Centrifugal two-way air outlet fan

Abstract

The utility model discloses a centrifugal two-way air outlet fan which comprises a fan frame and a fan cover, a hollow mounting cavity is formed in the fan frame, and the fan frame comprises a bottom plate, side plates extending upwards from the periphery of the bottom plate and a top plate covering the upper edges of the side plates and opposite to the bottom plate in a spaced mode; the fan wheel assembly is rotationally combined in the mounting cavity; the air inlet penetrates through the top plate in the vertical direction; the first air outlet is formed in the position of the side plate between the bottom plate and the top plate; the inner flow channel is formed between the outer periphery of the fan wheel assembly and the inner wall surface of the side plate; the fan frame is further provided with a branch flow channel, the branch flow channel comprises a direct flow section and a flow guide section which are communicated with each other, the direct flow section extends in the radial direction of the fan wheel assembly and is communicated with the branch flow area, the flow guide section further extends downwards from one end of the direct flow section, and a second air outlet with a downward opening is formed in the lower end of the flow guide section. According to the centrifugal bidirectional air outlet fan, double air outlets can be formed, airflow loss is small, and the overall air driving efficiency of the fan wheel assembly is improved.

Description

Technical Field

[0001] This application relates to a centrifugal two-way air outlet fan. Background Art

[0002] In the era of rapid development of electronic technology, more and more electronic products need to be cooled by a cooling fan to ensure their normal operation or extend their service life. Traditional cooling fans generally include a stator, a rotor, and a fan frame for installing the stator and the rotor. Usually, the stator includes a coil and a PCB assembly, and the rotor includes an impeller, a magnetic ring, etc.

[0003] Existing cooling fans generally have only one air outlet and cannot cool two heat sources simultaneously. At the same time, for an existing cooling fan with one air outlet, the air flow driven by the fan cannot actually be completely discharged, and there is a certain degree of air flow loss, resulting in low efficiency. Installing two cooling fans has a high cost and occupies a large space, further occupying the already limited space inside the electronic device, and also requires a new design layout.

[0004] Therefore, it is necessary to design a new cooling fan to solve the above technical problems. Utility Model Content

[0005] The purpose of this application is to provide a centrifugal two-way air outlet fan, which can form a double air outlet, with less air flow loss, and improve the air driving efficiency of the impeller assembly.

[0006] To achieve the above purpose, this application provides the following technical solutions:

[0007] A centrifugal two-way air outlet fan, characterized by comprising:

[0008] A fan frame, which forms a hollow installation cavity. The fan frame includes a bottom plate, side plates extending upward from the four sides of the bottom plate, and a top plate covering the upper edges of the side plates and spaced apart from the bottom plate;

[0009] An impeller assembly, rotatably coupled in the installation cavity;

[0010] An air inlet, formed through the top plate in the vertical direction and located directly above the impeller assembly. The air inlet communicates the installation cavity with the outside in the axial direction of the impeller assembly;

[0011] A first air outlet, formed at the position of the side plate between the bottom plate and the top plate. The first air outlet communicates the installation cavity with the outside in the radial direction of the impeller assembly;

[0012] An inner flow passage, formed between the outer periphery of the impeller assembly and the inner wall surface of the side plate;

[0013] The tongue and orifice part is formed on the side plate and is located on one side of the first air outlet. The width of the inner flow path in the radial direction of the fan wheel assembly gradually increases from the position of the tongue and orifice part along the rotation direction of the fan wheel assembly;

[0014] The inner flow path sequentially includes a pressurization area, a flow splitting area, and a pressure relief area from the position of the tongue and orifice part along the rotation direction of the fan wheel assembly;

[0015] The fan frame is further formed with a flow splitting channel, which includes a direct current section and a diversion section that are connected to each other. The direct current section extends in the radial direction of the fan wheel assembly and is connected to the flow splitting area. The diversion section further extends downward from one end of the direct current section, and a second air outlet with a downward opening is formed at the lower end position of the diversion section.

[0016] Further, the straight line where the edge of the first air outlet is located is defined as the horizontal line A0;

[0017] The straight line passing through the axis of the fan wheel assembly and perpendicular to the horizontal line A0 is defined as the first dividing line A1;

[0018] The straight line passing through the axis of the fan wheel assembly and parallel to the horizontal line A0 is defined as the second dividing line A2;

[0019] The flow splitting area of the inner flow path is located between the first dividing line A1 and the second dividing line A2.

[0020] Further, the diversion section extends in the axial direction of the fan wheel assembly, and the second air outlet opens downward along the axial direction of the fan wheel assembly.

[0021] Further, the direct current section includes an inner bottom surface, an inner top surface, and a first inner side surface;

[0022] The inner bottom surface is flush with the upper surface of the bottom plate;

[0023] The inner top surface is flush with the lower surface of the top plate.

[0024] Further, the first inner side surface is a planar shape perpendicular to the upper surface of the bottom plate.

[0025] Further, the first dividing line A1 and the inner wall surface of the side plate forming the inner flow path form an intersection point B;

[0026] The straight line passing through the intersection point B and parallel to the horizontal line A0 is defined as the set line B0;

[0027] The first inner side surface is perpendicular to the upper surface of the bottom plate;

[0028] An included angle β is formed between the first inner side surface and the set line B0, and the included angle β is greater than 0 degrees and not greater than 10 degrees.

[0029] Further, the intersection point B falls on the first inner side surface.

[0030] Further, the first inner side surface is formed by extending with a straight line passing through the intersection point B and perpendicular to the upper surface of the bottom plate as the starting edge.

[0031] Further, the set line B0 is the tangent line of the pressurized area of the inner flow path at the intersection point B.

[0032] Further, the direct current section further includes a second inner side surface, the second inner side surface is closer to the horizontal line A0 than the first inner side surface, and on the extension surface of the inner bottom surface, the extension length of the first inner side surface is greater than the extension length of the second inner side surface.

[0033] Further, the second inner side surface is parallel to the horizontal line A0.

[0034] Further, an intersection part C is formed between the second inner side surface and the inner wall surface of the inner flow path;

[0035] The flow path width L2 of the shunt flow path at the intersection part C is greater than the flow path width L1 of the inner flow path at the intersection point B;

[0036] The flow path width L2 of the shunt flow path at the intersection part C is less than the flow path width L3 of the inner flow path at the intersection part C.

[0037] Further, the guiding section is formed by extending axially downward along the fan wheel assembly, and the guiding section forms a front-end inner side surface, a rear-end inner side surface, a first mating inner side surface and a second mating inner side surface;

[0038] The first mating inner side surface and the first inner side surface are coplanar;

[0039] The second mating inner side surface and the second inner side surface are coplanar;

[0040] The front-end inner side surface is perpendicular to the inner top surface and is connected through an arc surface in a transitional manner, and the arc surface is formed by the extension of the side plate;

[0041] The rear-end inner side surface is connected to the inner bottom surface.

[0042] Further, the respective extension planes of the front-end inner side surface, the rear-end inner side surface, the first mating inner side surface and the second mating inner side surface are all perpendicular to the plane where the upper surface of the bottom plate is located.

[0043] Further, the part of the side plate extending to form the arc surface and the projection of the rear-end inner side surface along the axial direction of the fan wheel assembly do not overlap.

[0044] Compared with the prior art, the beneficial effects of the present application are: it can form a double air outlet, and the air flow loss is small, improving the overall air driving efficiency of the fan wheel assembly. Brief Description of the Drawings

[0045] Figure 1 is a three-dimensional schematic diagram of the centrifugal two-way air outlet fan of the present application.

[0046] Figure 2 is a top view of the centrifugal two-way air outlet fan of the present application.

[0047] Figure 3 is a partial three-dimensional exploded view of the centrifugal two-way air outlet fan of the present application, specifically showing a three-dimensional schematic diagram after the top plate is separated.

[0048] Figure 4 is a top view of the centrifugal two-way air outlet fan of the present application after removing the top plate.

[0049] Figure 5 is from Figure 2 a cross-sectional view taken along line A-A.

[0050] Figure 6 is Figure 5 an enlarged view of the structure within the dashed box.

[0051] Figure 7 is Figure 6 another embodiment of the structure, with the main structural difference being the combination position of the top plate and the side plate forming an arc surface.

[0052] Figure 8 is a bottom view of the centrifugal two-way air outlet fan of the present application.

[0053] Figure 9 is Figure 8 an enlarged view of the structure within the dashed box. Detailed Description of the Preferred Embodiments

[0054] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application.

[0055] In the description of the present application, it should be understood that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0056] Please refer to Figures 1 to 9As shown, a centrifugal two-way air outlet fan disclosed in the present application includes a fan frame 1, a stator assembly (not shown), and a fan wheel assembly 2. The fan frame 1 forms a hollow installation cavity 10. The fan frame 1 includes a bottom plate 11, side plates 12 extending upward from the periphery of the bottom plate 11, and a top plate 13 covering the upper edges of the side plates 12. The stator assembly is fixedly arranged in the installation cavity 10. The fan wheel assembly 2 is rotatably coupled in the installation cavity 10. The fan wheel assembly 2 can generate electromagnetic coupling with the stator assembly. After the stator assembly is powered on, the rotation of the fan wheel assembly 2 can be realized through the stator assembly. The centrifugal two-way air outlet fan of the present application can be used to be installed inside an electronic device for dissipating heat from the heat-generating components inside the electronic device.

[0057] Specifically, an air inlet 101 is formed through the top plate 13 along the axial direction of the fan wheel assembly 2, and the air inlet 101 is located directly above the fan wheel assembly 2. The air inlet 101 communicates the installation cavity 10 with the outside along the axial direction of the fan wheel assembly 2. A first air outlet 102 is formed at the position of the side plate 12 between the bottom plate 11 and the top plate 13, and the first air outlet 102 communicates the installation cavity 10 with the outside along the radial direction of the fan wheel assembly 2. An inner flow channel 3 for air flow is formed between the outer peripheral edge of the fan wheel assembly 2 and the inner wall surface of the side plate 12. A tongue portion 121 is formed on the side plate 12 on one side of the first air outlet 102, and the width of the inner flow channel 3 along the radial direction of the fan wheel assembly 2 gradually increases from the position of the tongue portion 121 along the rotation direction of the fan wheel assembly 2.

[0058] Please refer to Figure 4 and in combination with Figure 3 As shown, the inner flow channel 3 sequentially includes a pressurization zone 31, a diversion zone 32, and a pressure relief zone 33 from the position of the tongue portion 121 along the rotation direction of the fan wheel assembly 2. The fan frame 1 further forms a diversion channel 4. The diversion channel 4 includes a direct current section 41 and a diversion section 42 that are connected to each other. The direct current section 41 extends along the transverse direction perpendicular to the radial direction of the fan wheel assembly 2 and is connected to the diversion zone 32 of the inner flow channel 3. The diversion section 42 is further extended downward from one end of the direct current section 41, and a second air outlet 103 with a downward opening is formed at the lower end position of the diversion section 42. In one implementation, the second air outlet 103 opens downward along the axial direction of the fan wheel assembly 2, and the air flow blown out through the second air outlet 103 flows downward along the axial direction of the fan wheel assembly 2.

[0059] When the centrifugal two-way air outlet fan of the present application is in use, after the stator assembly is powered on, it generates electromagnetic coupling with the impeller assembly 2, thereby driving the impeller assembly 2 to rotate, and then driving the air flow to be inhaled from the air inlet 101 and blown out through the first air outlet 102 and the second air outlet 103 after being pressurized and accelerated through the inner flow path 3 to achieve the effect of two-way air outlet. In the present application, the air flow directions blown out through the first air outlet 102 and the second air outlet 103 are perpendicular to each other.

[0060] In the embodiment of the present application, in order to reduce the kinetic energy attenuation of the air flow inhaled from the air inlet 101 and driven by the impeller assembly 2, improve the air driving efficiency of the impeller assembly 2, and maximize the energy conversion of the rotation of the impeller assembly 2, the shape and position of the flow dividing channel 4 are specially designed, and specific reference is made to the following description.

[0061] Please refer to Figure 4 As shown, when looking down at the centrifugal two-way air outlet fan, the straight line where the edge of the first air outlet 102 is located is defined as the horizontal line A0. The straight line passing through the axis of the impeller assembly 2 and perpendicular to the horizontal line A0 is defined as the first dividing line A1. The straight line passing through the axis of the impeller assembly 2 and parallel to the horizontal line A0 is defined as the second dividing line A2. The flow dividing area 32 of the inner flow path 3 is located between the first dividing line A1 and the second dividing line A2. That is to say, the straight flow section 41 of the flow dividing channel 4 communicates with the flow dividing area 32 located between the first dividing line A1 and the second dividing line A2.

[0062] In a preferred embodiment, the straight flow section 41 is defined by an inner bottom surface 401, an inner top surface 402, a first inner side surface 403 and a second inner side surface 404. The inner bottom surface 401 is flush with the upper surface of the bottom plate 11. The inner top surface 402 is flush with the lower surface of the top plate 13. The second inner side surface 404 is closer to the horizontal line A0 than the first inner side surface 403. Along the extension surface of the inner bottom surface 401, the extension length of the first inner side surface 403 is greater than the extension length of the second inner side surface 404. Preferably, the first inner side surface 403 is a planar shape perpendicular to the upper surface of the bottom plate 11. The second inner side surface 404 is a planar shape perpendicular to the upper surface of the bottom plate 11. In a preferred embodiment, the second inner side surface 404 is parallel to the horizontal line A0.

[0063] Further, in a preferred embodiment, the first dividing line A1 intersects with the inner wall surface of the side plate 12 forming the inner flow channel 3 to form an intersection point B. A straight line passing through the intersection point B and parallel to the horizontal line A0 is defined as the set line B0. An included angle β is formed between the first inner side surface 403 and the set line B0, and the included angle β is preferably greater than 0 degree and not greater than 10 degrees. In a more preferred embodiment, the included angle β is preferably greater than 0 degree and not greater than 5 degrees. Such a design makes the flow channel width of the straight flow section 41 where the second inner side surface 404 is located gradually narrow along the flow direction of the air flow, so as to achieve the purpose of secondary pressurization of the air flow flowing into the straight flow section 41 after being shunted. In a preferred embodiment, the intersection point B falls on the first inner side surface 403. In a more preferred embodiment, the first inner side surface 403 is formed by extending with a straight line passing through the intersection point B and perpendicular to the upper surface of the bottom plate 11 as the starting edge (or understood as: the first inner side surface 403 extends with the position where the intersection point B is located as the starting point). In a preferred embodiment, the set line B0 is the tangent line of the pressurization area 31 of the inner flow channel 3 at the intersection point B. Such a design can reduce the kinetic energy loss of the air flow flowing into the straight flow section 41, so that when the air flow flows in the inner flow channel 3, it passes through the pressurization area 31, the shunt area 32, and the pressure relief area 33, and at the same time, the process of part of the air flow in the shunt area 32 flowing into the straight flow section 41 is smoother. The occurrence of the adverse situation of additional loss of air flow kinetic energy caused by poor flow channel design (referring to the inner flow channel 3 and the straight flow section 41) is reduced.

[0064] Please refer to Figure 4 As shown, an intersection part C is formed between the second inner side surface 404 and the inner wall surface of the inner flow channel 3. Preferably, the flow channel width L2 of the shunt channel 4 at the intersection part C is greater than the flow channel width L1 of the inner flow channel 3 at the intersection point B. The flow channel width L2 of the shunt channel 4 at the intersection part C is less than the flow channel width L3 of the inner flow channel 3 at the intersection part C.

[0065] Please refer to in combination Figures 4 to 9As shown, the diversion section 42 is formed by extending downward along the axial direction of the fan wheel assembly 2. The diversion section 42 is formed with a front inner side surface 421, a rear inner side surface 422, a first mating inner side surface 423, and a second mating inner side surface 424. The first mating inner side surface 423 is coplanar with the first inner side surface 403. The second mating inner side surface 424 is coplanar with the second inner side surface 404. The front inner side surface 421 is perpendicular to the inner top surface 402 and is connected by an arc surface 420 in a transitional manner. Specifically, in the present application, the bottom plate 11 and the top plate 13 are preferably made of metal materials, and the side plate 12 is preferably integrally injection-molded from an insulating plastic material. The front inner side surface 421, the rear inner side surface 422, the first mating inner side surface 423, the second mating inner side surface 424, and the arc surface 420 are all formed of the plastic material integrally provided with the side plate 12. The inner bottom surface 401 is further extended from the bottom plate 11. The inner top surface 402 is further extended from the top plate 13. In a preferred embodiment of the present application, the rear inner side surface 422 is perpendicularly connected to the inner bottom surface 401.

[0066] One implementation is as Figure 6 shown, where a convex-shaped bearing transition portion 4210 is formed on the inner surface position of the joint position between the part of the top plate 13 forming the inner top surface 402 and the plastic part forming the arc surface 420, so as to make the combination of the part of the top plate 13 and the plastic part forming the arc surface 420 more stable and firm. Under the condition of ensuring that the bonding force between the two is sufficient, the smaller the bearing transition portion 4210 is designed, the better. Of course, in order to make the airflow flowing into the flow dividing channel 4 flow more smoothly, the bearing transition portion 4210 can be formed on the outer surface of the joint position between the part of the top plate 13 forming the inner top surface 402 and the plastic part forming the arc surface 420 (specific reference Figure 7 to another embodiment shown).

[0067] Furthermore, in a preferred implementation, the respective extending planes of the front inner side surface 421, the rear inner side surface 422, the first mating inner side surface 423, and the second mating inner side surface 424 are all perpendicular to the plane of the upper surface of the bottom plate 11. In addition, in order to be more conducive to integrally injection-molding to form the diversion section 42, the projection of the plastic part of the side plate 12 further extending to form the arc surface 420 and the rear inner side surface 422 along the axial direction of the fan wheel assembly 2 do not overlap (as shown in the attached Figure 6 , attached Figure 7 : taking the interface P1 as the boundary, the rear inner side surface 422 and the plastic part forming the arc surface 420 are respectively located on both sides of the interface P1). Such a design can facilitate direct demolding in the up and down direction (the axial direction of the fan wheel assembly 2) during integrally injection-molding.

[0068] In addition, in other embodiments, the second inner side surface 404 may be shortened or not provided, and the rear end inner side surface 422 is directly formed at the intersection C position in the appended drawings, which is equivalent to shortening the extension length of the DC section 41, depending on the needs of the usage scenario. Figure 4 The intersection C position in the appended drawings, which is equivalent to shortening the extension length of the DC section 41, depending on the needs of the usage scenario.

[0069] By designing the structure of the flow dividing channel 4, the present application can achieve bidirectional air outlet in the axial direction and the radial direction of the fan wheel assembly 2. In addition, through the specific position layout and overall structure design of the flow dividing channel 4, the starting position design and inclined setting of the first inner side surface 403 and other structural designs, the kinetic energy loss of the air flow in the inner flow channel 3 can be reduced or weakened, and the overall air driving efficiency of the fan wheel assembly can be improved.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this design and are not intended to limit them. Although the present design has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this design.

[0071] Although the embodiments of the present application have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, replacements, and variations can be made to these embodiments without departing from the principle and spirit of the present application. The scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A centrifugal two-way air outlet fan, characterized in that, Comprising: A fan frame (1) forming a hollow installation cavity (10), the fan frame (1) including a bottom plate (11), side plates (12) extending upward from the periphery of the bottom plate (11), and a top plate (13) covering the upper edge of the side plates (12) and spaced apart from the bottom plate (11); A fan wheel assembly (2) rotatably coupled within the installation cavity (10); An air inlet (101) formed through the top plate (13) in the vertical direction and located directly above the fan wheel assembly (2), the air inlet (101) communicating the installation cavity (10) with the outside in the axial direction of the fan wheel assembly (2); A first air outlet (102) formed at the position of the side plate (12) between the bottom plate (11) and the top plate (13), the first air outlet (102) communicating the installation cavity (10) with the outside in the radial direction of the fan wheel assembly (2); An inner flow channel (3) formed between the outer periphery of the fan wheel assembly (2) and the inner wall surface of the side plate (12); A tongue portion (121) formed on the side plate (12) and located on one side of the first air outlet (102), the width of the inner flow channel (3) in the radial direction of the fan wheel assembly (2) gradually increasing from the position of the tongue portion (121) along the rotation direction of the fan wheel assembly (2); The inner flow channel (3) sequentially includes a pressurization zone (31), a diversion zone (32), and a pressure relief zone (33) from the position of the tongue portion (121) along the rotation direction of the fan wheel assembly (2); The fan frame (1) further forms a diversion channel (4) including a direct current section (41) and a diversion section (42) that communicate with each other, the direct current section (41) extending in the radial direction of the fan wheel assembly (2) and communicating with the diversion zone (32), the diversion section (42) further extending downward from one end of the direct current section (41), and a second air outlet (103) with a downward opening formed at the lower end position of the diversion section (42).

2. The centrifugal double - direction air - outlet fan according to claim 1, wherein: A straight line where the edge of the first air outlet (102) is located is defined as a horizontal line A0; A straight line passing through the axis of the fan wheel assembly (2) and perpendicular to the horizontal line A0 is defined as a first dividing line A1; A straight line passing through the axis of the fan wheel assembly (2) and parallel to the horizontal line A0 is defined as a second dividing line A2; The diversion zone (32) of the inner flow channel (3) is located between the first dividing line A1 and the second dividing line A2.

3. The centrifugal two-way air outlet fan according to claim 1, wherein: The diversion section (42) extends in the axial direction of the fan wheel assembly (2), and the second air outlet (103) opens downward in the axial direction of the fan wheel assembly (2).

4. The centrifugal two-way air outlet fan according to claim 2, characterized in that: The direct current section (41) includes an inner bottom surface (401), an inner top surface (402), and a first inner side surface (403); The inner bottom surface (401) is flush with the upper surface of the bottom plate (11); The inner top surface (402) is flush with the lower surface of the top plate (13).

5. The centrifugal two-way air outlet fan according to claim 4, wherein: The first inner side surface (403) is a planar shape perpendicular to the upper surface of the bottom plate (11).

6. The centrifugal double - direction air - outlet fan according to claim 5, wherein: The first dividing line A1 and the inner wall surface of the side plate (12) forming the inner flow channel (3) form an intersection point B; The straight line passing through the intersection point B and parallel to the horizontal line A0 is defined as the set line B0; The first inner side surface (403) is perpendicular to the upper surface of the bottom plate (11); An included angle β is formed between the first inner side surface (403) and the set line B0, and the included angle β is greater than 0 degree and not greater than 10 degrees.

7. The centrifugal two-way air outlet fan according to claim 6, characterized in that: The intersection point B lies on the first inner side surface (403).

8. The centrifugal two-way air outlet fan according to claim 7, wherein: The first inner side surface (403) is formed by extending with the straight line passing through the intersection point B and perpendicular to the upper surface of the bottom plate (11) as the starting edge.

9. The centrifugal two-way air outlet fan according to claim 6, wherein: The set line B0 is the tangent line of the pressurized area (31) of the inner flow channel (3) at the position of the intersection point B.

10. The centrifugal two-way air outlet fan according to claim 4 or 5 or 6 or 7 or 8 or 9, characterized in that: The straight-through section (41) further includes a second inner side surface (404), the second inner side surface (404) is closer to the horizontal line A0 than the first inner side surface (403), and on the extension surface of the inner bottom surface (401), the extension length of the first inner side surface (403) is greater than the extension length of the second inner side surface (404); The second inner side surface (404) is parallel to the horizontal line A0; An intersection part C is formed between the second inner side surface (404) and the inner wall surface of the inner flow channel (3); The flow channel width L2 of the shunt channel (4) at the position of the intersection part C is greater than the flow channel width L1 of the inner flow channel (3) at the position of the intersection point B; The flow channel width L2 of the shunt channel (4) at the position of the intersection part C is less than the flow channel width L3 of the inner flow channel (3) at the position of the intersection part C; The guiding section (42) is formed by extending axially downward along the fan wheel assembly (2), and the guiding section (42) forms a front-end inner side surface (421), a rear-end inner side surface (422), a first mating inner side surface (423) and a second mating inner side surface (424); The first mating inner side surface (423) is coplanar with the first inner side surface (403); The second mating inner side surface (424) is coplanar with the second inner side surface (404); The front-end inner side surface (421) is perpendicular to the inner top surface (402) and is connected through an arc surface (420) in a transitional manner, and the arc surface (420) is formed by extending from the side plate (12); The rear-end inner side surface (422) is connected to the inner bottom surface (401); The respective extension planes of the front-end inner side surface (421), the rear-end inner side surface (422), the first mating inner side surface (423) and the second mating inner side surface (424) are all perpendicular to the plane where the upper surface of the bottom plate (11) is located; The part of the side plate (12) that extends to form the arc surface (420) does not overlap with the projection of the rear-end inner side surface (422) in the axial direction of the fan wheel assembly (2).

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