Fan

Abstract

The utility model provides a fan, relates to life household electrical appliance technical field, the fan includes mesh enclosure and fan wheel, the mesh enclosure includes air-out submesh enclosure and air-in submesh enclosure, air-out submesh enclosure is provided on fan air-out side, air-in submesh enclosure is provided on fan air-in side, air-out submesh enclosure and air-in submesh enclosure together enclose to form the accommodation chamber, the accommodation chamber is provided with the fan wheel, the fan wheel is provided with the air-out submesh enclosure and the air-in submesh enclosure, the air-out submesh enclosure is provided with the air-out submesh enclosure and the air-in submesh enclosure. The fan wheel is arranged in the containing cavity and comprises a hub and a plurality of blades extending outwards from the periphery of the hub, an air outlet notch is formed in the position, between every two adjacent blades, of the hub, the air outlet notches are sunken from the air outlet side to the air inlet side, the hub is concavely provided with an air flow groove from the air outlet side to the air inlet side, and the air flow groove communicates with every two adjacent air outlet notches. High-pressure airflow on the windward side of the fan blade can flow around to the back side of the fan blade through the air outlet notches, concentrated impact of air pressure on a hub is reduced, noise caused by turbulent flow is lowered, and then noise generated when the fan is used is lowered.

Description

Technical Field

[0001] This utility model relates to the field of household appliance technology, and in particular to a fan. Background Technology

[0002] A fan is a traditional cooling tool. It uses electricity to drive the blades to rotate, and the rotating fan stirs the air, creating airflow to achieve a cooling effect. Fans are very practical in the hot summer. However, existing fans often have the problem of being quite noisy during use, especially when the pressure on the windward side of the blades is too high. The high-pressure airflow impacts the hub, generating significant noise. Utility Model Content

[0003] The purpose of this invention is to provide a fan that solves the problem of excessive noise in existing fans.

[0004] To achieve the above objectives, the technical solution of this utility model embodiment is as follows:

[0005] A fan, comprising:

[0006] The mesh cover includes an air outlet mesh cover and an air inlet mesh cover. The air outlet mesh cover is disposed on the side where the fan exits air, and the air inlet mesh cover is disposed on the side where the fan enters air. The air outlet mesh cover and the air inlet mesh cover together form a receiving cavity.

[0007] A fan wheel is disposed within the accommodating cavity. The fan wheel includes a hub and a plurality of blades extending outward from the outer periphery of the hub. The hub includes an air inlet side facing the air inlet sub-screen and an air outlet side facing the air outlet sub-screen.

[0008] The hub has an air outlet notch between two adjacent blades. The air outlet notch is recessed from the air outlet side to the air inlet side. The hub has an airflow groove recessed from the air outlet side to the air inlet side. The airflow groove connects two adjacent air outlet notches.

[0009] Furthermore,

[0010] The depth of the air outlet notch recessed from the air outlet side to the air inlet side is one-fifth to one-half of the axial length of the wheel hub.

[0011] Furthermore,

[0012] The blade includes an inner side facing the windward side when rotating and an outer side opposite to the inner side. The blade also includes a fixed edge connected to the hub. The air outlet notch includes two first side edges close to two adjacent blades and a first bottom edge connecting the two first side edges. The first side edge of the air outlet notch close to the inner side is moved towards the fixed edge in the direction of the adjacent inner side.

[0013] Furthermore,

[0014] The first side of the air outlet near the outer side is moved towards the fixed side in the direction of the adjacent outer side.

[0015] Furthermore,

[0016] The hub has an air intake notch on the air intake side, which is located between two adjacent blades and is recessed from the air intake side to the air outlet side.

[0017] Furthermore,

[0018] The blade includes an inner side facing the windward side when rotating and an outer side opposite to the inner side. The blade also includes a fixed edge connected to the hub. The air inlet includes two second side edges near both sides of the blade and a second bottom edge connecting the two second side edges. Each second side edge has a gap with the adjacent fixed edge and forms a blocking portion.

[0019] Furthermore,

[0020] The depth of the air intake notch recessed from the air intake side to the air outlet side is one-fifth to one-third of the axial length of the wheel hub.

[0021] Furthermore,

[0022] The end of the blade near the air intake side extends out of the air intake side end face of the hub.

[0023] Furthermore,

[0024] The length of the blade extending from the air intake side end face of the hub is one-third to three-fifths of the axial length of the hub.

[0025] Furthermore,

[0026] The blade extends obliquely relative to the end face of the hub near the air inlet side along the central axis of the fan wheel. The angle between the blade and the end face of the air inlet side is A, and the value of A ranges from 30 degrees to 50 degrees.

[0027] Compared with the prior art, the embodiments of this utility model have at least the following technical effects:

[0028] The fan of this embodiment includes a grille and a fan wheel. The grille includes an exhaust grille and an intake grille. The exhaust grille is located on the side where the fan exits air, and the intake grille is located on the side where the fan enters air. The exhaust grille and the intake grille together form a cavity. The fan wheel is disposed within the cavity. The fan wheel includes a hub and multiple blades extending outward from the outer periphery of the hub. An exhaust notch is provided between two adjacent blades on the hub. The exhaust notch is recessed from the exhaust side to the intake side. An airflow groove is recessed from the exhaust side to the intake side on the hub, and the airflow groove connects two adjacent exhaust notches. When the fan blades rotate, a pressure difference is generated between the windward side of the fan blades and the opposite side of the blades. The windward side of the blades is the high-pressure side, and the opposite side is the low-pressure side. If the airflow pressure on the windward side of the blades is too high, the concentrated air pressure will impact the hub, and the pressure difference will generate turbulence. The turbulence impacts the blades, causing noise. The high-pressure airflow on the windward side of the fan blades can be diverted to the opposite side of the fan blades through the hub with air outlets, reducing the impact of concentrated airflow on the hub, reducing the airflow pressure on the windward side of the fan blades, reducing the generation of turbulence, reducing the noise caused by turbulence, and thus reducing the noise during fan operation. Attached Figure Description

[0029] Figure 1 This is a three-dimensional schematic diagram of one embodiment;

[0030] Figure 2 This is a three-dimensional schematic diagram of another embodiment from another angle;

[0031] Figure 3 This is a cross-sectional view in one embodiment;

[0032] Figure 4 This is an exploded view of one embodiment;

[0033] Figure 5 This is a front view of the fan wheel in one embodiment;

[0034] Figure 6 This is a perspective view of the fan wheel in one embodiment;

[0035] Figure 7 This is a cross-sectional view of an embodiment where the fan blades are mixed-flow fan blades.

[0036] Explanation of icon numbers:

[0037] 10. Mesh cover; 11. Exhaust mesh cover; 110. Fixing groove; 111. Display screen; 113. Circular part; 114. Exhaust grille strip; 12. Inlet mesh cover; 120. Fixing part; 121. Inlet grille strip; 1210. Horizontal section; 1211. Bending section; 13. Receiving cavity; 14. Fan air intake space;

[0038] 20. Fan wheel; 21. Hub; 210. Air outlet notch; 2100. First side; 2101. First bottom; 211. Air inlet side; 212. Air outlet side; 213. Airflow channel; 214. Air inlet notch; 2140. Second side; 2141. Second bottom; 215. Baffle; 22. Blade; 221. Outer side; 222. Fixed side; 220. Air duct; 223. Inner side;

[0039] 30. Electric motor. Detailed Implementation

[0040] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this utility model belongs. The terminology used in this specification of this utility model is for the purpose of describing particular embodiments only and is not intended to limit the utility model. In the following description, the expression "some embodiments" refers to a subset of all possible embodiments; however, it should be understood that "some embodiments" can be the same subset or different subsets of all possible embodiments and can be combined with each other without conflict.

[0041] It should also be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "inner," "outer," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0042] like Figure 1-7 As shown, in one embodiment of this utility model, the fan includes a mesh cover 10 and a fan wheel 20. The mesh cover 10 includes an air outlet sub-mesh cover 11 and an air inlet sub-mesh cover 12. The air outlet sub-mesh cover 11 is disposed on the side where the fan exits air, and the air inlet sub-mesh cover 12 is disposed on the side where the fan enters air. The air outlet sub-mesh cover 11 and the air inlet sub-mesh cover 12 together form a receiving cavity 13. The fan wheel 20 is disposed in the receiving cavity 13. The fan wheel 20 includes a hub 21 and a plurality of blades 22 extending outward from the outer periphery of the hub 21. The hub 21 has an air outlet notch 210 between two adjacent blades 22. The air outlet notch 210 is recessed from the air outlet side 212 to the air inlet side 211. The hub 21 has an airflow groove 213 recessed from the air outlet side 212 to the air inlet side 211. The airflow groove 213 connects two adjacent air outlet notches 210. When the blades 22 are in the air outlet direction, the fan wheel 20 can open the air outlet direction. Figure 6When the fan rotates clockwise as shown, the high-pressure airflow on the windward side of the fan blade 22 can be diverted to the back side of the fan blade 22 by setting the air outlet 210. This avoids the airflow pressure on the windward side of the fan blade 22 being too high and concentrating on impacting the hub 21. At the same time, it avoids the noise caused by turbulent flow caused by uneven air pressure on both sides impacting the fan blade 22, thereby reducing the noise during fan operation.

[0043] like Figure 5 As shown, in one embodiment of this utility model, the depth of the air outlet notch 210 recessed from the air outlet side 212 to the air inlet side 211 accounts for one-fifth to one-half of the axial length of the hub 21. This can ensure the overall structural strength of the hub 21 while ensuring that the notch range can effectively reduce airflow at high pressure and reduce noise.

[0044] Furthermore, such as Figure 5-6 As shown, in one embodiment of this utility model, the blade 22 includes an inner surface 223 located on the windward side when rotating and an outer surface 221 opposite to the inner surface 223. The blade 22 also includes a fixed edge 222 connected to the hub 21. The air outlet notch 210 includes two first side edges 2100 near two adjacent blades 22 and a first bottom edge 2101 connecting the two first side edges 2100. The first side edge 2100 of the air outlet notch 210 near the inner surface 223 is moved towards the fixed edge 222 in the direction of the adjacent inner surface 223. It should be noted that the "movement" mentioned in the text refers to a part of the structure moving in another direction or adjusting its position. In this embodiment, the inner surface 223 is the windward surface of the blade 22 on the windward side, and the outer surface 221 is the surface on the blade 22 opposite to the inner surface 223. When the blade 22 rotates as... Figure 6 When rotated clockwise as shown (e.g.) Figure 6 As shown in the diagram (airflow direction illustration), one side of the inner side 223 is the high-pressure end, and one side of the outer side 221 is the low-pressure end. The high-pressure airflow of the fan blades 22 can flow around from one side of the inner side 223 to one side of the outer side 221 through the provided air outlet 210, thereby reducing the airflow pressure on the windward side of the fan blades 22, thus reducing the noise of impact on the hub 21 and reducing the noise caused by turbulence.

[0045] like Figure 6 As shown, in one embodiment of this utility model, the first side 2100 of the air outlet 210 near the outer side 221 is moved towards the fixed side 222 in the direction of the adjacent outer side 221, so as to maximize the opening range of the air outlet 210 and facilitate the flow of air at the high and low pressure ends.

[0046] like Figure 1-6As shown, in one embodiment of this utility model, the air inlet side 211 of the hub 21 is provided with an air inlet notch 214. The air inlet notch 214 is located between two adjacent blades 22, and the air inlet notch 214 is recessed from the air inlet side 211 towards the air outlet side 212. Providing an air inlet notch 214 on the air inlet side 211 of the hub 21 can improve airflow uniformity, reduce flow loss, and increase the air intake volume by expanding the effective air intake area or adjusting the airflow angle.

[0047] like Figure 1-6 As shown, in one embodiment of the present invention, the blade 22 includes an inner side 223 located on the windward side when rotating and an outer side 221 opposite to the inner side 223. The blade 22 also includes a fixed edge 222 connected to the hub 21. The air inlet notch 214 includes two second side edges 2140 near both sides of the blade 22 and a second bottom edge 2141 connecting the two second side edges 2140. Each second side edge 2140 has a gap with the adjacent fixed edge 222 and forms a blocking part 215. The blocking part 215 plays the role of blocking the airflow and preventing the airflow at the blade 22 from flowing from the high-pressure end to the low-pressure end, thereby affecting the normal operation of the blade 22. That is, the blade 22 gathers the airflow on the air inlet side 211 to the air outlet side 212.

[0048] like Figure 5 As shown, in one embodiment of this utility model, the depth of the air inlet notch 214 recessed from the air inlet side 211 to the air outlet side 212 accounts for one-fifth to one-third of the axial length of the hub 21. While ensuring the overall structural strength of the hub 21, the range of the air inlet notch 214 can effectively increase the air intake.

[0049] like Figure 5 As shown, in one embodiment of the present invention, the end of the blade 22 near the air inlet side 211 extends out of the end face of the air inlet side 211 of the hub 21, which can effectively increase the air intake volume of the blade 22.

[0050] like Figure 5 As shown, in one embodiment of this utility model, the length of the blade 22 extending from the end face of the air inlet side 211 of the hub 21 is one-third to three-fifths of the axial length of the hub 21. This setting makes it less likely for the blade 22 to wobble and generate noise, and can effectively increase the air intake volume of the blade 22 while ensuring the structural strength of the blade 22.

[0051] like Figure 1-3As shown in one embodiment of the present invention, a fan includes a mesh cover 10, a fan wheel 20, and a motor 30. The mesh cover 10 includes an exhaust mesh cover 11 and an inlet mesh cover 12. The exhaust mesh cover 11 is disposed on the side where the fan exhausts air, and the inlet mesh cover 12 is disposed on the side where the fan inlets air. The exhaust mesh cover 11 and the inlet mesh cover 12 together form a receiving cavity 13. The fan wheel 20 is disposed within the receiving cavity 13. The fan wheel 20 includes a hub 21 and a drive wheel 30. Multiple fan blades 22 extend outward from the outer periphery of the hub 21. The fan wheel 20 is driven to rotate by the motor 30. The motor 30 is installed inside the air outlet sub-screen 11. The air inlet sub-screen 12 and the fan wheel 20 are spaced apart to form a fan air inlet space 14. The air inlet space is not blocked by the motor 30, which can increase the air intake volume. The motor 30 is installed inside the air outlet sub-screen 11, which helps the heat of the motor 30 to be quickly dissipated through the air outlet sub-screen 11, reducing the risk of the motor 30 overheating.

[0052] like Figure 1-3 As shown, in one embodiment of this utility model, the air inlet sub-screen 12 includes a fixing part 120 and multiple air inlet grid strips 121 disposed on the outer periphery of the fixing part 120. The air inlet grid strips 121 extend outward from the fixing part 120, and each air inlet grid strip 121 includes a horizontal segment 1210 parallel to the fixing part 120 and a bent segment 1211 extending from the horizontal segment 1210. The air inlet grid strips 121 composed of the horizontal segment 1210 and the bent segment 1211 can effectively guide airflow to enter the fan more evenly, reduce airflow turbulence and resistance, thereby improving air intake efficiency.

[0053] like Figure 1-4 As shown, in one embodiment of this utility model, the fixing part 120 and the motor 30 are arranged facing each other along the direction of the central axis of the fan wheel 20, and the radial cross-sectional area of ​​the fixing part 120 is smaller than the radial cross-sectional area of ​​the motor 30 (it should be noted that the radial direction mentioned in the text is the direction perpendicular to the central axis of the fan wheel 20, such as...). Figure 3 or Figure 7 (The central axis of the fan wheel 20 shown). The fixing part 120 occupies less space in the air inlet sub-screen 12, which ensures that there is more space to set more air inlet grid strips 121. More grid strips can increase the ventilation area of ​​the air inlet, thereby increasing the air volume. Increasing the number of grid strips helps to guide the airflow into the fan more evenly, reduce airflow turbulence and resistance, and improve air intake efficiency.

[0054] like Figure 1-4As shown, in one embodiment of this utility model, the air inlet sub-screen 12 includes a fixing part 120 and multiple air inlet grid strips 121 disposed on the outer periphery of the fixing part 120. The air inlet grid strips 121 extend outward from the fixing part 120. The hub 21 and the fixing part 120 are arranged opposite each other along the central axis of the fan wheel 20. The radial cross-sectional area of ​​the fixing part 120 is smaller than the radial cross-sectional area of ​​the hub 21. The fixing part 120 occupies less space in the air inlet sub-screen 12, which ensures more space to set more air inlet grid strips 121. More grid strips can increase the ventilation area of ​​the air inlet, thereby increasing the air intake volume. Increasing the number of grid strips helps to guide the airflow into the fan more evenly, reduce airflow turbulence and resistance, and improve air intake efficiency.

[0055] like Figure 1-6 As shown, in one embodiment of this utility model, the fan blade 22 is an axial flow fan blade. The fan blade 22 extends obliquely along the direction of the central axis of the fan wheel 20 relative to the end face of the hub 21 near the air inlet side of the hub 21. The angle of inclination between the fan blade 22 and the end face of the hub 21 near the air inlet side of the hub 21 is A (e.g., ...). Figure 5 As shown), the value of A ranges from 30 degrees to 50 degrees. The large-angle fan blades 22 increase wind pressure, allowing the air to travel further. In other embodiments of this invention, the fan blades 22 can also be mixed-flow fan blades, with the angle of inclination between the fan blades 22 and the end face of the hub 21 being A, where A ranges from 30 degrees to 50 degrees. The large-angle fan blade design 22 increases wind pressure, allowing the air to travel further, helping to maintain a high airflow while providing sufficient wind pressure, making it suitable for applications requiring long-distance air delivery. Figure 7 As shown, in one embodiment of this utility model, the fan blade 22 is a mixed-flow fan blade, and the gap between the fan blade 22 and the mesh cover 10 forms an air duct 220. The cross-section of the air duct 220 gradually decreases from the fan inlet side to the fan outlet side. The cross-section of the air duct 220 decreases from large to small (e.g., ...). Figure 7 As shown in the diagram (showing the airflow direction), it can effectively increase wind pressure and make the wind blow further.

[0056] like Figure 1-6As shown, in one embodiment of the present invention, the hub 21 is provided with a plurality of air outlet notches 210 on the side of the fan wheel 20 where the air is discharged. Each air outlet notch 210 is located between two adjacent fan blades 22. The air outlet notch 210 is located at the end of the hub 21 near the air outlet side of the hub and is recessed from the air outlet side of the hub to the air inlet side of the hub. Of course, in other embodiments, only one air outlet notch 210 may be provided. By providing an air outlet notch 210 on the hub 21, the amount of material used can be reduced, thereby reducing the weight of the hub 21. This helps to reduce the rotational inertia of the entire fan, allowing the motor 30 to drive the fan wheel 20 more easily and improving energy efficiency. In addition, the air outlet notch 210 can reduce the turbulence or eddies generated when the airflow hits the hub 21 when the fan is blowing out. That is, the air outlet notch 210 on the hub 21 helps to reduce the turbulence and eddies of the airflow near the hub 21. The reduction of turbulence can reduce the airflow resistance, improve the aerodynamic efficiency of the fan, reduce energy loss, and also appropriately reduce the pressure on the windward side of the fan blades 22, thereby helping to reduce noise.

[0057] like Figure 1-4 As shown, in one embodiment of this utility model, a fixing groove 110 is formed in the middle of the air outlet sub-screen 11, the fixing groove 110 penetrates the air outlet sub-screen 11, and the motor 30 is installed in the fixing groove 110. The design of the fixing groove 110 allows the motor 30 to be compactly installed in the air outlet sub-screen 11, optimizing space utilization and making the fan design more compact. The fixing groove 110 is recessed inward on the housing, which can reduce the overall thickness of the fan.

[0058] like Figure 1-4 As shown, in one embodiment of this utility model, the air outlet mesh cover 11 is provided with a display screen 111. The display screen 111 is located at the opening of the fixing groove 110 on the side away from the receiving cavity (13) to cover the opening of the fixing groove 110. The display screen 111 and the motor 30 are directly opposite each other along the central axis of the fan wheel 20. The projected area of ​​the motor 30 on the display screen 111 is smaller than the screen area of ​​the display screen 111. The display screen 111 can be used to display fan information, and can also serve as a decorative cover for the opening to hide the fixing groove 110, and can also serve as a decorative cover for the motor 30 to hide the motor 30. In other embodiments, the user can choose to have the display screen 111 cover the opening of the fixing groove 110 alone, or the display screen 111 cover the motor 30 alone.

[0059] like Figure 1-4As shown, in one embodiment of this utility model, the air outlet cover 11 includes an air outlet end located on the air outlet side of the fan. The air outlet end includes a circular portion 113 located in the middle and air outlet grid strips 114 disposed around the circular portion 113. The inclination direction of the air outlet grid strips 114 relative to the central axis of the fan wheel 20 is opposite to the inclination direction of the fan blades 22. When the fan blades 22 rotate to generate airflow, the opposite inclination direction of the air outlet grid strips 114 can guide and rectify the airflow to a certain extent, making the airflow more evenly discharged from the air outlet end, reducing airflow turbulence and eddy phenomena, thereby improving the fan's air delivery efficiency and airflow uniformity, and enhancing the user experience.

[0060] The above are merely specific embodiments of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. The protection scope of this utility model shall be determined by the protection scope of the claims.

Claims

1. A fan, characterized in that, include: The mesh cover (10) includes an air outlet mesh cover (11) and an air inlet mesh cover (12). The air outlet mesh cover (11) is located on the side where the fan is venting, and the air inlet mesh cover (12) is located on the side where the fan is inlet. The air outlet mesh cover (11) and the air inlet mesh cover (12) together form a receiving cavity (13). A fan wheel (20) is disposed in the accommodating cavity (13). The fan wheel (20) includes a hub (21) and a plurality of blades (22) extending outward from the outer periphery of the hub (21). The hub (21) includes an air inlet side (211) facing the air inlet sub-screen (12) and an air outlet side (212) facing the air outlet sub-screen (11). The hub (21) has an air outlet notch (210) between two adjacent blades (22). The air outlet notch (210) is recessed from the air outlet side (212) to the air inlet side (211). The hub (21) has an airflow groove (213) recessed from the air outlet side (212) to the air inlet side (211). The airflow groove (213) connects two adjacent air outlet notches (210).

2. The fan according to claim 1, characterized in that, The depth of the air outlet notch (210) recessed from the air outlet side (212) to the air inlet side (211) is one-fifth to one-half of the axial length of the hub (21).

3. The fan according to claim 1, characterized in that, The blade (22) includes an inner side (223) located on the windward side when rotating and an outer side (221) opposite to the inner side (223). The blade (22) also includes a fixed edge (222) connected to the hub (21). The air outlet notch (210) includes two first side edges (2100) close to two adjacent blades (22) and a first bottom edge (2101) connecting the two first side edges (2100). The first side edge (2100) of the air outlet notch (210) close to the inner side (223) is moved towards the fixed edge (222) in the direction of the adjacent inner side edge (223).

4. The fan according to claim 3, characterized in that, The air outlet (210) near the first side (2100) of the outer side (221) is moved towards the fixed side (222) in the direction of the adjacent outer side (221).

5. The fan according to claim 1, characterized in that, The hub (21) has an air inlet notch (214) on the air inlet side (211). The air inlet notch (214) is located between two adjacent blades (22). The air inlet notch (214) is recessed from the air inlet side (211) toward the air outlet side (212).

6. The fan according to claim 5, characterized in that, The blade (22) includes an inner side (223) on the windward side when rotating and an outer side (221) opposite to the inner side (223). The blade (22) also includes a fixed edge (222) connected to the hub (21). The air inlet (214) includes two second side edges (2140) near both sides of the blade (22) and a second bottom edge (2141) connecting the two second side edges (2140). Each second side edge (2140) has a gap with the adjacent fixed edge (222) and forms a blocking portion (215).

7. The fan according to claim 5, characterized in that, The depth of the air inlet notch (214) recessed from the air inlet side (211) to the air outlet side (212) is one-fifth to one-third of the axial length of the hub (21).

8. The fan according to any one of claims 1 to 7, characterized in that, The blade (22) extends from the end of the hub (21) near the air intake side (211) of the air intake side (211).

9. The fan according to claim 8, characterized in that, The length of the blade (22) extending from the air intake side (211) end face of the hub (21) is one-third to three-fifths of the axial length of the hub (21).

10. The fan according to any one of claims 1 to 7, characterized in that, The blade (22) extends obliquely relative to the end face of the hub (21) near the air inlet side (211) along the direction of the central axis of the fan wheel (20). The angle between the blade (22) and the end face of the air inlet side (211) is A, and the value of A ranges from 30 degrees to 50 degrees.

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