Active noise reduction system and range hood

Abstract

The application belongs to the technical field of kitchen electric appliances, and discloses an active noise reduction system and a range hood. The active noise reduction system comprises a support frame, a noise preprocessing assembly and a pickup assembly. The noise preprocessing assembly is arranged on the support frame and is used for filtering noise of a specific frequency. The pickup assembly is arranged on the support frame and comprises a microphone module. The microphone module is used for collecting noise filtered by the noise preprocessing assembly. The active noise reduction system can ensure sound transmission and noise reduction while preventing wind and oil, prolongs the service life of the microphone module, and realizes full-band noise reduction of the range hood.

Description

Technical Field

[0001] The present invention relates to the field of kitchen appliance technology, and in particular to an active noise reduction system and a range hood. Background Technology

[0002] With the improvement of living standards, range hoods have become a common kitchen appliance for purifying the kitchen environment. They quickly extract and exhaust the exhaust gases from the gas stove and the fumes produced during cooking, reducing indoor oil fume pollution and thus purifying the kitchen air and improving the user's cooking comfort. During operation, the high-speed rotation of the centrifugal fan generates broadband turbulent aerodynamic noise, mainly distributed in the mid-to-low frequency range. Due to the long sound waves, traditional sound absorption and noise reduction measures have limited effectiveness, while active noise cancellation (ANC) technology can effectively suppress fan noise.

[0003] However, the airflow within the duct impacts the microphone diaphragm, generating high-frequency noise such as airflow noise and secondary turbulence noise. This noise, combined with the original noise signal, leads to a decrease in ANC noise reduction, affecting pickup accuracy and noise reduction stability. Summary of the Invention

[0004] The purpose of this invention is to provide an active noise reduction system and range hood that can ensure sound transmission and noise reduction while preventing wind and oil, extend the service life of the microphone module, and achieve full-band noise reduction for the range hood.

[0005] To achieve this objective, the embodiments of the present invention adopt the following technical solutions: An active noise cancellation system, comprising: Support frame; A noise preprocessing component is disposed in the support frame, and the noise preprocessing component is used to filter noise of a specific frequency; A sound pickup component is disposed on the support frame. The sound pickup component includes a microphone module, which is used to collect noise filtered by the noise preprocessing component.

[0006] Preferably, the support frame includes a front panel with multiple perforations, and the noise pretreatment component includes a first sound-absorbing cotton, which is disposed on the inner side of the front panel and covers all the perforations.

[0007] Preferably, the noise pretreatment component further includes a second sound-absorbing cotton, which is disposed on the side of the first sound-absorbing cotton away from the front panel and located above and / or below the sound pickup component.

[0008] Preferably, the first sound-absorbing cotton includes a sound-absorbing layer and non-woven fabric disposed on both sides of the sound-absorbing layer.

[0009] Preferably, the microphone pickup assembly further includes a mounting box and a sound-permeable diaphragm. The mounting box has an opening facing the noise preprocessing assembly. The microphone module is disposed inside the mounting box. The sound-permeable diaphragm is sealed to the mounting box and blocks the opening.

[0010] Preferably, the microphone pickup assembly further includes a flexible support member disposed within the mounting box and located between the microphone module and the acoustic diaphragm, the flexible support member supporting the acoustic diaphragm.

[0011] Preferably, the pickup assembly further includes a first damping pad, which is disposed within the mounting box and located between the mounting box and the microphone module; and / or, The pickup assembly also includes a second vibration damping pad, which is disposed on the outer surface of the mounting box.

[0012] Preferably, the mounting box has an air pressure balancing hole on its side wall facing the noise pretreatment component, the air pressure balancing hole being used to balance the air pressure inside and outside the mounting box.

[0013] Preferably, the pickup assembly further includes a sealing frame that seals and presses the acoustic membrane against the opening of the mounting box and tensions the acoustic membrane.

[0014] A range hood includes the aforementioned active noise reduction system, a main unit housing, and a fan. The active noise reduction system also includes a speaker assembly. Both the fan and the speaker assembly are disposed within the main unit housing. Air inlets are provided on opposite sides of the fan. The sound pickup assembly is disposed on the inner wall of the main unit housing opposite to the air inlets of the fan.

[0015] The beneficial effects of this invention are: This invention provides an active noise reduction system and a range hood. In this active noise reduction system, the support frame serves as the main support structure, ensuring the stability of the system. Simultaneously, the support frame can block large oil droplets and foreign objects while ensuring sound wave propagation, providing protection for the inner noise pre-processing components and the sound pickup components. The noise pre-processing components can filter noise of specific frequencies, enabling the microphone module to isolate high-frequency noise such as airflow noise and secondary turbulence noise, improving sound pickup accuracy. Combined with the speaker components, it can emit noise reduction waves with equal amplitude and opposite phase for low-frequency noise, enhancing noise reduction stability.

[0016] This active noise reduction system improves sound pickup accuracy and noise reduction stability. Through the combination of active noise reduction technologies, it achieves noise reduction across the entire frequency band of the range hood.

[0017] In the range hood of this invention, the active noise reduction system located on both sides of the air inlet of the fan can obtain the sound waves of the noise at this time. The microphone modules are symmetrically arranged and are positioned directly facing the lower edge of the fan. This allows for accurate and full-coverage collection of the original rotational noise of the fan and the coupled noise of the airflow in the duct. This effectively improves the integrity and spatial consistency of the noise sound wave collection. Then, the speaker assembly emits noise reduction waves with the same amplitude and opposite phase as the original noise in real time, forming a spatial sound wave cancellation area inside the main unit. This suppresses the external noise radiation from the smoke collection chamber and the oil filter, achieving a pure hardware, zero-delay, and high-purity active noise reduction effect. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the range hood provided in an embodiment of the present invention; Figure 2 This is a front view of the active noise cancellation system provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the back of the active noise cancellation system provided in an embodiment of the present invention; Figure 4 This is an exploded view of the active noise reduction system provided in an embodiment of the present invention; Figure 5 This is an exploded view of the pickup component provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of the microphone module provided in an embodiment of the present invention.

[0019] In the picture: 1. Main unit case; 2. Fan; 21. Air inlet; 3. Active noise cancellation system; 31. Support frame; 311. Front panel; 312. Side panel; 313. Perforation; 32. Noise pretreatment component; 321. First sound-absorbing cotton; 322. Second sound-absorbing cotton; 33. Sound pickup component; 331. Mounting box; 3311. Opening; 3312. Air pressure equalization hole; 332. Microphone module; 3321. PCB board; 3322. Microphone; 333. Acoustic membrane; 334. Sealing frame; 335. Flexible support component; 336. First vibration damping pad; 337. Second vibration damping pad; 34. Speaker assembly; 4. Smoke collection chamber. Detailed Implementation

[0020] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar components or components having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0021] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," "fixed," "combined," "coupled," and "installed" should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; a direct connection or an indirect connection via an intermediate medium; or the internal communication of two components or the interaction between two components. As examples, a direct connection refers to two parts or components being connected together without the need for an intermediate medium, while an indirect connection refers to two parts or components each being connected to at least one intermediate medium, with the connection achieved through the intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. Furthermore, "connected" and "coupled" are not limited to physical or mechanical connections or couplings, but can also include electrical connections or couplings.

[0022] In the description of this invention, the terms "upper," "lower," "left," "right," "front," and "rear," etc., refer to the orientation or positional relationships shown in the accompanying drawings. They are used solely for ease of description and simplification of operation, 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. Therefore, they should not be construed as limitations on this invention. Furthermore, in the context, it should be understood that when an element is mentioned as being "upper" or "lower" of another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected through an intermediate element. It should also be understood that directional terms such as upper side, lower side, left side, right side, front side, and rear side not only represent positive orientation but can also be understood as lateral orientation. For example, "above," "on top of," "upper side of," and "above" of the first feature and the second feature include the first feature being directly above, to the upper left, to the upper right, to the upper front, and to the upper rear of the second feature, or simply indicating that the first feature is at a higher horizontal level than the second feature. The terms "below," "under," "below," and "below" for "first feature" and "second feature" include situations where the first feature is directly below, to the lower left, to the lower right, in front of, or behind the second feature, or simply indicate that the first feature is at a lower horizontal level than the second feature. Furthermore, the terms "first" and "second" are used merely for descriptive distinction and have no specific meaning.

[0023] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0024] This invention provides a range hood, such as Figures 1-3As shown, the range hood includes a main unit box 1, a fan 2 and an active noise reduction system 3. The active noise reduction system 3 includes a sound pickup component 33 and a speaker component 34. The fan 2 and the speaker component 34 are both located inside the main unit box 1. Air inlets 21 are provided on both sides of the fan 2. The sound pickup component 33 is provided on the inner wall of the main unit box 1 opposite to the air inlets 21 of the fan 2.

[0025] When the fan 2 starts, air and fumes are drawn into the main unit 1 and enter the fan 2 through the air inlets 21 on both sides, and then discharged through the exhaust pipe. At this time, the active noise reduction system 3 located on both sides of the air inlets 21 of the fan 2 can obtain the sound waves of the noise. The sound pickup components 33 are symmetrically arranged and are positioned directly facing the lower edge of the fan 2. This allows for accurate and full-coverage collection of the original rotational noise of the fan 2 and the coupled noise of the airflow in the duct. This effectively improves the integrity and spatial consistency of the noise sound wave collection. Then, the speaker components 34 emit noise reduction waves with the same amplitude and opposite phase as the original noise in real time, forming a spatial sound wave cancellation area inside the main unit 1. This suppresses the external noise radiation from the smoke collection chamber 4 and the oil mesh, achieving a pure hardware, zero-delay, and high-purity active noise reduction effect.

[0026] In this embodiment, the fan 2 is a centrifugal fan. The impeller shaft of the centrifugal fan extends along the left and right direction of the range hood. Therefore, the air inlet 21 of the centrifugal fan is opened on the left and right sides of the volute. Correspondingly, the inner sides of the left and right side walls of the main unit 1 are provided with the pickup components 33 of the active noise reduction system 3.

[0027] Preferably, the range hood further includes a smoke collection chamber 4, which is located below and connected to the main unit 1. A speaker assembly 34 is positioned between the fan 2 and the smoke collection chamber 4. Noise from the main unit 1, after passing through the active noise reduction system 3, propagates through the smoke collection chamber 4 to the outside of the range hood, affecting the user. Positioning the speaker assembly 34 between the fan 2 and the smoke collection chamber 4 is equivalent to placing it along the propagation path of the noise wave. When the speaker assembly 34 emits a noise-reducing wave with the same amplitude but opposite phase to the original noise, it can promptly cancel out the noise wave, improving the noise reduction effect.

[0028] However, the airflow within the duct impacts the microphone diaphragm, generating high-frequency noise such as airflow noise and secondary turbulence noise. This noise, combined with the original noise signal, leads to a decrease in ANC noise reduction, affecting pickup accuracy and noise reduction stability.

[0029] like Figures 2-4As shown, to solve the above problems, this embodiment provides an active noise cancellation system 3. The active noise cancellation system 3 includes a support frame 31, a noise preprocessing component 32, and a sound pickup component 33. The noise preprocessing component 32 is disposed on the support frame 31 and is used to filter noise of a specific frequency. The sound pickup component 33 is disposed on the support frame 31 and includes a microphone module 332. The microphone module 332 is used to collect the noise filtered by the noise preprocessing component 32.

[0030] In the active noise cancellation system 3, the support frame 31 serves as the main support structure, ensuring the stability of the active noise cancellation system 3. At the same time, the support frame 31 can also block large oil droplets and foreign objects while ensuring the propagation of sound waves, providing protection for the inner noise pre-processing component 32 and the pickup component 33. The noise pre-processing component 32 can filter noise of specific frequencies, enabling the microphone module 332 to isolate high-frequency noise such as airflow noise and secondary turbulence noise, thereby improving the pickup accuracy. Together with the speaker component 34, it can emit noise reduction waves with equal amplitude and opposite phase for low-frequency noise, thus improving the noise reduction stability.

[0031] The active noise reduction system 3 improves sound pickup accuracy and noise reduction stability. Through the combination of active noise reduction technology, it achieves full-frequency noise reduction for the range hood.

[0032] In this embodiment, the support frame 31 includes a front panel 311 with multiple perforations 313. The noise pretreatment component 32 includes a first sound-absorbing cotton 321, which is disposed on the inner side of the front panel 311 and covers all the perforations 313. The support frame 31 can block large oil droplets and foreign objects, providing protection for the inner first sound-absorbing cotton 321 and the pickup component 33. It can also ensure the normal propagation of sound waves through the perforations 313. The first sound-absorbing cotton 321 can absorb high-frequency noise and intercept fine oil mist particles, preventing the pickup component 33 from being contaminated with oil and affecting its sensitivity.

[0033] Preferably, the first sound-absorbing cotton 321 includes a sound-absorbing layer and non-woven fabric disposed on both sides of the sound-absorbing layer. That is, the first sound-absorbing cotton 321 has a composite structure, with the outermost layer being a waterproof and oil-resistant non-woven fabric, the middle layer being a loose and porous sound-absorbing layer, and the innermost layer being a waterproof and oil-resistant non-woven fabric.

[0034] Non-woven fabric is a cloth-like material in which fibers are directly bonded together by physical, chemical, or mechanical means. It possesses functions such as softness, breathability, and sound absorption. By attaching non-woven fabric to both the inner and outer sides of the sound-absorbing layer, the first sound-absorbing cotton 321 is guaranteed not to absorb oil, harden, or shed residue, thus stabilizing the structure. The sound-absorbing layer can be polyurethane sound-absorbing cotton, melamine foam, or a two-component blend of sound-absorbing cotton. Its characteristic is a porous structure, which utilizes numerous interconnected micropores within the material to convert sound wave energy into heat energy, thereby rectifying turbulent airflow, absorbing high-frequency noise, intercepting fine oil mist particles, buffering airflow impact, and ensuring uniform sound wave transmission. Non-woven fabric and sound-absorbing cotton, as materials with different acoustic properties, can form a more effective sound-absorbing structure when combined.

[0035] It is worth noting that the outer non-woven fabric is bonded to the inner sound-absorbing layer by hot melting or adhesive to ensure a stable connection between the non-woven fabric and the sound-absorbing layer, and to prevent the non-woven fabric from becoming loose and affecting the absorption effect.

[0036] In some embodiments, the noise preprocessing component 32 may also include other structures, such as loose and porous polyurethane, glass wool, rock wool, felt, foam plastic, foam ceramic and other passive noise reduction materials, or active noise reduction structures combining microphone and speaker, as long as they can absorb noise of a specific frequency (such as high-frequency noise) and filter out high-frequency noise in advance for the pickup component 33.

[0037] like Figure 3 and Figure 4 As shown, in this embodiment, to ensure the compactness of the internal structure of the active noise cancellation system 3, the active noise cancellation system 3 also includes a second sound-absorbing cotton 322, which is disposed on the side of the first sound-absorbing cotton 321 facing away from the front panel 311. The second sound-absorbing cotton 322 can fill the portion between the first sound-absorbing cotton 321 and the side wall of the main unit 1 where the sound-collecting component 33 is not located, thus providing support for the first sound-absorbing cotton 321 and ensuring its stability, and further improving the sound absorption effect of the active noise cancellation system 3 on mid-to-high frequency noise.

[0038] In other words, the second sound-absorbing cotton 322 can be set above the sound pickup component 33, below the sound pickup component 33, or both above and below the sound pickup component 33. The two sound-absorbing cottons clamp the sound pickup component 33 in the vertical direction to ensure the stability of the sound pickup component 33.

[0039] Specifically, the second sound-absorbing cotton 322 can be polyurethane foam or melamine foam, which has good filling properties and ensures the uniformity of thickness inside the support frame.

[0040] like Figures 3-6As shown, in this embodiment, the microphone pickup assembly 33 includes a mounting box 331 and a sound-permeable diaphragm 333. The mounting box 331 is provided with an opening 3311 facing the noise pre-processing assembly 32. The microphone module 332 is disposed inside the mounting box 331. The sound-permeable diaphragm 333 is sealed to the mounting box 331 and blocks the opening 3311.

[0041] In the active noise cancellation system 3, the sound-permeable membrane 333 of the pickup component 33 can both allow sound waves to pass through and block gas molecules from penetrating, thus completely isolating the internal and external air. This ensures sound wave transmission performance while preventing oil mist from directly contacting the microphone module 332, and eliminates secondary noise caused by membrane airflow vibration.

[0042] The active noise reduction system 3 uses multi-layered protection to block oil stains, airflow noise, and secondary noise from turbulence. It ensures sound transmission and noise reduction while providing wind and oil protection, extending the lifespan of the microphone module 332 and achieving full-frequency noise reduction for the range hood. Furthermore, since the microphone module 332 is located behind the front panel 311, it does not occupy space in the gas flow channel, does not affect airflow performance, and the front panel 311 is washable, improving cleaning convenience. The front panel 311, the first sound-absorbing cotton 321, and the sound-permeable membrane 333 form a gradient protection structure, progressively attenuating airflow energy and intercepting oil mist in layers, ensuring lossless sound wave transmission and resolving the contradiction between wind protection and sound transmission, and between oil protection and noise reduction, that traditional structures often cannot simultaneously achieve.

[0043] It is worth noting that the opening 3311 of the mounting box 331 can be positioned forward to be protected by the first sound-absorbing cotton 321, or it can be positioned upward or downward to be protected by the second sound-absorbing cotton 322. Preferably, the opening 3311 of the mounting box 331 is positioned forward, that is, towards the first sound-absorbing cotton 321, so that sound waves can directly enter the mounting box 331 and be received by the microphone module 332.

[0044] Specifically, the acoustic permeable membrane 333 is a functional thin film specifically designed to protect the acoustic components of electronic devices (such as microphones and speakers) while ensuring efficient sound transmission. For example, the acoustic permeable membrane 333 can be a 20-30 μm thick ePTFE (Expanded Polytetrafluoroethylene) membrane, possessing the advantages of sound transmission, air permeability, complete blocking of oil mist and liquid particles, hydrophobicity, oleophobicity, resistance to high and low temperatures, and low acoustic attenuation. Furthermore, the structure of the acoustic permeable membrane 333 is existing technology, and existing acoustic permeable membranes 333 can be selected as needed, which will not be elaborated here.

[0045] like Figure 5 and Figure 6As shown, the microphone module 332 includes a PCB board 3321 and multiple microphones 3322 disposed on the PCB board 3321, with the multiple microphones 3322 spaced apart along the length of the PCB board 3321. The PCB board 3321 is used to connect to external circuits and receive the sound wave signals from the multiple microphones 3322 and convert them into electrical signals. In order to cover the noise inside the main unit 1, the length direction of the PCB board 3321 is the front-to-back direction of the main unit 1. At this time, the two sets of microphone modules 332 on the left and right sides of the main unit 1 can receive the sound waves of noise from front to back.

[0046] Specifically, four microphones 3322 are set at equal intervals on each PCB board 3321, and a total of eight microphones 3322 are set on the whole device, forming a symmetrical, high-density spatial pickup array, which effectively improves the integrity and spatial consistency of noise acquisition.

[0047] In other words, this range hood adopts a fixed-gap spatial array topology structure, precisely matching the spacing of the microphones 3322 according to the characteristics of sound wave wavelength. Utilizing the principle of spatial phase difference, it achieves passive spatial cancellation filtering of airflow turbulence noise above 1000Hz, environmental high-frequency interference, and random noise. At the same time, it completely retains the 50~400Hz steady-state low-frequency effective noise signal of the fan 2, completing noise purification from the source of the microphones 3322. This completely avoids the problems of analog phase shift deviation, noise reduction attenuation, and abnormal noise distortion caused by high-frequency noise, and significantly improves the low-frequency noise reduction accuracy and working stability of the analog circuit.

[0048] When the system is working, eight microphones 3322 synchronously pick up the original operating noise of the fan 2 and input it to the analog noise reduction control board. The noise signal passes through the pre-bias and filtering circuits to complete voltage stabilization, noise filtering and waveform trimming. Then, it passes through the operational amplifier to achieve 180° precise phase reversal and signal amplitude amplification. Finally, it passes through the audio power amplifier to complete power drive amplification. Finally, it drives the noise reduction speaker to emit noise reduction waves with the same amplitude and opposite phase as the original noise in real time.

[0049] like Figure 5 As shown, in this embodiment, the sound pickup assembly 33 further includes a sealing frame 334. The sealing frame 334 seals and presses the acoustic membrane 333 tightly against the opening 3311 of the mounting box 331 and tensions the acoustic membrane 333. The sealing frame 334 and the mounting box 331 together clamp the acoustic membrane 333, which can ensure the stability of the acoustic membrane 333 and the seal of the opening 3311, and can also tension the acoustic membrane 333 to a preset degree, preventing the acoustic membrane 333 from loosening and wrinkling, and making the sound waves more stable when passing through the acoustic membrane 333.

[0050] To further improve the stability of the acoustic diaphragm 333, the pickup assembly 33 also includes a flexible support 335. The flexible support 335 is disposed within the mounting box 331 and located between the microphone module 332 and the acoustic diaphragm 333, supporting the acoustic diaphragm 333. The flexible support 335 abuts against the inner side of the acoustic diaphragm 333, thereby supporting the acoustic diaphragm 333 to ensure the stability of its overall shape, and being able to elastically deform with the vibration of the acoustic diaphragm 333. This does not affect the vibration of the acoustic diaphragm 333 caused by sound waves propagating to it, thus ensuring that sound waves can pass through the acoustic diaphragm 333.

[0051] In this embodiment, the flexible support 335 is a dehumidifying support cotton, which has a porous structure and a high porosity. It can not only provide flexible support for the acoustic membrane 333, but also absorb moisture that passes through the acoustic membrane 333, further improving the protection of the microphone 3322. Specifically, the dehumidifying support cotton can be melamine foam.

[0052] Optionally, the flexible support 335 abuts against the PCB board 3321 to ensure the stability of the flexible support 335 within the mounting box 331, thereby further improving the support for the acoustic membrane 333.

[0053] In this embodiment, the microphone pickup assembly 33 further includes a first damping pad 336, which is disposed within the mounting box 331 and located between the mounting box 331 and the microphone module 332. That is, the PCB board 3321 of the microphone module 332 is fixedly mounted within the mounting box 331 via the first damping pad 336. This structure enables flexible isolation between the microphone 3322 and the mounting box 331, blocking the transmission path of vibration from the main unit chassis 1 and reducing the impact on the microphone 3322.

[0054] In this embodiment, the pickup assembly 33 further includes a second vibration damping pad 337, which is disposed on the outer surface of the mounting box 331. The mounting box 331 abuts against the inner wall of the main unit housing 1 through the second vibration damping pad 337. The second vibration damping pad 337 can block the transmission path of vibration of the main unit housing 1 and reduce the impact on the microphone 3322.

[0055] In some embodiments, the pickup assembly 33 includes both a first damping pad 336 and a second damping pad 337. By simultaneously providing the first damping pad 336 and the second damping pad 337, the impact of vibration of the main unit 1 on the microphone 3322 can be minimized.

[0056] Preferably, the first damping pad 336 and the second damping pad 337 are made of nitrile rubber. Nitrile rubber has good damping properties to dissipate the energy of the vibration waves from the main unit housing 1, significantly reducing the impact of the vibration of the main unit housing 1 on the microphone 3322. In addition, nitrile rubber also has good oil resistance, and can still maintain good performance in the high oil environment inside the range hood, avoiding corrosion.

[0057] like Figure 5 As shown, in this embodiment, the side wall of the mounting box 331 is provided with an air pressure balance hole 3312. The air pressure balance hole 3312 connects the inside and outside of the mounting box 331 to balance the air pressure inside and outside the mounting box 331, eliminate the acoustic resonance peak of the sealed cavity, and avoid the BPF frequency resonance distortion problem of the fan 2.

[0058] Preferably, the diameter of the pressure balancing hole 3312 is 0.2mm to 0.4mm. The diameter of the pressure balancing hole 3312 should not be too large or too small. If it is too large, it will affect the sound pickup effect of the microphone 3322 and easily lead to oil and gas intrusion, affecting the service life of the microphone 3322. If it is too small, it will be difficult to achieve the function of balancing the pressure difference inside and outside the mounting box 331. Specifically, the diameter of the pressure balancing hole 3312 can be 0.2mm, 0.21mm, 0.22mm, 0.23mm, 0.24mm, 0.25mm, 0.26mm, 0.27mm, 0.28mm, 0.29mm, 0.3mm, 0.31mm, 0.32mm, 0.33mm, 0.34mm, 0.35mm, 0.36mm, 0.37mm, 0.38mm, 0.39mm, or 0.4mm.

[0059] Preferably, the second sound-absorbing cotton 322 blocks the air pressure balance hole 3312. That is, the air pressure balance hole 3312 is opened on the top or bottom surface of the mounting box 331, and the second sound-absorbing cotton 322 abuts against the top or bottom surface of the mounting box 331. The air pressure balance hole 3312 is protected by the second sound-absorbing cotton 322 assembly, which can completely block the intrusion of oil mist and airflow, and the second sound-absorbing cotton 322 will not affect the propagation of low-frequency effective noise signals, nor will it affect the sound pickup accuracy.

[0060] like Figures 3-5 As shown, in this embodiment, the support frame 31 also includes a side plate 312 surrounding the front plate 311. Mounting posts are provided at both ends of the mounting box 331. The mounting posts of the mounting box 331 abut against the corresponding side plate 312 of the support frame 31 and are fixedly connected to the side plate 312 by screws. The side plate 312 improves the overall rigidity of the support frame 31 and prevents deformation of the front plate 311. Fixing the mounting box 331 to the side plate 312 via the mounting posts ensures the stability of the sound pickup assembly 33 and also compresses the first sound-absorbing cotton 321, preventing oil fumes from seeping in through the gap between the first sound-absorbing cotton 321 and the front plate 311.

[0061] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. An active noise reduction system, characterized in that, include: Support frame (31); A noise preprocessing component (32) is disposed on the support frame (31), and the noise preprocessing component (32) is used to filter noise of a specific frequency; A pickup component (33) is disposed on the support frame (31). The pickup component (33) includes a microphone module (332), which is used to collect noise filtered by the noise preprocessing component (32).

2. The active noise cancellation system according to claim 1, characterized in that, The support frame (31) includes a front panel (311), which has multiple perforations (313). The noise pretreatment component (32) includes a first sound-absorbing cotton (321), which is located on the inside of the front panel (311) and covers all the perforations (313).

3. The active noise reduction system according to claim 2, characterized in that, The noise pretreatment component (32) further includes a second sound-absorbing cotton (322), which is disposed on the side of the first sound-absorbing cotton (321) away from the front panel (311) and located above and / or below the pickup component (33).

4. The active noise cancellation system according to claim 2, characterized in that, The first sound-absorbing cotton (321) includes a sound-absorbing layer and non-woven fabric disposed on both sides of the sound-absorbing layer.

5. The active noise cancellation system according to any one of claims 1 to 4, characterized in that, The pickup assembly (33) also includes a mounting box (331) and a sound-permeable membrane (333). The mounting box (331) has an opening (3311) facing the noise preprocessing assembly (32). The microphone module (332) is disposed inside the mounting box (331). The sound-permeable membrane (333) is sealed to the mounting box (331) and blocks the opening (3311).

6. The active noise cancellation system according to claim 5, characterized in that, The pickup assembly (33) also includes a flexible support (335), which is disposed in the mounting box (331) and located between the microphone module (332) and the acoustic membrane (333), and the flexible support (335) supports the acoustic membrane (333).

7. The active noise cancellation system according to claim 5, characterized in that, The pickup assembly (33) further includes a first damping pad (336), which is disposed within the mounting box (331) and located between the mounting box (331) and the microphone module (332); and / or, The pickup assembly (33) also includes a second damping pad (337), which is disposed on the outer surface of the mounting box (331).

8. The active noise cancellation system according to claim 5, characterized in that, The mounting box (331) has an air pressure balancing hole (3312) on its side wall facing the noise pretreatment component (32). The air pressure balancing hole (3312) is used to balance the air pressure inside and outside the mounting box (331).

9. The active noise cancellation system according to claim 5, characterized in that, The pickup assembly (33) also includes a sealing frame (334) that seals and presses the acoustic membrane (333) against the opening (3311) of the mounting box (331) and tensions the acoustic membrane (333).

10. A range hood, characterized in that, The active noise cancellation system (3) according to any one of claims 1 to 9 further includes a main unit (1) and a fan (2). The active noise cancellation system (3) further includes a speaker assembly (34). The fan (2) and the speaker assembly (34) are both disposed in the main unit (1). Air inlets (21) are opened on opposite sides of the fan (2). The pickup assembly (33) is disposed on the inner wall of the main unit (1) opposite to the air inlets (21) of the fan (2).

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