Range hood

Abstract

The invention discloses a range hood which comprises a smoke collecting box, a smoke outlet, a smoke outlet and a smoke outlet. The fan is arranged in the smoke collecting box, and the fan is provided with an air inlet facing the front side; the range hood further comprises a flow guide piece arranged between the smoke inlet and the air inlet.

Description

Technical Field

[0001] This invention relates to an oil fume purification device, and more particularly to an oil fume extractor. Background Technology

[0002] As an essential kitchen appliance in every household, the range hood works by using a high-speed rotating impeller in the casing to draw in cooking fumes from the air inlet, filter the fumes using the impeller, and then expel the filtered fumes from the air outlet, thus purifying the kitchen air.

[0003] Range hoods are generally divided into top-mounted and side-mounted types. For side-mounted range hoods, in order to improve the smoke collection effect, a guide plate is usually set at the air inlet. The guide plate forms a ring suction plate. For example, a range hood disclosed in Chinese Patent Application No. 202222940145.2 includes a range hood body and a guide plate assembly. The range hood body is provided with an air inlet, and the guide plate assembly is set on the range hood body and located on the outside of the air inlet.

[0004] This type of range hood, with its unique ring-shaped air inlet and concentrated smoke collection effect, is favored by some consumers. The air inlet channel of a ring-type range hood is essentially the gap between the ring-shaped air guide plate assembly and the recessed platform structure on the main panel of the range hood. Most of the cooking fumes enter the range hood from this location. Some range hoods use a design where the recessed platform is not flush with the fan housing, shortening the gap between the platform and the air guide plate assembly. This strengthens the shielding effect of the back panel of the air guide plate assembly and the recessed platform on the internal functional components (such as the fan), enhancing the product's sophistication. Furthermore, appropriately narrowing the upper air inlet channel improves the smoke extraction effect, because cooking fumes are mostly collected from the lower part of the range hood. With the same airflow, narrowing the upper air inlet allows more airflow to enter the range hood from the lower and left / right sides.

[0005] While the design of the recessed platform not fitting snugly against the fan casing improves the product's refinement when installing the annular air inlet assembly, for ease of cleaning, annular suction range hoods often employ a detachable air inlet design. Therefore, the aforementioned technical solution exposes the internal structures such as the fan casing and sound-absorbing cotton when the air guide plate assembly is removed, affecting the product's refinement. Thus, additional structures are needed to cover the gap between the fan casing and the recessed platform.

[0006] Furthermore, the design where the recessed platform doesn't fit snugly against the fan casing creates two interconnected zones with significantly different airflow velocities during range hood operation. Notably, the airflow velocity is high in the area before the fan inlet and behind the annular inlet, while the velocity is lower inside the casing. Based on Bernoulli's principle, vortices form at the boundary between the high-speed and low-speed zones, resulting in significant turbulent noise. Therefore, it's necessary to separate these two spaces.

[0007] Therefore, further improvements are needed. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a range hood that guides the oil fume airflow smoothly into the fan and reduces noise.

[0009] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a range hood, comprising:

[0010] A smoke collection box, wherein a smoke inlet is provided on the front side of the smoke collection box; and

[0011] A fan is installed inside a smoke collection box, and the fan has a front-facing air inlet;

[0012] Its features are:

[0013] The range hood also includes a guide component disposed between the smoke inlet and the air inlet.

[0014] By setting up a flow guide, the fumes entering through the smoke inlet can be smoothly guided to the air inlet of the fan, while avoiding two zones with large differences in flow velocity when the range hood is working, thus avoiding turbulent noise caused by eddies due to different flow velocities.

[0015] Furthermore, to facilitate the installation of the smoke inlet, the smoke collection box includes a box body with an open front side and a panel assembly disposed at the open front side of the box body, with the smoke inlet located on the panel assembly.

[0016] Preferably, the panel assembly includes a panel body and a recessed platform formed on the panel body. The recessed platform is formed by the front of the panel body being recessed into the housing. The recessed platform includes a bottom wall and a peripheral wall formed on the outer periphery of the bottom wall. The peripheral wall extends from the outer periphery of the bottom wall toward the panel body. The smoke inlet is opened on the bottom wall.

[0017] To further avoid zones with large differences in flow velocity, the fan includes a volute, and the volute forms the aforementioned air inlet on the side facing the smoke inlet. The guide includes a bottom surface that is in close contact with the surface of the volute located on the outer periphery of the air inlet and a top surface that is in close contact with the bottom wall of the settling platform.

[0018] According to one aspect of the invention, an angle exists between the bottom wall of the settling platform and the surface of the volute forming the air inlet side, and the guide member is obtained by obliquely cutting the end face of the cylinder by the bottom wall of the settling platform. The cylindrical structure, compared to an irregular arc surface, is easier to manufacture, has higher machinability, and lower manufacturing cost. Furthermore, because it can be flattened, sound-absorbing structures such as small holes can be provided on the guide tube, while interference between the guide member and the air inlet ring typically located at the fan air inlet can be avoided.

[0019] Preferably, to ensure sufficient airflow guidance and noise reduction while maintaining ease of processing, the outer periphery of the smoke inlet forms a first circle, the center of which is a first center and the radius is r. c The bottom profile of the guide member forms a second circle, the center of the second circle is the second center and the radius is r, and the projection of the first circle on the plane on the side where the air inlet is opened in the volute is an ellipse, and the ellipse is externally tangent to the second circle.

[0020] The radius of the equivalent circle of the ellipse Wherein, the major axis and the minor axis are the major axis and the minor axis of the ellipse, respectively; the eccentricity between the center of the equivalent circle and the second center is L. p The radius of the second circle is r≈L p +r d .

[0021] To further ensure sufficient airflow guidance and noise reduction while maintaining ease of machining, the center point of the air inlet on the volute is also the aforementioned second center, with the coordinates of the second center being (0, 0, 0). The equation of the plane on the side of the volute where the air inlet is located is z = 0, and the coordinates of the first center are (a, b, c). The normal vector of the bottom wall of the smoke inlet is set on the set-top platform.

[0022] The major and minor axes of the ellipse are respectively perpendicular to the plane normal vector. The following relationship must be satisfied:

[0023] Long axis

[0024] short axis

[0025] The equation of the ellipse in the z=0 plane is:

[0026]

[0027] The radius r of the equivalent circle of the ellipse d for:

[0028]

[0029] The eccentricity

[0030] The radius of the second circle

[0031] According to another aspect of the invention, there is an included angle between the bottom wall of the platform and the surface of the volute forming the air inlet side, and the guide is obtained by obliquely cutting the end face of the oblique cylinder by the bottom wall of the platform. The oblique cylinder can improve the smoothness and tightness of the flow channel connection while ensuring the machinability of the structure, reduce the mismatch area between the smoke inlet on the platform and the guide, and reduce turbulence noise.

[0032] Furthermore, to improve the connection between the guide and the settling platform, the center point of the smoke inlet on the settling platform is the first center, the center point of the air inlet on the volute is the second center, the center of the circle formed by the profile of the bottom surface of the guide is also the second center, the position coordinates of the second center are (0, 0, 0), the equation of the plane on the side of the volute where the air inlet is opened is z = 0, and the position coordinates of the first center are (a, b, c).

[0033] The direction vector of the axis (N) of the flow guide in space is:

[0034]

[0035] Therefore, the geometric center of the elliptical curve formed by the guide member on the bottom wall of the platform coincides with the geometric center of the smoke inlet.

[0036] Furthermore, to better reduce the mismatch area between the smoke inlet and the guide vane on the set-top platform and reduce turbulence noise, the outer periphery of the smoke inlet is formed into a circle with a first center as the center and a radius of r. c The normal vector of the bottom wall of the settling platform where the smoke inlet is located. The radius of the circle formed by the profile of the bottom surface of the guide is r, and the radius r satisfies the following relationship:

[0037]

[0038] Compared with the prior art, the advantages of the present invention are as follows: by setting guide components at the smoke inlet of the smoke collection box and the air inlet of the fan, the oil fumes entering through the smoke inlet can be smoothly guided to the air inlet of the fan, while avoiding two zones with large differences in flow velocity during the operation of the range hood, thereby avoiding turbulent noise caused by eddies due to different flow velocities; the guide components are designed and optimized from the perspectives of spatial interference, processability optimization, and aerodynamic optimization to obtain better flow guidance and noise reduction performance and ease of processing. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of a range hood according to the first embodiment of the present invention;

[0040] Figure 2 This is a cross-sectional side view (front and rear vertical section) of the range hood according to the first embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of the air guide component of the range hood according to the first embodiment of the present invention;

[0042] Figure 4 This is a side view of the air guide component of the range hood according to the first embodiment of the present invention;

[0043] Figure 5 This is a schematic diagram of the concealed air guide plate and fan mesh cover of the range hood according to the second embodiment of the present invention;

[0044] Figure 6 This is a schematic diagram of the concealed air guide plate and panel assembly of the range hood according to the second embodiment of the present invention;

[0045] Figure 7 This is a front view of the concealed air guide plate and panel assembly of the range hood according to the second embodiment of the present invention (the fan is in front view);

[0046] Figure 8 This is a cross-sectional view (front and back vertical section) of the range hood according to the second embodiment of the present invention;

[0047] Figure 9 This is a top sectional view (horizontal section) of the range hood according to the second embodiment of the present invention;

[0048] Figure 10 This is a schematic diagram of the air guide component of the range hood according to the second embodiment of the present invention;

[0049] Figure 11 This is a side view of the air guide component of the range hood according to the second embodiment of the present invention;

[0050] Figure 12 This is a flattened schematic diagram of the air guide component of the range hood according to the second embodiment of the present invention;

[0051] Figure 13 This is a front view of the concealed air guide plate and panel assembly of the range hood according to the third embodiment of the present invention (the fan is in front view);

[0052] Figure 14 This is a schematic diagram of the air guide component of the range hood according to the third embodiment of the present invention;

[0053] Figure 15 This is a schematic diagram (viewed from bottom to top) of the air guide component of the range hood according to the third embodiment of the present invention. Detailed Implementation

[0054] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0055] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Since the embodiments disclosed in this invention can be arranged in different directions, these terms indicating direction are only for illustration and should not be regarded as limitations. For example, "upper" and "lower" are not necessarily limited to directions opposite to or consistent with the direction of gravity. In addition, features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0056] Example 1

[0057] See Figures 1-4 A range hood includes a smoke collection box 1 and a fan 2 disposed inside the smoke collection box 1.

[0058] The smoke collection box 1 includes a box body 11 with an open front side and a panel assembly 12 disposed at the open front side of the box body 11. The upper and lower edges of the panel assembly 12 extend to the upper and lower edges of the open front side of the box body 11, respectively, thereby closing the open front side of the box body 11. A smoke inlet 13 is provided on the front of the smoke collection box 1. Preferably, the smoke inlet 13 is located on the panel assembly 12 and at the center of the panel assembly 12 along the width direction of the range hood. The width direction of the range hood refers to the left-right direction when the user faces the range hood in its normal installation state. (See [reference needed]). Figure 1 As shown by arrow M in the diagram.

[0059] The panel assembly 12 includes a panel body 121 and a recessed platform 122 formed on the panel body 121. The recessed platform 122 is formed by recessing the front of the panel body 121 into the housing 11. The recessed platform 122 includes a bottom wall 1221 and a peripheral wall 1222 formed on the outer periphery of the bottom wall 1221. The peripheral wall 1222 extends from the outer periphery of the bottom wall 1221 toward the panel body 121, thereby connecting integrally with the rest of the panel body 121. The aforementioned smoke inlet 13 is formed on the bottom wall 1221, and its preferred cross-section is also circular, where the cross-section refers to the cross-section along the thickness direction of the bottom wall 1221. The smoke inlet 13 is smaller than the opening of the recessed platform 122. Preferably, the cross-section of the bottom wall 1221 is circular, where the cross-section refers to the cross-section along the thickness direction of the panel body 121, and the diameter of the peripheral wall 1222 may gradually decrease from front to back.

[0060] The fan 2 includes a volute 21, an impeller 22 disposed within the volute 21, and a motor 23 for driving the impeller 22 to rotate. An air inlet 25 is formed on the side of the volute 21 facing the smoke inlet 13, and an air inlet ring 24 is provided at the air inlet 25. The above-described fan 2 is prior art.

[0061] The smoke collection box 1 is also equipped with a guide 14 inside the box 11, which connects the smoke inlet 13 and the air inlet 25 of the fan 2. The guide 14 is hollow so as to smoothly guide the oil fumes entering from the smoke inlet 13 to the air inlet 25 of the fan 2.

[0062] In addition, a mesh cover 26 extending into the air guide 14 can be installed at the air inlet 25.

[0063] The range hood also includes an air guide plate 3, which is located at intervals on the front side of the recessed platform 122. As a result, the fumes can enter the recessed platform 122 along the outer periphery of the air guide plate 3, forming a ring suction.

[0064] The bottom of the housing 11 is provided with an oil cup 4 to collect the oil flowing down from the housing 11.

[0065] The aforementioned fan 2 can be controlled by a voice module. A controller, a voice receiving module, and a voice parsing module can be installed on the range hood. The voice receiving module receives user commands, and the voice parsing module parses the commands. Based on the parsed commands, the controller controls the fan 2 to perform corresponding operations, thereby realizing intelligent control of the range hood and improving the user experience.

[0066] Example 2

[0067] In Embodiment 1, the air inlet 25 and the smoke inlet 13 are directly connected by the flow guide 14. The flow channel is tightly connected and there is no dead zone, which is optimal from the perspective of aerodynamic performance. However, it is easy to cause spatial interference between the flow guide 14 and the air inlet ring 24. In addition, the flow guide 15 has an irregular arc shape, which makes it difficult to process and has high processing cost.

[0068] Therefore, in this embodiment, see Figures 5-12 The guide member 14 is a straight cylinder with a beveled edge adjacent to the panel assembly 12 to fit the recessed platform 122. The connection point between the guide member 14 and the fan 2 is designated as its bottom surface 142, while the connection point with the recessed platform 122 is designated as its top surface 143. The bottom surface 142 of the guide member 14 is annular, meaning the profile of the bottom surface 142 is circular, surrounding the outer periphery of the air inlet 25. The radius of this circle can be obtained as follows: project the smoke inlet 13 of the recessed platform 122 onto the surface of the volute 21, and find the point on the curve that is furthest from the center of the air inlet 25 on the volute 21. The distance from this furthest point to the center of the air inlet 25 is the radius of the bottom profile circle.

[0069] Therefore, the flow guide 14 is easy to manufacture, highly machinable, and inexpensive. Furthermore, because it can be flattened, noise reduction holes 141 can be formed on the flow guide 14, while also preventing interference between the flow guide 14 and the air inlet ring 24.

[0070] The main design parameter of the aforementioned guide member 14 is the radius r of the bottom surface, which can be designed in the following way:

[0071] 1. Given conditions:

[0072] Taking the center point of the air inlet 25 on the volute 21 as the second center O2, its coordinates in the three-dimensional coordinate system are (0, 0, 0), and the normal vector of the side of the volute 21 where the air inlet 25 is located... Its plane equation is easily obtained as z = 0. The center point of the smoke inlet 13 on the settling platform 122 is the first center O1. Based on the determined structural design of the settling platform 122, the guide element 14 is designed, so the position of this first center O1 is equivalent to a known position, denoted as (a, b, c). The radius r of the smoke inlet 13 is... c Assume it is known. The normal vector of the bottom wall 1221 (which is a wall of uniform thickness, simplified to a plane) of the smoke inlet 13 is set on the set-off platform 122. It is considered to be known (its spatial plane equation is easily derived as A(xa)+B(yb)+C(zc)=0).

[0073] 2. Geometric Model

[0074] Therefore, the design of the guide element 14 can be converted into the following geometric description: On a plane in space with the equation A(xa) + B(yb) + C(zc) = 0, there is a center point (a, b, c) and a radius r. c There is a circle (denoted as the first circle A1) with radius r on the plane z = 0 (denoted as the second circle A2, which is the circle formed by the bottom surface 142 of the guide 14). The center of the circle is the second center O2. The projection of the first circle A1 onto the plane z = 0 is an ellipse A3 (because there is an angle between the bottom wall 1221 of the platform 122 and the surface of the volute 21 that forms the air inlet 25, i.e., they are not parallel to each other, hence the projection is an ellipse). The ellipse A3 is just externally tangent to the second circle A2. Given r... c Find r.

[0075] 3. Solution process:

[0076] 3.1 The center of ellipse A3 is the projection of the first circle A1 onto the plane z = 0. The coordinates of the center of this ellipse A3 are (a, b, 0).

[0077] 3.2 Major and Minor Axis Lengths: Since the plane A(xa) + B(yb) + C(zc) = 0 is inclined relative to the surface of the volute 21 where the air inlet 25 is located, the first circle A1 will be deformed into an ellipse when projected onto the plane z = 0. Because the projection is linear, the major and minor axes of the ellipse A3 are perpendicular to the plane normal vector. The following relationship is satisfied.

[0078] Long axis

[0079] short axis

[0080] The equation of ellipse A3 in the z=0 plane is:

[0081]

[0082] The equation of the second circle A2 on the z=0 plane is:

[0083] x 2 +y 2 =r 2

[0084] 3.3 External tangency condition: Among the parameters of ellipse A3, A, B, C, a, b, r c Given that everything is known, the exact value of the tangent circle r can be calculated using the theory of external tangency conditions. However, this precise calculation is quite cumbersome. Therefore, the following simplified calculation is provided to use the radius r of the "equivalent circle" of ellipse A3. d It can be calculated using the following formula

[0085]

[0086] Eccentricity between the center of the equivalent circle and O2

[0087] The radius of the second circle A2

[0088] Example 3

[0089] See Figures 13-15 In this embodiment, the difference from Embodiment 2 is that the guide member 14 is a regular oblique cylinder, which can be manufactured by cutting an oblique cylindrical tube and assembled by welding it to the surface of the air inlet ring 24. This ensures the machinability of the structure while maximizing the smoothness and tightness of the flow channel connection, reducing the mismatch area between the smoke inlet 13 and the guide member 14, and reducing turbulence noise.

[0090] To minimize the area of ​​the mismatch between the guide vane 14 and the smoke inlet 13 on the settling platform 122, the design is carried out as follows:

[0091] 1. Determine the control parameters of the inclined cylinder.

[0092] Describing the geometric features of an oblique cylinder typically requires the following parameters:

[0093] 1.1 Base radius r: The radius of the cylinder's base is a variable that needs to be designed in this patent;

[0094] 1.2 Bottom center position: It is usually necessary to determine the center position of the bottom surface. The center coordinates are (0, 0, 0) with the center point of the air inlet 25 on the volute 21 as the center coordinates, the same as in Example 2.

[0095] 1.3 Axis Direction: The direction vector of the axis N of the skew cylinder in space. To describe.

[0096] 1.4 Height: The height of a cylinder is the vertical distance between the bottom and top surfaces. Once the axial direction and slope angle are determined, the height of the base material can be considered infinitely long and therefore unimportant.

[0097] 2. Obtain the direction vector of the cylinder's axis in space.

[0098] The position of the smoke inlet 13 of the settling platform 122 is known and denoted as (a, b, c), as in Embodiment 2. When the axis of the cylinder has a direction vector in space... When the vector points from the origin to the center of the platform, the projection of the inclined cylinder and the platform 122 has the highest degree of overlap, which corresponds to a better connection between the guide 14 and the platform 122.

[0099]

[0100] The geometric center of the elliptical curve formed on the cross section of the guide component 14 designed by the above scheme after the oblique cylinder is obliquely cut by the bottom wall 1221 of the settling platform 122 coincides with the geometric center of the smoke inlet 13.

[0101] 3. Calculate the base radius r

[0102] By using the above method, after aligning the geometric center of the cross-sectional ellipse with the geometric center of the smoke inlet 13, and setting the bottom radius r to be as small as possible within a reasonable range, the area of ​​the mismatch between the smoke inlet 13 and the guide 14 can be minimized.

[0103] The specific method for obtaining r is as follows:

[0104] The radius of the smoke inlet 13 is r c The normal vector of the plane where the smoke inlet 13 is located depends on the design requirements such as smoke extraction effect and appearance, and is considered known, the same as in Embodiment 2.

[0105] Let the normal vector of the plane containing the smoke inlet 13 be... Given that the coordinates of a point on the plane are (a, b, c), the equation of the plane can be expressed as A(xa) + B(yb) + C(zc) = 0.

[0106] The method for obtaining r can be transformed into the following geometric model: an infinitely long inclined cylindrical tube with an axis direction of (a,b,c) and a radius of r intersects the space plane A(xa)+B(yb)+C(zc)=0, and the cross-section forms an ellipse. Find the length L of the minor axis of the ellipse. When L=r c At this time, it can be assumed that the guide 14 is tangent to the smoke inlet 13.

[0107] The relationship between the minor axis length L of the ellipse, the radius r of the cylinder, and the angle θ between the plane and the axis of the cylinder is as follows:

[0108] L=r·sin(θ)

[0109] Where θ is the angle between the cylinder axis and the plane normal vector, it can be calculated using the following formula:

[0110]

[0111] When L = r c hour

[0112]

[0113] If you want the edge of the guide vane 14 to be slightly larger than the smoke inlet 13, you can adjust the r... c The value should be increased slightly by 3-5 mm.

[0114] Furthermore, since the mating structure between the aforementioned guide element 14 and the air inlet ring 24 is geometrically asymmetrical, the positioning accuracy of the guide element 14 during welding to the air inlet ring 24 is critical. If the guide element 14 is angled, problems such as exposed structure may occur. To solve these problems, process positioning holes can be made on the guide element 14. Its ease of machining also allows for the inclusion of sound-absorbing holes to improve its noise reduction effect.

Claims

1. A range hood, comprising: A smoke collection box (1) is provided with a smoke inlet (13) on the front side; as well as A fan (2) is installed inside a smoke collection box (1), the fan (2) having an air inlet (25) facing forward; Its features are: The range hood also includes a guide (14) disposed between the smoke inlet (13) and the air inlet (25).

2. The range hood according to claim 1, characterized in that: The smoke collection box (1) includes a box body (11) with an open front side and a panel assembly (12) provided at the open front side of the box body (11), and the smoke inlet (13) is opened on the panel assembly (12).

3. The range hood according to claim 2, characterized in that: The panel assembly (12) includes a panel body (121) and a recessed platform (122) formed on the panel body (121). The recessed platform (122) is formed by the front of the panel body (121) recessed into the housing (11). The recessed platform (122) includes a bottom wall (1221) and a peripheral wall (1222) formed on the outer periphery of the bottom wall (1221). The peripheral wall (1222) extends from the outer periphery of the bottom wall (1221) toward the panel body (121). The smoke inlet (13) is opened on the bottom wall (1221).

4. The range hood according to claim 3, characterized in that: The fan (2) includes a volute (21), and the volute (21) forms the air inlet (25) on the side facing the smoke inlet (13). The guide (14) includes a bottom surface (142) that is in close contact with the surface of the volute (21) located on the outer periphery of the air inlet (25) and a top surface (143) that is in close contact with the bottom wall (1221) of the settling platform (122).

5. The range hood according to claim 4, characterized in that: There is an angle between the bottom wall (1221) of the sinking platform (122) and the surface of the volute (21) forming the air inlet (25). The guide (14) is a cylindrical end face that is obliquely cut by the bottom wall (1221) of the sinking platform (122).

6. The range hood according to claim 5, characterized in that: The outer periphery of the smoke inlet (13) forms a first circle (A1), the center of which is a first center (O1) and the radius is r. c The bottom surface (142) of the guide (14) forms a second circle (A2), the center of the second circle (A2) is the second center (O2) and the radius is r. The projection of the first circle (A1) on the plane of the side where the air inlet (25) is opened on the volute (21) is an ellipse (A3), and the ellipse (A3) is externally tangent to the second circle (A2). The radius of the equivalent circle of the ellipse (A3) Wherein, the major axis and minor axis are the major axis and minor axis of the ellipse (A3), respectively; the eccentricity between the center of the equivalent circle and the second center (O2) is L. p The radius of the second circle (A2) is r≈L p +r d .

7. The range hood according to claim 6, characterized in that: The center point of the air inlet (25) on the volute (21) is also the second center (O2) mentioned above. The coordinates of the second center (O2) are (0, 0, 0). The equation of the plane on the side of the volute (21) where the air inlet (25) is opened is z = 0. The coordinates of the first center (O1) are (a, b, c). The normal vector of the bottom wall (1221) of the smoke inlet (13) of the set-top platform (122) is set. The major and minor axes of the ellipse (A3) are respectively perpendicular to the plane normal vector. The following relationship must be satisfied: Long axis short axis The equation of the ellipse (A3) in the z=0 plane is: The radius r of the equivalent circle of the ellipse (A3) d for: The eccentricity The radius of the second circle (A2) 8. The range hood according to claim 4, characterized in that: There is an angle between the bottom wall (1221) of the sinking platform (122) and the surface of the volute (21) forming the air inlet (25). The guide (14) is obtained by obliquely cutting the end face of the oblique cylinder by the bottom wall (1221) of the sinking platform (122).

9. The range hood according to claim 8, characterized in that: The center point of the smoke inlet (13) on the settling platform (122) is the first center (O1), the center point of the air inlet (25) on the volute (21) is the second center (O2), the center of the circle formed by the profile of the bottom surface (142) of the guide (14) is also the second center (O2), the position coordinates of the second center (O2) are (0, 0, 0), the equation of the plane on the side of the volute (21) where the air inlet (25) is opened is z = 0, and the position coordinates of the first center (O1) are (a, b, c). The direction vector of the axis (N) of the guide (14) in space is: Thus, the geometric center of the elliptical curve formed by the guide member (14) on the bottom wall (1221) of the settling platform (122) coincides with the geometric center of the smoke inlet (13).

10. The range hood according to claim 9, characterized in that: The outer periphery of the smoke inlet (13) forms a circle with the first center (O1) as the center and the radius is r. c The normal vector of the bottom wall (1221) of the settling platform (122) is provided by the smoke inlet (13). The radius of the circle formed by the profile of the bottom surface (142) of the guide member (14) is r, and the radius r satisfies the following relationship:

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