JP5164913B2 - Fluid pressure shock absorber and seismic isolation system - Google Patents

Description

  The present invention relates to a fluid pressure shock absorber and a seismic isolation system applied to a base isolation structure of a building.

  A fluid pressure shock absorber used for a seismic isolation system such as a building is disclosed in Patent Document 1, for example. This type of fluid pressure shock absorber requires a plurality of acceleration sensors that detect vibration and a plurality of electromagnetic valves that switch the damping force in stages based on the detection results of the acceleration sensors, which increases costs. At the same time, regular maintenance is required.

JP 2006-283839 A

  Therefore, an object of the present invention is to provide a fluid pressure shock absorber and a seismic isolation system capable of reducing cost and facilitating maintenance.

  In order to solve the above problems, the present invention has the following means.

The present invention includes a cylinder filled with a working fluid;
A piston inserted into the cylinder and defining the inside of the cylinder into two pressure chambers;
A piston rod having one end connected to the piston and the other end extending outward from one end of the cylinder;
A liquid passage filled with the working fluid and flowing the working fluid to and from the pressure chamber;
Damping force generating means for generating a damping force in the working fluid flowing through the liquid passage;
Damping force switching means for switching the damping force generated by the damping force generating means;
A fluid pressure shock absorber comprising:
The damping force switching means is
A damping force switching valve for switching the damping force generating means to a low side or a high side by circulating or blocking the liquid passage;
A valve switching mechanism for switching the damping force switching valve from open to closed,
The valve switching mechanism is
A connection / separation mechanism provided on the damping force switching valve so as to be connectable and separable, wherein the damping force generating means has a low damping force side in a connected state, and the damping force generating means has a high damping force side in a separated state;
Provided between the connection separation mechanism and the piston rod, when the movement amount of the piston rod is small, the connection state of the connection separation mechanism is maintained, and the axial movement amount of the piston rod is equal to or greater than a predetermined value. In some cases, a release mechanism is provided for bringing the connection / separation mechanism into a separated state.

  According to the present invention, it is possible to provide a fluid pressure shock absorber and a seismic isolation system capable of reducing cost and facilitating maintenance.

It is a block diagram which shows typically one Example of the fluid pressure damper and seismic isolation system by this invention. It is a longitudinal cross-sectional view which shows the structure of a fluid pressure buffer. It is a front view which shows the external appearance shape of a fluid pressure buffer, and a valve switching mechanism. It is the top view which looked at the fluid pressure buffer and the valve switching mechanism from above. It is the figure which looked at the fluid pressure buffer and the valve switching mechanism from the axial direction. It is a figure which shows the actuator 42 at the time of the seismic isolation operation state in which the connection pin 70 was inserted in the holding member 71. It is the figure which looked at the actuator 42 from the axial direction. It is a figure which shows the actuator 42 in the time of the high attenuation | damping mode state from which the connection pin 70 remove | deviated from the holding member 71. FIG. It is a figure which shows the state which removed the holding member 71 from the actuator. It is a front view of the fluid pressure buffer which shows an operation state when a piston rod moves to the extending direction more than predetermined. It is a front view of the fluid pressure shock absorber showing an operation state when the piston rod moves in the contraction direction more than a predetermined amount.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram schematically showing an embodiment of a fluid pressure shock absorber and a seismic isolation system according to the present invention. As shown in FIG. 1, the building 10 is made of a building such as a condominium or an office building, and is supported on the foundation 12 via a plurality of seismic isolation members 14. As the seismic isolation member 14, for example, laminated rubber in which rubber plates and iron plates are alternately laminated is used. Further, a fluid pressure damper 20 made of a hydraulic damper or the like is provided between the building 10 and the foundation 12. In the present embodiment, the seismic isolation system 30 is configured by the seismic isolation member 14 and the fluid pressure damper 20. The seismic isolation system 30 gives priority to the seismic isolation operation by the seismic isolation member 14, and the damping operation by the fluid pressure shock absorber 20 converges the shaking caused by the vibration of the building 10 and the operation stroke of the fluid pressure shock absorber 20 is set. When this is the case, the damping force is increased.

  As will be described later, when the seismic intensity is relatively small, the fluid pressure shock absorber 20 generates a small damping force so as not to disturb the seismic isolation operation by the seismic isolation member 14, and a large seismic intensity is input and the fluid pressure is reduced. When the operation stroke of the shock absorber 20 is equal to or greater than the set value, there is a damping force switching means for automatically switching the damping force by the damping force generating means so as to generate a large damping force.

  Here, the configuration of the fluid pressure shock absorber 20 will be described. FIG. 2 is a longitudinal sectional view showing the configuration of the fluid pressure shock absorber.

  As shown in FIG. 2, the fluid pressure shock absorber 20 has a mounting eye 25 provided at the proximal end portion of the outer case 22 and a mounting eye 26 provided at the distal end portion of the piston rod 23. One attachment eye 25 is connected to a joint 27 fixed to one of the building or the foundation via a connection member 27a, and the other attachment eye 26 is connected to a joint 28 fixed to the other of the building or the foundation. Connected through. Thereby, the fluid pressure shock absorber 20 is attached so as to buffer the relative displacement between the building 10 and the foundation 12 due to the vibration input.

  The fluid pressure shock absorber 20 includes a cylinder 36 filled with a working fluid (working oil) 35 in the outer case 22 and a piston 37 slidably fitted in the cylinder 36 in the Xa and Xb directions. Have. A proximal end portion of the piston rod 23 is fixed to the piston 37. The fluid pressure buffer 20 operates between the auxiliary tank 38 filled with the working fluid 35 and one of the two pressure chambers 36 a and 36 b in the cylinder 36 divided by the piston 37 and the auxiliary tank 38. A liquid passage 29A through which the fluid 35 flows, a check valve 30 provided in the piston 37 that allows only the flow of the working fluid 35 from the pressure chamber 36b to the pressure chamber 36a, and a right end side of the outer case 22 shown in FIG. A suction valve 31 that allows only the flow of the working fluid 35 from the liquid passage 29A to the pressure chamber 36b, and a damping force provided to the working fluid 35 that is provided on the left end side of the outer case 22 and flows through the liquid passages 29A and 29B. And two or more damping valves 32A and 32B (damping force generating means). The path communicating between the pressure chamber 36a and the liquid passage 29A has a system A having a damping valve 32A, a shutoff valve 39 (damping force switching valve), and a damping valve 32B (damping force generating means). There are two systems, B system. In the normal seismic isolation mode, when the working fluid 35 flows from both the A and B systems and a large seismic intensity is input and the operation stroke of the fluid pressure shock absorber 20 exceeds the set value, the B system is Shut off and switch to distribution using only the A system.

  In the embodiment of the present invention, the auxiliary tank 38 is provided outside the liquid passage 29 on the outer periphery of the cylinder 36 separately from the liquid passage 29. However, the liquid passage 29 itself may be used as an auxiliary tank.

  FIG. 3 is a front view showing the external shape of the fluid pressure shock absorber and the valve switching mechanism. FIG. 4 is a plan view of the fluid pressure buffer and the valve switching mechanism as seen from above. FIG. 5 is a view of the fluid pressure buffer and the valve switching mechanism as seen from the axial direction.

  As shown in FIG. 3, the fluid pressure shock absorber 20 includes a damping force switching mechanism (damping force switching means) 40 that switches from a setting with a low damping force to a setting with a high damping force.

The damping force switching mechanism 40 is provided on the left end side of the outer case 22, and is a shut-off valve 39 disposed slightly above the center of the outer case 22 in the height direction (vertical direction in FIG. 3). And an actuator 42 provided integrally with the off valve 39.
Further, the damping force switching mechanism 40 includes a damping force switching valve 50 that switches the damping force to a low side or a high side by circulating or blocking the liquid passage 29B communicated with the shutoff valve 39, and a damping force switching valve 50. And a valve switching mechanism 60 for switching from open to closed.

  As shown in FIGS. 3 to 5, when the fluid pressure shock absorber 20 is displaced beyond a predetermined displacement amount due to the input of vibration caused by an earthquake, the damping force switching valve 50 of the damping force switching mechanism 40 is switched. A valve switching mechanism 60 is attached to the outer periphery of the outer case 22.

  The damping force switching valve 50 opens a spool valve 52 that adjusts the liquid supply amount of the B system having the damping valve 32B, a valve portion 54 that has a valve seat that is opened and closed according to the movement position of the spool valve 52, and the spool valve 52. And a biasing member (coil spring) 56 that biases in the valve direction (Xb direction).

  The valve switching mechanism 60 is provided so as to be separable from the damping force switching valve 50. The damping valve 32A, 32B has a low damping force in the connected state, and the damping valve 32A, 32B has a high damping force in the separated state. The connection separation mechanism 62 is provided between the connection separation mechanism 62 and the piston rod 23. When the movement amount of the piston rod 23 is small, the connection state of the connection separation mechanism 62 is maintained, and the movement amount of the piston rod 23 in the axial direction is maintained. And a release mechanism 63 that puts the connection separation mechanism 62 into a disconnected state when the value becomes equal to or greater than a predetermined value.

  The release mechanism 63 includes slide guides 64A and 64B, slide members 65A and 65B, a rod member 66, a sliding member 67, and a swinging member 68.

  The connection / separation mechanism 62 includes a wire 69 and a connecting pin 70.

  The slide guides 64A and 64B are attached in parallel to a plate 61 fixed to the outer periphery of the outer case 22 so as to extend in the axial direction (X direction) of the piston rod 23.

  The slide guide 64A disposed on the upper side is engaged with the slide member 65A so as to be slidable in the X direction. Further, the upper slide guide 64A is formed to be shorter in length than the lower slide guide 64B, and stoppers for restricting the sliding range of the slide member 65A are provided at both left and right end portions. It is configured not to slide more than the displacement amount.

  A slide member 67 and a slide member 65B formed in a U-shape are slidably attached to the slide guide 64B arranged on the lower side, and the slide member 67 is slid in the central space portion of the slide member 67. A member 65B is disposed. The sliding member 67 includes a horizontal portion 67a extending in the horizontal direction (X direction), a first vertical portion 67b protruding upward from the left end of the horizontal portion 67a, and a first protrusion protruding upward from the right end of the horizontal portion 67a. 2 vertical portions 67c. Further, slide members 65A and 65B are arranged between the first vertical portion 67b and the second vertical portion 67c. The first vertical portion 67b is formed to extend to a height position where it abuts on the upper slide member 65A. Further, the second vertical portion 67c is formed to extend to a height position where the second vertical portion 67c contacts the lower slide member 65B.

  The distance in the horizontal direction (X direction) between the first vertical portion 67b and the second vertical portion 67c is either the sliding member 65A or 65B when the sliding member 67 moves in the horizontal direction (X direction). A non-abutting section is formed which becomes a play until it abuts on the. Therefore, even if the sliding member 67 is pressed and moved in the horizontal direction (X direction) by the rod member 66, the sliding members 65A and 65B are in contact with the first vertical portion 67b and the second vertical portion 67c. Stay stationary and inactive. For example, if two sliding members 67 are formed and the first vertical portion 67b and the second vertical portion 67c are configured to be slidable, the horizontal separation distance can be adjusted even after the fluid pressure shock absorber is installed. Can be possible.

  For example, in the case shown in FIG. 3, when the sliding member 67 is moved by a distance that is ½ of the separation distance between the first vertical portion 67b and the second vertical portion 67c, the first vertical portion 67b or Either one of the second vertical portions 67c abuts on any side surface of the slide members 65A and 65B. For example, the first vertical portion 67b presses the upper slide member 65A and the lower slide member 65B in the right direction (Xb direction) when the piston 37 operates in the contraction direction (Xb direction). Further, the second vertical portion 67c presses the lower slide member 65B leftward (Xa direction) when the piston 37 operates in the extending direction (Xa direction).

  One end of the rod member 66 is connected to the eye 26 via a bracket 66a, and the other end is connected to the left end of the sliding member 67. The rod member 66 moves in the X direction in conjunction with the expansion and contraction of the piston rod 23 caused by an earthquake input. To do.

  A swing member 68 having a rotation shaft 68a at the center is rotatably attached to the upper slide member 65A. The lower end of the swing member 68 has a long hole 68b that fits into the pin 65c attached to the center of the slide member 65B disposed on the lower side, and the right end of the wire 69 is at the upper end 68c of the swing member 68. It is connected.

  A connecting pin 70 connected to the left end portion of the wire 69 is inserted into an insertion hole of the holding member 71 for keeping the movable shaft in the actuator 42 in an open state so as not to close the push-off valve 39. The holding member 71 is normally held in a ring shape by insertion of the connecting pin 70, and when the piston rod 23 slides more than a predetermined amount, the connecting pin 70 is pulled out and changed to an open state to shut it. It is configured to be separated from the off valve 39.

  Here, the configuration of the actuator 42 will be described. FIG. 6A is a view showing the actuator 42 in the low attenuation mode state in which the connecting pin 70 is inserted into the holding member 71. FIG. 6B is a view of the actuator 42 as seen from the axial direction. FIG. 6C is a diagram illustrating the actuator 42 in the high attenuation mode state in which the connecting pin 70 is detached from the holding member 71. FIG. 6D is a view showing a state in which the holding member 71 is detached from the actuator 42.

  As shown in FIG. 6A, the actuator 42 includes a sliding shaft 82 inserted into the housing 80, a spring member 84 that urges the flange portion 82a of the sliding shaft 82 in the axial direction (X direction), A pressing member 86 disposed coaxially with the sliding shaft 82 and a coil spring 88 that transmits a pressing force that is pressed by the pressing member 86 to move the spool valve 52 in the axial direction (X direction).

  A right end side end portion 82b of the sliding shaft 82 projects rightward from the through hole 80b of the right side wall portion 80a of the housing 80, and is held in a non-movable state by a holding member 71 combined in a ring shape. Further, the left end side end portion 82c of the sliding shaft 82 protrudes to the left from the through hole 80d of the left side wall portion 80c of the housing 80 when moved to the left direction (Xa direction) by the pressing force of the spring member 84. Move to.

  As shown in FIGS. 6B and 6D, the holding member 71 is formed by connecting one ends of a pair of arcuate members 71a and 71b so as to be rotatable by a shaft 71c. An insertion hole 71d through which the connecting pin 70 is inserted in the axial direction (Xa direction) is provided at the other end of the pair of arcuate members 71a and 71b. In a state where the connecting pin 70 is inserted into the insertion holes 71d of the arc-shaped members 71a and 71b, the arc-shaped members 71a and 71b are ring-shaped on the outer periphery of the right end side end portion 82b of the sliding shaft 82 protruding to the outside of the housing 80. The sliding shaft 82 is fastened to the housing 80.

  As shown in FIG. 6C, when a large vibration is input and the piston rod 23 moves greatly in the axial direction (Xa, Xb direction), the connecting pin 70 is pulled out from the insertion hole 71d. At the same time, the pair of arcuate members 71a and 71b rotate in the opening direction about the shaft 71c and drop off from the right end 82b of the sliding shaft 82. As a result, since the holding by the holding member 71 is released, the sliding shaft 82 moves to the left (Xa direction) by the spring force of the spring member 84 to press the pressing member 86, via the spring of the coil spring 88. Thus, the spool valve 52 is pressed leftward (Xa direction). Note that a spring may be added outside or near the inside of the insertion hole 71d so that the holding member 71 can easily rotate in the opening direction when the connecting pin 70 is pulled out of the insertion hole 71d.

  As shown in FIG. 2, the spool valve 52 closes the valve portion 54 to block the flow of the working fluid 35 through the liquid passage 29B and switches to the high damping mode in which the damping force is generated only by the damping valve 32A. That is, the flow of the working fluid 35 by the operation of the piston 37 is limited to the damping valve 32A, and the damping force (resistance force) with respect to the stroke of the piston 37 is increased, so that larger vibrations can be effectively damped.

  As described above, according to the fluid pressure shock absorber 20 and the seismic isolation system 30, for example, a plurality of acceleration sensors for detecting vibrations disclosed in Patent Literature 1 and a plurality of damping forces that are switched stepwise based on the detection results of the acceleration sensors. No individual solenoid valve is required, and costs can be reduced and maintenance can be facilitated.

  Here, the operation of the valve switching mechanism 60 and the shut-off valve 39 according to the magnitude of the operation stroke of the piston 37 corresponding to the magnitude of the vibration input as described above will be described.

  In FIG. 3, when the input vibration is relatively small, even if relative displacement between the cylinder 36 and the piston rod 23 occurs, the sliding member 67 connected to the piston rod 23 via the rod member 66 is replaced with the sliding member. It only moves in the axial direction (X direction) within a range where it does not contact 65A and 65B. At this time, the swing member 68 does not rotate clockwise or counterclockwise around the pin 68 a and does not transmit vibration to the connecting pin 70.

  As described above, when the seismic intensity is relatively small, the first vertical portion 67b and the second vertical portion 67c of the slide members 65A and 65B are in the process of moving the sliding member 67 in the axial direction (Xa, Xb direction). It does not touch the side. For this reason, the fluid pressure damper 20 supplies the working fluid 35 to both the damping valves 32A and 32B so as to keep the damping force small so as not to hinder the seismic isolation operation by the seismic isolation member 14.

  Next, the mode switching operation when a large vibration occurs will be described.

  As shown in FIG. 7, when the piston rod 23 moves greatly in the extending direction (Xa direction), the operation stroke of the piston 37 is transmitted to the sliding member 67 via the rod member 66, and the sliding member The second vertical portion 67c of 67 presses the lower slide member 65B in the left direction (Xa direction).

  Then, the slide member 65B slides in the left direction (Xa direction), and the swinging member 68 rotates clockwise, and the connecting pin 70 is connected via the wire 69 connected to the upper end portion 68c of the swinging member 68. Is pulled out from the holding member 71. As a result, since the holding of the sliding shaft 82 by the holding member 71 is released, the sliding shaft 82 moves in the Xa direction by the spring force of the spring member 84 to press the pressing member 86, and the spool valve 52 via the spring of the coil spring 88. Is moved in the axial direction (X direction). Therefore, the spool valve 52 closes the valve portion 54 and blocks the liquid flow in the liquid passage 29B. As a result, one damping valve 32B is switched to a closed state in which no damping force is generated. Therefore, only the other damping valve 32A is actuated to increase the damping force (resistance force) with respect to the stroke of the piston 37. It is possible to attenuate large vibrations.

  As shown in FIG. 8, when the piston rod 23 moves greatly in the contraction direction (Xb direction), the sliding member 67 connected to the piston rod 23 via the rod member 66 slides to the right. When the operation stroke of the piston 37 is transmitted to the sliding member 67 via the rod member 66, the first vertical portion 67b moves the upper slide member 65A and the lower slide member 65B to the right (Xb direction). Press on. At this time, if a stopper is provided above the rotation center of 65A or on the right side of the slide member 65B so that the swing member 68 does not rotate clockwise on the left side of the slide member 65A, the first vertical portion 67b becomes the swing member. It is possible to eliminate a delay until the connecting pin 70 comes off after coming into contact with 68.

  While the slide member 65A slides in the right direction (Xb direction), the movement of the swing member 68 is transmitted to the connection pin 70 via the wire 69, and the connection pin 70 is pulled out from the holding member 71. As a result, since the holding of the sliding shaft 82 by the holding member 71 is released, the sliding shaft 82 moves in the axial direction by the spring force of the spring member 84 to press the pressing member 86, and the spool valve 52 via the spring of the coil spring 88. Is moved in the axial direction (Xa direction). Therefore, since the spool valve 52 is switched to a state in which the valve portion 54 is closed and the liquid flow in the liquid passage 29B is blocked and the damping force by the damping valve 32B is not generated, the damping force (resistance force) against the stroke of the piston 37 is increased. It becomes possible to attenuate larger vibrations.

  In this embodiment, when a large vibration is input and the operation stroke of the fluid pressure shock absorber 20 exceeds a set value, the connecting pin 70 is pulled out from the holding member 71 and the spool valve 52 blocks the liquid flow in the liquid passage 29B. In order to switch the damping valve 32B to the non-operating state, it is switched to the setting on the higher damping force side of the fluid pressure shock absorber 20 by visually confirming that the connecting pin 70 has been removed from the holding member 71 during maintenance. You can see that from the appearance. Further, when the mode is once switched to the high damping force mode, the holding member 71 is attached with the shaft of the actuator 42 pulled, and the connecting pin 70 is inserted into the insertion hole 71a, whereby the shutoff valve 39 returns to the valve open state. The damping force of the fluid pressure buffer 20 can be returned to the low damping force mode.

  According to this embodiment, the fluid pressure shock absorber 20 can be configured without using components that require power supply such as an electromagnetic valve and an acceleration sensor.

  Thereby, the manufacturing cost of the fluid pressure damper 20 used for the seismic isolation system 30 can be significantly reduced. In addition, since parts that require power supply are not used, maintenance is easier than conventional damping force switching fluid pressure shock absorbers, and the maintenance interval can be greatly extended. Running costs can be reduced.

  In the above-described embodiment, a configuration in which the damping force of the fluid pressure buffer is switched by closing one of the damping valves 32A and 32B that restricts the flow of the working fluid (working oil) such as a hydraulic shock absorber is taken as an example. However, the present invention is not limited to this. For example, the damping force is adjusted by adjusting the throttle of the liquid flow path in which the working fluid moves as the piston 37 moves, or by selectively switching the plurality of liquid flow paths to open or closed. Can be switched.

  In the above embodiment, the hydraulic shock absorber has been described as an example. However, the present invention is not limited to this, and the present invention can of course be applied to a fluid shock absorber using a fluid having other viscosity.

DESCRIPTION OF SYMBOLS 10 Building 12 Foundation 14 Seismic isolation member 20 Fluid pressure buffer 30 Seismic isolation system 23 Piston rod 29A, 29B Fluid passage 30 Check valve 31 Suction valve 32A, 32B Damping valve 36 Cylinder 37 Piston 38 Auxiliary tank 39 Shut-off valve 35 Actuation Fluid (hydraulic oil)
40 Damping force switching mechanism 42 Actuator 50 Damping force switching valve 52 Spool valve 54 Guide portion 56 Energizing member (coil spring)
60 Valve switching mechanism 61 Plate 62 Connection separation mechanism 63 Release mechanism 64A, 64B Slide guide 65A, 65B Slide member 66 Rod member 67 Slide member 67a Horizontal portion 67b First vertical portion 67c Second vertical portion 68 Oscillating member 69 Wire 70 Connecting pin 71 Holding members 71a and 71b Arc-shaped member 71d Insertion hole 80 Housing 82 Slide shaft 84 Spring member 86 Pressing member 88 Coil spring

Claims (5)

A cylinder filled with working fluid;
A piston inserted into the cylinder and defining the inside of the cylinder into two pressure chambers;
A piston rod having one end connected to the piston and the other end extending outward from one end of the cylinder;
A liquid passage filled with the working fluid and flowing the working fluid to and from the pressure chamber;
Damping force generating means for generating a damping force in the working fluid flowing through the liquid passage;
Damping force switching means for switching the damping force generated by the damping force generating means;
A fluid pressure shock absorber comprising:
The damping force switching means is
A damping force switching valve for switching the damping force generating means to a low side or a high side by circulating or blocking the liquid passage;
A valve switching mechanism for switching the damping force switching valve from open to closed,
The valve switching mechanism is
A connection / separation mechanism provided on the damping force switching valve so as to be connectable and separable, wherein the damping force generating means has a low damping force side in a connected state, and the damping force generating means has a high damping force side in a separated state;
Provided between the connection separation mechanism and the piston rod, when the movement amount of the piston rod is small, the connection state of the connection separation mechanism is maintained, and the axial movement amount of the piston rod is equal to or greater than a predetermined value. A fluid pressure shock absorber having a release mechanism that sometimes brings the connection / separation mechanism into a separated state.   2. The fluid pressure shock absorber according to claim 1, wherein the release mechanism causes the connection / separation mechanism to be in a separated state with respect to movement of the piston rod with respect to movement of the predetermined value or more for any movement of the piston rod. The release mechanism is
A rod member for transmitting the operation of the piston rod;
A sliding member that is slidably provided outside the cylinder, is coupled to the rod, and slides in the operating direction of the rod member;
A sliding member that is pressed in the sliding direction when the sliding member moves more than a predetermined distance;
A swinging member that swings in conjunction with the operation of the slide member when an operating range of the sliding member by a relative displacement between the piston and the cylinder is within a predetermined range;
When the operation range due to the relative displacement between the piston and the cylinder is equal to or greater than a predetermined range, the connection separation mechanism is displaced into a separated state by a sliding operation of the sliding member or a swinging operation of the swinging member. The fluid pressure shock absorber according to claim 1 or 2, characterized in that: The connection separation mechanism is
A wire coupled to the rocking member;
A pin connected to the tip of the wire;
A holding member that holds the damping force switching valve in a low damping force mode by inserting the pin,
The release mechanism separates the pin from the holding member and switches the damping force switching valve to a high damping force mode when an operation range due to relative displacement between the piston and the cylinder is equal to or greater than a predetermined range. The fluid pressure shock absorber according to claim 1 or 2. A seismic isolation system comprising a seismic isolation member that supports a building, and a fluid pressure buffer that is installed between the building and the ground and attenuates the vibration input from the ground,
The fluid pressure shock absorber
A cylinder filled with working fluid;
A piston inserted into the cylinder and defining the inside of the cylinder into two pressure chambers;
A piston rod having one end connected to the piston and the other end extending outward from one end of the cylinder;
A liquid passage filled with the working fluid and flowing the working fluid to and from the pressure chamber;
Damping force generating means for generating a damping force in the working fluid flowing through the liquid passage;
Damping force switching means for switching the damping force generated by the damping force generating means;
Have
The damping force switching means is
A damping force switching valve that switches the damping force to a low side or a high side by circulating or blocking the liquid passage of the fluid pressure buffer;
A valve switching mechanism for switching the damping force switching valve from open to closed;
The valve switching mechanism is
A connection separation mechanism that is provided so as to be separable from the damping force switching valve, has a low damping force in the connected state, and has a high damping force by being separated from the damping force switching valve;
Provided between the connection separation mechanism and the piston rod, when the movement amount of the piston rod is small, the connection state of the connection separation mechanism is maintained, and the axial movement amount of the piston rod is equal to or greater than a predetermined value. A seismic isolation system having a release mechanism that sometimes places the connection and separation mechanism in a separated state.

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