JP7493893B2 - Magnetic Damper - Google Patents

Description

The present invention relates to a magnetic damper.

Conventionally, there has been known a seismically isolated building in which a laminated rubber layer made of multiple rubber plates and steel plates is provided on a foundation (substructure), along with energy absorbing means such as lead plugs, and the building (superstructure) is supported on top of these in a seismic isolation manner.
In such seismically isolated buildings, one possible method of controlling excessive displacement of the building (superstructure) in the event of an earthquake motion that exceeds the earthquake motion assumed in normal design (earthquake motion that exceeds the assumptions made in the design) is to further install a damper extending horizontally between the lower structure and the superstructure.
However, if this method is used to respond to earthquake motions that exceed the design assumptions and are considered to have a very low occurrence frequency and probability, the damper will also exert its damping force for earthquakes with a higher occurrence frequency and probability, reducing the seismic isolation performance and causing unnecessary seismic forces to be generated in the superstructure.

One possible solution is to install a damper that has a mechanism for switching the damping force depending on the magnitude and velocity of the displacement occurring in the seismic isolation layer (see, for example, Patent Document 1).
The hydraulic shock absorber (damper) of Patent Document 1 is provided with a passage through which oil passes and a variable throttle mechanism, and the damping force changes according to the displacement of the piston.

Japanese Patent Application Laid-Open No. 1-269741

However, dampers with a mechanism for switching the damping force depending on the magnitude and speed of the displacement occurring in the seismic isolation layer, as in Patent Document 1, have a complex configuration, so it is desirable to use a damper with a simple configuration that exerts a damping force in response to earthquake motion that exceeds the assumptions in the design.

The present invention was developed in consideration of the above circumstances, and aims to provide a magnetic damper with a simple configuration that suppresses the deterioration of seismic isolation performance against earthquake motions assumed in normal designs, and also exerts a damping force against earthquake motions that exceed the assumptions in the design.

In order to achieve the above-mentioned object, one embodiment of the present invention is a magnetic damper comprising a cylinder, and a rod arranged on the axis of the cylinder so as to be capable of reciprocating motion and protruding from both ends of the cylinder, wherein the magnetic damper comprises a first magnet arranged on the inner surface of both ends of the cylinder in the axial direction, and a second magnet arranged on the outer surface of the axial center of the rod, the radial inner side of the first magnet and the radial outer side of the second magnet having different magnetic poles, and the rod is arranged in an initial position so that the second magnet faces the axial center of the cylinder.
In addition, one embodiment of the present invention is characterized in that the first magnet is provided around the entire inner circumferential surface of both ends of the cylinder, and the second magnet is provided around the entire outer circumferential surface of the central portion.
In addition, one embodiment of the present invention is characterized in that the first magnet and the second magnet are permanent magnets.
In one embodiment of the present invention, at least one of the first magnet and the second magnet is an electromagnet, and the magnet further includes a control unit that energizes the electromagnet.
Moreover, one embodiment of the present invention is a magnetic damper comprising a cylinder, and a rod arranged on the axis of the cylinder so as to be capable of reciprocating motion and protruding from both ends of the cylinder, wherein the magnetic damper comprises a magnet arranged on one of the inner surfaces of both ends of the cylinder in the axial direction and the outer surface of the central part of the rod in the axial direction, and a conductor arranged on the other of the inner surfaces of both ends of the cylinder in the axial direction and the outer surface of the central part of the rod in the axial direction, and wherein the rod is characterized in that, in an initial position, the magnet or the conductor arranged in the central part of the rod is positioned opposite the central part of the axial direction of the cylinder.
In addition, one embodiment of the present invention is characterized in that the magnet or the conductor arranged in the cylinder is provided around the entire inner surface of both ends of the cylinder, and the magnet or the conductor arranged in the rod is provided around the entire outer surface of the center of the rod.
In addition, one embodiment of the present invention is characterized in that the magnet is a permanent magnet.
In addition, one embodiment of the present invention is characterized in that the magnet is an electromagnet, and the device further includes a control unit that applies electricity to the electromagnet.
In addition, one embodiment of the present invention is characterized in that the magnetic damper is installed in a seismically isolated building constituting an upper structure supported for seismic isolation on a lower structure, and mounting members are attached to the end of the rod protruding from one end in the axial direction of the cylinder and the other end in the axial direction of the cylinder, one of the mounting members being connected to the upper structure and the other mounting member being connected to the lower structure.
In addition, one embodiment of the present invention is characterized in that the mounting member is connected to the lower structure and the upper structure in a state in which it can swing around an axis extending in a vertical direction perpendicular to the axial direction of the cylinder.
In addition, one embodiment of the present invention is characterized in that the control unit passes current through the electromagnet when the seismic isolated building vibrates.
In addition, one embodiment of the present invention is characterized in that the rod has a male threaded portion and is arranged to be able to move back and forth and rotate on the axis of the cylinder, and a female threaded member having a female threaded portion that can be screwed into the male threaded portion is arranged non-rotatably.
In addition, one embodiment of the present invention is characterized in that the male threaded portion is provided on at least half of the longitudinal direction of the rod, the cylinder has a cylindrical wall that forms the inner surface of the cylinder and a pair of end walls that close both axial ends of the cylinder and through which the rod passes, and the female threaded member is attached to the end walls where half of the rod is located on the outer surface of the cylinder.

According to one embodiment of the present invention, in the magnetic damper, a first magnet is arranged on the inner circumferential surface of both axial ends of the cylinder, a second magnet is arranged on the outer circumferential surface of the axial center of the rod, and the rod is provided at a position where the second magnet faces the axial center of the cylinder in the initial position. When the relative displacement between the cylinder and the rod reaches or exceeds a predetermined value, the first magnet and the second magnet face each other and an attractive force acts, suppressing the movement of the rod. This simple configuration suppresses the deterioration of seismic isolation performance against earthquake motion assumed in the normal design, and is advantageous in exerting a damping force against earthquake motion that exceeds the assumption in the design.

In addition, if the first magnet is provided around the entire inner circumference of both ends of the cylinder, and the second magnet is provided around the entire outer circumference of the rod, this is advantageous in ensuring that the damping force is exerted only when earthquake motion occurs that exceeds the design assumptions and the relative displacement between the cylinder and the rod exceeds a predetermined value.

In addition, if the first magnet and the second magnet are made of permanent magnets, they generate magnetic force simply by being placed in the magnetic damper, which is advantageous in terms of reducing costs.

Furthermore, if at least one of the first magnet and the second magnet is configured as an electromagnet and further includes a control unit that energizes the electromagnet, the timing at which the magnetic force is generated can be adjusted, which is advantageous in improving convenience.

In addition, according to one embodiment of the present invention, in the magnetic damper, a magnet is arranged on one of the inner circumferential surface of both ends of the cylinder in the axial direction and the outer circumferential surface of the center of the rod in the axial direction, and a conductor is arranged on the other of the inner circumferential surface of both ends of the cylinder in the axial direction and the outer circumferential surface of the center of the rod in the axial direction. In the initial position, the magnet or conductor arranged in the center of the rod is provided in a position facing the center of the cylinder in the axial direction. When the relative displacement between the cylinder and the rod reaches or exceeds a predetermined value, the magnet and the conductor face each other, and the movement of the rod is suppressed by the resistance force generated by the action of the eddy current flowing in the conductor and the magnetic field of the magnet. This simple configuration suppresses the deterioration of seismic isolation performance against earthquake motion assumed in the normal design, and is advantageous in exerting a damping force against earthquake motion that exceeds the assumption in the design.

In addition, if the magnets or conductors arranged on the cylinder are arranged around the entire circumference of the inner surface of both ends of the cylinder, and the magnets or conductors arranged on the rod are arranged around the entire circumference of the outer surface of the center of the rod, this is advantageous in ensuring that damping force is exerted only when seismic motion occurs that exceeds the design assumptions and the relative displacement between the cylinder and the rod exceeds a predetermined value.

In addition, if the magnet is a permanent magnet, it generates magnetic force simply by being placed in the magnetic damper, which is advantageous in terms of reducing costs.

Furthermore, if the magnet is an electromagnet and a control unit that energizes the electromagnet is further provided, the timing at which the magnetic force is generated can be adjusted, which is advantageous in improving convenience.

In addition, if mounting members are attached to the end of the rod protruding from one axial end of the cylinder and to the other axial end of the cylinder, and one of the mounting members is connected to the upper structure and the other is connected to the lower structure, this is advantageous in terms of exerting a damping force when the upper structure is displaced relative to the lower structure due to earthquake motion that exceeds the design assumptions.

In addition, if the mounting members are connected to the lower structure and the upper structure in a state in which they can swing about an axis extending vertically perpendicular to the axial direction of the cylinder, the magnetic damper can be swung horizontally even if the upper structure moves horizontally relative to the lower structure due to seismic motion, which is advantageous in avoiding damage to the magnetic damper.

In addition, if the control unit is configured to energize the electromagnet when the seismic isolation building vibrates, no electricity will be applied when no earthquake is occurring, which is advantageous in reducing costs.

In addition, if the rod has a male threaded portion and is arranged so that it can reciprocate and rotate on the axis of the cylinder, and a female threaded member having a female threaded portion that can be screwed into the male threaded portion is arranged so that it cannot rotate, even if there is a place where the magnetic force of the first magnet and the second magnet is weaker than other places, the rod will move while rotating, which is advantageous in exerting a damping force evenly in the circumferential direction.

In addition, if the male threaded portion is provided on at least half of the longitudinal direction of the rod, and the female threaded member is attached to the end wall on the outer surface of the cylinder where half of the rod is located, this has the effect of allowing the rod to move while rotating with a simple configuration.

1 is a schematic diagram showing a seismically isolated building provided with a magnetic damper according to a first embodiment. 1 is a configuration diagram of a magnetic damper according to a first embodiment; 4 is an explanatory diagram showing a state in which the magnetic damper according to the first embodiment is most compressed; FIG. 5 is an explanatory diagram showing a state in which the magnetic damper according to the first embodiment is fully extended; FIG. FIG. 11 is a configuration diagram of a magnetic damper according to a second embodiment. FIG. 11 is a configuration diagram of a magnetic damper according to a third embodiment. FIG. 13 is a configuration diagram of a magnetic damper according to a fourth embodiment. FIG. 13 is an explanatory diagram showing a state in which the magnetic damper according to the fourth embodiment is most compressed. FIG. 13 is an explanatory diagram showing a state in which the magnetic damper according to the fourth embodiment is fully extended. FIG. 13 is a configuration diagram of a magnetic damper according to a fifth embodiment.

(First embodiment)
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in Figure 1, a seismically isolated building is an upper structure 4 (building) supported in a seismic isolation manner on a lower structure 2 (foundation), and a laminated rubber 6 and a magnetic damper 10A are installed between the lower structure 2 and the upper structure 4.

The laminated rubber 6 is an isolator that supports the upper structure 4 and moves the upper structure 4 horizontally when an earthquake occurs, thereby making it difficult for ground vibrations caused by an earthquake to be transmitted to the upper structure 4.
In the example of FIG. 1, a laminated rubber is used as the isolator, in which multiple rubber plates and steel plates are alternately stacked. However, other isolators using rolling bearings, sliding bearings, etc. may also be used.

The magnetic damper 10A exerts a horizontal damping force against the shaking of the upper structure 4, which is displaced horizontally by the laminated rubber 6 when an earthquake occurs.
In this embodiment, an example is shown in which the magnetic damper 10A is installed vertically between the foundation as the lower structure 2 and the building as the upper structure 4, but it may also be installed between each floor of a building, such as between the lower and upper floors of the building, or it may be installed horizontally between the building and a foundation provided on the periphery of the building.

As shown in Figures 2 to 4, the magnetic damper 10A includes a cylinder 12, a rod 14, a first magnet 16, a second magnet 18, one mounting member 22, and the other mounting member 24.

The cylinder 12 is a metal container composed of a cylindrical wall 1202 that forms the inner surface of the cylinder 12, and a pair of disk-shaped end walls 1204, 1206 that close both axial ends of the cylinder 12 and through which the rod 14 passes.
One of the pair of end walls 1204 , 1206 closes one end 12 A of the cylinder 12 , and the other is a second end wall 1206 that closes the other end 12 B of the cylinder 12 .

The rod 14 is disposed on the axis of the cylinder 12 so as to be capable of reciprocating motion, and is a metal bar-shaped member protruding from a first end wall 1204 and a second end wall 1206 at both ends of the cylinder 12 .
In the initial position shown in FIG. 1 , the center of the rod 14 in the axial direction is located at the center of the cylinder 12 in the axial direction.

The first magnets 16 are permanent magnets arranged on the inner circumferential surface of both ends of the cylindrical wall 1202 of the cylinder 12 in the axial direction.
The first magnets 16 are provided with a uniform width and thickness around the entire inner circumferential surface at both ends of the cylindrical wall 1202 .

The second magnet 18 is a permanent magnet arranged on the outer circumferential surface of the axial center portion of the rod 14 .
The second magnet 18 is provided with a uniform width and thickness around the entire outer circumferential surface of the central portion of the rod 14 .

In this embodiment, the reciprocating movement of the rod 14 passing through the cylinder 12 is suppressed by applying an attractive force (attractive force) to the first magnet 16 and the second magnet 18, so that the radially inner side of the first magnet 16 and the radially outer side of the second magnet 18 have different magnetic poles.
Specifically, if the radially inner side of the first magnet 16 is a south pole, the radially outer side of the second magnet 18 is a north pole, and if the radially inner side of the first magnet 16 is a north pole, the radially outer side of the second magnet 18 is a south pole.

The one mounting member 22 and the other mounting member 24 are made of metal and are provided on both end portions 12A, 12B of the magnetic damper 10A, respectively.
That is, one mounting member 22 is attached to one end 14A of the rod 14 protruding from one end 12A in the axial direction of the cylinder 12, and the other mounting member 24 is attached to the second end wall 1206 located at the other end 12B in the axial direction of the cylinder 12.

As shown in FIG. 1 , one mounting member 22 is connected to the upper structure 4 in a state in which it can swing about an axis 4B extending in a vertical direction perpendicular to the axial direction of the cylinder 12, and the other mounting member 24 is connected to the lower structure 2 in a state in which it can swing about an axis 2B extending in a vertical direction perpendicular to the axial direction of the cylinder 12.
Specifically, for example, one of the mounting members 22 is connected to the upper structure 4 in a state in which it can swing around an axis passing through the center of the mounting hole 2202, by supporting an axis 4B that is swingably inserted into the mounting hole 2202 by a retaining member 4A that is attached to the lower part of the upper structure 4.

In addition, the other mounting member 24 is attached to a second end wall 1206 located at the other end of the cylinder 12 in the axial direction, and is composed of a cylindrical portion 2402 protruding in the axial direction from the second end wall 1206, and a mounting portion 2404 provided at the end of the cylindrical portion 2402.
The cylindrical portion 2402 is formed to have a length capable of accommodating the rod 14 protruding from the second end wall 1206 of the cylinder 12 when the rod 14 moves to its maximum in the X1 direction (see FIG. 3).
The other mounting member 24 is connected to the lower structure 2 in a state in which it can swing around an axis passing through the center of the mounting hole 2406, by supporting an axis 2B, which is swingably inserted into a mounting hole 2406 provided in the mounting portion 2404, by a retaining member 2A attached to the upper part of the lower structure 2.

In this embodiment, one mounting member 22 is connected to the upper structure 4, and the other mounting member 24 is connected to the lower structure 2, but they may be arranged in the opposite manner. In other words, one mounting member 22 may be connected to the lower structure 2, and the other mounting member 24 may be connected to the upper structure 4.

Next, the operation of the magnetic damper 10A will be described.
In this embodiment, when earthquake motion assumed in normal design occurs, the amount of relative axial displacement of rod 14 with respect to cylinder 12 is less than length L1.
Furthermore, in the event of earthquake motion that exceeds the design assumption, the amount of relative axial displacement of the rod 14 with respect to the cylinder 12 will be greater than or equal to L1 and up to L1+L2.
3 shows the magnetic damper 10A in its most contracted state, and FIG. 4 shows the magnetic damper 10A in its most expanded state.

First, in the event of earthquake motion assumed in a normal design, which is considered to have a relatively high frequency and probability of occurrence, when the upper structure 4 moves in the X1 direction (see Figure 1), the magnetic damper 10A is pressed in the X1 direction where the rod 14 is inserted into the cylinder 12, and moves in the X1 direction, but the relative displacement between the cylinder 12 and the rod 14 is less than the length L1.
In addition, when earthquake motion occurs as assumed in normal designs, which is considered to have a relatively high frequency and probability of occurrence, when the upper structure 4 moves in the X2 direction (see Figure 1), the magnetic damper 10A is pulled in the X2 direction in which the rod 14 is pulled out of the cylinder 12, and moves in the X2 direction, but similarly, the relative displacement between the cylinder 12 and the rod 14 is less than the length L1.
In this way, when the relative displacement between the cylinder 12 and the rod 14 is less than the length L1, the first magnet 16 and the second magnet 18 are not in opposing positions, and therefore the attractive force acting between the first magnet 16 and the second magnet 18 is smaller than the attractive force acting when the first magnet 16 and the second magnet 18 are in opposing positions.
Therefore, the force exerted by the first magnet 16 and the second magnet 18 to suppress the reciprocating movement of the rod 14 passing through the cylinder 12 is also reduced, so that when seismic motion as envisaged in a normal design occurs, the damping force exerted by the magnetic damper 10A is hardly exerted, and the deterioration of the seismic isolation performance of the seismic isolated building is suppressed.

Next, in the event of earthquake motion that exceeds the design assumptions, which is considered to have a relatively low frequency and probability of occurrence, when the upper structure 4 moves in the X1 direction (see Figure 1), the magnetic damper 10A is pressed in the X1 direction where the rod 14 is inserted into the cylinder 12, and moves in the X1 direction, and the relative displacement between the cylinder 12 and the rod 14 becomes equal to or greater than the length L1.
In addition, if seismic motion occurs that exceeds the design assumptions, which are considered to have a relatively low frequency and probability of occurrence, when the upper structure 4 moves in the X2 direction (see Figure 1), the magnetic damper 10A is pulled in the X2 direction in which the rod 14 is pulled out of the cylinder 12, and moves in the X2 direction, and similarly, the relative displacement between the cylinder 12 and the rod 14 becomes equal to or greater than the length L1.
In this way, when the relative displacement between the cylinder 12 and the rod 14 becomes equal to or greater than the length L1, the first magnet 16 and the second magnet 18 are positioned opposite each other, and an attractive force acts between the first magnet 16 and the second magnet 18.
Therefore, the first magnet 16 and the second magnet 18 suppress the reciprocating movement of the rod 14 passing through the cylinder 12, and in the event of earthquake motion that exceeds the design assumption, the magnetic damper 10A exerts a damping force.

Even if the rod 14 moves in the X1 or X2 direction and the relative displacement between the cylinder 12 and the rod 14 exceeds the length L1, the first magnet 16 and the second magnet 18 maintain their opposing positional relationship, and the magnetic damper 10A continues to exert a damping force.

Then, when the rod 14, which had been moving in the X1 or X2 direction, returns to the X2 or X1 direction and the relative displacement between the cylinder 12 and the rod 14 becomes less than the predetermined length L1, the first magnet 16 and the second magnet 18 are no longer in opposing positions, the damping force of the magnetic damper 10A is no longer exerted, and the seismic isolation performance of the seismic isolated building is exerted.

In other words, the greater the relative displacement between the cylinder 12 and the rod 14 when earthquake motion occurs, the closer the first magnet 16 and the second magnet 18 will be, until they eventually come into opposing positions.
Therefore, the greater the amount of relative displacement between the cylinder 12 and the rod 14, the greater the attractive force acting between the first magnet 16 and the second magnet 18.
In this embodiment, when the amount of relative displacement between the cylinder 12 and the rod 14 becomes large but is still less than the length L1, the attractive force acting between the first magnet 16 and the second magnet 18 gradually becomes larger than the attractive force acting in the initial position, but is not large enough to suppress the reciprocating movement of the rod 14.
When the amount of relative displacement between the cylinder 12 and the rod 14 exceeds the length L1, the force acting between the first magnet 16 and the second magnet 18 becomes even stronger, suppressing the reciprocating movement of the rod 14.
Furthermore, when the relative displacement between the cylinder 12 and the rod 14 again becomes less than the length L1, the force acting between the first magnet 16 and the second magnet 18 becomes weaker and no longer suppresses the reciprocating movement of the rod 14.

In this way, according to this embodiment, in the magnetic damper 10A, the first magnet 16 is arranged on the inner circumferential surface of both axial ends of the cylinder 12, the second magnet 18 is arranged on the outer circumferential surface of the axial center of the rod 14, and the rod 14 is provided at a position where the second magnet 18 faces the axial center of the cylinder 12 in the initial position. When the relative displacement between the cylinder 12 and the rod 14 reaches or exceeds a predetermined value, the first magnet 16 and the second magnet 18 face each other and an attractive force acts, suppressing the movement of the rod 14. Therefore, with a simple configuration, it is advantageous in suppressing the deterioration of seismic isolation performance against earthquake motion assumed in a normal design and in exerting a damping force against earthquake motion that exceeds the assumption in the design.

In addition, the first magnet 16 is provided around the entire inner circumference of both ends of the cylinder 12, and the second magnet 18 is provided around the entire outer circumference of the center of the rod 14, which is advantageous in ensuring that the damping force is exerted only when earthquake motion occurs that exceeds the design assumptions and the relative displacement between the cylinder 12 and the rod 14 exceeds a predetermined value.

In addition, since the first magnet 16 and the second magnet 18 are made of permanent magnets, they generate magnetic force simply by being placed in the magnetic damper 10A, which is advantageous in terms of reducing costs.

Mounting members 22, 24 are attached to one end 14A of the rod 14 protruding from one end 12A in the axial direction of the cylinder 12 and to the other end 12B in the axial direction of the cylinder 12, respectively, and one mounting member 22 is connected to the upper structure 4 and the other mounting member 24 is connected to the lower structure 2, which is advantageous in exerting a damping force when the upper structure 4 is displaced relative to the lower structure 2 due to earthquake motion that exceeds the design assumptions.

In addition, one mounting member 22 and the other mounting member 24 are connected to the lower structure 2 and the upper structure 4, respectively, in a state in which they can swing around an axis extending in a vertical direction perpendicular to the axial direction of the cylinder 12. Therefore, even if an earthquake motion causes the upper structure 4 to move horizontally relative to the lower structure 2 in a direction intersecting the axial direction of the cylinder 12, the magnetic damper 10A can swing, so that the magnetic damper 10A can function while avoiding damage to the magnetic damper 10A.

Second Embodiment
In the first embodiment of magnetic damper 10A, the first magnet 16 and the second magnet 18 are permanent magnets, whereas in the second embodiment of magnetic damper 10B, at least one of the first magnet and the second magnet is an electromagnet.
In the following description of the embodiment, the same parts and members as those in the first embodiment are denoted by the same reference numerals and their description will be omitted, and the description will focus on the parts that are different from the first embodiment.

As shown in FIG. 5, the magnetic damper 10B of this embodiment includes a cylinder 12, a rod 14, a first magnet 26, a second magnet 28, one mounting member 22, the other mounting member 24, and a control unit 100.

The first magnets 26 are electromagnets that are disposed on the inner circumferential surfaces of both ends of the cylinder 12 in the axial direction, and generate magnetic force when energized (electric current flows).
The first magnets 26 are provided with a uniform width and thickness around the entire inner circumferential surface at both ends of the cylinder 12 .

The second magnet 28 is an electromagnet arranged on the outer circumferential surface of the central portion of the rod 14 in the axial direction.
The second magnet 28 is provided with a uniform width and thickness around the entire outer circumferential surface of the central portion of the rod 14 .

The control unit 100 controls the supply of electricity to the first magnet 26 and the second magnet 28, which are electromagnets.
The control unit 100 is configured to include a microcomputer including a CPU, a memory unit, an interface circuit, etc., and the memory unit stores a control program executed by the CPU, and the first magnet 26, the second magnet 28, and a vibration sensor (not shown) are connected via the interface circuit.
In this embodiment, a vibration sensor connected to the control unit 100 is provided in the seismically isolated building, and the vibration of the seismically isolated building is detected by detecting the amount of vibration (e.g., acceleration) of the upper structure 4.

In this embodiment, the control unit 100 applies electricity to the first magnet 26 and the second magnet 28 when the seismically isolated building vibrates.
Then, after the control unit 100 has energized the first magnet 26 and the second magnet 28, if it determines that the vibration of the seismically isolated building has stopped based on the amount of vibration of the upper structure 4 detected by the vibration sensor, the control unit 100 stops energizing the first magnet 26 and the second magnet 28.

The operation of the magnetic damper 10B in this embodiment when earthquake motion occurs is the same as in the first embodiment, but in this embodiment, current is passed through the first magnet 26 and the second magnet 28 when the seismically isolated building vibrates.

Thus, according to this embodiment, the first magnet 26 and the second magnet 28 are electromagnets, and when the seismically isolated building vibrates, the control unit 100 energizes the first magnet 26 and the second magnet 28, and when the vibration of the seismically isolated building stops, the control unit 100 stops energizing the first magnet 26 and the second magnet 28. This makes it possible to adjust the timing at which the first magnet 26 and the second magnet 28 generate magnetic force, which is advantageous in terms of improving convenience.
Furthermore, if the control unit 100 is configured to pass current through the first magnet 26 and the second magnet 28 when the seismically isolated building vibrates, no current will be passed through the magnets when no earthquake is occurring, which is advantageous in terms of reducing costs.
Furthermore, the same members and configurations as those in the first embodiment provide the same effects as those in the first embodiment.

In this embodiment, an example is shown in which the first magnet 26 and the second magnet 28 are both electromagnets, but since it is sufficient that an attractive force be exerted between the first magnet 26 and the second magnet 28 under specified conditions, it is sufficient that at least one of the first magnet 26 and the second magnet 28 is composed of an electromagnet.
That is, the first magnet 26 may be an electromagnet and the second magnet 28 may be a permanent magnet, or the first magnet 26 may be a permanent magnet and the second magnet 28 may be an electromagnet. In this case, an attractive force can be generated by passing electricity through the magnet formed of an electromagnet.

Third Embodiment
In the magnetic damper 10A of the first embodiment, the rod 14 passes through a pair of end walls 1204, 1206 of the cylinder 12, whereas in the magnetic damper 10C of the third embodiment, a further difference is that the rod 30 has a male threaded portion 3002, and a female threaded member 32 having a female threaded portion 3202 that can be screwed into the male threaded portion 3002 is disposed.

As shown in FIG. 6, the magnetic damper 10C of this embodiment includes a cylinder 12, a rod 30, a first magnet 16, a second magnet 18, one mounting member 22, the other mounting member 24, and a female thread member 32.

The rod 30 has a male thread portion 3002 provided in a half portion on one end portion 30A side in the longitudinal direction, and is disposed so as to be capable of reciprocating and rotatable on the axis of the cylinder 12 .
The rod 30 is a metal rod-shaped member that protrudes from a first end wall 1204 and a second end wall 1206 at both ends of the cylinder 12, and one end 30A of the rod 30 is rotatably supported on one of the mounting members 22 via a bearing 3004, and is also rotatably supported by the second end wall 1206.
As in the first embodiment, in the initial position shown in Figure 1, the rod 30 is positioned so that the second magnet 18 in the axial center of the rod 30 faces the axial center of the cylinder 12.

The female thread member 32 has a female thread portion 3202 that can be screwed into the male thread portion 3002 of the rod 30, and is arranged non-rotatably.
The female thread member 32 is composed of, for example, a ball screw, and is attached to the outer surface of the end wall where half of the rod 30 is located on the outer surface of the cylinder 12, i.e., the outer surface of the first end wall 1204 at one end 12A of the cylinder 12, and the axis of the female thread portion 3202 and the axis of the rod 30 are aligned.

In the magnetic damper 10C of this embodiment, when the rod 30 is pressed in the X1 direction to be inserted into the cylinder 12 and moves in the X1 direction, the male thread portion 3002 and the female thread portion 3202 cause the rod 30 to move in the X1 direction while rotating forward.
In addition, in the magnetic damper 10C, when the rod 30 is pulled in the X2 direction to be pulled out of the cylinder 12 and moves in the X1 direction, the male thread portion 3002 and the female thread portion 3202 cause the rod 30 to move in the X2 direction while rotating in the reverse direction.

The operation of the magnetic damper 10C in this embodiment when earthquake motion occurs is the same as in the first embodiment, but in this embodiment, the rod 30 moves while rotating when it moves in the X1 direction or the X2 direction.

As described above, according to the present embodiment, in addition to the same effects as those of the first embodiment, the following effects are achieved.
In this embodiment, the rod 30 has a male threaded portion 3002 and is arranged so as to be able to reciprocate and rotate on the axis of the cylinder 12, and the female threaded member 32 having a female threaded portion 3202 that can be screwed into the male threaded portion 3002 is arranged so as not to rotate. Therefore, the rod 30 moves while rotating, which is advantageous in terms of exerting a uniform damping force.
Further, the male thread portion 3002 is provided on one half of the longitudinal end portion 30A side of the rod 30, and the female thread member 32 is attached to the first end wall 1204 where the half of the rod 30 is located on the outer surface of the cylinder 12. Therefore, an effect is achieved that the rod 30 can move while rotating with a simple configuration.

In this embodiment, the rod 30 has a male threaded portion 3002 in half of one end 30A, but the rod 30 may have male threaded portions 3002 all the way from one end 30A to the other end 30B. In this case, if the female thread member 32 is also attached to the outer surface of the second end face 1206 wall at the other end 12B of the cylinder 12, this is advantageous for stably rotating the rod 30.

In addition, in this embodiment, the female thread member 32 is attached to the outer surface of the first end wall 1204 at one end 12A of the cylinder 12, but the female thread portion 3202 may be provided on the inner periphery of the first end wall 1204, so that the first end wall 1204 has the function of the female thread member 32. This is advantageous in reducing the number of parts and cutting costs.

(Fourth embodiment)
In the magnetic damper 10A of the first embodiment, the second magnet 18, which is a permanent magnet, is arranged on the outer peripheral surface of the rod 14, whereas in the magnetic damper 10D of the fourth embodiment, the conductor 48 is arranged on the outer peripheral surface of the rod 14.

As shown in FIG. 7, the conductor 48 is an electrically conductive copper plate, and is disposed on the outer circumferential surface of the central portion of the rod 14 in the axial direction.
The conductor 48 in this embodiment is provided with a uniform width and thickness all around the outer circumferential surface of the central portion of the rod 14 .

In this embodiment, the conductor 48 is made of a copper plate, but it may be made of other metals as long as they are electrically conductive.
In addition, in this embodiment, an example is shown in which the first magnet 16, which is a permanent magnet, is provided on the inner surface of the cylinder, and the conductor 48 is provided on the outer surface of the rod 14, but a configuration in which the conductor is provided on the inner surface of the cylinder 12 and the permanent magnet is provided on the outer surface of the rod 14 may also be used.

In this embodiment, when seismic motion occurs and the first magnet 16 provided in the cylinder 12 and the conductor 48 provided in the rod 14 are positioned opposite each other, the relative displacement between the first magnet 16 and the conductor 48 generates an induced electromotive force due to electromagnetic induction in the conductor 48, causing an eddy current to flow. This eddy current interacts with the magnetic field of the first magnet 16, generating a resistance force between the first magnet 16 and the conductor 48 in the opposite direction to the direction of the relative displacement, and this resistance force acts as a damping force.

The operation of the magnetic damper 10D of this embodiment when seismic motion occurs is similar to that of the first embodiment, but in this embodiment, a resistance force is generated between the conductor 48 provided on the outer peripheral surface of the rod 14 and the first magnet 16.
FIG. 8 shows the magnetic damper 10D in its most contracted state, and FIG. 9 shows the magnetic damper 10D in its most expanded state.

Thus, according to this embodiment, the first magnet 16, which is a permanent magnet, is arranged on the inner circumferential surface of both ends of the axial direction of the cylinder 12 in the magnetic damper 10D, the conductor 48 is arranged on the outer circumferential surface of the central portion of the axial direction of the rod 14, and in the initial position, the conductor 48 arranged in the central portion of the rod 14 is provided in a position facing the central portion of the axial direction of the cylinder 12. Therefore, when the relative displacement amount between the cylinder 12 and the rod 14 becomes equal to or greater than a predetermined value, the first magnet 16 and the conductor 48 face each other, and the movement of the rod 14 is suppressed by the resistance force generated by the action of the eddy current flowing in the conductor 48 and the magnetic field of the first magnet 16. This simple configuration is advantageous in suppressing the deterioration of seismic isolation performance against earthquake motion assumed in a normal design and in exerting a damping force against earthquake motion that exceeds the assumption in the design.

In addition, the first magnet 16 is provided around the entire inner circumference of both ends of the cylinder 12, and the conductor 48 is provided around the entire outer circumference of the center of the rod 14, which is advantageous in ensuring that the damping force is exerted only when earthquake motion occurs that exceeds the design assumptions and the relative displacement between the cylinder 12 and the rod 14 exceeds a predetermined value.

In addition, since the first magnet 16 is a permanent magnet, it generates magnetic force simply by being placed in the magnetic damper 10D, which is advantageous in terms of reducing costs.

Furthermore, the same components and configurations as those in the first embodiment provide the same effects as those in the first embodiment.

In the magnetic damper 10D of the fourth embodiment, similar to the magnetic damper 10C of the third embodiment, the rod 14 may have a male threaded portion, and a female threaded member having a female threaded portion that can be screwed into the male threaded portion may be further disposed, so that when the rod 14 moves in the X1 or X2 direction, it moves while rotating via the male threaded portion and the female threaded portion.

Fifth embodiment
In the magnetic damper 10B of the second embodiment, the second magnet 28, which is an electromagnet, is arranged on the outer peripheral surface of the rod 14, whereas in the magnetic damper 10E of the fifth embodiment, the conductor 48 is arranged on the outer peripheral surface of the rod 14.

As shown in FIG. 10, the conductor 48 is an electrically conductive copper plate, similar to the fourth embodiment, and is disposed on the outer circumferential surface of the rod 14 at the center in the axial direction.
The conductor 58 in this embodiment is provided with a uniform width and thickness all around the outer circumferential surface of the central portion of the rod 14 .

In addition, in this embodiment, an example is shown in which the first magnet 26, which is an electromagnet, is provided on the inner surface of the cylinder, and the conductor 48 is provided on the outer surface of the rod 14, but a configuration in which the conductor is provided on the inner surface of the cylinder 12 and the electromagnet is provided on the outer surface of the rod 14 may also be used.

The control unit 200 controls the supply of electricity to the first magnet 26, which is an electromagnet, and is configured in the same manner as in the second embodiment, and is connected to the first magnet 26 via an interface circuit.
In this embodiment, the control unit 200 applies electricity to the first magnet 26 when the seismically isolated building vibrates.
Then, after the control unit 200 has energized the first magnet 26, if it determines that the vibration of the seismically isolated building has stopped based on the amount of vibration of the upper structure 4 detected by the vibration sensor, the control unit 200 stops energizing the first magnet 26.

In this embodiment, when seismic motion occurs and the control unit 200 energizes the first magnet 26, the first magnet 26 provided on the cylinder 12 and the conductor 48 provided on the rod 14 are positioned opposite each other, the relative displacement between the first magnet 26 and the conductor 48 generates an induced electromotive force due to electromagnetic induction in the conductor 48, causing an eddy current to flow. This eddy current interacts with the magnetic field of the first magnet 26, generating a resistance force between the first magnet 26 and the conductor 48 in the opposite direction to the relative displacement, and this resistance force acts as a damping force.

The operation of the magnetic damper 10E in this embodiment when earthquake motion occurs is the same as in the first embodiment, but in this embodiment, the first magnet 26 is energized when the seismically isolated building vibrates.

Thus, according to this embodiment, the first magnet 26 is an electromagnet, and when the seismically isolated building vibrates, the control unit 200 energizes the first magnet 26, and when the vibration of the seismically isolated building stops, the control unit 200 stops energizing the first magnet 26. This makes it possible to adjust the timing at which the first magnet 26 generates a magnetic force, which is advantageous in terms of improving convenience.
Furthermore, if the control unit 200 is configured to pass current through the first magnet 26 when the seismically isolated building vibrates, no current will be passed through the magnet when no earthquake is occurring, which is advantageous in terms of reducing costs.

Furthermore, the same components and configurations as those in the first embodiment provide the same effects as those in the first embodiment.

In the magnetic damper 10E of the fifth embodiment, similar to the magnetic damper 10C of the third embodiment, the rod 14 may have a male threaded portion, and a female threaded member having a female threaded portion that can be screwed into the male threaded portion may be further disposed, so that when the rod 14 moves in the X1 or X2 direction, it moves while rotating via the male threaded portion and the female threaded portion.

2 Lower structure 2A Holding member 4 Upper structure 4A Holding member 6 Laminated rubber 10A, 10B, 10C, 10D, 10E Magnetic damper 12 Cylinder 12A One end 12B Other end 1202 Cylindrical wall 1204 First end wall 1206 Second end wall 14, 30 Rod 14A, 30A One end 14B, 30B Other end 16, 16A First magnet 18 Second magnet 22 One mounting member 2202 Mounting hole 24 Other mounting member 2402 Cylindrical portion 2404 Mounting portion 2406 Mounting hole 3002 Male threaded portion 32 Female threaded member 3002 Female threaded portion 3004 Bearing 48 Conductor 100 Control unit

Claims (13)

A magnetic damper comprising: a cylinder; and a rod arranged on an axis of the cylinder so as to be capable of reciprocating motion and protruding from both ends of the cylinder,
A first magnet is disposed on an inner peripheral surface of both ends of the cylinder in an axial direction;
A second magnet is disposed on an outer circumferential surface of the rod at a central portion in the axial direction,
The first magnet has a magnetic pole different from that of the radially inner side and the radially outer side of the second magnet,
The rod is provided at a position where the second magnet faces a central portion of the cylinder in an axial direction in an initial position.
1. A magnetic damper comprising: The first magnet is provided around the entire inner circumferential surface of each end of the cylinder,
The second magnet is provided around the entire outer circumferential surface of the central portion.
2. The magnetic damper according to claim 1. The first magnet and the second magnet are permanent magnets.
3. The magnetic damper according to claim 1 or 2. At least one of the first magnet and the second magnet is an electromagnet,
Further comprising a control unit that energizes the electromagnet.
3. The magnetic damper according to claim 1 or 2. A magnetic damper comprising: a cylinder; and a rod arranged on an axis of the cylinder so as to be capable of reciprocating motion and protruding from both ends of the cylinder,
a magnet disposed only on the inner peripheral surface of each of both ends in the axial direction of the cylinder and on one of the outer peripheral surface of the central portion of the rod in the axial direction;
a conductor disposed only on the inner peripheral surfaces of both ends in the axial direction of the cylinder and on the outer peripheral surface of the central portion of the rod in the axial direction;
In the initial position, the magnet or the conductor arranged in the center of the rod is provided at a position facing the center of the cylinder in the axial direction.
1. A magnetic damper comprising: The magnet or the conductor disposed in the cylinder is provided over the entire inner circumferential surface at both ends of the cylinder,
The magnet or the conductor disposed on the rod is provided around the entire outer circumferential surface of the central portion of the rod.
6. The magnetic damper according to claim 5. The magnet is a permanent magnet.
7. The magnetic damper according to claim 5 or 6. The magnet is an electromagnet,
Further comprising a control unit that energizes the electromagnet.
7. The magnetic damper according to claim 5 or 6. The magnetic damper is installed in a seismically isolated building that comprises an upper structure supported by a lower structure in a seismically isolated manner,
An attachment member is attached to an end of the rod protruding from one end of the cylinder in the axial direction and to the other end of the cylinder in the axial direction,
one of the mounting members is connected to the upper structure;
The other mounting member is connected to the lower structure.
9. The magnetic damper according to claim 1, wherein the magnetic damper is a magnetic material. The mounting member is connected to the lower structure and the upper structure in a state in which the mounting member can swing around an axis extending in a vertical direction perpendicular to the axial direction of the cylinder.
10. The magnetic damper according to claim 9. The control unit energizes the electromagnet when the seismic isolated building vibrates.
11. A magnetic damper according to claim 9 or 10 which cites claim 4 or claim 8. The rod has a male thread and is arranged to be reciprocable and rotatable on the axis of the cylinder;
A female screw member having a female screw portion that can be screwed into the male screw portion is arranged in a non-rotatable manner.
The magnetic damper according to any one of claims 1 to 11. The male thread portion is provided on at least half of the rod in the longitudinal direction,
The cylinder has a cylindrical wall that constitutes an inner peripheral surface of the cylinder, and a pair of end walls that close both ends of the cylinder in an axial direction and through which the rod passes,
The female thread member is attached to the end wall where the half of the rod is located on the outer surface of the cylinder.
13. The magnetic damper according to claim 12.

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