Ventilation system for coal mine tunneling

Abstract

The present application relates to the technical field of tunneling ventilation, and particularly relates to a ventilation system for coal mine roadway tunneling, which comprises a supply air unit composed of a pressure-in fan and a positive pressure air duct and configured to press fresh air into a tunneling working face in a roadway, and an exhaust air unit composed of a pressure-out fan and a negative pressure air duct and configured to exhaust dirty air at the tunneling working face out along the roadway, wherein the negative pressure air duct is composed of a plurality of cylinder bodies; and an adjusting member is arranged between every two adjacent cylinder bodies. The present application sets the telescopic adjusting member between the adjacent negative pressure air duct cylinder bodies, so that the total length of the negative pressure air duct can be dynamically adjusted according to the advancement of the tunneling working face, without frequent disassembly and additional cylinder bodies, thereby realizing the synchronous extension of the exhaust air unit and the tunneling process, and adopting the composite structure of the elastic support and the pipe body to effectively prevent the radial deformation or collapse of the air duct due to the negative pressure, so as to ensure the effective sectional area of the ventilation channel and guarantee the exhaust efficiency.

Description

Technical Field

[0001] This invention relates to the field of tunneling ventilation technology, and more particularly to a ventilation system for tunneling in coal mines. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] During underground tunnel excavation in coal mines, an effective ventilation system is essential to ensure the breathing safety of workers and to dilute and remove harmful gases and dust. Currently, the long-pressure, short-exhaust ventilation system is a widely used ventilation method at the tunneling face. This system typically includes an air supply unit consisting of a forced-in fan and a positive-pressure duct, and an exhaust unit consisting of an exhaust fan and a negative-pressure duct. The air supply unit forces fresh air into the tunneling face, while the exhaust unit removes polluted air (including methane, coal dust, etc.) generated at the face. The two work together to create effective air circulation.

[0004] However, as the tunneling face advances, the existing ventilation system faces a practical problem: the length of the negative pressure ventilation duct cannot be extended synchronously and conveniently with the advancement of the working face. The traditional approach is to stop tunneling after a certain distance and manually disassemble, add, or replace sections of the negative pressure ventilation duct. This process is not only time-consuming and labor-intensive, affecting tunneling efficiency, but also inconvenient to operate in narrow tunnel environments. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned shortcomings by providing a ventilation system for coal mine roadway excavation.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a ventilation system for coal mine roadway excavation, comprising an air supply unit consisting of a forced-in fan and a positive pressure duct that pressurizes fresh air into the excavation face within the roadway, and an exhaust unit consisting of an exhaust fan and a negative pressure duct that discharges polluted air from the excavation face outward along the roadway, wherein the negative pressure duct is composed of multiple cylinders; An adjusting element is provided between two adjacent cylinders to adjust the total length of the negative pressure ventilation duct according to the forward movement of the tunneling face, so that the ventilation unit extends synchronously with the tunnel excavation.

[0007] Furthermore, the adjusting component includes an elastic support disposed between two adjacent cylinders and extending and retracting along the axial direction of the negative pressure duct, and a tube body covering the outside of the elastic support. The elastic support is used to provide radial support force to resist radial deformation under negative pressure. The tube expands or contracts as the elastic support extends and retracts, forming an airtight ventilation channel.

[0008] Furthermore, the tube body is made of coated fabric, and the wall surface of the tube body is provided with a double layer; The elastic support is composed of multiple inner support rings embedded in the interlayer, and the spacing between two adjacent inner support rings is equal. Each inner support ring has a fixed node at its upper end, and the fixed node extends outward and is formed on the outer surface of the tube body. Each fixed node is provided with a supporting outer frame, and the outside of the tube body is provided with a pitch-changing mechanism. The variable pitch mechanism is used to synchronously adjust the spacing between the two supporting outer frames and to increase or decrease the length of the tube body.

[0009] Furthermore, the upper end of the fixed node extends and connects to the supporting outer frame; The variable pitch mechanism includes telescopic units corresponding to and disposed on each of the fixed nodes; The telescopic unit includes two cross-connected first connecting plates, and the intersection of the two first connecting plates is located on the axis of the fixed node and is rotatably connected to the fixed node. The two ends of the first connecting plates are provided with connecting holes a, and the connecting holes a are provided with pins a connecting two adjacent telescopic units. The two first connecting plates formed on the telescopic units at the beginning and end are each provided with two second connecting plates through pins b. The two second connecting plates are cross-connected on the side away from the telescopic unit and are provided with connecting holes b. The connecting holes b are connected to the corresponding fixed nodes through pins c.

[0010] Furthermore, it also includes modular guide rails installed at the top of the tunnel, which are composed of multiple slide rail units spliced ​​together end to end; A sliding component, corresponding to the slide rail unit, is provided to allow the negative pressure duct to slide along the modular guide rail; The supporting outer frame at the corresponding connection hole b is fixedly connected to a sliding component, and a locking device is provided on the sliding component. The locking device is used to temporarily limit the supporting outer frame connected to the sliding component to a predetermined position on the modular guide rail. A hydraulic rod is provided on the supporting outer frame at the corresponding other connecting hole b, and the fixed end of the hydraulic rod is located on another supporting outer frame adjacent to the supporting outer frame; The hydraulic rod is activated to drive the outermost support frame to move. The telescopic units connected to the middle support frames stretch or compress, and the spacing between the adjacent support frames is adjusted synchronously to strengthen the support of the tube body during its expansion and contraction.

[0011] Furthermore, the end of the cylinder is provided with a splicing mechanism that connects to the tube body.

[0012] Furthermore, the splicing mechanism includes a fixed ring, a first annular concave surface disposed on the fixed ring and opening to the side of the cylinder, a first movable ring rotatably disposed on the inner surface of the first annular concave surface, and a plurality of first positioning blocks evenly disposed on the first movable ring; The cylinder body is provided with a plurality of first positioning grooves on the connecting side corresponding to the first movable ring. Each first positioning groove is composed of a guide groove adapted to the axial insertion of the first positioning block and an arc groove formed in the guide groove and extending along the circumference of the cylinder body.

[0013] Furthermore, a second annular concave surface is provided on the fixed ring and on the other side opposite to the first annular concave surface. The second annular concave surface corresponds to the opening on the side of the tube body. A second movable ring is rotatably provided on the inner surface of the second annular concave surface. A plurality of second positioning blocks are evenly provided on the second movable ring. Multiple second positioning grooves are evenly provided on the connecting side of the corresponding second movable ring on the tube body. Each second positioning groove is also composed of a guide groove and an arc groove. The guide groove is adapted to the axial insertion of the second positioning block, and the arc groove is opened on the outer wall of the tube body and is used to limit the connection by allowing the second positioning block to rotate circumferentially.

[0014] Furthermore, both the first and second movable rings have meshing surfaces on their opposing end faces, and a gear rotating on the fixed ring is disposed between the two meshing surfaces.

[0015] The beneficial effects of this invention are reflected in: This invention, by setting a retractable adjusting component between adjacent negative pressure ventilation duct bodies, allows the total length of the negative pressure ventilation duct to be dynamically adjusted according to the advancement of the tunneling face, eliminating the need for frequent disassembly and addition of duct bodies. This achieves synchronous extension of the ventilation unit with the tunneling process. Furthermore, the composite structure of the elastic support and the duct body effectively prevents the ventilation duct from radially deforming or collapsing due to negative pressure, ensuring the effective cross-sectional area of ​​the ventilation channel and guaranteeing ventilation efficiency. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the arrangement in a tunnel according to an embodiment of the present invention; Figure 2 This is a perspective view of a negative pressure ventilation duct according to an embodiment of the present invention; Figure 3 This is a separate view of two spliced ​​cylindrical bodies according to an embodiment of the present invention; Figure 4 This is a half-sectional view of two spliced ​​cylindrical bodies according to an embodiment of the present invention; Figure 5 for Figure 4 Enlarged view of point A in the middle; Figure 6 This is a perspective view of a cylindrical body with an adjustment component assembled on it, according to an embodiment of the present invention. Figure 7 This is a perspective view of the cylinder body according to an embodiment of the present invention; Figure 8 This is a perspective view of a fixing ring according to an embodiment of the present invention; Figure 9 This is a half-section perspective view of a fixing ring according to an embodiment of the present invention.

[0017] In the picture: 100. Forced-in fan; 101. Positive pressure duct; 102. Exhaust fan; 103. Negative pressure duct; 1. Duct body; 11. First positioning groove; 2. Adjusting component; 21. Elastic support; 211. Inner support ring; 212. Fixed node; 22. Tube body; 221. Second positioning groove; 23. Support frame; 24. Pitch-changing mechanism; 241. First connecting plate; 242. Second connecting plate; 25. Hydraulic rod; 3. Modular guide rail; 4. Sliding component; 5. Splicing mechanism; 51. Fixed ring; 52. First annular concave surface; 53. First movable ring; 54. First positioning block; 55. Second annular concave surface; 56. Second movable ring; 57. Second positioning block; 6. Gear. Detailed Implementation

[0018] 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 a part of the embodiments of the present invention, and not all of them. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. 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.

[0019] Example 1 Please see Figure 1-9 This invention discloses a ventilation system for coal mine roadway excavation, installed in underground coal mine roadways. The system mainly includes an air supply unit and an exhaust unit. The air supply unit consists of a forced-in fan 100 and a positive pressure duct 101, used to force fresh air into the excavation face. The exhaust unit consists of an exhaust fan 102 and a negative pressure duct 103, used to exhaust polluted air containing methane and coal dust generated at the excavation face.

[0020] To address the issue of the negative pressure ventilation duct 103 extending as the tunneling face advances, in this embodiment, the negative pressure ventilation duct 103 is composed of multiple rigid cylinders 1, with an adjusting member 2 positioned between each pair of adjacent cylinders 1. This adjusting member 2 is used to adjust its length according to the forward movement of the tunneling face, thereby changing the overall length of the entire negative pressure ventilation duct 103. This ensures that the air intake of the ventilation unit remains close to the tunneling face, achieving synchronous extension.

[0021] Specifically, the adjusting component 2 includes an elastic support 21 that is axially extendable along the negative pressure duct 103, and a tube body 22 covering the elastic support 21. The elastic support 21 is arranged in a ring-like series and its main function is to provide sufficient radial support force to resist the negative pressure generated when the exhaust fan 102 is working, preventing the tube body 22 from being sucked flat. The tube body 22 is made of high-strength, flame-retardant, and antistatic coated fabric material, which has good airtightness and flexibility, and can naturally expand or contract with the extension and contraction of the elastic support 21 to form a sealed ventilation channel.

[0022] Example 2 Based on Example 1, this embodiment further optimizes the structure of the adjusting member 2 to achieve more precise and stable length adjustment.

[0023] Specifically, the inner wall of the tube body 22 is provided with a sandwich layer. The elastic support 21 is specifically composed of multiple independent inner support rings 211, which are equally spaced and embedded in the sandwich layer of the tube body 22. The upper end of each inner support ring 211 (the end facing the top of the tunnel in the installed state) is provided with a fixing node 212, which extends from the inside of the tube body 22 through the sandwich layer to the outer surface of the tube body 22, forming a raised connection point. On the outside of the tube body 22, a support frame 23 is fixedly installed on each fixing node 212. All support frames 23 are connected to a pitch-changing mechanism 24. The pitch-changing mechanism 24 is used to synchronously and uniformly change the distance between two adjacent support frames 23, thereby driving the inner support rings 211 to move and realize the overall increase or decrease in the length of the tube body 22.

[0024] like Figure 6As shown, the variable pitch mechanism 24 consists of a set of telescopic units connected end-to-end, each telescopic unit corresponding to a fixed node 212. Each telescopic unit includes two first connecting plates 241 that intersect in an X-shape, and their intersection is rotatably connected to the fixed node 212 via a pin. Each first connecting plate 241 has connecting holes a at both ends, and the ends of the first connecting plates 241 corresponding to two adjacent telescopic units are hinged together via pin a. Second connecting plates 242 are additionally connected to the telescopic units at the beginning and end. Specifically, the ends of the two first connecting plates 241 on the fixed node 212 at the beginning or end are respectively connected to a second connecting plate 242 via pin b, and the other ends of the two second connecting plates 242 intersect each other and are connected to another fixed node 212 (which can be an adjacent or designated fixed node) via connecting holes b and pin c. This forms a telescopic scissor-type linkage mechanism.

[0025] Example 3 In order to achieve automatic or semi-automatic driving of the adjusting component 2 and ensure its stability during the extension process, this embodiment introduces a guide rail and a power system.

[0026] like Figure 1 As shown, a modular guide rail 3 is installed on the inner top of the tunnel. The guide rail 3 is composed of multiple standard-length slide rail units spliced ​​together end to end. The negative pressure ventilation duct 103 is suspended on the modular guide rail 3 by multiple sliding parts 4 and can slide freely along the guide rail 3.

[0027] Specifically, a supporting outer frame 23 located at the front end of the negative pressure ventilation duct 103 (near the tunneling face) is fixedly connected to a sliding component 4. The sliding component 4 is equipped with a locking device (e.g., a pneumatic or electromagnetic brake, not shown in the figure) to temporarily lock it at a certain position on the guide rail 3. A supporting outer frame 23 located at the rear end (away from the tunneling face) is designated as the active end, and a hydraulic rod 25 is installed on it. The cylinder (fixed end) of this hydraulic rod 25 is connected to another adjacent supporting outer frame 23 (i.e., the second supporting outer frame 23 at the rear end).

[0028] When the negative pressure ventilation duct 103 needs to be extended forward, first loosen the locking device, then activate the hydraulic rod 25 to extend. The thrust of the hydraulic rod 25 drives the foremost support frame 23 to move forward. Since the middle support frames 23 are interconnected through the X-shaped pitch mechanism 24, this movement causes the spacing between all support frames 23 to increase synchronously and uniformly, thereby stretching the elastic support 21 and the tube body 22. After reaching the required length, stop the hydraulic rod 25 and activate the locking device again to lock the front sliding part 4 onto the guide rail 3, maintaining the length. When shortening is required, the hydraulic rod 25 retracts, causing the spacing between the support frames 23 to decrease synchronously.

[0029] Example 4 This embodiment focuses on describing the connection method between the cylinder 1 and the adjusting component 2 (tube body 22), such as... Figure 7 , Figure 8 and Figure 9 As shown.

[0030] A splicing mechanism 5 is provided at the end of the cylinder 1. This splicing mechanism 5 includes a central fixing ring 51. A first annular concave surface 52 is formed on the side of the fixing ring 51 facing the cylinder 1, and a first movable ring 53 is rotatably mounted within the first annular concave surface 52. Multiple first positioning blocks 54 are evenly distributed on the inner surface of the first movable ring 53. Correspondingly, a first positioning groove 11 is formed on the connecting end face of the cylinder 1, corresponding to the number and position of the first positioning blocks 54. Each first positioning groove 11 is L-shaped and consists of an axial guide groove and a circumferential arc groove.

[0031] A second annular concave surface 55 is formed on the side of the fixed ring 51 facing the tube body 22, and a second movable ring 56 is rotatably installed within the second annular concave surface 55. Multiple second positioning blocks 57 are evenly distributed on the inner surface of the second movable ring 56. Correspondingly, a second positioning groove 221, also L-shaped, is provided at the connecting end of the tube body 22, corresponding to the number and position of the second positioning blocks 57.

[0032] During connection, the first positioning block 54 of the first movable ring 53 is aligned with the guide groove of the first positioning groove 11 on the cylinder 1 and inserted. Then, the first movable ring 53 is rotated to slide the first positioning block 54 into the arc groove portion, thereby achieving axial locking. Similarly, the second movable ring 56 is rotated to screw the second positioning block 57 into the arc groove of the second positioning groove 221 of the tube body 22, thereby achieving locking with the tube body 22.

[0033] To make operation easier and achieve synchronous locking, such as Figure 5 As shown, gear meshing surfaces (e.g., internal or external gear rings) can be provided on the opposing end faces of the first movable ring 53 and the second movable ring 56, and one or more gears 6 can be rotatably mounted on the fixed ring 51, so that the two movable rings are connected by gear 6. In this way, by simply rotating either the first movable ring 53 or the second movable ring 56, the other can be driven to rotate synchronously in the opposite direction through the gear 6, so as to simultaneously lock or unlock the cylinder 1 and the tube body 22, which greatly improves the installation efficiency.

[0034] It should be noted that, to prevent unexpected rotation of gear 6 due to vibration or accidental contact during ventilation system operation, which could cause the first movable ring 53 or the second movable ring 56 to loosen, a locking screw (not shown in the figure) is provided on the fixed ring 51. This locking screw is screwed in radially along the fixed ring 51, with its end abutting against the tooth surface or spokes of gear 6. When adjustment of the splicing mechanism is required, the locking screw is loosened, allowing gear 6 to rotate freely; after adjustment, the locking screw is tightened, locking gear 6 and ensuring the long-term reliability of the splicing connection.

[0035] Working principle: After the tunneling face advances a certain distance, the negative pressure ventilation duct 103 needs to be extended. The operator or automatic control system first controls the exhaust fan 102 to reduce its frequency or temporarily stop it (according to safety regulations), then activates the hydraulic rod 25 (or manually drives the pitch-changing mechanism 24). The hydraulic rod 25 pushes the front support frame 23 to slide along the modular guide rail 3. Through the scissor action of the X-shaped pitch-changing mechanism 24, the spacing of all inner support rings 211 is evenly widened, and the pipe body 22 unfolds accordingly, extending the entire adjusting component 2. After reaching the predetermined length, the sliding component 4 is locked, and the exhaust fan 102 is restarted or restored to normal operation, completing one dynamic extension. Due to the presence of the adjusting component 2, the negative pressure ventilation duct 103 can be continuously and quickly adjusted in length, minimizing ventilation interruption time caused by duct extensions and ensuring continuous and effective ventilation of the tunneling face.

[0036] The electrical components described in this article are controlled automatically by a controller. The controller circuit can be implemented by a person skilled in the art through simple programming. The power supply is also common knowledge in the field. Furthermore, since this application is mainly used to protect mechanical devices, the control method and circuit connection will not be explained in detail here.

[0037] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0038] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0039] Additionally, "multiple" refers to two or more.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A ventilation system for coal mine roadway excavation, comprising an air supply unit consisting of a forced-in fan (100) and a positive pressure duct (101) that forces fresh air into the excavation face within the roadway, and an exhaust unit consisting of an exhaust fan (102) and a negative pressure duct (103) that discharges stale air from the excavation face outwards along the roadway, characterized in that: The negative pressure ventilation duct (103) is composed of multiple cylinders (1); Adjustment component (2) is provided between two adjacent cylinders (1) for adjusting the total length of the negative pressure ventilation duct (103) according to the forward movement state of the tunneling face, so that the ventilation unit extends synchronously with the tunnel excavation.

2. The ventilation system for coal mine roadway excavation according to claim 1, characterized in that: The adjusting component (2) includes an elastic support (21) disposed between two adjacent cylinders (1) and extending and retracting along the axial direction of the negative pressure air duct (103), and a tube body (22) covering the outside of the elastic support (21). The elastic support (21) is used to provide radial support force to resist radial deformation under negative pressure. The tube body (22) expands or contracts with the extension and retraction of the elastic support (21), forming an airtight ventilation channel.

3. The ventilation system for coal mine roadway excavation according to claim 2, characterized in that: The tube body (22) is made of coated cloth, and the wall of the tube body (22) is provided with a sandwich layer; The elastic support (21) is composed of multiple inner support rings (211) embedded in the interlayer, and the spacing between two adjacent inner support rings (211) is equal. Each inner support ring (211) has a fixed node (212) at its upper end, and the fixed node (212) extends outward and is formed on the outer surface of the tube body (22). Each fixed node (212) is provided with a supporting outer frame (23), and the tube body (22) is provided with a pitch mechanism (24). The variable pitch mechanism (24) is used to synchronously adjust the spacing between the two supporting outer frames (23) and to increase or decrease the length of the tube body (22).

4. The ventilation system for coal mine roadway excavation according to claim 3, characterized in that: The upper end of the fixed node (212) extends and connects to the supporting outer frame (23); The variable pitch mechanism (24) includes telescopic units corresponding to and disposed on each of the fixed nodes (212); The telescopic unit includes two cross-connected first connecting plates (241), and the intersection of the two first connecting plates (241) is located on the axis of the fixed node (212) and is rotatably connected to the fixed node (212). The two ends of the first connecting plate (241) are provided with connecting holes a, and the connecting holes a are provided with pins a connecting two adjacent telescopic units. The two first connecting plates (241) formed on the telescopic units at the beginning and end are each provided with two second connecting plates (242) through pins b. The two second connecting plates (242) are cross-connected on the side away from the telescopic unit and are provided with connecting holes b. The connecting holes b are connected to the corresponding fixed nodes (212) through pins c.

5. The ventilation system for coal mine roadway excavation according to claim 4, characterized in that: It also includes a modular guide rail (3) installed at the top of the alleyway, the modular guide rail (3) being composed of multiple slide rail units spliced ​​together end to end; A sliding component (4), corresponding to the slide rail unit, is used to allow the negative pressure duct (103) to slide along the modular guide rail (3); The supporting outer frame (23) at the corresponding connection hole b is fixedly connected to a sliding component (4), and a locking device is provided on the sliding component (4). The locking device is used to temporarily limit the supporting outer frame (23) connected to the sliding component (4) to a predetermined position on the modular guide rail (3). A hydraulic rod (25) is provided on the support frame (23) at the corresponding other connection hole b, and the fixed end of the hydraulic rod (25) is located on another support frame (23) adjacent to the support frame (23); The hydraulic rod (25) is activated to drive the outermost support frame (23) to move. The telescopic units connected to the middle support frames (23) stretch or compress and change, and the spacing between the adjacent support frames (23) is adjusted synchronously to strengthen the support of the tube body (22) during its expansion and contraction.

6. The ventilation system for coal mine roadway excavation according to claim 3, characterized in that: The end of the cylinder (1) is provided with a splicing mechanism (5) that is connected to the tube body (22).

7. The ventilation system for coal mine roadway excavation according to claim 6, characterized in that: The splicing mechanism (5) includes a fixed ring (51), a first annular concave surface (52) disposed on the fixed ring (51) and opening to the side of the cylinder (1), a first movable ring (53) is rotatably disposed on the inner surface of the first annular concave surface (52), and a plurality of first positioning blocks (54) are evenly disposed on the first movable ring (53). Multiple first positioning grooves (11) are uniformly provided on the connecting side of the cylinder (1) corresponding to the first movable ring (53). Each first positioning groove (11) is composed of a guide groove adapted to the axial insertion of the first positioning block (54) and an arc groove formed in the guide groove and extending circumferentially along the cylinder (1).

8. The ventilation system for coal mine roadway excavation according to claim 7, characterized in that: A second annular concave surface (55) is provided on the fixed ring (51) and on the other side opposite to the first annular concave surface (52). The second annular concave surface (55) corresponds to the side opening of the tube body (22). A second movable ring (56) is rotatably provided on the inner surface of the second annular concave surface (55). A plurality of second positioning blocks (57) are evenly provided on the second movable ring (56). Multiple second positioning grooves (221) are evenly provided on the connecting side of the tube body (22) corresponding to the second movable ring (56). Each second positioning groove (221) is also composed of a guide groove and an arc groove. The guide groove is adapted to the axial insertion of the second positioning block (57). The arc groove is opened on the outer wall of the tube body (22) and is used to limit the connection by rotating the second positioning block (57) circumferentially.

9. A ventilation system for coal mine roadway excavation according to claim 8, characterized in that: Both the first movable ring (53) and the second movable ring (56) have meshing surfaces on their opposite end faces, and a gear (6) that rotates on the fixed ring (51) is provided between the two meshing surfaces.

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