An environmentally friendly steel structure electric arc welding device

Abstract

An environmentally friendly steel structure arc welding device includes a welding torch and a dust collection cylinder. The dust collection cylinder includes an air inlet cylinder facing the welding torch tip and an air suction cylinder connected to an external air extraction device. The air inlet cylinder and the air suction cylinder are connected. The interior of the air inlet cylinder has multiple air inlet channels around the periphery of the welding torch. Each air inlet channel is equipped with an airflow regulating component, which is configured to adjust the airflow through the air inlet channel according to the amount of dust in the air inlet channel. By adjusting the opening of the airflow regulating component, the airflow in the air inlet channel is positively correlated with the amount of dust. The air inlet channels at different positions can distribute the airflow in each air inlet channel according to the distribution area of ​​dust, so that the airflow can carry away as much dust as possible. While maintaining a certain extraction power, it achieves a high-efficiency dust removal effect. At the same time, the dust filter cylinder can filter dust particles at the rear of the air inlet channel and backwash periodically, without affecting the continuity of fume exhaust during welding torch operation.

Description

Technical Field

[0001] This invention belongs to the field of welding equipment technology, specifically referring to an environmentally friendly steel structure electric arc welding device. Background Technology

[0002] Steel structures in environmental protection equipment are generally used in heavy-duty support frames, which are used to support the core modules of the environmental protection equipment. The steel frame resists the equipment's own weight and operating vibration loads. The steel structure welding usually adopts automated / semi-automated arc welding technology, combined with strict process control to ensure structural strength.

[0003] During welding, the arc zone is at a high temperature, where the steel and welding wire materials vaporize instantly. The vaporized metal reacts with oxygen in the air to form oxides, which then rapidly cool after leaving the arc zone, forming tiny particles. Currently, an extraction device is installed near the welding torch to capture most of the smoke at its source. However, the extraction device has limited adsorption capacity, and the smoke is not evenly distributed around the welding torch. To enhance the adsorption effect, the power of the extraction device must be increased. Therefore, how to improve the adsorption effect of the extraction device without increasing its power has become an urgent problem to be solved. Summary of the Invention

[0004] In view of the above situation and to overcome the defects of the prior art, the purpose of the present invention is to provide an environmentally friendly steel structure electric arc welding device to at least partially solve the problems mentioned in the background art.

[0005] The technical solution adopted in this invention is as follows: An environmentally friendly steel structure arc welding device is proposed, comprising:

[0006] A welding torch is mounted at the end of a robotic arm and can be driven to move by the robotic arm.

[0007] A vacuum cleaner is arranged around the welding torch;

[0008] The dust collection cylinder includes an air inlet cylinder facing the welding torch head and an air suction cylinder connected to an external air extraction device. The air inlet cylinder and the air suction cylinder are connected. The interior of the air inlet cylinder is provided with multiple air inlet channels around the periphery of the welding torch. Each air inlet channel is provided with an airflow regulating component. The airflow regulating component is configured to adjust the airflow through the air inlet channel according to the amount of dust in the air inlet channel. The opening degree of the airflow regulating component is adjusted so that the airflow in the air inlet channel is positively correlated with the amount of dust.

[0009] Furthermore, the flow regulating component includes a smoke concentration sensor and a flow valve arranged sequentially along the airflow direction. The smoke concentration sensor is disposed in the air intake channel and is used to detect the amount of smoke in the airflow in the air intake channel. The flow valve is configured to adjust its opening size according to the amount of smoke detected by the smoke concentration sensor, and the opening size of the flow valve increases with the increase of the amount of smoke.

[0010] Furthermore, the air intake cylinder has multiple baffles arranged in a centrally symmetrical manner inside, and any two adjacent air intake channels are separated by the baffles. A housing is fixedly provided on the outer side wall of the air intake cylinder, and the smoke concentration sensor is fixedly installed inside the housing. A background plate is provided on the inner side wall of the air intake cylinder corresponding to the output end of the smoke concentration sensor.

[0011] Furthermore, a dust filter is provided between the air inlet and the air intake, and a filter element is provided inside the dust filter. The filter element is configured to trap the smoke and dust in the airflow in the dust filter.

[0012] Furthermore, the filter element includes a flow guide hood and a filter screen. Along the airflow direction, the flow guide hood is disposed on the front side of the filter screen, and both the flow guide hood and the filter screen are constructed as cylindrical bodies with a "U"-shaped cross-section. The flow guide hood is disposed on the outside of the filter screen. There is a converging channel for airflow between the flow guide hood and the inner wall of the dust filter cylinder. There is a dust filtering channel between the flow guide hood and the filter screen. The tail end of the flow guide hood is provided with a plurality of centrally symmetrically distributed air guide holes. The converging channel and the dust filtering channel are connected through the air guide holes.

[0013] Furthermore, the filter element also includes a water distribution cylinder, which is disposed inside the filter screen, and there is a set gap between the water distribution cylinder and the filter screen, so that the airflow in the dust filtration channel can pass through the filter screen and enter the air intake cylinder.

[0014] Furthermore, a water inlet connector is provided on the outer wall of the dust filter tube corresponding to the tail end of the water distribution tube. The water distribution tube has a hollow structure, and a water distribution cavity communicating with the water inlet connector is provided inside the water distribution tube. Water spray holes are provided on the outer wall of the water distribution tube in the area corresponding to the filter screen.

[0015] Furthermore, a drain connector is provided on the outer wall of the dust filter cartridge corresponding to the head end of the flow guide shroud, and the drain connector is connected to the dust filter channel.

[0016] Furthermore, the water inlet connector is connected to an external water supply device, and the drain connector is connected to an external water pumping device. The water in the water distribution chamber can blow the dust adhering to the filter screen surface back into the dust filter channel, and then pump it out through the drain connector.

[0017] Furthermore, the air intake cylinder has a reflux chamber inside, which is connected to the inner space of the filter screen. An air intake connector is fixed on the outer wall of the air intake cylinder, which is connected to an external air extraction device and is connected to the reflux chamber.

[0018] Beneficial effects:

[0019] This invention features a dust collection cylinder that moves with the welding torch on its outer side, facilitating the extraction and treatment of fumes at their source. The air intake cylinder has multiple air intake channels distributed around the welding torch. These channels, located at different positions, can distribute airflow according to the distribution area of ​​the fumes, ensuring that the airflow carries away as much fumes as possible. This achieves highly efficient dust removal while maintaining a constant extraction power. Simultaneously, the dust filter cylinder filters fumes particles at the rear of the air intake channels and performs periodic backwashing, ensuring the continuity of fume extraction during welding torch operation. Attached Figure Description

[0020] Figure 1 This is a three-dimensional structural schematic diagram of an environmentally friendly steel structure arc welding device proposed in an embodiment of the present invention;

[0021] Figure 2 This is a front view schematic diagram of an environmentally friendly steel structure arc welding device proposed in an embodiment of the present invention;

[0022] Figure 3 A three-dimensional structural diagram of the vacuum cleaner cylinder is provided for an embodiment of the present invention;

[0023] Figure 4 A schematic diagram of the internal structure of the vacuum cleaner cylinder is provided for an embodiment of the present invention;

[0024] Figure 5 for Figure 4 Enlarged structural diagram of region A in the middle;

[0025] Figure 6 This is a schematic diagram of the air inlet end of the dust collection cylinder according to an embodiment of the present invention.

[0026] Among them, 10 is the welding torch; 20 is the robotic arm; 30 is the dust collection canister; 300 is the welding torch mounting channel; 40 is the air inlet; 400 is the air inlet channel; 401 is the outer shell; 41 is the partition; 42 is the smoke concentration sensor; 421 is the background plate; 43 is the flow valve; 50 is the dust filter canister; 51 is the water inlet connector; 52 is the drain connector; 53 is the filter element; 5300 is the manifold; 531 is the flow guide; 5310 is the air guide hole; 5311 is the dust filter channel; 532 is the filter screen; 533 is the water distribution canister; 5330 is the water distribution chamber; 5331 is the water spray hole; 60 is the air suction canister; 600 is the return chamber; and 61 is the air suction connector.

[0027] The accompanying drawings are provided to further understand the embodiments and form part of the specification. They are used together with the embodiments for explanation and do not constitute a limitation on the embodiments. Detailed Implementation

[0028] The technical solutions in 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, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection.

[0029] In the description of the embodiments, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the embodiments and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments.

[0030] Setting an exhaust assembly on the welding torch 10 is currently a relatively efficient dust removal method. However, its dust removal efficiency is limited by the suction power. If the suction power of the exhaust device is continuously increased, it will cause an increase in energy consumption. Therefore, in order to increase the dust removal efficiency of the exhaust assembly while maintaining a certain power, this embodiment of the invention provides an environmentally friendly steel structure arc welding device, which mainly includes a welding torch 10, a robotic arm 20, and a dust collection cylinder 30.

[0031] like Figure 1 and Figure 2 As shown, the welding torch 10 is mounted on the end of the robotic arm 20 and can be driven to move by the robotic arm 20. The dust collection tube 30 is mounted on the outside of the welding torch 10 and is connected to an external air extraction device so that the dust collection tube 30 can suck up the fumes generated when the welding torch 10 is working.

[0032] In some embodiments, the robotic arm 20 adopts a six-axis articulated robot with high flexibility. During operation, the robotic arm 20 is first taught and programmed to memorize the welding path, posture and parameters, and generate an execution program. After startup, the robotic arm 20 controls the movement of the robotic arm according to the program, and the welding torch 10 moves accordingly. During the welding process, the sensors monitor parameters such as current and voltage in real time and feed them back to the control system for timely adjustment to ensure welding quality and achieve efficient and precise welding.

[0033] Furthermore, such as Figure 3 and Figure 4As shown, the dust collection cylinder 30 has a hollow cylindrical structure. The middle position of the dust collection cylinder 30 has a welding torch mounting channel 300 for accommodating the welding torch 10. The dust collection cylinder 30 includes an air inlet cylinder 40 facing the head end of the welding torch 10 and an air suction cylinder 60 connected to an external air extraction device. The air inlet cylinder 40 and the air suction cylinder 60 are connected. During operation, through the connection between the external air extraction device and the air suction cylinder 60, a negative pressure can be generated at the air inlet cylinder 40, causing the air inlet cylinder 40 to suck in the fumes generated when the welding torch 10 is working and to exhaust them from the air suction cylinder 60.

[0034] During operation, the fumes generated by the welding torch 10 will drift around the torch 10. However, the fumes are unpredictable in their drift. The amount of fumes drawn in by the suction cylinder 30 varies in multiple directions around the welding torch 10. Areas with less fumes drawn in reduce suction efficiency. To direct the airflow drawn in by the suction cylinder 30 towards areas with more fumes, the air intake cylinder 40 is provided with multiple air intake channels 400 around the periphery of the welding torch 10. Each air intake channel 400 is equipped with an airflow regulating component. The airflow regulating component is configured to adjust the airflow through the air intake channel 400 according to the amount of fumes in the air intake channel 400. The opening of the airflow regulating component is adjusted to make the airflow in the air intake channel 400 positively correlated with the amount of fumes.

[0035] Multiple air intake channels 400 are arranged inside the dust collection cylinder 30 along the circumferential direction of the welding torch 10, and a flow regulator is configured in each air intake channel 400. The flow regulator adjusts the airflow rate entering the air intake channel 400 according to the dust content in the airflow entering the air intake channel 400. For example, when the dust content in a certain air intake channel 400 is detected to be low, the opening of the flow regulator is reduced accordingly, so that the airflow rate entering the air intake channel 400 is reduced. When the volume is large, the opening of the flow regulator is increased accordingly, increasing the airflow into the air intake channel 400. In multiple areas around the welding torch 10, the air intake channel 400 has a larger capacity on the side with more dust, and the airflow is concentrated and flows from that area, carrying away the dust. On the side with less dust, the airflow is allocated to a relatively smaller volume. In this way, while maintaining a constant extraction power, the distribution of airflow is allocated according to the distribution area of ​​dust, so that the airflow can carry away as much dust as possible, achieving a highly efficient dust removal effect.

[0036] Furthermore, the flow regulating component includes a smoke concentration sensor 42 and a flow valve 43 arranged sequentially along the airflow direction. The smoke concentration sensor 42 is disposed in the air intake channel 400 and is used to detect the amount of smoke in the airflow in the air intake channel 400. The flow valve 43 is configured to adjust the opening size according to the amount of smoke detected by the smoke concentration sensor 42, and the opening of the flow valve 43 increases with the increase of the amount of smoke.

[0037] In some embodiments, a plurality of partition plates 41 distributed in central symmetry are provided inside the air intake cylinder 40. As Figure 6 shown, the number of the partition plates 41 is eight. Accordingly, eight air intake channels 400 are separated at the inlet end of the air intake cylinder 40. Any two adjacent air intake channels 400 are separated by the partition plates 41. A housing 401 is fixedly provided on the outer side wall of the air intake cylinder 40. A smoke concentration sensor 42 is fixedly installed in the housing 401. A background plate 421 is provided on the inner side wall of the air intake cylinder 40 corresponding to the output end of the smoke concentration sensor 42. Among them, the smoke concentration sensor 42 adopts a photoelectric sensor, and the photoelectric sensor is composed of a light source and a photosensitive element. When there is no smoke, the light emitted by the light source propagates directly, and the photosensitive element does not receive a signal. When there is smoke, the smoke particles scatter or absorb the light, causing a change in the optical signal received by the photosensitive element. The smoke particles will absorb part of the light, resulting in a decrease in the light intensity received by the photosensitive element. By measuring the change in the light intensity, the smoke concentration can be indirectly judged. The background plate 421 helps with light reflection. Thus, the opening degree of the flow valve 43 is adjusted according to the smoke concentration.

[0038] Since there are many particulate matters in the soot inhaled by the air intake cylinder 40, generally a hose is arranged between the air intake cylinder 40 and the air extraction device to convey the dust-containing air flow. However, since the bending degree of the robotic arm 20 is relatively large during operation, and the soot particles in the dust-containing air flow are easy to adhere to the pipe wall, causing partial blockage of the pipe wall and affecting normal smoke exhaust. Thus, in the present invention, a dust filtering cylinder 50 is provided between the air intake cylinder 40 and the air suction cylinder 60. A filter element 53 is provided inside the dust filtering cylinder 50, and the filter element 53 is configured to intercept the soot in the air flow in the dust filtering cylinder 50.

[0039] As Figure 5 shown, the filter element 53 includes a flow guiding cover 531 and a filter screen 532. Along the air flow conveying direction, the flow guiding cover 531 is arranged on the front side of the filter screen 532, and both the flow guiding cover 531 and the filter screen 532 are configured as cylinders with a "U" - shaped cross section. The flow guiding cover 531 is arranged outside the filter screen 532. Thus, during the process of the air flow flowing in the dust filtering cylinder 50, it will pass through the flow guiding of the flow guiding cover 531 and then pass through the filter screen 532.

[0040] Furthermore, a confluence channel 5300 for the air flow to flow is provided between the flow guiding cover 531 and the inner wall of the dust filtering cylinder 50. A dust filtering channel 5311 is provided between the flow guiding cover 531 and the filter screen 532. A plurality of air guiding holes 5310 distributed in central symmetry are opened at the tail end of the flow guiding cover 531. The confluence channel 5300 and the dust filtering channel 5311 are connected through the air guiding holes 5310.

[0041] During operation, under the influence of negative pressure, the dust-laden airflow enters the dust filter cartridge 50 through the air inlet 40. It first flows into the confluence channel 5300 under the action of the guide hood 531, and then enters the dust filter channel 5311 between the guide hood 531 and the filter screen 532 after passing through the air guide hole 5310 on the guide hood 531. The airflow in the dust-laden airflow flows backward after passing through the filter screen 532, while the dust particles are blocked by the filter screen 532 and remain in the dust filter channel 5311, thus achieving the filtration of dust in the dust-laden airflow.

[0042] In order to regularly clean the dust in the dust filtration channel 5311, the filter element 53 also includes a water distribution cylinder 533, which is located inside the filter screen 532 and has a set gap between it and the filter screen 532, so that the airflow in the dust filtration channel 5311 can pass through the filter screen 532 and enter the air intake cylinder 60.

[0043] The dust filter 50 has a water inlet connector 51 on its outer wall corresponding to the tail end of the water distribution tube 533. The water distribution tube 533 has a hollow structure. The inside of the water distribution tube 533 has a water distribution chamber 5330 that communicates with the water inlet connector 51. The area on the outer wall of the water distribution tube 533 corresponding to the filter screen 532 has a water spray hole 5331. The outer wall of the dust filter 50 has a drain connector 52 corresponding to the head end of the guide hood 531. The drain connector 52 communicates with the dust filter channel 5311.

[0044] In some embodiments, the water inlet connector 51 is connected to an external water supply device, and the drain connector 52 is connected to an external water pumping device. The water in the water distribution chamber 5330 can blow the dust adhering to the surface of the filter screen 532 back into the dust filter channel 5311, and then pump it out through the drain connector 52.

[0045] It should be understood that a differential pressure sensor is installed in the dust filter cartridge 50. The differential pressure sensor is used to detect the pressure difference between the airflow on the front and rear sides of the filter screen 532. When the pressure difference reaches a set threshold, it indicates that the dust particle content in the dust filter channel 5311 has reached the level that needs to be cleaned. At this time, water is connected to the water inlet connector 51, and the water flows into the water distribution cartridge 533. The water flows through the water distribution chamber 5330 inside the water distribution cartridge 533 and fills the entire water distribution cartridge 533. Then, the water is distributed through the water distribution chamber. The water spray hole 5331 on the filter cylinder 533 sprays water from the inside to the outside of the filter screen 532, which plays a backwashing role on the dust adhering to the filter screen 532. It can remove the dust adhering to the filter screen 532. The dust falls into the space between the guide hood 531 and the filter screen 532. The drain connector 52 is connected to the guide hood 531, which can discharge the washed dust and water, while preventing water from flowing into the confluence channel 5300, so that the dust filter cylinder 50 can continue to filter dust.

[0046] Furthermore, the air intake 60 is provided with a return chamber 600 inside, which is connected to the inner space of the filter screen 532. An air intake connector 61 is fixedly provided on the outer wall of the air intake 60. The air intake connector 61 is connected to an external air extraction device and is connected to the return chamber 600. During operation, the external air extraction device draws air into the air intake 60, making the air intake 60 a negative pressure state, which causes the airflow to enter the air intake 60 through the air intake 40 and the dust filter 50, thereby drawing out the fumes generated by the welding torch 10 during operation.

[0047] In conjunction with the above embodiments, by setting a dust suction cylinder 30 that can move with the welding torch 10 on the outside of the welding torch 10, it is beneficial to extract and treat the fumes at the source of the fumes. Furthermore, the air intake cylinder 40 has multiple air intake channels 400 distributed around the welding torch 10. The air intake channels 400 at different positions can distribute the airflow in each air intake channel 400 according to the distribution area of ​​the fumes, so that the airflow can carry away as much fumes as possible. While maintaining a certain suction power, it can achieve a high-efficiency dust removal effect. At the same time, the dust filter cylinder 50 can filter the fumes particles on the rear side of the air intake channel 400 and backwash periodically, without affecting the continuity of the fumes exhaust when the welding torch 10 is working.

[0048] 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.

[0049] The embodiments have been described above, and such description is not restrictive. The figures shown are only one embodiment, and the actual structure is not limited to this. In short, if a person skilled in the art is inspired by this description and designs a similar structure and embodiment without departing from the inventive spirit, such design should fall within the scope of protection.

Claims

1. An environmentally friendly steel structure electric arc welding device, characterized in that, Comprising: A welding torch (10), installed at the end of a robotic arm (20) and capable of being driven to move by the robotic arm (20); A dust suction cylinder (30), arranged around the welding torch (10); Wherein, the dust suction cylinder (30) includes an air intake cylinder (40) facing the head end of the welding torch (10) and a suction cylinder (60) connected to an external air extraction device. The air intake cylinder (40) is communicated with the suction cylinder (60). A plurality of air intake channels (400) are provided around the circumference of the welding torch (10) inside the air intake cylinder (40). Each air intake channel (400) is provided with an air flow rate adjusting member. The flow rate adjusting member is configured to adjust the air flow rate passing through the air intake channel (400) according to the amount of soot in the air intake channel (400). By adjusting the opening degree of the flow rate adjusting member, the air flow rate in the air intake channel (400) is positively correlated with the amount of soot; A dust filter cylinder (50) is provided between the air intake cylinder (40) and the suction cylinder (60). A filter element (53) is provided inside the dust filter cylinder (50). The filter element (53) is configured to intercept the soot in the air flow in the dust filter cylinder (50); The filter element (53) includes a flow guide cover (531) and a filter screen (532). Along the air flow conveying direction, the flow guide cover (531) is arranged on the front side of the filter screen (532), and both the flow guide cover (531) and the filter screen (532) are constructed as cylinders with a "U" - shaped cross - section. The flow guide cover (531) is arranged outside the filter screen (532). There is a confluence channel (5300) for air flow between the flow guide cover (531) and the inner wall of the dust filter cylinder (50). There is a dust filtering channel (5311) between the flow guide cover (531) and the filter screen (532). A plurality of guide air holes (5310) symmetrically distributed around the center are opened at the tail end of the flow guide cover (531). The confluence channel (5300) and the dust filtering channel (5311) are communicated through the guide air holes (5310); The filter element (53) further includes a water distribution cylinder (533). The water distribution cylinder (533) is arranged inside the filter screen (532), and there is a set gap between the water distribution cylinder (533) and the filter screen (532), so that the air flow in the dust filtering channel (5311) can pass through the filter screen (532) and enter the suction cylinder (60).

2. The environmentally friendly steel structure electric arc welding device according to claim 1, characterized in that: The flow rate adjusting member includes a smoke concentration sensor (42) and a flow valve (43) arranged in sequence along the air flow direction. The smoke concentration sensor (42) is arranged in the air intake channel (400) and is used to detect the amount of soot in the air flow in the air intake channel (400). The flow valve (43) is constructed to adjust the opening degree according to the amount of soot detected by the smoke concentration sensor (42), and the opening degree of the flow valve (43) increases with the increase of the amount of soot.

3. The environmentally friendly steel structure arc welding device according to claim 2, characterized in that: The air intake cylinder (40) has multiple partitions (41) arranged in a centrally symmetrical manner inside. Any two adjacent air intake channels (400) are separated by the partitions (41). A housing (401) is fixedly provided on the outer wall of the air intake cylinder (40). The smoke concentration sensor (42) is fixedly installed inside the housing (401). A background plate (421) is provided on the inner wall of the air intake cylinder (40) corresponding to the output end of the smoke concentration sensor (42).

4. The environmentally friendly steel structure electric arc welding device according to claim 1, characterized in that: The outer wall of the dust filter tube (50) is provided with a water inlet connector (51) corresponding to the tail end of the water distribution tube (533). The water distribution tube (533) is hollow. The interior of the water distribution tube (533) is provided with a water distribution cavity (5330) communicating with the water inlet connector (51). The area on the outer wall of the water distribution tube (533) corresponding to the filter screen (532) is provided with a water spray hole (5331).

5. The environmentally friendly steel structure arc welding device according to claim 4, characterized in that: The outer wall of the dust filter cartridge (50) is provided with a drain connector (52) corresponding to the head end of the flow guide hood (531), and the drain connector (52) is connected to the dust filter channel (5311).

6. The environmentally friendly steel structure electric arc welding device according to claim 5, characterized in that: The water inlet connector (51) is connected to an external water supply device, and the drain connector (52) is connected to an external water pumping device. The water in the water distribution chamber (5330) can blow the dust adhering to the surface of the filter screen (532) back into the dust filter channel (5311) and be pumped out through the drain connector (52).

7. The environmentally friendly steel structure electric arc welding device according to claim 1, characterized in that: The air intake cylinder (60) has a return chamber (600) inside, which is connected to the inner space of the filter screen (532). An air intake connector (61) is fixedly provided on the outer wall of the air intake cylinder (60), which is connected to an external air extraction device and is connected to the return chamber (600).

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