Vibration control mechanism

Abstract

To vibrate a vibrator for 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; first and second tension coil springs D2a, D2b respectively locked to the arm part 11 at one ends so that they are at positions opposite to each other across the arm part 11 in a direction coincident with a vibration face of the arm part 11, and having the same spring constant; and first and second lock members D3a, D3b for respectively locking other ends of the first and second tension coil springs D2a, D2b. A distance L1 between two locking positions of the first tension coil spring D2a and a distance L2 of two locking positions of the second tension coil spring D2b are not equal to each other.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 mass body that is aligned with the vibration plane of the arm portion. the first tension coil spring and the second tension coil spring having the same spring constant, one end of which is engaged with the arm portion in a direction perpendicular to the arm portion and at a position opposite to the arm portion with the arm portion in between, and a first locking member and a second locking member which lock the other end of the first tension coil spring and the second tension coil spring, respectively, wherein the distance between the locking position of the arm portion of the first tension coil spring and the locking position of the first locking member and the distance between the locking position of the arm portion of the second tension coil spring and the locking position of the second locking member are unequal.

[0010] In order to solve the above problems, 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 the vibrating body hangs down in a direction inclined with respect to the vertical direction in a free state, and the arm section the first tension coil spring and the second tension coil spring having the same spring constant, one end of which is engaged with the arm portion in a direction that coincides with the vibration plane of the spring and at a position opposite to each other across the arm portion, and a first locking member and a second locking member that lock the other end of the first tension coil spring and the second tension coil spring, respectively, wherein the distance between the locking position of the arm portion of the first tension coil spring and the locking position of the first locking member is equal to the distance between the locking position of the arm portion of the second tension coil spring and the locking position of the second locking member.

[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, it has a magnet installed on the arm section with the direction of magnetic flux directed in the vibration direction of the arm section, and a first magnet holding section and a second magnet holding section that are each installed in a direction that coincides with the vibration plane of the arm section and on opposite sides of the arm section, and hold the magnet so that the magnetic poles facing the magnet in the arm section are the same polarity, thereby regulating the vibration amplitude of the arm section through the repulsion of the magnets, and the distance between the magnet in the arm section and the magnet in the first magnet holding section and the distance between the magnet in the arm section and the magnet in the second magnet holding section are arranged at equal intervals when the arm section is in the vertical direction.

[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 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 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]

[0014] 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 damping the vibration of the target structure that is constructed extending horizontally can vibrate with the vibration of the target structure. [Brief explanation of the drawings]

[0015] [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. [Figure 3] FIG. 10 is a schematic diagram showing a vibration damping mechanism according to a third embodiment of the present invention. [Figure 4] 10 is a graph showing the relationship between the tension coil spring and the deflection angle of the vibrating body. 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] (Embodiment 1)

[0018] 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.

[0019] 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.

[0020] The vibration damping device D of the first embodiment for suppressing the up-and-down vibration of such a target structure S for vibration damping includes a vibrating body D1, a tension coil spring D2, and a locking member D3.

[0021] In Fig. 1, vibrating body D1 comprises an arm 11 that is installed on the underside of a target structure S to be damped and vibrates around the target structure S as a fulcrum, and a mass 12 attached to arm 11. Since mass 12 is attached to arm 11 at its center of gravity, vibrating body D1 hangs down vertically in a free state (a state in which it is not constrained by the spring force of a tension coil spring D2, which will be described later). Arm 11 is attached to a mounting base 13 that is fixed to the target structure S to be damped so that it can rotate about a rotation shaft 14. This allows arm 11 to oscillate like a pendulum, with rotation shaft 14 as a fulcrum.

[0022] The tension coil spring D2 is made up of a first tension coil spring D2a and a second tension coil spring D2b, each of which has one end engaged with the arm portion 11 in a direction that coincides with the vibration plane of the arm portion 11 and at positions opposite each other across the arm portion 11. The first tension coil spring D2a and the second tension coil spring D2b have the same spring constant, and are engaged by having one end hooked onto hooks 11a-1 provided on both sides of a large diameter portion 11a that constitutes part of the arm portion 11.

[0023] The locking members D3 are a first locking member D3a and a second locking member D3b provided on the first tension coil spring D2a and the second tension coil spring D2b, respectively, on the opposite side of the arm portion 11. The other end of the first tension coil spring D2a is locked to the first locking member D3a, and the other end of the second tension coil spring D2b is locked to the second locking member D3b.

[0024] As shown in the figure, the locking member D3 is composed of a bracket 31 fixed to the target structure S to be damped, a bolt 32 attached by passing through the bracket 31, a nut 33 screwed onto the bolt 32 so as to sandwich the bracket 31 from both sides, and a locking tool 34 attached to the end of the arm portion 11 of the bolt 32 and provided with a hook 34-1 on which the other end of the tension coil spring D2 is hooked. Then, the bolt 32 is fixed to the bracket 31 by the nut 33 sandwiching the bracket 31 from both sides.

[0025] In this way, the nut 33 threaded onto the bolt 32 sandwiches the bracket 31 from both sides, so that by adjusting the threaded position of the bolt 32 and the nut 33, the protruding length of the bolt 32 toward the arm portion 11 when fixed to the bracket 31 can be freely set.

[0026] 1, in the first embodiment, the length by which the first locking member D3a protrudes toward the arm portion 11 of the bolt 32 is shorter than the length by which the second locking member D3b protrudes toward the arm portion 11 of the bolt 32. In other words, the distance L1 between the locking position of the first tension coil spring D2a with respect to the arm portion 11 (the position of the hook 11a-1 on which the first tension coil spring D2a is hooked) and the locking position of the first locking member D3a (the position of the hook 34-1 on which the first tension coil spring D2a is hooked) is longer than the distance L2 between the locking position of the second tension coil spring D2b with respect to the arm portion 11 (the position of the hook 11a-1 on which the second tension coil spring D2b is hooked) and the locking position of the second locking member D3b (the position of the hook 34-1 on which the second tension coil spring D2b is hooked). As described above, the first tension coil spring D2a and the second tension coil spring D2b have the same spring constant, so the first tension coil spring D2a is pulled more strongly than the second tension coil spring D2b. As a result, the first tension coil spring D2a and the second tension coil spring D2b try to maintain balance, and as shown in the figure, the vibrating body D1, which hangs down vertically in a free state, is slightly tilted toward the first tension coil spring D2a, which is pulled more strongly, that is, toward the side where the separation distance between the locking positions is longer.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] (Embodiment 2)

[0033] 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 a mass body 12 is attached to the arm portion 11 with its center of gravity shifted, and that a distance L1 between two locking positions of the first tension coil spring D2a (the locking position of the arm portion 11 and the locking position of the first locking member D3a) is the same as a distance L2 between two locking positions of the second tension coil spring D2b (the locking position of the arm portion 11 and the locking position of the second locking member D3b). In other respects, the vibration damping device (vibration damping means) D of the first embodiment is configured similarly to the vibration damping device D of the first embodiment.

[0034] In other words, 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 when in a free state (when not restrained by the spring force of the tension coil spring D2 described later).

[0035] Furthermore, since the first tension coil spring D2a and the second tension coil spring D2b, which have the same spring constant, are pulled with the same strength, the vibrating body D1, which hangs down in a direction inclined from the vertical direction in its free state, hangs down in the vertical direction due to the first tension coil spring D2a and the second tension coil spring D2b attempting to maintain balance.

[0036] 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.

[0037] 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.

[0038] (Embodiment 3)

[0039] 3 is a schematic diagram showing a vibration damping mechanism according to embodiment 3 of the present invention. The vibration damping device (vibration damping means) D constituting the vibration damping mechanism of embodiment 3 shown in the figure is configured by adding a deflection angle restricting member D4 for restricting the deflection angle of vibrating body D1 to a predetermined angle to the vibration damping device (vibration damping means) D of embodiment 1 described above.

[0040] 4, the restoring force F of the tension coil spring D2 does not significantly affect the period of the vibrating body D1 when the vibrating body D1 does not oscillate significantly (when the oscillation angle θ of the vibrating body D1 is within a predetermined range). However, as the oscillation angle θ of the vibrating body D1 increases, the restoring force F of the tension coil spring D2 weakens, resulting in a longer period of the vibrating body D1.

[0041] Therefore, a swing angle restricting member D4 is added to restrict the swing angle θ of the vibrating body D1 to a predetermined angle and to suppress the occurrence of nonlinear mechanical components in the restoring force F of the tension coil spring D2 that expands when the vibrating body D1 swings.

[0042] 4, the swing angle limiting member D4 includes a magnet 41 that is installed on the arm 11 with the direction of magnetic flux facing the vibration direction of the arm 11 (i.e., with both poles of the magnet facing the vibration direction of the arm 11), and a first magnet holder 42a and a second magnet holder 42b that are installed in a direction that matches the vibration plane of the arm 11 and on opposite sides of the arm 11. The first magnet holder 42a and the second magnet holder 42b hold magnets 43a and 43b so that the magnetic poles facing the magnet 41 installed on the arm 11 are the same polarity (for example, if the magnetic pole facing the first magnet holder 42a of the magnet 41 installed on the arm 11 is an S pole, the first magnet holder 42a holds the magnet 43a so that the S pole faces the magnet 41), and the repulsion between the magnets limits the vibration amplitude of the arm 11.

[0043] As shown in the figure, the first magnet holder 42a and the second magnet holder 42b are attached to the arm portion 11 side end of a bolt 44 that is attached by passing through the bracket 31. A nut 45 for fixing the bolt 44 to the bracket 31 is threaded onto the bolt 44. By adjusting the threaded position of the bolt 44 and the nut 45, the length of protrusion of the bolt 44 toward the arm portion 11 when fixed to the bracket 31 is made equal. As a result, the distance between the magnet 41 of the arm portion 11 and the magnet 43a of the first magnet holder 42a and the distance between the magnet 41 of the arm portion 11 and the magnet 43b of the second magnet holder 42b are equal when the arm portion 11 is oriented vertically.

[0044] By providing such a swing angle restricting member D4, the swing angle θ of the vibrating body D1 is restricted to a predetermined angle by the repulsion between the magnets, and the occurrence of a nonlinear mechanical component in the restoring force F of the tension coil spring D2 that extends when the vibrating body D1 swings is suppressed. This prevents the restoring force F of the tension coil spring D2 from weakening and the period of the vibrating body D1 from becoming longer.

[0045] The oscillation angle θ of the vibrating body D1 at which the occurrence of a nonlinear mechanical component in the restoring force F of the tension coil spring D2 is suppressed varies depending on the spring constant of the tension coil spring D2, and therefore cannot be uniquely defined.

[0046] 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.

[0047] For example, in the above-mentioned embodiment 3, the vibration control device D is configured by adding a sway angle regulating member D4 to the vibration control device D of embodiment 1, but the vibration control device D can also be configured by adding a sway angle regulating member D4 to the vibration control device D of embodiment 2.

[0048] Furthermore, 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]

[0049] 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]

[0050] 11 Arm section 11a Large diameter part 11a-1 Hook 12 mass body 13 Mounting base 14 Rotating shaft 31 Bracket 32 volts 33 Nut 34 Locking device 34-1 Hook 41 Magnet 42a First magnet holder 42b Second magnet holder 43a, 43b Magnet 44 volts 45 Nut D. Vibration control device (vibration control means) D1 vibrating body D2 tension coil spring D2a First tension coil spring D2b Second tension coil spring D3 Locking member D3a First locking member D3b Second locking member D4 Swing angle control member 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 in the target structure and 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 first tension coil spring and a second tension coil spring, one ends of which are engaged with the arm portion in a direction coinciding with the vibration plane of the arm portion and at positions opposite to each other across the arm portion, the first tension coil spring and the second tension coil spring having the same spring constant; a first locking member and a second locking member that lock the other ends of the first tension coil spring and the second tension coil spring, respectively; a distance between a locking position of the arm portion of the first tension coil spring and a locking position of the first locking member and a distance between a locking position of the arm portion of the second tension coil spring and a locking position of the second locking member are unequal. 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 in the target structure and 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 tension coil spring and a second tension coil spring, one ends of which are engaged with the arm portion in a direction coinciding with the vibration plane of the arm portion and at positions opposite to each other across the arm portion, the first tension coil spring and the second tension coil spring having the same spring constant; a first locking member and a second locking member that lock the other ends of the first tension coil spring and the second tension coil spring, respectively; a distance between a locking position of the arm portion of the first tension coil spring and a locking position of the first locking member is equal to a distance between a locking position of the arm portion of the second tension coil spring and a locking position of the second locking member; A vibration damping mechanism characterized by:

3. 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 equal intervals when the arm portion is oriented vertically; 3. The vibration damping mechanism according to claim 1 or 2.

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.

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

5. The target structure to be damped has a cantilever structure supported at only 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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