JPS5950243A - Vibration absorbing device - Google Patents

Abstract

PURPOSE:To stop the vibration of a hull, i.e. a structure, which is subjected to the vibration, by providing a weight on the support lever in the form of a long rod which is cantilever-mounted to the vibrated structure, such weight being allowed to move in response to the change in frequency of the vibration of the vibrated structure. CONSTITUTION:The support lever 3 in the form of the long rod which is cantilever-mounted to a hull 1 is attached in a flexible manner at its one end in the pre-determined position through a support bracket 4, and a spring 5 is installed in-between the hull 1 to allow the support lever 3 to vibrate. The weight 6 which is mounted on the support lever 3 and is capable of changing its natural frequency k2 in response to the change in the distance from the point of support is moved by a motor 7 through a screw thread mechanism. The frequency omega of the vibration coming from an engine 2 is detected by an accelerometer 8. Based on the frequency detected by the accelerometer 8, a control device 9 operates the motor 7 to move the weight 6 so k2=omega. As a result, the vibration of the vibrated structure can be stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dynamic suction device used to reduce vibrations of an armrest.

Taking the example of a ship, the hull of the ship vibrates due to the operation of its engine, and the interior of the ship is extremely noisy.In order to eliminate this problem, dynamic vibration absorbers have traditionally been installed on the ship's hull. ing. The reason why ship hull vibration is eliminated by a dynamic vibration absorber is based on the following dynamic vibration absorption principle π.

In other words, the vibration system as shown in the first stage π (the quality of the maneuvered object i
= 7n1, spring constant -kx) When a periodic external force θ8ot acts, if the natural frequency p1 of this vibration system
- It resonates when ko is close to ω. However, -5 at this time, the second
A vibration system as shown in the figure (mass of the vibrated body - m2, spring constant -
By adding 2) to make ω=-p, , =, /E otoph stone-1, the added vibration system becomes the vibrating h''-1 source, as shown by the following formula. The vibration of the vibration system can be stopped.

The equation of motion of both dynamic systems is ``+::2''klX1+, 2(Xz-xl)+f&i
+mt ---ir) 2x2- m2 lower "-kz (Xz xl) ++
+ f2) Solution All XI ”” A1S! ! 1 (ot, )
(Assuming that 2== A25UIQJt, this (11,
Substituting it into formula +21 and rearranging it, we get (-ynlJ t1(
, + A2) A, k2A2= 0 ・=
13) -2A4 + (-tn2rv2+2)A
2-O-f41 When obtained from this equation as a function of A1 and A2tω, the formula shown in FIGS. 6 and 4 is obtained. Here, the amplitude is expressed as an amplitude multiplier for one static deflection of θ and J:Rl(H).

As is clear from this figure, A becomes 0 for a certain ω. That is, as can be seen from equation (4), c
o. For =3, [, teA, =0. At this time, A2=-θ/l<2 is obtained from equation (3). Therefore, if the entire vibrating system having a natural frequency equal to the external force frequency is added, the original vibrating system will no longer vibrate.

However, according to the above principle, \dJ'? The range in which e can be stopped is limited to a specific ω, as shown in Figure 3, and there is a resonance point on both sides of this ω, 1/i7, where the original vibration system resonates with infinite amplitude. There is a risk. Therefore, when a dynamic vibration absorber is used to stop the vibrations of a ship's hull, the natural frequency control section of the dynamic vibration absorber must be able to accurately follow changes in the frequency of the ship's engine.

However, conventional dynamic vibration absorbers have a poor ability to follow changes in the vibration frequency of a ship's engine, so none of them have been satisfactory in terms of actual vibration reduction. The present invention has been made in order to eliminate all the drawbacks of the conventional ρ, and it is possible to make the natural frequency accurately follow the change in the frequency of the ship's engine, thereby reducing the vibration of the ship's body, that is, the structure. π to ensure that the tile stops
The purpose of the present invention is to provide a vibration absorber.

The present invention provides for a vibrated body to be subjected to forced vibrations such that the distance 1I11 between the support handle and the fulcrum of the support handle can be changed. It is movably attached, and as it moves, the natural frequency of the support shaft vibration system increases or decreases by 2 [, 1 weight and the above-mentioned weight fully moves following the change in the frequency of 6 vibrations of the vibrated body. The gist is a dynamic vibration absorber comprising means for

Hereinafter, one embodiment of the present invention will be described based on the drawings.

(1) is a ship body which is a body to be vibrated, and the ship body (1) is forced to move by engines (2) g and J during navigation.

(3) is a support handle in the shape of an elongated stalk that can be lifted up from the hull (1) in a cantilevered state, and the support handle (3) has one end held in place via the support (4). It is attached so that it can be bent, and a spring (5) is inserted between the support handle (6) and the hull (1) so that the support handle (3) can vibrate. In this case,
As shown in Fig. 6, if the support handle (3) is made of spring material, the spring (5) can be fully inserted between it and the hull (1) (7 is not necessary).
6) is a weight that is attached to the support shaft (3) K and is movable Vτ, and whose natural frequency can be increased or decreased by 2 as the distance from the fulcrum changes. (7) is a motor for moving the weight (6), and the motor (7) is connected to the weight (6) via a screw-like groove. However, the mechanism for moving the weight (6) is not limited to the Renezi machine, and other mechanisms, such as a rack machine, may also be employed. (8)(
This is an acceleration section for detecting the vibration frequency of the engineering engine (2), and the output (i1!l) of the accelerometer (8) is connected to the control 1III device (9) for controlling the motor (7). .

Next, the operation of the present invention will be explained. First, the frequency ω of the vibrations generated by the engine (2) force is detected using an accelerometer (8) mounted near the engine (2) or the force that is the vibration source.Control 1 device (9) detects the acceleration discrimination (8) and adjusts the motor (
7) to move the weight (6) completely. Note that 2 is given to the natural frequency of the dynamic vibration absorber by the following formula.

When the support handle (3) of the dynamic vibration absorber is rotated by an angle θ, the displacement of the weight is -t-0, the extension of the spring is -1kO, then the reaction force = -Klkθ, and the equation of motion is Ml-θ=-K
Now that tkθ holds true, if y=t−θ, then as explained above, the present invention moves the weight and calculates 2=
Since ω is equalized, it is easy to control the natural frequency of the dynamic vibration reducer by 2, and the natural frequency of the dynamic vibration absorber can be made to accurately match the frequency θJ of the periodic external force. As a result, it is possible to reliably stop the vibration of the structure that is the vibrated body.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of a 1-degree-of-freedom vibration system, Figure 2 is an explanatory diagram of a 2-degree-of-freedom vibration system, and Figure 6 is a diagram of the relationship between the amplitude and frequency of the vibrated system of a 2-degree-of-freedom J-axis system. , Fig. 4 is a diagram of the relationship between the amplitude and frequency of the excitation vibration system of a two-degree-of-freedom vibration system, Figs. 5 and 6 are explanatory diagrams of the main parts of the present invention@h vibration absorber, and Fig. 7 is The mounting of the inventive dynamic vibration absorber is an explanatory diagram, and Figure 8 is an explanatory diagram of the relationship between the length from the fulcrum to the weight and the natural frequency. 1... wave moving body, 2... vibration source , 3... support pattern,
4... Support, 5... Spring, 6... Weight, 7...
- Motor, 8... Accelerometer, 9... Control device. Agent Patent Attorney Sanro Kimura Figure 1 Figure 2 Figure 5 Figure 7 Figure 81!1

Claims (1)

[Claims] A long support handle is attached so as to be able to vibrate in a cantilevered state to a vibrated body that is subjected to forced vibration, and a support handle is movably attached to the support handle so that the distance from the fulcrum of the support handle can be changed. A weight that can increase or decrease the natural frequency of the support handle vibration system by 2 in accordance with the movement of the IC, and a means for moving the weight to follow changes in the frequency ω of the to-be-moved object. Dynamic vibration absorber.