JPH08270725A - Repulsion type magnetic damper, repulsion type magnetic actuator and repulsion type magnetic vibration proof base - Google Patents

Abstract

PURPOSE: To provide a repulsion type vibration control base and a magnetic damper in which unstable phenomenon in the lateral dislocation direction is stabilized and a repulsion type magnetic actuator in which more positive location controlling is possible. CONSTITUTION: A damper 1 is basically so constituted that the lateral dislocation direction is stabilized by holding a sprig 2 between repulsive permanent magnets 104a and 104b. A vibration control base is formed by using this damper 1 as free degree in the repulsion direction and free degree in the lateral dislocation direction are secured. Further, the damper 1 has function as a three axis actuator for changing flux density of the permanent magnet by actuating an electromagnet and the vibration damping base used this may be utilized as a three axis damper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a repulsion type magnetic damper, an actuator and a vibration isolation table for supporting a precision machine or the like with a vibration isolation effect.

[0002]

2. Description of the Related Art An anti-vibration stand is used to support a precision machine or the like in a state where vibration such as an earthquake is blocked.

To summarize the basic performance of the anti-vibration table, it depends on the high-frequency cutoff characteristic due to the flexible support. Therefore, the cutoff frequency has been widened by setting the natural frequency of the flexible support system as low as possible. That is, the anti-vibration table is required to have a sufficient stroke so that contact does not occur even when a low frequency is excited.

Conventionally used vibration proofing bases include a vibration proofing base using magnetic levitation, a vibration proofing base using an air spring, a vibration proofing base using a coil spring, and the like.

Of these, a vibration-isolating base using magnetic levitation has attracted attention as a supporting system for precision machinery and the like because it has no contact portion and thus has a good vibration-proofing performance.

A vibration isolating table utilizing magnetism is one in which a fixed body (fixed side) 101 and a movable table 102 shown in FIG. 12 are connected by a magnetic damper 103. The magnetic damper 103 used here is the attraction type magnetic damper 10 shown in FIG.
3a and the repulsive magnetic damper 103b shown in FIG. 12 (b). The attraction type magnetic damper 103a is a fixed magnet 104a.
And the table-side magnet 104b are attracted, and the repulsive magnetic damper 103b repels the fixed-side magnet 104a and the table-side magnet 104b.

[0007]

However, a drawback of the vibration isolating table utilizing magnetism is that the initial state of the system is unstable regardless of whether the suction type or the repulsion type is used. In the suction type, when there is no suction force, the anti-vibration table falls freely or the magnets attract each other. In the repulsive type, the repulsive force of the permanent magnet is essentially stable in the levitation direction, as known from the Earnshaw theorem, but it tries to escape to the permanent magnet because the lateral deviation direction is unstable. Power is exerted, and the anti-vibration table does not stop. Therefore, as a conventional method, in the case of the suction type, the vibration isolation table cannot be levitated unless the vertical direction is actively controlled and stabilized, and the repulsion type also actively stabilizes the lateral deviation direction. The function cannot be exhibited unless the lateral deviation direction is stabilized by a guide or the like.

However, since the conventional repulsive magnetic levitation system that passively stabilizes the lateral deviation direction uses a guide, there is a degree of freedom in the repulsive direction but no freedom in the lateral deviation direction, and active control is performed. The method of stabilizing by taking into account that there is no stroke in the lateral deviation direction because it controls so that lateral deviation is constrained, and if a large vibration occurs in the lateral direction, it will come into contact with the controller or control in the lateral deviation direction will be impossible and Cannot play the role of. In other words, the anti-vibration table requires that the table does not move regardless of whether the floor moves vertically or horizontally.
The lack of freedom and stroke is a fatal defect of the anti-vibration table.

In addition, in the vibration isolating table using the spring, the spring itself needs to be thick in order to float the vibration isolating table only by the spring force. Therefore, the lateral rigidity is increased and the natural frequency of the flexible support system is increased as much as possible. This is in the opposite direction to the requirements of the anti-vibration table for low frequencies.

From the above, it is desired to develop a repulsion type vibration proof base and a magnetic damper which stabilize the unstable phenomenon in the lateral deviation direction, and a repulsion type magnetic actuator capable of positively controlling the position.

The present invention has been made in view of the above circumstances, and is a repulsion-type vibration-proof base and magnetic damper that stabilize the unstable phenomenon in the lateral displacement direction, and a repulsion-type that allows more positive position control. It is intended to provide a magnetic actuator.

[0012]

To this end, the repulsive-type magnetic damper of the present invention is characterized in that the relative positions of a pair of repulsive permanent magnets are restrained by springs, and the repulsive-type magnetic damper of the present invention is used. The magnetic actuator is characterized in that a relative position of a pair of repulsive permanent magnets is restrained by a spring, and an electromagnet capable of generating a magnetic field acting on the magnetic fields of the pair of permanent magnets is provided. The anti-vibration table connects the fixed body and the table with a repulsion-type magnetic actuator, and the repulsion-type magnetic actuator restrains a relative position of a pair of repulsive permanent magnets with a spring, and a magnetic field acting on a magnetic field of the pair of permanent magnets. Is characterized by having an electromagnet capable of generating

[0013]

The repulsion-type magnetic damper of the present invention uses the repulsive force of a permanent magnet to levitate an object, which is the same as the conventional method. The feature is that it is stabilized in the form. The basic configuration of the damper stabilizes the lateral deviation direction by sandwiching a spring between repulsive permanent magnets. The spring used at this time only needs to have a spring constant necessary for stabilization in the lateral deviation direction, and a spring force is added to the force for levitating the object, but the repulsive force of the permanent magnet is mainly used. From this point, since both the degree of freedom in the repulsion direction and the degree of freedom in the lateral shift direction can be secured, it is also useful as an anti-vibration table, and is also characterized by its flexibility.

Further, the actuator has a function as a three-axis actuator capable of changing the magnetic flux density of the permanent magnet by causing an electromagnet to act, and the vibration isolation table using this has to be used as a three-axis vibration damper. You can

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of these inventions will be described below with reference to the drawings showing one embodiment.

In FIG. 1, reference numeral 1 is a damper. The damper 1 is provided between the fixed body 101 and the movable table 102. Each of the dampers 1 is composed of a permanent magnet, and the fixed magnet 104a and the table magnet 104b are arranged to face each other so that a repulsive force acts between them. The fixed magnet 104a and the table magnet 104b are restrained by the spring 2. Therefore, the stationary magnets 104a and the table magnets 104b are subjected to a restoring force in the three axial directions by the spring 2 in the three axial directions.

Therefore, in this damper 1, the method of levitating an object by utilizing the repulsive force of a permanent magnet is the same as the conventional method, but the unstable phenomenon in the lateral deviation direction is made passive by utilizing the lateral rigidity of the spring 2. The feature is that it is stabilized at.

Next, the actuator will be described.

As shown in FIG. 2, the actuator 3 is constructed by adding electromagnets 4 to 6 which exert a magnetic force to the damper 1 in at least one axial direction of one to three axes. The electromagnet 4 is for applying a magnetic force in the vertical direction (Z-axis direction) in the figure, and is configured by winding a coil 7 around the fixed-side magnet 104a, and the electromagnet 5 is arranged in the horizontal direction (X direction in the figure).
It is for applying a magnetic force in the axial direction and is constituted by winding a coil 9 around the iron core 8. The electromagnet 6 is for applying a magnetic force in the horizontal direction (Y-axis direction) in the drawing, and has the same configuration as the electromagnet 5. In the actuator having such a configuration, a repulsive magnetic flux flows from the N pole to the S pole between the fixed-side magnet 104a, which is a permanent magnet, and the table-side magnet 104b. The magnetic flux density can be varied by winding the magnetic flux with an enameled wire or the like around the side surface of the magnet, or by placing electromagnets 4 to 6 composed of an electromagnet coil having an iron core near the permanent magnet and passing a current through the coil. That is,
The support system itself as shown in FIG. 2 has the capability as a three-axis actuator, and this actuator 3 can be used as a three-axis vibration suppressor and also as a three-axis vibrator. it can.

FIG. 4 shows an example of dynamic characteristics when the actuator is used as a vibration exciter. This figure shows the current flowing in the coil on the horizontal axis and the vertical force generated by the actuator on the vertical axis, and the repulsive force increases by increasing the current and the magnetic flux between the permanent magnets. I know that

Further, FIG. 5 shows the frequency response when a constant alternating current is applied to the coil. From the frequency response, it can be seen that a force proportional to the current is generated at each frequency, and it has the ability as an actuator to generate a stable force over a wide frequency range.

Next, the horizontal excitation force will be described. Basically, the same as in the vertical direction, but an electromagnet wound around the iron core 270 was placed between the permanent magnets, and the exciting force in the lateral direction was examined. FIG. 6 shows the current flowing in the coil on the horizontal axis and the horizontal force generated by the actuator on the vertical axis. It can be seen that the repulsive force is increased by increasing the current and increasing the magnetic flux of the electromagnet 5. . Although the force that can be generated is reduced by the smaller cross-sectional area of the iron core, a sufficient horizontal excitation force can be obtained even with this number of windings.

Further, FIG. 7 shows the frequency response when a constant alternating current is applied to the coil 9. In the frequency response, it can be seen that a force proportional to the electric power is generated at each frequency, and it has an ability as an actuator that can generate a stable force in a wide frequency range.

By disposing the damper 1 or the actuator 3 as described above between the fixed body 101 and the movable table 102, the vibration isolation table 10 shown in FIG. 3 can be constructed. The vibration isolation table 10 includes a fixed body 101 and a movable table 10.
2 and 2 are connected by an actuator 3 or a damper 1.

Next, a vibration isolator using conventional magnetic levitation,
A comparison between the vibration isolation table using the air spring and the coil spring and the vibration isolation table 10 of the present invention will be described. First, a comparison with a vibration isolation table using a coil spring will be made. The anti-vibration table 10 using the actuator 3 of the present invention levitates the anti-vibration table using the magnetic repulsive force, but although it is magnetically levitated, it is a member having the same characteristic as a magnetic invisible spring. It is equivalent to a support system supported by. However, since magnetism has no mass, there is no resonance of the spring itself called surging as compared with the spring. The anti-vibration table according to the present invention also uses a spring for stabilizing the system, but the levitating force can remarkably reduce the mass as compared with an ordinary spring due to the magnetic repulsive force. That is, the frequency at which surging occurs can be increased by several tens or hundreds of times, and the adverse effect of surging is proportional to the mass, so that the displacement generated is negligible.
In addition, in order to actively control the anti-vibration table, an actuator is required in addition to the support system, and it is impossible to incorporate the actuator mounting position into the support system itself due to physical restrictions. Must be installed in a fixed position. This means that, considering that the disturbance flows in through the support system, the place where the disturbance is suppressed is not in the support system but in the vibration isolation table. Considering the disturbance energy that has flowed into the anti-vibration table, since the anti-vibration table is a flat surface and the energy is dissipated, it is not possible to remove all energy efficiently, and it is possible to remove it. Requires a restraint within the support system as in the system. Furthermore, in order to control the 3 axes, 3 locations (vertical Z
The actuator must be attached to the axis and the point where the force acts on the parallel XY axes. However, since the vibration isolation table of the present invention can control the three axis directions with one support system, the vibration isolation table itself can be simplified.

Next, a comparison will be made with a vibration isolation table using an air spring. Currently, it is the most used method for a vibration isolation table, but the weak points of the air spring are the complexity of the system and poor dynamic characteristics. In order to use air as a spring force and perform control, a pneumatic servo valve is required. The pneumatic servo valve controls the inside of the cylinder by increasing or decreasing the compressed air pressure. Therefore, the compressor, the pneumatic pipe, the servo valve, the pneumatic cylinder, etc. must be an accessory of the vibration isolation table, and the system becomes very complicated. Also,
Like the coil spring vibration isolation table, the air spring isolation table also requires actuators at three locations for three-axis control. Even worse is the dynamic characteristics of pneumatic servo systems. The frequency response of the pneumatic servo valve is only about several tens of Hz, and high frequency cannot be suppressed. In that respect, the vibration isolation table of the present invention can respond to a very high frequency because the dynamic characteristics of the electromagnetic force can be used as they are.

Finally, a comparison with the magnetic levitation type vibration isolation table will be made. The magnetic levitation type vibration isolation table has a suction type vibration isolation table and a repulsion type vibration isolation table, but the initial state of both systems is unstable. Therefore, it is necessary to prepare a control system for stabilizing the system and a control system for performing image stabilization.
Furthermore, the fact that there are two control systems causes a coupling problem of the control systems, and in a control system based on feedback such as the magnetic levitation type, the vibration-stabilized control system destroys the levitation-stabilized control system. Problems such as oscillation occur. Further, in the suction type, when trying to take a stroke in the suction direction, unless a large current is applied, the vibration isolation table does not float, and at the same time the system becomes non-linear and the conventional control method cannot be used. In addition, even if the repulsive type tries to take a stroke in the lateral deviation direction, it is difficult to take a stroke because a large current is required.

As described above, in the anti-vibration table of the present invention, one support system has the control elements of three axes, and the system at the time of control can be simplified. Furthermore, considering that the force acts, the anti-vibration table can be controlled by the flow path of the disturbance because the force acts in the support system, whereas in the conventional method, the anti-vibration table is passed by the support system. Since the control is performed, the method has a good control effect from the viewpoint of the control effect. Moreover, unlike the pneumatic servo valve, the controllable frequency band is not narrow, and it is possible to control a wide frequency band. Further, the frequency of the surging by the spring can be increased and the level thereof can be decreased.

(Experimental example) FIG. 9 shows an example of the result of an experiment on the vibration isolation performance in the vertical direction using the experimental apparatus shown in FIG. 8 and an amplifier for supplying a driving current. In the experiment, an accelerometer is installed on the antivibration table 10 of the present invention, and the displacement and speed obtained by integrating the signal of the accelerometer and the acceleration of the accelerometer output are fed back. As is clear from the figure, the vibration transmissibility to the anti-vibration table becomes less than 1 times at all frequencies by simply constructing a simple control system, and it has sufficient performance as the anti-vibration table.

The specifications of the anti-vibration table shown in FIG. 8 are such that the damper support capacity is set to 3 kg (12 kg for 4 axes), the coil spring linearity is 0.8 mm (4 pieces are used), and the number of drive coil windings is 2.
It has 40 volumes. The diameter of the rare earth magnet is 3 cm.
The neodymium magnet of was used. Further, an aluminum honeycomb table of 60 cm × 45 cm × 7 cm is coupled to the actuator, and an accelerometer is installed on the table to construct a system. The system is an extremely simple control system as is clear from FIG.

Next, the performance of the vibration isolation table will be described. The main purpose of the anti-vibration table is to suppress disturbance from below. The largest vibration as a disturbance from below is an earthquake, and a vibration-proof stand that does not move on the stage even if an earthquake occurs is desired.
The magnitude of vibration of the earthquake is specified by the seismic intensity, with a seismic intensity of 1 to 0.8-2.5 gal and an intensity of 2 of 2.5 to 8.0 ga.
1, seismic intensity 3 is 8.0 to 25 gal, seismic intensity 4 is 25 to 80
It is gal. The unit of gal is 1 of the gravitational acceleration G.
/ 1000, which is equal to the weight supported by the damper when 1 G is applied to the vibration isolating table of the present invention, and when the damper supporting capacity is 3 kg, the force for controlling the acceleration of 1 gal is 3 g. That is, in order to suppress an earthquake with a seismic intensity of about 3, it suffices to have an actuator having a force generation capacity of 75 g, and the actuator of the present invention (240 windings) provides sufficient specifications. Moreover, if the control force is increased, the number of windings of the drive coil is increased.
This can be handled by increasing the drive current.

FIG. 10 shows an example of the dynamic characteristics of the vibration isolation table. The horizontal axis shows the current flowing in the coil, and the vertical axis shows the vertical force generated by the actuator of the vibration isolation table.By increasing the current and the magnetic flux between the permanent magnets, the repulsive force increases. I know that

Further, FIG. 11 shows the frequency response when a constant alternating current is applied to the coil. In the frequency response, it can be seen that a force proportional to the current is generated at each frequency, and it has an ability as a vibration isolation table that can generate a stable force over a wide frequency range.

[0034]

As is apparent from the above description, according to the present invention, the method of levitating an object by utilizing the repulsive force of a permanent magnet is the same as the conventional method, but the instability phenomenon in the lateral deviation direction is caused by the lateral movement of the spring. It is possible to obtain a damper, an actuator, and an anti-vibration table that are stabilized in a passive manner by utilizing rigidity. The spring used at this time only needs to have a spring constant necessary for stabilization in the lateral deviation direction, and a spring force is added to the force for levitating the object, but the repulsive force of the permanent magnet is mainly used. In this way, the damper, actuator, and vibration isolator of the present invention are characterized by being useful as a vibration isolator and having a degree of freedom because both the degree of freedom in the rebound direction and the degree of freedom in the lateral shift direction can be secured.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a damper configuration.

FIG. 2 is an explanatory diagram of a configuration of an actuator.

FIG. 3 is an explanatory diagram of a configuration of a vibration isolation table.

FIG. 4 is a graph showing the relationship between the drive current of the actuator and the vertical direction exciting force.

FIG. 5 is a graph showing the relationship between the frequency of the actuator and the vertical excitation force.

FIG. 6 is a graph showing the relationship between the drive current of the actuator and the horizontal exciting force.

FIG. 7 is a graph showing the relationship between the frequency of the actuator and the horizontal exciting force.

FIG. 8 is an explanatory diagram of the configuration of the vibration isolation table used in the experiment.

FIG. 9 is a graph showing the relationship between frequency and vibration transmissibility.

FIG. 10 is a graph showing the relationship between drive current and vertical direction excitation force in the actuator.

FIG. 11 is a graph showing the relationship between the frequency and vertical excitation force in the actuator.

FIG. 12 is an explanatory diagram of a conventional damper configuration.

[Explanation of symbols]

 1 Damper 2 Spring 3 Actuator 4 Electromagnet 5 Electromagnet 6 Electromagnet 7 Coil 8 Iron core 9 Coil 10 Vibration isolation table 101 Fixed body 102 Movable table 103 Magnetic damper 103a Suction type magnetic damper 103b Repulsion type magnetic damper 104a Fixed side magnet 104b Table side magnet

Claims (4)

[Claims] 1. A repulsion-type magnetic damper, characterized in that the relative positions of a pair of repulsive permanent magnets are restrained by springs. 2. A repulsive-type magnetic actuator, comprising: an electromagnet capable of generating a magnetic field that acts on a magnetic field of the pair of permanent magnets by restraining relative positions of the pair of repulsive permanent magnets with a spring. 3. The repulsive magnetic actuator according to claim 2, wherein the electromagnet is formed by winding a coil around the permanent magnet. 4. A magnetic field acting on a magnetic field of the pair of permanent magnets, wherein a fixed body and a table are connected by a repulsion type magnetic actuator, and the repulsion type magnetic actuator restrains a relative position of a pair of repulsive permanent magnets by a spring. A repulsion-type magnetic vibration isolation table having an electromagnet capable of generating a magnetic field.