JPH049931B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a viscous dynamic vibration absorber for suppressing vibrations of bridges, tower structures, spherical tanks, etc.

[Conventional technology] Bridges and tower-like structures generate vibrations due to wind or earthquakes, but vibrations must be suppressed during construction to ensure the safety of the structure and to ensure the safety of workers and prevent seasickness. It is important to suppress vibrations, and various vibration damping measures have been implemented in the past, such as those described below.

In FIG. 6, wires b are stretched radially on the top of structure a, and the hysteresis of wires b is used to change the stiffness of structure a. A damping device c is attached to the tip or an intermediate position of the wire b to control vibration (arrow d). However, this method requires large-scale equipment and is accompanied by considerable difficulty or limitations in implementing countermeasures, especially in the case of offshore structures.

Fig. 7 shows a so-called pendulum method (or seismometer method) in which a weight f is attached to a structure a via hanging materials e and e, and a damping device c is placed between the hanging materials e and e.
Vibration energy is absorbed by utilizing the damping effect due to shear deformation of the damping device c when the weight f makes a pendulum movement. However, in this method, the natural frequency of structure a,
Alternatively, depending on the order of vibration, the device may become large or may not be effective.

Further, in FIG. 8, a structure a is connected to a support g via a damping device c such as a hydraulic damper. However, this method has problems such as the damping effect is small when the amplitude of vibration is small, and the method of connecting the structure a and the support g is complicated.

[Problems to be Solved by the Invention] In view of the above-mentioned problems, the present invention provides a vibration absorbing device that is small in size, can be easily attached to a structure, and can be adapted to structures having arbitrary vibration characteristics. The purpose is to provide equipment.

[Means for Solving the Problems] The viscous dynamic vibration absorber of the present invention for solving the above-mentioned problems comprises: a hollow cylindrical body having a sufficiently large weight and containing a viscous body therein; The rotary shaft is provided with a rotary shaft that penetrates through the center and has an agitator provided in the inner part of the cylinder, and a support that rotatably supports the rotary shaft, and the rotary shaft is rotatably supported by the cylinder. be.

[Function] When the structure to which the vibration absorber of the present invention is attached vibrates horizontally, the inertia of the cylinder is sufficiently large, so the cylinder is slightly displaced relative to the structure, while the rotating shaft is supported according to the displacement of the water. Rolling on a surface, the agitating body agitates the viscous material and attenuates the vibration energy. Since there is no need to stretch wires or lower weights like in the past, the device can be made smaller, and the vibration absorber can be installed at the desired location, such as on the top, bottom, or side of the structure. It can be widely applied without being limited to the type of structure.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. Figures 1 to 4 show a first embodiment of the present invention, in which the vibration absorber has a sufficiently large weight, is made in a sealed structure, and is filled with a viscous material 1 (for example, lubricating oil). a hollow cylindrical body 2;
A rotating shaft 5 that passes through the center of the cylinder 2 in the longitudinal direction, is rotatably supported by a bearing 3 provided in the penetrating part, and has blades 4 attached to the inside of the cylinder, and both ends of the rotating shaft All of these components are housed in a box 8 for safety purposes, and fittings for connecting lifting ropes (not shown) are installed at appropriate locations on the pedestal 7. installed.

The vibration absorber is arranged approximately horizontally on the top, inside, outside, side, etc. of the structure 9 so that the axis i of the rotary shaft 5 faces in a direction perpendicular to the vibration direction. They can also be arranged in parallel.

The radius of curvature R of the support surface 6 is set in consideration of the vibration characteristics (e.g. natural frequency or amplitude) of the target structure 9. For example, if the natural frequency of the structure is high, the radius of curvature R Set R small.

Further, in order to enhance the damping effect, it is preferable to increase the rotational speed of the rotating shaft 5 while the vibration absorber is in operation, and for this reason, it is preferable that the diameter of the rotating shaft 5 is as small as possible.

Next, the operation of this vibration absorber will be explained. Now, when the structure 9 vibrates horizontally (arrow j), the cylindrical body 2 tends to remain in its original position due to its large weight, so the horizontal relative change between the cylindrical body 2 and the structure 9 is slight. On the other hand, the rotating shaft 5 rolls on the support surface 6 in response to the horizontal displacement, and the blades 4 stir the viscous body 1 and absorb vibration energy. Therefore, horizontal vibration of the structure 9 is suppressed.

Next, a second embodiment of the present invention is shown in FIG.
This example shows the arrangement for absorbing vibrations in the vertical direction of the structure 9a, and uses a suspension spring 11 having the same natural frequency as the natural frequency of the structure 9a to move the cylindrical body 2 to the structure 9a. Suspended from the bottom of the cylinder body 2
A pinion 12 is attached to both ends of a rotating shaft passing through the structure 9a, and the pinion 12 is engaged with a rack 13 fixed to the structure 9a.Other than that, there is no difference from the first embodiment.

When the structure 9a vibrates in the vertical direction, the cylindrical body 2 is sensitively synchronized via the suspension spring 11 and moves up and down (arrow m). This vertical movement makes it easy13.
The rotating shaft rotates via the pinion 12, and the damping mechanism inside the cylinder body 2 operates.

Note that the present invention is not limited to the above-described embodiments; for example, the cross section of the cylinder may be a regular polygon instead of a circle, and the supporting surface of the support is not limited to an arc; It goes without saying that various other changes may be made without departing from the gist of the present invention, such as that it may be formed with a quadratic curved surface or a cubic or higher curved surface.

[Effects of the Invention] As described above, the viscous dynamic vibration absorber of the present invention exhibits the following excellent effects.

() Since the structure is such that the cylindrical body is supported on a support via the rotating shaft, the external dimensions are compact and it can be placed on the top, inside, outside, or at the bottom of the side of the structure, allowing for easy installation location selection. is free.

() It is possible to adapt to various vibration forms simply by changing the curvature of the pedestal support surface.

() Multiple absorbers can be used in parallel, so
Combined with the effects mentioned in the previous paragraph (), the combination of a cylinder and a rotating shaft can be widely applied to various structures.
Standardization can be achieved.

[Brief explanation of drawings]

1 to 4 show a first embodiment of the present invention, in which FIG. 1 is a cutaway side view of a vibration absorber, and FIGS. 2 and 3 are arrows taken from the − direction and − direction in FIG. The perspective view, Fig. 4, is − in Fig. 2.
FIG. 5 is a side view showing a schematic structure of a vibration absorber according to a second embodiment of the present invention, and FIGS. 6 to 8 are explanatory diagrams of a conventional vibration damping device. be. In the figure, 1 is a viscous body, 2 is a cylindrical body, 4 is a blade, 5 is a rotating shaft, 7 is a pedestal, and 13 is a rack.

Claims (1)

[Claims] 1. A hollow cylinder with a sufficiently large weight that accommodates a viscous material inside, a rotating shaft that penetrates the center of the cylinder and has an agitating body in the inside of the cylinder, and a rotary shaft that can freely roll. 1. A viscous dynamic vibration absorber, comprising: a support for supporting the rotary shaft; and the rotary shaft is rotatably supported by the cylinder.