JP7640386B2 - Dynamic vibration absorber - Google Patents

Description

The present invention relates to a dynamic vibration absorber, in particular one that adds a rotating inertial mass to the inertial mass of an inertial mass body such as a weight, thereby damping vibration.

A vibration control device for long structural parts such as beams and floors of a large building is described in Patent Document 1 (particularly Figures 6 and 7). A Tuned Mass Damper (TMD) provided in the center of the floor where the amplitude of floor vibration is the largest comprises a viscoelastic rubber member fixed to the underside of the floor and a mass body fixed to the underside of the viscoelastic rubber member, and by setting the rigidity of the viscoelastic rubber member to be in tune with the natural frequency of the floor, the mass body is made to resonate with the vibration of the floor and vibrate greatly, absorbing the vibration energy of the floor and reducing the vibration.
Also, Patent Document 2 (particularly Figs. 10 and 11) discloses a vibration control device that is installed along a direction perpendicular to the bridge axis between a pair of support crossbeams installed between piers located at the end of the viaduct in the bridge axis direction. In this vibration control device, a movable mass penetrated by a support shaft erected on a base is elastically supported by upper and lower coil springs around each support shaft while being guided in its vertical movement. When the vibration of the viaduct is transmitted to the movable mass, the movable mass vibrates up and down along the support shaft while resisting the spring reaction force, vibrating in synchronization with the natural vibration of the viaduct, and an oil damper between the base frame and the movable mass generates viscous resistance of oil passing through an orifice, thereby damping the vibration of the viaduct.
Furthermore, Patent Document 3 (particularly Figs. 1 and 2) discloses a dynamic vibration absorber for a plurality of divided floor panels. This dynamic vibration absorber includes a beam-shaped spring member, a mass, and a viscoelastic body. One end of the beam-shaped spring member is fixed to the lower surface of the plurality of divided floor panels, and vibration of the divided floor panels is input, and the other end vibrates with the spring force of bending deformation against the divided floor panels. The mass is fixed to the lower surface of the other end side of the beam-shaped spring member. The viscoelastic body is provided on the other end side of the beam-shaped spring member, and strikes the divided floor panels or applies a compressive force according to the contact state in response to vibration of the other end of the beam-shaped spring member. The vibration of the divided floor panels is transmitted to the mass of the dynamic vibration absorber to suppress the vibration of the divided floor panels, and the viscoelastic body of the dynamic vibration absorber comes into contact with the divided floor panels to further suppress the vibration of the divided floor panels.
Furthermore, because dynamic vibration absorbers are highly effective at reducing steady-state vibration, they are not only used to counter traffic vibration, but in recent years have also been used to counter wind vibration in high-rise buildings and long-period earthquake motion. A representative example is Patent Document 4. Patent Document 4 describes a dynamic vibration absorber that has a structure that allows springs to be arranged appropriately for the direction of vibration while preventing the structure from becoming complicated, for structures that have different natural frequencies depending on the direction of vibration. However, it is the same as conventional dynamic vibration absorbers in that it uses a large mass weight to reduce vibration.

JP 2018-145627 A JP 2017-82493 A JP 2016-118031 A JP 2017-025943 A

In both of the above-mentioned conventional vibration control devices and dynamic vibration absorbers, a weight is used as the inertial mass. Therefore, when applying them to long structures such as large buildings or high-rise buildings, it is necessary to use a weight with a mass corresponding to the weight of the object to be damped. This results in a large load on the strength due to the weight of the weight itself, and also results in fixed vibration damping characteristics that are determined by the inertial mass of the weight.
Therefore, an object of the present invention is to provide a dynamic vibration absorber that is compact for relatively long objects such as beams and floors, imposes only a small load on the object, and yet can be configured to have vibration characteristics appropriate to the object.

In order to solve the above problems, the present invention provides a dynamic vibration absorber 1 that is connected to an installation target such as the floor F of a building via elastic bodies such as coil springs 9 and 10, and that attenuates vibrations by the inertial mass of the inertial mass body 3 associated with the vibration of the vibration-damping target, and is equipped with rotating inertia bodies 12 and 14 that are rotatably supported on the vibration-damping target via a mounting member such as a frame body 2, and links 11 and 13 that are pivotally supported at one end on the inertial mass body 7 and at the other end on the rotation axes 12a and 14a of the rotating inertia bodies 12 and 14, respectively, and rotate the rotating inertia bodies 12 and 14 with the vibration of the inertia mass body. By superimposing the rotating inertia mass of the rotating inertia bodies 12 and 14 on the inertial mass of the inertia mass body 3 associated with the vibration of the vibration-damping target, the inertial mass of the inertia mass body 3 is increased or decreased, and a vibration damping force suitable for the vibration-damping target is applied.

According to the present invention, the rotational inertial mass of the rotating inertial body is added to the inertial mass of the inertial mass body, increasing or decreasing the inertial mass. Therefore, despite the overall configuration being compact and with a light load on the object to be damped, an appropriate inertial mass can be obtained, and by appropriately adjusting the inertial mass, optimal vibration damping characteristics can be imparted to the anticipated vibrations.

1 is a front view of a dynamic vibration absorber according to an embodiment of the present invention; FIG. 2 is a rear view of the dynamic vibration absorber of FIG. 1 . FIG. 2 is a side view of the dynamic vibration absorber of FIG. 1 . FIG. 2 is a plan view of the dynamic vibration absorber of FIG. 1 . 5A to 5C are diagrams illustrating the operation of the first rotary inertia mechanism. 11A to 11C are diagrams illustrating the operation of the second rotational inertia mechanism. 1A is a graph showing the relationship between the rotation angle of a first rotational inertia mechanism and the magnification of the equivalent mass with respect to an inertial mass body, and FIG. 1B is a graph showing the relationship between the rotation angle of a second rotational inertia mechanism and the magnification of the equivalent mass with respect to an inertial mass body. 13 is a graph showing a change in amplitude magnification with respect to an input frequency ratio when the magnification of the equivalent mass of an inertial mass body is increased or decreased by 10% and 20%. 11 is a graph showing a comparison of changes in amplitude magnification with respect to input frequency ratio when the equivalent mass of an inertial mass body is reduced by 10%. 11 is a graph showing a comparison of changes in amplitude magnification with respect to input frequency ratio when the equivalent mass of an inertial mass body is increased by 10%. 11 is a graph showing a comparison of changes in amplitude magnification with respect to input frequency ratio when the equivalent mass of the inertial mass body is reduced by 20%. 11 is a graph showing a comparison of changes in amplitude magnification with respect to input frequency ratio when the equivalent mass of the inertial mass body is increased by 20%. 2 is an explanatory diagram of the operation of the dynamic vibration reducer of FIG. 1; FIG. 11 is a graph showing the relationship between the rotation angle and equivalent mass of a dynamic vibration absorber that combines a first rotational inertia mechanism and a second rotational inertia mechanism, the link length ratio and the rotational inertia mass ratio being set to Condition 1 shown in Table 1. 11 is a graph showing the relationship between the rotation angle and equivalent mass of a dynamic vibration absorber that combines a first rotational inertia mechanism and a second rotational inertia mechanism, the link length ratio and the rotational inertia mass ratio being set to Condition 2 shown in Table 1. 13 is a graph showing the relationship between the rotation angle and equivalent mass of a dynamic vibration absorber that combines a first rotational inertia mechanism and a second rotational inertia mechanism, the link length ratio and the rotational inertia mass ratio being set to Condition 3 shown in Table 1. 13 is a graph showing the relationship between the rotation angle and equivalent mass of a dynamic vibration absorber that combines a first rotational inertia mechanism and a second rotational inertia mechanism, the link length ratio and the rotational inertia mass ratio being set to Condition 4 shown in Table 1. 13 is a graph showing the relationship between the rotation angle and equivalent mass of a dynamic vibration absorber that combines a first rotary inertia mechanism and a second rotary inertia mechanism, with the link length ratio and rotary inertia mass ratio set to Condition 5 shown in Table 1. FIG. 11 is a front view of a dynamic vibration absorber according to another embodiment.

An embodiment of the present invention will be described with reference to the drawings.
1 to 4, the dynamic vibration absorber 1 comprises a substantially cross-shaped frame 2 which is attached to the underside of a floor F which is the object of vibration damping and which constitutes a mounting member for the following accessories to the floor F, an inertial mass body 3 which is supported vertically along the vertical plate parts of the frame body 2 and performs a damping action by resonating with the vertical vibration of the floor F, first and second rotational inertia mechanisms 4 and 5 which are supported on both sides of the horizontal plate parts of the frame body 2 and increase or decrease the inertial mass by adding a rotational inertial mass to the inertial mass body 3, and a vibration damping means 6 which damps the vibration of the floor F. The frame body 2 comprises an upper frame 2a for fixing to the underside of the floor F, a lower frame 2b which faces the upper frame 2a at the lower part, a substantially cross-shaped support plate 2c which connects the upper frame 2a and the lower frame 2b to the upper and lower ends, and a connecting rod 2d which connects the upper frame 2a and the lower frame 2b.

The inertial mass body 3 comprises a rectangular weight section 7 supported vertically along the vertical piece of the support plate 2c of the frame body 2, and a guide shaft section 8 extending vertically from the weight section 7 and slidably penetrating the upper frame 2a and the lower frame 2b. The inertial mass body 3 is held vertically movably on the frame body 2 by coil springs 9, 10 engaged between the weight section 7 and the upper frame 2a and the lower frame 2b. The vibration damping means 6 connected to the lower end of the guide shaft section 8 reinforces the damping effect as necessary to prevent the inertial mass body 3 from continuing to vibrate vertically, and various well-known dampers that provide resistance to the behavior of the inertial mass body can be used.

The first rotational inertia mechanism 4 comprises a first link 11 rotatably supported on the pivot 7a of the weight section 7 and extending along one side of the support plate 2c, and a first rotational inertia body 12 whose center is pivoted on the support plate 2c and engages with the tip of the first link 11. The base end of the first link 11 is supported rotatably around the pivot 7a located at the front center of the weight section 7, extends horizontally along the side of the support plate 2c at the initial position of the weight section 7, and has a small diameter part 11a of a predetermined length in the longitudinal direction at the tip. The first rotational inertia body 12 has a predetermined rotational inertia mass, is disk-shaped integral with the central rotational shaft 12a, and is supported on the support plate 2c rotatably in the vertical direction around the rotational shaft 12a. A horizontal engagement tube 12b perpendicular to the axis is fixed to the tip of the extended rotational shaft 12a. The small diameter portion 11a of the first link 11 slides through the engagement tube 12b, allowing the first rotating inertia body 12 to rotate as the first link 11 tilts in response to the up and down movement of the inertia mass body 3.

The second rotational inertia mechanism 5 comprises a second link 13 rotatably supported on the pivot 7a of the weight section 7 and extending horizontally along the other side of the support plate 2c, and a second rotational inertia body 14 whose center is pivoted on the support plate 2c and engages with the tip of the second link 13. The base end of the second link 13 is rotatably supported at the front center of the pivot 7a of the weight section 7, extends horizontally to the opposite side to the first link 11 at the initial position of the weight section 7, and is connected to the rotational shaft 14a of the second rotational inertia body 14 at its tip. The second rotational inertia body 14 has a predetermined rotational inertia mass, is disk-shaped integral with the central rotational shaft 14a, and is supported on the support plate 2c so as to be rotatable vertically around the rotational shaft 14a. The second rotating inertia body 14 is supported so that it can move horizontally within the range of a longitudinal long hole 15 formed in the support plate 2c, and allows the second rotating inertia body 14 to rotate together with the tilting of the second link 13 accompanying the vertical movement of the inertia mass body 3.

但し、Ｍｅ_１；第１回転慣性体の等価質量、Ｉｒ_１；第１回転慣性体の慣性質量（第１リンクを含む）、ｒ_１；第１回転慣性体と慣性質量体の中心間距離、θ_１；第１リンクの回転角とする。
また、床Ｆの振動が動吸振器１に伝達されて、図６に示すように、慣性質量体３が上方へ移動したときの第２回転慣性機構５の等価質量は以下になる。

但し、Ｍｅ_２；第２回転慣性体の等価質量、Ｉｒ_２；第２回転慣性体の慣性質量（第２リンクを含む）、ｒ_２；第２回転慣性体と慣性質量体を結ぶ第２リンク長さ、θ_２；第２リンクの回転角とする。 When vibration of the floor F is transmitted to the dynamic vibration absorber 1 and the inertial mass body 3 moves upward as shown in FIG. 5, the equivalent mass of the first rotary inertia mechanism 4 is as follows:

where Me ₁ is the equivalent mass of the first rotating inertia body, Ir ₁ is the inertia mass of the first rotating inertia body (including the first link), r ₁ is the center-to-center distance between the first rotating inertia body and the inertia mass body, and θ ₁ is the rotation angle of the first link.
When the vibration of the floor F is transmitted to the dynamic vibration absorber 1 and the inertial mass body 3 moves upward as shown in FIG. 6, the equivalent mass of the second rotary inertia mechanism 5 is as follows:

where Me ₂ is the equivalent mass of the second rotating inertia body, Ir ₂ is the inertia mass of the second rotating inertia body (including the second link), r ₂ is the length of the second link connecting the second rotating inertia body and the inertia mass body, and θ ₂ is the rotation angle of the second link.

As shown in Figures 7(A) and (B), the equivalent mass of the inertial mass body 3 has the characteristic of increasing or decreasing with respect to the rotation angle of the first and second rotary inertia mechanisms 4 and 5. The dashed lines in the figures indicate the region where the magnification of the equivalent mass exceeds 10%.

As shown in FIG. 8, the amplitude magnification curve changes according to the equivalent mass of the inertial mass body 3, and the vibration characteristics change. In particular, as shown in FIG. 9A and FIG. 9B, if the increase or decrease in the equivalent mass is within 10%, the amplitude amplification factor changes relatively little, but as shown in FIG. 9C and FIG. 9D, if the increase or decrease in the equivalent mass exceeds 20%, the amplitude magnification changes significantly. In other words, if the increase or decrease in the equivalent mass of the inertial mass body 3 is within 10%, the displacement of the inertial mass body 3 is acceptable for the function of the dynamic vibration absorber, but if the increase or decrease in the equivalent mass is in the range exceeding 10%, the displacement of the inertial mass body 3 may become excessive and may not be desirable for the function of the dynamic vibration absorber. However, the effect of increasing or decreasing the equivalent mass of the first and second rotating inertia mechanisms 4 and 5 alone on the inertial mass body 3 is limited but effective.

但し、α；リンク長さ比ｒ_２／ｒ_１、β；回転慣性質量比Ｉｒ_１／Ｉｒ_２とする。
リンク長さ比αと回転慣性質量比βは、慣性質量体３の変位に伴い変動するので、等価質量の増減にも影響を及ぼす。
等価質量の増幅率が高くなると、慣性質量体３の変位に伴う等価質量の変動は大きくなり、逆に増幅率が低くなると、慣性質量体３の変位に伴う等価質量の変動は小さくなる傾向にある。 In this embodiment, vibrations of a floor F on which the dynamic vibration absorber 1 having the first and second rotational inertia mechanisms 4, 5 are transmitted, and when the inertial mass body moves upward as shown in FIG. 10, the equivalent mass of the inertial mass body 3 is as follows:

where α is the link length ratio r ₂ /r ₁ , and β is the rotational inertia mass ratio Ir ₁ /Ir ₂ .
The link length ratio α and the rotational inertia mass ratio β vary with the displacement of the inertia mass body 3, and therefore affect the increase or decrease in the equivalent mass.
When the amplification factor of the equivalent mass becomes higher, the fluctuation in the equivalent mass accompanying the displacement of the inertial mass body 3 becomes larger, and conversely, when the amplification factor becomes lower, the fluctuation in the equivalent mass accompanying the displacement of the inertial mass body 3 tends to become smaller.

第１，第２回転慣性機構４，５をそれぞれ単体で用いた場合の等価質量の倍率変化は、図７に示すように、１０％以内の領域が第１回転慣性機構４で回転角度約１３度以下、第２回転慣性機構５で回転角度約１７．５度以下になっている。これに対して、図１１ＡからＥに示すように、本実施形態の動吸振器１は、いずれの条件においても回転角度約３０度を超える範囲まで慣性質量体３の可動域が拡がっていることを確認できる。 Depending on how the link length ratio α and the rotational inertia mass ratio β are set, it is also possible to increase the amplification factor of the equivalent mass of the inertia mass body 3 compared to the first and second rotational inertia mechanisms 4 and 5 alone.
11A to 11E show changes in the amplification ratio of the equivalent mass of the inertia mass body 3 relative to the displacement angle of the first link 11 for five conditions of the link length ratio α and the rotational inertia mass ratio β shown in Table 1 below.

7, the change in the magnification of the equivalent mass when the first and second rotary inertia mechanisms 4 and 5 are used alone is within a region of 10% at rotation angles of approximately 13 degrees or less for the first rotary inertia mechanism 4, and at rotation angles of approximately 17.5 degrees or less for the second rotary inertia mechanism 5. In contrast, as shown in Figures 11A to 11E, it can be confirmed that in the dynamic vibration absorber 1 of this embodiment, the range of motion of the inertial mass body 3 is expanded to a range exceeding a rotation angle of approximately 30 degrees under all conditions.

As described above, in the dynamic vibration absorber 1, if the first and second rotary inertia mechanisms 4 and 5 are connected to the inertial mass body 3 individually, the equivalent mass increases or decreases according to the displacement of the inertial mass body 3, so that the fixed inertial mass of the inertial mass body 3 can be adjusted according to the displacement of the vibration. In addition, by combining the first and second rotary inertia mechanisms 4 and 5, the changes in the rotary inertia mass due to the displacement of the inertial mass body 3 are cancelled out by each other, the changes in the rotary inertia mass are suppressed, and the movable range in which the inertial mass body 3 has an inertial mass of a nearly constant magnification can be expanded. Therefore, the dynamic vibration absorber 1 of the present invention can set vibration damping characteristics suitable for the vibration damping target while suppressing the mass of the inertial mass body 3. Furthermore, by combining the first rotary inertia mechanism 4, which has a characteristic of reducing the equivalent mass, with the second rotary inertia mechanism 5, which has a characteristic of amplifying the equivalent mass, the displacement range of the inertial mass body 3 in which the increase or decrease in the equivalent mass effective for the dynamic vibration absorber is within 10% can be expanded.

In addition, this dynamic vibration absorber 1 has the characteristic of shifting from a region where the equivalent mass of the inertial mass body 3 is at a nearly constant magnification to a region where it increases or decreases in response to the displacement of the inertial mass body 3. For example, when the object to be damped is a small-amplitude vibration such as wind, the vibration is suppressed in a region where the equivalent mass fluctuation is within 10%, while when the object to be damped is a large-amplitude vibration such as that caused by an earthquake, the equivalent mass is increased in a region where the equivalent mass fluctuation exceeds a threshold of 10%, thereby suppressing the vibration. In this way, the dynamic vibration absorber 1 can suppress vibrations of various amplitudes and can also be applied to general building structures.

The dynamic vibration absorber 1 according to the present invention is also effective against lateral vibrations in the same manner as the above embodiment when installed on the wall surface W of a structure as shown in FIG. 12, and the present invention is not limited to the vibration direction of the object to be damped.

REFERENCE SIGNS LIST 1 dynamic vibration absorber 2 frame 2a upper frame 2b lower frame 2c support plate 2d connecting rod 3 inertia mass body 4 first rotary inertia mechanism 5 second rotary inertia mechanism 6 vibration damping means 7 weight portion 7a pivot 8 guide shaft portion 9 coil spring 10 coil spring 11 first link 11a small diameter portion 12 first rotary inertia body 12a rotary shaft 12b engagement tube 13 second link 14 second rotary inertia body 14a rotary shaft 15 long hole F floor W wall

Claims (4)

A dynamic vibration absorber that is connected to a vibration damping target via an elastic body so as to be capable of relative movement, and that attenuates vibration of the vibration damping target by relative displacement of an inertial mass body in response to vibration of the vibration damping target,
a rotating inertia body that is rotatably supported on a vibration damping target via a mounting member and has a rotation axis perpendicular to a relative displacement direction of the inertia mass body;
a link having one end pivotally supported on the inertial mass body and the other end pivotally supported on the rotating inertia body, the link rotating the rotating inertia body in response to a relative displacement of the inertial mass body caused by vibration of the vibration damping target,
A dynamic vibration absorber comprising an inertial mass body and a rotary inertial mass body, the rotary inertial mass body being superimposed on the inertial mass of the rotary inertial mass body to impart a vibration damping force to an object to be damped. The dynamic vibration absorber according to claim 1, characterized in that the rotary inertia body is a first rotary inertia body that slidably engages with the link to allow relative displacement of the inertia mass body. The dynamic vibration absorber according to claim 1, characterized in that the rotary inertia body is a second rotary inertia body whose rotary shaft movably engages with the mounting member to allow relative displacement of the inertia mass body. 2. The dynamic vibration absorber according to claim 1 , wherein the rotary inertia body comprises a first rotary inertia body slidably engaged with the link to allow relative displacement of the inertia mass body, and a second rotary inertia body whose rotating shaft movably engages with the mounting member to allow relative displacement of the inertia mass body.

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