Volute, centrifugal fan and range hood

Abstract

The application relates to the technical field of range hoods, and provides a volute, a centrifugal fan and a range hood. The profile of the volute comprises first, second, third and fourth profile segments connected in sequence, and the two profile segments connected in sequence are smoothly connected. The third profile segment constitutes the main body of the volute, the second profile segment constitutes the volute tongue of the volute, and the third profile segment is located on a logarithmic spiral curve. Since the logarithmic spiral curve where the third profile segment is located is an arc segment generated with the same center, the curvature of the third profile segment is continuous, and the radial gap between the logarithmic spiral curve and the reference circle is gradually increased through the design of the reference circle. Therefore, the change of the polar radius of the third profile segment is continuous, the error of the profile of the volute is reduced, the vortex in the volute can be prevented to reduce the noise of the volute, the gas in the volute can be more concentrated, and the smoke exhaust efficiency of the volute is improved.

Description

TECHNICAL FIELD

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

[0002] In the related art, the volute profile is designed by using four arcs with different centers. In this process, since the arc radius is positively correlated with the impeller speed, the larger the impeller speed, the larger the error of the volute profile. Thus, the volute profile does not match the impeller, resulting in low smoke exhaust efficiency of the volute and high noise. Meanwhile, in the method of generating the volute profile, the arc radius of adjacent arcs changes greatly, which causes vortex in the volute, greatly reduces the air volume, air pressure and efficiency of the fan, and forms a large pressure gradient in the volute, thereby increasing the vortex noise. SUMMARY

[0003] Therefore, it is necessary to provide a volute, centrifugal fan and range hood to improve the smoke exhaust efficiency of the volute and reduce the noise of the volute.

[0004] According to one aspect of the present application, an embodiment of the present application provides a volute, a profile of the volute comprising a first profile segment, a second profile segment, a third profile segment and a fourth profile segment connected in sequence, the two profile segments being smoothly connected; the third profile segment constitutes a main body of the volute, the second profile segment constitutes a volute tongue of the volute, the first profile segment and the fourth profile segment constitute an air outlet of the volute, and the third profile segment is located on a logarithmic spiral curve.

[0005] The third profile segment is tangent to the first tangent point with the second profile segment, and the third profile segment is tangent to the second tangent point with the fourth profile segment. The direction from the first tangent point to the second tangent point along the third profile segment is a first path direction. A reference circle is defined as a circle with the pole of the logarithmic spiral curve as the center and the radius r of the impeller located in the volute as the radius. The logarithmic spiral curve intersects with the reference circle at a first intersection point. A radial gap is formed between the outline of the reference circle and the logarithmic spiral curve located between the first intersection point and the second tangent point.

[0006] In the first path direction, the radial gap gradually increases, and the curvature of the third profile segment is continuous.

[0007] The third type line segment is continuous in curvature, and the radial gap between the logarithmic spiral curve and the reference circle is gradually increased through the design of the reference circle, so that the change of the polar radius of the third type line segment is continuous, the error of the volute profile is reduced, the vortex in the volute is prevented to reduce the noise of the volute, and the gas in the volute is more concentrated to improve the exhaust efficiency of the volute.

[0008] In one of the embodiments, the line between the pole point and the first tangent point intersects the outline of the reference circle at a second intersection point, and the length of the line between the second intersection point and the first tangent point is d1; wherein the ratio of r to d1 is 5.73-8.8. In this way, the distance between the third type line segment and the reference circle is limited, that is, the minimum distance between the volute tongue and the matched impeller is limited, that is, the minimum distance between the volute and the matched impeller is limited, so as to prevent wind noise at the volute tongue due to fluid diversion, and to avoid the wind noise being transmitted to the outside through the volute tongue to affect the user's experience.

[0009] In one of the embodiments, the second type line segment is a circular arc. In this way, the wind resistance at the volute tongue can be reduced through the circular arc shape.

[0010] In one of the embodiments, the radius of the circular arc of the second type line segment is R; wherein the ratio of r to R is 7.33-10.15. In this way, the size of the circular arc radius of the second type line segment is limited, that is, the size of the volute tongue corner is limited, and the wind noise at the volute tongue can be further reduced.

[0011] In one of the embodiments, the line between the pole point of the logarithmic spiral curve and the arc center of the second type line segment is a first line, and the included angle between the line between the pole point and the first intersection point and the first line is a1; wherein 76°≤a1≤86°. In this way, the length of the circular arc of the second type line segment can be limited, and a volute tongue with a preset shape can be constructed to further improve the dynamic characteristics of the fluid flowing through the volute tongue.

[0012] In one of the embodiments, the fourth type line segment is a straight line, and the included angle between the fourth type line segment and the line between the pole point and the first intersection point is a2; wherein 80°≤a2≤90°. In this way, a reasonable volute diffuser angle can be obtained to prevent the gas in the volute from flowing back to the inside of the volute, thereby improving the exhaust efficiency.

[0013] In one of the embodiments, the length of the line between the first intersection point and the second tangent point is d2; wherein the ratio of r to d2 is 1.38-1.56. In this way, the third type line segment can be limited, and the curvature of the third type line segment can be limited, thereby further reducing the error of the volute profile.

[0014] In one of the embodiments, the equation of the logarithmic spiral curve is:

[0015]

[0016] wherein r is the radius of the impeller, e is the base of the natural logarithm, a is the back flow angle of the blade of the impeller, b is the outlet width of the impeller, B is the height of the volute, is the angle between the polar radius of the logarithmic spiral curve and the line connecting the pole point and the first intersection point, is the correction value of R. In this way, by setting the correction value, the spiral curve is corrected, and the error of the volute profile can be reduced.

[0017] In one of the embodiments, the maximum rotating speed of the impeller is 800 r / min-1000 r / min, and l is 10 mm-15 mm.

[0018] The maximum rotating speed of the impeller is 600 r / min-800 r / min, and l is 5 mm-10 mm. In this way, the correction can be made in different degrees according to the impellers with different rotating speeds.

[0019] According to another aspect of the present application, the embodiments of the present application provide a centrifugal fan, comprising an impeller and the volute as described above.

[0020] The impeller is arranged in the volute, and the center of the impeller coincides with the pole point of the logarithmic spiral curve. In this way, the centrifugal fan can have high smoke exhaust efficiency and low noise.

[0021] In one of the embodiments, the number of blades of the impeller is 64-70. In this way, the volute profile can be more matched with the impeller, the smoke exhaust efficiency of the volute can be improved, and the noise can be reduced.

[0022] According to still another aspect of the present application, the embodiments of the present application provide a range hood, comprising the centrifugal fan as described above. In this way, the range hood can have high smoke exhaust efficiency and low noise.

[0023] Additional aspects and advantages of the embodiments of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a schematic diagram of the volute profile in an embodiment of the related art;

[0025] Figure 2 is a schematic diagram of the volute profile in another embodiment of the related art;

[0026] Figure 3 A structural schematic view of a volute in an embodiment of the present application;

[0027] Figure 4 A sectional structural schematic view of a volute in an embodiment of the present application;

[0028] Figure 5 A schematic view of a volute profile in an embodiment of the present application;

[0029] Figure 6 A schematic view of a volute profile in an embodiment of the present application; Figure 5 A local enlarged schematic view of a second profile segment in an embodiment of the present application;

[0030] Figure 7 A structural schematic view of a volute profile in an embodiment of the present application;

[0031] Figure 8 A sound pressure nephogram schematic view of a volute provided in an embodiment of the present application;

[0032] Figure 9 A sound pressure nephogram schematic view of a volute provided in another embodiment of the present application;

[0033] Figure 10 A sound pressure nephogram schematic view of a volute provided in another embodiment of the present application.

[0034] Element symbol simple explanation:

[0035] First profile segment L1, second profile segment L2, third profile segment L3, fourth profile segment L4, first connecting line L5, second connecting line L6;

[0036] Pole point O, reference circle P, radial gap t;

[0037] First tangent point T1, second tangent point T2, third tangent point T3;

[0038] First intersection point C1, second intersection point C2;

[0039] Volute tongue 100, air outlet 200, volute upper plate 300, volute bottom plate 400, volute surrounding plate 500, air inlet 600, air guide ring 700;

[0040] Impeller 20;

[0041] Motor 30. DETAILED DESCRIPTION

[0042] To make the above objectives, features and advantages of the present application more clear and comprehensible, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. It will be apparent, however, to one skilled in the art, that the specific embodiments described herein can be practiced without these specific details. In other instances, well-known methods have not been described in detail in order to avoid unnecessarily obscuring the present application. Therefore, the specific embodiments described herein are not intended to limit the present application, but rather the embodiments are to serve as examples of the present application.

[0043] It can be understood that the terms "first", "second", "third", "fourth" and the like in the description of the present application can be used to describe various technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. However, unless otherwise specified, these technical features are not limited by these terms. These terms are only used to distinguish one technical feature from another. For example, without departing from the scope of the present application, the first type of line segment, the second type of line segment, the third type of line segment and the fourth type of line segment are different line segments, and the first point of intersection, the second point of intersection and the third point of intersection are different points of intersection. In the description of the embodiments of the present application, the meaning of "a plurality of" and "several" is at least two, for example, two, three, etc., unless otherwise explicitly specified.

[0044] In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood in a broad sense, for example, can be fixedly connected, or can be detachably connected, or can be integrated; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium, or can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0045] In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the first feature "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature "above", "over" and "on" the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than the horizontal height of the second feature. The first feature "below", "under" and "under" the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than the horizontal height of the second feature.

[0046] It is to be noted that when an element is referred to as being "fixed" or "set" on another element, it can be directly on the other element or there can be an intervening element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or there can be an intervening element.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0048] The centrifugal volute is one of the core components of the range hood, which can concentrate the gas near the volute inlet, and drive the impeller to rotate through the driving motor, so as to discharge the gas from the volute outlet. In this process, the profile of the centrifugal volute not only determines the shape of the volute, but also has an influence on the air volume, air pressure, efficiency and noise of the range hood.

[0049] Figure 1 A schematic diagram of the volute profile in an embodiment of the related art is shown; Figure 2 A schematic diagram of the volute profile in another embodiment of the related art is shown; only the part related to the embodiment in the related art is shown for ease of description.

[0050] Please refer to Figure 1 and Figure 2 In the related art, the volute profile is composed of multiple arc shapes, and a volute profile is usually generated by using four arcs with different centers. Thus, the curve has four arc radii R1, R2, R3 and R4. The inventors have noticed that the change of the arc radii of adjacent arcs is large, which can cause vortex in the volute, greatly reduce the air volume, air pressure and efficiency of the fan, and form a large pressure gradient in the volute, thereby increasing the vortex noise. In addition, since the arc radius is positively correlated with the speed of the impeller, the larger the speed of the impeller, the larger the error of the volute profile. Thus, the volute profile does not match the impeller, resulting in low smoke exhaust efficiency and high noise of the volute.

[0051] Based on the above considerations, the inventors have designed a volute through limiting the shape of the volute profile, which can improve the smoke exhaust efficiency of the volute and reduce the noise of the volute. The volute provided by the embodiments of the application is described in relation to the description of some embodiments.

[0052] The volute disclosed by the embodiments of the present application can be used in a centrifugal fan, and the centrifugal fan can be used in an extractor hood or other wind power systems requiring the air duct structure formed by the volute. The following describes the specific structure of the volute in some embodiments, but is not limited thereto. It should be noted that the profile of the volute disclosed by the embodiments of the present application can be in a clockwise direction or in an anticlockwise direction, which can be selected according to the use, and the embodiments of the present application do not make specific limitations thereto.

[0053] Figure 3 A structural schematic diagram of the volute in an embodiment of the present application is shown. Figure 4 A sectional structural schematic diagram of the volute in an embodiment of the present application is shown. Only the parts related to the embodiments of the present application are shown for the convenience of description.

[0054] For the convenience of understanding, as shown in Figure 4 , the upward direction of the drawing is defined as the upper side, the downward direction of the drawing is defined as the lower side, the leftward direction of the drawing is defined as the left side, the rightward direction of the drawing is defined as the right side, the leftward direction of the drawing is defined as the front side, and the rightward direction of the drawing is defined as the rear side. The definitions of the remaining diagrams are consistent with Figure 4 . It can be understood that the above definitions are only for the convenience of description and cannot be understood as limitations on the present application. It can be understood that the above definitions are only for the convenience of description and cannot be understood as limitations on the present application.

[0055] Please refer to Figure 3 and Figure 4 , an embodiment of the present application provides a volute, which comprises a volute upper plate 300, a volute bottom plate 400 and a volute enclosure plate 500. The volute upper plate 300 is provided with an air inlet 600. The volute bottom plate 400 is arranged in a spaced manner with the volute upper plate 300, and the volute bottom plate 400 is provided with a mounting hole for mounting a motor 30. The volute enclosure plate 500 is connected between the volute upper plate 300 and the volute bottom plate 400, and the volute enclosure plate 500, the volute upper plate 300 and the volute bottom plate 400 form a containing space and an air outlet 200 at the rear side. The air inlet 600, the mounting hole (not shown in the figure) and the air outlet 200 are communicated with the containing space. The containing space is used to contain an impeller 20. The volute enclosure plate 500 is formed with a volute tongue 100 on one side close to the air outlet 200. The volute tongue 100 is used to split the airflow at the outlet of the volute, and the flow field at the volute tongue 100 is relatively complex. The volute tongue 100 is also a place where noise of the centrifugal volute is generated.

[0056] The following describes the profile of the volute by taking the structure of the volute in some embodiments as an example.

[0057] Figure 5 A schematic diagram of the profile of the volute in an embodiment of the present application is shown. Figure 6 AFigure 5 A local enlarged schematic view of the second type line segment L2; only parts relevant to the embodiments of the present application are shown for ease of illustration.

[0058] Please refer to Figure 5 and Figure 6 The embodiments of the present application provide a volute, the type line of which comprises a first type line segment L1, a second type line segment L2, a third type line segment L3 and a fourth type line segment L4 connected in sequence. The two type line segments connected in sequence are smoothly connected. The third type line segment L3 constitutes the main body of the volute, the second type line segment L2 constitutes the volute tongue 100, the first type line segment L1 and the fourth type line segment L4 constitute the air outlet 200 of the volute, and the third type line segment L3 is located on a logarithmic spiral curve.

[0059] The third type line segment L3 is tangent to the first type line segment L1 at a first tangent point T1, and the third type line segment L3 is tangent to the fourth type line segment L4 at a second tangent point T2. The direction from the first tangent point T1 to the second tangent point T2 along the third type line segment L3 is a first path direction. A reference circle P is defined as a circle with the pole point O of the logarithmic spiral curve as the center and the radius r of the impeller 20 located in the volute as the radius. The logarithmic spiral curve intersects the reference circle P at a first intersection point C1. The outline of the reference circle P and the logarithmic spiral curve located between the first intersection point C1 and the second tangent point T2 form a radial gap t. In the first path direction, the radial gap t gradually increases, and the curvature of the third type line segment L3 is continuous. That is, the difference between the polar radius of the logarithmic spiral curve and the radius of the impeller 20 gradually increases in the first path direction. For example, the first path direction is the clockwise direction along the third type line segment L3. Figure 5

[0060] It should be noted that the "main body of the volute" refers to the part corresponding to the volute shroud 500 after the impeller 20 is placed in the volute. The volute shroud 500 is curved to form a shape suitable for the impeller 20. Correspondingly, the shape of the volute upper plate 300 and the volute bottom plate 400 at this part is also suitable for the volute shroud 500. The "radial gap t" changes from zero at the first intersection point C1 and ends at the position corresponding to the second tangent point T2.

[0061] ​Since the logarithmic spiral curve where the third type line segment L3 is located is an arc segment generated with the same center, the curvature of the third type line segment is continuous, and at the same time, by designing the reference circle P, the radial gap t between the logarithmic spiral curve and the reference circle P is gradually increased, so that the change of the polar radius of the third type line segment L3 is continuous. That is, by jointly constraining the construction of the third type line segment L3 through the radial gap t and the curvature of the third type line segment L3, the third type line segment L3 is smoother, the change of the polar radius of the third type line segment L3 is continuous, the error of the volute profile is reduced, not only can prevent the generation of eddy current in the volute to reduce the noise of the volute, but also can make the gas in the volute more concentrated, and improve the exhaust efficiency of the volute.

[0062] In some embodiments, please continue to refer to Figure 5 and Figure 6 The line between the pole point O and the first tangent point T1 intersects the outline of the reference circle P at a second intersection point C2, and the length of the line between the second intersection point C2 and the first tangent point T1 is d1. Wherein, the ratio of r to d1 is 5.73-8.8. In this way, the distance between the third type line segment L3 and the reference circle P can be limited, that is, the minimum distance between the volute tongue 100 of the volute and the impeller 20 matched therewith can be limited, that is, the minimum distance between the volute and the impeller 20 matched therewith. The volute tongue 100 can prevent part of the gas from circulating in the volute. When the gas flow at the outlet of the blade passage of the impeller 20 flows near the volute tongue 100, the volute tongue 100 will split the gas flow, and most of the gas flow will flow to the air outlet 200 along the passage. A small part of the gas flow flows back into the volute through the gap between the volute tongue 100 and the impeller 20, and then participates in the new flow splitting after rotating with the impeller 20 for one revolution. When the gap between the volute tongue 100 and the impeller 20 is too small, although the backflow of the gas in the volute will be reduced, the gas flow to the air outlet 200 will be increased, and the wind noise will be increased. When the gap between the volute tongue 100 and the impeller 20 is too large, the gas flow to the air outlet 200 will be reduced, and the backflow of the gas in the volute will be increased, which will lead to low exhaust efficiency of the volute. Therefore, by limiting the minimum distance between the volute tongue 100 of the volute and the impeller 20 matched therewith, not only can the wind noise caused by the flow splitting at the volute tongue 100 be prevented, and the wind noise can be prevented from being transmitted to the outside through the volute tongue 100 to affect the user's experience, but also good exhaust efficiency can be obtained.

[0063] In some embodiments, please continue to refer to Figure 5 and Figure 6The second type of line segment L2 is an arc. This arc shape reduces wind resistance at the volute tongue 100. Specifically, in some embodiments, the radius of the arc of the second type of line segment L2 is R; where the ratio of r to R is 7.33-10.15. This limits the size of the radius R of the arc of the second type of line segment L2, thus limiting the size of the corner of the volute tongue 100, which not only allows for smooth airflow splitting but also further reduces wind noise at the volute tongue 100.

[0064] In some embodiments, please refer to Figure 5 and Figure 6 The line connecting the pole O of the logarithmic spiral curve and the arc center O2 of the second type segment L2 is the first connecting line L5, and the line connecting the pole O and the first intersection point C1 is the second connecting line L6. The angle between the first connecting line L5 and the second connecting line L6 is α1. Wherein, 76°≤α1≤86°. That is, the starting point for constructing the third type segment L3 is located on the reference circle P. The line segment between the starting point of the third type segment L3 and the starting point of the third type segment L3 can be removed after obtaining the starting point of the third type segment L3. This further defines the shape of the third type segment L3 to match the impeller 20 and improve the flue gas exhaust efficiency. Thus, by defining the angle between the first connecting line L5 and the second connecting line L6, not only can the arc length of the second type segment L2 be defined, and a volute tongue 100 of a preset shape be constructed to reduce wind noise, but the starting point of the third type segment L3 can also be obtained to further improve the dynamic characteristics of the fluid flowing through the volute tongue 100.

[0065] In some embodiments, please refer to Figure 5 The fourth type line segment L4 is a straight line, and the angle between the fourth type line segment L4 and the second connecting line L6 is α2. Where 80°≤α2≤90°. Figure 5 For example, the case where the included angle α2 is 90° is illustrated. In this way, a reasonable volute diffusion angle can be obtained, preventing gas inside the volute from flowing back into the volute and improving exhaust efficiency.

[0066] In some embodiments, please refer to Figure 5 The length of the line connecting the first intersection point C1 and the second tangent point T2 is d2. The ratio of r to d2 is 1.38-1.56. That is, the first intersection point C1 is the starting point for constructing the third-type line segment L3, and the second tangent point T2 is the ending point. By limiting the distance between the starting and ending points of the third-type line segment L3, the curvature of the third-type line segment L3 can be defined, further reducing the error of the volute profile. In addition, the airflow rate towards the outlet 200 is limited, which neither affects the smoke extraction efficiency nor reduces noise.

[0067] In some embodiments, the equation of the logarithmic spiral curve is:

[0068]

[0069] wherein r is the radius of the impeller 20, e is the base of the natural logarithm, a is the back flow angle of the blade of the impeller 20, b is the outlet width of the impeller 20 (i.e. Figure 4 the height of the impeller 20 in the up-down direction), B is the height of the volute (i.e. Figure 4 the height of the volute in the up-down direction, i.e. the distance between the volute upper plate 300 and the volute bottom plate 400), is the angle between the polar radius of the logarithmic spiral curve and the second connecting line L6, is the correction value of R. In this way, by setting the correction value, the spiral curve is corrected, and the error of the volute profile can be reduced.

[0070] In some embodiments, the maximum rotating speed of the impeller 20 is 800 r / min-1000 r / min, and l is 10 mm-15 mm. In other embodiments, the maximum rotating speed of the impeller 20 is 600 r / min-800 r / min, and l is 5 mm-10 mm. In this way, the correction can be made to different degrees according to the impeller 20 with different rotating speeds.

[0071] Based on the same inventive concept, the embodiments of the present application provide a centrifugal fan, which comprises the impeller 20 and the volute in the above embodiments. The impeller 20 is arranged in the volute, and the center of the impeller 20 coincides with the pole point O of the logarithmic spiral curve. In this way, the smoke exhaust efficiency of the centrifugal fan can be high, and the noise can be low.

[0072] In some embodiments, the number of blades of the impeller 20 is 64-70. In this way, the volute profile can be more matched with the impeller 20, the smoke exhaust efficiency of the volute can be improved, and the noise can be reduced.

[0073] Based on the same inventive concept, the embodiments of the present application provide a range hood, which comprises the centrifugal fan in the above embodiments. In this way, the smoke exhaust efficiency of the range hood can be high, and the noise can be low.

[0074] Figure 7 A structure diagram of the volute profile in an embodiment of the present application is shown; for the convenience of description, only the relevant part in the embodiment of the present application is shown.

[0075] The construction method of the volute profile of the volute provided in the embodiments of the present application is exemplarily described below, please refer to Figure 7 The steps are as follows:

[0076] S100, constructing a logarithmic spiral curve: taking an arbitrary point as a pole of the logarithmic spiral curve, determining a radius r of the impeller 20, and taking the radius r of the impeller 20 as an initial radius, taking an end point A on the initial radius as a starting point of the logarithmic spiral curve, and determining a point B on the logarithmic spiral curve according to an equation of the logarithmic spiral curve forming a spiral curve S;

[0077] S200, constructing a second type line segment L2: determining the second type line segment L2 at a position with an included angle of 76°-86°, and a minimum distance between the second type line segment L2 and the reference circle P being 15mm-23mm, and a circular arc radius of the second type line segment L2 being 13mm-18mm;

[0078] S300, constructing a third type line segment L3: taking an end point of the second type line segment L2 as a starting point of the third type line segment L3, and taking a point B on the spiral curve S with a distance of 85mm-95mm from the end point A as an end point of the third type line segment L3, and the third type line segment L3 being tangent to the second type line segment L2;

[0079] S400, constructing a fourth type line segment L4: the fourth type line segment L4 being tangent to the third type line segment L3, and an included angle between the fourth type line segment L4 and the line segment OA being 80°-90°;

[0080] S500, constructing a first type line segment L1: the first type line segment L1 being tangent to the second type line segment L2 at a starting point of the second type line segment L2.

[0081] Figure 8 a sound pressure nephogram of a volute provided in an embodiment of the present application is shown; Figure 9 a sound pressure nephogram of a volute provided in another embodiment of the present application is shown; Figure 10 a sound pressure nephogram of a volute provided in another embodiment of the present application is shown; only parts related to the embodiments of the present application are shown for convenience of description.

[0082] In the above embodiments, d2=90mm, a2=90°, a circular arc radius R of the volute tongue 100 is 15mm, l=10mm, a number of blades of the impeller 20 is 64 blades, a radius r of the impeller 20 is 132mm, and the following aerodynamic simulation of the volute provided in the embodiments of the present application is performed by using the fluent simulation software of Ansys, taking the minimum distance between the volute and the outer edge of the impeller 20 (i.e. the length of the line connecting the second intersection point C2 and the first tangent point T1) as 15mm, 19mm and 23mm respectively as examples for simulation. It should be noted that, Figure 8 to Figure 10 ​In the figure, U1 represents the color corresponding to the sound pressure intensity in different regions, and U2 represents the specific sound pressure intensity in dB. Different sound pressure intensities have different colors, and the color changes as the sound pressure intensity changes. As shown in the figure, the color change is shown as a gradual transition from the cold tone to the warm tone along the clockwise direction from the volute tongue 100. As shown in the figure, the color change is shown as a gradual transition from the cold tone to the warm tone along the clockwise direction from the volute tongue 100. Figure 8 to Figure 10 As shown in the figure, the color change is shown as a gradual transition from the cold tone to the warm tone along the clockwise direction from the volute tongue 100. Figure 8 to Figure 10 As shown in the figure, the color change is shown as a gradual transition from the cold tone to the warm tone along the clockwise direction from the volute tongue 100. Figure 8 As shown in the figure, the color change is shown as a gradual transition from the cold tone to the warm tone along the clockwise direction from the volute tongue 100. As shown in the figure, the color change is shown as a gradual transition from the cold tone to the warm tone along the clockwise direction from the volute tongue 100. Figure 9 As shown in the figure, the color change is shown as a gradual transition from the cold tone to the warm tone along the clockwise direction from the volute tongue 100. As shown in the figure, the color change is shown as a gradual transition from the cold tone to the warm tone along the clockwise direction from the volute tongue 100. Figure 10 As shown in the figure, the color change is shown as a gradual transition from the cold tone to the warm tone along the clockwise direction from the volute tongue 100. As shown in the figure, the color change is shown as a gradual transition from the cold tone to the warm tone along the clockwise direction from the volute tongue 100.

[0083] As shown in the figure, the color change is shown as a gradual transition from the cold tone to the warm tone along the clockwise direction from the volute tongue 100.

[0084] The technical features of the above embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above embodiments are described, but as long as the combinations of the technical features do not contradict, they should be considered as within the scope of the present disclosure.

[0085] The above-described embodiments are merely illustrative of several embodiments of the present application, which are described in more detail and in a specific manner, but should not be construed as limiting the scope of the patent. It should be noted that for those skilled in the art, several 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 protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A volute, characterized in that, The spiral casing includes sequentially connected first line segment (L1), second line segment (L2), third line segment (L3) and fourth line segment (L4), and two connected line segments are smoothly connected; the third line segment (L3) constitutes the main body of the spiral casing, the second line segment (L2) constitutes the spiral tongue (100) of the spiral casing, the first line segment (L1) and the fourth line segment (L4) constitute the air outlet (200) of the spiral casing, and the third line segment (L3) is located on a logarithmic spiral curve; The third line segment (L3) is tangent to the first tangent point (T1) of the second line segment (L2), the third line segment (L3) is tangent to the second tangent point (T2) of the fourth line segment (L4), and the direction from the first tangent point (T1) to the second tangent point (T2) along the third line segment (L3) is a first path direction; a reference circle (P) is defined as a circle with the pole point (O) of the logarithmic spiral curve as the center and the radius r of the impeller (20) located in the spiral casing as the radius, the logarithmic spiral curve intersects the reference circle (P) at a first intersection point (C1), and a radial gap (t) is formed between the outline of the reference circle (P) and the logarithmic spiral curve located between the first intersection point (C1) and the second tangent point (T2); Wherein, in the first path direction, the radial gap (t) gradually increases, and the curvature of the third line segment (L3) is continuous; the difference between the polar radius of the logarithmic spiral curve and the radius of the impeller (20) gradually increases in the first path direction; The equation of the logarithmic spiral curve is: ； wherein r is a radius of the impeller (20), e is a base of a natural logarithm, a is a back flow angle of a blade of the impeller (20), b is an outlet width of the impeller (20), B is a height of the volute, is an angle between a polar radius of the logarithmic spiral curve and a line connecting the pole point (O) and the first intersection point (C1), is a correction value of R; the maximum rotating speed of the impeller (20) is 800 r / min-1000 r / min, and l is 10 mm-15 mm; the maximum rotating speed of the impeller (20) is 600 r / min-800 r / min, and l is 5 mm-10 mm; The line connecting the pole point (O) and the first tangent point (T1) intersects the outline of the reference circle (P) at a second intersection point (C2), the length of the line connecting the second intersection point (C2) and the first tangent point (T1) is d1, and the ratio of r to d1 is 5.73-8.8; the second line segment (L2) is a circular arc, the radius of the circular arc of the second line segment (L2) is R, and the ratio of r to R is 7.33-10.

15.

2. The volute of claim 1, wherein The line connecting the pole point (O) of the logarithmic spiral curve and the arc center (O2) of the second line segment (L2) is a first line (L5), and the angle between the line connecting the pole point (O) and the first intersection point (C1) and the first line (L5) is α1; Wherein, 76°≤α1≤86°.

3. A volute according to claim 1 or 2, characterised in that The fourth line segment (L4) is a straight line, and the angle between the fourth line segment (L4) and the line connecting the pole point (O) and the first intersection point (C1) is α2; Wherein, 80°≤α2≤90°.

4. The volute according to claim 1 or 2, characterized in that The length of the line connecting the first intersection point (C1) and the second tangent point (T2) is d2; Wherein, the ratio of r to d2 is 1.38-1.

56.

5. A centrifugal fan characterized by The impeller (20) and the spiral casing according to any one of claims 1-4 are included; Wherein, the impeller (20) is arranged in the spiral casing, and the center of the impeller (20) is coincident with the pole point (O) of the logarithmic spiral curve.

6. The centrifugal fan of claim 5, wherein The number of blades of the impeller (20) is 64-70.

7. A range hood characterized by, A centrifugal fan comprising a centrifugal fan as claimed in claim 5 or 6.

Images