Range hood

Abstract

The utility model provides a range hood which comprises an impeller and a smoke collecting cavity, the smoke collecting cavity is located at the upstream of the impeller, and air is sucked to an air outlet from an air inlet of the smoke collecting cavity; a first arc-plate-shaped flow guide plate and a second arc-plate-shaped flow guide plate are arranged in the smoke collecting cavity, the first flow guide plate is located on the first side opposite to the rotating tangential direction in the rotating tangential direction of the upstream area of the impeller in the rotating direction of the impeller, and the second flow guide plate is located on the second side facing the rotating tangential direction; the outer arc surface of the first guide plate faces the air inlet, and the first air outlet end of the first guide plate is connected to the first outer wall surface, close to the first side, of the air outlet; the inner arc face of the second guide plate faces the air inlet, and the second air outlet end of the second guide plate is connected to the second outer wall face, close to the second side, of the air outlet. Therefore, gas vortex and flow separation generated in the corresponding corner areas can be reduced, the adverse effect of the corner areas on the aerodynamic performance and noise of the range hood is reduced, and the flow characteristics of the corner areas on the two sides are adapted.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of range hood. BACKGROUND

[0002] Range hood is a kind of kitchen appliance for purifying kitchen environment, mainly used for the oil fume generated during cooking is discharged outdoor. The existing range hood product can be divided into low suction, side suction and top suction according to the position of air inlet. With the improvement of living standards, people have better requirements for the performance, appearance and noise of range hood. For low suction type range hood, especially the smoke collection cavity ultra-thin type range hood, due to the small thickness size of smoke collection cavity, the operating space above the cooking bench can be released, and the position of air inlet is relatively close to the source of smoke, which can "capture" the oil fume into the air inlet channel in the initial stage of oil fume diffusion, and has good gathering ability, and is favored by consumers in recent years.

[0003] However, at the same time, the structure of low suction, ultra-thin range hood also brings some problems in use. Due to the relatively small thickness size of smoke collection cavity of low suction, ultra-thin range hood, compared with other types of range hood, the airflow velocity in the ultra-thin smoke collection cavity is larger, which is easy to produce gas vortex and flow separation in the cavity, especially in the corner area, which affects the aerodynamic performance and noise of range hood. UTILITY MODEL CONTENTS

[0004] The technical problem to be solved by the utility model is to overcome the defect that gas vortex and flow separation are easy to occur in the corner area of the ultra-thin smoke collection cavity in the prior art, and to provide a range hood.

[0005] The utility model solves the above technical problems by the following technical scheme:

[0006] A range hood comprises an impeller and a smoke collection cavity, the smoke collection cavity is located upstream of the impeller, air is sucked from the air inlet of the smoke collection cavity to the air outlet; the smoke collection cavity is provided with arc plate-shaped first and second guide plates, in the tangential direction of the upstream area of the impeller along the rotation direction of the impeller, the first guide plate is located on the first side of the smoke collection cavity opposite to the rotation tangential direction, and the second guide plate is located on the second side of the smoke collection cavity facing the rotation tangential direction;

[0007] The outer arc surface of the first guide plate faces the air inlet, the first guide plate has a first air outlet end close to the air outlet, and the first air outlet end is connected to the first outer wall surface of the air outlet close to the first side;

[0008] The inner arc surface of the second guide plate faces the air inlet, the second guide plate has a second air outlet end close to the air outlet, and the second air outlet end is connected to the second outer wall surface of the air outlet close to the second side.

[0009] In the technical solution, the first and second flow guide plates are arranged on both sides of the upstream tangent line inside the smoke collecting cavity, so that the gas vortex and flow separation generated in the corresponding corner area are reduced, and the adverse effects of the corner area on the aerodynamic performance and noise of the range hood are reduced. The first outflow end of the first flow guide plate is connected to the first outer wall surface, and the second outflow end of the second flow guide plate is connected to the second outer wall surface, so that the adverse effects of the narrow tube formed between the first flow guide plate and the first outer wall surface and between the second flow guide plate and the second outer wall surface on the aerodynamic performance and noise of the range hood are avoided. The outer arc surface of the first flow guide plate on the first side facing away from the direction of the rotating tangent line faces the air inlet, and the inner arc surface of the second flow guide plate on the second side facing the direction of the rotating tangent line faces the air inlet, so that the flow characteristics of the two corner areas are adapted, and the smoke collecting effect of the smoke collecting cavity is further improved, and the adverse effects of the corner area on the aerodynamic performance and noise of the range hood are reduced.

[0010] Preferably, the included angle between the tangent direction of the first outflow end and the first outer wall surface is set as a first outflow angle, and the range of the first outflow angle is 0°-15°.

[0011] In the technical solution, the above arrangement can further adapt the gas flow characteristics of the first outflow end.

[0012] Preferably, the first flow guide plate further has a first inflow end close to the air inlet, and the smoke collecting cavity has a first inner wall surface close to the first side.

[0013] The included angle between the tangent direction of the first inflow end and the first inner wall surface is set as a first inflow angle, and the range of the first inflow angle is 30°-60°; and / or,

[0014] The range hood further includes a first inflow end fixing member, the first inflow end is provided with a first inflow mounting hole, and the first inflow end fixing member is arranged in the first inflow mounting hole to fix the first inflow end to the first inner wall surface.

[0015] In the technical solution, by setting the range of the first inflow angle to be 30°-60°, the gas flow characteristics of the first inflow end can be further adapted. By arranging the first inflow end fixing member in the first inflow mounting hole, the first inflow end can be maintained stable in the airflow with a relatively simple structure.

[0016] Preferably, the first flow guide plate is provided with a plurality of first sound absorption holes.

[0017] The ratio of the perforated area of the first sound absorption hole to the total area of the first flow guide plate is in the range of 3%-8%; and / or,

[0018] The first sound absorption hole has a hole diameter ranging from 1 mm to 3 mm; and / or

[0019] The hole distance between adjacent first sound absorption holes ranges from 6 mm to 8 mm.

[0020] In the technical solution, by setting the ratio of the perforated area of the first sound absorption hole to the total area of the first flow guide plate to range from 3% to 8%, or the hole diameter of the first sound absorption hole to range from 1 mm to 3 mm, or the hole distance between adjacent first sound absorption holes to range from 6 mm to 8 mm, the aerodynamic noise in the smoke collecting cavity can be further reduced.

[0021] Preferably, the side edge of the first flow guide plate is provided with a first flow guide flange;

[0022] The first flow guide flange and the inner arc surface of the first flow guide plate form an included angle ranging from 80° to 100°; and / or,

[0023] The first flow guide flange has a width ranging from 4 mm to 6 mm.

[0024] In the technical solution, by setting the included angle between the first flow guide flange and the inner arc surface of the first flow guide plate to range from 80° to 100°, or the width of the first flow guide flange to range from 4 mm to 6 mm, the strength of the first flow guide plate can be improved.

[0025] Preferably, an included angle between the tangent direction of the second air outlet and the second outer wall surface is set as a second air outlet angle, and the second air outlet angle ranges from 30° to 60°.

[0026] In the technical solution, by the above settings, the gas flow characteristics of the second air outlet can be further adapted.

[0027] Preferably, the second flow guide plate further has a second air inlet end close to the air inlet, and the smoke collecting cavity has a second inner wall surface close to the second side;

[0028] An included angle between the tangent direction of the second air inlet end and the second inner wall surface is set as a second air inlet angle, and the second air inlet angle ranges from 0° to 15°; and / or,

[0029] The extractor hood further includes a second air inlet end fixing member, the second air inlet end is provided with a second air inlet mounting hole, and the second air inlet end fixing member is arranged through the second air inlet mounting hole to fix the second air inlet end to the second inner wall surface.

[0030] In the technical solution, by setting the second air inlet angle to range from 0° to 15°, the gas flow characteristics of the second air inlet end can be further adapted. By arranging the second air inlet end fixing member through the second air inlet mounting hole, the second air inlet end can be maintained stable in the airflow with a relatively simple structure.

[0031] Preferably, a plurality of second sound absorption holes are arranged on the second flow guide plate.

[0032] The ratio of the perforated area of the second sound absorption hole to the total area of the second flow guide plate ranges from 3% to 8%; and / or,

[0033] The aperture of the second sound absorption hole ranges from 1mm to 3mm; and / or,

[0034] The hole distance of adjacent second sound absorption holes ranges from 6mm to 8mm.

[0035] In the technical solution, by setting the ratio of the perforated area of the second sound absorption hole to the total area of the second flow guide plate ranges from 3% to 8%, or the aperture of the second sound absorption hole ranges from 1mm to 3mm, or the hole distance of adjacent second sound absorption holes ranges from 6mm to 8mm, the aerodynamic noise in the smoke collecting cavity can be further reduced.

[0036] Preferably, a second flow guide flange is arranged on the side edge of the second flow guide plate.

[0037] The included angle between the second flow guide flange and the inner arc surface of the second flow guide plate ranges from 80° to 100°; and / or,

[0038] The width of the second flow guide flange ranges from 4mm to 6mm.

[0039] In the technical solution, by setting the included angle between the second flow guide flange and the inner arc surface of the second flow guide plate ranges from 80° to 100°, or the width of the second flow guide flange ranges from 4mm to 6mm, the strength of the second flow guide plate can be improved.

[0040] Preferably, the extractor hood further comprises a first air outlet end fixing member, a first air outlet mounting hole is arranged on the first air outlet end, the first air outlet end fixing member is arranged through the first air outlet mounting hole, and the first air outlet end is fixed to the first outer wall surface; and / or,

[0041] The extractor hood further comprises a second air outlet end fixing member, a second air outlet mounting hole is arranged on the second air outlet end, the second air outlet end fixing member is arranged through the second air outlet mounting hole, and the second air outlet end is fixed to the second outer wall surface.

[0042] In the technical solution, by arranging the first air outlet end fixing member through the first air outlet mounting hole, the first air outlet end can be maintained stable in the airflow with a relatively simple structure. By arranging the second air outlet end fixing member through the second air outlet mounting hole, the second air outlet end can be maintained stable in the airflow with a relatively simple structure.

[0043] The positive progress effect of the utility model lies in:

[0044] By providing the range hood, the first guide plate and the second guide plate are respectively arranged on both sides of the upstream tangent line inside the smoke collecting cavity, so that the gas vortex and flow separation generated in the corresponding corner area are reduced, and the adverse effects of the corner area on the aerodynamic performance and noise of the range hood are reduced. The first gas outlet end of the first guide plate is connected to the first outer wall surface, and the second gas outlet end of the second guide plate is connected to the second outer wall surface, so that the adverse effects of the narrow pipe formed between the first guide plate and the first outer wall surface and between the second guide plate and the second outer wall surface on the aerodynamic performance and noise of the range hood are avoided. The outer arc surface of the first guide plate located on the first side opposite to the direction of the rotation tangent line faces the air inlet, and the inner arc surface of the second guide plate located on the second side facing the direction of the rotation tangent line faces the air inlet, so that the flow characteristics of the two corner areas are adapted, and the smoke collecting effect of the smoke collecting cavity is further improved, and the adverse effects of the corner area on the aerodynamic performance and noise of the range hood are reduced. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 It is a three-dimensional structure schematic view of the range hood of an embodiment of the utility model.

[0046] Figure 2 It is a sectional structure schematic view of the range hood of an embodiment of the utility model.

[0047] Figure 3 It is a three-dimensional structure schematic view of the first guide plate of an embodiment of the utility model.

[0048] Figure 4 It is a three-dimensional structure schematic view of the second guide plate of an embodiment of the utility model.

[0049] BRIEF DESCRIPTION OF DRAWINGS:

[0050] Fan frame 11

[0051] Impeller 12, rotation direction A, upstream area B

[0052] Smoke collecting cavity 2, rotation tangent direction C

[0053] Air inlet 21

[0054] Air outlet 22

[0055] First outer wall surface 221

[0056] Second outer wall surface 222

[0057] First guide plate 3

[0058] First gas outlet end 31

[0059] First gas inlet end 32

[0060] First air inlet mounting hole 33

[0061] First sound absorption hole 34

[0062] First flow guide flange 35

[0063] First air outlet mounting hole 36

[0064] Second flow guide plate 4

[0065] Second air outlet end 41

[0066] Second air inlet end 42

[0067] Second air inlet mounting hole 43

[0068] Second sound absorption hole 44

[0069] Second flow guide flange 45

[0070] Second air outlet mounting hole 46 DETAILED DESCRIPTION

[0071] A preferred embodiment is described below in conjunction with the accompanying drawings so as to make the utility model more clear and complete.

[0072] As Figure 1 , Figure 2 shown, the present embodiment provides an oil fume extractor, which is a low-suction and ultra-thin oil fume extractor. The smoke collecting cavity 2 is an ultra-thin smoke collecting cavity, which occupies less kitchen space, is convenient for users to install, and makes the user have more space to move when cooking, thereby improving the user's experience. The centrifugal fan is located in the fan frame 11 above the smoke collecting cavity 2. Generally, a double-suction multi-blade centrifugal fan is used, and the main component is an impeller 12. The impeller 12 is driven by a motor to rotate in the rotation direction A (as Figure 2 shown, the present embodiment rotates counterclockwise). The smoke collecting cavity 2 is located upstream of the impeller 12, that is, the smoke collecting cavity 2 is arranged in the upstream region B of the impeller 12, so as to generate negative pressure by the rotation of the impeller 12 to suck air from the air inlet 21 of the smoke collecting cavity 2 to the air outlet 22. In order to consider both left and right stove heads, the air inlet 21 of the smoke collecting cavity 2 is a horizontal strip rectangle. After the gas enters the smoke collecting cavity 2, due to the narrow channel, the airflow is accelerated upward under the driving of the negative pressure of the impeller 12. At the air outlet 22 of the smoke collecting cavity 2, the channel area is contracted, and the airflow is further accelerated here. The smoke collecting cavity 2 is rectangular, which is easy to generate vortex and flow separation in the right-angle region in the cavity.

[0073] Even if a straight-plate guide structure is installed at the corner of the smoke collection chamber 2 to interfere with the formation of gas vortices, it will still have a negative effect on the aerodynamic performance and smoke extraction effect of the range hood because it does not conform to the flow characteristics at this location. Furthermore, since the impeller 12 rotates in one direction to intake air, there is circumferential non-uniformity in the airflow, resulting in differences in the flow field on the left and right sides of the smoke collection chamber. A uniform straight-plate guide structure cannot effectively solve the problems of gas vortex and flow separation. If the design is unreasonable, it will actually worsen the performance of the range hood and increase noise.

[0074] Therefore, to address the aforementioned issues, an arc-shaped first guide plate 3 and a second guide plate 4 are provided within the smoke collection chamber 2. Two guide plates are arranged along the rotational tangent direction C within the upstream region B, specifically, the first guide plate 3 is positioned on the first side of the smoke collection chamber 2 facing away from the rotational tangent direction C, and the second guide plate 4 is positioned on the second side of the smoke collection chamber 2 facing the rotational tangent direction C. This reduces gas vortices and flow separation generated in the corresponding corner areas, mitigating the adverse effects of the corner areas on the aerodynamic performance and noise of the range hood. Specifically, in this embodiment, the impeller 12 rotates counterclockwise, and the smoke collection chamber 2 is located below the impeller. Therefore, the rotational tangent direction C is from left to right, with the first guide plate 3 located on the left side of the smoke collection chamber 2 and the second guide plate 4 located on the right side.

[0075] The outer arc surface of the first guide plate 3 faces the air inlet 21, and the first guide plate 3 has a first air outlet end 31 near the air outlet 22; the inner arc surface of the second guide plate 4 faces the air inlet 21, and the second guide plate 4 has a second air outlet end 41 near the air outlet 22; this can adapt to the flow characteristics of the corner areas on both sides, further improve the smoke collection effect of the smoke collection chamber 2, and reduce the adverse effects of the corner areas on the aerodynamic performance and noise of the range hood.

[0076] By connecting the first air outlet 31 to the first outer wall surface 221 near the first side of the air outlet 22 and the second air outlet 41 to the second outer wall surface 222 near the second side of the air outlet 22, the adverse effects of the narrow tubes formed between the first guide plate 3 and the first outer wall surface 221, and between the second guide plate 4 and the second outer wall surface 222 on the aerodynamic performance and noise of the range hood can be avoided.

[0077] like Figure 3 As shown, in this embodiment, the tangential direction of the first outlet end 31 coincides with the first outer wall surface 221. This allows for further adaptation to the gas flow characteristics around the first outlet end 31. In other embodiments, the angle between the tangential direction of the first outlet end and the first outer wall surface 221 is set as the first outlet angle, which can also take other values ​​within the range of 0°-15°.

[0078] In this embodiment, the first guide plate 3 also has a first air inlet end 32 near the air inlet 21, and the smoke collection chamber 2 has a first inner wall surface near the first side. The angle between the tangent direction of the first air inlet end 32 and the first inner wall surface is set as the first air inlet angle α, where α = 60°. This allows for further adaptation to the gas flow characteristics around the first air inlet end 32. Of course, in other embodiments, the first air inlet angle can also take other values ​​within the range of 30°-60°.

[0079] In this embodiment, the range hood also includes a first air inlet fixing member (not shown in the figure) and a first air outlet fixing member (not shown in the figure). The first air inlet 32 ​​has a first air inlet mounting hole 33, through which the first air inlet fixing member passes to fix the first air inlet 32 ​​to the first inner wall surface. The first air outlet 31 has a first air outlet mounting hole 36, through which the first air outlet fixing member passes to fix the first air outlet 31 to the first outer wall surface 221. This allows for a relatively simple structure that keeps both the first air inlet 32 ​​and the first air outlet 31 stable in the airflow. Of course, in other embodiments, the first air inlet and the first air outlet can also be fixed using adhesive, snap-fit, or other structures.

[0080] In this embodiment, the first guide plate 3 is provided with a plurality of first sound-absorbing holes 34. The ratio of the perforation area of ​​the first sound-absorbing hole 34 to the total area of ​​the first guide plate 3 is 8%, the diameter of the first sound-absorbing hole 34 is 2mm, and the distance between adjacent first sound-absorbing holes 34 is 8mm. This can further reduce the aerodynamic noise in the smoke collection chamber 2. Of course, in other embodiments, the ratio of the perforation area of ​​the first sound-absorbing hole to the total area of ​​the first guide plate can also be other values ​​within the range of 3%-8%, the diameter of the first sound-absorbing hole can also be other values ​​within the range of 1mm-3mm, and the distance between adjacent first sound-absorbing holes can also be other values ​​within the range of 6mm-8mm.

[0081] In this embodiment, the first guide plate 3 has a first guide flange 35 on its side, and the first guide flange 35 is perpendicular to the inner arc surface of the first guide plate 3; the width D1 of the first guide flange 35 is 6mm, which can improve the strength of the first guide plate 3. Of course, in other embodiments, the angle between the first guide flange and the inner arc surface of the first guide plate can be other values ​​within the range of 80°-100°, and the width of the first guide flange can be other values ​​within the range of 4mm-6mm.

[0082] like Figure 4 As shown, in this embodiment, the angle between the tangent direction of the second outlet end 41 and the second outer wall surface 222 is set as the second outlet angle β, where β = 60°. This allows for further adaptation to the gas flow characteristics around the second outlet end 41. Of course, in other embodiments, the second outlet angle can also take other values ​​within the range of 30°-60°.

[0083] In this embodiment, the second baffle 4 also has a second air inlet end 42 close to the air inlet 21, and the smoke collecting cavity 2 has a second inner wall surface close to the second side. The tangent direction of the second air inlet end 42 is parallel to the second inner wall surface. In this way, the gas flow characteristics of the second air inlet end 42 can be further adapted. Of course, in other embodiments, the included angle between the tangent direction of the second air inlet end 42 and the second inner wall surface is set as a second air inlet angle, and the second air inlet angle can also take other values in the range of 0°-15°.

[0084] In this embodiment, the range hood also includes a second air inlet end fixing member (not shown in the figure) and a second air outlet end fixing member (not shown in the figure). The second air inlet end 42 is provided with a second air inlet mounting hole 43, and the second air inlet end fixing member is arranged in the second air inlet mounting hole 43 to fix the second air inlet end 42 to the second inner wall surface. The second air outlet end 41 is provided with a second air outlet mounting hole 46, and the second air outlet end fixing member is arranged in the second air outlet mounting hole 46 to fix the second air outlet end 41 to the second outer wall surface 222. In this way, the second air inlet end 42 and the second air outlet end 41 can be maintained stable in the airflow with a relatively simple structure. Of course, in other embodiments, the second air inlet end and the second air outlet end can also be fixed by bonding, clamping, or other structures.

[0085] In this embodiment, the second baffle 4 is provided with a plurality of second sound absorbing holes 44, and the ratio of the perforated area of the second sound absorbing holes 44 to the total area of the second baffle 4 is 8%. The diameter of the second sound absorbing holes 44 is 2mm, and the hole distance between adjacent second sound absorbing holes 44 is 8mm. In this way, the aerodynamic noise in the smoke collecting cavity 2 can be further reduced. Of course, in other embodiments, the ratio of the perforated area of the second sound absorbing holes to the total area of the second baffle can also take other values in the range of 3%-8%, the diameter of the second sound absorbing holes can also take other values in the range of 1mm-3mm, and the hole distance between adjacent second sound absorbing holes can also take other values in the range of 6mm-8mm.

[0086] In this embodiment, the side edge of the second baffle 4 is provided with a second flow guide flange 45, which is perpendicular to the inner arc surface of the second baffle 4. The width D2 of the second flow guide flange 45 is 6mm, which can improve the strength of the second baffle 4. Of course, in other embodiments, the included angle between the second flow guide flange and the inner arc surface of the second baffle can also take other values in the range of 80°-100°, and the width of the second flow guide flange can also take other values in the range of 4mm-6mm.

[0087] The range hood of this embodiment was printed and tested, and the experimental results are as follows:

[0088]

[0089] It can be seen that compared with the prototype without the first guide plate 3 and the second guide plate 4, the embodiment achieves the effects of increasing air volume, improving total pressure efficiency and maintaining almost consistent noise under the condition that the impeller rotating speed is basically consistent.

[0090] Although the specific embodiments of the present application are described above, those skilled in the art should understand that this is only an example, the protection scope of the present application is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present application, but these changes and modifications all fall within the protection scope of the present application.

Claims

1. A range hood comprising an impeller, a smoke collecting cavity, said smoke collecting cavity being located upstream of said impeller, air being drawn from an air inlet of said smoke collecting cavity to an air outlet; characterized in that, The arc plate-shaped first flow guide plate and the second flow guide plate are arranged in the smoke collecting cavity, and in the rotational tangential direction of the upstream area of the impeller in the rotation direction of the impeller, the first flow guide plate is located on the first side of the smoke collecting cavity facing away from the rotational tangential direction, and the second flow guide plate is located on the second side of the smoke collecting cavity facing the rotational tangential direction. The outer arc surface of the first flow guide plate faces the air inlet, the first flow guide plate has a first air outlet end close to the air outlet, and the first air outlet end is connected to the first outer wall surface close to the first side of the air outlet. The inner arc surface of the second flow guide plate faces the air inlet, the second flow guide plate has a second air outlet end close to the air outlet, and the second air outlet end is connected to the second outer wall surface close to the second side of the air outlet.

2. The hood as claimed in claim 1, wherein, The angle between the tangential direction of the first air outlet end and the first outer wall surface is set as a first air outlet angle, and the first air outlet angle ranges from 0° to 15°.

3. The hood as claimed in claim 1 wherein, The first flow guide plate also has a first air inlet end close to the air inlet, and the smoke collecting cavity has a first inner wall surface close to the first side. The angle between the tangential direction of the first air inlet end and the first inner wall surface is set as a first air inlet angle, and the first air inlet angle ranges from 30° to 60°; and / or The range of the hole distance between adjacent second sound absorption holes is 6mm-8mm.

4. The hood as claimed in claim 1, wherein, The side edge of the first flow guide plate is provided with a first flow guide flange; The angle between the first flow guide flange and the inner arc surface of the first flow guide plate ranges from 80° to 100°; and / or The width of the first flow guide flange ranges from 4mm to 6mm. The angle between the tangential direction of the second air outlet end and the second outer wall surface is set as a second air outlet angle, and the second air outlet angle ranges from 30° to 60°.

5. The hood as claimed in claim 1, wherein, The second flow guide plate also has a second air inlet end close to the air inlet, and the smoke collecting cavity has a second inner wall surface close to the second side. The angle between the tangential direction of the second air inlet end and the second inner wall surface is set as a second air inlet angle, and the second air inlet angle ranges from 0° to 15°; and / or The range of the hole distance between adjacent second sound absorption holes is 6mm-8mm.

6. The hood according to claim 1, wherein The second flow guide plate is provided with a plurality of second sound absorption holes; 7. The hood according to claim 1, wherein The ratio of the perforated area of the second sound absorption hole to the total area of the second flow guide plate ranges from 3% to 8%; and / or The hole diameter of the second sound absorption hole ranges from 1mm to 3mm; and / or The range of the hole distance between adjacent second sound absorption holes is 6mm-8mm.

8. The hood according to claim 1, wherein ​ ​ ​ ​ 9. The hood according to claim 1, wherein The side edge of the second flow guide plate is provided with a second flow guide flange; An included angle between the second flow guide flange and the inner arc surface of the second flow guide plate ranges from 80° to 100°; and / or The width of the second flow guide flange ranges from 4 mm to 6 mm.

10. The hood according to claim 1, wherein The range hood further comprises a first air outlet end fixing member, the first air outlet end is provided with a first air outlet mounting hole, the first air outlet end fixing member is arranged in the first air outlet mounting hole, and the first air outlet end is fixed to the first outer wall surface; and / or The range hood further comprises a second air outlet end fixing member, the second air outlet end is provided with a second air outlet mounting hole, the second air outlet end fixing member is arranged in the second air outlet mounting hole, and the second air outlet end is fixed to the second outer wall surface.

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