Vibration control mechanism

Abstract

To vibrate a vibrator damping a damping object structure extending in a horizontal direction with vibration of the damping object structure.SOLUTION: A damping device D installed on a damping object structure S has: a vibrator D1 comprising an arm part 11 vibrated on the damping object structure S side as a fulcrum, and a mass body 12 mounted to the arm part 11, and suspended in a vertical direction under a free condition; a magnet 13 installed on the arm part 11 while a direction of a magnetic flux is directed to a vibration direction of the arm part 11; and a first magnet holding part 21 and a second magnet holding part 22 installed at positions opposite to each other across the arm part 11 in a direction coincident with a vibration face of the arm part 11, respectively holding magnets 21a, 22a so that magnetic poles opposite to the magnet 13 of the arm part 11 have the same polarity, and restraining a vibration width of the arm part 11 by repulsion of the magnets. An interval L1 between the magnet 13 and the magnet 21a and an interval L2 between the magnet 13 and the magnet 22a are not equal while the arm part 11 is in a vertical direction.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 problems, the vibration control mechanism of the present invention as set forth in claim 1 comprises a target structure to be damped that is constructed extending in the horizontal direction 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 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 portion that is installed on the underside of the target structure to be damped and vibrates with the target structure side as a fulcrum, and a mass body attached to the arm portion at the position of its center of gravity, and the vibrating body hangs down in the vertical direction in a free state, and a vibration control means that has a magnetic flux direction The magnetic head has a magnet installed on the arm portion facing the vibration direction of the arm portion, and a first magnet holding portion and a second magnet holding portion that are installed in a direction that coincides with the vibration plane of the arm portion and on opposite sides of the arm portion, and hold the magnet so that the magnetic poles facing the magnet in the arm portion are the same polarity, thereby regulating the vibration amplitude of the arm portion by the repulsion of the magnets, and is characterized in that the distance between the magnet in the arm portion and the magnet in the first magnet holding portion and the distance between the magnet in the arm portion and the magnet in the second magnet holding portion are arranged unequal when the arm portion is in the vertical direction.

[0010] The vibration control mechanism of the present invention as set forth in claim 2 comprises a target structure to be damped, constructed to extend in the horizontal direction and having a predetermined natural frequency (f), and vibration control means installed on the target structure to be damped, capable of vibrating in a direction intersecting the vibration direction of the target structure to be damped, and having 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 installed on the underside of the target structure to be damped and vibrating with the target structure side as a fulcrum, and a mass body attached to the arm section with its center of gravity shifted, and which is tilted relative to the vertical direction in a free state. The vibrating body has a vibrating body that hangs down in an oblique direction, and a first magnet holding portion and a second magnet holding portion that are respectively installed in a direction that coincides with the vibration plane of the arm portion and on opposite sides of the arm portion, and that hold magnets so that the magnetic poles facing the magnets in the arm portion are the same polarity, thereby regulating the vibration amplitude of the arm portion by the repulsion of the magnets, and the spacing between the magnets in the arm portion and the magnets in the first magnet holding portion and the magnets in the arm portion and the magnets in the second magnet holding portion are arranged at equal intervals when the arm portion is in the vertical direction.

[0011] The vibration control mechanism of the present invention described in claim 3 is characterized in that, in the invention described in claim 1 or 2 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.

[0012] The vibration control mechanism of the present invention described in claim 4 is characterized in that, in the invention described in claim 1 or 2 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]

[0013] According to the present invention, the acceleration acting on the vibrating body is shifted from the center of the vibration angle of the vibrating body, so that the vibrating body for vibration-damping the target structure, which is constructed extending horizontally, can vibrate in response to the vibration of the target structure. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic diagram showing a vibration damping mechanism according to a first embodiment of the present invention. [Figure 2] FIG. 10 is a schematic diagram showing a vibration damping mechanism according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] 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.

[0016] (Embodiment 1)

[0017] Fig. 1 is a schematic diagram showing a vibration control mechanism according to embodiment 1 of the present invention. As shown in Fig. 1, a vibration control device (vibration control means) D constituting the vibration control mechanism of embodiment 1 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 that 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 the first embodiment for suppressing the vertical vibration of such a target structure S for vibration damping has a vibrating body D1 and a vibration generating part D2.

[0020] In Figure 1, the vibrating body D1 comprises an arm portion 11 that is installed on the underside of the vibration-damping target structure S and vibrates with the vibration-damping target structure S as a fulcrum, a mass body 12 attached to the lower end of the arm portion 11, and a magnet 13 that is installed on the arm portion 11.

[0021] 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 where there is no influence of repulsion between magnets, which will be described later). Arm portion 11 is attached to mounting base 14, which is fixed to target vibration-damping structure S, so that it can rotate by pivot 15. This allows arm portion 11 to oscillate like a pendulum, with pivot 15 as the fulcrum.

[0022] Furthermore, the magnet 13 is installed on the arm portion 11 with the direction of the magnetic flux facing the vibration direction of the arm portion 11 (that is, with the two poles of the magnet facing the vibration direction of the arm portion 11).

[0023] Vibration generating unit D2 is composed of first magnet holder 21 and second magnet holder 22, which are respectively installed in a direction coinciding with the vibration plane of arm unit 11 and on opposite sides of arm unit 11, and magnets 21a and 22a held by first magnet holder 21 and second magnet holder 22. First magnet holder 21 and second magnet holder 22 hold magnets 21a and 22a so that the magnetic poles facing magnet 13 installed on arm unit 11 are the same polarity (for example, if the magnetic pole facing first magnet holder 21 of magnet 13 installed on arm unit 11 is an S pole, first magnet holder 21 holds magnet 21a so that the S pole faces magnet 13), and the repulsion between the magnets regulates the vibration amplitude of arm unit 11.

[0024] As shown in the figure, the first magnet holder 21 and the second magnet holder 22 are attached to the arm 11 side end of a bolt 32 that is attached to and passes through a bracket 31 that is fixed to the target structure S to be damped. A nut 33 for fixing the bolt 32 to the bracket 31 is threadedly engaged with the bolt 32. By adjusting the position at which the bolt 32 and the nut 33 are threadedly engaged, the length by which the bolt 32 protrudes toward the arm 11 when fixed to the bracket 31 can be freely set.

[0025] 1, in the first embodiment, the length by which bolt 32 of first magnet holder 21 protrudes toward arm portion 11 is shorter than the length by which bolt 32 of second magnet holder 22 protrudes toward arm portion 11. In other words, distance L1 between magnet 13 of arm portion 11 and magnet 21a of first magnet holder 21 and distance L2 between magnet 13 of arm portion 11 and magnet 22a of second magnet holder 22 are unequal when arm portion 11 is oriented vertically. As a result, as shown in the figure, vibrating body D1, which hangs down vertically in a free state, is slightly inclined toward first magnet holder 21.

[0026] By adopting such a structure, the balance of the vibrating body D1, which hangs down vertically in a free state, is lost (the acceleration acting on the vibrating body D1 is shifted from the center of the vibration angle of the vibrating body D1), and a component force (restoring force) is generated in the vibration direction of the vibrating body D1 in the initial state (a state in which the vibrating body D1 is slightly tilted).Therefore, when the vibration-controlled structure S, which is constructed to extend horizontally, begins to vibrate, the vibrating body D1 begins to vibrate spontaneously.

[0027] In the vibration control device D of embodiment 1, 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 the first embodiment, the target structure S is assumed to be 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 15), 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] (Embodiment 2)

[0032] 2 is a schematic diagram showing a vibration damping mechanism according to a second embodiment of the present invention. A vibration damping device (vibration damping means) D constituting the illustrated vibration damping mechanism of the second embodiment differs from the vibration damping device (vibration damping means) D of the first embodiment in that mass body 12 is attached to arm portion 11 with its center of gravity shifted, and that the length of projection of bolt 32 of first magnet holder 21 toward arm portion 11 is the same as the length of projection of bolt 32 of second magnet holder 22 toward arm portion 11 (i.e., distance L1 between magnet 13 of arm portion 11 and magnet 21a of first magnet holder 21, and distance L2 between magnet 13 of arm portion 11 and magnet 22a of second magnet holder 22 are equidistant when arm portion 11 is oriented vertically). In other respects, the vibration damping device (vibration damping means) D is configured similarly to the vibration damping device D of the first embodiment.

[0033] That is, since the mass body 12 is attached to the arm portion 11 with the center of gravity shifted, the vibrating body D1 hangs down in a direction inclined relative to the vertical direction in a free state (a state in which there is no influence of repulsion between the magnets).

[0034] Furthermore, since the distance L1 between the magnet 13 of the arm portion 11 and the magnet 21a of the first magnet holding portion 21 and the distance L2 between the magnet 13 of the arm portion 11 and the magnet 22a of the second magnet holding portion 22 are arranged at equal intervals when the arm portion 11 is in the vertical direction, the vibrating body D1, which hangs down in a direction inclined to the vertical direction in the free state, hangs down in the vertical direction.

[0035] By adopting such a structure, the balance of the vibrating body D1, which hangs down in a direction inclined relative to the vertical direction in a free state, will be lost (as with the vibration control device D in the first embodiment described above, the acceleration acting on the vibrating body D1 will be shifted from the center of the vibration angle of the vibrating body D1), and a component force (restoring force) will be generated in the vibration direction of the vibrating body D1 in the initial state (when the vibrating body D1 hangs down in the vertical direction), so when the structure S to be vibration-controlled, which is constructed extending horizontally, begins to vibrate, the vibrating body D1 will begin to vibrate spontaneously.

[0036] As a result, even in the vibration control device D of embodiment 2, the natural frequency generated by the vibration of the arm portion 11 can be set to half the natural frequency of the vibration control target structure S, thereby suppressing the vertical vibration of the vibration control target structure S.

[0037] 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.

[0038] For example, vibration control effects can be achieved by setting the natural frequency of the vibration control device D to half (f / 2) of the natural frequency (f) of the structure S to be controlled, but the "half of the natural frequency" here does not necessarily have to be half in the strict sense. [Industrial Applicability]

[0039] 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]

[0040] 11 Arm section 12 mass body 13 Magnet 14 Mounting base 15 Rotating shaft 21 First magnet holder 21a Magnet 22 Second magnet holder 22a Magnet 31 Bracket 32 volts 33 Nut D. Vibration control device (vibration control means) D1 vibrating body D2 Excitation part L1,L2 interval 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 that includes 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 the center of gravity, and that hangs down vertically in a free state; a magnet disposed on the arm portion such that the direction of magnetic flux is oriented in the vibration direction of the arm portion; a first magnet holder and a second magnet holder, which are respectively installed in a direction coinciding with the vibration plane of the arm portion and at positions opposite to each other with the arm portion in between, and which hold a magnet such that magnetic poles facing the magnet of the arm portion are of the same polarity, thereby regulating the vibration amplitude of the arm portion by the repulsion of the magnets; the magnet of the arm portion and the magnet of the first magnet holder, and the magnet of the arm portion and the magnet of the second magnet holder are disposed at unequal intervals when the arm portion is oriented vertically; A vibration damping mechanism characterized by:

2. 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 that includes 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 with its center of gravity shifted, and that hangs down in a direction inclined with respect to the vertical direction in a free state; a first magnet holder and a second magnet holder, which are respectively installed in a direction coinciding with the vibration plane of the arm portion and at positions opposite to each other with the arm portion in between, and which hold a magnet such that magnetic poles facing the magnet of the arm portion are of the same polarity, thereby regulating the vibration amplitude of the arm portion by the repulsion of the magnets; the magnet of the arm portion and the magnet of the first magnet holder, and the magnet of the arm portion and the magnet of the second magnet holder are disposed at equal intervals when the arm portion is oriented vertically; A vibration damping mechanism characterized by:

3. 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.

3. The vibration damping mechanism according to claim 1 or 2.

4. 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.

3. The vibration damping mechanism according to claim 1 or 2.

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