Fluid levitation device

Abstract

To provide a levitation type seismic isolator which is conceived based on the above-described technical background, achieves improvement of fluid sealing performance, and can levitate and slide stably while reducing friction.SOLUTION: A fluid levitation device includes: a levitation body which levitates from a base and supports a structure; a seal ring body; and a fluid supply unit. The levitation body includes: a contact part which contacts with the base; a housing part which houses the seal ring body; a fluid layer formation part which forms a fluid layer with the base; a fluid supply passage for supplying the fluid from the fluid supply part to the fluid layer formation part; and a discharge passage for discharging the fluid.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This relates to a fluid flotation device that uses pressurized fluid to levitate an object to be protected while isolating vibrations and has a sealing mechanism that prevents leakage of the supplied pressurized fluid. [Background technology]

[0002] For example, art galleries and museums use seismic isolation devices, a type of vibration suppression device, to prevent damage to collections in the event of an earthquake. Examples of seismic isolation devices include those configured between the ground and a building, or between a foundation such as a floor inside the building and a mounting base such as a platform on which the collections are placed. These devices are installed between the building and the mounting base and float using the pressure of a pressurized fluid, slidably supporting the building or mounting base to isolate vibrations. Multiple floating vessels are used, and uneven loads on the mounted items can be accommodated by changing the pressure in the floating vessels. However, structures that are completely sealed with a membrane, such as air springs, cannot accommodate earthquakes because the amount of horizontal displacement they can accommodate is too small.

[0003] Therefore, various mechanisms have been devised to allow the edges of the sealing membrane of the floating container to slide against the floor surface (Patent Documents 2, 3, 4, and Non-Patent Documents 5 and 6). However, when a membrane is used to seal a gap equal to the floating height, the membrane needs a fixed point on the floating plate, and the membrane necessarily needs to be several times the length of the floating height. This increases the pressure-receiving area and the downward force, so when the membrane comes into contact, a large sliding resistance occurs and vibration is transmitted. Furthermore, the membrane's fixing parts must be thick, making it impossible to minimize the air column height. Because sliding resistance affects the horizontal vibration isolation performance, a structure is used in which fluid leaks to separate the membrane's contact surfaces (Non-Patent Document 5).

[0004] Research is also being conducted into floating vessels that do not use sealing materials (Patent Document 1, and Non-Patent Documents 1-4), but technology is still needed to avoid the large amount of fluid air used. Meanwhile, because the main components of earthquakes exist in the frequency band below 10 Hz, if the floating vessel's fluid volume / effective pressure-receiving area (= air height) is large, it is thought that the vertical support rigidity will decrease, amplifying vertical vibrations or inducing rocking vibrations, resulting in instability. For this reason, technology is needed to minimize the air column height.

[0005] Various types of seismic isolation mechanisms that do not use pressurized fluids have been devised and put into practical use, but these have mechanical sliding parts, and horizontal seismic isolation mechanisms, which stack one-way seismic isolation mechanisms in two layers perpendicular to the XY direction, also include vertical amplification elements, and therefore cannot be said to have desirable performance. In the conventional method of using a membrane as a seal in a fluid-air floating seismic isolation mechanism, there is a trade-off between reducing the membrane's sliding resistance and improving sealing performance, making adjustments difficult. Also, because of the presence of a fixing part that fixes the membrane, the fluid air volume or air column height (volume / effective area) of the floating container cannot be reduced beyond a certain level. As a result, it is not possible to increase vertical rigidity.

[0006] Furthermore, a seismic isolation device has been disclosed in which a ring-shaped sealing body is caused to protrude from the bottom of a support by fluid pressure, thereby preventing the propagation of seismic motion to the building (Patent Document 5). This ring-shaped sealing body is configured so that an on-off valve opens in response to a detection signal during an earthquake, and the pressure of the pressurized fluid presses the sealing body against the sliding plate on the foundation side. However, with this type of support, it is difficult to adjust the amount of fluid flowing into the fluid pressure chamber to insulate it from the foundation, and the fluid leaks out from between the sealing body and the sliding plate, making it difficult to maintain the posture of the support. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2017-187083 A [Patent Document 2] JP 2015-59390 A [Patent Document 3] Japanese Patent Application Laid-Open No. 2011-202769 [Patent Document 4] Utility Model Registration No. 3119675 [Patent Document 5] Japanese Patent Application Publication No. 05-256046 [Non-patent literature]

[0008] [Non-Patent Document 1] Masashi Yasuda, Eiji Sato, Manabu Yamada, Koichi Kajiwara, Masaki Hayatsu, "Development of a 3D Seismic Isolation Device Using a Negative Stiffness Link Mechanism and an Air Levitation Mechanism in Series", Transactions of the Japan Society of Mechanical Engineers, Vol. 83, No. 851 (2017), DOI: 10.1299 / transjsme.17-00057 [Non-patent document 2] Masashi Yasuda, Eiji Sato, Manabu Yamada, Koichi Kajiwara, Masaki Hayatsu, Development of a Horizontally Non-Periodic 3D Seismic Isolation System Using Air Levitation, Transactions of the Japan Society of Mechanical Engineers, Vol. 84, No. 861 (2018), DOI: 10.1299 / transjsme.17-00509 [Non-patent document 3] Manabu Yamada, Koichi Kajiwara, Eiji Sato, Masaki Hayatsu, Hideo Kase, Masashi Yasuda, "Development of a 3D seismic isolation device using air levitation, negative stiffness links, and air dampers," Proceedings of the Dynamics and Design Conference 2018 [Non-patent document 4] Manabu Yamada, Koichi Kajiwara, Eiji Sato, Masaki Hayatsu, Hideo Kase, Masashi Yasuda, "Experimental Verification of Element Behavior in Air-Levitated 3D Seismic Isolation System," Proceedings of the Dynamics and Design Conference 2019 [Non-Patent Document 5] Minagawa K, Fujita S, Tanaka G, Shimosaka H, ​​Floating Type Isolation System Using Earthquake Early Warning, The 15th WCEE, Lisboa, 2012 [Non-patent document 6] http: / / www.airdanshin.jp / Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention was devised based on the above-mentioned technical background, and aims to provide a floating seismic isolation device that has improved sealing performance against fluids and can levitate and glide stably while reducing friction. [Means for solving the problem]

[0010] The present invention provides a fluid flotation device comprising a float that floats from a base and supports a structure, a seal ring body, and a fluid supply unit, wherein the float includes a contact portion that contacts the base, a housing portion that houses the seal ring body, a fluid layer forming portion that forms a fluid layer between the float body and the base, a fluid supply path that supplies fluid from the fluid supply portion to the fluid layer forming portion, and a discharge path that discharges the fluid, the fluid supply path being configured to move the seal ring body housed in the housing portion from a housing position to a protruding position by fluid supplied from the fluid supply path, the discharge path being connected to the fluid supply path so as to discharge the fluid when a predetermined amount of fluid is supplied, and the seal ring body, when moved to the protruding position, prevents fluid in the fluid layer from leaking out through a gap between the base and the float body. By using the fluid flotation device of the present invention, the seal ring body suppresses fluid leakage and allows excess fluid to be discharged through the discharge path, thereby maintaining a stable posture.

[0011] The present invention also provides a fluid flotation device configured to adjust the pressing force of the seal ring body against the base body by the fluid supplied to the fluid layer.

[0012] The present invention also provides a fluid flotation device in which, when the seal ring body is accommodated in the accommodation portion, the seal ring body prevents fluid from flowing out of the discharge path, and when the seal ring body moves to the protruding position, the fluid can be discharged from the discharge path.

[0013] The present invention also provides a fluid levitation device in which the seal ring body has a rigid portion that maintains its ring-shaped structure, and a deformable portion that is located closer to the base than the rigid portion and that seals or prevents the fluid from leaking by coming into contact with the base or by maintaining a predetermined gap with the base.

[0014] The present invention also provides a fluid flotation device in which, at the beginning of fluid supply, the seal ring body abuts against the inner surface of the accommodating portion, forming a fluid obstruction portion that obstructs the fluid from being discharged from the fluid supply path to the discharge path. [Effects of the Invention]

[0015] By using the fluid levitation device of the present invention, the sealing performance for fluids is improved, and a floating type seismic isolation device is obtained that can levitate stably while adjusting the frictional force against horizontal movement. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a partially enlarged cross-sectional view of one embodiment of a fluid levitation device of the present invention in a state (initial state) before fluid is introduced. [Figure 2] FIG. 2 is an enlarged partial cross-section of the fluid flotation device of FIG. 1 during flotation. [Figure 3] Figure 3(A) is a partial cross-sectional view illustrating the flow path of the fluid levitation device of Figure 1. Figure 3(B) is a partial cross-sectional view illustrating the flow path of the fluid levitation device of Figure 2. [Figure 4] FIG. 4 is a diagram illustrating the shape of the lower surface of the seal ring body 3. As shown in FIG. [Figure 5] FIG. 5 is a schematic perspective view of the fluid levitation device 1 of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] The fluid levitation device of the present invention will be described below with reference to the drawings. Fig. 1 is an embodiment of the present invention, and is a partially enlarged cross-sectional view of the fluid levitation device 1 in a state (initial state) before fluid is introduced. As shown in Fig. 1, the fluid levitation device 1 comprises a float 2, a seal ring body 3, and a fluid supply unit 4. The float 2 forms a fluid layer L with the fluid supplied from the fluid supply unit 4, and floats from a base 5. In this embodiment, the float 2 is placed on a surface S of a base 5 provided on a foundation, and is movable relative to the surface S in a direction parallel to it while floating. In the fluid levitation device 1, air is used as the fluid.

[0018] As shown in FIG. 1 , the float 2 includes a contact portion 6 that contacts the base 5, a housing portion 7 that houses the seal ring body 3, and a fluid layer forming portion 8. The fluid layer forming portion 8 is provided in a portion of the float 2 facing the base 5, and forms a fluid layer L between the surface of the base 5 facing the fluid layer forming portion 8, thereby generating buoyancy. In this embodiment, the fluid layer forming portion 8 is formed as a surface parallel to the surface of the base 5, is not in contact with the surface of the base 5, and is formed as the bottom surface of the center of the float 2. The fluid layer L formed between the fluid layer forming portion 8 and the base 5 is interposed between the base 5 and the float 2 and exhibits blocking performance against vibration propagation from the foundation, such as during an earthquake. The thickness of the fluid layer L can be adjusted by adjusting the degree of protrusion of the contact portion 6 toward the base, and the natural frequency can be appropriately set based on the vertical spring characteristics of the fluid layer L. Therefore, the fluid levitation device 1 can be highly effective in isolating horizontal vibrations from the base body 5, such as those caused by earthquakes, without amplifying vertical vibrations. The levitation body 2 can be provided with an adjustment part that adjusts the degree of protrusion of the contact part 6 in order to adjust the fluid layer L, and in this embodiment, the adjustment part corresponds to the gap adjustment part 13 described below, more specifically a shim plate (a plate having a predetermined thickness, such as a thin plate).

[0019] The contact portion 6 is provided on the base side of the float 2 and contacts the base 5. The contact portion 6 is provided on the float 2 so as to protrude further toward the base than the fluid layer forming portion 8. Therefore, when the contact portion 6 comes into contact with the base 5, a fluid layer L can be formed between the smooth surface of the base 5 and the fluid layer forming portion 8. The contact portion 6 only needs to contact the base 5 to form a predetermined fluid layer L between the fluid layer forming portion 8 and the base 5, and as described above, the degree of protrusion from the float 2 can be adjusted. In this embodiment, the contact portion 6 is provided on the outer periphery of the float 2 and is provided in a ring shape. By providing the contact portion 6 in a ring shape, the float 2 can be stably placed on the base 5 and fluid outflow from the fluid layer L can be suppressed. The contact portion 6 can be formed by attaching a ring-shaped member to the main body 21 of the float, and the degree of protrusion can be adjusted by providing a mechanism for adjusting the gap between the contact portion 6 and the main body 21 of the float (for example, by interposing gap screws or shim plates at three or more points), and at the same time, a discharge path as described below can be formed.

[0020] The seal ring body 3 is provided relative to the float body 2 so as to prevent the fluid in the fluid layer L from leaking outward. The seal ring body 3 is provided so as to surround the fluid layer L at least when the float body 2 is floating, and prevents the fluid in the fluid layer L from leaking outward. Because the fluid in the fluid layer L is prevented from leaking outward, the fluid layer L can maintain a predetermined thickness. The seal ring body 3 need only surround the fluid layer L at least when the float body 2 is floating, and may be a sealing material in which a deformable portion 32 and a rigid portion 31, which will be described later, are integrated, and the ring does not need to be circular, and the shape of the contact portion is not limited.

[0021] Before fluid flows into the float 2, the seal ring body 3 is accommodated in a storage section 7 provided in the float 2. When the fluid flows in, the seal ring body 3 moves from the storage section 7 and protrudes toward the base body relative to the float 2. The seal ring body 3 is configured to protrude in response to the inflow of fluid. The seal ring body 3 can transition between a stored position in the storage section 7 as shown in FIG. 1 and a protruding position protruding toward the base body as shown in FIG. 2. The storage section 7 is configured so that the seal ring body 3 can move between the stored position and the protruding position. The protruding position is a position for forming a predetermined fluid layer L, and the desired thickness of the fluid layer L can be obtained by the fluid whose outflow is suppressed by the seal ring body 3. The storage position is not limited as long as the seal ring body 3 does not hinder the stable installation of the fluid flotation device on the base body 5 during steady-state conditions, such as before an earthquake.

[0022] As shown in FIG. 1 , the accommodating portion 7 has an accommodating space for accommodating the seal ring body 3. In this embodiment, an annular space corresponding to the annular seal ring body 3 is formed by the inner wall of the accommodating portion 7. The accommodating portion 7 is not particularly limited as long as it allows the seal ring body 3 to move to the protruding position. However, it is preferable that a gap be provided between the outer or inner periphery of the seal ring body 3 and the corresponding inner wall of the accommodating portion 7 so as not to hinder the movement of the seal ring body 3. In this embodiment, the accommodating portion 7 may have an inlet through which a fluid flows in and an outlet through which the seal ring body 3 can protrude, as described below. The accommodating portion 7 may also be provided with a fall-off prevention portion (not shown) that prevents the seal ring body 3 from protruding too far from the accommodating portion 7 and falling off.

[0023] The fluid supply path 9 is a flow path for guiding the fluid supplied from the fluid supply unit 4 attached to the floating body 2 to the space between the fluid layer forming unit 8 and the base 5, and the shape of the flow path is not limited to a tubular or gap shape. In this embodiment, the fluid supply path 9 includes a first supply path 91 which is a flow path from the fluid supply unit 4 to the storage unit 7, and a second supply path 92 which is formed by the inner wall of the storage unit 7 and the outer surface of the seal ring body 2. In this embodiment, the fluid supply path 9 also uses the space between the seal ring body 3 and the base 5 as a flow path. The fluid which flows from the second supply path 92 into the space between the seal ring body 3 and the base 5 is guided to the space between the fluid layer forming unit 8 and the base 5.

[0024] In this embodiment, as shown in FIG. 3(A), a fluid sent from a fluid supply source (not shown), such as a compressor, via piping to the fluid supply unit 4 moves via a first supply path 91 to a second supply path 92, and then passes through the second supply path 92 to be sent to the space between the seal ring body 3 and the base 5, thereby forming a fluid layer L. As the fluid moves from the first supply path 91 to the second supply path 92, it is sent to the accommodation unit 7. The fluid supply path 9 uses a part of the accommodation unit 7, but it may also be formed as a flow path that directly connects the fluid supply unit 4 to the space between the fluid layer forming unit 8 and the base 5. In this case, a fluid supply path can be provided that branches off from the fluid supply path 4 and supplies the fluid that moves the seal ring body 3 to the accommodation unit 7.

[0025] Furthermore, in this embodiment, before the floatation body 2 floats, as shown in FIG. 3(A), the inner wall surface of the storage section 7 and the outer surface of the seal ring body 3 come into contact with each other to form a fluid inhibiting section 10. The fluid inhibiting section 10 blocks communication of the gap formed by the upper surface of the seal ring body 3 and the ceiling surface of the storage section 7 with the discharge path 11, inhibiting the fluid from flowing into the discharge path 11. The fluid inhibiting section 10 inhibits the fluid from flowing into the discharge path 11 and allows the fluid to flow into the space between the fluid layer forming section 8 and the base body 5. Depending on the viscosity of the fluid, the inner wall surface of the storage section 7 and the outer surface of the seal ring body 3 may be close to each other as long as the fluid can be inhibited from flowing into the discharge path 11 to the extent that the fluid can flow in.

[0026] In this embodiment, the seal ring body 3 is accommodated in the float body 2 so that the upper surface of the seal ring body 3 is subjected to the pressure of the fluid supplied from the fluid supply unit 4. The seal ring body 3 is pressed toward the base body 5, and fluid fills the space between the fluid layer forming unit 8 and the base body 5, causing the seal ring body 3 to move to the protruding position, and the float body 2 to float as shown in FIG. 3(B). When the seal ring body 3 moves to the protruding position, it moves relative to the float body 2. Therefore, the inner wall surface of the accommodation unit 7 and the outer surface of the seal ring body 3, which were in contact as the fluid obstruction unit 10, are separated from each other to form a discharge communication passage 12 communicating with the discharge passage 11. By forming this discharge communication passage 12, excess fluid supplied from the fluid supply passage 4 is discharged to the outside via the discharge communication passage 12 and the discharge passage 11. This prevents excess fluid from flowing into the fluid layer L, facilitating stable floating of the float body 2. Both surfaces of this fluid obstruction portion are inclined and in contact with the buoyancy axis at an angle. The discharge volume can be controlled by changing this angle. The discharge passage 11 can be any flow path that allows the fluid supplied from the fluid supply portion 4 to be discharged appropriately. A predetermined flow path can be set by the gap adjustment portion 13 formed by interposing a gap adjustment member such as a shim plate. In this case, the gap adjustment portion 13 is used to ensure the flow rate of the discharge passage 11 and to adjust the protrusion amount of the contact portion 6 on the base side of the float 2. Note that the discharge passage 11 may have any shape as long as it is configured so that the exhaust flow rate increases approximately in proportion to the protrusion amount (length along the buoyancy axis) when the seal ring body 3 is moved to the protruding position. The cross-sectional shape of the discharge passage 11 may be, for example, a round hole, an elongated hole, or a rectangular hole.

[0027] The seal ring body 3 prevents the outflow of fluid from the fluid layer L. Therefore, in order to reduce the thickness of the fluid layer L, it is preferable that the seal ring body 3 contacts the surface of the base body so as not to create a gap between the base body surface and the seal ring body 3. In this embodiment, the seal ring body 3 is composed of a rigid portion 31 and a deformable portion 32. The deformable portion 32 is provided on the base body side of the seal ring body 3 and contacts the base body. As shown in the figure, the deformable portion 32 is in approximate point contact with the base body 5, so that vibrations from the base body 5 are not easily transmitted to the float body 2 via the seal ring body 3, and the float body 2 can easily slide on the base body 5.

[0028] The deformable portion 32 of the seal ring body 3 is preferably made of a deformable material such as soft resin so that it can easily follow the surface shape of the base body 5 to reduce the gap with the surface of the base body. It may also be made of a slippery resin material such as PTFE (polytetrafluoroethylene) to allow the float body 2 to slide easily on the base body 5, or a felt ring that can be used as a flexible dustproof or oil supply packing. In this embodiment, the rigid portion 31 constituting the seal ring body 3 has a recess that opens downward relative to the float axis in a cross section cut parallel to the float axis, and the deformable portion 32 is housed within the recess. The rigid portion 31 has the rigidity necessary to maintain the shape of the seal ring body 3, so it is preferably made of a hard material such as metal.

[0029] Furthermore, in the fluid levitation device 1 of the present invention, the seal ring body 3 is configured to adjust the pressing force applied to the seal ring body 3 by the fluid supplied to the fluid layer L against the base body 5. The configuration for achieving this function will be described below. Specifically, the rigid portion 31 of the seal ring body 3 has a concave cross-sectional shape that opens downward in a cross section parallel to the levitation axis direction, and has an end face at its end on the base body side that faces the surface of the base body 5 with a gap therebetween. Because the rigid portion 31 has such an end face that leaves a gap with respect to the surface of the base body 5 and faces away from it, even if the rigid portion 31 is pressed toward the base body by the fluid from the fluid supply path 9, the fluid that has entered between the surface of the base body 5 and the opposing end face of the rigid portion 31 applies a force to the end face of the rigid portion 31 in the upward direction in the levitation axis direction. As a result, the force (pressing down force) acting downward in the levitation axis direction on the upper surface of the rigid portion 31 by the fluid supplied from the first supply path and the force (push up force) acting upward in the levitation axis direction on the end face of the rigid portion 31 by the fluid that has entered between the surface of the base 5 and the end face of the rigid portion 31 facing it cancel out the push down force, and the pressure pressing the rigid portion 31 toward the base is adjusted. In other words, this makes it possible to adjust the contact friction force against horizontal movement. For this reason, it is preferable that the seal ring body 3 has an end face on the base side that is spaced apart from and faces the base 5.

[0030] In order to have an end surface that directly exerts such a pressing force, the underside of the seal ring body 3 (i.e., the surface formed by the surface of the rigid portion 31 and the surface of the deformable portion 32) may have a shape in which the entire surface bulges downward as shown in Fig. 4(a), or a shape in which a portion (for example, the outer periphery) bulges downward as shown in Fig. 4(b), or a shape in which one or more circular protrusions are formed as shown in Fig. 4(c). Note that the shape of the underside of the seal ring body 3 is not limited to this, and it may also have a flat shape as a whole.

[0031] As shown in FIG. 5, the fluid levitation device 1 of the present invention is disk-shaped, with a portion of the target aircraft placed on the central mounting section 14. For example, the fluid levitation device 1 of the present invention can be placed at the four corners of the aircraft to stably levitate the aircraft. In the above embodiment, the base 5 is mounted on a foundation, but it may also be mounted on other equipment instead of a foundation. The present invention can be used in vibration isolation technology to protect buildings and machinery from earthquakes and vibrations. Note that the fluid levitation device 1 is not limited to a disk shape, and may be rectangular when viewed from the levitation axis direction, for example. [Explanation of symbols]

[0032] 1. Fluid flotation device 2 Floating body 3 Seal ring body 4 Fluid supply section 5 Base 6 Contact area 7 Storage section 8 Fluid layer forming part 9 Fluid supply path 10 Fluid obstruction section 11 Exhaust channel 12 Discharge communication path 13 Gap adjustment part 14 Mounting section 21 Main body of the floating body 31 Rigid part 32 Transformable part 91 First supply route 92 Second supply route L Air layer S: Surface of the substrate

Claims

1. A fluid flotation device comprising a float that floats from a base and supports a structure, a seal ring body, and a fluid supply unit, The buoyant body is a contact portion that contacts the base body, a housing portion that houses the seal ring body, a fluid layer forming portion that forms a fluid layer between the contact portion and the base body, a fluid supply path that supplies a fluid from the fluid supply portion to the fluid layer forming portion, and a discharge path that discharges the fluid, The fluid supply path is the seal ring body accommodated in the accommodation portion is moved from an accommodation position to a protruding position by the fluid supplied from the fluid supply path, the discharge path communicates with the fluid supply path so as to discharge the fluid when the fluid is supplied in an amount equal to or greater than a predetermined amount; When the seal ring body is moved to the protruding position, the seal ring body prevents the fluid in the fluid layer from flowing out through a gap between the base body and the float body. Fluid flotation device.

2. 2. The fluid levitation device according to claim 1, wherein the seal ring body is configured to adjust the pressing force of the seal ring body against the base body by the fluid supplied to the fluid layer.

3. A fluid flotation device as described in claim 1, wherein when the seal ring body is accommodated in the accommodation portion, the seal ring body prevents fluid from flowing out of the discharge path, and when the seal ring body moves to the protruding position, fluid can be discharged from the discharge path.

4. The seal ring body is a rigid portion that maintains the ring-shaped structure; a deformable portion that is provided closer to the base than the rigid portion and that seals or prevents the outflow of the fluid by coming into contact with the base or by setting a predetermined gap between the deformable portion and the base; 10. The fluid flotation device of claim 1, comprising:

5. A fluid levitation device as described in claim 3, wherein the seal ring body abuts against the inner surface of the accommodating portion at the beginning of fluid supply, forming a fluid obstruction portion that obstructs fluid from being discharged from the fluid supply path to the discharge path.

Images