CN118030142A - Temporary support trolley for reconstruction and expansion of in-situ tunnel based on air bag - Google Patents

Abstract

The invention belongs to the technical field of tunnel support, and particularly relates to a temporary support trolley for in-situ tunnel reconstruction and expansion based on an air bag, which comprises the following components: the four corners of the top of the main body support are respectively fixedly connected with the bottom ends of hollow support columns, inner lifting columns vertically slide in the hollow support columns, and the inner lifting columns are in transmission connection with a jacking device; the main body support is embedded with a control inflation assembly which is used for inflating a plurality of air bags and detecting air pressure, the air bags are sequentially piled up among the four hollow support columns, and the control inflation assembly is electrically connected with the jacking device; the bottom of the main body bracket is provided with a driving component which is electrically connected with the control inflation component; the four corners of the circumference of the main body bracket are respectively provided with a supporting component; the supporting component is electrically connected with the inflation control component. The invention has the advantages of automatic walking, repeated application, convenient operation and the like, and ensures that the reconstruction and expansion construction efficiency is higher and the cost is lower.

Description

Temporary support trolley for reconstruction and expansion of in-situ tunnel based on air bag

Technical Field

The invention belongs to the technical field of tunnel support, and particularly relates to a temporary support trolley for in-situ tunnel reconstruction and expansion based on an air bag.

Background

In order to ensure construction safety, the conventional reconstruction and expansion tunnel construction needs to be carried out by firstly backfilling hole residues on the in-situ tunnel to the arch waist before construction, the backfilled hole residues cannot be backfilled to the hole top, effective support cannot be achieved, and safety is poor.

In order to overcome the defects in the prior art, the invention provides a temporary support trolley for reconstruction and expansion of an in-situ tunnel based on an air bag, which solves the problems by changing the traditional construction method.

Disclosure of Invention

The invention aims to provide a temporary support trolley for reconstruction and expansion of an in-situ tunnel based on an air bag so as to solve the problems.

In order to achieve the above object, the present invention provides the following solutions:

An airbag-based in-situ tunnel reconstruction and expansion temporary support trolley, comprising: the four corners of the top of the main body support are respectively fixedly connected with the bottom ends of hollow support columns, inner lifting columns vertically slide in the hollow support columns, and the inner lifting columns are in transmission connection with a jacking device;

the main body support is embedded with a control inflation assembly, the control inflation assembly is used for inflating a plurality of air bags and detecting air pressure, the air bags are sequentially stacked among the four hollow support columns, and the control inflation assembly is electrically connected with the jacking device;

The bottom of the main body bracket is provided with a driving component which is electrically connected with the control inflation component;

support components are respectively arranged at four corners of the circumference of the main body support; the supporting component is electrically connected with the control inflation component.

Preferably, the side wall of the inner wall of the hollow support column is provided with a sliding part, the sliding part is arranged along the height direction of the hollow support column, and the four sliding parts are respectively arranged in a sliding manner with the corresponding outer side wall of the inner lifting column.

Preferably, the sliding part comprises a plurality of stabilizing pulleys, the stabilizing pulleys are arranged at equal intervals along the height direction of the hollow supporting column, and the stabilizing pulleys are rotationally connected with the inner wall of the hollow supporting column.

Preferably, the jacking device comprises a screw driving motor, a fixed end of the screw driving motor is fixedly connected with the top of the main body support, a second bevel gear is connected with an output shaft of the screw driving motor in a shaft mode, a first bevel gear is meshed with the second bevel gear, a rotary screw is fixedly connected with the axis of the first bevel gear, the rotary screw is in threaded connection with the corresponding inner lifting column, and the bottom end of the rotary screw is in rotary connection with the top of the main body support.

Preferably, the rotary screw is coaxially and fixedly connected with a limiting ring, the limiting ring is arranged below the corresponding inner lifting column, and the limiting ring is in limiting fit with the bottom of the corresponding inner lifting column.

Preferably, the driving assembly comprises four steering engines, fixed ends of the steering engines are fixedly connected to four corners of the bottom of the main body support respectively, and movable ends of the steering engines are fixedly connected with fixed ends of driving wheels;

the steering engines are electrically connected with the control inflation assembly, and a plurality of steering engines are used for controlling the main body support to steer;

The driving wheels are electrically connected with the control inflation assembly, and a plurality of the driving wheels are used for controlling the main body support to move.

Preferably, the support assembly comprises a hydraulic support leg, wherein the fixed end of the hydraulic support leg is fixedly connected with the side wall of the main body support, the hydraulic support leg is used for stably supporting the main body support, and the hydraulic support leg is electrically connected with the control inflation assembly.

Preferably, the electrical connection of the control inflation assembly comprises a control assembly, the control assembly is embedded in the main body bracket, the control assembly is electrically connected with an inflator pump and a digital pressure monitoring device, and the inflator pump and the digital pressure monitoring device are used for inflating the air bags and monitoring the air pressure of each air bag;

The control assembly is electrically connected with the hydraulic supporting legs, the screw driving motors, the steering engines and the driving wheels.

Preferably, a plurality of first rails are fixedly connected between two adjacent hollow support columns from low to high in sequence, and the first rails are used for preventing the corresponding air bags from leaking out of the four hollow support columns.

Preferably, a plurality of second rails are detachably connected between two adjacent inner lifting columns from low to high in sequence, and the second rails are used for preventing the corresponding air bags from leaking out from four inner lifting columns.

Compared with the prior art, the invention has the following advantages and technical effects:

When the support is used, the main support automatically walks through the driving assembly and moves to a position where the hole top needs to be supported, then the four supporting assemblies prop up the main support, so that the driving assembly at the bottom of the main support leaves the ground, the main support is further stabilized, then the lifting columns are lifted through the lifting device, the air bags are inflated through the control inflation assembly, the air pressure of the air bags is monitored in real time, the air bags are sequentially piled between the four hollow supporting columns until the air bags are contacted with the inner wall of the hole top of the in-situ tunnel, effective supporting protection is achieved, and the support has the advantages of automatic walking, repeated application, convenience in operation and the like, and is higher in reconstruction and expansion construction efficiency and lower in cost.

Drawings

For a clearer description of an embodiment of the invention or of the solutions of the prior art, the drawings that are needed in the embodiment will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art:

FIG. 1 is a schematic diagram of the structure of the present invention;

FIG. 2 is an enlarged view of a portion of the invention at A in FIG. 1;

FIG. 3 is a top view of the structure of the present invention;

FIG. 4 is a schematic view of the present invention with an air bag 17 installed;

FIG. 5 is a schematic view of the present invention for installing a plurality of air bags 17;

FIG. 6 is a schematic structural diagram of embodiment 2 of the present invention;

FIG. 7 is a schematic view of the structure of embodiment 3 of the present invention;

FIG. 8 is a top view showing the structure of a drawknot portion according to embodiment 3 of the present invention;

Wherein, 1, the main body bracket; 2. a first rail; 3. rotating the screw; 4. a hydraulic support leg; 5. a driving wheel; 6. an inflator pump and a digital pressure monitoring device; 7. steering engine; 8. a jacking device; 9. a screw drive motor; 10. a stabilizing pulley; 11. a control assembly; 12. an inner lifting column; 13. a hollow support column; 14. a limiting ring; 15. a first bevel gear; 16. a second bevel gear; 17. an air bag; 18. a second rail; 19. a steel twisted coil; 20. hooking rings; 21. a guard board; 22. a connecting ring; 23. a bottom bladder; 24. a middle air bag; 25. a top bladder; 26. a middle stretching rib; 27. horizontal lacing wires; 28. corner lacing wires; 29. the communicating air tap; 30. and (5) self-closing the valve.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.

Example 1:

Referring to fig. 1 to 5, the present invention discloses a temporary support trolley for in-situ tunnel reconstruction and expansion based on an airbag, comprising: the main body support 1, the four corners of the top of the main body support 1 are fixedly connected with the bottom ends of hollow support columns 13 respectively, inner lifting columns 12 vertically slide in the hollow support columns 13, and the inner lifting columns 12 are in transmission connection with a jacking device 8;

the main body bracket 1 is embedded with a control inflation assembly which is used for inflating a plurality of air bags 17 and detecting air pressure, the air bags 17 are sequentially piled up among the four hollow support columns 13, and the control inflation assembly is electrically connected with the jacking device 8;

the bottom of the main body bracket 1 is provided with a driving component which is electrically connected with the control inflation component;

The circumference Xiang Sijiao of the main body bracket 1 is respectively provided with a supporting component; the supporting component is electrically connected with the inflation control component.

During the use, main part support 1 is walked automatically through drive assembly, remove to the position that the hole top needs to support, four support assemblies prop up main part support 1 afterwards, make the drive assembly of main part support 1 bottom leave ground, and then realize main part support 1's firm, rise each internal lifting column 12 through jacking device 8 afterwards, and use control to inflate the subassembly to each gasbag 17, and to the atmospheric pressure real-time supervision of each gasbag 17, pile up each gasbag 17 in proper order between four cavity support columns 13, until gasbag 17 and the contact of normal position tunnel top inner wall play effectual support protection.

The air tap of the air bag 17 is provided with a wireless air pressure detection device, and the air inflation assembly is controlled to acquire data in a wireless transmission mode. The wireless air pressure detection device is the prior art and will not be described in detail here.

Further optimizing scheme, the inner wall lateral wall of cavity support column 13 is equipped with the sliding part, and the sliding part sets up along cavity support column 13 direction of height, and four sliding parts slide with the lateral wall of corresponding interior lift column 12 respectively and set up.

Further optimizing scheme, the sliding part includes a plurality of stable pulleys 10, and a plurality of stable pulleys 10 are along the equidistant setting of cavity support column 13 direction of height, and stable pulley 10 rotates with cavity support column 13 inner wall to be connected.

The plurality of stabilizing pulleys 10 are arranged on the inner wall of the opposite side of the hollow support column 13 and the inner lifting column 12, so that the inner lifting column 12 can slide more smoothly relative to the hollow support column 13.

Further optimizing scheme, jacking device 8 includes screw rod driving motor 9, and screw rod driving motor 9's stiff end and main part support 1 top rigid coupling, and screw rod driving motor 9's output shaft coupling has second bevel gear 16, and second bevel gear 16 meshing has first bevel gear 15, and first bevel gear 15 axle center rigid coupling has rotatory screw rod 3, and rotatory screw rod 3 and corresponding interior lift post 12 threaded connection, rotatory screw rod 3 bottom and main part support 1 top rotation are connected.

In a further optimized scheme, the rotary screw 3 is coaxially and fixedly connected with a limiting ring 14, the limiting ring 14 is arranged below the corresponding inner lifting column 12, and the limiting ring 14 is in limiting fit with the bottom of the corresponding inner lifting column 12.

The spacing ring 14 prevents that the bottom of interior post 12 from descending excessively, play the effect of protection first bevel gear 15 and second bevel gear 16, screw drive motor 9 drive second bevel gear 16 drive first bevel gear 15 drive rotatory screw rod 3 rotation, rotatory screw rod 3 and interior post 12 threaded connection, under the screw thread effect, interior post 12 can rise along rotatory screw rod 3, interior post 12 and the hollow support column 13 cross-section are the rectangle simultaneously, and the stable pulley 10 that the inner wall of hollow support column 13 set up, four stable pulleys 10 that are located same height encircle interior post 12 circumference setting, be equivalent to with interior post 12 centre gripping in the centre, play the effect of preventing interior post 12 rotation, and then through the rotation of rotatory screw rod 3, can realize the lift of interior post 12.

In a further optimization scheme, the driving assembly comprises four steering engines 7, fixed ends of the steering engines 7 are fixedly connected to four corners of the bottom of the main body support 1 respectively, and movable ends of the steering engines 7 are fixedly connected with fixed ends of driving wheels 5;

the steering engines 7 are electrically connected with the control inflation assembly, and a plurality of steering engines 7 are used for controlling the main body bracket 1 to steer;

the driving wheels 5 are electrically connected with the inflation control assembly, and the driving wheels 5 are used for controlling the main body bracket 1 to move.

The specific structure and connection manner of the steering engine 7 and the driving wheel 5 are the prior art, and will not be described in detail here.

Further optimizing scheme, supporting component includes hydraulic support leg 4, and hydraulic support leg 4's stiff end and main part support 1 lateral wall rigid coupling, hydraulic support leg 4 are used for firmly supporting main part support 1, hydraulic support leg 4 and control inflation subassembly electric connection.

Further optimizing scheme, the control inflation assembly is electrically connected and comprises a control assembly 11, the control assembly 11 is embedded in the main body bracket 1, the control assembly 11 is electrically connected with an inflator pump and a digital pressure monitoring device 6, and the inflator pump and the digital pressure monitoring device 6 are used for inflating the air bags 17 and monitoring the air pressure of each air bag 17;

the control assembly 11 is electrically connected with a plurality of hydraulic supporting legs 4, a plurality of screw driving motors 9, a plurality of steering engines 7 and a plurality of driving wheels 5.

The control assembly 11 is preferably a PLC programmable controller.

Further optimizing scheme, a plurality of first rails 2 are fixedly connected between two adjacent hollow support columns 13 from low to high in sequence, and the first rails 2 are used for preventing corresponding air bags 17 from leaking out from four hollow support columns 13.

Further optimizing scheme, a plurality of second rails 18 are detachably connected between two adjacent inner lifting columns 12 from low to high in sequence, and the second rails 18 are used for preventing corresponding air bags 17 from leaking out from four inner lifting columns 12.

The side walls of the inner lifting columns 12 are provided with a plurality of through holes in advance, the through holes are used for penetrating the end parts of the second railing 18 into the inner lifting columns 12, and after the inner lifting columns 12 extend out of the hollow supporting columns 13, the second railing 18 is installed between two adjacent inner lifting columns 12.

Example 2:

Referring to fig. 6, this embodiment is different from embodiment 1 in that an airbag protection part is placed on top of the airbag 17 located on top, and four corners of the airbag protection part are fixedly connected with the tops of the corresponding jack-up posts 12, respectively.

The air bag protection part comprises a plurality of guard plates 21 which are arranged in a matrix, connecting rings 22 are arranged between two adjacent guard plates 21, the connecting rings 22 are hooked with the corresponding guard plates 21, one ends of the plurality of connecting rings 22, which are positioned at the same side edge part, far away from the plurality of guard plates 21 are hooked with one corresponding side of the steel twisted coil 19, four corners of the steel twisted coil 19 are respectively fixedly connected with a hook ring 20, the hook rings 20 are hooked with the tops of the corresponding inner lifting columns 12 through hooks, and the hooks are hinged to the tops of the inner lifting columns 12.

In order to avoid that the top airbag 17 is worn or pierced by the contact surface of the hole roof during the bearing, an airbag protection is provided on top of the top airbag 17.

The air bag protection part is composed of a plurality of guard plates 21 which are arranged in a matrix, the two adjacent guard plates 21 are hooked through connecting rings 22, so that the guard plates 21 are in flexible connection, the flexible connection can be changed along with the shape of the top of the air bag 17, the hook rings 20 at four corners of the steel strand ring 19 are hooked with the tops of the corresponding inner lifting columns 12 through hooks, and the guard plates 21 are arranged at the top of the air bag 17 at the top, so that the protection effect is realized.

Example 3:

referring to fig. 7 to 8, this embodiment differs from embodiment 1 in that the airbag 17 is divided into a bottom airbag 23, a plurality of middle airbags 24, and a top airbag 25, the plurality of middle airbags 24 are sequentially spliced, the bottom of the middle airbag 24 located at the bottom is spliced with the top of the bottom airbag 23, and the top of the middle airbag 24 located at the top is spliced with the bottom of the top airbag 25;

The top of the middle air bag 24 is provided with a first groove, and the bottom of the middle air bag 24 is provided with a first bulge;

the top of the bottom air bag 23 is provided with a second groove which is matched with the first bulge;

The bottom of the top air bag 25 is provided with a second bulge, the second bulge is matched with the first groove, the second groove has the same structure and size as the first groove, and the first bulge has the same structure and size as the second bulge;

The bottom air bag 23, the middle air bag 24 and the top air bag 25 are internally provided with drawknot parts, each drawknot part comprises a middle stretching rib 26, the end parts of the middle stretching ribs 26 are fixedly connected with one ends of a plurality of obliquely arranged corner stretching ribs 28, and the other ends of the corner stretching ribs 28 are fixedly connected with the corresponding corners of the bottom air bag 23 or the middle air bag 24 or the top air bag 25;

One end of a plurality of horizontal lacing wires 27 are fixedly connected on the middle stretching rib 26 in the circumferential direction, and the other end of the horizontal lacing wires 27 is fixedly connected with the corresponding side wall center of the bottom air bag 23 or the middle air bag 24 or the top air bag 25;

the centers of the first bulge and the second bulge are fixedly connected and communicated with a communication air tap 29, the communication air tap 29 is slidably connected with a self-closing air valve 30, and the self-closing air valve 30 is correspondingly arranged at the center of the first groove or the second groove.

In order to ensure the stability of each airbag 17 when stacking, the airbag 17 is divided into a bottom airbag 23, a middle airbag 24 and a top airbag 25, the bottom airbag 23, the middle airbag 24 and the top airbag 25 are spliced together through the matching of the bulges and the grooves, so that the stability of the bottom airbag 23, the middle airbag 24 and the top airbag 25 in the vertical direction is greatly increased after stacking, the supporting effect can be better achieved, meanwhile, the drawknot parts arranged inside the bottom airbag 23, the middle airbag 24 and the top airbag 25 are used for simultaneously pulling the side walls of the bottom airbag 23, the middle airbag 24 or the top airbag 25 towards the center when the bottom airbag 23, the middle airbag 24 and the top airbag 25 are recovered and deflated, and the corner drawstrings 28 are used for simultaneously pulling the corners of the bottom airbag 23, the middle airbag 24 or the top airbag 25 towards the center, so that the bottom airbag 23, the middle airbag 24 and the top airbag 25 can be quickly collapsed into a group and the storage is convenient.

When the inflatable device is required to be inflated, after the bottom airbag 23 is placed, the first bulge at the bottom of the middle airbag 24 is inserted into the second groove at the top of the bottom airbag 23, meanwhile, the communicating air tap 29 at the bottom of the middle airbag 24 is inserted into the self-closing air tap 30 at the top of the bottom airbag 23, after the plurality of middle airbags 24 are mutually spliced, the first groove of the front middle airbag 24 is matched with the first bulge of the rear middle airbag 24, the self-closing air tap 30 of the front middle airbag 24 is spliced and communicated with the communicating air tap 29 of the rear middle airbag 24, finally, the second bulge of the top airbag 25 is matched with the first groove of the middle airbag 24 at the top, the communicating air tap 29 of the top airbag 25 is inserted into the self-closing air tap 30 of the middle airbag 24 at the top, and under the action of the plurality of self-closing air taps 30 and the communicating air tap 29, the interiors of the bottom airbag 23, the plurality of middle airbags 24 and the top airbag 25 are all in a communicating state, and the bottom airbag 23 can be inflated simultaneously through the inflator pump and the digital pressure monitoring device 6.

In the description of the present invention, it should be understood that the terms "longitudinal," "transverse," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate or are based on the orientation or positional relationship shown in the drawings, merely to facilitate description of the present invention, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present invention.

The above embodiments are only illustrative of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention, and various modifications and improvements made by those skilled in the art to the technical solutions of the present invention should fall within the protection scope defined by the claims of the present invention without departing from the design spirit of the present invention.

Claims (10)

1. Temporary support platform truck is rebuild and expand based on gasbag normal position tunnel, characterized by comprising: the lifting device comprises a main body support (1), wherein the bottom ends of hollow support columns (13) are fixedly connected to four corners of the top of the main body support (1), inner lifting columns (12) vertically slide in the hollow support columns (13), and the inner lifting columns (12) are in transmission connection with a lifting device (8);

The main body support (1) is internally embedded with a control inflation assembly, the control inflation assembly is used for inflating a plurality of air bags (17) and detecting air pressure, the air bags (17) are sequentially stacked among the four hollow support columns (13), and the control inflation assembly is electrically connected with the jacking device (8);

The bottom of the main body bracket (1) is provided with a driving component which is electrically connected with the control inflation component;

the four circumferential corners of the main body support (1) are respectively provided with a support component; the supporting component is electrically connected with the control inflation component.

2. The temporary support trolley for in-situ tunnel reconstruction based on air bags according to claim 1, wherein: the inner wall side wall of the hollow support column (13) is provided with sliding parts, the sliding parts are arranged along the height direction of the hollow support column (13), and the four sliding parts are respectively arranged in a sliding manner with the corresponding outer side wall of the inner lifting column (12).

3. The temporary support trolley for in-situ tunnel reconstruction based on air bags according to claim 2, wherein: the sliding part comprises a plurality of stabilizing pulleys (10), the stabilizing pulleys (10) are arranged at equal intervals along the height direction of the hollow supporting column (13), and the stabilizing pulleys (10) are rotationally connected with the inner wall of the hollow supporting column (13).

4. The temporary support trolley for in-situ tunnel reconstruction based on air bags according to claim 1, wherein: the jacking device (8) comprises a screw driving motor (9), the fixed end of the screw driving motor (9) is fixedly connected with the top of the main body support (1), a second bevel gear (16) is connected with an output shaft of the screw driving motor (9) in a shaft mode, a first bevel gear (15) is meshed with the second bevel gear (16), a rotary screw (3) is fixedly connected with the axis of the first bevel gear (15), the rotary screw (3) is in threaded connection with a corresponding inner lifting column (12), and the bottom end of the rotary screw (3) is connected with the top of the main body support (1) in a rotating mode.

5. The temporary support trolley for in-situ tunnel reconstruction based on air bags according to claim 4, wherein: the rotary screw (3) is coaxially and fixedly connected with a limiting ring (14), the limiting ring (14) is arranged below the corresponding inner lifting column (12), and the limiting ring (14) is in limiting fit with the bottom of the corresponding inner lifting column (12).

6. The temporary support trolley for in-situ tunnel reconstruction based on air bags according to claim 4, wherein: the driving assembly comprises four steering engines (7), fixed ends of the steering engines (7) are fixedly connected to four corners at the bottom of the main body support (1) respectively, and movable ends of the steering engines (7) are fixedly connected with fixed ends of driving wheels (5);

The steering engines (7) are electrically connected with the control inflation assembly, and a plurality of steering engines (7) are used for controlling the main body support (1) to steer;

the driving wheels (5) are electrically connected with the inflation control assembly, and a plurality of the driving wheels (5) are used for controlling the main body support (1) to move.

7. The temporary support trolley for in-situ tunnel reconstruction based on air bags according to claim 6, wherein: the support assembly comprises a hydraulic support leg (4), wherein the fixed end of the hydraulic support leg (4) is fixedly connected with the side wall of the main body support (1), the hydraulic support leg (4) is used for stably supporting the main body support (1), and the hydraulic support leg (4) is electrically connected with the control inflation assembly.

8. The temporary support trolley for in-situ tunnel reconstruction based on air bags according to claim 7, wherein: the control inflation assembly is electrically connected with the main body support (1), the control assembly (11) is embedded in the main body support (1), the control assembly (11) is electrically connected with an inflator pump and a digital pressure monitoring device (6), and the inflator pump and the digital pressure monitoring device (6) are used for inflating the air bags (17) and monitoring the air pressure of each air bag (17);

The control assembly (11) is electrically connected with the hydraulic support legs (4), the screw driving motors (9), the steering engines (7) and the driving wheels (5).

9. The temporary support trolley for in-situ tunnel reconstruction based on air bags according to claim 1, wherein: a plurality of first rails (2) are fixedly connected between two adjacent hollow support columns (13) from low to high in sequence, and the first rails (2) are used for preventing the corresponding air bags (17) from leaking out from four hollow support columns (13).

10. The temporary support trolley for in-situ tunnel reconstruction based on air bags according to claim 1, wherein: a plurality of second rails (18) are sequentially and detachably connected between two adjacent inner lifting columns (12) from low to high, and the second rails (18) are used for preventing the corresponding air bags (17) from leaking out from four inner lifting columns (12).