JPS6255017B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for preventing vibrations of machines, etc., and particularly to a dynamic damper.

Conventionally used manual techniques to prevent machine vibrations are: (1) Elastic support (2) Sturdy foundations (3) Suspended foundations (4) Vibration isolation grooves or vibration isolation walls (5) Phase control drive system method Vibration prevention method using phase control drive system (1979 Patent Application No. 127436) Preventing mechanical system vibration by controlling the rotational phase of the motor (Nikkei Mechanical November 1979 issue No. 8)
Page) Vibration prevention by phase control drive system (electric) (Proceedings of the 910th Annual Meeting of the Japan Society of Mechanical Engineers No. 800
-19, December 9-10, 1980, Tokyo; Environmental Engineering, pages 15 to 22) (6) Active control (7) Dynamic dampers, etc.

Among these, the dynamic damper, as shown in Fig. 1, has a main vibrating body 1, which is a controlled object such as a machine that is subject to vibration control, supported on a foundation 3 by a spring 2 to form a main vibration system 4. , to which a damper system 7 consisting of a damper vibrating body 5 and a spring 6 is attached via a spring 6.

Here, m: Mass of main vibrating body 1 k ₁ : Spring constant of main vibrating system 4 md: Mass of damper vibrating body 5 k ₂ : Spring constant of damper system 7 x _st : Static displacement p of main vibrating body 1 =√ ₁ : Main vibration system natural circular frequency q=√ ₂ : Damper system natural circular frequency, and periodic external force Psinωt acts on the main vibration body 1. The equation of motion at this time is md ² x ₁ /dt ² +k ₁ x ₁ −k ₂ (x ₂ −x ₁ )=Psinφt−
(1) ^mdd2x2 / _dt2 + _k2 ( _x2 - _x1 )=0-( ² ). The amplitude of forced vibration with circular frequency ω of such a system is |x ₁ /x _st |=(1-ω ² /q ² )/D-(3
) |x ₂ /x _st |=1/D −(4). Here, D={(1-ω ² /q ² )(1+k ₂ /k ₁ -ω ² /p
² ) _-k2 / _k1 }-(5). The purpose of adding a damper is to prevent the main vibration system from resonating at ω=p −(6). From equation (3), ω=q
Since the displacement of _{the main} vibrating body becomes 0 when At this time, the magnification of the forced vibration is |x ₁ /x _st |=(1-ω ² /p ² )/{(1-ω ² /p ² )(1+R-ω ² /p ² ) for the main vibration system. −R} −(9), and when ω=p, |x ₁ /x _st |=0. That is, the main vibrating body is stationary. However, even if a damper with such a design is added, the system will have a new natural frequency ω ₀ =p {(1+R/2)±(R+R ₂ /4)〓}〓-
(10) occurs, so a new resonance point occurs at ω=ω ₀ . Therefore, this type of damper has ω=
Valid only near p. This relationship between the main vibration system and the damper vibration system is illustrated in FIGS. 2 and 3.

In this way, conventional dynamic dampers have a simple structure, are therefore inexpensive, and do not require the addition of energy for vibration isolation, which means they are energy-saving, which is a special advantage. On the other hand, with respect to the periodic external force Psinωt, it is effective only near ω=p, and on the contrary, it has the opposite effect when ω= _ω0 . Moreover, ω=p and ω=ω ₀ , that is, p and ω ₀ are close to each other. Therefore, if you are not careful, there is a risk that the vibrations will be amplified by installing the dynamic damper, or that the opposite effect will occur.

Therefore, it is desired to improve the above-mentioned problems in these conventional dynamic dampers.

This invention solves the above-mentioned problems while retaining the advantages of a dynamic damper, and provides a dynamic damper that can always reliably damp the vibration of the main vibrator even if the circular frequency ω of the main vibrator changes. The purpose is to provide

Corresponding to this purpose, the dynamic damper of the present invention includes one container and the other container, both of which can contain a liquid mass substance, and which are connected by a flexible hose so that the liquid mass substance can flow through each other. , a dynamic damper comprising a damper system connected to a main vibration system including a controlled object that is an object of vibration control, wherein at least a portion of the damper system is configured in the one container, and The present invention is characterized in that the vibration of the main vibration system is controlled by adjusting the mass of the damper system by supplying and discharging the mass substance to and from the other container.

The details of this invention will be explained below with reference to the drawings showing one embodiment.

In FIG. 4, reference numeral 11 denotes a vibration-suppressed object to be subjected to vibration control, such as a machine, which constitutes a main vibrating body _M1 together with a tank 18, which will be described later, and has a spring constant _k1 .
It is elastically supported on a foundation 13 via a spring 12.

A tank 18 is attached to the vibration damped body 11 . A tank 19 is attached to this tank 18 via a spring 16 having a spring constant k ₂ . However, this tank 18 is not attached to the vibration-damped body 11, but is separated from the vibration-damped body 11 and attached to the foundation 13.
It can also be placed on top. The tank 19 functions as a damper vibrating body _M2 while containing a liquid 22, which will be described later. Tank 18 and tank 19 are connected by a flexible hose 21.
A liquid 22 with a heavy specific gravity such as mercury is stored in the tank 18 and the tank 19. This liquid 22 can flow between the tank 18 and the tank 19 through a flexible hose 21, and its flow rate is controlled by a valve 23. and is controlled by a valve 24 and a pump 25. By supplying and discharging the liquid 22 to and from the tank 19, the value of the damper mass md of the damper vibrating body _M2 changes. However, since the mass of the main vibrating body M ₁ is mainly determined by the mass of the damped body 11 such as a machine, it does not change significantly due to the movement of the liquid.

Dynamic damper 10 configured in this way
In this case, when a periodic external force P sin ωt acts on the vibration damped body 11 such as a machine, first, so that the condition p=q, that is, k ₂ /k ₁ =md/m=R is satisfied, The amount of liquid 22 in tank 18 and tank 19 is adjusted in advance. if, i.e. the periodic external force
When Psinωt is working and does not change at ω=p, |x ₁ /x _st |=0, and the valves 23, 24 and pump 25 do not operate. Therefore, the amount of liquid in tanks 18, 19 remains unchanged. In this state, the main vibrator _M1 has stopped vibrating.

Next, when ω changes and approaches ω=ω ₀ , that is, ω ₀ =p{(1+R/2)±(R+R ² /4)〓}〓, the main vibrating body M ₁ tries to vibrate violently. , valves 23 and 24 are opened and pump 25 is activated to move liquid 22 between tanks 18 and 19; That is, the value of md is changed so that 1-ω ₀ ² /q ² =0. That is, md=k ₂ /ω ₀ ^2As a result, |x ₁ /x _st |=0, so even if the periodic external force changes from Psinωt=Psinpt to Psinω ₀ t, |x ₁ /x _st |=0 becomes. That is, the vibration of the main vibrating body _M1 also stops in this case.

The valves 23, 24 and pump 25 are operated as follows. That is, as shown in FIG. 5, a circular frequency detector 26, an arithmetic device 27 and an operating device
is prepared, and the value of ω is detected by the circular frequency detector 26. With respect to ω, the operation amount of the valves 23, 24 and the pump 25 necessary for md at which the vibration of the main vibrating body _M1 is minimized is calculated by the calculation device 27. Based on the calculation result, the operating device 28 controls the valves 23, 24,
Operate the pump 25.

In addition, as another example of controlling a dynamic damper, as described above, instead of detecting the circular frequency ω of the main vibrating body _M1 , the magnitude of the vibration itself of the main vibrating body _M1 is directly detected, Valves and pumps may be operated to eliminate this vibration. In this case, as shown in FIG. 6, a vibration detector 29, a command circuit 31, an operating device 32, and a memory circuit 33 are provided. Then, the vibration of the main vibrating body _M1 is detected by the vibration detector 29. The command circuit 31 operates the valves 23, 24 and the pump 25 so that md changes one after another. The storage circuit 33 stores the relationship between the operation amount and the vibration value of the main vibrating body _M1 at that time. Among the combinations stored in the memory circuit 33, the combination that gives the minimum vibration is determined and selected. Select the operation that provides the minimum condition and perform it. As a result, the value of the vibration of the main vibrating body _M1 is set to the minimum. If the vibration of the main vibrating body _M1 changes, the command circuit 31 works again and repeats the above operation. Therefore, fluctuations in ω are always followed, and the main vibrating body is always set to the minimum vibration value. In the above-described repeated operations, the vibrations of the main vibrating body _M1 are compared, and the conditions under which the vibrations are small are stored in the memory circuit 33, and the conditions where the vibrations are large are deleted. Therefore, the memory circuit 33 does not require a large number of memories. Further, the vibration of the main vibrating body _M1 is automatically tracked in the direction where it becomes smaller.

In this way, the drawbacks of the conventional dynamic damper are eliminated, and the vibration of the main vibrating body stops even if ω changes. Further, even when ω=ω ₀ , the vibration does not diverge and stops. Further, since the valves 23, 24 and the pump 25 operate only when ω changes, there is no consumption of large power or energy.
Furthermore, the structure is simple. Therefore, the present invention maintains the advantages of conventional dampers and overcomes the adverse effect on fluctuations in ω, which was a decisive disadvantage. That is, the main vibrating body always stops vibrating in response to changes in ω.

FIG. 7 shows a dynamic damper according to another embodiment of the present invention, in which the pump 25 of the previous embodiment is not used. That is, in the case of the embodiment shown in FIG.
b, and each flexible hose 21
Valves 35, 36 and automatic valves 37, 38 on a and 21b
Place. In this case, the automatic valve 37 only allows the liquid 22 to flow from the tank 18 to the tank 19, and the automatic valve 38 allows the liquid 22 to flow from the tank 19 to the tank 18.
It is assumed that the liquid 22 is allowed to flow toward.

In such a configuration, Psin is applied to the main vibrator _M1 .
When a periodic external force of ωt acts, the main vibrating body M ₁ vibrates. As a result, the tank 18 also vibrates. Therefore, the liquid 22 in the tank 18 is shaken. That is, pressure fluctuations occur. When valve 35 is open, liquid 22 is directed to automatic valve 37. automatic valve 3
7 acts only in the discharge direction and does not cause backflow, so the liquid 22 flows only in one direction, and as a result, the liquid moves into the tank 19 and fills it. When vibration isolation of the main vibrating body _M1 is performed, the valve 35 is closed and the amount of liquid in the tank 19 becomes constant. In other words, the damper mass md is required for vibration isolation of the main vibrating body _M1 . To reduce the amount of liquid in the tank 19, the valve 36 is opened and the automatic valve 38 causes the main vibrator M ₁
until the liquid stops vibrating (tank 18).
(inflow) is repeated. To control the operation of the valves 35 and 36, md is controlled to minimize the vibration of the main vibrating body _M1 . That is, as described above, this is performed by detecting ω of the periodic external force Psinωt acting on the main vibrating body _M1 , or by detecting the vibration acceleration of the main vibrating body _M1 .

As is clear from the above explanation, according to the present invention, when the disadvantage of the conventional dynamic damper, that is, when ω of the periodic external force P=sinωt of the main vibrating body changes, due to the installation of the dynamic damper, the The drawbacks such as the significant increase in vibration of the main vibrating body are completely overcome. The advantage of the dynamic damper, that is, |x ₁ /x _st |=0 at ω=p, is completely effective in this invention, and the structure of the device is not complicated.
The price is not expensive either.

Note that the amount of movement of the liquid 22 between the tanks 18 and 19 can of course be controlled manually as well as automatically.

[Brief explanation of the drawing]

Fig. 1 is a configuration explanatory diagram showing a conventional dynamic damper, Fig. 2 is a graph showing the vibration of the main vibration system in the conventional dynamic damper, and Fig. 3 shows the vibration of the damper system in the conventional dynamic damper. 4 is a configuration diagram showing a dynamic damper according to an embodiment of the present invention, FIG. 5 is a configuration diagram showing an example of a dynamic damper control device, and FIG. 6 is a configuration diagram showing an example of a dynamic damper control device. FIG. 7 is a configuration diagram showing another example of the dynamic damper according to another embodiment of the present invention. M ₁ ... Main vibrator, M ₂ ... Damper vibrator, 11
...Damped body, 12...Spring, 13...Foundation, 1
8, 19... Talc, 21... Flexible hose, 22... Liquid, 23, 24... Valve, 25...
pump.

Claims (1)

[Scope of Claims] 1. A container comprising one container and another container that are both capable of storing a liquid mass substance and are connected by a flexible hose so that the liquid mass substance can flow through each other,
In a dynamic damper including a damper system connected to a main vibration system including a controlled object that is an object of vibration control, at least a portion of the damper system is constituted by the one container, and the one container contains the damper system. A dynamic damper characterized in that the vibration of the main vibration system is controlled by adjusting the mass of the damper system by supplying and discharging a mass substance to and from the other container. 2 When the circular frequency of the controlled object is ω and the spring constant of the damper system is _k2 , the mass of the damper system is
The dynamic damper according to claim 1, characterized in that the mass material is supplied and discharged so that md approximately satisfies √ ₂ =ω.