WO2021147605A1

WO2021147605A1 - Impeller, mixed flow blower, and air conditioner

Info

Publication number: WO2021147605A1
Application number: PCT/CN2020/138941
Authority: WO
Inventors: 谭建明; 张治平; 马屈杨; 池晓龙; 苏玉海; 张碧瑶; 夏凯
Original assignee: 珠海格力电器股份有限公司
Priority date: 2020-01-20
Filing date: 2020-12-24
Publication date: 2021-07-29
Also published as: CN111441984A

Abstract

An impeller, a mixed flow blower, and an air conditioner. The impeller comprises an impeller cover (3), a hub (1), and a plurality of blades (2); the impeller cover (3) comprises an axially through inner cavity, and the inner cavity is provided with an air inlet end and an air outlet end which are oppositely provided; the hub is provided in the impeller cover; the plurality of blades are connected between an inner surface of the impeller cover and an outer surface of the hub, the blades are twisted blades, the surface of each twisted blade comprises a first surface section (2A), a second surface section (2B), and a third surface section (2C), and the second surface section is located between the first surface section and the third surface section and is recessed towards one side of the impeller along a rotating direction with respect to the first surface section and the third surface section. The twisted blades are of a double-twisted structure, and the surfaces of the blades extend in a plurality of directions, so that the blades effectively adapt to change of airflow at multi-direction speeds, flowing separation of airflow in an internal flow channel is reduced, production of a large amount of eddy current is avoided, and then the airflow flowing condition of the whole blower is optimized.

Description

Impeller, mixed flow fan and air conditioner

Cross-references to related applications

This application is based on the application with the CN application number 202010063829.1 and the filing date of January 20, 2020, and claims its priority. The disclosure of the CN application is hereby incorporated into this application as a whole.

Technical field

The present disclosure 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 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 of 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 indicators of the air conditioner, the air path system of the air conditioner in the related art adopts a mixed flow fan.

Summary of the invention

In the related art that the inventor knows, since the inlet direction of the mixed flow fan is generally along the axis of the hub, the outlet direction is generally inclined to a certain angle with respect to the axis, so that the airflow in the flow channel of the mixed flow fan includes partial speeds in different directions. . However, the blades of the mixed flow fan in the related art have a smooth surface, so that airflows with different directional sub-velocities will have a serious boundary separation phenomenon when passing through the surface of the blade, which will lead to the generation of eddy currents.

In view of this, the present disclosure provides an impeller, a mixed flow fan, and an air conditioner to avoid separation of air flow.

The first aspect of the present disclosure provides an impeller, including:

The wheel cover includes an inner cavity penetrating along the axis, and the inner cavity has an air inlet end and an air outlet end that are arranged oppositely;

The wheel hub is arranged in 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 are twisted blades. The surface of the twisted blades includes a first surface section, a second surface section and a third surface section, and the second surface section is located at Between the first surface section and the third surface section and relative to the first surface section and the third surface section, it is recessed toward one side of the rotation direction of the impeller.

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

In some embodiments, the surface of the twisted blade is curved and includes a first curved section, a second curved section, and a third curved section.

In some embodiments, the blade further includes a trailing edge on one side of the air outlet, and the projection of the contour line of the trailing edge on the longitudinal projection surface is an inner concave arc, and the inner concave arc is concave toward the outer side of the blade. enter.

In some embodiments, the concave arc has a first end point and a second end point, and the length of the chord line between the first end point and the second end point ranges from [10mm, 30mm].

In some embodiments, the length of the chord line between the first end point and the second end point is 19 mm.

In some embodiments, the inner concave arc has a first end point and a second end point, and the included angle between the tangent of the inner concave arc at the first end point and the chord line is [10°, 50°].

In some embodiments, the included angle range between the tangent line of the inner concave arc line at the first end point and the chord line is 31°.

In some embodiments, the inner concave arc line has a first end point and a second end point, and the included angle between the tangent line of the inner concave arc line at the second end point and the chord line is [10°, 50°].

In some embodiments, the included angle between the tangent line of the inner concave arc line at the second end point and the chord line is 31.5°.

In some embodiments, the blade includes a blade root connected to 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 root of the blade. The contour of the outer edge of the blade is projected on a longitudinal projection plane passing through the axis. For the variable inclination curve, the angle between the tangent of the variable inclination curve and the longitudinal reference line gradually increases in the direction from the air inlet end to the air outlet end.

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

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

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

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

A second aspect of the present disclosure provides a mixed flow fan including the above-mentioned impeller.

A third aspect of the present disclosure provides an air conditioner, including the mixed flow fan described above.

Based on the technical solution provided by the present disclosure, the impeller includes a wheel cover, a hub, and a plurality of blades. The wheel cover includes an inner cavity penetrating along the axis, and the inner cavity has an air inlet and an air outlet oppositely arranged; the hub is arranged in the wheel cover A plurality of blades are connected between the inner surface of the wheel cover and the outer surface of the hub, and the blades are twisted blades. The surface of the twisted blades includes a first surface section, a second surface section and a third surface section, and the second surface section is located Between the first surface section and the third surface section and relative to the first surface section and the third surface section, it is recessed toward one side in the direction of rotation of the impeller. The twisted blade of the present disclosure has a double-twisted structure, so that the surface of the blade extends in multiple directions, thereby effectively adapting to changes in multi-directional velocity air flow, thereby reducing the flow separation of air flow in the internal flow channel, avoiding the generation of a large number of vortices and optimizing the air flow of the entire fan Flow status.

Through the following detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings, other features and advantages of the present disclosure will become clear.

Description of the drawings

In order to more clearly describe the technical solutions in the embodiments of the present disclosure or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only These are some embodiments described in the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings.

FIG. 1 is a schematic diagram of a three-dimensional structure of an impeller of an embodiment of the disclosure;

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

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

Figure 4 is a schematic structural view of the impeller shown in Figure 1 with the wheel cover removed;

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

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

FIG. 7 is a schematic diagram of a partial enlarged structure of the impeller in FIG. 6;

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

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

Figure 12 is a vector diagram of the velocity in the inlet flow channel of a mixed flow fan in the related art;

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

Detailed ways

In order to make the objectives, technical solutions, and advantages of the present disclosure clearer, the embodiments of the present disclosure will be further described in detail below through embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described here are only used to explain the present disclosure, and not used to limit the present disclosure.

The specific structure of the impeller of the embodiment of the present disclosure will be described in detail below based on FIGS. 1 to 13.

As shown in Figure 1, Figure 2, Figure 4 and Figure 5, the impeller of the embodiment of the present disclosure includes a hub 1, a wheel cover 3 and a plurality of blades 2, wherein the wheel cover 3 includes an inner cavity penetrating along an axis, and the inner cavity There are oppositely arranged air inlet and outlet ends; 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 hub 1. The blade 2 is a twisted blade. The twisted blade includes three surface segments from the air inlet end to the air outlet end. The three curved surface segments are a first surface segment, a second surface segment, and a third surface segment. The second surface segment is located in the first surface segment and the third surface segment. Between the third surface segments and relative to the first surface segment and the third surface segment, they are recessed toward one side in the direction of rotation of the impeller. That is to say, the twisted blade in the embodiment of the present disclosure has a double-twisted structure, so that the surface of the blade extends in multiple directions, thereby effectively adapting to the change of the multi-directional velocity air flow, thereby reducing the flow separation of the air flow in the internal flow channel, and avoiding the generation of a large number of vortices. Optimize the air flow of the entire fan.

The transition between the first surface section, the second surface section and the third surface section of this embodiment is made through a circular arc surface, so that the airflow of this embodiment does not change its speed direction suddenly when flowing along the wall surface, thereby further reducing the eddy current. produce.

Specifically, as shown in FIG. 5, each surface segment of the twisted blade in this embodiment is a curved surface segment, which is a first curved surface segment 2A, a second curved surface segment 2B, and a third curved surface segment 2C, respectively. Setting each surface segment as a curved surface segment makes the surface of the twisted blade of this embodiment more adaptable to airflow with multiple speed directions.

In some embodiments, the blade 2 of this embodiment further includes a trailing edge 23 on the side of the air outlet. As shown in FIG. 9, the projection of the trailing edge 23 on the longitudinal projection surface is a concave arc. And the inner concave arc line is concave toward the outside of the blade. 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 approximate shape of the trailing edge 23 of the blade 2 is a concave surface to adapt to the airflow in different speed directions so as to avoid the formation of vortex when the airflow is discharged.

In actual application, the two end points of the concave arc are the first end point C and the second end point D, and the length range of the chord line CD is [10mm, 30mm]. The range of the included angle e between the tangent line of the inner concave arc at the first end point C and the chord line is [10°, 50°]. The included angle f between the tangent of the inner concave arc at the second end point D and the chord line is [10°, 50°]. In some embodiments, the length of the chord line CD of this embodiment is 19 mm, the angle e between the tangent line of the inner concave arc at the first end point C and the chord line is 31°, and the inner concave arc The angle f between the tangent line at the second end point D and the chord line is 31.5°.

As shown in FIG. 5, the blade 2 includes a blade root 24 connected to the outer surface of the hub 1 and extending along the outer surface of the hub 1 and a blade outer edge 22 opposite to 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, and the angle between the tangent of the variable inclination curve and the longitudinal reference line gradually increases in the direction from the inlet end to the outlet end. Big.

The projection of the outer edge 22 of the blade on the longitudinal projection surface of the embodiment of the present disclosure is a variable pitch curve, and the angle between the tangent of the variable pitch curve and the longitudinal reference line gradually increases, so that the airflow in the flow channel of the blade of the present embodiment is gradually increased. Guide to avoid large pressure gradients and reduce flow losses.

It should be noted here that the transverse projection plane of the embodiment of the present disclosure is perpendicular to the axis L of the impeller. The longitudinal projection plane of the embodiment of the present disclosure needs to pass through the axis L of the impeller. And for any blade, the longitudinal projection surface refers to the longitudinal projection surface of the blade facing the direction of the axis L. For example, among the blades 2 in FIG. 4, the longitudinal projection surface of the blade located on the front side of the hub 1 and in the middle is the longitudinal projection surface parallel to the paper surface. In other words, for different blades, the position of the longitudinal projection surface is different. The longitudinal reference line of the embodiment of the present disclosure 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 third end point B on the side of the air inlet end and a first end point C on the side of the air outlet end, wherein the variable inclination curve is at the third end point. The range of the entrance angle d between the tangent line at B and the longitudinal reference line is [20°, 85°]. The range of the exit angle g between the tangent line of the variable inclination curve at the first end point C and the longitudinal reference line is [10°, 70°].

In some embodiments, 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 of this embodiment has an inflection point and includes a first curve segment and a second curve segment located on both sides of the inflection point, and the radius of curvature R1 of the first curve segment and the radius of curvature R2 of the second curve segment are different. The range of the ratio between is [0.2, 5].

In some embodiments, experiments have shown that when the radius of curvature R1 of the first curve segment is set to 125 mm and the radius of curvature R2 of the second curve segment is set to 38 mm, the flow loss of the airflow is the smallest.

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

Specifically, the second S-shaped curve includes a fourth end point A on the side of the air inlet end and a second end point D on the side of the air outlet end, wherein the tangent and transverse lines of the second S-shaped curve at the fourth end point A are 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 horizontal reference line is [10° , 65°]. The horizontal reference line here is not an absolute horizontal reference line, but is located in a longitudinal projection plane passing through the axis L and perpendicular to the axis L.

In some embodiments, the entrance angle m between the tangent line of the second S-shaped curve at the fourth end point A and the transverse reference line is 91°, and the tangent line of the second S-shaped curve at the second end point D and the transverse reference line is 91°. The entrance angle n between the lines is 24°.

As shown in Fig. 5, the blade 2 further includes a leading edge 21 located on one side of the air inlet end. As shown in FIGS. 6 and 7, the projection of the contour line of the front edge 21 on the horizontal projection plane perpendicular to the axis L is a concave curve. That is to say, looking down on the impeller from above, the shape of the leading edge 21 of the blade 2 is roughly concave, so as to reduce the air intake resistance and direct impact on the blades to improve the air intake smoothness and make the fan run with high efficiency and low noise.

It should be noted here that the lateral projection surface of the embodiment of the present disclosure is not an absolute lateral projection surface, but a relative lateral projection surface. No matter how the impeller is placed, the lateral projection surface is perpendicular to the axis L of the impeller.

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 disclosure will be described in detail below based on FIGS. 1 to 11.

As shown in Figure 1, the impeller of this embodiment includes a hub 1, a wheel cover 3 and a plurality of blades 2; among them. The wheel cover 3 has an inner cavity penetrating along the axis, and the inner cavity has an air inlet end and an air outlet end respectively located at two 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 Figure 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 Figure 5, 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 to the root 23 of the blade.

As shown in Figures 6 and 7, in the top view of the impeller, the leading edge 21 of this embodiment has a first intersection E that intersects the hub 1 and a second intersection F that intersects the wheel cover 3. At this time, the leading edge 21 It is a concave curve connecting the first intersection E and the second intersection F. In other words, the projection of the contour line of the front edge 21 in the transverse projection plane perpendicular to the axis L is a concave curve. The projection of the blades 21 of the impeller in this embodiment on the transverse projection plane is a concave curve to reduce the air intake resistance and the direct impact of the air flow on the blades to optimize the air intake conditions, which is helpful for the fan to operate with high efficiency and low noise.

In this embodiment, the direction of the concave curve is consistent with the direction of rotation of the impeller. Specifically, as shown in Fig. 7, the impeller of this embodiment rotates counterclockwise. Such a setting can further improve the fluency of air intake.

Specifically, the concave curve of this embodiment includes a leaf-shaped line. For example, the following equation can be used to obtain the leaf profile 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 the parameter used to adjust the chord length of the concave curve; p=±1 is used to adjust the direction of the concave curve; the value range of t is (0,1); m ₁ , n ₁ , n _{2 are} used to adjust The degree of curvature of the concave curve.

In this embodiment, as shown in FIGS. 6 and 7, the range of 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 [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 bending 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 bending point O here refers to the point on the concave curve with the largest distance from the chord line.

In this embodiment, the range of the distance c between the maximum bending line O and the chord 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 front edge 21 on the longitudinal projection plane is an oblique line, and the vertical distance between the oblique line and the horizontal reference line gradually increases in the extending direction from the radial inner side to the radial outer side. The lateral reference line here refers to the lateral reference line that passes through the radially inner end point of the inclined line and is perpendicular to the axis. Preferably, the range of the maximum vertical distance h between the inclined line and the lateral reference line is [0, 15 mm]. More preferably, h is 6.7 mm.

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

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

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

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

Through the above optimized design, as shown in FIG. 2, the internal flow channel of the mixed flow fan of this embodiment has a special form, so that the airflow flows in along the impeller axis L and flows out obliquely. Specifically, in the longitudinal projection plane, the impeller flow channel of this embodiment is roughly a flow channel curve M1M2, and the range of the included angle α between the tangent line of the flow channel curve M1M2 at the air inlet end and the longitudinal reference line is [0 , 30°], the range of the angle β between the tangent line at the air outlet end and the horizontal reference line is [0, 80°]. Optionally, the angle α between the tangent line at the air inlet end and the longitudinal reference line of the runner curve M1M2 is 10 degrees, and the angle β between the tangent line at the air outlet end and the horizontal reference line is 40 degrees. .

A simulation experiment was performed on the mixed flow fan of this embodiment and compared with the simulation of the mixed flow fan before optimization. The experimental data is shown in the following table. In the simulation experiment, the noise measurement point is 0.5m from the outlet of the fan.

From the simulation data, it can be seen that when the air volume is close, the fan speed is significantly reduced after optimization, the noise value is reduced at 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. Through the comparison of the velocity vector diagrams shown in Figure 12 and Figure 13, it can also be found that after optimization, the direction of airflow along the guide ring changes significantly, the airflow shifts to the middle of the flow channel, and the airflow is rectified to make the flow velocity distribution more uniform. , The speed gradient slows down significantly.

It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or a central element may also be present. When an element is considered to be "connected" to another element, it can be directly connected to the other element or an intermediate element may be present at the same time. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

In the description of the present disclosure, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance.

At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" cited in this specification are only for ease of description, not to limit the text. Disclosure of the implementable scope, and the change or adjustment of the relative relationship, shall be regarded as the implementable scope of the present disclosure without substantial changes to the technical content.

The above-mentioned embodiments only express several implementation manners of the present disclosure, and their descriptions are relatively specific and detailed, but they should not be understood as limiting the scope of the present disclosure. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present disclosure, several modifications and improvements can be made, and these all fall within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the appended claims.

Claims

An impeller, including:

The wheel cover (3) includes an inner cavity penetrating along the axis, and the inner cavity has an air inlet end and an air outlet end that are arranged oppositely;

The wheel hub (1) is arranged in the wheel cover (3); and

A plurality of blades (2) are connected between the inner surface of the wheel cover (3) and the outer surface of the hub (1), and the blades (2) are twisted blades, and the surface of the twisted blades includes The first surface section, the second surface section and the third surface section, the second surface section is located between the first surface section and the third surface section and is opposite to the first surface section and the first surface section. The three-surface section is recessed toward one side in the direction of rotation of the impeller.
The impeller according to claim 1, wherein the transition between the first surface section, the second surface section and the third surface section is through a circular arc surface.
The impeller according to claim 1, wherein the surface of the twisted blade is curved and includes a first track section, a second curved section, and a third curved section.
The impeller according to claim 1, wherein the blade (2) further comprises a trailing edge (23) located on one side of the air outlet, and the contour line of the trailing edge (23) passes through the axis. The projection on the longitudinal projection surface is an inner concave arc, and the inner concave arc is concave toward the outside of the blade.
The impeller according to claim 4, wherein the concave arc has a first end point (C) and a second end point (D), the first end point (C) and the second end point (D) The length range of the chord line between) is [10mm, 30mm].
The impeller according to claim 5, wherein the length of the chord line between the first end point (C) and the second end point (D) is 19 mm.
The impeller according to claim 4, wherein the concave arc line has a first end point (C) and a second end point (D), and the concave arc line is at the first end point (C). The range of the included angle (e) between the tangent line and the chord line is [10°, 50°].
The impeller according to claim 7, wherein the angle (e) between the tangent of the inner concave arc at the first end point (C) and the chord line is 31°.
The impeller according to claim 4, wherein the range of the included angle (f) between the tangent line of the inner concave arc line at the second end point (D) and the chord line is [10°, 50°] .
The impeller according to claim 9, wherein the angle (f) between the tangent line of the inner concave arc at the second end point (D) and the chord line is 31.5°.
The impeller according to any one of claims 1 to 10, wherein the blade comprises a blade root (24) connected to the outer surface of the hub (1) and extending along the outer surface of the hub (1) And the blade outer edge (22) opposite to the blade root (24), the contour line of the blade outer edge (22) is projected as a variable pitch curve on the longitudinal projection plane passing through the axis (L) 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 impeller according to claim 11, wherein the variable inclination curve is a first S-shaped curve.
The impeller according to claim 11, wherein the projection of the blade root (24) on the longitudinal projection surface is a second S-shaped curve.
The impeller according to any one of claims 1 to 10, wherein the blade (2) further comprises a leading edge (21) located on one side of the air inlet end, and a contour line of the leading edge (21) The projection on the transverse projection plane perpendicular to the axis (L) is a concave curve.
The impeller according to claim 1, wherein the number of the blades (2) is 6 to 20.
A mixed flow fan, comprising the impeller according to any one of claims 1 to 15.
An air conditioner, comprising the mixed flow fan according to claim 16.