A volute structure, centrifugal fan, extractor hood and integrated cooker

Abstract

The present application relates to the technical field of kitchen equipment, and particularly relates to a volute structure, a centrifugal fan, a range hood and an integrated cooker. The first cover plate and the second cover plate of the volute structure are oppositely arranged and form a containing cavity containing an impeller; a ring wall coaming connects the first cover plate and the second cover plate in a preset profile line to enclose an air flow channel, and a terminal end of the air flow channel is provided with an air outlet; the ring wall coaming is locally concave to form an oil leakage hole structure, and the oil leakage hole structure is located in a pressure distribution equal area of the air flow channel; the oil leakage hole structure comprises a circular arc surface and a first opening and a second opening symmetrically arranged on the circular arc surface, the first opening is directed to the first cover plate, and the second opening is directed to the second cover plate, so that the airflow in the air flow channel forms airflow with the same speed and opposite directions when passing through the first opening and the second opening. In this way, the airflow speed in the centrifugal fan can be reduced, the noise can be reduced, different working conditions of the range hood can be coped with, and the smooth flow and collection of the deposited oil are not affected.

Description

Technical Field

[0001] This invention relates to the field of kitchen equipment technology, and in particular to a volute structure, a centrifugal fan, a range hood, and an integrated stove. Background Technology

[0002] When centrifugal fans with a volute structure are used in range hoods, an oil drain hole is provided at the bottom of the volute. The purpose of this is to guide the grease deposited inside the volute to the oil collection box. Currently, the oil drain hole is typically a single hole stamped into the annular wall of the volute, allowing communication between the inside and outside. However, during range hood operation, on the one hand, the oil drain hole at the bottom of the volute allows some aerodynamic noise from inside the volute to propagate out, increasing overall noise; on the other hand, when operating under high-resistance pipe networks, the high-speed airflow through the oil drain hole inside the volute generates exhaust noise. Summary of the Invention

[0003] To address the problem of exhaust noise caused by oil leakage holes at the bottom of the volute during operation in existing range hoods, this invention provides a volute structure, a centrifugal fan, a range hood, and an integrated cooktop.

[0004] On one hand, the present invention provides a volute structure for use in centrifugal fans. The volute structure includes a first cover plate, a second cover plate, and an annular wall plate, wherein:

[0005] The first cover plate and the second cover plate are arranged opposite to each other, and the first cover plate and the second cover plate have holes of equal size, which are used to form a receiving cavity for accommodating the impeller;

[0006] The ring wall panel is connected to the first cover plate and the second cover plate in a preset shape to form an air flow channel, and an air outlet is opened at the end of the air flow channel;

[0007] The ring wall plate is partially concave to form an oil leakage hole structure, which is located in the pressure distribution area of ​​the air flow channel. The oil leakage hole structure includes a circular arc surface and a first opening and a second opening symmetrically arranged on the circular arc surface. The first opening points to the first cover plate, and the second opening points to the second cover plate, so that when the airflow in the air flow channel passes through the first opening and the second opening, it forms an airflow with the same speed and opposite direction.

[0008] Furthermore, the plane where the air outlet is located is at the highest point of the preset profile, and the oil leakage hole structure is located at the lowest point of the preset profile, so that the deposited liquid inside the volute flows out through the oil leakage hole structure under the action of gravity.

[0009] Furthermore, the oil leakage hole structure is smoothly connected to the ring wall plate; the chord length of the arc surface of the oil leakage hole structure is set to 10mm to 20mm; the chord height of the arc surface of the oil leakage hole structure is set to 10mm to 20mm.

[0010] Furthermore, the first opening and the second opening have equal areas and are set at the same height on the arc surface.

[0011] Furthermore, the impeller blade height is L, and the central symmetry plane of the oil leakage hole structure coincides with the impeller rotation surface where 0.4L to 0.6L are located.

[0012] Furthermore, the distance between the center of the first opening and the center of the second opening is d, where 0.1L≤d≤0.2L is set.

[0013] Furthermore, the first included angle between the plane where the first opening is located and the central symmetry plane of the oil leakage hole structure is set to 3° to 5°;

[0014] The second included angle between the plane containing the second opening and the central symmetry plane of the oil leakage hole structure is set to 3° to 5°.

[0015] On the other hand, the present invention provides a centrifugal fan, including an impeller, a motor, and a volute structure as described above.

[0016] On the other hand, the present invention also provides a range hood, including the centrifugal fan as described above.

[0017] On the other hand, the present invention also provides an integrated stove, including the range hood described above.

[0018] By adopting the above technical solution, the present invention has the following beneficial effects:

[0019] This invention utilizes a partially recessed oil-leaking hole structure within the annular wall of the volute structure. This structure includes a curved surface and symmetrically positioned first and second openings on this surface. The first opening points towards a first cover plate, and the second opening points towards a second cover plate. Applying the principle of opposing-phase noise reduction, the oil-leaking hole structure is located in the pressure distribution area of ​​the airflow channel. This ensures that when the airflow passes through the first and second openings, it forms airflows of equal speed but opposite directions, colliding and reducing their speed. As the flow velocity decreases, the sound also decreases, achieving noise reduction. Regardless of the centrifugal fan speed, the airflows through the first and second openings always cancel each other out, thus providing good adaptability to different operating conditions of the range hood. This effectively solves the problem of gas leakage and increased noise caused by the oil-leaking hole in the volute structure under varying pipe network resistances. Furthermore, it does not affect the smooth outflow and collection of deposited grease within the volute structure.

[0020] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and the same reference numerals usually represent the same parts. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the volute structure provided in an embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the centrifugal fan structure provided in an embodiment of the present invention;

[0024] Figure 3 This is a front sectional view of a centrifugal fan provided in an embodiment of the present invention;

[0025] Figure 4 This is a bottom view of a centrifugal fan provided in an embodiment of the present invention;

[0026] Figure 5 Pressure cloud diagrams of the internal flow field of a centrifugal fan provided in this embodiment of the invention and existing centrifugal fans;

[0027] Figure 6 Velocity cloud diagrams of the internal flow field of a centrifugal fan provided in this embodiment of the invention and existing centrifugal fans;

[0028] Figure 7 The velocity contour plots of the centrifugal fan provided in the embodiments of the present invention and existing centrifugal fans under low-resistance operating conditions are shown.

[0029] Figure 8 The velocity contour plots of the centrifugal fan provided in the embodiments of the present invention and existing centrifugal fans under high resistance conditions are shown.

[0030] The following is supplementary explanation of the attached figures:

[0031] 1-Volume structure; 11-First cover plate; 12-Second cover plate; 13-Annular wall plate; 14-Air outlet; 15-Oil leakage hole structure; 2-Impeller Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0033] The term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the invention. In the description of the invention, it should be understood that the terms "upper," "lower," "top," "bottom," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" and "second" may explicitly or implicitly include one or more of that feature. Moreover, the terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein.

[0034] When centrifugal fans with a volute structure are used in range hoods, an oil drain hole is provided at the bottom of the volute. The purpose of this is to guide the grease deposited inside the volute to the oil collection box. Currently, the oil drain hole is typically a single hole stamped into the annular wall of the volute, allowing communication between the inside and outside. However, during range hood operation, on the one hand, the oil drain hole at the bottom of the volute allows some aerodynamic noise from inside the volute to propagate out, increasing overall noise; on the other hand, when operating under high-resistance pipe networks, the high-speed airflow through the oil drain hole inside the volute generates exhaust noise.

[0035] To address the noise issue caused by the oil leakage holes in the volute casing, existing technologies offer the following solutions: two types of oil leakage nozzles, one with the oil leakage hole protruding inwards from the volute casing and the other with the oil leakage hole protruding outwards. These nozzles cover the oil leakage hole, preventing direct communication between the airflow channel and the outside of the volute casing, thus reducing the amount of smoke leakage from the oil leakage hole and lowering the noise generated there. The inner protrusion of the oil leakage nozzle aligns the oil leakage hole with the airflow direction, preventing collision with the main airflow and subsequent gas leakage. The outer protrusion of the oil leakage nozzle reverses the airflow direction, reducing the amount of leakage from the oil leakage hole during forward airflow. Both of these structural solutions can reduce gas leakage within the volute casing under low-resistance operating conditions. However, under high-resistance operating conditions, the increased pressure inside the volute casing leads to increased flow velocity at the oil leakage hole, and both traditional oil leakage hole structures and the aforementioned oil leakage hole solutions will increase exhaust noise to varying degrees.

[0036] Another solution involves installing a sealing device on the volute. This device seals the oil leakage hole when the range hood is operating, preventing airflow from leaking out through the hole. When not in operation, the hole is opened to allow accumulated grease to drain. However, this solution is relatively complex, adding a sealing device to the existing volute oil leakage hole, requiring manual intervention or an additional drive mechanism, and may also result in incomplete sealing.

[0037] Therefore, the existing centrifugal fan casings still need further improvement.

[0038] refer to Figure 1 and Figure 2 As shown, the volute structure provided in this embodiment of the invention is applied to a centrifugal fan. The volute structure 1 includes a first cover plate 11, a second cover plate 12, and an annular wall 13. The first cover plate 11 and the second cover plate 12 are arranged opposite to each other. The first cover plate 11 and the second cover plate 12 have holes of equal size, which are used to form a receiving cavity for accommodating the impeller 2. The annular wall 13 is connected to the first cover plate 11 and the second cover plate 12 in a preset profile to form an air flow channel. An air outlet 14 is opened at the end of the air flow channel.

[0039] Specifically, the first cover plate 11 and the second cover plate 12 have the same shape, both being integrally formed spiral surface structures. The first cover plate 11 and the second cover plate 12 have equally sized circular holes in the spiral surface section to form a receiving cavity for accommodating the impeller 2. The annular wall plate 13 has a preset profile. In this embodiment of the invention, the preset profile can be an integrally formed spiral profile. The edge of the spiral profile is fully matched with the edge of the first cover plate 11 and the second cover plate 12. In order to ensure stable airflow, the annular wall plate 13 can be connected to the first cover plate 11 and the second cover plate 12 by welding.

[0040] The annular wall panel 13, with a preset profile, connects the first cover plate 11 and the second cover plate 12 to form an airflow channel. An air inlet is also provided on either the first cover plate 11 or the second cover plate 12. Air enters the airflow channel through the air inlet. The impeller 2, driven by a motor, rotates its blades, creating airflow within the airflow channel. The airflow circulates in the spiral section of the volute and then reaches the air outlet 14 at the end of the airflow channel for discharge. In one possible embodiment, the plane containing the air outlet 14 is located at the highest point of the preset profile, that is, the spiral profile of the annular wall panel 13.

[0041] The air entering the airflow channel contains oil vapor. Over time, the oil vapor condenses and turns into liquid grease. Therefore, it is necessary to open an oil drain hole at the bottom of the volute to drain the grease.

[0042] In this embodiment of the invention, an oil leakage hole structure 15 is formed by a partial indentation in the annular wall plate 13. The oil leakage hole structure 15 is located in the pressure distribution area of ​​the air flow channel. The oil leakage hole structure 15 includes an arc surface and a first opening and a second opening symmetrically arranged on the arc surface. The first opening points to the first cover plate 11, and the second opening points to the second cover plate 12, so that when the airflow in the air flow channel passes through the first opening and the second opening, it forms an airflow with the same speed and opposite direction.

[0043] Specifically, without affecting the external characteristics of the fan, sheet metal stamping can be used to create a partially concave oil leakage hole structure 15 in the ring wall panel 13. The oil leakage hole structure 15 includes a smooth arc surface and a first opening and a second opening symmetrically arranged on the arc surface. The first opening points towards the first cover plate 11, and the second opening points towards the second cover plate 12. By matching the design of the position and structural dimensions of the oil leakage hole structure 15, it is positioned in the pressure distribution area of ​​the airflow channel. This allows the airflow in the airflow channel to form airflows with the same speed and opposite direction when passing through the first and second openings, thus forming a potential-averaged flow field. This cancels out some of the flow velocity, thereby reducing the noise during the operation of the range hood.

[0044] In one possible implementation, with the highest point of the plane containing the air outlet 14 located on a preset profile as a reference, the oil drain hole structure 15 is specifically located at the lowest point of the preset profile, so that the deposited liquid inside the volute flows out through the oil drain hole structure 15 under the action of gravity. In some embodiments, when the entire volute structure 1 is placed in the centrifugal fan, the air outlet 14 faces upward in the vertical direction, and the oil drain hole structure 15 faces downward in the vertical direction, so that the grease deposited inside the volute flows out through the oil drain hole structure 15 under the action of gravity.

[0045] According to fan flow theory, local concavity in the volute profile can affect the internal flow state or external characteristics of the fan. To further reduce the impact of the oil leakage hole structure 15 on the internal flow field of the volute, its structural dimensions should not be too large. (Reference) Figure 3 As shown, in one possible configuration, the oil leakage hole structure 15 is smoothly connected to the annular wall plate 13; the chord length B of the arc surface of the oil leakage hole structure 15 is set to 10mm to 20mm; and the chord height H of the arc surface of the oil leakage hole structure 15 is set to 10mm to 20mm.

[0046] In one possible configuration, the first and second openings have equal areas and are positioned at the same height on the arc surface. This is because, according to Lighthill's theory, the exhaust noise power is proportional to the sixth power of the gas velocity. Furthermore, by combining the principle of opposing phase cancellation, the exhaust noise is reduced by using the opposing phases of the sound waves to reduce the flow velocity, thereby lowering the exhaust noise.

[0047] In one possible configuration, the blade height of impeller 2 is L, and the central symmetry plane of the oil leakage hole structure 15 coincides with the rotating surface of impeller 2 where 0.4L to 0.6L are located.

[0048] Specifically, as described above, in order to form two opposing airflows of equal size and opposite direction, the oil leakage hole structure 15 is located in the region of equal pressure distribution (or region of small pressure gradient) within the volute casing. According to the flow field distribution of the dual-inlet multi-blade centrifugal fan, the axial velocity distribution of the airflow within the volute casing first increases and then decreases. In the middle region, the higher velocity impacts the volute casing annular wall, causing a local pressure increase. After impacting the volute casing annular wall, the airflow undergoes flow separation, moving towards the front and rear cover plates respectively, impacting the front and rear cover plates again, causing a pressure increase near the cover plates. Therefore, the pressure distribution within the volute casing first decreases, then increases, then decreases again, and then increases again along the axial direction. By matching the design of the oil leakage hole structure 15 to the flow separation region of the volute casing's axial velocity distribution,

[0049] In one possible approach, the distance between the center of the first opening and the center of the second opening is d, where 0.1L≤d≤0.2L is set.

[0050] Specifically, the airflow inside the volute impacts the oil drain hole structure 15, causing flow separation, with the airflow flowing towards the front and rear cover plates respectively. To reduce the secondary flow generated by this flow separation from the oil drain hole and its impact on the stability of the opposing airflow, the distance d between the center of the first opening and the center of the second opening needs to be designed. If the value of d is small, the airflow inside the volute impacts the concave curved surface of the oil drain hole, causing flow separation, and some gas will flow out from the oil drain hole, affecting the noise reduction effect; if the value of d is large, the velocity of the opposing airflow will decrease, also affecting the noise reduction effect. To promote the formation of a relatively stable opposing airflow, a value of 0.1L ≤ d ≤ 0.2L is set.

[0051] refer to Figure 4 As shown, in one possible configuration, the first included angle θ1 between the plane containing the first opening and the central symmetry plane of the oil leakage hole structure 15 is set to 3° to 5°; the second included angle θ2 between the plane containing the second opening and the central symmetry plane of the oil leakage hole structure 15 is set to 3° to 5°.

[0052] Specifically, the circumferential flow of gas inside the volute will generate a certain wake vortex after impacting the concave curved surface of the oil leakage hole. Therefore, setting 3°≤θ1=θ2≤5° can reduce the impact of local vortex on the noise reduction effect of the multi-oil leakage hole structure 15.

[0053] On the other hand, the present invention provides a centrifugal fan, including an impeller 2, a motor, and a volute structure 1 as described above.

[0054] On the other hand, the present invention also provides a range hood, including the centrifugal fan as described above.

[0055] On the other hand, the present invention also provides an integrated stove, including the range hood described above.

[0056] This invention utilizes a partially recessed oil-leaking hole structure within the annular wall of the volute structure. This structure includes a curved surface and symmetrically positioned first and second openings on this surface. The first opening points towards a first cover plate, and the second opening points towards a second cover plate. Applying the principle of opposing-phase noise reduction, the oil-leaking hole structure is located in the pressure distribution area of ​​the airflow channel. This ensures that when the airflow passes through the first and second openings, it forms airflows of equal speed but opposite directions, colliding and reducing their speed. As the flow velocity decreases, the sound also decreases, achieving noise reduction. Regardless of the centrifugal fan speed, the airflows through the first and second openings always cancel each other out, thus providing good adaptability to different operating conditions of the range hood. This effectively solves the problem of gas leakage and increased noise caused by the oil-leaking hole in the volute structure under varying pipe network resistances. Furthermore, it does not affect the smooth outflow and collection of deposited grease within the volute structure.

[0057] To verify that the oil leakage hole structure in the centrifugal fan provided in this embodiment of the invention effectively reduces airflow velocity and exhaust noise, flow field tests were conducted on the centrifugal fan of this invention and existing centrifugal fans, including generating pressure and velocity cloud maps under different operating conditions. (Reference) Figure 5 The diagram shows a comparison of pressure cloud maps of the internal flow field of the centrifugal fan provided by this invention and existing centrifugal fans. The right image shows the pressure cloud map of the internal flow field of the centrifugal fan of this invention, while the left image shows the pressure cloud map of the internal flow field of an existing centrifugal fan. Figure 5 As can be seen from the data, the axial pressure distribution of the flow field inside the centrifugal fan is characterized by a large value in the middle, then gradually decreasing towards the first and second cover plates of the volute, and then increasing again near the first and second cover plates.

[0058] refer to Figure 6 The diagram shows a comparison of velocity cloud maps of the internal flow field of the centrifugal fan provided by this invention and that of existing centrifugal fans. The right diagram shows the velocity cloud map of the internal flow field of the centrifugal fan of this invention, while the left diagram shows the velocity cloud map of the internal flow field of an existing centrifugal fan. Figure 6It can be seen that the axial velocity distribution of the flow field inside the volute is high in the middle and then gradually decreases towards the first and second cover plates of the volute. The main reason for this is that the airflow at the impeller inlet is deflected, and the deflection angle of the airflow at the blade tip is relatively large, affecting the flow velocity. This results in a relatively high flow velocity of the airflow at the impeller outlet at the middle blade height. After the high-speed airflow impacts the volute annular wall, flow separation occurs, and the airflow flows to the front and rear cover plates of the volute and collides with them, resulting in a relatively high pressure distribution in the annular wall and front and rear cover plate areas. Based on the above flow field distribution characteristics, on the basis of the existing volute, by sheet metal stamping of the annular wall, the reverse counter-current oil leakage hole structure of this proposal is designed and matched. This structure is located in the flow separation area where the airflow collides with the annular wall at the bottom of the volute. Furthermore, through parametric design, the boundary of the oil leakage hole structure is located in the pressure potential distribution area, promoting the formation of two stable reverse airflows, thereby achieving the purpose of counter-current flow velocity reduction and exhaust noise reduction.

[0059] Figure 7 , Figure 8 These are schematic diagrams comparing the velocity field distribution of the centrifugal fan provided by this invention with that of existing centrifugal fans under low-resistance and high-resistance operating conditions. Figure 7 The left figure is a comparative diagram of the velocity cloud map of the internal flow field of an existing centrifugal fan under low resistance conditions, while the right figure is the velocity cloud map of the internal flow field of the centrifugal fan of the present invention under low resistance conditions. Figure 8 The left figure is a comparative diagram of the velocity cloud map of the internal flow field of an existing centrifugal fan under high resistance conditions, while the right figure is the velocity cloud map of the internal flow field of the centrifugal fan of the present invention under high resistance conditions.

[0060] from Figure 7 , Figure 8 As can be seen, existing centrifugal fans exhibit relatively low gas flow velocity at the oil leak hole under low-resistance conditions and relatively high gas flow velocity under high-resistance conditions. However, the centrifugal fan provided by this invention exhibits significantly lower airflow velocity at the oil leak hole compared to existing centrifugal fans under both low-resistance and high-resistance conditions. This further demonstrates that the volute structure with a reverse-flush oil leak hole provided by this invention can better match any operating condition of the centrifugal fan, achieving the technical effects of reducing flow velocity and exhaust noise, as well as ensuring implementation stability.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A volute structure, characterized by, The volute structure (1) comprises a first cover plate (11), a second cover plate (12) and a ring wall plate (13): The first cover plate (11) and the second cover plate (12) are oppositely arranged, and the first cover plate (11) and the second cover plate (12) are provided with equal-sized holes for forming a containing cavity for accommodating an impeller (2); The ring wall plate (13) is connected to the first cover plate (11) and the second cover plate (12) in a preset profile to enclose an air flow channel, and a discharge port (14) is formed at the terminal end of the air flow channel; The ring wall plate (13) is partially concave to form an oil leakage hole structure (15), which is located in the pressure distribution equivalent area of the air flow channel; the oil leakage hole structure (15) comprises a circular arc surface and first and second openings symmetrically arranged on the circular arc surface, the first opening is directed to the first cover plate (11), and the second opening is directed to the second cover plate (12), so that the airflow in the air flow channel forms airflow with the same speed and opposite directions when passing through the first and second openings.

2. A spiral casing structure (1) according to claim 1, characterized in that The plane where the discharge port (14) is located is at the highest point of the preset profile, and the oil leakage hole structure (15) is located at the lowest point of the preset profile, so that the deposited liquid in the volute flows out through the oil leakage hole structure (15) under the action of gravity.

3. A spiral casing structure (1) according to claim 1, characterized in that The oil leakage hole structure (15) is smoothly connected with the ring wall plate (13); the chord length of the circular arc surface of the oil leakage hole structure (15) is set to 10mm to 20mm; and the chord height of the circular arc surface of the oil leakage hole structure (15) is set to 10mm to 20mm.

4. A spiral case structure (1) according to claim 1, characterized in that The first and second openings are equal in area and are arranged at the same height on the circular arc surface.

5. A spiral case structure (1) according to claim 1, characterized in that The center of symmetry of the oil leakage hole structure (15) coincides with the impeller (2) rotation surface where 0.4L to 0.6L is located.

6. A spiral case structure (1) according to claim 5, characterized in that The distance between the center of the first opening and the center of the second opening is d, wherein 0.1L≤d≤0.2L is set.

7. A spiral case structure (1) according to claim 1, characterized in that The first included angle between the plane where the first opening is located and the center of symmetry of the oil leakage hole structure (15) is set to 3° to 5°; The second included angle between the plane where the second opening is located and the center of symmetry of the oil leakage hole structure (15) is set to 3° to 5°.

8. A centrifugal fan characterized by The centrifugal fan comprises an impeller (2), a motor and the volute structure (1) according to any one of claims 1 to 7.

9. A range hood characterized by, The centrifugal fan according to claim 8.

10. An integrated hob, characterized in that The range hood according to claim 9.

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