Axial flow fan and air conditioner

Abstract

An axial flow fan and an air conditioner. The axial flow fan (100) comprises: a hub (10), and a plurality of blades (20) connected to the hub (10), wherein each blade (20) comprises a first blade (121) and a second blade (122) connected in series, the leading edge of the first blade (121) forms the leading edge of the blade (20), the trailing edge of the second blade (122) forms the trailing edge of the blade (20), and the trailing edge end of the first blade (121) is spaced apart from the trailing edge end of the second blade (122). According to the axial flow fan, the fan efficiency is improved.

Description

Axial fan and air conditioner

[0001] This application claims priority to Chinese Patent Application No. 202420744894.4, filed on April 11, 2024, Chinese Patent Application No. 202410671448.X, filed on May 28, 2024, and Chinese Patent Application No. 202410671053.X, filed on May 28, 2024, the contents of which are incorporated herein by reference in their entirety. TECHNICAL FIELD

[0002] The present application relates to the fan technical field, and particularly relates to an axial fan and an air conditioner. BACKGROUND

[0003] The axial fan generally has a cylindrical hub, and a plurality of blades distributed on the outer periphery of the hub. When the hub is driven to rotate, the blades rotate with the hub, thereby pushing the airflow to flow.

[0004] However, the performance of the current axial fan is limited, and the fan efficiency is low. SUMMARY

[0005] Some embodiments of the present application provide an axial fan and an air conditioner, which improve the fan efficiency by improving the blade arrangement of the axial fan.

[0006] In one aspect of the present application, an axial fan is provided, comprising: a hub configured to be driven to rotate about a central axis; and a plurality of blades connected to the hub, the plurality of blades being uniformly distributed along the circumferential direction of the hub, the plurality of blades comprising a first blade and a second blade in series, a leading edge of the first blade forming a leading edge of the plurality of blades, and a trailing edge of the second blade forming a trailing edge of the plurality of blades; and wherein a trailing edge end of the first blade is spaced apart from a trailing edge end of the second blade.

[0007] In another aspect of the present application, an air conditioner is provided, comprising: a housing; a refrigerant circuit having a condenser and an evaporator; and an axial fan disposed in the housing and configured to blow air to at least one of the condenser and the evaporator.

[0008] Some embodiments of the present application split one blade of the axial fan into a first blade and a second blade spaced apart at the head and tail, the first blade and the second blade are arranged in series, and there is a gap between them. When the gas passes through the surface of the first blade, a certain thickness of the boundary layer is generated. When the gas passes through the surface of the second blade, the boundary layer is redistributed. This is conducive to reducing the aerodynamic loss of the fan, thereby improving the working performance and improving the fan efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0009] FIG. 1 shows a perspective view of an air conditioner from a front view according to some embodiments;

[0010] FIG. 2 illustrates a perspective view of an air conditioner from a rear view angle according to some embodiments;

[0011] FIG. 3 illustrates an internal configuration diagram 1 of an air conditioner according to some embodiments;

[0012] FIG. 4 illustrates an internal configuration diagram 2 of an air conditioner according to some embodiments;

[0013] FIG. 5 illustrates a front view of an axial fan according to some embodiments;

[0014] FIG. 6 illustrates a side view of an axial fan according to some embodiments;

[0015] FIG. 7 illustrates a blade profile cross-sectional view of an axial fan according to some embodiments;

[0016] FIG. 8 illustrates a graph of a relationship between a radius and a pitch of tandem blades of an axial fan according to some embodiments;

[0017] FIG. 9 illustrates a front view of a blade of an axial fan according to some embodiments;

[0018] FIG. 10 illustrates an n curve graph of an axial fan according to some embodiments;

[0019] FIG. 11 illustrates a blade profile cross-sectional view of an axial fan according to some embodiments;

[0020] FIG. 12 illustrates an outer rim β angle curve graph of an axial fan according to some embodiments;

[0021] FIG. 13 illustrates static pressure clouds of an axial fan in a conventional technology before optimization and an axial fan according to some embodiments;

[0022] FIG. 14 illustrates an overall air field cloud of an air conditioner in a conventional technology before optimization and an air conditioner according to some embodiments;

[0023] FIG. 15 illustrates a perspective view of an axial fan according to other embodiments;

[0024] FIG. 16 illustrates a front view of an axial fan according to other embodiments;

[0025] FIG. 17 illustrates static pressure clouds of an axial fan in a conventional technology before optimization and an axial fan according to other embodiments;

[0026] FIG. 18 illustrates an overall air field cloud of an air conditioner in a conventional technology before optimization and an air conditioner according to other embodiments;

[0027] FIG. 19 illustrates an exploded view of an axial fan according to other embodiments;

[0028] FIG. 20 illustrates a side view of an axial fan according to further embodiments;

[0029] FIG. 21 illustrates a perspective view of an axial fan according to further embodiments;

[0030] FIG. 22 illustrates a side view of another perspective of an axial fan according to further embodiments;

[0031] FIG. 23 illustrates a partial schematic view of an axial fan according to further embodiments;

[0032] FIG. 24 illustrates a blade profile cross-sectional view in the direction of X-X in FIG. 23;

[0033] FIG. 25 illustrates a flap height profile graph of a blade according to further embodiments;

[0034] FIG. 26 illustrates a fan surface turbulent energy map of a conventional axial fan before optimization and an axial fan of the present application;

[0035] FIG. 27 illustrates a static pressure cloud map of a fan surface of a conventional axial fan before optimization and an axial fan of the present application.

[0036] Embodiments of the present application

[0037] For the purpose of the present application and embodiments, the following will describe the exemplary embodiments of the present application clearly and completely with reference to the accompanying drawings of the exemplary embodiments of the present application. It is obvious that the described exemplary embodiments are only some of the embodiments of the present application, not all of the embodiments.

[0038] In the description of the present application, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0039] The terms "first", "second", are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features referred to. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise stated, the meaning of "a plurality of" is two or more.

[0040] In the description of the present application, it should be noted that unless specifically stated and limited otherwise, the terms "mounting", "connected", "connection" should be construed broadly, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0041] [air conditioner]

[0042] The air conditioner in the present application performs a refrigeration or heating cycle of the air conditioner by using a compressor, a condenser, an expansion valve and an evaporator. The refrigeration or heating cycle includes a series of processes involving compression, condensation, expansion and evaporation, and the purpose of air temperature adjustment is achieved by heat exchange with air through a heat exchanger.

[0043] The compressor compresses the refrigerant gas in a low-temperature and low-pressure state and discharges the compressed refrigerant gas. The discharged refrigerant gas flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, and heat is released to the surrounding environment through the condensation process.

[0044] The expansion valve expands the liquid-phase refrigerant in a high-temperature and high-pressure state condensed in the condenser into a low-pressure and low-temperature liquid-phase refrigerant. The evaporator evaporates the refrigerant expanded in the expansion valve and returns the refrigerant gas in a low-temperature and low-pressure state to the compressor. The evaporator can achieve a refrigeration effect by exchanging heat with an air flow to be cooled using the latent heat of evaporation of the refrigerant. Throughout the cycle, the air conditioner can adjust the temperature of the indoor space.

[0045] The outdoor unit of the air conditioner refers to the part of the refrigeration cycle including the compressor and the outdoor heat exchanger, the indoor unit of the air conditioner includes the indoor heat exchanger, and the expansion valve can be provided in the indoor unit or the outdoor unit.

[0046] The indoor heat exchanger and the outdoor heat exchanger are used as a condenser or an evaporator. When the indoor heat exchanger is used as a condenser, the air conditioner is used as a heater in a heating mode, and when the indoor heat exchanger is used as an evaporator, the air conditioner is used as a cooler in a cooling mode.

[0047] [Outdoor unit]

[0048] Referring to FIG. 1, the outdoor unit includes a housing 10 constituting the overall appearance of the outdoor unit. The housing 10 can be in the shape of a rectangular box.

[0049] Referring to FIGS. 2 and 3, the housing 10 includes a front plate 11 constituting a front surface of the housing 10, a rear plate 12 constituting a back surface of the housing 10, a top plate 13 constituting an upper surface of the housing 10, a bottom plate 14 constituting a lower surface of the housing 10, and a left side plate 15 and a right side plate 16 constituting a pair of side surfaces of the housing 10.

[0050] An air inlet is formed in the left side plate 15 and the rear plate 12 of the housing 10 for drawing air from the outside. An opening is provided in the front plate 11 of the housing 10, and a grill plate 17 is installed in the opening. Holes formed in the grill plate 17 constitute an air outlet for blowing air from the inside of the housing 10 to the outside. The grill plate 17 prevents external objects from contacting the axial fan 100 inside the housing 10.

[0051] As shown in FIG. 4, the outdoor unit includes a motor 20 for driving the axial fan 100 to rotate. In some embodiments, the motor 20 is installed on a motor bracket 21. The motor bracket 21 is disposed between the motor 20 and the heat exchanger 30.

[0052] In some embodiments, as shown in FIG. 5, the outdoor unit includes the axial fan 100, which rotates about a rotation axis RA, so that air enters the housing 10 from the air inlet of the housing 10 and is blown out of the housing 10 by the air outlet.

[0053] The outdoor unit includes a heat exchanger 30 connected in the housing 10 corresponding to the air inlet. The heat exchanger 30 is located on the suction side of the axial fan 100 and has a plurality of fins arranged in parallel in a stacked manner, and a heat transfer tube penetrating through each fin in the stacking direction. The heat transfer tube is connected in a refrigerant circuit, so that refrigerant flows through the heat transfer tube. The heat exchanger 30 functions as an evaporator when the air conditioner is in heating operation, and functions as a condenser when the air conditioner is in cooling operation.

[0054] [AXIAL FAN 100]

[0055] The axial fan 100 of the present application can be used in an outdoor unit of an air conditioner. The axial fan 100 rotates to form an air flow at the outdoor unit.

[0056] Referring to FIGS. 5 and 6, the axial fan 100 includes a hub 110 for connection with a rotation axis of the motor 20. The hub 110 can be in a cylindrical shape.

[0057] The axial fan 100 includes a plurality of blades 120 connected to a circumferential surface of the hub 110. The blades 120 extend radially outward from the circumferential surface of the hub 110, and the plurality of blades 120 are arranged in a radial pattern with respect to the hub 110.

[0058] A plurality of blades 120 are provided at regular intervals in the circumferential direction. An example is shown in which three blades 120 are provided, but the number of blades 120 is not limited to three.

[0059] In some embodiments, the blade 120 has a leading edge 123, a trailing edge 124, an outer edge 125, and an inner edge 126.

[0060] In the blade 120, with the rotational direction RD as a reference, the leading edge 123 is an edge of the advancing side of the blade 120, and the trailing edge 124 is an edge of the retreating side of the blade 120. The leading edge 123 is located forward in the rotational direction RD with respect to the trailing edge 124, and the trailing edge 124 is located rearward in the rotational direction RD with respect to the leading edge 123. The leading edge 123 is located on the upstream side in the direction in which the air flow is generated with respect to the trailing edge 124, and the trailing edge 124 is located on the downstream side in the direction in which the air flow is generated with respect to the leading edge 123.

[0061] The outer edge 125 is an edge of the outer peripheral side of the blade 120. The outer edge 125 connects the outermost end of the leading edge 123 and the outermost end of the trailing edge 124.

[0062] The inner edge 126 is an edge at which the blade 120 is connected to the hub 110. The inner edge 126 connects the innermost end of the leading edge 123 and the innermost end of the trailing edge 124. The inner edge 126 of the blade 120 can be integrally formed with the hub 110.

[0063] In some embodiments, the length of the outer edge 125 is greater than the length of the inner edge 126 in the circumferential direction.

[0064] The blade 120 is formed obliquely with respect to a plane perpendicular to the axis of the hub 110. The blade 120 pushes the air present between the blades 120 with the blade face, accompanying the rotation of the axial flow fan 100, thereby transporting the air.

[0065] A face in which the air is pushed and the pressure rises in the blade face is referred to as a pressure face 127, and a face opposite the pressure face 127 is referred to as a suction face 128. In the blade 120, with the flow direction of the air as a reference, the face on the upstream side of the blade 120 becomes the suction face 128, and the face on the downstream side of the blade 120 becomes the pressure face 127.

[0066] [Series of blades]

[0067] As shown in FIG. 6, the blade 120 includes at least two blades arranged in series, the two series of blades being a first blade 121 and a second blade 122, respectively. The first blade 121 and the second blade 122 have a gap in the rotational direction RD.

[0068] In this case, the leading edge 123 of the blade 120 is the leading edge 123 of the first blade 121, and the trailing edge 124 of the blade 120 is the trailing edge 122 of the second blade 122.

[0069] In the blade 120, the first blade 121 is located at the front side in the rotation direction with respect to the second blade 122, and the second blade 122 is located at the rear side in the rotation direction with respect to the first blade 121.

[0070] In the embodiments provided in the present application, the blade is divided into two: the first blade 121 and the second blade 122, which are arranged in series. When the air passes through the suction surface 128 of the first blade 121, a boundary layer with a certain thickness is generated. When the air continues to pass through the second blade 122, the boundary layer is redistributed, which is conducive to reducing the aerodynamic loss of the axial flow fan 100.

[0071] The face of the cylindrical surface coaxial with the axis of the hub 110 and intersecting the blade 120 is called the blade profile section.

[0072] In some embodiments, the trailing edge end of the first blade 121 is spaced apart from the trailing edge end of the second blade 122.

[0073] In some embodiments, the trailing edge end of the first blade 121 is spaced apart from the trailing edge end of the second blade 122 in the horizontal direction (or radial direction) and the thickness direction (or axial direction) by a predetermined distance.

[0074] For example, referring to FIG. 7, in the blade profile section of the blade 120, the distance between the trailing edge end of the first blade 121 and the leading edge end of the second blade 122 in the direction perpendicular to the axis of the hub 110 (i.e., in the horizontal direction from front to back) is denoted as θ1.

[0075] Alternatively, θ1 can also be referred to as the distance between the trailing edge end of the first blade 121 and the leading edge end of the second blade 122 in the radial direction.

[0076] In some embodiments, the size of θ1 is related to the size of the radius of the circle with the axis of the hub 110 as the center.

[0077] For example, referring to FIG. 8, assuming that the horizontal axis of the θ1 curve is the size of the radius of the circle with the axis of the hub 110 as the center, and the vertical axis is the size of θ1, the relationship between the size of θ1 and the radius is represented as a θ1 curve. The θ1 curve gradually increases in size as the radius increases. That is, from the inner edge 126 side to the outer edge 125 side, the distance θ1 between the first blade 121 and the second blade 122 gradually increases.

[0078] Since the part of the blade close to the inner edge 126 does less work, the corresponding θ1 can be set to be relatively small.

[0079] Since the working area on the blade is mainly concentrated in the area close to the trailing edge and close to the outer edge of the second blade 122, the θ1 of the first blade 121 and the second blade 122 close to the outer edge 125 is large, which is conducive to the boundary layer reshaping of the air flow close to the outer edge 125 part, thereby reducing the aerodynamic loss of the fan.

[0080] According to the embodiments of the present application, for the axial flow fan with an outer diameter of 260mm-410mm, the value of θ1 at the inner edge 126 end is not less than 2mm, and the value of θ1 at the outer edge 125 end is not greater than 12mm. It can be avoided that θ1 is too small or too large to affect the redistribution of the boundary layer on the second blade 122.

[0081] Exemplarily, in the direction of increasing radius, the value of θ1 can gradually increase from 2mm to 12mm.

[0082] In some embodiments, continuing to refer to FIGS. 7 and 8, in the blade profile section of the blade 120, the distance from the trailing edge end of the first blade 121 to the leading edge end of the second blade 122 in the direction parallel to the axis of the hub 110 (i.e. in the thickness direction of the blade) is denoted as θ2.

[0083] The value of θ2 at any radius is constant. That is, the axial distance θ2 between the first blade 121 and the second blade 122 is a constant value.

[0084] According to the embodiments of the present application, for the axial flow fan with a maximum outer diameter of 260mm-410mm, θ2=8-10mm. Exemplarily, θ2=9.3mm. Within this value range, the tandem blade can greatly improve the fan performance.

[0085] In some embodiments, referring to FIG. 9, in the plane perpendicular to the axis of the hub 110, with the center of the hub 110 as the center of the circle, passing through the circle of the blade 120, the arc length of the trailing edge 124 of the second blade 122 to the leading edge 123 of the first blade 121 is L1, the arc length of the first blade 122 is L2, and L2 / L1=n, n=0.4-0.6. That is, the position of the first blade 121 and the second blade 122 in tandem is approximately at the midpoint of the total arc length. In any blade profile section, the arc length of the first blade 121 is approximately equal to the arc length of the second blade 122.

[0086] Exemplarily, from the inner edge 126 side to the outer edge 125 side, n gradually increases, for example, n can gradually increase from 0.4 to 0.6.

[0087] In some embodiments, the relationship between the size of n and the radius of the circle with the center of the hub 110 as the center of the circle is that as the radius increases, the size of n changes in the trend of first increasing, then decreasing, and then increasing.

[0088] Exemplarily, with reference to FIG. 10, assuming that the horizontal axis of the n curve is the radius of a circle with the axis of the hub 100 as the center and the vertical axis is the size of n, the relationship between the size of n and the radius is expressed as the n curve.

[0089] The n curve has a first part and a second part, wherein the first part corresponds to the part with smaller radius of the first blade 121 and the second blade 122, and the length of the horizontal axis of the second part is greater than that of the first part, i.e., the length of the line segment of the second part accounts for a greater proportion of the total length of the n curve than the length of the line segment of the first part accounts for the total length of the n curve. The first part shows a trend of first increasing and then decreasing with the increase of the radius, and the second part shows a trend of gradually increasing with the increase of the radius.

[0090] In some embodiments, continuing to refer to FIG. 9, in the plane perpendicular to the axis of the hub, the total arc length of the circular arc passing through the blade 120 with the axis of the hub as the center is L1, and the ratio of the arc length of any point on the circular arc to L1 is defined as z.

[0091] With reference to FIG. 11, in the profile section of the blade 120, the angle between the imaginary line where the point perpendicular to the axis of the hub 110 and intersecting the edge of the profile section is located and the imaginary line representing the tangent of the point is defined as the β angle.

[0092] The β angle of the trailing edge of the first blade 121 is the same as the β angle of the leading edge of the second blade 122.

[0093] With reference to FIG. 12, the horizontal axis of the outer edge β angle curve is the size of z, and the vertical axis is the size of the β angle. The relationship between the size of the β angle and the size of z is expressed as the outer edge β angle curve.

[0094] The β angles of the first blade 121 and the second blade 122 at the positions close to each other are the same.

[0095] The outer edge β angle curve has two lines, which are the first line LP1 and the second line LP2. According to the trend of the first line LP1, the highest point of the first line LP1 is connected to the second line LP2 by a dashed line DL. The intersection point of the dashed line DL and the second line LP2 is marked as W, which divides the second line LP2 into a line segment corresponding to the front part of the second blade and a line segment corresponding to the rear part of the second blade, wherein the z value of the front part of the second blade is smaller than the z value of the rear part of the second blade.

[0096] The first line LP1, the dashed line DL, and the rear portion of the second blade form an outer edge beta angle curve of the integral blade, while the line segment of the front portion of the second blade in the corresponding tandem blade of the application deviates from the outer edge beta angle curve of the integral blade. In other words, the line segment formed by the size of the beta angle of the second blade 122 and the size of z deviates from the line segment formed by the size of the beta angle of the first blade 121 and the size of z. Alternatively, the line segment formed by the size of the beta angle of the front portion of the second blade 122 and the size of z deviates from the line segment formed by the size of the beta angle of the first blade 121 and the size of z.

[0097] In some embodiments, the beta angle of the leading edge end of the second blade can be slightly changed, and the angle parameters of other portions remain unchanged.

[0098] For example, the portion deviating from the beta angle curve, the smaller the beta angle is, the closer to the leading edge end the z value is. That is, the closer to the leading edge end of the second blade, the more the line segment formed by the size of the beta angle of the second blade 122 and the size of z deviates from the line segment formed by the size of the beta angle of the first blade 121 and the size of z.

[0099] According to the embodiments of the application, the first line LP1 presents a shape of gradually decreasing and then gradually increasing as the value of z of the transverse axis increases. The lowest point of the first line LP1 is close to the leading edge side, at which time the portion close to the leading edge and close to the outer edge on the first blade usually turns outward to the suction surface, thereby reducing the beta angle.

[0100] The second line LP2 presents a shape of gradually increasing as the value of z of the transverse axis increases.

[0101] Referring to FIG. 13, by simulating the axial flow fan of the prior art and the axial flow fan 100 of the application, a fan surface static pressure cloud chart can be obtained, and the black area and the halo around the black area are the areas with strong work. By comparing the working areas of the prior art (before optimization) and the axial flow fan 100 (after optimization), it can be seen that after the axial flow fan 100 of the application adopts the tandem blade, the working ability of the blade 120 close to the hub 110 side is improved, and the overall working area is widened. It can be seen that the axial flow fan 100 of the application can effectively improve the performance of the fan.

[0102] Referring to FIG. 14, by simulating the air conditioner of the prior art and the air conditioner of the application, a whole machine wind field cloud chart can be obtained, and the light white flow field is a high wind speed area. By comparing the wind field trend of the prior art (before optimization) and the air conditioner of the application (after optimization), it can be found that in the air conditioner of the application, after the axial flow fan 100 adopts the tandem blade, the divergence angle (the angle between the two straight lines in the figure) of the air outlet is smaller; and in the air conditioner of the application, the wind speed at a position far from the whole machine (the position circled in the figure) is improved, and the air supply distance is improved.

[0103] The following table is a comparison of the measured results of the axial fan of the conventional technology and the axial fan 100 of the present application:

[0104] As can be seen from the measured results, after the axial fan 100 of the present application adopts the tandem blade, the air volume is increased by 42 CMH, the fan efficiency is increased by 4.5%, and the noise is reduced by 2 dB(A) at the same speed.

[0105] Therefore, after the axial fan 100 of the present application adopts the tandem blade, the fan efficiency can be significantly improved, and the aerodynamic noise of the fan can be reduced without modifying the three-dimensional torque shape of the blade.

[0106] [Splitter blade]

[0107] Referring to FIGS. 15 and 16, the axial fan 100 can include a plurality of splitter blades 130. The plurality of splitter blades 130 are connected with the hub 110 and are arranged one-to-one corresponding to the blades 120.

[0108] The corresponding splitter blades 130 and blades 120 are a group. In each group of splitter blades 130 and blades 120, the splitter blades 130 and the blades 120 are arranged in parallel to the axis direction of the hub 110; the splitter blades 130 are located on the side of the pressure surface 127 of the first blade 121.

[0109] The embodiments provided by the present application add the splitter blades 130 on the basis of the tandem blade, and the splitter blades 130 are arranged on the pressure surface side of the first blade 121, which can further enhance the work capacity of the fan, improve the flow condition of the blade passage between the tandem blades, and improve the efficiency.

[0110] According to the embodiments of the present application, in the plane perpendicular to the axis of the hub 110, most of the area of the splitter blade 130 coincides with the first blade 121, and the splitter blade 130 does not coincide with the second blade 122. Thus, the splitter blade 130 can be ensured to be close to the leading edge of the blade 120, and the air flow entering the leading edge of the blade 120 can be split, thereby improving the work capacity of the fan.

[0111] In some embodiments, the shape of the splitter blade 130 can be the same as that of the second blade 122. The β angle of the splitter blade 130 is consistent with the β angle of the second blade 122. That is, the inclination angle of the splitter blade 130 relative to the hub 110 is the same as that of the second blade 122, which can simplify the structural design of the splitter blade 130.

[0112] Referring to FIG. 17, by simulating the axial flow fan of the prior art and the axial flow fan 100 of the present application, a fan surface static pressure cloud chart can be obtained. By comparing the working area of the axial flow fan of the prior art (before optimization) and the axial flow fan 100 of the present application (after optimization), it can be seen that after the axial flow fan 100 of the present application adopts the tandem blade and the splitter blade, the blade working area is dispersed: from a single blade area to be evenly distributed on the splitter blade 130 and the second blade 122, and the overall working area is widened. It can be seen that the axial flow fan 100 of the present application can improve the performance of the fan after the splitter blade 130 is arranged.

[0113] Referring to FIG. 18, by simulating the air conditioner of the prior art and the air conditioner of the present application, a whole machine wind field cloud chart can be obtained. The light white flow field is a high wind speed area. By comparing the wind field trend of the air conditioner of the prior art (before optimization) and the air conditioner of the present application (after optimization), it can be found that in the air conditioner of the present application, the divergence angle (the angle between the two straight lines in the figure) of the outlet air is smaller after the axial flow fan 100 adopts the tandem blade and the splitter blade. Moreover, in the air conditioner of the present application, the outlet air (the position surrounded in the figure) has higher wind speed and longer air supply distance.

[0114] The following table is the comparison of the measured results of the axial flow fan of the prior art and the axial flow fan 100 of the present application:

[0115] It can be seen from the measured results that after the axial flow fan 100 of the present application adopts the tandem blade and the splitter blade, the air volume of the whole machine is increased by 608 CMH at the same speed, and the fan efficiency is increased by 2.4%, which significantly improves the working capacity and efficiency of the fan. At the same air volume, the fan speed of the present application can be reduced by about 70 rpm, and the fan noise at the same air volume is reduced by 3 dB.

[0116] Therefore, after the axial flow fan 100 of the present application adopts the tandem blade and the splitter blade, the working capacity of the fan can be improved without modifying the three-dimensional torque shape of the blade, and the aerodynamic noise of the fan is reduced.

[0117] For the axial flow fan without the splitter blade, the blades 120 do not overlap in the axial direction, and the mold is respectively out of the mold in the up-down direction when the axial flow fan is made. However, for the axial flow fan with the splitter blade 130, the blades 120 and the splitter blade 130 are stacked in the axial direction, and cannot be normally out of the mold.

[0118] Therefore, in the embodiment of the present application, referring to FIG. 19, the hub 110 includes a first hub portion 111 and a second hub portion 112. The first hub portion 111 and the second hub portion 112 are two-body structures, and are assembled into the hub 110 in a split connection form.

[0119] The blade 120 is connected to the first hub portion 111, and the splitter blade 130 is connected to the second hub portion 112. Since the blade 120 and the splitter blade 130 are respectively arranged on two parts, the first hub portion 111 and the blade 120 can be molded by using one mold, and the second hub portion 112 and the splitter blade 130 can be molded by using another mold.

[0120] In the embodiments provided in the present application, by splitting the axial flow fan 100 into two parts connected in a split manner, the blade 120 and the first hub portion 111 are one part, and the splitter blade 130 and the second hub portion 112 are one part, the normal molding of the two parts can be ensured, and the molding of the axial flow fan 100 can be realized.

[0121] In some embodiments, the circumferential side wall of the first hub portion 111 is provided with a hook groove 115. The circumferential side wall of the second hub portion 112 is provided with a hook portion 116, which can be fitted into the hook groove 115.

[0122] When assembling, the hook portion 116 of the second hub portion 112 is screwed into the hook groove 115 of the first hub portion 111, and through the cooperation of the hook portion 116 and the hook groove 115, the installation and positioning of the first hub portion 111 and the second hub portion 112 can be realized.

[0123] In other embodiments, the positions of the hook portion 116 and the hook groove 115 can be interchanged, that is, the hook portion 116 is arranged on the first hub portion 111, and the hook groove 115 is arranged on the second hub portion 112, and the positioning of the first hub portion 111 and the second hub portion 112 can still be realized through the cooperation of the hook portion 116 and the hook groove 115.

[0124] For convenience of description, it is defined that along the axis direction of the hub 110, the first hub portion 111 is located at the front side of the second hub portion 112, and the second hub portion 112 is located at the rear side of the first hub portion 111.

[0125] The rear end surface of the first hub portion 111 is provided with an opening, and the hook groove 115 is formed by the opening extending obliquely along the circumferential side wall.

[0126] In some embodiments, the outer circumferential portion of the first hub portion 111 is provided with a plurality of first positioning portions 113 arranged at intervals, and the first positioning portion 113 is formed by the circumferential portion of the first hub portion 111 protruding outward. The first positioning portion 113 is provided with a first positioning hole.

[0127] The outer circumferential portion of the second hub portion 112 is provided with a plurality of second positioning portions 114, and the second positioning portion 114 is formed by the circumferential portion of the second hub portion 112 protruding outward. The second positioning portion 114 is provided with a second positioning hole.

[0128] The fasteners such as screws or bolts are sequentially arranged in the first positioning holes and the second positioning holes to fasten and connect the first hub part 111 and the second hub part 112.

[0129] Exemplarily, three first positioning parts 113 are uniformly distributed on the first hub part 111 along the circumference. Three second positioning parts 114 are uniformly distributed on the second hub part 112 along the circumference. The three first positioning parts 113 and the three second positioning parts 114 are one-to-one corresponding and are connected by the fasteners respectively.

[0130] In some embodiments, the first hub part 111 has a first mounting part 117 located at the center of the hub 110, and the first mounting part 117 is connected with the circumferential side wall of the first hub part 111 by a radial wall. The first mounting part 117 is provided with a plurality of third positioning holes.

[0131] The second hub part 112 has a second mounting part 118 located at the center of the hub 110, and the second mounting part 118 is connected with the circumferential side wall of the second hub part 112 by a radial wall. The second mounting part 118 is provided with a plurality of fourth positioning holes.

[0132] The third positioning holes and the fourth positioning holes are arranged one-to-one. During assembly, the fasteners such as screws or bolts are sequentially arranged in the third positioning holes and the fourth positioning holes, so as to fasten and connect the first hub part 111 and the second hub part 112.

[0133] In the present application, the whole blade is divided into two: the first blade 121 and the second blade 122, and the first blade 121 and the second blade 122 are arranged in series. When the air passes through the suction surface 128 of the first blade 121, a boundary layer with a certain thickness is generated. When the air continues to pass through the second blade 122, the boundary layer is redistributed, which is beneficial to reduce the aerodynamic loss of the axial flow fan 100.

[0134] In the present application, after the axial flow fan 100 adopts the tandem blade, the power of the blade 120 near the hub 110 side is improved, and the overall working area is widened. The axial flow fan 100 of the present application can effectively improve the performance of the fan.

[0135] In the present application, after the axial flow fan 100 adopts the tandem blade, compared with the conventional technology, the air volume is increased by 42 CMH at the same speed, the fan efficiency is increased by 4.5%, and the noise is reduced by 2dB(A).

[0136] In the present application, on the basis of the tandem blade, the splitter blade 130 is additionally arranged on the pressure surface side of the first blade 121. The splitter blade 130 can further enhance the power of the fan, improve the flow condition between the tandem blades, and improve the efficiency.

[0137] In the present application, after the tandem blade and the splitter blade are adopted, the working area of the blade is dispersed: from a single blade area to be evenly distributed on the splitter blade 130 and the second blade 122, and the overall working area is widened, improving the performance of the fan.

[0138] In the present application, after the tandem blade and the splitter blade are adopted, the wind volume of the whole machine is increased by 608 CMH at the same speed, and the fan efficiency is increased by 2.4%, significantly improving the working capacity and efficiency of the fan. At the same wind volume, the fan speed of the present application can be reduced by about 70 rpm, and the noise of the fan with the same wind volume is reduced by 3 dB.

[0139] In some embodiments, a flap portion can be provided on the blade of the axial flow fan to improve the performance rate of the fan.

[0140] In an embodiment, the axial flow fan includes a hub rotating around a center axis, a plurality of blades connected to the hub, the blades further having a leading edge, a trailing edge, an inner edge and an outer edge; the blades have upper and lower surfaces, which are respectively positive pressure surfaces and negative pressure surfaces, wherein the trailing edge end of the positive pressure surface of the blade is provided with a flap portion protruding from the positive pressure surface, and the flap portion extends from the inner edge to the outer edge.

[0141] For example, as shown in FIGS. 20 and 21, the axial flow fan 200 according to the embodiment of the present application includes a hub 201 and a plurality of blades 202. The hub 201 is used to be connected with a driving source in the form of an electric motor or the like, so as to be driven to rotate; the blades 202 are connected to the outer circumferential surface of the hub 201.

[0142] Referring specifically to FIG. 20, the hub 201 rotates around the rotation axis A to form airflow flow. The side (rear side) close to the air inlet side is the upstream side, and the side (front side) close to the air outlet side is the downstream side, and the air flow flows from the rear side to the front side at the axial flow fan.

[0143] Referring specifically to FIGS. 21 and 22, the blade 202 includes a leading edge 22a, a trailing edge 22b, an outer edge 23 and an inner edge 24.

[0144] In combination with FIG. 20, the leading edge 22a and the trailing edge 22b are two edges in the radial direction of the blade 202 extending outward from the hub 201; with reference to the rotation direction B of the axial flow fan 200, the leading edge 22a is located on the advancing side relative to the trailing edge 22b; for example, in FIG. 5, viewed from the front side to the rear side, the axial flow fan rotates counterclockwise B relative to the rotation axis A, then, taking one blade 202 as the research object, the leading edge 22a is formed on the advancing side of the rotation direction B, that is, the leading edge 22a is located in front of the trailing edge 22b in the rotation direction B. The trailing edge 22b is formed on the rear side of the rotation direction B, that is, the trailing edge 22b is located behind the leading edge 22a in the rotation direction B.

[0145] The outer edge 23 is an edge of the blade 202 that is the outermost edge in the circumferential direction. The outer edge 23 is connected between the outermost circumferential end of the leading edge 22a and the outermost circumferential end of the trailing edge 22b. The outer edge 23 extends obliquely with respect to the rotation axis A. The inner edge 24 is an edge of the blade 202 that is connected to the hub 201. The inner edge 24 is connected between the innermost circumferential end of the leading edge 22a and the innermost circumferential end of the trailing edge 22b. The inner edge 24 extends obliquely with respect to the rotation axis A.

[0146] The blade 202 pushes the gas present between the blades 202 with the blade surface to transport the fluid as the axial fan rotates. At this time, a surface in which the fluid is pushed in the blade surface and the pressure rises is set as a positive pressure surface 25, and a surface that is the back of the positive pressure surface 25 and in which the pressure decreases is set as a negative pressure surface 26. In the blade 202, with respect to the flow direction of the gas flow, the surface of the upstream side of the blade 202 becomes the negative pressure surface 26, and the surface of the downstream side becomes the positive pressure surface 25. In FIG. 20, in the blade 202, the surface of the front side of the blade 202 becomes the positive pressure surface 25, and the surface of the rear side of the blade 202 becomes the negative pressure surface 26.

[0147] The trailing edge 22b end of the positive pressure surface 25 of the blade 202 is provided with a flap portion 27 that protrudes outward, and the flap portion 27 extends smoothly from the inner edge 24 side to the outer edge 23 side.

[0148] The present application simulates the axial fan without the flap portion 27 (conventional technology) and the axial fan provided with the flap portion 27 in the present application, and the following results can be obtained:

[0149] As can be seen from the above table, the fan with the flap portion 27 added in the present application has an air volume increase of 134 CMH at the same wind speed, and the fan efficiency is improved by 2.8%.

[0150] The present application can significantly improve the overall performance of the fan by providing the flap portion 27 that protrudes outward at the trailing edge 22b end of the positive pressure surface 25.

[0151] In some embodiments, as shown in FIGS. 23 and 24, FIG. 24 is a sectional view of FIG. 23 along the X-X line, and the X-X line section is a blade section at a certain specific position in the radial direction with the rotation axis A as the center. In the blade section, the center line of the blade section is C.

[0152] In some embodiments, the height H direction of the flap portion 27 is perpendicular to the center line C of the blade passing through the trailing edge 22b.

[0153] The thickness d of the flap portion 27 is similar to the thickness of the blade 202. Exemplarily, the thickness d of the flap portion 27 = 2 mm.

[0154] The flap portion 27 can be integrally formed with the blade 202, and the structure, manufacturing process are relatively simple, and the cost is relatively low.

[0155] In some embodiments, the height of the flap portion 27 gradually decreases from the inner edge 24 side to the outer edge 23 side. In other words, the height of the flap portion 27 gradually increases from the outer edge 23 side to the inner edge 24 side.

[0156] In some embodiments, referring to FIG. 25, assuming that the horizontal axis is the length of the radius R from the inner edge 24 to the outer edge 23 in the radial direction, and the vertical axis is the height H of the flap portion 27, the relationship between the height H of the flap portion 27 and the length of the radius R from the inner edge 24 to the outer edge 23 in the radial direction is expressed as a flap height curve LP. The flap height curve LP is a smooth line segment.

[0157] The flap height curve LP includes a first portion 271 near the inner edge 24 side.

[0158] The first portion 271 is a curved segment close to a straight line segment. The first portion 271 occupies about 1 / 6 of the entire flap height curve LP. That is, the length of the flap portion 27 corresponding to the first portion 271 is about 1 / 6 of the total length of the flap portion 27. The line segment of the first portion 271 indicates that the height of the flap portion 27 near the inner edge 24 changes relatively small, and thus the slope of this portion is relatively small, close to 0. The flap portion 27 of this portion can also increase the structural strength of the trailing edge 22b of the blade 202 on the inner edge 24 side.

[0159] In addition, since the height of the flap portion 27 corresponding to the first portion 271 is the largest, in order to avoid the flap portion 27 excessively increasing the weight of the blade 202, the length of the flap portion 27 corresponding to the first portion 271 is relatively small.

[0160] The flap height curve LP includes a second portion 272 near the outer edge 23 side. The height of the flap portion 27 corresponding to the second portion 272 is smaller than that of the flap portion 27 corresponding to the first portion 271.

[0161] The second portion 272 occupies about 1 / 3 of the entire flap height curve LP. That is, the length of the flap portion 27 corresponding to the second portion 272 is about 1 / 3 of the total length of the flap portion 27.

[0162] The length of the flap portion 27 corresponding to the second portion 272 changes relatively small, for example, the flap portion 27 of this portion can be a constant height. Alternatively, the second portion 272 can be a curved segment close to a straight line segment.

[0163] The height difference of the flap portion 27 corresponding to the second portion 272 is also relatively small. In some embodiments, the height difference of the flap portion 27 corresponding to the second portion 272 is smaller than that of the flap portion 27 corresponding to the first portion 271.

[0164] The flap height curve LP also includes a third portion 273 between the first portion 271 and the second portion 272. The height of the third portion 273 is also between the height of the first portion 271 and the height of the second portion 272. That is, the height of the flap portion 27 corresponding to the third portion 273 is less than the height of the flap portion 27 corresponding to the first portion 271, and the height of the flap portion 27 corresponding to the third portion 273 is greater than the height of the flap portion 27 corresponding to the second portion 272.

[0165] The third portion 273 occupies about 1 / 2 of the flap height curve LP. That is, the length of the flap portion 27 corresponding to the third portion 273 is about 1 / 2 of the total length of the flap portion 27.

[0166] In some embodiments, the slope of the third portion 273 is greater than the slope of the first portion 271 and the second portion 272. That is, the third portion 273 is steeper than the first portion 271 and the second portion 272.

[0167] The third portion 273 is set to be relatively steep so that the height difference between the first portion 271 and the second portion 272 is relatively large. That is, the height of the first portion 271 can be set to be relatively large to ensure the strength of the blade root; and the height of the second portion 272 is as low as possible to avoid the influence of the flap portion 27 on the weight increase on the basis of ensuring the performance of the flap portion 27.

[0168] In some embodiments, the slope of the third portion 273 is not greater than 0.08. This avoids the height of the flap portion 27 corresponding to the first portion 271 being too high or the height of the flap portion 27 corresponding to the second portion 272 being too low. The height of the first portion 271 being too high increases the axial size of the axial flow fan and increases the weight. The height of the second portion 272 being too low greatly reduces the effect of the flap portion 27 on improving the performance of the fan.

[0169] The slope of the third portion 273 is not less than 0.015. If the slope of the third portion 273 is too small, the heights of the portions of the flap portion 27 are almost the same. If the overall height is set to be the height corresponding to the first portion 271, the weight will be increased due to the large height. If the overall height is set to be the height corresponding to the second portion 272, the blade root will not be able to increase the strength.

[0170] In some embodiments, the maximum height of the flap portion 27 is not greater than 10 mm. This avoids the flap portion 27 being too high, which increases the axial size and the weight of the fan.

[0171] The minimum height of the flap portion 27 is not less than 2 mm to improve the performance of the blade.

[0172] As an example, the following table is a few points on the flap height curve:

[0173] The first portion 271 corresponds to a portion of the flap portion 27 having a radius of 90mm to 120mm, the second portion 272 can be a portion corresponding to a radius of 210mm to 270mm, and the third portion 273 can be a portion of the flap portion 27 corresponding to a radius of 120mm to 210mm.

[0174] Fig. 26 shows a fan surface turbulent energy diagram of the axial flow fan of the conventional technology (left side) and the axial flow fan of the present application (right side), which characterizes the loss of the fan surface, wherein the black area indicates a larger aerodynamic loss.

[0175] As can be seen from the contrast of the circled places in the figure, the black area of the present application is reduced compared with the conventional technology, that is, the aerodynamic loss of the blade 202 is significantly reduced after the flap portion 27 is added.

[0176] Fig. 27 shows a static pressure nephogram of the fan surface of the axial flow fan of the conventional technology (left side) and the axial flow fan of the present application (right side), which characterizes the work capacity of the fan surface, and the black area indicates a larger work capacity.

[0177] As can be seen from the contrast of the circled places in the figure, the area of the black area of the present application is increased, that is, the work capacity of the blade near the trailing edge 24 is significantly improved after the flap portion 27 is added, and the negative pressure area of the fan surface is significantly improved.

[0178] In some embodiments, the height of the flap portion 27 gradually decreases in the direction from the inner edge 24 to the outer edge 23.

[0179] In some embodiments, the axial flow fan includes a plurality of blades, each blade including a first blade and a second blade in series, the leading edge of the first blade forming the leading edge of the blade, and the trailing edge of the second blade forming the trailing edge of the blade, and a flap portion can be provided on the trailing edge of the second blade to improve the performance rate of the fan.

[0180] In addition, the air volume and fan efficiency of the axial flow fan 200 of the present application when reversed are also higher than those of the axial flow fan of the conventional technology when reversed.

[0181] Specifically, the air conditioner outdoor unit is installed for use in an outdoor environment, and in some cases, the outdoor environment is worse than the indoor environment, and the air volume of the outdoor unit is also higher than that of the indoor unit, so the dust accumulation amount of the heat exchanger in the outdoor unit is higher. At this time, the heat exchanger needs to be cleaned to avoid the weakening of the whole machine capacity caused by dust accumulation.

[0182] The cleaning of the heat exchanger can be implemented in cooperation with the reverse rotation of the fan. Specifically, the whole machine runs in the heating mode, the heat exchanger is frosted; the whole machine runs in the refrigeration mode, the heat exchanger is defrosted; in the process of defrosting, the fan is reversed, and the wind is blown to the heat exchanger, so that part of the dirt adhered to the heat exchanger is blown off, thereby realizing the cleaning of the heat exchanger.

[0183] The axial flow fan of the present application can increase the wind speed on the heat exchanger by 0.5-2 m / s compared with the conventional technology when the rotation speed is reversed. Therefore, the air conditioner of the present application can improve the cleaning speed of the heat exchanger.

[0184] In freezing rain and snow weather, the outdoor unit blows out low-temperature wind during heating operation, which causes the rain and snow to be easily sucked into the heat exchanger, thereby freezing the heat exchanger or freezing the fan, which causes the fan to break due to poor dynamic balance during operation.

[0185] The air conditioner heating cooperates with the forward and reverse rotation of the fan, which can prevent the outdoor unit from freezing. Specifically, the whole machine runs in the heating mode, and the forward and reverse rotation of the fan can intermittently blow wind to the heat exchanger and the grille plate, thereby preventing the components from being frozen by freezing rain, and also preventing the fan surface from being iced, which causes the fan to be damaged during operation.

[0186] The axial flow fan of the present application can provide the same air volume as the forward rotation when reversed, thereby ensuring that the outdoor unit can also operate normally when the fan is reversed.

[0187] In the present application, the trailing edge 22b end of the pressure surface 25 of the blade 202 is provided with an outwardly protruding flap part 27, which smoothly extends from the inner edge 24 side to the outer edge 23 side, so that the air volume and fan efficiency of the fan are improved at the same wind speed, and the overall performance of the fan is significantly improved.

[0188] In the present application, the axial flow fan can increase the wind speed on the heat exchanger compared with the conventional technology when the rotation speed is reversed, thereby improving the cleaning speed of the heat exchanger.

[0189] In the present application, the axial flow fan can provide a larger air volume compared with the conventional technology when the rotation speed is reversed, thereby ensuring that the air conditioner can also operate normally when the fan is reversed.

[0190] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

[0191] For the sake of explanation, the foregoing descriptions have been presented in terms of specific embodiments. However, it is to be appreciated that specific embodiments described herein are not intended to limit the scope of the present application, which is defined with reference to the following claims. Various modifications and changes can be made thereto by those skilled in the art which fall within the scope of the present application as defined by the following claims. The embodiments were chosen and described in order to explain the principles of the application and the practical application and to enable others skilled in the art to understand for implementing various embodiments and with various modifications as are suited to the particular use contemplated.

Claims

1. An axial flow fan, wherein: include: A wheel hub, configured to be driven to rotate about a central axis; as well as A plurality of blades are connected to the hub, and the plurality of blades are evenly distributed along the circumference of the hub. Each of the blades includes a first blade and a second blade arranged in series, the leading edge of the first blade forms the leading edge of the blade, the trailing edge of the second blade forms the trailing edge of the blade, and the trailing edge end of the first blade is spaced apart from the trailing edge end of the second blade.

2. The axial flow fan according to claim 1, wherein: The axial flow fan further comprises: A plurality of splitter blades are connected to the hub and correspond to the blades. In a direction parallel to the axis of the hub, the splitter blades are located on a side where the pressure surface of the first blade is located.

3. The axial flow fan according to claim 2, wherein: In the corresponding blades and splitter blades, when projected on a plane perpendicular to the axis of the hub, at least half of the area of ​​the splitter blade overlaps with the first blade, and the splitter blade does not overlap with the second blade.

4. The axial flow fan according to claim 2, wherein: The hub includes a first hub portion and a second hub portion connected to each other; the blades are connected to the first hub portion, and the splitter blades are connected to the second hub portion.

5. The axial flow fan according to claim 4, wherein: One of the first hub part and the second hub part is provided with a hook portion, and the other is provided with a hook groove, and the hook portion is adapted to the hook groove.

6. The axial flow fan according to any one of claims 1 to 5, wherein: In the blade profile cross section, in a direction perpendicular to the hub axis, a distance between the trailing edge of the first blade and the leading edge of the second blade is θ1; The magnitude of θ1 is related to the radius of a circle having the axis of the hub as its center.

7. The axial flow fan according to claim 6, wherein: The blade has an outer edge and an inner edge, the inner edge is connected to the hub, and the outer edge is the edge of the outer peripheral side of the blade. In the direction from the inner edge to the outer edge, the distance θ1 between the first blade and the second blade gradually increases as the radius increases.

8. The axial flow fan according to claim 7, wherein: The outer diameter of the axial flow fan is 260 mm to 410 mm, and the value range of θ1 is greater than or equal to 2 mm and less than or equal to 12 mm.

9. The axial flow fan according to claim 8, wherein: Along the direction of increasing radius, the value of θ1 gradually increases from 2 mm to 12 mm.

10. The axial flow fan according to any one of claims 1 to 5, wherein: In the blade profile cross section, in a direction parallel to the hub axis, a distance between the trailing edge of the first blade and the leading edge of the second blade is θ2; The value of θ2 is the same in each blade profile section of the blade.

11. The axial flow fan according to claim 10, wherein: The outer diameter of the axial flow fan is 260 mm to 410 mm, and the value range of θ2 is 8 mm to 10 mm.

12. The axial flow fan according to any one of claims 1 to 5, wherein: In a plane perpendicular to the axis of the hub, on a circle with the axis of the hub as the center and passing through the blade, the arc length from the leading edge of the first blade to the trailing edge of the second blade is L1, and the arc length of the first blade is L2, and L2 / L1=n, n=0.4~0.

6.

13. The axial flow fan according to claim 12, wherein: The relationship between the size of n and the radius of a circle with the axis of the hub as the center is as follows: as the radius increases, the size of n tends to increase first, then decrease, and then increase again.

14. The axial flow fan according to claim 12, wherein: In the blade profile section, the angle between an imaginary line perpendicular to the axis of the hub and intersecting a point on the blade profile section and a tangent line of the point relative to the blade is defined as angle β; The angle β of the trailing edge of the first blade is the same as the angle β of the leading edge of the second blade.

15. The axial flow fan according to claim 14, wherein The ratio of the arc length from any point on the blade to the leading edge to L1 is defined as z, and the z value corresponding to the front part of the second blade is smaller than the z value corresponding to the rear part of the second blade.

16. The axial flow fan according to claim 15, wherein With the size of the angle β as the vertical axis and the size of z as the horizontal axis, the line segment formed by the size of the angle β of the second blade and the size of z deviates from the line segment formed by the size of the angle β of the first blade and the size of z.

17. The axial flow fan according to claim 16, wherein: With the size of the β angle as the vertical axis and the size of z as the horizontal axis, an outer edge β angle curve is formed. The outer edge β angle curve includes two disconnected line segments, namely the first line LP1 and the second line LP2. The first line LP1 corresponds to the relationship between the β angle and the z value of the first blade, and the second line LP2 corresponds to the relationship between the β angle and the z value of the second blade. The front part of the second line LP2 deviates from the alignment trend of the first line LP.

18. An air conditioner, wherein: include: case; a refrigerant circuit having a condenser and an evaporator; The axial flow fan according to any one of claims 1 to 17 is arranged in the housing and is used to blow air toward at least one of the condenser and the evaporator.

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