A micro heat-dissipation axial flow fan based on multi-features of blades

Abstract

The application discloses a novel miniature heat-dissipating axial flow fan, which comprises a hub, a plurality of moving blades arranged on the hub, a flow guide cover, a casing, a support and a magnetic ring; the flow guide cover is located on the incoming flow side and the outlet side of the casing, the axial distance of the flow guide cover on the outlet side is greater than that on the incoming flow side; the support is located on the outlet side of the casing and is used for supporting the casing; the moving blades are controlled by a plurality of spline curves and Bezier curves, and the moving blades are controlled according to the parameters of each interface layer of the blades; each moving blade is divided into six spatial sections from the hub to the blade tip, which are layer1-layer6 respectively, and the position of the spatial section is determined by Span; wherein the moving blades are controlled by Bezier curves to control the sweep degree, the leading edge of the moving blades in the meridian direction is distributed in an S-shaped mode of first sweep, then reverse sweep and then first sweep again from the blade tip to the blade root, and the trailing edge of the moving blades is distributed in an S-shaped mode of first sweep, then reverse sweep and then first sweep again.

Description

Technical Field

[0001] This invention belongs to the technical field of heat dissipation devices for electronic devices, and specifically relates to a miniature heat dissipation axial fan based on multi-feature blade design. Background Technology

[0002] Miniature cooling fans are widely used in traditional and modern instruments and equipment such as computers, communication products, optoelectronic products, consumer electronics, automotive electronic equipment, switches, medical equipment, heaters, air conditioners, inverters, ATMs, car refrigerators, welding machines, induction cookers, audio equipment, environmental protection equipment, and refrigeration equipment. Common types of cooling fans include centrifugal fans, blowers, mixed-flow fans, cross-flow fans, frameless fans, and axial fans.

[0003] Miniature axial cooling fans are primarily used in highly integrated devices, and their main structure is very compact. The main body consists of rotor blades, upstream and downstream supports, a rectangular frame, and a shroud. Internally, miniature components such as magnetic rings, coils, and bearings are used to drive the fan to rotate stably.

[0004] The main indicators for evaluating the performance of cooling fans are aerodynamic properties such as airflow, efficiency, and noise. The performance of a cooling fan can be altered to varying degrees by changing components other than the impeller. However, the characteristics of the blades themselves, such as tip clearance, blade sweep, inlet and outlet angles of the leading and trailing edges, blade thickness, ellipticity at the blade root, local protrusions on the blade edge, or biomimetic technologies such as eagle wing-inspired blades, humpback whale pectoral fin-inspired blades, owl wing-inspired blades, and tropical rainforest leaf-inspired blades, can significantly improve cooling fan performance.

[0005] Miniature axial cooling fans are compact in structure and small in size, but have relatively large radial clearances, resulting in complex internal flow characteristics under high-speed blade motion. Modifying the overall fan structural parameters to reduce leakage vortices caused by leaking airflow ultimately optimizes the flow field, improves aerodynamic performance, and reduces noise. Current research often focuses on local optimization of individual blade characteristics to improve the aerodynamic performance of cooling fans, neglecting to optimize the combined characteristics of all blades to achieve an overall performance improvement. Therefore, it is urgent to develop a global optimization method for various characteristics of composite blades. Summary of the Invention

[0006] To address the aforementioned technical problems in existing technologies, this invention provides a miniature cooling axial fan based on multi-feature blade design. Addressing the limitations of existing fan optimization, this invention proposes a novel miniature cooling axial fan design incorporating composite fan sweep characteristics, thickness variability, polynomial curve control of blade structure, and blade leading and trailing edge ellipticity, thereby improving performance while reducing fan noise.

[0007] The technical solution adopted in this invention is:

[0008] A miniature axial flow fan with multi-feature blade design is characterized by comprising a hub, a plurality of moving blades mounted on the hub, a shroud, a housing, a support, and a magnetic ring; the shroud is located on the inflow side and the outlet side of the housing, with the axial distance of the shroud on the outlet side being greater than the axial distance of the shroud on the inflow side; the support is located on the outlet side of the housing and is used to support the housing; the magnetic ring is pressed into the hub and is coupled to a drive shaft by a spring and a double ball bearing; the drive shaft passes through a coil and a PCB board in sequence and is then fixedly installed in a groove in the support plate by a snap fastener and connected to the transmission structure; the PCB board is fixed inside the support; the moving blades are controlled by multiple spline curves and Bézier curves, and the moving blades are controlled according to the parameters of each interface layer of the blade; each moving blade is divided into 6 spatial sections from the hub to the blade tip, namely layer 1 to 6, and a span is introduced to determine the position of the spatial section;

[0009] The moving blade is controlled by a Bezier curve to control its sweeping degree. The moving blade has an S-shaped distribution from the leading edge tip to the root in the meridional direction, which is swept forward, then swept backward, and then swept forward again. The trailing edge of the moving blade has an S-shaped distribution, which is swept forward, then swept backward, and then swept forward again.

[0010] Furthermore, the Bézier curve has 4-6 control points and the order of the Bézier curve is 3-5.

[0011] Furthermore, the position angle of the moving blade and the inlet and outlet angles of the leading and trailing edges are controlled by spline curves, which stipulate that the moving blade is angularly distributed from the leading edge to the trailing edge according to the curve position to achieve curvature control.

[0012] Furthermore, the thickness distribution of the moving blade is controlled from the leading edge to the trailing edge in the form of a Bezier curve.

[0013] Furthermore, the diameter of the moving blade is 88-90mm, and the hub ratio is 0.41.

[0014] Furthermore, the change in the ellipticity of the leading and trailing edges of the moving blade is controlled by the ratio of the leading and trailing edges ellipticity of the boundary (hub) at the root of the moving blade and the boundary (shroud) at the tip of the meridional channel blade.

[0015] Furthermore, the moving blades are divided at equal intervals at 25% of the blade height. To improve the complex flow at the blade tip, a layer is inserted at 95% of the blade height, and a local concave treatment is performed at the trailing edge of the blade.

[0016] The tip clearance of the moving blade is relative to the radial clearance according to design requirements. It should be kept between 0.8% and 1%. Because the fan diameter is too small, the blade tip clearance will increase the noise level of the fan. Therefore, the blade tip clearance of the moving blade is 1 mm.

[0017] Furthermore, the number of moving blades is 7. For high-speed blades, an odd number of blades solves the resonance between blades caused by vibration and reduces noise; at the same time, too many fans would reduce their air volume, so it is designed to have 7.

[0018] Furthermore, the miniature axial fan has a speed of 3700 RPM; the fan rotation is determined to be in reverse according to the fan exhaust direction and the right-hand rule.

[0019] Furthermore, the bearing and buckle are designed according to the diameter of the rotating transmission shaft of the moving blade, so that they fit the diameter of the transmission shaft; the coil is perfectly matched with the outer diameter of the magnetic ring and the outer diameter of the bearing.

[0020] Compared with the prior art, one advantage of the present invention is that:

[0021] This invention relates to a novel micro-cooling axial fan design based on composite fan sweep characteristics, variable thickness, polynomial curve control of blade structure, and blade leading and trailing edge ellipticity. The main approach involves designing the fan blade structure by incorporating various blade characteristics. By determining the fan flow direction and using the right-hand rule, the forward and reverse rotation of the blades are determined to be counter-rotation.

[0022] The present invention determines the pressure and pressure side of the blade based on the rotation direction of the blade, and then sets the position angle, leading and trailing edge inlet and outlet angles, blade thickness, etc. of each airfoil layer;

[0023] 3. This invention proposes to determine the sweep degree of the moving blade by modifying the meridional curve in the meridional view. The leading edge of the moving blade exhibits an S-shaped distribution from the blade root to the blade tip, with a sweep followed by a reverse sweep and then a forward sweep. The trailing edge of the moving blade also exhibits an S-shaped distribution with a sweep followed by a reverse sweep and then a forward sweep. The airfoil shape at each of the multiple spatial airfoil sections (layers 1 to 6) is designed. Layers 1 to 5 are equally spaced at 25% of the blade height, and layer 6 is inserted at 95% of the blade height. A local concave treatment is applied at the trailing edge of the blade through angle control. The airfoil shapes of layers 1 to 5 are designed in the form of position angles (wrapping angles) and leading and trailing edge inlet and outlet angles, and the angles are represented by spline curves and Bézier curves.

[0024] 4. In terms of blade thickness control, this invention also uses the spatial airfoil section of the moving blade as a division, designs the thickness distribution of each airfoil layer separately, and represents the thickness using spline curves and Bézier curves in functional form. Simultaneously, the curvature of the blade root and tip is controlled by changing the ellipticity ratio of the moving blade hub to the shroud. Attached Figure Description

[0025] Figure 1 This is the front view of the fan assembly of the present invention.

[0026] Figure 2 This is a top view of the fan assembly of the present invention.

[0027] Figure 3 This is a partial schematic diagram A of the fan assembly of the present invention.

[0028] Figure 4 This is a partial schematic diagram (B) of the fan assembly of the present invention.

[0029] Figure 5 This is a cloud map showing the speed measurement of the yz plane of the fan performance testing pipeline according to the present invention.

[0030] Figure 6 This is a cloud diagram showing the velocity magnitude at the fan outlet cross section of the present invention.

[0031] Figure 7 This is a three-dimensional streamline diagram of the fan performance testing pipeline of the present invention.

[0032] Figure 8 This is a schematic diagram of the time-domain sound pressure of the fan in this invention.

[0033] Figure 9 This is a schematic diagram of the fan frequency domain sound pressure level of the present invention.

[0034] Figure 10 This is a meridional view of the impeller of the present invention.

[0035] Figure 11 This invention relates to the angle distribution of the impeller layer.

[0036] Figure 12 This invention relates to the thickness distribution of the impeller layer. Detailed Implementation

[0037] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0038] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0039] The present invention will now be described in detail with reference to the accompanying drawings and exemplary embodiments.

[0040] Figures 1 to 11This invention discloses a miniature axial flow fan based on multi-feature blade design, comprising a hub, several moving blades 2 disposed on the hub 1, a guide shroud 3, a housing 4, a support 5, and a magnetic ring 6; the guide shroud 3 is located on the inflow side and the outlet side of the housing 4, with the axial distance of the guide shroud 3 on the outlet side being greater than the axial distance of the guide shroud 3 on the inflow side; the support 5 is located on the outlet side of the housing 4 and is used to support the housing 4; the magnetic ring 6 is pressed into the hub 1 and is coupled to the drive shaft by a spring 7 and a double ball bearing, the drive shaft passing through a coil 9 and a PCB board 10 in sequence and then fixedly installed in the support plate groove by a buckle 8 and connected to the transmission structure; the PCB board 10 is fixed inside the support 5; the moving blades 2 are controlled by multiple spline curves and Bezier curves, and the moving blades 2 are controlled according to the parameters of each interface layer of the blade, each moving blade 2 is divided into 6 spatial sections from the hub to the blade tip, namely layer 1 to 6, and a span is introduced to determine the position of the spatial section;

[0041] The moving blade is controlled by a Bezier curve to control its sweeping degree. The moving blade has an S-shaped distribution from the leading edge tip to the root in the meridional direction, which is swept forward, then swept backward, and then swept forward again. The trailing edge of the moving blade has an S-shaped distribution, which is swept forward, then swept backward, and then swept forward again.

[0042] In one embodiment, the Bézier curve has 4-6 control points and the order of the Bézier curve is 3-5.

[0043] In one embodiment, the position angle of the moving blade and the inlet and outlet angles of the leading and trailing edges are controlled by a spline curve, which specifies that the moving blade is angularly distributed from the leading edge to the trailing edge according to the curve position to achieve curvature control.

[0044] In one embodiment, the thickness distribution of the moving blade is controlled from the leading edge to the trailing edge in the form of a Bezier curve.

[0045] In one embodiment, the moving blade has a diameter of 88-90 mm and a hub ratio of 0.41.

[0046] In one embodiment, the change in the ellipticity of the leading and trailing edges of the moving blade is controlled by the ratio of the leading and trailing edges of the boundary (hub) at the root of the meridional channel blade to the boundary (shroud) at the tip of the meridional channel blade.

[0047] In one embodiment, the moving blades are divided at equal intervals at 25% of the blade height. To improve the complex flow at the blade tip, a layer is inserted at 95% of the blade height, and a local concave treatment is performed at the trailing edge of the blade.

[0048] The tip clearance of the moving blade is relative to the radial clearance according to design requirements. It should be kept between 0.8% and 1%. Because the fan diameter is too small, the blade tip clearance will increase the noise level of the fan. Therefore, the blade tip clearance of the moving blade is 1 mm.

[0049] In one embodiment, the number of moving blades is 7. For high-speed blades, an odd number of blades solves the resonance between blades caused by vibration and reduces noise. At the same time, too many fans would reduce their air volume, so it is designed to have 7 blades.

[0050] In one embodiment, the miniature cooling axial fan is 3700 RPM; the fan rotation is determined to be in reverse according to the fan exhaust direction and the right-hand rule.

[0051] In one embodiment, the bearing and the buckle are designed to fit the diameter of the rotating drive shaft of the moving blade; the coil is perfectly matched with the outer diameter of the magnetic ring and the outer diameter of the bearing.

[0052] In this invention, the specifications of the miniature axial fan for heat dissipation are as follows:

[0053] Both the fan blades and the outer frame are made of polybutylene terephthalate (PET), a polymer material. The designed cooling fan blades have an outer diameter of 88 mm, a hub ratio of 0.41, and a blade tip clearance of 1 mm. The maximum airfoil thickness C... max The value is 1 cm. Six spatial sections are defined as layers 1 to 6, corresponding to spans of 0, 0.25, 0.5, 0.75, 0.9, and 1 respectively. The inlet and outlet angles of the impeller and hub are 63.7° and 65.1°, and 51.8° and 45° respectively. The position angles of the impeller and hub are -0.5° and 34.74°, and 0° and 44.40° respectively.

[0054] Figure 10 It is the meridional distribution of the impeller. By adjusting the projection coordinates of the leading and trailing edges of the blades, the sweep degree of the leading and trailing edges of the blades can be controlled.

[0055] Figure 11 The position angles and inlet / outlet angles of the designed blade spatial airfoil sections (layers 1-6) were designed to achieve blade camber control. (Taking layer 6 at 95% blade height as an example, the control was achieved using a 2-point spline curve, with a leading edge inlet angle of 62.2°, a trailing edge outlet angle of 60.18°, a leading edge position angle of -36.15°, and a trailing edge position angle of -2.81°).

[0056] Figure 12Design the thickness of blades for the airfoil section layers 1 to 6. (Taking layer 6 with 95% blade height as an example, the thickness is controlled by a four-point Bézier curve, with the four points from the leading edge to the trailing edge being 0.99, 1.01, 1.02, and 0.99).

[0057] The Blade Angles Table represents the continuous angular distribution of the six spatial airfoil sections from the leading edge to the trailing edge. The specific distribution is shown in the table below.

[0058] Table 1 shows the continuous angular distribution from the leading edge to the trailing edge when the span is 0-0.2500.

[0059]

[0060] Table 2 shows the continuous angular distribution from the leading edge to the trailing edge when the span is 0.2500-0.5000.

[0061]

[0062]

[0063] Table 3 shows the continuous angular distribution from the leading edge to the trailing edge when the span is 0.7500-0.9500.

[0064]

[0065]

[0066] Table 4 shows the continuous angular distribution from the leading edge to the trailing edge when the span is 0.9500-1.0000.

[0067]

[0068]

[0069] Simulation of the axial fan of this invention:

[0070] Airflow enters from the fan's suction side, with the first section of the airflow entrance featuring a trapezoidal shroud to reduce the speed gradient and lower the pitch of the intake noise. A bonded neodymium iron boron multipole magnetic ring is pressed into the fan hub. A spring and a double ball bearing are fitted onto the drive shaft, allowing it to pass through the coil and the PCB (printed circuit board). Another double ball bearing and clips secure it to the support plate groove. The PCB is fixed inside the support and stabilized by the stator.

[0071] CFD analysis software was used for simulation analysis. The axial fan, modeled according to the aforementioned dimensions, was imported into the CFD numerical simulation software for calculation. After the calculation, the mass flow rates at the outlet and inlet sections were exported, and the aerodynamic performance and noise of the fan of this size were obtained through simulation. After a period of flow field calculation, the duct flow field entered a relatively stable state, showing a velocity gradient along the fan axis, with two vortices appearing on both sides of the impeller outlet due to air recirculation. As the duct extends axially, the vortices gradually disappear, and the airflow tends to stabilize. The flow rate of this miniature axial fan is 50.07 CFM, and its noise level is relatively low at 35.91 dB.

[0072] from Figure 5 , Figure 6 and Figure 7 It is evident that the speed within the fan performance test pipe is relatively high, and the horizontal airflow distance of this miniature cooling fan is nearly half a meter, with relatively stable airflow. The airflow speed at the fan outlet can reach approximately 5 m / s. Figure 8 The time-domain sound pressure level is 1×10^-3 MPa. The frequency-domain sound pressure level after Fourier transform is as follows: Figure 9 As shown, the overall sound pressure level is 35.91 dB.

[0073] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0074] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0075] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0076] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0077] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0078] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A micro heat-dissipation axial flow fan based on multi-features design of blades, characterized in that, It includes a hub, several moving blades mounted on the hub, a shroud, a housing, a support, and a magnetic ring; the shroud is located on the inflow side and the outlet side of the housing, and the axial distance of the shroud on the outlet side is greater than the axial distance of the shroud on the inflow side. The support is located on the outlet side of the housing and is used to support the housing; the magnetic ring is pressed into the hub and is engaged with the drive shaft by a spring and a double ball bearing. The drive shaft passes through the coil and PCB board in sequence and is fixedly installed in the support plate groove by a buckle and connected to the transmission structure; the PCB board is fixed inside the support; the moving blade is controlled by multiple spline curves and Bezier curves. The moving blade is controlled according to the parameters of each interface layer of the blade. Each moving blade is divided into 6 spatial sections from the hub to the blade tip, namely layer 1 to 6. At the same time, a span is introduced to determine the position of the spatial section. The moving blade is controlled by a Bezier curve to control its sweeping degree. The moving blade has an S-shaped distribution from the leading edge tip to the root in the meridional direction, which is swept forward, then swept backward, and then swept forward again. The trailing edge of the moving blade has an S-shaped distribution, which is swept forward, then swept backward, and then swept forward again. The position angle of the moving blade and the inlet and outlet angles of the leading and trailing edges are controlled by spline curves. The moving blade is angularly distributed from the leading edge to the trailing edge according to the curve position to achieve curvature control. The thickness distribution of the moving blade is controlled by a Bezier curve from the leading edge to the trailing edge; The change in the ellipticity of the leading and trailing edges of the moving blade is controlled by the ratio of the ellipticity of the leading and trailing edges of the boundary at the root of the meridional channel blade to that at the tip of the meridional channel blade. The moving blades are divided at equal intervals at 25% of the blade height. To improve the complex flow at the blade tip, a layer is inserted at 95% of the blade height, and a local concave treatment is performed at the trailing edge of the blade. Wherein, the tip clearance of the moving blade is designed to have a relative radial clearance Should be kept at 0.8% ~ 1%, due to the fan diameter is too small, too small tip clearance will increase the noise value of the fan, so the tip clearance of the moving blade is 1mm.

2. A micro heat-dissipation axial fan based on multi-features of blade design according to claim 1, characterized in that, The Bézier curve has 4-6 control points and is of order 3-5.

3. A micro heat-dissipation axial fan based on multi-features of blade design according to claim 1, characterized in that, The diameter of the moving blade is 88-90mm, and the hub ratio is 0.

41.

4. A micro heat-dissipation axial fan based on multi-features of blade design according to any one of claims 1-3, characterized in that, The number of moving blades is 7.

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