A silent axial flow fan with a drum-type damper

Abstract

The present invention provides a silent axial flow fan with a drum-type damper, which belongs to the technical field of axial flow fans, wherein a top sealing plate is provided at one end of the air outlet section away from the main section, a guide cover is provided on the side of the top sealing plate facing the inside of the air outlet section, a motor is installed on the side of the top sealing plate facing the outside of the air outlet section, a fan impeller is fixedly sleeved on the output shaft end of the motor, a plurality of air outlet section openings are provided on the side wall of the air outlet section, in the circumferential direction of the side wall of the air outlet section, the spacing of the air outlet section openings is greater than the pore width of the air outlet section openings, a drum-type damper is rotatably sleeved on the outer side of the side wall of the air outlet section in a matching manner, a plurality of damper openings corresponding to the air outlet section openings are provided on the drum-type damper, and a driving mechanism for controlling its rotation is also connected. The present invention controls the opening and closing of the air outlet through quick and easy operation, reduces wind resistance, noise and energy consumption, and improves the operating environment of the motor.

Description

Technical Field

[0001] The invention belongs to the technical field of axial flow fans, and in particular relates to a silent axial flow fan with a drum-type damper. Background Art

[0002] Axial flow fans, also known as local ventilators, are commonly used in industrial and mining enterprises. For example, the exhaust gas high-efficiency purification system at the top of the urea granulation tower currently has multiple axial flow fans installed at the multiple air outlets at the top. The traditional axial flow fan structure is as follows Figure 8 As shown, the motor 10' is directly connected to the fan impeller 4', and the motor 10' is fixed in the cylindrical main body section 2' housing, with air entering at one end and air exiting at the other end. The main problems are as follows:

[0003] 1. When only some fans are started, the impellers of other fans that have not started will start to reverse due to negative pressure, causing these fans to fail to start. The current solution is to manually add a wind shield at the outlet of the fan to be started, and then quickly remove the wind shield after the fan starts. This work is inefficient and requires more than two people to complete the normal start of the fan.

[0004] 2. When the fan is running, because the motor in the air duct is fixed horizontally, the local resistance suddenly increases when the gas flows through the motor, resulting in serious turbulence and loud noise.

[0005] 3. When the fan is running, serious vortex will occur due to the influence of the motor and the motor's fixed seat. A negative pressure area will be formed in the local area of ​​the air outlet, which will suck the outside air into the fan and then discharge it through the rotation of the fan impeller. This part of the air flow in and out of the air outlet is completely meaningless, and will increase energy consumption. It will also suck the external dusty air into the equipment, causing the system operation performance to fail to meet environmental protection requirements.

[0006] 4. When the system is running, the gas temperature is around 60°C. If the motor is placed in a high temperature environment for a long time, it will have a relatively large impact on the heat dissipation of the motor and will also have a certain impact on the motor's service life.

[0007] 5. There is a small amount of urea dust in the air flow. Although the content is less than 10mg / m³, long-term exposure to dust will still have a certain impact on the motor.

[0008] 6. When the fan is out of use, it also needs to be covered manually to prevent rain and snow from entering the fan and the fan from reversing, which is time-consuming and laborious. Summary of the invention

[0009] Based on the technical problems existing in the prior art, the present invention provides a silent axial flow fan with a drum-type damper, which can seal / open the air outlet through quick and easy operation, reduce wind resistance, noise and energy consumption, and avoid the above-mentioned disadvantages of the prior art.

[0010] According to the technical solution of the present invention, the present invention provides a silent axial flow fan with a drum-type damper, which includes an air inlet section, a main section and an air outlet section connected in sequence, and the main structures of the air inlet section, the main section and the air outlet section are all cylindrical; a fan impeller and a bearing seat are provided in the main section, the bearing seat is connected to the side wall of the main section through a fixed rib plate, and a bearing is installed in the bearing seat; a top sealing plate is provided at one end of the air outlet section away from the main section, and a guide cover is provided on the side of the top sealing plate facing the inside of the air outlet section, and a motor is installed and connected to the top sealing plate through a motor seat on the side facing the outside of the air outlet section; a sealing plate through hole is provided on the top sealing plate, and a guide cover through hole is provided on the guide cover, the output shaft end of the motor passes through the sealing plate through hole, the guide cover through hole and the bearing in the bearing seat, and the fan impeller fixing sleeve is provided on the output shaft end of the motor.

[0011] Among them, a plurality of air outlet section openings are provided on the side wall of the air outlet section; in the circumferential direction of the side wall of the air outlet section, the spacing between the air outlet section openings is greater than the pore width of the air outlet section openings; a drum-type air door is rotatably sleeved on the outer side of the side wall of the air outlet section to match, and a plurality of air door openings corresponding to the air outlet section openings are provided on the drum-type air door; the drum-type air door is also connected to a driving mechanism for controlling its rotation.

[0012] Furthermore, the driving mechanism includes a driving arm rotatably connected to the top sealing plate and a cylinder rotatably connected to the top sealing plate; the output end of the cylinder is rotatably connected to the driving arm; the end of the driving arm extends outward to the outside of the outline of the top sealing plate, and the end of the driving arm is provided with a strip slot hole that passes through up and down along its length direction; a toggle rod is provided on the outer surface of one end of the drum-type damper close to the top sealing plate, extending toward the top sealing plate, and the toggle rod is inserted into the strip slot hole.

[0013] Preferably, an annular slide rail is provided on the outer side of one end of the side wall of the air outlet section close to the main section, a plane bearing is provided on the inner wall of the annular slide rail close to the main section, and the drum-type air door is embedded in the annular slide rail and in contact with the plane bearing.

[0014] Preferably, a plurality of reinforcing ribs are connected between the air guide cover and the top sealing plate.

[0015] Preferably, an air outlet guide ring is provided on the inner side surface of one end of the air outlet section close to the main body section.

[0016] Preferably, the openings of the air outlet section are strip holes, the length direction of the openings of the air outlet section is the same as the axial direction of the side wall of the air outlet section, and the openings of the air outlet section are evenly arranged along the circumference of the side wall of the air outlet section.

[0017] Preferably, the total area of ​​the openings in the air outlet section is 1.5-2.5 times the cross-sectional area of ​​the internal space of the air outlet section.

[0018] Preferably, a sealing layer is provided on the outer side of the air outlet section, and the outer side of the sealing layer fits with the inner side of the drum-type damper; or, a sealing layer is provided on the inner side of the drum-type damper, and the inner side of the sealing layer fits with the outer side of the air outlet section.

[0019] Preferably, the main body section, the air inlet section and the air outlet section are detachably connected separate structures, and flanges are provided at adjacent positions of the three sections and are connected by bolt and nut assemblies.

[0020] Preferably, an air inlet guide ring is provided on the inner side surface of the air inlet section.

[0021] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0022] 1. The present invention adopts a drum-type damper with an original rotating structure, which can open and close the fan outlet by rotating a small angle, and is easy to operate and quick to move. It avoids the trouble of manually placing and removing the wind shield cover in the prior art, and on this basis, a PLC controller can be used to realize automatic control of the drum-type damper.

[0023] 2. The present invention places the motor outside and is provided with a guide device such as a guide cover, thereby reducing wind resistance and turbulence, reducing noise and energy consumption. In addition, since serious turbulence is avoided and the air is discharged from all sides, the problem caused by the formation of a negative pressure area at the air outlet in the prior art is avoided.

[0024] 3. The present invention places the motor externally, thereby reducing the ambient temperature of the motor, facilitating the heat dissipation of the motor, and preventing the motor from directly contacting the dusty gas flowing through the fan, thereby improving the efficiency and service life of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of a silent axial flow fan with a drum-type damper according to an embodiment of the present invention.

[0026] Figure 2 yes Figure 1 Schematic diagram of the top view of the main section and the drum damper in the open state.

[0027] Figure 3 yes Figure 2 Schematic diagram of the partial structure of part B of the middle drum damper in the closed state.

[0028] Figure 4The present invention is a schematic diagram of the structure of the opening of the air outlet section of the silent axial flow fan with a drum-type air door.

[0029] Figure 5 yes Figure 1 A schematic diagram of the structure of the embodiment shown is a top view.

[0030] Figure 6 yes Figure 1 Schematic diagram of the local structure of part A.

[0031] Figure 7 It is a schematic diagram of the top view of the main body section in another embodiment of the present invention.

[0032] Figure 8 It is a structural schematic diagram of an existing axial flow fan.

[0033] Explanation of the reference numerals in the accompanying drawings: 1. air inlet section; 2. main section; 3. air outlet section; 4. fan impeller; 5. bearing seat; 6. fixed rib plate; 7. top cover plate; 8. air guide cover; 9. motor seat; 10. motor; 11. air outlet section opening; 12. drum damper; 13. damper opening; 14. driving mechanism; 15. driving arm; 16. cylinder; 17. strip slot; 18. toggle lever; 19. annular slide rail; 20. plane bearing; 21. reinforcing rib; 22. sealing layer; 23. air inlet guide ring; 24. coupling; 25. transmission shaft; 26. cylinder shaft; 27. driving arm shaft; 28. air outlet guide ring. DETAILED DESCRIPTION

[0034] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention.

[0035] It will be understood by those skilled in the art that, unless expressly stated, the singular forms "one", "said", and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be intermediate elements. In addition, the "connection" or "coupling" used herein may include wireless connection or coupling. The term "and / or" used herein includes any unit and all combinations of one or more associated listed items.

[0036] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the field to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0037] To facilitate understanding of the embodiments of the present invention, several specific embodiments will be further explained below with reference to the accompanying drawings, and each embodiment does not constitute a limitation on the embodiments of the present invention.

[0038] The present invention provides a silent axial flow fan with a drum-type damper, the improvement focuses on: 1. The motor is placed outside; 2. The side air outlet is adopted and a guide structure is provided; 3. The drum-type damper with an original rotating structure is provided at the air outlet. Thus, the air outlet can be sealed by quick and easy operation, and the wind resistance, noise and energy consumption are reduced, the operating environment of the motor is improved, and the above-mentioned disadvantages of the prior art are avoided.

[0039] See also Figure 1 The present invention provides a silent axial flow fan with a drum-type damper, which includes an air inlet section 1, a main body section 2 and an air outlet section 3 connected in sequence. The main structures of the air inlet section, the main body section and the air outlet section are all cylindrical, and the three are preferably detachably connected split structures. For example, flanges (i.e., a circular ring structure extending outward from the pipe mouth of the circular tube structure, and a plurality of through holes are opened on the circular ring) are provided at the adjacent positions of the three (i.e., the upper end of the air inlet section 1, the upper and lower ends of the main body section 2, and the lower end of the air outlet section 3). The adjacent flanges on the two parts are fitted together, and bolts are inserted into the through holes, and nuts are then installed at the ends to form a bolt-nut assembly for connection. In this way, the air inlet section 1, the main body section 2 and the air outlet section 3 are processed in sections and then assembled. The processing process is easier to carry out and the processing accuracy can be guaranteed; it is also convenient for the inspection and replacement of internal components.

[0040] The air inlet section 1 is preferably provided with a guide device on the inner side, such as a bell-shaped arc-shaped air inlet guide ring 23 facing outward, so as to reduce the air inlet vortex, reduce the air inlet resistance, and reduce wind noise.

[0041] The main body section 2 has a fan impeller 4 and a bearing seat 5, and a bearing is installed in the bearing seat 5. The axis of the fan impeller 4 and the bearing coincides with the axis of the main body section 2. The bearing seat 5 is connected to the side wall of the main body section 2 through a fixed rib plate 6, preferably as follows Figure 7As shown, the fixed ribs 6 are multiple radially arranged, and the bearing seat 5 and the fixed ribs 6 are very small in size, and the fixed ribs 6 have a large gap, which has almost no turbulence and resistance to the passing airflow, greatly reducing wind resistance and wind noise. Figure 1 In the illustrated embodiment, the fan impeller 4 is located on the side of the bearing seat 5 close to the air inlet section 1, and the bearing is close to the fan impeller 4, which ensures that the drive shaft 25 shakes less and reduces the lateral vibration of the fan impeller 4 when the fan is running, so that the operation is stable and no large vibration and noise are generated. It is conceivable that the fan impeller 4 can also be located on the side of the bearing seat 5 away from the air inlet section 1, that is, the bearing seat 5 is closer to the air inlet, but a relatively longer drive shaft is required. On the other hand, the solution of the present invention can reduce the required height of the main section 2 after the motor 10 is externalized, so that the roundness can be guaranteed when the cylinder of the main section 2 is rolled, and the inside is machined to further improve the assembly accuracy, so that the gap between the outside of the fan impeller 4 and the inside of the main section 2 is smaller, thereby improving the efficiency of the fan.

[0042] A top sealing plate 7 is provided at one end of the air outlet section 3 away from the main section 2, and a motor 10 is installed and connected to the top sealing plate 7 on the side (upper side) facing the outside of the air outlet section 3 through a motor seat 9. In a specific embodiment, the motor 10 is a vertical motor, and the motor 10 and the motor seat 9 have a flange structure and are connected by bolts. The solution of the present invention places the motor 10 outside the fan, which is convenient for maintenance and overhaul, and prevents the motor 10 from contacting dusty high-temperature gas, reduces damage to the motor 10, and effectively prolongs the service life.

[0043] The top sealing plate 7 is provided with a deflector 8 on one side (lower side) facing the air outlet section 3. The deflector 8 may be called a large arc deflector, which is similar to an umbrella shape and guides the upward-flowing gas to the surroundings, which can effectively reduce sudden changes in airflow, reduce resistance, and reduce wind noise. The top sealing plate 7 is provided with a sealing plate through hole, and the deflector 8 is provided with a deflector through hole. The output shaft end of the motor 10 passes through the sealing plate through hole and the deflector through hole, and the end is inserted into the bearing installed in the bearing seat 5. The fan impeller 4 is fixedly sleeved on the output shaft end of the motor 10. In a specific embodiment, as Figure 1 As shown, the output shaft end of the motor 10 includes a motor output shaft and a transmission shaft 25. The motor output shaft passes downward through the motor seat 9 (also having a through hole) and the top sealing plate 7, and then is connected to the transmission shaft 25 through the coupling 24. The transmission shaft 25 continues to extend downward, passes through the bearing of the bearing seat 5, and is fixedly connected to the fan impeller 4. There is only a small gap between the sealing plate through hole and the air guide cover through hole and the output shaft end of the motor 10. The output shaft end of the motor 10 rotates therein without collision or friction. At the same time, the seal can be basically guaranteed. The gas will be preferentially diverted to the surroundings, and only a very small amount enters between the air guide cover 8 and the top sealing plate 7, and the impact can be ignored.

[0044] Preferably, a plurality of plate-shaped reinforcing ribs 21 , for example, vertically arranged, are connected between the air deflector 8 and the top sealing plate 7 to play a supporting and reinforcing role and ensure the strength of the air deflector 8 and the motor base 9 .

[0045] Preferably, a guide device, such as a bell-shaped arc-shaped air guide ring 28 facing outward, is provided on the inner side surface of one end of the air outlet section 3 close to the main section 2, so as to reduce the air outlet vortex, reduce the air outlet resistance, and reduce wind noise.

[0046] See also Figures 2 to 4 , a plurality of air outlet openings 11 are provided on the side wall of the air outlet section 3. In the circumferential direction of the side wall of the air outlet section 3, the spacing D of the air outlet openings 11 is greater than the pore width W of the air outlet openings 11. A drum-type damper 12 is rotatably sleeved on the outer side of the side wall of the air outlet section 3, and a plurality of damper openings 13 corresponding to the air outlet openings 11 are provided on the drum-type damper 12. For example Figure 4 As shown, the air outlet section opening 11 is a strip hole, the length direction of the air outlet section opening 11 is the same as the axial direction of the side wall of the air outlet section 3, the air outlet section opening 11 is evenly arranged along the circumference of the side wall of the air outlet section 3, and its specific size is, for example, the pore width W of the strip hole is 65mm, the pore length is 1100mm, the spacing D is 72mm, the length of the cylindrical section of the air outlet section 3 is slightly greater than 1100mm, and the air outlet section opening 11 is arranged in the middle of the length direction of the air outlet section 3. Further preferably, the total area of ​​the air outlet section opening 11 is about twice the cross-sectional area of ​​the internal space of the air outlet section 3, for example, in the range of 1.5-2.5 times, so that the total area of ​​the air outlet is increased, the gas flow rate of the air outlet is reduced, the gas resistance is reduced, and the wind noise is reduced. This method of setting the openings at a certain distance can not only reduce the weight of the air outlet section 3, but also ensure the strength and meet the requirements of the top support motor 10; and the hole width W is small, so only a small rotation angle is required to open and close the air outlet, and the action is fast and the operation is quick. It can be imagined that the setting method of the air outlet section opening 11 and the air door opening 13 is not limited to this, for example, it can be set as an oblique strip hole, or a dot-shaped circular hole, or a grid-shaped square hole, etc., which can achieve the same effect as above (that is, as Figure 2 As shown, the air outlet section opening 11 and the air door opening 13 can overlap to form an open air outlet. After the drum-type air door 12 is rotated to a certain angle, as shown in FIG. Figure 2 Part B is converted to Figure 3 As shown, any specific method that can achieve complete closure of the air outlet is possible.

[0047] Preferably, a sealing layer 22 is provided on the outer side of the air outlet section 3, and the outer side of the sealing layer 22 is in contact with the inner side of the drum damper 12; or, a sealing layer 22 is provided on the inner side of the drum damper 12, and the inner side of the sealing layer 22 is in contact with the outer side of the air outlet section 3. The surface of the sealing layer 22 is relatively smooth and has a certain elasticity, for example, an elastic coating of Teflon (polytetrafluoroethylene, PTFE), so as to play a sealing role between the two hard steel cylinders of the air outlet section 3 and the drum damper 12, so that the drum damper 12 has better sealing performance when it is placed in the air outlet closed position, thereby better avoiding the problem of the fan impeller 4 in the prior art being reversed under the influence of other fans.

[0048] The drum type damper 12 is also connected to a driving mechanism 14 for controlling its rotation. Figure 1 and Figure 5 The driving mechanism 14 includes a driving arm 15 rotatably connected to the top sealing plate 7 and a cylinder 16 rotatably connected to the top sealing plate 7. For example, the barrel of the cylinder 16 is hinged to the upper surface of the top sealing plate 7 through a cylinder shaft 26, and the driving arm 15 is hinged to the upper surface of the top sealing plate through a driving arm shaft 27 in the middle. The cylinder 16 is connected to external compressed air, and the output end of the cylinder 16 is rotatably connected to the driving arm 15. For example, the end of the piston rod of the cylinder 16 is hinged to the driving arm 15. The end of the driving arm 15 extends outward to the outside of the contour of the top sealing plate 7, and the end of the driving arm 15 is provided with a strip slot 17 that passes through from top to bottom along its length direction. A toggle rod 18 is provided on the outer surface of one end of the drum damper 12 close to the top sealing plate 7, extending toward the top sealing plate 7. The toggle rod 18 penetrates into the strip slot 17 and can slide smoothly in the strip slot 17.

[0049] The working principle of the driving mechanism 14 is that the piston rod of the compressed air driving cylinder 16 is extended and retracted, thereby pushing / pulling the driving arm 15 to rotate around the driving arm rotating shaft 27, and the toggle rod 18 can slide in the length direction of the strip slot 17 and be pushed in the width direction, thereby driving the drum damper 12 to rotate. It can be understood that the driving arm of the present invention is not limited to Figure 5 The L-shaped plate shown, the hinge point of the cylinder 16 and the driving arm 15 and the strip slot 17 can also be located on the same side of the driving arm shaft 27, as long as the cylinder 16 can drive the driving arm 15 to rotate a certain angle. Further preferably, a PLC controller can be used to automatically control the cylinder 16.

[0050] like Figure 1In the illustrated embodiment, the edge profile of the top cover plate 7 is larger than the air outlet section 3 and the drum-type damper 12, so that it can completely cover and better be fixedly connected to the air outlet section 3, ensuring that the top cover plate 7 can bear the weight of the motor 10 and other components thereon. For this structure, a cross bar needs to be welded between the toggle rod 18 and the outer side surface of the drum-type damper 12, so that the toggle rod 18 can be set upward without being blocked by the edge of the top cover plate 7.

[0051] See also Figure 6 (for Figure 1 Part A), in a preferred embodiment, a groove-shaped annular slide rail 19 is provided on the outer side of the side wall of the air outlet section 3 near one end of the main body section 2, for example, a groove-shaped groove with an opening facing upward, so as to support the drum-type damper 12. Furthermore, a plane bearing 20 (for example, a needle bearing) is provided on the inner wall of the annular slide rail 19 near the main body section 2, and the drum-type damper 12 is embedded in the annular slide rail 19 and contacts the plane bearing 20. This makes it easy for the drum-type damper 12 to rotate. It is conceivable that, for example, one or more protrusions are provided on the outer side surface of the air outlet section 3, and the drum-type damper 12 is grooved accordingly; or a baffle is extended inwardly from the upper edge of the drum-type damper 12 so that it can be mounted on the top sealing plate 7; etc. Other movable connection methods that can limit the drum-type damper 12 are also possible.

[0052] In summary, the present invention has the following beneficial technical effects compared with the prior art:

[0053] 1. The present invention adopts a drum-type damper with an original rotating structure, which can open and close the fan outlet by rotating a small angle, and is easy to operate and quick to move. It avoids the trouble of manually placing and removing the wind shield cover in the prior art, and on this basis, a PLC controller can be used to realize automatic control of the drum-type damper.

[0054] 2. The present invention places the motor outside and is provided with a guide device such as a guide cover, thereby reducing wind resistance and turbulence, reducing noise and energy consumption. In addition, since serious turbulence is avoided and the air is discharged from all sides, the problem caused by the formation of a negative pressure area at the air outlet in the prior art is avoided.

[0055] 3. The present invention places the motor externally, thereby reducing the ambient temperature of the motor, facilitating the heat dissipation of the motor, and preventing the motor from directly contacting the dusty gas flowing through the fan, thereby improving the efficiency and service life of the motor.

[0056] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A silent axial flow fan with a drum-type damper, characterized in that: It comprises an air inlet section (1), a main body section (2) and an air outlet section (3) which are connected in sequence, and the main structures of the air inlet section (1), the main body section (2) and the air outlet section (3) are all cylindrical; The main body section (2) comprises a fan impeller (4) and a bearing seat (5); the bearing seat (5) is connected to the side wall of the main body section (2) via a fixed rib plate (6); a bearing is installed in the bearing seat (5); the axis of the fan impeller (4) and the bearing coincides with the axis of the main body section (2); the fan impeller (4) is located on a side of the bearing seat (5) close to the air inlet section (1), and the bearing is close to the fan impeller (4); A top sealing plate (7) is provided at one end of the air outlet section (3) away from the main section (2); a flow guide cover (8) is provided on the side of the top sealing plate (7) facing the inside of the air outlet section (3); a motor (10) is installed and connected to the top sealing plate (7) on the side facing the outside of the air outlet section (3) through a motor seat (9); a sealing plate through hole is provided on the top sealing plate (7); a flow guide cover through hole is provided on the flow guide cover (8); an output shaft end of the motor (10) passes through the sealing plate through hole, the flow guide cover through hole, and the output shaft end of the motor (10) passes through a bearing in a bearing seat (5); and the fan blades The wheel (4) is fixedly sleeved on the output shaft end of the motor (10); the motor (10) is a vertical motor, and the motor (10) and the motor seat (9) have a flange structure and are connected by bolts; the output shaft end of the motor (10) includes a motor output shaft and a transmission shaft (25), the motor output shaft passes downward through the motor seat (9) having a through hole and the top cover plate (7), and is then connected to the transmission shaft (25) through a coupling (24), and the transmission shaft (25) continues to extend downward, passes through the bearing of the bearing seat (5), and is fixedly connected to the fan impeller (4); A plurality of air outlet section openings (11) are provided on the side wall of the air outlet section (3); in the circumferential direction of the side wall of the air outlet section (3), the spacing (D) of the air outlet section openings (11) is greater than the pore width (W) of the air outlet section openings (11); a drum-type air door (12) is rotatably sleeved on the outer side of the side wall of the air outlet section (3) in a matching manner, and the drum-type air door (12) is provided with a plurality of air door openings (13) corresponding one-to-one to the air outlet section openings (11); the drum-type air door (12) is also connected to a driving mechanism (14) for controlling its rotation; The driving mechanism (14) comprises a driving arm (15) rotatably connected to the top sealing plate (7) and a cylinder (16) rotatably connected to the top sealing plate (7); the output end of the cylinder (16) is rotatably connected to the driving arm (15); the end of the driving arm (15) extends outward to the outside of the contour of the top sealing plate (7), and the end of the driving arm (15) is provided with a strip slot (17) extending vertically along its length direction; and a toggle rod (18) is provided on the outer surface of one end of the drum-type damper (12) close to the top sealing plate (7) and extending toward the top sealing plate (7), and the toggle rod (18) penetrates into the strip slot (17).

2. The silent axial flow fan with a drum-type damper according to claim 1, characterized in that: An annular slide rail (19) is arranged on the outer side of one end of the side wall of the air outlet section (3) close to the main section (2), a plane bearing (20) is arranged on the inner wall of the annular slide rail (19) close to the main section (2), and the drum-type air door (12) is embedded in the annular slide rail (19) and in contact with the plane bearing (20).

3. The silent axial flow fan with a drum-type damper according to claim 1, characterized in that: A plurality of reinforcing ribs (21) are connected between the air guide cover (8) and the top sealing plate (7).

4. The silent axial flow fan with a drum-type damper according to claim 1, characterized in that: An air outlet guide ring (28) is provided on the inner side surface of one end of the air outlet section (3) close to the main body section (2).

5. The silent axial flow fan with a drum-type damper according to claim 1, characterized in that: The air outlet section opening (11) is a strip-shaped hole, the length direction of the air outlet section opening (11) is the same as the axial direction of the side wall of the air outlet section (3), and the air outlet section opening (11) is evenly arranged along the circumference of the side wall of the air outlet section (3).

6. The silent axial flow fan with a drum-type damper according to claim 5, characterized in that: The total area of ​​the openings (11) of the air outlet section is 1.5 to 2.5 times the cross-sectional area of ​​the internal space of the air outlet section (3).

7. The silent axial flow fan with a drum damper according to any one of claims 1 to 6, characterized in that: The outer side surface of the air outlet section (3) is provided with a sealing layer (22), and the outer side surface of the sealing layer (22) is in contact with the inner side surface of the drum-type damper (12); or, the inner side surface of the drum-type damper (12) is provided with a sealing layer (22), and the inner side surface of the sealing layer (22) is in contact with the outer side surface of the air outlet section (3).

8. The silent axial flow fan with a drum damper according to any one of claims 1 to 6, characterized in that: The main body section (2), the air inlet section (1) and the air outlet section (3) are detachably connected split structures, and flanges are provided at adjacent locations of the three sections and are connected via bolt and nut assemblies.

9. The silent axial flow fan with a drum damper according to any one of claims 1 to 6, characterized in that: An air inlet guide ring (23) is provided on the inner side surface of the air inlet section (1).

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