CN114483653A

CN114483653A - Volute, centrifugal fan and range hood

Info

Publication number: CN114483653A
Application number: CN202111581138.1A
Authority: CN
Inventors: 卢宇轩; 周骏尧
Original assignee: Guangdong Vanward New Electric Co Ltd
Current assignee: Guangdong Vanward New Electric Co Ltd
Priority date: 2021-12-22
Filing date: 2021-12-22
Publication date: 2022-05-13

Abstract

The application relates to the technical field of range hoods, and the embodiment of the application provides a volute, a centrifugal fan and a range hood. The molded line of the volute comprises a first molded line segment, a second molded line segment, a third molded line segment and a fourth molded line segment which are connected in sequence, and the two connected molded line segments are in smooth transition. The third molded line section forms a main body of the volute, the second molded line section forms a volute tongue of the volute, and the third molded line section is located on the logarithmic spiral curve. The logarithmic spiral curve where the third molded line segment is located is an arc line segment generated by the same circle center, the curvature of the third molded line segment is continuous, and meanwhile, the radial clearance between the logarithmic spiral curve and the reference circle is gradually increased by designing the reference circle, so that the change of the polar radius of the third molded line segment is continuous, the molded line error of the volute is reduced, vortex can be prevented from being generated in the volute to reduce the noise of the volute, gas in the volute can be concentrated, and the smoke exhaust efficiency of the volute is improved.

Description

Volute, centrifugal fan and range hood

Technical Field

The application relates to the technical field of range hoods, in particular to a volute, a centrifugal fan and a range hood.

Background

In the related art, the volute profile design mostly adopts four arcs with different circle centers to generate the volute profile. In the process, the arc radius is positively correlated with the rotating speed of the impeller, so that the wind wheel speed is higher, and the error of the volute profile is higher. So, make the spiral case molded lines and impeller mismatch, cause the spiral case to discharge fume inefficiency, the noise is high. Meanwhile, in the method for generating the volute profile, the change of the arc radius of the adjacent arcs is large, so that vortices are generated in the volute, the air volume, the air pressure and the efficiency of the fan are greatly reduced, a large pressure gradient is formed in the volute, and the vortex noise is increased.

Disclosure of Invention

Accordingly, it is desirable to provide a volute, a centrifugal fan and a range hood to improve the smoke discharging efficiency of the volute and reduce the noise of the volute.

According to one aspect of the present application, the embodiment of the present application provides a volute, wherein a profile of the volute includes a first profile segment, a second profile segment, a third profile segment and a fourth profile segment which are connected in sequence, and a smooth transition is formed between the two connected profile segments; the third molded line segment forms a main body of the volute, the second molded line segment forms a volute tongue of the volute, the first molded line segment and the fourth molded line segment form an air outlet of the volute, and the third molded line segment is positioned on a logarithmic spiral curve;

the third section line and the second section line are tangent to a first tangent point, the third section line and the fourth section line are tangent to a second tangent point, and the direction from the first tangent point to the second tangent point along the third section line is a first path direction; defining a circle obtained by taking the pole of the logarithmic spiral curve as the center of a circle and the radius r of the impeller positioned in the volute as the radius as a reference circle, wherein the logarithmic spiral curve and the reference circle are intersected at a first intersection point, and a radial gap is formed between the outline of the reference circle and the logarithmic spiral curve positioned between the first intersection point and the second intersection point;

wherein, in the first path direction, the radial gap gradually increases, and the curvature of the third type line segment is continuous.

In the volute, the logarithmic spiral curve where the third molded line segment is located is an arc segment generated by the same circle center, the curvature of the third molded line segment is continuous, and meanwhile, the radial clearance between the logarithmic spiral curve and the reference circle is gradually increased by designing the reference circle, so that the change of the polar radius of the third molded line segment is continuous, the error of the molded line of the volute is reduced, the vortex generated in the volute can be prevented to reduce the noise of the volute, the gas in the volute can be concentrated, and the smoke exhaust efficiency of the volute is improved.

In one embodiment, a connecting line between the polar point and the first tangent point intersects with the outline of the reference circle at a second intersection point, and the length of the connecting line between the second intersection point and the first tangent point is d 1; wherein the ratio of r to d1 is 5.73-8.8. Therefore, the distance between the third profile line segment and the reference circle can be defined, namely, the minimum distance between the volute tongue of the volute and the matched impeller is defined, namely, the minimum distance between the volute and the matched impeller is defined, wind noise caused by fluid shunting at the volute tongue is prevented, and the phenomenon that the wind noise is transmitted to the outside through the volute tongue to influence the use feeling of a user is avoided.

In one embodiment, the second profile segment is a circular arc. Therefore, the wind resistance at the volute tongue can be reduced through the arc shape.

In one embodiment, the arc radius of the second profile segment is R; wherein the ratio of R to R is 7.33-10.15. Therefore, the size of the arc radius of the second profile line segment, namely the size of the corner of the volute tongue can be limited, and the wind noise at the volute tongue can be further reduced.

In one embodiment, a connection line between a pole of the logarithmic spiral curve and an arc center of the second type line segment is a first connection line, and an included angle between a connection line between the pole and the first intersection point and the first connection line is α 1; wherein alpha 1 is more than or equal to 76 degrees and less than or equal to 86 degrees. Therefore, the arc length of the second profile segment can be limited, and the volute tongue with the preset shape can be constructed, so that the dynamic characteristic of the fluid flowing through the volute tongue is further improved.

In one embodiment, the fourth line segment is a straight line, and an included angle between the fourth line segment and a connecting line between the pole and the second intersection point is α 2; wherein alpha 2 is more than or equal to 80 degrees and less than or equal to 90 degrees. Therefore, a reasonable volute diffusion angle can be obtained, gas in the volute is prevented from flowing back to the inside of the volute, and the exhaust efficiency is improved.

In one embodiment, the length of a connecting line between the first intersection point and the second tangent point is d 2; wherein the ratio of r to d2 is 1.38-1.56. Therefore, the third profile line segment can be limited, the curvature of the third profile line segment is further limited, and the error of the volute profile line is further reduced.

In one embodiment, the equation for the logarithmic spiral is:

wherein r is the radius of the impeller, e is the base of the natural logarithm, a is the back flow angle of the blades of the impeller, B is the outlet width of the impeller, B is the height of the volute,

is the included angle between the polar radius of the logarithmic spiral curve and the connecting line of the polar point and the first intersection point,

is a correction value for R. Therefore, the spiral curve is corrected by setting a correction value, and the error of the molded line of the spiral casing can be reduced.

In one embodiment, the maximum rotating speed of the impeller is 800r/min-1000r/min, and l is 10mm-15 mm;

the maximum rotating speed of the impeller is 600r/min-800r/min, and l is 5mm-10 mm. Therefore, the correction in different degrees can be carried out according to impellers with different rotating speeds.

According to another aspect of the present application, an embodiment of the present application provides a centrifugal fan, including an impeller and the above-mentioned volute;

the impeller is arranged in the volute, and the center of the impeller is superposed with the pole of the logarithmic spiral curve. So, can make this centrifugal fan's exhaust fume efficient, the noise is low.

In one embodiment, the impeller has 64-70 blades. So, can make spiral case molded lines and impeller more match, improve spiral case smoke exhaust efficiency, noise reduction.

According to another aspect of the present application, an embodiment of the present application provides a range hood, which includes the centrifugal fan described above. Therefore, the smoke exhaust efficiency of the range hood is high, and the noise is low.

Additional aspects and advantages of embodiments of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of embodiments of the present application.

Drawings

FIG. 1 is a schematic view of a volute profile according to an embodiment of the related art;

FIG. 2 is a schematic view of a volute profile in another embodiment of the related art;

FIG. 3 is a schematic diagram of a volute according to an embodiment of the present application;

FIG. 4 is a schematic cross-sectional view of a volute according to an embodiment of the present disclosure;

FIG. 5 is a schematic view of a volute profile according to an embodiment of the present application;

FIG. 6 is an enlarged partial view of the second type line segment of FIG. 5 according to the present application;

FIG. 7 is a schematic view of the configuration of a volute profile according to an embodiment of the present disclosure;

FIG. 8 is a schematic acoustic pressure cloud diagram of a volute provided in an embodiment of the present application;

FIG. 9 is a sound pressure cloud diagram of a volute provided in a further embodiment of the present application;

figure 10 is a sound pressure cloud diagram of a volute provided in another embodiment of the present application.

Notation of elements for simplicity:

a first model line segment L1, a second model line segment L2, a third model line segment L3, a fourth model line segment L4, a first connecting line L5 and a second connecting line L6;

pole O, reference circle P, radial gap t;

a first tangent point T1, a second tangent point T2, and a third tangent point T3;

a first intersection point C1, a second intersection point C2;

the volute comprises a volute tongue 100, an air outlet 200, a volute upper plate 300, a volute bottom plate 400, a volute enclosing plate 500, an air inlet 600 and an air guide ring 700;

an impeller 20;

a motor 30.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present application more comprehensible, specific embodiments of the present application are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth to provide a thorough understanding of embodiments of the present application. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application. The embodiments of this application can be implemented in many different ways than those described herein and similar modifications can be made by those skilled in the art without departing from the spirit of the invention and therefore the embodiments of this application are not limited to the specific embodiments disclosed below.

It will be understood that, as used herein, the terms "first," "second," "third," "fourth," and the like may be used herein to describe various terms of art, and are not to be construed as indicating or implying relative importance or implicit to a number of technical features indicated. However, these terms are not intended to be limiting unless specifically stated. These terms are only used to distinguish one term from another. For example, the first type line segment, the second type line segment, the third type line segment and the fourth type line segment are different type line segments, and the first tangent point, the second tangent point and the third tangent point are different tangent points, without departing from the scope of the present application. In the description of the embodiments of the present application, "a plurality" or "a plurality" means at least two, e.g., two, three, etc., unless specifically defined otherwise.

In the description of the embodiments of the present application, unless otherwise explicitly stated or limited, the terms "mounted," "connected," "fixed," and the like are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the embodiments of the present application can be understood by those of ordinary skill in the art according to specific situations.

In the description of the embodiments of the present application, unless otherwise explicitly specified or limited, a first feature "on" or "under" a second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "above," and "over" a second feature may mean that the first feature is directly above or obliquely above the second feature, or that only the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely below the second feature, or may simply mean that the first feature is at a lesser level than the second feature.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present.

Unless defined otherwise, 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 present application in the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

The centrifugal volute is one of core components of the range hood, can concentrate gas near an air inlet of the volute, and drives the impeller to rotate through the driving motor, so that the gas is discharged from an outlet of the volute. In the process, the molded line of the centrifugal volute not only determines the shape of the volute, but also influences the air volume, the air pressure, the efficiency and the noise of the whole range hood.

FIG. 1 is a schematic view illustrating a volute profile in an embodiment of the related art; FIG. 2 is a schematic view illustrating a volute profile in another embodiment of the related art; for convenience of explanation, only portions related to the embodiments in the related art are shown.

Referring to fig. 1 and 2, in the related art, the volute profile is formed by a plurality of arcs, and four arcs with different circle centers are used to generate the volute profile. Thus, the segment of the curve has four circular arc radii of R1, R2, R3 and R4. The inventor of the application notices that the change of the arc radius of the adjacent arc is large, the vortex is generated in the volute, the air volume, the air pressure and the efficiency of the fan are greatly reduced, and a large pressure gradient is formed in the volute, so that the vortex noise is increased. In addition, the arc radius is in positive correlation with the rotating speed of the impeller, so that the larger the speed of the wind wheel is, the larger the error of the molded line of the volute is. So, make the spiral case molded lines and impeller mismatch, cause the spiral case to discharge fume inefficiency, the noise is high.

Based on the consideration, the inventor designs the volute through intensive research, and the shape of the molded line of the volute is limited, so that the smoke discharging efficiency of the volute can be improved, and the noise of the volute can be reduced. The volute provided by the embodiment of the application is described in connection with the related description of some embodiments.

The volute disclosed by the embodiment of the application can be used in a centrifugal fan, the centrifugal fan can be used in a range hood, and the volute can also be used in other wind power systems which need to use an air channel structure formed by the volute. The following description is given by way of example of the specific structure of the volute in some embodiments, but not by way of limitation. It should be noted that the profile of the volute disclosed in the embodiment of the present application may be in a clockwise direction or a counterclockwise direction, which may be selected according to the use situation, and the embodiment of the present application does not specifically limit this.

FIG. 3 illustrates a schematic diagram of a volute according to an embodiment of the present application; FIG. 4 shows a schematic cross-sectional structure of a volute in an embodiment of the present application; for convenience of explanation, only the portions related to the embodiments of the present application are shown.

For ease of understanding, as shown in FIG. 4, the upper direction of the drawing sheet is defined as the upper direction, the lower direction of the drawing sheet is defined as the lower direction, the left direction of the drawing sheet is defined as the left side, the right direction of the drawing sheet is defined as the right side, the left direction of the drawing sheet is defined as the front side, and the right direction of the drawing sheet is defined as the rear side. The remaining figures follow the definition of fig. 4. It is to be understood that the above definitions are for illustration purposes only and are not to be construed as limitations of the present application. It is to be understood that the above definitions are for illustration purposes only and are not to be construed as limitations of the present application.

Referring to fig. 3 and 4, an embodiment of the present application provides a volute including a volute upper plate 300, a volute bottom plate 400, and a volute bulkhead 500. An air inlet 600 is arranged on the volute casing upper plate 300. The volute bottom plate 400 is spaced from the volute top plate 300, and the volute bottom plate 400 is provided with a mounting hole for mounting the motor 30. The volute enclosing plate 500 is connected between the volute upper plate 300 and the volute bottom plate 400, an accommodating space and an air outlet 200 located at the rear side are enclosed among the volute enclosing plate 500, the volute upper plate 300 and the volute bottom plate 400, and the air inlet 600, the mounting hole (shown as a mark) and the air outlet 200 are communicated with the accommodating space. The receiving space is to receive the impeller 20. A volute tongue 100 is formed on the volute shroud 500 on one side close to the air outlet 200. The volute tongue 100 is used for dividing the airflow at the outlet of the volute, the flow field at the volute tongue 100 is complex, and the volute tongue 100 is also used for generating centrifugal volute noise.

The profile of the volute will be described below by taking the structure of the volute in some embodiments as an example.

FIG. 5 illustrates a schematic view of a volute profile in an embodiment of the present application; FIG. 6 is a partially enlarged view of the second profile L2 of FIG. 5 of the present application; for convenience of explanation, only the portions related to the embodiments of the present application are shown.

Referring to fig. 5 and 6, the molded line of the volute includes a first molded line segment L1, a second molded line segment L2, a third molded line segment L3, and a fourth molded line segment L4 connected in sequence. And the two connected line segments are smoothly transited. The third type line segment L3 forms the main body of the volute, the second type line segment L2 forms the volute tongue 100 of the volute, the first type line segment L1 and the fourth type line segment L4 form the air outlet 200 of the volute, and the third type line segment L3 is positioned on a logarithmic spiral curve.

The third section L3 and the second section L2 are tangent to the first tangent point T1, the third section L3 and the fourth section L4 are tangent to the second tangent point T2, and a direction from the first tangent point T1 to the second tangent point T2 along the third section L3 is a first path direction; a circle obtained by taking the pole O of the logarithmic spiral as the center of a circle and the radius r of the impeller 20 positioned in the volute as the radius is defined as a reference circle P, the logarithmic spiral 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 positioned between the first intersection point C1 and a second tangent point T2. Wherein, in the first path direction, the radial gap t gradually increases, and the curvature of the third profile line segment L3 is continuous. That is, the difference between the radius of the pole of the logarithmic spiral and the radius of the impeller 20 gradually increases in the first path direction. Taking fig. 5 as an example, the first path direction is clockwise along the third line segment L3.

It should be noted that the term "main body of the volute" refers to a portion of the impeller 20 corresponding to the volute enclosing plate 500 after the impeller 20 is placed in the volute, and the volute enclosing plate 500 is bent to form a shape adapted to the impeller 20, and correspondingly, the shape of the volute upper plate 300 and the volute bottom plate 400 at this portion is also adapted to the volute enclosing plate 500. The "radial gap T" varies from zero at the first intersection point C1 and ends at a location corresponding to the second tangent point T2.

Since the logarithmic spiral curve in which the third type line segment L3 is located is an arc line segment generated at the same center, the curvature of the third type line segment is continuous, and the radial gap t between the logarithmic spiral curve and the reference circle P is gradually increased by designing the reference circle P, so that the change of the polar radius of the third type line segment L3 is continuous. That is to say, the radial gap t and the curvature of the third profile line segment L3 jointly constrain the structure of the third profile line segment L3, so that the third profile line segment L3 is more smooth, the change of the polar radius of the third profile line segment L3 is continuous, the error of the volute profile is reduced, the vortex generated 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.

In some embodiments, with continued reference to fig. 5 and 6, the line connecting the pole O and the first tangent point T1 intersects the contour of the reference circle P at a second intersection point C2, and the length of the line connecting the second intersection point C2 and the first tangent point T1 is d 1. Wherein the ratio of r to d1 is 5.73-8.8. Thus, the distance between the third line segment L3 and the reference circle P can be defined, i.e. the minimum distance between the volute tongue 100 and the associated impeller 20, i.e. the minimum distance between the volute and the associated impeller 20. The volute tongue 100 prevents a portion of the gas from circulating in the volute. When the airflow at the outlet of the blade channel of the impeller 20 passes by the vicinity of the volute tongue 100, the volute tongue 100 divides the airflow, and most of the airflow flows along the channel to the air outlet 200. A small part of the airflow flows back into the volute through the gap between the volute tongue 100 and the impeller 20, and returns to the volute tongue 100 to participate in new flow division after rotating for a circle along with the impeller 20 in the volute. When the gap between the volute tongue 100 and the impeller 20 is too small, the airflow flowing back into the volute becomes small, but the airflow flowing to the air outlet 200 becomes large, and the wind noise becomes large. When the gap between the volute tongue 100 and the impeller 20 is too large, the airflow flowing to the air outlet 200 will be reduced, and the airflow flowing back into the volute will be increased, which will result in low exhaust efficiency of the volute. Thus, by limiting the minimum distance between the volute tongue 100 of the volute and the matched impeller 20, wind noise generated by fluid shunting at the volute tongue 100 can be prevented, the wind noise is prevented from being transmitted to the outside through the volute tongue 100 to influence the use feeling of a user, and good exhaust efficiency can be obtained.

In some embodiments, with continued reference to fig. 5 and 6, the second profile L2 is a circular arc. Thus, the wind resistance at the volute tongue 100 can be reduced by the arc shape. In some embodiments, the arc radius of the second profile segment L2 is R; wherein the ratio of R to R is 7.33-10.15. Thus, the size of the arc radius R of the second profile L2, i.e. the size of the corner of the volute tongue 100, can be limited, which not only can smoothly split the flow, but also can further reduce the wind noise at the volute tongue 100.

In some embodiments, with continued reference to fig. 5 and 6, a connection line between the pole O of the logarithmic spiral and the arc center O2 of the second type line segment L2 is a first connection line L5, a connection line between the pole O and the first intersection point C1 is a second connection line L6, and an included angle α 1 is formed between the first connection line L5 and the second connection line L6. Wherein alpha 1 is more than or equal to 76 degrees and less than or equal to 86 degrees. That is, the starting point of the third model line segment L3 is located on the reference circle P, and the line segment between the starting point of the third model line segment L3 and the starting point of the third model line segment L3 may be removed after the starting point of the third model line segment L3 is obtained, so that the shape of the third model line segment L3 is further defined to match the impeller 20, and the volute casing smoke discharge efficiency is improved. In this way, by limiting the included angle between the first line L5 and the second line L6, not only the arc length of the second profile L2 can be limited to obtain a preset shape of the volute tongue 100, thereby reducing wind noise, but also the starting point of the third profile L3 can be obtained, thereby further improving the dynamic characteristics of the fluid flowing through the volute tongue 100.

In some embodiments, with reference to fig. 5, the fourth line segment L4 is a straight line, and the included angle between the fourth line segment L4 and the second connection line L6 is α 2. Wherein alpha 2 is more than or equal to 80 degrees and less than or equal to 90 degrees. Taking fig. 5 as an example, the case where the included angle α 2 is 90 ° is illustrated. Therefore, a reasonable volute diffusion angle can be obtained, gas in the volute is prevented from flowing back to the inside of the volute, and the exhaust efficiency is improved.

In some embodiments, with continued reference to fig. 5, the length of the line connecting the first intersection point C1 and the second tangent point T2 is d 2. Wherein the ratio of r to d2 is 1.38-1.56. That is, the first intersection point C1 is the structural starting point of the third line segment L3, the second tangent point T2 is the structural end point of the third line segment L3, the distance between the structural starting point of the third line segment L3 and the structural end point of the third line segment L3 is limited, the third line segment L3 can be limited, the curvature of the third line segment L3 can be further limited, and the error of the volute shape line can be further reduced. In addition, the air flow to the air outlet 200 is limited, thereby not only not influencing the smoke exhaust efficiency, but also reducing the noise.

In some embodiments, the equation for the logarithmic spiral is:

wherein r is half of the impeller 20The diameter e is the base of the natural logarithm, a is the back flow angle of the blades of the impeller 20, B is the outlet width of the impeller 20 (i.e., the height of the impeller 20 in the vertical direction as illustrated in fig. 4), B is the height of the volute (i.e., the height of the volute in the vertical direction as illustrated in fig. 4, 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 and the second line L6,

In some embodiments, the maximum rotational speed of the impeller 20 is 800r/min to 1000r/min, and l is 10mm to 15 mm. In other embodiments, the maximum rotational speed of the impeller 20 is 600r/min to 800r/min, and l is 5mm to 10 mm. In this way, the correction can be performed to different degrees according to the impellers 20 having different rotation speeds.

Based on the same inventive concept, the embodiment of the present application provides a centrifugal fan, which includes an impeller 20 and a volute in the above embodiments. Wherein, the impeller 20 is arranged in the volute, and the center of the impeller 20 is superposed with the pole O of the logarithmic spiral curve. So, can make this centrifugal fan's exhaust fume efficient, the noise is low.

In some embodiments, the impeller 20 has a number of blades ranging from 64 blades to 70 blades. Therefore, the volute molded line can be more matched with the impeller 20, the smoke exhaust efficiency of the volute is improved, and the noise is reduced.

Based on the same inventive concept, the embodiment of the application provides a range hood, which comprises the centrifugal fan in the embodiment. Therefore, the smoke exhaust efficiency of the range hood is high, and the noise is low.

FIG. 7 illustrates a schematic view of the configuration of a volute profile in an embodiment of the present application; for convenience of explanation, only the portions related to the embodiments of the present application are shown.

Referring to fig. 7, a method for constructing a volute profile of a volute provided in an embodiment of the present application is illustrated as follows:

s100, constructing a logarithmic spiral curve: determining the radius r of the impeller 20 by taking any point as the pole of the logarithmic spiral curve, taking the radius r of the impeller 20 as an initial radius, taking the endpoint A on the initial radius as the starting point of the logarithmic spiral curve, and according to the equation of the logarithmic spiral curve

Forming a spiral curve S;

s200, constructing a second profile segment L2: at an included angle

The position of the angle of 76-86 degrees determines a second profile segment L2, the minimum distance between the second profile segment L2 and the reference circle P is 15-23 mm, and the arc radius of the second profile segment L2 is 13-18 mm;

s300, constructing a third line segment L3: taking the terminal point of the second type line segment L2 as the starting point of the third type line segment L3, taking the point B which is on the spiral curve S and is 85mm-95mm away from the terminal point A as the terminal point of the third type line segment L3, and the third type line segment L3 is tangent to the second type line segment L2;

s400, constructing a fourth line segment L4: the included angle between the fourth line segment L4 and the line segment OA is 80-90 degrees, and the fourth line segment L4 is tangent to the third line segment L3;

s500, constructing a first type line segment L1: the first type line segment L1 and the second type line segment L2 are tangent to the starting point of the second type line segment L2.

Figure 8 illustrates an acoustic pressure cloud diagram of a volute provided in an embodiment of the present application; figure 9 illustrates an acoustic pressure cloud diagram of a volute provided in a further embodiment of the present application; figure 10 illustrates an acoustic pressure cloud diagram of a volute provided in another embodiment of the present application; for convenience of explanation, only the portions related to the embodiments of the present application are shown.

In the above embodiment, d2 is 90mm, α 2 is 90 °, the arc radius R of the volute tongue 100 is 15mm, l is 10mm, the number of blades of the impeller 20 is 64, the radius R of the impeller 20 is 132mm, and then fluent simulation by Ansys is used as followsThe software performs pneumatic simulation on the volute provided by the embodiment of the application, and the minimum distance between the volute and the outer edge of the impeller 20 (namely, the length of a connecting line between the second intersection point C2 and the first tangent point T1) is 15mm, 19mm and 23mm respectively. Note that, in fig. 8 to 10, U1 represents a color corresponding to the sound pressure intensity in different regions, and U2 represents a specific sound pressure intensity in dB. Different sound pressure intensities have different colors, and the colors can change along with the change of the sound pressure intensities. The color change means that the color gradually changes from cold tone to warm tone along with the increasing sound pressure intensity. As shown in fig. 8 to 10, the color change appears as a gradual transition from the cool tone to the warm tone in the clockwise direction from the volute tongue 100, and most of the colors are cool tones in fig. 8 to 10. In the volute illustrated in figure 8, the minimum distance between the volute and the outer edge of the impeller 20 is 15mm, at an included angle

The sound pressure intensity at the volute tongue 100 of 80 degrees is 59db respectively, and in the volute shown in the diagram of fig. 9, the minimum distance between the volute and the outer edge of the impeller 20 is 19mm, and the included angle is formed

The sound pressure intensity at the volute tongue 100 of 80 degrees is 53db respectively, and in the volute casing illustrated in fig. 10, the minimum distance between the volute casing and the outer edge of the impeller 20 is 23mm, and the included angle is formed

The sound pressure intensity at the volute tongue 100 of 80 ° is 49db respectively. It can be seen that the aerodynamic noise at the volute tongue 100 is significantly improved.

To sum up, in the volute profile of the volute provided by the embodiment of the present application, because the logarithmic spiral curve where the third profile L3 is located is an arc segment generated at the same center of circle, the curvature of the third profile is continuous, and meanwhile, 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 profile L3 is continuous, the error of the volute profile is reduced, the vortex generated in the volute can be prevented to reduce the noise of the volute, the gas in the volute can be concentrated, and the smoke exhaust efficiency of the volute is improved. By defining the shape of the volute tongue 100 and the distance between the volute tongue 100 and the outer edge of the impeller 20, wind noise generated by fluid diversion at the volute tongue 100 is prevented from being transmitted to the outside through the volute tongue 100, and the use feeling of a user is prevented from being influenced. By defining the angle of the fourth profile line segment L4, more gas inside the volute is prevented from flowing back to the inside of the volute, and the exhaust efficiency is improved.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A volute is characterized in that the molded line of the volute comprises a first molded line segment (L1), a second molded line segment (L2), a third molded line segment (L3) and a fourth molded line segment (L4) which are connected in sequence, and the two connected molded line segments are in smooth transition; the third type line segment (L3) forms the main body of the volute, the second type line segment (L2) forms the volute tongue (100) of the volute, the first type line segment (L1) and the fourth type line segment (L4) form the air outlet (200) of the volute, and the third type line segment (L3) is located on a logarithmic spiral curve;

the third type line segment (L3) and the second type line segment (L2) are tangent to a first tangent point (T1), the third type line segment (L3) and the fourth type line segment (L4) are tangent to a second tangent point (T2), and a 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; defining a circle with the pole (O) of the logarithmic spiral as the center and the radius r of an impeller (20) in the volute as the radius as a reference circle (P), wherein the logarithmic spiral intersects the reference circle (P) at a first intersection point (C1), and a radial gap (T) is constructed between the outline of the reference circle (P) and the logarithmic spiral 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 type line segment (L3) is continuous.

2. A spiral casing according to claim 1, characterized in that a line connecting the pole (O) and the first tangent point (T1) intersects the profile 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) being d 1;

wherein the ratio of r to d1 is 5.73-8.8.

3. The spiral casing as claimed in claim 1, wherein the second profile segment (L2) is a circular arc, the circular arc radius of the second profile segment (L2) being R;

wherein the ratio of R to R is 7.33-10.15.

4. A spiral casing according to any of claims 1-3, characterized in that the line connecting the pole (O) of the logarithmic spiral with the arc center (O2) of the second type segment (L2) is a first line (L5), the line connecting the pole (O) and the first intersection point (C1) makes an angle α 1 with the first line (L5);

wherein alpha 1 is more than or equal to 76 degrees and less than or equal to 86 degrees.

5. The spiral casing according to any of the claims 1-3, characterized in that the fourth type line segment (L4) is a straight line and the fourth type line segment (L4) has an angle α 2 with the line connecting the pole (O) and the second intersection point (C2);

wherein alpha 2 is more than or equal to 80 degrees and less than or equal to 90 degrees.

6. The spiral casing of any of claims 1-3 wherein the first intersection point (C1) is connected to the second tangent point (T2) with a length d 2;

wherein the ratio of r to d2 is 1.38-1.56.

7. The spiral casing of any of claims 1 to 3 wherein the equation for the logarithmic spiral is:

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 blades of the impeller (20), B is the outlet width of the impeller (20), and B is the height of the volute,

is the angle between the polar radius of the logarithmic spiral and the line connecting the pole (O) and the first intersection point (C1),

is a correction value for R.

8. The spiral casing according to claim 7, wherein the impeller (20) has a maximum rotational speed of 800r/min-1000r/min, l being 10mm-15 mm;

the maximum rotating speed of the impeller (20) is 600r/min-800r/min, and l is 5mm-10 mm.

9. A centrifugal fan comprising an impeller (20) and a volute according to any of claims 1-8;

wherein the impeller (20) is arranged in the volute, and the center of the impeller (20) is superposed with the pole (O) of the logarithmic spiral curve.

10. The centrifugal fan according to claim 9, wherein the impeller (20) has a number of blades of 64-70 blades.

11. A range hood comprising a centrifugal fan according to claim 9 or 10.