Volute, centrifugal fan and range hood

Abstract

The application relates to a volute, a centrifugal fan and a range hood. The volute comprises a ring wall used to define a volute profile line, wherein the ring wall has a starting end located upstream and a terminal end located downstream in a flow path of air flow, the ring wall has a bending part formed by connecting a plurality of fold line segments near the terminal end, wherein when the ring wall defines a first volute profile line, the bending part extends in a wave shape, a fold angle is formed between the fold line segment and a line connecting adjacent valleys in the bending part, and the fold angle is not greater than 15 DEG. The application can improve the air volume of the volute and optimize the air flow performance of the volute under a certain profile line. The application further provides a centrifugal fan and a range hood comprising the above volute.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fan systems, in particular to a volute, a centrifugal fan and a range hood. BACKGROUND

[0002] The noise level of a fan system is an important indicator for evaluating the quality of the fan system. The noise indicator is an important basis for users to intuitively compare the performance of products, and noise also directly affects the user experience. Therefore, how to reduce the noise of the fan system is crucial.

[0003] Among the many methods for reducing the noise of a fan system, designing a reasonable volute profile is a common means. After designing a reasonable volute profile, the ring wall of the volute is manufactured according to the volute profile. The volute profile in the prior art is usually a smooth spiral curve, and the ring wall manufactured based on this is also usually a continuously smooth curved curve. After the ring wall is manufactured according to the preset volute profile, the noise and air flow level under a specific working condition are basically determined, and it is usually difficult to further optimize the air flow performance.

[0004] In view of this, it is necessary to propose a new technical scheme to overcome the shortcomings of the prior art. SUMMARY

[0005] Based on this, the present application provides a volute, a centrifugal fan and a range hood, which can improve the air volume of the volute and optimize the air flow performance of the volute under a determined profile.

[0006] To this end, the present application adopts the following technical scheme: a volute, comprising a ring wall for defining a volute profile, the ring wall having a start end located upstream and an end located downstream in the flow path of the airflow, the ring wall having a bending portion formed by connecting a plurality of fold line segments near the end, wherein when the ring wall defines a first volute profile, the bending portion extends in a wave shape, the fold line segment and the connecting line between adjacent troughs in the bending portion form a fold angle, and the fold angle is not greater than 15°.

[0007] In one embodiment, the fold angle is 5°-10°.

[0008] In one embodiment, the length of the fold line segment is 5mm-7mm.

[0009] In one embodiment, the volute comprises a first support portion located above the ring wall, the first support portion supporting the ring wall when the ring wall defines the first volute profile, and the first support portion is provided with a wave-shaped structure matching the bending portion.

[0010] In one of the embodiments, the bending part is switchable between an extended state and a folded state, and the bending part is in the extended state when the ring wall defines the first volute profile.

[0011] In one of the embodiments, the bending part is in the folded state, and the fold line segment is perpendicular to the line connecting the adjacent valleys in the bending part.

[0012] In one of the embodiments, the ring wall defines a second volute profile when the bending part is in the folded state, the first volute profile is longer than the second volute profile, and the end position of the first volute profile is higher than the end position of the second volute profile.

[0013] In one of the embodiments, the volute comprises side walls on both sides of the ring wall, the side walls and the ring wall enclose an air duct, the air duct has an air duct outlet, and the side wall is provided with a limiting groove defining the end position of the ring wall near the air duct outlet.

[0014] In one of the embodiments, the limiting groove is an elongated slot extending in the up-down direction, and the ring wall is provided with a convex part in sliding cooperation with the limiting groove; when the convex part slides to the lower part of the limiting groove, the bending part is extruded into the folded state, and when the convex part slides to the upper part of the limiting groove, the bending part is stretched into the extended state.

[0015] In one of the embodiments, the volute comprises a push rod, and the push rod applies force to the ring wall to switch the bending part between the extended state and the folded state.

[0016] The application also adopts the following technical solution: a centrifugal fan comprising a fan and a volute as described in any of the above embodiments.

[0017] The application also adopts the following technical solution: a range hood comprising a centrifugal fan as described above.

[0018] The volute provided by the application has a bending part at the end of the ring wall, and when the ring wall defines the first volute profile, the fold line segment in the bending part has a reasonable fold angle, which can guide the airflow to form a favorable vortex structure, so that the airflow flow rate near the ring wall at the air outlet of the volute is increased, the boundary layer thickness is reduced, the fluid is more easily separated from the wall surface, the separation phenomenon of the fluid is improved, and the air outlet flow rate is increased. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or the description of the prior art will be briefly introduced. Obviously, the accompanying drawings in the following description only show some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative effort based on these drawings.

[0020] Figure 1 A perspective view of an embodiment of the volute provided in the present application.

[0021] Figure 2 A perspective view of another view of an embodiment of the volute provided in the present application.

[0022] Figure 3 A sectional view of an embodiment of the volute provided in the present application.

[0023] Figure 4 A perspective view of an embodiment of the volute provided in the present application. Figure 3 An enlarged view of a partial portion of the volute.

[0024] Figure 5 A perspective view of an embodiment of the volute provided in the present application.

[0025] Figure 6 An enlarged view of a partial portion of an embodiment of the volute provided in the present application.

[0026] The element reference numbers are as follows:

[0027] 100, volute; 101, air duct; 102, air duct outlet; 1, ring wall; 11, initial end; 12, terminal end; 13, bending portion; 131, convex portion; 2, side wall; 201, limiting groove; 21, first supporting portion; 22, second supporting portion; 3, connecting piece; 4, push rod; 5, outer shell. DETAILED DESCRIPTION

[0028] In order to make the above objectives, features and advantages of the present application more apparent, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. In the following description, a lot of specific details are set forth in order to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0029] It is to be understood that where the terms specific, "fixed", "connected", or terms such as similar terms used in the description of the specification are used, they can be directly connected, or there can be intermediate components present. The terms "vertical", "horizontal", "upper", "lower", "left", "right", and similar terms are used for the purpose of description and are not intended to indicate the sole orientation of the application.

[0030] In addition, the terms "first", "second", "third", etc. are used herein for purposes of description and are not intended to refer to or imply a relative importance or a quantity of the identified technical features. That is, a feature defined with "first", "second" or "third" can include at least one of the feature explicitly or implicitly. In the description of the present application, the meaning of "a plurality" is at least two, for example, two, three, etc., unless otherwise explicitly specified and limited.

[0031] In the present application, unless otherwise explicitly specified and limited, the "on", "under", "above", and "over" of the first feature to the second feature can be that the first feature is in direct contact with the second feature, or the first feature is indirectly in contact with the second feature through an intermediate medium. Moreover, the "on", "above", and "over" of the first feature to the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the first feature is horizontally higher than the second feature. The "under", "below", and "under" of the first feature to the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the first feature is horizontally lower than the second feature.

[0032] Unless otherwise defined, all technical and scientific terms used in the specification of the present application have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used in the specification of the present application includes any and all combinations of one or more related listed items.

[0033] Please refer to Figures 1 to 6 As shown in the drawings, the present application provides a volute 100, which includes a ring wall 1 used to define a volute profile, and the ring wall 1 has a starting end 11 located upstream and an ending end 12 located downstream in the flow path of the airflow. The ring wall 1 has a bending portion 13 formed by connecting a plurality of fold line segments near the ending end 12, wherein when the ring wall 1 defines a first volute profile, the bending portion 13 extends in a wave shape, and the fold line segment and the line connecting adjacent valleys in the bending portion 13 form a fold angle θ, and the fold angle θ is not greater than 15°.

[0034] This application provides a bent section 13 at the end 12 of the annular wall 1. When the annular wall 1 defines the first volute profile, the bent section 13 has a reasonable crease angle θ, which can guide the airflow to form a favorable vortex structure. This causes the airflow velocity at the outlet of the volute 100 close to the annular wall 1 to increase, the boundary layer thickness to decrease, and the fluid to more easily detach from the wall surface, thereby improving the fluid separation phenomenon and increasing the outlet airflow.

[0035] In one embodiment, the bent portion 13 can switch between an extended state and a folded state. The annular wall 1 defines a first volute profile when the bent portion 13 is in the extended state and a second volute profile when the bent portion 13 is in the folded state. The first volute profile is longer than the second volute profile. In this embodiment, the volute 100 has two switchable volute profiles, achieving low noise levels under different operating conditions. For example, the first volute profile exhibits excellent noise performance under semi-anechoic chamber conditions, while the second volute profile exhibits excellent noise performance under high-noise operating conditions. Furthermore, the annular wall 1 of the volute 100 provided in this embodiment is a complete structure, resulting in high structural stability and good fluid guidance performance. Of course, in other embodiments, the bent portion 13 may not have two switchable states and may operate in only one specific state.

[0036] Please see Figures 1 to 3 As shown, the annular wall 1 is a curved sheet, and its curved shape defines the path for guiding airflow in the volute 100. The volute 100 includes sidewalls 2 located on both sides of the annular wall 1, and the sidewalls 2 are generally flat sheets. The sidewalls 2 and the annular wall 1 form an air duct 101, which has an air duct outlet 102. The volute 100 also has a plurality of connectors 3 for connecting the sidewalls 2 and the annular wall 1. In this embodiment, the connectors 3 are U-shaped metal strips that span across both sides of the annular wall 1 and connect to the sidewalls 2.

[0037] Please see Figures 3 to 5As shown, in the present embodiment, the ring wall 1 is movably arranged relative to the side wall 2, i.e. the ring wall 1 is movable relative to the side wall 2, so as to switch between different profile lines. The ring wall 1 being movable relative to the side wall 2 should be understood as at least a portion of the ring wall 1 being movable relative to the side wall 2. In the present embodiment, the initial end 11 of the ring wall 1 is fixed relative to the side wall 2, and the terminal end 12 of the ring wall 1 is movable relative to the side wall 2. Herein, the initial end 11 refers to the end upstream in the direction of airflow, and the terminal end 12 refers to the end downstream in the direction of airflow. It should also be noted that, since the ring wall 1 is a gradually curved line from the initial end 11 to the terminal end 12, there is no clear boundary between the portion of the ring wall 1 fixed relative to the side wall 2 and the portion of the ring wall 1 movable relative to the side wall 2. In the present embodiment, from the initial end 11 to the terminal end 12, the ring wall 1 is movable relative to the side wall 2 with an increasing amplitude. In the present embodiment, when the ring wall 1 is moved downward relative to the side wall 2 to a lower limit position, a second volute profile line is formed, and when the ring wall 1 is moved upward relative to the side wall 2 to an upper limit position, a first volute profile line is formed. The first volute profile line and the second volute profile line partially overlap, and the terminal end 12 of the first volute profile line is located higher than the terminal end 12 of the second volute profile line. The portion of the first volute profile line and the second volute profile line overlapping is the portion close to the initial end 11 of the ring wall 1.

[0038] Please refer to Figure 4 As shown, the upper limit position and the lower limit position of the movement of the ring wall 1 are defined by the structure on the side wall 2. In the present embodiment, the side wall 2 is provided with a first support portion 21 and a second support portion 22, the first support portion 21 supports the ring wall 1 when the ring wall 1 defines the first volute profile line, and the second support portion 22 supports the ring wall 1 when the ring wall 1 defines the second volute profile line. The first support portion 21 is a folded edge extending from the top end of the side wall 2, and the second support portion 22 is a rib protruding from the inner surface of the side wall 2. The folded edge abuts the outer surface of the ring wall 1 to define the first volute profile line, and the rib abuts the inner surface of the ring wall 1 to define the second volute profile line. In the present embodiment, the first support portion 21 is located above the ring wall 1, and the first support portion 21 is provided with a wave-shaped structure matching the folded portion 13, so as to more stably support the folded portion 13 and ensure that the fold angle θ of the folded portion 13 is maintained at a specific angle, thereby ensuring stable air volume.

[0039] Please refer to Figure 5As shown, the side wall 2 is provided with a limiting groove 201 near the air duct outlet 102, which defines the position of the end 12 of the ring wall 1. The end 12 of the ring wall 1 can slide in the limiting groove 201. In this embodiment, the limiting groove 201 is a long strip groove extending in the up-down direction, and the ring wall 1 is provided with a protrusion 131 which is in sliding cooperation with the limiting groove 201. When the end 12 of the ring wall 1 slides to the lower part of the limiting groove 201 by means of the protrusion 131, the bending part 13 on the ring wall 1 is pressed into the folded state, and when the end 12 of the ring wall 1 slides to the upper part of the limiting groove 201 by means of the protrusion 131, the bending part 13 is stretched into the stretched state.

[0040] As shown in the drawings, Figures 3 to 6 As shown, the bending part 13 is a corrugated segment of the ring wall 1 which undulates in the up-down direction. When the bending part 13 is in the folded state, the valleys of the corrugated segment and the inner surface of the ring wall 1 define the second spiral casing profile. When the bending part 13 is in the folded state, the fold line segments included in the bending part 13 are perpendicular to the connecting lines of the adjacent valleys in the bending part 13; that is, each fold line segment included in the bending part 13 is in a state of close proximity to each other, in other words, each fold line segment has reached the limit of the folded state. It should be noted that the perpendicularity herein should not be limited to an absolute 90°, and according to the actual bending characteristics of different materials, it is allowed to have a certain angular deviation. When the bending part 13 is in the stretched state, the corrugated segment is stretched and unfolded, but it is not completely flattened, i.e. it forms a structure state with the fold angle θ as described above, and at this time the inner surface of the ring wall 1 defines the first spiral casing profile.

[0041] In the embodiment, the ring wall 1 and the side wall 2 are both metal sheets. When the ring wall 1 moves downward, the limiting groove 201 prevents the end 12 of the ring wall 1 from extending forward by the convex part 131, so that the bending part 13 is pressed and folded. The bending part 13 is arranged at the end 12 of the ring wall 1, and the transmission path of the pressing force of the limiting groove 201 is short, so that the folding deformation is more reliable. Of course, in other embodiments, the bending part 13 can also be arranged at other positions of the middle part of the ring wall 1. The volute 100 comprises a push rod 4, which pushes the ring wall 1 to switch the bending part 13 between the stretched state and the folded state. In the embodiment, the push rod 4 is located on the outer surface side of the ring wall 1, and the push rod 4 pushes the ring wall 1 to switch the bending part 13 from the stretched state to the folded state; when the push rod 4 releases the pushing force on the ring wall 1, the bending part 13 is reset to the stretched state by its own elastic force. The volute 100 further comprises an outer shell 5, one end of the push rod 4 is connected to the outer shell 5, and the other end abuts against the ring wall 1, and the starting end of the ring wall 1 is fixed to the outer shell 5. In the embodiment, the push rod 4 is arranged in a telescopic manner, comprising a top rod and a top rod sleeve for the extension and retraction of the top rod, and the top rod can be driven to move by an electric or pneumatic manner. In other embodiments, the push rod 4 can also be driven to rotate to push the ring wall 1.

[0042] Of course, the driving mode for switching between the stretched state and the folded state is not limited to this, and in other embodiments, the push rod 4 can be configured to apply force to the ring wall 1 in two directions, for example, when the pushing force is applied, the bending part 13 is switched to the folded state, and when the pulling force is applied, the bending part 13 is switched to the stretched state, that is, the bending part 13 is not completely reset to the stretched state by its own elastic force; in another embodiment, the push rod 4 can be arranged on the inner surface side of the ring wall 1, the push rod 4 pushes the ring wall 1 to switch the bending part 13 from the folded state to the stretched state, and the push rod 4 releases the pushing force or applies the pulling force to switch the bending part 13 from the stretched state to the folded state.

[0043] The fold line segment in the bending part 13 is arranged with a reasonable fold angle θ, which can guide the airflow to form a favorable vortex structure to improve the air outlet flow; on the contrary, an unreasonable fold angle θ will hinder the airflow and reduce the air outlet flow. Different fold angles θ have an important influence on the airflow performance, and the experimental data are shown in the following table.

[0044] Number of cells N Pitch L Crease inclination angle Θ Rotational speed Outlet air volume (m 3 / min) 5 10 0° (control) 500 rpm 18.76 5 10 5° 500 rpm 19.42 5 10 10° 500 rpm 19.43 5 10 15° 500 rpm 18.84

[0045] In combination Figure 6 As shown in the figure, between the two adjacent folds is a fold line segment, and the length is as Figure 6L as shown in the table above; two adjacent fold line segments form a folding unit S. From the experimental data in the table above, it can be found that when there is an angle of 5°-10° between the fold line segment and the connecting line D of adjacent valleys, the air volume of the volute is increased compared to the case without the fold angle at the same rotational speed. However, when the fold angle θ is further increased, the air volume shows a decreasing trend. This is because when the appropriate angle feature is set at the outlet 102 of the air duct, a vortex structure is formed that is conducive to the flow of air, so that the air flow rate near the ring wall 1 at the outlet 102 of the air duct is increased, the boundary layer thickness is reduced, the fluid is more easily separated from the wall, the separation phenomenon of the flow is improved, the boundary layer thickness is reduced, and thus the flow rate is increased; when the angle is further increased to more than 15°, the excessive angle increases the strength of the backflow vortex, increases the flow resistance, and thus the overall flow rate at the outlet 102 of the air duct is decreased, and the flow rate of the volute is reduced. Therefore, preferably, the fold angle is 5°-10°.

[0046] The length of the fold line segment also has an important influence on the air flow performance. When the length difference between the first volute profile and the second volute profile is determined, the number of folding units S is different, and the length of the corresponding fold line segment is different. When the number of folding units S is large, the length of each fold line segment is short.

[0047] The actual test results of some specific embodiments are shown in the following table.

[0048] Number of cells N Pitch L Crease inclination angle Θ Rotational speed Outlet air volume (m 3 / min) 5 10 10° 500 rpm 19.43 8 7.1 10° 500 rpm 20.21 12 5.4 10° 500 rpm 20.20 18 4.3 10° 500 rpm 19.96

[0049] As can be seen from the above table, when the fold angle θ is constant, the number of folding units S is 8-12, and the fold angle interval, i.e. the length L of the fold line segment, is 5-7, the outlet air volume is large. Therefore, preferably, the length of the fold line segment is 5mm-7mm. The interval L data in the table is calculated according to the following formula when the length difference between the first volute profile and the second volute profile is 78mm, the fold angle coefficient K1 is 0.99, and the bending coefficient K2 is 2, and different N is taken:

[0050]

[0051] The formula will be described below.

[0052] Please refer to Figure 4 and Figure 6 The design method of the above-mentioned volute 100 is as follows:

[0053] Determine the length difference ΔC between the first volute profile and the second volute profile and the folding space interval P between the first volute profile and the second volute profile;

[0054] The length L of the broken line segment of the folding unit S is determined based on the folding space spacing P, and the length L of the broken line segment is less than the folding space spacing P.

[0055] Calculate the number N of folding units S based on the length difference ΔC and the length L of the broken line segment; and

[0056] A section of the annular wall 1 is folded to form a bent portion 13 using the length L and quantity N of the folded segment;

[0057] The portion between two adjacent peaks or two adjacent troughs constitutes one folding unit S.

[0058] like Figure 6 As shown, a folded unit S is a segment of a corrugated section containing a complete crest or a complete trough; the corrugated section is formed by the repeated extension of multiple folded units S. The folded space refers to the space where the annular wall 1 can move vertically. For example... Figure 6 As shown, in one embodiment, the first support 21 defines the upper limit position of the movement of the ring wall 1, and the second support 22 defines the lower limit position of the movement of the ring wall 1. Then, the folding space is the space between the lower surface of the first support 21 and the upper surface of the second support 22. The folding space spacing P is the vertical distance of the folding space, that is, the distance between the lower surface of the first support 21 and the upper surface of the second support 22.

[0059] The length L of the folded segment is the distance between two adjacent bending points, or in other words, the width of the portion between two adjacent creases. Since the bending portion 13 needs to be folded within the folding space, the length L of the folded segment formed by the bending portion 13 cannot be greater than the folding space spacing P. Generally speaking, based on the consideration of processing convenience, if the folding space size allows, the solution with fewer folds will be preferred. Therefore, if the length L of the folded segment is less than the folding space spacing P, a longer folded segment length L is preferred. At the same time, considering the folding performance of the metal material, in this embodiment, the length L of the folded segment is 0.6 to 0.8 of the folding space spacing P.

[0060] In one embodiment, the design method proceeds as follows.

[0061] First, the optimal volute profile for different working conditions has been obtained through theoretical calculations and testing. For example, the volute profile A with the lowest noise in the semi-anechoic chamber and the volute profile B with the lowest working noise have been obtained. The perimeter Ca of volute profile A and the perimeter Cb of volute profile B can be obtained through mathematical methods. Then, the length change distance that the bending part 13 needs to be able to achieve, that is, the length difference ΔC = Ca - Cb, is required. When the bending part 13 is composed of N folding units S, each folding unit S must be able to achieve a length change of ΔC / N.

[0062] When the annular wall 1 is in its longest state, that is, when the bent portion 13 is fully extended and flat, each folding unit S is at its maximum length L. max Maximum length L max The length L is twice the length of the broken line segment; considering that the crease usually prevents the ring wall 1 from being completely straightened, a crease coefficient K1 is added, preferably 0.95 to 0.99; then the maximum length L of the folded unit S is... max It can be expressed as follows: L min =2*K1*L.

[0063] like Figure 6 As shown, when the annular wall 1 is in its shortest state, that is, when the folding units S included in the bending part 13 are close to each other, each folding unit S is at its shortest length L. min The shortest length L min It is twice the wall thickness t of the annular wall, plus twice the minimum bending diameter d. That is: L min = 2t + 2d; where the minimum bending diameter d of the sheet metal part is usually proportional to the wall thickness of the ring wall 1, that is: d = K2 * t, where K2 is the bending coefficient, which is usually taken as 1 to 3. In one embodiment, the wall thickness t of the ring wall 1 is preferably 0.5 mm to 1 mm.

[0064] Therefore, the length difference ΔL of each folded unit S in its longest and shortest states satisfies:

[0065] ΔL=L max -L min =2*K1*L-2t-2*K2*t=2*(K1*L-(1+K2)*t); then ΔC=N*ΔL=2*N*(K1*L-(1+K2)*t).

[0066] Considering ease of processing, and to reduce the number of bends, a longer fold line segment length L is preferred, provided that the fold line segment length L is less than the folding space spacing P. Considering the folding performance of the metal material, the relationship between the fold line segment length L and the folding space spacing P is expressed as follows: L = K3 * P; where K3 is a folding coefficient added to consider the folding performance of the metal, which is preferably 0.6 to 0.8.

[0067] Substituting the above formula into the equation, we can calculate the number of folding units N, i.e.:

[0068]

[0069] Since N should be a positive integer, its value calculated using the above formula can be rounded up. Based on this formula, the calculation formula for the bending line length L can be obtained by modification.

[0070] The following is a specific experimental data to calculate the reasonable design parameters of the bending part 13. The circumference Ca of the volute profile A is 1000mm, the circumference Cb of the volute profile B is 900mm, the distance P between the first support part 21 and the second support part 22 at the end of the volute is 20mm, the wall thickness t of the ring wall 1 is 0.7mm, the crease coefficient K1 is 0.95, the bending coefficient K2 is 2, and the folding coefficient K3 is 0.75; the number N of the folding units S is calculated to be 4.12 by bringing the above formula, and the number N is rounded up to 5; the length L of the fold line segment is calculated by bringing the formula again according to the rounded number N, and the length L of the fold line segment is 12.7mm.

[0071] As can be known from the above description of the specific embodiments, the volute 100 provided by the present application has a bending part 13 formed by a plurality of fold line segments connected at the end 12 of the ring wall 1, when the ring wall 1 defines a first volute profile, the bending part 13 extends in a wave shape, the crease angle is formed between the fold line segment and the line connecting adjacent valleys in the bending part 13, and the crease angle is not greater than 15°; by providing a bending part 13 at the end of the ring wall 1, the fold line segment in the bending part 13 has a reasonable crease angle when the ring wall 1 defines a first volute profile, which can guide the airflow to form a beneficial vortex structure, so that the airflow speed near the ring wall 1 at the air outlet of the volute 100 is increased, the boundary layer thickness is reduced, the fluid is more easily separated from the wall surface, the separation phenomenon of the fluid is improved, and the air flow rate is increased.

[0072] The present application also provides a centrifugal fan, which comprises the volute 100 described above and a fan arranged in the volute 100.

[0073] The present application also provides an extractor hood, which comprises the centrifugal fan described above.

[0074] The centrifugal fan and the extractor hood provided by the present application have the beneficial effects of the above-mentioned volute 100.

[0075] The technical features of the above-described embodiments can be combined in any manner, and in order to make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not exist, they should be considered as the scope of the present application.

[0076] The above-described embodiments only express several implementation manners of the present application, the description is more specific and detailed, but it should not be understood as a limitation on the patent protection scope of the present application. It should be pointed out that for ordinary skilled persons in the art, some modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. A volute comprising a ring wall defining a volute profile, the ring wall having a start end located upstream and an end located downstream in a flow path of an air flow; characterized in that the ring wall has a bending portion formed by a plurality of bending line segments connected near the end, wherein the bending portion extends in a wave shape when the ring wall defines a first volute profile, a bending angle is formed between the bending line segment and a line connecting adjacent valleys in the bending portion, and the bending angle is not greater than 15°; and the bending portion is switchable between an extended state and a folded state, the bending portion is in the extended state when the ring wall defines the first volute profile.

2. The volute of claim 1, wherein The bending angle is 5°-10°.

3. The volute of claim 1, wherein, The length of the bending line segment is 5mm-7mm.

4. The volute of claim 1, wherein, The volute comprises a first support portion located above the ring wall, the first support portion supports the ring wall when the ring wall defines the first volute profile, and the first support portion is provided with a wave shape structure matching the bending portion.

5. The volute of claim 1, wherein, The bending line segment is perpendicular to the line connecting adjacent valleys in the bending portion when the bending portion is in the folded state.

6. The volute of claim 1, wherein, The ring wall defines a second volute profile when the bending portion is in the folded state, the first volute profile is longer than the second volute profile, and the end position of the first volute profile is higher than the end position of the second volute profile.

7. The volute of claim 1, wherein The volute comprises side walls located on both sides of the ring wall, the side walls and the ring wall enclose an air duct, the air duct has an air duct outlet, and the side walls are provided with a limiting groove defining the end position of the ring wall near the air duct outlet.

8. The volute of claim 7, wherein, The limiting groove is an elongated slot extending in the up-down direction, and the ring wall is provided with a protrusion slidingly fitted with the limiting groove; wherein the protrusion slides to the lower part of the limiting groove, the bending portion is extruded into the folded state, and the protrusion slides to the upper part of the limiting groove, the bending portion is stretched into the extended state.

9. The volute of claim 1, wherein, The volute comprises a push rod, the push rod exerts a force on the ring wall to switch the bending portion between the extended state and the folded state.

10. A centrifugal fan characterized by A centrifugal fan comprising a fan and a volute as claimed in any one of claims 1 to 9.

11. A range hood characterized by, A centrifugal fan as claimed in claim 10.

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