Vibration control mechanism

Abstract

To provide a vibration control mechanism capable of suppressing a resonance phenomenon at natural frequency of a vibration control object structure.SOLUTION: A vibration control device D is installed on a vibration control object structure S with predetermined natural frequency (f), can vibrate in a direction perpendicular to a vibration direction of a vibration control object structure S, and has natural frequency (f / 2) which is half the natural frequency (f) of the vibration control object structure S. The vibration control device D has: an arm section 11 which is installed on a lower surface side of the vibration control object structure S and vibrates with the vibration control object structure S as a fulcrum; a vibrating body D1 which is provided with a mass body 12 installed on the arm section 11 at a gravity center position; and an exciter body D2 which is installed on the mass body 12 so as to be flash with a vibration surface of the arm section 11 and vibrates the vibrating body D1 by moving vertically in sync with vertical vibration of the vibration control object structure S.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vibration control mechanism for suppressing vibrations occurring in a target structure. [Background technology]

[0002] For example, in beam- or plate-like structures that extend horizontally, such as bridges that allow roads and railways to pass over land obstacles, rivers, valleys, or the sea, and in tower-like structures such as high-rise buildings (structures to be controlled), the period of shaking during earthquakes or strong winds is long, and the shaking continues for some time even after the earthquake or strong winds have subsided.

[0003] Therefore, vibrations are controlled by installing vibration control means on the target structure. This device installs a vibrating body, which has an auxiliary mass attached via an arm that can vibrate with the target structure as a fulcrum, on the target structure, so that the vibrating body vibrates in a way that takes over the vibrations of the structure, thereby suppressing the resonance phenomenon around the natural frequency of the target structure.

[0004] Specifically, by installing vibration control means in which the direction of vibration of the vibrating body is perpendicular to the direction of vibration of the structure to be vibration-controlled and the vibration period of the vibrating body is half the natural period of the structure to be vibration-controlled, it becomes possible to reduce the vibration of the structure to be vibration-controlled.

[0005] In addition, technology for reducing vibrations of a structure to be damped using a vibration damping means that halves the vibration period of the vibrating body relative to the natural period of the structure to be damped is described in detail, for example, in Patent Publication No. 2020-148339. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2020-148339 Summary of the Invention [Problem to be solved by the invention]

[0007] Here, when vibration control means is installed on a structure to be controlled that is constructed to extend horizontally, such as a bridge, and that vibrates in a vertical direction (up and down vibration), the vibrating body is initially stable in a vertical position, and cannot vibrate as it is, even if the structure to be controlled vibrates up and down.

[0008] The present invention has been made in light of the above-mentioned technical background, and aims to provide a vibration control mechanism in which a vibrating body for controlling vibrations of a structure to be controlled that is constructed to extend horizontally can be vibrated by the vibrations of the structure to be controlled. [Means for solving the problem]

[0009] In order to solve the above problem, the vibration control mechanism of the present invention described in claim 1 comprises a target structure to be damped that is constructed extending horizontally and has a predetermined natural frequency (f), and vibration control means that is installed on the target structure to be damped and is capable of vibrating in a direction intersecting the vibration direction of the target structure to be damped and that has a natural frequency (f / 2) that is half the natural frequency (f) of the target structure to be damped, wherein the vibration control means comprises an arm section that is installed on the underside of the target structure to be damped and vibrates with the target structure side as a fulcrum, a vibrating body that has a mass body attached to the arm section at its center of gravity, and a vibrator that is attached to the mass body so as to be in a plane that coincides with the vibration plane of the arm section and moves up and down in response to the up and down vibration of the target structure to be damped, thereby vibrating the vibrating body.

[0010] The vibration damping mechanism of the present invention described in claim 2 is characterized in that, in the invention described in claim 1, the vibrator comprises a leaf spring or wire spring attached to the side of the mass body and bending and deforming in the vertical direction, and a weight portion fixed to the tip of the leaf spring or wire spring and vibrating up and down due to the bending deformation of the leaf spring.

[0011] The vibration damping mechanism of the present invention described in claim 3 is characterized in that, in the invention described in claim 1, the vibrator comprises a pair of coil springs attached to the sides of the mass body and arranged opposite each other in the vertical direction, and a weight portion held by being sandwiched between the coil springs and vibrating up and down due to the expansion and contraction of the coil springs.

[0012] The vibration control mechanism of the present invention described in claim 4 is characterized in that, in the invention described in any one of claims 1 to 3 above, the structure to be controlled is a double-supported structure supported at both ends, and the vibration control means is installed at a central position between the support positions at both ends of the structure to be controlled.

[0013] The vibration control mechanism of the present invention described in claim 5 is characterized in that, in the invention described in any one of claims 1 to 3 above, the structure to be controlled has a cantilever structure supported at only one end, and the vibration control means is installed at the free end opposite to the one end of the structure to be controlled. [Effects of the Invention]

[0014] According to the present invention, the weight vibrates up and down in response to the up and down vibrations of the structure to be damped, and the vibrating body vibrates in accordance with the vibrations of the weight, so that the vibrating body for damping the structure to be damped, which is constructed to extend horizontally, can vibrate in response to the vibrations of the structure to be damped. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing a vibration damping mechanism according to an embodiment of the present invention. [Figure 2] FIG. 10 is a schematic diagram showing a modified example of a vibration damping mechanism according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings for explaining the embodiment, the same components are generally designated by the same reference numerals, and repeated description thereof will be omitted.

[0017] Fig. 1 is a schematic diagram showing a vibration control mechanism according to one embodiment of the present invention. As shown in Fig. 1, a vibration control device (vibration control means) D constituting the vibration control mechanism of this embodiment is installed on the underside of a target structure S to be controlled, which is a beam-like or board-like structure extending horizontally, such as a bridge, which is an aerial structure built to allow roads, railways, etc. to pass over land obstacles, rivers, valleys, the sea, etc., and has the function of suppressing vertical vibrations of the target structure S to be controlled.

[0018] The vertical vibration of the target structure S is caused by strong winds due to earthquakes or typhoons, and in the case of bridges, by vehicles or trains passing over the bridge. These vertical vibrations have a long period of time, and continue for some time even after the earthquake or strong winds have subsided or the vehicle has passed.

[0019] The vibration damping device D of this embodiment for suppressing the vertical vibration of such a target structure S for vibration damping has a vibrating body D1 and a vibrating body D2.

[0020] In FIG. 1, the vibrating body D 1 is made up of an arm portion 11 and a mass body 12 .

[0021] The arm section 11 is installed on the underside of the target structure S to be damped and vibrates around the target structure S as a fulcrum. As shown in the figure, the arm section 11 is attached to a mounting base 13 fixed to the target structure S to be damped so as to be rotatable by a rotation shaft 14. This allows the arm section 11 to oscillate like a pendulum with the rotation shaft 14 as a fulcrum.

[0022] Mass body 12 is attached to arm portion 11. Since mass body 12 is attached to arm portion 11 at the center of gravity, vibrating body D1 hangs down vertically in a free state (a state without the influence of vibrating body D2, which will be described later).

[0023] Vibrator D2 is attached to mass body 12 so that it is in a plane that coincides with the vibration plane of the arm. Vibrator D2 includes leaf spring 21, a metal plate-shaped body that is attached to the side of mass body 12 and bends and deforms in the vertical direction, and weight part 22 that is fixed to the tip of leaf spring 21 and vibrates up and down due to the bending deformation of leaf spring 21.

[0024] In this way, since the weight portion 22 is attached to the mass body 12 via the leaf spring 21, the leaf spring 21 bends and deforms in the vertical direction in conjunction with the vertical vibration of the structure S to be damped, causing the weight portion 22 to vibrate up and down.

[0025] As mentioned above, when in a free state, the vibrating body D1 is stable in a hanging vertical position. Therefore, when the target structure S for vibration control simply vibrates up and down, the vibrating body D1 simply moves up and down along with the target structure S for vibration control, but does not start vibrating on its own.

[0026] Therefore, in this embodiment, a vibrator D2 is provided that is attached to the mass body 12. This vibrator D2 causes the leaf spring 21 to bend and deform in conjunction with the up and down vibration of the target vibration-damping structure S, which in turn causes the weight portion 22 to vibrate up and down, causing the vibrator D1 to vibrate in accordance with the vibration of the weight portion 22. As a result, the vibrator D1, which hangs down vertically in a free state, begins to vibrate spontaneously.

[0027] In the vibration control device D of this embodiment, the natural frequency generated by the vibration of the arm portion 11 is set to half the natural frequency of the vibration-control target structure S as described below, thereby suppressing the vertical vibration of the vibration-control target structure S.

[0028] It is desirable to install the vibration control device D in a location where the vibration of the target structure S is at its maximum. In other words, if the target structure S has a doubly supported structure (a structure supported at both ends), the vibration control device D is installed so that the vibrating body D1 is located at the center of the support positions at both ends of the target structure S, and if it has a cantilevered structure (a structure supported at only one end), the vibration control device D is installed at the free end opposite the supported end. In this embodiment, it is assumed that the target structure S is doubly supported, and the vibration control device D is attached so that the vibrating body D1 is located at the center of the two support positions of the target structure S.

[0029] Here, the target structure S to be damped has a predetermined natural frequency (f), and the vibration control device D installed on this target structure S has a natural frequency (f / 2) that is half the natural frequency (f) of the target structure S. By adjusting the effective length of the arm portion 11 (the distance between the center of the mass body 12 and the rotation axis 14), the natural frequency of the vibration control device D can be set to f / 2. In other words, by moving the mass body 12 to a predetermined position on the arm portion 11, the effective length of the arm portion 11 can be changed, and the frequency of the vibration control device D can be set to f / 2.

[0030] In this application, the natural frequency (f / 2) of the vibration control device D does not mean a natural frequency that is exactly half the natural frequency of the vibration-control target structure S (i.e., a natural frequency that is the natural frequency f of the vibration-control target structure S multiplied by 0.5), but means a natural frequency that is approximately half the natural frequency of the vibration-control target structure S. This is because, although the vibration control effect of the vibration-control target structure S becomes extremely large when the natural frequency of the vibration control device D is exactly half the natural frequency of the vibration-control target structure S, an effective vibration control effect can be obtained even if it is not exactly half.

[0031] The invention made by the inventor has been specifically described above based on the embodiments, but the embodiments disclosed in this specification are illustrative in all respects and are not limited to the disclosed technology. In other words, the technical scope of the present invention should not be interpreted restrictively based on the description of the above embodiments, but should be interpreted solely in accordance with the claims, and includes technologies equivalent to the technologies described in the claims and all modifications that do not deviate from the gist of the claims.

[0032] For example, in this embodiment, the weight portion 22 of the vibrator D2 is configured to vibrate up and down due to the bending deformation of the leaf spring 21, which is a metal plate-shaped body, but it may also be configured to vibrate up and down due to the bending deformation of a wire spring, which is a metal linear body (wire).

[0033] Furthermore, weight portion 22 only needs to vibrate up and down in accordance with the up and down vibration of target structure S to be damped, and does not necessarily have to be caused by deformation of leaf spring 21 or wire spring.

[0034] 2, a structure can be adopted in which a pair of coil springs 23a, 23b arranged opposite each other in the vertical direction are attached to the sides of mass body 12, and weight portion 22 is held between these coil springs 23a, 23b. In this structure, weight portion 22 vibrates up and down due to the expansion and contraction of coil springs 23a, 23b. [Industrial Applicability]

[0035] The vibration damping mechanism of the present invention can be applied to various horizontally extending structures that generate pitching (up-and-down vibrations) as structures to be damped. [Explanation of symbols]

[0036] 11 Arm section 12 mass body 13 Mounting base 14 Rotating shaft 21 Leaf spring 22 said weight part 22 Weight 23a, 23b Coil spring D. Vibration control device (vibration control means) D1 vibrating body D2 Oscillator S Structure to be controlled

Claims

1. A vibration-damping target structure that is constructed to extend horizontally and has a predetermined natural frequency (f); a vibration control means that is installed on the target structure, is capable of vibrating in a direction intersecting the vibration direction of the target structure, and has a natural frequency (f / 2) that is half the natural frequency (f) of the target structure, The vibration damping means is a vibrating body including an arm portion that is installed on the underside of the vibration-damping target structure and vibrates with the vibration-damping target structure side as a fulcrum, and a mass body that is attached to the arm portion at a center of gravity; a vibrator attached to the mass body so as to be in a plane that coincides with the vibration plane of the arm portion, and which moves up and down in response to the up and down vibration of the target structure to be vibration-damped, thereby vibrating the vibrator; A vibration damping mechanism comprising:

2. The vibrator is a leaf spring or a wire spring attached to a side of the mass body and bending and deforming in the vertical direction; a weight portion fixed to the tip of the leaf spring or the wire spring and vibrating up and down due to bending deformation of the leaf spring; 2. The vibration damping mechanism according to claim 1.

3. The vibrator is a pair of coil springs attached to the sides of the mass body and arranged opposite each other in the vertical direction; a weight portion that is held by being sandwiched between the coil springs and vibrates up and down due to expansion and contraction of the coil springs, 2. The vibration damping mechanism according to claim 1.

4. The target structure to be damped has a double-supported structure supported at both ends, The vibration damping means is installed at a center position between support positions at both ends of the vibration damping target structure.

4. The vibration damping mechanism according to claim 1, wherein the vibration damping mechanism is a vibration damping mechanism.

5. The target structure to be damped has a cantilever structure supported only at one end, The vibration damping means is installed at a free end opposite to the one end of the vibration damping target structure.

4. The vibration damping mechanism according to claim 1, wherein the vibration damping mechanism is a vibration damping mechanism.

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