JPS61206841A - Exciting force variable type vibration damper - Google Patents

Abstract

PURPOSE:To obtain optimum vibration damping effect by providing two sets of vibration dampers which are independently controllable and varying synthetic exciting force of vibration dampers desirably from 0 to maximum while keeping the phase of the exciting force of the vibration dampers optimum to the exciting source. CONSTITUTION:Two sets of vibration dampers A, B are controlled by identical control units, 11a, 11b respectively. The synthetic exciting force by the vibration dampers A, B is put in inverse phase to that of the exciting source, but one of the vibration dampers A is controlled to +theta phase and the other B is to -thetaphase. By controlling this theta to 0 to pi/2, the synthetic exciting force can be controlled to a desirable magnitude.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] [Technical Field of the Invention] The present invention is directed to a structure vibrating in resonance with the excitation force of a vibration source, which is Involved in improving vibration dampers with variable excitation force that apply excitation force and reduce vibration.

[Technical background of the invention and its problems]

Vibration dampers are used in various structures, but here,
An example of application to ships will be explained.

In ships, the hull of the ship resonates with the excitation force generated by a reciprocating engine such as a diesel engine, and vibrations are often generated at a frequency equivalent to twice the rotation of the normal engine.

Therefore, as shown in Fig. 8, two unbalanced weights 1 and 2 are
are rotated in opposite directions to generate an excitation force in the vertical direction, which is then combined with the excitation force of the excitation source.

An invention for canceling vibrations by controlling to have an antiphase relationship has been carried out and is published in Japanese Patent Publication No. 52-30079. However, in this invention, although the phase relationship between the excitation force of the excitation source and the excitation force of the vibration damper can be controlled, the vibration excitation force of the vibration damper cannot be controlled.

Therefore, the magnitude of the vibration excitation force has been determined by either stopping the vibration damper and replacing the weight, or changing the radius of rotation of the rotating weight using an extremely complicated mechanism. It also lacked practicality.

In addition, the excitation force required for a vibration damper generally changes depending on the resonance frequency, and also changes depending on the presence or absence of cargo in ships, etc., so if the excitation force is adjusted to a certain point,
At other resonance points, there is a disadvantage that the effect is small or that resonance is even promoted.

On the other hand, as shown in FIGS. 9a and 9b, as shown in FIG. It is also known to prepare one set of unbalanced weights 3.4 in addition to the set of unbalanced weights 3.4, and to adjust the rotational phase relationship between the two sets using a differential gear 51 to adjust the overall excitation force. However, this required a complicated differential gear device 1i51, and there was no suitable method for controlling the phase of the combined excitation force, so it could not be used as a vibration damper.

[Purpose of the invention]

An object of the present invention is to enable the vibration excitation force to be able to arbitrarily control the magnitude of the excitation force during operation, and at the same time to control the phase of the excitation force to an arbitrary angle with respect to the excitation phase of the excitation source. The present invention aims to provide a deformable vibration damper.

[Summary of the invention]

The variable excitation force type vibration damper according to the present invention is designed to provide a structure that vibrates in resonance with the excitation force generated by an excitation source, in synchronization with the excitation force of the excitation source and in the opposite phase. In a vibration damper that reduces vibration by applying vibrational force to a structure, two sets of vibration dampers that can be controlled completely independently are installed, and the necessary deflection angle θ is calculated from the desired vibrational force. The vibration damper is controlled to a phase that is θ ahead of the opposite phase, and the other vibration damper is controlled to a phase that is delayed by θ from the opposite phase, so that an arbitrary composite excitation force can be obtained. It is characterized by:

[Embodiments of the invention]

The present invention will be described below with reference to the embodiments shown in FIGS. 1 and 2. First, for convenience, the basic concept of the present invention will be explained. 1 shows a schematic configuration of a variable excitation force vibration damper according to the present invention. In FIGS. 2a and 2b, 1 and 2 are unbalanced weights that mesh with spur gears 5 provided on their circumferential surfaces and rotate in opposite directions, and as they rotate, horizontal excitation forces cancel each other out. It is configured to generate vibrational force only in the vertical direction. This configuration is similar to a known vibration damper, and the unbalanced weights 1 and 2 are speed-controlled by a driving machine 6 directly connected to the weight 1. Furthermore, 3 and 4 are unbalanced weights which have the exact same structure as 1 and 2, meshing with spur gears 7 provided on their circumferential surfaces, and are driven by a driver 8 directly connected to the weight 3, and are unbalanced. It is placed on top of weights 1 and 2.

Hereinafter, for the sake of simplicity, the part made up of 1 and 2 will be referred to as a vibration damper A, and the part made up of 3 and 4 will be referred to as a vibration damper.

It is called B. The vibration dampers A and B have no mechanical communication at all and can rotate freely.

Now, if the unbalanced weight of the unbalanced weight is m (kg), the equivalent radius is r (m), and the rotational angular velocity is ω (rad/s), then the centrifugal force F generated by each weight is F=mrω" ( N) Q).

Now, as shown in Fig. 3, if we express the excitation force of the vibration damper according to the present invention with E in the horizontal direction and G in the vertical direction, Fz = F cos (ωt)
■Fy =Fsin(ωt) (3).

Since the two unbalanced weights 1 and 2 of vibration damper A are rotating in opposite directions in a symmetrical relationship with respect to the ν axis, the respective excitation forces can be expressed as subscripts 1 and 2 as shown in (a) below. 〜■ Formula.

Fzl =Fcos((II t) −@)F
yl==Fsin(ωt) ■Fz2
=Fcos(π-ωt)=-Fxl(eFy2 = F
cos(π-(II t) = Fyt (2) Therefore, if the combined excitation force is again set as FXaeFV&, it becomes (2) and the formula 0.

Fxa = Fxx +'Fx2= O(aFya=F
y1+Fy2= 2Fyl= 2Fsin(ωt)
(9) In other words, the horizontal excitation force is canceled out,
Only the excitation forces in the vertical direction are added together and doubled.

This is the principle of conventional, well-known vibration dampers.

Now, writing equation (9) in more detail, FVa = 2mrω”5in(ωt) (1
0), and it can be seen that the magnitude of the excitation force is a function of m, r, and ω. Of these, ω is uniquely determined in order to synchronize with the excitation source, so if you wanted to adjust the excitation force, you had to make m or r variable, but this It is difficult to find an effective way to make this variable.

In the present invention, a vibration damper B is further provided on top of the vibration damper A.
are placed one on top of the other, and are operated at the same ω while having a certain phase angle with respect to A. The excitation force is expressed by equations (11) to (14) with subscripts 3 and 4.

FzB=Fcos(ωt+20) (
11) Fy3=Fsin(+11 t+ 20)
(12) Fz4=Fcos(π−ωt+2
0)=Fxa (13)Fy4=Fsin(π
-ωt+20)=Fv3 (14) However, 2θ=phase difference between unbalanced weights 1 and 3. This relationship is shown in FIG.

If we set these combined vibrational forces as +Fvb from F, then (15
) and equation (16).

From F=o (ts)F
yb= 2Fya= 2Fsin(ωt+20)
(16) If we compare equations (9) and (16) here, we find that they are only out of phase by 20 from each other.

Now, if we consider a virtual phase between the phases of vibration dampers A and B, FVa and Fvb can be regarded as two excitation forces that lead and lag by θ with respect to this virtual phase. .

Therefore, if we rewrite equation (16), we get the following (17
) and (18).

FVa= 2Fsin (ω10> (1
7) Fyb = 2Fsin (ω = 10>
(18) If this is illustrated with the time axis as t, it becomes FIG. 5.

Let F be the excitation force obtained by combining equations (17) and (18), then Fy=2F(sin(ωt-θ)+5in(ωt+θ) according to the simple harmonic synthesis formula.
))=2r′rF 1 cos 2 e 5in(
ωt) (19).

According to this, the phase angle of F is always between Fulla and Fyb, as shown in Figure 5, and the excitation force is 1
It can be seen that it is proportional to cos e. In other words, it becomes. Substituting equation 0 into equation (19) results in equation (20) below.

Fv=2(τmr (11” 3go5in(ωt)
(20) Therefore, if this virtual phase is made to be in opposite phase to the excitation force of the excitation source, it will serve as a vibration damper.

FK = 2 Ebr (112
21), the desired excitation force FK can be obtained.

A specific example for implementing the present invention will be explained.

When equation (21) is solved for θ, the following equation (22) is obtained.

Since m and r are usually constants, the desired excitation force FK,
If the current angular velocity ω is known, θ can be found from (22).

Therefore, as a control device for a vibration damper according to the present invention,
In order to cancel the excitation force generated from the excitation source, it is necessary to generate a composite excitation force that is in the opposite phase to it, that is, shifted by π. The objective is to be achieved by controlling the phase so that it has a phase of π-θ.

FIG. 1 shows a circuit of a control device used in a variable excitation force type vibration damper according to the present invention. In FIG. 1, 11a.

11b is a synchronous control unit that controls the vibration damper A and the vibration damper B. Since the surface control units 11a and llb have the same configuration, the control unit 11a will be explained as a representative.

The excitation source phase pulse 13a and the damper phase pulse 14a are input to the phase angle discriminator 12a, and the phase difference signal 1 between the two is input.
5a is made. For example, if the phase difference signal 15a is compared with the phase difference setting signal 16a and the rotational speed of the vibration damper is controlled so that the signal 15a and the signal 16a are equal, the signal 16
If a is set to have an opposite phase to the vibration source, the phase of the vibration excitation force of the vibration damper will always be opposite to that of the vibration source, and a vibration damping effect can be obtained. The above is the control principle of the conventional vibration damper.

In the present invention, as shown in FIG. 1, the excitation force is set by the excitation force setting device 21 to be FK/2□mr. 2 of the denominator
a/1 m r is a constant determined by the dimensions of the machine. Next, angular velocity ω (the average of the angular velocities of vibration absorbers A and B, or either angular velocity since they are both stationary) is squared by a multiplier or a square calculator 22 to calculate ω2.

Next, the divider 23 divides the excitation force setting signal Fg/2[mr by the square of the angular velocity ω2 to calculate Fx/2Ehrω2. Further, the signal is squared by a multiplier or square calculator 24, 1 is subtracted, and 1/2 of the inverse cosine is calculated by a function calculator 25 to obtain θ.

As a result, the calculation of equation (22) is executed, and θ is determined. One of the obtained θ is added as is to the phase difference setting signal 16a of the damper control section 11a, and the other is inverted in sign by the sign inverter 26 to obtain 10. The configuration is such that this is added to the vibration damper control section 16b.

In this way, the vibration damper A is controlled to have an opposite phase, and the vibration damper B is controlled to have an opposite phase of −○, so that their combined excitation force always faces the opposite phase, and at the same time its origin The magnitude of the vibration force is θ=0
It is maximum when θ=■, and becomes 0 when θ=■, and can be controlled to any size in between.

In addition, in Fig. 1, we have taken as an example a method in which the excitation force is kept constant using the excitation force setting device 21 or controlled manually, but in reality, the degree of resonance of the structure differs depending on each ω. ,
The required excitation force is generally a function of ω as shown in FIG.

Therefore, as shown in FIG.
By calculating the excitation force setting value through the vibration excitation force setting device 21 in FIG. 1, the most effective vibration damping effect can be achieved over a wide range of speeds.

Also, if the excitation force simply needs to be proportional to ω2, then
Of course, it is sufficient to simply omit the arithmetic unit 22 and the divider 23 in FIG.

Generally, it is also easy to detect the amplitude of the vibrating portion, feed back that value, and internally control the excitation force of the vibration damper so as to minimize this amplitude.

Note that although the above explanation has taken analog control using an operational amplifier or the like as an example, it is of course possible to implement digital control using an electronic computer or the like. Furthermore, for convenience of explanation, a vibration absorber that generates vibrational force in the vertical direction has been taken as an example, but the scope of the present invention is not limited thereby.

It goes without saying that this method can be applied to anything that exerts an excitation force in any direction.

〔Effect of the invention〕

According to the present invention, while the vibration damper is in operation, the phase of the excitation force of the vibration damper with respect to the vibration source remains optimally maintained.

Since the combined vibration excitation force can be arbitrarily varied from 0 to the maximum, the optimal vibration damping effect can be obtained in all respects.
It has great practical value.

Since two vibration absorbers are required, there is a concern that the cost will increase, but each has only half the required capacity, so the cost does not increase much.

Furthermore, as a side effect, such a load with a large moment of inertia does not require much power once it is turned, but it requires a large power supply capacity for starting. However, if the power supply is divided into two units and the start times are set at different times as in the present invention, the power supply capacity can be reduced to one unit, which is an element of cost reduction, and overall it can be said that it is almost the same as the conventional product.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a control device for a variable excitation force type vibration damper according to the present invention, and FIGS. 2a and 2 b show a schematic configuration of a vibration suppressor with variable excitation force according to the present invention. A front view and a side view, Fig. 3 is a vector diagram for explaining the principle of generation of excitation force of the vibration damper, Fig. 4 is a vector diagram showing the phase relationship of the excitation force of two vibration dampers, Fig. 5 is a waveform diagram showing the relationship between the excitation force and the combined excitation force of the two vibration dampers, Fig. 6 is a perspective view showing the vibration force, and Fig. 9 a and b are the same. It is a front view and a side view which show a shaker. A, B... Vibration damper 1, 2, 3.4... Unbalanced weight 5.7... Spur gear 6, 8... Drive machine 11a, llb... Control section 12a... - Phase angle discriminator 13a... Excitation source phase pulse 14a... Vibration cancellation-like phase pulse 15a... Phase signal 16a... Phase difference setting signal 21... Excitation force setting device 22.24. 25... Arithmetic unit 23... Divider 26... Sign inverter (8733) Agent Patent attorney Yoshiaki Inomata (and one other person) Figure 1 Figure 3 Figure 4 Figure 5 Figure 6 W Figure 7 Figure 8 Figure 9 (cL) (!:))

Claims (2)

[Claims] (1) A structure that vibrates in resonance with the excitation force generated by an excitation source is vibrated by applying an excitation force that is synchronized with and in opposite phase to the excitation force of the excitation source to the structure. Two sets of dampers are installed that can be controlled completely independently, and the necessary deflection angle θ is calculated based on the desired excitation force. A variable excitation force type vibration damper characterized in that the vibration damper is configured to obtain an arbitrary composite vibration force by controlling the vibration damper to an advanced phase and controlling the other vibration damper to a phase delayed by θ from the opposite phase. Machine. (2) The argument angle θ is calculated using the following formula θ=1/2cos＾*＾1；((
F_K)/(2√2mrω^2))^2-1} (However, F
_K is a desired excitation force, ω is an angular velocity, and m and r are constants).
Variable excitation force vibration damper as described in Section 1.