Auxiliary filtering device of shield air duct system

Abstract

The utility model relates to an auxiliary filtering device of a shield air duct system, which comprises a self-circulation filtering device, and the self-circulation filtering device comprises a high-efficiency filter, a low-pressure air inlet pipe and a low-pressure air outlet pipe. Airflow in the air duct circularly flows along the low-pressure air inlet pipe, the high-efficiency filter and the low-pressure air outlet pipe; the high-efficiency filter comprises a front conical cover, a motor bin, a filter cartridge, a rear cartridge cover, a brushless motor and a filter element; the motor bin is internally communicated with an outlet pipe joint in the radial direction, a brushless motor is arranged in the motor bin, an output shaft of the brushless motor is provided with a fan impeller, the fan impeller is rotatably arranged in the front conical cover, and the filter element is inserted between the filter cartridge and the rear cartridge cover; the fan impeller drives airflow at the front end of the front conical cover to backwards penetrate through the motor bin and the filter cartridge, then enter the filter element, return to the motor bin after being filtered by the filter element and flow out through the outlet pipe connector. The air duct ventilation system can improve the filtering effect, ensure the filtering performance and effectively assist the air duct ventilation system in air filtering.

Description

Technical Field

[0001] This utility model relates to the field of air purification technology, and in particular to an auxiliary filtration device for a tunnel boring machine air duct system. Background Technology

[0002] As a core piece of equipment in underground engineering, tunnel boring machines (TBMs) rely on their ventilation systems, in conjunction with fans, to deliver fresh air and expel polluted gases, ensuring the safety of the working environment and the stability of the equipment at the tunnel face. However, the working environment of a TBM contains a large amount of dust, volatile organic compounds, and microbial pollutants. These particulate matter and harmful gases can enter the ventilation ducts with the airflow, not only accelerating fan blade wear and reducing heat dissipation efficiency but also potentially threatening the respiratory health of operators.

[0003] To address this, filtration devices are built into the ventilation system. Some duct systems employ multi-layer composite filters, which achieve graded filtration by layering pre-filters and medium-efficiency filters, such as using a G4 pre-filter and an F8 medium-efficiency filter. While this can intercept large particles, its filtration efficiency for micron-sized dust particles (less than 5 micrometers in diameter) and viral aerosols is typically below 90%. Furthermore, filtration efficiency decreases in high humidity environments, and the frequent replacement cycles lead to high maintenance costs.

[0004] Some filtration devices also use a combination of electrostatic dust collection and activated carbon adsorption. This combination uses an electrostatic field to capture particulate matter and activated carbon to adsorb volatile organic compounds. Although it can reduce wind resistance, it is sensitive to dust concentration and the energy consumption for activated carbon regeneration is high.

[0005] Currently, with the increasing air quality requirements stipulated in the "Code for Ventilation Design of Underground Engineering," high-efficiency filtration technology has become a research hotspot. Among them, high-efficiency particulate air filters (HEPA filters) are widely used in cleanrooms, medical fields, and other areas due to their filtration efficiency of ≥99.97% for 0.3-micron particles. Although the filtration efficiency is significantly improved after the HEPA filter media is used in the air duct, the dense structure of the media leads to a sharp increase in air resistance, far exceeding the design pressure range of the tunnel boring machine's fan.

[0006] Meanwhile, the filter media of high-efficiency filters is prone to clogging in humid and hot environments or high-dust conditions, leading to a significant decline in performance, and it is difficult to monitor the status of the filter media in real time. Relying on manual inspections can easily delay maintenance opportunities, increase the risk of downtime, and make it difficult to meet the long-term stability requirements under complex geological conditions. Therefore, it is necessary to design auxiliary filtration devices for shield tunnel ventilation systems. Summary of the Invention

[0007] To address the problem of increased wind resistance and impaired airflow within the duct caused by the dense structure of the filter material, this invention provides an auxiliary filtration device for a tunnel boring machine (TBM) duct system. A separate filtration system is installed on and connected to the duct. During the operation of the duct ventilation system, the additionally configured filtration system operates independently to provide auxiliary filtration of the air within the duct.

[0008] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0009] The auxiliary filtration device of the tunnel boring machine ventilation system includes a self-circulating filtration device installed outside the ventilation duct. The self-circulating filtration device includes a high-efficiency filter and a low-pressure air inlet pipe and a low-pressure air outlet pipe that are respectively connected to the inlet and outlet of the high-efficiency filter.

[0010] The high-efficiency filter includes a front conical cover, a motor compartment, a filter cartridge, a rear cover, a brushless motor, and a filter element. The front conical cover, motor compartment, filter cartridge, and rear cover are detachably connected in sequence.

[0011] The motor compartment is radially connected to an outlet pipe connector to facilitate the outflow of filtered air. The brushless motor is installed inside the motor compartment. The output shaft of the brushless motor has a fan impeller. The fan impeller is arranged to rotate inside the front cone cover. The filter element is inserted between the filter cartridge and the rear cartridge cover.

[0012] The airflow at the front end of the fan impeller drives the front cone cover to pass through the motor compartment and filter cartridge, then enters the filter element, is filtered by the filter element, returns to the motor compartment, and flows out through the outlet pipe joint.

[0013] The low-pressure air inlet pipe is connected between the front end of the front cone cover and the bottom of the air duct, and the low-pressure air outlet pipe is connected between the outlet pipe joint and the top of the air duct. The airflow in the air duct circulates along the low-pressure air inlet pipe, the high-efficiency filter and the low-pressure air outlet pipe.

[0014] Furthermore, the inlet of the high-efficiency filter is connected to the air duct through a low-pressure air inlet pipe, and the outlet of the high-efficiency filter is connected to the air duct through a low-pressure air outlet pipe, which facilitates the self-circulation and purification of the air in the air duct.

[0015] Furthermore, the front cone cover, motor compartment, filter cartridge, and rear cylinder cover are bolted together sequentially, facilitating the assembly and disassembly of the components. The front cone cover has a conical cylinder structure with open ends to allow for air circulation.

[0016] Both ends of the motor compartment and the filter cartridge are open. The rear cover has a "U" shaped cross section. The length of the rear cover is less than the length of the filter element. The filter element is a cylindrical body with open ends. The brushless motor and the filter element are arranged coaxially front and back. The interior of the filter element, the interior of the motor compartment, and the outlet pipe connector are connected in sequence.

[0017] Furthermore, the motor compartment sidewall has a through front airflow channel to facilitate airflow into the filter cartridge, and the filter cartridge sidewall has a through rear airflow channel to facilitate airflow to the filter element. The front cone cover, the front airflow channel, the rear airflow channel, and the rear cylinder cover are connected sequentially, and there is a gap between the filter element and the inner wall of the rear cylinder cover.

[0018] Furthermore, the high-speed rotating fan impeller draws the airflow in the low-pressure air inlet duct into the front cone cover, and then sends it into the front airflow channel by the fan impeller. The airflow flows through the front airflow channel and the rear airflow channel in sequence into the filter element for filtration. The filtered airflow returns to the motor compartment, flows out of the high-efficiency filter through the outlet pipe joint, and flows into the low-pressure air outlet duct.

[0019] Furthermore, the fan impeller includes an inner cone block, an outer cone cylinder, and connecting blades. The inner cone block is mounted on the output shaft of the brushless motor, and the taper of the outer cone cylinder is consistent with the taper of the front cone cover. The outer cone cylinder is sleeved outside the inner cone block.

[0020] The outer cone and the inner cone form an air intake channel. The connecting blades are provided between the outer cone and the inner cone. There are multiple connecting blades, which are evenly distributed in a spiral shape to facilitate the flow of air.

[0021] Furthermore, the filter element includes an inner support layer, a first filter layer, a second filter layer, and a third filter layer, which are sequentially arranged from the inside to the outside, as well as an outer support layer. Both the inner support layer and the outer support layer are cylindrical bodies made of metal wire mesh.

[0022] The filter layer one, filter layer two and filter layer three are all cylindrical bodies made of HEPA filter material, and the pore size on filter layer one, filter layer two and filter layer three increases sequentially.

[0023] Here, filter layer one can be made of H13 high-efficiency filter media, filter layer two can be made of F7 medium-efficiency filter media, and filter layer three can be made of G4 pre-filter media. The composite structure of the filter element improves the filtration effect.

[0024] Furthermore, it also includes a fresh air supply device installed outside the air duct. The fresh air supply device includes a fresh air filter and a high-pressure air outlet pipe. The inlet of the fresh air filter is connected to the atmosphere, and the outlet of the fresh air filter is connected to the air duct via the high-pressure air outlet pipe, so as to facilitate the filtration of outdoor air and its delivery into the air duct.

[0025] Furthermore, the fresh air filter and the high-efficiency filter have the same structure, and the front end of the fresh air filter is also provided with a pre-cleaning mechanism, which includes a pre-cleaning hood and a pre-cleaning turbine;

[0026] The front cone cover of the fresh air filter is also fitted with a pre-cleaning cover. The pre-cleaning cover is a stepped cylindrical body with one end open. Several air holes are provided circumferentially on the side wall of the pre-cleaning cover to facilitate uniform air intake of the fresh air filter.

[0027] A pre-cleaning turbine is rotatably mounted on the closed end of the pre-cleaning cover, and the pre-cleaning turbine and the front cone cover are arranged in a straight line with a front-to-back interval.

[0028] Furthermore, the high-speed rotating fan impeller generates airflow that passively drives the pre-cleaning turbine. Outside air is drawn into the pre-cleaning hood through the air vents and comes into contact with the pre-cleaning turbine. Large dust particles in the air are ejected, and the remaining air is transferred to the filter element by the fan impeller. The filtered air flows into the high-pressure air outlet pipe through the outlet pipe connector.

[0029] The beneficial effects of this utility model through the above technical solution are:

[0030] This invention adds a self-circulating filter device connected to the ductwork to the existing duct ventilation system, thus assisting in air purification. The high-efficiency filters are connected to the ductwork via pipes. During operation, the high-efficiency filters draw air from the ductwork for filtration and then return it to the ductwork, thus conveniently achieving self-circulating purification of the air within the duct.

[0031] This utility model uses a high-efficiency filter to actively attract airflow in the duct and guide it to the filter element for filtration. Then, it is quickly delivered into the duct. By adjusting the speed of the brushless motor, resistance can be overcome within a certain range, maintaining the stability of the filtered airflow and avoiding affecting the airflow in the duct.

[0032] This utility model's fresh air supply device facilitates the delivery of filtered fresh air into the air duct. The fresh air supply device combines a fresh air filter with a high-efficiency filter in a self-circulating filtration system. Furthermore, the filter element employs a composite structure, enabling precise interception of micron-sized particles. This effectively removes pollutants from the airflow within the air duct and replenishes the duct with fresh air, thereby significantly improving the purification speed and effect of the air within the air duct.

[0033] This utility model is equipped with differential pressure sensors at both the inlet and outlet of the fresh air filter and the inlet and outlet of the high-efficiency filter. These sensors can determine the filter element's condition and degree of blockage based on the pressure difference between the incoming and outgoing air, thus enabling real-time monitoring of the filter element's status. Simultaneously, the brushless motor's operating speed can be adjusted in real-time based on the feedback signal from the differential pressure sensors, reducing energy consumption and maintaining stable airflow pressure. Attached Figure Description

[0034] Figure 1This is a front view of the auxiliary filtration device of the shield tunnel ventilation system of this utility model. The arrow in the figure points to the direction of airflow.

[0035] Figure 2 This utility model relates to an auxiliary filtration device for a tunnel boring machine ventilation duct system. Figure 1 Diagram of direction A in the middle.

[0036] Figure 3 This utility model relates to an auxiliary filtration device for a tunnel boring machine ventilation duct system. Figure 1 Schematic diagram of direction B in the middle.

[0037] Figure 4 This is a schematic diagram showing the vertical arrangement of the fresh air filter and the high-efficiency filter in the auxiliary filtration device of the shield tunnel ventilation system of this utility model.

[0038] Figure 5 This is a cross-sectional view of the high-efficiency filter of the auxiliary filtration device of the shield tunnel ventilation system of this utility model. The arrow in the figure points to the direction of air flow.

[0039] Figure 6 This utility model relates to an auxiliary filtration device for a tunnel boring machine ventilation duct system. Figure 5 A breakdown diagram.

[0040] Figure 7 This is a cross-sectional view of the fan impeller of the auxiliary filtration device of the shield tunnel ventilation system of this utility model.

[0041] Figure 8 This is a cross-sectional view of the motor compartment and filter cylinder of the auxiliary filtration device of the shield tunnel ventilation system of this utility model.

[0042] Figure 9 This is a cross-sectional view of the filter element of the auxiliary filtration device of the shield tunnel ventilation system of this utility model.

[0043] Figure 10 This is a cross-sectional view of the fresh air filter of the auxiliary filtration device of the shield tunnel ventilation system of this utility model. The arrow in the figure points to the direction of air flow.

[0044] Figure 11 This utility model relates to an auxiliary filtration device for a tunnel boring machine ventilation duct system. Figure 10 A breakdown diagram.

[0045] The attached diagram is labeled as follows: 1. Self-circulating filter device; 2. Fresh air supply device; 3. High-efficiency filter; 4. Front cone cover; 5. Motor compartment; 51. Inner ring one; 52. Outer ring one; 53. Front support plate; 6. Filter cartridge; 61. Inner ring two; 62. Outer ring two; 63. Rear support plate; 7. Rear cover; 8. Fan impeller; 81. Inner cone block; 82. Outer cone; 83. Connecting blades; 9. Brushless motor; 10. Filter element; 101. Inner support layer; 102. Filter layer one; 103. Filter layer two; 104. Filter layer three; 105. Outer support layer; 11. Low-pressure air inlet duct; 13. Low-pressure air outlet duct. 15 Motor mounting ring, 16 Air intake duct, 17 Sealing ring, 18 Front airflow duct, 19 Rear airflow duct, 20 Outlet pipe connector, 21 Fresh air filter, 22 High-pressure outlet duct, 23 Motor bracket, 24 Mounting parts, 241 Pipe clamp, 242 Connecting plate, 25 Louvered air outlet, 26 Pre-cleaning cover, 27 Pre-cleaning turbine, 28 Internal threaded sleeve, 29 Air hole, 31 Air duct. Detailed Implementation

[0046] The specific embodiments of this utility model are described in detail below with reference to the accompanying drawings:

[0047] like Figures 1-11 As shown, the auxiliary filtration device of the shield tunnel ventilation system includes a self-circulating filter device 1 installed outside the ventilation duct 31. The self-circulating filter device 1 can attract air from the ventilation duct 31, filter it, and then transport it back into the ventilation duct 31, thereby realizing the self-circulating filtration of airflow in the ventilation duct 31.

[0048] The self-circulating filtration device 1 includes a high-efficiency filter 3 and a low-pressure air inlet pipe 11 and a low-pressure air outlet pipe 13 that are respectively connected to the inlet and outlet of the high-efficiency filter 3. The inlet of the high-efficiency filter 3 is connected to the air duct 31 through the low-pressure air inlet pipe 11, and the outlet of the high-efficiency filter 3 is connected to the air duct 31 through the low-pressure air outlet pipe 13.

[0049] Thus, the high-efficiency filter 3 is connected to the air duct 31 through the low-pressure air inlet pipe 11 and the low-pressure air outlet pipe 13. Through the operation of the high-efficiency filter 3, the air in the air duct 31 can be circulated. That is, the air in the air duct 31 enters the high-efficiency filter 3 from a lower position through the low-pressure air inlet pipe 11 and is filtered. The filtered air returns to the air duct 31 from a higher position through the low-pressure air outlet pipe 13, realizing the self-circulation of air in the air duct 31 and filtration during the flow.

[0050] In this embodiment, the high-efficiency filter 3 includes a front conical cover 4, a motor compartment 5, a filter cartridge 6, a rear cover 7, a brushless motor 9, and a filter element 10 for air filtration. The front conical cover 4, the motor compartment 5, the filter cartridge 6, and the rear cover 7 are detachably connected in sequence. Specifically, the front conical cover 4, the motor compartment 5, the filter cartridge 6, and the rear cover 7 are bolted together in sequence, enabling convenient assembly and disassembly of the high-efficiency filter 3.

[0051] The front cone cover 4 has a conical cylindrical structure with open ends. The front opening of the front cone cover 4 is smaller, and the rear opening is larger. Both ends of the motor compartment 5 and the filter cartridge 6 are open. The motor compartment 5 is a cylindrical shape with open ends, and the filter cartridge 6 has a smaller opening at the front end and a larger opening at the rear end. An outlet pipe connector 20 is radially connected inside the motor compartment 5.

[0052] A brushless motor 9 is installed inside the motor compartment 5. There is a gap between the brushless motor 9 and the inner wall of the motor compartment 5. When installing the brushless motor 9, a motor mounting ring 15 is installed on the outside of the brushless motor 9. The brushless motor 9 is connected and fixed to the motor compartment 5 through the motor mounting ring 15. The motor mounting ring 15 is attached to one end face of the motor compartment 5 and is fixed by bolt connection. In this way, the brushless motor 9 can be installed inside the motor compartment 5.

[0053] The brushless motor 9 has a fan impeller 8 mounted on its output shaft, which is rotatably positioned within the front conical cover 4. When the brushless motor 9 is running, it directly drives the fan impeller 8 to rotate within the front conical cover 4, thereby drawing air into the high-efficiency filter 3 through the opening at the front end of the front conical cover 4. The diameter of the fan impeller 8 is much larger than that of the brushless motor 9 and also larger than the diameter of the motor mounting ring 15.

[0054] To enable the fan impeller 8 to drive airflow, the fan impeller 8 includes an inner cone block 81, an outer cone cylinder 82, and connecting blades 83. The inner cone block 81 is mounted on the output shaft of the brushless motor 9, and the taper of the outer cone cylinder 82 is consistent with the taper of the front cone cover 4. The outer cone cylinder 82 is fitted over the inner cone block 81.

[0055] The outer cone 82 and the inner cone 81 form an annular air intake channel 16. Multiple connecting blades 83 are arranged between the outer cone 82 and the inner cone 81 in a spiral arrangement. The connecting blades 83 connect and fix the outer cone 82 and the inner cone 81, and also evenly divide the air intake channel 16. When the fan impeller 8 rotates, the airflow enters the high-efficiency filter 3 through the air intake channel 16.

[0056] The rear cover 7 has a "U" shaped cross section. The filter element 10 is inserted between the filter cylinder 6 and the rear cover 7. That is, both ends of the filter element 10 are inserted into the filter cylinder 6 and the rear cover 7 respectively. At the same time, a sealing ring 17 is provided at one end of the filter element 10, and the sealing ring 17 is tightly pressed against the filter cylinder 6.

[0057] The filter element 10, filter cartridge 6, and rear cover 7 all have gaps in their inner walls, thus forming an annular cavity. The length of the rear cover 7 is less than the length of the filter element 10. The brushless motor 9 and the filter element 10 are arranged coaxially front and rear, with a gap between them. The interior of the filter element 10, the interior of the motor compartment 5, and the outlet pipe connector 20 are connected in sequence.

[0058] The filter element 10 is a cylindrical body open at both ends. The filter element 10 includes an inner support layer 101, a first filter layer 102, a second filter layer 103, and a third filter layer 104, and an outer support layer 105, which are sequentially arranged from the inside to the outside. The inner support layer 101 and the outer support layer 105 are both cylindrical bodies made of metal wire mesh. The first filter layer 102, the second filter layer 103, and the third filter layer 104 are all cylindrical bodies made of HEPA filter material, and the pore size on the first filter layer 102, the second filter layer 103, and the third filter layer 104 increases sequentially.

[0059] As can be seen, filter element 10 is made of composite filter material, which significantly improves dust holding capacity compared to traditional single-layer filters. As air flows from the outside to the inside of filter element 10, it undergoes more refined filtration. Filter layer 3 (104) is made of 3D meltblown fiber cloth with a porosity ≤15μm, capturing large particles >5μm through inertial impaction and gravitational settling. Filter layer 2 (103) is made of high-density gradient glass fiber cloth with a pore size gradient of 2.5-0.8μm, capable of trapping submicron particles through Brownian diffusion. Filter layer 1 (102) is made of nanoscale PTFE membrane with surface pores <0.2μm, achieving final interception through a sieving mechanism.

[0060] The principle of the high-efficiency filter 3 is as follows: the brushless motor 9 drives the fan impeller 8 to rotate. The fan impeller 8 drives the airflow at the front end of the front cone cover 4 to pass through the motor chamber 5 and the filter cartridge 6, and then enters the filter element 10. After being filtered by the filter element 10, it returns to the motor chamber 5 and flows out through the outlet pipe connector 20.

[0061] To facilitate airflow through the motor housing 5, a through-flow front airflow channel 18 is provided on the side wall of the motor housing 5, which is connected to the air intake channel 16. The front airflow channel 18 is formed as follows: The motor housing 5 includes an inner ring 51, an outer ring 52, and a front support plate 53. The inner ring 51 and the outer ring 52 are arranged coaxially from the inside to the outside, and the inner ring 51 and the outer ring 52 are of equal length. The cross-section of the inner ring 51 is in the shape of a "﹁", that is, the front opening of the inner ring 51 is large and the rear opening is small.

[0062] The inner ring 51 and the outer ring 52 form an annular front airflow channel 18. A front support plate 53 is provided between the inner ring 51 and the outer ring 52, and the number of front support plates 53 is evenly distributed in the circumferential direction. The front support plates 53 connect and fix the inner ring 51 and the outer ring 52 together, and the front support plates 53 evenly divide the front airflow channel 18.

[0063] To facilitate airflow through the filter cartridge 6, a through rear airflow channel 19 is provided on the side wall of the filter cartridge 6. The front cone cover 4, the air intake channel 16, the front airflow channel 18, the rear airflow channel 19, and the rear cylinder cover 7 are connected sequentially, allowing air at the front cone cover 4 to flow to the filter element 10.

[0064] The rear airflow channel 19 is formed as follows: the filter cartridge 6 includes an inner ring 61, an outer ring 62, and a rear support plate 63. The inner ring 61 and the outer ring 62 are arranged coaxially from the inside to the outside. The length of the inner ring 61 is much smaller than that of the outer ring 62. The cross-section of the inner ring 61 is "U" shaped, resulting in a small opening at the front end and a large opening at the rear end. One end of the filter element 10 is tightly pressed against the inner ring 61.

[0065] The inner ring 61 and the outer ring 62 form a ring-shaped rear airflow channel 19. A rear support plate 63 is provided between the inner ring 61 and the outer ring 62, and multiple rear support plates 63 are evenly distributed in the circumferential direction. The length of the rear support plate 63 is the same as the length of the inner ring 61. The rear support plate 63 is used to connect and fix the inner ring 61 and the outer ring 62, and the rear support plate 63 divides the rear airflow channel 19.

[0066] When the HEPA filter 3 is connected to the air duct 31, a low-pressure air inlet pipe 11 is connected between the front end of the front cone cover 4 and the bottom of the air duct 31. The low-pressure air inlet pipe 11 is arranged horizontally. A low-pressure air outlet pipe 13 is connected between the outlet pipe connector 20 and the top of the air duct 31. The low-pressure air outlet pipe 13 extends vertically upward and then bends horizontally into the air duct 31. The airflow in the air duct 31 circulates along the low-pressure air inlet pipe 11, the HEPA filter 3, and the low-pressure air outlet pipe 13.

[0067] In this way, the high-speed rotating fan impeller 8 draws the airflow in the low-pressure air inlet pipe 11 into the front cone cover 4, and sends it into the front airflow channel 18 by the fan impeller 8. The airflow flows through the front airflow channel 18 and the rear airflow channel 19 in sequence and enters the filter element 10 for filtration. The filtered airflow returns to the motor compartment 5, flows out of the high-efficiency filter 3 through the outlet pipe connector 20 and flows into the low-pressure air outlet pipe 13.

[0068] The outlet pipe connector 20 passes through the inner ring 51, the front airflow channel 18 and the outer ring 52 in sequence, and extends radially to the outside of the motor compartment 5. Then, the air filtered in the motor compartment 5 flows out of the high-efficiency filter 3 through the outlet pipe connector 20.

[0069] Therefore, the high-efficiency filter 3 in operation draws air from the air duct 31. The air in the air duct 31 is transported to the interior of the high-efficiency filter 3 by the low-pressure air inlet pipe 11, and after being effectively filtered by the filter element 10, it returns to the air duct 31 through the low-pressure air outlet pipe 13, achieving the effect of self-circulation filtration and purification of air in the air duct 31.

[0070] To optimize the product structure, a fresh air supply device 2 is also installed outside the air duct 31. The fresh air supply device 2 connects the inside and outside of the air duct 31 and is used to supply fresh air into the air duct 31.

[0071] The fresh air supply unit 2 includes a fresh air filter 21 and a high-pressure air outlet duct 22. The high-efficiency filter 3 and the fresh air filter 21 are arranged vertically at intervals. During installation, a motor bracket 23 is installed between the fresh air filter 21 and the high-efficiency filter 3. The fresh air filter 21 and the high-efficiency filter 3 are connected and fixed to the air duct 31 through the motor bracket 23, enabling the simultaneous installation of the fresh air filter 21 and the high-efficiency filter 3. The motor bracket 23 provides structural support for the fresh air filter 21 and the high-efficiency filter 3.

[0072] The inlet of the fresh air filter 21 is connected to the atmosphere, and the outlet of the fresh air filter 21 is connected to the high-pressure air outlet pipe 22 between the air duct 31 and the atmosphere. The high-pressure air outlet pipe 22 and the low-pressure air outlet pipe 13 are arranged alternately on the left and right sides. During installation, mounting parts 24 are installed on both the high-pressure air outlet pipe 22 and the low-pressure air outlet pipe 13.

[0073] The high-pressure air outlet duct 22 and the low-pressure air outlet duct 13 are respectively connected and fixed to the air duct 31 via mounting components 24. The mounting components 24 include pipe clamps 241 and connecting plates 242. The pipe clamps 241 clamp the high-pressure air outlet duct 22 and the low-pressure air outlet duct 13, and the pipe clamps 241 are connected to the air duct 31 via the connecting plates 242, which are approximately Z-shaped plates. Louvered air vents 25 are provided at the outlets of both the high-pressure air outlet duct 22 and the low-pressure air outlet duct 13 to achieve uniform airflow. The louvered air vents 25 are installed on the inner wall of the air duct 31.

[0074] The fresh air filter 21 and the high-efficiency filter 3 have the same structure. However, since the fresh air filter 21 is directly connected to the atmosphere, a pre-cleaning mechanism is also provided at the front end of the fresh air filter 21 in order to achieve air pre-cleaning. The pre-cleaning mechanism includes a pre-cleaning cover 26 and a pre-cleaning turbine 27.

[0075] The front cone cover 4 of the filter 21 is also fitted with a pre-cleaning cover 26. The pre-cleaning cover 26 is a stepped cylindrical body with one open end. When the pre-cleaning cover 26 is installed, the front cone cover 4 is provided with an internal threaded sleeve 28. By using a long bolt to pass through the pre-cleaning cover 26 and connect it to the internal threaded sleeve 28, the pre-cleaning cover 26 can be installed and fixed on the front cone cover 4, and a certain gap is maintained between them.

[0076] The pre-cleaning hood 26 has several circumferentially arranged air vents 29 on its sidewalls. These vents 29 are oblong in shape and surround the front cone cover 4, allowing air to enter the pre-cleaning hood 26. A pre-cleaning turbine 27 is rotatably mounted on the closed end of the pre-cleaning hood 26. The pre-cleaning turbine 27 and the front cone cover 4 are arranged in a straight line with a back-to-back spacing. The pre-cleaning turbine 27 removes large dust particles from the air and pressurizes the air. The outlet pipe connector 20 of the fresh air filter 21 connects to the high-pressure air outlet pipe 22.

[0077] The principle of the fresh air supply device 2 is as follows: the high-speed rotating fan impeller 8 generates airflow that passively drives the pre-cleaning turbine 27. Outside air is drawn into the pre-cleaning hood 26 through the air vent 29 and comes into contact with the pre-cleaning turbine 27. Large dust particles in the air are ejected, and the remaining air is transferred to the filter element 10 by the fan impeller 8. The filtered air flows into the high-pressure air outlet pipe 22 through the outlet pipe connector 20, and then the filtered air is delivered into the air duct 31. It can be seen that the fresh air filter 21 is essentially using the centrifugal pressurization principle to increase the airflow energy.

[0078] To control the fresh air supply unit 2 and the self-circulating filter unit 1, an electrical control cabinet is installed outside the air duct 31. The electrical control cabinet integrates a vector frequency converter, a controller, and a differential pressure sensor. The vector frequency converter is used to drive the fresh air filter 21 and the high-efficiency filter 3 and to dynamically regulate their operating speed.

[0079] Differential pressure sensors are installed on the fresh air supply unit 2 and the self-circulating filter unit 1, respectively. These sensors monitor the pressure difference between the inlet and outlet of the fresh air filter 21 and the inlet and outlet of the high-efficiency filter 3. The sensors provide real-time feedback signals to determine the blockage status of the filter element 10. Simultaneously, a controller dynamically adjusts the operation of the fresh air filter 21 and the high-efficiency filter 3 to maintain the differential pressure within a stable set range, thereby achieving dynamic airflow regulation.

[0080] The embodiments described above are merely preferred embodiments of this utility model and are not intended to limit the scope of implementation of this utility model. Therefore, all equivalent changes or modifications made to the structure, features and principles described in the patent claims of this utility model should be included within the scope of the patent application of this utility model.

Claims

1. An auxiliary filtration device for a shield tunnel ventilation duct system, characterized in that, Includes a self-circulating filter device (1) installed outside the air duct (31), the self-circulating filter device (1) includes a high-efficiency filter (3) and a low-pressure air inlet pipe (11) and a low-pressure air outlet pipe (13) respectively connected to the inlet and outlet of the high-efficiency filter (3). The high-efficiency filter (3) includes a front cone cover (4), a motor compartment (5), a filter cartridge (6), a rear cover (7), a brushless motor (9), and a filter element (10). The front cone cover (4), the motor compartment (5), the filter cartridge (6), and the rear cover (7) are detachably connected in sequence. The motor compartment (5) is radially connected to an outlet pipe connector (20). The brushless motor (9) is installed inside the motor compartment (5). The output shaft of the brushless motor (9) is equipped with a fan impeller (8). The fan impeller (8) is rotatably arranged inside the front cone cover (4). The filter element (10) is inserted between the filter cylinder (6) and the rear cylinder cover (7). The fan impeller (8) drives the airflow at the front end of the front cone cover (4) to pass through the motor compartment (5) and the filter cartridge (6) and then enter the filter element (10). After being filtered by the filter element (10), the airflow returns to the motor compartment (5) and flows out through the outlet pipe joint (20). The low-pressure air inlet pipe (11) is connected between the front end of the front cone cover (4) and the bottom of the air duct (31), and the low-pressure air outlet pipe (13) is connected between the outlet pipe joint (20) and the top of the air duct (31). The airflow in the air duct (31) circulates along the low-pressure air inlet pipe (11), the high-efficiency filter (3) and the low-pressure air outlet pipe (13).

2. The auxiliary filtration device for the shield tunnel ventilation system according to claim 1, characterized in that, The inlet of the high-efficiency filter (3) is connected to the air duct (31) through the low-pressure air inlet pipe (11), and the outlet of the high-efficiency filter (3) is connected to the air duct (31) through the low-pressure air outlet pipe (13).

3. The auxiliary filtration device for the shield tunnel ventilation system according to claim 1, characterized in that, The front cone cover (4), motor compartment (5), filter cylinder (6) and rear cylinder cover (7) are bolted together in sequence. The front cone cover (4) is a conical cylinder structure with open ends. Both ends of the motor compartment (5) and the filter cartridge (6) are open. The rear cover (7) has a "U" shaped cross section. The length of the rear cover (7) is less than the length of the filter element (10). The filter element (10) is a cylindrical body with open ends. The brushless motor (9) and the filter element (10) are arranged coaxially front and back. The interior of the filter element (10), the interior of the motor compartment (5), and the outlet pipe connector (20) are connected in sequence.

4. The auxiliary filtration device for the shield tunnel ventilation system according to claim 3, characterized in that, The motor compartment (5) has a through front airflow channel (18) on its side wall, and the filter cartridge (6) has a through rear airflow channel (19) on its side wall. The front cone cover (4), the front airflow channel (18), the rear airflow channel (19), and the rear cylinder cover (7) are connected in sequence. There is a gap between the filter element (10) and the inner wall of the rear cylinder cover (7).

5. The auxiliary filtration device for the shield tunnel ventilation system according to claim 4, characterized in that, The high-speed rotating fan impeller (8) draws the airflow in the low-pressure air inlet pipe (11) into the front cone cover (4) and sends it into the front airflow channel (18) by the fan impeller (8). The airflow flows through the front airflow channel (18) and the rear airflow channel (19) in sequence and enters the filter element (10) for filtration. The filtered airflow returns to the motor compartment (5), flows out of the high-efficiency filter (3) through the outlet pipe connector (20) and flows into the low-pressure air outlet pipe (13).

6. The auxiliary filtration device for the shield tunnel ventilation system according to claim 3, characterized in that, The fan impeller (8) includes an inner cone block (81), an outer cone cylinder (82), and connecting blades (83). The inner cone block (81) is mounted on the output shaft of the brushless motor (9). The outer cone cylinder (82) has the same taper as the front cone cover (4). The outer cone cylinder (82) is fitted over the inner cone block (81). The outer cone (82) and the inner cone (81) form an air intake channel (16). The connecting blades (83) are provided between the outer cone (82) and the inner cone (81). There are multiple connecting blades (83), and the multiple connecting blades (83) are evenly distributed in a spiral shape.

7. The auxiliary filtration device for the shield tunnel ventilation system according to claim 3, characterized in that, The filter element (10) includes an inner support layer (101), a first filter layer (102), a second filter layer (103), and a third filter layer (104) arranged sequentially from the inside to the outside, as well as an outer support layer (105). The inner support layer (101) and the outer support layer (105) are both cylindrical bodies made of metal wire mesh. The filter layer one (102), filter layer two (103) and filter layer three (104) are all cylindrical bodies made of HEPA filter material, and the pore size of the filter pores on filter layer one (102), filter layer two (103) and filter layer three (104) increases sequentially.

8. The auxiliary filtration device for the shield tunnel ventilation system according to claim 1, characterized in that, It also includes a fresh air supply device (2) installed outside the air duct (31), the fresh air supply device (2) includes a fresh air filter (21) and a high-pressure air outlet pipe (22), the inlet of the fresh air filter (21) is connected to the atmosphere, and the outlet of the fresh air filter (21) is connected to the air duct (31) via the high-pressure air outlet pipe (22).

9. The auxiliary filtration device for the shield tunnel ventilation system according to claim 8, characterized in that, The fresh air filter (21) and the high-efficiency filter (3) have the same structure. The front end of the fresh air filter (21) is also provided with a pre-cleaning mechanism, which includes a pre-cleaning cover (26) and a pre-cleaning turbine (27). The front cone cover (4) of the fresh air filter (21) is also fitted with a pre-cleaning cover (26). The pre-cleaning cover (26) is a stepped cylindrical body with one end open. Several air holes (29) are provided on the side wall of the pre-cleaning cover (26) in a circumferential direction. The pre-cleaning cover (26) is rotatably equipped with a pre-cleaning turbine (27) on its closed end. The pre-cleaning turbine (27) and the front cone cover (4) are arranged in a straight line with a front-to-back interval.

10. The auxiliary filtration device for the shield tunnel ventilation system according to claim 9, characterized in that, The high-speed rotating fan impeller (8) generates airflow to passively drive the pre-cleaning turbine (27) to operate. Outside air is drawn into the pre-cleaning hood (26) through the air hole (29) and comes into contact with the pre-cleaning turbine (27). Large dust particles in the air are ejected, and the remaining air is transferred to the filter element (10) by the fan impeller (8). The filtered air flows into the high-pressure air outlet pipe (22) through the outlet pipe connector (20).

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