JP7810566B2 - Jack equipment and floor structure - Google Patents

Description

The present invention relates to a jack device and a floor structure.

A construction method is sometimes used in which a building structure is raised and lowered using a jacking device and then fixed in place. When seismically isolating an existing building, a known method involves cutting the building and foundation apart, lifting the building using a jacking device at the installation height of the seismic isolation layer, and fixing it in place. After installing a seismic isolation device between the foundation and building, the gap that has formed between the foundation and building is filled with grout. With this method, the weight of the building may increase as the amount of items stored in the building increases after the seismic isolation device is installed, or the weight of the building may increase due to an extension to the building, which may increase the load acting on the jacking device after fixing it in place.

Patent Document 1 also describes a floor structure in which the floor is supported by spring members and configured as a floating floor. In floor structures where the floor can be raised and lowered, such as the floating floor of a live music hall or a stage, a jack device is used to secure the floor. In such floor structures, if the load on the floor increases due to people, stage equipment, stage props, etc. after the floor is secured, the load acting on the jack device also increases.

Generally, the load capacity of a jack device is considered to be the same whether it is jacked up or fixed. Therefore, if the load of the object increases after the jack device is fixed, it is necessary to use a jack device with a load capacity that can accommodate the increased load.

When the floor section in the above-mentioned floor structure is secured with a jack device, the floor section is supported by spring members before securing, so no load is applied to the jack device. Furthermore, when lifting the floor section, the load-bearing capacity of the jack device is smaller than when no spring members are present, because the lifting load is simply the spring value x lifting height, since the floor section is supported by spring members. After the floor section is secured in such a floor structure, the jack device is subjected to the increased load on the floor, so when selecting a jack device, it is sufficient to ensure that its load-bearing capacity exceeds the load after securing.

Large live concert halls with floors supported by spring members are sometimes used for a variety of events other than live performances. For example, stepped flooring may be installed at the rear of the floor when a classical concert is held, or heavy objects may be placed locally on the floor at events such as motor shows. In such applications, there is no vertical vibration as occurs during a live concert, so there is no risk of vibration problems, and it is easier to use a floating floor that is fixed horizontally rather than spring-supported.

Japanese Patent Application Laid-Open No. 2019-178555 Japanese Patent Application Publication No. 6-48685

In buildings with floating floors, the floors are secured with jacking devices to prevent sinking before step floors or heavy objects are placed on them or before spectators enter. These jacking devices abut against and secure the floating floor, so the jacking reaction force is nearly zero when installed, and the increased live load on the floating floor after securing is borne by the jacking devices. These jacking devices are selected so that their load-bearing capacity exceeds the increased load on the floor after securing.

Therefore, it is reasonable for a jack device for securing a floating floor to be configured so that its load-bearing capacity after securing is higher than its lifting capacity. For example, Patent Document 2 describes a jack device for raising and lowering a structure. The jack device described in Patent Document 2 does not have a configuration for securing the placed object, and does not increase the load-bearing capacity after securing compared to the load-bearing capacity during lifting.

The objective of the present invention is to provide a jack device and floor structure that can increase the load-bearing capacity after fixing compared to the load-bearing capacity during lifting.

To achieve the above object, one aspect of the present invention is a jack device comprising: a first wedge member having a first inclined surface; a second wedge member having a second inclined surface; a lower support portion on which the first wedge member and the second wedge member are placed so that they can move toward or away from each other with the first inclined surface and the second inclined surface facing each other; a left-right screw that connects the first wedge member and the second wedge member and moves the first wedge member and the second wedge member in the axial direction based on rotation; and an upper support portion formed with a third inclined surface that contacts the first inclined surface and a fourth inclined surface that contacts the second inclined surface, and which moves up and down based on movement of the first wedge member and the second wedge member.

In the present invention, the first and second wedge members placed on the lower support section are connected by left and right screws using the above-mentioned configuration, and the upper support section is supported by the first and second wedge members. This reduces the horizontal load generated by the first and second wedge members, and increases the vertical load capacity of the jack device when fixed compared to the load applied by the left and right screws during lifting.

The present invention may also provide a jack device in which the lower support portion has a first groove formed therein that allows the first wedge member and the second wedge member to move axially.

With the above configuration, the present invention allows the first wedge member and second wedge member to move along the first groove on the lower support part based on the rotation of the left and right screws, thereby creating a jack that lifts the upper support part.

The present invention may also provide a jack device in which a second groove is formed in the first inclined surface or the third inclined surface, allowing the first wedge member to move in the axial direction.

With the above configuration, the present invention allows the first wedge member to move along the movement direction relative to the upper support part.

The present invention may also provide a jack device in which a third groove is formed in the second inclined surface or the fourth inclined surface, allowing the second wedge member to move in the axial direction.

With the above configuration, the present invention allows the twelfth wedge member to move along the movement direction relative to the upper support part.

The present invention may also be a jack device equipped with a drive unit that rotates the left-right screw.

With the above configuration, the present invention can provide a jack structure in which the drive unit rotates the left-right screw in a predetermined rotational direction, moving the first wedge member and the second wedge member in a direction toward or away from each other, and the upper support unit moves up and down in response to the movement of the first wedge member and the second wedge member.

The present invention may also be a floor structure comprising a floor section supported by the upper support section and the above-mentioned jack device.

With the above configuration, the present invention can realize a floor structure in which the floor section can be lifted to any desired height in the vertical direction using a jack device and then fixed in place.

The present invention may also include one or more elastic members provided between the floor portion and the upper support portion, and a restricting portion that restricts upward movement of the floor portion relative to the upper support portion and compresses the elastic members to generate a preload on the elastic members.

With the above-mentioned configuration, the present invention can constantly prevent vertical displacement of floor section B and keep it in place, while preventing the generation of excessive reaction forces during vertical earthquakes, etc.

According to the present invention, the load-bearing capacity after fixing can be increased compared to the load-bearing capacity during lifting.

1 is a front view showing a configuration of a jack device according to an embodiment of the present invention. FIG. 2 is a right side view showing the configuration of the jack device. FIG. 2 is a left side view showing the configuration of the jack device. 10A and 10B are diagrams illustrating the operation of the jack device. 10A and 10B are diagrams illustrating forces acting on a first wedge member and a second wedge member. FIG. 10 is a right side view showing the configuration of a lower support part according to a modified example. FIG. 10 is a front view showing the configuration of a floor structure according to a modified example. FIG. 10 is a diagram showing the relationship between a load applied to a floor structure according to a modified example and the resulting displacement.

Embodiments of a jack device and floor structure according to the present invention will be described below with reference to the drawings. In the following description, mutually perpendicular X, Y, and Z axes are set. The Z axis is a direction along the vertical direction. The X axis direction will be referred to as the longitudinal direction, axial direction, etc., as appropriate, and the Y axis direction will be referred to as the transverse direction, width direction, etc., as appropriate. Furthermore, the -X axis direction will be referred to as one axial side, and the +X axis direction will be referred to as the other axial side, etc.

As shown in Figures 1 to 3, the jack device 1 comprises a lower support part 2 provided on the installation object E, a pair of first and second wedge members 3 and 4 provided on the lower support part 2, left and right screws 5 connecting the pair of first and second wedge members 3 and 4, and an upper support part 6 provided on the pair of first and second wedge members 3 and 4.

The lower support part 2 is formed, for example, from a steel material into a rectangular plate-like body. The lower support part 2 is fixed onto the installation object E, with its longitudinal direction (axial direction) running along the X-axis direction. A first groove 2M is formed on the upper surface of the lower support part 2 along the longitudinal direction. The first groove 2M is formed, for example, by recessing downward from the upper surface side. A first wedge member 3 and a second wedge member 4 are placed in the first groove 2M. When viewed along the X-axis direction, the first groove 2M is shaped so that the bottom surfaces of the first wedge member 3 and the second wedge member 4 engage with each other. The first groove 2M is formed so that the first wedge member 3 and the second wedge member 4 can move along the longitudinal direction, as described below.

The first wedge member 3 is disposed, for example, on one axial side of the lower support part 2. The first wedge member 3 is formed, for example, in the shape of a block using steel. The first wedge member 3 is formed with a width in the width direction (Y-axis direction) that allows it to engage with the first groove 2M. The upper surface of the first wedge member 3 is formed with a first inclined surface 3S that slopes downward toward the other axial side, for example. The inclination angle of the first inclined surface 3S is θ. A first through hole 3H that penetrates the first wedge member 3 along the axial direction is formed inside the first wedge member 3.

The first through hole 3H has, for example, a right-handed female thread formed therein. As described below, one axial side of a right-handed screw 5 is threaded into the first through hole 3H. Instead of providing a female thread in the first through hole 3H, a nut fixed to the first wedge member 3 concentrically with the first through hole 3H may be threaded onto one axial side of the right-handed screw 5 inserted into the first through hole 3H. In this case, the first through hole 3H may be a slit. A second wedge member 4 is arranged opposite the first wedge member 3.

The second wedge member 4 is disposed, for example, on the other axial side of the lower support part 2. The second wedge member 4 is formed, for example, in the shape of a block using steel. The second wedge member 4 is formed with a width in the width direction (Y-axis direction) that allows it to engage with the first groove 2M. A second inclined surface 4S that slopes downward toward one axial side is formed on the upper surface of the second wedge member 4. The inclination angle of the second inclined surface 4S is θ. A second through hole 4H that penetrates the second wedge member 4 along the axial direction is formed inside the second wedge member 4.

The second through hole 4H has, for example, a left-handed female thread formed therein. As described below, the other axial side of the right-handed screw 5 is threaded into the second through hole 4H. Instead of providing a female thread in the second through hole 4H, a nut fixed to the second wedge member 4 concentrically with the second through hole 4H may be threaded onto the other axial side of the right-handed screw 5 inserted into the second through hole 4H. In this case, the second through hole 4H may be a slit.

The bi-directional screw 5 is formed in a rod shape using, for example, steel. The axial direction of the bi-directional screw 5 is aligned along the X-axis direction. A pair of tubular members 5C are inserted into the center of the bi-directional screw 5 and are constrained from moving axially relative to the screw. The tubular members 5C may be formed integrally with the bi-directional screw 5. A right-handed male thread portion 5A is formed on one axial side of the center of the bi-directional screw 5. The male thread portion 5A is threaded into a first through-hole 3H provided in the first wedge member 3. A left-handed male thread portion 5B is formed on the other axial side of the center of the bi-directional screw 5. The pitch of the male thread portion 5B is formed to be equal to the pitch of the male thread portion 5A. The male thread portion 5B is threaded into a second through-hole 4H provided in the second wedge member 4.

A drive unit 7 that rotates the screw is provided at the other axial end of the male thread portion 5B. The drive unit 7 is fixed, for example, to the lower support portion 2. The drive unit 7 includes, for example, a motor and a reducer. The reducer reduces the rotation of the motor's output shaft and increases the rotational torque for output. The screw 5 is driven to rotate by the drive unit 7, and the first wedge member 3 and second wedge member 4 move along the axial direction based on the rotation of the screw 5.

By changing the rotational output direction of the drive unit 7, the first wedge member 3 and the second wedge member 4, whose first inclined surface 3S and second inclined surface 4S face each other, move toward or away from each other on the lower support unit 2. A handle (not shown) for manual rotation or a bearing (not shown) for rotatably supporting the screw may be provided at one axial end of the male threaded portion 5A. The first wedge member 3 and the second wedge member 4 support the upper support unit 6.

The upper support portion 6 is formed in the shape of a block using, for example, steel. The upper support portion 6 has a third inclined surface 6A that contacts the first inclined surface 3S and a fourth inclined surface 6B that contacts the second inclined surface 4S.

The third inclined surface 6A is formed from the center of the underside of the upper support part 6 to one axial side. The inclination angle of the third inclined surface 6A is θ. The third inclined surface 6A is formed so as to slope upward from the center of the underside of the upper support part 6 to one axial side. The third inclined surface 6A is formed to have approximately the same length as the male thread portion 5A of the left-right screw 5.

The fourth inclined surface 6B is formed from the center of the underside of the upper support part 6 to the other axial direction. The inclination angle of the fourth inclined surface 6B is θ. The fourth inclined surface 6B is formed so as to slope upward from the center of the underside of the upper support part 6 to the other axial direction. The fourth inclined surface 6B is formed to have approximately the same length as the male thread portion 5B of the left-right screw 5.

With the above configuration, the underside of the upper support portion 6 is formed to protrude downward when viewed in the Y-axis direction. A downward-protruding protrusion 6T is formed in the center of the underside of the upper support portion 6. A slit hole 6H with an inverted U-shaped cross section is formed in the axial direction in the protrusion 6T. The width of the slit hole 6H is slightly larger than the outer diameter of the screw and smaller than the diameter of the tubular member 5C. The slit hole 6H may be an elongated hole extending in the vertical direction. The center of the screw 5 is inserted into the slit hole 6H. A pair of tubular members 5C is disposed on one axial side surface and the other axial side surface of the protrusion 6T. With the above configuration, the protrusion 6T axially supports the screw 5 at its center so that it can rotate freely, while its axial movement is restricted by the pair of tubular members 5C. As described below, the protrusion 6T is guided by the slit hole 6H and can move up and down relative to the center of the screw 5. The protrusion 6T functions to position the first wedge member 3 and the second wedge member 4 symmetrically along the axial direction relative to the center of the underside of the upper support part 6.

With the above configuration, when the left-right screw 5 is rotated, the first wedge member 3 and the second wedge member 4 move axially on the first groove 2M of the lower support 2. Based on the movement of the first wedge member 3 and the second wedge member 4, the upper support 6 moves vertically as the protrusion 6T is restricted in its axial movement by a pair of tubular members 5C and is guided vertically by the slit hole 6H provided in the protrusion 6T. The upper surface 6F of the upper support 6 is formed as a flat surface extending horizontally (X-axis direction). The floor B of the structure is supported on the upper surface 6F of the upper support 6. The floor B of the structure may be supported on the upper surface 6F of the upper support 6 via a steel material or the like. The floor B can move vertically in conjunction with the upper support 6. This forms a floor structure comprising the jack device 1 and the floor B. The floor B is supported, for example, by one or more jack devices 1. One or more drive units 7 of one or more jack devices 1 are controlled in conjunction with each other so that the floor B moves up and down horizontally.

For example, a second groove may be formed on the first inclined surface 3S, allowing the first wedge member 3 to move in the axial direction. A guide portion that engages with the second groove may be formed on the third inclined surface 6A. The guide portion is guided by the second groove, preventing the upper support portion 6 from rotating around the Z axis when the first wedge member 3 moves, and allowing the upper support portion 6 to move in the axial direction. Alternatively, the second groove may be formed on the third inclined surface 6A side, and the guide portion may be formed on the first inclined surface 3S side. In other words, the second groove may be formed on either the first inclined surface 3S or the third inclined surface 6A.

For example, a third groove may be formed on the second inclined surface 4S, allowing the second wedge member 4 to move in the axial direction. A guide portion that engages with the third groove may be formed on the fourth inclined surface 6B. The guide portion is guided by the third groove, preventing the upper support portion 6 from rotating around the Z axis when the second wedge member 4 moves, and allowing the upper support portion 6 to move in the axial direction. Alternatively, the third groove may be formed on the fourth inclined surface 6B side, and the guide portion may be formed on the second inclined surface 4S side. In other words, the second groove may be formed on either the second inclined surface 4S or the fourth inclined surface 6B.

As shown in Figure 4, when the drive unit 7 is driven and the screw 5 is rotated in a predetermined direction, the first wedge member 3 and the second wedge member 4 move toward each other along the axial direction (see Figure 4(A)). The center of the screw 5 is rotatably supported by the protrusion 6T of the upper support unit 6, so the first wedge member 3 and the second wedge member 4 move by the same amount while maintaining symmetrical positions centered on the protrusion 6T. If the load applied to the upper surface 6F of the upper support unit 6 is not eccentric, the load acts evenly on the first wedge member 3 and the second wedge member 4. When the first wedge member 3 and the second wedge member 4 approach each other, the protrusion 6T of the upper support unit 6 is restricted from moving in the axial direction by the pair of tubular members 5C and is guided upward by the slit hole 6H provided in the protrusion 6T, causing the upper support unit 6 to rise upward (see Figure 4(B)). When the rotation of the screw 5 is stopped, the upper support part 6 is fixed at the height it was at after it was raised. If the screw 5 is rotated in the opposite direction to the specified rotation direction after the upper support part 6 has been raised, when the first wedge member 3 and the second wedge member 4 separate, the upper support part 6's protrusions 6T are restricted from axial movement by the pair of tubular members 5C, and are guided downward by the slit holes 6H provided in the protrusions 6T, causing them to descend downward.

As shown in Figure 5, the inclination angle of the first inclined surface 3S and the second inclined surface 4S is θ, so when the first wedge member 3 or the second wedge member 4 moves horizontally in the direction x along the X-axis, the upper support portion 6 moves vertically by x tan θ. If the load acting on the first wedge member 3 or the second wedge member 4 via the upper support portion 6 is W (the sum of the upper support portion 6 and the live load), the force acting on the first wedge member 3 or the second wedge member 4 is expressed as follows, where μ is the coefficient of friction between the first wedge member 3 or the second wedge member 4 and the upper support portion 6 and the lower support portion 2, and F is the force acting on the first wedge member 3 or the second wedge member 4 from the left-right screw 5:

Vertical force acting on the wedge of the first wedge member 3 or the second wedge member 4: W/2
Horizontal force generated by inclination angle θ: (Wtanθ)/2
Horizontal component of the friction force between the first wedge member 3 or the second wedge member 4 and the upper support portion 6: μW/2
Friction force between the first wedge member 3 or the second wedge member 4 and the lower support portion 2: μW/2
Horizontal force from the right and left screws 5 screwed into the first wedge member 3 and the second wedge member 4: F

From the above relationship, the force _F1 acting on the left-right screw 5 when the first wedge member 3 and the second wedge member 4 are pulled together to lift the upper support portion 6 is expressed by the following equation (1).

Furthermore, the force _F2 acting on the left-right screw 5 when the first wedge member 3 and the second wedge member 4 are separated and the upper support portion 6 is lowered is expressed by the following equation (2).

If 2μ - tan θ < 0, then without the left-right screws 5, the first wedge member 3 and second wedge member 4 would slip apart, making it impossible for the upper support part 6 to support the load. Since the coefficient of friction between steel materials is μ≧0.2, if tan θ≦2μ≦0.4, then even without screws, the first wedge member 3 and second wedge member 4 can be held in position simply by the friction generated between the upper support part 6 and lower support part 2, regardless of the magnitude of the load W. (This corresponds to θ≦21.8°).

The left-right screw 5 rotates due to the torque T in the rotational direction output from the drive unit 7. The axial force F generated in the male thread portion 5A threaded into the female thread portion of the first through hole 3H and the male thread portion 5B threaded into the female thread portion of the second through hole 4H is expressed by the following equation (3), assuming that the pitch p of the male thread portions 5A and 5B and the thread efficiency is 1.0 (ignoring friction loss), since the torque T, including the drive unit 7, is threaded into the female thread portions at two locations.

Furthermore, the vertical load W ₁ (jack lifting capacity) that can be lifted when raising the upper support portion 6 is expressed by the following equation (4).

Because the vertical load _W2 that can be lifted when the jack is lowered is greater than _W1 , the jack strength is determined based on _W1 . For example, when μ = 0.2 and tan θ = 0.25, _W1 = 3.08 F, and the jack lifting capacity is three times the axial force of the left and right screws 5. If the coefficient of friction is reduced to μ = 0.1 and tan θ = 0.2, _W1 = 5.0 F, which is five times the axial force of the left and right screws 5. A typical screw jack supports the load with the screw axial force. In comparison, with the jack device 1, it can be seen that when the same screw is used, a lifting capacity (load resistance) several times greater than that of a screw jack can be obtained.

The force F ₀ generated in the left and right screws 5 when an object is lifted and fixed by the jack device 1 is expressed by the following equation (5) based on the condition that the upper support part 6 does not descend.

Since the coefficient of friction between typical steel materials is μ≧0.2, when the wedge slope tanθ≦0.4, _F0 = 0. Since it is not realistic to form such a steep slope based on the first inclined surface 3S and the second inclined surface 4S, the first wedge member 3 and the second wedge member 4 do not usually move due to friction alone. If low-friction treatment is applied to the top and bottom of the first wedge member 3 and the second wedge member 4, the coefficient of friction μ = 0.1, and the slope of the first inclined surface 3S and the second inclined surface 4S is tanθ = 0.25, _F0 = 0.025W. In this case, an axial force is generated in the horizontal screw 5, but since it is only 1/40 of the load W, the movement of the first wedge member 3 and the second wedge member 4 can be easily restricted by using a mechanism for restricting the rotation of the horizontal screw 5, such as a brake provided to the electric motor provided in the drive unit 7.

The majority of the vertical load acting on the jack device 1 is transmitted as a compressive force from the upper support portion 6 to the lower support portion 2 via the first wedge member 3 and the second wedge member 4. For example, if the width of the first wedge member 3 and the second wedge member 4 is 200 mm, the axial length is 100 mm, and they are made of SN400 steel, the long-term allowable compressive force is 640 tonf (6.3 MN). The jack device 1 can be configured as a jack mechanism with extremely high strength after installation, even if its lifting capacity is 20 tonf (200 kN), which is the same as that of a typical screw jack.

As described above, the jack device 1 can increase the load-bearing capacity after lifting and securing an object, regardless of the lifting capacity. The jack device 1 can adjust the height of the upper support part 6 by rotating the left and right screws 5 using an electric motor provided in the drive unit 7, which can be remotely controlled from the outside, making it easy to lift and secure an object. In the unlikely event that the drive unit 7 fails, the jack device 1 also makes it possible to manually rotate the left and right screws 5 to lift and secure the upper support part 6.

With the jack device 1, the drive unit 7 is fixed to the lower support unit 2 and the horizontal screw 5 is connected, so the horizontal screw only rotates without moving, allowing the upper support unit 6, which is installed so that its center of gravity is located at the center of the horizontal screw 5, to be raised and lowered vertically without horizontal displacement. With the jack device 1, the first wedge member 3 and second wedge member 4 threaded onto the horizontal screw 5 always displace axially symmetrically with respect to the center position of the upper support unit 6, allowing the vertical load acting on the first wedge member 3 and second wedge member 4 to be evenly distributed.

The floating floor (floor section B) described above will sink slightly (approximately 20 mm) due to the load of spectators and other people. The floating floor has a structure on its periphery that acts as a fixed floor and will not sink. The floating floor section is equipped with expansion joints to accommodate the step that occurs between it and the fixed floor when spectators enter. The smaller the step between the floating floor and the fixed floor, the better. It is desirable to align the floating floor level with the fixed floor level when there is no load, and to fix the floating floor so that it does not displace vertically when holding events that do not cause vertical vibrations that could cause vibration problems.

The jack device 1 can be applied to such floating floors. Before an event without live load is held, the upper support part 6 is raised and placed in contact with the floating floor. After the event is over, the live load is removed and the upper support part 6 is lowered away from the floating floor. With the jack device 1, almost no load is applied when the upper support part 6 is raised or lowered, so the motor specifications required for the left and right screws 5 and drive part 7 can be made small and inexpensive. Furthermore, the jack device 1 can directly support the load via the first wedge member 3 and second wedge member 4, which do not move due to friction when fixed.

With jack device 1, by connecting a reducer using a planetary gear or the like to the motor provided in the drive unit 7, the rotational torque of the motor can be increased and output, allowing the use of an inexpensive motor. Unlike a conventional screw jack that supports vertical loads, jack device 1 only needs to handle the load converted into horizontal force via the first wedge member 3 and second wedge member 4, making it possible to lift and secure objects even with low screw strength or motor capacity.

The jack device 1 provides grooves in the upper support portion 6 and lower support portion 2 along which the first wedge member 3 and second wedge member 4 slide, limiting the displacement of the first wedge member 3 and second wedge member 4 to one direction and preventing movement in an orthogonal direction and rotation (twisting) around the normal (Z-axis) of the sliding surface. The jack device 1 can be applied not only to newly constructed buildings and facilities with vibration-isolating floating floors, but also to existing floating floor structures. The jack device 1 can be used to convert a floating floor into a fixed floor, and can also be appropriately adapted to convert a fixed floor into a floating floor.

[Modification 1]
The following describes modified examples of the jack device 1. In the following description, the same components as those in the above embodiment are designated by the same names and reference numerals, and redundant description will be omitted as appropriate.

As shown in FIG. 6 , the first groove 2M of the lower support 2 may be formed so that its width increases downward when viewed along the axial direction (X-axis). The bottoms of the first wedge member 3 and the second wedge member 4 may engage with this first groove 2M and be slidable along the axial direction. This configuration prevents the first wedge member 3 and the second wedge member 4 from coming off the lower support 2. In other words, the jack device 1 prevents the first wedge member 3 and the second wedge member 4 from coming off the lower support 2 even when a tensile force is generated in the upper support 6, making it applicable even when a tensile load is applied. Furthermore, the bottoms of the first wedge member 3 and the second wedge member 4 that engage with the first groove 2M do not necessarily have to be located over the entire axial length, but may only be located over a portion of their length.

[Modification 2]
As shown in FIG. 7 , a floor structure P having an excessive reaction force prevention mechanism may be configured on the upper portion of the jack device 1. The excessive reaction force prevention mechanism may include, for example, one or more elastic members D provided between the floor portion B and the upper support portion 6, and a restricting portion 8 that restricts upward movement of the floor portion B relative to the upper support portion 6. The restricting portion 8 may include, for example, a side wall portion 8A provided on the upper surface 6F of the upper support portion 6 and an upper flange portion 8B provided at the upper end of the side wall portion 8A. The side wall portion 8A is formed, for example, extending around the periphery of the upper surface 6F of the upper support portion 6. The side wall portion 8A is formed in the shape of a wall that rises upward from the upper surface 6F of the upper support portion 6. An upper flange portion 8B is formed at the upper portion of the side wall portion 8A and protrudes horizontally from the inner periphery of the side wall portion 8A.

The upper flange portion 8B abuts against the lower flange portion B2 provided on the floor support portion B1 formed on the floor portion B. The floor support portion B1 is formed, for example, with a diameter smaller than the inner diameter of the upper flange portion 8B. A lower flange portion B2 protruding radially is formed on the lower end side of the floor support portion B1. The lower flange portion B2 is formed to extend along the periphery of the lower end side of the floor support portion B1. The lower flange portion B2 abuts against the upper flange portion 8B. One or more elastic members D are provided between the underside of the floor support portion B1 and the upper surface of the upper support portion 6.

The elastic member D is, for example, a coil spring that elastically deforms in the vertical direction. Other elastic members, such as leaf springs, rod springs, and gas springs, may also be used as long as they are elastically deformable in the vertical direction. The elastic member D is disposed in a compressed state between the underside of the floor support portion B1 and the upper surface of the upper support portion 6. The elastic member D biases the floor support portion B1 upward relative to the upper support portion 6. The floor support portion B1 is restricted from moving upward relative to the upper support portion 6 by the lower flange portion B2 abutting against the upper flange portion 8B. The floor support portion B1 and the restricting portion 8 compress the elastic member D, creating a preload. As shown in Figure 8, when a downward load is applied to the floor support portion B1, downward displacement of the floor support portion B1 does not occur until the load value of the preload is reached.

In floor structure P equipped with the excessive reaction force prevention mechanism of variant 2, jack device 1 applies the rated load of jack device 1 upward to floor section B as a preload. Therefore, when the vertical load applied to floor section B is equal to or less than the preload, the vertical spring stiffness becomes infinity (rigid), and floor section B does not displace downward, remaining a fixed floor. When the vertical load applied to floor section B due to a vertical earthquake or impact force exceeds the preload, floor section B is supported by the vertical spring stiffness k of elastic member D, which acts as a buffer, and displaces downward, absorbing energy and suppressing an increase in reaction force. In this way, floor structure P can constantly prevent vertical displacement of floor section B and fix it, while preventing the generation of excessive reaction force during a vertical earthquake, etc.

The above describes one embodiment of the present invention, but the present invention is not limited to the above embodiment and can be modified as appropriate without departing from the spirit of the invention. For example, the first inclined surface 3S and the second inclined surface 4S may be provided on the underside of the first wedge member 3 and the second wedge member 4, and the third inclined surface 6A and the fourth inclined surface 6B may be provided on the lower support part 2.

1. Jacking device, 2. Lower support part, 2M. First groove, 3. First wedge member, 3S. First inclined surface, 4. Second wedge member, 4S. Second inclined surface, 5. Left and right screws, 6. Upper support part, 6A. Third inclined surface, 6B. Fourth inclined surface, 7. Drive part, 8. Restriction part, B. Floor part, D. Elastic member, P. Floor structure

Claims (7)

a first wedge member having a first inclined surface;
a second wedge member having a second inclined surface formed thereon;
a lower support portion on which the first wedge member and the second wedge member are mounted so as to be movable in a direction in which the first inclined surface and the second inclined surface face each other;
a right-and-left screw that connects the first wedge member and the second wedge member and moves the first wedge member and the second wedge member along an axial direction based on rotation;
an upper support portion having a third inclined surface in contact with the first inclined surface and a fourth inclined surface in contact with the second inclined surface, the upper support portion being movable in a vertical direction based on movement of the first wedge member and the second wedge member ;
A jack device characterized in that, when the inclination angle of the first inclined surface and the second inclined surface is θ and the coefficient of friction generated between the first wedge member or the second wedge member and the upper support portion or the lower support portion is μ, tanθ≦2μ . The lower support portion has a first groove formed therein that allows the first wedge member and the second wedge member to move along the axial direction.
The jack apparatus according to claim 1 . a second groove that allows the first wedge member to move in the axial direction is formed in the first inclined surface or the third inclined surface;
The jack device according to claim 1 or 2. a third groove that allows the second wedge member to move in the axial direction is formed in the second inclined surface or the fourth inclined surface;
The jack device according to any one of claims 1 to 3. A drive unit that rotates the left and right screws is provided.
A jack device according to any one of claims 1 to 4. A floor structure comprising a floor supported by the upper support and the jack device described in any one of claims 1 to 5. one or more elastic members disposed between the floor portion and the upper support portion;
a restricting portion that restricts upward movement of the floor portion relative to the upper support portion and compresses the elastic member to generate a preload on the elastic member,
The floor structure according to claim 6.