KR101202569B1

KR101202569B1 - Dynamic Absorber Using Electromagnet

Info

Publication number: KR101202569B1
Application number: KR20100104065A
Authority: KR
Inventors: 이순희
Original assignee: 이순희
Priority date: 2010-10-25
Filing date: 2010-10-25
Publication date: 2012-11-19
Also published as: KR20120042384A

Abstract

The present invention relates to a vibration control technology, and more particularly, to a dynamic reducer using a restoring force of an electromagnet.
The dynamic reducer of the present invention is configured by using an electromagnet and a permanent magnet instead of using a spring as a means for applying a restoring force to the mass. It consists of a magnet 2 and an electromagnet 3 that is charged inside the housing 1. The dynamic reducer of the present invention can be used for vibration control of a machine by attaching it to a machine causing vibration in the same manner as a conventional dynamic reducer composed of a metal spring and a mass.
The dynamic reducer of the present invention has the same basic function and method of use as a conventional dynamic reducer composed of a metal spring and a mass. However, the dynamic reducer of the present invention, unlike the conventional dynamic reducer can adjust the spring constant in a very simple way by adjusting the strength of the current flowing in the electromagnet, it can be used in a machine having a variety of rotational speed, the operating speed is constantly changing It can also be used on machines and can be arbitrarily adjusted even when mounted on the machine.

Description

Dynamic Absorber Using Electromagnet

The present invention relates to a vibration control technology, and more particularly, to a dynamic reducer using a restoring force of an electromagnet.

Rotating machines such as motors, fans, and pumps and reciprocating machines such as internal combustion engines inevitably cause vibrations during operation, and when the vibrations generated from these machines are transmitted to the surroundings, they cause anxiety and discomfort to humans and damage to life. Not only can cause damage to the building structure in which the machine is installed, it can cause the malfunction of the precision equipment and control system installed nearby, reduce the precision of vibration-sensitive precision measuring equipment, optical equipment, precision processing equipment, This may cause the failure of these machines. In addition, when vibration is transmitted to the building structure, it may cause structure pollution (Structure Borne Noise) to cause noise pollution.

Therefore, in order to prevent the vibration generated from the machine that causes the vibration to be transferred to the surroundings, the machine is supported on a structure such as a building floor using a vibration isolator. Thus, blocking vibration from being transmitted to the surroundings is called dustproofing. The vibration isolator uses an elastic body that has a restoring force to restore to its original state when deformation occurs, such as a rubber pad, rubber mount, metal spring mount, or air mount.

For vibration protection, when a vibrating object with mass m is supported by an elastic body with spring constant k and a damper with damping coefficient c, one vibration system is achieved. The simplest vibration system is one mass, one spring and one The case of a damper and the mass oscillating in only one movement direction (for example, up and down direction) is called a single degree of freedom vibration system.

When dust-proofing a machine that causes vibration, the machine itself is regarded as one mass, and a plurality of springs of the vibration isolator supporting the machine is regarded as one spring having one equivalent spring constant, and there is no damper ( Normally, damper is not used for the vibration of the machine, and the damping effect due to the air resistance and the internal damping of the material of the spring is neglected.) It is assumed that the machine vibrates only up and down. It is enough to design.

When the excitation force, which is the force of the harmonic function that causes vibration, is applied to the mass of the single degree of freedom vibration system, the equation of motion of the vibration system is as follows.

When a sufficient time has elapsed after the excitation force is applied to the single degree-of-freedom vibration system as described above, the vibration state is stabilized (this is referred to as a "steady state"). The vibration amplitude of the mass, that is, the steady state vibration response, is represented by the differential equation. Expressed as the Particular Solution of

Where X is the amplitude of the steady-state response, ω is the angular velocity of the excitation force, and φ is the phase. The amplitude X of the double steady-state response is calculated by

, here

(Frequency ratio)

In the above formula, F / k is a static strain that is a deformation that occurs when a force corresponding to the amplitude of the excitation force is applied to the spring, and the value obtained by dividing the vibration amplitude by the static strain is called an amplification coefficient.

The amplification coefficient is shown in a graph as shown in FIG. 3, and the vibration amplitude of the mass increases infinity at the frequency ratio r 1, which is called resonance.

The vibration transfer rate is the amplitude of the force transmitted to the floor (F _t ) relative to the amplitude of the vibration-propulsive force applied to the machine (in rotating machines, an excitation force with an amplitude of meω ² occurs due to the unbalanced mass of the rotor). It is defined as the ratio of.

When the above and the vibration transmission rate is shown in a graph as shown in FIG.

The vibration transfer rate is made smaller than 1 as mentioned above.

When the vibration-inducing machine is supported by the elastic body to be dustproof as described above, the vibration-vibrating force applied to the machine can be prevented from being transmitted to the adjacent structure, but the steady-state vibration amplitude of the machine itself is considerably large. In particular, in the resonant zone where the frequency ratio is around 1, the amplitude of the machine becomes infinitely large. In the case of a rotating machine, the machine vibrates very largely because it always passes through the resonant zone when starting and stopping during operation. have.

As described above, in order to prevent the machine from vibrating very largely in the resonant region, a damper may be used or an elastic body may be made of a viscoelastic material such as rubber, which has a large dimmer of the material itself. In this case, there is a problem that the vibration transmission rate increases in the normal vibration state. In general, the damper has a problem that the effect is not very large and expensive in the vibration of small amplitude.

In order to solve the problem of the conventional machine vibration using the elastic body as described above, by attaching a dynamic absorber (Dynamic Absorber) to the dust-proof machine, to prevent the amplitude increase in the resonance region and to reduce the amplitude of the machine in the steady state Is being sought.

The dynamic reducer is a vibration system having a spring and a mass itself, and a conceptual diagram of attaching it to the machine and dust-proofing with an elastic body is as shown in FIG. 5. In this way, the vibration system with the dynamic reducer is a two-DOF vibration system. The equation of motion is as follows.

Where m ₁ k ₁ X ₁ is the mass, spring constant and amplitude of the machine, respectively, m ₂ k ₂ X ₂ is the mass, spring constant and amplitude of the dynamic reducer, respectively.

Solving the equation of motion is as follows.

Where Δ (ω) is (k ₁ + k ₂ -ω ² m ₁ ) (k ₂ -ω ² m ₂ )-k ₂ ² .

Since the function of the motion reducer eliminates the vibration of the machine itself, the amplitude of the machine should be zero in the above equation, so k ₂ ω ² m ₂ = 0, i.e.

This is done by matching the natural frequency of the dynamic reducer itself with the frequency of the vibration excitation force (hereinafter referred to as "vibration frequency"). Amplitude coefficient graph of the amplitude coefficient and dynamic reducer mass of the machine equipped with the dynamic reducer is shown in FIG.

Referring to the graph of FIG. 6, it can be seen that the vibration amplitude of the machine becomes 0 at the frequency ratio 1, that is, the resonance point, and when the frequency ratio increases to 2 or more, the vibration amplitude of the machine drops rapidly to 0.

A general dynamic reducer uses a metal spring as a spring, but once it is manufactured, the spring constant is invariant, so it cannot cope with changing the operating speed of the machine. Therefore, a separate dynamic reducer must be manufactured and attached according to the change of operating speed. do. And such a conventional dynamic reducer there is a problem that can not be used in the machine continuously changing the operating speed.

If you try to control the natural frequency by changing the mass of the dynamic reducer, not only does the dynamic reducer have to be disassembled in the machine, but it is also difficult to finely adjust the mass.

As described above, the dynamic reducer may be a very useful means to lower the vibration of the machine which has been dustproof using the elastic body. However, such a conventional dynamic reducer has a problem that can not respond to the change in the operating speed of the machine.

Therefore, there is a need for a dynamic reducer in which the spring constant can be arbitrarily adjusted. As such, the dynamic reducer with adjustable spring constant should be able to be adjusted in a simple manner while attached to the machine.

The dynamic reducer of the present invention is configured by using an electromagnet and a permanent magnet instead of using a spring as a means for applying a position restoring force to a mass, and having two cylindrical housings 1 and two ends respectively provided at both ends of the housing 1. It consists of a permanent magnet (2), and an electromagnet (3) inserted into the housing (1).

In the dynamic reducer of the present invention, when the intensity of the electromagnet is constant and the displacement is very small, the restoring force of the electromagnet is proportional to the displacement, and the spring constant k obtained by dividing the restoring force by the displacement has a constant value. Therefore, the dynamic reducer of the present invention is a dynamic reducer having a mass equal to that of an electromagnet and a constant spring constant.

The dynamic reducer of the present invention can be used for vibration control of a machine by attaching it to a machine causing vibration in the same manner as a conventional dynamic reducer composed of a metal spring and a mass.

The dynamic reducer of the present invention has the same basic function and method of use as a conventional dynamic reducer composed of a metal spring and a mass.

However, the dynamic reducer of the present invention, unlike the conventional dynamic reducer can adjust the spring constant in a very simple way by adjusting the strength of the current flowing in the electromagnet, it can be used in a machine having a variety of rotational speed, the operating speed is constantly changing It can also be used on machines and can be arbitrarily adjusted even when mounted on the machine.

1 is a longitudinal sectional view of a dynamic reducer of the present invention.
2 is a view showing the displacement of the electromagnet and the force acting on it.
3 is a steady state vibration response graph of a damper-free one degree of freedom vibration system.
Figure 4 is a graph of the transmission rate of the damper-free 1 degree of freedom dust system.
5 is a conceptual diagram of a vibration system equipped with a dynamic reducer.
6 is a vibration response graph of a vibration system equipped with a dynamic reducer.

As shown in FIG. 1, the dynamic reducer of the present invention has a cylindrical housing 1, two permanent magnets 2 provided at both ends of the housing 1, and an electromagnet inserted into the housing 1. It consists of (3).

The housing 1 is composed of a cylindrical body 11, a stopper 12 coupled to both ends of the body 11. And it is preferable that the mounting bracket 13 is provided on the side of the body 11, so that the housing 1 can be easily attached to the machine to be used.

The stopper 12 may be attached to the body 11 in various ways, but as shown in the figure, it is preferable to facilitate the disassembly and coupling by screwing using the fastening bolts 14. The stopper 12 and the mounting bracket 13 may be provided with fastening holes 15 so as to be easily attached to the machine to be attached. In the wall 11 or the plug 12 of the body 11, a wire hole 16 through which an electric wire for supplying electricity to the electromagnet passes.

Permanent magnet (2) is fixed to both ends of the body (11) of the housing (1), as shown in the magnet 12 to form a magnet seat coupled to the stopper 12, the permanent magnet (2) It is good to combine them and fix them with screws. As shown, the permanent magnet 2 couples the N pole and the S pole toward the inside of the body 11 of the housing 1.

The electromagnet 3 is charged inside the body 11 of the housing 1 to move in the longitudinal direction of the body. The electromagnet 3 is manufactured by forming the coil 32 which wound the electric wire many times in the exterior of the core 31 like a normal electromagnet. The direct current is applied to the coil 32 through the wire 33.

The core 31 of the electromagnet 3 has a mass by itself, but if the mass is not large enough, the additional mass 34 may be further provided at both ends. As shown in the drawing, the additional mass 34 may be screwed at both ends of the core 31 so as to be easily replaced with one having a suitable mass as necessary. The mass of the dynamic reducer becomes the mass of the whole electromagnet 3. In addition, the core 31 of the electromagnet 3 is provided with a bearing 35, so that the electromagnet 3 can smoothly move the housing 1 inside the body 11.

When direct current is applied to the coil of the electromagnet (3) in a certain direction, both ends become electromagnets with N and S poles respectively. do. In the dynamic reducer configured as described above, the electromagnet is applied to the electromagnet so that the permanent magnet 2 is formed with the same poles as both magnetic poles of the electromagnet.

When electricity is applied to the electromagnet 3 and becomes magnetic, both magnetic poles of the electromagnet are repulsed by a permanent magnet, respectively, so that both ends of the electromagnet are spaced apart from the permanent magnet at a constant distance d. Are spaced apart. The magnitude of the repulsive force generated is inversely proportional to the square of the distance and is proportional to the product of the strengths of the two magnets.

In the state where the two magnetic poles of the electromagnet are in equilibrium by permanent magnets of the same strength facing each other, as shown in FIG. 2, when the electromagnet moves by one displacement x as shown in FIG. The restoring force, the applied force, is calculated as follows.

,

Where C is the proportional constant and q ₁ q ₂ is the strength of electromagnets and permanent magnets, respectively.

In the case of the actual steady state vibration, since the vibration amplitude x is very small compared to the separation distance d between the magnetic poles, x ² can be ignored, and the restoring force is simplified as follows.

As can be seen from the above equation, when the strength of the electromagnet is constant and the displacement is very small in the dynamic reducer using the electromagnet (3) and the permanent magnet (2) as in the present invention, the restoring force of the permanent magnet is displaced in the direction opposite to the displacement direction. It can be seen that it occurs in proportion.

It can be seen that the spring constant (k) obtained by dividing the restoring force by the displacement in the dynamic reducer is calculated as follows.

That is, it can be seen that the dynamic reducer of the present invention has a mass equal to the mass of the electromagnet 3 and the spring constant becomes a dynamic reducer such as the above formula. When the intensity q ₁ of the electromagnet is adjusted by adjusting the intensity of the current applied to the electromagnet 3, the spring constant of the dynamic reducer is adjusted.

1 housing, 2 permanent magnet, 3 electromagnet,
11 body, 12 stopper, 13 mounting bracket,
14 fastening bolt, 15 fastening hole, 16 wire
31 core, 32 coil, 33 wire, 34 additional mass 3, 5 bearing

Claims

A housing (1) comprising a cylindrical body (11) and a stopper (12) coupled to both ends of the body (11);
Two permanent magnets (2) which are provided at both ends of the housing (1), one coupled to the N pole and the other to the S pole toward the inside of the housing (1);
The coil 32 is charged into the housing 1 to move in the longitudinal direction of the body, and the coil 32 is wound around the core 31 a plurality of times to form a coil 32. Electromagnet 3, to which direct current is applied through
The electromagnet 3,
Additional mass 34 is further provided at both ends of the core 31 to increase the mass of the electromagnet 3, and the core 31 is further provided with a bearing 35 so that the electromagnet 3 is provided with the housing 1. Dynamic reducer, characterized in that to be able to move smoothly inside the body (11).

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