior art, particularly, external vibrations due to earthquakes. It is an object of the present invention to provide a pole damping device that can be obtained.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, a fluid 2 is sealed in a container 3,
Attach the container 3 to the upper half of the pole 1
In the vibration damping device having a swing frequency substantially matching the natural frequency of the container 3, the projecting piece 4 is provided on the inner peripheral surface of the container 3.

In such a vibration damping device for the pole 1, when the container 3 attempts to vibrate due to the vibration of the pole 1, the fluid 2 sealed in the container 3 oscillates, thereby canceling the vibration and the vibration of the pole 1. Can be suppressed. Here, the oscillating frequency is a frequency at which the center of gravity of the fluid 2 moves when the fluid 2 in the container 3 oscillates, and can be theoretically derived by the Hausner's theory. When the oscillation frequency is made to match the natural frequency of the pole 1, the natural vibration component of the pole 1 is reduced.
Since the vibration of the pole 1 is greatly reduced, plastic deformation and breakage of the pole 1 can be prevented.

Further, the projecting piece 4 provided on the inner peripheral surface of the container 3
It acts as a resistance to the fluid 2 that is going to swirl along the inner peripheral surface in the container 3. Therefore, the swirling motion of the fluid 2 can be suppressed, and the motion of the fluid 2 is limited to the swing that cancels the external vibration, so that the vibration damping effect can be sufficiently exhibited.

The invention according to claim 2 is characterized in that, in the invention according to claim 1, a plurality of protruding pieces 4 are provided on the inner peripheral surface of the container 3 at equal intervals. .

In such a vibration damping device for the pole 1, since a plurality of projections 4 are provided at equal intervals on the inner peripheral surface of the container 3, the disturbance of the oscillation of the fluid 2 caused by the projections 4 is symmetrical. Therefore, the fluid 2 can oscillate in a well-balanced manner, and the effect of damping external vibrations can be further improved.

According to a third aspect of the present invention, in the first and second aspects of the present invention, the length of the protrusion 4 in the horizontal direction is
It is characterized by being formed to be 1/50 or less of the inner diameter of the container 3.

In such a vibration damping device for the pole 1, since the horizontal length of the projecting piece 4 is 1/50 or less of the inner diameter of the container 3, it greatly affects the oscillation frequency of the fluid 2 in the container 3. , The swirling motion of the fluid 2 near the inner peripheral surface of the container 3 can be suppressed.

According to a fourth aspect of the present invention, in the first to third aspects, the liquid surface 2a of the fluid 2 in the container 3 is provided.
It is characterized in that the upper part of the protruding piece 4 is protruded upward.

In such a vibration damping device for the pole 1, the projecting piece 4 provided near the liquid surface 2 a of the fluid 2 in the container 3
Since the swirling motion in the vicinity of the liquid surface 2a having a high moving speed is effectively suppressed, the vibration damping effect against external vibration can be further improved.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a vibration damping device for a pole 1 according to the present invention will be described below with reference to FIGS.

FIG. 1 shows an embodiment of a damping device for a pole 1 according to the present invention, wherein (a) is a front view of the pole 1, (b) is a cross-sectional view of the damping device, and (c) is an A- It is A sectional drawing.

As shown in FIG. 1A, an arm 6 projecting horizontally from the upper end of a pole 1 standing on the ground 5 is provided.
Illustrates an illumination column provided with a lamp 7 at each end. A vibration damping device in which the fluid 2 having viscosity is sealed in the cylindrical container 3 is attached to the upper surface of the arm 6. This vibration damping device has a swing frequency substantially equal to 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 6.6 kg and the bending stiffness is 1640 N / m, according to experiments, the natural frequency of the pole 1 is 2.5 Hz.

On the other hand, as shown in FIGS. 1B and 1C,
The vibration damping device has a liquid level 2 in a cylindrical container 3 having an inner diameter of 146 mm.
The fluid 2 is sealed so that a is set to a height of 55 mm. As the fluid 2, silicone oil having a kinematic viscosity of 50 cs is used. According to Hausner's linear theory, the vibration condition in this case is the natural frequency of the pole 1 of 2.5.
The frequency is 2.35 Hz, which is substantially equal to Hz.

The inner peripheral surface of the container 3 has a plurality of projecting pieces 4
Are provided at equal intervals. The protruding pieces 4 are formed in the shape of a quadrangular prism that is vertically continuous from the upper end to the lower end of the container 3, and are provided at eight locations on the inner peripheral surface of the container 3. The length of the protrusion 4 in the horizontal direction is 2.9 mm. This length is formed to be 1/50 or less of the inner diameter 146 mm of the container 3.

FIG. 2 is a graph showing a frequency amplitude response indicating the performance of the vibration damping device of the pole 1 shown in FIG. Is a case where the vibration damping device without the projecting piece 4 is used, and a curve C connecting the characteristics indicated by □ is a case where the vibration damping device with the projecting piece 4 is used.

Here, the frequency amplitude response means the amplitude at the upper end of the pole 1 with respect to the amplitude of the pole 1 near the ground 5. Note that the excitation condition is a sweep excitation with an acceleration of 0.06 G.

As is apparent from FIG. 2, when there is no vibration damping device, resonance having a sharp peak of the frequency amplitude response at 2.5 Hz is observed. If the vibration damping device is attached here, the peak of the frequency amplitude response will be at two places, and its size will be small. When the vibration damping device is changed to one having the projecting piece 4, the amplitude is further reduced.

FIGS. 3A and 3B are explanatory views showing the swirling motion of the fluid 2 in the container 3, wherein FIG. 3A is a cross-sectional view of the vibration damping device, and FIG.

As shown in FIG. 3, in a vibration damping device formed by enclosing the fluid 2 in a cylindrical container 3 having no protruding piece 4 on its inner peripheral surface, the pole becomes larger as the excitation force increases. Vibrates, and the damping device vibrates greatly. At this time, the fluid 2 causes a swirling motion along the inner peripheral surface of the container 3. Due to this turning, the swing of the fluid 2 is hindered, and the damping performance is reduced. On the other hand, in the vibration damping device in which the projecting piece 4 is provided on the inner peripheral surface of the cylindrical container 3, the projecting piece 4 acts as a resistance to the turning of the fluid 2, so that the turning motion of the fluid 2 becomes small. . Therefore, the movement of the fluid 2 is limited to the swing, and the vibration damping performance is stable without lowering.

Further, in such a vibration damping device for the pole 1, since a plurality of projections 4 are provided at equal intervals on the inner peripheral surface of the container 3, the disturbance of the oscillation of the fluid 2 caused by the projections 4 is changed between right and left. Since the fluid 2 is symmetric, the fluid 2 can oscillate in a well-balanced manner, and the vibration damping effect against external vibration can be further improved. Further, the length of the protrusion 4 in the horizontal direction is set to １ ／ of the inner diameter of the container 3.
Since it is formed to be 0 or less, the swirling motion of the fluid 2 near the inner peripheral surface of the container 3 is effectively suppressed without greatly affecting the oscillation frequency of the fluid 2 in the container 3.

As described above, the plurality of protrusions 4 are provided at equal intervals on the inner peripheral surface of the container 3 so that the swirling motion of the fluid 2 is efficiently suppressed. 4 is not a plurality, is not continuous above and below the container 3, is not a quadrangular prism, or the horizontal length of the projection 4 is 1/50 of the inner diameter of the container 3. Even if it is not below, the damping effect can be expected. However, the number, shape,
Since there is a difference in the damping characteristics depending on the shape of the projecting piece 4 such as the size and the arrangement, it is necessary to set a desirable shape of the projecting piece 4 according to the required vibration damping property.

FIGS. 4A and 4B show another embodiment of the vibration damping device for the pole 1 of the present invention, which is different from FIG. 1, wherein FIG. 4A is a cross-sectional view of the vibration damping device, and FIG. .

In this vibration damping device, similarly to the vibration damping device shown in FIG. 1, the liquid level 2a is placed on a cylindrical container 3 having an inner diameter of 146 mm.
Is filled with the fluid 2 so as to fit at a height of 55 mm.
As the fluid 2, silicone oil having a kinematic viscosity of 50 cs is used.

The inner peripheral surface of the container 3 has eight projecting pieces 4
Are provided at equal intervals. The protruding piece 4 is formed in a quadrangular prism shape that is vertically continuous from substantially the center of the liquid level 2 a of the fluid 2 to the upper end of the container 3. The length of the protrusion 4 in the horizontal direction is 2.9 mm. This length is the inner diameter 146 of the container 3.
1/50 mm or less.

In such a vibration damping device for the pole 1, the projecting piece 4 provided near the liquid surface 2 a of the fluid 2 in the container 3
In order to efficiently suppress the swirling motion near the liquid surface 2a having a high moving speed, the damping effect against external vibration is improved. The frequency amplitude response in this case is substantially similar to the curve C in FIG. That is, providing the protruding piece 4 near the height of the liquid surface 2a of the fluid 2 is an element for improving the vibration damping effect.

[0033]

According to the first aspect of the present invention, when the container attempts to vibrate due to the vibration of the pole, the fluid sealed in the container swings to cancel the vibration and suppress the vibration of the pole. . When the oscillation frequency is matched with the natural frequency of the pole, the natural vibration component of the pole is reduced, so that the vibration of the pole is greatly reduced. And breakage can be prevented. In addition, since the protruding piece provided on the inner peripheral surface of the container acts as a resistance to the swirling motion of the fluid in the container, the swirling motion of the fluid can be reduced, and the movement of the fluid can be substantially limited to swing, so that the external The effect of damping vibration can be improved. Therefore, 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 oscillation of the fluid, there is also an effect that abnormal noise such as an impact sound does not occur.

According to the second aspect of the present invention, since a plurality of projections are provided at equal intervals on the inner peripheral surface of the container, the disturbance of the oscillation of the fluid due to the projections is symmetrical in the left-right direction, so that the oscillation is well balanced. Since it can move, the vibration damping effect against external vibration can be further improved.

According to the third aspect of the present invention, since the horizontal length of the projection is 1/50 or less of the inner diameter of the container,
The turning motion of the fluid in the vicinity of the inner peripheral surface of the container can be suppressed without greatly affecting the oscillation frequency of the fluid in the container. Therefore, since the movement of the fluid can be substantially limited to the swing, the vibration damping effect against the external vibration can be improved.

According to the fourth aspect of the present invention, since the protruding piece provided near the liquid surface of the fluid in the container efficiently suppresses the swirling motion near the liquid surface at which the moving speed of the fluid is high, the protrusion is provided outside the container. The effect of damping vibration can be further improved.

[Brief description of the drawings]

1A and 1B show an embodiment of a pole damping device according to the present invention, in which FIG. 1A is a sectional perspective view of a main part, and FIG. 1B is a longitudinal sectional view of an entire wall.

FIG. 2 is a graph of frequency amplitude response showing the performance of the pole damping device shown in FIG.

FIGS. 3A and 3B are explanatory diagrams showing a swirling motion of a fluid in a container 3, wherein FIG. 3A is a cross-sectional view of the vibration damping device, and FIG.

FIGS. 4A and 4B show another embodiment of the pole damping device of the present invention, which is different from FIG. 1, wherein FIG. 4A is a cross-sectional view of the damping device, and FIG.

FIG. 5 is a cross-sectional view showing an example of a conventional pole damping device.

6A and 6B show another conventional vibration damping device for a pole, in which FIG. 6A is a longitudinal sectional view of a main part, FIG. 6B is a transverse cross-sectional view of a main part, and FIG. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pole 2 Fluid 2a Liquid surface 3 Container 4 Projection piece 5 Ground 6 Arm 7 Lighting 8 Weight

Claims (4)

[Claims] 1. A vibration damping device comprising a fluid sealed in a container, said container mounted on an upper half of a pole, and having a swing frequency substantially equal to a natural frequency of the pole. A pole vibration damping device comprising a projection provided on a surface. 2. The pole vibration damping device according to claim 1, wherein a plurality of projecting pieces are provided at equal intervals on an inner peripheral surface of the container. 3. The container according to claim 1, wherein the length of the projection in the horizontal direction is less than 1/50 of the inner diameter of the container.
3. The pole damping device according to any one of claims 1 to 2. 4. The pole vibration damping device according to claim 1, wherein an upper portion of the projecting piece protrudes above a liquid level of the fluid in the container.