Blade, centrifugal fan and electrical equipment

Abstract

The present invention relates to a blade, a centrifugal fan, and an electrical device. The thickness of the blade gradually increases and then gradually decreases from one end of the trailing edge 12 of the blade to one end of the leading edge 11 of the blade, and the thickness of the trailing edge 12 of the blade is greater than 1.5 mm. The centrifugal fan includes an impeller 3 and a plurality of blades arranged on the impeller 3. The plurality of blades are evenly arranged along the circumference of the axis of the impeller 3, and the trailing edge 12 of each blade is located on the outer diameter circle of the impeller 3. The blade, centrifugal fan, and electrical device provided by the present invention have the effects of achieving high flow, low noise, and high efficiency, while also improving the injection molding strength of the blade, facilitating the mass injection molding production of blades.

Description

Technical Field

[0001] The present invention relates to the technical field of centrifugal fans, and in particular to a blade, a centrifugal fan and electrical equipment. Background Art

[0002] The fan blade is formed by connecting the leading edge, pressure side, trailing edge, and suction side of the blade end to end, with the pressure side facing the suction side. Existing centrifugal fan impeller blades are mostly designed as airfoil blades to improve fan performance. However, when designed in this way, the trailing edge of the blade is very thin, resulting in low strength and easy breakage. This is not only not conducive to injection molding for mass production, but also leads to reduced centrifugal fan efficiency, increased noise, and reduced flow. Summary of the Invention

[0003] In response to the problem of insufficient strength of existing blades, the present invention proposes a blade, a centrifugal fan and an electrical device, which can achieve the technical effects of large flow, low noise and high efficiency, and are also convenient for mass production of blades.

[0004] A blade, wherein the thickness of the blade gradually increases and then gradually decreases from one end of the trailing edge of the blade to one end of the leading edge of the blade, and the thickness of the trailing edge of the blade is greater than 1.5 mm.

[0005] In one embodiment, the pressure surface of the blade and the suction surface of the blade are both cambered surfaces, and the pressure surface is concave toward the suction surface, and the suction surface is convex away from the pressure surface.

[0006] A centrifugal fan is also provided, comprising an impeller and a plurality of blades as described in any of the above embodiments arranged on the impeller, wherein the plurality of blades are evenly distributed circumferentially along the axis of the impeller, and the trailing edge of each blade is located on the outer diameter circle of the impeller.

[0007] In one embodiment, the diameter of the cotangent circle of the leading edges of the plurality of blades is the blade inlet diameter D1, and the diameter of the cotangent circle of the trailing edges of the plurality of blades is the blade outlet diameter D2;

[0008] The blade inlet diameter D1 and the blade outlet diameter D2 satisfy: D1 / D2=0.8-0.82.

[0009] In one embodiment, the centerline length L of each blade and the blade path width t1 of the centrifugal fan satisfy: L / t1 = 2.0 to 2.2.

[0010] In one embodiment, the invention further comprises a volute, wherein the impeller is rotatably disposed inside the volute;

[0011] The profile of the volute is a spiral line, comprising a first curved segment, a second curved segment, a third curved segment and a fourth curved segment connected in sequence, wherein the first curved segment is connected to the volute tongue of the volute;

[0012] The four arc segments connected in sequence obtained based on the equilateral primitive method include a first reference segment, a second reference segment, a third reference segment and a fourth reference segment, wherein the first reference segment is connected to the volute tongue by reference;

[0013] The second curved segment, the third curved segment and the fourth curved segment are configured to coincide with the second reference segment, the third reference segment and the fourth reference segment respectively, and the first curved segment is configured as an arc segment having a curvature smaller than that of the first reference segment.

[0014] In one embodiment, the distance from the connection point of the first curved section and the volute tongue to the outer diameter circle of the impeller is the volute tongue gap t3, and the diameter of the outer diameter circle of the impeller is D2', satisfying: t3 / D2'=0.06-0.07.

[0015] In one embodiment, the second curved segment includes a first connecting segment, a first straight segment, and a second connecting segment connected in sequence, wherein the first connecting segment connects the first curved segment, and the second connecting segment connects the third curved segment;

[0016] The second reference segment includes a first reference arc segment, a second reference arc segment, and a third reference arc segment connected in sequence, wherein the first reference arc segment is connected to the first reference segment, and the third reference arc segment is connected to the third reference segment;

[0017] The first connecting segment and the second connecting segment are configured to coincide with the first reference arc segment and the third reference arc segment, respectively;

[0018] A maximum perpendicular distance from the first straight line segment to the axis of the impeller is smaller than a maximum perpendicular distance from the second reference segment to the axis of the impeller.

[0019] In one embodiment, the fourth curved segment includes a third connecting segment, a second straight segment, and a fourth connecting segment connected in sequence, and the third connecting segment connects the third curved segment;

[0020] The fourth reference segment includes a fourth reference arc segment, a fifth reference arc segment and a sixth reference arc segment connected in sequence, and the fourth reference arc segment is connected with reference to the third reference segment;

[0021] The third connecting segment and the fourth connecting segment are configured to coincide with the fourth reference arc segment and the sixth reference arc segment, respectively;

[0022] A maximum perpendicular distance from the fifth reference arc segment to the axis of the impeller is greater than a maximum perpendicular distance from the second straight line segment to the axis of the impeller.

[0023] In one embodiment, the first straight segment and the second straight segment are both parallel to the tangent of the outer diameter circle of the impeller, the distance from the connection point of the first curved segment and the first connecting segment to the outer diameter circle of the impeller is a first distance t7, the distance from the first straight segment to the outer diameter circle of the impeller is a second distance t6, the distance from the connection point of the third curved segment and the third connecting segment to the outer diameter circle of the impeller is a third distance t5, and the distance from the second straight segment to the outer diameter circle of the impeller is a fourth distance t4, satisfying:

[0024] t6 / t7>0.85, and t4 / t5>0.9.

[0025] In addition, an electrical device is also provided, comprising the centrifugal fan as described in any of the above embodiments.

[0026] The thickness of the above-mentioned blade gradually increases and then gradually decreases from one end of the trailing edge to the other end of the leading edge, so that the blade has the characteristics of an airfoil blade, which can effectively reduce the flow resistance, improve the aerodynamic characteristics in the impeller while increasing the air volume, control the blade channel separation, and improve the efficiency of the fan; at the same time, the thickness of the trailing edge of the blade is greater than 1.5mm, which increases the strength of the trailing edge of the blade, and then increases the injection molding strength of the blade, which facilitates the mass production of blades by injection molding; moreover, increasing the strength of the trailing edge of the blade can effectively avoid the problems of reduced efficiency, increased noise and reduced flow of the centrifugal fan caused by the breaking of the trailing edge, and can achieve the technical effect of taking into account large flow, low noise and high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic structural diagram of a blade in one embodiment of the present invention;

[0028] Figure 2 A schematic diagram of a portion of the structure of a centrifugal fan in one embodiment of the present invention;

[0029] Figure 3 A partial structural diagram of a centrifugal fan in another embodiment of the present invention;

[0030] Figure 4 for Figure 3 The parameter comparison diagram of the centrifugal fan is shown.

[0031] Description of reference numerals:

[0032] Blade 1; leading edge 11; trailing edge 12; pressure side 13; suction side 14; volute 2; volute tongue 21; first curved segment 22; first reference segment 22'; second curved segment 23; second reference segment 23'; third curved segment 24; fourth curved segment 25; fourth reference segment 25'; first straight segment 231; second straight segment 251; impeller 3. DETAILED DESCRIPTION

[0033] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0034] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0035] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0036] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0037] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0038] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0039] See also Figure 1 In one embodiment of the present invention, a blade 1 is provided, the thickness of which gradually increases and then gradually decreases from one end of the trailing edge 12 of the blade 1 to one end of the leading edge 11 of the blade 1, and the thickness of the leading edge 11 of the blade 1 is not less than the thickness of the trailing edge 12 of the blade 1, and the thickness of the trailing edge 12 of the blade 1 is greater than 1.5 mm.

[0040] The thickness of the blade 1 gradually increases and then gradually decreases from one end of the trailing edge 12 to the end of the leading edge 11, so that the blade 1 has the characteristics of an airfoil blade, which can effectively reduce the flow resistance, improve the aerodynamic characteristics in the impeller 3 while increasing the air volume, control the blade channel separation, and improve the efficiency of the fan; at the same time, the thickness of the trailing edge 12 of the blade 1 is greater than 1.5 mm, which increases the strength of the trailing edge 12 of the blade 1, and then increases the injection molding strength of the blade 1, so that it is convenient to mass-produce the blade 1 through injection molding; moreover, increasing the strength of the trailing edge 12 of the blade 1 can effectively avoid the problems of reduced efficiency, increased noise and reduced flow of the centrifugal fan caused by the breaking of the trailing edge 12, and can achieve the technical effect of taking into account large flow, low noise and high efficiency.

[0041] It should be noted that the thickness of the blade 1 gradually increases and decreases, so that the lines of the suction surface 14 and the pressure surface 13 can be ensured to be smooth, thereby reducing the flow resistance of the blade 1.

[0042] In actual use, the thickness of the trailing edge 12 of the blade 1 can be 1.6 mm, 1.7 mm, 1.8 mm, 2.0 mm, etc.

[0043] It should be noted that the blade 1 includes a leading edge 11, a pressure surface 13, a trailing edge 12 and a suction surface 14 connected in sequence. The leading edge 11 and the trailing edge 12 are opposite to each other, and the pressure surface 13 and the suction surface 14 are opposite to each other. The area enclosed by the leading edge 11, the pressure surface 13, the trailing edge 12 and the suction surface 14 is the blade 1.

[0044] Alternatively, see Figure 1 The pressure surface 13 and the suction surface 14 are both curved surfaces, with the pressure surface 13 being concave toward the suction surface 14 and the suction surface 14 being convex away from the pressure surface 13. At this point, the curvature of the pressure surface 13 is greater than that of the suction surface 14, thereby achieving the purpose of increasing high pressure lift and reducing boundary layer separation at low flow rates.

[0045] Further, see Figure 1 The pressure surface 13 is an arcuate surface, and the suction surface 14 is an arcuate surface formed when a convex point located between 25% and 45% of the length of the arcuate surface, which is concentric with the pressure surface 13, convexly extends away from the pressure surface 13. The thickness of the blade 1 at this convex point corresponds to the maximum relative thickness of the blade 1. It is understood that the convex point is close to the leading edge 11.

[0046] See also Figure 1 At this time, the radius of the pressure surface 13 is Ra, the radius of the arc segment of the suction surface 14 that intersects with the trailing edge 12 and is concentric with the pressure surface 13 is Rb, and the thickness of the trailing edge 12 is t2 = Rb-Ra.

[0047] In other embodiments, the pressure surface 13 and the suction surface 14 may also adopt an existing airfoil structure design, for example, the suction surface 14 and the pressure surface 13 are relatively protruding. As long as the advantages of the airfoil blade 1 such as effectively reducing flow resistance are achieved, the thickness of the trailing edge 12 is ensured to be greater than 1.5 mm to ensure the strength of the trailing edge 12.

[0048] Furthermore, the leading edge 11 is an arc surface, and the leading edge 11 is smoothly connected to the pressure surface 13 and the suction surface 14 , which helps to reduce flow resistance.

[0049] Also, see Figures 2 to 4 An embodiment of the present invention further provides a centrifugal fan, comprising an impeller 3 and a plurality of blades 1 as described in the above embodiment, arranged on the impeller 3, wherein the plurality of blades 1 are evenly distributed circumferentially along the axis of the impeller 3, and the trailing edge 12 of each blade 1 is located on the outer diameter circle of the impeller 3.

[0050] It can be understood that the leading edge 11 of the blade 1 is arranged closer to the axis of the impeller 3 than the trailing edge 12 of the blade 1 .

[0051] In actual use, since the thickness of the blade 1 gradually increases and then gradually decreases from one end of the trailing edge 12 to the end of the leading edge 11, the blade 1 has the characteristics of an airfoil blade 1, which can effectively reduce the flow resistance, improve the aerodynamic characteristics in the impeller 3 while increasing the air volume, control the blade channel separation, and improve the efficiency of the centrifugal fan; at the same time, improving the strength of the trailing edge 12 of the blade 1 can effectively avoid the problems of reduced efficiency of the centrifugal fan, increased noise and reduced flow caused by the breaking of the trailing edge 12, and can achieve the technical effect of taking into account large flow, low noise and high efficiency.

[0052] Further, see Figure 2 The diameter of the first cotangential circle of the leading edges 11 of the multiple blades 1 is the blade 1 inlet diameter D1, and the diameter of the second cotangential circle of the trailing edges 12 of the multiple blades 1 is the blade 1 outlet diameter D2. The blade 1 inlet diameter D1 and the blade 1 outlet diameter D2 satisfy the following ratio: D1 / D2 = 0.8-0.82. At this ratio, the blades 1 can effectively withstand high static pressure and ensure the gas flow of the centrifugal fan.

[0053] In actual use, it can be designed as D1 / D2=0.81.

[0054] The first cotangential circle is a circle tangent to the leading edge 11 of each blade 1, and the second cotangential circle is a circle tangent to the trailing edge 12 of each blade 1. Since the trailing edge 12 is located on the outer diameter circle of the impeller 3, that is, the trailing edge 12 is tangent to the outer diameter circle of the impeller 3, the diameter of the outer diameter circle of the impeller 3 is equal to the outlet diameter D2 of the blade 1.

[0055] It can be understood that the first and second cotangential circles are concentric with the outer diameter of the impeller 3. The circle located between the first and second cotangential circles and equidistant from the first and second cotangential circles is the median circle of the blade 1. The diameter of the median circle of the blade 1 is D3, where D3 = (D1 + D2) / 2.

[0056] Viewed from the transverse plane of blade 1, the point on blade 1's suction surface 14 where it intersects the median circle of blade 1 is the midpoint of suction surface 14. The distance between the midpoints of two adjacent blades 1 is the centrifugal fan's blade path width t1. The midline of blade 1 is the blade profile midline of blade 1 (also known as the chord length of blade 1), and the midline length of blade 1 is denoted as L. The ratio of blade 1's midline length L to the blade path width t1 is the density of blade 1. Generally speaking, within a certain range, the larger this value, the greater the ability to withstand high static pressure and the greater the noise. The number of blades 1 on impeller 3 can be determined by the density of blade 1.

[0057] In a preferred embodiment, see Figure 2The midline length L of each blade 1 and the centrifugal fan's blade width t1 meet the following conditions: L / t1 = 2.0 to 2.2 (inclusive), meaning the blade's density is between 2.0 and 2.2. This ensures that the centrifugal fan's blade is not too narrow, maintaining both flow and noise levels.

[0058] In actual use, L / t1 can be taken as 2.1 or 2.15.

[0059] In some embodiments, see Figure 3 and Figure 4 The centrifugal fan further includes a volute 2, and an impeller 3 is rotatably disposed within the volute 2. The profile of the volute 2 in a cross section perpendicular to the axis of the impeller 3 is a spiral line, including a first curved segment 22, a second curved segment 23, a third curved segment 24, and a fourth curved segment 25 connected in sequence. The first curved segment 22 is connected to the volute tongue 21 of the volute 2. The four arc segments connected in sequence based on the equilateral element method include a first reference segment 22', a second reference segment 23', a third reference segment, and a fourth reference segment 25'. The first reference segment 22' is connected to the volute tongue 21 by reference. The second curved segment 23 and the third curved segment are configured to coincide with the second reference segment 23', the third reference segment, and the fourth reference segment 25', respectively. The first curved segment 22 is configured as an arc segment having a curvature smaller than that of the first reference segment 22'.

[0060] The function of the centrifugal fan volute 2 is to guide the gas leaving the impeller 3 toward the volute 2 outlet and convert some of the dynamic pressure into static pressure. The volute 2 is a complex spatial curved surface, and its contour is a helical line. Because helical lines are complex and difficult to draw, the contour of the volute 2 is designed using a simplified four-segment circular arc approximation to form an Archimedean spiral. In this embodiment, four arc segments drawn using the equilateral element method are used as a reference to generate the contour of the volute 2.

[0061] The four arc segments drawn using the equilateral primitive method include a first reference segment 22', a second reference segment 23', a third reference segment, and a fourth reference segment 25'. The first reference segment 22' is connected to the volute tongue 21. The circumscribed circle of the base square formed by the centers of the first reference segment 22', the second reference segment 23', the third reference segment, and the fourth reference segment 25' is located on the axis of the impeller 3. The radii of the first reference segment 22', the second reference segment 23', the third reference segment, and the fourth reference segment 25' are calculated based on the opening of the profile and increase in sequence. The opening of the profile is calculated based on the Archimedean spiral equation.

[0062] The second curved segment 23, the third curved segment 24 and the fourth curved segment 25 of the volute 2 profile are configured to coincide with the second reference segment 23', the third reference segment and the fourth reference segment 25', that is, the second reference segment 23', the third reference segment and the fourth reference segment 25' are respectively used as the second curved segment 23, the third curved segment 24 and the fourth curved segment 25.

[0063] The first curved section 22 of the volute 2 profile is an arc segment, and the curvature of the first curved section 22 is smaller than the curvature of the first reference section 22'. Therefore, the distance between the connection point of the first curved section 22 and the volute tongue 21 and the outer diameter of the impeller 3, i.e., the clearance t3 between the volute tongue 21 and the outer diameter of the impeller 3, is greater than the distance between the connection point of the first reference section 22' and the volute tongue 21 and the outer diameter of the impeller 3. The larger the clearance between the volute tongue 21, the quieter the centrifugal fan. Thus, the clearance between the volute tongue 21 and the centrifugal fan noise can be adjusted by flexibly setting the curvature of the first curved section 22.

[0064] When actually drawing the first curved segment 22, in order to make the curvature of the first curved segment 22 greater than the curvature of the first reference segment 22', the center of the first curved segment 22 is located on the side of the center of the first reference segment 22' away from the volute tongue 21 and within the area divided by the third reference segment.

[0065] It can be understood that an expander is further provided on the outlet side of the volute 2 , and the fourth curved section 25 is connected to the expander.

[0066] exist Figure 3 , the center of the first reference segment 22 ′ is a1 , the center of the second reference segment 23 ′ is a2 , the center of the third reference segment is a3 , the center of the fourth reference segment 25 ′ is a4 , and the center of the first curved segment 22 is a5 .

[0067] In a preferred embodiment, the distance from the connection point between the first curved section 22 and the tongue 21 to the outer diameter of the impeller 3 is the tongue 21 clearance t3, the outer diameter of the impeller 3 is D2', and the gap t3 between the tongue 21 clearance t3 and the outer diameter of the impeller 3, D2', satisfies the following relationship: t3 / D2' = 0.06-0.07. In this manner, the centrifugal fan can achieve both high efficiency and low noise.

[0068] In actual use, t3 / D2' can be set to 0.06, 0.065 or 0.07.

[0069] It can be understood that the diameter D2 ′ of the outer diameter circle of the impeller 3 is equal to the outlet diameter D2 of the blade 1 .

[0070] In one embodiment, see Figure 4In order to reduce the space occupied by the centrifugal fan and enable it to be placed inside the housing of the electrical equipment, the volute 2 is partially cut away. At this time, the second curved section 23 of the volute 2 includes a first connecting section, a first straight section 231, and a second connecting section connected in sequence. The first connecting section connects to the first curved section 22, and the second connecting section connects to the third curved section 24. The second reference section 23' connects to the first reference arc section, the second reference arc section, and the third reference arc section in sequence. The first reference arc section is connected to the first reference section 22', and the third reference arc section is connected to the third reference section. The first connecting section and the second connecting section are configured to coincide with the first reference arc section and the third reference arc section, respectively. The maximum vertical distance from the first straight section 231 to the axis of the impeller 3 is less than the maximum vertical distance from the second reference section 23' to the axis of the impeller 3.

[0071] At this time, replacing the second reference arc segment with the first straight segment 231 reduces the maximum vertical distance between the second curved segment 23 and the axis of the impeller 3, thereby reducing the protrusion distance and occupied space of the volute 2 in the corresponding direction.

[0072] Further, see Figure 3 The fourth curved section 25 of the volute 2 includes a third connecting section, a second straight section 251 and a fourth connecting section connected in sequence, and the third connecting section is connected to the third curved section 24; the fourth reference section 25' includes a fourth reference arc section, a fifth reference arc section and a sixth reference arc section connected in sequence, and the fourth reference arc section is connected to the third reference section with reference to the third reference section; the third connecting section and the fourth connecting section are configured to coincide with the fourth reference arc section and the sixth reference arc section, respectively; the maximum vertical distance from the fifth reference arc section to the axis of the impeller 3 is greater than the maximum vertical distance from the second straight section 251 to the axis of the impeller 3.

[0073] At this time, the fifth reference arc segment is replaced by the second straight segment 251, which reduces the maximum vertical distance of the fourth curved segment 25 from the axis of the impeller 3, thereby reducing the protruding distance and occupied space of the volute 2 in the corresponding direction, and further reducing the volume of the volute 2.

[0074] It can be understood that the sixth reference arc segment is connected to the expander, and the fourth connecting segment is connected to the expander.

[0075] In one embodiment, see Figure 4The first straight segment 231 and the second straight segment 251 are both parallel to the tangent of the outer diameter of the impeller 3. The distance from the connection point of the first curved segment 22 and the first connecting segment to the outer diameter of the impeller 3 is a first distance t7. The distance from the first straight segment 231 to the outer diameter of the impeller 3 is a second distance t6. The distance from the connection point of the third curved segment 24 and the third connecting segment to the outer diameter of the impeller 3 is a third distance t5. The distance from the second straight segment 251 to the outer diameter of the impeller 3 is a fourth distance t4. The following conditions are satisfied: t6 / t7>0.85, and t4 / t5>0.9. This is to ensure that the air volume and noise of the volute 2 are not significantly affected after the volume of the volute 2 is reduced.

[0076] In actual use, t6 / t7 can take values such as 0.9, 0.95, 1.0, 1.1, etc., and t4 / t5 can take values such as 0.9, 0.95, 1.0, 1.05, 1.1, 1.2, etc.

[0077] Alternatively, see Figure 3 and Figure 4 The first straight segment 231 and the second straight segment 251 are parallel to each other, so that the space occupied by the volute 2 can be minimized while ensuring that the air volume and noise of the volute 2 are not greatly affected.

[0078] When designing a centrifugal fan, flow rate, efficiency, and noise determine the performance of the fan. However, these parameters are often mutually exclusive. The centrifugal fan provided by the embodiments of the present invention can reasonably optimize various fan performance parameters by optimizing the structural parameters of the blades 1 and the volute 2, so that the centrifugal fan can achieve the effects of high flow rate, high efficiency, and low noise. At the same time, by thickening the trailing edge 12 of the blade 1, it facilitates the injection molding of the blade 1 and facilitates the mass production of the blade 1.

[0079] In addition, an embodiment of the present invention further provides an electrical device, which includes the centrifugal fan provided in the above embodiment. Since the electrical device includes the above centrifugal fan, all the beneficial effects of the centrifugal fan in the electrical device are not described here.

[0080] Optionally, the electrical appliance is a fresh air ventilator. Of course, the electrical appliance can also be other appliances such as a dehumidifier, an air conditioner, an air conditioning fan, etc.

[0081] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0082] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A centrifugal fan, characterized in that: The impeller comprises an impeller and a plurality of blades, wherein the plurality of blades are evenly distributed along the circumference of the axis of the impeller, and the trailing edge of each blade is located on the outer diameter circle of the impeller; The diameter of the first cotangent circle of the leading edges of the plurality of blades is the blade inlet diameter D1, and the diameter of the second cotangent circle of the trailing edges of the plurality of blades is the blade outlet diameter D2; The blade inlet diameter D1 and the blade outlet diameter D2 satisfy: D1 / D2=0.8-0.81; The thickness of the blade gradually increases and then gradually decreases from one end of the trailing edge of the blade to one end of the leading edge of the blade, and the thickness of the trailing edge of the blade is greater than 1.5 mm; A circle located between the first cotangential circle and the second cotangential circle and equidistant from the first cotangential circle and the second cotangential circle is the median circle of the blade. The diameter of the median circle of the blade is D3, where D3 = (D1 + D2) / 2. The midline length L of each blade and the blade path width t1 of the centrifugal fan satisfy: L / t1=2.0-2.2; The centrifugal fan further includes a volute, and the impeller is rotatably arranged inside the volute; The profile of the volute is a spiral line, comprising a first curved segment, a second curved segment, a third curved segment and a fourth curved segment connected in sequence, wherein the first curved segment is connected to the volute tongue of the volute; The four arc segments connected in sequence obtained based on the equilateral primitive method include a first reference segment, a second reference segment, a third reference segment and a fourth reference segment, wherein the first reference segment is connected to the volute tongue by reference; The second curved segment, the third curved segment, and the fourth curved segment are configured to coincide with the second reference segment, the third reference segment, and the fourth reference segment, respectively; the first curved segment is configured as an arc segment having a curvature smaller than that of the first reference segment; The distance from the connection point of the first curved section and the volute tongue to the outer diameter circle of the impeller is the volute tongue gap t3, and the diameter of the outer diameter circle of the impeller is D2', which satisfies: t3 / D2'=0.06-0.

07.

2. The centrifugal fan according to claim 1, characterized in that: The pressure surface of the blade and the suction surface of the blade are both cambered surfaces, and the pressure surface is concave toward the suction surface, while the suction surface is convex away from the pressure surface.

3. The centrifugal fan according to claim 1, characterized in that: The second curved segment includes a first connecting segment, a first straight segment, and a second connecting segment connected in sequence, wherein the first connecting segment connects the first curved segment, and the second connecting segment connects the third curved segment; The second reference segment includes a first reference arc segment, a second reference arc segment, and a third reference arc segment connected in sequence, wherein the first reference arc segment is connected to the first reference segment, and the third reference arc segment is connected to the third reference segment; The first connecting segment and the second connecting segment are configured to coincide with the first reference arc segment and the third reference arc segment, respectively; A maximum perpendicular distance from the first straight line segment to the axis of the impeller is smaller than a maximum perpendicular distance from the second reference segment to the axis of the impeller.

4. The centrifugal fan according to claim 3, characterized in that: The fourth curved segment includes a third connecting segment, a second straight segment and a fourth connecting segment connected in sequence, and the third connecting segment is connected to the third curved segment; The fourth reference segment includes a fourth reference arc segment, a fifth reference arc segment and a sixth reference arc segment connected in sequence, and the fourth reference arc segment is connected with reference to the third reference segment; The third connecting segment and the fourth connecting segment are configured to coincide with the fourth reference arc segment and the sixth reference arc segment, respectively; A maximum perpendicular distance from the fifth reference arc segment to the axis of the impeller is greater than a maximum perpendicular distance from the second straight line segment to the axis of the impeller.

5. The centrifugal fan according to claim 4, characterized in that: The first straight segment and the second straight segment are both parallel to the tangent of the outer diameter circle of the impeller, the distance from the connection point of the first curved segment and the first connecting segment to the outer diameter circle of the impeller is a first distance t7, the distance from the first straight segment to the outer diameter circle of the impeller is a second distance t6, the distance from the connection point of the third curved segment and the third connecting segment to the outer diameter circle of the impeller is a third distance t5, and the distance from the second straight segment to the outer diameter circle of the impeller is a fourth distance t4, satisfying: t6 / t7>0.85, and t4 / t5>0.

9.

6. An electrical device, characterized in that: The invention comprises the centrifugal fan according to any one of claims 1 to 5.

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