Air conditioner outdoor unit

Abstract

The application relates to an air conditioner outdoor unit, belonging to the technical field of air conditioner outdoor units; the air conditioner outdoor unit comprises an axial flow fan, the axial flow fan comprises a plurality of blades, the blade has a leading edge, a trailing edge, a blade root and a blade tip; from the blade root to the blade tip, the blade has a plurality of characteristic surfaces; the axial coordinate value of the leading edge point corresponding to each characteristic surface on the blade first decreases, then increases and finally decreases with the increase of the axial flow fan radius; the axial coordinate value of the trailing edge point corresponding to each characteristic surface on the blade first increases, then decreases with the increase of the axial flow fan radius; the working angle corresponding to each characteristic surface on the blade first increases, then decreases with the increase of the axial flow fan radius; the front bending angle corresponding to each characteristic surface on the blade gradually decreases with the increase of the axial flow fan radius. The application reduces the separation loss of airflow on the blade surface, improves the airflow pushing efficiency, and perfectly realizes the triple technical targets of noise reduction, air volume increase and stable power.

Description

Technical Field

[0001] This application relates to the field of air conditioner outdoor unit technology, and in particular to an air conditioner outdoor unit. Background Technology

[0002] Currently, air conditioners are rapidly evolving towards miniaturization. To meet market demand for compact sizes, their frame volume is constantly shrinking, while simultaneously ensuring the heat exchange capacity required for cooling and heating. This necessitates that the air supply system provide a more ample airflow. As the core component of the air supply system, the axial fan plays a crucial role in driving airflow, and its performance directly determines the air delivery effect.

[0003] To meet the demands of high airflow, high static pressure, high efficiency, and low noise while miniaturizing the fan casing, mainstream manufacturers have begun upgrading axial fans, increasing the number of blades from the traditional three to four and gradually increasing the fan diameter. However, large-sized fans have significant drawbacks: on the one hand, they generate considerable aerodynamic noise; on the other hand, their own vibrations can induce low-frequency noise. In particular, low-frequency sound has extremely strong penetrating power, severely impacting the user experience. Specifically, conventional four-blade axial fans, due to their symmetrical blade distribution, experience synchronized impacts on the airflow. This leads to the superposition of energy at different airflow pulse frequencies, increasing the amplitude of vibrations at the same frequency and ultimately amplifying noise, further exacerbating the interference of low-frequency sound on the user experience. Furthermore, the trailing edge vortices of different blades detach synchronously, forming large, highly coherent vortices, further deteriorating the noise reduction effect. Summary of the Invention

[0004] This application provides an outdoor unit for an air conditioner, the purpose of which is to optimize the fan flow field distribution by adopting an asymmetric blade structure so that the airflow pulse frequency generated by different blades is different; at the same time, the working angle, the forward bend angle curve, and the leading edge distribution curve and trailing edge distribution curve on the meridional surface of the blade are coupled; thereby solving the problem of high fan noise and affecting user experience; and finally achieving the effect of increasing air volume without increasing fan power, and reducing the low-frequency discrete noise and wideband rotational noise of the fan.

[0005] To achieve the above objectives, this application adopts the following technical solution: This application provides an outdoor unit for an air conditioner, including... The outer casing has an air inlet and an air outlet, and an air duct is provided between the air inlet and the air outlet; An axial flow fan, disposed within the air duct, is used to drive airflow from the air inlet into the air duct and then out through the air outlet; the axial flow fan includes: Wheel hub; Multiple blades are disposed on the outer peripheral wall of the hub and spaced apart along the circumference of the hub; each blade has a leading edge, a trailing edge, a root, and a tip; from the root to the tip, each blade has multiple feature surfaces; The axial coordinate values ​​of the leading edge points corresponding to each feature surface on the blade first decrease, then increase, and then decrease again as the radius of the axial fan increases. The axial coordinate values ​​of the trailing edge points corresponding to each feature surface on the blade first increase and then decrease as the radius of the axial fan increases; The working angles corresponding to each feature surface on the blades first increase and then decrease as the radius of the axial fan increases; The forward bend angle corresponding to each feature surface on the blade gradually decreases as the radius of the axial fan increases.

[0006] In the above embodiments, this application achieves a dual noise reduction effect by employing an asymmetric odd-numbered blade structure in the axial flow fan: on the one hand, the asymmetric distribution of the odd-numbered blades ensures that the airflow pulse frequencies generated by each blade do not overlap, effectively dispersing airflow pulse energy and reducing the intensity of low-frequency discrete noise; on the other hand, the trailing edge shedding vortices of the odd-numbered blades do not detach synchronously, avoiding the formation of large-scale vortices with strong coherence, thereby improving the intensity of broadband rotational noise. Simultaneously, this application also optimizes the fan flow field by coupling the operating angle, forward bend angle, and leading-edge axial coordinates with the trailing-edge axial coordinates; this reduces airflow separation losses on the blade surface, improves airflow propulsion efficiency, and maintains the same actual operating power as existing fans, perfectly achieving the triple technical goals of noise reduction, increased airflow, and stable power.

[0007] In some embodiments, the working angle of the blade is in the range of 53° to 63°.

[0008] In the above embodiments, this application limits the blade operating angle to the range of 53°~63°, which is the optimal range for aerodynamic performance. This ensures that the local length of each feature surface in the circumferential direction is sufficient to capture airflow, avoiding the situation where the circumferential length of the cross section is too short when the operating angle is <53°, resulting in reduced airflow capture and insufficient airflow to meet the heat exchange requirements of small air conditioners. At the same time, it also prevents the circumferential length from being too long when the operating angle is >63°, which would intensify the impact of airflow on the pressure surface, increase vortex shedding noise, reduce efficiency, and increase power. Thus, a precise balance between circumferential length, airflow driving efficiency, and noise control is achieved within the range of 53°~63°, laying the foundation for key parameters for efficient and low-noise operation of the fan.

[0009] In some embodiments, the forward bending angle of the blade ranges from 0° to 45°.

[0010] In the above embodiments, this application limits the blade's forward bend angle to 0°~45° to avoid the following when the forward bend angle is less than 0°, the leading edge bends backward, the airflow needs to bypass the trailing edge to enter the flow channel, the local acceleration loss increases, the effective flow area decreases, and the air supply efficiency decreases; it also avoids the following when the forward bend angle is greater than 45°, the leading edge circumferential deflection is too large, the angle between the incoming flow and the leading edge increases sharply, the leading edge pressure pulsation is enhanced, the impact noise increases, and the suction surface is prone to local separation, exacerbating vortex shedding; therefore, within the range of 0°~45°, acceleration loss and impact noise can be suppressed simultaneously, and high efficiency and low noise can be achieved in conjunction with the operating angle.

[0011] In some embodiments, the number of blades may be 3, 5, or 7. The leading edge distribution curve of the blade exhibits a formulaic change, satisfying the following formula:

[0012] Where r is the radius corresponding to the feature surface of the blade; z is the axial coordinate value of the leading edge point on the feature surface along the hub axis; The trailing edge distribution curve of the blade is divided into a first segment and a second segment; the first segment exhibits a formulaic change, satisfying the following formula:

[0013] The second curve exhibits a formulaic change, satisfying the following formula:

[0014] Where r is the radius corresponding to the feature surface of the blade; z is the axial coordinate value of the leading edge point on the feature surface along the hub axis; The working angle distribution curve of the blade is divided into a third curve and a fourth curve; the third curve exhibits a formulaic change, and the formula satisfies:

[0015] The fourth curve segment exhibits a formulaic change, and the formula satisfies:

[0016] Where r is the radius corresponding to the feature surface of the blade; z is the axial coordinate value of the leading edge point on the feature surface along the hub axis; The forward bend angle distribution curve of the blade exhibits a formulaic change, satisfying the following formula:

[0017] Where r is the radius corresponding to the feature surface of the blade; z is the axial coordinate value of the leading edge point on the feature surface along the hub axis.

[0018] In the above embodiments, this application further enhances the noise reduction effect by adopting an asymmetric five-blade structure in the axial flow fan. This application also optimizes the fan profile more finely by coupling the working angle distribution curve, the forward bend angle distribution curve, and the leading and trailing edge distribution curves on the blade meridional surface; this minimizes airflow separation losses on the blade surface and improves airflow propulsion efficiency, ultimately increasing the airflow of the new fan by 5% compared to existing fans, while maintaining the same actual operating power, perfectly achieving the triple technical goals of noise reduction, increased airflow, and stable power.

[0019] In some embodiments, the trailing edge distribution curve satisfies: Along the radial direction of the blade, the range of the radius corresponding to the point on the first curve segment starts from the root of the blade and extends to a position where the radial length reaches 63% of the total length of the blade; Along the radial direction of the blade, the radius corresponding to the point on the second curve ranges from a position where the radial length is 63% of the total length of the blade to the tip of the blade.

[0020] In the above embodiments, this application divides the trailing edge distribution curve into two segments along the blade radial direction. The first segment covers the region from the blade root to 63% of the total blade length, and the second segment covers the region from 63% of the total length to the blade tip. This segmented design can perform differentiated optimization of the z-coordinate for different radial positions of the blade. The blade root region adjusts the z-coordinate through the first segment curve to increase the trailing edge outlet flow cross section and suppress the tendency of airflow backflow at the root. The blade tip region maintains a smooth transition of the trailing edge z-coordinate through the second segment curve, which is close to a straight line, and weakens the intensity of trailing edge vortex shedding. This ultimately solves the problem that the existing single trailing edge curve cannot adapt to radial airflow differences and causes severe airflow separation, significantly improving the aerodynamic performance of the fan and further reducing broadband rotational noise.

[0021] In some embodiments, the working angle distribution curve satisfies: Along the radial direction of the blade, the range of the radius corresponding to the point on the third curve starts from the root of the blade and extends to the position where the radial length reaches 50% of the total length of the blade; Along the radial direction of the blade, the range of the radius corresponding to the point on the fourth curve starts from a position where the radial length is 50% of the total length of the blade and extends to the tip of the blade.

[0022] In the above embodiments, this application divides the working angle distribution curve into two segments along the blade radial direction. The third segment covers the area from the blade root to 50% of the total blade length, and the fourth segment covers the area from 50% of the total length to the blade tip. The third segment uses a convex line to make the working angle increase rapidly with the radius, extending the circumferential length and improving the work capacity in the low-speed zone. The fourth segment uses a concave line to make the working angle decrease slowly with the radius, shortening the circumferential length and reducing high-speed impact noise, thereby balancing blade root efficiency and blade tip quietness, and achieving efficient and low-noise operation of the entire blade.

[0023] In some embodiments, the blade has a suction surface; The suction surface has several arc-shaped concave ribs on the side near the blade tip.

[0024] In the above embodiments, this application provides several arc-shaped concave ribs on the side of the blade suction surface near the blade tip. On the one hand, this can locally strengthen the structure of the area with the most intense vibration at the trailing edge of the blade tip, effectively weakening the periodic vibration deformation of the fan blade at medium and high speeds, and reducing the low-frequency transmission noise formed by vibration transmitted to the air conditioner casing through the hub and motor. On the other hand, the arc-shaped concave ribs can divide the airflow at the blade tip, destroy the generation of large-scale coherent vortices, further suppress the vortex intensity at the trailing edge of the fan blade tip, reduce broadband rotational noise, and ultimately achieve the dual effect of vibration reduction and vortex suppression noise reduction. At the same time, it improves the reliability of the blade structure and avoids fatigue damage caused by long-term vibration.

[0025] In some embodiments, the spacing between two adjacent arc-shaped concave ribs is 10 mm to 20 mm, and the depth of the arc-shaped concave ribs is 1.5 mm to 3 mm.

[0026] In the above embodiments, this application limits the spacing between adjacent arc-shaped concave ribs to a range of 10mm to 20mm. This avoids the formation of airflow obstruction zones due to excessively small spacing (less than 10mm), which would hinder airflow and cause air volume loss. Simultaneously, it avoids the defects of insufficient rib coverage, ineffective reinforcement of the blade tip vibration area, and limited vibration reduction effect caused by excessively large spacing (greater than 20mm). Ultimately, this balances the structural reinforcement effect with airflow smoothness, ensuring that the fan achieves vibration reduction without affecting airflow, further consolidating the performance advantages of high airflow and low noise. Furthermore, this application limits the depth of the arc-shaped concave ribs to a range of 1.5mm to 3mm. This avoids the problem of excessively thin blades in the Z-axis direction at the concave ribs due to excessive depth (greater than 3mm), which would reduce the strength at the concave ribs. Simultaneously, it avoids the problem of insufficient structural reinforcement and vibration suppression failure due to excessively small depth (less than 1.5mm).

[0027] In some embodiments, in two adjacent arcuate ribs, the circumferential length of the arcuate rib closer to the leaf root is half the circumferential length of the arcuate rib closer to the leaf tip.

[0028] In the above embodiments, this application specifies that in two adjacent arc-shaped concave ribs, the circumferential length of the concave rib near the blade root is half that of the concave rib near the blade tip. This differentiated length design can adapt to the vibration intensity and circumferential length characteristics of different radial positions of the blade. The blade tip region has strong vibration and a long circumferential length, requiring a longer concave rib to achieve sufficient vibration reduction. The region near the blade root has weak vibration and a short circumferential length, and a short concave rib can meet the basic vibration reduction requirements while avoiding obstruction of airflow and impact on the air supply efficiency of the blade root region due to excessively long concave ribs. Ultimately, differentiated vibration reduction is achieved, weakening the vibration at the blade tip, while avoiding noise or airflow loss caused by additional airflow interference, so that the vibration reduction effect and air supply efficiency do not conflict.

[0029] In some embodiments, the number of the arc-shaped concave ribs is 3 to 5.

[0030] In the above embodiments, this application limits the number of arc-shaped concave ribs to a range of 3 to 5. This number design can balance the vibration reduction effect, processing feasibility and cost control; avoid the problem that the strength enhancement is limited and the vibration reduction effect is poor due to too few ribs (less than 3 ribs); in addition, it also avoids the defects of increased mold processing complexity and processing cost caused by too many concave ribs (more than 5 ribs); at the same time, it avoids the problem of dense concave ribs dividing the airflow and causing airflow turbulence.

[0031] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0032] 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 these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the overall structure of the outdoor unit of the air conditioner provided in the embodiment of this application; Figure 2 This is a schematic diagram of the overall structure of the outdoor unit (hidden protective grille) of the air conditioner provided in the embodiment of this application; Figure 3 This is a first-view structural schematic diagram of the axial fan provided in the embodiments of this application; Figure 4 This is a second-view structural schematic diagram of the axial fan provided in the embodiments of this application; Figure 5 This is a top view of the axial fan provided in the embodiment of this application; Figure 6This is a bottom view of the axial fan provided in the embodiment of this application; Figure 7 This is a schematic diagram of the working angle and forward bend angle of the blade provided in the embodiments of this application; Figure 8 This is a projection of the leading / trailing edge of the blade provided in the embodiment of this application onto the meridional plane; Figure 9 This is a diagram showing the leading edge distribution of the blades provided in an embodiment of this application; Figure 10 This is a trailing edge distribution curve of the blade provided in an embodiment of this application; Figure 11 This is a diagram showing the working angle distribution of the blades provided in an embodiment of this application; Figure 12 This is a diagram showing the forward bending angle distribution of the blades provided in an embodiment of this application; Figure 13 This is a comparison chart of the static pressure efficiency of the axial fan provided in the embodiments of this application and the existing four-blade fan; Figure 14 This is a comparison chart of the noise ratio between the axial fan provided in this application embodiment and the existing four-blade fan; Figure 15 This is a comparison chart of the static pressure coefficients of the axial flow fan provided in this application embodiment and the existing four-blade fan.

[0034] In the above figures: the X-axis is defined as the front-to-back direction (vertical); the Y-axis is defined as the left-to-right direction (horizontal); and the Z-axis is defined as the up-down direction (vertical).

[0035] In the above figures: r represents the radius corresponding to a certain feature interface, g represents the working angle, and w represents the forward bending angle.

[0036] In the above figures: 100, axial fan; 110, blade; 111, pressure surface; 112, suction surface; 112a, first arc-shaped concave rib; 112b, second arc-shaped concave rib; 112c, third arc-shaped concave rib; 112d, reinforcing concave rib; 113, leading edge; 114, trailing edge; 115, blade tip; 116, blade root; 120, hub; 200, outer casing; 210, air outlet; 220, protective grille. Detailed Implementation

[0037] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0038] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0039] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0040] Additionally, if the meaning of "and / or" in the text is that it includes three parallel options, taking "A and / or B" as an example, it includes option A, option B, or an option that satisfies both A and B.

[0041] The present application will now be described in detail through exemplary embodiments. However, it should be understood that, without further description, elements, structures, and features in one embodiment may be advantageously incorporated into other embodiments.

[0042] Currently, air conditioners are rapidly becoming smaller, leading to a continuous reduction in their frame size. At the same time, air conditioners still need to maintain sufficient heat exchange capacity to meet cooling and heating demands, requiring the air supply system to provide ample airflow. As the core of the air supply system, the performance of the axial fan directly determines the airflow effect, making its design upgrades crucial for manufacturers to meet these demands. Currently, mainstream air conditioner manufacturers (including Daikin, Mitsubishi Heavy Industries, Midea, Gree, Haier, and Hisense) generally use a four-blade design for their top-discharge outdoor unit axial fans, with fan diameters ranging from 680mm to 820mm and heights from 195mm to 230mm. Furthermore, these fans typically employ cylindrical hubs and incorporate flanged structures at the blade tips. In practical applications, large four-blade fans (680-820mm in diameter) not only generate significant aerodynamic noise but also produce low-frequency vibrations due to their structural characteristics, resulting in highly penetrating low-frequency sound transmission.

[0043] Specifically, there are often four-bladed axial fans. Because the blades are symmetrically distributed, the impact of the blades on the airflow is synchronous. That is, the energy of the airflow pulse frequency will be superimposed, the amplitude of the same frequency will increase, and the noise will be amplified. At the same time, the trailing edge vortices of different blades will fall off synchronously, forming large-size vortices with strong coherence, which will increase the noise.

[0044] Based on this, this application proposes an outdoor air conditioning unit that adopts an asymmetric five-blade 110 structure, so that the airflow pulse frequencies generated by different blades 110 are different. At the same time, the working angle distribution curve, the forward bending angle distribution curve and the leading / trailing edge distribution curve on the meridional plane of the blade 110 are coupled to optimize the fan flow field distribution. This achieves the effect of increasing air volume by 5%, without increasing fan power, and significantly reducing low-frequency discrete noise and wideband rotational noise. It solves the problem that existing axial fans, due to their symmetrical structure, cause the superposition of airflow pulse energy and prominent low-frequency vibration, making it difficult to balance air volume, power and noise.

[0045] In the following, embodiments of this application will be described in detail with reference to the accompanying drawings.

[0046] As attached Figures 1 to 8 As shown in an illustrative embodiment of this application, the outdoor unit of the air conditioner includes a housing 200 and an axial fan 100.

[0047] In some embodiments, a compressor is provided inside the housing 200; the compressor is a gas pressurization device used to compress the refrigerant from a low-pressure and low-temperature state to a high-pressure and high-temperature state; the compressor compresses the incoming low-pressure gaseous refrigerant by driving internal moving parts (such as pistons, rotors, scrolls, etc.) to make mechanical movements through a motor, so as to convert it into a high-pressure gaseous refrigerant. The specific process mainly includes three typical stages: intake, compression, and exhaust.

[0048] In some embodiments, a condenser is provided inside the housing 200. The condenser is used for heat exchange between the refrigerant and the outdoor air. Its main body is composed of multiple sets of parallel copper (or aluminum) heat exchange tubes and dense metal heat dissipation fins (usually aluminum fins). The heat exchange tubes are inserted into and fixed in the preset holes of the fins to form a heat exchange matrix integrating tubes and fins. At the same time, the condenser is fixed inside the outdoor unit housing by a bracket, and an air circulation channel is reserved on the side corresponding to the cooling fan. Some condensers are also provided with manifolds at the inlet and outlet of the pipes (for collecting / distributing refrigerant) to ensure that the refrigerant can flow evenly through each heat exchange tube, and finally achieve efficient heat exchange between the refrigerant and the outdoor air.

[0049] In some embodiments, the housing 200 is provided with an air inlet and an air outlet 210, and an air duct is provided between the air inlet and the air outlet 210.

[0050] In some embodiments, a protective grille 220 is provided at the air outlet 210. The protective grille 220 is used to prevent foreign objects from entering the housing 200 and affecting the normal operation of the outdoor unit of the air conditioner, or to prevent animals from accidentally entering the outdoor unit of the air conditioner and avoiding safety hazards.

[0051] In some embodiments, the outdoor unit of the air conditioner includes an axial fan 100, which is disposed in the air duct and on the side of the air duct near the air outlet 210; the axial fan 100 is used to drive airflow from the air inlet into the air duct and then out from the air outlet 210.

[0052] In some embodiments, the axial fan 100 includes a hub 120 and multiple blades 110. The multiple blades 110 are disposed on the outer peripheral wall of the hub 120 and are spaced apart along the circumference of the hub 120. The multiple blades 110 are evenly distributed in a 360° circumference.

[0053] In some embodiments, the number of blades 110 may be 3, 5 or 7.

[0054] Preferably, the number of blades 110 can be 5. The accompanying drawings of this application use 5 blades 100 as an example for illustration, but this does not mean that the number of blades 110 can only be 5.

[0055] In some embodiments, the outdoor unit of the air conditioner includes a drive motor, which is mounted inside the housing 200 via a bracket. The output shaft of the drive motor is connected to the hub 120 of the axial fan 100, and the drive motor is used to drive the axial fan 100 to rotate.

[0056] In some embodiments, a guide shroud is provided inside the housing 200, and the guide shroud is sleeved on the outer periphery of the axial fan 100; the drive motor drives the axial fan 100 to rotate, the axial fan 100 drives the airflow, and the airflow is discharged from the air outlet 210 after being rectified by the guide shroud.

[0057] In some embodiments, the blade 110 has a pressure surface 111, a suction surface 112, a leading edge 113, a trailing edge 114, a blade root 116, and a blade tip 115. The pressure surface 111 refers to the side of the blade 110 that actively propels air forward during rotation. Its surface morphology (designed in conjunction with the working angle and forward bend angle) directly determines the magnitude of the thrust on the airflow. Through its positive interaction with the airflow, it converts rotational kinetic energy into propulsive kinetic energy, making it the core force-generating surface for the fan to achieve airflow output. The suction surface 112, as the side of the blade 110 facing away from the direction of airflow thrust and following the airflow, forms a relatively low-pressure area in the suction surface 112 region while the pressure surface 111 propels the airflow. This low-pressure traction guides the airflow smoothly through the blade 110 channel, reducing airflow pressure. Airflow separation and vortex generation help improve air delivery efficiency; the leading edge 113 refers to the edge that first contacts the airflow when the blade 110 rotates, and its distribution curve determines the initial angle at which the airflow enters the blade 110 channel. The optimized shape of the leading edge 113 can reduce the airflow impact intensity and reduce aerodynamic noise; the trailing edge 114 refers to the edge at which the airflow finally leaves the blade 110 when the blade 110 rotates; the blade root 116 is the part where the blade 110 connects to the hub 120, and is the structural support foundation of the blade 110; the blade tip 115 is the top part of the blade 110 away from the hub 120, which is a high-incidence area of ​​vibration and vortex.

[0058] The axis of hub 120 is its central axis, which is also the rotation axis of axial fan 100. The plane passing through the central axis is called the meridional plane, and the plane perpendicular to the central axis is called the circumferential section. Specifically, the meridional plane refers to the plane defined by a cylindrical coordinate system with a point on the central axis as the origin, the radial direction of hub 120 as the y-axis, and the direction of the central axis as the z-axis; the z-axis is the vertical direction of the outdoor unit of the air conditioner, and the y-axis is the horizontal direction of the outdoor unit of the air conditioner.

[0059] In some embodiments, the leaf blade 110 has a plurality of feature surfaces from the leaf root 116 to the leaf tip 115.

[0060] The characteristic surface of blade 110 refers to a cylindrical surface with radius r that is coaxial with the fan's rotation axis and intersects with blade 110 to obtain a cross section. Furthermore, on this characteristic cross section, the point that first encounters the incoming flow along the flow direction (rotation direction) is called the leading edge point at that radius, and the leading edge point is located on the leading edge 113; on the same characteristic cross section, the point that last leaves the blade along the flow direction is called the trailing edge point at that radius, and the trailing edge point is located on the trailing edge 114.

[0061] In some embodiments, such as Figure 9 As shown, the axial coordinate values ​​of the leading edge points corresponding to each feature surface on the blade 110 first decrease, then increase, and then decrease again as the radius of the axial fan 100 increases.

[0062] In some embodiments, such as Figure 10 As shown, the axial coordinate values ​​of the trailing edge points corresponding to each feature surface on the blade 110 first increase and then decrease as the radius of the axial fan 100 increases.

[0063] In some embodiments, such as Figure 11 As shown, the working angles corresponding to each feature surface on the blade 110 first increase and then decrease as the radius of the axial fan 100 increases.

[0064] In some embodiments, such as Figure 12 As shown, the forward bending angles corresponding to each characteristic surface on the blade 110 gradually decrease as the radius of the axial fan 100 increases.

[0065] In some embodiments, such as Figure 9 As shown, from the leaf root 116 to the leaf tip 115, the leading edge distribution curve of the leaf blade 110 is first concave and then approaches a straight line; the leading edge distribution curve of the leaf blade 110 exhibits a formulaic change, satisfying the following formula:

[0066] Where r is the radius corresponding to the feature surface of blade 110; z is the axial coordinate value of the leading edge point on the feature surface along the hub 120, i.e., the z value; E is scientific notation; the same applies throughout the text and will not be repeated here.

[0067] The leading edge distribution curve is formed by the projection of the leading edge 113 on the meridional plane of the blade 110. The points on the leading edge distribution curve are composed of the corresponding radius r of each feature surface of the blade 110 and the axial coordinate of the leading edge point on the feature surface along the axis of the hub 120. The leading edge distribution curve can control the z-axis height of the blade 110.

[0068] In some embodiments, such as Figure 10 As shown, the trailing edge distribution curve of blade 110 is divided into a first curve and a second curve.

[0069] In some embodiments, the first curve segment is a concave-convex curve, and the first curve segment exhibits a formulaic change, satisfying the following formula:

[0070] In some embodiments, the second curve segment is approximately a straight line, and the second curve segment exhibits a formulaic change, satisfying the following formula:

[0071] The trailing edge distribution curve is formed by the projection of the trailing edge 114 on the meridional plane of the blade 110. The points on the trailing edge distribution curve are composed of the radius r corresponding to each feature surface and the axial coordinate of the trailing edge point on the feature surface along the axis of the hub 120. The trailing edge distribution curve can control the z-axis height of the blade 110.

[0072] In some embodiments, such as Figure 11 As shown, the working angle distribution curve of blade 110 is divided into the third curve and the fourth curve.

[0073] In some embodiments, the third curve extends from the leaf root 116 to the middle of the leaf, and the third curve is a convex line. The third curve exhibits a formulaic change, satisfying the following formula:

[0074] In some embodiments, the fourth curve extends from the middle of the leaf to the leaf tip at 115°. The fourth curve is a concave line and exhibits a formulaic change, satisfying the following formula:

[0075] Wherein, the working angle g is the angle between the projection of the leading and trailing edge points of each characteristic surface of the blade 110 onto the circumferential section and the line connecting the center point of the circumferential section. The circumferential section is perpendicular to the central axis of the hub 120, and the center point is the projection of the central axis of the hub 120 onto the circumferential section. Specifically, the angle between the projection points of the leading and trailing edge points of the blade 110 onto the circumferential section (i.e., the xoy plane) and the center point is the working angle. The x-axis is a straight line extending radially along the hub 120 and perpendicular to the y-axis and z-axis respectively. The x-axis is the front-rear direction of the outdoor unit of the air conditioner. The curve formed by the working angles g corresponding to different characteristic surfaces is the working angle distribution curve. The points on the working angle distribution curve are composed of the working angle g on each characteristic surface and the radius r of the corresponding characteristic surface. The working angle distribution curve is used to control the circumferential length of the blade 110.

[0076] In some embodiments, such as Figure 12 As shown, the forward bend angle distribution curve of blade 110 is nearly a straight line from the blade root 116 to the blade tip 115 (i.e., 0%~100% Span). The forward bend angle distribution curve exhibits a formulaic change, and the formula satisfies:

[0077] Span refers to the radial spread of the leaf blade, which is the total length from the leaf root to the leaf tip.

[0078] Among them, the angle between the projection of the leading edge point corresponding to each characteristic surface of the blade 110 onto the circumferential section and the line connecting the center point of the circumferential section and the oy axis is the forward bend angle w; the forward bend angles corresponding to different characteristic surfaces constitute the forward bend angle distribution curve, which is composed of the forward bend angle w and the radius r, and can also control the circumferential length of the blade 110.

[0079] In the above embodiments, this application achieves a dual noise reduction effect by adopting an asymmetric odd-numbered blade structure in the axial fan 100: on the one hand, the asymmetric distribution of odd-numbered blades 110 can ensure that the airflow pulse frequencies generated by each blade 110 do not overlap, effectively dispersing the airflow pulse energy and reducing the intensity of low-frequency discrete noise; on the other hand, the trailing edge 114 of the odd-numbered blades 110 will not detach synchronously, avoiding the formation of large-scale vortices with strong coherence, thereby improving the intensity of broadband rotational noise.

[0080] Furthermore, unlike existing technologies that often limit aerodynamic optimization of axial fan blades to isolated adjustments of single or partial curves (e.g., optimizing only the operating angle distribution to increase thrust, or improving the leading edge curve alone to reduce local noise), this approach often leads to mutual constraints between parameters. For example, simply increasing the operating angle may increase thrust, but it can easily cause increased airflow separation on the blade's suction surface, resulting in airflow loss or increased noise. While optimizing the leading edge curve alone can reduce airflow impact noise, it is difficult to coordinate and improve trailing edge vortices or uneven circumferential thrust distribution, ultimately failing to achieve the multiple objectives of noise reduction, increased airflow, and stable power.

[0081] This application overcomes this technical limitation by simultaneously coupling and optimizing the operating angle distribution curve, the forward bend angle distribution curve, and the leading and trailing edge distribution curves on the 110 meridional surface of the blade, enabling the parameters of each curve to work synergistically throughout the entire airflow path. Through holistic optimization, it reduces airflow separation losses on the 110 blade surface and improves airflow propulsion efficiency, ultimately increasing the airflow of the new fan by 5% compared to existing fans, while maintaining the same actual operating power. This perfectly achieves the triple technical goals of noise reduction, increased airflow, and stable power.

[0082] In some embodiments, the operating angle of the blade 110 is 53°. At this angle, the circumferential length of the blade 110 is at the basic threshold for adapting to airflow capture, which can ensure that the blade 110 has sufficient airflow contact area on each feature surface and avoid insufficient airflow capture due to the circumferential length being too short.

[0083] In some embodiments, the operating angle of the blade 110 is 63°. At this angle, the circumferential length of the blade 110 is further extended, which can enhance the driving ability of high-speed airflow, enabling the fan to output a larger air volume at the same speed, thus meeting the high heat exchange requirements of small air conditioner outdoor units in high-temperature environments.

[0084] In some embodiments, the working angle of the blade 110 ranges from 53° to 63°.

[0085] In the above embodiments, this application limits the working angle of the blade 110 to the range of 53°~63°, which is the range of optimal aerodynamic performance. This ensures that the local length of each feature surface in the circumferential direction is sufficient to capture the airflow, avoiding the situation where the circumferential length of the cross section is too short when the working angle is <53°, resulting in a reduction in the amount of airflow captured and the air volume being insufficient to meet the heat exchange requirements of a small air conditioner. At the same time, it also prevents the circumferential length from being too long when the working angle is >63°, which would intensify the impact of the airflow on the pressure surface 111, increase the noise of vortex shedding, and reduce efficiency and power. Thus, a precise balance between circumferential length, airflow driving efficiency, and noise control is achieved within the range of 53°~63°, laying the foundation for key parameters for the efficient and low-noise operation of the fan.

[0086] In some embodiments, the forward bend angle of the blade 110 is 0°. At this time, the leading edge 113 of the blade 110 has no circumferential deflection and its shape is closer to the traditional straight blade 110 design. The airflow can smoothly enter the flow channel along the radial direction of the blade 110 without additional adjustment of the flow direction. This can minimize the local airflow disturbance that may be caused by the deflection of the leading edge 113. It is especially suitable for small air conditioning outdoor units with compact air duct structure and high requirements for airflow stability.

[0087] In some embodiments, the forward bend angle of the blade 110 is 45°. At this angle, the leading edge 113 of the blade 110 deflects circumferentially toward the direction of the incoming airflow, which can more actively guide the airflow into the flow channel of the blade 110, reduce the impact angle between the airflow and the leading edge 113, and make the flow trajectory of the airflow in the circumferential cross section xoy more closely match the shape of the blade 110. The 45° forward bend angle can effectively weaken the impact intensity of the high-speed airflow on the leading edge 113, reduce the pressure pulsation of the leading edge 113, and at the same time enhance the traction effect on the airflow, thereby improving the air delivery efficiency of the blade 110 at high speeds.

[0088] In some embodiments, the forward bending angle of the blade 110 ranges from 0° to 45°.

[0089] In the above embodiments, this application limits the forward bending angle of the blade 110 to 0°~45° to avoid the leading edge 113 bending backward when the current bending angle is less than 0°, requiring the airflow to enter the flow channel around the trailing edge 114, which increases local acceleration loss, reduces the effective flow area, and decreases the air supply efficiency; it also avoids the leading edge 113 deflecting too much in the circumferential direction when the current bending angle is greater than 45°, which causes the angle between the incoming flow and the leading edge 113 to increase sharply, enhances the pressure pulsation of the leading edge 113, increases the impact noise, and makes the suction surface 112 prone to local separation, exacerbating vortex shedding; therefore, within the range of 0°~45°, acceleration loss and impact noise can be suppressed simultaneously, and high efficiency and low noise can be achieved in conjunction with the operating angle.

[0090] In some embodiments, the trailing edge distribution curve satisfies: Along the radial direction of the blade 110, the coverage area of ​​the first curve starts from the blade root 116 of the blade 110 and extends to a position where the radial length reaches 63% of the total length of the blade 110, i.e., 0%~63% Span. Along the radial direction of blade 110, the coverage area of ​​the second curve starts from a position where the radial length is 63% of the total length of blade 110 and extends to the tip 115 of blade 110; that is, 63% Span ~ 100% Span.

[0091] In the above embodiment, this application divides the trailing edge distribution curve into two segments along the radial direction of the blade 110. The first segment covers the region from the blade root 116 to 63% of the total length of the blade 110, and the second segment covers the region from 63% of the total length to the blade tip 115. This segmented design can perform differentiated optimization for the z-coordinate of different radial positions of the blade 110. The z-coordinate of the blade root 116 region is adjusted by the first segment curve, increasing the flow cross section at the trailing edge 114 outlet and suppressing the tendency of airflow backflow at the root. The z-coordinate of the trailing edge 114 region is kept smooth by the second segment curve, which is close to a straight line, reducing the intensity of vortex shedding at the trailing edge 114. This ultimately solves the problem that the existing single trailing edge 114 curve cannot adapt to the radial airflow differences and causes severe airflow separation, significantly improving the aerodynamic performance of the fan and further reducing broadband rotational noise.

[0092] In some embodiments, the working angle distribution curve satisfies: Along the radial direction of the blade 110, the coverage area of ​​the third curve starts from the leaf root 116 of the blade 110 and extends to a position where the radial length reaches 50% of the total length of the blade 110; that is, 0%~50% Span. Along the radial direction of blade 110, the coverage area of ​​the fourth curve starts from a position where the radial length is 50% of the total length of blade 110 and extends to the tip 115 of blade 110; that is, 50% Span ~ 100% Span.

[0093] In the above embodiment, this application divides the working angle distribution curve into two segments along the radial direction of the blade 110. The third segment covers the area from the blade root 116 to 50% of the total length of the blade 110, and the fourth segment covers the area from 50% of the total length to the blade tip 115. The third segment uses a convex line to make the working angle increase rapidly with the radius, extending the circumferential length and improving the work capacity in the low-speed zone. The fourth segment uses a concave line to make the working angle decrease slowly with the radius, shortening the circumferential length and reducing high-speed impact noise, thereby balancing the efficiency of the blade root 116 and the quietness of the blade tip 115, and achieving high-efficiency and low-noise operation of the entire blade 110.

[0094] In some embodiments, because the blade 110 is most prone to deformation near the trailing edge 114 at high airflow and medium-high speed, and this deformation is periodic, the vibration of the blade 110 will be very severe. This deformation not only affects the airflow but also the low-frequency vibration of the fan. Therefore, several arc-shaped concave ribs are provided on the side of the suction surface 112 near the blade tip 115. The arc-shaped concave ribs refer to grooves that are recessed towards the pressure surface 111 on the suction surface 112.

[0095] In the above embodiments, this application provides several arc-shaped concave ribs on the side of the suction surface 112 of the blade 110 near the blade tip 115. On the one hand, it can locally strengthen the area of ​​the most intense vibration, the trailing edge 114 of the blade tip 115, effectively weakening the periodic vibration deformation of the fan blade 110 at medium and high speeds, and reducing the low-frequency transmission noise formed by the vibration transmitted to the air conditioner casing 200 through the hub 120 and the motor. On the other hand, the arc-shaped concave ribs can divide the airflow at the blade tip 115, destroy the generation of large-scale coherent vortices, further suppress the vortex intensity at the trailing edge 114 of the fan blade tip 115, reduce broadband rotational noise, and ultimately achieve the dual effect of vibration reduction and vortex suppression and noise reduction. At the same time, it improves the structural reliability of the blade 110 and avoids fatigue damage caused by long-term vibration.

[0096] In some embodiments, the spacing between two adjacent arc-shaped concave ribs is 10 mm to 20 mm.

[0097] Preferably, the spacing between two adjacent arc-shaped concave ribs is 10 mm.

[0098] In the above embodiments, this application limits the spacing between adjacent arc-shaped concave ribs to a range of 10mm to 20mm. This avoids the formation of airflow obstruction zones due to dense concave ribs caused by excessively small spacing (less than 10mm), which would hinder airflow and cause air volume loss. At the same time, it avoids the defects of insufficient concave rib coverage, ineffective reinforcement of the blade tip 115 vibration area, and limited vibration reduction effect caused by excessively large spacing (greater than 20mm). Ultimately, it balances the structural reinforcement effect with the smoothness of airflow, ensuring that the fan achieves vibration reduction while the air volume is not affected, further consolidating the performance advantages of large air volume and low noise.

[0099] In some embodiments, the depth of the arc-shaped concave rib is 1.5 mm to 3 mm.

[0100] Preferably, the depth of the arc-shaped concave rib is 1.5 mm.

[0101] In the above embodiments, the depth of the arc-shaped concave rib is limited to the range of 1.5mm to 3mm to avoid the blade 110 being too thin in the local Z-axis direction at the concave rib due to excessive depth (greater than 3mm), which would reduce the strength at the concave rib. At the same time, it avoids the problem of insufficient structural reinforcement and vibration suppression failure due to insufficient depth (less than 1.5mm).

[0102] In some embodiments, in two adjacent arcuate concave ribs, the circumferential length of the arcuate concave rib closer to the leaf root 116 is half the circumferential length of the arcuate concave rib closer to the leaf tip 115.

[0103] Among them, the circumferential length refers to the arc length of the arc-shaped concave rib from the front edge 113 to the rear edge 114.

[0104] In the above embodiments, this application specifies that the circumferential length of the concave rib on the side closer to the blade root 116 is half that on the side closer to the blade tip 115. This differentiated length design can adapt to the vibration intensity and circumferential length characteristics of different radial positions of the blade 110. The vibration is strong and the circumferential length is long in the blade tip 115 area, requiring a longer concave rib to achieve sufficient vibration reduction. The vibration is weak and the circumferential length is short in the area closer to the blade root 116 area. The short concave rib can meet the basic vibration reduction requirements and avoid obstructing airflow and affecting the air supply efficiency in the blade root 116 area due to excessively long concave ribs. Ultimately, differentiated vibration reduction is achieved, weakening the vibration at the blade tip 115 of the blade 110, while avoiding noise or air volume loss caused by additional airflow interference, so that the vibration reduction effect and air supply efficiency do not conflict.

[0105] In some embodiments, the number of arc-shaped concave ribs is 3 to 5.

[0106] In the above embodiments, this application limits the number of arc-shaped concave ribs to a range of 3 to 5. This number design can balance the vibration reduction effect, processing feasibility and cost control; avoid the problem that the strength enhancement is limited and the vibration reduction effect is poor due to too few ribs (less than 3 ribs); in addition, it also avoids the defects of increased mold processing complexity and processing cost caused by too many concave ribs (more than 5 ribs); at the same time, it avoids the problem of dense concave ribs dividing the airflow and causing airflow turbulence.

[0107] Preferably, the number of arc-shaped concave ribs is 3.

[0108] Furthermore, from the leaf tip 115 to the leaf root 116, these three arc-shaped concave ribs are named sequentially as the first arc-shaped concave rib 112a, the second arc-shaped concave rib 112b, and the third arc-shaped concave rib 112c; the first arc-shaped concave rib 112a is located between 100% and 95% span, and extends from the trailing edge 114 to the front edge 113, covering the entire area between the front edge 113 and the trailing edge 114; the second arc-shaped concave rib 112b is located between 95% span... Between 90% and 90% span, the second arc-shaped concave rib 112b extends from the rear edge 114 to the front edge 113, and the circumferential length of the second arc-shaped concave rib 112b is half the circumferential length of the first arc-shaped concave rib 112a; the third arc-shaped concave rib 112c is located between 90% and 85% span, and the third arc-shaped concave rib 112c extends from the rear edge 114 to the front edge 113, and the circumferential length of the third arc-shaped concave rib 112c is half the circumferential length of the second arc-shaped concave rib 112b.

[0109] To reduce the impact of vibration deformation of the trailing edge 114 of the fan blade tip 115 on the structural strength of the blade 110, this patent uses three grooves of different lengths to locally strengthen the structure near the trailing edge 114 of the blade 110. The structural stress of the strengthened blade 110 can be reduced by 6 MPa.

[0110] In some embodiments, a plurality of reinforcing ribs 112d are provided on the suction surface 112 of the blade 110, and the reinforcing ribs 112d are disposed between the arc-shaped ribs and the blade root 116. The reinforcing ribs 112d are used to increase the strength of the blade 110 and reduce its weight.

[0111] In some embodiments, there are two reinforcing ribs 112d on each blade 110.

[0112] Specifically, through the above solution, this application can achieve the following technical effects: 1) Comparison of individual fan performance The axial flow fan 100 disclosed in this application was compared with a mass-produced fan in terms of individual fan characteristics, such as static pressure coefficient, static pressure efficiency, and specific noise performance. Figures 13-15 As shown, under high air volume (flow coefficient greater than 0.3), the static pressure coefficient, efficiency, and specific noise of the axial fan 100 disclosed in this application are all superior to those of mass-produced fans.

[0113] 2) Overall performance comparison To further verify the performance of the axial fan 100 in the whole unit, mass-produced fans and the axial fan 100 disclosed in this application were placed in the top-outlet outdoor unit to test their air volume, noise, and power. The results are shown in Table 1.

[0114] As shown in Table 1, the axial fan 100 disclosed in this application has a 5% higher air volume, a 59 rpm lower speed, a 3% lower power, a 0.9 dB(A) lower OA noise, a 3 dB(A) lower rotational noise, and a 10 dB(A) lower low-frequency transmission noise compared to existing four-blade mass-produced fans.

[0115] Table 1 shows a performance comparison of the fan in the overall system:

[0116] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. An outdoor unit for an air conditioner, characterized in that, include: The outer casing has an air inlet and an air outlet, and an air duct is provided between the air inlet and the air outlet; An axial flow fan, disposed within the air duct, is used to drive airflow from the air inlet into the air duct and then out through the air outlet; the axial flow fan includes: Wheel hub; Multiple blades are disposed on the outer peripheral wall of the hub and spaced apart along the circumference of the hub; each blade has a leading edge, a trailing edge, a root, and a tip; from the root to the tip, each blade has multiple feature surfaces; The axial coordinate values ​​of the leading edge points corresponding to each feature surface on the blade first decrease, then increase, and then decrease again as the radius of the axial fan increases. The axial coordinate values ​​of the trailing edge points corresponding to each feature surface on the blade first increase and then decrease as the radius of the axial fan increases; The working angles corresponding to each feature surface on the blades first increase and then decrease as the radius of the axial fan increases; The forward bend angle corresponding to each feature surface on the blade gradually decreases as the radius of the axial fan increases.

2. An outdoor unit for an air conditioner according to claim 1, characterized in that, The working angle of the blade is in the range of 53° to 63°.

3. An outdoor unit for an air conditioner according to claim 2, characterized in that, The forward bending angle of the blade is in the range of 0° to 45°.

4. An outdoor unit for an air conditioner according to any one of claims 1 to 3, characterized in that, The number of blades can be 3, 5 or 7; The leading edge distribution curve of the blade exhibits a formulaic change, satisfying the following formula: Where r is the radius corresponding to the feature surface of the blade; z is the axial coordinate value of the leading edge point on the feature surface along the hub axis; The trailing edge distribution curve of the blade is divided into a first segment and a second segment; the first segment exhibits a formulaic change, satisfying the following formula: The second curve exhibits a formulaic change, satisfying the following formula: Where r is the radius corresponding to the feature surface of the blade; z is the axial coordinate value of the leading edge point on the feature surface along the hub axis; The working angle distribution curve of the blade is divided into a third curve and a fourth curve; the third curve exhibits a formulaic change, and the formula satisfies: The fourth curve segment exhibits a formulaic change, and the formula satisfies: Where r is the radius corresponding to the feature surface of the blade; z is the axial coordinate value of the leading edge point on the feature surface along the hub axis; The forward bend angle distribution curve of the blade exhibits a formulaic change, satisfying the following formula: Where r is the radius corresponding to the feature surface of the blade; z is the axial coordinate value of the leading edge point on the feature surface along the hub axis.

5. An outdoor unit for an air conditioner according to claim 4, characterized in that, The trailing edge distribution curve satisfies: Along the radial direction of the blade, the range of the radius corresponding to the point on the first curve segment starts from the root of the blade and extends to a position where the radial length reaches 63% of the total length of the blade; Along the radial direction of the blade, the radius corresponding to the point on the second curve ranges from a position where the radial length is 63% of the total length of the blade to the tip of the blade.

6. An outdoor unit for an air conditioner according to claim 4, characterized in that, The working angle distribution curve satisfies: Along the radial direction of the blade, the range of the radius corresponding to the point on the third curve starts from the root of the blade and extends to the position where the radial length reaches 50% of the total length of the blade; Along the radial direction of the blade, the radius corresponding to the point on the fourth curve ranges from a position where the radial length is 50% of the total length of the blade, all the way to the tip of the blade.

7. An outdoor unit for an air conditioner according to claim 1, characterized in that, The blade has a suction surface; The suction surface has several arc-shaped concave ribs on the side near the blade tip.

8. An outdoor unit for an air conditioner according to claim 7, characterized in that, The spacing between two adjacent arc-shaped concave ribs is 10 mm to 20 mm, and the depth of the arc-shaped concave ribs is 1.5 mm to 3 mm.

9. An outdoor unit for an air conditioner according to claim 8, characterized in that, In two adjacent arc-shaped concave ribs, the circumferential length of the arc-shaped concave rib closer to the leaf root is half the circumferential length of the arc-shaped concave rib closer to the leaf tip.

10. An outdoor unit for an air conditioner according to any one of claims 7 to 9, characterized in that, The number of the arc-shaped concave ribs is 3 to 5.

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