Backward centrifugal fan, centrifugal fan and air conditioner

Abstract

The present invention relates to a backward centrifugal impeller, a centrifugal fan and an air conditioner. The backward centrifugal impeller comprises: a wheel disc (1); a wheel cover (4) arranged side by side with the wheel disc (1) along the axial direction of the centrifugal impeller and spaced apart, the wheel cover (4) being provided with an air inlet; a plurality of blades (2) arranged side by side along the circumference of the centrifugal impeller and all located between the wheel disc (1) and the wheel cover (4), the distance between the trailing edge of the blade (2) and the axis of the centrifugal impeller gradually increasing along the direction from the wheel disc (1) to the wheel cover (4). The trailing edge of the blade adopts a variable diameter design, with a larger diameter on the blade tip side and a smaller diameter on the blade root side. By modulating and balancing the power added by the blade profile at different blade heights, the unevenness and mixing degree of the airflow at the impeller outlet can be appropriately reduced, which helps to suppress noise.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning, and in particular to a backward centrifugal fan, a centrifugal fan and an air conditioner. Background Art

[0002] Currently, the trailing edges of backward-facing centrifugal rotor blades are mostly designed with a constant diameter. This design easily causes the airflow in the rotor to concentrate toward the disc side of the wind path, resulting in excessively high local wind speeds, exacerbating uneven airflow from the rotor and further inducing noise issues. Some backward-facing centrifugal rotors also use a variable trailing edge diameter design, but these designs are mostly based on two-dimensional blade deployment, resulting in suboptimal aerodynamic performance and low-noise characteristics. Summary of the Invention

[0003] The present invention aims to provide a backward centrifugal wind wheel, a centrifugal fan and an air conditioner which are beneficial to reducing noise.

[0004] According to one aspect of an embodiment of the present invention, a backward centrifugal wind wheel is provided, comprising:

[0005] Roulette;

[0006] The wheel cover is arranged side by side with the wheel disc along the axial direction of the centrifugal wind wheel and at intervals, and an air inlet is provided on the wheel cover;

[0007] Multiple blades are arranged side by side along the circumference of the centrifugal impeller and are all located between the wheel disc and the wheel cover. The distance between the trailing edge of the blade and the axis of the centrifugal impeller gradually increases from the wheel disc to the wheel cover.

[0008] In some embodiments, the distance between the end of the trailing edge of the blade close to the wheel cover and the axis of the centrifugal wind wheel is D2-2, and the distance between the end of the trailing edge of the blade close to the wheel disc and the axis of the centrifugal wind wheel is D2-1, where D2-2 / D2-1 is 1.02-1.2.

[0009] In some embodiments, the height of the centrifugal wind wheel is H, wherein D2-1 / H is 2.2-3.04.

[0010] In some embodiments, the diameter of the air inlet of the wind wheel is Ds, wherein Ds / D2-1 is 0.81-0.95.

[0011] In some embodiments, the blade has a blade outlet height h, and h / H is 0.65-0.75.

[0012] In some embodiments, the exhaust port area of ​​the centrifugal impeller is S 排 , the air inlet area of ​​the centrifugal impeller is S 进 , S 排 / S 进 It is 1.25-1.45.

[0013] In some embodiments,

[0014] The blade inlet installation angle of the blade root is 5 degrees to 15 degrees; and / or

[0015] The blade inlet installation angle of the blade top is 5 degrees to 25 degrees.

[0016] In some embodiments, the blade inlet installation angle of the blade gradually increases from the blade root to the blade tip.

[0017] In some embodiments, the blade inlet installation angle varies linearly in a direction from the blade root to the blade tip.

[0018] In some embodiments,

[0019] The blade outlet installation angle of the blade root is 35 degrees to 45 degrees; and / or

[0020] The blade outlet installation angle of the blade top is 20 degrees to 35 degrees.

[0021] In some embodiments, the blade outlet installation angle of the blade gradually decreases in a direction from the blade root to the blade tip.

[0022] In some embodiments, the blade outlet installation angle gradually increases in a rate of change from the blade root to the blade tip.

[0023] In some embodiments, the blade outlet edge of the blade is inclined in a direction opposite to the rotation direction relative to the axial direction of the centrifugal impeller in a direction from the impeller disc to the impeller cover.

[0024] In some embodiments, an inclination angle of the blade outlet relative to the axial direction of the centrifugal impeller along a direction from the blade root to the blade top gradually increases along a direction from the blade root to the blade top.

[0025] In some embodiments, the angular phase difference between the blade tip of the blade outlet edge and the blade root of the blade outlet edge in the circumferential direction is 15-25 degrees.

[0026] In some embodiments, the rate of change of the inclination angle gradually increases in a direction approaching the tip of the blade.

[0027] In some embodiments, the trailing edge of the blade is provided with a serration structure.

[0028] In some embodiments, the sawtooth structure is one of a trapezoidal shape, a triangle shape, and a sine wave shape.

[0029] In some embodiments, the distance between the trailing edge of the blade and the axis of the centrifugal impeller changes linearly in a direction approaching the wheel cover.

[0030] In some embodiments, the blade inlet diameter is D1, the centrifugal impeller outlet diameter is D2, and the inner and outer diameter ratio of the blade is D1 / D2, where

[0031] The ratio of the inner diameter to the outer diameter of the blade root near the disc is 0.65-0.75; or

[0032] The ratio of the inner diameter to the outer diameter of the blade at the top of the blade close to the wheel cover is 0.65-0.75.

[0033] In some embodiments, the inner diameter ratio increases gradually from the blade root to the blade tip.

[0034] According to another aspect of the present invention, a centrifugal fan is provided. The centrifugal fan includes the aforementioned backward centrifugal impeller.

[0035] According to another aspect of the present invention, an air conditioner is provided. The air conditioner includes the centrifugal fan described above.

[0036] By applying the technical solution of the present invention, the trailing edge of the blade adopts a variable diameter design, with a larger diameter on the top side and a smaller diameter on the root side. By modulating and balancing the power added by the blade profile at different blade heights, the unevenness of the airflow at the wind wheel outlet and the degree of mixing can be appropriately reduced, which helps to suppress noise.

[0037] Further 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0039] Figure 1 A schematic structural diagram of a backward centrifugal impeller according to an embodiment of the present invention is shown;

[0040] Figure 2 A schematic diagram of the top view of the backward centrifugal impeller according to an embodiment of the present invention is shown;

[0041] Figure 3a A parameter diagram of a backward centrifugal impeller according to an embodiment of the present invention is shown;

[0042] Figure 3b A schematic diagram showing the inlet and outlet installation angles of the blades of the backward centrifugal impeller according to an embodiment of the present invention;

[0043] Figure 4A schematic diagram showing the blade outlet inclination angle of a backward centrifugal impeller according to an embodiment of the present invention;

[0044] Figure 5 A diagram showing the distribution regularity of convex curves on the blade outlet installation angles of a backward centrifugal impeller according to an embodiment of the present invention is shown;

[0045] Figure 6 A diagram showing the distribution regularity of the convex curve of the blade outlet inclination angle of the backward centrifugal impeller according to an embodiment of the present invention is shown;

[0046] Figure 7 A schematic diagram showing a serrated structure of a trailing edge of a blade of a backward centrifugal wind wheel according to an embodiment of the present invention; and

[0047] Figure 8 A comparison diagram of technical parameters of a backward centrifugal wind wheel according to an embodiment of the present invention and a backward centrifugal wind wheel according to the prior art is shown. DETAILED DESCRIPTION

[0048] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0049] like Figures 1 to 4 As shown, the backward centrifugal impeller of this embodiment includes a wheel disc 1, a wheel cover 4 and a plurality of blades 2. The wheel cover 4 and the wheel disc 1 are arranged side by side and at intervals along the axial direction of the centrifugal impeller, and the wheel cover 4 is provided with an air inlet 6; the plurality of blades 2 are arranged side by side along the circumference of the centrifugal impeller and are all located between the wheel disc 1 and the wheel cover 4, and the distance between the trailing edge of the blade 2 and the axis of the centrifugal impeller gradually increases in the direction from the wheel disc 1 to the wheel cover 4.

[0050] In some embodiments, the distance between the trailing edge of the blade 2 and the axis of the centrifugal impeller changes linearly or curvedly in a direction approaching the wheel cover 4 .

[0051] Currently, the trailing edge of backward-facing centrifugal blades often adopts a constant diameter design, where the diameter is the distance between the blade and the impeller axis. This design easily causes the airflow in the rotor to concentrate toward the disc side of the wind path, resulting in excessively high local wind speeds, exacerbating uneven airflow from the rotor and further inducing noise issues. In this embodiment, the trailing edge of the blade adopts a variable diameter combined with a three-dimensional blade design, with a larger diameter at the top and a smaller diameter at the base. By modulating and balancing the power added by the blade profile at different blade heights, the unevenness and mixing of the airflow at the rotor outlet can be appropriately reduced, helping to suppress noise.

[0052] like Figure 1 As shown, the blade root 21 of the blade 2 is the end of the blade 2 close to the wheel disc 1 , and the blade top 22 of the blade 2 refers to the end of the blade 2 close to the wheel cover 4 .

[0053] The distance between the end of the trailing edge of the blade 2 close to the wheel cover 4 and the axis of the centrifugal wind wheel is D2-2, and the distance between the end of the trailing edge of the blade 2 close to the wheel disc 1 and the axis of the centrifugal wind wheel is D2-1. Preferably, D2-2 / D2-1 is 1.02-1.2.

[0054] In this embodiment, the centrifugal rotor features a highly flat design. The height of the centrifugal rotor is H. Preferably, D2-1 / H is 2.2-3.04. Optimizing the rotor's parameters for highly flattened design, large intake and exhaust ports not only fully utilizes the rotor's radial dimensions but also effectively reduces its axial height. This balance is achieved between expanding the airflow path and ensuring the blades' effective working area, resulting in optimal rotor aerodynamic performance and noise characteristics.

[0055] In this embodiment, the wind wheel air inlet adopts a large diameter air inlet design. The diameter of the wind wheel air inlet is Ds, and Ds / D2-1 is 0.81-0.95.

[0056] In this embodiment, the wind wheel exhaust port is designed with a large outlet height, the blade outlet height of the blade 2 is h, and h / H is 0.65-0.75.

[0057] In this embodiment, the exhaust port area of ​​the centrifugal wind wheel is S 排 , the air inlet area of ​​the centrifugal impeller is S 进 , preferably S 排 / S 进 The exhaust area of ​​the wind wheel is S 排 The area of ​​the conical surface that is rotated 360° with the generatrix of the exhaust port as the characteristic curve; the area of ​​the wind wheel air inlet S 进 It is the area of ​​a circle with diameter Ds.

[0058] The blade inlet diameter of blade 2 is D1, the outer diameter of the centrifugal impeller is D2, and the inner-outer diameter ratio of the blade is D1 / D2, wherein the inner-outer diameter ratio of the blade root of blade 2 is 0.6-0.75; the inner-outer diameter ratio of the blade top of blade 2 is 0.65-0.8.

[0059] In some embodiments, the ratio of the inner diameter to the outer diameter gradually increases from the blade root to the blade tip.

[0060] like Figure 3b As shown, taking the midline of the two-dimensional cross-section airfoil of the blade at a certain blade height as the reference, the midline intersects with the blade inlet edge at a point, and the angle formed by the tangent of the midline along the point and the tangent of the arc of the inlet edge corresponding to the point in the direction of rotation is the blade inlet installation angle in this patent. Taking the midline of the two-dimensional cross-section airfoil of the blade at a certain blade height as the reference, the midline intersects with the blade inlet edge at a point, and the angle formed by the tangent of the midline along the point and the tangent of the arc of the inlet edge corresponding to the point in the direction of rotation is the blade outlet installation angle in this patent.

[0061] The blade inlet installation angle of the blade root of the blade 2 is preferably 5 degrees to 15 degrees; the blade inlet installation angle of the blade top of the blade 2 is preferably 5 degrees to 25 degrees.

[0062] In some embodiments, the blade inlet installation angle of the blade 2 gradually increases in a direction close to the blade top of the blade 2. Preferably, the blade inlet installation angle changes linearly in a direction close to the blade top of the blade 2.

[0063] The blade outlet installation angle of the blade root of the blade 2 is preferably 35 degrees to 45 degrees; the blade outlet installation angle of the blade top of the blade 2 is preferably 20 degrees to 35 degrees.

[0064] The blade outlet installation angle of the blade 2 gradually decreases in the direction close to the blade top of the blade 2. Preferably, the blade inlet installation angle gradually increases in the direction close to the blade top of the blade 2, such as Figure 5 As shown, in a coordinate system where the horizontal coordinate is the displacement toward the blade top and the vertical coordinate is the blade outlet installation angle, the curve of the blade outlet installation angle is an upwardly convex curve.

[0065] The blade outlet edge of the blade 2 is inclined in the direction opposite to the rotation direction relative to the axial direction of the centrifugal impeller from the wheel disc 1 to the wheel cover 4. The inclination angle of the blade outlet relative to the axial direction of the centrifugal impeller gradually increases as it approaches the blade top of the blade 2.

[0066] The angle phase difference between the top of the blade outlet edge of the blade 2 and the root of the blade outlet edge in the circumferential direction is 15-25 degrees. The rate of change of the inclination angle of the blade outlet edge gradually increases from the root to the top of the blade, such as Figure 6 shown.

[0067] Through comprehensive optimization of the blade chord length, blade inlet and outlet placement angles, and blade outlet inclination angle, a small chord length blade design is adopted at the root of the blade main body, and a large chord length blade design is adopted at the top of the blade main body. At the same time, the blade outlet placement angle and outlet inclination angle adopt an upward convex curve distribution law, which can not only modulate and distribute the blade profile power at different blade heights, but also suppress the large-scale "jet-wake" structure generated near the wheel cover side of the blade outlet, resulting in a large momentum loss and induced aerodynamic noise problems.

[0068] Because variable diameter designs often result in a certain amount of airflow attenuation, the present invention adds trailing edge serrations to the blade outlet to mitigate this effect. This also improves boundary layer separation resistance, increases rotor efficiency, reduces operating aerodynamic noise, and, to a certain extent, reduces blade material costs while maintaining the same technical specifications.

[0069] The outlet edge of the blade is located at the trailing edge of the blade. The trailing edge of the blade 2 is provided with a sawtooth structure, which is one of a trapezoidal, triangular and sine wave shape. Figure 7 As shown, the length of the upper base of the trapezoid is c, the length of the lower base of the trapezoid is d, and the length of the waist of the trapezoid is e, wherein e / D2 is 0.004-0.022; d / D2 is 0.004-0.022; and the preferred range of c / D2 is 0.002-0.07.

[0070] In this embodiment, the blade cross-section adopts the long-eared owl airfoil as the basic airfoil, and further undergoes deformation design to modify its thickening distribution law to enhance the structural strength of the middle and rear sections of the airfoil.

[0071] like Figure 8 As shown, the horizontal axis is the air volume and the vertical axis is the noise. Compared with the centrifugal fan in the prior art, the backward centrifugal wind wheel of this embodiment increases the air volume, improves the wind wheel working efficiency, reduces power consumption, significantly improves the wind noise level, and reduces the wind wheel material cost.

[0072] According to another aspect of the present invention, a centrifugal fan is provided. The centrifugal fan includes the aforementioned backward centrifugal impeller.

[0073] According to another aspect of the present invention, an air conditioner is provided. The air conditioner includes the centrifugal fan described above.

[0074] The above are merely exemplary embodiments of the present invention and are 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 in the scope of protection of the present invention.

Claims

1. A backward centrifugal wind wheel, characterized in that: include: Roulette (1); A wheel cover (4) is arranged side by side with the wheel disc (1) along the axial direction of the centrifugal wind wheel and spaced apart from each other, and an air inlet (6) is provided on the wheel cover (4); A plurality of blades (2) are arranged side by side along the circumference of the centrifugal impeller and are all located between the wheel disc (1) and the wheel cover (4), and the distance between the trailing edge of the blade (2) and the axis of the centrifugal impeller gradually increases in the direction from the wheel disc (1) to the wheel cover (4). The exhaust port area of ​​the centrifugal wind wheel is S 排 The air inlet area of ​​the centrifugal wind wheel is S 进 , S 排 / S 进 is 1.25-1.45, The blade inlet installation angle of the blade (2) gradually increases in the direction from the blade root to the blade top of the blade (2), and the blade inlet installation angle changes linearly in the direction from the blade root to the blade top of the blade (2). The blade outlet edge of the blade (2) is inclined in a direction opposite to the rotation direction relative to the axial direction of the centrifugal impeller from the direction of the wheel disc (1) to the wheel cover (4), and the inclination angle of the blade outlet relative to the axial direction of the centrifugal impeller along the direction from the blade root of the blade (2) to the blade top gradually increases. The blade outlet installation angle of the blade (2) gradually decreases in the direction from the blade root (21) to the blade top (22) of the blade (2). The blade outlet installation angle has a gradually increasing rate of change along the direction from the blade root to the blade top of the blade (2).

2. The backward centrifugal impeller according to claim 1, characterized in that: The distance between the end of the trailing edge of the blade (2) close to the wheel cover (4) and the axis of the centrifugal wind wheel is D2-2, and the distance between the end of the trailing edge of the blade (2) close to the wheel disc (1) and the axis of the centrifugal wind wheel is D2-1, wherein D2-2 / D2-1 is 1.02-1.

2.

3. The backward centrifugal impeller according to claim 2, characterized in that: The height of the centrifugal wind wheel is H, wherein D2-1 / H is 2.2-3.

04.

4. The backward centrifugal impeller according to claim 1, characterized in that: The diameter of the air inlet (6) of the wind wheel is Ds, wherein Ds / D2-1 is 0.81-0.

95.

5. The backward centrifugal impeller according to claim 1, characterized in that: The blade outlet height of the blade (2) is h, and h / H is 0.65-0.

75.

6. The backward centrifugal impeller according to claim 1, characterized in that: The blade inlet installation angle of the blade root portion (21) of the blade (2) is 5 degrees to 15 degrees; and / or The blade inlet installation angle of the blade top (22) of the blade (2) is 5 degrees to 25 degrees.

7. The backward centrifugal impeller according to claim 1, characterized in that: The blade outlet installation angle of the blade root portion (21) of the blade (2) is 35 degrees to 45 degrees; and / or The blade outlet installation angle of the blade top (22) of the blade (2) is 20 degrees to 35 degrees.

8. The backward centrifugal impeller according to claim 1, characterized in that: The angular phase difference in the circumferential direction between the blade top portion of the blade outlet edge of the blade (2) and the blade root portion of the blade outlet edge is 15-25 degrees.

9. The backward centrifugal impeller according to claim 1, characterized in that: The rate of change of the inclination angle gradually increases from the blade root to the blade top.

10. The backward centrifugal impeller according to claim 1, characterized in that: The trailing edge of the blade (2) is provided with a serration structure.

11. The backward centrifugal impeller according to claim 10, characterized in that: The sawtooth structure is one of a trapezoidal shape, a triangle shape and a sine wave shape.

12. The backward centrifugal impeller according to claim 1, characterized in that: The distance between the trailing edge of the blade (2) and the axis of the centrifugal impeller changes linearly in a direction approaching the wheel cover (4).

13. The backward centrifugal impeller according to claim 1, characterized in that: The blade (2) has an inlet diameter of D1, an outlet diameter of D2, and an inner / outer diameter ratio of D1 / D2. The ratio of the inner diameter to the outer diameter of the blade (2) at the blade root close to the wheel disc (1) is 0.65-0.75; or The ratio of the inner diameter to the outer diameter of the blade (2) at the top of the blade close to the wheel cover (4) is 0.65-0.

75.

14. The backward centrifugal impeller according to claim 13, characterized in that: The inner-outer diameter ratio gradually increases from the blade root to the blade top.

15. A centrifugal fan, characterized in that: The invention comprises the backward centrifugal impeller according to any one of claims 1 to 14.

16. An air conditioner, characterized in that: Including the centrifugal fan according to claim 15.

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