Centrifugal fan

Abstract

The utility model relates to a centrifugal fan which comprises a fan frame provided with an accommodating cavity and provided with an upper cover plate, a lower cover plate and a side wall; the fan wheel is rotatably arranged in the fan frame, and the fan wheel is provided with a hub and a plurality of blades which are formed by outwards diverging and extending from the outer periphery of the hub; the at least one air inlet is formed in the upper cover plate in a penetrating manner; the at least one air outlet is jointly formed by an upper cover plate, a lower cover plate and a side wall, and the accommodating cavity is communicated with the outside through the air outlet in the radial direction perpendicular to the axial direction; the edge folding part is formed by extending the position, close to the air inlet, of the upper cover plate into the containing cavity, and the lower edge of the edge folding part is the lowest position of the part, over the containing cavity, of the upper cover plate; the sunken part is formed by sinking the edge of the side, close to the upper cover plate in the axial direction, of the blade in the axial direction, the lower end edge of the edge folding part directly faces the sunken part in the axial direction, and the design scheme can improve the performance of the centrifugal fan and reduce noise.

Description

TECHNICAL FIELD

[0001] The present application relates to a centrifugal fan. BACKGROUND

[0002] With the development of science and technology, computers are updated more and more quickly, and the heat generated by computer heat sources is also more and more, so that the requirements for the centrifugal fan inside the computer are also higher and higher. For example, the centrifugal fan mainly used in the notebook computer needs to meet the design requirements of miniaturization and thinning while meeting the requirements of strong heat dissipation performance and wind driving performance.

[0003] The conventional centrifugal fan can refer to the drawings in the specification Figure 1 、 Figure 2 exhibition, generally including a fan frame formed with a receiving cavity 4, a fan wheel rotatably combined in the receiving cavity 4 of the fan frame, and a stator assembly for driving the fan wheel to rotate, etc. Among them, the top plate 1 of the fan frame is formed with an air inlet 101, and the side surface of the fan frame is formed with an air outlet 102. When the centrifugal fan is in operation, the fan wheel drives air to be sucked from the air inlet 101, and then accelerated in the receiving cavity 4 by the centrifugal action of the fan blade 2, and then blown out through the air outlet 102. Because a certain assembly gap 3 (industry is called upper GAP value) must be reserved between the upper edge of the fan blade 2 and the upper surface of the top plate 1 for preventing the fan blade 2 of the rotating fan wheel from interfering and colliding with the top plate 1. Again, when the centrifugal fan is in operation, the receiving cavity 4 has a certain static pressure value, and a part of the airflow sucked through the air inlet 101 will overflow (backflow) from the air inlet edge area to the upper edge area of the fan blade 2, that is, the lower surface position of the structure ring 21 in the drawings Figure 2 in the specification, which is not conducive to improving the air volume of the fan, and also increases the noise, thereby affecting the overall performance of the centrifugal fan. SUMMARY

[0004] The purpose of the present application is to provide a centrifugal fan for improving the performance of the centrifugal fan.

[0005] The technical scheme provided by the present application to solve its technical problems is as follows:

[0006] A centrifugal fan, comprising:

[0007] a fan frame formed with a receiving cavity and provided with an upper cover plate, a lower cover plate and a side wall;

[0008] a fan wheel rotatably arranged in the fan frame, the fan wheel being provided with a hub and a plurality of blades extending outward from the outer periphery of the hub;

[0009] at least one air inlet formed through the upper cover plate;

[0010] At least one air outlet is formed by the upper cover plate, the lower cover plate and the side wall, and the air outlet is in communication with the outside along a radial direction perpendicular to the axial direction;

[0011] A folded edge portion is formed by the upper cover plate extending into the accommodating cavity from a position close to the air inlet, and a lower edge of the folded edge portion is a lowest position of a portion of the upper cover plate directly above the accommodating cavity;

[0012] A recessed portion is formed by the vane being recessed along the axial direction from a side edge close to the upper cover plate, and a lower end edge of the folded edge portion is directly opposite the recessed portion along the axial direction.

[0013] Further, the fan further comprises:

[0014] A structural stabilizing member integrally connects a plurality of adjacent vanes, and the structural stabilizing member is located at an end of the vane away from the hub;

[0015] The structural stabilizing member is located outside the folded edge portion along the radial direction.

[0016] Further, along the axial direction, a projection of the structural stabilizing member and the folded edge portion do not overlap.

[0017] Further, the structural stabilizing member is adjacent to the recessed portion along the radial direction.

[0018] Further, a plane P1 in which a lower edge of the folded edge portion is located is not higher than a plane P2 in which an upper edge of the structural stabilizing member is located along the axial direction.

[0019] Further, the plane P1 in which the lower edge of the folded edge portion is located is not lower than a plane P3 in which a lower edge of the structural stabilizing member is located along the axial direction.

[0020] Further, the recessed portion is formed with an inner bottom surface P4, a plane in which the inner bottom surface P4 is located is perpendicular to the axial direction, and a lower end edge of the folded edge portion is directly opposite the inner bottom surface P4 along the axial direction.

[0021] Further, the structural stabilizing member comprises a main body portion directly integrally connecting a plurality of adjacent vanes along the axial direction and a first extension portion formed by the main body portion extending close to the upper cover plate at an inner position along the radial direction, and the plane P1 in which the lower edge of the folded edge portion is located is not higher than a plane P2 in which an upper edge of the first extension portion is located along the axial direction.

[0022] Further, the first extension portion is perpendicular to the main body portion.

[0023] Further, the structural stabilizing member comprises a main body portion directly integrally connecting a plurality of adjacent vanes along the axial direction and a second extension portion formed by the main body portion extending close to the lower cover plate at an inner position along the radial direction.

[0024] Further, the second extension part is inclinedly extended from the inner side of the main part in the radial direction to the side of the lower cover plate and the side close to the hub, or

[0025] The second extension part is perpendicular to the main part, or

[0026] The second extension part is curvedly extended from the inner side of the main part in the radial direction to the side of the lower cover plate.

[0027] Further, the plane P1 where the lower edge of the folding edge part is located is not lower than the plane P3 where the lower edge of the second extension part in the axial direction.

[0028] Further, the inner side surface of the second extension part constitutes at least part of the inner wall surface of the recess.

[0029] Further, the upper cover plate is formed with a clearance part above the first extension part in the axial direction;

[0030] The clearance part is formed with an upward recess on the inner side surface of the accommodation cavity, and the outer side surface of the clearance part is formed with an upward protrusion;

[0031] The folding edge part is formed by extending the inner side edge of the clearance part in the radial direction into the accommodation cavity;

[0032] In the axial direction, the upper end edge of the first extension part is opposite to the recess.

[0033] Further, the folding edge part surrounds the whole of the air inlet.

[0034] Further, the main part and / or the first extension part is in a closed ring shape.

[0035] Further, the second extension part is in a closed ring shape.

[0036] Further, the maximum outer diameter of the fan wheel is R1, and the inner diameter of the air inlet is R2, satisfying R1*80%≦R2≦R1*95%.

[0037] Further, the maximum outer diameter of the fan wheel is R1, and the inner diameter of the air inlet is R2, satisfying R1*85%≦R2≦R1*95%.

[0038] The application has the beneficial effects of improving the performance of the centrifugal fan and improving the noise. BRIEF DESCRIPTION OF DRAWINGS

[0039] The application will be further described below in combination with the drawings and embodiments.

[0040] Figure 1 is a sectional view of a prior art centrifugal fan.

[0041] Figure 2 is an enlarged view of the structure in the dashed box in Figure 1

[0042] Figure 3 is a perspective view of the centrifugal fan of the present application.

[0043] Figure 4 is an enlarged view of the structure in the dashed box in Figure 3 is a top view of the centrifugal fan in

[0044] Figure 5 is a perspective view of the centrifugal fan in Figure 3 after the upper cover plate is removed.

[0045] Figure 6 is an enlarged view of the structure in the dashed box in Figure 5

[0046] Figure 7 is a sectional view along line A-A in Figure 4

[0047] Figure 8 is an enlarged view of the structure in the dashed box in Figure 7

[0048] Figure 9 is a second embodiment of the structure shown in Figure 8

[0049] Figure 10 is a third embodiment of the structure shown in Figure 8

[0050] Figure 11 is a fourth embodiment of the structure shown in Figure 8

[0051] Figure 12 is a fifth embodiment of the structure shown in Figure 8

[0052] Figure 13 Figure 8 ​​​​​​​​​The sixth embodiment of the structure shown is specifically a sixth embodiment of a backflow suppression structure composed of a folded edge, a recessed portion, and a structural stabilizer.

[0053] Figure 14 yes Figure 8 The seventh embodiment of the structure shown is specifically a seventh embodiment of a backflow suppression structure composed of a folded edge, a recessed portion, and a structural stabilizer.

[0054] Figure 15 yes Figure 8 The eighth embodiment of the structure shown is specifically the eighth embodiment of a backflow suppression structure composed of a folded edge, a recessed portion, and a structural stabilizer. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this application clearer, the following will provide a more detailed description of this application in conjunction with the accompanying drawings and specific embodiments.

[0056] Please refer to the reference. Figures 1 to 8 The diagram shown is a schematic representation of a first embodiment of a centrifugal fan disclosed in this application. Specifically, the centrifugal fan includes a fan frame 1, a fan wheel 2 installed within the fan frame 1, and a stator assembly (not shown). The fan frame 1 forms a receiving cavity 10 and is provided with an upper cover plate 11, a lower cover plate 12, and a side wall 13. An air inlet 101 is formed through the upper cover plate 11. The upper cover plate 11, the lower cover plate 12, and the side wall 13 together form a lateral air outlet 102. The air inlet 101 connects the receiving cavity 10 to the outside along the axial direction. The air outlet 102 connects the receiving cavity 10 to the outside along a radial direction perpendicular to the axial direction. The fan wheel 2 is rotatably disposed within the fan frame 1 and located directly below the air inlet 101. The fan wheel 2 is provided with a hub 21 and a plurality of blades 22 extending outward from the outer periphery of the hub 21. An airflow channel (not shown) is formed between the fan wheel 2 and the side wall 13. A magnetic gap is formed between the stator assembly and the fan wheel 2. In use, the stator assembly is energized to generate a magnetic field and magnetically couples with the fan wheel 2, thereby driving the fan wheel 2 to rotate. After the fan wheel 2 rotates, it drives air to be drawn in through the air inlet 101 and centrifugally accelerated through the air channel formed by the interval between adjacent blades 20 before being blown out through the air outlet 102, thus realizing the function of driving air and dissipating heat.

[0057] The centrifugal fan of the present application can be used in an electronic device, including but not limited to a mobile phone, a tablet computer (PAD), a notebook computer, a personal digital assistant (PDA), a server, a switch, a computing device, a vehicle-mounted device, a wearable device, a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, a wireless terminal in industrial control, a wireless terminal in self driving, a wireless terminal in remote medical, a wireless terminal in smart grid, a wireless terminal in transportation safety, a wireless terminal in smart city, a wireless terminal in smart home, and the like.

[0058] Reference is made to Figures 3 to 8 The upper cover plate 11 extends into the accommodating cavity 10 to form a folded edge portion 111 near the air inlet 101. The vane 22 is recessed to form a recessed portion 221 near the side edge of the vane 22 close to the upper cover plate 11. The lower end of the folded edge portion 111 is axially opposite to the recessed portion 221. The lower edge of the folded edge portion 111 is the lowest part of the upper cover plate 11 above the accommodating cavity 10. Through the structure and cooperation of the folded edge portion 111 and the recessed portion 221, the problem of backflow overflow of the air flow from the air inlet 101 through the gap between the upper edge of the vane 22 and the lower surface of the upper cover plate 11 can be improved or inhibited. The backflow overflow will cause more vortex of the air flow, and the sound quality will also be reduced. Through the present application, the air intake efficiency of the air flow can be effectively improved, the air volume of the centrifugal fan can be improved, and the noise can be effectively improved.

[0059] In the premise that the vane 2 does not interfere with the upper cover plate 11 when the fan wheel 2 rotates, the lower edge of the folded edge portion 111 needs to be as much as possible downwardly protruding. In a preferred embodiment, the lower edge of the folded edge portion 111 can be downwardly protruding to be flush with or below the plane where the upper edge of the vane 2 is located to be inside the recessed portion 221.

[0060] Reference is made to Figures 5 to 8As shown, the fan wheel 2 also includes a structural stabilizer 3, which integrally connects several adjacent blades 22. Preferably, the structural stabilizer 3 is located at the end of the blade 22 away from the hub 21. Preferably, the structural stabilizer 3 is located radially outside the folded edge 111. Preferably, the projections of the structural stabilizer 3 and the folded edge 111 do not overlap axially. Preferably, the structural stabilizer 3 and the recess 221 are arranged radially adjacent to each other. Preferably, the plane P1 containing the lower edge of the folded edge 111 is not higher than the plane P2 containing the upper edge of the structural stabilizer 3 axially. Preferably, the plane P1 containing the lower edge of the folded edge 111 is not lower than the plane P3 containing the lower edge of the structural stabilizer 3 axially. This optimizes the cooperation between the folded edge 111 and the recess 221 to improve or suppress the backflow of airflow from the air inlet 101 through the gap formed between the upper edge of the blade 22 and the lower surface of the upper cover plate 11.

[0061] In this embodiment, the recessed portion 221 has a cross-section that is upwardly opening and gradually widening into a polygon, and the inner end face of the structural stabilizer 3 constitutes part of the inner wall surface of the recessed portion 221. Preferably, the recessed portion 221 has an inner bottom surface P4, the plane containing the inner bottom surface P4 is perpendicular to the axial direction, and the lower edge of the folded edge portion 111 is directly opposite the inner bottom surface P4 along the axial direction. In this embodiment, the folded edge portion 111 is perpendicular to the structural stabilizer 3. Preferably, in this embodiment, the folded edge portion 111 surrounds the air inlet (101) for a full circumference, and the structural stabilizer 3 forms a closed ring.

[0062] Please refer to Figure 9 The second embodiment shown, the second embodiment and Figure 8 The only difference between the first embodiment shown is the cross-sectional shape of the recess 221. In the second embodiment, the cross-sectional shape of the recess 221 is approximately U-shaped with the opening facing upwards.

[0063] Please refer to Figure 10 The third embodiment shown is similar to... Figure 8 The only difference between the first embodiment and the third embodiment is the structure of the structural stabilizer 3. In the third embodiment, the structural stabilizer 3 includes a main body 31 and a second extension 33 formed by the main body 31 extending radially inward toward the lower cover plate 12. The main body 31 in the third embodiment has the same structure as the structural stabilizer 3 in the first embodiment. The second extension 33 extends obliquely from the main body 31 radially inward toward the lower cover plate 12 and toward the hub 21. Preferably, the plane P1 containing the lower edge of the folded edge 111 is not lower than the plane P3 containing the lower edge of the second extension (33) in the axial direction.

[0064] Please refer toFigure 11 The fourth embodiment shown is related to... Figure 9 The only difference in the second embodiment shown is the structure of the structural stabilizer 3. In the fourth embodiment, the structural stabilizer 3 includes a main body 31 and a second extension 33 formed by the main body 31 extending radially inward toward the lower cover plate 12. The main body 31 in the fourth embodiment has the same structure as the structural stabilizer 3 in the second embodiment. The second extension 33 is perpendicular to the main body 31. Preferably, the plane P1 containing the lower edge of the folded edge 111 is not lower than the plane P3 containing the lower edge of the second extension 33 along the axial direction.

[0065] Please refer to Figure 12 The fifth embodiment shown, the fifth embodiment and Figure 8 The difference between the first embodiment and the fifth embodiment lies in the structure of the structural stabilizer 3 and the folded edge portion 111. In the fifth embodiment, the structural stabilizer 3 includes a main body portion 31 and a first extension portion 32 formed by the main body portion 31 extending radially inward toward the upper cover plate 11. The main body portion 31 in the fifth embodiment has the same structure as the structural stabilizer 3 in the first embodiment. Preferably, the plane P1 containing the lower edge of the folded edge portion 111 is not higher than the plane P2 containing the upper edge of the first extension portion 32 along the axial direction. Preferably, the first extension portion 32 is perpendicular to the main body portion 31. The upper cover plate 11 forms a clearance portion 110 axially above the first extension portion 32. The clearance portion 110 forms an upwardly recessed portion 1101 on the inner surface of the receiving cavity 10, and an upwardly protruding portion 1102 on the outer surface of the clearance portion 110. The folded edge portion 111 is formed by the clearance portion 110 extending radially inward toward the receiving cavity 10. Preferably, along the axial direction, the upper edge of the first extension 32 is directly opposite the recess 1101.

[0066] Please refer to Figure 13 The sixth embodiment shown is actually... Figure 12 The sixth embodiment, a variation of the fifth embodiment, differs from the fifth embodiment in that the cross-sectional shape of the recess 221 is different. In the sixth embodiment, the cross-sectional shape of the recess 221 is approximately U-shaped with the opening facing upwards (same as the second embodiment). Furthermore, another difference between the sixth and fifth embodiments is that the plane P1 containing the lower edge of the folded edge 111 is flush with the plane P3 containing the lower edge of the second extension 33.

[0067] Please refer to Figure 14 The seventh embodiment shown is actually... Figure 12Another variant of the fifth embodiment, the seventh embodiment is only different from the fifth embodiment in that the structural stabilizer 3 further comprises a second extension 33 extending from the inner side of the radial position of the main body 31 to the lower cover plate 12. Figure 10 The second extension 33 of the third embodiment is the same as that of the second embodiment.

[0068] Please refer to Figure 15 The eighth embodiment is actually a variant of the seventh embodiment, and the eighth embodiment is different from the seventh embodiment in that the second extension 33 extends vertically downward from the main body 31. Figure 14 The second extension 33 of the eighth embodiment is the same as that of the fourth embodiment. Figure 11 Another difference between the eighth embodiment and the seventh embodiment is that the cross-sectional shape of the recessed portion 221 is substantially U-shaped with the opening facing upward (the same as the second embodiment).

[0069] In the present application, the second extension 33 is added in embodiments three, four, seven, and eight, which can improve or inhibit the problem of backflow overflow of air flow from the air inlet 101 along the lower surface of the main body 31 of the structural stabilizer 3 of the blade 22, further improve the air intake efficiency of the air flow, increase the air volume of the centrifugal fan, and improve the noise. Of course, in other embodiments, the second extension 33 can also be designed to extend from the inner side of the radial position of the main body 31 to one side of the lower cover plate 12. Preferably, the axial height of the second extension 33 protruding from the inner side of the radial position to one side of the lower cover plate 11 is not less than 0.3 mm and not more than 1.5 mm. Preferably, the inner surface 330 of the second extension 33 constitutes at least part of the inner wall surface of the recessed portion 221. Preferably, the plane P3 where the lower edge of the second extension 33 is located is flush with the inner bottom surface P4 of the recessed portion 221.

[0070] In the present application, the accommodation portion 110 is added in embodiments five, six, seven, and eight to cooperate with the first extension 32 structure, which is also to improve or inhibit the problem of backflow overflow of air flow from the air inlet 101 through the gap between the upper edge of the blade 22 and the lower surface of the upper cover plate 11, further improve the air intake efficiency of the air flow, increase the air volume of the centrifugal fan, and improve the noise. At the same time, the accommodation portion 110 and the folded edge portion 111 structure can greatly strengthen the structural strength of the upper cover plate 11. Similarly, the first extension 32 and the second extension 33 can strengthen the overall structural strength of the fan wheel 2, reduce the shaking between the adjacent two blades, and be beneficial to improve the noise problem.

[0071] In addition, preferably, the folded edge portion 111, the accommodation portion 110, the main body 31, the first extension 32, and the second extension 33 in each embodiment of the present application are all closed annular.

[0072] Please refer to Figure 4 As shown in the figure, the outer diameter of the fan wheel 2 is defined as R1, and the inner diameter of the air inlet is defined as R2. In the case where the overall size of the centrifugal fan is limited (including: the size of the internal flow channel, the size of the fan wheel 2, etc.), R2 is taken as a single variable. In principle, the larger R2 is, the larger the air inlet volume is, which is conducive to improving the overall air outlet volume of the centrifugal fan. However, when R2 exceeds a certain design value, the backflow overflow phenomenon described in the background art will be more obvious, which is not conducive to improving the overall air outlet volume of the centrifugal fan. Therefore, in order to ensure that the centrifugal fan has a relatively balanced performance, the general design value in the prior art is R2 = 80% * R1. When R2 is greater than 80% * R1, the overall air outlet volume of the centrifugal fan will be affected due to the increase in backflow overflow. When R2 is less than 80% * R1, the overall air outlet volume of the centrifugal fan will be affected due to the decrease in air inlet volume. Through the innovative design improvement of the present application, the design ratio of R1 and R2 can be improved to R1 * 80% ≦ R2 ≦ R1 * 95%, and the overall air outlet volume of the centrifugal fan is also significantly improved compared to the traditional scheme in the prior art (R2 = 80% * R1 scheme), and the noise control is also better than the traditional scheme in the prior art. In addition, the more optimal design range in the present application is R1 * 85% ≦ R2 ≦ R1 * 95%.

[0073] Further explanation, in the embodiments of the drawings, the recess 221 illustrates two shapes, which are respectively a polygon with a cross-section opening upward and gradually expanding in width, or a generally U-shaped structure opening upward. For example, Figure 8 、 Figure 10 、 Figure 12 、 Figure 14 For example, the recess 221 is shown as a pentagonal structure with a cross-section opening upward (one side opening). Of course, this is not a limitation, and the recess 221 can also be designed as a V-shaped, semicircular, etc. to achieve similar effects.

[0074] In the present application, the air inlet 101 can also be formed on the lower cover plate 12; of course, the corresponding folding edge portion 111 and the accommodation portion 110 can also be provided on the lower cover plate 12; correspondingly, the structure stabilizing piece 3 and the recess (221) can also be provided at the lower edge position of the fan blade 2.

[0075] In the description of the present application, it needs to be understood that the terms "width", "height", "upper", "lower", "front", "back", "horizontal", "inner", "outer", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated.

[0076] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application.

[0077] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description manner of the specification is only for the sake of clarity, those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be properly combined to form other implementation manners that those skilled in the art can understand.

Claims

1. A centrifugal fan characterized by comprising: The centrifugal fan comprises: a fan frame (1) formed with a containing cavity (10) and provided with an upper cover plate (11), a lower cover plate (12) and side walls (13); a fan wheel (2) rotatably arranged in the fan frame (1), the fan wheel (2) being provided with a hub (21) and a plurality of blades (22) extending outward from the outer periphery of the hub (21); at least one air inlet (101) formed through the upper cover plate (11); at least one air outlet (102) formed by the upper cover plate (11), the lower cover plate (12) and the side walls (13), the air outlet (102) being in communication with the outside along a radial direction perpendicular to an axial direction; a folded edge portion (111) formed by the upper cover plate (11) extending into the containing cavity (10) from a position close to the air inlet (101), a lower edge of the folded edge portion (111) being a lowest position of a portion of the upper cover plate (11) directly above the containing cavity (10); a recessed portion (221) formed by the blade (22) recessed along an axial direction from a side edge close to the upper cover plate (11), a lower end edge of the folded edge portion (111) being directly opposite the recessed portion (221) along the axial direction.

2. The centrifugal fan according to claim 1, characterized in that Further comprising: a structure stabilizing member (3) integrally connecting a plurality of adjacent blades (22), the structure stabilizing member (3) being located at an end of the blade (22) away from the hub (21); the structure stabilizing member (3) being located radially outside the folded edge portion (111).

3. The centrifugal fan according to claim 2, characterized in that Along the axial direction, projections of the structure stabilizing member (3) and the folded edge portion (111) do not overlap.

4. The centrifugal fan of claim 2, wherein: The structure stabilizing member (3) is radially adjacent to the recessed portion (221).

5. The centrifugal fan according to claim 2 or 3 or 4, characterized in that: A plane P1 in which a lower edge of the folded edge portion (111) is located is not higher than a plane P2 in which an upper edge of the structure stabilizing member (3) is located along the axial direction.

6. The centrifugal fan according to claim 2 or 3 or 4, characterized in that: The plane P1 in which the lower edge of the folded edge portion (111) is located is not lower than a plane P3 in which a lower edge of the structure stabilizing member (3) is located along the axial direction.

7. The centrifugal fan according to claim 1 or 2 or 3 or 4, characterized in that: The recessed portion (221) is formed with an inner bottom surface P4, a plane in which the inner bottom surface P4 is located being perpendicular to the axial direction, and a lower end edge of the folded edge portion (111) being directly opposite the inner bottom surface P4 along the axial direction.

8. The centrifugal fan according to claim 2 or 3 or 4, characterized by: The structure stabilizing member (3) comprises a main body portion (31) integrally connecting a plurality of adjacent blades (22) directly along the axial direction and a first extension portion (32) formed by the main body portion (31) extending close to the upper cover plate (11) at an inner position in the radial direction, a plane P1 in which a lower edge of the folded edge portion (111) is located being not higher than a plane P2 in which an upper edge of the first extension portion (32) is located along the axial direction.

9. The centrifugal fan of claim 8, wherein: The first extension portion (32) is perpendicular to the main body portion (31).

10. The centrifugal fan according to claim 2 or 3 or 4, characterized in that: The structure stabilizing member (3) comprises a main body portion (31) integrally connecting a plurality of adjacent blades (22) directly along the axial direction and a second extension portion (33) formed by the main body portion (31) extending close to the lower cover plate (12) at an inner position in the radial direction.

11. The centrifugal fan according to claim 10, characterized in that: The second extension part (33) is inclinedly extended from the inner side in the radial direction of the main body part (31) to the side of the lower cover plate (12) and the side close to the hub (21), or The second extension part (33) is perpendicular to the main body part (31), or The second extension part (33) is curvedly extended from the inner side in the radial direction of the main body part (31) to the side of the lower cover plate (12).

12. The centrifugal fan of claim 10, wherein: The plane P1 where the lower edge of the folded edge part (111) is located is not lower than the plane P3 where the lower edge of the second extension part (33) is located in the axial direction.

13. The centrifugal fan of claim 10, wherein: The inner side surface (330) of the second extension part (33) in the radial direction constitutes at least a part of the inner wall surface of the recess part (221).

14. The centrifugal fan according to claim 8, characterized in that: The upper cover plate (11) is formed with a clearance part (110) above the first extension part (32) in the axial direction; The clearance part (110) is formed with an upward recess part (1101) on the inner side surface of the accommodation cavity (10), and the outer side surface of the clearance part (110) is formed with an upward convex part (1102); The folded edge part (111) is formed by extending from the inner side edge of the clearance part (110) to the inside of the accommodation cavity (10); In the axial direction, the upper end edge of the first extension part (32) is opposite to the recess part (1101).

15. The centrifugal fan according to claim 1 or 2 or 3 or 4, characterized in that: The folded edge part (111) surrounds the whole circumference of the air inlet (101).

16. The centrifugal fan of claim 8, wherein: The main body part (31) and / or the first extension part (32) is in a closed ring shape.

17. The centrifugal fan of claim 10, wherein: The second extension part (33) is in a closed ring shape.

18. The centrifugal fan according to claim 1 or 2 or 3 or 4, characterized by: The maximum outer diameter of the fan wheel (2) is R1, and the inner diameter of the air inlet is R2, and R1*80%≦R2≦R1*95% is satisfied.

19. The centrifugal fan according to claim 1 or 2 or 3 or 4, characterized by: The maximum outer diameter of the fan wheel (2) is R1, and the inner diameter of the air inlet is R2, and R1*85%≦R2≦R1*95% is satisfied.

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