JPH0743003B2 - Dynamic vibration absorber - Google Patents

Description

Detailed Description of the Invention a. OBJECT OF THE INVENTION [Industrial field of application] The present invention relates to a vibration damping device for increasing vibration damping in a bridge or a machine body and its foundation, and other structures vibrated by an external force, a so-called dynamic vibration absorbing device. (Also called a dynamic vibration absorber or a dynamic damper)

[Prior Art] Generally, a dynamic vibration absorber has a natural frequency equal to a natural frequency of a main vibration system vibrated by a vibration source (external force), or a natural frequency slightly smaller than the natural frequency of the vibration system. It is a vibrating system having a function of reducing vibration of the main vibrating system by adding it to the main vibrating system, and its theory is already known. That is, as shown in FIG. 6 (a), the device (2) is basically composed of a spring body, a mass body (weight) and a damper (attenuator), which is used as a main vibration system (1). ) Is added to. When this is displayed as a vibration model, it becomes as shown in FIG. 6B, which is analyzed as a vibration model of a two-free system. Here, M1, K1, and C1 are the equivalent mass, equivalent spring constant, and damping coefficient of the main vibration system (1), respectively.

Such a dynamic vibration absorbing device has a structure in which a weight is supported by a spring body as disclosed in, for example, Japanese Unexamined Patent Publication No. Sho 50-96325.

However, with such a configuration, it is not possible to avoid rolling of the weight, and it is not possible to obtain a desired damping property due to the rolling of the weight. Therefore, a guide means for preventing the weight from rolling laterally and guiding only the vertical movement is desired. However, a friction force is generated by a normal guide means (for example, a guide by a roller), and the friction force attenuates the friction force. The characteristics are greatly diminished, and the movement of the weight is completely blocked by this frictional force even for minute vibrations of small amplitude, which is not an effective damping means.

Therefore, the conventional one is used while allowing the rolling of the weight.

[Problems to be Solved by the Invention] In view of such circumstances, an object of the present invention is to provide a dynamic vibration absorbing device having a support mechanism that can prevent lateral rolling of a weight and can ignore frictional resistance. Subject)).

B. Configuration of the Invention [Configuration of the Present Invention] The dynamic vibration absorbing device of the present invention has the following configuration in order to achieve the above object.

That is, a spring body installed on the bottom plate, a weight portion mounted and supported by the spring body, a fixed support body fixed to the bottom plate and arranged around the weight portion, and the weight portion. An arm portion with a weight portion protruding outward from the side portion of the fixed support; and an arm portion with a weight portion protruding from the side portion of the fixed support while keeping the vertical surface therebetween. An arm portion with a fixed support that is installed opposite to the arm portions at equal intervals; a thin plate-like member, and its end portions are fixed to the vertical planes of these arm portions, and between these arm portions And a leaf spring mechanism composed of: a thin leaf spring bent in a U shape with its plate width direction toward the center of the weight portion;
The leaf spring mechanism is arranged around the weight portion so as to offset horizontal displacements from each other.

In the above structure, the bottom plate and the fixed support form a fixed system, the spring and the weight portion form a movable system, and the leaf spring mechanism is interposed between the fixed system and the movable system.

In the above, the weight-equipped arm member corresponds to the inner-cylinder arm member in the following embodiments, and the fixed support arm member corresponds to the outer-cylinder arm member.

The dynamic vibration absorbing device is fixed to the main vibration system via the bottom plate.

[Action]

The weight portion is supported on the spring installed on the bottom plate at its balance position, and the thin leaf spring moves up and down following the dynamic displacement of the weight portion. Then, when the forced vibration force acting on the main vibration system is transmitted to the weight portion via the spring body installed on the bottom plate of the dynamic vibration absorbing device, the weight portion is laterally, that is, horizontal due to the lateral rigidity characteristic of the thin leaf spring. It is not displaced in any of the directions.

As a result, the weight of this dynamic vibration-absorbing device does not roll,
Since it only moves vertically without frictional force, it exhibits ideal dynamic vibration absorption.

Embodiment An embodiment of the dynamic vibration absorbing device of the present invention will be described with reference to the drawings.

(Structure of Embodiment) FIGS. 1 to 4 show a dynamic vibration absorbing device D of an embodiment thereof.
That is, FIGS. 1 and 2 show the whole, and FIGS. 3 and 4 show the partial structure.

The dynamic vibration absorbing device D includes a spring body 1, a weight portion 2 supported by the spring body 1, and a guide portion 3 of the weight portion 2,
The viscous shearing resistance part 4 is added.

Hereinafter, the structure of each part will be described in detail.

Spring Body 1 The spring body 1 is composed of a coil spring having a predetermined spring constant, and is placed on the bottom plate 10 and supports the weight portion 2 thereon.

The bottom plate 10 has bolt insertion holes 12 at its four corners, and is fixed to the main vibration system by fixing bolts as described later.

Weight Unit 2 The weight unit 2 includes a substrate 14, a cylindrical inner cylinder 16 having an open upper portion installed on the substrate 14, and a weight 18 installed in the inner cylinder 16. These are integrally fixed by a fixture 22 composed of a bolt 20 and a nut 21. That is, substrate 1
4, the bottom plate 16a of the inner cylinder 16 and the weight 18 are each provided with a bolt insertion hole 24, which is fixed by spirally tightening a nut 21 on a long bolt 20 inserted in the bolt insertion hole 24. .

The substrate 14 is formed thick and directly receives the load of the weight 18, and may be omitted if the bottom plate 16a of the inner cylinder 16 has the function.

The inner cylinder 16 is not limited to the inner cylinder, but may be a symmetrical cylindrical body such as a square cylinder or other polygonal cylinder, and the point is that the weight 18 can be housed therein. A vertical plate 26 is fixed to the outer surface of the side wall 16b of the inner cylinder 16 by welding or the like. The vertical plates 26 are provided on the outer surface of the inner cylinder 16 at appropriate intervals (usually equal intervals).

Further, the weight 18 is composed of a large number of sheets, and the load is adjusted by selecting an appropriate number. Therefore, if the load is uniquely determined, it is possible to use only one load.

Guide Part 3 The guide part 3 is composed of an outer cylinder 30 and a leaf spring mechanism 32 interposed between the outer cylinder 30 and the vertical plate 26.

The outer cylinder 30 constitutes a fixed support, and is erected on the bottom plate 10 so as to surround the inner cylinder 16 at a proper distance from the inner cylinder 16. The outer cylinder 10 has a main function of supporting the leaf spring mechanism 32. Therefore, as long as it fulfills this mechanism, it is not necessary to have a cylindrical body, and for example, a pillar member can be applied.

The leaf spring mechanism 32 includes a thin leaf spring 34, an arm member 36 with an inner cylinder that supports the thin leaf spring 34, an arm member 38 with an outer cylinder, and a backing plate that fixes these members. As can be seen from FIGS. 1 and 2, the leaf spring mechanism 32 is arranged in four directions at equal intervals of 90 ° in the circumferential direction with respect to the inner cylinder 16 and at two upper and lower positions. There is.

The configuration of the leaf spring mechanism 32 will be described in detail with reference to FIG.

The arm member 36 with the inner cylinder has its base portion 36a fixed to the vertical plate 26,
The arm member 38 with an outer cylinder is also fixed to the outer cylinder 30 by welding or the like.
These arm members 36 and 38 both have a flat plate shape, and the plane thereof is vertical, and the arm member 38 with an outer cylinder sandwiches the arm member 36 with an inner cylinder, and both are kept at an appropriate distance and at equal intervals. Opposed in layers parallel to each other.

Since the arm member 36 with the inner cylinder projects from the outer cylinder 30, the outer cylinder 30 has the window 39 opened at this position. The window portion 39 has a size that allows a vertical movement of the arm member 36.

The strip-shaped thin leaf spring 34 is bent into a U-shape, and its both ends are fixed to the arm members 36, 38 through the contact plates 40 by the fixtures 42 composed of bolts and nuts. Normally, a steel plate is used as the thin leaf spring 34, but other materials, such as plastics, can be used as long as they exhibit equivalent mechanical characteristics.

By its nature, the thin leaf spring 34 easily exhibits flexibility in any direction along the paper surface of FIG. 3 and exhibits rigidity (which is called lateral rigidity) with respect to a force acting at right angles to the paper surface.

As a result, the arm member 36 is easily displaced in the vertical direction of the paper surface of FIG. 3, exhibits rigidity in the direction perpendicular to the paper surface (front-back direction), and is hardly displaced. It should be noted that although the arm member 36 can be easily displaced in the left-right direction on the paper surface depending on one leaf spring mechanism 32, the leaf spring mechanism 32 can be arranged in the right-and-left direction by arranging at least one other at a right angle. The displacement is offset.

In this embodiment, since the plurality of leaf spring mechanisms 32 are arranged at 90 ° intervals on the four circumferences, the displacement in the left and right directions is canceled out, and only the displacement in the up and down direction is possible. It should be noted that in order to cancel this displacement in the left-right direction, it is sufficient to dispose the leaf spring mechanism at three positions at 120 ° intervals.

In the present embodiment, the leaf spring mechanism 32 is further arranged at two positions vertically to prevent the weight 2 from swinging (rolling). However, if it is not necessary to take this swinging motion into consideration, it is sufficient to provide only one position on the upper side.

A cover 50 for covering the leaf spring mechanism 32 is attached to the side portion of the outer cylinder 30 in association with the guide portion 3 described above, and the outer cylinder 30 is also attached.
A flange 52 is fixed on the upper part of the
54 is detachably installed.

Viscous shearing resistance part 4 The viscous shearing resistance part 4 is fixed to the bottom plate 10 and has a cylindrical fixed cylindrical body 60. Viscous fluid L filled in the cylinder 60
Consists of.

A bulging portion 64 extends over a fixed length on the peripheral surface of the lower end of the movable tubular body 62.
The outer surface of the bulging portion and the inner surface of the fixed cylindrical body 60 are held in a minute gap s, and viscous shear resistance is caused by the opposing surfaces and the viscous fluid L filled in the minute gap s. It constitutes a generator (see FIG. 4).

From the standpoint of avoiding the generation of frictional resistance as much as possible, the viscous shearing resistance portion 4 of this embodiment is not provided with a spacer in order to obtain the minute gap s, but is performed by the vertical guiding action of the guide portion 3.

When assembling the dynamic vibration absorber D, the weight 18 having a predetermined weight is used.
After being mounted on the spring body 1, in a state where the spring body 1 and the weight 18 are in balance and stationary, the thin plate spring 34
Is set. As a result, in the steady state, no stress is generated in the thin leaf spring 34, and the vertical movement is smoothly performed.

FIG. 5 shows an installation mode of the dynamic vibration absorbing device D on a bridge.

In the figure, G indicates the upper structure of the bridge, G1 is the passage part (bridge floor), and G2 is the frame part (bridge girder) composed of the main girder 70. The superstructure G constitutes the main vibration system.

A mounting plate 72 is bridged between the main girders 70 in the direction y perpendicular to the bridge axis at a position corresponding to the antinode of the vibration mode appearing in the bridge axis direction x of the main vibration system G. The dynamic vibration absorbing device D is attached to the attaching plate 72 with proper fixing means while keeping the symmetrical position.

(Operation of Embodiment) When the bridge superstructure G causes vibration due to passing traffic, seismic motion, or wind load, this vibration is transmitted to the dynamic vibration absorbing device G. This vibration becomes vibration of the weight portion 2 via the coil spring 1, but since the outer cylinder 30 moves integrally with the upper structure G, the arm member 38 with the outer cylinder fixed to the outer cylinder 18 and the inner cylinder. The displacement is relative to the arm member 36 with the inner cylinder fixed to 18. Then, this relative displacement is the displacement of the thin leaf spring 34, but the thin leaf spring 34 has rigidity in the plate width direction, exhibits almost no resistance in other directions, and the leaf spring mechanism 32 is arranged in four rounds. As a result, only the vertical displacement is allowed.

Therefore, the vibration of the weight unit 2 does not cause lateral vibration, but only vertical vibration.

Further, the thin leaf springs 34 are bent in a U shape and are arranged in two rows, so that the thin leaf springs 34 follow up-and-down vibrations of the weight portion 2 with no load, and are not biased. Good vibration absorbing characteristics as a vibration absorbing device can be exhibited. Further, the thin leaf spring 34 does not change its characteristics no matter how long it is, is not restricted by the stroke, and can deal with a wide range from small vibration to large vibration. In addition, the thin leaf spring 34 itself does not undergo any harmful deformation such as twisting and the durability is improved.

Further, in the viscous shearing resistance portion 4, the vertical vibration of the weight portion 2 supported by the coil spring 1 causes the displacement of the movable cylindrical body 62 as it is, and the outer surface of the bulging portion 64 and the fixed cylinder 60 under the movable cylindrical body 62. Relative displacement with the inner surface of the
The viscous body L, which is held in the minute gap s, causes a viscous shear resistance between the two surfaces in the direction opposite to the displacement, and damps the vibration of the movable tubular body 62. . This viscous shear resistance reacts sensitively to minute vibrations.

Due to the additional function of the viscous shearing resistance unit 4, the main vibration system G
The natural frequency range of this dynamic vibration absorber D is widened,
The damping effect is further ensured. At the same time, as described above, the micro-vibration characteristic of the leaf spring mechanism 32 and the micro-vibration characteristic of the viscous shear resistance are combined to obtain the vibration-damping action of the micro-vibration. Further, the viscous shear resistance reduces the spring constant of the spring body 1 and contributes to downsizing of the device.

(Other Embodiments) The present invention is not limited to the above embodiments, and various design changes are possible within the scope of the basic technical idea of the present invention. That is, the following aspects are included in the technical scope of the present invention.

In this implementation system, the arm member 36 with an inner cylinder and the arm member 38 with an outer cylinder are stretched outward, but the outer cylinder 30 is made larger in diameter, and the arm member 38 with an outer cylinder is stretched inward. However, the leaf spring mechanism 32 may be provided between the inner cylinder 16 and the outer cylinder 30.

The inner cylinder may have a frame structure instead of the cylindrical body.

C. EFFECTS OF THE INVENTION Since the dynamic vibration damping device of the present invention has the above-mentioned configuration and acts, it has the following unique effects.

The plate spring mechanism prevents lateral vibration of the weight portion, and only vertical vibration is obtained. Since frictional resistance is not generated, a reliable vibration damping action is obtained even for minute vibrations.

Since the thin leaf springs are bent in a U shape and are arranged in two lines, the thin leaf springs follow up-and-down vibrations of the weight portion without load, and no deviation occurs, which is excellent as a dynamic vibration absorbing device. It can exhibit excellent vibration absorption characteristics.

The thin leaf spring does not change its characteristics no matter how long it is,
It can handle a wide range of vibrations from small vibrations to large vibrations without being restricted by strokes.

The thin leaf spring itself does not undergo any harmful deformation such as twisting and the durability is improved.

[Brief description of drawings]

The drawings show an embodiment of the dynamic vibration absorbing device of the present invention. FIG. 1 is a longitudinal sectional view of one embodiment thereof, FIG. 2 is a sectional view taken along the line XX of FIG. 1, and FIG. FIG. 4 is an enlarged view (a sectional view taken along line YY of FIGS. 1 and 2) of FIG. 4, FIG.
FIG. 6 is an arrangement mode diagram, and FIG. 6 is a conceptual explanatory view of the dynamic vibration absorbing device. 1 ... Spring body, 2 ... Weight section, 3 ... Guide section, 4 ... Viscous shear resistance section, 10 ... Bottom plate, 18 ... Weight, 30 ... Outer cylinder (fixed support), 32 ...... Leaf spring mechanism, 34 …… Thin leaf spring,
36: Arm with inner cylinder, 38: Arm with outer cylinder

Claims (1)

[Claims] 1. A spring body installed on a bottom plate, a weight portion mounted and supported by the spring body, a fixed support body fixed to the bottom plate and arranged around the weight portion, An arm portion with a weight portion protruding outward from the side portion of the weight portion and protruding outward; and an arm portion with a weight portion protruding from the side portion of the fixed support while maintaining a vertical surface. An arm portion with a fixed support, which is opposed to the arm portion at equal intervals, with a thin plate shape, and the end portions of the arm portions are fixedly mounted on the vertical planes of the arm portions. A leaf spring mechanism including a thin leaf spring bent between the portions in a U-shape with its plate width direction toward the center of the weight portion and bridged therebetween; A dynamic vibration absorbing device, characterized in that the dynamic vibration absorbing devices are arranged around the weight portion so as to cancel horizontal displacements from each other.