Safety inspection device for surface mine

Abstract

The invention belongs to the technical field of mine inspection, and discloses a surface mine safety inspection device which comprises a vehicle body and a camera installed on the vehicle body, and further comprises a first hollow plate movably arranged outside a guide rod in a sleeving mode, and a second hollow plate movably arranged outside the guide rod in a sleeving mode. Gas compression assemblies used for receiving gas in the reciprocating piston assembly are installed on the opposite sides of the two sets of auxiliary plates. According to the scheme, the pressing plate presses the pressing valve to be in an open state, and at the moment, gas in the reciprocating piston assembly is injected into the gas storage cylinder in a one-way mode through the first one-way valve to be stored and compressed, so that the spring bayonet lock is pushed to accumulate force to be compressed and disengaged from the clamping groove; at the moment, the pressure in the air storage cylinder and the guide cylinder pushes the cylindrical rod and enables the hollow plate I to quickly move upwards under the limitation of the guide rod, and meanwhile, the cleaning head quickly wipes the lens of the camera, so that the problem that the imaging quality is influenced by a slow windscreen wiper under some instantaneous working conditions is avoided.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of mine inspection, and particularly relates to an open-pit mine safety inspection device. BACKGROUND

[0002] The robot generally adopts a crawler-type walking mechanism, so that it has good obstacle-crossing capability and can adapt to complex terrains such as slopes and gravel roads of the open-pit mine.

[0003] The robot can inspect key equipment such as a belt conveyor along a predetermined route, wherein the camera on the robot can provide overall situational awareness of the surrounding environment for a remote operator or an autonomous navigation system, avoid blind areas, and also automatically track and zoom in on suspicious targets or moving objects.

[0004] In a mine area, dust is usually diffused, which causes dust to adhere to the glass in front of the camera, seriously affecting image clarity and recognition effect. Therefore, an operator sets a wiper structure in front of the lens to regularly or as needed remove dust on the glass surface, so as to ensure that the camera continuously obtains high-quality pictures. However, generally, the wiper swings slowly, so in some transient working conditions, the slowly swinging wiper is difficult to quickly restore the field of view, which causes delay or omission of key inspection data collection, and further affects the imaging quality.

[0005] Therefore, in order to solve the above problems, an open-pit mine safety inspection device is provided. SUMMARY

[0006] To solve the problems in the background art, the application provides an open-pit mine safety inspection device, which solves the problem that a slow wiper affects the imaging quality in some transient working conditions.

[0007] To achieve the above purpose, the application provides the following technical scheme: an open-pit mine safety inspection device, comprising a vehicle body and a camera mounted thereon, a bracket part of the camera is provided with a supporting plate, a group of guide rods are mounted on the camera, and a sub plate is fixedly connected to the top end and the bottom end of the guide rod, further comprising: a hollow plate one movably sleeved outside the guide rod, a motor and a reciprocating piston assembly driven by the motor are mounted on the camera, and a gas compression assembly for receiving gas in the reciprocating piston assembly is mounted on the opposite side of the two groups of sub plates. A cleaning head is fixedly connected to the side of the camera of the hollow plate one, and a pressing plate is fixedly connected to the two ends of the hollow plate one. The gas compression assembly includes guide cylinders fixed to both ends of the sub-plate. A gas storage cylinder is fixedly connected to the bottom of the guide cylinder. A press valve that can be aligned with the pressure plate in the vertical direction and a one-way valve for restricting gas from entering the gas storage cylinder in one direction are installed on the gas storage cylinder. A cylindrical rod is fixed to both ends of the cleaning head. One end of the cylindrical rod can be sleeved in the guide cylinder and seal the bottom of the guide cylinder. The cylindrical rod has slots at both ends. A spring pin that can be initially locked into the slot is provided at the bottom of the guide cylinder. Initially, the pressure plate can press the push valve at the same height to open it.

[0008] Preferably, the end of the slot is provided with an inclined surface, which can compress the spring pin to store force.

[0009] Preferably, the reciprocating piston assembly includes a sleeve fixed to the camera, a piston body movably sleeved inside the sleeve, a limit rod symmetrically fixed to one end of the piston body, the limit rod movably sleeved in the sleeve, a slider fixedly sleeved inside the piston body, a one-way valve two for unidirectionally inputting gas into the sleeve installed on the sleeve, a three-way pipe one fixedly connected to the part of the sleeve between the one-way valve two and the piston body, and the other two ends of the three-way pipe one can be connected to the gas storage tank on the same side; The output end of the motor is fixedly connected to a transmission crankshaft, and the other end of the transmission crankshaft is fixedly connected to a reciprocating screw. The slider is movably sleeved on the outside of the reciprocating screw.

[0010] Preferably, hollow plate two is installed on both the upper and lower parts of hollow plate one, and a scraper that can contact the camera lens is fixed to the side of hollow plate two facing the camera.

[0011] Preferably, the two ends of the hollow plate one are movably fitted with tie rods, the hollow plate two is in contact with the hollow plate one, and the hollow plate two is movably fitted outside the tie rods, and the maximum distance between the two hollow plates two is less than the length of the tie rods.

[0012] Preferably, the camera is also equipped with two sets of air supply components; The gas delivery assembly includes an outer cylinder fixedly mounted on a camera, a piston movably mounted inside the outer cylinder, a connecting rod hinged to the outside of the piston, the other end of the connecting rod hinged to a transmission crankshaft, a plurality of one-way valves II communicating unidirectionally with the cavity of the outer cylinder II mounted on the piston, a three-way pipe II fixedly connected to one end of the outer cylinder II, the other two ends of the three-way pipe II communicating with the ends of two other hollow plates II, and a one-way valve I for restricting gas from entering the three-way pipe II unidirectionally at the end of the outer cylinder II communicating with the three-way pipe II. The portion of the piston located outside the two one-way valve discs can be fitted with a filter cloth, and exhaust ports are provided on opposite sides of the two hollow plates.

[0013] Preferably, the hollow plate two has a recess on the side away from the scraper; the upper and lower parts of the hollow plate one are both fixed with spring pieces that can be inserted into the recess of the hollow plate two.

[0014] Preferably, in the initial state, the exhaust port on the lower hollow plate 2 is blocked by the sub-plate; after the hollow plate 1 moves upward, the exhaust port on the upper hollow plate 2 will be blocked by another set of sub-plates.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The above solution uses a pressure plate to press the pressure valve to open it. At this time, the gas in the reciprocating piston assembly is injected into the air tank through the one-way valve and stored and compressed. At this time, the bottom of the guide cylinder is blocked by the cylindrical rod, and the pressure at the bottom of the air tank and the guide cylinder increases, thereby pushing the spring pin to be compressed and disengaged from the slot. At this time, the pressure in the air tank and the guide cylinder pushes the cylindrical rod and causes the hollow plate to move upward quickly under the limit of the guide rod. At the same time, the cleaning head quickly wipes the lens of the camera, avoiding the problem that slow wipers may affect the image quality under some instantaneous working conditions. The above solution also drives the second hollow plate upward as the first hollow plate moves upward, allowing the scraper to further remove dust and residual water droplets from the camera lens, thereby improving the cleaning effect.

[0016] The above solution uses a motor to drive the transmission crankshaft to rotate, causing the connecting rod and piston to reciprocate inside the outer cylinder. The gas inside the outer cylinder is then input into the hollow plate through the three-way pipe and discharged through the exhaust port. This ensures that after the hollow plates are wiped and scraped clean, the lens remains clean during continuous operation, and reduces the amount of dust adhering to the lens. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the installation structure of the camera of the present invention; Figure 2 This is a schematic diagram of the overall structure of the present invention; Figure 3 This is a schematic diagram of the installation of the hollow plate of the present invention; Figure 4 This is a partial cross-sectional view of the guide cylinder of the present invention; Figure 5 This is a schematic diagram of the mating structure of hollow plate one and hollow plate two of the present invention; Figure 6 This is a side cross-sectional view of the hollow plate of the present invention. Figure 7 This is a schematic diagram of the structure of the hollow plate II of the present invention; Figure 8This is a side cross-sectional view of the sleeve of the present invention; Figure 9 This is a schematic diagram showing the disassembled structure of the reciprocating piston assembly of the present invention.

[0018] In the diagram: 1. Vehicle body; 2. Camera; 21. Support plate; 22. Guide rod; 23. Sub-plate; 3. Hollow plate one; 31. Cleaning head; 32. Pressure plate; 33. Pull rod; 34. Spring; 4. Gas compression assembly; 41. Guide cylinder; 42. Air storage cylinder; 43. One-way valve one; 44. Press valve; 45. Spring pin; 46. Cylindrical rod; 47. Slot; 471. Inclined surface; 5. Hollow plate two; 1. Scraper; 52. Exhaust port; 6. Reciprocating piston assembly; 61. Sleeve; 62. Piston body; 63. Limiting rod; 64. Slider; 65. Three-way pipe one; 66. One-way valve two; 7. Motor; 71. Drive crankshaft; 72. Reciprocating screw; 8. Gas delivery assembly; 81. Outer cylinder; 82. Piston; 83. Connecting rod; 84. Three-way pipe two; 85. One-way valve disc one; 86. One-way valve disc two. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] like Figures 1 to 9 As shown, the present invention provides a safety inspection device for open-pit mines, including a vehicle body 1 and a camera 2 installed on it. A support plate 21 is installed on the bracket part of the camera 2. A set of guide rods 22 is installed on the camera 2, and a sub-plate 23 is fixedly connected to the top and bottom of the guide rods 22. The device also includes a hollow plate 3 movably sleeved outside the guide rods 22. A motor 7 and a reciprocating piston assembly 6 driven by the motor 7 are installed on the camera 2. A gas compression assembly 4 for receiving gas in the reciprocating piston assembly 6 is installed on one side of the two sets of sub-plates 23. A cleaning head 31 is fixedly connected to the side of the hollow plate 3 facing the camera 2, and pressure plates 32 are fixedly connected to both ends of the hollow plate 3. The gas compression assembly 4 includes a guide cylinder 41 fixed to both ends of the sub-plate 23. The bottom of the guide cylinder 41 is fixedly connected to a gas storage cylinder 42. The gas storage cylinder 42 is equipped with a press valve 44 that can coincide with the pressure plate 32 in the vertical direction and a one-way valve 43 for restricting gas from entering the gas storage cylinder 42 in one direction. The cleaning head 31 is fixed to both ends with cylindrical rods 46. One end of the cylindrical rod 46 can be sleeved in the guide cylinder 41 and seal the bottom of the guide cylinder 41. The cylindrical rod 46 has slots 47 at both ends. The bottom of the guide cylinder 41 is provided with a spring pin 45 that can be initially locked into the slot 47. The end of the slot 47 is provided with a slope 471, which can compress the spring pin 45 to store force. Initially, the pressure plate 32 can press the pressure valve 44 at the same height to open it; The reciprocating piston assembly 6 includes a sleeve 61 fixed to the camera 2. A piston body 62 is movably sleeved inside the sleeve 61. A limit rod 63 is symmetrically fixed to one end of the piston body 62. The limit rod 63 is movably sleeved in the sleeve 61. A slider 64 is fixedly sleeved inside the piston body 62. A one-way valve 66 for unidirectionally inputting gas into the sleeve 61 is installed on the sleeve 61. A three-way pipe 65 is fixedly connected to the part of the sleeve 61 between the one-way valve 66 and the piston body 62. The other two ends of the three-way pipe 65 can be connected to the gas storage tank 42 on the same side. The output end of the motor 7 is fixedly connected to the transmission crankshaft 71, and the other end of the transmission crankshaft 71 is fixedly connected to the reciprocating screw 72. The slider 64 is movably sleeved on the outside of the reciprocating screw 72.

[0021] Using the above scheme, initially, the pressure plate 32 presses the pressure valve 44 to open it. At this time, the gas in the reciprocating piston assembly 6 is injected into the air storage cylinder 42 through the one-way valve 43 and stored and compressed. At this time, the bottom of the guide cylinder 41 is blocked by the cylindrical rod 46, and the pressure at the bottom of the air storage cylinder 42 and the guide cylinder 41 increases, thereby pushing the spring latch 45 to be compressed and disengaged from the slot 47. At this time, the pressure in the air storage cylinder 42 and the guide cylinder 41 pushes the cylindrical rod 46 and, under the limit of the guide rod 22, causes the hollow plate 3 to move upward quickly. At the same time, the cleaning head 31 quickly wipes the lens of the camera 2, avoiding the problem that the slow wipers in some instantaneous working conditions will affect the image quality. It is worth noting that after the hollow plate 3 moves upward quickly, it will drive the top of the cylindrical rod 46 into the corresponding guide cylinder 41 above. At this time, the slot 47 opened at the top of the cylindrical rod 46 will be limited by the corresponding spring pin 45, thus facilitating the next operation of the device. Furthermore, when the pressure plate 32 moves upward, it releases the pressure on the bottom pressing valve 44, thereby closing the corresponding pressing valve 44. At this time, the corresponding air storage cylinder 42 cannot store power. When the pressure plate 32 moves upward, its top presses the upper pressing valve 44 to open it. At this time, the corresponding air storage cylinder 42 will store power, thereby ensuring that the pressure supplied by the reciprocating piston assembly 6 can meet the needs of the air storage cylinder 42 to push the hollow plate 3 to move up or down quickly.

[0022] like Figure 2 and Figures 5-9 As shown, hollow plate 2 5 is installed on both the upper and lower parts of hollow plate 1 3. A scraper 51 that can contact the lens part of the camera 2 is fixed to the side of hollow plate 2 3. Two sets of gas supply components 8 are also installed on the camera 2. The gas supply component 8 includes an outer cylinder 81 fixedly installed on the camera 2, a piston 82 movably installed inside the outer cylinder 81, a connecting rod 83 hinged to the outside of the piston 82, the other end of the connecting rod 83 hinged to the transmission crankshaft 71, a number of one-way valves 86 that communicate unidirectionally with the cavity of the outer cylinder 81 are installed on the piston 82, a three-way pipe 84 is fixedly connected to one end of the outer cylinder 81, the other two ends of the three-way pipe 84 are connected to the ends of two other hollow plates 5, and a one-way valve 85 for restricting gas from entering the three-way pipe 84 unidirectionally is installed at the end of the outer cylinder 81 that communicates with the three-way pipe 84. The portion of the piston 82 located outside the one-way valve disc 86 can be fitted with a filter cloth, and exhaust ports 52 are provided on opposite sides of the two hollow plates 25.

[0023] Using the above method, the hollow plate 3 will also drive the hollow plate 5 to move upward during the process, so that the scraper 51 can further scrape and clean the dust and residual water droplets on the lens of the camera 2, thereby improving the cleaning effect. At the same time, the transmission crankshaft 71 is driven to rotate by the motor 7, causing the connecting rod 83 and piston 82 to reciprocate inside the outer cylinder 81. The gas inside the outer cylinder 81 is fed into the hollow plate 5 through the three-way pipe 84 and discharged through the exhaust port 52. This ensures that after the hollow plate 3 and hollow plate 2 are wiped and scraped clean, the lens of the camera 2 remains clean during continuous operation, and reduces the amount of dust adhering to the lens. It is worth noting that the diameter of the outer cylinder 81 is larger than the diameter of the sleeve 61, thus ensuring that the gas supply assembly 8 can provide a stable and sufficient amount of gas to the hollow plate 2 5.

[0024] like Figures 3-7As shown, the two ends of the hollow plate 1 3 are movably fitted with tie rods 33, the hollow plate 2 5 is in contact with the hollow plate 1 3, and the hollow plate 2 5 is movably fitted outside the tie rods 33. The maximum distance between the two hollow plates 2 5 is less than the length of the tie rods 33. A recess is provided on the side of the hollow plate 2 5 away from the scraper 51. Both the upper and lower parts of the hollow plate 3 are fixed with spring clips 34 that can be inserted into the recesses of the hollow plate 5.

[0025] Using the above scheme, by setting the lever 33, when the hollow plate 3 moves upward, the hollow plate 5 below will remain stationary due to its own inertia until the lever 33 pulls the hollow plate 5 upward, thereby leaving sufficient distance between the hollow plate 3 and the hollow plate 5 below it to improve the cleaning of the camera lens by the scraper 51. Furthermore, after the hollow plate 3 moves upward and stops, the hollow plate 5 below it will be compressed by its own inertia, causing the spring 34 to be stuck into the recess on the hollow plate 5. At this time, the hollow plate 3 and the hollow plate 5 can still maintain a whole to prevent the hollow plate 5 from falling and blocking the lens.

[0026] like Figures 3-7 As shown, in the initial state, the exhaust port 52 on the lower hollow plate 2 5 is blocked by the sub-plate 23; after the hollow plate 1 3 moves upward, the exhaust port 52 on the upper hollow plate 2 5 will be blocked by another set of sub-plates 23. By adopting the above scheme, and by using two sets of hollow plates 25 with their exhaust ports 52 alternating with the position of hollow plate 13, the air volume can be increased while the air supply pressure of the air delivery component 8 can be reduced.

[0027] Working principle and usage process of this invention: Initially, the pressure plate 32 presses the pressure valve 44 to open it. At this time, the gas in the reciprocating piston assembly 6 is injected into the air storage cylinder 42 through the one-way valve 43 and stored and compressed. At this time, the bottom of the guide cylinder 41 is blocked by the cylindrical rod 46. The pressure at the bottom of the air storage cylinder 42 and the guide cylinder 41 increases, thereby pushing the spring pin 45 to be compressed and disengaged from the slot 47. At this time, the pressure in the air storage cylinder 42 and the guide cylinder 41 pushes the cylindrical rod 46 and, under the limit of the guide rod 22, causes the hollow plate 3 to move upward quickly. At the same time, the cleaning head 31 quickly wipes the lens of the camera 2. As the hollow plate 3 moves upward, it also drives the hollow plate 5 upward, allowing the scraper 51 to further scrape and clean the dust and residual water droplets on the lens of the camera 2, thereby improving the cleaning effect.

[0028] Initially, the motor 7 drives the transmission crankshaft 71 to rotate, causing the connecting rod 83 and piston 82 to reciprocate within the outer cylinder 81. The gas inside the outer cylinder 81 is then fed into the hollow plate 5 through the three-way pipe 84 and discharged through the exhaust port 52. This ensures that after the hollow plates 3 and 5 wipe and scrape the lens of the camera 2, the lens remains clean during continuous operation, and reduces the amount of dust adhering to the lens.

[0029] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0030] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An open-pit mine safety inspection device, comprising a vehicle body (1) and a camera (2) mounted thereon, a supporting plate (21) is mounted on the supporting part of the camera (2), a set of guide rods (22) are mounted on the camera (2), and a sub-plate (23) is fixedly connected to the top and bottom of the guide rod (22), characterized in that, Also include: The hollow plate one (3) is movably sleeved outside the guide rod (22), the camera (2) is provided with a motor (7) and a reciprocating piston assembly (6) reciprocating driven by the motor (7), and two groups of the auxiliary plate (23) are provided with a gas compression assembly (4) for receiving the gas in the reciprocating piston assembly (6) on opposite sides; The hollow plate one (3) is movably sleeved outside the guide rod (22), the camera (2) is provided with a motor (7) and a reciprocating piston assembly (6) reciprocating driven by the motor (7), and two groups of the auxiliary plate (23) are provided with a gas compression assembly (4) for receiving the gas in the reciprocating piston assembly (6) on opposite sides; The gas compression assembly (4) comprises guide cylinders (41) fixedly connected to the two ends of the auxiliary plate (23), the bottom of the guide cylinder (41) is fixedly connected with a gas storage cylinder (42), the gas storage cylinder (42) is provided with a pressing valve (44) which can coincide with the pressing plate (32) in the vertical direction and a one-way valve (43) for limiting the one-way entry of gas into the gas storage cylinder (42), the two ends of the cleaning head (31) are fixedly connected with a cylindrical rod (46), one end of the cylindrical rod (46) can be sleeved in the guide cylinder (41) and seal the bottom of the guide cylinder (41), the two ends of the cylindrical rod (46) are provided with clamping grooves (47), and the bottom of the guide cylinder (41) is provided with a spring clamping pin (45) which can be clamped into the clamping groove (47) at the beginning; At the beginning, the pressing plate (32) can press the pressing valve (44) of the same height to make it open.

2. The safety inspection device for open-pit mine according to claim 1, characterized in that: The end of the clamping groove (47) is provided with an inclined surface (471), and the inclined surface (471) can extrude the spring clamping pin (45) to store force.

3. The safety inspection device for open-pit mine according to claim 1, characterized in that: The reciprocating piston assembly (6) comprises a sleeve (61) fixedly connected to the camera (2), the sleeve (61) movably sleeved with a piston body (62) inside, the piston body (62) is symmetrically fixedly connected with a limiting rod (63) at one end, the limiting rod (63) movably sleeved in the sleeve (61), the piston body (62) is fixedly sleeved with a sliding block (64) inside, the sleeve (61) is provided with a one-way valve (66) for one-way input of gas into the sleeve (61), the part of the sleeve (61) between the one-way valve (66) and the piston body (62) is fixedly connected with a three-way pipe (65), and the other two ends of the three-way pipe (65) can be communicated with the same side of the gas storage cylinder (42); The output end of the motor (7) is fixedly connected with a transmission crankshaft (71), and the other end of the transmission crankshaft (71) is fixedly connected with a reciprocating screw rod (72), and the sliding block (64) is movably sleeved outside the reciprocating screw rod (72).

4. The safety inspection device for open-pit mine according to claim 3, characterized in that: The upper and lower parts of the hollow plate one (3) are provided with hollow plate two (5), and the cleaning head (31) is movably sleeved outside the guide rod (22), the camera (2) is provided with a motor (7) and a reciprocating piston assembly (6) reciprocating driven by the motor (7), and two groups of the auxiliary plate (23) are provided with a gas compression assembly (4) for receiving the gas in the reciprocating piston assembly (6) on opposite sides; 5. The safety inspection device for open-pit mine according to claim 4, characterized in that: The two ends of the hollow plate one (3) are movably sleeved with a pull rod (33), the hollow plate two (5) is in contact with the hollow plate one (3), and the hollow plate two (5) is movably sleeved outside the pull rod (33), and the maximum distance between the two hollow plate two (5) is less than the length of the pull rod (33).

6. The safety inspection device for open-pit mine according to claim 4, characterized in that: The camera (2) is also provided with two groups of gas conveying assemblies (8); The gas feeding assembly (8) comprises an outer cylinder (81) fixedly installed on the camera (2), a piston (82) movably installed in the outer cylinder (81), a connecting rod (83) hingedly connected to the outer side of the piston (82), the other end of the connecting rod (83) hingedly connected to a transmission crankshaft (71), a plurality of one-way valve petals (86) installed on the piston (82) and unidirectionally communicated with the cavity of the outer cylinder (81), a three-way pipe (84) fixedly and communicatively connected to one end of the outer cylinder (81), the other two ends of the three-way pipe (84) communicated with the end portions of the other two hollow plates (5), and a one-way valve petal (85) installed on the end of the outer cylinder (81) and the three-way pipe (84) for limiting the one-way entry of gas into the three-way pipe (84). The part of the piston (82) located outside the one-way valve petal (86) is capable of being installed with filter cloth, and the two hollow plates (5) are provided with exhaust ports (52) on the opposite sides.

7. The safety inspection device for open-pit mine according to claim 5, characterized in that: The hollow plate (5) is provided with a recess on the side away from the scraper (51); The upper portion and the lower portion of the hollow plate (1) are fixedly connected with elastic sheets (34) capable of being clamped into the recess of the hollow plate (5).

8. The safety inspection device for open-pit mine according to claim 6, characterized in that: The exhaust port (52) on the lower hollow plate (5) in the initial state is blocked by the sub plate (23); The exhaust port (52) on the upper hollow plate (5) is blocked by the other group of sub plates (23) after the upward movement of the hollow plate (1).

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