Volute of centrifugal fan, centrifugal fan comprising volute and range hood comprising volute

Abstract

The volute comprises an upper cover plate, a lower cover plate and an annular wall, and a volute tongue is arranged at the position, at an outlet area of a volute flow channel, of the annular wall; the upper cover plate and the lower cover plate are provided with volute flow guide devices at volute tongues respectively, the two volute flow guide devices stretch and protrude from the inner wall face to the inner cavity plane respectively, each volute flow guide device comprises a first side wall, a second side wall and two arc-shaped side walls, the two ends of each first arc-shaped side wall are connected with the corresponding first side wall and the corresponding second side wall respectively, and the two ends of each first arc-shaped side wall are connected with the corresponding second arc-shaped side wall respectively. The first side wall and the second side wall are arranged at an angle; the first side wall extends towards the interior of the volute flow channel in an arc mode and is spaced from the impeller. And the second side wall and the wall surface of the ring wall opposite to the volute tongue are arranged at intervals. According to the volute of the centrifugal fan, the centrifugal fan comprising the volute and the range hood comprising the volute, the low-speed airflow at the volute tongue is guided through the volute guide device, the gas fluidity at the outlet of the volute is improved, flow separation is avoided, the performance of the fan is improved, and noise is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of range hoods, and particularly relates to a volute of a centrifugal fan, a centrifugal fan including the same, and a range hood. Background Art

[0002] Due to characteristics such as a high pressure coefficient, a large flow coefficient, and a compact structure, centrifugal fans are widely used in household electrical appliance industries such as range hoods and air conditioners. Among them, for a range hood using a centrifugal fan, while exhausting the kitchen fumes outdoors, it will also be accompanied by working noise, thus affecting the physical and mental health of the cook. Therefore, how to operate efficiently, stably, and quietly is a key issue in the design of related products. Among them, the structural design of the centrifugal fan is closely related to the overall performance of the range hood, and the flow state in the volute outlet and volute tongue area of the fan has an important impact on the performance and noise of the centrifugal fan.

[0003] For example, in the Chinese invention patent "A Centrifugal Fan, a Range Hood and Its Control Method" with the application number 202211582872.4, it includes a volute and an impeller arranged in the volute. The volute includes spaced-apart covers, an annular wall arranged between the covers, and an air outlet. The centrifugal fan also includes a volute tongue assembly, including a tongue portion, a scroll, and a spring piece. By adjusting the volute tongue radius on the premise of ensuring the invariance of the volute tongue gap through the structural arrangement, the fan is in the best working state under different working conditions, improving the user experience. Another example is the volute tongue structure proposed in the Chinese utility model patent "Volute Tongue Structure of a Double-Inlet Centrifugal Fan, a Double-Inlet Centrifugal Fan and a Range Hood" with the application number 202322263511.X, which includes a volute tongue body and is axially divided into a first volute tongue section and a second volute tongue section. The first volute tongue section faces the front impeller of the double-inlet impeller, and the second volute tongue section faces the rear impeller of the double-inlet impeller, and a concave curved surface is formed between the first volute tongue section and the second volute tongue section, effectively improving the flow field state of the fan under different working conditions, enhancing the fan performance and reducing noise. These existing technologies are all based on the role of the volute tongue in the fan and improve its structure in combination with the flow characteristics of the fan under different working conditions, improving the fan performance to a certain extent.

[0004] However, through further research on the internal flow field of the centrifugal fan, it is found that: under any working conditions, there are differences in the flow field distribution along the axial direction of the meridional plane of the fan, and the flow non-uniformity in the volute outlet area is relatively obvious, and it is highly sensitive to the performance and noise of the fan. Among them, there is obvious low-speed flow at the volute tongue at the volute outlet. The main reason is that the air flow at the impeller outlet impacts the volute tongue ring wall, making the static pressure near the volute tongue relatively high. In addition, there is an axial gap between the impeller and the volute, and the dynamic-static interference makes the gas flow in this area relatively complex. The air flow in this gap mainly flows with the main air flow under the action of pressure difference and viscosity, and the flow velocity is relatively low. Especially in the volute tongue area, due to the impact of the main air flow at the impeller outlet on the volute tongue wall, the local pressure increases, resulting in an obvious low-speed area in the volute area with dynamic-static interference, generating flow separation, which affects the performance and noise of the fan.

[0005] Therefore, in the prior art, there are problems such as flow non-uniformity and low flow velocity in the low-speed area at the volute tongue, and the dynamic-static interference leads to flow separation, thus affecting the performance and noise of the fan. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the defects that the air flow in the volute tongue area in the prior art is non-uniform and prone to flow separation, and to provide a volute of a centrifugal fan, a centrifugal fan including the same, and a range hood.

[0007] The present invention solves the above technical problems through the following technical solutions:

[0008] A volute of a centrifugal fan, the volute includes an upper cover plate, a lower cover plate and a ring wall. The two ends of the ring wall along the axial direction of the volute are connected to the upper cover plate and the lower cover plate. An impeller of the centrifugal fan is arranged in the volute. A volute flow channel surrounding the impeller is formed between the ring wall and the impeller. A volute tongue is arranged at the outlet area of the volute flow channel of the ring wall and close to the inner side of the volute.

[0009] Volute guiding devices are respectively arranged on the upper cover plate and the lower cover plate at the volute tongue. The volute guiding device includes a top surface protruding into the inner cavity of the volute, and the top surface is parallel to the joint surface where the volute guiding device is attached to the upper cover plate or the lower cover plate.

[0010] The volute guiding device includes a first part and a second part. The side wall of the first part includes a first side wall, a first arc-shaped side wall and a second arc-shaped side wall. The side wall of the second part includes a top wall and a second side wall.

[0011] The second arc-shaped side wall abuts against the volute tongue, and both ends of the second arc-shaped side wall are connected to the top wall and the first side wall; the first side wall is arranged to extend in an arc shape towards the inside of the volute flow channel and is arranged at a radial interval from the impeller along the volute; both ends of the first arc-shaped side wall are respectively connected to the first side wall and the second side wall, and the first side wall and the second side wall are arranged at an angle; the second side wall is opposite to and spaced from the outlet wall surface at the volute outlet, and the included angle between the second side wall and the outlet wall surface is not greater than the first angle value; the top wall is connected to the second side wall, and the top wall is arranged at the outlet of the volute and is parallel to the outlet section of the volute.

[0012] In this solution, the volute of the centrifugal fan is provided with the volute flow guiding device with the above structure, which guides the low-speed air flow at the volute tongue, improves the gas fluidity at the volute outlet, avoids flow separation, improves the performance of the fan, and reduces the noise. Among them, the first side wall extends in an arc shape towards the inside of the volute flow channel and is arranged at a radial interval from the impeller, so that the first side wall can effectively guide the air flow in the volute flow channel at the volute tongue; the second side wall is opposite to and spaced from the outlet wall surface, and the included angle thereof is set not to be greater than the first angle value, so that the second side wall is inclined or parallel to the outlet wall surface within a small angle range, that is, the volute reverse flow device approaches the outlet wall surface through the second part, reduces the influence of the flow guiding device on the air flow at the volute outlet, and promotes the flow guiding effect of the flow guiding device at the volute outlet; the first side wall and the second side wall are arranged at an angle and are connected to both ends of the first arc-shaped side wall, forming a triangular and pointed flow guiding structure, and the volute flow guiding device as a whole protrudes from the joint surface with the upper cover plate and the lower cover plate towards the inner cavity, so such a volute flow guiding device constitutes a triangular pointed flow guiding device with a certain thickness, which can effectively guide the gas flowing through the first side wall (facing the impeller) and the second side wall (facing the ring wall opposite to the volute tongue), thereby improving the gas fluidity at the volute outlet.

[0013] Preferably, the range of the first angle value is 0° - 15°.

[0014] In this solution, the first angle value adopts the numerical value in this range, further restricting the inclination of the second side wall relative to the outlet wall surface within a very small angle range, which is beneficial to improving the air flow fluidity at the volute outlet, thereby improving the fluidity in the low-speed air flow area at the volute outlet.

[0015] Preferably, the volute includes a central vertical plane, and the central vertical plane is a vertical plane passing through the center of the volute and perpendicular to the upper cover plate or the lower cover plate; the included angle between the end of the first side wall extending in an arc shape towards the inside of the volute flow channel and the central vertical plane is the first circular arc deviation angle α, where 40° ≤ α ≤ 60°.

[0016] In this solution, the coverage area of the volute flow guiding device is determined by using the included angle set above. By using the included angle α within the above range, the flow in the low-speed flow region is improved, and the noise is reduced.

[0017] Preferably, the clearance between the first side wall and the impeller is the first radial clearance A, where 10 mm ≤ A ≤ 30 mm.

[0018] In this solution, the clearance within the above range is adopted between the first side wall and the impeller. While ensuring the flow splitting effect, it also avoids the intensification of the response of the airflow at the impeller outlet impacting the wall surface of the flow guiding device, thus being beneficial to reducing noise.

[0019] Preferably, the radius of the first arc-shaped side wall is the first arc radius R, where 12 mm ≤ R ≤ 25 mm.

[0020] In this solution, the first arc-shaped side wall adopts the radius within the above range to ensure the effective splitting of the gas and also avoids the first arc-shaped side wall with too large a radius from hindering the gas flow.

[0021] Preferably, the thickness of the volute flow guiding device protruding into the inner cavity of the volute is the first thickness D, and the diameter of the impeller is L, where 0.1L ≤ D ≤ 0.2L.

[0022] In this solution, the volute flow guiding device adopts the thickness within the above range to ensure effective flow splitting and will not affect the effective flow area due to being too thick.

[0023] Preferably, the second side wall is a side wall extending linearly. The second side wall includes a first straight edge connected to the upper cover plate or the lower cover plate. The first arc-shaped side wall includes a first arc edge connected to the upper cover plate or the lower cover plate; the first straight edge is tangent to the first arc edge; and / or, the first straight edge is parallel to the outlet profile of the outlet wall surface, and the outlet profile is the intersection line of the outlet wall surface and the cross-section parallel to the upper cover plate or the lower cover plate.

[0024] In this solution, the first straight edge of the second side wall is tangent to the first arc edge of the first arc-shaped side wall, enabling a smooth transition between the first arc-shaped side wall and the second side wall, which is beneficial to the stability of the gas flow and improves the flow guiding effect. The first straight edge being parallel to the above-mentioned outlet profile is beneficial to reducing the flow resistance of the airflow at the volute outlet and promoting the flow guiding effect.

[0025] Preferably, the two volute flow guiding devices are symmetric with respect to the central cross-section passing through the center of the volute and parallel to the upper cover plate or the lower cover plate;

[0026] And / or, the first side wall, the first arc-shaped side wall, and the second side wall have arc-shaped chamfers relative to the upper cover plate or the lower cover plate.

[0027] In this solution, the two volute guiding devices are symmetrically arranged as described above, which is beneficial to the similar flow field distribution of the air flow on both sides of the volute tongue (i.e., the two sides where the volute tongue is connected to the upper cover plate and the lower cover plate), and the gas flow is more uniform. Through the chamfers arranged as above, the three wall surfaces (the first side wall, the second side wall, and the first arc-shaped side wall) of the volute guiding device form a smoothly connected wall surface, which is beneficial to the stability of the gas flow and improves the guiding effect.

[0028] A centrifugal fan includes a volute and an impeller disposed inside the volute, and the volute is the volute as described above.

[0029] In this solution, the centrifugal fan guides the low-speed air flow at the volute tongue through the volute arranged with the above structure, improves the gas fluidity at the volute outlet, avoids flow separation, improves the performance of the fan, and reduces the noise.

[0030] Preferably, the centrifugal fan further includes an air outlet hood, the air outlet hood is connected to the volute at the outlet of the volute, and an air outlet guiding device corresponding to the volute guiding device is provided inside the air outlet hood, and the air outlet guiding device is smoothly connected to the volute guiding device.

[0031] In this solution, the centrifugal fan is smoothly connected through the air outlet guiding device and the volute guiding device, so that after the air flow flows out of the volute, the guiding effect is maintained in the air outlet hood, the gas fluidity in the entire air duct structure of the centrifugal fan is improved, flow separation is avoided, the performance of the fan is improved, and the noise is reduced.

[0032] An oil fume extractor, and the oil fume extractor includes the centrifugal fan as described above.

[0033] In this solution, the oil fume extractor improves the gas fluidity in the entire air duct structure by adopting the above centrifugal fan, avoids flow separation, improves the performance of the fan, and reduces the noise.

[0034] The positive and progressive effects of the present utility model are as follows: The volute of the centrifugal fan, the centrifugal fan including it, and the oil fume extractor guide the low-speed air flow at the volute tongue through the volute guiding device arranged with the above structure, improve the gas fluidity at the volute outlet, avoid flow separation, improve the performance of the fan, and reduce the noise. Description of the Drawings

[0035] Figure 1 It is a three-dimensional structural schematic diagram of the installation of the volute and the air outlet hood in Embodiment 1 of the present utility model.

[0036] Figure 2Schematic diagram of the internal structure of the volute and the air outlet hood in Embodiment 1 of the present utility model.

[0037] Figure 3 Top view of the volute in Embodiment 1 of the present utility model.

[0038] Figure 4 Schematic diagram of the structure of the volute guide device in Embodiment 1 of the present utility model.

[0039] Figure 5 Schematic diagram of the structure of the air outlet hood in Embodiment 1 of the present utility model.

[0040] Explanation of reference numerals:

[0041] Volute 1

[0042] Upper cover plate 2

[0043] Lower cover plate 3

[0044] Circumferential wall 4

[0045] Impeller 5

[0046] Volute tongue 6

[0047] Volute flow channel 7

[0048] Volute guide device 8

[0049] Fitting surface 85

[0050] Top surface 86

[0051] First part 87

[0052] Second part 88

[0053] First side wall 81

[0054] Second side wall 82

[0055] First straight edge 821

[0056] First arc-shaped side wall 84

[0057] First arc edge 841

[0058] Second arc-shaped side wall 80

[0059] Top wall 83

[0060] Central vertical plane 9

[0061] First arc deflection angle α

[0062] First radial clearance A

[0063] First arc radius R

[0064] First thickness D

[0065] Air outlet hood 10

[0066] Air outlet flow guiding device 11

[0067] Outlet wall surface 12 Specific implementation manner

[0068] The following is a preferred embodiment and is described in more clearly and completely in conjunction with the accompanying drawings for the present utility model.

[0069] Embodiment 1

[0070] As Figures 1-5 shown, this embodiment provides a volute 1 of a centrifugal fan. The volute 1 includes an upper cover plate 2, a lower cover plate 3 and an annular wall 4. The two ends of the annular wall 4 along the axial direction of the volute 1 are connected to the upper cover plate 2 and the lower cover plate 3. An impeller 5 of the centrifugal fan is provided inside the volute 1. A volute flow channel 7 surrounding the impeller 5 is formed between the annular wall 4 and the impeller 5. A volute tongue 6 is provided at the outlet area of the volute flow channel 7 and near the inner side of the volute 1. The contour line of the cross-section of the volute tongue 6 includes a straight line segment (i.e., the line segment connected to the volute outlet) that is smoothly connected to each other, an arc segment and a spiral line segment (i.e., the line segment connected to the annular wall 4 of the volute).

[0071] Volute flow guiding devices 8 are respectively attached to the upper cover plate 2 and the lower cover plate 3 at the volute tongue 6. The volute flow guiding device 8 includes a top surface 86 protruding into the inner cavity of the volute. The top surface 86 is parallel to the fitting surface 85 where the volute flow guiding device 8 is attached to the upper cover plate 2 or the lower cover plate 3.

[0072] The volute flow guiding device 8 includes a first part 87 and a second part 88. The side wall of the first part 87 includes a first side wall 81, a first arc-shaped side wall 84 and a second arc-shaped side wall 80. The side wall of the second part 88 includes a top wall 83 and a second side wall 82, that is, the first part 87 and the second part 88 are the parts on both sides of the dotted line as Figure 4 shown. The second arc-shaped side wall 80 abuts against the volute tongue 6. The two ends of the second arc-shaped side wall 80 are connected to the top wall 83 and the first side wall 81. The first side wall 81 is arranged to extend in an arc shape towards the inside of the volute flow channel 7 and is arranged at a radial interval from the impeller 5 along the volute. The two ends of the first arc-shaped side wall 84 are respectively connected to the first side wall 81 and the second side wall 82. The first side wall 81 and the second side wall 82 are arranged at an angle. The second side wall 82 is opposite to and spaced from the outlet wall surface 12 at the volute outlet of the annular wall 4. The included angle between the second side wall 82 and the outlet wall surface 12 is not greater than the first angle value. The top wall 83 is connected to the second side wall 82. The top wall 83 is arranged at the outlet of the volute and is parallel to the outlet section of the volute.

[0073] Specifically, in this embodiment, the two volute guiding devices 8 respectively extend and protrude from the inner wall surfaces of the upper cover plate 2 and the lower cover plate 3 towards the inner cavity plane of the volute 1. That is, the two volute guiding devices 8 are solid structures, which is beneficial to reducing vibration and making the structure more stable. In other embodiments, the protruding structure inside the volute guiding device 8 can also be hollow to save materials. In this embodiment, the second arc-shaped side wall 80 encloses the arc segment of the volute tongue 6. In other embodiments, preferably, the second arc-shaped side wall 80 can also be extended to the spiral segment of the volute tongue 6, which is beneficial to a better guiding effect.

[0074] Through the volute guiding device 8 arranged with the above structure in the volute 1 of the centrifugal fan, the low-speed air flow at the volute tongue 6 is guided, improving the gas fluidity at the outlet of the volute 1, avoiding flow separation, enhancing the performance of the fan, and reducing noise. Among them, the first side wall 81 extends in an arc towards the inside of the volute flow channel 7 and is arranged at a radial interval from the impeller 5, so that the first side wall 81 can effectively guide the air flow in the volute flow channel at the volute tongue 6; the second side wall 82 is opposite to and spaced from the outlet wall surface 12, and the included angle therebetween is set to be not greater than the first angle value, so that the second side wall 82 is inclined or parallel to the outlet wall surface 12 within a relatively small angle range. That is, the volute reverse flow device 8 approaches the outlet wall surface 12 through the second part 88, reducing the influence of the volute guiding device 8 on the volute outlet air flow and promoting the guiding effect of the volute guiding device 8 at the volute outlet; the first side wall 81 and the second side wall 82 of the volute guiding device 8 are arranged at an angle and are connected to both ends of the first arc-shaped side wall 84, forming a triangular and pointed guiding structure. And the volute guiding device 8 as a whole protrudes from the joint surface 85 of the upper cover plate 2 and the lower cover plate 3 towards the inner cavity. Therefore, such a volute guiding device 8 constitutes a triangular pointed guiding device with a certain thickness, which can effectively guide the gas flowing through the first side wall 81 (facing the impeller 5) and the second side wall 82 (facing the annular wall opposite to the volute tongue 6), thereby improving the gas fluidity at the outlet of the volute 1.

[0075] Among them, the range of the first angle value is 0° - 15°. For example, the included angle between the outlet wall surface of the volute and the vertical plane perpendicular to the upper cover plate or the lower cover plate is β, the included angle between the second side wall 82 and the vertical plane is θ, and the included angle between the second side wall 82 and the outlet wall surface 12 is the difference between θ and β. Then 0° ≤ |θ - β| ≤ 15°. Using this range of values for the first angle value further restricts the inclination of the second side wall 82 relative to the outlet wall surface 12 within a very small angle range, which is beneficial to improving the air flow fluidity at the volute outlet, thereby improving the fluidity in the low-speed air flow region at the volute outlet.

[0076] Further, in this embodiment, the first angle value is 0°, that is, the second side wall 82 is parallel to the outlet wall surface 12. In other embodiments, the size of the first angle value can be adjusted accordingly according to the needs of the diversion effect. However, for a better diversion effect, the first angle value should be as small as possible.

[0077] Among them, as Figure 2 shown, the volute 1 includes a central vertical plane 9, and the central vertical plane 9 is a vertical plane passing through the center of the volute 1 and perpendicular to the upper cover plate 2 or the lower cover plate 3; the included angle between the end of the first side wall 81 extending in an arc towards the inside of the volute flow path 7 and the central vertical plane 9 is the first circular arc deflection angle α, where 40° ≤ α ≤ 60°. This embodiment adopts the included angle within the above range, which is the preferred angle range. The included angle α determines the coverage area of the volute diversion device 8, and the included angle α within the above range can ensure the improvement of the flow in the low-speed flow area and reduce noise.

[0078] Among them, the gap between the first side wall 81 and the impeller 5 is the first radial gap A, where 10 mm ≤ A ≤ 30 mm. By using the gap within the above range between the first side wall 81 and the impeller 5, while ensuring the flow splitting effect, it also avoids the intensification of the impact of the airflow at the outlet of the impeller 5 on the wall surface of the diversion device, which is beneficial to reducing noise.

[0079] Among them, the radius of the first arc-shaped side wall 84 is the first circular arc radius R, where 12 mm ≤ R ≤ 25 mm. By adopting the radius within the above range for the first arc-shaped side wall 84, it ensures the effective splitting of the gas and also avoids the first arc-shaped side wall 84 with too large a radius from hindering the gas flow.

[0080] Among them, the thickness of the volute diversion device 8 stretched towards the inner cavity plane of the volute 1 is the first thickness D, and the diameter of the impeller 5 is L, where 0.1L ≤ D ≤ 0.2L. By adopting the thickness within the above range for the volute diversion device 8, it ensures effective flow splitting and does not affect the effective flow area due to being too thick.

[0081] Among them, the second side wall 82 is a side wall with a straight extension. The second side wall 82 includes a first straight edge 821 connected to the upper cover plate 2 or the lower cover plate 3. The first arc-shaped side wall 84 includes a first circular arc edge 841 connected to the upper cover plate 2 or the lower cover plate 3. The first straight edge 821 is tangent to the first circular arc edge 841. The first straight edge 821 of the second side wall 82 is parallel to the outlet profile of the outlet wall surface 12, and the outlet profile is the intersection line of the outlet wall surface 12 and the cross-section parallel to the upper cover plate 2 or the lower cover plate 3. The tangency of the first straight edge 821 of the second side wall 82 and the first circular arc edge 841 of the first arc-shaped side wall 84 enables a smooth transition between the first arc-shaped side wall 84 and the second side wall 82, which is beneficial to the stability of gas flow and improves the diversion effect. The parallelism of the first straight edge 821 to the above-mentioned outlet profile is beneficial to reducing the flow resistance of the airflow at the volute outlet and promoting the diversion effect.

[0082] Among them, in this embodiment, the two volute guiding devices 8 are symmetrical with respect to the central cross-section passing through the center of the volute and parallel to the upper cover plate 2 or the lower cover plate 3. By adopting the above symmetrical arrangement of the two volute guiding devices 8, it is beneficial to make the flow field distributions on both sides of the volute tongue 6 (i.e., the two sides where the volute tongue 6 is connected to the upper cover plate 2 and the lower cover plate 3) similar, and the gas flow is more uniform. In other embodiments, according to the requirements of the gas flow distribution and the guiding effect, the two volute guiding devices 8 may also be asymmetrical with respect to the central cross-section, allowing for a small difference in the positions and the surface profile shapes of the two volute guiding devices 8.

[0083] As Figure 4 shown, the first side wall 81, the first arc-shaped side wall 84 and the second side wall 82 are arc chamfered with respect to the upper cover plate 2 or the lower cover plate 3. Through the above-set chamfers, the three wall surfaces (the first side wall 81, the second side wall 82 and the first arc-shaped side wall 84) of the volute guiding device 8 form smoothly connected wall surfaces, which is beneficial to the stability of the gas flow and improves the guiding effect.

[0084] In other embodiments, according to the requirements of the guiding effect, the numerical ranges of the above four parameters (the first arc deflection angle α, the first radial clearance A, the first arc radius R and the first stretching thickness D) can also be adjusted accordingly as needed. In this embodiment, it is a preferred numerical range that these four parameters adopt the above numerical ranges.

[0085] In order to obtain a preferred combination scheme, these four parameters can respectively adopt a 3-level design selection, which are: the factor levels of the first radial clearance A are respectively: 10 mm, 20 mm and 30 mm; the factor levels of the first arc radius R are respectively: 12 mm, 18.5 mm and 25 mm; the factor levels of the first arc deflection angle are respectively: 40°, 50°, 60°; the factor levels of the first stretching thickness D are respectively: 0.1L, 0.15L and 0.2L.

[0086] Further, in order to obtain the optimal combination scheme, the volute flow guiding device 8 can also be optimized by simulation calculation. Specifically, taking the first radial clearance A, the first arc radius R, the first arc deflection angle α, and the first thickness D as four factors, and the air volume Q and total pressure efficiency η of the fan as responses, a response surface optimization and simulation calculation of four factors and three levels are carried out to obtain the optimal combination scheme of the first flow guiding device. In this embodiment, the significance ranking of the response air volume Q with respect to the four factors is as follows: the deflection angle α of the first volute tongue 6, the first radial clearance A, the radius R of the first volute tongue 6, and the first thickness D; and the significance ranking of the response total pressure efficiency η with respect to the four factors is as follows: the deflection angle α of the first volute tongue 6, the first radial clearance A, the first thickness D, and the radius R of the first volute tongue 6. In addition, the optimal combination scheme for the response air volume Q and total pressure efficiency η is: A = 10 mm, R = 25 mm, α = 60°, D = 14.5 mm. For different multi-wing centrifugal fans, the factor design levels of the four parameters are different, and the final optimal combination scheme is also different. It is necessary to select an effective parameter range for design according to the above principles and methods.

[0087] In this embodiment, the improved scheme (i.e., the fan with the volute flow guiding device 8 of this embodiment) is compared with the prototype machine (i.e., the fan without the volute flow guiding device 8), and the experimental results are shown in the following table:

[0088]

[0089] This embodiment also provides a centrifugal fan, including the volute 1 as described above and an impeller 5 provided inside the volute 1. Through the volute 1 arranged with the above structure, the centrifugal fan guides the low-speed air flow at the volute tongue 6, improves the gas fluidity at the outlet of the volute 1, avoids flow separation, improves the performance of the fan, and reduces the noise.

[0090] Among them, as Figure 1 and Figure 5 shown, the centrifugal fan further includes an air outlet hood 10. The air outlet hood 10 is connected to the volute 1 at the outlet of the volute 1, and an air outlet flow guiding device 11 corresponding to the volute flow guiding device 8 is arranged inside the hood, and the air outlet flow guiding device 11 is smoothly connected to the volute flow guiding device 8. Through the smooth connection between the air outlet flow guiding device 11 and the volute flow guiding device 8, after the air flow flows out of the volute 1, the guiding effect is maintained inside the air outlet hood 10, the gas fluidity in the entire air duct structure of the centrifugal fan is improved, flow separation is avoided, the performance of the fan is improved, and the noise is reduced.

[0091] Embodiment 2

[0092] This embodiment provides an oil fume machine, which includes a centrifugal fan as in Embodiment 1. By adopting the above-mentioned centrifugal fan, the oil fume machine improves the gas fluidity in the entire air duct structure, avoids flow separation, improves the performance of the fan, and reduces noise.

[0093] Although the specific embodiments of the present invention have been described above, those skilled in the art should understand that this is only an example, and the protection scope of the present invention is defined by the appended claims. Without departing from the principle and essence of the present invention, those skilled in the art can make various changes or modifications to these embodiments, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A volute of a centrifugal fan, the volute comprising an upper cover plate, a lower cover plate and an annular wall, the annular wall being connected to the upper cover plate and the lower cover plate at both ends of the axial direction of the volute, an impeller of the centrifugal fan being arranged in the volute, a volute flow channel surrounding the impeller being formed between the annular wall and the impeller, the annular wall being provided with a volute tongue at an outlet area of ​​the volute flow channel and close to an inner side of the volute; characterized in that: The upper cover plate and the lower cover plate are respectively provided with a volute flow guide device at the volute tongue, and the volute flow guide device comprises a top surface protruding toward the inner cavity of the volute, and the top surface is parallel to the fitting surface between the volute flow guide device and the upper cover plate or the lower cover plate; The volute flow guide device comprises a first part and a second part, the side wall of the first part comprises a first side wall, a first arcuate side wall and a second arcuate side wall, and the side wall of the second part comprises a top wall and a second side wall; The second arc-shaped side wall abuts against the volute tongue, and the two ends of the second arc-shaped side wall are connected to the top wall and the first side wall; the first side wall is arranged to extend in an inner arc shape toward the volute flow channel, and is spaced apart from the impeller along the radial direction of the volute; the two ends of the first arc-shaped side wall are respectively connected to the first side wall and the second side wall, and the first side wall and the second side wall are arranged at an angle; the second side wall and the annular wall are opposite to and spaced apart from the outlet wall surface of the volute outlet, and the angle between the second side wall and the outlet wall surface is not greater than the first angle value; the top wall is connected to the second side wall, and the top wall is arranged at the outlet of the volute and is parallel to the outlet cross-section of the volute.

2. The volute of a centrifugal fan according to claim 1, characterized in that: The first angle value ranges from 0° to 15°.

3. The volute of the centrifugal fan according to claim 1, characterized in that: The volute comprises a central vertical plane, which is a vertical plane passing through the center of the volute and perpendicular to the upper cover plate or the lower cover plate; the angle between the end of the first side wall extending in an arc shape toward the inner part of the volute flow channel and the central vertical plane is a first arc angle α, wherein 40°≤α≤60°; And / or, the gap between the first side wall and the impeller is a first radial gap A, wherein 10 mm ≤ A ≤ 30 mm.

4. The volute of a centrifugal fan according to claim 1, characterized in that: The radius of the first arc-shaped side wall is a first arc radius R, wherein 12 mm≤R≤25 mm.

5. The volute of the centrifugal fan according to claim 1, characterized in that: The thickness of the volute flow guide device protruding toward the inner cavity of the volute is a first thickness D, and the diameter of the impeller is L, wherein 0.1L≤D≤0.2L.

6. The volute of a centrifugal fan according to claim 1, characterized in that: The second side wall is a straight-extending side wall, the second side wall includes a first straight edge connected to the upper cover plate or the lower cover plate, and the first arc-shaped side wall includes a first arc edge connected to the upper cover plate or the lower cover plate; The first straight edge is tangent to the first arc edge; and / or the first straight edge is parallel to the outlet profile of the outlet wall, and the outlet profile is the intersection line of the outlet wall and a cross section parallel to the upper cover plate or the lower cover plate.

7. The volute of a centrifugal fan according to claim 1, characterized in that: The two volute flow guide devices are symmetrical with respect to a central cross section passing through the center of the volute and parallel to the upper cover plate or the lower cover plate; And / or, the first side wall, the first curved side wall and the second side wall have curved chamfers relative to the upper cover plate or the lower cover plate.

8. A centrifugal fan, comprising a volute and an impeller arranged inside the volute, characterized in that: The volute is the volute according to any one of claims 1 to 7.

9. The centrifugal fan according to claim 8, characterized in that: The centrifugal fan also includes an air outlet hood, which is connected to the volute at the outlet of the volute, and an air outlet guide device corresponding to the volute guide device is provided in the air hood, and the air outlet guide device is smoothly connected to the volute guide device.

10. A range hood, characterized in that: The range hood comprises the centrifugal fan as claimed in claim 8 or 9.

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