A range hood

Abstract

The utility model discloses a kind of range hood, including air inlet passage, air inlet passage includes box and the air duct in box, air duct has first port and second port, the length direction of air duct is recorded as Z axis direction, the width direction of air duct is recorded as X axis direction, the depth direction of air duct is recorded as Y axis direction, X axis, Y axis and Z axis are perpendicular to each other;Air duct is constituted by the first plate piece and the second plate piece of interval arrangement in box, first plate piece has first boundary, first boundary is the position of first plate piece on XY plane projection closest to the edge of second plate piece at second port, second plate piece, it has second boundary, second boundary is the position of second plate piece on XY plane projection closest to the edge of first plate piece at second port;The projection of first plate piece and second plate piece on XY plane overlaps;Or, the projection of first plate piece and second plate piece on XY plane does not overlap, when the interval of first boundary and second boundary is limited.

Description

Technical Field

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

[0002] As living standards continue to improve, consumers' demands for home appliances have shifted from simple functional needs to diversified quality requirements. Taking range hoods as an example, while ensuring efficient smoke extraction, they also need to operate with low noise. Quiet performance has become one of the core indicators for consumers to evaluate the quality of home appliances, directly affecting the product's market competitiveness and user experience.

[0003] Existing range hoods with noise reduction functions typically target fluid noise. For example, a range hood disclosed in Chinese Patent Application No. 202010220272.8 includes a flue and a fan. The flue is non-linear, and the air inlet of the fan is connected to one end of the flue. This allows the noise generated by the airflow from the fan to be reflected more before leaving the flue and being perceived by the user. The flue uses a core plate to guide the oil fumes along an arc shape, keeping the flow within the flue smooth.

[0004] However, among the noise sources of range hoods, the noise generated by the fan is one of the most significant and prevalent. As a core functional module, the performance of the fan directly affects the smoke extraction effect, so noise reduction cannot be achieved simply by reducing the fan power. Furthermore, since fan noise mainly propagates outward through the air duct, it is also impossible to reduce fan noise by isolating or closing the air duct.

[0005] Therefore, the applicant's application number 202222311210.5 proposes a fan system for a range hood, including an internally hollow air box, a centrifugal fan installed inside the air box, an air inlet and an air outlet on the air box, the outlet of the centrifugal fan being connected to the air outlet, a flow guide and noise reduction frame connected to the air inlet of the air box, a flow guide and noise reduction cavity formed within the flow guide and noise reduction frame, and a flow guide plate installed within the flow guide and noise reduction cavity. By connecting the flow guide and noise reduction frame to the air inlet of the air box, the uneven airflow velocity caused by the cross-sectional change in the air duct can be adjusted. The sound-absorbing cotton installed on the inner sidewall of the flow guide and noise reduction cavity can increase the absorption of noise transmitted downward from the air box, reduce the mechanical vibration noise (such as centrifugal fan, impeller) at the upper end, and reduce some of the aerodynamic noise transmitted downward.

[0006] The aforementioned range hoods achieve noise reduction by setting up a flow-guiding noise reduction frame, optimizing the duct curve design, and combining sound-absorbing materials. However, the outlets and inlets of these ducts are directly opposite each other, and the walls of the ducts are far apart. Noise that does not enter the noise reduction cavity can propagate downwards in a near-direct manner, resulting in limited noise reduction effect. Utility Model Content

[0007] The technical problem to be solved by this utility model is to provide a range hood that can improve noise reduction, addressing the shortcomings of the existing technology.

[0008] The technical solution adopted by this utility model to solve the above-mentioned technical problem is as follows: a range hood, comprising a power unit, an air inlet body, and an air inlet channel, wherein the air inlet channel is disposed between the smoke inlet on the air inlet body and the power unit; characterized in that:

[0009] The air intake channel includes a housing and an air duct located inside the housing. The air duct has a first port as an airflow inlet and a second port as a noise sound wave inlet. The length direction of the air duct is denoted as the Z-axis direction. The first port and the second port are arranged at intervals along the Z-axis direction. The width direction of the air duct is denoted as the X-axis direction, and the depth direction of the air duct is denoted as the Y-axis direction. The X-axis, Y-axis, and Z-axis are perpendicular to each other. The housing has a first opening corresponding to the first port and a second opening corresponding to the second port.

[0010] The air duct is composed of a first plate and a second plate arranged at intervals along the X-axis inside the box. The first plate has a first boundary, which is the position of the first plate that is closest to the edge of the second plate at the second port on the XY plane projection. The second plate has a second boundary, which is the position of the second plate that is closest to the edge of the first plate at the second port on the XY plane projection.

[0011] The projections of the first and second plates onto the XY plane at least partially overlap; or, the projections of the first and second plates onto the XY plane do not overlap along the X-axis, in which case the distance between the projections of the first and second boundaries onto the XY plane is ΔL, and satisfies: Where L1 is the width of the first opening and L2 is the width of the second opening.

[0012] This allows the air duct boundary formed by the two plates to completely shield or form a large shielding range, minimizing the direct downward propagation of noise and improving the noise reduction effect.

[0013] Furthermore, the inner surface of the first plate above the first boundary facing the air duct is the first acoustic surface, and the inner surface of the first plate below the first boundary facing the air duct is the second airflow surface; the inner surface of the second plate below the second boundary facing the air duct is the first airflow surface, and the inner surface of the second plate above the second boundary facing the air duct is the second acoustic surface.

[0014] Each frontal surface faces the direction of sound wave input and impacts the sound wave, and is a wall surface that allows noise to pass through; each frontal surface faces the direction of airflow input and impacts the airflow, and is at least partially a closed wall surface; a noise reduction cavity is formed between the housing and the wall surface constituting the air duct, and at least a portion of the noise reduction cavity corresponds to the frontal surface and the frontal surface on the corresponding side.

[0015] By utilizing the characteristic that airflow and sound waves propagate in opposite directions, the air duct wall of the range hood is divided into two different functional surfaces: the sound-facing surface and the airflow-facing surface. This approach can balance the dual performance indicators of noise reduction and airflow performance, improving both noise reduction and airflow efficiency. In addition, the closed wall design of the airflow-facing surface increases the number of times noise is absorbed, significantly enhancing the noise reduction effect.

[0016] Furthermore, to improve the noise reduction effect, the noise reduction cavity is provided with sound-absorbing materials or structures.

[0017] Furthermore, to improve the noise reduction effect, the equivalent thickness h of the sound-absorbing material or structure in the noise reduction cavity is ≥ λP / 4, where λP is the wavelength corresponding to the noise.

[0018] Compared with the prior art, the advantages of this utility model are as follows: The above-mentioned solution of this utility model enables the air duct boundary formed by the two plates to completely shield or form a large shielding range, thereby avoiding the direct downward propagation of noise as much as possible and improving the noise reduction effect; by utilizing the characteristic that the airflow and sound wave propagation directions are opposite, the air duct wall of the range hood's air intake channel is divided into two different functional surfaces: the sound-facing surface and the airflow-facing surface. This can take into account both noise reduction and flow field performance indicators, improving the noise reduction effect while also achieving good flow field efficiency; in addition, the closed wall design of the airflow-facing surface can increase the number of times noise is absorbed, which can significantly improve the noise reduction effect. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a range hood according to an embodiment of the present utility model;

[0020] Figure 2 This is a partial cross-sectional view of the range hood according to an embodiment of the present utility model;

[0021] Figure 3 This is a partial sectional view (and) of the range hood according to an embodiment of the present utility model. Figure 2 (Different perspectives);

[0022] Figure 4 This is a partial sectional side view of the range hood according to an embodiment of the present utility model;

[0023] Figure 5 This is a schematic diagram of one embodiment of the frontal surface of the noise reduction device of this utility model;

[0024] Figure 6 This is a schematic diagram of an alternative embodiment of the frontal surface of the noise reduction device of this utility model;

[0025] Figure 7 This is a schematic diagram of an alternative embodiment of the frontal surface of the noise reduction device of this utility model;

[0026] Figure 8 This is a schematic diagram of an alternative embodiment of the frontal surface of the noise reduction device of this utility model. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0028] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description. They 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 utility model 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.

[0029] See Figures 1-4 A range hood includes a power unit 200, an air inlet 300, and an air inlet duct 100 disposed between the power unit 200 and the air inlet 300. The power unit 200 may include a housing and a fan disposed within the housing. When the range hood is turned on, the power unit 200 is activated, drawing in cooking fumes through the smoke inlet (not labeled, representing prior art) at the air inlet 300, and then expelling them through the fan 300.

[0030] In this embodiment, the range hood can be a ceiling-mounted type, meaning its power unit 200 is placed above the kitchen ceiling. The power unit 200 is horizontally arranged, meaning it has a downward-facing air inlet 201, and there is sufficient space between the air intake body 300 and the power unit 200 to accommodate the air intake channel 100. Of course, in other types of range hoods, the air intake channel 100 can be of a suitable size depending on the available space, such as being located within the air intake body 300, downstream of the smoke inlet of the air intake body 300.

[0031] The air inlet duct 100 includes a housing 1 and plates disposed within the housing 1. Two plates, a first plate 21 and a first plate 22, are spaced apart from each other. The space between the two plates forms an air duct Q. The first plate 21 can be a single plate or composed of at least two plates joined together; similarly, the second plate 22 can be a single plate or composed of at least two plates joined together. The air duct Q extends between two opposing walls of the housing 1 (each plate contacts its corresponding wall of the housing 1), thus the air duct Q has a first port 211 and a second port 221. The first port 211 serves as both a fluid inlet and a noise outlet, and the second port 221 serves as both a fluid outlet and a noise inlet. The housing 1 has openings at positions corresponding to the first port 211 and the second port 221. In this embodiment, the housing 1 has a first opening 11 corresponding to the first port 211 and a second opening 12 corresponding to the second port 221. In this embodiment, the second port 221 is located at the top of the air duct Q, and the first port 211 is located at the bottom of the air duct Q. Therefore, the second opening 12 is located above the second port 221, and the two can almost overlap, while the first opening 11 is located below the first port 211. The first opening 11 allows oil fumes to enter the housing 1 from the air inlet 300. The bottom of the housing 1 gradually slopes downward from front to back, and the first opening 11 is opened at the bottom of the housing 1, also gradually sloping downward from front to back. The bottom of the air duct Q is horizontal, so the first opening 11 and the first port 211 are a certain distance apart. In the horizontal projection, the first opening 11 can fall within the range of the first port 211. The direction in which the air duct Q extends between the first port 211 and the second port 221 is the length direction (Z-axis direction) of the air duct Q. The first port 211 and the second port 221 are arranged at intervals along the Z-axis direction. Here, "at intervals" does not strictly require that the first port 211 and the second port 221 be aligned in the Z-axis direction (described in detail below), and can be arranged as follows. Figure 4 The diagram shows an aligned arrangement, but a staggered arrangement is also possible. The direction in which the air duct Q extends between the two plates is the width direction of the air duct Q. Figure 4 The X-axis direction is shown in the diagram. Each plate is positioned along the depth of the air duct Q. Figure 4 The direction perpendicular to the paper plane (i.e., the Y-axis direction) shown in the diagram all extends to contact the outer casing 1 to form a relatively enclosed air duct Q.

[0032] Due to the ultra-thin shape limitation of the air inlet 300 in this embodiment, the air duct Q is designed to fit it, forming a long and narrow shape along the left-right direction of the range hood. The two plates are spaced apart along the front-back direction of the range hood, meaning the width direction of the air duct Q is the front-back direction of the range hood. Each plate extends to contact the housing 1 in the depth direction of the air duct Q (i.e., the left-right direction of the range hood in this embodiment) to form a relatively enclosed air duct Q. The airflow enters the first port 211 in the same direction as the length direction of the air duct Q (perpendicular or nearly perpendicular to the first port 211), and the noise wave enters the second port 221 in the same direction as the length direction of the air duct Q (perpendicular or nearly perpendicular to the second port 221).

[0033] Each plate forming the inner surface of the air duct Q includes one or at least two curved surfaces or planes connected end to end. In the cross-section of the plane along the length and width directions of the air duct Q, in this embodiment, it is the vertical plane S (the plane containing the X-axis and Z-axis) extending along the front-back direction of the range hood. Figures 2-4 The cross section and Figure 1 The vertical planes S shown in the diagram coincide or are parallel, with wavy or sawtooth inner surfaces. The curvature of adjacent surfaces can be the same or different. The number of surfaces or planes can also be selected as needed. This forms a non-linear air duct, which helps reduce noise.

[0034] When a range hood is working, cooking fumes are drawn upwards, while the noise from the power unit 200 propagates downwards; that is, the airflow and noise waves propagate in opposite directions. Therefore, based on this characteristic of airflow and sound wave propagation in opposite directions, this invention divides the inner surfaces of each plate into two different functional areas: the sound-facing surface and the airflow-facing surface. The sound-facing surface is the main surface on which sound waves directly incident, aligned with the direction of sound wave propagation. It allows noise waves to pass through, and the airflow does not directly impact this area during its propagation. The airflow-facing surface, on the other hand, is the main surface on which the airflow directly impacts, aligned with the direction of airflow propagation. The airflow-facing surfaces on opposite sides along the X-axis have at least one sound-facing surface and at least one airflow-facing surface, with the sound-facing surface on one side facing the airflow-facing surface on the other.

[0035] The first plate 21 located at the rear has a first boundary 2121, which is the position of the first plate 21 closest to the edge of the second plate 22 at the second port 221 in the XY plane projection. The inner surface of the first plate 21 above the first boundary 2121 facing the air duct Q is the first acoustic surface 231, and the inner surface of the first plate 21 below the first boundary 2121 facing the air duct Q is the second airflow surface 242. See also Figure 4The first boundary 2121 is the most forward-protruding position. The second plate 22 located on the front side has a second boundary 2221, which is the position of the second plate 22 closest to the edge of the first plate 21 at the second port 221 on the XY plane projection. The inner surface of the second plate 22 below the second boundary 2221 facing into the air duct Q is the first airflow-facing surface 241, and the inner surface of the second plate 22 above the second boundary 2221 facing into the air duct Q is the second acoustic-facing surface 232. The first acoustic-facing surface 231 and the first airflow-facing surface 241 are opposite each other along the Y-axis.

[0036] In this embodiment, preferably, each component consists of three interconnected planes or curved surfaces, which can be transitioned between each other using curved surfaces or directly. Thus, the first plate 21 also has a third boundary 2122, where the first acoustic surface 231 extends upward to the third boundary 2122, and the inner surface of the first plate 21 above the third boundary 2122 facing the air duct Q is the third airflow-facing surface 243. The second plate 22 also has a fourth boundary 2222, where the first airflow-facing surface 241 extends downward to the fourth boundary 2222, and the inner surface of the second plate 22 below the fourth boundary 2222 facing the air duct Q is the third acoustic surface 233.

[0037] At each boundary, the two adjacent faces tilt and bend in different directions, where different directions refer to the X-axis direction.

[0038] As mentioned above, the first plate 21 and the second plate 22 each have multiple plates spliced ​​together. Therefore, there may be an incomplete and continuous transition between adjacent frontal and frontal surfaces, or there may be discontinuous extensions on the same surface.

[0039] Each airflow-facing surface is at least partially enclosed. The enclosed surface can be smooth or rough and can reflect noise waves. When the airflow enters upward from the first port 211 (approximately perpendicular to the first port 211), because the second airflow-facing surface 242 on the lower left side of the figure bulges to the right relative to the first port 211, at least part of the airflow will collide with the first airflow-facing surface 242, guiding it and flowing out from the second port 221 after passing through multiple airflow-facing surfaces in sequence.

[0040] The frontal surface is at least partially enclosed. In this invention, "partially enclosed wall" refers to, see [link to relevant documentation]. Figure 5In one embodiment of the partially enclosed frontal surface, a first boundary line S1 is taken along the Z-axis direction, intersecting with both sides of the frontal surface in the Y-axis direction, thereby dividing the frontal surface into two regions along the Z-axis direction, namely the first region S11 and the second region S12. As shown in the figure, the second region S12 is a fully enclosed wall (i.e., without any openings). Alternatively, the first region S11 can also be a fully enclosed wall.

[0041] See Figure 6 In an alternative embodiment where the frontal surface is partially closed, both the first region S11 and the second region S12 have openings. The opening ratio of the second region S12 shown in the figure is ≤20%. These openings in the second region S12 may be for installation or other requirements. The circular holes in the figure represent holes, but it is understood that the shape of the holes is not limited. Alternatively, the first region S11 can be a wall surface with an opening ratio of ≤20%.

[0042] The above Figure 5 , Figure 6 The closed wall shown is located adjacent to the boundary along the Y-axis. Alternatively, see [link to alternative]. Figure 7 An alternative embodiment of partially enclosed frontal surface involves taking two second boundary lines S2 along the Y-axis, arranged parallel to each other along the Z-axis. Each second boundary line S2 intersects both sides of the frontal surface along the Y-axis, thereby dividing the frontal surface along the Z-axis into a third region S21, a fourth region S22, and a fifth region S23. The fourth region S22, located between the two second boundary lines S2, is a fully enclosed wall. Alternatively, see [link to alternative embodiment]. Figure 8 The opening ratio of the fourth region S22 is ≤20%, and the openings in the fourth region S22 may be for installation or other needs.

[0043] The plate area corresponding to each frontal sound surface is composed of perforated plates, sound-absorbing materials, or other materials or structures that allow noise to easily pass through. At least one end of the plate area corresponding to each frontal sound surface extends along the Z-axis to the corresponding wall surface of the housing 1. Thus, the plate area corresponding to the frontal sound surface, the plate area corresponding to the adjacent frontal sound surface, and the corresponding wall surface of the housing 1 together constitute the noise reduction cavity Q1. Figure 4 Taking the noise reduction cavity Q1 on the left side as an example, the plate areas corresponding to the adjacent first frontal surface 231, second frontal surface 242 and third frontal surface 243, as well as the upper side wall and left side wall of the housing 1, together constitute this noise reduction cavity Q1 (acoustic trap).

[0044] Except for the plate area corresponding to the frontal surface, all other walls constituting the noise reduction cavity Q1 are at least partially enclosed walls. Sound-absorbing material or structure 25 is provided inside the noise reduction cavity Q1, which can absorb noise entering the noise reduction cavity Q1. The sound-absorbing material or structure 25 inside the noise reduction cavity Q1 can completely fill the noise reduction cavity Q1, or it may not completely fill the corresponding noise reduction cavity Q1. It can be arranged to fill key areas according to the noise distribution within the noise reduction cavity Q1, or it can be attached to part of the walls constituting the noise reduction cavity Q1.

[0045] Thus, noise enters the air duct Q downwards from the second port 221 (approximately perpendicular to the second port 221). Since the first frontal surface 231 protrudes to the right relative to the second port 221, some noise passes through the plate area corresponding to the first frontal surface 231 and the second frontal surface 232 and enters the corresponding noise reduction cavity Q1. It then undergoes multiple reflections and interferences inside until the sound wave energy is exhausted or only a small portion passes through and re-enters the air duct Q. Meanwhile, some noise is reflected to the first airflow surface 241 opposite to the first frontal surface 231, and then reflects multiple times between the opposing frontal and airflow surfaces, consuming energy. Only a small portion of the noise passes through the first port 211.

[0046] The projections of the first plate 21 and the second plate 22 onto the XY plane at least partially overlap, that is, the first plate 21 at the edge of the second port 221 (first port 211) is located behind the second plate 22 at the edge of the second port 221 (first port 211), while the first boundary 2121 is located in front of the second boundary 2221 (and vice versa, if the left and right directions are similar). Alternatively, the projections of the first boundary 2121 of the first plate 21 and the second boundary 2221 of the second plate 22 onto the XY plane do not overlap, but the distance between the projections of the first boundary 2121 and the second boundary 2221 onto the XY plane (measured based on the boundary projections on the same vertical section) is ΔL, and satisfies: Where L1 is the width of the first port 211 and L2 is the width of the second port 221. This allows the two boundaries to work together to form a complete or large shielding area, minimizing the direct downward propagation of noise and improving noise reduction.

[0047] To enhance sound absorption and noise reduction, the equivalent diameter D of the duct Q is preferably ≤ λP, where the diameter of the inscribed circle at the narrowest point of the duct Q is the equivalent diameter, and λP is the wavelength corresponding to the noise, especially referring to noise in the main frequency band. For example, the noise energy of a range hood is mainly concentrated in the 300Hz~2000Hz range, so the corresponding wavelength λP is 170mm~1133mm. Here, the equivalent diameter refers to the diameter calculated using the area equivalent circle. The equivalent thickness (dimension along the width direction of the duct Q) of the sound-absorbing material or structure 25 is preferably h ≥ λP / 4; the equivalent length l of the channel Q is preferably l ≥ λP / 4, and l ≥ 4D. The equivalent length refers to the height projected onto the YZ plane.

[0048] The rotational speed of the aforementioned power unit 200 can be intelligently voice-controlled. Therefore, the range hood can be equipped with an intelligent voice control module, which includes a controller, a voice receiving module, and a voice parsing module. The voice receiving module can receive user commands, and the voice parsing module can analyze these commands. Based on the analyzed commands, the module controls the range hood to perform corresponding operations, thereby achieving intelligent control of the range hood and improving the user experience. Of course, the dimensions of the aforementioned duct Q and the dimensions of the sound-absorbing material or structure 25 still need to meet the operating conditions under intelligent control.

Claims

1. A range hood, comprising a power unit (200), an air inlet body (300), and an air inlet channel (100), wherein the air inlet channel (100) is disposed between the smoke inlet on the air inlet body (300) and the power unit (200); characterized in that: The air inlet channel (100) includes a housing (1) and an air duct (Q) located inside the housing (1). The air duct (Q) has a first port (211) as an airflow inlet and a second port (221) as a noise sound wave inlet. The length direction of the air duct (Q) is denoted as the Z-axis direction. The first port (211) and the second port (221) are arranged at intervals along the Z-axis direction. The width direction of the air duct (Q) is denoted as the X-axis direction. The depth direction of the air duct (Q) is denoted as the Y-axis direction. The X-axis, Y-axis and Z-axis are perpendicular to each other. The housing (1) has a first opening (11) corresponding to the first port (211) and a second opening (12) corresponding to the second port (221). The air duct (Q) is composed of a first plate (21) and a second plate (22) arranged at intervals along the X-axis direction inside the housing (1). The first plate (21) has a first boundary (2121), which is the position of the first plate (21) on the XY plane projection closest to the edge of the second plate (22) at the second port (221). The second plate (22) has a second boundary (2221), which is the position of the second plate (22) on the XY plane projection closest to the edge of the first plate (21) at the second port (221). The projections of the first plate (21) and the second plate (22) onto the XY plane at least partially overlap; or, the projections of the first plate (21) and the second plate (22) onto the XY plane do not overlap along the X-axis, in which case the distance between the projections of the first boundary (2121) and the second boundary (2221) onto the XY plane is ΔL, and satisfies: Wherein, L1 is the width of the first opening (11) and L2 is the width of the second opening (12).

2. The range hood according to claim 1, characterized in that: The inner surface of the first plate (21) above the first boundary (2121) facing the air duct (Q) is the first acoustic surface (231), and the inner surface of the first plate (21) below the first boundary (2121) facing the air duct (Q) is the second airflow surface (242); the inner surface of the second plate (22) below the second boundary (2221) facing the air duct (Q) is the first airflow surface (241), and the inner surface of the second plate (22) above the second boundary (2221) facing the air duct (Q) is the second acoustic surface (232). Each frontal surface faces the direction of sound wave input and impacts the sound wave, and is a wall surface that allows noise to pass through; each frontal surface faces the direction of airflow input and impacts the airflow, and is at least partially a closed wall surface; a noise reduction cavity (Q1) is formed between the housing (1) and the wall surface constituting the air duct (Q), and at least a portion of the noise reduction cavity (Q1) corresponds to the frontal surface and the frontal surface on the corresponding side.

3. The range hood according to claim 2, characterized in that: The noise reduction cavity (Q1) is provided with sound-absorbing material or structure (25).

4. The range hood according to claim 3, characterized in that: The equivalent thickness h of the sound-absorbing material or structure (25) in the noise reduction cavity (Q1) is ≥ λP / 4, where λP is the wavelength corresponding to the noise.

5. The range hood according to claim 1, characterized in that: The equivalent diameter D of the air duct (Q) is ≤ λP, where λP is the wavelength corresponding to the noise.

6. The range hood according to claim 5, characterized in that: The equivalent length of the air duct (Q) is l≥λP / 4 and l≥4D.

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