JPS6231735A - Two-node pendulum type vibration absorber - Google Patents

Abstract

PURPOSE:To aim at miniaturizing a vibration absorber having a long oscillating period, by disposing dampers between a first arm which is fitted on a first pin attached to a support frame, through the intermediary of springs, and second arms which are coupled to the other end of the first arm and each having a weight. CONSTITUTION:The lower end part of a first arm 16 is rotatably fitted onto a first pin 3 fitted in bearings 20, 20' fixed to a support frame 1, through the intermediary of first springs 19, 19', and a second pin 17 is fitted in the upper end part of the first arm 16. Second arms 2, 2' are rotatably and slidably engaged to both ends of the second pin 17 through the intermediary of springs 18, 18'. Further, weights 4, 4' are movably attached to the lower ends of the second arms 2, 2' by means of bolts 5, 5'. Further, dampers 9, 9' are disposed between a pin 23 fixed to the first arm 16 and pins 24, 24' fixed to the second arms 2, 2'.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to an oscillator-type dynamic vibration absorber for suppressing horizontal vibration caused by wind or the like in a tower-like structure. More specifically, tower-like structures, such as the main tower of a long bridge that becomes independent during construction, generate Karman oscillations due to relatively low wind speeds.
The present invention relates to a device for suppressing vibrations, which are harmful to the tower construction work and to the tower structural strength.

[Conventional technology]

In order to suppress the above-mentioned vibrations, the main method used in the past was to extend a cable from the tower and attach a damper to the end of the cable. Examples of this method include (1) a sliding block method in which damping is added to the vibration system by Coulomb friction between the block and the base, and (2) a hydraulic damper is used to dampen the vibration by the vortex-forming resistance of the oil. There are hydraulic damping methods that add flexibility to the vibration system. However, these methods (1)
In the case of (2), the quantitative reliability of the damping effect is poor, and the block's operability is inconsistent; in the case of (2), the problem of (1) is resolved, but the cable is stretched even though it is under construction. This poses a major problem in that it poses considerable problems in securing a location in the ocean area and attenuator installation. Therefore, a vibration damping method that does not require cables is also being sought.

As a method that does not require the use of ropes, damping using dynamic vibration absorbers may be considered. Patent application 1984-2 as a vibration damping device using a dynamic vibration absorber
There is a pendulum type described in the specification of No. 10553.

In this method, if the structure has a long period, the length of the arm of the oscillator is very large.
In addition, with this method, the damping effect can only be achieved for one vibration mode, so if you try to damp two vibration modes, two pendulum type A dynamic vibration absorber is required.

[Problem to be solved by the invention 3 As is clear from the above explanation, the conventional vibration damping device has
There were the following problems.

(Since the cable is stretched from the ω tower, it is difficult to find a place to install it.

(b) Coulomb friction! The damping force is unstable because it is damped by friction.

(C) In the conventional pendulum type dynamic vibration absorber, the length of the arm increases as the natural frequency decreases.

(d) It cannot be handled when there are two vibration modes in the structure to be damped.

(e) It is not possible to easily respond to changes in the amount of vibration of the structure to be damped.

(f) The cost will be high. [Means for Solving the Problems] The present invention has been made to solve the problems as described above. At the same time, a weight is attached to the top of the arm or the end of the second pin, and a weight is attached between the first arm and the second arm, between the first arm and the support frame, or between the support frame and the second pin. between the two arms or the second
An attenuator is provided between the arm and the first pin.

Further, the present invention provides a dynamic suction IM device for a structure, in which an end of the first arm is rotatably fitted to a first pin provided on the structure or a support frame, and the other end There is a second
The pin is fitted, and one end of the second arm is fitted to the other end of the second pin, and the first arm and the second arm are fitted as necessary.
A spring is interposed between the arms, a weight is attached to the other end of the second arm, the top of the first arm, or the end of the second pin, and a damper is provided between the first arm and the second arm. The device with the attached device is fixed in parallel to the structure, a link is interposed between the second pin and the descending second pin, and a link is interposed between the second arm and the adjacent second arm. Two arms and a second pin are fixed, and the other end of the first arm and the second pin are slid together to form a parallel type.

[For production]

When vibration occurs in a structure to which the dynamic vibration absorber of the present invention is attached, the vibration is transmitted to the support frame, the first pin, the first spring, the first
The vibration is transmitted to the arm, the second pin, the second spring, and the second arm, but the vibration of the second arm and the structure is absorbed by a damper interposed between the first arm and the second arm. dampen the vibrations of the structure as much as possible.

Furthermore, in the parallel type, the movements of the second pin and the second arm are linked by a link, and they operate all at once, thereby damping the vibration of the heavy fi fJ structure as much as possible.

〔Example〕

FIGS. 1(a) and 1(t) show an embodiment of the present invention, in which (a) is a front view and (b) is a side view.

In the figure, (1) is the support frame, (20')
is a bearing fixed to a support frame (1) and fitted with a first pin (3), and a first spring (11,
(19'), the lower end of the first arm al19 is rotatably inserted, and the upper end of the first arm (1Q) is fitted with the second pin α. A second spring 1119.(18') is inserted between both ends of the pin αD (however,
This second spring (1, (18') may not be present)
Arm (2).

f5J, (is movably fixed by five, and pins (26) and pins (24) and (24') are fixed to the first arm αG and second arms (2) and (2'), respectively. and further pin (26) and peer (24),
Attenuators (91, (9')) are installed between (24').

Next, the operation will be explained. In Figure 1 (-), the support frame (1) fixed to the allocated structure is indicated by the arrow (25
), this vibration is caused by the bearing (a).

(20'), the first pin (3) and the first pin, (1
9'), first arm ue, second spring α seconds, (18'),
Second pin (17) and second arm (2), (2')
A weight (4) that is integrated with the.

(It is transmitted in the order of four, and is braked by the if2 damping slides (9) and (9') provided between the first arm ([19) and the second arms (2) and (2').
2 pins (1η is in the direction of the arrow (27), and the weight (4)
, (4') vibrate in the direction of arrow (26), and dampers (9), (99) expand and contract for braking action. Spring 0 barrels.

(18') is subjected to alternating repeated stresses.

FIG. 2 is a schematic diagram for explaining the mechanism of the 2#i pendulum type dynamic vibration absorber shown in FIG. 1 in an easy-to-understand manner. In the figure, (1) is the structure to be damped or the support frame, (A) is the bearing fixed to the support frame (1), and (3) is the bearing fixed to the support frame (1).
) is the first pin fitted to bearing 4, σ■ is bearing (1)
and a first spring coupled to both the first arm αυ.

The second spring (1311-t) is connected to both the first arm αe and the second arm (2), but the spring α frame may not be necessary.The first arm ae and the second arm ,
A second pin αη is fitted in each, and the weight (4) is fixed to the end of the second arm (2) so that its position can be changed. Then, the first arm screams and the second arm (2
) Since the attenuator (9) is installed diagonally between the two, it is possible to absorb kinetic energy.

Usually the second arm (2) and the attenuator (9) are connected to the first arm α.
e biconcave ((equipped symmetrically.

Although a piston type damper (9) is illustrated, a viscoelastic damper (9) may also be used. Also, the mounting positions are between the support frame (1) and the second arm (2), between the support frame (IJ and the first arm), and between the first pin (3).
) and the second arm (2), etc., where the device moves relative to each other when it vibrates.

FIG. 3 is a front view of a two-pendulum parallel type dynamic vibration absorber according to another invention of the present invention. In the reasons, (1) to (9), (
IE9-(24) are the same as the case j in FIG. 1, so their explanation will be omitted. (t5) is a fixing bolt (28) for attaching the entire device to the structure to be damped via the support frame (1);
) are links rotatably mounted between the parallel second pins αD and between the parallel second arms (2), and only the two rows on the near side are visible in the figure.

(29) is a weight fixed to the top of the first arm (1e) with a screw (26), and (30) is a weight that can be fixed to both ends of the second pin αη. The device is shown in which the basic units shown in FIG. 1(a) are arranged horizontally in six dishes.

Next, the operation of the two-bar parallel pendulum type dynamic vibration reducer will be explained. The principle of vibration is exactly the same as that of the basic structure shown in Fig. 1, but when the structure to be subjected to vibration becomes large, such as the main tower of a long bridge, the principle of vibration is simply the same as that of the basic structure shown in Fig. 1. Even if several dynamic vibration absorbers are installed side by side, it is expected that in actual dynamic vibration absorbers, differences will occur in the amplitudes and phases of the individual pendulums, causing them to come into contact. Therefore, it becomes necessary to provide a link (28) as described above to interlock each unit. However, since it is necessary for the front side and the opposite side to vibrate simultaneously in the same direction and with the same amplitude, in this parallel dynamic vibration absorber, the first arm αe and the second pin female are slid together, and the second pin αη and the second arm (2) are fixed. 2 to 4 more links (28
) to make all pendulums interlock 0
As a matter of course, the weight (4
), (29) and (30) are also adjusted.

It is known theoretically that if the system is taught and operated as described above, the vibration damping effect is extremely large. Fig. 4 is an approximate dynamic model diagram of the two-bar pendulum type dynamic vibration absorber shown in Fig. @1. It is known that the solution to the equation of motion based on this dynamic model diagram is expressed by equation [1].

However, when X5t=Fo/, is the force F. The static deflection of the main vibration system due to K ω2 = 祿; The natural angular frequency β of the dynamic vibration absorber is β = -/
The mass ratio of the dynamic vibration absorber to the main mass
o) δ = ω2 /'11 The ratio of the natural angular frequency of the vibration sucker and the main vibration system 1 = pA +, is the ratio of the frequency of the external force to the natural angular frequency of the main vibration string ) to the amplitude = V to 7
〒〒2-attenuation is μ-C/fuω.

FIG. 5 is a resonance curve diagram of the above equation [1]. The figure shows β=π
However, in actual damping of the main tower of a long bridge, β = '
/200 <'It's leprosy. In the figure, when μ=0 (excluding the attenuator), the displacement due to resonance becomes infinite in two places. Also, when μ = ω (fixed attenuator), “/
, = 1.0, it can be seen that the situation is dangerous. It is shown that the safest state is reached when μ=0.32 to μ=0.10.

In the two-bar pendulum type dynamic vibration absorber, adjustment is mainly made by changing the position and weight of the weight in order to create the above-mentioned safe condition.

Figure 6 shows the dynamic vibration absorber shown in Figure 1 or Figure 3.
In addition to 4), the weights (29) and (30) are connected to the second pin α.
This is a dynamic model when installed near η.

FIG. 7 is a resonance plane PiI diagram for explaining the system shown by the above dynamic model. In the figure, C2=C0=0(
(excluding the attenuator), the displacement due to resonance is maximum at six locations (
(hazardous condition), with two minimum values in between. In other words, it shows that vibration can be suppressed corresponding to the two vibration modes of the main vibration system.However, in an actual dynamic vibration absorber, C2,
I'm trying to find C3.

〔Effect of the invention〕

A long-period dynamic vibration reducer was obtained in space. Furthermore, in order to obtain an even longer period, the second arm may be further extended. Also, by installing an attenuator between the first arm and the second arm, space could be used effectively. Furthermore, inserting coiled springs along the outer peripheries of the first and second pins is effective in making the device compact. Furthermore, since the basic unit in this invention was developed with parallel use in mind, by adding simple elements, for example, as construction work progresses, its natural frequency, weight, and other vibration actors can change. Even in the case of

[Brief explanation of the drawing]

Figures 1 (a) and (b) show 41 examples of the present invention, where (a) is a front view, (b) is an individual view, Figure 2 is a schematic diagram, and Figure 3 is a diagram. 4 is a front view showing another invention of the present invention; FIG. 4 is a dynamic model diagram of the present invention; FIG. 5(2) is a resonance curve diagram thereof; FIG.
The figure is a diagram of its resonance curve. In the figure, (1) is the support frame, (2) is the first second arm, (3) is the first pin, (4) is the first trowel, (5) is the fixing screw, (9) is the attenuator, (IQ is the fixing bolt, (te is the first arm, αη is the second pin, bet is the second spring, C1 is the first spring, ■ is the bearing, (23) is the pin, (24) is the pin,
(28) is a link, (29) is a weight, and (60) is a weight. In each figure, the same reference numerals indicate the same or corresponding parts. Agent Patent Attorney Tadashi Sato Year 1 Cause (a) (b) 1 Defective frame 17: 11A 2 Pin 26 Ominai Riki 2 Scroll 2 A-1-18 Scroll 2 l
r'l''2'7:rLD3 1A1 Hi-N 19゛Scroll 1 trb β
Emperor 1st. 2! 4, Senshu Iku 20 Bearing 5/Measuring screw 23 Bin 95 Kogyo 8
24 pin 16: *17-m 25 trench recommendation $2
Figure 3 Figure 4 Figure 5 ωn jI6 Peng 70%Jn

Claims (2)

[Claims] (1) In a dynamic vibration absorber for a structure, one end of the first arm is rotatably fitted to a first pin provided on the structure or support frame via a spring, and the other end of the first arm is is the second
A pin is fitted, and one end of the second arm is fitted to the other end of the second pin, and if necessary, a spring is interposed between the first arm and the second arm. A weight is attached to the other end, the top of the first arm, or the end of the second pin, and between the first arm and the second arm, or between the first arm and the support frame, or between the support frame and the second pin. A two-bar pendulum type dynamic vibration absorber, characterized in that a damper is provided between two arms or between the second arm and the first pin. (2) In a dynamic vibration absorber for a structure, the end of the first arm is rotatably fitted to a first pin provided on the structure or the support frame via a spring, and A second pin is fitted to the end, and one end of the second arm is fitted to the other end of the second pin, and if necessary, a spring is interposed between the first arm and the second arm. , a device in which a weight is attached to the other end of the second arm, the top of the first arm, or the end of the second pin and an attenuator is attached between the first arm and the second arm is parallel to the structure; and a link is interposed between the second pin and the adjacent second pin, and a link is interposed between the second arm and the adjacent second arm to connect the second arm and the second pin. A two-bar pendulum type dynamic vibration absorber, characterized in that the other end of the first arm and the second pin are slidably connected to each other.