Chinese speech teaching device

Abstract

The invention discloses a Chinese speech teaching device, which relates to the field of teaching and comprises a base and a fixed column arranged at the upper end of the base, a lifting block is arranged in the fixed column, a display screen is arranged at the upper end of the lifting block, a honeycomb sounder is mounted on the surface of the display screen, and a control panel is arranged at the lower end of the base. And a positioning anti-skid mechanism is arranged between the control panel and the base. According to the Chinese speech teaching device, after the Chinese speech teaching device is moved to a proper position, the height of a display screen is adjusted, so that clamping plates at the front end and the rear end of a control panel press locking blocks downwards, clamping grooves of the clamping plates are separated from clamping of the locking blocks, and at the moment, the control panel makes contact with the ground under the action of pressure springs; and the friction force between the control panel and the ground is increased, so that the effect of automatic positioning and stabilizing after reaching the use position can be achieved, the device can be prevented from shaking due to the universal wheels at the bottom, and the stability of the device is improved.

Description

Technical Field

[0001] The present invention relates to the field of teaching technologies, and particularly to a Chinese speech teaching device. Background Art

[0002] A Chinese speech teaching device is a device used to help users learn Chinese speech, mainly for displaying pictures and playing audio to assist users in better learning Chinese pronunciation.

[0003] In the prior art, during Chinese speech teaching, the storage and transportation of the device are inconvenient, which is not conducive to the handling by users. At the same time, during use, the height adjustment of the device is inconvenient, which is likely to affect the viewing of people in different positions.

[0004] To overcome the above deficiencies, a Chinese patent of the prior art (Publication No. CN211979947U) discloses a Chinese speech teaching tool, including a base. A plurality of traveling devices are fixedly connected to the lower end of the base. A device rod is fixedly connected to the upper end of the base. A storage device is disposed through the side wall of the device rod. A threaded column is disposed above the device rod. The device rod and the threaded column are rotatably connected through a rotating shaft. A limiting device is fixedly connected to the side wall of the device rod. The upper end of the threaded column is threadedly connected to a threaded seat. A teaching board is fixedly connected to the upper end of the threaded seat. A book placement groove is disposed through the side wall of the teaching board. Two clamping devices are fixedly connected to the upper end of the teaching board, which has the advantage of convenient storage.

[0005] To overcome the above deficiencies, a Chinese patent of the prior art (Publication No. CN213241581U) discloses a Chinese speech teaching tool, including a display board. The left end of the display board is connected to a speech board. The connection between the display board and the speech board is movably hinged through two hinges. Two second magnets are fixedly connected to the left front position of the front end of the speech board. Two first magnets are fixedly connected to the front end of the display board. Two connecting blocks are fixedly connected to the lower end of the display board. The lower ends of the two connecting blocks are both fixedly connected to a screw rod. The two screw rods are movably inserted into the upper end of a base box and both extend into the interior of the base box. Two gear covers are fixedly connected to the upper inner wall of the base box and respectively sleeved on the surfaces of the two screw rods. A second gear is rotatably connected in each of the two gear covers and respectively threadedly connected to the surfaces of the two screw rods. Internal threaded holes are drilled at the upper ends of the two second gears. The present utility model can adjust the height and improve the teaching efficiency.

[0006] Although the prior art can overcome the above-mentioned deficiencies, there are still other problems during its operation. For example, during the teaching process using a Chinese voice teaching device, when the user touches the display screen, a certain force will be exerted on the teaching device. As the user touches and uses the teaching device, it is easy to cause the device to shake. Under the action of the applied force, the contact between the device and different ground positions is likely to shift, thus affecting the stability of the device and further being unfavorable for the user's viewing. At the same time, if it is used near the blackboard in the classroom, since the chalk dust is scattered in the air, it is easy to stain the surface of the display screen with chalk dust, affecting the user's viewing. Summary of the Invention

[0007] The purpose of the present invention is to provide a Chinese voice teaching device to solve the problems mentioned in the above background technology, that is, when using a Chinese voice teaching device for teaching, a force is exerted on the teaching device. As the user touches and uses the teaching device, it is easy to cause the device to shake. At this time, under the action of the applied force, the contact between the device and the ground position is likely to shake and shift. At the same time, if it is used near the blackboard in the classroom, since the chalk dust is scattered in the air, it is easy to stain the surface of the display screen with chalk dust, affecting the user's viewing.

[0008] To achieve the above purpose, the present invention provides the following technical solution: A Chinese voice teaching device includes a base and a fixed column arranged at the upper end of the base. A lifting block is arranged inside the fixed column, and a display screen is arranged at the upper end of the lifting block. A honeycomb sound generator is installed on the surface of the display screen; a servo motor is arranged on the surface of the base, and a multi-position adjustment mechanism is arranged at the output end of the servo motor. The multi-position adjustment mechanism is provided with a threaded rod, and the threaded rod is arranged inside the fixed column; a control board is arranged at the lower end of the base, and a positioning and anti-slip mechanism is arranged between the control board and the base. The positioning and anti-slip mechanism is provided with a damping rod, and the upper and lower ends of the damping rod are arranged between the control board and the base; an airbag is arranged outside the fixed column, and a self-cleaning mechanism is arranged at the upper end of the airbag. The self-cleaning mechanism is provided with a telescopic bellows, and the lower end of the telescopic bellows is connected to the airbag.

[0009] Furthermore, the multi-position adjustment mechanism is provided with a first bevel gear, and the left side of the first bevel gear is fixedly installed at the output end of the servo motor. A second bevel gear is meshed and installed at the upper end of the first bevel gear, and the upper end of the second bevel gear is fixedly installed at the lower end of the threaded rod. The threaded rod is rotationally connected to the inside of the fixed column. Four universal wheels are arranged at the lower end of the base.

[0010] Further, the surface of the threaded rod is threadedly connected to the inside of the lifting block, and limiting plates are fixedly installed on the left and right sides of the lifting block. Openings are provided on the left and right sides of the fixed column, and the limiting plates are correspondingly arranged with the openings on the left and right sides of the fixed column.

[0011] Further, a rotating block is rotatably installed at the upper end of the lifting block, and the upper end of the rotating block is rotatably connected to the elevation adjustment block. A rubber ring is arranged on the outer side of the rear end of the elevation adjustment block, and the outer side of the rubber ring is attached to the upper end of the rotating block. The front end of the elevation adjustment block is fixedly connected to the display screen.

[0012] Further, the positioning and anti-slip mechanism is provided with a positioning rod, and the left and right sides of the positioning rod are fixedly installed at the lower end of the base. A movable block is installed through the surface of the positioning rod, and an inclined rod is rotatably installed at the lower end of the movable block. The lower end of the inclined rod is rotatably installed with a control plate.

[0013] Further, a pressure spring is arranged on the outer side of the movable block, and the outer side of the pressure spring is arranged at the bottom of the base. An anti-slip pad is fixedly installed at the lower end of the control plate.

[0014] Further, clamping plates are fixedly installed at the front and rear ends of the control plate, and the upper ends of the clamping plates penetrate through the base. A dial is fixedly installed on the outer side of the clamping plate, and a card slot is provided at the upper end of the clamping plate.

[0015] Further, a fixed block is arranged on the surface of the base, and a pull rod is installed through the inside of the fixed block. A locking block is fixedly installed on the inner side of the pull rod, and the inner side of the locking block is inclined. The locking block is correspondingly arranged with the card slot. A positioning socket is nested at the upper end of the fixed block, and the lower end of the positioning socket is located on the outer side of the locking block. A traction rope is fixedly installed at the upper end of the positioning socket, and the upper end of the traction rope is fixedly installed at the lower end of the limiting plate.

[0016] Further, the self-cleaning mechanism is provided with a jet port, and the rear end of the jet port is fixedly installed on the surface of the display screen. The output end of the display screen is aligned with the screen of the display screen, and the upper end of the jet port is communicated with the airbag through a telescopic bellows.

[0017] Further, the airbag is made of elastic material, and the airbag and the limiting plate form a pressing structure. A one-way air inlet is installed through the upper end of the airbag, and a one-way valve is arranged inside the one-way air inlet.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] 1. After moving the Chinese voice teaching device to a suitable position and adjusting the height of the display screen, when the limiting plate rises, under the action of the traction rope, the positioning socket is pulled away from the fixed block. Therefore, the clamping plates at the front and rear ends of the control board press down the locking block, causing the card slots of the clamping plates to disengage from the engagement of the locking block. At this time, the control board contacts the ground under the action of the compression spring. Through the setting of the anti-slip pad, the friction between the control board and the ground is increased. Therefore, after reaching the use position, the effect of automatic positioning and stability can be achieved, and the device can be prevented from shaking due to the universal wheels at the bottom, improving the stability of the device.

[0020] 2. When using the device, by starting the servo motor at the upper end of the base, the rotation of the first bevel gear and the second bevel gear at the output end of the servo motor is driven. When the threaded rod is threadedly connected to the lifting block inside the fixed column at the upper end, with the rotation of the threaded rod, the height is adjusted under the limitation of the limiting plate. In this way, the components at the upper end can be driven to adjust the height, which is convenient for use in different venues and can be retracted and stored for easy storage management.

[0021] Furthermore, after the height of the lifting block is adjusted, through the setting of the rotating block, the display screen at the front end can be driven to perform micro-angle left and right adjustments. At the same time, under the setting of the elevation adjustment block, the elevation angle of the display screen can be adjusted. In this way, Chinese voice teaching can be carried out through the honeycomb sound generator on the surface of the display screen, which can be applied to different occasions, improving the practicability of the device and facilitating the angle adjustment of the user.

[0022] 3. When the height of the display screen is adjusted, as the height of the limiting plate rises, the airbag is squeezed. The air inside the airbag is conveyed to the jet orifice through the telescopic bellows, and the jet orifice blows the dust accumulated on the surface of the display screen from top to bottom, facilitating the user's viewing. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic three-dimensional structure diagram of the whole invention;

[0024] Figure 2 It is a schematic rear three-dimensional structure diagram of the whole invention;

[0025] Figure 3 It is a schematic bottom three-dimensional structure diagram of the whole invention;

[0026] Figure 4 It is a schematic sectional three-dimensional structure diagram of the fixed column of the whole invention;

[0027] Figure 5 It is a schematic three-dimensional structure diagram of the rubber ring of the whole invention;

[0028] Figure 6 It is a schematic sectional three-dimensional structure diagram of the inclined rod of the whole invention;

[0029] Figure 7 Schematic perspective side-sectional view of the fixing block of the present invention;

[0030] Figure 8 Schematic perspective top-sectional view of the fixing block of the present invention;

[0031] Figure 9 Schematic perspective side-sectional view of the airbag of the present invention;

[0032] Figure 10 For the present invention Figure 9 Schematic enlarged view of the structure at A in the present invention.

[0033] In the figure: 1, base; 2, fixed column; 3, lifting block; 4, rotating block; 5, elevation adjustment block; 6, display screen; 7, honeycomb sound generator; 8, servo motor; 9, first bevel gear; 10, second bevel gear; 11, threaded rod; 12, limiting plate; 13, rubber ring; 14, positioning rod; 15, movable block; 16, inclined rod; 17, control board; 18, pressure spring; 19, damping rod; 20, clamping plate; 21, dial; 22, card slot; 23, fixing block; 24, pull rod; 25, locking block; 26, positioning socket; 27, traction rope; 28, airbag; 29, telescopic bellows; 30, jet port; 31, one-way air inlet. Specific embodiments

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0035] Embodiment 1: As Figures 1 - 5The technical solution shown is a Chinese voice teaching device. To solve the problem of inconvenient angle adjustment during teaching, it discloses: a base 1 and a fixed column 2 provided at the upper end of the base 1. An elevating block 3 is provided inside the fixed column 2, and a display screen 6 is provided at the upper end of the elevating block 3. A honeycomb sound generator 7 is installed on the surface of the display screen 6. A servo motor 8 is provided on the surface of the base 1, and a multi-position adjustment mechanism is provided at the output end of the servo motor 8. The multi-position adjustment mechanism is provided with a threaded rod 11, and the threaded rod 11 is arranged inside the fixed column 2. The multi-position adjustment mechanism is provided with a first bevel gear 9, and the left side of the first bevel gear 9 is fixedly installed at the output end of the servo motor 8. A second bevel gear 10 is meshed and installed at the upper end of the first bevel gear 9, and the upper end of the second bevel gear 10 is fixedly installed at the lower end of the threaded rod 11. The threaded rod 11 is rotationally connected to the inside of the fixed column 2. Four universal wheels are provided at the lower end of the base 1. The surface of the threaded rod 11 is threadedly connected to the inside of the elevating block 3. Limiting plates 12 are fixedly installed on the left and right sides of the elevating block 3. Openings are provided on the left and right sides of the fixed column 2, and the limiting plates 12 are correspondingly arranged with the openings on the left and right sides of the fixed column 2. A rotating block 4 is rotationally installed at the upper end of the elevating block 3, and the upper end of the rotating block 4 is rotationally connected to the elevation adjustment block 5. A rubber ring 13 is provided on the outer side of the rear end of the elevation adjustment block 5, and the outer side of the rubber ring 13 is attached to the upper end of the rotating block 4. The front end of the elevation adjustment block 5 is fixedly connected to the display screen 6;

[0036] When using the device, by starting the servo motor 8 at the upper end of the base 1, the rotation of the first bevel gear 9 and the second bevel gear 10 at its output end is driven by the start of the servo motor 8. When the second bevel gear 10 rotates, it can drive the threaded rod 11 to rotate. With the threaded rod 11 threadedly connected to the elevating block 3 inside the fixed column 2 at the upper end, the height of the elevating block 3 is adjusted under the limitation of the limiting plate 12 as the threaded rod 11 rotates. In this way, the components at the upper end can be driven to adjust the height, which is convenient for use in different venues and can be retracted and stored, facilitating storage management. At the same time, after the height of the elevating block 3 is adjusted, through the setting of the rotating block 4, the display screen 6 at the front end can be adjusted slightly left and right in angle. At the same time, with the setting of the elevation adjustment block 5, the elevation angle of the display screen 6 can be adjusted. With the setting of the rubber ring 13, the friction between the rotating block 4 and the elevation adjustment block 5 is increased, preventing the display screen 6 from being too heavy to support. In this way, Chinese voice teaching can be carried out through the honeycomb sound generator 7 on the surface of the display screen 6, which can be applied to different occasions, improving the practicability of the device and facilitating the angle adjustment for users.

[0037] Embodiment 2: As Figures 1 - 8Based on the first embodiment, the disclosed technical solution aims to solve the problem of poor stability when using a Chinese voice teaching device. It is disclosed that a control board 17 is provided at the lower end of the base 1, and a positioning and anti-slip mechanism is arranged between the control board 17 and the base 1. The positioning and anti-slip mechanism is provided with a damping rod 19, and the upper and lower ends of the damping rod 19 are arranged between the control board 17 and the base 1. The positioning and anti-slip mechanism is provided with a positioning rod 14, and the left and right sides of the positioning rod 14 are fixedly installed at the lower end of the base 1. The surface of the positioning rod 14 is penetrated and installed with a movable block 15, and an inclined rod 16 is rotatably installed at the lower end of the movable block 15. The lower end of the inclined rod 16 is rotatably installed with the control board 17. A pressure spring 18 is arranged outside the movable block 15, and the outside of the pressure spring 18 is arranged at the bottom of the base 1. An anti-slip pad is fixedly installed at the lower end of the control board 17. Clamping plates 20 are fixedly installed at the front and rear ends of the control board 17, and the upper ends of the clamping plates 20 penetrate through the base 1. A dial plate 21 is fixedly installed on the outside of the clamping plates 20, and a card slot 22 is opened at the upper end of the clamping plate 20. A fixing block 23 is arranged on the surface of the base 1, and a pull rod 24 is penetrated and installed inside the fixing block 23. A locking block 25 is fixedly installed on the inner side of the pull rod 24, and the inner side of the locking block 25 is inclined. The locking block 25 is arranged corresponding to the card slot 22. A positioning socket 26 is nested and installed at the upper end of the fixing block 23, and the lower end of the positioning socket 26 is located outside the locking block 25. A traction rope 27 is fixedly installed at the upper end of the positioning socket 26, and the upper end of the traction rope 27 is fixedly installed at the lower end of the limiting plate 12;

[0038] After moving the Chinese voice teaching device to a suitable position and adjusting the height of the display screen 6, when the limit plate 12 rises, under the action of the traction rope 27, the positioning socket 26 is pulled away from the fixed block 23. At this time, since the inner shape of the locking block 25 is inclined, under the action of the pressure spring 18 at the bottom, the pressure spring 18 pushes the movable block 15 to slide along the positioning rod 14. The movable block 15 pushes the inclined rod 16 rotatably installed at both the upper and lower ends, so that the inclined rod 16 can push the control board 17 downward. Therefore, the clamping plates 20 at the front and rear ends of the control board 17 press the locking block 25 downward, so that the clamping groove 22 inside the clamping plate 20 is disengaged from the engagement of the locking block 25. At this time, the control board 17 contacts the ground under the action of the pressure spring 18. Through the setting of the anti-slip pad, the friction between the control board 17 and the ground is increased. At the same time, under the setting of the damping rod 19, the reciprocating vibration of the pressure spring 18 is avoided. Therefore, after reaching the use position, the effect of automatic positioning and stability can be achieved, and the device can be prevented from shaking due to the universal wheels at the bottom, improving the stability of the device. When storage is required, the height of the display screen 6 is adjusted downward until the limit plate 12 is reset. Then, the clamping plate 20 is driven to rise by the dial 21 outside the clamping plate 20, so that the clamping plate 20 passes through the base 1. After the clamping groove 22 inside it corresponds to the locking block 25, the locking block 25 is pushed into the clamping groove 22 by the pull rod 24. At this time, the positioning socket 26 is inserted into the fixed block 23 to fix the locking block 25 to prevent it from moving outward, and reset storage can be achieved. At this time, the device can continue to move through the universal wheels at the bottom of the base 1.

[0039] Embodiment 3: As Figures 1 - 10 shown in the technical solution, on the basis of Embodiment 2, in order to solve the problem that when the device is used in an environment with more dust, the display screen is easily contaminated with dust and cannot be observed clearly, it is disclosed that: an airbag 28 is arranged on the outer side of the fixed column 2, and a self-cleaning mechanism is arranged at the upper end of the airbag 28. The self-cleaning mechanism is provided with a telescopic bellows 29, and the lower end of the telescopic bellows 29 is connected to the airbag 28. The self-cleaning mechanism is provided with a jet port 30, and the rear end of the jet port 30 is fixedly installed on the surface of the display screen 6. And the output end of the display screen 6 is aligned with the screen of the display screen 6. Moreover, the upper end of the jet port 30 is communicated with the airbag 28 through the telescopic bellows 29. The airbag 28 is made of elastic material, and the airbag 28 and the limit plate 12 form a pressing structure. And a one-way air inlet 31 is installed through the upper end of the airbag 28, and a one-way valve is arranged inside the one-way air inlet 31;

[0040] When the height of the display screen 6 is adjusted, as the height of the limit plate 12 rises, the airbag 28 is squeezed. The air inside the airbag 28 is conveyed to the jet port 30 through the telescopic bellows 29. The jet port 30 is aligned with the surface of the display screen 6 and blows the dust accumulated on the surface area of the display screen 6 from top to bottom, facilitating the user's viewing. At the same time, when the limit plate 12 descends and resets, the airbag 28 stops being squeezed, and the airbag 28 resets by its own elasticity. When the airbag 28 resets, it inhales through the one-way valve inside the one-way air inlet 31 and can be re-inflated and recycled.

[0041] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A Chinese voice teaching device, comprising a base (1) and a fixing column (2) arranged at the upper end of the base (1). An elevating block (3) is arranged inside the fixing column (2), and a display screen (6) is arranged at the upper end of the elevating block (3). A honeycomb sound generator (7) is installed on the surface of the display screen (6). It is characterized in that: A servo motor (8) is arranged on the surface of the base (1), and a multi-position adjusting mechanism is arranged at the output end of the servo motor (8). The multi-position adjusting mechanism is provided with a threaded rod (11), and the threaded rod (11) is arranged inside the fixing column (2). A control board (17) is arranged at the lower end of the base (1), and a positioning and anti-slip mechanism is arranged between the control board (17) and the base (1). The positioning and anti-slip mechanism is provided with a damping rod (19), and the upper and lower ends of the damping rod (19) are arranged between the control board (17) and the base (1). An airbag (28) is arranged outside the fixing column (2), and a self-cleaning mechanism is arranged at the upper end of the airbag (28). The self-cleaning mechanism is provided with a telescopic bellows (29), and the lower end of the telescopic bellows (29) is connected to the airbag (28).

2. The Chinese voice teaching device according to claim 1, characterized in that: The multi-position adjusting mechanism is provided with a first bevel gear (9), and the left side of the first bevel gear (9) is fixedly installed at the output end of the servo motor (8). A second bevel gear (10) is meshed and installed at the upper end of the first bevel gear (9), and the upper end of the second bevel gear (10) is fixedly installed at the lower end of the threaded rod (11). The threaded rod (11) is rotationally connected to the inside of the fixing column (2). Four universal wheels are arranged at the lower end of the base (1).

3. The Chinese speech teaching device according to claim 2, wherein: The surface of the threaded rod (11) is threadedly connected to the inside of the elevating block (3). Limiting plates (12) are fixedly installed on the left and right sides of the elevating block (3). Openings are formed on the left and right sides of the fixing column (2), and the limiting plates (12) are correspondingly arranged with the openings on the left and right sides of the fixing column (2).

4. A Chinese voice teaching device according to claim 3, characterized in that: A rotating block (4) is rotationally installed at the upper end of the elevating block (3), and the upper end of the rotating block (4) is rotationally connected to an elevation adjusting block (5). A rubber ring (13) is arranged on the outer side of the rear end of the elevation adjusting block (5), and the outer side of the rubber ring (13) is attached to the upper end of the rotating block (4). The front end of the elevation adjusting block (5) is fixedly connected to the display screen (6).

5. A Chinese speech teaching device according to claim 1, characterized in that: The positioning and anti-slip mechanism is provided with a positioning rod (14), and the left and right sides of the positioning rod (14) are fixedly installed at the lower end of the base (1). A movable block (15) is installed through the surface of the positioning rod (14). An inclined rod (16) is rotationally installed at the lower end of the movable block (15), and the lower end of the inclined rod (16) is rotationally installed on the control board (17).

6. The Chinese speech teaching device according to claim 5, characterized in that: A pressure spring (18) is arranged on the outer side of the movable block (15), and the outer side of the pressure spring (18) is arranged at the bottom of the base (1). An anti-slip pad is fixedly installed at the lower end of the control board (17).

7. The Chinese speech teaching device according to claim 6, wherein: The front and rear ends of the control board (17) are fixedly installed with clamping plates (20), and the upper ends of the clamping plates (20) penetrate through the base (1). A dial plate (21) is fixedly installed on the outer side of the clamping plate (20), and a clamping groove (22) is opened at the upper end of the clamping plate (20).

8. A Chinese voice teaching device according to claim 7, characterized in that: A fixing block (23) is arranged on the surface of the base (1). A pull rod (24) is installed through the inside of the fixing block (23). A locking block (25) is fixedly installed on the inner side of the pull rod (24). The inner side of the locking block (25) is inclined. The locking block (25) is arranged corresponding to the clamping groove (22). A positioning socket (26) is nested and installed at the upper end of the fixing block (23). The lower end of the positioning socket (26) is located on the outer side of the locking block (25). A traction rope (27) is fixedly installed at the upper end of the positioning socket (26), and the upper end of the traction rope (27) is fixedly installed at the lower end of the limiting plate (12).

9. The Chinese speech teaching device according to claim 1, characterized in that: The self-cleaning mechanism is provided with an air jet port (30). The rear end of the air jet port (30) is fixedly installed on the surface of the display screen (6). The output end of the display screen (6) is aligned with the screen of the display screen (6). The upper end of the air jet port (30) is communicated with an air bag (28) through a telescopic bellows (29).

10. A Chinese speech teaching device according to claim 9, characterized in that: The air bag (28) is made of elastic material. The air bag (28) and the limiting plate (12) form a pressing structure. A one-way air inlet (31) is installed through the upper end of the air bag (28), and a one-way valve is arranged inside the one-way air inlet (31).

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