JPH0231256B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dynamic vibration absorber for suppressing resonance of a structure.

For example, recently constructed pedestrian bridges tend to have lower rigidity and vibration damping than conventional bridges due to their simplified structures, and these vibrations often cause discomfort to pedestrians. This phenomenon occurs not only in pedestrian bridges but also in bridges and other structures, and the low-frequency vibrations caused by this cause discomfort to nearby residents, so early resolution is currently an important issue. It's summery.

In order to suppress the resonance of such structures, various dynamic vibration absorbers have been proposed in the past, and some of them are in practical use. This dynamic vibration absorber is a one-degree-of-freedom vibration system that has a resonant frequency equal to the resonant frequency of the structure whose resonance is to be suppressed (hereinafter simply referred to as the structure), and by installing it on the structure, The resonance amplitude of objects can be reduced. Now, to simplify the explanation of this principle,
As shown in FIG. If a dynamic vibration reducer 5 consisting of is added, its configuration can be expressed as c.

By the way, conventional dynamic vibration absorbers installed in structures such as civil engineering and architecture have generally had the structure shown in Figure 2 in order to achieve the functions shown in Figure 1. . In the figure, reference numeral 11 denotes a weight corresponding to the mass 6 in FIG. 14 is Figure 1b
A coil spring 15 corresponds to the spring 7, and an oil damper 15 corresponds to the damping 8.

However, a dynamic vibration absorber with such a structure,
A high-performance bearing 13 is required that does not interfere with the minute vertical movement of the weight 11, and maintenance work must be performed from time to time during long-term use.
Furthermore, since the spring function and the damping function are provided by separate mechanisms, there are many problems such as a complicated structure and troublesome assembly and adjustment.

The present invention was made to solve the above-mentioned conventional problems, and provides an inexpensive dynamic vibration absorber that not only has a simple structure and is easy to assemble and adjust, but also has high performance and does not require maintenance work. The purpose is to provide the following.

In order to achieve the above object, the dynamic vibration absorber according to the present invention has a weight supported in a casing via a vibration isolating member mainly composed of rubber, and has a vibration degree of freedom of substantially 1. In addition, the vibration isolating member is characterized in that it functions as a spring and a damper. The present invention will be explained below using the drawings.

FIG. 3 is a plan view of an embodiment of the present invention, and FIG. 4 is a sectional view taken along the line AA. In the figure, reference numeral 21 denotes a weight, which is supported in a suspended state within a metal casing 22 by eight vibration isolating members 23, which are arranged around the weight in two layers, four each in a plane. As shown in FIG. 5, for example, this vibration isolating member 23 includes bolts 26 attached to both ends of a round vibration isolating rubber 24 formed in a cylindrical shape using an elastic material such as rubber.
26 are bonded together with a strong adhesive, and are attached to the weight 21 and the casing 22 via bolts 26, 26.

The vibration isolating member 23 configured in this manner can have lower rigidity in shear in the direction perpendicular to the axial direction than in tension and compression in the axial direction. Therefore, the eight vibration isolating members 23 arranged as shown in FIGS.
3 acts in the shear direction, and four vibration isolating members 23 act in the tensile and compressive directions in the X and Y directions, respectively. Furthermore, for rotations around the X-axis and around the Y-axis, four vibration isolation members act in the tension and compression directions, so the five degrees of freedom of the weight 21 (X, Y, Z directions and the X-axis , rotation around the Y axis)
Of these, the rigidity in the Z direction can be made the smallest.

Therefore, the weight 21 supported by these vibration isolating members 23 can be regarded as a one-degree-of-freedom vibration system that can move almost only in the Z direction near the Z-direction resonance frequency as a dynamic vibration absorber. Note that there is no need to consider the degree of freedom of rotation around the Z-axis, since the structure in which the dynamic vibration absorber is installed generally does not have this degree of freedom. It goes without saying that the anti-vibration rubber 24 has the function of the coil spring 14 shown in FIG. It can also have the function of a damper 15.

In the above embodiment, the weight having a rectangular cross section is arranged inside the rectangular casing, but either or both of them may be circular. Further, although a case has been shown in which a disc with bolts is attached to both ends of the vibration-proof rubber, the bolts may be attached by other means. Further, although the case where the weight is supported using eight vibration isolating members has been described, the number can be increased as appropriate depending on the situation.

As is clear from the above description, the present invention does not require complicated mechanisms such as guide rails, bearings, and oil dampers, and can be manufactured, assembled, adjusted, maintained, etc. with an extremely simple configuration. This makes it possible to realize a dynamic vibration absorber that is much easier to use, has high performance, and is inexpensive.

[Brief explanation of drawings]

Figures 1a, b, and c are schematic diagrams showing the principle of a dynamic vibration absorber, Figure 2a is a plan view showing an example of a conventional dynamic vibration absorber, Figure b is a longitudinal sectional view, and Figure 3 is an embodiment of the present invention. FIG. 4 is a sectional view taken along line A-A, and FIG. 5 is a perspective view of an embodiment of the vibration isolating member used in the present invention. 21: Weight, 22: Casing, 23: Anti-vibration member, 24: Anti-vibration rubber, 26: Bolt.

Claims (1)

[Claims] 1. A casing, a weight disposed within the casing, and a plurality of cylindrical elastic members arranged in a plane around the weight to support the weight in a suspended state within the casing. A dynamic vibration absorber comprising a vibration isolating member consisting of: