A fan module and a handheld fan

Abstract

The utility model provides a fan module and handheld fan, fan module includes straight cylinder air duct, the impeller of setting in air duct and drive motor of driving impeller, straight cylinder air duct is divided into air inlet section, air supply section and air outlet section along its axial direction in proper order, air inlet section is defined with air inlet, air outlet section is defined with air outlet, and the impeller is set in air supply section, the fixed setting of air outlet section has the air cutting bone, and the air outlet channel is defined between two adjacent air cutting bones, the air cutting bone can be divided into the first air cutting section close to the impeller and the second air cutting section close to the air outlet along its axial direction, and the two are connected as the integral structure of one body through the smooth curved surface transition between them, the leading edge of first air cutting section is curved and formed with the arc angle in the radial plane, first air cutting section and impeller have opposite rotation direction, and the included angle between the trailing edge of second air cutting section and air duct axial direction is no more than 5. The utility model realizes high -efficient rectification through the optimization air cutting bone configuration, eliminates the rotation of airflow, converts it into the cluster jet, and promotes the air supply distance.

Description

Technical Field

[0001] This utility model belongs to the technical field, and in particular relates to a fan module and a handheld fan. Background Technology

[0002] Handheld fans are an increasingly popular type of portable personal device. Traditional miniature axial fans typically employ a simple "impeller + straight duct" structure, which inherently suffers from several drawbacks: the airflow becomes intensely turbulent after leaving the impeller; traditional designs often use a single, flat shear line without segmenting and rectifying the rotating airflow exiting the impeller; and the shear line's rotation direction is poorly matched to the impeller's, failing to effectively counteract the rotational component, resulting in some axial kinetic energy being wasted in the circular motion. The airflow rapidly disperses and attenuates at the outlet, resulting in insufficient effective air delivery distance, forcing users to hold the fan at extremely close range. Furthermore, in confined spaces, the flat trailing edge of traditional handheld fan impellers leads to significant differences in airflow characteristics between the blade root (low linear velocity) and the tip (high linear velocity), with particularly severe tip vortices and boundary layer separation. Increasing the rotation speed to achieve higher airflow actually exacerbates aerodynamic noise, and the vortices and separation further consume kinetic energy. Utility Model Content

[0003] In view of the shortcomings of the prior art, the purpose of this utility model is to provide a fan module and a handheld fan to meet the needs of users.

[0004] To achieve the above objectives, this utility model provides a fan module, including a straight air duct, an impeller disposed in the air duct, and a drive motor for driving the impeller;

[0005] The straight-tube air duct is divided into an air inlet section, an air supply section, and an air outlet section along its axial direction. The air inlet section is defined by an air inlet and is suitable for guiding the airflow to enter smoothly and reducing pre-swirl. The air outlet section is defined by an air outlet and is suitable for rectifying the accelerated turbulent airflow. The impeller is located in the air supply section, which serves as the core power zone, where the impeller accelerates the airflow.

[0006] A cutter is fixedly installed inside the air outlet section, and an air outlet channel is defined between two adjacent cutters. The cutter can be divided along its axial direction into a first cutter section near the impeller and a second cutter section near the air outlet. The first cutter section and the second cutter section are connected by a smooth curved transition to form an integral structure. The leading edge of the first cutter section is bent in the radial plane to form an arc-shaped bend. The first cutter section has the opposite rotation direction to the impeller. The angle between the trailing edge tangent of the second cutter section and the axial direction of the air duct does not exceed 5°.

[0007] Preferably, the length ratio of the first cutting section to the second cutting section in the axial direction is 1:1.5 to 1:2. The first cutting section is suitable for using the Coanda effect to turn the airflow from tangential to axial direction, while the second cutting section is suitable for stabilizing the flow field, eliminating internal turbulence, and achieving airflow homogenization. This ratio ensures that the first section has sufficient length to complete the main turning task, while the second section has more sufficient length to stabilize the flow field and homogenize the velocity distribution.

[0008] Preferably, the axial length of the air cutter is equal to the axial length of the air inlet section.

[0009] Preferably, the axial length of the air inlet section is 14mm, and the axial length of the air outlet section is 14mm.

[0010] Preferably, the minimum distance between the leading edge of the shear blade and the trailing edge of the impeller in the axial direction is 1 mm to 3 mm.

[0011] Preferably, an arc-shaped blade is formed between the suction surface and the pressure surface of the cutting edge to achieve smooth airflow diversion. The arc-shaped blade has a blade angle of 20° to 25°, which effectively induces the Coanda effect, "adsorbs" the airflow onto the surface of the cutting edge, thereby achieving efficient deflection while maintaining low flow resistance.

[0012] Preferably, the trailing edge of the impeller has a forward sweeping portion extending forward from the root of its blades and a backward sweeping portion extending backward from the tip of its blades, the forward sweeping portion and the backward sweeping portion being connected by a smooth arc.

[0013] Preferably, the forward sweep portion has a spreading distance along the impeller trailing edge that accounts for 60% to 70% of the total spreading distance of the impeller trailing edge, and the backward sweep portion has a spreading distance along the impeller trailing edge that accounts for 30% to 40% of the total spreading distance of the impeller trailing edge.

[0014] Preferably, the air cutters are arranged in a circumferentially evenly distributed manner, and the number of air cutters and the number of impellers are coprime numbers, ensuring that when the impellers rotate, the periodic pulsations generated by any impeller passing through any air cutter will not be synchronously superimposed, eliminating resonance noise, and the number of air cutters is greater than the number of impellers.

[0015] As a preferred option: the air cutter has 8 blades and the impeller has 7 blades.

[0016] A handheld fan, comprising the fan module as described above.

[0017] The beneficial effects of this utility model are:

[0018] 1. By optimizing the air-cutting rib configuration, efficient rectification is achieved, eliminating the rotation of the airflow and converting it into a concentrated jet, thereby increasing the air delivery distance. Users can enjoy a continuous and powerful cooling airflow without having to press the fan against their face. Specifically: (1) When the rotating mixed airflow impacts the arc-shaped bend of the first air-cutting section, the Coanda effect causes the airflow that was originally going to disperse to be adsorbed onto the suction surface of the air-cutting rib, forcibly guiding it to the path defined by the shape of the air-cutting rib. Moreover, the first air-cutting section rotates in the opposite direction to the impeller, which can accurately cancel the circumferential component of the rotating airflow and efficiently convert the tangential velocity component of the airflow into the axial velocity component, reducing the turbulence and rotational momentum of the airflow, and transforming it from a "vortex state" to a "jet state". (2) With the design of the trailing edge of the second air-cutting section and the axial angle ≤ 5°, a nearly parallel stable flow and guiding channel is provided, which enables the airflow to be quickly converted into a parallel axial flow, effectively reducing the initial diffusion angle caused by the radial velocity component after the airflow leaves the duct, and concentrating the airflow. (3) The first and second wind-cutting sections are smoothly transitioned by curved surfaces, which eliminates the flow separation and secondary vortices generated at the joints of the segmented structure, ensuring that the airflow energy is used to propel forward to the maximum extent, rather than being consumed in overcoming internal resistance.

[0019] II. (1) By setting a swept section at the trailing edge of the impeller to reduce the effective angle of attack of the airflow at the root, the boundary layer separation is significantly delayed, making the low-pressure area distribution in the root region more gentle and reducing the adverse pressure gradient. This allows the airflow to adhere to the blade surface for a longer time, converting the energy that would otherwise form separation vortices into effective axial thrust. (2) By setting a swept section at the trailing edge of the impeller to lengthen and weaken the generation of tip vortices, the kinetic energy consumption caused by vortices is directly reduced, and the main noise source of the handheld fan is reduced. Attached Figure Description

[0020] Figure 1 is a structural schematic diagram of a fan module provided by this utility model.

[0021] Figure 2 is a front view of a fan module provided by this utility model.

[0022] Figure 3 is a schematic diagram of the AA cross-section provided by this utility model.

[0023] Figure 4 is a front view of the straight-tube air duct and air cutter provided by this utility model.

[0024] Figure 5 is a schematic cross-sectional view of BB provided by this utility model.

[0025] Figure 6 is a schematic diagram of the impeller provided by this utility model.

[0026] In the diagram: straight duct 1, air inlet section 11, air inlet 111, air inlet filter 112, air supply section 12, air cutting section 13, air outlet 131, inner shell 132, impeller 2, blade root 211, forward sweeping part 212, blade tip 213, backward sweeping part 214, arc 215, drive motor 3, air cutting bone 4, first air cutting section 41, arc-shaped blade 411, second air cutting section 42, air outlet channel 43, suction surface 44, pressure surface 45. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0029] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0030] like Figure 1-6 As shown, a fan module includes a straight-tube air duct 1, an impeller 2 disposed within the straight-tube air duct 1, a drive motor 3 driving the impeller 2, and a cutter 4. The straight-tube air duct 1 is sequentially divided along its axial direction into an air inlet section 11, an air delivery section 12, and a cutter section 13. The air inlet section 11 is located at the front end of the air duct, with an axial length h1 of 14 mm. Its internal contour is a smooth cylindrical shape, and its main function is to guide the outside air to flow in smoothly and evenly, preparing a stable flow field for the subsequent acceleration process. The front end of the air inlet section 11 is open to form an air inlet 111, and an air filter 112 is disposed at the air inlet 111. The air delivery section 12 is disposed immediately after the air inlet section 11, and the impeller 2 is housed inside it. The cutter section 13 is located at the rear end of the air duct, and its end is open to form an air outlet 131. A cutter 4 is fixedly installed inside the cutter section 13, with an axial length h2 also of 14 mm, equal to the length of the air inlet section 11. An air outlet channel 43 is defined between two adjacent air cutters 4. An inner housing 132 suitable for installing a drive motor 3 is formed in the center of the air cutter section 13. The air cutter 4, the inner housing 132 and the air duct 1 are integrally injection molded. The root of the air cutter 4 extends to the inner housing 132 and is evenly distributed circumferentially.

[0031] In this embodiment, each cutter rib 4 can be divided along its axial direction into a first cutter section 41 located near the impeller 2 and a second cutter section 42 located near the air outlet 131. The leading edge of the first cutter section 41 is curved in the radial plane to form an arc-shaped bend. An arc-shaped blade 411 is formed between the suction surface 44 and the pressure surface 45 of the leading edge of the first cutter section 41. The arc-shaped blade 411 has a cutting edge angle α of 22°, which realizes smooth flow diversion of the airflow. Importantly, the curvature direction of the arc-shaped bend of the first cutter section 41 is opposite to the rotation direction of the impeller 2, which is used to actively counteract the rotational momentum of the airflow. The trailing edge tangent l of the second cutter section 42 is parallel to the axial direction of the straight duct 1, that is, the angle between its trailing edge tangent l and the axial direction is °. The first cutter section 41 and the second cutter section 42 are integrally formed structures, and the two are connected by a smooth curved surface transition without any steps or gaps.

[0032] In this embodiment, the ratio of the axial length of the first cutting section 41 to the axial length L4 of the second cutting section is 1:1.6. In the axial direction, the minimum distance between the leading edge of the arc-shaped cutting edge 411 of the cutting blade 4 and the trailing edge of the impeller 2 is 1.5mm.

[0033] In this embodiment, the impeller 2 is mounted on the shaft of the drive motor 3 and located within the air supply section 12. The trailing edge of the impeller 2 has a forward-swept portion 212 extending forward from its blade root 211. The forward-swept portion 212 accounts for 65% of the total trailing edge extension distance. The trailing edge 21 also has a backward-swept portion 214 extending rearward to the blade tip 213. The backward-swept portion 214 accounts for 35% of the total trailing edge extension distance. The forward-swept portion 212 and the backward-swept portion 214 are connected by a smooth arc 215 with continuous curvature to ensure that the airflow does not suddenly separate at this point.

[0034] In this embodiment, the impeller 2 has 7 blades and 8 cutting blades, which are coprime to the 7 blades of the impeller.

[0035] The working principle of this embodiment is as follows: When the drive motor 3 starts and drives the impeller 2 to rotate at high speed, air is smoothly drawn in from the air inlet 111 of the air inlet section 11. The airflow is accelerated by the impeller 2 in the air delivery section 12. Due to the unique forward and backward sweeping composite design of the trailing edge of the impeller 2, the boundary layer separation of the airflow at the blade root is effectively suppressed, and the tip vortex intensity at the blade tip is significantly weakened. The accelerated high-speed rotating airflow instantly reaches the cutting section 13. The arc-shaped cutting edge 411 of the first cutting section 41 smoothly cuts into the airflow and uses the Coanda effect to adsorb the airflow onto its suction surface 412, forcibly converting the tangential velocity component of the airflow into the axial velocity component, thereby cutting and straightening the vortex. Subsequently, the airflow enters the second cutting section 42. This section, with its near-axial flow channel, performs final smoothing and stabilization of the airflow, making its velocity distribution more uniform and further reducing the turbulence. Finally, a highly concentrated, almost non-rotating collimated airflow is ejected from the air outlet 131.

[0036] Actual measurements showed that the handheld fan in this embodiment still provided a noticeable airflow at a distance of 5cm from the air outlet, with a wind speed of 12.8m / s, while the traditional high-speed fan at the same distance only had a wind speed of 7.7m / s. Furthermore, when operating at full speed at a distance of 30cm from the air outlet, the noise level of the handheld fan in this embodiment was 73.2bB, while the traditional high-speed fan measured 72.8bB, showing negligible differences.

[0037] A handheld fan, comprising the fan module as described above.

[0038] The above embodiments are only used to illustrate the technical solutions of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the spirit and scope of the technical solutions of this utility model.

Claims

1. A fan module, characterized in that, It includes a straight-tube air duct, an impeller disposed within the air duct, and a drive motor that drives the impeller; The straight-tube air duct is divided into an air inlet section, an air supply section and an air outlet section along its axial direction. The air inlet section defines an air inlet, the air outlet section defines an air outlet, and the impeller is disposed in the air supply section. A cutter is fixedly installed inside the air outlet section, and an air outlet channel is defined between two adjacent cutters. The cutter can be divided along its axial direction into a first cutter section near the impeller and a second cutter section near the air outlet. The first cutter section and the second cutter section are connected by a smooth curved transition to form an integral structure. The leading edge of the first cutter section is bent in the radial plane to form an arc-shaped bend. The first cutter section has the opposite rotation direction to the impeller. The angle between the trailing edge tangent of the second cutter section and the axial direction of the air duct does not exceed 5°.

2. A fan module according to claim 1, characterized in that, The axial length ratio between the first and second wind-cutting sections is 1:1.5 to 1:

2.

3. A fan module according to claim 1 or 2, characterized in that, The axial length of the air cutter is equal to the axial length of the air inlet section.

4. A fan module according to claim 3, characterized in that, The axial length of the air inlet section is 14mm, and the axial length of the air outlet section is 14mm.

5. A fan module according to claim 4, characterized in that, In the axial direction, the minimum distance between the leading edge of the cutting blade and the trailing edge of the impeller is 1 mm to 3 mm.

6. A fan module according to claim 1, characterized in that, An arc-shaped cutting edge is formed between the suction surface and the pressure surface of the front edge of the cutting blade, and the arc-shaped cutting edge has a cutting edge angle of 20° to 25°.

7. A fan module according to claim 1, characterized in that, The trailing edge of the impeller has a forward sweep portion extending forward from the root of its blades and a backward sweep portion extending backward from the tip of its blades, the forward sweep portion and the backward sweep portion being connected by a smooth arc.

8. A fan module according to claim 7, characterized in that, The forward-swept portion accounts for 60% to 70% of the total forward-swept distance of the impeller trailing edge, and the backward-swept portion accounts for 30% to 40% of the total forward-swept distance of the impeller trailing edge.

9. A fan module according to claim 7, characterized in that, The air cutters are arranged in a circumferentially evenly distributed manner. The number of air cutters and the number of impellers are coprime numbers, and the number of air cutters is greater than the number of impellers.

10. A handheld fan, characterized in that, Includes the fan module as described in any one of claims 1 to 9.

Images