CN211501072U - Impeller, mixed flow fan and air conditioner - Google Patents

Abstract

The utility model discloses an impeller, a mixed flow fan and an air conditioner. The impeller includes a wheel cover, a wheel hub and a plurality of blades. The wheel cover includes an inner cavity that passes through along the axis, and the inner cavity has an air inlet end and an air outlet end arranged oppositely; the wheel hub is arranged in the wheel cover; the plurality of blades are connected to the wheel cover between the inner surface of the hub and the outer surface of the hub, and the blade includes a blade root connected with the outer surface of the hub and extending along the outer surface of the hub and an outer edge of the blade opposite to the blade root, and the contour line of the outer edge of the blade is in the direction passing through the axis. The projection on the longitudinal projection surface is a variable inclination curve, and the angle between the tangent of the variable inclination curve and the longitudinal reference line gradually increases from the air inlet end to the air outlet end. The projection of the outer edge of the blade on the longitudinal projection surface of the utility model is a variable inclination curve, and the angle between the tangent of the variable inclination curve and the longitudinal reference line gradually increases, so that the blade gradually guides the airflow in the flow channel to avoid large pressure gradients and reduce flow losses.

Description

Impellers, mixed flow fans and air conditioners

technical field

The utility model relates to the technical field of electrical appliances, in particular to an impeller, a mixed flow fan and an air conditioner.

Background technique

The air duct system is one of the components used in the air conditioner to accelerate the heat exchange of the air in the action area of the air conditioner. In the air duct system of the air conditioner, the designer selects and matches the appropriate fan according to the actual needs corresponding to the different models and specifications of the air conditioner to meet the working quality and comfort of the air conditioner.

In order to meet the air volume and pressure head indexes of the air conditioner, the air duct system of the air conditioner in the related art adopts a mixed flow fan. Designers found that the pressure gradient of the airflow in the flow channel of the mixed-flow fan in the related art is relatively large, thereby causing a large flow loss.

Utility model content

The utility model provides an impeller, a mixed flow fan and an air conditioner to avoid flow loss caused by a large pressure gradient.

A first aspect of the present utility model provides an impeller, comprising:

a wheel cover, comprising an inner cavity passing through along the axis, and the inner cavity has an air inlet end and an air outlet end arranged oppositely;

a wheel hub, disposed within the wheel cover; and

A plurality of blades are connected between the inner surface of the wheel cover and the outer surface of the hub, and the blades include a blade root connected with the outer surface of the hub and extending along the outer surface of the hub and an outer edge of the blade opposite the blade root. The projection of the contour line of the edge on the longitudinal projection plane passing through the axis is a variable inclination curve. In the direction from the air inlet end to the air outlet end, the angle between the tangent of the variable inclination curve and the longitudinal reference line gradually increases. Lines are parallel to the axis.

In some embodiments, the variable inclination curve includes a first end point on one side of the air inlet end and a second end point on the side of the air outlet end, wherein a tangent of the variable inclination curve at the first end point and a longitudinal reference line The inlet angle between is in the range of [20°, 85°]; and/or the outlet angle between the tangent of the variable inclination curve at the second end point and the longitudinal reference line is in the range of [10°, 70° ].

In some embodiments, the inlet angle is 50° and the outlet angle is 57.7°.

In some embodiments, the variable dip curve is a first S-shaped curve.

In some embodiments, the first S-shaped curve has an inflection point and includes a first curve segment and a second curve segment respectively located on both sides of the inflection point, and a ratio between a radius of curvature of the first curve segment and a radius of curvature of the second curve segment The range is [0.2, 5].

In some embodiments, the radius of curvature of the first curved segment is 125 mm, and the radius of curvature of the second curved segment is 38 mm.

In some embodiments, the projection of the blade root on the longitudinal projection plane is a second S-shaped curve.

In some embodiments, the second S-shaped curve includes a third end point on one side of the air inlet end and a fourth end point on the side of the air outlet end, wherein the tangent line of the second S-shaped curve at the third end point and the transverse direction The range of the entrance angle between the reference lines is [65°, 120°]; and/or the range of the exit angle between the tangent of the second S-shaped curve at the fourth end point and the transverse reference line is [10 °, 65°].

In some embodiments, the entrance angle between the tangent of the second S-shaped curve at the third end point and the lateral reference line is 91°, and the tangent of the second S-shaped curve at the fourth end point and the lateral reference line is 91° The entrance angle is 24°.

In some embodiments, the blade further includes a leading edge located on one side of the air inlet end, and the projection of the contour line of the leading edge on a transverse projection plane perpendicular to the axis is a concave curve.

In some embodiments, the blade is a twisted blade, and the surface of the twisted blade includes a first curved surface segment, a second curved surface segment and a third curved surface segment sequentially arranged from the air inlet end to the air outlet end, and the second curved surface segment is located on the first curved surface Between the segment and the third curved segment and relative to the first curved segment and the third curved segment, it is concave toward one side in the rotational direction of the impeller.

In some embodiments, the first curved surface segment, the second curved surface segment and the third curved surface segment are transitioned by a circular arc surface.

In some embodiments, the blade further includes a trailing edge located on one side of the air outlet end, and the projection of the contour line of the trailing edge on the longitudinal projection plane is a concave arc.

In some embodiments, the number of blades is 6 to 20.

A second aspect of the present utility model provides a mixed-flow fan, comprising the impeller according to any one of the first aspect of the present utility model.

A third aspect of the present utility model provides an air conditioner, which includes the mixed-flow fan according to the second aspect of the present utility model.

Based on the technical solution provided by the present utility model, the impeller includes a wheel cover, a wheel hub and a plurality of blades, the wheel cover includes an inner cavity passing through along the axis, and the inner cavity has an air inlet end and an air outlet end arranged oppositely; the wheel hub is arranged on the wheel cover Inside; a plurality of blades are connected between the inner surface of the wheel cover and the outer surface of the hub, and the blades include a blade root connected with the outer surface of the hub and extending along the outer surface of the hub and an outer edge of the blade opposite the blade root, the blade The projection of the contour line of the outer edge on the longitudinal projection plane passing through the axis is a variable inclination curve. In the direction from the air inlet end to the air outlet end, the angle between the tangent of the variable inclination curve and the longitudinal reference line gradually increases. The reference line is parallel to the axis. The projection of the outer edge of the blade of the present invention on the longitudinal projection plane is a variable inclination curve, and the angle between the tangent of the variable inclination curve and the longitudinal reference line gradually increases, so that the blade of the present invention gradually guides the airflow in the flow channel so as to Avoid large pressure gradients and reduce flow losses.

Other features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings.

Description of drawings

The accompanying drawings described here are used to provide further understanding of the present invention and constitute a part of the present application. The schematic embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention. In the attached image:

Fig. 1 is the three-dimensional structure schematic diagram of the impeller of the utility model embodiment;

Fig. 2 is the sectional structure schematic diagram of the impeller shown in Fig. 1;

Fig. 3 is the partial enlarged structural schematic diagram of the impeller shown in Fig. 2;

FIG. 4 is a schematic structural diagram of the impeller shown in FIG. 1 after removing the wheel cover;

Fig. 5 is a three-dimensional schematic diagram of one of the blades in Fig. 4;

Fig. 6 is the top-view structure schematic diagram of the impeller shown in Fig. 1;

Fig. 7 is the partial enlarged structural schematic diagram of the impeller in Fig. 6;

Fig. 8 is the bottom view structure schematic diagram of the impeller shown in Fig. 1;

9 to 11 are schematic diagrams of the projection structure of another blade in FIG. 4 on the longitudinal projection plane;

Fig. 12 is the velocity vector diagram in the inlet channel of the mixed-flow fan of the related art;

FIG. 13 is a velocity vector diagram in the inlet channel of the mixed-flow fan according to the embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the implementations. example. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application or uses in any way. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the invention unless specifically stated otherwise. Meanwhile, it should be understood that, for the convenience of description, the dimensions of various parts shown in the accompanying drawings are not drawn in an actual proportional relationship. Techniques, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the authorized description. In all examples shown and discussed herein, any specific value should be construed as illustrative only and not as limiting. Accordingly, other examples of exemplary embodiments may have different values. It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further discussion in subsequent figures.

For ease of description, spatially relative terms, such as "on", "over", "on the surface", "above", etc., may be used herein to describe what is shown in the figures. The spatial positional relationship of one device or feature shown to other devices or features. It should be understood that spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "above" or "over" other devices or features would then be oriented "below" or "over" the other devices or features under other devices or constructions". Thus, the exemplary term "above" can encompass both an orientation of "above" and "below." The device may also be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptions used herein interpreted accordingly.

The specific structure of the impeller of the embodiment of the present invention will be described in detail below according to FIG. 1 to FIG. 13 .

As shown in FIGS. 1 , 2 , 5 and 10 , the impeller of the embodiment of the present invention includes a hub 1 , a wheel cover 3 and a plurality of blades 2 , wherein the wheel cover 3 includes an inner cavity passing through along the axis, and the inner The cavity has an air inlet end and an air outlet end arranged oppositely; the hub 1 is arranged in the wheel cover 3; a plurality of blades 2 are connected between the inner surface of the wheel cover 3 and the outer surface of the wheel hub 1, and the blades 2 include and the hub 1 The outer surface of the blade connects and extends along the outer surface of the hub 1 with the blade root 24 and the blade outer edge 22 opposite the blade root 24 . The projection of the contour line of the outer edge 22 of the blade on the longitudinal projection plane passing through the axis L is a variable inclination curve. In the direction from the air inlet end to the air outlet end, the angle between the tangent of the variable inclination curve and the longitudinal reference line gradually increases. big.

The projection of the outer edge 22 of the blade in the embodiment of the present invention on the longitudinal projection plane is a variable inclination curve, and the angle between the tangent of the variable inclination curve and the longitudinal reference line gradually increases, so that the blade of this embodiment convects the airflow in the flow channel Stepwise orientation avoids large pressure gradients and reduces flow losses.

It should be noted here that the transverse projection plane of the embodiment of the present invention is perpendicular to the axis L of the impeller. The longitudinal projection plane of the embodiment of the present invention needs to pass through the axis L of the impeller. And for any blade, the longitudinal projection plane refers to the longitudinal projection plane facing the direction of the axis L of the blade. For example, among the blades 2 in FIG. 4 , the longitudinal projection plane corresponding to the blade located on the front side of the hub 1 and at the middlemost position is the longitudinal projection plane parallel to the paper surface. That is to say, for different blades, the positions of their longitudinal projection surfaces are different. The longitudinal reference line of the embodiment of the present invention is located in the longitudinal projection plane and is parallel to the axis L, and the transverse reference line is perpendicular to the axis L.

In some embodiments, as shown in FIG. 10 , the variable inclination curve includes a first end B on the side of the air inlet end and a second end C on the side of the air outlet, wherein the variable inclination curve is at the first end The entry angle d between the tangent at point B and the longitudinal reference line is in the range [20°, 85°]. The range of the exit angle g between the tangent of the variable inclination curve at the second end point C and the longitudinal reference line is [10°, 70°].

Optionally, after experiments, when the inlet angle d is set to 50° and the outlet angle g is set to 57.7°, the flow loss of the airflow is the smallest.

In this embodiment, as shown in FIG. 10 , the variable inclination curve is a first S-shaped curve. Specifically, the first S-shaped curve in this embodiment has an inflection point and includes a first curve segment and a second curve segment respectively located on both sides of the inflection point. The radius of curvature R1 of the first curve segment and the radius of curvature R2 of the second curve segment are between The ratio between them ranges from [0.2, 5].

Optionally, it has been proved by experiments that when the radius of curvature R1 of the first curved segment is set to 125 mm, and the radius of curvature R2 of the second curved segment is set to be 38 mm, the flow loss of the airflow is minimal.

As shown in FIG. 11 , in this embodiment, the projection of the blade root 24 on the longitudinal projection plane is a second S-shaped curve.

Specifically, the second S-shaped curve includes a third end point A on the side of the air inlet end and a fourth end point D on the side of the air outlet end, wherein the tangent line of the second S-shaped curve at the third end point A and the transverse direction The range of the inlet angle m between the reference lines is [65°, 120°]; the range of the outlet angle n between the tangent of the second S-shaped curve at the fourth end point D and the transverse reference line is [10° , 65°]. The transverse reference line here is also not an absolute transverse reference line, but lies in the longitudinal projection plane through the axis L and is perpendicular to the axis L.

Optionally, the entrance angle m between the tangent of the second S-shaped curve at the third end point A and the transverse reference line is 91°, and the difference between the tangent of the second S-shaped curve at the fourth end point D and the transverse reference line is 91°. The entrance angle n between them is 24°.

The second S-shaped curve of the present embodiment has an inflection point and includes a first curve segment and a second curve segment respectively located _on both sides of the inflection point, and the curvature radius R4 of the first curve segment and the curvature radius _R3 of the second curve segment are between The range of the ratio is [0, 3.5].

As shown in FIG. 4 , the blade 2 further includes a leading edge 21 located on one side of the air inlet end. As shown in FIG. 7 , the projection of the contour line of the leading edge 21 on the lateral projection plane perpendicular to the axis L is a concave curve. That is to say, when looking at the impeller from above, the shape of the leading edge 21 of the blade 2 is roughly concave, so as to reduce the intake resistance and the direct impact on the blade, thereby improving the smoothness of the intake air and enabling the fan to operate efficiently and with low noise.

In this embodiment, the blade 2 is a twisted blade. The twisted blade includes three curved surface segments from the air inlet end to the air outlet end, the three curved surface segments are respectively a first curved surface segment, a second curved surface segment and a third curved surface segment, wherein the second curved surface segment is located between the first curved surface segment and the third curved surface segment. Between the third curved surface segments and relative to the first curved surface segment and the third curved surface segment, it is concave to one side in the rotation direction of the impeller. That is to say, the twisted blade of this embodiment is a double twisted structure, which can reduce the separation of airflow in the internal flow channel, avoid the generation of a large number of vortices, and optimize the airflow of the entire fan.

Further, the blade 2 of this embodiment further includes a trailing edge 23 located on one side of the air outlet. As shown in FIG. 9 , the projection of the trailing edge 23 on the longitudinal projection plane is a concave arc. And the concave arc line is concave toward the outer side of the blade, and the outer side of the blade here refers to the side away from the blade body. As shown in FIG. 6 , when looking up at the impeller from below, the general shape of the trailing edge 23 of the blade 2 is a concave surface to avoid the formation of swirls in the air flow and optimize the flow of the air flow.

When the impeller of this embodiment is applied to a mixed flow fan and the mixed flow fan is applied to an air conditioner, the number of blades is set to 6 to 20.

The structure of the impeller of the specific embodiment of the present invention will be described in detail below according to FIGS. 1 to 11 .

As shown in FIG. 1 , the impeller of this embodiment includes a hub 1 , a wheel cover 3 and a plurality of blades 2 ; wherein. The wheel cover 3 has an inner cavity passing through along the axis, and the inner cavity has an air inlet end and an air outlet end respectively located at both ends. Among them, the air inlet end is located on the upper side, and the air outlet end is located on the lower side. As shown in FIG. 2, the outer surface of the hub 1 is substantially tapered. The wheel cover 3 is coaxially sleeved on the outer side of the wheel hub 1 . A plurality of blades 2 are connected between the outer surface of the hub 1 and the inner surface of the wheel cover 3 . As shown in FIG. 4 , each blade 2 includes a leading edge 21 on the side of the air inlet end, a trailing edge 23 on the side of the air outlet end, and a blade connected to the outer surface of the hub 1 and extending along the outer surface of the hub 1 The root 23 and the outer edge 22 opposite the blade root 23 .

As shown in FIG. 6 and FIG. 7 , in the top view of the impeller, the leading edge 21 of this embodiment has a first intersection E intersecting with the hub 1 and a second intersection F intersecting with the wheel cover 3 . At this time, the leading edge 21 is a concave curve connecting the first intersection E and the second intersection F. That is, the projection of the contour line of the leading edge 21 on the lateral projection plane perpendicular to the axis L is a concave curve. The projection of the blades 21 of the impeller in the present embodiment on the lateral projection plane is a concave curve to reduce the intake resistance and the direct impact of the airflow on the blades, thereby optimizing the intake conditions and helping the fan to operate efficiently and with low noise. In this embodiment, the direction of the concave curve is opposite to the direction of rotation of the impeller. Specifically, as shown in FIG. 7 , the impeller of this embodiment rotates counterclockwise. This setting can further improve the smoothness of the intake air.

Specifically, the concave curve in this embodiment includes a leaf-shaped line. For example, the following equation can be used to obtain the lobe line trajectory.

x=p*m ₁ *k*t/n ₁ +t ³ ;

y=m ₁ *k*t ² /n ₂ +t ³ ;

Among them, k is a parameter used to adjust the chord length of the concave curve; _{p =} ± ₁ is used to adjust the direction of the concave curve; .

In this embodiment, as shown in FIGS. 6 and 7 , the included angle a between the tangent of the concave curve at the first intersection E and the tangent of the contour line of the hub 1 at the first intersection E is in the range of [20 °, 150°], preferably, the included angle a is 70°. And the range of the included angle b between the tangent of the concave curve at the second intersection F and the tangent of the wheel cover 3 at the second intersection F is [20°, 150°], preferably, the included angle b is 78.5°.

In this embodiment, the distance between the projection of the maximum inflection point O of the concave curve on the chord line connecting the first intersection E and the second intersection F and the first intersection A is 20%-85% of the chord length. The maximum inflection point O here refers to the point on the concave curve with the largest distance from the chord.

In this embodiment, the range of the distance c between the maximum bending line O and the string line is [2mm, 12mm]. Preferably, the distance c between the maximum bending line O and the chord line is 2.4 mm.

As shown in FIG. 3 , the projection of the leading edge 21 on the longitudinal projection plane is an inclined line, and the vertical distance between the inclined line and the transverse reference line gradually increases in the extending direction from the radially inner side to the radially outer side. The transverse reference line here refers to a transverse reference line that passes through the radially inner end point of the inclined line and is perpendicular to the axis. Preferably, the maximum vertical distance h between the inclined line and the transverse reference line is in the range of [0, 15mm]. More preferably, h is 6.7mm.

In some embodiments, the number of blades is 6 to 20.

Figures 9 to 11 are projections of a single blade on a longitudinal projection plane.

In this embodiment, as shown in FIGS. 8 and 9 , the trailing edge projection of the trailing edge 23 is a concave arc. The trailing edge design of the concave arc can optimize the flow condition of the mixed-flow fan to the greatest extent, reduce the flow separation of the airflow in the internal flow channel of the mixed-flow fan, and avoid the generation of a large number of vortex shedding.

In practical application, the two end points of the concave arc line are the second end point C and the fourth end point D respectively, and the length range of the chord CD is [10mm, 30mm]. The included angle e between the tangent line and the chord line is in the range of [10°, 50°], and the included angle f between the tangent line and the chord line of the concave arc at the fourth endpoint D is [10°, 50°] . Preferably, the length of the chord line CD in this embodiment is 19 mm, the angle e between the tangent of the concave arc line at the second end point C and the chord line is 31°, and the concave arc line is at the fourth end point. The angle f between the tangent at D and the chord is 31.5°.

As shown in FIG. 10 , the projection of the outer edge 22 of the blade 2 in this embodiment on the longitudinal projection plane is a variable inclination arc. In the direction from the air inlet end to the air outlet, the tangent of the variable inclination arc and the longitudinal reference line The inclination angle gradually increases.

Specifically, as shown in FIG. 10 , the outer edge 22 of this embodiment is an S-shaped curve.

In some embodiments, as shown in FIG. 10 , the variable inclination curve includes a first end B on the side of the air inlet end and a second end C on the side of the air outlet, wherein the variable inclination curve is at the first end The entry angle d between the tangent at point B and the longitudinal reference line is in the range [20°, 85°]. The range of the exit angle g between the tangent of the variable inclination curve at the second end point C and the longitudinal reference line is [10°, 70°].

Optionally, after experiments, when the inlet angle d is set to 50° and the outlet angle g is set to 57.7°, the flow loss of the airflow is the smallest.

Through the above optimized design, as shown in FIG. 2 , the internal flow channel of the mixed-flow fan in this embodiment has a special form, so that the airflow flows in along the axis L of the impeller, and then flows out obliquely. Specifically, in the longitudinal projection plane, the impeller flow channel of this embodiment is roughly a flow channel curve M ₁ M ₂ , and the angle between the tangent line of the flow channel curve M ₁ M ₂ at the air inlet end and the longitudinal reference line The range of α is [0, 30°], and the range of the included angle β between the tangent line at the outlet end and the transverse reference line is [0, 80°]. Optionally, the angle α between the tangent line of the flow channel curve M ₁ M ₂ at the air inlet end and the longitudinal reference line is 10 degrees, and the angle β between the tangent line at the air outlet end and the transverse reference line is β. is 40 degrees.

The simulation experiment of the mixed flow fan in this embodiment is carried out and compared with the simulation of the mixed flow fan before optimization. The experimental data is shown in the following table. During the simulation experiment, the noise measurement point is 0.5m from the fan outlet.

It can be seen from the simulation data that when the air volume is close, the fan speed after optimization decreases significantly, the noise value decreases under the same air volume, the operating efficiency and pressure head are improved, and the aerodynamic performance and wind noise level of the fan are significantly improved. By comparing the velocity vector diagrams shown in Figure 12 and Figure 13, it can also be found that after the optimization, the airflow entering direction along the guide ring has changed significantly, and the airflow shifted to the middle of the flow channel. Through the intake rectification, the flow velocity distribution is more uniform , the velocity gradient slows down significantly.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present utility model rather than limit them; although the present utility model has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: still The specific embodiments of the present invention can be modified or some technical features can be equivalently replaced; without departing from the spirit of the technical solutions of the present invention, all of them should be included in the scope of the technical solutions claimed in the present invention.

Claims (16)

1. an impeller, is characterized in that, comprises: A wheel cover (3), comprising an inner cavity passing through along the axis, and the inner cavity has an air inlet end and an air outlet end arranged oppositely; A wheel hub (1), arranged in the wheel cover (3); and a plurality of blades (2) connected between the inner surface of the wheel cover (3) and the outer surface of the hub (1), and the blades (2) comprise an outer surface of the hub (1) A blade root (24) connected and extending along the outer surface of the hub (1) and a blade outer edge (22) opposite the blade root (24), the contour of the blade outer edge (22) passing through The projection on the longitudinal projection plane of the axis (L) is a variable inclination curve. From the air inlet end to the air outlet end, the angle between the tangent of the variable inclination curve and the longitudinal reference line gradually increases. Increase, the longitudinal reference line is parallel to the axis (L). 2 . The impeller according to claim 1 , wherein the variable inclination curve comprises a first end point (B) on one side of the air inlet end and a second end point on one side of the air outlet end. 3 . (C), wherein, the range of the entrance angle (d) between the tangent of the variable inclination curve at the first end point (B) and the longitudinal reference line is [20°, 85°]; And/or, the range of the exit angle (g) between the tangent of the variable inclination curve at the second end point (C) and the longitudinal reference line is [10°, 70°]. 3 . The impeller according to claim 2 , wherein the inlet angle (d) is 50°, and the outlet angle (g) is 57.7°. 4 . 4. The impeller according to claim 1, wherein the variable inclination curve is a first S-shaped curve. 5 . The impeller according to claim 4 , wherein the first S-shaped curve has an inflection point and includes a first curve segment and a second curve segment respectively located on both sides of the inflection point, the first curve segment The ratio between the radius of curvature (R ₁ ) of and the radius of curvature (R ₂ ) of the second curve segment is in the range of [0.2, 5]. 6 . The impeller according to claim 5 , wherein the radius of curvature (R ₁ ) of the first curved segment is 125 mm, and the radius of curvature (R ₂ ) of the second curved segment is 38 mm. 7 . 7. The impeller according to any one of claims 1 to 6, wherein the projection of the blade root (24) on the longitudinal projection plane is a second S-shaped curve. 8 . The impeller according to claim 7 , wherein the second S-shaped curve comprises a third end point (A) located on one side of the air inlet end and a fourth end point (A) located on one side of the air outlet end. 9 . End point (D), wherein, the range of the entrance angle (m) between the tangent of the second S-shaped curve at the third end point (A) and the transverse reference line is [65°, 120°]; And/or, the range of the exit angle (n) between the tangent of the second S-shaped curve at the fourth end point (D) and the transverse reference line is [10°, 65°]. 9 . The impeller according to claim 8 , wherein the inlet angle (m) between the tangent of the second S-shaped curve at the third end point (A) and the transverse reference line is 91°. 10 . , the entrance angle (n) between the tangent of the second S-shaped curve at the fourth end point (D) and the transverse reference line is 24°. 10. The impeller according to any one of claims 1 to 6, wherein the blade (2) further comprises a leading edge (21) located on one side of the air inlet end, the leading edge (21) ) on the lateral projection plane perpendicular to the axis (L) is a concave curve. 11. The impeller according to any one of claims 1 to 6, characterized in that, the blade (2) is a twisted blade, and the surface of the twisted blade includes from the air inlet end to the air outlet end A first curved surface segment, a second curved surface segment and a third curved surface segment are arranged in sequence, the second curved surface segment is located between the first curved surface segment and the third curved surface segment and is opposite to the first curved surface segment and the The third curved surface segment is concave toward one side in the rotation direction of the impeller. 12 . The impeller according to claim 11 , wherein the first curved surface segment, the second curved surface segment and the third curved surface segment are transitioned by a circular arc surface. 13 . 13. The impeller according to any one of claims 1 to 6, wherein the blade (2) further comprises a trailing edge (23) located on one side of the air outlet end, the trailing edge (23) ) on the longitudinal projection plane is a concave arc. 14. The impeller according to claim 1, wherein the number of the blades (2) is 6 to 20. 15. A mixed flow fan, characterized in that it comprises the impeller according to any one of claims 1 to 14. 16. An air conditioner, characterized by comprising the mixed flow fan according to claim 15.

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