JP7807334B2 - Seismic isolation device - Google Patents

Description

The present invention relates to a seismic isolation device that is effective against everything from minor vibrations to major earthquakes.

Seismic isolation devices are known for protecting precision equipment and buildings from earthquake motion. Such isolation devices generally comprise a fixed part that is installed on the floor or ground, a movable part on which the precision equipment, building, or other seismically isolated object is placed, and an isolator and damper that are installed between the fixed and movable parts.

When vibration energy is transmitted from the fixed part to the movable part, the isolator separates the movable part from the fixed part, allowing it to vibrate freely, lengthening the vibration of the movable part and reducing the response acceleration of the seismically isolated object. The damper also absorbs the vibration energy transmitted to the movable part, quickly converging the vibration of the movable part that has been lengthened by the isolator.

In such seismic isolation devices, if the damping force of the damper is increased to accommodate seismic motion from a major earthquake, such as one exceeding a seismic intensity of 5+, the resistance that the damper exerts against the free vibration of the moving part also increases, meaning that the isolator does not function adequately against micro-vibrations associated with small to medium-sized earthquakes, for example, and it becomes impossible to reduce the response acceleration of the seismically isolated object to vibration. On the other hand, if the damping force of the damper is set to accommodate micro-vibrations, the displacement of the moving part in response to large seismic motion will be excessive, raising concerns about interference between the moving part and surrounding structures and making it difficult to quickly converge the vibration of the moving part.

In response to these issues, Patent Document 1 discloses a seismic isolation device using elastic sliding bearings. This elastic sliding bearing combines an elastic bearing made of laminated rubber with a sliding bearing, and is configured to dissipate lateral vibrations through deformation of the laminated rubber when small vibrations act on the movable part due to a small- to medium-sized earthquake. Furthermore, when a large earthquake causes large vibrations that exceed the specified deformation amount of the laminated rubber to act on the movable part, a sliding member attached integrally to the laminated rubber slides on the fixed part, allowing the device to cope with vibrations of a magnitude that are difficult for the laminated rubber to handle.

JP 2009-281559

For example, in precision processing fields such as semiconductor manufacturing, it is necessary to sufficiently reduce the response acceleration of seismically isolated objects not only in response to the large vibrations that accompany major earthquakes, but also to the micro-vibrations that occur in small- to medium-sized earthquakes, in order to prevent adverse effects on product processing.

However, the elastic bearings and sliding bearings used in seismic isolation devices are mechanisms that combine the functions of an isolator and a damper, and it has been difficult to limit their function as a damper while still fully utilizing their isolator function.

The present invention was developed in consideration of these issues, and its purpose is to provide a seismic isolation device that can widely optimize the damping force exerted by the damper for vibrations of various magnitudes, from the large seismic motions caused by mega-earthquakes to the micro-vibrations caused by small to medium-sized earthquakes, and that can reduce as much as possible the response acceleration that occurs in the object to be isolated.

The seismic isolation device of the present invention comprises a fixed section, a movable section on which an object to be isolated is placed and which is disposed on the fixed section, a support and guide mechanism that allows horizontal movement of the movable section relative to the fixed section and includes a track member and a movable block that reciprocates along the track member, a damper unit that exerts a reaction force against the movement of the movable section relative to the fixed section, and an elastic restoring member that returns the movable section to its initial position on the fixed section. The damper unit is composed of a first damper disposed relative to the fixed section, and a second damper that has a damping force and maximum movable amount set smaller than those of the first damper and is disposed between the first damper and the movable section to connect the first damper and the movable section.

This invention makes it possible to optimize the damping force exerted by the damper over a wide range of vibrations, from the large seismic motions caused by mega-earthquakes to the micro-vibrations caused by small to medium-sized earthquakes, thereby reducing as much as possible the response acceleration that occurs in the seismically isolated object.

1 is a schematic plan view showing a first embodiment of a seismic isolation device to which the present invention is applied. FIG. 10 is a perspective view showing an example of a linear guide that can be used as a support guide mechanism. FIG. 10 is a cross-sectional view showing an example of a viscous damper that can be used as the first damper. FIG. 10 is a perspective view showing a ball spline device that can be used as a second damper. 10 is a schematic plan view showing a state in which the movable part of the seismic isolation device shown in the embodiment has started to move in the X+ direction. FIG. 10 is a schematic plan view showing a state in which the movable part of the seismic isolation device shown in the embodiment has moved in the X+ direction to the maximum movable range of the second damper. FIG. 7 is a schematic plan view showing a state in which the movable part has further moved in the X+ direction from the state shown in FIG. 6; FIG. 8 is a schematic plan view showing a state in which the movable part starts to move in the X-direction from the state shown in FIG. 7. 8 is a schematic plan view showing a state in which the movable part has further moved in the X-direction from the state shown in FIG. 7. FIG. 10 is a perspective view showing a second embodiment of a seismic isolation device to which the present invention is applied. 10 is a perspective view showing a state in which a movable part and one of the second dampers have been removed from the seismic isolation device according to the second embodiment. FIG.

The seismic isolation device of the present invention will be described in detail below with reference to the attached drawings.

Figure 1 is a schematic plan view showing a first embodiment of a seismic isolation device 1 to which the present invention is applied. The seismic isolation device 1 of this first embodiment comprises a fixed part 2 that is installed on a floor surface, the ground, etc.; a movable part 3 on which an object to be seismically isolated, such as a precision instrument or a building, is placed; a support guide mechanism 4 that serves as an isolator that guides the horizontal movement of the movable part 3 relative to the fixed part 2 (the direction of the arrow X in Figure 1); a damper unit 5 that applies a reaction force to the movement of the movable part 3 in the X direction; and an elastic restoring member 6 that returns the movable part 3 to its initial position on the fixed part 2.

For example, if the seismic isolation object is a precision instrument or a work of art, the fixed part 2 is a fixed table installed on the floor of a building or loading platform, and if the seismic isolation object is a building, it is a building foundation installed on the ground.

Furthermore, if the seismic isolation object is, for example, a precision instrument or a work of art, the movable part 3 is a movable table supported on the fixed table via the support and guide mechanism, and if the seismic isolation object is a building, it is a sturdy movable frame supported on the building foundation via the support and guide mechanism.

The support guide mechanism 4 can be, for example, a linear guide 40 as shown in Figure 2. This linear guide 40 is composed of a track member 41 that is laid on the fixed part 2 along the X direction and has a ball or roller rolling surface 41a formed along the longitudinal direction, and a moving block 42 that has an infinitely circulating row of rolling elements inside and can freely reciprocate along the track member 41. The moving part 3 is fixed to the moving block 42, and when the moving block 42 reciprocates along the track member 41, the moving part 3 also moves in the X direction on the fixed part 2 together with the moving block 42.

The support guide mechanism 4 is not limited to the linear guide 40 shown in Figure 2, as long as it can ensure free linear reciprocating motion of the movable part 3 relative to the fixed part 2.

On the other hand, the damper unit 5 is composed of a combination of a first damper 50 and a second damper 51. The first damper 50 is provided to correspond to the range of movement of the movable part 3 on the fixed part 2, i.e., the range of movement of the movable part by the support guide mechanism, and is capable of responding to seismic motions such as large earthquakes with large amplitudes and vibration energy. On the other hand, the second damper 51 is provided between the first damper 50 and the movable part 3 to connect them, and is capable of responding to micro-vibrations with small amplitudes and vibration energy such as small to medium-sized earthquakes, traffic vibrations, and wind swaying of buildings.

The first damper 50 can be, for example, a viscous damper 70 as shown in Figure 3. This viscous damper 70 includes a threaded shaft 71 that is axially aligned with the X direction on the fixed part and has a helical thread groove formed on its outer surface; a damper body 72 that is cylindrical and passes through the threaded shaft 71 and moves back and forth along the threaded shaft 71; a rotor 73 that is rotatably held inside the damper body 72; and a nut member 74 that is threadedly engaged with the threaded shaft 71 via a number of balls that roll in the thread grooves of the threaded shaft 71 and is fixed to the axial end of the rotor 73. A viscous fluid is filled between the inner surface of the damper body 72 and the outer surface of the rotor 73.

The screw shaft 71 and the nut member 74 form a so-called ball screw device. When the damper main body 72 moves on the fixed part 2 in the axial direction of the screw shaft 71, the nut member 74 rotates around the screw shaft 71, and this rotation is transmitted to the rotor 73. In other words, when the damper main body 72 performs linear reciprocating motion along the screw shaft 71, the rotor performs rotational reciprocating motion inside the damper main body, and a shear resistance force corresponding to the rotational speed of the rotor acts on the rotor from the viscous fluid.

The shear resistance force acting on the rotor 73 from the viscous fluid becomes a reaction force against the rotary reciprocating motion of the rotor 73, and after being converted by the ball screw device, becomes a reaction force against the linear reciprocating motion of the damper body 72 in the X direction. This makes it possible to attenuate the energy that moves the damper body 72 in the X direction.

Note that the viscous damper shown in Figure 3 is merely an example of a damper that can be used as the first damper 50, and is not limited to this. In other words, various types of dampers can be selected as the first damper 50 depending on the required range of motion and magnitude of damping force.

On the other hand, the second damper 51 is composed of a guide shaft 81 whose axial direction is aligned with the X direction relative to the movable part 3, and a sliding member 82 that is connected to the damper body 72 of the first damper 50 and moves along the guide shaft 81.

In this first embodiment, a ball spline device 80 shown in Figure 4 is used as the second damper. A rolling groove 81a for rolling elements is provided on the outer peripheral surface of the guide shaft 81 along the axial direction, and the sliding member 82 is attached to the guide shaft 81 via an infinitely circulating row of rolling elements. The rolling elements roll on the rolling groove 81a of the guide shaft 81, allowing the sliding member 82 to reciprocate along the guide shaft 81 with extremely little movement resistance. Meanwhile, by adjusting the magnitude of the preload applied to the rolling elements interposed between the guide shaft 81 and the sliding member 82, the movement resistance of the sliding member 82 relative to the guide shaft 81 can be increased or decreased as desired. In this sense, the ball spline device 80 functions as a damper with extremely little damping force.

Note that the ball spline shown in Figure 4 is merely an example of a device that can be used as the second damper 51, and is not limited to this. Various types of dampers can be selected depending on the range of motion required for the second damper 51 and the magnitude of the required damping force.

Both ends of the guide shaft 81 are fixed to the movable part 3 by a pair of support members, and the sliding member 82 connected to the first damper 50 can move along the guide shaft 81 only between the pair of support members. In this way, the damper unit 5 is structured so that the first damper 50 is connected to the movable part 3 via the second damper 51; in other words, the first damper 50 and the second damper 51 are arranged in series between the fixed part 2 and the movable part 3. The damping force exerted by the second damper 51, i.e., the magnitude of the reaction force exerted against the linear reciprocating motion of the movable part 3, is set to be smaller than the damping force exerted by the first damper 50.

Furthermore, while the first damper 50 is configured to exert a damping force over substantially the entire range of movement of the movable part 3, the second damper 51 is configured to exert a damping force only within a narrower range than the first damper 50. In other words, the maximum amount of movement of the second damper 51 is set smaller than that of the first damper 50.

As a result, when the movable part 3 moves in the X direction, the second damper 51 in the damper unit 5 operates before the first damper 50, and when the amount of movement of the movable part 3 exceeds the movable range of the second damper 51, the first damper 50 operates.

The elastic restoring member 6 comprises a first restoring member 61 provided between the damper body 72 of the first damper 50 and the fixed part 2, and a second restoring member 62 provided between the movable part 3 and the fixed part 2. The first restoring member 61 serves to return the first damper 50 to its initial position before operation after the vibration transmitted to the movable part 3 has subsided. The second restoring member 62 serves to return the movable part 3 to its initial position before operation after the vibration transmitted to the movable part 3 has subsided.

The seismic isolation device 1 of the first embodiment configured as described above operates as follows.

For example, when an earthquake causes vibrations to act on the fixed part 2, the support guide mechanism 4 separates the movable part 3 from the fixed part 2, and a relative linear reciprocating motion in the X direction occurs between the fixed part 2 and the movable part 3. As shown in Figure 5, when the movable part 3 first begins to move in the X+ direction relative to the fixed part 2, only the second damper 51, which has a damping force smaller than that of the first damper 50, operates, and the first damper 50 does not operate. That is, in the first damper 50, the damper body 72 does not move relative to the screw shaft 71, and in the second damper 51, the sliding member 82 moves relative to the guide shaft 81.

For this reason, if the amplitude of the vibration generated in the movable part 3 is within the movable range of the second damper 51, in this seismic isolation device 1, only the second damper 51 operates without operating the first damper 50, and the second damper 51 absorbs the vibration energy transmitted from the fixed part 2 to the movable part 3, quickly converging the vibration of the movable part 3.

In addition, because the damping force of the second damper 51 is set smaller than that of the first damper 50, the support guide mechanism 4 can be fully operated as an isolator to isolate the movable part 3 from vibrations of the fixed part 2 even in the event of minor vibrations such as small to medium-sized earthquakes, wind-induced shaking of the building, or traffic vibrations. Therefore, this seismic isolation device 1 can fully reduce the response acceleration occurring in the seismically isolated object mounted on the movable part 3 even in the event of minor vibrations, making it effective as a countermeasure against vibrations in precision processing equipment such as semiconductor manufacturing equipment.

On the other hand, if vibrations occurring in the movable part 3 cause the movable part 3 to move in the X+ direction beyond the movable range of the second damper 51, the sliding member 82 of the second damper 51 will hit the support member supporting the guide shaft 81 as shown in FIG. 6. As a result, if the movable part 3 moves further in the X+ direction, the first damper 50 will operate from this point. That is, as shown in FIG. 7, the damper body 72 of the first damper 50, which is connected to the sliding member 82 of the second damper 51, moves relative to the screw shaft 71, and the first damper 50 absorbs the vibration energy transmitted from the fixed part 2 to the movable part 3, thereby converging the vibrations of the movable part 3.

After this, when the direction of movement of the movable part reverses from the X+ direction to the X- direction, as shown in Figure 8, only the second damper 51, which has a smaller damping force than the first damper 50, operates in response to the movement of the movable part in the X- direction. At this time, the first damper 50 does not operate, and the damper body 72 of the first damper 50 remains in the position on the screw shaft 71 when the direction of movement of the movable part 3 reverses.

Then, as the movable part 3 moves further in the X-direction and the sliding member 82 of the second damper 51 hits the support member that supports the guide shaft 81, the first damper 50 begins to operate. That is, as shown in Figure 9, with the sliding member of the second damper 51 hitting the support member for the guide shaft, the damper body 72 of the first damper 50 moves in the X-direction relative to the screw shaft 71, and the first damper 50 absorbs the vibration energy transmitted from the fixed part 2 to the movable part 3, converging the vibration of the movable part 3.

In this way, in the seismic isolation device 1 of the first embodiment, if a large earthquake causes seismic motion with a large amount of movement to act on the fixed part 2, and the movable part 3 moves beyond the movable range of the second damper 51 relative to the fixed part 2, the first damper, which exerts a greater damping force than the second damper 51, will operate. As a result, even if the enormous seismic energy of a major earthquake is transmitted to the movable part, the large damping force exerted by the first damper can suppress the maximum displacement of the movable part, and the vibration of the movable part 3 can be quickly converged.

Next, we will explain a second embodiment of a seismic isolation device to which the present invention is applied.

Figure 10 shows a seismic isolation device of the second embodiment. Similar to the first embodiment, the seismic isolation device 1A of this second embodiment supports a movable part 3 on a fixed part 2 via a support guide mechanism 4, and the movable part 3 is freely movable on the fixed part 2 in the X direction. The linear guide 40 shown in Figure 2 can be used as the support guide mechanism 4 of this second embodiment. In the example shown in Figure 10, a track member 41 is laid on the fixed part 2 in the X direction, and a moving block 42 that slides on the track rail 41 is fixed to the movable part.

A damper unit 5 is provided between the fixed part 2 and the movable part 3. The damper unit 5 is composed of a combination of a first damper 50 and a pair of second dampers 51. The first damper 50 is provided to correspond to the range of movement of the movable part 3 on the fixed part 2, i.e., the range of movement of the movable part by the support guide mechanism 4, while the second damper 51 is provided between the first damper 50 and the movable part 3, connecting the first damper 50 and the movable part 3.

Figure 11 is a perspective view showing the first damper 50 exposed after either the movable part 3 or the second damper 51 has been removed. The first damper 50 includes a rack 52 fixed to the fixed part 2 along the X direction, a pinion gear 53 that rotates in mesh with the rack 52, and a rotary damper 54 that is rotated by the pinion gear 53 and is fixed to the second damper 51. The rack 52 is installed on the fixed part 2 in a position corresponding to the range of motion of the moving block 42 of the support guide mechanism 4. The rotary damper 54 is filled with a viscous fluid and is configured to exert a damping force on rotational motion input from the pinion gear 53.

On the other hand, as shown in FIG. 11 , the second damper includes a sliding member 55 fixed to the movable part 3, a guide shaft 56 to which the sliding member 55 is attached via multiple rolling elements and which is arranged along the X direction, an intermediate plate 57 on which the guide shaft 56 is installed, and a pair of locking members 58 provided on the intermediate plate 57 corresponding to both longitudinal ends of the guide shaft 56. The intermediate plate 57 is suspended from the movable part 3 via the sliding member 55 and the guide shaft 56, and movement of the guide shaft 56 in the X direction relative to the sliding member 55 allows the intermediate plate 57 to move in the X direction relative to the movable part 3. However, because the guide shaft 56 is set shorter than the length of the track rail 41 of the support and guide mechanism 4, the range of movement of the movable part 3 relative to the intermediate plate 57 is set shorter than the range of movement of the movable part 3 relative to the fixed part 2.

The combination of the sliding member 55 and the guide shaft 56 functions as a damper with extremely small damping force, similar to the ball spline device in the first embodiment. In other words, by adjusting the magnitude of the preload applied to the rolling elements interposed between the sliding member 55 and the guide shaft 56, it is possible to increase or decrease the movement resistance of the sliding member 55 relative to the guide shaft 56 as desired.

The rotary damper 54 is fixed to the back side of the intermediate plate 57, i.e., the surface opposite the surface on which the guide shaft 56 is laid. Therefore, when the intermediate plate 57 moves relative to the fixed part 2, the pinion gear 53 that meshes with the rack 52 rotates, causing the rotary damper 54 to exert a damping force, which acts against the movement of the intermediate plate 57 in the X direction.

In addition, although not shown in Figures 10 and 11, an elastic restoring member, such as a coil spring, is provided between the movable part 3 and the fixed part 2, and applies a biasing force in a direction returning the movable part 3, which has vibrated in the X direction on the fixed part 2, to the center position of the vibration amplitude. A similar elastic restoring member is also provided between the fixed part 2 and the intermediate plate 57, and applies a biasing force in a direction returning the intermediate plate 57 to its initial position on the fixed part.

The seismic isolation device of the second embodiment configured as described above operates as follows:

For example, when an earthquake causes vibrations to act on the fixed part 2, the movable part 3, which is supported by the support guide mechanism 4 acting as an isolator, moves in the X direction relative to the fixed part 2, causing reciprocating motion on the fixed part 2. If the amplitude of the reciprocating motion of the movable part 3 at this time is within the movable range of the second damper 51, i.e., within the range of movement of the sliding member 55 relative to the guide shaft 56, only the weak damping force of the second damper 51 acts on the movable part 3. At this time, the intermediate plate 57 is in a substantially stationary state on the fixed part 2.

As a result, similar to the first embodiment described above, the second damper 51 absorbs the vibration energy transmitted from the fixed part 2 to the movable part 3 in response to micro-vibrations such as small to medium-sized earthquakes, wind-induced shaking of the building, and traffic vibrations, thereby quickly converging the vibrations of the movable part 3. Furthermore, because the damping force of the second damper 51 is smaller than that of the first damper 50, the support guide mechanism 4 can operate sufficiently as an isolator, making it possible to sufficiently reduce the response acceleration occurring in the seismically isolated object mounted on the movable part 3.

On the other hand, when the amplitude of the reciprocating motion of the movable part 3 exceeds the movable range of the second damper 51, the movable part 3 strikes the locking member 58 provided on the intermediate plate 57, and the intermediate plate is dragged by the movable part 3 and moves in the X direction on the fixed part 2 together with the movable part 3.

As a result, in the first damper 50, the rotary damper 54 moves in the X direction relative to the fixed part 2, causing the pinion gear that meshes with the rack to rotate, and the damping force of the rotary damper 54 acts on the movement of the intermediate plate 57 in the X direction. And because the intermediate plate 57 is dragged by the movable part 3 and moves in the X direction, the damping force exerted by the rotary damper 54 acts on the movement of the movable part 3 in the X direction.

In this way, even in the seismic isolation device 1A of the second embodiment shown in Figure 10, if a large earthquake causes large-amplitude seismic motion to act on the fixed part 2 and the movable part 3 moves beyond the movable range of the second damper 51 relative to the fixed part 2, the first damper 50, which exerts a greater damping force than the second damper 51, will operate, and the large damping force exerted by the first damper 50 will be able to suppress the maximum displacement of the movable part and will also be able to quickly converge the vibration of the movable part 3.

As explained above, with the seismic isolation devices of the first and second embodiments, by connecting two types of dampers with different damping forces and maximum movable ranges in series between the fixed part 2 and the movable part 3, it is possible to sufficiently reduce the response acceleration occurring in the seismically isolated object mounted on the movable part in response to minute vibrations caused by small to medium-sized earthquakes, wind swaying of buildings, traffic vibrations, etc. It is also effective against large amounts of movement and large-energy vibrations associated with major earthquakes, making it possible to widely optimize the damping force exerted by the dampers in response to various types of vibration and to reduce as much as possible the response acceleration occurring in the seismically isolated object.

Furthermore, by setting the damping force exerted by the second damper 51 to any desired magnitude, it is possible to optimize the seismic isolation device for various uses.

In the embodiment of the present invention shown in the figures, an example has been described in which the movable part vibrates only in the X direction. However, by stacking a seismic isolation device whose movable part vibrates in the X direction with another seismic isolation device whose movable part vibrates in the Y direction, which is perpendicular to the X direction, it is also possible to create a seismic isolation device that operates within a horizontal, two-dimensional plane.

1... Seismic isolation device, 2... Fixed part, 3... Movable part, 4... Support guide mechanism, 5... Damper unit, 6... Elastic restoring member, 50... First damper, 51... Second damper

Claims (4)

A fixed portion;
a movable part on which an object to be isolated is placed and which is disposed on the fixed part;
a support and guide mechanism that allows the movable part to move horizontally relative to the fixed part and includes a track member and a moving block that reciprocates along the track member;
a damper unit that exerts a reaction force against the movement of the movable part relative to the fixed part;
an elastic restoring member that returns the movable part to an initial position on the fixed part,
The damper unit is
a first damper disposed relative to the fixed portion;
A seismic isolation device characterized by being composed of a second damper whose damping force and maximum movable amount are set smaller than those of the first damper, and which is arranged between the first damper and the movable part to connect the first damper and the movable part. The seismic isolation device described in claim 1, characterized in that the first damper operates only when the movement of the movable part exceeds the maximum movement of the second damper. The seismic isolation device described in claim 1, characterized in that the second damper includes a guide shaft arranged parallel to the track member of the support guide mechanism, and a sliding member that moves along this guide shaft. 4. The seismic isolation device according to claim 3, wherein the first damper operates when the movable portion moves beyond the movable range of the sliding member relative to the guide shaft of the second damper.