Low noise axial flow fan

Abstract

The utility model discloses a low noise axial flow fan relates to axial flow fan technical field, the utility model discloses a shell and transmission shaft are connected with the support top -notch limit support in the shell inside, and the limit support outer part is respectively sleeved with the control sleeve and the anti -drop sleeve, and the transmission shaft top is connected with the key strip. The utility model discloses through the setting of the snap and the limit support, when needing to overhaul, only need to hold the impeller with one hand, avoid the impeller to hit the person and be convenient for rotating the impeller adjustment snap angle, and the other hand is rotated limit support and makes limit support to resist one of the plane of snap and lock transmission shaft, avoid the impeller in and subsequent work process and rotate at random, compared with the subsequent dismounting and overhauling process continuously pay attention to the impeller, and this fan only needs to pay attention to the impeller when operating limit support before and after dismounting, more simple and convenient, can put more energy and physical force in the overhauling and dismounting process subsequently, or reduce the consumption of energy and physical force, and simple structure convenient operation.

Description

Technical Field

[0001] This utility model relates to the field of axial flow fan technology, specifically a low-noise axial flow fan. Background Technology

[0002] The most common types of fans on the market include axial fans, centrifugal fans, and Roots blowers. Among them, axial fans refer to the type of fan in which gas flows along the direction of the fan's rotation axis. They are characterized by large flow rate and simple structure, and are widely used in industrial building ventilation, agricultural building ventilation, residential building ventilation, commercial building ventilation, and electrical appliance heat dissipation.

[0003] When performing maintenance on existing axial flow fans, although power is usually cut off to ensure safety and prevent injury to workers, the impeller can still move freely. Whether the axial flow fan is disassembled for maintenance or not, the movement of the impeller can easily interfere with the workers' operations. For example, during disassembly and assembly, the impeller may rotate due to human intervention, requiring workers to expend extra effort to control it. During maintenance, external airflow or human intervention may cause the impeller to rotate and strike the worker's arm. While this may not sever the arm, there is a high possibility of cuts or injuries. The free rotation of the impeller significantly impacts the operation during maintenance and replacement. Utility Model Content

[0004] Therefore, the purpose of this utility model is to provide a low-noise axial flow fan to solve the technical problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a low-noise axial flow fan, comprising a housing and a drive shaft, wherein a bracket is connected inside the housing and a limit frame extends through the top of the bracket, and an operating sleeve and an anti-disengagement sleeve are respectively fitted outside the limit frame; a key bar is connected to the top of the drive shaft, and a retaining sleeve is fitted outside the drive shaft, with keyways on both sides of the retaining sleeve.

[0006] By adopting the above technical solution, during actual maintenance, workers only need to hold the impeller with one hand, avoiding injury from the impeller and facilitating the adjustment of the sleeve angle by rotating the impeller. The other hand uses a wrench to rotate the control sleeve. The shape of the contact surface between the control sleeve and the limit frame facilitates torque transmission, allowing the rotation of the control sleeve to drive the limit frame. Rotating the limit frame causes it to move upwards and abut against one of the planes of the sleeve, locking the drive shaft and preventing the impeller from rotating arbitrarily during subsequent operations. If the limit frame cannot abut against the plane, workers can manually rotate the impeller to adjust the sleeve angle. The T-shaped limit frame has a larger contact surface, acting like a flat washer, increasing the stability of the limit frame. When the limit frame moves upwards and abuts against the bottom plane of the sleeve, it reduces the possibility of the limit frame loosening due to vibration during maintenance. The sleeve is a regular octagon with more planes, facilitating the abutment between the limit frame and the sleeve planes for limiting and preventing rotation. Like the impeller, the sleeve transmits torque through keyways and keyways, which is convenient for disassembly and assembly, with a simple structure and mature technology, avoiding excessive cost increases. The ferrule is synchronized with the impeller, and the ferrule is stopped from rotating by limiting its position. Furthermore, all edges and corners of the ferrule are rounded, which smooths the airflow path, reduces airflow impact and turbulence, thereby reducing aerodynamic noise and vibration. It also facilitates balancing during the rounding process. The ferrule's center of gravity can be adjusted by grinding the chamfer; for example, heavier areas can be ground with increased grinding to create a larger radius, while lighter areas can be ground with reduced grinding to create a smaller radius. Drilling can also be used to reduce weight and adjust the ferrule's center of gravity, avoiding significant differences in grinding across multiple edges. The design optimizes aesthetics and airflow path, eliminating the need for additional counterweights and preventing vibrations caused by centrifugal force during sleeve rotation. After maintenance, the operator holds the impeller with one hand to prevent it from hitting them, while using the other hand to rotate the control sleeve in the opposite direction with a wrench. This causes the limit bracket to move down and press against the top of the support. During this process, the T-shaped limit bracket has a larger contact surface, acting like a flat washer to increase its stability. This releases the limit on the sleeve and thus the impeller. Afterward, the power can be connected to start the axial flow fan.

[0007] Furthermore, the limiting frame has a "T" shaped cross section, and the top of the limiting frame abuts against the sleeve, while the bottom two sides of the limiting frame abut against the bracket.

[0008] By adopting the above technical solution, the T-shaped limit bracket has a larger contact surface, which acts like a flat gasket, increasing the stability of the limit bracket. For example, when the limit bracket moves upward and abuts against the bottom plane of the sleeve, it reduces the possibility of the limit bracket loosening due to vibration during maintenance. And when the limit bracket moves downward and abuts against the top of the bracket, it reduces the possibility of the limit bracket loosening due to vibration during the operation of the fan.

[0009] Furthermore, threads are provided on both the upper and lower surfaces of the outer surface of the limiting frame, and the thread on the upper surface of the limiting frame is threadedly connected to the bracket, while the thread on the lower surface of the limiting frame is threadedly connected to the anti-disengagement thread.

[0010] By adopting the above technical solution, rotating the limit bracket causes it to move upward and abut against one of the planes of the ferrule to lock the drive shaft. After maintenance is completed, rotating the control sleeve in the opposite direction causes the limit bracket to move downward and abut against the top of the bracket, thereby ending the limitation on the ferrule and the impeller. When it is necessary to separate the limit bracket and the control sleeve, the anti-disengagement sleeve can be loosened and removed using an Allen wrench.

[0011] Furthermore, the cross-section of the middle section of the limiting frame is square, and square holes are provided at the top and bottom of the operating sleeve, which is adapted to the middle section of the limiting frame.

[0012] By adopting the above technical solution, the contact surface shape between the control sleeve and the limit frame is conducive to the transmission of torque, so that the rotation of the control sleeve can drive the limit frame to rotate, thereby making it easier and more convenient to tighten the limit frame.

[0013] Furthermore, the control sleeve has a hexagonal cross-section, and the bottom of the anti-detachment sleeve has a hexagonal hole.

[0014] By adopting the above technical solution, the control sleeve is designed to be easily rotated with a wrench, and the bottom of the anti-disengagement sleeve has a hexagonal groove. Therefore, when it is necessary to separate the limit bracket and the control sleeve, the anti-disengagement sleeve can be loosened and removed with an Allen wrench.

[0015] Furthermore, a motor is installed on the top of the bracket, and the drive shaft is connected to the output end of the motor. An impeller is sleeved on the outside of the drive shaft, and a reverse thread nut is connected to one side of the impeller through an anti-loosening washer. Mounting holes are provided on both sides of the outer casing.

[0016] By adopting the above technical solution, the motor drives the transmission shaft to rotate. The transmission shaft is connected to the ferrule and impeller via a key and keyway, thereby transmitting torque and causing the impeller to rotate to generate airflow. When the motor needs to be disassembled, it is connected to the bracket by bolts, which facilitates disassembly, maintenance, and replacement of the motor. When the impeller needs to be disassembled, the operator needs to remove the anti-loosening nut and anti-loosening washer in sequence. Then, the operator can remove the impeller axially for maintenance and replacement. During installation, the operator only needs to reinstall the impeller, anti-loosening washer, and anti-loosening nut in sequence. The anti-loosening nut is tightened in the direction of impeller rotation to prevent the torque generated by the impeller rotation from causing the anti-loosening nut to fall off and the impeller to fall off.

[0017] Furthermore, the motor is a variable frequency permanent magnet synchronous motor, and the impeller is an aluminum alloy axial flow fan impeller from Dezhou Zhongxiao Ventilation Equipment Co., Ltd.

[0018] By adopting the above technical solution, the impeller is an aluminum alloy axial flow fan impeller from Dezhou Zhongxiao Ventilation Equipment Co., Ltd., with a nominal noise level of dB, which is a low-noise impeller; and the motor is a variable frequency permanent magnet synchronous motor. Compared with asynchronous motors, permanent magnet synchronous motors reduce electromagnetic noise, and the rotor dynamic balance accuracy reaches G level, reducing vibration noise caused by rotational imbalance. With the addition of variable frequency control, the speed can be adjusted according to the load, avoiding the resonance speed range and reducing noise caused by speed fluctuations.

[0019] Furthermore, the ferrule is made of aluminum alloy, and the limit frame, operating sleeve, and anti-disengagement sleeve are made of 316L stainless steel or 2507 duplex stainless steel.

[0020] By adopting the above technical solutions, the ferrule is made of lightweight and high-strength aluminum alloy, and the same material as the impeller avoids electrochemical corrosion; the limit bracket, control sleeve and anti-disengagement sleeve are all made of stainless steel, which has high strength and avoids the corrosion and rust caused by moisture in the airflow. The difference between 316L stainless steel and 2507 duplex stainless steel is that 2507 duplex stainless steel has higher strength.

[0021] Furthermore, both the control sleeve and the anti-detachment sleeve have a "T"-shaped longitudinal section.

[0022] By adopting the above technical solution, the anti-slip sleeve is T-shaped, which acts like a flat gasket to prevent the anti-slip sleeve from loosening and falling off. The operating sleeve is also T-shaped, similar to a flat gasket. While the limit frame moves up and abuts against the bottom of the sleeve, the top of the operating sleeve can abut against the upper part of the bracket, increasing the stability of the limit frame.

[0023] In summary, the present invention has the following main advantages:

[0024] 1. This utility model, through the design of the clamp and the limiting bracket, allows for easy maintenance by holding the impeller with one hand, preventing injury and facilitating adjustment of the clamp angle. The other hand rotates the limiting bracket to lock the drive shaft against one of the planes of the clamp, preventing the impeller from rotating freely during subsequent operations. If the limiting bracket cannot reach the plane, the angle of the clamp can be adjusted by manually rotating the impeller. The clamp is a regular octagon with multiple planes to facilitate the limiting bracket and the plane of the clamp for limiting and preventing rotation. Compared to continuously monitoring the impeller during subsequent disassembly and maintenance, this fan only requires attention to the impeller when operating the limiting bracket before and after disassembly, making it simpler and more convenient. This allows more energy and effort to be focused on maintenance and disassembly, or to reduce the consumption of energy and effort. Furthermore, the structure is simple and the operation is convenient.

[0025] 2. This utility model, through the design of a ferrule, key bar, and keyway, allows the ferrule to transmit torque via the key bar and keyway, similar to an impeller. This facilitates assembly and disassembly, and the mature structure and technology avoid excessive cost increases. Furthermore, it allows for synchronization with the impeller; the ferrule's rotation is limited and stopped, effectively stopping the impeller's rotation. The ferrule's edges and corners are all rounded, smoothing the airflow path and reducing airflow impact and turbulence, thus lowering aerodynamic noise and vibration. It also facilitates balancing during the rounding process. The ferrule's center of gravity can be adjusted by grinding the chamfer; for example, heavier areas can be ground more to create a larger radius, while lighter areas can be ground less to create a smaller radius. Drilling can also be used to adjust the ferrule's center of gravity, preventing large differences in grinding across multiple edges that could affect aesthetics and airflow path. This eliminates the need for additional counterweights and prevents vibration caused by centrifugal force during ferrule rotation, improving the ferrule's performance.

[0026] 3. This utility model, through the design of a limiting frame, a control sleeve, and an anti-detachment sleeve, features a T-shaped limiting frame with a larger contact surface, acting like a flat washer and increasing its stability. When the limiting frame moves upward and abuts against the bottom plane of the retaining sleeve, it reduces the possibility of the limiting frame loosening due to vibration during maintenance. The control sleeve facilitates rotation with a wrench, and the shape of the contact surface between the control sleeve and the limiting frame facilitates torque transmission, allowing the rotation of the control sleeve to drive the limiting frame's rotation. This makes tightening the limiting frame easier and more convenient. The anti-detachment sleeve prevents the control sleeve from loosening and falling off. The anti-detachment sleeve has a circular cross-section with a diameter smaller than the length and width of the control sleeve, preventing the wrench from rotating it. A hexagonal groove is provided at the bottom of the anti-detachment sleeve, allowing it to be loosened and removed with an Allen wrench when the limiting frame and control sleeve need to be separated. This design improves stability and facilitates operation, disassembly, and replacement. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of this utility model;

[0028] Figure 2 This is a cross-sectional structural diagram of the present invention;

[0029] Figure 3 This is a side sectional view of the bracket structure of this utility model;

[0030] Figure 4 This is a schematic diagram of the exploded structure of the limiting frame of this utility model;

[0031] Figure 5 This is a schematic diagram of the exploded structure of the motor according to this utility model.

[0032] In the diagram: 1. Outer shell; 2. Mounting hole; 3. Bracket; 4. Motor; 5. Drive shaft; 6. Key bar; 7. Impeller; 8. Anti-loosening washer; 9. Reverse thread nut; 10. Compression sleeve; 11. Keyway; 12. Limiting bracket; 13. Control sleeve; 14. Anti-disengagement sleeve. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0034] The embodiments of this utility model will be described below based on its overall structure.

[0035] Example 1:

[0036] A low-noise axial flow fan, such as Figures 1-5As shown, the device includes a housing 1 and a drive shaft 5. A bracket 3 is connected inside the housing 1, with a limit frame 12 extending through its top. The limit frame 12 has a "T"-shaped cross-section. The bottom sides of the limit frame 12 abut against the bracket 3. Threads are provided on both the top and bottom of the outer surface of the limit frame 12. The thread on the top of the limit frame 12 is threaded to the bracket 3. An operating sleeve 13 and an anti-detachment sleeve 14 are respectively fitted onto the outside of the limit frame 12. The thread on the bottom of the limit frame 12 is threaded to the anti-detachment sleeve 14. A hexagonal hole is provided at the bottom of the anti-detachment sleeve 14. The cross-section of the middle section of the limit frame 12 is square. Square holes are provided at the top and bottom of the operating sleeve 13. The operating sleeve 13 is adapted to the middle section of the limit frame 12 for operation. The sleeve 13 has a hexagonal cross-section; a key 6 is connected to the top of the drive shaft 5, and a retaining sleeve 10 is sleeved on the outside of the drive shaft 5. The top of the limiting frame 12 abuts against the retaining sleeve 10. Keyways 11 are provided on both sides of the retaining sleeve 10. In actual maintenance, the operator only needs to hold the impeller 7 with one hand to avoid the impeller 7 hitting the operator and to facilitate the rotation of the impeller 7 to adjust the angle of the retaining sleeve 10, while the operator's other hand rotates the operating sleeve 13 with a wrench. The shape of the contact surface between the operating sleeve 13 and the limiting frame 12 facilitates the transmission of torque, so that the rotation of the operating sleeve 13 can drive the limiting frame 12 to rotate. Rotating the limiting frame 12 causes the limiting frame 12 to abut against one of the planes of the retaining sleeve 10 and lock it against the drive shaft 5, preventing the impeller 7 from hitting the operator. During operation, the device can rotate freely. If the limit bracket 12 cannot abut against the plane, the operator can manually adjust the angle of the sleeve 10 by rotating the impeller 7. During this process, the T-shaped limit bracket 12 has a larger contact surface, acting like a flat washer and increasing the stability of the limit bracket 12. When the limit bracket 12 moves upward and abuts against the bottom plane of the sleeve 10, it reduces the possibility of the limit bracket 12 becoming loose due to vibration during maintenance. The sleeve 10 is a regular octagon with more flat surfaces to facilitate the abutment between the limit bracket 12 and the plane of the sleeve 10 for limiting and preventing rotation. Like the impeller 7, the sleeve 10 transmits torque through the key 6 and keyway 11. This facilitates disassembly and assembly, has a simple structure and mature technology to avoid excessive cost increases, and also allows for... The sleeve 10 is synchronized with the impeller 7, and the sleeve 10 is limited to stop the impeller 7 from rotating. The corners of the sleeve 10 are all rounded, i.e., rounded corners. The rounded transition can smooth the airflow path, reduce airflow impact and turbulence, thereby reducing aerodynamic noise and vibration. It also facilitates balancing during the rounding process. The center of gravity of the sleeve 10 can be adjusted by grinding the chamfer. For example, the grinding amount can be increased in the heavier area to form a larger rounded corner, and the grinding amount can be reduced in the lighter area to form a smaller rounded corner. The center of gravity of the sleeve 10 can also be adjusted by drilling to remove weight, so as to avoid large differences in grinding on multiple sides, which would affect the aesthetics and airflow path. Therefore, there is no need for additional fixed counterweights, and the phenomenon of vibration caused by centrifugal force when the sleeve 10 rotates is avoided.After maintenance, the worker holds the impeller 7 with one hand to prevent it from hitting them, while using the other hand to reverse the control sleeve 13 with a wrench. This causes the limit bracket 12 to move downwards and abut against the top of the bracket 3. During this process, the T-shaped limit bracket 12 has a larger contact surface, acting like a flat washer to increase its stability. This releases the limit on the clamping sleeve 10, thus releasing the limit on the impeller 7. Power can then be connected to start the axial flow fan.

[0037] See Figure 1 , Figure 2 , Figure 3 and Figure 5 In the above embodiment, a motor 4 is installed on the top of the bracket 3. The motor 4 is a variable frequency permanent magnet synchronous motor. The drive shaft 5 is connected to the output end of the motor 4. An impeller 7 is sleeved on the outside of the drive shaft 5. The impeller 7 is an aluminum alloy axial flow fan impeller from Dezhou Zhongxiao Ventilation Equipment Co., Ltd. That is, the motor 4 drives the drive shaft 5 to rotate. The drive shaft 5 is keyed to the sleeve 10 and the impeller 7 through the key bar 6 and the keyway 11, thereby transmitting torque and causing the impeller 7 to rotate to generate airflow. A reverse thread nut 9 is connected to one side of the impeller 7 through an anti-loosening washer 8. When it is necessary to disassemble and assemble the motor 4, the motor 4 and the bracket 3 are connected by bolts. This facilitates the disassembly, repair, and replacement of motor 4. When it is necessary to disassemble and install impeller 7, the operator needs to remove the reverse thread nut 9 and anti-loosening washer 8 in sequence. Then, the operator can remove impeller 7 axially for repair and replacement. During installation, the operator only needs to reinstall impeller 7, anti-loosening washer 8, and reverse thread nut 9 in sequence. The direction of rotation of reverse thread nut 9 is the same as the direction of tightening reverse thread nut 9, to avoid the torque generated by the rotation of impeller 7 causing reverse thread nut 9 to fall off and thus causing impeller 7 to fall off. Mounting holes 2 are provided on both sides of the outer casing 1. The outer casing 1 is connected to the pipeline through the mounting holes 2 and bolts.

[0038] Example 2:

[0039] Based on the above embodiment one, the following settings are now implemented to increase service life and strength.

[0040] See Figures 2-5 In the above embodiments, the ferrule 10 is made of aluminum alloy, which is lightweight and strong, and is made of the same material as the impeller 7 to avoid electrochemical corrosion; the limit frame 12, the operating sleeve 13 and the anti-detachment sleeve 14 are made of 316L stainless steel or 2507 duplex stainless steel. The limit frame 12, the operating sleeve 13 and the anti-detachment sleeve 14 are all made of stainless steel, which is strong and prevents the airflow from being mixed with moisture, which would cause the three to corrode and rust. The difference between 316L stainless steel and 2507 duplex stainless steel is that 2507 duplex stainless steel has higher strength.

[0041] Example 3:

[0042] Based on the above embodiment one, the following settings are now implemented to further enhance stability.

[0043] See Figures 2-4 In the above embodiment, both the control sleeve 13 and the anti-detachment sleeve 14 have a "T" shape in their longitudinal sections. The anti-detachment sleeve 14 is T-shaped, which acts like a flat gasket to prevent the anti-detachment sleeve 14 from loosening and falling off. The control sleeve 13 is also T-shaped, similar to a flat gasket. While the limit frame 12 moves up and abuts against the bottom of the sleeve 10, the top of the control sleeve 13 can abut against the upper part of the bracket 3, increasing the stability of the limit frame 12.

[0044] The implementation principle of this utility model is as follows: First, the outer shell 1 is connected to the pipeline through the mounting hole 2 and bolts, or a resistive silencer is installed at the inlet to absorb mid-to-high frequency noise through porous materials, or a reactive silencer is installed at the outlet to attenuate low frequency noise through the expansion chamber structure, or a combination thereof; and the outer shell 1 can be connected to the pipeline or silencer through a flexible joint to avoid vibration transmission caused by rigid connection; and spring shock absorbers or rubber shock absorber pads can be symmetrically installed at the bottom of the outer shell 1 to isolate the transmission of vibration to the foundation structure; and the outer shell 1 adopts a double-layer sandwich structure, namely an outer steel plate, a middle sound insulation cotton (such as rock wool, aluminum foam), and an inner sound-absorbing layer. The fan features a perforated sound-absorbing plate; the impeller 7 is an aluminum alloy axial flow fan impeller from Dezhou Zhongxiao Ventilation Equipment Co., Ltd., with a nominal noise level of 31dB, classifying it as a low-noise impeller; and the motor 4 is a variable frequency permanent magnet synchronous motor. Compared to asynchronous motors, permanent magnet synchronous motors reduce electromagnetic noise, and the rotor dynamic balance accuracy reaches G1.0 level, reducing vibration noise caused by rotational imbalance. Furthermore, with variable frequency control, the speed can be adjusted according to the load, avoiding the resonance speed range and reducing noise caused by speed fluctuations. Through the above existing technical means, the overall noise of this axial flow fan can be reduced, decreasing the noise generated and emitted to the outside during operation.

[0045] In actual operation, the working principle of the axial flow fan is relatively simple: the motor 4 drives the transmission shaft 5 to rotate. The transmission shaft 5 is connected to the sleeve 10 and the impeller 7 through the key bar 6 and keyway 11, thereby transmitting torque and causing the impeller 7 to rotate to generate airflow. When it is necessary to disassemble the motor 4, the motor 4 is connected to the bracket 3 by bolts, which facilitates the disassembly, maintenance and replacement of the motor 4. When it is necessary to disassemble the impeller 7, the operator needs to remove the reverse thread nut 9 and the anti-loosening washer 8 in sequence. Then the operator can remove the impeller 7 axially for maintenance and replacement. During installation, the operator only needs to put the impeller 7, anti-loosening washer 8 and reverse thread nut 9 back in sequence. The direction of rotation of the reverse thread nut 9 is the same as the direction of tightening the reverse thread nut 9, so as to avoid the torque generated by the rotation of the impeller 7 causing the reverse thread nut 9 to fall off and the impeller 7 to fall off.

[0046] In actual maintenance, workers only need to hold the impeller 7 with one hand to prevent injury and facilitate rotation to adjust the angle of the ferrule 10. The other hand uses a wrench to rotate the control sleeve 13. The shape of the contact surface between the control sleeve 13 and the limit frame 12 facilitates torque transmission, allowing the rotation of the control sleeve 13 to drive the limit frame 12. Rotating the limit frame 12 causes it to move upwards and abut against one of the planes of the ferrule 10, locking the drive shaft 5 and preventing the impeller 7 from rotating arbitrarily during subsequent operations. If the limit frame 12 cannot abut against the plane, workers can manually rotate the impeller 7 to adjust the angle of the ferrule 10. The T-shaped limit frame 12 has a larger contact surface, acting like a flat washer, increasing its stability. When the limit frame 12 moves upwards and abuts against the bottom plane of the ferrule 10, it reduces the possibility of vibration causing the limit frame 12 to loosen during maintenance. The ferrule 10 is a regular octagon with a flat surface. Furthermore, the limiting bracket 12 and the ferrule 10 abut against each other to limit rotation; and the ferrule 10, like the impeller 7, transmits torque through the key 6 and keyway 11. This facilitates disassembly and assembly, with a simple structure and mature technology to avoid excessive cost increases. It also allows for synchronization with the impeller 7, where the ferrule 10 being limited and preventing rotation means the impeller 7 is also limited and prevented from rotating. Moreover, the corners of the ferrule 10 are all rounded, i.e., rounded corners. The rounded transition can smooth the airflow path, reduce airflow impact and turbulence, thereby reducing aerodynamic noise and vibration, and facilitate balancing during the rounding process. The center of gravity of the ferrule 10 can be adjusted by grinding the chamfer. For example, the grinding amount can be increased in heavier areas to form a larger rounded corner, and the grinding amount can be reduced in lighter areas to form a smaller rounded corner. The center of gravity of the ferrule 10 can also be adjusted by drilling to remove weight, avoiding large differences in grinding on multiple sides that affect aesthetics and airflow path. This eliminates the need for additional fixed counterweights and prevents vibration caused by centrifugal force when the ferrule 10 rotates.

[0047] After maintenance, the worker holds the impeller 7 with one hand to prevent it from hitting them, while using the other hand to reverse the control sleeve 13 with a wrench. This causes the limit bracket 12 to move down and abut against the top of the bracket 3. During this process, the T-shaped limit bracket 12 has a larger contact surface, acting like a flat washer to increase its stability. This releases the limit on the clamping sleeve 10, thus releasing the limit on the impeller 7. Power can then be connected to start the axial flow fan. The limit bracket 12, control sleeve 13, and anti-detachment sleeve 14 are all made of stainless steel, which is high-strength and prevents moisture in the airflow from causing damage to these three components. Corrosion and rust; the anti-loosening sleeve 14 is also T-shaped, which also serves as a flat gasket to prevent the anti-loosening sleeve 14 from loosening and falling off. The operating sleeve 13 is also T-shaped, similar to a flat gasket. While the limit frame 12 moves up and abuts against the bottom of the sleeve 10, the top of the operating sleeve 13 can abut against the upper part of the inside of the bracket 3, increasing the stability of the limit frame 12. Of course, other gaskets with better anti-loosening effect, such as spring gaskets and toothed locking gaskets, can be set on the contact surface between the bottom of the limit frame 12 and the bracket 3, the top of the operating sleeve 13 and the top of the anti-loosening sleeve 14, to achieve a better anti-loosening effect when used together.

[0048] Although embodiments of the present invention have been shown and described, these specific embodiments are merely explanations of the present invention and are not intended to limit the invention. The specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. After reading this specification, those skilled in the art may make modifications, substitutions, and variations to the embodiments as needed without departing from the principles and spirit of the present invention, provided that such modifications, substitutions, and variations are within the scope of the claims of the present invention and are protected by patent law.

Claims

1. A low-noise axial flow fan, comprising a housing (1) and a drive shaft (5), characterized in that: The outer shell (1) is connected to the bracket (3) inside, and the top of the bracket (12) is connected to the limit frame (12). The limit frame (12) is fitted with the operating sleeve (13) and the anti-detachment sleeve (14) respectively. The top of the drive shaft (5) is connected to the key bar (6), and the drive shaft (5) is fitted with the sleeve (10). The sleeve (10) has key grooves (11) on both sides.

2. The low-noise axial flow fan according to claim 1, characterized in that: The limiting frame (12) has a "T" shaped cross section, and the top of the limiting frame (12) abuts against the sleeve (10), while the bottom sides of the limiting frame (12) abut against the bracket (3).

3. The low-noise axial flow fan according to claim 2, characterized in that: The upper and lower surfaces of the outer surface of the limiting frame (12) are both provided with threads, and the thread on the upper surface of the limiting frame (12) is threadedly connected to the bracket (3), and the thread on the lower surface of the limiting frame (12) is threadedly connected to the anti-detachment sleeve (14).

4. The low-noise axial flow fan according to claim 3, characterized in that: The cross-section of the middle section of the limiting frame (12) is square, and the top and bottom of the operating sleeve (13) are provided with square holes. The operating sleeve (13) is adapted to the middle section of the limiting frame (12).

5. The low-noise axial flow fan according to claim 3, characterized in that: The operating sleeve (13) has a hexagonal cross-section, and the bottom of the anti-detachment sleeve (14) has a hexagonal hole.

6. The low-noise axial flow fan according to claim 1, characterized in that: The bracket (3) is equipped with a motor (4) on top, and the drive shaft (5) is connected to the output end of the motor (4). An impeller (7) is sleeved on the outside of the drive shaft (5), and a reverse thread nut (9) is connected to one side of the impeller (7) through an anti-loosening washer (8). Mounting holes (2) are provided on both sides of the outer shell (1).

7. The low-noise axial flow fan according to claim 6, characterized in that: The motor (4) is a variable frequency permanent magnet synchronous motor, and the impeller (7) is an aluminum alloy axial flow fan impeller from Dezhou Zhongxiao Ventilation Equipment Co., Ltd.

8. The low-noise axial flow fan according to claim 3, characterized in that: The sleeve (10) is made of aluminum alloy, and the limit frame (12), operating sleeve (13) and anti-detachment sleeve (14) are made of 316L stainless steel or 2507 duplex stainless steel.

9. The low-noise axial flow fan according to claim 8, characterized in that: The longitudinal section of both the control sleeve (13) and the anti-detachment sleeve (14) is T-shaped.

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