JPS63147072A - Vibration damper - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a vibration damping device for suppressing horizontal vibrations occurring in tower-like structures such as long bridge towers, high-rise buildings, and chimneys.

[Prior Art] Conventionally, a pendulum-type dynamic vibration absorber or a pendulum-type dynamic vibration absorber with a spring is generally used as a vibration damping device for the tower-like structure described above.

FIG. 5 is a schematic diagram of a conventional pendulum-type dynamic vibration absorber disclosed in Japanese Patent Application Laid-open No. 59-97342. A weight 4 is attached to the rod arm 3, and a damper 5 made of a hydraulic damper is connected to the middle of the rod arm 3.

Therefore, by adjusting the mounting position of the weight 4 and the length of the rod arm 3, the frequency of the pendulum made up of the rod arm 3 and the weight 4 can be made to match the natural frequency of the structure 1. Then, when an external force is applied to the structure 1 in the vibration direction of the rod arm 3, the resonance kinetic energy is converted into thermal energy by the attenuator 5 connected to the rod arm 3 and scattered, so that the horizontal This allows vibrations to be damped as quickly as possible.

[Problems to be Solved by the Invention] However, such a pendulum-type dynamic vibration absorber has an extremely simple structure with a simple swing preconfiguration, and therefore the frequency can be adjusted only by changing the mounting position of the weight 4. The adjustment range is narrow and there are many practical problems.

Therefore, as shown in FIG. 6, a spring-equipped pendulum type dynamic vibration absorber has been devised in which a torsion spring 6 or the like is attached to the pivot portion of the rod arm 3. However, especially in the case of a torsion spring, if there is play in the attachment part of the torsion spring 6, the vibration frequency will not be constant, making it extremely difficult to process and attach the spring end with precision.

Therefore, there is a problem of high cost.

The present invention was made in order to solve such problems, and an object of the present invention is to provide a vibration damping device that is inexpensive and can sufficiently cope with a wide frequency adjustment range.

[Means for Solving the Problems] A vibration damping device according to the present invention includes a rod arm swingably suspended from a structure, a weight attached to the rod arm, and an intermediate portion of the rod arm. A pair of coil springs having the same spring constant are symmetrically coupled to the middle of the rod arm.

In a preferred embodiment of the present invention, the base ends of the pair of coil springs are installed close to the fulcrum side of the rod arm so that the spring axes are V-shaped.

In a further preferred embodiment of the present invention, the base ends of the pair of coil springs are installed on a circumference whose diameter is the distance from the fulcrum of the rod arm to the connection point of the coil spring to the rod arm.

[Operation] In the vibration damping device according to the present invention, a pair of coil springs having the same spring constant are installed symmetrically in the middle of the rod arm in the conventional pendulum type dynamic vibration absorber, so that the length of the pendulum and the coil spring can be adjusted. The vibration frequency of the system can be freely adjusted by changing the mounting position and angle of the system.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention. In this case, the device differs from the device shown in FIG. 5 in that a pair of coil springs 8, 8a are horizontally and symmetrically attached to the middle of the rod arm 3.

FIG. 2 is a schematic configuration diagram showing another embodiment of the present invention.

In this case, the mounting position 9 at the base end of the coil spring 8.8a,
The mounting angle is such that the spring axis 9a is brought closer to the fulcrum O side, which is the center of swing of the rod arm 3, and the spring axis forms a V-shape.

This pendulum has coil springs 8 and 8a with the same spring constant.
If it vibrates in a plane containing , the equation of motion at that time is given by the following equation.

・・・・・・・・・ (1) Here, I: Pendulum inertia rate θ: Pendulum swing angle M: Weight mass g: Gravitational acceleration H: Pendulum length g: Coil spring installation length β Spring constant Po: Initial tension of the coil spring a: Distance from the fulcrum O of the pendulum to the coupling point A of the coil spring The horizontal distance 0 [θ3] from the attachment points B and C to the pendulum fulcrum O is the meaning of θ3 and higher-order terms.

In the above equation, the term θ2 does not appear, and this is an effect due to the two coil springs being symmetrically attached to the pendulum, so it can be assumed that the system vibrates linearly. Moreover, the period T is...(2).

In addition, in the case of Fig. 2, the amplitude of the coil spring is h-aθ
sinβ, and the spring amplitude h −aθ in the case of Fig. 1
Since it is smaller than , the mounting width W of the spring can be made smaller.

Furthermore, FIG. 3 shows another embodiment of the present invention, in which the diameter of the proximal attachment points B and C of the coil spring is the distance from the fulcrum point 0 to the coil spring connection point A. It is located on the circumference. If the base end of the coil spring is fixed on the circumference with OA as the diameter in this way, 8.2 X''' 2 g.

, and the term of the initial tension of the spring disappears. Therefore, the period T is not affected by the initial tension of the spring and becomes simple from equation (2).

Next, the specific embodiment of FIG. 2 is shown in FIGS. 4(a) to 4(C). As shown in the figure, the rod arm 3 has its base end pivotally connected to a rotary shaft 2 supported by a bearing 12 on a support frame 11 on a structure, and is swingably suspended. A hydraulic damper constituting the damper 5 is interposed between the rod arm 3 and the support frame 11 near its base end. Symmetrical 2
The coil springs 8, 8a are interposed between the rod arm 3 and the support frame 11 in a V-shape with an installation angle of 45''. It is adjustable within the range of the rod arm 3.

[Effect of the invention〕 According to the present invention, the following effects can be obtained.

(1) Since it is a coil spring, it is easy to achieve high machining accuracy and installation accuracy, and therefore the vibration damping device is inexpensive.

(2) By attaching the coil springs to the left and right with the rod arm of the pendulum as the axis of symmetry, the linear vibration of the pendulum is almost satisfied regardless of the attachment position of the spring.

(3) Vibration of the system can be easily adjusted by changing the pendulum length, spring mounting position, and mounting angle.

(4) The frequency of the system can be adjusted by the initial tension of the spring.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of the present invention, FIG. 2 is a schematic diagram of another embodiment, FIG. 3 is a schematic diagram of another embodiment, and FIGS. ) shows the specific embodiment of FIG. 2, in which FIG. 2(a) is a front view, FIG. 2(b) is a plan view, and FIG. 2(c) is a side view. 5 and 6 are schematic configuration diagrams of conventional examples, respectively. 1... Structure 2... Pivot 3... Rod arm 4... Weight 5... Attenuator
8, 8a... Coil spring agent Patent attorney Souji Sasaki 1st diagram Do structure Gogu 2゛J Takumi 6, BO: Coil spring 2nd diagram 4 (O) (b) (C)

Claims (3)

[Claims] (1) A rod arm swingably suspended from a structure,
A weight attached to the rod arm, and an attenuator connected to the middle of the rod arm,
A vibration damping device characterized in that a pair of coil springs having the same spring constant are symmetrically coupled to the middle of the rod arm. (2) The control according to claim 1, characterized in that the base ends of the pair of coil springs are installed close to the fulcrum side of the rod arm so that the spring axes thereof are inclined in a crescent shape. Shaking device. (3) The base ends of the pair of coil springs are installed on a circumference whose diameter is the distance from the fulcrum of the rod arm to the connection point of the coil spring to the rod arm. Vibration damping device as described in section.