Noise reduction range hood and control method thereof

Abstract

The present invention relates to a noise-reducing range hood and its control method. The range hood comprises: a housing having an air inlet at its bottom; a fan disposed within the housing; and a noise reduction device comprising a first movable noise reduction plate, a first noise reduction chamber formed between the first movable noise reduction plate and the sidewall of the housing, and first noise reduction holes disposed on the first movable noise reduction plate, which communicate with the first noise reduction chamber. The fan can be driven by a drive mechanism to move up and down relative to the housing to change its distance from the air inlet of the housing. The first movable noise reduction plate is linked to the fan and can move relative to the sidewall of the housing during the upward and downward movement of the fan, thereby adjusting the volume of the first noise reduction chamber. The range hood can adjust the airflow path from the range hood inlet to the fan inlet according to different air volume operating conditions, thereby improving the noise reduction effect.

Description

Technical Field

[0001] The present invention relates to the technical field of range hoods, and in particular to a noise-reducing range hood and a control method thereof. Background Art

[0002] Range hoods are kitchen appliances that purify the kitchen environment. The noise generated during operation can affect people's cooking experience and health. Range hood noise primarily comes from impeller rotation noise and broadband eddy current noise. Existing range hoods experience significant eddy currents, which vary significantly under different operating conditions, placing a higher demand on noise reduction. Currently, optimization of fan system structures, such as the volute impeller, or the addition of noise reduction measures, such as sound-absorbing cotton, are common approaches to noise reduction.

[0003] For example, the Chinese invention patent No. 201310627547.X (authorization announcement No. CN 103697512 B) discloses a silent range hood. The range hood is provided with a sound-absorbing air guide cover at the front air inlet facing the volute, and microholes are provided on the sound-absorbing air guide cover. The rear panel of the sound-absorbing air guide cover facing the front air inlet is tilted so that the diameter of the front oil fume channel between the sound-absorbing air guide cover and the front air inlet of the volute gradually decreases from bottom to top, thereby accelerating the airflow to rise and guiding it into the front air inlet of the volute. Although the micropores in the silent range hood have the effect of absorbing and reducing noise, and the tilted setting of the rear panel has the effect of accelerating the airflow and allowing it to quickly enter the air inlet, since the noise frequency of common range hoods is mainly distributed around 100HZ~2000HZ, which is low-frequency noise, although the microporous plate sound-absorbing structure in the above patent has a good noise reduction effect, it is very selective in the sound absorption frequency and only has good absorption of noise near the resonance frequency, and its sound absorption frequency band is relatively narrow.

[0004] For example, the Chinese invention patent application with application number CN201810206517.4 (application publication number CN110274276A) discloses a noise-reducing range hood, including a fan frame and a fan. A fan cover is provided on the front side of the fan frame, and a noise reduction device is installed on the fan cover. The noise reduction device includes a fixed noise reduction plate, a first movable noise reduction plate and a noise reduction hole plate. The fixed noise reduction plate is provided on the fan cover, and the fixed noise reduction plate is covered with noise reduction cavities. The noise reduction hole plate is provided on the rear side of the fixed noise reduction plate, and noise reduction holes corresponding to the noise reduction cavities are opened on the noise reduction hole plate. The area where the noise reduction holes are located corresponds to the air inlet of the fan. The first movable noise reduction plate is provided on the front side of the fixed noise reduction plate. The first movable noise reduction plate can move forward and backward relative to the fixed noise reduction plate under the drive of the driving mechanism to adjust the volume of the noise reduction cavity. This noise-reduction range hood can adjust the volume of the noise reduction cavity on the fixed noise reduction plate by moving the first movable noise reduction plate back and forth. According to the Helmholtz resonance principle, the resonance frequency of the noise reduction cavity can be made the same as or matched with the wind noise frequency generated by different gears of the range hood, thereby achieving stepless noise reduction.

[0005] The noise reduction range hood in the above patent still has certain shortcomings. First, the noise reduction device in the patent is aimed at the noise problem generated when the fan is fixed at a set height in the fan frame. It does not take into account the noise problem and the influence of resistance loss caused by the impact of the airflow on the fan volute under different air volumes. Therefore, the noise reduction effect still has certain limitations. Secondly, the range hood is equipped with a noise reduction device on the fan cover on the front side of the fan frame, which is directly opposite the fan air inlet. Since the presence of the noise reduction device occupies the air duct space in the box (especially the air duct space in the flow path from the air inlet of the range hood housing to the fan volute inlet), this will inevitably increase the airflow resistance in the air duct. The sound absorption effect, especially in the low-frequency band, is affected by the depth of the sound absorption cavity that can be arranged, resulting in poor effect.

[0006] Therefore, the existing noise reduction range hoods need further improvement. Summary of the Invention

[0007] The first technical problem to be solved by the present invention is to provide a noise-reducing range hood that can adjust the airflow path from the range hood inlet to the fan inlet according to different air volume conditions, thereby improving the noise reduction effect, based on the current status of the existing technology.

[0008] The second technical problem to be solved by the present invention is to provide a noise reduction range hood that can effectively avoid the poor noise reduction effect caused by occupying air duct space in response to the current status of the existing technology.

[0009] The third technical problem to be solved by the present invention is to provide a noise reduction control method for a range hood based on the current status of the existing technology, which can adjust the airflow path from the range hood inlet to the fan inlet according to different air volume conditions, thereby improving the noise reduction effect.

[0010] The fourth technical problem to be solved by the present invention is to provide a noise reduction control method for a range hood based on the current status of the existing technology, which can smoothly introduce the turbulent airflow on the top of the box into the fan inlet according to the different height positions of the fan, thereby further improving the noise reduction effect.

[0011] The technical solution adopted by the present invention to solve the first technical problem is: a noise reduction range hood, comprising:

[0012] The box body has an air inlet at the bottom;

[0013] A fan is arranged in the box;

[0014] The noise reduction device includes a noise reduction plate assembly, the noise reduction plate assembly includes at least one movable noise reduction plate, a noise reduction cavity is constructed between the movable noise reduction plate and the side wall of the box, and noise reduction holes are distributed on the movable noise reduction plate and communicate with the noise reduction cavity;

[0015] The fan can be driven by a driving mechanism to move up and down relative to the box to change the distance from the air inlet of the box. The movable noise reduction plate is linked to the fan and can move relative to the side wall of the box during the up and down movement of the fan to adjust the volume of the noise reduction chamber.

[0016] In the present invention, "the noise reduction plate is linked to the fan" may mean that the power output end of the driving mechanism is directly connected to the fan, and the noise reduction plate is connected to the fan, and the distance between the noise reduction plate and the side wall of the box is changed by the up and down movement of the fan; it may also mean that the power output end of the driving mechanism is directly connected to the noise reduction plate, and the fan is connected to the noise reduction plate, and the fan is driven up and down by the movement of the noise reduction plate.

[0017] The technical solution adopted by the present invention to solve the second technical problem is: the box body includes a fan frame, a front cover plate arranged on the front side of the fan frame, and an air outlet plate arranged on the top of the fan frame; the noise reduction plate assembly includes a first movable noise reduction plate, which is arranged below the air outlet plate in a manner that can move up and down relative to the air outlet plate; the first movable noise reduction plate, the air outlet plate, the upper part of the front cover plate and the upper part of the fan frame jointly define the first noise reduction cavity; the fan is arranged on the bottom wall of the first movable noise reduction plate and can move up and down with the first movable noise reduction plate.

[0018] A corresponding noise reduction device is set at the top position of the box (that is, the air outlet plate), which will not obviously occupy the air duct space in the flow path from the air inlet of the range hood box to the fan volute inlet. Therefore, the airflow resistance in the air duct will not increase significantly, and the volume adjustment range of the first noise reduction chamber is wider, thereby achieving a better effect of targeted stepless noise reduction.

[0019] In order to achieve corresponding communication between the air outlet of the fan and the first opening on the air outlet plate while ensuring that the fan can move up and down, the air outlet plate is provided with a first opening, and the first movable noise reduction plate is provided with a second opening at a position corresponding to the air outlet. The fan includes a volute having an air outlet, and the air outlet is connected to the second opening. Generally, after the air outlet of the fan is connected to the second opening of the first movable noise reduction plate, since the second opening of the first movable noise reduction plate is directly opposite to the first opening of the air outlet plate, even when the first movable noise reduction plate moves up and down relative to the air outlet plate and has a certain distance therebetween, the airflow can be smoothly discharged from the first opening of the air outlet plate into the air outlet cover and the external smoke exhaust pipe. Of course, in order to avoid disturbances in the airflow between the first opening and the second opening, an annular guide wall that can extend to the second opening can also be provided on the first opening.

[0020] In order to ensure the stability of the first movable noise reduction plate and the fan in the up and down movement, the first movable noise reduction plate is constrained by vertical sliding on the inner wall of the fan frame through a slide rail assembly.

[0021] Generally speaking, the driving mechanism can adopt various existing technologies that cooperate with electric push rods, motors and screw slider motion mechanisms. The driving mechanism includes an electric push rod arranged on the top of the air outlet plate, and the output shaft of the electric push rod passes through the air outlet plate and is transmission-connected to the first movable noise reduction plate.

[0022] In order to further improve the noise reduction effect, the first noise reduction cavity is filled with a first sound absorbing member.

[0023] In order to reduce the dead zone of air flow in the corner area at the top of the box and effectively improve the noise problem caused by air flow disturbance in the dead zone, the side wall of the box opposite to the air inlet of the fan is also provided with a guide plate inclined from bottom to top toward the location of the fan.

[0024] In order to enable the guide plate to change its inclination angle according to the up and down movement of the fan, so that the airflow can smoothly enter the inlet of the fan, the bottom of the guide plate is rotatably connected to the side wall of the box, and the top of the guide plate is slidably connected to the first movable noise reduction plate. During the up and down movement of the first movable noise reduction plate, the guide plate is driven by the first movable noise reduction plate and deflected around the bottom of the guide plate to change its inclination angle.

[0025] In order to utilize the space occupied by the guide plate in the box and further improve the noise reduction effect, the noise reduction plate assembly also includes a second movable noise reduction plate. The guide plate and the corresponding part of the side wall of the fan rack and the corresponding part of the first movable noise reduction plate jointly define a second noise reduction cavity. Second noise reduction holes connected to the second noise reduction cavity are distributed on the guide plate. The second noise reduction cavity is also filled with a second sound-absorbing member. The guide plate constitutes the second movable noise reduction plate.

[0026] The deflection movement of the guide plate can be achieved by various motion mechanisms in the prior art that are linked with the first movable noise reduction plate to drive the guide plate to deflect, such as a connecting rod mechanism, a sliding mechanism coordinated with a slide slot slider, etc. In order to facilitate installation and reduce costs, the bottom of the guide plate is hinged to the two opposite side walls of the fan frame through a horizontally extending rotating shaft, and the bottoms of the two opposite side edges of the first movable noise reduction plate have two first slide slots arranged in parallel, and the top of the guide plate has a pin shaft that can be correspondingly slidably limited in the two first slide slots.

[0027] The technical solution adopted by the present invention to solve the third technical problem is: a control method for a noise reduction range hood, comprising the following steps:

[0028] The air volume level information of the fan is obtained, and according to the obtained air volume level information, the movable noise reduction plate is driven by a driving mechanism to move relative to the side wall of the box and to move the fan up and down, thereby adjusting the distance between the fan and the air inlet and the volume of the noise reduction chamber.

[0029] The technical solution adopted by the present invention to solve the fourth technical problem is: a control method for a noise reduction range hood, comprising the following steps:

[0030] Obtain the air volume level information of the fan, and according to the obtained air volume level information, drive the first movable noise reduction plate and the fan up and down through the driving mechanism, thereby adjusting the distance between the fan and the air inlet, the volume of the first noise reduction chamber, the inclination angle of the guide plate, and the volume of the second noise reduction chamber.

[0031] Compared with the existing technology, the advantages of the present invention are: the height of the fan can be adaptively adjusted by the drive mechanism according to the actual air volume conditions, changing the airflow path length from the air inlet of the range hood housing to the fan inlet. At the same time, a first noise reduction chamber of different volumes (for different wind noise frequencies) is provided to ensure that users have a good oil fume extraction effect and sound experience when using the range hood under different back pressure conditions at the range hood outlet. Specifically, when the range hood is operating at high back pressure resistance and low air volume, the fan can be relatively lowered, shortening the airflow path and reducing air inlet resistance losses. At the same time, the volume of the first noise reduction chamber can be correspondingly increased. According to the Helmholtz resonance noise reduction principle, it can enhance the low-frequency noise reduction effect. When the range hood is running with low back pressure resistance and large air volume, the fan can be relatively moved upward to increase the distance from the air inlet of the range hood case to the fan inlet, so that the airflow can have a larger turning path, thereby reducing the impact loss of the airflow hitting the bottom of the volute, and reducing the resistance loss and noise caused by eddy currents. At the same time, the volume of the first noise reduction chamber can be reduced accordingly, so that the resonance frequency of the first noise reduction chamber matches the wind noise frequency under the large air volume state, thereby achieving the purpose of targeted noise reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic diagram of the three-dimensional structure of a range hood according to an embodiment of the present invention;

[0033] Figure 2 is a front view of a range hood according to an embodiment of the present invention;

[0034] Figure 3 A vertical cross-sectional view of the range hood according to an embodiment of the present invention taken along the front-to-back direction (with the fan in a high position);

[0035] Figure 4 A vertical cross-sectional view of the range hood according to an embodiment of the present invention taken along the front-to-back direction (with the fan in a low position);

[0036] Figure 5 for Figure 3 Cross-sectional view at AA in the middle;

[0037] Figure 6 A vertical sectional perspective view of the noise reduction device of the range hood according to an embodiment of the present invention, cut along the front-to-back direction;

[0038] Figure 7 Schematic diagram of the three-dimensional structure of the first movable noise reduction plate according to an embodiment of the present invention. DETAILED DESCRIPTION

[0039] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0040] In the present specification and claims, directional terms such as "front," "back," "up," "down," "left," "right," "side," "top," and "bottom" are used to describe various exemplary structural parts and components of the present invention. However, these terms are used herein for convenience of description only and are based on the exemplary orientations shown in the accompanying drawings. Because the embodiments disclosed herein can be arranged in various orientations, these directional terms are intended for illustrative purposes only and should not be construed as limiting. For example, "up" and "down" are not necessarily limited to directions opposite to or consistent with the direction of gravity.

[0041] See also Figure 1-Figure 7 A noise reduction range hood includes a housing 10 and a fan 30 disposed in the housing 10. The housing 10 includes a fan frame 11 and a smoke collecting hood 14 disposed at the bottom of the fan frame 11. An air inlet 15 is provided at the bottom of the smoke collecting hood 14, and an oil net for filtering oil smoke is provided at the air inlet 15. The fan frame 11 is a U-shaped frame structure as a whole, with a front cover 12 provided at the front opening and an air outlet plate 13 provided at the top opening. Components such as an electrical box are usually arranged on the top of the air outlet plate 13. There is also a first opening 130 on the air outlet plate 13, which is usually a square opening for connecting to the air outlet hood.

[0042] The fan 30 is provided in the fan frame 11. The fan 30 generally comprises a volute 31, an impeller and a motor. The impeller is provided in the volute 31 and is driven to rotate, thereby providing negative pressure for sucking and exhausting oil smoke. The volute 31 of the fan 30 is provided with an air inlet 310 and an air outlet 311, see Figure 3 In this embodiment, the air inlet 310 of the volute 31 corresponds to the rear side plate of the fan frame 11, and the air outlet 311 of the volute 31 is connected to the first opening 130 of the first movable noise reduction plate 41 of the noise reduction device (described in detail below).

[0043] from Figure 3It can be seen that the fan 30 is located directly above the air inlet 15 of the smoke hood 14. The external airflow can directly enter the smoke hood 14 through the air inlet 15, then enter the air duct in the fan frame 11, and finally enter the air inlet 310 of the volute 31. The flow path of the airflow is detailed in Figure 3 Indicated by the hollow arrow.

[0044] The noise reduction device includes a noise reduction panel assembly, which includes at least one movable noise reduction panel. In this embodiment, the noise reduction panel assembly includes a first movable noise reduction panel 41, a second movable noise reduction panel, a first sound absorbing member 62, and a second sound absorbing member 64.

[0045] The first movable noise reduction plate 41 is arranged substantially horizontally, located below the air outlet plate 13. Its shape substantially matches the horizontal cross-section of the fan frame 11. Together with the air outlet plate 13, the upper portion of the front cover 12, and the upper portion of the fan frame 11, the first movable noise reduction plate 41 defines a first noise reduction cavity 61. This cavity 61 is filled with a first sound-absorbing member 62, which can be made of sound-absorbing cotton. The first movable noise reduction plate 41 is provided with a first noise reduction hole 410, which communicates with the first noise reduction cavity 61. The first noise reduction hole 410 in the first movable noise reduction plate 41 is preferably a 2 mm diameter hole with an open area ratio of at least 5%. The hole is not limited to a circular hole and can also be of other shapes or sizes.

[0046] See also Figure 7 In this embodiment, the first movable noise reduction plate 41 is arranged below the air outlet plate 13 in a manner that allows it to move up and down relative to the air outlet plate 13. Specifically, two opposite side walls of the wind frame 11 are each provided with a vertically arranged second fixing frame 22, and the second fixing frame 22 is provided with a vertically opened second slide groove 220. The edge of the first movable noise reduction plate 41 is provided with a pulley 42 that can roll up and down in the second slide groove 220. Among them, a slide groove section is provided on the side wall of the wind frame 11. The slide groove section is a pressed profile that protrudes outward, and the second fixing frame 22 can be arranged in the slide groove section. Based on this, the noise reduction plate still has a regular square structure around it, and only a small amount of necessary sliding clearance, such as 1mm, needs to be left between the surrounding area and the wind frame 11. The above-mentioned pulley 42 and the second slide groove 220 constitute a slide rail assembly.

[0047] When the first movable noise reduction plate 41 is at the uppermost high position, the minimum gap between the air outlet plate 13 and the noise reduction plate is not less than 10 mm, and the thickness of the first sound absorbing member 62 is not less than 10 mm.

[0048] A drive mechanism 71 is provided at the top of the air outlet plate 13. Specifically, the drive mechanism 71 can be an electric push rod or a motor and a screw-slider mechanism that connects to the first movable noise reduction plate 41, thereby driving the first movable noise reduction plate 41 to move up and down. In this embodiment, the drive mechanism 71 is preferably an electric push rod, whose output shaft passes through the air outlet plate 13 and is in transmission connection with the first movable noise reduction plate 41.

[0049] A corresponding first noise reduction chamber 61 is provided at the top position of the housing 10 (i.e., the air outlet plate 13), which does not obviously occupy the air duct space in the flow path from the air inlet 15 of the range hood housing 10 to the inlet of the volute 31 of the fan 30. Therefore, the airflow resistance in the air duct will not be significantly increased, and the volume adjustment range of the first noise reduction chamber 61 is wider, thereby achieving a better effect of targeted stepless noise reduction.

[0050] The fan 30 of this embodiment is movable up and down within the housing 10. Specifically, the fan 30 is mounted on the bottom wall of the first movable noise reduction plate 41 and is capable of moving up and down with the first movable noise reduction plate 41. When the drive mechanism 71 is activated, the first movable noise reduction plate 41 and the fan 30 located thereon move up and down relative to the fan frame 11. This allows the distance between the fan 30 and the air inlet 15 of the housing 10 to be changed, and the volume of the first noise reduction chamber 61 between the air outlet plate 13 and the first movable noise reduction plate 41 to be adjusted.

[0051] The air outlet plate 13 has a first opening 130, and the first movable noise reduction plate 41 has a second opening 411 at a position corresponding to the air outlet 311. The air outlet 311 of the volute 31 of the fan 30 is connected to the second opening 411 of the first movable noise reduction plate 41. Generally, after the air outlet 311 of the fan 30 is connected to the second opening 411 of the first movable noise reduction plate 41, since the second opening 411 of the first movable noise reduction plate 41 is aligned with the first opening 130 of the air outlet plate 13, even when the first movable noise reduction plate 41 moves up and down relative to the air outlet plate 13, air can be smoothly discharged from the first opening 130 of the air outlet plate 13 into the air outlet 311 cover 16 and the external smoke exhaust duct. Of course, to prevent airflow disturbances between the first opening 130 and the second opening 411, an annular guide wall 4110 extending to the second opening 411 can be provided on the first opening 130 to prevent airflow leakage there.

[0052] The fan 30 can move up and down a minimum of 50mm. This design consideration requires that when the fan 30 is in its lowest position, its height H1 (the distance from the top of the fan 30 to the bottom of the housing 10) is limited by the oil screen or rectifier plate at the bottom. This ensures a minimum distance of 30mm between the bottom of the fan 30 and the oil screen or rectifier plate, allowing space for the airflow to be diverted or rectified downward. The fan 30's highest position is affected by the position H2 of the air outlet plate 13 (the distance from the air outlet plate 13 to the bottom of the range hood). Height H1 = H2 - t, where t is the minimum clearance between the air outlet plate and the first movable noise reduction plate.

[0053] The rear side panel of the fan frame 11 also has a guide plate 51 at a location corresponding to the air inlet 310 of the fan 30. The guide plate 51 is tilted from bottom to top toward the location of the fan 30. The tilted guide plate 51 can guide the airflow in the air duct (especially the turbulent airflow at the top of the housing 10) into the air inlet 310 of the volute 31 of the fan 30, thereby effectively reducing the dead zone of the airflow in the corner area of the top of the housing 10 and effectively improving the noise problem caused by the airflow disturbance in the dead zone.

[0054] Because the vertical position of the fan 30 needs to be adjusted for different air volumes, the deflector 51 is designed to be deflectable so that it can adjust its tilt angle as the fan 30 moves up and down, allowing air to flow smoothly into the inlet of the fan 30. The deflector 51 is slightly shorter than the left and right widths of the fan frame 11 to prevent interference, and its width ranges from 50 to 200 mm, preferably 100 mm.

[0055] The bottom of the deflector 51 is provided with a rotating shaft 53 extending left and right. Specifically, the lower edge of the deflector 51 has a folded-back curl, within which the rotating shaft 53 is located. Fixed seats 17 are provided on the left and right side walls of the fan frame 11. Both fixing seats 17 have holes for the rotating shaft 53. The ends of the rotating shaft 53 of the deflector 51 can be inserted into the holes of the rotating shaft 53 of the two fixing seats 17. The bottoms of the two opposing sides of the first movable noise reduction plate 41 have two parallel first fixing brackets 21. The two first fixing brackets 21 are elongated and extend horizontally in the front-to-back direction. The two first fixing brackets 21 have first slide slots 210. The top of the deflector 51 has a pin 52 extending left and right. The two ends of the pin 52 of the deflector 51 are respectively inserted into the first slide slots 210 of the two first fixing brackets 21 and can slide back and forth along the first slide slots 210.

[0056] See also Figure 6The deflector plate 51, the corresponding portion of the sidewall of the fan frame 11, and the corresponding portion of the first movable noise reduction plate 41 collectively define a second noise reduction chamber 63. The deflector plate 51 is provided with second noise reduction holes 510 communicating with the second noise reduction chamber. The second noise reduction chamber 63 is also filled with a second sound absorbing member 64. Generally, the diameter of the second noise reduction holes 510 in the deflector plate 51 is smaller than or equal to the diameter of the first noise reduction holes 410 in the first movable noise reduction plate 41. The deflector plate 51 constitutes the second movable noise reduction plate of this embodiment.

[0057] Because the top of the deflector plate 51 is slidably connected to the bottom wall of the first movable noise reduction plate 41, as the first movable noise reduction plate 41 moves up and down, the deflector plate 51, driven by the first movable noise reduction plate 41, deflects about the rotation axis 53 at its bottom, changing its inclination angle. This allows the rising airflow to smoothly enter the air inlet 310 of the volute 31 of the fan 30. Furthermore, as the fan 30 and the first movable noise reduction plate 41 move up and down, the deflection of the deflector plate 51 also causes the volume of the second noise reduction chamber 63 to change accordingly.

[0058] In this embodiment, the height position of the fan 30 can be adaptively adjusted according to the actual air volume working conditions under the drive mechanism 71, changing the airflow path length from the air inlet 15 of the range hood housing 10 to the fan 30 inlet, while providing first noise reduction chambers 61 of different volumes (for different wind noise frequencies) to ensure that under different back pressure conditions at the range hood outlet, users have good oil smoke extraction effects and sound experience when using the range hood. Among them, when the range hood is running at high back pressure resistance and low air volume, low-frequency composite noise reduction and dead zone control are mainly used. The fan 30 can be relatively low, shortening the airflow path and reducing the air inlet resistance loss. At the same time, the volume of the first noise reduction chamber 61 can be increased accordingly. According to the Helmholtz resonance noise reduction principle, the low-frequency noise reduction effect can be improved. At the same time, the guide plate 51 is tilted toward the side of the volute 31, reducing the flow dead zone above. The first noise reduction hole 410 on the first movable noise reduction plate 41 (at the edge position) If it is in a dead zone of flow, its noise reduction effect is weak and can be covered by the guide plate 51. A second noise reduction hole 510 and a second noise reduction cavity 63 are also provided on the guide plate 51. Since they are closer to the rising airflow, they can effectively exert the noise reduction advantage. In addition, although part of the first noise reduction hole 410 on the upper first movable noise reduction plate 41 will be covered by the guide plate 51, the space between the air outlet plate 13 and the first movable noise reduction plate 41 is increased, and the volume of the first noise reduction cavity 61 is increased. According to the Helmholtz resonance noise reduction principle, the noise reduction effect in the low frequency band can be improved.

[0059] Specifically, according to the Helmholtz resonance principle, the calculation formula for the resonance frequency is: Where f is the resonant frequency of the noise reduction cavity, c is the speed of sound in air, s is the sum of the noise reduction hole areas, V is the cavity volume, and L is the effective neck length of the cavity. This shows that, with other parameters remaining constant, increasing the cavity volume decreases the resonant frequency, while conversely, decreasing the cavity volume increases the resonant frequency. Utilizing the Helmholtz resonance principle, the air column within the noise reduction hole and the air within the cavity form an elastic resonance system. When the frequency of some range hood noise matches the natural frequency of this resonance system, the air column within the hole resonates and rubs violently against the hole wall. This friction converts sound energy into heat, thereby achieving the desired sound attenuation. The cavity volume behind the hole controls the resonant frequency of the peak sound absorption.

[0060] When the range hood is operating with low back pressure resistance and large air volume, the fan 30 can be relatively moved upward to increase the distance from the air inlet 15 of the range hood housing 10 to the inlet of the fan 30, so that the airflow can have a larger turning path, thereby reducing the impact loss of the airflow hitting the bottom of the volute 31, and reducing the resistance loss and noise caused by the vortex. At the same time, the volume of the first noise reduction chamber 61 can be reduced accordingly, and the resonant frequency can be increased, so that the resonant frequency of the first noise reduction chamber 61 matches the wind noise frequency under the large air volume state. According to the Helmholtz resonance noise reduction principle, the high-frequency noise reduction effect can be improved to achieve the purpose of targeted noise reduction. On the other hand, since there are fewer dead zones above the air inlet channel of the fan rack 11, the guide plate 51 can be biased toward one side of the fan rack 11 to increase the volume of the air inlet channel. At this time, the first noise reduction hole 410 on the first movable noise reduction plate 41 is more exposed in the air inlet channel. In this case, the noise reduction is mainly performed by the first noise reduction cavity 61 of the first movable noise reduction plate 41, and the noise reduction of the second noise reduction cavity 63 on the side of the guide plate 51 can help further improve the effect.

[0061] A control method for a noise-reduction range hood comprises the following steps: obtaining air volume level information of the fan 30; and, based on the obtained air volume level information, driving the first movable noise reduction plate 41 and the fan 30 up and down via a driving mechanism 71, thereby adjusting the distance between the fan 30 and the air inlet 15, the volume of the first noise reduction chamber 61, the inclination angle of the guide plate 51, and the volume of the second noise reduction chamber 63.

[0062] Specifically, the air volume level is obtained by additionally setting up a speed acquisition and monitoring module, a static pressure acquisition and monitoring module, etc. to realize the judgment of the operating status of the fan 30. The operating status of the fan 30 can also be obtained through the power board electrical signal to judge the user's working condition. Specifically, it is first necessary to establish a relationship database between the power board electrical signal Xi (such as the module input current) and the range hood operating condition (such as the air volume Q) to establish a mapping relationship. This mapping relationship needs to be obtained through preliminary testing. For example, the air volume is set to 3 air volume intervals, and 2 air volume points Q correspond to 2 electrical signals X, that is, Xmin corresponds to Qmin, and Xmax corresponds to Qmax; then different intervals correspond to different noise reduction plate heights. The three air volume intervals can be a small flow point under high resistance, Q≤8m3 / min, a large air volume point under low resistance, Q≥15m3 / min, and an air volume interval in the middle. The more intervals, the more refined the accuracy. The number of adjustment positions of the first movable noise reduction plate 41 is consistent with the number of air volume points, and each position is evenly distributed.

[0063] Taking three air volume intervals as an example, the control logic is described as follows:

[0064] When the range hood is operating stably, the electrical signal Xi is read, and it is assumed that the initial position of the first movable noise reduction plate 41 is at the highest position M1.

[0065] Based on the following judgment, the feedback is given to the regulating circuit to drive the driving mechanism 71 accordingly:

[0066] 1) When the monitored electrical signal Xi≤Xmin, the driving mechanism 71 controls the first movable noise reduction plate 41 to move downward to the lowest position, preferably a moving distance of 100 mm, and at the same time, drives the upper side of the guide plate 51 to move closer to the volute 31 to a set position;

[0067] 2) When the monitored electrical signal Xi≥Xmax, the position of the first movable noise reduction plate 41 is controlled to remain unchanged;

[0068] 3) When the monitored electrical signal Xmax>Xi>Xmin, the first movable noise reduction plate 41 is controlled to move upward to a set position in the middle, and at the same time, the upper side of the guide plate 51 is driven to move closer to the volute 31 to a set position;

[0069] When the range hood is turned off, the first movable noise reduction plate 41 is driven by the driving mechanism 71 to return to the initial position, and the initial position is the uppermost height position by default.

[0070] The "transmission connection" referred to in the present invention refers to a direct connection between two components or an indirect connection through a transmission mechanism.

Claims

1. A noise-reducing range hood, comprising: The box body (10) has an air inlet (15) at its bottom; A fan (30) is arranged in the box (10); The noise reduction device comprises a noise reduction plate assembly, wherein the noise reduction plate assembly comprises at least one movable noise reduction plate, a noise reduction cavity is constructed between the movable noise reduction plate and the side wall of the box (10), and noise reduction holes are distributed on the movable noise reduction plate and communicate with the noise reduction cavity; The invention is characterized in that: the fan (30) can be driven by a driving mechanism (71) to move up and down relative to the box (10) to change the distance from the air inlet (15) of the box (10); the movable noise reduction plate is linked with the fan (30) and can move relative to the side wall of the box (10) during the up and down movement of the fan (30) to adjust the volume of the noise reduction chamber; The box body (10) includes a fan frame (11), a front cover plate (12) arranged on the front side of the fan frame (11), and an air outlet plate (13) arranged on the top of the fan frame (11); the noise reduction plate assembly includes a first movable noise reduction plate (41); the first movable noise reduction plate (41) is arranged below the air outlet plate (13) in a manner that it can move up and down relative to the air outlet plate (13); the first movable noise reduction plate (41) and the air outlet plate (13), the upper part of the front cover plate (12) and the upper part of the fan frame (11) jointly define a first noise reduction chamber (61); the fan (30) is arranged on the bottom wall of the first movable noise reduction plate (41) and can move up and down with the first movable noise reduction plate (41); The fan comprises a volute, an impeller and a motor. The impeller is arranged in the volute and is driven to rotate by the motor.

2. The noise reduction range hood according to claim 1, characterized in that: The air outlet plate (13) is provided with a first opening (130); the first movable noise reduction plate (41) is provided with a second opening (411) at a position corresponding to the air outlet (311); the fan (30) includes a volute (31), the volute (31) has an air outlet (311), and the air outlet (311) is connected to the second opening (411).

3. The noise reduction range hood according to claim 1, characterized in that: The first movable noise reduction plate (41) is vertically slidably constrained on the inner wall of the fan frame (11) via a slide rail assembly.

4. The noise reduction range hood according to claim 1, characterized in that: The driving mechanism (71) includes an electric push rod disposed on the top of the air outlet plate (13), and the output shaft of the electric push rod passes through the air outlet plate (13) and is transmission-connected to the first movable noise reduction plate (41).

5. The noise reduction range hood according to claim 1, characterized in that: The first noise reduction cavity (61) is filled with a first sound absorbing member (62).

6. The noise reduction range hood according to any one of claims 1 to 5, characterized in that: The box body (10) further has a guide plate (51) on the side wall opposite to the air inlet (310) of the fan (30), which is inclined from bottom to top toward the location of the fan (30).

7. The noise reduction range hood according to claim 6, characterized in that: The bottom of the guide plate (51) is rotatably connected to the side wall of the box (10), and the top of the guide plate (51) is slidably connected to the first movable noise reduction plate (41). When the first movable noise reduction plate (41) moves up and down, the guide plate (51) is driven by the first movable noise reduction plate (41) to deflect around the bottom of the guide plate (51) to change its inclination angle.

8. The noise reduction range hood according to claim 7, characterized in that: The noise reduction plate assembly also includes a second movable noise reduction plate. The guide plate (51), the corresponding portion of the side wall of the fan frame (11), and the corresponding portion of the first movable noise reduction plate (41) jointly define a second noise reduction cavity (63). Second noise reduction holes (510) communicating with the second noise reduction cavity (63) are distributed on the guide plate (51). The second noise reduction cavity (63) is also filled with a second sound absorbing member (64). The guide plate (51) constitutes the second movable noise reduction plate.

9. The noise reduction range hood according to claim 8, characterized in that: The bottom of the guide plate (51) is hinged to two opposite side walls of the fan frame (11) through a horizontally extending rotating shaft (53), the bottom of the two opposite sides of the first movable noise reduction plate (41) has two first sliding grooves (210) arranged in parallel, and the top of the guide plate (51) has a pin shaft (52) that can be correspondingly slidably limited in the two first sliding grooves (210).

10. A control method for a noise reduction range hood according to any one of claims 1 to 7, characterized in that The following steps are involved: The air volume level information of the fan (30) is obtained, and based on the obtained air volume level information, the movable noise reduction plate is driven to move relative to the side wall of the box (10) and the fan (30) is driven to move up and down by a driving mechanism (71), thereby adjusting the distance between the fan (30) and the air inlet (15) and the volume of the noise reduction chamber.

11. A control method for a noise reduction range hood according to any one of claims 8 to 9, characterized in that The following steps are involved: The air volume level information of the fan (30) is obtained, and according to the obtained air volume level information, the first movable noise reduction plate (41) and the fan (30) are driven to move up and down by a driving mechanism (71), thereby adjusting the distance between the fan (30) and the air inlet (15), the volume of the first noise reduction chamber (61), the inclination angle of the guide plate (51), and the volume of the second noise reduction chamber (63).

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