Axial flow fan, axial flow fan design method, fan assembly, and chassis

Abstract

The present application relates to the technical field of fan noise reduction, and specifically provides an axial flow fan, an axial flow fan design method, a fan assembly, and a chassis. The axial flow fan comprises a hub and at least two fan blades. The at least two fan blades are mounted on the outer peripheral surface of the hub in an annular array, and the fan blades are arranged obliquely relative to the axis of the hub. Each fan blade comprise a blade root and a blade tip; the blade root is connected to the hub; the blade tip is located at the end of the fan blade extending radially from the hub; the blade root smoothly extends to the blade tip; the size of the mean camber line in the circumferential section of the fan blade gradually increases; a leading edge and a trailing edge are provided between the blade root and the blade tip; and the leading edge and the trailing edge are bent into an arc shape towards the rotation direction of the fan blade. The axial flow fan provided by the present application can achieve a balance among airflow, air pressure, and noise.

Description

Axial fan, axial fan design method, fan assembly and case

[0001] The present application claims priority to the Chinese Patent Application No. 2024111170461, filed on August 15, 2024, entitled “A Vane, an Axial Fan and a Case”, and the Chinese Patent Application No. 2025111224470, filed on August 11, 2025, entitled “An Axial Fan, an Axial Fan Design Method and a Fan Assembly”, both of which are incorporated herein by reference in their entirety. TECHNICAL FIELD

[0002] The present application relates to the field of fan noise reduction, and in particular to an axial fan, an axial fan design method, a fan assembly and a case. BACKGROUND

[0003] An axial fan is a common type of fan, and its working principle is based on pushing or sucking air along the axial direction through rotating blades, that is, the air moves along the same axis of the axial fan when entering and leaving the fan. The axial fan is widely used in the field of heat dissipation of electronic products such as automobiles, computers and servers due to its simple manufacturing, low cost and strong heat dissipation capability.

[0004] As the main heat dissipation component at present, the axial fan has sufficient fan flow and pressure for heat dissipation, but the noise of the fan itself is large. Or, in the case of the same heat dissipation performance, the noise is large, which affects the user's experience. In other words, the current axial fan product is difficult to balance the relationship between noise and good heat dissipation performance at the same time. SUMMARY

[0005] In order to solve the above problems, the embodiments of the present application provide an axial fan, an axial fan design method, a fan assembly and a case, which can balance the noise while having fan flow and pressure.

[0006] To this end, the embodiments of the present application adopt the following technical solutions:

[0007] In a first aspect, the present application provides an axial fan, comprising a hub and at least two blades, the at least two blades are installed in an annular array on the outer circumferential surface of the hub, the blades are inclined to the axis of the hub, and the blades comprise a blade root and a blade tip, the blade root is connected with the hub, the blade tip is located at the end of the blade extending radially from the hub, the blade root smoothly extends to the blade tip, and the size of the middle arc line of the circumferential section of the blade gradually increases; a leading edge and a trailing edge are provided between the blade root and the blade tip, and the leading edge and the trailing edge are curved into an arc shape towards the rotation direction of the blade.

[0008] In this embodiment, the fan blades of the axial fan are installed in a ring array on the outer periphery of the hub, and the fan blades are arranged obliquely relative to the axis of the hub, which helps to more effectively push the air. The fan blades extend radially outward from the hub, and the tip of the fan blade is the end of the fan blade, which helps to generate greater air volume and higher air pressure. The gradually increasing arc size in the circumferential cross section of the fan blade means that the width or thickness of the fan blade gradually increases along the direction from the root to the tip, which can improve the aerodynamic efficiency of the fan, reduce turbulence and resistance, and thus reduce noise. Further, the leading edge and trailing edge of the fan blade are curved into an arc towards the direction of rotation of the fan blade, which can reduce the generation of turbulence and vortex when the air flows, further reducing the noise level when the fan is running. In other words, the axial fan provided in this embodiment reduces turbulence and resistance generated when the fan is running by optimizing the circumferential cross section and edge shape of the fan blade, thereby significantly reducing the noise level, which is particularly important for scenarios where the fan is used in a quiet environment and needs to dissipate heat. The end user will benefit from lower noise and higher performance indicators, improving the user experience and user satisfaction. In summary, the axial fan provided in this embodiment can have better air volume and air pressure under the same decibel noise level, meeting the heat dissipation needs of electronic components and improving the user experience.

[0009] As an implementable embodiment, each blade fan blade penetrates a plurality of reference variable cylinders S coaxial with the hub to form a plurality of fan circumferential cross sections; the ratio P of the diameter D2 of the plurality of reference variable cylinders S minus the diameter D1 of the hub to the maximum diameter D3 of the blade fan blade minus the diameter D1 of the hub is defined; a coordinate system is established for the median arc of the plurality of fan circumferential cross sections to obtain the coordinates of a plurality of points on the median arc; the coordinates of the plurality of points are fitted into shape using the least squares method to obtain: z = ξ0*(r*θ) + ξ1*r*θ + ξ2 2 +ξ1*r*θ+ξ2

[0010] wherein ξ0, ξ1 and ξ2 are linear coefficients, r is the radius corresponding to the median arc, θ is the angular coordinate of the position point on the median arc, and z is the height coordinate of the position point on the median arc; when P is between 0.1 and 0.9, the coefficient ξ0 is between -0.0058 and -0.0044, ξ1 is between 0.5915 and 0.8415, and ξ2 is between -27.2123 and 0.0303, the error range of ξ0 is ±0.00024, the error range of ξ1 is ±0.028, and the error range of ξ2 is ±2.354.

[0011] In this implementation, when fitting the coordinates of the six end points, the least squares method can help determine an optimal curve or function model to describe the spatial distribution of these end points as accurately as possible. This method can still provide a reasonable and effective fitting result even if there are measurement errors or inaccuracies in the end point coordinates, thereby supporting subsequent optimization and analysis work on the fan blade design. In this way, the quadratic equation obtained by using the least squares method to fit can be used to define the camber line in the fan blade, and by optimizing the parameters of the camber line in the fan blade, the fan blade obtained can reduce the turbulence and vortex generated when the air flows, thereby reducing the noise generated when the fan operates. Specifically, the optimized fan blade can guide the air more smoothly, reducing the resistance and shock of the air flow, thereby reducing the generation of noise. Moreover, the optimized fan blade can improve the air delivery efficiency of the fan, that is, generate more air volume under the same power. This is because the optimized fan blade can rotate and push the air more efficiently without losing energy due to turbulence and resistance. For users, a low-noise fan means a more comfortable user experience, especially in a quiet environment. At the same time, a higher air output can more quickly reduce the ambient temperature or provide better air circulation effect, enhancing user satisfaction and experience of the product.

[0012] As an implementable embodiment, when P = 0.10, ξ0= -0.0056, ξ1= 0.5997, ξ2= 0.0272;

[0013] When P = 0.30, ξ0= -0.0056, ξ1= 0.6606, ξ2= -5.5733;

[0014] When P = 0.50, ξ0= -0.0054, ξ1= 0.7216, ξ2= -11.2962;

[0015] When P = 0.70, ξ0= -0.0049, ξ1= 0.7730, ξ2= -17.4675;

[0016] When P = 0.90, ξ0= -0.0044, ξ1= 0.8178, ξ2= -24.8580.

[0017] As an implementable embodiment, when P = 0.10, ξ0= -0.0055, ξ1= 0.5959, ξ2= 0.0303;

[0018] When P = 0.30, ξ0= -0.0055, ξ1= 0.6756, ξ2= -6.7042;

[0019] When P = 0.50, ξ0= -0.0053, ξ1= 0.7476, ξ2= -13.1921;

[0020] When P = 0.70, ξ0 = -0.0049, ξ1 = 0.8010, ξ2 = -19.7954;

[0021] When P = 0.90, ξ0 = -0.0044, ξ1 = 0.8415, ξ2 = -27.2123.

[0022] As an implementable embodiment, when P = 0.10, ξ0 = -0.0058, ξ1 = 0.5915, ξ2 = 0.0240;

[0023] When P = 0.30, ξ0 = -0.0058, ξ1 = 0.6491, ξ2 = -4.9237;

[0024] When P = 0.50, ξ0 = -0.0056, ξ1 = 0.7144, ξ2 = -10.4364;

[0025] When P = 0.70, ξ0 = -0.0052, ξ1 = 0.7675, ξ2 = -16.3333;

[0026] When P = 0.90, ξ0 = -0.0046, ξ1 = 0.8049, ξ2 = -27.7129.

[0027] In this embodiment, it has been verified through tests that the fan noise can be reduced and the air volume can be increased by using the above-mentioned specific range of fan blade curvature parameters, thereby improving the user experience.

[0028] As an implementable embodiment, when P is between 0.1 and 0.9, the included angle A1 between the line L2 connecting the center point a of the circumferential section of the fan blade projected along the axial direction of the hub and the hub center O and the line L1 connecting the center point b of the blade root projected along the axial direction of the hub and the hub center O is between 14.77r° and 72.01r°, and r is an error adjustment coefficient and the range value is ±10°.

[0029] In this embodiment, the fan blade is curved along the rotation direction and has a certain curvature, and A1 can limit the curvature of the blade tip of the fan blade within the curvature range. Through the limitation, the centrifugal force of the fluid in the boundary layer of the fan blade can be reduced, the blade tip stall of the fan blade can be effectively inhibited, the energy loss at the blade tip of the fan blade can be reduced, and the fan blowing efficiency can be improved.

[0030] In this embodiment, it has been verified through tests that the air volume can be increased by using the above-mentioned specific range of fan blade curvature A1 parameters.

[0031] As an implementable embodiment, when P is between 0.1 and 0.9, the included angle A2 between the line L3 connecting the intersection point c of the axial projection of the fan blade reference circumferential section along the hub and the axial projection of the leading edge along the hub and the tangent line L4 of the leading edge at the point c and the hub center O is between 42.24t° and 55.83t°, t being an error adjustment coefficient and the range value being ±7°.

[0032] In this embodiment, A2 effectively inhibits vortex shedding at the trailing edge of the fan blade, thereby reducing fan blade noise.

[0033] In this embodiment, it has been verified through tests that the fan blade noise can be reduced by using the above-mentioned specific range of the fan blade bending degree A2 parameter.

[0034] As an implementable embodiment, when P is between 0.1 and 0.9, the included angle A3 between the line L5 connecting the intersection point d of the axial projection of the fan blade reference circumferential section along the hub and the axial projection of the trailing edge along the hub and the tangent line L6 of the trailing edge at the point d and the hub center O is between 42.35u° and 58.00u°, u being an error adjustment coefficient and the range value being ±5°.

[0035] In this embodiment, A3 can eliminate the backflow problem existing in the leading edge of the axial flow fan, absorb the low-energy fluid in the end wall area into the high-energy main flow in the fan blade, weaken the gathering of the end low-energy fluid, thereby reducing flow loss and flow blockage.

[0036] In this embodiment, it has been verified through tests that the air flow backflow can be reduced by using the above-mentioned specific range of the fan blade bending degree A3 parameter, thereby reducing air flow noise, and at the same time, the low-energy fluid in the end wall area can be absorbed into the high-energy main flow in the fan blade, thereby improving the air output and air pressure.

[0037] As an implementable embodiment, the length of the line connecting the intersection point c of the axial projection of the fan blade reference circumferential section along the hub and the axial projection of the leading edge along the hub and the intersection point d of the axial projection of the fan blade reference circumferential section along the hub and the axial projection of the trailing edge along the hub is the projected outer arc length cd, and the length of the line connecting the intersection point e of the axial projection of the blade tip along the hub and the axial projection of the leading edge along the hub and the intersection point f of the axial projection of the blade tip along the hub and the axial projection of the trailing edge along the hub is the blade tip arc projection length ef, and the ratio Q=cd / ef of the two is in the range of 0.47 to 0.97.

[0038] In this embodiment, the limitation of the ratio Q of the axial projection chord length of the fan blade reference circumferential section and the blade tip can make the fan have a balance between air supply and noise.

[0039] As an implementable embodiment, the circumferential section of the hub is circular, and the hub is closed at one end and open at the other end along its own axis. The internal area surrounded by the hub is installed with an axle seat, which is connected with the hub through a plurality of annularly arranged ribs. The axle seat is used to install the rotating shaft used in cooperation with the hub.

[0040] In this embodiment, the hub is designed in a circular shape, which helps to reduce the overall weight of the axial flow fan while maintaining sufficient strength. The axle seat is a component that fixes the rotating shaft, usually fixed inside the closed end of the hub by bolts or other connection methods. It plays a role in supporting and positioning the rotating shaft. The ribs form an annular array between the hub and the axle seat, and these ribs serve to enhance the rigidity and load-bearing capacity of the overall structure. Exemplarily, the ribs can be firmly connected with the hub and the axle seat by welding, bolting or other connection methods. Moreover, the design of the axle seat and the annular ribs ensures the safe and stable installation of the rotating shaft, reducing vibration and noise during operation.

[0041] As an implementable embodiment, the height of the blade root along the axial direction of the hub accounts for 1 / 2 to 2 / 3 of the height of the hub, and the connection point of the blade root and the trailing edge is closer to the open side of the hub than the connection point of the blade root and the leading edge, and smoothly extends from the blade root to the blade tip.

[0042] In this embodiment, the blade root is located at the axial height of the hub, accounting for 1 / 2 to 2 / 3 of the height of the hub. This design aims to balance the structural strength of the fan blade and the lightweight requirement of the hub. The higher position of the blade root can usually provide sufficient strength while minimizing the weight of the hub, thereby optimizing the dynamic efficiency of the fan. The connection point of the blade root and the trailing edge closer to the open side of the hub can reduce the turbulence and resistance of air flowing through the axial flow fan, improving the aerodynamic characteristics. By placing the connection point of the blade root and the trailing edge close to the open side of the hub, it can also effectively reduce the generation of wake and vortex, improve the efficiency and performance of the fan. The smooth extension of the blade root from the connection point to the blade tip ensures the streamlining and continuity of the fan blade surface, reducing airflow separation and turbulence, further reducing resistance, and improving the efficiency of the fan. The smooth blade root design can also reduce noise and vibration, improving user experience.

[0043] As an implementable embodiment, the leading edge gradually increases along the axial height from the blade root to the blade tip, and the connection point of the blade tip and the leading edge is closer to the highest point of the axial height of the hub than the connection point of the trailing edge and the blade tip.

[0044] In this embodiment, the leading edge of the blade gradually increases in height along the hub axis in the direction from the root to the tip, which can make the airflow faced by the blade more uniform during operation, reducing the resistance and turbulence generated at different positions, thereby improving the aerodynamic efficiency of the fan. In the design of the blade, the connection point of the tip and the leading edge is closer to the highest point of the hub axial height than the connection point of the trailing edge and the tip, which helps to optimize the structural strength and aerodynamic performance of the blade. By placing the connection point close to the highest point of the hub axial height, air flow separation at the top of the blade can be reduced, and the streamline of the blade surface can be improved, further reducing resistance and noise.

[0045] As an implementable embodiment, the tip and the combination of the leading edge and the trailing edge are circular arc chamfer structures.

[0046] In this embodiment, the circular arc chamfer can make the transition between the tip, leading edge and trailing edge of the blade smoother, avoiding sudden changes and sharp angles. This smooth transition can reduce air resistance on the blade surface, reduce the generation and development of turbulence, and thus reduce energy loss. Moreover, by optimizing the streamline design of the blade surface, the circular arc chamfer can reduce the generation of air flow separation and vortex. This helps to improve the aerodynamic efficiency of the axial flow fan, so that the fan can provide more air volume under the same input power or reduce power consumption under the same air volume. The smooth tip and the combination of the leading and trailing edges reduce the disturbance and turbulence noise when the airflow passes through, which helps to reduce the overall noise level. In addition, the reduction of airflow distortion and uneven flow can also reduce the vibration impact on the blade and the structure of the axial flow fan, further improving the operation stability and life of the axial flow fan. The circular arc chamfer structure also takes into account the structural strength and durability of the blade. By reasonable circular arc radius and chamfer depth, stress concentration can be reduced, the service life of the blade can be prolonged, and the overall structural stability can be improved.

[0047] As an implementable embodiment, the thickness of the blade gradually increases and then gradually decreases from the leading edge to the trailing edge of the blade, so that the curved surface of the blade is smoother.

[0048] In this embodiment, the design of the thickness variation of the fan blades can make the fan blade surface smoother, and the thickness gradually increases and then decreases from the leading edge to the trailing edge, which can reduce the separation and vortex of the airflow on the surface of the fan blades, reduce the resistance, help to smooth the transition of the airflow and reduce the generation of turbulence, and improve the aerodynamic efficiency of the fan. The smooth fan blade surface can reduce the disturbance of the airflow, thereby reducing the generation of noise. In addition, the reduction of airflow distortion and uneven flow can also reduce the vibration impact on the fan blades and the overall axial flow fan structure, further improving the operation stability and service life of the fan. By optimizing the thickness distribution of the fan blades, the fan can provide larger air volume under the same input power, or reduce power consumption under the same air volume. This is because the smoother fan blade design can reduce energy loss, so that the overall performance of the fan is improved. Moreover, reasonable design of the thickness distribution of the fan blades can reduce stress concentration of the fan blades during high-speed operation, prolong the service life of the fan blades. The design of thickness variation can also optimize the structural strength of the fan blades, so that they can better withstand the action of wind force and inertial force, and improve the overall reliability of the axial flow fan.

[0049] As an implementable embodiment, the number of fan blades is 7.

[0050] In this embodiment, the number of fan blades can be set to an odd number to avoid resonance during rotation of the axial flow fan, improve the use stability of the axial flow fan, and reduce noise.

[0051] As an implementable embodiment, the fan blades are integrally formed with the hub.

[0052] In this embodiment, the integrally formed axial flow fan has better structural strength, thereby prolonging the service life of the axial flow fan. Moreover, the integrally formed axial flow fan also has better operation stability, thereby further reducing the possibility of generating noise due to vibration.

[0053] In a second aspect, the application provides another axial flow fan, which comprises a hub and at least two fan blades. Each fan blade penetrates a plurality of reference variable cylinders S coaxial with the hub to form a plurality of fan blade circumferential sections, and each fan blade circumferential section has a median arc line. Each position point of the median arc line has a radius r, an angle θ of the median arc line position point, and a height z of the median arc line position point. Wherein, for each median arc line position point, the equation z=a(rθ) 2 is used to represent. Wherein, for different median arc lines, the coefficient a corresponding to the median arc line with a larger radius is greater than the coefficient a corresponding to the median arc line with a smaller radius, so that the bending degree of the fan blade is higher near the proximal end of the hub, and the bending degree of the fan blade gradually tends to be gentle as the radius increases towards the blade tip.

[0054] The linear parameter a of the middle camber line corresponding to the smaller radius is smaller than the a in the coordinate equation of the middle camber line corresponding to the larger radius, so that the consistency of the air outlet direction of the axial flow fan is good, and the air outlet is reduced to diffuse outward along the axial direction and the effective air outlet is increased.

[0055] As an implementable embodiment, for each middle camber line position point, the equation z=a(rθ-b) 2 may also be used to represent. Wherein the coefficient b corresponding to the larger radius r of the middle camber line is larger than the coefficient b corresponding to the smaller radius r, so that the middle camber line of the fan blade gradually deviates from the flow direction of the axial flow fan as the radius increases.

[0056] b represents the relative movement direction of the middle camber line of the fan blade. The b in the coordinate equation of the middle camber line corresponding to the larger radius is larger than the b in the coordinate equation of the middle camber line corresponding to the smaller radius, so that the middle camber line of the fan blade gradually deviates from the flow direction of the fan as the radius increases. Since it gradually deviates from the flow direction of the fan as the radius increases, the blade tip contacts the airflow before the blade root and exerts a force on the airflow, so that the airflow is subjected to a centripetal force and tends to deviate towards the center of the fan blade. The airflow deviation towards the center of the fan blade can effectively suppress the stall phenomenon and ensure the efficiency of the fan.

[0057] As an implementable embodiment, for each middle camber line position point, the equation z=a(rθ-b) 2 +c can also be used to represent; wherein the coefficient c is used to represent the reference deviation or reference height of the middle camber line of the fan blade in the height direction.

[0058] As an implementable embodiment, from the direction close to the hub to the direction away from the hub, the angle coordinate corresponding to each position point of the trailing edge of the fan blade gradually increases, and the angle coordinate corresponding to each position point of the leading edge of the fan blade gradually increases.

[0059] According to the gradually increasing angle coordinate corresponding to each position point of the trailing edge of the fan blade and the gradually increasing angle coordinate corresponding to each position point of the leading edge of the fan blade, it can be known that in addition to gradually deviating from the flow direction of the fan as the radius increases, the middle camber line of the fan blade also deviates from the rotation direction of the fan as the radius increases, so that the fan type of the fan blade is a forward-leaning fan type. The blade tip of the forward-swept wing fan blade contacts the airflow before the blade root, and in combination with the gradually deviating middle camber line of the fan blade from the flow direction of the fan as the radius increases, the airflow can be further obviously deviated towards the center of the fan blade compared to the radial fan blade and the backward-swept wing fan blade. In addition, the gradually increasing angle coordinate corresponding to each position point of the trailing edge of the forward-swept wing fan blade makes the intersection between the trailing edge of the fan blade and the trailing edge of the blade tip be an obtuse angle, and the airflow deviates from this area when flowing over the fan blade. Compared to the radial fan blade and the backward-swept wing fan blade, the forward-swept wing fan blade has less stratification tendency and the airflow has less tendency to converge towards the trailing edge of the blade tip, so that the stall phenomenon can be more effectively suppressed and the noise generated by the operation of the fan can be reduced.

[0060] As an implementable embodiment, the radii corresponding to the plurality of middle camber lines include at least three of the radii in mm as follows: r1∈(25.705, 27.295), r1∈(29.585, 31.415), r3∈(33.465, 35.535), r4∈(37.345, 39.655), r5∈(41.225, 43.775), r6∈(45.105, 47.895), r7∈(48.985, 52.015), and r8∈(52.865, 56.135); from r1 to r8, the a value range corresponding to each radius in the middle camber line coordinate equation is (-0.011519689, -0.003119689), (-0.009185063, -0.004385063), (-0.008649787, -0.004249787), (-0.007840749, -0.004440749), (-0.007065648, -0.004265648), (-0.00634749, -0.00374749), (-0.005704969, -0.003104969), (-0.005646877, -0.002246877) in sequence; from r1 to r8, the b value range corresponding to each radius in the middle camber line coordinate equation is (31.41397475, 57.24297475), (35.67459397, 59.80259397), (39.16665805, 64.05565805), (43.26887814, 69.05887814), (50.1852636, 74.4952636), (61.37546577, 80.15546577), (66.99512971, 96.95512971), and (74.14539731, 112.9853973) in sequence.

[0061] In this embodiment, it is verified by experiments that, by using the above-mentioned specific range of fan middle camber line parameters, the fan noise can be reduced, the air volume can be increased, and the user experience can be improved.

[0062] As an implementable embodiment, the value ranges of c in the coordinate equation of the middle arc line corresponding to each radius from r1 to r8 are (9.62845506, 17.02845506), (9.55830966, 15.55830966), (9.38681835, 14.58681835), (9.23807747, 14.03807747), (9.95227863, 13.35227863), (10.8127758, 13.4127758), (11.56604664, 14.56604664) and (11.60406431, 16.20406431) in sequence.

[0063] In this embodiment, it is verified by experiments that the fan noise can be reduced and the air volume can be increased by using the above-mentioned specific range of the fan middle arc line parameters, thereby improving the user experience.

[0064] As an implementable embodiment, the value ranges of the angle coordinates corresponding to each position point of the fan rear edge from r1 to r8 are (-0.388, -0.312), (-0.258, -0.122), (-0.161, 0.001), (-0.07, 0.110), (0.012, 0.208), (0.080, 0.320) in sequence; and the value ranges of the angle coordinates corresponding to each position point of the fan front edge from r1 to r8 are (0.327, 0.393), (0.412, 0.548), (0.499, 0.661), (0.600, 0.780), (0.682, 0.878), (0.750, 0.990), (0.850, 1.090) and (0.970, 1.210) in sequence.

[0065] In this embodiment, by setting the above-mentioned parameters, the angle coordinates corresponding to each position point of the fan rear edge gradually increase, the angle coordinates corresponding to each position point of the fan front edge gradually increase, and in addition to gradually deviating from the flow direction of the fan as the radius increases, the middle arc line of the fan gradually deviates from the rotation direction of the fan as the radius increases, so that the fan type is a forward-inclined fan type. The forward-inclined fan type can more effectively suppress the stall phenomenon and reduce the noise generated by the fan operation.

[0066] In a third aspect, the application provides a method for designing an axial fan, the method comprising: determining a plurality of mean camber lines of the axial fan at a plurality of radii of the fan blades, wherein each of the plurality of mean camber lines is formed by a plurality of reference variable cylinders S coaxial with the hub and intersected by each of the fan blades, each of the plurality of mean camber lines having a plurality of position points, each of the position points having a radius r, an angle θ of the position point, and a height z of the position point; generating a three-dimensional fan blade model based on the plurality of mean camber lines corresponding to the plurality of radii; and generating a three-dimensional fan model based on the three-dimensional fan blade model.

[0067] As an implementation, in initializing the angle coordinate range of the fan blade at each radius and adjusting the angle coordinate range of the mean camber line at each radius, the angle coordinate range satisfies the following condition: the angle coordinate at the trailing edge position of the fan blade corresponding to each radius gradually increases from the position close to the hub to the position far from the hub, and the angle coordinate at the leading edge position of the fan blade corresponding to each radius gradually increases.

[0068] In a fourth aspect, the application provides a fan assembly comprising a driving motor and the axial fan of any one of the first aspect or the second aspect. The driving motor is arranged in the hub of the axial fan.

[0069] In a fifth aspect, the application provides a case comprising the fan assembly of the fourth aspect, the axial fan being arranged on a side panel of the case and used for dissipating heat of a heat-generating component in the case.

[0070] The beneficial effects are as described above, and will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0071] In order to more clearly illustrate the specific embodiments of the application or the technical solutions of the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0072] The various regions, shapes and their relative sizes and positional relationships shown in the drawings are only exemplary, and in actuality, there may be deviations due to manufacturing tolerances or technical limitations, and a person skilled in the art can additionally design regions / layers with different shapes, sizes and relative positions according to actual needs.

[0073] In the various drawings, the same elements are denoted by similar reference numerals. For the sake of clarity, the various parts in the drawings are not drawn to scale, and some features can be exaggerated or omitted in order to more clearly show and explain the application.

[0074] Fig. 1 shows a perspective view of an axial fan according to an embodiment of the present application;

[0075] Fig. 2 shows a front view of the axial fan of Fig. 1;

[0076] Fig. 3 shows a schematic view of the axial fan according to an embodiment of the present application after being cut by a reference variable cylinder S;

[0077] Fig. 4 shows a schematic view of establishing a coordinate system for a middle arc of a fan blade according to an embodiment of the present application;

[0078] Fig. 5 shows a bottom view of the axial fan of Fig. 1 according to an embodiment of the present application;

[0079] Fig. 6 shows a schematic view of a fan blade being cut by a plurality of reference variable cylinders S according to an embodiment of the present application;

[0080] Fig. 7 shows a perspective view of the axial fan of Fig. 1 from another angle according to an embodiment of the present application;

[0081] Fig. 8 shows a comparison of P-Q curves of the axial fan and other fans of the same specification according to an embodiment of the present application;

[0082] Fig. 9 shows a comparison of air volume of the axial fan and other fans of the same specification when the air pressure is the same (2.00 mmAq) according to an embodiment of the present application;

[0083] Fig. 10 shows a comparison of P-Q curves of the axial fan and other fans of the same specification according to an embodiment of the present application;

[0084] Fig. 11 shows a comparison of air volume of the axial fan and other fans of the same specification when the air pressure is the same (3.00 mmAq) according to an embodiment of the present application;

[0085] Fig. 12 shows an exploded view of the axial fan according to an embodiment of the present application;

[0086] Fig. 13 shows a schematic view of the axial fan according to an embodiment of the present application in a whole radial direction;

[0087] Fig. 14 shows a schematic view of the axial fan according to an embodiment of the present application in an axial direction;

[0088] Fig. 15 shows a schematic view of a longitudinal section of a fan blade at a radius r according to an embodiment of the present application;

[0089] Fig. 16 shows a schematic view of a decomposition of a wind speed triangle of a fan blade at different radii according to an embodiment of the present application;

[0090] Fig. 17 shows a flow characteristic diagram of the axial flow fan provided by the embodiment of the present application under normal airflow and stall airflow speed;

[0091] Fig. 18 shows a schematic diagram of a plurality of different shaped fan blades provided by the embodiment of the present application;

[0092] Fig. 19 shows a wind pressure-air volume curve diagram of the axial flow fan provided by the embodiment of the present application;

[0093] Fig. 20 shows a whole design flowchart of the fan provided by the embodiment of the present application;

[0094] Fig. 21 shows a method flowchart for determining the fan type of the axial flow fan by using simulation analysis provided by the embodiment of the present application;

[0095] Fig. 22 shows a schematic diagram of the axial cross section of the axial flow fan provided by the embodiment of the present application;

[0096] Fig. 23 shows a schematic diagram for generating the control section based on the determined radius size provided by the embodiment of the present application;

[0097] Fig. 24 shows a schematic diagram for directly expanding the middle-arc control curve in three-dimensional space provided by the embodiment of the present application;

[0098] Fig. 25 shows a schematic diagram for expanding the middle-arc control curve in a two-dimensional plane provided by the embodiment of the present application;

[0099] Fig. 26 shows a schematic diagram of the structure for forming a complete three-dimensional fan blade model provided by the embodiment of the present application;

[0100] Fig. 27 shows a schematic diagram of the three-dimensional model of the axial flow fan formed by splicing provided by the embodiment of the present application. DETAILED DESCRIPTION

[0101] The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.

[0102] In the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0103] In addition, the terms "first", "second", etc. are used only for the purpose of description, and should not be understood as indicating or implying relative importance or implying the number of the technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0104] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0105] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be directly above or obliquely above the first feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be directly below or obliquely below the first feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0106] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms is not necessarily for the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples described in the present application and the features of different embodiments or examples, without contradiction.

[0107] As described in the background, in the related art, it is difficult for an axial fan to simultaneously consider the relationship between noise and good heat dissipation performance.

[0108] To solve the above problems, the embodiment of the present application provides an axial flow fan, which is applied to the axial flow fan. FIG. 1 shows a three-dimensional structure schematic diagram of an axial flow fan provided by the embodiment of the present application. Referring to FIG. 1, the axial flow fan comprises a hub 1 and at least two fan blades 2. The at least two fan blades 2 are arranged in a ring array on the outer circumferential surface of the hub 1. The fan blade 2 is arranged obliquely relative to the axis of the hub 1, and the fan blade 2 comprises a blade root 23 and a blade tip 24. The blade root 23 is connected with the hub 1, and the blade tip 24 is located at the end of the fan blade 2 extending radially from the hub 1. The fan blade 2 is smoothly extended from the blade root 23 to the blade tip 24, and the size of the arc F3 in the circumferential cross section of the fan blade 2 gradually increases. A leading edge 21 and a trailing edge 22 are arranged between the blade root 23 and the blade tip 24. The leading edge 21 and the trailing edge 22 are curved into an arc shape towards the rotating direction of the fan blade, that is, the arc-shaped protrusions of the leading edge 21 and the trailing edge 22 are away from the rotating direction. It should be noted that the leading edge 21 is the edge part of the fan through which the airflow enters the fan in the rotating direction of the fan, and the trailing edge 22 is the edge part of the fan through which the airflow flows out of the fan in the rotating direction of the fan.

[0109] It can be understood that the fan blade 2 is arranged obliquely relative to the axis of the hub 1, so that the fan blade 2 of the axial flow fan cuts the air to do work during rotation, and a pressure difference is generated between the outflow side and the inflow side of the fan blade 2. Under the action of the pressure difference, the airflow is driven to flow from the inflow side of the fan blade 2 to the outflow side of the fan blade 2 through the gap between the fan blades 2, that is, the gas flows along the axial direction of the axial flow fan under the action of the pressure difference.

[0110] In the embodiment of the present application, by aerodynamic optimization design of each fan blade 2 in the axial flow fan, for example, by optimizing the circumferential cross-sectional shape of the fan blade 2, the turbulence and resistance generated during the operation of the fan are reduced, so that the air volume and air pressure can be effectively increased while keeping low noise. Therefore, the axial flow fan design scheme provided by the embodiment of the present application based on the ring array, the gradually increasing arc in the circumferential cross section and the arc-shaped leading and trailing edges can effectively balance the air volume, air pressure and noise level of the fan by optimizing the aerodynamic characteristics of the axial flow fan.

[0111] In this embodiment, the number of fan blades 2 is 7. It should be noted that the skilled person can set the specific number of fan blades 2 according to actual needs, which is not limited in this application. In some embodiments, the number of fan blades 2 can also be 3, 5, 7, 9, 11, 13, etc. Therefore, the number of fan blades 2 is selected as an odd number, which has better dynamic balance, avoids resonance of the fan blades 2, reduces bearing wear, and prolongs the service life. It is worth mentioning that too small spacing between the fan blades 2 will cause airflow disturbance, increase the conflict on the surface of the fan blades 2, and reduce the efficiency of the electric fan. Too large spacing will cause increased pressure loss and insufficient wind pressure. Therefore, after selecting different numbers of fan blades 2, the developer needs to verify and adjust the spacing between the fan blades 2. In this embodiment, the 7 fan blades 2 are evenly arranged along the outer circumferential surface of the hub 1, which can make the spacing between the fan blades 2 suitable, so that the fan can balance the wind volume, wind pressure and noise.

[0112] In order to facilitate understanding of the scheme provided by the embodiments of the application, the definitions and concepts designed by the application for aerodynamic optimization design of the fan blades 2 are introduced below.

[0113] FIG. 2 shows a front view of the axial flow fan in FIG. 1. FIG. 3 shows a schematic view of the axial flow fan provided by the embodiments of the application after being cut by a reference variable cylinder S. FIG. 4 shows a schematic view of the coordinate system established by the application for the arc line in the fan blade 2. FIG. 5 shows a bottom view of the axial flow fan in FIG. 1. Referring to FIGS. 2 to 5, the concepts of the connecting line, intersection point, etc. are generated by fan axial projection drawing without special description:

[0114] Referring to FIG. 2, the center O of the hub; the hub diameter D1; the reference variable cylinder S is arranged concentrically with the hub; D2: the diameter of the cylinder S; D3: the maximum diameter of the fan blade 2. Among them, the diameter D2 of the plurality of reference variable cylinders S is a variable value between the hub diameter D1 and the maximum diameter D3 of the fan blade 2, and the definition of the reference variable P is the ratio of the diameter D2 of the cylinder S minus the hub diameter D1 to the maximum diameter D3 of the fan blade 2 minus the hub diameter D1, that is, P = (D2-D1) / (D3-D1). The rest of the fan blade 2 structure parameters change according to the change of P value. Specifically, the value range of P can be 0.1-0.9.

[0115] Continuing to refer to FIG. 2, a: the midpoint of the axial projection of the circumferential section formed by the intersection of the reference variable cylinder S and the fan blade 2; b: the midpoint of the axial projection of the circumferential section formed by the hub connection of the blade root of the fan blade 2; L1: the connecting line of b and the hub center O; L2: the connecting line of a and the hub center O.

[0116] Fan blade 2 net bending angle A1: the included angle between L1 and L2; c: the intersection point of the cylinder S and the leading edge of the fan blade 2; L3: the line connecting c and the center O of the hub; L4: the tangent line of the leading edge of the fan blade 2 at the point c.

[0117] Leading edge guide vane bending angle A2: the included angle between L3 and L4; d: the intersection point of the cylinder S and the trailing edge of the fan blade 2; L5: the line connecting D and the center O of the hub; L6: the tangent line of the trailing edge of the fan blade 2 at the point d.

[0118] Trailing edge guide vane bending angle A3: the included angle between L5 and L6.

[0119] The length of the line connecting the intersection point c of the axial projection of the reference circumferential section of the fan blade 2 along the hub and the axial projection of the leading edge along the hub and the intersection point d of the axial projection of the reference circumferential section of the fan blade 2 along the hub and the axial projection of the trailing edge along the hub is the projected outer arc length cd; the length of the line connecting the intersection point e of the axial projection of the tip of the fan blade 2 along the hub and the axial projection of the leading edge along the hub and the intersection point f of the axial projection of the tip of the fan blade 2 along the hub and the axial projection of the trailing edge along the hub is the tip arc projection length ef, and the ratio Q = cd / ef of the two can be in the range of 0.47-0.97.

[0120] Referring to FIG. 3, the leaf section F: the circumferential section formed by the intersection of the plurality of reference variable cylinders S and the fan blade 2. The upper arc F1: the arc length of the upper surface of the fan blade 2. The lower arc F2: the arc length of the lower surface of the fan blade 2. The middle arc F3 of the fan blade 2: the points of the leaf section at equal distances from the upper arc and the lower arc constitute the middle arc of the fan blade 2.

[0121] Referring to FIG. 4, a coordinate system can be established for the middle arc F3 of the fan blade 2. The coordinate system is established as follows:

[0122] The circumferential section formed by the intersection of the reference variable cylinder S and the root of the fan blade 2, and the midpoint of the middle arc of the circumferential section is m. The hub rotation axis is the Z axis and the rotation direction is the counterclockwise direction of the Z axis projection plane (right-hand rule direction), the plane G is perpendicular to the Z axis and passes through the point m, the X axis passes through the intersection of the Z axis and the plane G and the point m, and the positive direction points from the intersection of the Z axis and the plane G to the point m; M is a point on the middle arc F3 of the fan blade 2, and the coordinates can be represented as (r, θ, z); r represents the vertical distance of the point M from the Z axis, and the unit of r is mm; θ represents the included angle between the projection line of the line OM on the plane G and the positive X axis, and the unit of θ is rad, and the range is 0 to 2π; the size of z is the minimum vertical distance of the point M from the plane G, and the unit is mm.

[0123] On the premise that the value range of P is 0.1-0.9, the coordinates of multiple points on the middle camber line can be obtained by establishing a coordinate system according to the above method for the middle camber line corresponding to the reference circumferential section of the different radius size of the fan blade 2. Then the least square method can be fitted by using the coordinates of multiple points to obtain the quadratic equation.

[0124] Exemplarily, the middle camber line F3 is divided into five equal lengths, and the coordinates of six endpoints can be obtained. The coordinates of the six endpoints are fitted into shape by the least square method to obtain: z = ξ0*(r*θ) + ξ1*r*θ + ξ2 2 +ξ1*r*θ+ξ2

[0125] The quadratic equation about r*θ, wherein r*θ is the arc length, when P is between 0.1-0.9, the coefficient ξ0 is between-0.0058-0.0044, the coefficient ξ1 is between 0.5915-0.8415, and the coefficient ξ2 is between-27.2123-0.0303, wherein the error range of the coefficient ξ0 is ±0.00024, the error range of the coefficient ξ1 is ±0.028, and the error range of the coefficient ξ2 is ±2.354.

[0126] In this way, the quadratic equation fitted by the least square method is used to define the middle camber line F3 of the fan blade 2, and the parameters of the middle camber line F3 of the fan blade 2 are optimized by limiting the values of ξ0, ξ1 and ξ2. With the specific range of the parameters of the middle camber line F3 of the fan blade 2, the fan noise can be reduced, the air volume can be improved, and the user experience can be improved.

[0127] Based on the above, the axial flow fan provided by the embodiments of the present application is described in detail. These embodiments are used to specifically illustrate the implementation of the present application, and should not be understood as limiting the scope of the present application in any way.

[0128] Fig. 6 shows a schematic view of the fan blade 2 being cut by multiple reference variable cylinders S. As shown in Fig. 6, when P is respectively 0.1, 0.3, 0.5, 0.7, 0.9, the 5 reference variable cylinders S divide the fan blade 2 into 6 angular regions A, each angular region A is arranged in sequence and is in an arc shape, which makes the air flow more concentrated and helps to increase the air supply distance and air pressure. Referring back to Fig. 3, each reference variable cylinder S cuts the fan blade 2 to obtain a corresponding blade section F, the relative upper and lower sides of the blade section F form an upper arc F1 and a lower arc F2 respectively, the two ends of the upper arc F1 and the lower arc F2 are connected to the leading edge 21 and the trailing edge 22 respectively, and the points in the blade section F that are equidistant from the upper arc F1 and the lower arc F2 constitute a middle arc F3 of the fan blade 2. The middle part of the upper arc F1 and the lower arc F2 forms a middle arc point, the connecting line of each upper arc middle arc point forms a middle arc line, which is defined as I, and the maximum distance between the upper arc F1 and the lower arc F2 is defined as the maximum thickness, the maximum thickness is the distance between the middle part of the upper arc F1 and the lower arc F2, and the maximum distance between the middle part of the upper arc F1 and the lower arc F2 is located at the middle arc line I.

[0129] For example, the thickness of the fan blade 2 gradually increases from the leading edge 21 to the middle arc line I and gradually decreases from the middle arc line I to the trailing edge 22, and the dividing point is located at the middle arc line I, so that the curved surface of the fan blade 2 is smoother. At the same time, as the value of P increases, the size of the corresponding middle arc F3 gradually increases, and correspondingly, the length of the upper arc F1 and the lower arc F2 corresponding to the middle arc F3 also gradually increases. In this way, the fan blade 2 is designed to be a variable cross-section streamline, which makes the fan run more efficiently based on the principle of aerodynamics.

[0130] In a specific embodiment, when P is respectively 0.1, 0.3, 0.5, 0.7, 0.9, the corresponding middle arc F3 is obtained. For each middle arc, the curve function model is z = ξ0*(r*θ) 2 + ξ1*r*θ + ξ2

[0131] When P = 0.10, ξ0 = -0.0056, ξ1 = 0.5997, and ξ2 = 0.0272;

[0132] When P = 0.30, ξ0 = -0.0056, ξ1 = 0.6606, and ξ2 = -5.5733;

[0133] When P = 0.50, ξ0 = -0.0054, ξ1 = 0.7216, and ξ2 = -11.2962;

[0134] When P = 0.70, ξ0 = -0.0049, ξ1 = 0.7730, and ξ2 = -17.4675;

[0135] When P = 0.90, ξ0= -0.0044, ξ1= 0.8178, ξ2= -24.8580.

[0136] In one specific embodiment, when P = 0.10, ξ0= -0.0055, ξ1= 0.5959, ξ2= 0.0303;

[0137] When P = 0.30, ξ0= -0.0055, ξ1= 0.6756, ξ2= -6.7042;

[0138] When P = 0.50, ξ0= -0.0053, ξ1= 0.7476, ξ2= -13.1921;

[0139] When P = 0.70, ξ0= -0.0049, ξ1= 0.8010, ξ2= -19.7954;

[0140] When P = 0.90, ξ0= -0.0044, ξ1= 0.8415, ξ2= -27.2123.

[0141] In another specific embodiment, when P = 0.10, ξ0= -0.0058, ξ1= 0.5915, ξ2= 0.0240;

[0142] When P = 0.30, ξ0= -0.0058, ξ1= 0.6491, ξ2= -4.9237;

[0143] When P = 0.50, ξ0= -0.0056, ξ1= 0.7144, ξ2= -10.4364;

[0144] When P = 0.70, ξ0= -0.0052, ξ1= 0.7675, ξ2= -16.3333;

[0145] When P = 0.90, ξ0= -0.0046, ξ1= 0.8049, ξ2= -27.7129.

[0146] Thus, the fan blade 2 obtained after the above parameter optimization can guide the air more smoothly, reduce the resistance and shock when the air flows, and thus reduce the generation of noise. Moreover, the optimized fan blade 2 can improve the air conveying efficiency of the fan, i.e., generate greater air volume under the same power.

[0147] Referring to FIG. 5, H3 represents the axial height of the hub, H1 represents the axial height of the blade root, and H2 represents the axial height of the blade tip. Optionally, the axial height H1 of the blade root 23 along the hub 1 is 1 / 2 to 2 / 3 of the axial height H3 of the hub 1, and the connecting point of the blade root 23 and the trailing edge 22 is closer to the opening side of the bottom of the hub 1 than the connecting point of the blade root 23 and the leading edge 21, and the blade root 23 smoothly extends to the blade tip 24. Correspondingly, the axial height of the leading edge 21 along the blade root 23 to the blade tip 24 gradually increases, and the connecting point of the blade tip 24 and the leading edge 21 is closer to the highest point of the axial height H3 of the hub 1 than the connecting point of the blade tip 24 and the trailing edge 22. In this way, by optimizing the connecting point of the blade root 23 and the hub 1, the structural strength of the fan blade 2 is increased while meeting the lightweight requirement of the hub 1, and by optimizing the shape of the leading edge 21 and the trailing edge 22 of the fan blade 2 in combination with the above-mentioned camber line F3 in the fan blade 2, the fan blade 2 is smoother, which can reduce the friction and turbulence between the airflow and the surface of the fan blade 2, thereby reducing the generation of noise.

[0148] In a more specific embodiment, the connecting point of the blade tip 24 and the leading edge 21 and the trailing edge 22 is a circular arc chamfer structure, so that the connecting point of the blade tip 24 and the leading edge 21 and the trailing edge 22 is smoothly transitioned. It should be noted that when the axial flow fan rotates, part of the airflow moves along the surface of the fan blade 2 structure, and when the airflow flows along the surface of the fan blade 2 structure, due to the viscosity between the airflow and the surface of the fan blade 2, a small amount of vortex is generated in the airflow during the flow, which in turn generates a small amount of noise. The connecting point of the blade tip 24 and the leading edge 21 and the trailing edge 22 is smoothly transitioned, which reduces the travel distance of the airflow flowing along the surface of the sheet structure and accelerates the shedding of the airflow, thereby further reducing noise.

[0149] It is worth mentioning that the camber of the fan blade 2 in the embodiment is curved along the rotation direction and presents a certain camber, and the camber range A1, A2, A3 in the embodiment ensures that the blowing airflow is concentrated in the columnar space directly in front of the air outlet, so that the overall air flow line is stable, the air supply distance and air pressure are increased, and the air supply volume can be increased under the premise of ensuring a certain air pressure.

[0150] For example, referring to FIG. 2, in some embodiments, when P is between 0.1 and 0.9, the included angle A1 between the line L2 connecting the center point a of the axial projection of the fan blade 2 reference circumferential cross section F along the hub 1 and the center O of the hub 1 and the line L1 connecting the center point b of the axial projection of the blade root 23 along the hub 1 and the center O of the hub 1 is between 14.77v° and 72.01v°, where v is an error adjustment coefficient and the range value is ±10°.

[0151] In one specific embodiment, when P = 0.10, A1 = 17.53v°; when P = 0.30, A1 = 35.10v°; when P = 0.50, A1 = 44.66v°; when P = 0.70, A1 = 54.19v°; when P = 0.90, A1 = 64.08v°.

[0152] In one specific embodiment, when P = 0.10, A1 = 21.11v°; when P = 0.30, A1 = 40.59v°; when P = 0.50, A1 = 53.26v°; when P = 0.70, A1 = 62.58v°; when P = 0.90, A1 = 72.01v°.

[0153] In one specific embodiment, when P = 0.10, A1 = 21.11v°; when P = 0.30, A1 = 40.59v°; when P = 0.50, A1 = 53.26v°; when P = 0.70, A1 = 62.58v°; when P = 0.90, A1 = 72.01v°.

[0154] A1 can limit the degree of curvature of the tip 24 of the fan blade 2, through which the centrifugal force of the fluid in the boundary layer of the fan blade 2 can be reduced, so as to effectively inhibit the stall of the tip 24 of the fan blade 2, thereby reducing the energy loss at the tip 24 of the fan blade 2 and improving the air supply efficiency of the fan blade 2.

[0155] In some embodiments, when P is between 0.1 and 0.9, the included angle A2 between the line L3 connecting the intersection point c of the axial projection of the fan blade 2 reference circumferential section F along the hub 1 and the axial projection of the leading edge 21 along the hub 1 and the tangent line L4 of the leading edge 21 at the point c is between 42.24t° and 55.83t°, where t is an error adjustment coefficient and the range value is ±7°.

[0156] In one specific embodiment, when P = 0.10, A2 = 47.91t°; when P = 0.30, A2 = 44.36t°; when P = 0.50, A2 = 42.24t°; when P = 0.70, A2 = 47.66t°; when P = 0.90, A2 = 55.83t°.

[0157] In one specific embodiment, when P = 0.10, A2 = 54.18t°; when P = 0.30, A2 = 44.56t°; when P = 0.50, A2 = 44.92t°; when P = 0.70, A2 = 44.20t°; when P = 0.90, A2 = 55.32t°.

[0158] In another specific embodiment, when P = 0.10, A2 = 45.88t°; when P = 0.30, A2 = 42.43t°; when P = 0.50, A2 = 42.92t°; when P = 0.70, A2 = 45.20t°; when P = 0.90, A2 = 53.86t°.

[0159] A2 in the above values can effectively inhibit vortex shedding at the trailing edge of the fan blade 2, thereby reducing the noise of the fan blade 2.

[0160] In some embodiments, when P is between 0.1 and 0.9, the angle A3 between the line L5 connecting the intersection point d of the axial projection of each of the fan blades 2 with respect to the circumferential section F and the axial projection of the trailing edge 22 along the hub 1 and the tangent line L6 of the trailing edge 22 at the point d is between 42.35u° and 58.00u°, where u is an error adjustment coefficient and ranges in ±5°.

[0161] In one specific embodiment, when P = 0.10, A3 = 53.28u°; when P = 0.30, A3 = 51.05u°; when P = 0.50, A3 = 44.09u°; when P = 0.70, A3 = 43.97u°; when P = 0.90, A3 = 50.14u°.

[0162] In one specific embodiment, when P = 0.10, A3 = 58.00u°; when P = 0.30, A3 = 54.36u°; when P = 0.50, A3 = 45.57u°; when P = 0.70, A3 = 42.35u°; when P = 0.90, A3 = 50.25u°.

[0163] In another specific embodiment, when P = 0.10, A3 = 50.13u°; when P = 0.30, A3 = 47.74u°; when P = 0.50, A3 = 44.91u°; when P = 0.70, A3 = 43.06u°; when P = 0.90, A3 = 47.87u°.

[0164] A3 can eliminate the backflow problem existing at the leading edge 21 of the axial fan, absorb the low-energy fluid in the end wall region into the high-energy main flow in the fan blade 2, weaken the aggregation of the end low-energy fluid, thereby reducing flow loss and flow blockage.

[0165] In some embodiments, the length of the line connecting the intersection c of the axial projection of the fan blade 2 reference circumferential section F along the hub 1 and the axial projection of the leading edge 21 along the hub 1 with the intersection d of the axial projection of the fan blade 2 reference circumferential section F along the hub 1 and the axial projection of the trailing edge 22 along the hub 1 is the projected outer arc length cd, and the length of the line connecting the intersection e of the axial projection of the blade tip 24 along the hub 1 and the axial projection of the leading edge 21 along the hub 1 with the intersection f of the axial projection of the fan blade 2 blade tip 24 along the hub 1 and the axial projection of the trailing edge 22 along the hub 1 is the blade tip arc projection length ef, and the ratio Q = cd / ef of the two is in the range of 0.47 to 0.97. The limitation of the ratio Q of the axial projection chord length of the fan blade 2 reference circumferential section F and the blade tip 24 can balance the air supply and noise of the fan.

[0166] For example, in a specific embodiment, when P = 0.10, cd = 18.49, ef = 38.55, Q = 0.48; when P = 0.30, cd = 22.17, ef = 38.55, Q = 0.57; when P = 0.50, cd = 26.14, ef = 38.55, Q = 0.68; when P = 0.70, cd = 31.15, ef = 38.55, Q = 0.81; when P = 0.90, cd = 33.94, ef = 38.55, Q = 0.88.

[0167] In another specific embodiment, when P = 0.10, cd = 18.37, ef = 37.75, Q = 0.49; when P = 0.30, cd = 21.85, ef = 37.75, Q = 0.58; when P = 0.50, cd = 25.73, ef = 37.75, Q = 0.68; when P = 0.70, cd = 30.68, ef = 37.75, Q = 0.81; when P = 0.90, cd = 36.59, ef = 37.75, Q = 0.97.

[0168] In another specific embodiment, when P = 0.10, cd = 18.37, ef = 37.75, Q = 0.49; when P = 0.30, cd = 21.85, ef = 37.75, Q = 0.58; when P = 0.50, cd = 25.73, ef = 37.75, Q = 0.68; when P = 0.70, cd = 30.68, ef = 37.75, Q = 0.81; when P = 0.90, cd = 36.59, ef = 37.75, Q = 0.97.

[0169] It should be noted that the angle between the axial projection chord length of the blade root 23 and the axial projection chord length of the blade tip 24 is less than 90°. The axial projection chord lengths at the blade root 23 and the blade tip 24 are different, so that the fan blade 2 is twisted. In this way, the airflow speed and pressure distribution of each part of the fan blade 2 during operation can be more uniform. In the embodiment, the chord length at the blade tip 24 is longer, so the rotational speed of the blade tip 24 is relatively fast, and the airflow speed generated is also higher. At the same time, the interaction between the airflow generated by the fan blade 2 and the adjacent fan blade 2 is more balanced, reducing the vibration and noise caused by the imbalance of the aerodynamic force. This balance also helps to reduce the noise at the blade tip 24, making the overall fan operation more stable and quiet. The more uniform airflow speed and pressure distribution helps to improve the overall efficiency of the fan. By optimizing the twisted design of the fan blade 2, a larger air volume can be provided under the same power consumption or the power consumption can be reduced under the same air volume, thereby improving the energy efficiency ratio of the fan.

[0170] Figure 7 shows another perspective view of the axial flow fan of Figure 1. As shown in Figure 7, the circumferential cross-section of the hub 1 is a circular ring, and the hub 1 is closed at one end and open at the other end along the axial direction of the hub 1. The hub 1 surrounds an internal area in which the shaft seat 4 is installed. The shaft seat 4 and the hub 1 are connected by a plurality of annularly arranged ribs 5. The shaft seat 4 is used to install a rotating shaft (not shown) that cooperates with the hub 1.

[0171] For example, the overall material of the axial flow fan can be metal, plastic, or composite material, but is not limited thereto, to meet the strength and durability requirements of the fan. In one embodiment, the fan blade 2 and the hub 1 can be connected by welding, screwing, bonding, or clamping. For example, the fan blade 2 can be bonded to the side wall of the hub 1; or the fan blade 2 can be fixed to the side wall of the hub 1 by screws; or the side wall of the hub 1 can be provided with a clamping groove, and the blade root 23 of the fan blade 2 can be clamped in the clamping groove, which is not limited in the present application. In another embodiment, the fan blade 2 and the hub 1 can be integrally formed, such as cast or injection molded, to make the axial flow fan have better structural strength, thereby prolonging the service life of the axial flow fan. Moreover, the integrally formed axial flow fan also has better running stability, thereby further reducing the possibility of generating noise due to vibration.

[0172] Based on the above description, the basic fan blade 2 is adopted, and the specific verification of the parameters of the fan blade 2 is carried out:

[0173] Table 1 shows the parameter distribution of the basic fan blade 2 under different P values:

[0174] Table 1 shows the data obtained by cutting the fan blade under different P values (P = 0.1, 0.3, 0.5, 0.7, 0.9)

[0175] In Table 1, the original parameters under each P value should meet the following floating range:

[0176] Table 2

[0177] Based on the analysis and optimization of the above basic fan blade 2 parameters, the following parameters of the axial flow fan are obtained:

[0178] Example 1

[0179] Table 3 below is the structural parameters of the axial flow fan of Example 1:

[0180] Table 3 Structural parameters of the axial flow fan of Example 1

[0181] Figure 8 shows the P-Q curve comparison of the axial flow fan provided by Example 1 and other fans of the same specification under the same noise condition. It can be seen that the axial flow fan of Example 1 has more ideal air volume and air pressure in a larger range under the same noise condition. It can be understood that the above-mentioned other fans of the same specification are from the market, and only the overall size of the hub and the fan blade 2 (such as the hub diameter D1 and the fan diameter D3) is the same as the axial flow fan provided by the present application.

[0182] Figure 9 shows the air volume comparison of the axial flow fan provided by Example 1 and other fans of the same specification when the air pressure is the same (all 2.00mmAq). As shown in Figure 9, when the air pressure is 2.00mmAq, the air volume of the axial flow fan in Example 1 is 50CFM (cubic feet per minute), which is better than that of the comparison fans one to four. It shows that the axial flow fan in Example 1 has better fan performance.

[0183] Example 2

[0184] Table 4 below is the structural parameters of the axial flow fan of Example 2

[0185] Table 4 Structural parameters of the axial flow fan of Example 2

[0186] Figure 10 shows the P-Q curve comparison of Example 2 and other fans of the same specification under the same noise condition. As shown in Figure 10, Example 2 has more ideal air volume and air pressure in a larger range under the same noise condition. It can be understood that the above-mentioned other fans of the same specification are from the market, and only the overall size of the hub and the fan blade 2 (such as the hub diameter D1 and the fan diameter D3) is the same as the axial flow fan provided by the present application.

[0187] Figure 11 shows the air volume of the axial flow fan provided in Embodiment 2 of the present application and other fans of the same specification when the air pressure is the same (3.00 mmAq). As shown in Figure 11, the air volume of the axial flow fan in Embodiment 1 is about 48 CFM (cubic feet per minute) when the air pressure is 3.00 mmAq, which is better than that of the comparative fans 5 to 8. This shows that the axial flow fan in Embodiment 2 has a larger air volume at the same air pressure and a larger air pressure at the same air volume, and thus can sufficiently dissipate heat from the heat dissipation component and has better fan performance.

[0188] Figure 12 shows an exploded structural schematic diagram of an axial flow fan provided in an embodiment of the present application. As shown in Figure 12, the axial flow fan includes a frame 3 and the axial flow fan provided in any of the above embodiments, which is rotatably installed in the frame 3 by a power motor. Specifically, the power motor includes a PCB (printed circuit board) 6 for providing power supply and control signal transmission, a stator winding 7, a magnet 8, and a rotating shaft (not shown in the figure), the magnet 8, the rotating shaft, and the axial flow fan are integrally arranged, and the rotating shaft is rotatably connected at the central axis of the frame 3.

[0189] In an embodiment, the frame 3 is provided with noise absorbing material, which is used to reduce the reflection and propagation of the noise of the axial flow fan. For example, the noise absorbing material can be sound-absorbing cotton made of polyester fiber or glass fiber. In some embodiments, the noise absorbing material can also be foamed plastic made of polyethylene, polypropylene, or polystyrene, which is not limited in the present application.

[0190] Optionally, the noise absorbing material can be arranged in or outside the frame 3 as long as it can reduce noise, which is not limited in the present application.

[0191] Optionally, the overall diameter of the axial flow fan can be 9 CM, 12 CM, 13 CM, or 14 CM specification axial flow fan.

[0192] In the present embodiment, the axial flow fan provided in the above embodiment has smaller noise generated during operation, and has better air volume and air pressure at the same decibel noise, which can meet the heat dissipation needs of electronic components and improve the user experience.

[0193] The present disclosure also provides another axial flow fan. Figure 13 is a radial schematic diagram of the axial flow fan provided in an embodiment of the present disclosure, and Figure 14 is an axial schematic diagram of the axial flow fan provided in an embodiment of the present disclosure. Figures 13 and 14 respectively show the shape of the axial flow fan from the radial direction and the axial direction. As shown in Figures 13 and 14, the axial flow fan 100 in the present embodiment includes a hub 110 and at least two fan blades 120.

[0194] The hub 110 is a structural component that mounts the drive motor or the drive motor power output shaft and carries the plurality of blades 120. The hub 110 can be configured as a cylinder. The hub diameter in the axial fan shown in FIGS. 13 and 14 is D, and the hub rotation axis is O (the hub rotation axis O is also the blade rotation axis).

[0195] The blade 120 is a component that drives the airflow when rotating. Typical locations of the blade 120 include a blade root 121, a blade tip 122, a leading edge 123, a trailing edge 124, a pressure surface 125, and a suction surface 126. The blade root 121 is a location where the blade 120 is connected to the hub 110, and the radius at the blade root 121 is D / 2, which is the outer radius of the hub 110. The blade tip 122 is the outermost location in the radial direction of the blade 120. The leading edge 123 is the edge location of the blade that is first contacted by the airflow when the airflow enters the fan. The trailing edge 124 is the edge location of the blade that is last contacted by the airflow when the airflow exits the fan. The pressure surface 125 is the surface of the fan where the static pressure is higher than the back pressure, and the pressure surface 125 faces the outflow side of the axial fan. The suction surface 126 is the surface of the fan where the static pressure is lower than the back pressure, and the suction surface 126 faces the inflow side of the axial fan.

[0196] The blade 120 is profiled using a reference variable cylinder S that is concentric with the hub to obtain a circumferential cross section of the blade at a radius r. FIG. 15 is a schematic view of the circumferential cross section of the blade 120 at a radius r, and FIG. 15 also shows the relative relationship of the leading edge 123, the trailing edge 124, the pressure surface 125, and the suction surface 126. In addition, FIG. 15 also shows a mean camber line 127, a chord line 128, and an installation angle ζ at the circumferential cross section at the radius r.

[0197] The mean camber line 127 refers to a curve formed by connecting points in the circumferential cross section of the blade 120 that are equidistant from the pressure surface 125 and the suction surface 126. The chord line 128 is a straight line connecting two points of the leading edge 123 and the trailing edge 124 in the circumferential cross section. The angle between the chord line 128 and the rotation axis of the fan blade is the installation angle ζ.

[0198] In order to characterize the three-dimensional shape of the axial fan blade using mathematical methods, the present disclosure establishes a coordinate system for the blade 120, and the method of establishing the coordinate system can refer to FIG. 4.

[0199] Specifically, the reference variable cylinder S intersects with the fan blade root to form a circumferential section, and the midpoint of the center curve of the circumferential section is denoted as m. The hub rotation axis is the Z axis, and the rotation direction is the counterclockwise direction of the Z axis projection plane from top to bottom (right-hand rule direction). The plane G is perpendicular to the Z axis and passes through the point m. The X axis passes through the intersection of the Z axis and the plane G and the point m. The positive direction points from the intersection of the Z axis and the plane G to the point m. M is a point on the center curve of the fan blade 120, and the coordinates can be represented as (r, θ, z). r represents the vertical distance between the point M and the Z axis, and the unit of r is mm. θ represents the included angle between the projected line of the line OM on the plane G and the positive X axis, and the unit of θ is rad, and the range is 0 to 2π. The size of z is the minimum vertical distance between the point M and the plane G, and the unit of z is mm.

[0200] Further, returning to FIG. 15, the size of the installation angle ζ can represent the bending degree of the fan blade at the radius r. The chord line 128 is a straight line passing through the two points of the leading edge 123 and the trailing edge 124 of the circumferential section, and can also be regarded as the connecting line between the two end points of the center curve. In addition, the included angle between the chord line 128 and the rotation axis of the fan blade 120 is the installation angle ζ. The smaller the installation angle ζ, the greater the bending degree of the fan blade at the radius r, and the greater the installation angle ζ, the smaller the bending degree of the fan blade at the radius r. That is, as the installation angle ζ increases, the fan blade tends to be closer to the radial plane of the hub (the fan blade tends to be flat). It can also be inferred that the smaller the installation angle ζ, the greater the minimum vertical distance between the point M on the center curve and the plane G (the plane G is perpendicular to the rotation axis) (the greater the value of z).

[0201] In an embodiment, each fan blade can intersect with a plurality of reference variable cylinders S coaxial with the hub to form a plurality of fan blade circumferential sections. Each circumferential section of each fan blade includes a center curve. A coordinate system can be established for each center curve according to the above method. The coordinates of each position point of the center curve can be represented as (r, θ, z).

[0202] In this embodiment, the position points of each center curve of the fan blade can be represented by the equation z = a(rθ) 2 . Specifically, the coefficient a corresponding to a larger radius r of the center curve is greater than the coefficient a corresponding to a smaller radius r. Thus, the height z of the entire center curve gradually decreases as the radius increases, further making the bending degree of the center curve of the fan blade higher near the proximal end of the hub, and gradually tending to be flat as the radius increases towards the blade tip.

[0203] In addition, the coefficient a can take a negative value, that is, the smaller the radius corresponding to the center curve, the smaller the coefficient a, and the greater the absolute value of the coefficient a. Conversely, the greater the radius corresponding to the center curve, the greater the coefficient a, and the smaller the absolute value of the coefficient a. θ can be pre-set within a certain range.

[0204] In one embodiment, the position points of the middle camber line in each of the fan blades can be represented by the equation z=a(rθ-b) 2 In particular, the coefficient b corresponding to the larger radius r of the middle camber line is larger than the coefficient b corresponding to the smaller radius r, so that the middle camber line of the entire fan blade gradually deviates from the incoming flow direction of the axial flow fan as the radius increases. The b represents the relative moving direction of the middle camber line.

[0205] In one embodiment, the position points of the middle camber line in each of the fan blades can be represented by the equation z=a(rθ-b) 2 +c. Wherein a, b and c are linear coefficients, a<0, b>0, r is the radius corresponding to the middle camber line (the radius corresponding to the projection of the middle camber line on the x plane), θ is the angular coordinate of the position point on the middle camber line, and z is the height coordinate of the position point on the middle camber line. The c parameter can be used to represent the reference offset or reference height of the middle camber line in the height direction (z axis).

[0206] The linear speed of air flowing through the fan blade at different radii is different. Structural analysis and force analysis show that the pressure exerted on the flowing air by the fan blade is related to the angle between the air flowing through the fan blade and the contact area between the air and the fan blade. By adjusting the a value at different radii (i.e. adjusting the angle between the air and the fan blade at different radii) and the arc length at different radii (adjusting the relative contact area between the air and the fan blade at different radii), the pressure value and pressure direction experienced by the corresponding air can be adjusted, i.e. the outflow speed and outflow direction of the air flowing through the fan blade can be adjusted.

[0207] The a in the middle camber line coordinate equation corresponding to the smaller radius of the fan blade (a<0) is smaller than the a in the middle camber line coordinate equation corresponding to the larger radius, and the smaller radius corresponds to a smaller θ range and the larger radius corresponds to a larger θ range, which can make the outflow direction consistency of the axial flow fan better and reduce the outflow diffusion along the axial direction to increase the effective outflow. The following comparative analysis of the velocity triangles at two different radii explains why adjusting a according to the aforementioned adjustment strategy can reduce outflow diffusion and increase effective outflow.

[0208] Figure 16a is an exploded schematic view of the velocity triangle at a first radius; Figure 16b is an exploded schematic view of the velocity triangle at a second radius, and the first radius is smaller than the second radius. In Figures 16a and 16b, u represents the tangential velocity of air passing through the fan blade, wr represents the rotational linear velocity of the fan blade at a radius of r, and ua represents the flow velocity of the airflow along the rotation axis.

[0209] Comparing FIG. 16a and FIG. 16b, in order to avoid the air flow spreading outwards along the axial direction, the minimum requirement is to make the flow direction of the air flow at different radii the same (the greater requirement can be to make the air flow at different radii converge towards the rotation axis), that is, it is required to make the flow velocity ua of the air flow at different radii the same (if the flow velocity ua is different, the flow velocity ua corresponding to the second radius is greater than the flow velocity ua corresponding to the first radius, the pressure of the air flow outside is less than the pressure of the air flow inside, so that the air flow spreads outwards along the axial direction). Since the angular velocity of rotation of the fan blade at each position is the same, the circumferential component velocity wr of the wind speed at different radii is not the same, that is, the circumferential component velocity wr of the first radius is less than the circumferential component velocity wr of the second radius. In order to make the flow velocity ua the same, it is required that the tangential velocity at different radii projects different velocities in the direction of the rotation axis, specifically, it is required that the smaller the radius of the position of the fan blade, the greater the value of the velocity of the corresponding tangential velocity projected in the direction of the rotation axis, and the greater the radius of the position of the fan blade, the smaller the value of the velocity of the corresponding tangential velocity projected in the direction of the rotation axis. The axial flow fan blade provided in the above embodiment gradually increases the bending degree of the middle camber line of the fan blade from the fan blade to the blade root, and the greater the bending degree of the middle camber line, the smaller the angle between the tangential direction of the fan blade and the axial direction of the hub, and further the greater the value of the velocity of the tangential velocity projected in the direction of the rotation axis of the hub (that is, the greater the component of the tangential velocity in the direction of the rotation axis).

[0210] In this way, the flow velocity ua of the air flow at different radii of the fan blade is as close as possible, so as to slow down the phenomenon of the air flow spreading outwards along the axial direction.

[0211] In summary, by setting the coefficient a (a<0) in the middle camber line coordinate equation corresponding to the smaller radius to be less than the coefficient a (a<0) in the middle camber line coordinate equation corresponding to the larger radius, the bending degree of the fan blade at the corresponding position gradually decreases as the radius increases, so that the tangential velocity of the incoming flow gradually decreases, and further the flow velocity of the air flow at each position of the fan blade is as close as possible.

[0212] Each position of the fan blade cuts the air at a certain angle during rotation. In the case of a moderate cutting angle, the air flow can flow completely through the entire fan blade. If the cutting angle changes too much, turbulent separation occurs at the rear half position of the suction surface, causing the air flow to decrease, the pressure transient to fluctuate violently, the total static pressure to decrease, and further the fan efficiency to decrease.

[0213] FIG. 17a is a diagram of the air flow flow characteristics of the axial flow fan at a normal air flow speed, and FIG. 17b is a diagram of the air flow flow characteristics of the axial flow fan at a stall air flow speed. Specifically, FIG. 17 shows the cross sections of two fan blades, and also shows the air flow flowing between the two fan blades, and the hollow arrows indicate the flow direction of the air flow (from the leading edge 123 of the fan blade to the trailing edge 124 of the fan blade).

[0214] Comparing Fig. 17a and Fig. 17b, when the fan resistance is increased so that the air flow velocity is reduced to the stall region, the turbulent separation inevitably occurs, resulting in the decrease of the fan efficiency. If the a in the mean camber line coordinate equation corresponding to the smaller radius is greater than the a in the mean camber line coordinate equation corresponding to the larger radius to determine the mean camber line at each position, and the fan blade is formed by using the aforementioned mean camber line, the angle change of the fan blade (relative to the radial plane of the hub) is gentle, which can reduce the problem of the turbulent separation caused by the fan air flow entering the stall region, and further reduce the problem of the decrease of the fan efficiency caused by the turbulent separation.

[0215] In the embodiment, in addition to the a in the mean camber line coordinate equation corresponding to the larger radius being greater than the a in the mean camber line coordinate equation corresponding to the smaller radius, the b in the mean camber line coordinate equation corresponding to the larger radius is greater than the b in the mean camber line coordinate equation corresponding to the smaller radius.

[0216] In the coordinate equation of the mean camber line, the b represents the relative moving direction of the mean camber line of the fan blade. In the case of a < 0, the b in the mean camber line coordinate equation corresponding to the larger radius is greater than the b in the mean camber line coordinate equation corresponding to the smaller radius, so that the mean camber line of the fan blade gradually deviates to the direction of the fan air flow with the increase of the radius. Since the mean camber line gradually deviates to the direction of the fan air flow with the increase of the radius, the blade tip of the fan blade contacts the air flow before the blade root, and exerts the force on the air flow, so that the air flow is subjected to the centripetal force and deviates to the center of the fan blade. The deviation of the air flow to the center of the fan blade can effectively suppress the stall phenomenon and ensure the fan efficiency.

[0217] In an embodiment, in addition to the a in the mean camber line coordinate equation corresponding to the larger radius being greater than the a in the mean camber line coordinate equation corresponding to the smaller radius, and the b in the mean camber line coordinate equation corresponding to the larger radius being greater than the b in the mean camber line coordinate equation corresponding to the smaller radius, the fan blade of the axial flow fan further has the following characteristics: from the direction close to the hub to the direction away from the hub, the angle coordinate corresponding to each position point of the trailing edge of the fan blade gradually increases, and the angle coordinate corresponding to each position point of the leading edge of the fan blade gradually increases.

[0218] According to the gradually increasing angle coordinate corresponding to each position point of the trailing edge of the fan blade and the gradually increasing angle coordinate corresponding to each position point of the leading edge of the fan blade, it can be known that in addition to the mean camber line gradually deviating to the direction of the fan air flow with the increase of the radius, the mean camber line of the fan blade also deviates to the direction of the rotation of the fan with the increase of the radius, so that the fan type of the fan blade is the forward-inclined fan type.

[0219] [Corrected according to Rule 91 on 29.09.2025] FIG. 18a is a schematic diagram of a forward-swept fan blade of an embodiment of the present disclosure. FIG. 18b is a schematic diagram of a radial fan blade for reference, and FIG. 18c is a schematic diagram of a backward-swept fan blade for reference. Here, it is assumed that each fan blade is only different in the arc corresponding to each radius, but the middle arc line equation at the corresponding radius is the same. Referring to the airflow and fan blade fan type in FIGS. 18a-18c, because the tip of the forward-swept fan blade contacts the airflow before the root, combined with the fact that the middle arc line of the fan blade gradually shifts to the direction of the fan inflow as the radius increases, compared to the radial fan blade and the backward-swept fan blade, it can make the airflow further obviously deviate to the center of the fan blade. In addition, the angle coordinate corresponding to each position point of the trailing edge of the forward-swept fan blade gradually increases, so that the intersection between the tail tip and the trailing edge of the fan blade is an obtuse angle, and the airflow deviates from this area when flowing over the fan blade. Compared to the radial fan blade and the backward-swept fan blade, it has less stratification trend problem and airflow has a tendency to converge to the rear tip, so it can more effectively suppress the stall phenomenon and reduce the noise generated by the fan operation.

[0220] In an embodiment, the plurality of radii includes at least three of the following radii in mm: r1 ∈ (25.705, 27.295), r1 ∈ (29.585, 31.415), r3 ∈ (33.465, 35.535), r4 ∈ (37.345, 39.655), r5 ∈ (41.225, 43.775), r6 ∈ (45.105, 47.895), r7 ∈ (48.985, 52.015), and r8 ∈ (52.865, 56.135).

[0221] From r1 to r8, the value range of a in the middle arc line coordinate equation corresponding to each radius is (-0.011519689, -0.003119689), (-0.009185063, -0.004385063), (-0.008649787, -0.004249787), (-0.007840749, -0.004440749), (-0.007065648, -0.004265648), (-0.00634749, -0.00374749), (-0.005704969, -0.003104969), (-0.005646877, -0.002246877), respectively.

[0222] In an embodiment, the value ranges of b in the central camber line coordinate equation corresponding to each radius r1 to r8 are (31.41397475, 57.24297475), (35.67459397, 59.80259397), (39.16665805, 64.05565805), (43.26887814, 69.05887814), (50.1852636, 74.4952636), (61.37546577, 80.15546577), (66.99512971, 96.95512971) and (74.14539731, 112.9853973) in sequence.

[0223] In an embodiment, the value ranges of c in the central camber line coordinate equation corresponding to each radius r1 to r8 are (9.62845506, 17.02845506), (9.55830966, 15.55830966), (9.38681835, 14.58681835), (9.23807747, 14.03807747), (9.95227863, 13.35227863), (10.8127758, 13.4127758), (11.56604664, 14.56604664) and (11.60406431, 16.20406431) in sequence.

[0224] In a specific example one, the outer diameter of the axial flow fan is determined to be 120 mm, the hub diameter is 42 mm, the blade gap is 3 mm, the design air volume is 32 cfm, and the design air pressure is 2.1 mmAq according to the use environment conditions. The flow channel space is determined to be a cylindrical annular space with an inner diameter of 42 mm, an outer diameter of 114 mm, and a maximum thickness of no more than 25 mm according to the foregoing parameters. According to the foregoing design indicators and the ability to obtain a relatively smooth central camber curve, it is determined that the central camber line equation of the axial flow fan at eight radii meets z=a(rθ-b) 2 +c in sequence from the inside to the outside, r1=26.5 mm, r2=30.5 mm, r3=34.5 mm, r4=38.5 mm, r5=42.5 mm, r6=46.5 mm, r7=50.5 mm, and r8=54.5 mm.

[0225] According to the foregoing specific parameters and the value size relationship of the central camber line equation, simulation experiments are performed to determine the central camber line linear coefficients that meet the design indicators as shown in Table 5, and the angle coordinate ranges corresponding to each radius are shown in Table 6.

[0226] Table 5: Linear coefficients of the central camber line equation corresponding to each radius in example one

[0227] Table 6: Angle coordinate range corresponding to each radius in Example 1

[0228] Fig. 19 is a graph of the axial flow fan pressure-flow rate curve in Example 1. The black line in Fig. 19 shows the flow rate of the axial flow fan provided in this example under various external wind pressure conditions. From the trend that the wind pressure of the black line decreases with the increase of the flow rate, it can be seen that the axial flow fan provided in this example does not have a stall region and can work normally under various external wind pressure conditions. Fig. 19 also shows the wind pressure-flow rate change of two comparative axial flow fans. According to the curves corresponding to the two comparative examples, it can be seen that the two comparative axial flow fans have stall problems in a specific wind pressure-flow rate range.

[0229] After determining the optimal linear coefficient of this example, the optimal linear coefficient is moderately expanded based on the foregoing optimal linear coefficient. It is determined that after the sector control coefficient is appropriately adjusted based on the data in Table 5, the axial flow fan still meets the design index. The corresponding sector control coefficient adjustment range is shown in Table 7.

[0230] Table 7: Change range of linear coefficient corresponding to each radius in Example 1

[0231] That is, based on Table 7, the change range of the arc coordinate equation coefficient in a specific application can be as follows:

[0232] (1) From r1 to r8, the value range of a in the arc coordinate equation corresponding to each radius is (-0.011519689, -0.003119689), (-0.009185063, -0.004385063), (-0.008649787, -0.004249787), (-0.007840749, -0.004440749), (-0.007065648, -0.004265648), (-0.00634749, -0.00374749), (-0.005704969, -0.003104969), (-0.005646877, -0.002246877), respectively.

[0233] (2) The value ranges of b in the middle camber line coordinate equation corresponding to each radius r1 to r8 are (31.41397475, 57.24297475), (35.67459397, 59.80259397), (39.16665805, 64.05565805), (43.26887814, 69.05887814), (50.1852636, 74.4952636), (61.37546577, 80.15546577), (66.99512971, 96.95512971) and (74.14539731, 112.9853973) in sequence;

[0234] (3) The value ranges of c in the middle camber line coordinate equation corresponding to each radius r1 to r8 are (9.62845506, 17.02845506), (9.55830966, 15.55830966), (9.38681835, 14.58681835), (9.23807747, 14.03807747), (9.95227863, 13.35227863), (10.8127758, 13.4127758), (11.56604664, 14.56604664) and (11.60406431, 16.20406431) in sequence.

[0235] Based on the appropriate error adjustment of the trailing edge and leading edge ranges corresponding to each radius in this example, the angle ranges shown in Table 8 are determined, and the linear coefficients of the middle camber line formed as shown in Table 5 and Table 7 can still be used.

[0236] Table 8 Angle coordinate ranges corresponding to each radius in Example 1

[0237] In another example 2, the design constraints of the provided axial flow fan, the number of radii for which the middle camber line needs to be generated and the radius values are the same as in example 1, only the linear coefficients in the middle camber line corresponding to each radius are different. Table 9 is the linear coefficients in the middle camber line equation corresponding to each radius in example 2, and Table 10 is the angle coordinate ranges corresponding to each radius in example 2.

[0238] Table 9 Linear coefficients in the middle camber line equation corresponding to each radius in Example 2

[0239] Table 10 Angle coordinate ranges corresponding to each radius in Example 2

[0240] In another example three, the design constraints of the axial flow fan, the number of radii of the generated middle camber line and the radius values are the same as example one, only the linear coefficients of the middle camber line corresponding to each radius are different. Table 11 is the linear coefficients of the middle camber line equation corresponding to each radius in example two, and table 12 is the angle coordinate range corresponding to each radius in example two.

[0241] Table 11 is the linear coefficients of the middle camber line equation corresponding to each radius in example three

[0242] Table 12 is the angle coordinate range corresponding to each radius in example three

[0243] In another example four, the design constraints of the axial flow fan, the number of radii of the generated middle camber line and the radius values are the same as example one, only the linear coefficients of the middle camber line corresponding to each radius are different. Table 13 is the linear coefficients of the middle camber line equation corresponding to each radius in example four, and table 14 is the angle coordinate range corresponding to each radius in example four.

[0244] Table 13 is the linear coefficients of the middle camber line equation corresponding to each radius in example four

[0245] Table 14 is the angle coordinate range corresponding to each radius in example four

[0246] The linear coefficients in the above examples two to four are within the coefficient range defined in example one.

[0247] In another example five, the installation angle of each radius in example one is shown.

[0248] Table 15 is the installation angle of each radius in example one

[0249] As can be seen from example five, the angle of the installation angle ζ gradually increases with the increase of the radius of the fan blade. Since the smaller the installation angle ζ represents the greater the bending degree of the fan blade at the radius r, and the greater the installation angle ζ represents the smaller the bending degree of the fan blade at the radius r. Through this example, it can be shown that the bending degree of the fan blade gradually decreases with the increase of the radius of the fan blade.

[0250] The foregoing analyzes the qualitative structural characteristics of the fan blade of the axial flow fan of the present disclosure, and the following analyzes how to design the fan of the present disclosure.

[0251] In an embodiment, the method of determining the middle camber line of the fan blade can be used to design the axial flow fan.

[0252] Determine the middle arc line corresponding to each radius of the fan blade of the axial flow fan. Specifically, each of the plurality of reference variable cylinders S passing through the fan blade coaxial with the hub forms a plurality of fan blade circumferential sections, each of which has a middle arc line. For each position point of the middle arc line, there is a radius r, an angle θ of the middle arc line position point, and a height z of the middle arc line position point.

[0253] Based on the middle arc line corresponding to each radius, generate a three-dimensional fan blade model, and generate a three-dimensional fan model based on the three-dimensional fan blade model.

[0254] Figure 20 shows the overall design flowchart of the fan of the embodiment of the present disclosure. As shown in Figure 20, the overall design flowchart of the fan of the embodiment of the present disclosure includes S110-S130.

[0255] S110: Determine the middle arc line coordinate equation corresponding to each radius of the fan blade of the axial flow fan, and initialize the linear coefficient of the middle arc line coordinate equation at each radius and the angle coordinate range.

[0256] As previously analyzed, the middle arc line coordinate equation at each radius in the embodiment of the present disclosure is z=a(rθ-b) 2 +c, a, b and c are linear coefficients, a<0, b>0, r is the radius corresponding to the middle arc line, θ is the angle coordinate of the position point on the middle arc line, and z is the height coordinate of the position point on the middle arc line.

[0257] In addition, when initializing the linear coefficient of the middle arc line coordinate equation, a in the middle arc line coordinate equation corresponding to a larger radius is greater than a in the middle arc line coordinate equation corresponding to a smaller radius, and b in the middle arc line coordinate equation corresponding to a larger radius is greater than b in the middle arc line coordinate equation corresponding to a smaller radius.

[0258] In specific implementation, the linear coefficient of the middle arc line coordinate equation at each radius and the angle coordinate range can be generally determined according to empirical parameters. As previously analyzed, when determining the linear coefficient of the middle arc line coordinate equation at each radius, the above indexes should be met.

[0259] S120: Generate a three-dimensional fan blade model based on the middle arc line coordinate equation and the angle coordinate range, and generate a three-dimensional fan model based on the three-dimensional fan blade model.

[0260] In specific implementation, after generating a three-dimensional fan blade model according to the angle coordinate range, a three-dimensional fan model can be generated based on the three-dimensional fan blade model according to the number of fan blades and hub parameters determined as needed.

[0261] S130: Perform fluid simulation test on the three-dimensional fan model, and determine whether the simulation result meets the set index; if not, perform S140.

[0262] If yes, perform S150;

[0263] S140: adjust the linear coefficients of each camber line coordinate equation or the coordinate range of each radius camber line angle coordinate, and perform S120.

[0264] S150: end the execution.

[0265] In a specific implementation, a computational fluid dynamics (CFD) software can be used to simulate the three-dimensional model of the axial fan to obtain simulation results. In a specific implementation, the simulation results can include simulation evaluation flow, simulation evaluation wind pressure, simulation effective efficiency, and simulation noise.

[0266] Corresponding to the various simulation results described above, the design indicators include flow indicators, wind pressure indicators, conversion efficiency indicators, and noise indicators. In one specific application, the three-dimensional model of the axial fan is determined to meet the actual design indicators only when each of the simulation results described above meets the corresponding design indicators.

[0267] If the simulation results do not meet the design indicators, it is determined that the linear coefficients of the camber line coordinate equation or the coordinate range of each radius camber line coordinate need to be adjusted, and the three-dimensional fan blade model and the three-dimensional fan model are regenerated and simulation testing is performed again. That is, in actual execution, S120-S140 will most likely be repeated multiple times. It should be noted that during the repeated execution of S140 to adjust the linear coefficients of each camber line coordinate equation, it is necessary to always ensure that a in the camber line coordinate equation corresponding to a larger radius is greater than a in the camber line coordinate equation corresponding to a smaller radius, and b in the camber line coordinate equation corresponding to a larger radius is greater than b in the camber line coordinate equation corresponding to a smaller radius.

[0268] In addition, in some embodiments, during the initialization of the angle coordinate range of the fan blade at each radius in S110 and the adjustment of the angle coordinate range of each radius camber line in S140, the angle coordinate range is made to satisfy the following conditions: from the direction close to the hub to the direction away from the hub, the angle coordinate at the trailing edge position of the fan blade corresponding to each radius gradually increases, and the angle coordinate at the leading edge position of the fan blade corresponding to each radius gradually increases, so that the fan blade fan type is a forward-inclined fan type.

[0269] [Corrected according to Rule 91 on 29.09.2025] Figure 21 shows a flowchart of a method for determining the fan type of an axial fan using a simulation analysis method, and Figure 21 further expands the analysis of the design method of the axial fan described above. As shown in Figure 21, the method for determining the camber line three-dimensional fan type includes S210-S290.

[0270] S210: determine the flow passage space according to the design constraint conditions.

[0271] The design constraints mainly include the size constraints of the axial flow fan, such as the maximum blade size of the axial flow fan, the size of the hub, the size of the flow passage space, the number of blades, the angle coordinate range at different positions of the blades, and the like.

[0272] In one specific embodiment, the axial flow fan is arranged in a fan assembly. In order to determine the forming space of the blades, first, the size of the fan frame of the fan assembly is determined according to the size of the installation space in the actual application scenario, the size of the hub is determined according to the size of the motor used, and then the forming space of the blades is determined according to the size of the fan frame, the size of the hub and the inter-blade gap to be reserved.

[0273] [According to Rule 91 Correction 29.09.2025] FIG. 22 is a schematic diagram of an axial cross-section of an axial flow fan, which shows that the flow passage space of the axial flow fan is a part of the flow passage space, which is determined by three parameters, i.e., the size of the fan frame 300, the size of the hub 100 and the inter-blade gap to be reserved. Referring to FIG. 22, it can be seen that the flow passage space of the axial flow fan is a circular ring space.

[0274] S220: Determine the radius size of the middle-arc line to be generated according to the flow passage space, and form the control section according to the radius size.

[0275] [According to Rule 91 Correction 29.09.2025] FIG. 23 is a schematic diagram of generating a control section based on the radius size that has been determined. FIG. 24 shows the fan hub and the control sections formed based on the radius sizes. As can be seen from FIG. 22, each control section is a cylindrical side surface.

[0276] S230: Establish a cylindrical coordinate system in the flow passage space, and generate a middle-arc line control curve in the corresponding control section according to the middle-arc line equation and the linear coefficient for each radius.

[0277] In actual execution, the middle-arc line control curve needs to be determined multiple times through iteration. In the first execution, the linear coefficient corresponding to each radius can be determined by experience; in subsequent executions, the linear coefficient corresponding to each radius can be determined by simulation model feedback data.

[0278] It should be noted here that the sector control parameters in the middle-arc line equation corresponding to each radius in S130 should meet the description in the foregoing, i.e., a in the middle-arc line coordinate equation corresponding to a smaller radius is smaller than a in the middle-arc line coordinate equation corresponding to a second radius, b in the middle-arc line coordinate equation corresponding to a smaller radius is larger than b in the middle-arc line coordinate equation corresponding to a second radius, the angle coordinate of the trailing edge of the middle-arc line of a smaller radius is smaller than the angle coordinate of the trailing edge of a larger radius, and the angle coordinate of the leading edge of the middle-arc line of a smaller radius is smaller than the angle coordinate of the leading edge of the middle-arc line of a larger radius.

[0279] S240: generating corresponding fan blade profile curve based on camber line control curve and fan blade thickness.

[0280] [Corrected according to Rule 91 on 29.09.2025] In the specific embodiment, each camber line control curve can be directly unfolded in three-dimensional space, or can be unfolded in a two-dimensional plane first. Figure 24 shows a schematic diagram of unfolding the camber line control curve directly in three-dimensional space in one embodiment. Figure 25 shows a schematic diagram of unfolding the camber line control curve in a two-dimensional plane in another embodiment. After obtaining each camber line control curve, the corresponding fan blade profile curve can be generated according to the camber line control curve and the fan blade thickness. In the specific implementation, the corresponding fan blade profile curve can be generated for each camber line control curve according to the NACA blade shape or the variant blade shape to be generated as needed.

[0281] S250: smoothly connecting each radius corresponding fan blade profile curve to form a local three-dimensional fan blade model, and expanding the local three-dimensional fan blade to form a complete three-dimensional fan blade model.

[0282] Smoothly connecting the fan blade profile curve to obtain the local three-dimensional fan blade is performed by the smoothing tool in the design software, which will not be expanded here. After obtaining the local three-dimensional fan blade model, the root region and the tip of the local three-dimensional fan blade model can be expanded to form a complete three-dimensional fan blade model.

[0283] Figure 26 is a structural schematic diagram of forming a complete three-dimensional fan blade model. Each dark closed curve represents a fan blade profile curve at the corresponding position.

[0284] S260: generating a three-dimensional model of the axial flow fan based on the complete three-dimensional fan blade model, the hub model, and the number of fan blades.

[0285] Generating a three-dimensional model of the axial flow fan based on the complete three-dimensional fan blade model, the hub model, and the number of fan blades is to generate a corresponding number of three-dimensional fan blades according to the number of fan blades, then arrange each three-dimensional fan blade uniformly in the circumferential direction with the rotation axis of the hub model as the center line, and make the root of each three-dimensional fan blade connected with the hub model.

[0286] Figure 27 shows a schematic diagram of a three-dimensional model of an axial flow fan formed by splicing. The number of fan blades of the axial flow fan shown in Figure 27 is 7.

[0287] S270: performing simulation calculation on the three-dimensional model of the axial flow fan, and outputting the simulation result.

[0288] In some embodiments, a three-dimensional model of the axial flow fan can be simulated by using a computational fluid dynamics (CFD) software to obtain simulation results. The simulation results include a simulation evaluation flow, a simulation evaluation pressure, a simulation effective efficiency, and a simulation noise.

[0289] S280: determining whether the simulation results meet the design index requirements; if yes, performing S190; if no, adjusting the linear coefficient and performing S130.

[0290] Corresponding to the various simulation results described above, the design index includes a flow index, a pressure index, a conversion efficiency index, and a noise index. In one specific application, the three-dimensional model of the axial flow fan is determined to meet the actual design index only when each of the simulation results described above meets the corresponding design index.

[0291] S290: outputting the three-dimensional model of the axial flow fan.

[0292] In addition to providing the axial flow fan and the axial flow fan design method described above, the embodiments of the present disclosure also provide a fan assembly using the axial flow fan described above. The fan assembly includes the axial flow fan described above and a driving motor arranged in the hub of the axial flow fan. When the driving motor is powered and rotated, the axial flow fan is driven to rotate.

[0293] In some embodiments, the fan assembly can further include a fan frame, which is arranged outside the axial flow fan to protect the fan blades of the axial flow fan from being damaged by external objects.

[0294] The embodiments of the present disclosure also provide a case including the axial flow fan provided by the above-described embodiments. Exemplarily, the axial flow fan provided by the embodiments of the present disclosure is mounted on a side panel in the case and used to dissipate heat of a heating component in the case. The axial flow fan can be connected to the case by means of bolt connection, adhesion, or clamping connection, which is not limited herein. With the case using the axial flow fan described above, the noise generated by the axial flow fan is low, so that the overall noise generated by the case is reduced. Meanwhile, the axial flow fan has more ideal air volume and air pressure in a larger range when working, which can meet the heat dissipation requirement of the heating component in the case and ensure the service life of the heating component in the case.

[0295] The position relationship, quantity, structural shape, and gas flow direction of each component of the axial flow fan provided by the embodiments of the present disclosure are not limited to the above-described embodiments, and any technical solution realized under the principle of the present disclosure is within the protection scope of the present disclosure. Any one or more embodiments or drawings in the specification, which are combined in a suitable manner, are within the protection scope of the present disclosure.

[0296] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application. Those skilled in the art should understand that, although the present application has been described in detail with reference to the foregoing embodiments, modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent replacements can be made to some of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions in the embodiments of the present application.

Claims

1. An axial flow fan characterised in that, The hub comprises: At least two blades are installed on the outer circumferential surface of the hub in an annular array, the blades are arranged obliquely to the axis of the hub, and the blades comprise a blade root connected to the hub and a blade tip at the end of the blade extending radially from the hub, the blade root smoothly extends to the blade tip, and the size of the middle camber line of the circumferential section of the blade gradually increases; a leading edge and a trailing edge are arranged between the blade root and the blade tip, and the leading edge and the trailing edge are curved into arcs towards the rotating direction of the blade. Wherein, ξ0, ξ1 and ξ2 are linear coefficients, r is the radius corresponding to the middle camber line, θ is the angular coordinate of the position point on the middle camber line, and z is the height coordinate of the position point on the middle camber line; when P is between 0.1 and 0.9, the coefficient ξ0 is between -0.0058 and -0.0044, ξ1 is between 0.5915 and 0.8415, and ξ2 is between -27.2123 and 0.0303, the error range of the coefficient ξ0 is ±0.00024, the error range of the coefficient ξ1 is ±0.028, and the error range of the coefficient ξ2 is ±2.

354.

2. The axial fan according to claim 1, characterized in that Each of the blade sector and the plurality of reference variable cylinders S coaxial with the hub are mutually penetrated to form a plurality of sector circumferential sections; the ratio of the diameter D2 of the plurality of reference variable cylinders S minus the diameter D1 of the hub to the maximum diameter D3 of the blade sector minus the diameter D1 of the hub is P; a coordinate system is established by corresponding mean camber lines of the plurality of sector circumferential sections, to obtain coordinates of a plurality of points on the mean camber lines; the coordinates of the plurality of points are fitted by using the least square method to obtain: z=ξ0*(r*θ)+ξ1*r*θ+ξ2 2 +ξ1*r*θ+ξ2 3. The axial flow fan according to claim 2, wherein, when P=0.10, ξ0=-0.0056, ξ1=0.5997, and ξ2=0.0272; when P=0.30, ξ0=-0.0056, ξ1=0.6606, and ξ2=-5.5733; when P=0.50, ξ0=-0.0054, ξ1=0.7216, and ξ2=-11.2962; when P=0.70, ξ0=-0.0049, ξ1=0.7730, and ξ2=-17.4675; when P=0.90, ξ0=-0.0044, ξ1=0.8178, and ξ2=-24.8580.

4. The axial flow fan according to claim 2, wherein, when P=0.10, ξ0=-0.0055, ξ1=0.5959, and ξ2=0.0303; when P=0.30, ξ0=-0.0055, ξ1=0.6756, and ξ2=-6.7042; when P=0.50, ξ0=-0.0053, ξ1=0.7476, and ξ2=-13.1921; when P=0.70, ξ0=-0.0049, ξ1=0.8010, and ξ2=-19.7954; when P=0.90, ξ0=-0.0044, ξ1=0.8415, and ξ2=-27.2123.

5. The axial flow fan according to claim 2, wherein, when P=0.10, ξ0=-0.0058, ξ1=0.5915, and ξ2=0.0240; when P=0.30, ξ0=-0.0058, ξ1=0.6491, and ξ2=-4.9237; when P=0.50, ξ0=-0.0056, ξ1=0.7144, and ξ2=-10.4364; ​ When P=0.70, ξ0=-0.0052, ξ1=0.7675, ξ2=-16.3333; When P=0.90, ξ0=-0.0046, ξ1=0.8049, ξ2=-27.7129.

6. The axial fan according to any one of claims 2-5, characterized in that When P is between 0.1 and 0.9, the angle A1 between the line L2 connecting the center point a of the axial projection of the reference circumferential section of the fan blade along the hub and the hub center O and the line L1 connecting the center point b of the axial projection of the blade root along the hub and the hub center O is between 14.77v° and 72.01v°, where v is an error adjustment coefficient and the range value is ±10°.

7. An axial fan as claimed in any one of claims 2 to 5, characterized in that When P is between 0.1 and 0.9, the angle A2 between the line L3 connecting the intersection point c of the axial projection of the reference circumferential section of the fan blade along the hub and the axial projection of the leading edge along the hub and the tangent line L4 of the leading edge at the point c and the hub center O is between 42.24t° and 55.83t°, where t is an error adjustment coefficient and the range value is ±7°.

8. An axial fan as claimed in any one of claims 2 to 5, characterized in that When P is between 0.1 and 0.9, the angle A3 between the line L5 connecting the intersection point d of the axial projection of the reference circumferential section of the fan blade along the hub and the axial projection of the trailing edge along the hub and the tangent line L6 of the trailing edge at the point d and the hub center O is between 42.35u° and 58.00u°, where u is an error adjustment coefficient and the range value is ±5°.

9. An axial fan as claimed in any one of claims 2 to 5, characterized in that The length of the line connecting the intersection point c of the axial projection of the reference circumferential section of the fan blade along the hub and the axial projection of the leading edge along the hub and the intersection point d of the axial projection of the reference circumferential section of the fan blade along the hub and the axial projection of the trailing edge along the hub is the projected outer arc length cd, and the length of the line connecting the intersection point e of the axial projection of the tip along the hub and the axial projection of the leading edge along the hub and the intersection point f of the axial projection of the tip along the hub and the axial projection of the trailing edge along the hub is the tip arc projection length ef, and the ratio Q=cd / ef is between 0.47 and 0.

97.

10. An axial fan as claimed in any one of claims 1 to 5, characterized in that The circumferential section of the hub is circular, and the hub is closed at one end and open at the other end along the axial direction, and an axle seat is installed in the internal area surrounded by the hub, and the axle seat and the hub are connected by a plurality of annularly arranged ribs, and the axle seat is used to install a rotating shaft used in cooperation with the hub.

11. The axial fan according to claim 10, wherein The height of the blade root along the axial direction of the hub is between 1 / 2 and 2 / 3 of the height of the hub, and the connection point of the blade root and the trailing edge is closer to the open side of the hub than the connection point of the blade root and the leading edge.

12. The axial fan of claim 10, wherein, The axial height of the leading edge gradually increases from the blade root to the tip, and the connection point of the tip and the leading edge is closer to the highest point of the axial height of the hub than the connection point of the trailing edge and the tip.

13. An axial fan as claimed in any one of claims 1 to 5, characterized in that The connection point of the tip and the leading edge and the trailing edge is a circular arc chamfer structure.

14. An axial fan as claimed in any one of claims 1 to 5, characterized in that The thickness of the fan blade gradually increases from the leading edge to the trailing edge and then gradually decreases, so that the curved surface of the fan blade is smoother.

15. An axial flow fan characterised in that, The thickness of the fan blade gradually increases from the leading edge to the trailing edge and then gradually decreases, so that the curved surface of the fan blade is smoother. The thickness of the fan blade gradually increases from the leading edge to the trailing edge and then gradually decreases, so that the curved surface of the fan blade is smoother. A wheel hub; The device comprises at least two fan blades; each fan blade intersects with multiple reference variable cylinders S coaxial with the hub to form multiple circumferential cross sections, each fan blade circumferential cross section having a mid-arc line; for each position point of each mid-arc line, there are a radius r, an angle θ of the mid-arc line position point, and a height z of the mid-arc line position point; wherein, for each mid-arc line position point, the equation z = a(rθ) is used. 2 Let be used to represent ; where, for different mid-arc lines, the coefficient 'a' corresponding to the mid-arc line with a larger radius is greater than the coefficient 'a' corresponding to the mid-arc line with a smaller radius, so that the degree of curvature of the fan blade is higher near the hub, while as the radius increases towards the blade tip, the degree of curvature of the fan blade gradually becomes gentler.

16. An axial fan as claimed in claim 15, c h a r a c t e r i s e d in that For each camber line position point, it can also be expressed by equation z=a(rθ-b) 2 ; wherein, the coefficient b corresponding to the larger radius r of the camber line is larger than the coefficient b corresponding to the smaller radius r, so that the camber line of the fan gradually deviates from the flow direction of the axial flow fan as the radius increases.

17. An axial fan as claimed in claim 16, c h a r a c t e r i s e d in that For each point on the mid-arc line, the equation z = a(rθ - b) can also be used. 2 +c represents the reference offset or reference height of the fan blade's center arc in the height direction; where the coefficient c is used to characterize the reference offset or reference height of the fan blade's center arc in the height direction.

18. An axial fan as claimed in any of claims 15 to 17, wherein The angle coordinate corresponding to each position point of the trailing edge of the fan blade gradually increases from the direction close to the wheel hub to the direction far from the wheel hub, and the angle coordinate corresponding to each position point of the leading edge of the fan blade gradually increases.

19. The axial fan of claim 16, wherein, The radii corresponding to the plurality of middle-arc lines include at least three radii in mm as follows: r1 ∈ (25.705, 27.295), r1 ∈ (29.585, 31.415), r3 ∈ (33.465, 35.535), r4 ∈ (37.345, 39.655), r5 ∈ (41.225, 43.775), r6 ∈ (45.105, 47.895), r7 ∈ (48.985, 52.015), and r8 ∈ (52.865, 56.135); The value ranges of a in the middle-arc line coordinate equation corresponding to each radius from r1 to r8 are, in sequence, (-0.011519689, -0.003119689), (-0.009185063, -0.004385063), (-0.008649787, -0.004249787), (-0.007840749, -0.004440749), (-0.007065648, -0.004265648), (-0.00634749, -0.00374749), (-0.005704969, -0.003104969), and (-0.005646877, -0.002246877); The value ranges of b in the middle-arc line coordinate equation corresponding to each radius from r1 to r8 are, in sequence, (31.41397475, 57.24297475), (35.67459397, 59.80259397), (39.16665805, 64.05565805), (43.26887814, 69.05887814), (50.1852636, 74.4952636), (61.37546577, 80.15546577), (66.99512971, 96.95512971), and (74.14539731, 112.9853973).

20. The axial fan of claim 17, wherein, The value ranges of the radius corresponding to each of the middle-arc-line coordinates from r1 to r8 are (9.62845506, 17.02845506), (9.55830966, 15.55830966), (9.38681835, 14.58681835), (9.23807747, 14.03807747), (9.95227863, 13.35227863), (10.8127758, 13.4127758), (11.56604664, 14.56604664) and (11.60406431, 16.20406431) respectively.

21. The axial fan of claim 18, wherein, The value ranges of the angle coordinates corresponding to each of the position points of the blade trailing edge from r1 to r8 are (-0.388, -0.312), (-0.258, -0.122), (-0.161, 0.001), (-0.07, 0.110), (0.012, 0.208), (0.080, 0.320) respectively. The value ranges of the angle coordinates corresponding to each of the position points of the blade leading edge from r1 to r8 are (0.327, 0.393), (0.412, 0.548), (0.499, 0.661), (0.600, 0.780), (0.682, 0.878), (0.750, 0.990), (0.850, 1.090) and (0.970, 1.210) respectively.

22. A method of designing an axial fan, characterized by The method comprises: determining the middle-arc-lines of the axial fan at a plurality of radii corresponding to the blade, wherein each of the blades intersects a plurality of reference variable cylinders S coaxial with the hub to form a plurality of blade circumferential sections, each of the blade circumferential sections having a middle-arc-line; for each of the middle-arc-lines, each position point has a radius r, an angle θ of the middle-arc-line position point and a height z of the middle-arc-line position point; generating a three-dimensional blade model based on the middle-arc-lines corresponding to the plurality of radii, and generating a three-dimensional fan model based on the three-dimensional blade model.

23. The method of designing according to claim 22, wherein, In the initialization of the angle coordinate range of the blade at each radius and the adjustment of the angle coordinate range of the middle-arc-line at each radius, the angle coordinate range satisfies the following conditions: from the direction close to the hub to the direction away from the hub, the angle coordinates of the position points of the blade trailing edge corresponding to each of the radii gradually increase, and the angle coordinates of the position points of the blade leading edge corresponding to each of the radii gradually increase.

24. A fan assembly characterized by, The axial fan of any one of claims 1-21; and a driving motor arranged in the hub of the axial fan.

25. A chassis, characterized by The axial fan of claim 24 is installed on a side panel in a cabinet for dissipating heat of a heat-generating component in the cabinet.

Images