A centrifugal fan having a three-dimensional flow impeller and a method of using the same

Abstract

This invention discloses a centrifugal fan with a three-dimensional flow impeller and its usage method. The device includes a fan casing and a three-dimensional flow impeller body rotatably disposed inside it. A variable airflow guide is provided in the fan casing. When the wind speed is increased to above a preset wind speed, the shape memory metal plate is tightly attached to the inner wall of the volute guide plate and is attracted and fixed by a first strong magnet. At this time, the curvature of the flow channel inside the entire fan casing is at its maximum design range. The strong airflow smoothly and slowly transitions along the inner wall of the shape memory metal plate to the air outlet for discharge, effectively avoiding eddies and airflow howling. When the wind speed is reduced to below the preset wind speed, the entire shape memory metal plate deforms inward, thereby forming a guide channel with a larger curvature between the volute guide plate and the shape memory metal plate. This allows the low-speed airflow to pass through the guide quickly and be discharged from the air outlet, thus making the exhaust air more concentrated and avoiding the formation of backflow turbulence at the air outlet.

Description

Technical Field

[0001] This invention relates to the field of airflow elements, and in particular to a centrifugal fan with a three-dimensional impeller and its method of use. Background Technology

[0002] Traditional centrifugal fan impellers are designed using binary technology theory. However, with the development of technology and the increasing demand for efficiency, the traditional binary design theory of centrifugal fans has obvious limitations and shortcomings in terms of design accuracy, efficiency improvement, adaptability, maintenance convenience, and noise control.

[0003] Centrifugal fan impellers face various losses during operation, which significantly impact fan efficiency and noise levels, and may also lead to equipment wear and malfunctions. This is particularly true for the centrifugal fan's volute structure, which typically employs fluid dynamics control to manage the volute curvature design. This ensures that, at the expected wind speed, the corresponding volute curvature guarantees effective airflow into the outlet, preventing turbulence and vortices, and ensuring concentrated airflow. However, in practical applications, most centrifugal fans now use variable frequency motors for energy-saving design, outputting different power levels under different operating conditions. This creates a mismatch between volute curvature and wind speed variations. Therefore, this paper presents a centrifugal fan with a three-dimensional flow impeller and its application method. Summary of the Invention

[0004] The purpose of this invention is to provide a centrifugal fan with a three-dimensional impeller and its method of use, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a centrifugal fan with a three-dimensional flow impeller, comprising;

[0006] The fan casing has a volute shape whose curvature is controlled by an exponential curve spiral equation. The fan casing has an air outlet at its end, and a baffle plate is provided in the fan casing near the air outlet to suppress the generation of outflow vortices.

[0007] The three-dimensional flow impeller body is rotatably mounted in the fan casing. The three-dimensional flow impeller body has multiple blades arranged in a ring array. The shape of the blades is designed by parameters using multiple control curves and control equations.

[0008] A variable air outlet guide is fixedly welded to the inner wall of the fan casing at its top end and extends toward the air outlet at its bottom end. The bottom end of the variable air outlet guide moves toward the inner wall of the fan casing, thereby causing the variable air outlet guide to bend and deform, thereby adjusting the curvature of the air outlet of the fan casing to a preset value.

[0009] Preferably, the variable airflow guide includes a shape memory metal plate and connecting portions fixedly welded to both sides of the bottom end of the shape memory metal plate. The guide baffle is fixedly welded to the shape memory metal plate, and the outer surface of the guide baffle is provided with multiple shearing openings for relieving bending stress. The fan volute, including a volute-shaped air guide plate and sealing cover plates fixedly welded to both sides of the volute-shaped air guide plate, is fixedly welded to the top of the shape memory metal plate on the inner wall of the volute-shaped air guide plate. The connecting portions are slidably disposed on the inner side wall of the sealing cover plate.

[0010] Preferably, the two sides of the memory metal plate are folded inward to form a sealing edge, the sealing edge is attached to the inner wall of the sealing cover, and the outer surface of the sealing edge is formed with a sealing and noise reduction layer by a rubber coating process. A self-resetting component is fixedly welded to the bottom outer wall of the sealing cover, and the connecting part is pulled and reset by the self-resetting component.

[0011] Preferably, the self-resetting component includes a sealing chamber fixedly welded to the outer wall of the sealing cover plate, the sealing chamber and the sealing cover plate having an inclined groove, a connecting shaft rotatably disposed on the connecting part, the connecting shaft being slidably disposed in the inclined groove, a connecting seat fixedly welded to the inner wall of the sealing chamber, and a traction spring fixedly installed between the connecting seat and the connecting shaft, the traction spring being used to pull the connecting shaft to slide downward along the inclined groove.

[0012] Preferably, a second strong magnetic component is fixedly disposed on the inner wall of the sealed chamber, and a first strong magnetic component is fixedly welded to the bottom inner wall of the volute air guide plate. The connecting part and the bottom of the memory metal plate are both magnetized so that the second strong magnetic component is magnetically attracted and fixed to the connecting part, and the first strong magnetic component is magnetically attracted and fixed to the bottom of the memory metal plate.

[0013] Preferably, one set of the sealing cover plates has an air inlet, and an air inlet cover is fixedly welded to the outside of the air inlet. A variable frequency motor is fixedly installed on another set of the sealing cover plates. One side of the three-dimensional flow impeller body is fixedly connected to the output end of the variable frequency motor, and the other side of the three-dimensional flow impeller body faces the air inlet cover.

[0014] Preferably, the air inlet shroud includes an air inlet flare and an inner air guide portion integrally formed at the constricted end of the air inlet flare. The inner end of the inner air guide portion is outwardly expanding, and the end of the inner air guide portion is integrally formed with an outwardly folded lip. An assembly flange ring is fixedly welded to the outer wall of the inner air guide portion. The assembly flange ring is fixedly installed on the outer wall of the air inlet, and a reinforcing rib is fixedly welded between the assembly flange ring and the air inlet flare.

[0015] Preferably, the three-dimensional impeller body includes a rear plate radial acceleration guide and a front plate. The blades are fixedly welded between the rear plate radial acceleration guide and the front plate. The output shaft of the variable frequency motor is coaxially fixed with the rear plate radial acceleration guide. The front plate has an integrally formed inner folded lip that adapts to the outer folded lip, and the assembly gap between the outer folded lip and the inner folded lip is mm.

[0016] Preferably, a bearing is installed between the rear plate radial acceleration guide fluid and a set of the sealing cover plates. The outer side of the bearing is provided with guide vanes in an annular shape. The guide vanes are fixedly welded to the sealing cover plates so that the airflow flows along the volute guide plate towards the air outlet.

[0017] A method of using a centrifugal fan with a three-dimensional impeller includes:

[0018] S1. Design the output power thresholds Pmax and Pmin of the variable frequency motor. Then, based on the thrust Fb generated by the airflow at the air outlet on the memory metal plate under different working conditions of Pmax and Pmin, design the magnetic strength of the first and second strong magnetic components and the tension Fa of the traction spring.

[0019] S2. When the output power of the variable frequency motor is greater than Pmax, it is the "strong wind mode". At this time, the airflow thrust Fb can overcome the tension Fa of the traction spring and the magnetic force of the second strong magnet and the connecting part, so that the memory metal plate is tightly attached to the side wall of the volute air guide plate. At this time, the overall air outlet has a "small curvature" and a smooth transition, avoiding airflow vortex.

[0020] S3. When the output power of the variable frequency motor is less than Pmin, it is in "weak wind mode". At this time, the tension Fa of the traction spring is greater than the sum of the airflow thrust Fb and the magnetic attraction of the first strong magnet and the memory metal plate, causing the memory metal plate to bend and deform inward. At this time, the overall air outlet turns quickly with "large curvature", making the airflow more concentrated.

[0021] S4. When the output power of the variable frequency motor is between Pmin and Pmax, the memory metal plate maintains its current state.

[0022] The technical effects and advantages of this invention are as follows:

[0023] 1. This centrifugal fan with a three-dimensional impeller, by installing a variable airflow guide on the inner wall of the fan casing, when the wind speed increases to above the preset wind speed, the shape memory metal plate is tightly attached to the inner wall of the volute guide plate and is attracted and fixed by the first strong magnetic component. At this time, the curvature of the flow channel inside the entire fan casing is at its maximum design range, and the strong airflow smoothly and slowly transitions along the inner wall of the shape memory metal plate to the air outlet for discharge, effectively avoiding eddies and airflow howling. When the wind speed decreases to below the preset wind speed, the entire shape memory metal plate deforms inward, thereby forming a guide channel with a larger curvature between the volute guide plate and the shape memory metal plate, allowing the low-speed airflow to pass through the guide quickly and be discharged from the air outlet, thus making the exhaust air more concentrated and avoiding the formation of backflow turbulence at the air outlet.

[0024] 2. This centrifugal fan with a three-dimensional impeller has a sealing fold that moves tightly against the inner wall of the sealing cover plate. The outer surface of the sealing fold is formed with a sealing and noise reduction layer through a rubber coating process. This prevents air leakage at low wind speeds and avoids friction and noise generation when the shape memory metal plate moves.

[0025] 3. The method of using the centrifugal fan with a three-dimensional impeller is based on the preset wind speed variation to design the magnetic strength of the first and second strong magnets and the tension Fa of the traction spring. This ensures that at high wind speeds, the shape memory metal plate can adhere tightly to the inner wall of the volute guide plate to form an effective fit; at low wind speeds, the shape memory metal plate can deform to a preset state under the traction of the traction spring and be fixed by magnetic attraction, avoiding vibration of the shape memory metal plate caused by small wind speed changes. Attached Figure Description

[0026] Figure 1 This is a frontal view of the entire invention;

[0027] Figure 2 This is a schematic diagram of the overall rear side of the invention;

[0028] Figure 3 This is a side view of the entire invention;

[0029] Figure 4 This is an exploded view of the outer surface structure of the fan casing of the present invention;

[0030] Figure 5 This is a schematic diagram of the main body of the fan casing and the three-dimensional flow impeller of the present invention;

[0031] Figure 6 This is a schematic diagram showing the state of the variable airflow guide inside the fan casing of the present invention during the "strong wind mode";

[0032] Figure 7 This is a schematic diagram of the variable airflow guide inside the fan casing of the present invention during the "weak wind mode";

[0033] Figure 8 This is a cross-sectional view of the inner wall structure of the fan casing of the present invention;

[0034] Figure 9 This is a schematic diagram of the outer surface of the variable airflow guide of the present invention;

[0035] Figure 10 This is a schematic diagram of the internal structure of the variable airflow guide and self-resetting component of the present invention;

[0036] Figure 11 This is a schematic diagram of the internal structure of the three-dimensional flow impeller body of the present invention;

[0037] Figure 12 This is a cross-sectional view of the internal structure of the air inlet shroud of the present invention.

[0038] In the diagram: 1. Fan casing; 11. Sealing cover; 12. Volute guide vane; 13. Air outlet; 14. Bearing; 15. Guide vane; 16. Air inlet; 2. Three-dimensional impeller body; 21. Rear plate radial acceleration guide; 22. Front plate; 23. Blade; 24. Inner angle lip; 3. Air inlet shroud; 31. Air inlet flare; 32. Assembly flange ring; 33. Inner air guide; 34. Outer angle lip; 35. Reinforcing rib; 4. Variable frequency motor; 5. Variable air outlet guide; 51. Memory metal plate; 52. Guide baffle; 53. Connecting part; 54. Connecting shaft; 55. Shearing opening; 56. Sealing fold; 57. First strong magnet; 6. Self-resetting component; 62. Inclined groove; 63. Second strong magnet; 64. Traction spring; 65. Connecting seat. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] This invention provides, for example Figures 1 to 12 The centrifugal fan shown includes a three-dimensional flow impeller, comprising a fan casing 1. The volute curvature of the volute is generated using an exponential spiral equation, which better conforms to the actual flow profile and meets diffusion requirements. An outlet 13 is located at the end of the fan casing 1, and a baffle 52 is provided at the end of the fan casing 1 near the outlet 13 to suppress the generation of outflow vortices, thereby reducing noise and flow losses. Its volute curve control equation is:

[0041] Rφ=417.92e0.1364345φ;

[0042] Where φ: 0.994~6.28; unit is radians;

[0043] The three-dimensional flow impeller body 2 is rotatably mounted in the fan casing 1. The three-dimensional flow impeller body 2 has multiple blades 23 arranged in a ring array. The shape of the blades 23 is designed by parameters based on multiple control curves and control equations. There are 13 blades 23. The spatial profile is generated by fitting multiple control curves. The overall production and processing adopts a 4-axis precision machining fixture and red pressing method for one-piece molding. The three-coordinate inspection accuracy is less than 0.4mm.

[0044] The blade profile and governing equations are as follows:

[0045] Curve 1: X = 0 ~ 144.7

[0046] Curve 2: X = 0 ~ 133.2

[0047] Curve 3: X = 0 ~ 125.6

[0048] Curve 4: X = 0 ~ 125.6

[0049] Curve 5: X = 0 ~ 126.9

[0050] Y = a + bX1 + cX2 + dX3 + eX4 + fX5

[0051] Z=a+bX+cY+dX2+eY2+fX3+gY3+hXY+iX2Y+jXY2

[0052]

[0053]

[0054] The variable air outlet guide 5 has its top end fixedly welded to the inner wall of the fan volute 1, and its bottom end extends toward the air outlet 13. The bottom end of the variable air outlet guide 5 moves toward the inner wall of the fan volute 1, thereby pulling the variable air outlet guide 5 to bend and deform, thereby adjusting the curvature of the air outlet of the fan volute 1 to a preset value.

[0055] The variable airflow guide 5 includes a shape memory metal plate 51 and connecting parts 53 fixedly welded to both sides of the bottom end of the shape memory metal plate 51. A flow guide baffle 52 is fixedly welded to the shape memory metal plate 51, and the outer surface of the flow guide baffle 52 is provided with multiple shearing openings 55 for relieving bending stress. A fan volute 1 including a volute-shaped air guide plate 12 and sealing cover plates 11 fixedly welded to both sides of the volute-shaped air guide plate 12 are fixedly welded to the middle of the shape memory metal plate 51. The top end of the shape memory metal plate 51 is fixedly welded to the inner wall of the volute-shaped air guide plate 12. The connecting parts 53 are slidably disposed on the inner side wall of the sealing cover plate 11.

[0056] The two sides of the memory metal plate 51 are folded inward to form a sealing edge 56. The sealing edge 56 is attached to the inner wall of the sealing cover plate 11, and the outer surface of the sealing edge 56 is formed with a sealing and noise reduction layer by a rubber coating process. A self-resetting component 6 is fixedly welded to the bottom outer wall of the sealing cover plate 11, and the connecting part 53 is pulled and reset by the self-resetting component 6.

[0057] The self-resetting component 6 includes a sealing chamber fixedly welded to the outer wall of the sealing cover plate 11. An inclined groove 62 is provided on the sealing chamber and the sealing cover plate 11. A connecting shaft 54 ​​is rotatably provided on the connecting part 53. The connecting shaft 54 ​​is slidably provided in the inclined groove 62. A connecting seat 65 is fixedly welded to the inner wall of the sealing chamber. A traction spring 64 is fixedly installed between the connecting seat 65 and the connecting shaft 54. The traction spring 64 is used to pull the connecting shaft 54 ​​to slide downward along the inclined groove 62.

[0058] A second strong magnet 63 is fixedly installed on the inner wall of the sealed chamber, and a first strong magnet 57 is fixedly welded to the inner wall of the bottom end of the volute air guide plate 12. The bottom of the connecting part 53 and the memory metal plate 51 are both magnetized so that the second strong magnet 63 is magnetically attracted to the connecting part 53 and the first strong magnet 57 is magnetically attracted to the bottom of the memory metal plate 51.

[0059] An air inlet 16 is provided on a set of sealing cover plates 11. An air inlet cover 3 is fixedly welded to the outside of the air inlet 16. A variable frequency motor 4 is fixedly installed on another set of sealing cover plates 11. One side of the three-dimensional flow impeller body 2 is fixedly connected to the output end of the variable frequency motor 4, and the other side of the three-dimensional flow impeller body 2 faces the air inlet cover 3.

[0060] The air inlet shroud 3 includes an air inlet flare 31 and an inner air guide 33 integrally formed on the constricted end of the air inlet flare 31. The inner end of the inner air guide 33 is outwardly expanding. The end of the inner air guide 33 is integrally formed with an outwardly folded lip 34. An assembly flange ring 32 is fixedly welded to the outer wall of the inner air guide 33. The assembly flange ring 32 is fixedly installed on the outer wall of the air inlet 16. A reinforcing rib 35 is fixedly welded between the assembly flange ring 32 and the air inlet flare 31.

[0061] The three-dimensional impeller body 2 includes a rear plate radial acceleration guide 21 and a front plate 22. The rear plate radial acceleration guide 21 is integrally forged and precision machined on an integrated lathe to ensure dimensional accuracy. The impeller front plate is formed by combining a conical surface with an arc surface, with a cone angle of 10°. The blades 23 are fixedly welded between the rear plate radial acceleration guide 21 and the front plate 22. The output shaft of the variable frequency motor 4 is coaxially fixed with the rear plate radial acceleration guide 21. The front plate 22 has an integrally formed inner folded lip 24 that matches the outer folded lip 34, and the assembly gap between the outer folded lip 34 and the inner folded lip 24 is 3mm.

[0062] A bearing 14 is installed between the rear plate radial acceleration guide fluid 21 and a set of sealing cover plates 11. A guide vane 15 is arranged in a ring on the outer side of the bearing 14. The guide vane 15 is fixedly welded to the sealing cover plate 11 so that the airflow flows along the volute guide plate 12 towards the air outlet 13.

[0063] Working Principle: This centrifugal fan with a three-dimensional flow impeller generates its centrifugal fan by controlling the volute curvature of the fan casing 1 using an exponential spiral equation. A baffle 52 is installed near the outlet 13 of the fan casing 1 to suppress the generation of outflow vortices. The three-dimensional flow impeller body 2 contains multiple blades 23 arranged in a ring array. The shape of each blade 23 is designed using multiple control curves and control equations. There are 13 blades in total, and their spatial profile is generated by fitting multiple control curves. The entire fan is manufactured using a 4-axis precision machining fixture with a hot-pressing process, achieving a three-coordinate measurement accuracy of less than 0.4mm. After extensive simulation calculations, the final technical solution was determined. This three-dimensional flow impeller body 2 is suitable for medium and high-speed applications. High-speed operation significantly reduces separation losses within the impeller flow channel; the inlet angle of attack gradually increases from the rear plate to the intermediate front, and the separation formed by the impact of the blade leading edge is symmetrical and uniform, reducing impact losses and preventing the secondary flow from fully forming. At the same time, the separation of the non-working blades 23 is also suppressed to a certain extent. The overall impeller efficiency is 2-3 percentage points higher than that of products with a two-dimensional design. The product has been simulated by CFD, and the highest efficiency exceeds 89%, which is better than the 86% requirement of the national first-level energy efficiency standard GB19761-2020. Meanwhile, the prototype product has an impeller diameter of 1200 mm and an experimental speed of 1492 rpm. The experimental efficiency reaches 90% at its highest point, which is better than the 87% requirement of the national first-level energy efficiency standard GB19761-2020.

[0064] Furthermore, this centrifugal fan with a three-dimensional impeller, by installing a variable airflow guide 5 on the inner wall of the fan casing 1, when the wind speed is increased to above the preset wind speed, the tangential thrust of the airflow acting on the shape memory metal plate 51 at the air outlet 13 is greater than the tension Fa of the traction spring 64 and the magnetic force of the second strong magnet 63 and the connecting part 53, thereby causing the connecting shaft 54 ​​to slide upward along the inclined groove 62, and finally causing the shape memory metal plate 51 to be tightly attached to the inner wall of the volute guide plate 12, so that the bottom end of the shape memory metal plate 51 is attracted and fixed to the first strong magnet 57. At this time, the curvature of the flow channel inside the entire fan casing 1 is at the maximum design range. At this time, the strong airflow smoothly and slowly transitions along the inner wall of the shape memory metal plate 51 to the air outlet 13 for discharge, effectively avoiding the occurrence of eddies and airflow whistling.

[0065] When the wind speed drops below the preset wind speed, the tension Fa of the traction spring 64 is greater than the sum of the airflow thrust and the magnetic attraction of the first strong magnet 57 and the memory metal plate 51. At this time, the traction spring 64 contracts, pulling the connecting shaft 54 ​​down along the inclined groove 62 to the bottom, so that the second strong magnet 63 is magnetically fixed to the connecting part 53, thereby causing the entire memory metal plate 51 to deform inward, so that the front part of the volute guide plate 12 and the memory metal plate 51 form a guide channel with a larger curvature, so that the low-speed airflow can quickly pass through the guide and be discharged from the air outlet 13, thereby making the exhaust air more concentrated and avoiding the formation of backflow turbulence at the air outlet 13.

[0066] Meanwhile, during the above process, the sealing fold 56 moves closely against the inner wall of the sealing cover plate 11. The outer surface of the sealing fold 56 is formed with a sealing and noise reduction layer through a rubber coating process, which prevents air leakage at low wind speeds and avoids friction noise when the shape memory metal plate 51 moves. At the same time, the flow guide baffle 52 on the shape memory metal plate 51 can play the role of airflow diversion. When the shape memory metal plate 51 is bent, the internal stress is released by the shearing opening 55, and the side deformation of the shape memory metal plate 51 can be effectively prevented.

[0067] Example 2: Based on Example 1, the present invention further proposes a method for using a centrifugal fan with a three-dimensional flow impeller, including:

[0068] S1. Design the output power thresholds Pmax and Pmin of the variable frequency motor 4. Then, based on the thrust Fb generated by the airflow at the air outlet 13 on the memory metal plate 51 under different working conditions of Pmax and Pmin, design the magnetic strength of the first strong magnet 57 and the second strong magnet 63, as well as the tension Fa of the traction spring 64.

[0069] S2. When the output power of the variable frequency motor 4 is greater than Pmax, it is in "strong wind mode". At this time, the airflow thrust Fb overcomes the tension Fa of the traction spring 64 and the magnetic force of the second strong magnet 63 and the connecting part 53, so that the memory metal plate 51 is tightly attached to the side wall of the volute air guide plate 12. At this time, the overall air outlet has a "small curvature" and a smooth transition, avoiding airflow vortex.

[0070] S3. When the output power of the variable frequency motor 4 is less than Pmin, it is in "weak wind mode". At this time, the tension Fa of the traction spring 64 is greater than the sum of the airflow thrust Fb and the magnetic attraction of the first strong magnet 57 and the memory metal plate 51, causing the memory metal plate 51 to bend and deform inward. At this time, the overall air outlet is in a "large curvature" and turns quickly, making the airflow more concentrated.

[0071] S4. When the output power of the variable frequency motor 4 is between Pmin and Pmax, the memory metal plate 51 maintains its current state.

[0072] Working principle: In this method, the magnetic strength of the first strong magnet 57 and the second strong magnet 63, as well as the tension Fa of the traction spring 64, are designed based on the preset wind speed intensity changes to affect the thrust value Fb generated by the shape memory metal plate 51. This ensures that at high wind speeds, the shape memory metal plate 51 can adhere tightly to the inner wall of the volute wind guide plate 12 to form an effective fit. At the same time, at low wind speeds, the shape memory metal plate 51 can deform to a preset state under the traction of the traction spring 64 and be fixed by magnetic attraction, avoiding vibration of the shape memory metal plate 51 caused by small wind speed changes.

[0073] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A centrifugal fan with a three-dimensional impeller, characterized in that, include; The fan volute (1) has a volute curvature controlled by an exponential curve spiral equation. The fan volute (1) has an air outlet (13) at its end. The fan volute (1) has a guide baffle (52) for suppressing the generation of outflow vortices at one end near the air outlet (13). The three-dimensional flow impeller body (2) is rotatably disposed in the fan casing (1). The three-dimensional flow impeller body (2) has multiple blades (23) arranged in a ring array. The shape of the blades (23) is designed by parameters using multiple control curves and control equations. The variable air outlet guide (5) has its top end fixedly welded to the inner wall of the fan volute (1) and its bottom end extends toward the air outlet (13). The bottom end of the variable air outlet guide (5) moves toward the inner wall of the fan volute (1) to pull the variable air outlet guide (5) to bend and deform, thereby adjusting the curvature of the air outlet of the fan volute (1) to a preset value. The variable airflow guide (5) includes a shape memory metal plate (51) and a connecting part (53) fixedly welded to both sides of the bottom end of the shape memory metal plate (51). The guide baffle (52) is fixedly welded to the shape memory metal plate (51). The fan volute (1) includes a volute guide plate (12) and a sealing cover plate (11) fixedly welded to both sides of the volute guide plate (12). A self-resetting part (6) is fixedly welded to the outer wall of the bottom end of the sealing cover plate (11). The connecting part (53) is traction-reset through the self-resetting part (6). The self-resetting component (6) includes a sealing chamber fixedly welded to the outer wall of the sealing cover plate (11). The sealing chamber and the sealing cover plate (11) are provided with inclined grooves (62). A connecting shaft (54) is rotatably provided on the connecting part (53). The connecting shaft (54) is slidably disposed in the inclined groove (62). A connecting seat (65) is fixedly welded to the inner wall of the sealing chamber. A traction spring (64) is fixedly installed between the connecting seat (65) and the connecting shaft (54). The traction spring (64) is used to pull the connecting shaft (54) to slide downward along the inclined groove (62). A second strong magnetic component (63) is fixedly installed on the inner wall of the sealed chamber, and a first strong magnetic component (57) is fixedly welded to the inner wall of the bottom end of the volute air guide plate (12). The bottom of the connecting part (53) and the memory metal plate (51) are both magnetized so that the second strong magnetic component (63) is magnetically attracted to the connecting part (53), and the first strong magnetic component (57) is magnetically attracted to the bottom of the memory metal plate (51).

2. A centrifugal fan with a three-dimensional flow impeller according to claim 1, characterized in that, The outer surface of the flow guide baffle (52) is provided with multiple shearing openings (55) for eliminating bending stress. The top end of the memory metal plate (51) is fixedly welded to the inner wall of the volute air guide plate (12). The connecting part (53) is slidably disposed on the inner side wall of the sealing cover plate (11).

3. A centrifugal fan with a three-dimensional flow impeller according to claim 2, characterized in that, The two sides of the memory metal plate (51) are folded inward to form a sealing edge (56). The sealing edge (56) is attached to the inner wall of the sealing cover plate (11), and the outer surface of the sealing edge (56) is formed with a sealing and noise reduction layer by a rubber coating process.

4. A centrifugal fan with a three-dimensional flow impeller according to claim 1, characterized in that, An air inlet (16) is provided on one set of the sealing cover plates (11), and an air inlet cover (3) is fixedly welded to the outside of the air inlet (16). A variable frequency motor (4) is fixedly installed on another set of the sealing cover plates (11). One side of the three-dimensional flow impeller body (2) is fixedly connected to the output end of the variable frequency motor (4), and the other side of the three-dimensional flow impeller body (2) faces the air inlet cover (3).

5. A centrifugal fan with a three-dimensional flow impeller according to claim 4, characterized in that, The air inlet hood (3) includes an air inlet flare (31) and an inner air guide part (33) integrally formed on the constricted end of the air inlet flare (31). The inner end of the inner air guide part (33) is outwardly expanding. The end of the inner air guide part (33) is integrally formed with an outer folded lip (34). An assembly flange ring (32) is fixedly welded to the outer wall of the inner air guide part (33). The assembly flange ring (32) is fixedly installed on the outer wall of the air inlet (16). A reinforcing rib plate (35) is fixedly welded between the assembly flange ring (32) and the air inlet flare (31).

6. A centrifugal fan with a three-dimensional flow impeller according to claim 5, characterized in that, The three-dimensional impeller body (2) includes a rear plate meridional acceleration guide (21) and a front plate (22). The blade (23) is fixedly welded between the rear plate meridional acceleration guide (21) and the front plate (22). The output shaft of the variable frequency motor (4) is coaxially fixed with the rear plate meridional acceleration guide (21). The front plate (22) is integrally formed with an inner folded lip (24) that is adapted to the outer folded lip (34), and the assembly gap between the outer folded lip (34) and the inner folded lip (24) is 3mm.

7. A centrifugal fan with a three-dimensional flow impeller according to claim 6, characterized in that, A bearing (14) is installed between the rear plate radial acceleration guide fluid (21) and a set of sealing cover plates (11). A guide vane (15) is arranged in an annular shape on the outer side of the bearing (14). The guide vane (15) is fixedly welded to the sealing cover plate (11) so that the airflow flows along the volute guide plate (12) towards the air outlet (13).

8. A method of using a centrifugal fan with a three-dimensional flow impeller, as described in any one of claims 1-7, characterized in that, include: S1. Design the output power thresholds Pmax and Pmin of the variable frequency motor (4), and then design the magnetic strength of the first strong magnetic component (57) and the second strong magnetic component (63) and the tension Fa of the traction spring (64) based on the thrust Fb generated by the airflow at the air outlet (13) on the memory metal plate (51) under different working conditions of Pmax and Pmin. S2. When the output power of the variable frequency motor (4) is greater than Pmax, it is a "strong wind mode". At this time, the airflow thrust Fb overcomes the tension Fa of the traction spring (64) and the magnetic force of the second strong magnet (63) and the connecting part (53), so that the memory metal plate (51) is tightly attached to the side wall of the volute air guide plate (12). At this time, the overall air outlet has a "small curvature" smooth transition to avoid airflow vortex. S3. When the output power of the variable frequency motor (4) is less than Pmin, it is a "weak wind mode". At this time, the tension Fa of the traction spring (64) is greater than the sum of the airflow thrust Fb and the magnetic attraction of the first strong magnetic component (57) and the memory metal plate (51), causing the memory metal plate (51) to bend and deform inward. At this time, the overall air outlet is in a "large curvature" and turns quickly, making the airflow more concentrated. S4. When the output power of the variable frequency motor (4) is between Pmin and Pmax, the memory metal plate (51) maintains its current state.

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