Axial flow wind wheel, axial flow fan and air supply equipment

Abstract

The invention discloses an axial flow wind wheel, an axial flow fan and air supply equipment, and relates to the technical field of air supply equipment, the axial flow wind wheel comprises a hub and blades, each blade comprises a first blade part and a second blade part which are arranged in the radial direction of the axial flow wind wheel, the first blade part is located between the hub and the second blade part, and the second blade part is located between the hub and the second blade part. The first blade part is provided with a plurality of first rectification grooves distributed in the radial direction of the axial flow wind wheel, and the multiple first rectification grooves are sequentially connected to form a wave structure which is arranged in the thickness direction of the blade in a fluctuating mode. Separation points of airflow on the blades can be delayed, and the attachment length of the airflow on the blades is increased, so that the lifting force of the blades is improved, the effect of improving the operation efficiency of the axial flow wind wheel is achieved, separation of the airflow on the surfaces of the blades is reduced, vortex and turbulent flow are reduced, and noise and vibration generated by the blades are reduced.

Description

Technical Field

[0001] This invention relates to the field of air supply equipment technology, and in particular to an axial flow impeller, an axial flow fan, and an air supply device. Background Technology

[0002] Axial flow fans are widely used in household appliances. For example, most outdoor units of household air conditioners use axial flow fans. Currently, air conditioning systems have increasingly higher requirements for the efficiency and noise reduction of axial flow fan impellers, and traditional axial flow impellers can no longer meet the latest energy efficiency and noise requirements. There is an urgent need for a high-efficiency, low-noise axial flow impeller to adapt to the new air conditioning systems. Summary of the Invention

[0003] The main objective of this invention is to provide an axial flow impeller, an axial flow fan, and an air supply device, which aims to improve the operating efficiency of the axial flow impeller and reduce the noise during operation.

[0004] To achieve the above objectives, the present invention proposes an axial flow impeller comprising:

[0005] Wheel hubs; and

[0006] The blade includes a first blade portion and a second blade portion arranged radially along the axial flow impeller. The first blade portion is located between the hub and the second blade portion. The first blade portion is provided with a plurality of first rectifier slots arranged radially along the axial flow impeller. The plurality of first rectifier slots are connected in sequence to form a wave structure that undulates along the thickness direction of the blade.

[0007] In one embodiment, the number of the first rectifier slots is not less than 3 and the number of the first rectifier slots is not greater than 10.

[0008] In one embodiment, each of the first rectifier slots has an equal width in the radial direction of the axial flow impeller.

[0009] In one embodiment, the blade has a pressure surface and a suction surface disposed opposite to each other, each first rectifier groove is recessed from the suction surface toward the pressure surface to form a trough, and the first blade also has a connecting portion connecting two adjacent first rectifier grooves, the connecting portion being raised from the pressure surface toward the suction surface to form a crest.

[0010] The width of the first rectifier groove in the radial direction of the axial flow impeller is the distance between two adjacent wave crests.

[0011] In one embodiment, the width of the first rectifier groove in the radial direction of the axial flow impeller is defined as r1, and the depth of the first rectifier groove is defined as d, wherein d is not greater than 0.1r1.

[0012] In one embodiment, the second blade is provided with a second rectifier groove, which protrudes from the suction surface toward the pressure surface.

[0013] In one embodiment, the number of the second rectifier slots is one.

[0014] In one embodiment, on a projection plane perpendicular to the hub axis, the center of the hub is defined as the center point, and the projection radius of the blade is defined as R with the center point as the center. The projection radius of the first blade is defined as r2, where r2 is not greater than 0.7R.

[0015] The present invention also proposes an axial flow fan, including a motor and an axial flow impeller as described above, wherein the motor is driven to drive the axial flow impeller to rotate.

[0016] The present invention also proposes an air supply device, including the axial flow impeller as described above, or including the axial flow fan as described above.

[0017] In one embodiment, the air supply device is an air conditioner, and the axial flow impeller is located on the outdoor unit and / or indoor unit of the air conditioner.

[0018] The technical solution of this invention optimizes the structure of the axial flow wind turbine blades. Multiple first rectifying slots are arranged radially along the axial flow wind turbine in the first blade section located between the second blade section and the hub. These first rectifying slots can be connected sequentially to form a wave-shaped structure undulating along the blade thickness direction. On one hand, the undulating wave-shaped structure helps the airflow adhere more smoothly to the blade surface, thereby improving aerodynamic efficiency and increasing fan thrust. It also delays the airflow separation point on the blade, increasing the airflow adhesion length on the blade, thus helping to improve the blade's lift and ultimately enhancing the axial flow wind turbine's operating efficiency. On the other hand, the undulating wave-shaped structure along the blade thickness direction reduces airflow separation on the blade surface, reducing the generation of eddies and turbulence, thereby reducing noise and vibration emitted by the blades. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of an embodiment of an air conditioner outdoor unit provided by the present invention;

[0021] Figure 2 A schematic diagram of an embodiment of the axial flow wind turbine provided by the present invention.

[0022] Figure 3 for Figure 1 A schematic diagram of the structure of a central axial flow impeller at one angle;

[0023] Figure 4 for Figure 1 A partial sectional view of a central axial flow impeller;

[0024] Figure 5 A comparison chart of airflow and power between the axial flow wind turbine provided by this invention and existing wind turbines;

[0025] Figure 6 A comparison chart of airflow and noise between the axial flow fan provided by this invention and existing wind turbines.

[0026] Explanation of icon numbers:

[0027] 100. Axial flow impeller; 10. Hub; 20. Blade; 21. First blade; 211. First rectifier slot; 22. Second blade; 221. Second rectifier slot; 201. Leading edge; 202. Trailing edge; 203. Blade tip; 204. Blade root; 205. Pressure surface; 206. Suction surface; O. Center point;

[0028] 200, Motor; 300, Heat Exchanger; 400, Air Outlet Panel; 500, Mesh Cover.

[0029] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0030] 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 a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0032] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0033] Axial flow fans are widely used in household appliances. For example, most outdoor units of household air conditioners use axial flow fans. Currently, air conditioning systems have increasingly higher requirements for the impeller efficiency and noise levels of axial flow fans, and the traditional axial flow impeller 100 can no longer meet the latest energy efficiency and noise requirements. There is an urgent need for a high-efficiency, low-noise axial flow impeller 100 to adapt to the new air conditioning systems.

[0034] This invention proposes an axial flow impeller 100. By optimizing the structure of the axial flow impeller 100, the fan efficiency can be improved, and power consumption and noise can be reduced while achieving the same air volume.

[0035] The axial flow impeller 100 or an axial flow fan having the axial flow impeller 100 can also be used in air supply equipment, including but not limited to air conditioners, fans, air purifiers, dehumidifiers, humidifiers, etc. When the air supply equipment is an air conditioner, the axial flow impeller 100 can be installed in the outdoor unit and / or indoor unit of the air conditioner.

[0036] Taking the application of this axial flow impeller 100 in an air conditioner outdoor unit as an example, such as Figure 1As shown, in one embodiment, the outdoor unit of the air conditioner includes a casing, and an axial flow fan 100, a motor 200, and a heat exchanger 300 disposed within the casing. The casing has an air inlet and an air outlet. The heat exchanger 300 is disposed opposite to the air inlet, and the axial flow fan 100 is located between the heat exchanger 300 and the air outlet. The axial flow fan 100 is driven by the motor 200. When the outdoor unit is working, the motor 200 drives the axial flow fan 100 to rotate, drawing outside air into the casing through the air inlet to exchange heat with the heat exchanger 300 before expelling it from the air outlet. Optionally, the casing has an air outlet panel 400 located on the front side, with an air outlet and a mesh cover 500 at the air outlet to prevent foreign objects from entering the interior of the outdoor unit. By employing the axial flow fan 100 of the present invention, the noise and power consumption of the outdoor unit can be reduced while achieving the same airflow, enabling it to meet the latest air conditioning energy efficiency and noise requirements. The following mainly illustrates the implementation of the axial flow fan 100.

[0037] Please see Figures 2 to 4 In one embodiment of the present invention, the axial flow impeller 100 includes a hub 10 and blades 20. The blades 20 include a first blade portion 21 and a second blade portion 22 arranged radially along the axial flow impeller 100. The first blade portion 21 is located between the hub 10 and the second blade portion 22. The first blade portion 21 is provided with a plurality of first rectifier grooves 211 arranged radially along the axial flow impeller 100. The plurality of first rectifier grooves 211 are sequentially connected to form a wave structure that undulates along the thickness direction of the blades 20.

[0038] It is understood that the axial flow wind turbine 100 includes a hub 10 and blades 20 disposed on the outer periphery of the hub 10. The number of blades 20 is generally two, but can be two, three, four, five, or more. Optionally, the number of blades 20 is not less than two and not more than five. For example, the hub 10 has three blades 20 spaced circumferentially and evenly arranged, with each blade 20 having a substantially similar shape and thickness to ensure the stability of the axial flow wind turbine 100 during rotation. Taking a single blade 20 as an example, the blade root 204, leading edge 201, blade tip 203, and trailing edge 202 of the blade 20 are connected end-to-end to form the outer periphery of the blade 20. The blade root 204 connects to the hub 10, and the blade tip 203 is located on the side of the blade root 204 away from the hub 10, forming the free end of the blade 20. In the incoming flow direction, the leading edge 201 is located on the upstream side of the blade 20, and the trailing edge 202 is located on the outflow side of the blade 20. The axial flow impeller 100 is driven to rotate by the motor 200. Air flows in from the leading edge 201 of the blades 20, and after the blades 20 do work to gain pressure, it flows out from the trailing edge 202 of the blades 20, thus realizing the air supply function. The blades 20 have a pressure surface 205 and a suction surface 206. The pressure surface 205 is located on the side of the axial flow impeller 100 where the air is discharged, and the suction surface 206 is located on the other side of the blades 20. When the blades 20 rotate, the pressure surface 205 is directly impacted by the airflow, and the pressure is relatively high. On the other hand, the suction surface 206 moves relatively fast relative to the airflow when the blades 20 rotate, and the pressure is relatively low, forming a low-pressure area.

[0039] The first leaf portion 21 refers to the position of the blade 20 near the leaf root 204, and the second leaf portion 22 refers to the position of the blade 20 near the leaf tip 203. The wave structure undulating along the thickness direction of the blade 20 refers to a structural feature shape with undulation and unevenness. It can be a regular wave with regular geometric shape (such as sine wave, cosine wave, sawtooth wave, etc.) or an irregular wave shape.

[0040] The technical solution of this invention optimizes the structure of the blade 20 of the axial flow impeller 100. Multiple first rectifying grooves 211 are arranged radially along the first blade 21 of the blade 20 located between the second blade 22 and the hub 10. These first rectifying grooves 211 can be connected sequentially to form a wave-shaped structure undulating along the thickness direction of the blade 20. This undulating wave-shaped structure helps the airflow adhere more smoothly to the surface of the blade 20, thereby improving aerodynamic efficiency and increasing fan thrust. It also delays the separation point of the airflow on the blade 20, increasing the adhesion length of the airflow on the blade 20, thus helping to improve the lift of the blade 20 and ultimately enhancing the operating efficiency of the axial flow impeller 100. On the one hand, the undulating wave-shaped structure along the thickness direction of the blade 20 can reduce the separation of airflow on the surface of the blade 20, reduce the generation of eddies and turbulence, and thus reduce the noise and vibration emitted by the blade 20. On the other hand, the undulating wave-shaped structure can improve the pressure distribution on the blade 20, reduce the local high-pressure area on the blade 20, thereby reducing the load and stress on the blade 20. Furthermore, since the wave-shaped structure is relatively closer to the hub 10, that is, in the area where the blade 20 bears a larger atmospheric load, the load in this area can be evenly distributed, better reducing the local stress concentration of the blade 20. In addition, the wave-shaped structure can enhance the structural strength of the blade 20, thereby increasing the service life of the axial flow wind turbine 100.

[0041] Optionally, in one embodiment, the number of the first rectifying slots 211 is not less than 3 and not more than 10. This arrangement ensures that the number of the first rectifying slots 211 is moderate, neither too many nor too few. It avoids the situation where too few first rectifying slots 211 would fail to provide effective rectification, resulting in insignificant improvements in the operating efficiency and noise reduction of the axial flow impeller 100. Simultaneously, it avoids the situation where too many first rectifying slots 211 would cause complex interference on the surface of the blades 20, leading to additional turbulence and eddies, and also avoids the situation where too many first rectifying slots 211 would increase the weight of the blades 20 and increase costs due to complex blade design. For example, the number of first rectifying slots 211 can be 3, 4, 5, 6, 7, 10, etc.

[0042] like Figure 3 , Figure 4As shown, in one embodiment, the width of each of the first rectifying slots 211 in the radial direction of the axial flow impeller 100 is equal. This arrangement ensures that the wave undulation period of the wave structure formed by the sequential connection of multiple first rectifying slots 211 is the same, thus providing more uniform airflow disturbance. Since the airflow disturbance is regular, it can better reduce the turbulence generated by the airflow on the surface of the blade 20, helping the airflow to adhere more smoothly to the surface of the blade 20, thereby reducing energy loss, improving aerodynamic efficiency, and better reducing noise generation. In addition, the identical wave undulation period also makes it easier to maintain the consistency of the blade 20 during the manufacturing process, simplifying the blade 20 production process.

[0043] like Figure 2 , Figure 4 As shown, in one embodiment, the blade 20 has a pressure surface 205 and a suction surface 206 disposed opposite to each other. Each first rectifier groove 211 is recessed from the suction surface 206 toward the pressure surface 205 to form a trough. The first blade portion 21 also has a connecting portion connecting two adjacent first rectifier grooves 211. The connecting portion protrudes from the pressure surface 205 toward the suction surface 206 to form a crest.

[0044] The width of the first rectifier groove 211 in the radial direction of the axial flow impeller 100 is the distance between two adjacent wave crests.

[0045] Specifically, when the first rectifier groove 211 is configured to be recessed towards the pressure surface 205 to form a trough, the surface of the pressure surface 205 can be made to bulge, thereby increasing the contact area between the pressure surface 205 of the blade 20 and the airflow, thus improving the lift of the blade 20. Furthermore, it can reduce the pressure gradient of the pressure surface 205 of the blade 20, reducing boundary layer separation caused by pressure difference. Additionally, when the connecting portion of adjacent first rectifier grooves 211 bulges from the pressure surface 205 towards the suction surface 206 to form a crest, the position between adjacent troughs on the suction surface 206 can form a protrusion on the surface of the suction surface 206. With higher kinetic energy on the suction surface 206 and easier airflow escaping from the surface of the blade 20, it helps to attract airflow to adhere more tightly to the suction surface 206, reducing airflow separation on the suction surface 206 of the blade 20, improving boundary layer adhesion, and also reducing turbulence and eddy current linearity on the suction surface 206, thereby reducing aerodynamic noise generated when the blade 20 rotates.

[0046] like Figure 4 As shown, optionally, the width of the first rectifier groove 211 in the radial direction of the axial flow impeller 100 is defined as r1, and the depth of the first rectifier groove 211 is defined as d, wherein d is not greater than 0.1r1.

[0047] This configuration results in the depth of the first rectifier slot 211 being shallower than its width along the radial direction of the axial flow impeller 100. In other words, the depth of the undulating wave-like structure located on the first blade 21 is relatively shallow. This avoids the problem of a reduced effective cross-sectional area of ​​the blade 20 due to a deeper wave-like structure, which would otherwise lead to a decrease in the structural strength and stiffness of the blade 20. Furthermore, the shallow depth of the wave-like structure prevents excessively strong airflow interference on the surface of the blade 20, thus avoiding airflow separation and increased turbulence, which would reduce the aerodynamic efficiency of the blade 20. For example, d can be 0.1r1, 0.09r1, 0.08r1, 0.07r1, 0.06r1, etc.

[0048] like Figure 2 , Figure 4 In one embodiment, the second blade 22 is provided with a second rectifier groove 221, which protrudes from the suction surface 206 toward the pressure surface 205.

[0049] During the actual operation of the axial flow impeller 100, leakage is more likely to occur in the area of ​​the blade 20 near the blade tip 203. That is, due to the gap between the blade 20 and the fan casing, the airflow velocity is faster and the pressure is lower on the suction surface 206, while the pressure on the pressure surface 205 is higher. The airflow on the high-pressure side is more likely to be pulled to the low-pressure side through this gap, resulting in leakage.

[0050] To this end, a second rectifier slot 221 is provided in the second blade section 22. Since the second blade section 22 is closer to the blade tip 203 region, the second rectifier slot 221 can guide the airflow more smoothly from the blade tip 203 to the blade root 204 of the blade 20, reducing the formation of vortices and reducing leakage caused by airflow separation in the blade tip 203 region. In addition, the second rectifier slot 221 can also reduce the noise generated in the blade tip 203 region by reducing the formation of vortices in the blade tip 203 region, thereby further reducing the noise generated during the operation of the axial flow impeller 100.

[0051] In this invention, when a large number of second rectifier slots 221 are provided in the region of the blade 20 near the blade tip 203, the overall structural strength of the region of the blade 20 near the blade tip 203 decreases, affecting the durability of the blade 20 during rotation. Furthermore, providing a large number of second rectifier slots 221 can lead to stress concentration in the blade tip 203 region, making the blade 20 more susceptible to damage when subjected to aerodynamic loads or other forces. Therefore, in one embodiment of this invention, optionally, the number of second rectifier slots 221 is one. Of course, in other embodiments of this invention, the number of second rectifier slots 221 can also be two, three, etc.

[0052] like Figure 3 , Figure 4 As shown, on the projection plane perpendicular to the axis of the hub 10, the center of the hub 10 is defined as the center point O. With the center point O as the center, the projection radius of the blade 20 is defined as R, and the projection radius of the first blade 21 is defined as r2, where r2 is not greater than 0.7R.

[0053] In this embodiment, the radius R of the axial flow impeller 100 refers to the straight-line distance from the center point O of the hub 10 to the outermost edge of the blade tip 203 in the radial direction of the hub 10. The radius of the first blade 21 is r2, where r2 is not greater than 0.7R. This setting ensures that the length of the first blade 21 is moderate, neither too long nor too short, thereby ensuring that the wave structure formed by the sequential connection of multiple first rectifying slots 211 does not approach the blade tip 203 region too closely, and that rectification only occurs in the middle region of the blade 20 and the region of the blade 20 near the blade root 204. This ensures that the area of ​​the blade tip 203 is not affected, and that the structural strength and working efficiency of the blade 20 are guaranteed when only a small number of second rectifying slots 221 are provided in the second blade 22. It can be understood that the first blade 21 is located between the hub 10 and the second blade 22, so r2 should also be greater than the radius r of the hub 10. That is, r < r2 ≤ 0.7R. For example, r1 can be 0.1R, 0.2R, 0.3R, 0.4R, 0.5R, 0.6R, 0.7R, etc.

[0054] An experimental comparison was conducted between an existing wind turbine (i.e., a smooth wind turbine) and an axial flow wind turbine 100 provided in an embodiment of the present invention (hereinafter referred to as the wind turbine with a first rectifier slot and a second rectifier slot in this solution), and the results were as follows: Figure 5 The air volume-power comparison chart shown, and as follows Figure 6 The image shows a comparison of airflow and noise levels. (Source: [Insert Source Here]) Figure 5 It can be seen that, under the same air volume, the power of the wind turbine with the first and second rectifier slots provided by this solution is less than that of the existing wind turbine, which can effectively reduce power consumption. Figure 6 It can be seen that, under the same air volume, the noise of the impeller with the first and second rectifier slots provided by this solution is less than that of the existing impeller, which can effectively reduce noise.

[0055] The present invention also proposes an axial flow fan, which includes a motor 200 and an axial flow impeller 100. The specific structure of the axial flow impeller 100 is as described in the above embodiments. Since the outdoor unit of this air conditioner adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0056] In this embodiment, the output shaft of the motor 200 is driven to the hub 10. The motor 200 drives the axial flow impeller 100 to rotate. Air flows in from the leading edge 201 of the blades 20, and after the blades 20 do work to gain pressure, it flows out from the trailing edge 202 of the blades 20, thereby realizing the air delivery function. Furthermore, through the above-described design of the axial flow impeller 100, the noise and power consumption of the axial flow fan can be reduced while achieving the same air volume.

[0057] This invention also proposes an air supply device, including an axial flow impeller 100 or an axial flow fan having an axial flow impeller 100. The specific structure of the axial flow impeller 100 is as described in the above embodiments. Since this air supply device adopts all the technical solutions of all the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated upon here. The air supply device includes, but is not limited to, air conditioners, fans, air purifiers, dehumidifiers, and humidifiers.

[0058] In one embodiment, the air supply device is an air conditioner, and the axial flow impeller 100 is disposed in the outdoor unit and / or indoor unit of the air conditioner.

[0059] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An axial flow impeller, characterized in that, include: Wheel hub; as well as The blade includes a first blade portion and a second blade portion arranged radially along the axial flow impeller. The first blade portion is located between the hub and the second blade portion. The first blade portion is provided with a plurality of first rectifier slots arranged radially along the axial flow impeller. The plurality of first rectifier slots are connected in sequence to form a wave structure that undulates along the thickness direction of the blade.

2. The axial flow impeller as described in claim 1, characterized in that, The number of the first rectifier slots is not less than 3 and not more than 10.

3. The axial flow impeller as described in claim 1, characterized in that, Each of the first rectifier slots has the same width in the radial direction of the axial flow impeller.

4. The axial flow impeller as described in claim 3, characterized in that, The blade has a pressure surface and a suction surface arranged opposite to each other. Each first rectifier groove is recessed from the suction surface toward the pressure surface to form a trough. The first blade also has a connecting part that connects two adjacent first rectifier grooves. The connecting part is convex from the pressure surface toward the suction surface to form a peak. The width of the first rectifier groove in the radial direction of the axial flow impeller is the distance between two adjacent wave crests.

5. The axial flow impeller as described in claim 4, characterized in that, The width of the first rectifier groove in the radial direction of the axial flow impeller is defined as r1, and the depth of the first rectifier groove is defined as d, wherein d is not greater than 0.1r1.

6. The axial flow impeller as described in claim 4, characterized in that, The second blade is provided with a second rectifier groove, which protrudes from the suction surface toward the pressure surface.

7. The axial flow impeller as described in claim 6, characterized in that, The number of the second rectifier slot is 1.

8. The axial flow wind turbine as described in any one of claims 1 to 7, characterized in that, On a projection plane perpendicular to the hub axis, the center of the hub is defined as the center point, and the projection radius of the blade is defined as R with the center point as the center. The projection radius of the first blade is defined as r2, where r2 is not greater than 0.7R.

9. An axial flow fan, characterized in that, It includes a motor and an axial flow impeller as described in any one of claims 1 to 8, wherein the motor is driven to drive the axial flow impeller to rotate.

10. An air supply device, characterized in that, It includes an axial flow fan impeller as described in any one of claims 1 to 8, or an axial flow fan as described in claim 9.

11. The air supply device as described in claim 10, characterized in that, The air supply device is an air conditioner, and the axial flow impeller is located in the outdoor unit and / or indoor unit of the air conditioner.

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