JP4157393B2 - Vibration isolator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an anti-vibration device, and more particularly to an anti-vibration device for insulating a processing table of various devices from disturbances in the fields of precision processing, measurement, and the like.
[0002]
[Prior art]
At present, semiconductor device manufacturing systems and ultra-small area measurement systems are rapidly becoming highly accurate and high-performance. In these systems, the importance of vibration isolation and vibration isolation devices to remove disturbances such as vibrations. Is increasing. Such vibration disturbances to be removed by the vibration isolator can be broadly divided into ground disturbances caused by vibrations from the installation floor and linear motion disturbances input to the vibration isolation member of the apparatus. In the former case, a low-rigidity mechanism is suitable, and for the latter a high-rigidity mechanism is suitable.
[0003]
As a conventional vibration isolator, there is a passive vibration isolator that insulates and isolates ground disturbance, but this reduces the spring constant k to reduce the spring stiffness in order to reduce the vibration transmissibility from the floor. Then, it becomes weak against disturbances on the spring such as a change in mass on the vibration isolation table and a change in load acting on the vibration isolation table. Therefore, it is necessary to increase the spring rigidity to some extent against disturbance on the spring. As described above, the vibration isolator is required to have a characteristic for achieving both a low-rigidity mechanism for absorbing ground disturbance and a high-rigidity mechanism for maintaining position and posture. When a spring having a normal positive spring constant is coupled in series, the spring constant formed by the coupling becomes smaller than the spring constant before the coupling. Therefore, it is extremely difficult to secure high rigidity against disturbances on the spring such as mass change and vibration with these conventional vibration isolation devices. Therefore, an active vibration isolation device is proposed. Has been.
[0004]
Some of the above-described vibration isolation devices use a magnetic levitation mechanism that uses a repulsive force between permanent magnets. This can be used as a spring element in place of the air spring often used in ordinary vibration isolation devices. Recently, the performance of permanent magnet materials has been remarkably improved, and a considerably large supporting force can be obtained even with a small magnet. In this magnetic levitation mechanism, various methods are possible depending on the combination of materials used on the floating side and the support side. Of these, the main use for vibration isolation devices is
(1) A system that uses the repulsive force between permanent magnets
(2) A system that uses an attractive force acting between a normal conductive magnet and a ferromagnetic material
Etc.
[0005]
FIG. 9 is a diagram showing a state in which springs are coupled in series. When two springs having spring constants k1 and k2 are connected in series to form one spring, the spring constant kc is obtained by the following equation (1).
kc = k1 · k2 / k1 + k2 Equation (1)
Here, if a spring with a negative spring constant is realized,
k1 = −k2 Formula (2)
If you satisfy the relationship
| Kc | = ∞ Formula (3)
That is, theoretically infinite rigidity can be obtained.
[0006]
When the above relationship is used, there is a possibility that a support mechanism having high rigidity against linear motion disturbance can be realized while maintaining vibration isolation characteristics against ground motion disturbance. Specifically, the vibration insulation characteristics are ensured by lowering the rigidity of each, and the rigidity against the direct acting disturbance is made infinite by matching the magnitudes of the two. A support mechanism having a negative spring characteristic can be realized by using a zero power magnetic levitation mechanism.
[0007]
The above-described zero power magnetic levitation control is a suction type magnetic levitation system using a composite magnet that combines an electromagnet and a permanent magnet. The weight of the levitation object is supported only by the permanent magnet, and the control current of the electromagnet is steadily adjusted. Is a control method that keeps zero.
FIG. 10 is a diagram for explaining the characteristics of the zero-power magnetic levitation mechanism. 10A and 10B, 31 is an object of mass m, 32 is a load, 33 is a spring, 34 is an electromagnet, and 35 is a permanent magnet. As shown in FIG. 10A, in the normal spring system, if the gravity acting on the object 31 having the mass m supported by the spring 33 increases by Δmg, that is, the mass Δm of the load 32, the spring 33 extends. So the object changes in the same direction as gravity. On the other hand, in the zero power magnetic levitation mechanism, as shown in FIG. 10B, when a constant external force acts on the levitating object (object 31 + load 32) in the direction away from the electromagnet 34, the electromagnet 34 is steadily applied. And the gap between the flying object is reduced. In other words, it behaves as if it has “negative” stiffness.
[0008]
As a vibration isolator using the above-mentioned zero-power magnetic levitation mechanism, high rigidity against linear motion disturbance is ensured without impairing vibration insulation performance against ground motion disturbance, enabling high-performance vibration isolation functions and precision machining, etc. Has been disclosed. (For example, see Patent Document 1 and Non-Patent Document 1)
[0009]
FIG. 11 is a diagram showing a basic configuration example of a vibration isolator using a conventional zero power magnetic levitation mechanism. In the figure, 41 is an intermediate stand, 42 is a vibration isolation table, 43 is a permanent magnet, 44 is An electromagnet, 45 is a spring having a spring constant k, 46 is a floor, and 47 is a damping element. An electromagnet 44 for magnetic levitation is fixed to the intermediate base 41 supported by the positive spring 45 and the damping element 47 having the spring coefficient k. In the vibration isolation table 42, a permanent magnet 43 for levitation of zero power and a ferromagnetic material are attached to a portion facing the electromagnet 44. The behavior of the vibration isolator against the direct acting disturbance acting on the vibration isolation table 42 is as follows.
Let the attractive force / displacement coefficient of the electromagnet 44 be ks (this is the magnitude of the negative stiffness). When a certain downward force is applied to the vibration isolation table 42, the gap between the electromagnet 44 and the vibration isolation table 42 becomes narrow due to the action of zero power control. In other words, the vibration isolation table 42 tends to be displaced upward. However, when the gap is narrowed and the attractive force of the magnet is increased, the spring 45 is compressed by this force, so that the intermediate table 41 is displaced downward. If these two displacements are set so as to cancel each other out, that is, if k = ks is set, as a result, the vibration isolation table 42 is not displaced at all.
[0010]
[Patent Document 1]
JP 2002-81498 A
[Non-Patent Document 1]
Journal of Precision Engineering VOL. 68, no. 9, 2002 (1180 to 1)
183)
[0011]
[Problems to be solved by the invention]
However, in the above-described zero power magnetic levitation mechanism, since the levitation force is obtained by applying the attraction force of the permanent magnet, the relationship between the levitation gap and the attraction force has nonlinearity. That is, when the mass on the vibration isolation table, that is, the mass of the levitation object changes, the levitation gap changes, and as a result, the rigidity of the zero power magnetic levitation mechanism changes. Since “linear stiffness” is used for “positive rigidity”, the rigidity of the vibration isolator theoretically becomes a finite value as the mass on the vibration isolation table increases / decreases, and the linear motion disturbance removal performance decreases. End up. In other words, the “positive stiffness” spring has linearity, and the “negative stiffness” zero-power magnetic levitation mechanism has non-linearity. The vibration isolation performance will be reduced.
[0012]
The present invention has been made in view of the above circumstances, and uses a non-linear element for the “negative stiffness” and also uses a non-linear element for the “positive stiffness”. Providing an anti-vibration device capable of exhibiting a stable removal performance by securing high rigidity against an arbitrary linear motion disturbance while constituting a component and ensuring vibration isolation characteristics against ground disturbance More specifically, when an element having a positive stiffness k1 and an element having a negative stiffness k2 are connected in series, k1 = −k2 is established for an arbitrary load. The purpose of this is to make the rigidity of the vibration isolator almost infinite by introducing an element with positive rigidity having non-linearity.
[0013]
[Means for Solving the Problems]
The invention of claim 1 A pair of An intermediate support that is levitated and supported from the bottom by the repulsive force of the permanent magnet, an electromagnet or a permanent magnet is provided below the intermediate support, and a permanent magnet or an electromagnet is provided at a position facing the electromagnet or the permanent magnet. A pair of permanent magnets that support the intermediate support body with respect to the bottom surface, and a vibration isolation table connected to the floating intermediate member and supported on an upper side of the intermediate support body. The floating intermediate member having a predetermined positive spring constant and supporting the vibration isolation table with respect to the intermediate support has a predetermined negative spring constant, and the pair of permanent magnets, the floating intermediate member, Has a non-linearity such that the absolute values of the positive and negative spring constants are equal for an arbitrary load applied on the vibration isolation table. It is characterized by that.
[0014]
The invention of claim 2 In the invention according to claim 1, the floating intermediate member is fixed to the intermediate support by the attractive force of a permanent magnet provided on the vibration isolation table in a stationary state where the vibration isolation table is not loaded. The coil current of the electromagnet provided on the intermediate support is kept at zero, and in a load state loaded on the vibration isolation table, a current corresponding to an external force caused by the load is passed through the electromagnet. Is controlled so that the generated suction force is balanced with the external force. It is characterized by that.
[0015]
The invention of claim 3 In the invention according to claim 1, the floating intermediate member is placed against the vibration isolation table by a suction force of a permanent magnet provided on the intermediate support in the stationary state where no load is applied to the vibration isolation table. The coil current of the electromagnet provided on the vibration isolation table is kept at zero, and in a load state loaded on the vibration isolation table, a current corresponding to the external force due to the load is passed through the electromagnet Is controlled so that the generated suction force is balanced with the external force. It is characterized by that.
[0016]
A fourth aspect of the present invention provides the intermediate support according to any one of the first to third aspects. Alternatively, the vibration isolation table includes a composite magnet in which an electromagnet and a permanent magnet are combined, and the vibration isolation table or the intermediate support is a ferromagnetic body at a position facing the composite magnet. It is characterized by having.
[0017]
The invention of claim 5 A plurality of intermediate supports that are levitated and supported with respect to the bottom by the repulsive force of a pair of permanent magnets, and an electromagnet or permanent magnet is provided below each of the intermediate supports, and the permanent magnet is positioned opposite the electromagnet or permanent magnet. Or a plurality of floating intermediate members provided with electromagnets, and a vibration isolation table connected to the floating intermediate members and supported on the upper side of the intermediate support members, and the intermediate support members with respect to the bottom surface Each of the pair of permanent magnets that are supported has a predetermined positive spring constant, and each of the floating intermediate members that support the vibration isolation table with respect to each of the intermediate supports has a predetermined negative spring constant. The pair of permanent magnets and the floating intermediate members have nonlinearity such that the absolute values of the positive and negative spring constants are equal to an arbitrary load applied on the vibration isolation table. It is characterized by that.
[0018]
The invention of claim 6 A levitation in which an upright L-shaped support is provided with respect to the bottom surface and an electromagnet or permanent magnet is provided on the surface of the support facing the bottom surface, and a permanent magnet or electromagnet is provided at a position facing the electromagnet or permanent magnet. An intermediate member, an intermediate support coupled to the floating intermediate member, and a vibration isolation table that is levitated and supported on the upper side of the column by a repulsive force of a pair of permanent magnets provided between the intermediate support and the intermediate support And the pair of permanent magnets that support the vibration isolation table with respect to the intermediate support have a predetermined positive spring constant, and the floating intermediate member that supports the intermediate support with respect to the support column Has a predetermined negative spring constant, and the pair of permanent magnets and the floating intermediate member have the same absolute value of the positive and negative spring constants for any load applied on the vibration isolation table. Have non-linearity like It is characterized by that.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing a basic configuration example of a vibration isolator having a zero power magnetic levitation mechanism according to an embodiment of the present invention. In the figure, 1 is an intermediate stand (intermediate support), and 2 is a vibration isolator. Table, 3 is permanent magnet, 4 is electromagnet, 5 ₁ And 5 ₂ Is a permanent magnet and 6 is a floor. In the vibration isolator of the present embodiment, A is a support mechanism, and the support mechanism A is a permanent magnet 5 installed on the floor 6. ₂ And a permanent magnet 5 provided at the bottom of the intermediate stand 1 ₁ The magnetic spring has a positive spring characteristic, that is, a predetermined positive spring constant k1 (N / m) with respect to the floor 6 and a non-linear characteristic. B is a magnetic levitation mechanism (a levitation intermediate member) having the above-described zero power characteristics. The magnetic levitation mechanism B includes a permanent magnet 3 provided on the vibration isolation table 2 and an electromagnet 4 provided below the intermediate stand 1. And a negative spring characteristic, that is, a predetermined negative spring constant k2 (N / m) with respect to the intermediate platform 1, and a non-linear characteristic. By connecting the support mechanism A and the magnetic levitation mechanism B in series, the support mechanism A and the magnetic levitation mechanism B have substantially infinite rigidity against the linear motion disturbance generated on the vibration isolator, and also insulate the vibration from the floor 6. be able to. That is, the vibration transmitted from the floor 6 to the intermediate platform 1 is insulated by the support mechanism A, and the vibration transmitted from the intermediate platform 1 to the vibration isolation table 2 is insulated by the magnetic levitation mechanism B.
[0026]
In FIG. 1, if the slopes of the characteristic curves at the same load (indicating the relationship between the gap between magnets and the load) match, the absolute values of the rigidity of both the support mechanism A and the magnetic levitation mechanism B are equal. By combining both the support mechanism A and the magnetic levitation mechanism B having similar nonlinear characteristics, that is, two nonlinear elements, one linear element can be configured. As a result, each displacement due to the load applied to the vibration isolation table 2 is eliminated, and the displacement of the vibration isolation table 2 is eliminated. That is, this vibration isolator can stably have an almost infinite rigidity.
[0027]
In order to increase the attractive force by the permanent magnet, a ferromagnetic material (not shown) may be disposed on the vibration isolation table 2 side in combination with the permanent magnet 3, and the permanent magnet 3 may be disposed on the electromagnet 4. Alternatively, a composite magnet may be embedded in the iron core and only the ferromagnetic material may be disposed on the vibration isolation table 2 side. Further, the arrangement of the electromagnet 4 and the permanent magnet 3 is reversed, that is, the electromagnet 4 is arranged on the vibration isolation table 2 side and the permanent magnet 3 is arranged on the intermediate stand 1 side, and the attractive force of the electromagnet 4 acts on the vibration isolation table 2. You may make it increase / decrease according to increase / decrease in a load. Also in this case, the ferromagnetic material may be disposed on the intermediate stand 1 side in combination with the permanent magnet 3, or the permanent magnet 3 is embedded in the iron core of the electromagnet 4 to form a composite magnet, and on the intermediate stand 1 side. May be provided with only a ferromagnetic material.
[0028]
Here, the magnetic levitation mechanism B having zero power characteristics will be described.
Zero power control is an attraction type magnetic levitation system configured by combining an electromagnet and a permanent magnet. As shown in FIG. 1, the mass of the vibration isolation table 2 is supported only by the attraction force of the permanent magnet 3, This is a control method in which the coil current of the electromagnet 4 on the intermediate platform 1 side is constantly kept at zero. The magnetic levitation mechanism B has this zero power characteristic. The control system for performing the zero power control will be described later with reference to FIG. 3, and description thereof will be omitted here.
[0029]
Here, in addition to the above-described magnetic spring having the predetermined positive spring constant, for example, a nonlinear spring including an air spring or an active controlled actuator may be used as the nonlinear element of the support mechanism A. . In addition to the above-described magnetic levitation mechanism having a predetermined negative spring constant, for example, an actively controlled actuator may be used as the nonlinear element of the magnetic levitation mechanism B. As the actively controlled actuator having the predetermined positive spring constant or the predetermined negative spring constant, for example, a voice coil motor, a linear motor, a pneumatic actuator, a hydraulic actuator, a piezoelectric actuator, a magnetostrictive actuator, or the like is preferably used. Can do. Since the vibration isolator of the present invention can be configured by appropriately combining the various actuators described above, nonlinear springs, and the like according to the application, the application range is wide.
[0030]
FIG. 2 is a diagram illustrating an example of state transition when a load is applied to the vibration isolation table 2 of the vibration isolation device. As shown in FIG. 2, the attraction force of the electromagnet 4 provided on the intermediate platform 1 is not shown so as to increase or decrease in accordance with the increase or decrease of the mass Δm due to the load applied to the vibration isolation table 2 provided with the permanent magnet 3. Control appropriately by the control system. FIG. 2A shows the stationary state of the vibration isolation device, and FIG. 2B shows the state when a load of mass Δm is applied to the vibration isolation table 2.
[0031]
Here, the attractive force / displacement coefficient of the electromagnet 4 is set to k2 (N / m) (this is the magnitude of negative rigidity), and the permanent magnet 5 ₁ And 5 ₂ Let the spring constant of the magnetic spring repelled by k1 (N / m). When a certain downward force is applied to the vibration isolation table 2, the gap between the electromagnet 4 and the vibration isolation table 2 becomes narrow due to the action of zero power control. In other words, the vibration isolation table 2 tends to be displaced upward. However, when the gap becomes narrower and the attractive force of the magnet increases, this force causes the magnetic spring (permanent magnet 5). ₁ And 5 ₂ ) Is compressed, the intermediate platform 1 is displaced downward. If these two displacements are set so as to cancel each other out, that is, if k1 (N / m) = k2 (N / m) is set, as a result, the vibration isolation table 2 is It will not be displaced at all.
[0032]
FIG. 3 is a diagram for explaining the features of the zero power magnetic levitation control system according to the present invention. In the figure, 11 is a support fixing portion, 12 is a vibration isolation table, 13 is a permanent magnet, and 14 is an electromagnet. As shown in FIG. 3A, the vibration isolation table 12 is stopped at a stationary position in a state where the forces are balanced, but when a load of Δm is applied as shown in FIG. When a constant downward external force is applied to the table 12, an attraction force is generated to pull up the vibration isolation table 12 by passing an electric current through the coil of the electromagnet 14, so that the attraction force by the permanent magnet 13 and the downward force are balanced. As shown in FIG. 3C, the current flowing through the coil of the electromagnet 14 becomes zero at a position where the gap is narrowed, and a stationary state is obtained.
[0033]
The control system 20 for controlling the operation as described above detects the position of the vibration isolation table 12 with respect to the support fixing portion 11 (corresponding to the intermediate table 1 shown in FIG. 1), as shown in FIG. A displacement sensor 21, and a control circuit 22 for generating a control signal for floatingly holding the vibration isolation table 12 while constantly holding the coil current of the electromagnet 14 based on an output signal from the displacement sensor 21; And a power amplifier 23 for supplying a predetermined current to the coil of the electromagnet 14 in accordance with the output from the control circuit 22. The zero power control can be realized based on these configurations.
[0034]
FIG. 4 is a diagram showing an example of a characteristic curve in the vibration isolation device of the present invention. 4A and 4B, the vertical axis represents the gap between the permanent magnets (unit: mm), and the horizontal axis represents the load (unit: N). As shown in FIG. 4A, the magnetic spring constituting the support mechanism A exhibits nonlinear characteristics. When a spring having a linear characteristic as shown in the prior art is used for the support mechanism A, the magnetic levitation mechanism B exhibits a non-linear characteristic. Disturbance removal performance is degraded. Further, as shown in FIG. 4B, one of the magnetic levitation mechanisms B similarly exhibits nonlinear characteristics. In this way, if the slopes of the characteristic curves at the same load match in both characteristics, the absolute value of the stiffness is equal. By combining two nonlinear elements having similar characteristics, one linear element can be obtained. It becomes possible to construct.
[0035]
FIG. 5 is a diagram showing an example of a characteristic curve indicated by the vibration isolation table according to the present invention. Load applied on the vibration isolation table by the support mechanism A (magnetic spring) having a positive spring constant k1 (N / m) and the zero power magnetic levitation mechanism B having a negative spring constant k2 (N / m) The respective displacements due to are canceled, and the displacement of the vibration isolation table is not seen.
[0036]
FIG. 6 is a diagram showing an example of an experimental result based on the configuration of the vibration isolation device of the present invention. In the figure, ■ is a characteristic curve representing displacement of the vibration isolation table, ● is a characteristic curve representing displacement of the magnetic spring, ▲ is a characteristic curve representing the displacement of the zero power magnetic levitation mechanism. Thus, it can be seen that the displacement of the vibration isolation table can no longer be seen by giving the same non-linear characteristics to the magnetic spring and the zero power magnetic levitation mechanism. In this case, if a spring having linear characteristics is used instead of the magnetic spring, the zero power magnetic levitation mechanism has a nonlinear characteristic. Therefore, the linear motion disturbance removal performance is reduced. According to the present invention, substantially the same infinite rigidity can be stably maintained by giving both the same non-linear characteristics.
[0037]
Here, the displacement control in the vibration isolator shown in FIG. 1 will be described based on the above-described equation (1). When the load is applied to the vibration isolation table 2 and a constant downward external force F0 is applied, zero power is applied. As a result of the control, the distance between the electromagnet 4 provided on the intermediate platform 1 and the vibration isolation table 2 is displaced (shortened) by F0 / k2. Here, k2 is a negative spring constant realized by zero power control. Therefore, if the vibration isolation device is designed so as to satisfy the relationship of k2 = k1, the vibration isolation table 2 will not be displaced at all. That is, according to the above equation (1), kc = k1 · k2 / (k1 + k2), if a negative spring constant is introduced into the relation of k1 = −k2, a spring constant that | kc | = ∞ can be obtained. . In this vibration isolator, a spring having an infinite spring constant can be obtained by combining a positive spring and a negative spring having the same spring constant (absolute value). This means that the compliance is zero.
[0038]
Here, another embodiment of the vibration isolator of the present invention shown in FIG. 1 will be described.
FIG. 7 is a diagram showing a basic configuration example of a vibration isolator having a zero power magnetic levitation mechanism according to another embodiment of the present invention, in which 1 is an intermediate stand (intermediate support), 2 ₁ Is a vibration isolation table, 3 is a permanent magnet, 4 is an electromagnet, 5 ₁ And 5 ₂ Is a permanent magnet, 6 is a floor, 7 is a movable stage, and 8 is a moving load. In the vibration isolator of the present embodiment, the difference from the embodiment shown in FIG. 1 is that a vibration isolating table 2 includes a plurality of support mechanisms and a magnetic levitation mechanism. ₁ This is the point that supports and isolates the vibration.
[0039]
Here, the permanent magnet 5 installed on the floor 6 ₂ And a permanent magnet 5 provided on the bottom surface of the intermediate stand 1 ₁ It is assumed that the magnetic spring having the repulsive force has a positive spring characteristic, that is, a predetermined positive spring constant k1 (N / m) with respect to the floor 6 and a non-linear characteristic. Moreover, the vibration isolation table 2 ₁ The magnetic levitation mechanism comprising the permanent magnet 3 provided on the base plate 1 and the electromagnet 4 provided on the lower side of the intermediate stand 1 has a negative spring characteristic, that is, a predetermined negative spring constant k2 (N / m) with respect to the intermediate stand 1. And non-linear characteristics. By connecting the magnetic spring and the magnetic levitation mechanism in series, it has substantially infinite rigidity against the linear motion disturbance generated on the vibration isolator, and can insulate the vibration from the floor 6. it can. In the magnetic levitation mechanism and magnetic spring of the present embodiment, one vibration isolation table 2 ₁ On the other hand, the magnetic spring and the magnetic levitation mechanism are arranged at a plurality of locations so that the relationship of k1 (N / m) = k2 (N / m) is satisfied at each location.
[0040]
The vibration isolation table 2 is based on the above characteristics. ₁ When the movable stage 7 is installed on the top, the vibration isolation table 2 no matter where the moving load 8 is located. ₁ Does not displace and keeps its posture horizontal.
[0041]
FIG. 8 is a diagram showing a basic configuration example of a vibration isolation device having a zero power magnetic levitation mechanism according to another embodiment of the present invention, in which 1 is an intermediate stand (intermediate support), 2 ₂ Is a vibration isolation table, 3 is a permanent magnet, 4 is an electromagnet, 5 ₁ And 5 ₂ Is a permanent magnet, 6 is a floor, and 9 is a support. The vibration isolator of this embodiment is different from the embodiment shown in FIG. 1 in that a magnetic levitation mechanism is provided between the support column 9 and the intermediate platform 1. Here, the permanent magnet 5 ₁ And 5 ₂ It is assumed that the magnetic spring made of has a positive spring characteristic, that is, a predetermined positive spring constant k1 (N / m) with respect to the intermediate stand 1 and a non-linear characteristic. Further, the magnetic levitation mechanism comprising the permanent magnet 3 provided on the intermediate platform 1 and the electromagnet 4 provided on the column 9 has a negative spring characteristic, that is, a predetermined negative spring constant k2 (N / m with respect to the column 9). ) And nonlinear characteristics. By connecting the magnetic spring and the magnetic levitation mechanism in series, it has substantially infinite rigidity against the linear motion disturbance generated on the vibration isolator, and can insulate the vibration from the floor 6. it can. Also in this embodiment, the relationship of k1 (N / m) = k2 (N / m) is satisfied as in the case of the vibration isolation device illustrated in FIG.
[0042]
【The invention's effect】
According to the present invention, by using a non-linear element for “negative stiffness” and using an element having non-linearity for “positive stiffness” as well, one linear element is formed, and vibration isolation characteristics against ground disturbance are reduced. It is possible to provide a vibration isolation device that can secure a high rigidity against an arbitrary linear motion disturbance and can exhibit a stable removal performance while ensuring.
Further, when an element having a positive stiffness k1 and an element having a negative stiffness k2 are connected in series, a positive stiffness having nonlinearity that establishes k1 = −k2 for an arbitrary load. By introducing an element having a, the rigidity of the vibration isolator can be made almost infinite.
[Brief description of the drawings]
FIG. 1 is a diagram showing a basic configuration example of a vibration isolation device having a zero power magnetic levitation mechanism according to an embodiment of the present invention.
FIG. 2 is a diagram showing an example of state transition when a load is applied to a vibration isolation table of the vibration isolation device.
FIG. 3 is a diagram for explaining the characteristics of a zero power magnetic levitation control system according to the present invention.
FIG. 4 is a diagram showing an example of a characteristic curve in the vibration isolation device of the present invention.
FIG. 5 is a diagram showing an example of a characteristic curve indicated by a vibration isolation table according to the present invention.
FIG. 6 is a diagram showing an example of an experimental result based on the configuration of the vibration isolation device of the present invention.
FIG. 7 is a diagram showing a basic configuration example of a vibration isolation device having a zero power magnetic levitation mechanism according to another embodiment of the present invention.
FIG. 8 is a diagram showing a basic configuration example of a vibration isolation device having a zero power magnetic levitation mechanism according to another embodiment of the present invention.
FIG. 9 is a view showing a state in which springs are coupled in series.
FIG. 10 is a diagram for explaining the characteristics of a zero-power magnetic levitation mechanism.
FIG. 11 is a diagram showing a basic configuration example of a vibration isolator using a conventional zero power magnetic levitation mechanism.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,41 ... Intermediate stand (intermediate support body), 2, 21, 22, 12, 42 ... Vibration isolation table, 3, 13, 35, 43 ... Permanent magnet, 4, 14, 34, 44 ... Electromagnet, 5 ₁ , 5 ₂ DESCRIPTION OF SYMBOLS Permanent magnet, 6,46 ... Floor, 7 ... Movable stage, 8 ... Moving load, 9 ... Strut, 11 ... Support fixing part, 20 ... Control system, 21 ... Displacement sensor, 22 ... Control circuit, 23 ... Power amplifier, 31 ... object, 32 ... load, 33, 45 ... spring, 47 ... damping element.

Claims (6)

An intermediate support that is levitated and supported by the repulsive force of a pair of permanent magnets, an electromagnet or a permanent magnet is provided below the intermediate support, and a permanent magnet or an electromagnet is provided at a position facing the electromagnet or the permanent magnet. A provided floating intermediate member, and a vibration isolation table connected to the floating intermediate member and supported on the upper side of the intermediate support,
The pair of permanent magnets that support the intermediate support with respect to the bottom surface have a predetermined positive spring constant, and the floating intermediate member that supports the vibration isolation table with respect to the intermediate support has a predetermined negative Having a spring constant of
The pair of permanent magnets and the floating intermediate member have nonlinearity such that absolute values of the positive and negative spring constants are equal to an arbitrary load applied on the vibration isolation table. Vibration isolator. 2. The vibration isolation device according to claim 1, wherein the floating intermediate member is configured such that, in a stationary state where no load is applied to the vibration isolation table, the intermediate vibration is generated by a suction force of a permanent magnet provided on the vibration isolation table. While supporting the support, the coil current of the electromagnet provided on the intermediate support is kept at zero, and in the load state loaded on the vibration isolation table, a current corresponding to the external force due to the load is supplied to the electromagnet. The vibration isolator is controlled so as to cause the electromagnet to generate an attractive force and to balance the generated attractive force with the external force . 2. The vibration isolation device according to claim 1, wherein the floating intermediate member is moved by the attraction force of a permanent magnet provided on the intermediate support in a stationary state where no load is applied to the vibration isolation table. While supporting the vibration table, the coil current of the electromagnet provided on the vibration isolation table is held at zero, and in the load state loaded on the vibration isolation table, a current corresponding to the external force due to the load is supplied to the electromagnet. The vibration isolator is controlled so as to cause the electromagnet to generate an attractive force and to balance the generated attractive force with the external force . 4. The vibration isolation device according to claim 1, wherein the intermediate support or the vibration isolation table includes a composite magnet in which an electromagnet and a permanent magnet are combined, and the vibration isolation table or the intermediate support is provided. The vibration isolator according to claim 1, wherein the body has a ferromagnetic body at a position facing the composite magnet . A plurality of intermediate supports that are levitated and supported with respect to the bottom surface by the repulsive force of a pair of permanent magnets, and an electromagnet or permanent magnet provided at the lower part of each intermediate support, and a permanent magnet at a position facing the electromagnet or permanent magnet Or a plurality of floating intermediate members provided with electromagnets, and a vibration isolation table connected to each floating intermediate member and supported on the upper side of each intermediate support,
The pair of permanent magnets that support the intermediate supports with respect to the bottom surface have a predetermined positive spring constant, and the floating intermediate members that support the vibration isolation table with respect to the intermediate supports. Has a predetermined negative spring constant,
Each of the pair of permanent magnets and each of the floating intermediate members has nonlinearity such that the absolute values of the positive and negative spring constants are equal to an arbitrary load applied on the vibration isolation table. The vibration isolator. A levitation in which an upright L-shaped support is erected with respect to the bottom surface, and an electromagnet or permanent magnet is provided on the surface of the support facing the bottom surface, and a permanent magnet or electromagnet is provided at a position facing the electromagnet or permanent magnet. An intermediate member, an intermediate support coupled to the floating intermediate member, and a vibration isolation table that is levitated and supported on the upper side of the column by a repulsive force of a pair of permanent magnets provided between the intermediate support and the intermediate support Have
The pair of permanent magnets that support the vibration isolation table with respect to the intermediate support have a predetermined positive spring constant, and the floating intermediate member that supports the intermediate support with respect to the support column has a predetermined negative Having a spring constant of
The pair of permanent magnets and the floating intermediate member have nonlinearity such that absolute values of the positive and negative spring constants are equal to an arbitrary load applied on the vibration isolation table. Vibration isolator.

Images