Axial flow impeller and air conditioner

Abstract

The application provides an axial flow impeller and an air conditioner. The axial flow impeller comprises a hub and a cascade which is uniformly spaced and installed on the outer periphery of the hub. The cascade comprises a pressure surface, a suction surface, a trailing edge surface, a tip surface and a leading edge surface. The outer contour of the cascade is formed by the trailing edge surface, the tip surface and the leading edge surface in sequence. The leading edge surface is on the same side of the rotating direction of the cascade, and the trailing edge surface is on the opposite side of the rotating direction of the cascade. The projection of the trailing edge surface on the normal plane of the hub axis is a trailing edge contour line which is composed of at least four lines with different curvatures in sequence, i.e., ab, bc, cd and de. The ab is a quintic polynomial curve, the bc is a straight line, the cd is a quartic polynomial curve, and the de is a straight line. The trailing edge contour line of the trailing edge surface is optimized from the perspective of bionics, which can improve the shedding of the air flow on the line segment with different curvatures, reduce the broadband noise, and thus help to reduce the noise.

Description

Technical Field

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

[0002] Air conditioners are an indispensable household appliance in people's daily lives. The outdoor unit of an air conditioner uses an axial impeller for heat dissipation and airflow. Driven by a motor, the axial impeller rotates, generating airflow that expels the heat generated by the outdoor unit to the outside. During rotation, the axial impeller often experiences mechanical losses, volumetric losses, and flow losses. Therefore, the airflow and efficiency generated by the axial impeller affect the heating or cooling capacity of the air conditioner. Furthermore, the axial impeller generates considerable noise during rotation; rotational noise and eddy current noise are the main noise sources of the axial impeller, significantly reducing the user's experience.

[0003] Axial flow impellers include pressure surfaces, suction surfaces, trailing edge surfaces, tip surfaces, and leading edge surfaces. Existing technologies lack sufficient optimization design for the trailing edge surface curve, resulting in significant noise and obstructed airflow as the airflow passes over it during impeller rotation. Summary of the Invention

[0004] In view of this, the present invention aims to propose an axial flow impeller that optimizes the design of the trailing edge surface from a biomimetic perspective. The trailing edge profile of the trailing edge surface is composed of at least four lines with different curvatures, thereby improving the vortex scale excited by the trailing edge surface, thus improving the generation frequency and reducing the noise of the axial flow impeller.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] An axial flow impeller includes a hub and multiple blade cascades evenly spaced on the outer periphery of the hub. Each blade cascade comprises a pressure surface, a suction surface, a trailing edge surface, a tip surface, and a leading edge surface. The outer contour of the blade cascade is formed by sequentially connecting the trailing edge surface, the tip surface, and the leading edge surface. The projection of the trailing edge surface onto the normal plane of the hub axis is a trailing edge profile line, which is composed of at least four lines with different curvatures: ab, bc, cd, and de. The ab segment is a fifth-order polynomial curve, the bc segment is a straight line, the cd segment is a fourth-order polynomial curve, and the de segment is a straight line. Optimizing the trailing edge profile line of the trailing edge surface from a biomimetic perspective can improve the airflow drop across the line segments with different curvatures, reduce broadband noise, and thus help reduce noise.

[0007] Segment ab is a fifth-order polynomial curve, segment bc is a straight line, segment cd is a fourth-order polynomial curve, and segment de is a straight line. In segment ab, as the distance between the trailing edge surface and the hub increases, the airflow gradually detaches later; the airflow detaches latest between segments bc. In segment cd, as the distance between the trailing edge surface and the hub increases, the airflow gradually detaches earlier. However, in segment de, although the airflow detaches earlier as the distance between the trailing edge surface and the hub increases, the detachment is faster than after segment cd, with the airflow detaching at points a and e almost simultaneously. By continuously changing the airflow detachment intensity along the blade root to the blade tip, and making the airflow detach more rapid in the final segment de, the airflow dissipation and sound wave scattering of the axial impeller can be effectively accelerated. This improves the flow efficiency of the axial impeller, achieves a larger air volume, and further reduces the noise of the axial impeller, thus enhancing the user experience.

[0008] Furthermore, the installation angle θ of the axial flow impeller is 20°≤θ≤35°, where θ is the angle between the chord line and the normal plane of the hub axis. Optimizing the installation angle θ helps to increase the airflow velocity through the outlet channel and improve the efficiency of the axial flow impeller.

[0009] Furthermore, the axial flow impeller includes an inlet airflow angle β1 and an outlet airflow angle β2, wherein the inlet airflow angle β1 is 8°≤β1≤30°, and the outlet airflow angle β2 is 35°≤β2≤55°. By setting two different airflow angles, the airflow resistance experienced by the impeller blades is reduced, thereby reducing the load on the motor.

[0010] Furthermore, the inlet airflow angle β1 is 15°, and the outlet airflow angle β2 is 40°. This makes the area of ​​the airflow inlet channel smaller than the area of ​​the airflow outlet channel. As the airflow passes through this channel, the flow velocity decreases, the pressure increases, and the noise level at the outlet channel is reduced.

[0011] Furthermore, the airflow deflection angle Δβ of the axial impeller is equal to the outlet airflow angle β2 minus the inlet airflow angle β1, and the airflow deflection angle Δβ is 5° ≤ Δβ ≤ 47°. By using an inlet channel area smaller than the outlet channel area, an expansion-type flow channel is formed, optimizing the airflow field and helping to reduce the noise of the axial impeller.

[0012] Furthermore, at the trailing edge surface, the pressure surface and the suction surface are connected by an inclined transition. This inclined transition replaces the blunt structure of the prior art, guiding the airflow and reducing or essentially eliminating the strong vortex flow from the suction surface to the pressure surface, thereby improving the efficiency of the axial impeller and reducing noise.

[0013] Furthermore, the outermost endpoint of the pressure surface away from the hub axis is C, and the outermost endpoint of the suction surface away from the hub axis is D. C extends downwards at an angle along the blade rotation direction to D. This can weaken the flow separation that occurs when the airflow passes through this location.

[0014] Furthermore, the distance between C and D along the hub axis is L1, and the distance between C and D perpendicular to the hub axis is L2. L1 is 10mm ≤ L1 ≤ 16mm, and L2 is 12mm ≤ L2 ≤ 16mm. Optimizing L1 and L2 minimizes airflow separation and suppresses noise.

[0015] Compared with the prior art, the axial flow impeller of the present invention has the following advantages:

[0016] (1) The axial impeller of the present invention designs the trailing edge profile of the trailing edge surface as being composed of at least four lines with different curvatures. From a biomimetic perspective, it reduces broadband noise and reduces airflow resistance, giving the axial impeller higher aerodynamic performance. By continuously changing the airflow shedding intensity of the trailing edge surface, it improves the flow efficiency of the axial impeller, obtains a larger air volume, and further reduces the noise of the axial impeller, thereby enhancing the user's experience.

[0017] (2) The axial flow impeller of the present invention improves the airflow speed through the outlet channel by optimizing the installation angle θ, thereby increasing the efficiency of the axial flow impeller.

[0018] (3) The axial flow impeller of the present invention adjusts the inlet airflow angle β1 and the outlet airflow angle β2 so that the area of ​​the inlet channel is smaller than that of the outlet channel, forming an expansion channel. When the airflow passes through this channel, the flow velocity decreases and the pressure increases, resulting in less noise at the outlet channel.

[0019] (4) The axial flow impeller of the present invention weakens the flow separation that occurs when the airflow flows from the suction surface to the pressure surface by optimizing L1 and L2, and improves the noise sound pressure level hump phenomenon at the trailing edge surface.

[0020] Another aspect of the present invention provides an air conditioner comprising the aforementioned axial flow impeller, wherein the axial flow impeller is disposed on the outdoor unit of the air conditioner. The advantages of this air conditioner and the aforementioned axial flow impeller over the prior art are the same and will not be repeated here. Attached Figure Description

[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0022] Figure 1This is a schematic diagram of the structure of an axial flow impeller according to the present invention;

[0023] Figure 2 The projection of the hub and blades of the present invention onto the normal plane of the hub axis;

[0024] Figure 3 A graph showing the curves of the first curve and the trailing edge contour line;

[0025] Figure 4 A bottom view of an axial flow impeller as described in the invention;

[0026] Figure 5 This is a side view of an axial flow impeller according to the present invention;

[0027] Figure 6 This is a schematic diagram of the cross-section of the blade cascade where the center circle has been cut off.

[0028] Figure 7 for Figure 6 A magnified view of a portion at point A.

[0029] Explanation of reference numerals in the attached figures:

[0030] 1. Hub; 2. Blade cascade; 3. Blade root; 4. Blade tip; 5. Pressure surface; 6. Suction surface; 7. Trailing edge surface; 8. Blade tip surface; 9. Leading edge surface; 10. Chord line; 11. Center circle; 12. Leading edge line; 13. Trailing edge line; 14. Hub axis. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. The embodiments described herein are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0032] It should be noted that the terms "upper," "lower," "left," "right," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0033] like Figure 1 and Figure 4-5The illustration shows an axial flow impeller comprising a hub 1 and blade cascades 2. The hub 1 is cylindrical. Multiple blade cascades 2 are evenly spaced and installed on the outer periphery of the hub 1. Driven by a motor, the blade cascades 2 rotate clockwise or counterclockwise around the hub axis 14. In this application, the number of blade cascades 2 is three.

[0034] The side of the blade cascade 2 connected to the hub 1 is the blade root 3, and the side of the blade cascade 2 away from the hub 1 is the blade tip 4. The blade cascade 2 includes a pressure surface 5, a suction surface 6, a trailing edge surface 7, a blade tip surface 8, and a leading edge surface 9. In the axial direction of the hub 1, pressure surface 5 and suction surface 6 are formed on both sides of the blade cascade 2, respectively, and the pressure surface 5 and suction surface 6 are arranged opposite to each other. When the hub 1 drives the blade cascade 2 to rotate, the surface of the blade cascade 2 facing the airflow is the suction surface 6, and the surface facing away from the airflow is the pressure surface 5. The outer contour of the blade cascade 2 is formed by sequentially connecting the trailing edge surface 7, the blade tip surface 8, and the leading edge surface 9. The leading edge surface 9 and the trailing edge surface 7 are respectively provided on both sides of the blade cascade 2 along the airflow direction, and both the leading edge surface 9 and the trailing edge surface 7 are connected to the hub 1. The leading edge surface 9 and the blade cascade 2 rotate in the same direction, and the trailing edge surface 7 is located on the opposite side of the rotation direction of the blade cascade 2. An air intake channel is formed between the leading edge curved surfaces 9 of adjacent blade cascades 2, and an air outlet channel is formed between the trailing edge curved surfaces 7 of adjacent blade cascades 2.

[0035] For the trailing edge surface 7, the projection of the trailing edge surface 7 onto the normal plane of the hub axis 14 is the trailing edge profile line. The trailing edge profile line is composed of at least four lines with different curvatures, namely segments ab, bc, cd, and de. The trailing edge profile line formed by different curvature combinations can improve the airflow drop of different line segments and reduce noise generation.

[0036] For ease of description, the curve mirrored by the curve formed by the trailing edge contour is defined as the first curve.

[0037] like Figure 2 The diagram shows the projections of hub 1 and blade 2 onto the normal plane of hub axis 14. The center of the projection of hub 1 onto this normal plane is the origin, and x is the inverse value of the horizontal distance from any point on the trailing edge profile to the center. The horizontal direction referred to here is... Figure 2 The direction parallel to the paper surface. The first curve is specifically... Figure 3 The curve to the left of the y-axis, the actual curve corresponding to the trailing edge contour is the curve formed by the mirror image of the first curve, that is... Figure 3 The curve to the right of the y-axis. From the blade root 3 to the blade tip 4, the trailing edge profile is composed of segments ab, bc, cd, and de. Each point on the trailing edge profile lies on the mirror image of the equation fitted to the first curve. Due to the presence of hub 1, the starting point of the first curve is not at the origin. Figure 3 This is the curve without considering the radius of hub 1.

[0038] Inspired by the "silent" flight of owls and the "quiet" swimming of humpback whales, the applicant has adopted a biomimetic optimization design for the trailing edge profile of the axial flow impeller. From a biomimetic perspective, this reduces broadband noise and gives the axial flow impeller higher aerodynamic performance. While ensuring airflow, it reduces drag, allowing the airflow generated by the rotation of the blade cascade 2 to achieve greater pressure and flow rate, and reducing vortex generation. Segment ab is a fifth-order polynomial curve, segment bc is a straight line, segment cd is a fourth-order polynomial curve, and segment de is a straight line. Furthermore, segment bc is a horizontal straight line, and segment de is an inclined linear straight line. The trailing edge profile is composed of a combination of linear and non-linear lines, which can improve the vortex scale excited by the trailing edge surface 7 during airflow discharge, thereby improving the sound source frequency and reducing the noise generated during the rotation of the axial flow impeller. Trailing edge profiles formed by different curvatures can improve airflow shedding. In segment ab, as the distance between the trailing edge surface 7 and the hub 1 increases, the airflow gradually detaches with a delayed rate; the airflow detaches latest between segments bc; in segment cd, as the distance between the trailing edge surface 7 and the hub 1 increases, the airflow gradually detaches earlier; and in segment de, although the airflow detaches earlier than in segment cd, the detachment is more rapid than in segment de, with the airflow detaching at points a and e almost simultaneously. By continuously changing the airflow detachment intensity of the trailing edge surface 7 along the direction from the blade root 3 to the blade tip 4, and by making the airflow detach more rapid in the final segment de, the airflow dissipation and sound wave scattering of the axial impeller can be effectively accelerated. This improves the flow efficiency of the axial impeller, achieves a larger air volume, and further reduces the noise of the axial impeller, thus enhancing the user experience.

[0039] The installation angle θ of the axial flow impeller of the present invention is 20°≤θ≤35°. Further, θ is 27°. The installation angle θ is the angle between the chord line 10 and the normal plane of the hub axis 14. Optimizing the installation angle θ helps to increase the airflow velocity through the outlet channel, thereby increasing the efficiency of the axial flow impeller. The installation angle θ can be determined based on the overall dimensions of the axial flow impeller, the specific installation environment, and the usage scenario, or it can be obtained through multiple tests in simulation experiments.

[0040] The projection of the axial impeller onto the normal plane of the hub axis 14 is as follows: Figure 4The diagram shows a bottom view of the axial flow impeller. The center of the projection of hub 1 in this direction is the center of the circle. The distance between the center of the circle and the outermost contour of blade cascade 2 is the radius of blade cascade 2. Due to the certain bending thickness of the leading edge surface 9, the projection of the leading edge surface 9 in this direction has two contour lines. The contour line with the largest distance from the center of the circle is called the leading edge contour line. A center circle 11 is obtained by drawing a circle with the center of hub 1 as the center and half the difference between the radius of blade cascade 2 and the radius of hub 1 as the radius. The intersection of center circle 11 and the leading edge contour line is the leading edge intersection point B1, and the intersection of center circle 11 and the trailing edge contour line is the trailing edge intersection point B2. The continuity between the leading edge intersection point B1 and the trailing edge intersection point B2 is the chord line 10.

[0041] like Figure 5 As shown, the leading edge line 12 passes through the leading edge intersection point B1 and is parallel to the normal plane of the hub 1 axis, while the trailing edge line 13 passes through the trailing edge intersection point B2 and is parallel to the normal plane of the hub 1 axis. The leading edge line 12 and the trailing edge line 13 are parallel to each other and perpendicular to the hub 1 axis, respectively.

[0042] Cut off the plane containing the central circle 11, and stretch and unfold any blade cascade 2 after removing the central circle 11. The cross-section of blade cascade 2 at the point where the central circle 11 was cut off is as follows. Figure 6 As shown in the diagram. On this cross-section, there are multiple inscribed circles between the arc formed by the projection of the pressure surface 5 and the arc formed by the projection of the suction surface 6. Each inscribed circle is tangent not only to the arc formed by the projection of the pressure surface 5 but also to the arc formed by the projection of the suction surface 6, and adjacent inscribed circles are also tangent to each other. The line connecting the centers of the multiple inscribed circles is the centerline. The centerline intersects the leading edge line 12 at a first point. The angle between the tangent at the first intersection point and the leading edge line 12 is the inlet airflow angle β1, which is 8°≤β1≤30°. Further, the inlet airflow angle β1 is 15°. The centerline intersects the trailing edge line 13 at a second point. The angle between the tangent at the second intersection point and the trailing edge line 13 is the outlet airflow angle β2, which is 35°≤β2≤55°. Further, the outlet airflow angle β2 is 40°. The inlet airflow angle β1 and outlet airflow angle β2 can be determined based on the overall dimensions of the axial flow impeller, as well as the specific installation environment and usage scenario, or can be obtained through multiple tests in simulation experiments. By setting two different airflow angles, the airflow resistance experienced by the blade cascade 2 is reduced, thereby reducing the load on the motor.

[0043] The airflow turning angle Δβ = outlet airflow angle β2 - inlet airflow angle β1. Further, the inlet airflow angle β1 < outlet airflow angle β2. The airflow turning angle Δβ is 5° ≤ Δβ ≤ 47°. Even further, the airflow turning angle Δβ is 25°. Since multiple blades 2 are evenly spaced on the hub 1, a suitable airflow turning angle Δβ, with the inlet airflow angle β1 < outlet airflow angle β2, makes the area of ​​the airflow inlet channel smaller than the area of ​​the outlet channel. Axial flow impellers rotate at low speeds, with Mach number Ma < 0.3, and air is considered incompressible. Using an inlet channel area smaller than the outlet channel area creates an expanding flow channel, optimizing the airflow field. Airflow through this channel reduces velocity and increases pressure, resulting in less noise at the outlet channel.

[0044] At the trailing edge surface 7, the pressure surface 5 and the suction surface 6 are connected by an inclined transition. Specifically, in Figure 6-7 In the design, the outermost endpoint of the pressure surface 5, away from the hub axis 14, is C, and the outermost endpoint of the suction surface 6, away from the hub axis 14, is D. C extends downwards at an angle along the rotation direction of the blade cascade 2 to D. The purpose of this inclined connection is to guide the airflow, weaken the flow separation that occurs when the airflow flows from the suction surface 6 to the pressure surface 5, improve the noise sound pressure level hump phenomenon at the trailing edge surface 7, and also guide the airflow, reducing or essentially eliminating the strong vortex flow of the airflow from the suction surface 6 to the pressure surface 5, thereby improving the efficiency of the axial flow impeller and reducing noise.

[0045] Specifically, the distance between C and D along the hub axis 14 is L1, and the distance between C and D along the trailing edge line 13 is L2, that is, the distance between C and D in the direction perpendicular to the hub axis 14 is L2. The specific dimensions of L1 and L2 can be determined based on the overall dimensions of the axial flow impeller and the specific installation environment and usage scenario, or can be obtained through multiple tests in simulation experiments. Furthermore, 10mm≤L1≤16mm, 12mm≤L2≤16mm. Even further, L1 is 13mm, and L2 is 14mm. Through the optimization of L1 and L2, the flow separation during airflow is minimized to the greatest extent, thus suppressing noise.

[0046] The present invention provides an axial flow impeller that, by improving the structure of the blade cascade 2, can effectively improve the flow characteristics of airflow, increase air volume, and reduce noise.

[0047] An air conditioner includes an axial flow impeller as shown in this invention. The axial flow impeller is installed inside the casing of the outdoor unit of the air conditioner. In addition to the aforementioned axial flow impeller, the air conditioner of this invention also includes conventional air conditioner components such as an indoor heat exchanger, an outdoor heat exchanger, a compressor, and a four-way valve. Since these components and their mounting structures are prior art, they will not be described in detail here.

[0048] Furthermore, the axial flow impeller of the present invention has a wide range of applications. In addition to air conditioners, it is also suitable for other low-pressure air supply environments, such as ventilation fans or guide fans.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An axial flow impeller, the axial flow impeller comprising a hub (1) and blade cascades (2), wherein multiple blade cascades (2) are provided and evenly spaced on the outer periphery of the hub (1), the blade cascades (2) comprising a pressure surface (5), a suction surface (6), a trailing edge surface (7), a blade tip surface (8), and a leading edge surface (9), the outer contour of the blade cascades (2) being formed by sequentially connecting the trailing edge surface (7), the blade tip surface (8), and the leading edge surface (9); characterized in that, The projection of the trailing edge surface (7) onto the normal plane of the hub axis (14) is the trailing edge profile line. The trailing edge profile line is composed of at least four lines with different curvatures, namely ab, bc, cd and de. The ab segment is a fifth-order polynomial curve, the bc segment is a straight line, the cd segment is a fourth-order polynomial curve and the de segment is a straight line. At the trailing edge surface (7), the pressure surface (5) and the suction surface (6) are connected by an inclined transition. The outermost end point of the pressure surface (5) away from the hub axis (14) is C, and the outermost end point of the suction surface (6) away from the hub axis (14) is D. C extends downward along the rotation direction of the blade cascade (2) to D. The distance between C and D in the direction of the hub axis (14) is L1, and the distance between C and D in the direction perpendicular to the hub axis (14) is L2. L1 is 10mm≤L1≤16mm, and L2 is 12mm≤L2≤16mm.

2. An axial flow impeller according to claim 1, characterized in that, The installation angle θ of the axial flow impeller is 20°≤θ≤35°, and the installation angle θ is the angle between the chord line (10) and the normal plane of the hub axis (14).

3. An axial flow impeller according to claim 1, characterized in that, The axial flow impeller includes an inlet airflow angle β1 and an outlet airflow angle β2, wherein the inlet airflow angle β1 is 8°≤β1≤30° and the outlet airflow angle β2 is 35°≤β2≤55°.

4. An axial flow impeller according to claim 3, characterized in that, The inlet airflow angle β1 is 15°, and the outlet airflow angle β2 is 40°.

5. An axial flow impeller according to claim 3, characterized in that, The airflow turning angle Δβ of the axial flow impeller is equal to the outlet airflow angle β2 minus the inlet airflow angle β1, and the airflow turning angle Δβ is 5°≤Δβ≤47°.

6. An air conditioner, characterized in that, The air conditioner uses an axial flow impeller as described in any one of claims 1-5, and the axial flow impeller is disposed on the outdoor unit of the air conditioner.

Images