CN110822505B

CN110822505B - Smoke exhaust ventilator

Info

Publication number: CN110822505B
Application number: CN201810909458.7A
Authority: CN
Inventors: 宋祖龙; 蒋济武
Original assignee: Foshan Shunde Midea Washing Appliances Manufacturing Co Ltd
Current assignee: Foshan Shunde Midea Washing Appliances Manufacturing Co Ltd
Priority date: 2018-08-10
Filing date: 2018-08-10
Publication date: 2021-05-25
Anticipated expiration: 2038-08-10
Also published as: CN110822505A

Abstract

The invention discloses a range hood, comprising: a frame; the fan comprises a volute and a driving piece, a first air inlet is formed in a first end face of the volute, a second air inlet is formed in a second end face of the volute, an air passing cavity communicated with the first air inlet and the second air inlet is formed in the volute, the driving piece is arranged at the second air inlet, an air outlet communicated with an air outlet and the air passing cavity is formed in the peripheral face of the volute, the volute is obliquely arranged relative to the vertical central line of the rack so that the first end face of the volute and the first inner wall of the rack jointly define an expansion flow channel, the expansion flow channel is communicated with the first air inlet and the air inlet, and the flow area is increased along the air inlet direction; and the sound absorption component is arranged on the first inner wall of the rack and/or the second inner wall of the rack. According to the range hood disclosed by the invention, the expanded flow channel with the flow area increased along the air inlet direction is formed at the air inlet front end of the first air inlet, so that the radiation noise outwards from the inside of the rack can be effectively controlled.

Description

Smoke exhaust ventilator

Technical Field

The invention relates to the technical field of kitchen equipment, in particular to a range hood.

Background

The range hood in the related art is developing towards the direction of large air volume, large wind pressure and small noise (namely silence). Generally, the optimization of noise in the range hood has two modes of active noise reduction and passive noise reduction, and due to the factors of simple structure, low cost and the like, the passive noise reduction mode is applied more and more.

For example, a sound absorption dome is arranged in the frame to form a flow passage which is gradually reduced from bottom to top, so that the radiation noise at the air outlet of the volute is reflected downwards. However, the noise-reducing structure still has reflected noise, and the tapered flow passage forms a downward bell mouth facing the air suction port of the frame, so that the noise can be diffused outwards through the guide plate, and the noise is increased. For another example, a sound absorption module with the same cross-sectional area from top to bottom is arranged in the rack to form a flow channel with the constant flow area from top to bottom, and although the structure can weaken the outward radiation noise to a certain extent, the structure does not reasonably guide the radiation noise, and still has a part of noise radiating outward from the inside of the rack.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides the range hood which can effectively control the radiation noise outwards from the inside of the rack.

The range hood according to the embodiment of the invention comprises: the air conditioner comprises a frame, a first air inlet, an air outlet, a first inner wall and a second inner wall, wherein the first inner wall and the second inner wall are arranged oppositely; the fan is arranged in the rack and positioned between the air suction port and the air exhaust port, the fan comprises a volute and a driving piece, a first end face of the volute is provided with a first air inlet, a second end face of the volute is provided with a second air inlet, the volute is internally provided with an air passing cavity communicated with the first air inlet and the second air inlet, the driving piece is arranged at the second air inlet, the peripheral face of the volute is provided with an air outlet communicated with the air exhaust port and the air passing cavity, the volute is obliquely arranged relative to the vertical center line of the rack so that the first end face of the volute and the first inner wall of the rack jointly define an expansion flow channel, the expansion flow channel is communicated with the first air inlet and the air suction port, and the flow area is increased along the air inlet direction from the air suction port to the air passing cavity; at least one sound absorbing component is arranged on the first inner wall of the rack and/or the second inner wall of the rack.

According to the range hood provided by the embodiment of the invention, the expanded flow channel with the flow area increased along the air inlet direction is formed at the air inlet front end of the first air inlet, so that the radiation noise outwards from the inside of the rack can be effectively controlled.

In addition, the range hood according to the embodiment of the invention also has the following additional technical characteristics:

according to some embodiments of the invention, the sound absorbing assembly has an expanding surface disposed toward the first air inlet or the second air inlet, and a distance between the expanding surface and the first end surface or the second end surface of the scroll increases in the air intake direction.

Further, the diverging surface includes at least one of a decelerating surface and a rectifying surface, the decelerating surface extends obliquely outward in the intake direction, and a distance between the rectifying surface and the first inner wall or the second inner wall of the housing is constant in the intake direction.

Optionally, an accelerating surface is arranged in the machine frame, the accelerating surface is connected with the edge of the expanding surface, which is adjacent to the suction port, and the accelerating surface extends in an inward inclined manner along the air inlet direction to define a contraction flow channel, which communicates the expanding flow channel and the suction port, together with the volute.

In some embodiments of the invention, the edge of the diverging surface adjacent to the suction opening is closer to the suction opening than the first or second inlet opening, and the edge of the accelerating surface remote from the suction opening is located at the bottom of the scroll in the air intake direction.

In some embodiments of the invention, the diverging surface comprises the decelerating surface and the rectifying surface, the rectifying surface being located between the decelerating surface and the accelerating surface.

Optionally, the number of the rectifying surfaces is multiple, and the distance between the multiple rectifying surfaces and the first inner wall or the second inner wall of the rack decreases in a stepped manner along the air intake direction.

Advantageously, the included angle between the tangent plane at any point on the decelerating surface and the first inner wall or the second inner wall of the frame is alpha 1, and alpha 1 is more than 0 degrees and less than or equal to 5 degrees.

According to some embodiments of the present invention, a distance between a surface of the sound-absorbing member provided on the first inner wall of the housing, the surface facing the first air inlet, and the first inner wall of the housing is constant in the air intake direction or extends obliquely inward in the air intake direction.

According to some embodiments of the present invention, a distance between a surface of the sound-absorbing member provided on the second inner wall of the housing facing the second air inlet and the second inner wall of the housing is constant in the air intake direction or extends obliquely inward in the air intake direction.

According to some embodiments of the invention, the angle of inclination of the volute with respect to the vertical centre line of the frame is α 2, 0 ° < α 2 ≦ 5 °.

According to some embodiments of the present invention, the sound-absorbing member is made of a sound-absorbing material and is bonded to the frame, or a sound-absorbing cavity is defined between the sound-absorbing member and the frame, and the sound-absorbing member is provided with a plurality of sound-absorbing holes communicating with the sound-absorbing cavity.

According to some embodiments of the invention, the sound absorbing assembly comprises: a sound-absorbing member made of a sound-absorbing material; the radome fairing, the radome fairing install in frame and cover are established inhale the sound piece, the radome fairing is equipped with a plurality of bloops so that allow the noise to pass the radome fairing.

Further, a sound-deadening cavity is defined between the sound-absorbing piece and the inner surface of the fairing and is communicated with the sound-deadening hole.

Additional aspects and advantages of the invention 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 the invention.

Drawings

FIG. 1 is a cross-sectional view of a range hood according to an embodiment of the present invention;

figure 2 is a perspective view of a sound absorbing assembly of a range hood according to a first alternative embodiment of the present invention;

figure 3 is an exploded view of a sound absorbing assembly of a range hood according to a first alternative embodiment of the present invention;

fig. 4 is a schematic structural diagram of a sound-absorbing assembly of a range hood according to a first alternative embodiment of the present invention;

FIG. 5 is a cross-sectional view taken along line A-A of FIG. 4;

figure 6 is a cross-sectional view of a sound absorbing assembly of a range hood according to a second alternative embodiment of the present invention;

fig. 7 is a cross-sectional view of a sound absorbing assembly of a range hood according to a third alternative embodiment of the present invention.

Reference numerals:

a range hood 1 is provided,

a frame 100, an air inlet 101, an air outlet 102, a first inner wall 103, a second inner wall 104,

a fan 200, a volute 210, a first inlet 211, a second inlet 212, a drive member 220, an impeller 230,

sound absorbing member 300, sound absorbing member 301, cowl 302, muffling hole 303, expanding surface 310, decelerating surface 311, rectifying surface 312, and accelerating surface 320.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

A range hood 1 according to an embodiment of the present invention is described below with reference to the accompanying drawings.

As shown in fig. 1 to 7, a range hood 1 according to an embodiment of the present invention includes: a frame 100, a fan 200 and at least one sound absorbing assembly 300.

Specifically, the rack 100 is placed vertically (i.e., in the up-down direction), the rack 100 has a suction port 101, an exhaust port 102, and a first inner wall 103 and a second inner wall 104 which are disposed opposite to each other, the exhaust port 102 is located above the suction port 101, and the first inner wall 103 is located on the front side of the second inner wall 104. The fan 200 is disposed in the frame 100 and located between the suction port 101 and the exhaust port 102, the fan 200 includes a volute 210 and a driving member 220, a first end surface (i.e., a front end surface) of the volute 210 is provided with a first air inlet 211, and a second end surface (i.e., a rear end surface) of the volute 210 is provided with a second air inlet 212, a gas passing cavity communicating the first air inlet 211 and the second air inlet 212 is disposed in the volute 210, the driving member 220 is disposed at the second air inlet 212, and a gas outlet communicating the exhaust port 102 and the gas passing cavity is disposed on a circumferential surface of the volute 210. The driving member 220 may be a motor, the fan 200 may further include an impeller 230, the impeller 230 is disposed in the volute 210, and the impeller 230 is in transmission connection with the driving member 220.

The volute 210 is disposed obliquely with respect to the vertical center line of the rack 100, so that the first end surface of the volute 210 and the first inner wall 103 of the rack 100 jointly define an expansion flow channel, the expansion flow channel communicates with the first air inlet 211 and the air suction port 101, and the flow area of the expansion flow channel increases along the air intake direction (i.e., from bottom to top) from the air suction port 101 to the air passing chamber. That is, the center axis of the scroll 210 extends obliquely with respect to the horizontal direction and the opening of the first inlet port 211 is obliquely upward and the opening of the second inlet port 212 is obliquely downward.

Here, the volute 210 may be placed front to back, left to right, or offset. "placed front to back" means that the opening of the first air inlet 211 is forward and the opening of the second air inlet 212 is rearward, "placed left to right" means that one of the first air inlet 211 and the second air inlet 212 is leftward and the other is rightward, and "placed offset" means that the opening of the first air inlet 211 is inclined toward both the left-right direction and the front-rear direction.

The sound absorbing assembly 300 is provided on the first inner wall 103 of the rack 100 and/or the second inner wall 104 of the rack 100. In other words, the sound-absorbing member 300 is located inside the rack 100, and the sound-absorbing member 300 may be provided on the first inner wall 103 of the rack 100, or the sound-absorbing member 300 may be provided on the second inner wall 104 of the rack 100, or the sound-absorbing member 300 may be provided in plurality, and the sound-absorbing members 300 are provided on the first inner wall 103 and the second inner wall 104 of the rack 100, respectively.

Therefore, when the range hood 1 works, most of the smoke is sucked into the expansion flow channel from the air suction port 101, enters the air passing cavity from the first air inlet 211 after passing through the expansion flow channel, the rest of the smoke enters the air passing cavity from the air suction port 101 and the second air inlet 212, and finally the smoke is discharged from the air outlet and the air exhaust port 102.

According to the range hood 1 of the embodiment of the invention, the expanded flow channel with the flow area increased along the air inlet direction is formed at the air inlet front end of the first air inlet 211, so that the radiation noise outwards from the inside of the rack 100 can be effectively controlled. Here, "outward" refers to a direction away from the center of the rack 100, and similarly, "inward" refers to a direction toward the center of the rack 100.

According to some embodiments of the present invention, as shown in fig. 2 to 7, the sound absorbing assembly 300 has an expanding surface 310 disposed toward the first inlet port 211 or the second inlet port 212, and a distance between the expanding surface 310 and the first end surface or the second end surface of the scroll 210 increases in the air intake direction, that is, a distance between the expanding surface 310 and the first inner wall 103 or the second inner wall 104 decreases from bottom to top, thereby facilitating noise control.

Here, the "decrease" may be a gradual decrease or an intermittent decrease, and the present invention is not particularly limited thereto. For example, the diverging surface 310 includes at least one of a decelerating surface 311 and a rectifying surface 312: as shown in fig. 5, the diverging surface 310 includes a decelerating surface 311, the decelerating surface 311 extends obliquely outward in the air intake direction (i.e., from bottom to top), and the decelerating surface 311 may be formed of at least one of a flat surface and a curved surface. For example, the decelerating surface 311 is a slanted plane or a curved surface, so that the distance between the expanding surface 310 and the first inner wall 103 or the second inner wall 104 gradually decreases from bottom to top; for another example, the decelerating surface 311 is formed by a plurality of planes with different inclination angles or a plurality of curved surfaces with different curvatures; for another example, the decelerating surface 311 is formed by a slanted plane and a curved surface. The present invention is not particularly limited in this regard.

Alternatively, as shown in fig. 2 to 7, an acceleration surface 320 is provided in the frame 100, the acceleration surface 320 is connected to a rim (i.e., a lower rim) of the expansion surface 310 adjacent to the suction port 101, the acceleration surface 320 extends obliquely inward in the air intake direction to define a constricted flow passage together with the scroll 210, and the constricted flow passage communicates the expansion flow passage and the suction port 101. Like this, the flow area of shrink runner reduces from bottom to top, and shrink runner and expansion runner constitute jointly and follow the runner that intake direction flow area reduces earlier the increase to can avoid the flue gas to reduce by the air current that flow area sudden change leads to when entering the expansion runner by induction port 101, noise increase, noise control better.

The accelerating surface 320 may be formed on the sound absorbing member 300, or may be formed by extending the first inner wall 103 or the second inner wall 104 of the housing 100 in a partially inclined manner. Wherein the acceleration surface 320 may be formed of at least one of a flat surface and a curved surface. For example, the acceleration surface 320 is an inclined plane or a curved surface, i.e., the flow area of the constricted flow passage gradually decreases from bottom to top; for another example, the acceleration surface 320 is formed by a plurality of planes with different inclination angles or a plurality of curved surfaces with different curvatures; for another example, the acceleration surface 320 is formed by a combination of an inclined plane and a curved surface. The present invention is not particularly limited in this regard.

In some embodiments of the present invention, as shown in fig. 2 to 7, the edge (i.e., the lower edge) of the expansion surface 310 adjacent to the suction port 101 is closer to the suction port 101 than the first inlet port 211 or the second inlet port 212, and the edge (i.e., the upper edge) of the acceleration surface 320 far from the suction port 101 is located at the bottom of the scroll 210 in the air intake direction, so that the noise reduction effect is better.

In the example shown in fig. 7, the expansion surface 310 includes a plurality of rectifying surfaces 312, each rectifying surface 312 is parallel to the vertical center line of the rack 100, and the distance between each rectifying surface 312 and the first inner wall 103 or the second inner wall 104 of the rack 100 is constant along the air intake direction, and the distance between each rectifying surface 312 and the first inner wall 103 or the second inner wall 104 of the rack 100 is reduced in a step shape along the air intake direction, so that the distance between the expansion surface 310 and the first inner wall 103 or the second inner wall 104 is discontinuously reduced from bottom to top, that is, the flow area of the expansion flow channel is suddenly changed at the connection position of two adjacent rectifying surfaces 312. In this way, an expanding sound-deadening cavity with an abrupt cross section is formed between the sound-absorbing assembly 300 and the volute 210. Wherein, the position where the above-mentioned sudden change occurs for the first time in the air intake direction is located below the first air inlet 211 or the second air inlet 212 to ensure the sound deadening effect.

In some embodiments of the present invention, as shown in fig. 6, the diverging surface 310 may further include a decelerating surface 311 and a rectifying surface 312, and the rectifying surface 312 is located between the decelerating surface 311 and the accelerating surface 320, that is, the rectifying surface 312 is located below the decelerating surface 311. Therefore, the change of the flow area of the flow channel is gentle, and the noise is small.

Advantageously, as shown in fig. 5 and 6, an included angle between a tangent plane at any point on the decelerating surface 311 and the first inner wall 103 or the second inner wall 104 of the rack 100 is α 1, and in order to avoid that the flow area is too small due to too large α 1 and the overall flow rate of the range hood 1 is affected, α 1 needs to be controlled within a certain range, where α 1 is greater than 0 ° and less than or equal to 5 °.

According to some embodiments of the present invention, as shown in fig. 2, a distance between a surface of the sound-absorbing member 300 provided on the first inner wall 103 of the rack 100 facing the first air inlet 211 and the first inner wall 103 of the rack 100 is constant along the air intake direction, that is, a longitudinal section of the sound-absorbing member 300 is designed to have a uniform cross section in the up-down direction. Alternatively, the distance between the surface of the sound-absorbing member 300 provided on the first inner wall 103 of the housing 100 facing the first air inlet 211 and the first inner wall 103 of the housing 100 extends obliquely inward in the air intake direction.

According to some embodiments of the present invention, a distance between a surface of the sound-absorbing member 300 provided on the second inner wall 104 of the rack 100 facing the second air inlet 212 and the second inner wall 104 of the rack 100 is constant in the air intake direction, that is, a longitudinal section of the sound-absorbing member 300 is of a uniform sectional design in the up-down direction. Alternatively, the distance between the surface of the sound-absorbing member 300 provided on the second inner wall 104 of the rack 100 facing the second air inlet 212 and the second inner wall 104 of the rack 100 extends obliquely inward in the air intake direction.

According to some embodiments of the present invention, as shown in fig. 2, an inclination angle of the volute 210 with respect to the vertical centerline of the rack 100 is α 2, and in order to avoid that the flow area is too small due to too large α 2 and the overall flow rate of the range hood 1 is affected, α 2 needs to be controlled within a certain range, and α 2 is greater than 0 ° and less than or equal to 5 °.

According to some embodiments of the present invention, the sound-absorbing member 300 may be made of a sound-absorbing material, and the sound-absorbing member 300 is bonded to the frame 100, and the surface thereof may be covered with a thin film, thereby preventing oil from being soaked.

Or, a sound absorbing cavity is defined between the sound absorbing assembly 300 and the rack 100, the sound absorbing assembly 300 is provided with a plurality of sound absorbing holes communicated with the sound absorbing cavity, and the plurality of sound absorbing holes are distributed on the decelerating surface 311 and the accelerating surface 320, so that a helmholtz resonant cavity is formed between the sound absorbing assembly 300 and the rack 100, noise in a specific frequency band can be eliminated, the functions of rectifying and emitting noise are achieved, and the noise is sealed inside the rack 100. For example, the aperture of the sound absorption hole is 1mm-10mm, so that the sound absorption effect is good. The sound absorbing assembly 300 may be fixedly connected to the rack 100, or may be integrally formed with the rack 100.

According to some embodiments of the present invention, as shown in fig. 2 to 7, the sound-absorbing assembly 300 includes a sound-absorbing member 301 and a cowling 302, the sound-absorbing member 301 is made of a sound-absorbing material, the cowling 302 is mounted to the rack 100, and the cowling 302 covers the sound-absorbing member 301, and the cowling 302 can protect and fix the sound-absorbing member 301. The fairing 302 is provided with a plurality of silencing holes 303, and the plurality of silencing holes 303 are distributed on the decelerating surface 311 and the accelerating surface 320, so that noise can better pass through the fairing 302 and be eliminated by sound absorption materials. For example, the sound-deadening holes 303 have a hole diameter of 1mm to 10mm, and thus have a good sound-absorbing effect.

Further, a sound attenuation cavity is defined between the sound absorbing piece 301 and the inner surface of the fairing 302 and is communicated with the sound attenuation hole 303, so that the noise of a specific frequency band can be attenuated, and the noise can be better controlled by matching with the sound absorbing piece 301.

Other constructions and operations of the extractor hood 1 according to an embodiment of the present invention are known to those skilled in the art and will not be described in detail herein.

In the description of the present invention, it is to be understood that the terms "central", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "bottom", "inner", "outer", "circumferential", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, should not be construed as limiting the present invention.

Furthermore, the terms "first", "second", "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", "third" may explicitly or implicitly include one or more of the features. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the description of the present invention, "the first feature" and "the second feature" may include one or more of the features. The first feature may be "on" or "under" the second feature and may include the first and second features being in direct contact, or the first and second features being in contact via another feature not being in direct contact. The first feature being "on," "over" and "above" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature.

It should be noted that, in the description of the present invention, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as being fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; either directly or indirectly through intervening media, or through the communication between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "a specific embodiment," "an example" or "some examples" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A range hood, comprising:

the air conditioner comprises a frame, a first air inlet, an air outlet, a first inner wall and a second inner wall, wherein the first inner wall and the second inner wall are arranged oppositely;

the fan is arranged in the rack and positioned between the air suction port and the air exhaust port, the fan comprises a volute and a driving piece, a first end face of the volute is provided with a first air inlet, a second end face of the volute is provided with a second air inlet, the volute is internally provided with an air passing cavity communicated with the first air inlet and the second air inlet, the driving piece is arranged at the second air inlet, the peripheral face of the volute is provided with an air outlet communicated with the air exhaust port and the air passing cavity, the volute is obliquely arranged relative to the vertical center line of the rack so that the first end face of the volute and the first inner wall of the rack jointly define an expansion flow channel, the expansion flow channel is communicated with the first air inlet and the air suction port, and the flow area is increased along the air inlet direction from the air suction port to the air passing cavity;

at least one inhale the sound subassembly, it establishes to inhale the sound subassembly the first inner wall of frame and/or on the second inner wall of frame, inhale the sound subassembly and have the orientation first air inlet or the expansion face that the second air inlet set up, the expansion face with distance between the first terminal surface of spiral case or the second terminal surface is followed the direction of admitting air increases, the expansion face includes speed reduction face and fairing, the speed reduction face is followed the direction of admitting air is leaned out and is extended, the fairing with distance between the first inner wall of frame or the second inner wall is followed the direction of admitting air is unchangeable.

2. The range hood of claim 1, wherein an acceleration surface is disposed in the housing, the acceleration surface is connected to an edge of the expansion surface adjacent to the suction opening, and the acceleration surface extends obliquely inward along the air intake direction to define a constricted flow path with the volute to communicate the expansion flow path with the suction opening.

3. The range hood of claim 2, wherein the edge of the diverging surface adjacent to the suction opening is closer to the suction opening than the first inlet port or the second inlet port, and the edge of the accelerating surface away from the suction opening is located at the bottom of the volute in the air intake direction.

4. The range hood of claim 2, wherein the diverging surface comprises the decelerating surface and the rectifying surface, and the rectifying surface is located between the decelerating surface and the accelerating surface.

5. The range hood of claim 1, wherein the plurality of flow control surfaces are arranged, and the distance between the plurality of flow control surfaces and the first inner wall or the second inner wall of the rack decreases in a stepped manner along the air inlet direction.

6. The range hood according to claim 1, wherein an included angle between a tangent plane at any point on the decelerating surface and the first inner wall or the second inner wall of the rack is α 1, and α 1 is greater than 0 ° and less than or equal to 5 °.

7. The range hood of any one of claims 1-6, wherein the angle of inclination of the volute relative to the vertical centerline of the housing is α 2, 0 ° < α 2 ≦ 5 °.

8. The range hood of any one of claims 1-6, wherein the sound absorbing assembly is made of a sound absorbing material and is bonded to the frame, or,

inhale the sound subassembly with inject between the frame and inhale the sound chamber, inhale the sound subassembly and be equipped with the intercommunication inhale a plurality of sound holes of sound chamber.

9. The range hood of any one of claims 1-6, wherein the sound absorbing assembly comprises:

a sound-absorbing member made of a sound-absorbing material;

the radome fairing, the radome fairing install in frame and cover are established inhale the sound piece, the radome fairing is equipped with a plurality of bloops so that allow the noise to pass the radome fairing.

10. The range hood of claim 9 wherein the sound absorbing member and the inner surface of the cowling define a sound dampening chamber therebetween, the sound dampening chamber in communication with the sound dampening port.