Adjustable noise reduction device, noise reduction adjusting method and range hood

Abstract

The invention discloses an adjustable noise reduction device, a noise reduction adjusting method and a range hood, the adjustable noise reduction device comprises a sound absorption chamber and a cover plate covering the sound absorption chamber, each layer of cover plate comprises a plurality of parallel and spaced battens, and the battens of the adjacent upper and lower layers are arranged in a staggered manner to form a plurality of micropores communicating with the sound absorption chamber; a plurality of driving mechanisms are arranged on the side edge of the sound absorption cavity, and the driving mechanisms on the different side edges are connected with the battens on the different layers correspondingly. The driving mechanism is used for driving the battens to move so as to adjust the distance between the battens on the same layer. According to the adjustable noise reduction device, the noise reduction adjusting method and the range hood, the structural strength is improved, meanwhile, the adverse factor that the acoustic resistance is too large due to the fact that the plate thickness is increased is avoided, the adjustable noise reduction device can be matched with the characteristic impedance of air, and therefore the sound absorption and noise reduction effect is improved. In addition, the sound absorption frequency band of the adjustable noise reduction device can be adjusted, the sound absorption capacity under different frequencies is improved, and therefore the adaptability to different working conditions and the sound absorption and noise reduction effect are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of noise reduction, and particularly to an adjustable noise reduction device, a noise reduction adjustment method, and a range hood. Background Art

[0002] At the current stage of the development of range hoods, it is no longer just a simple competition in the oil fume suction effect. The level of noise during use is also an important consideration for users when choosing a range hood, and low noise is the main advantage of the product.

[0003] The suppression of range hood noise has always been one of the main problems to be overcome by range hoods and is also an effective means to improve the user experience. Currently, for noise above 1000HZ, the main noise reduction method is based on sound-absorbing cotton; for noise reduction below 1000HZ, acoustic cavity resonance noise reduction is carried out by combining a micro-perforated structure with an air cavity.

[0004] The micro-perforated plate generally selects a relatively thin flat plate with a thickness of about 0 - 1mm. The relatively thin micro-perforated plate is easy to balance the acoustic resistance and acoustic reactance, so as to obtain good sound absorption performance. However, if the flat plate is too thin, it will lead to insufficient structural strength and also cause a large difference between the calculated sound absorption result and the actual sound absorption result, making it difficult to determine the plate thickness; however, increasing the plate thickness will lead to too large an acoustic resistance and make it difficult for sound waves to penetrate.

[0005] On the other hand, the sound absorption frequency band of the existing micro-perforated plate cannot be adjusted. That is, under different working conditions of the range hood, there will be different main peak frequencies of noise that are relatively high, and specific frequency noise reduction is required to improve the noise reduction effect. Currently, when the noise frequency of the micro-perforated plate changes, it cannot be adjusted accordingly according to the changing noise frequency, and the sound absorption effect is poor. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the defects of weak structural strength and poor sound absorption effect of the micro-perforated plate in the prior art, and provide an adjustable noise reduction device, a noise reduction adjustment method, and a range hood.

[0007] The present invention solves the above technical problems through the following technical solutions:

[0008] An adjustable noise reduction device, the adjustable noise reduction device includes a sound absorption chamber and at least two layers of cover plates covering the sound absorption chamber. Each layer of the cover plate includes a plurality of strip plates arranged in parallel and at intervals. The plurality of strip plates in adjacent upper and lower layers are arranged staggeredly to form a plurality of micropores communicating with the sound absorption chamber; a plurality of driving mechanisms are provided on the side of the sound absorption chamber, and the driving mechanisms on different sides are respectively connected to different layers of the strip plates; the driving mechanism is used to drive the strip plates to move to adjust the distance between the strip plates in the same layer.

[0009] In this solution, the adjustable noise reduction device forms a staggered multi-layer micro-perforated plate sound absorption structure through a sound absorption chamber and multiple layers of overlapping covers. On the one hand, by stacking multiple covers, the overall plate thickness is increased, improving the structural strength. On the other hand, by adjusting the strip plates (quantity, width, spacing, etc.), several strip plates in the upper and lower layers are staggered to form several micropores, which can increase the perforation rate, avoid the adverse factor of excessive acoustic resistance caused by increasing the plate thickness, and can match the characteristic impedance of air (the characteristic impedance of air refers to the obstructive effect of air on the propagation of sound waves under specific conditions), thereby improving the sound absorption and noise reduction effect. Moreover, by adjusting the spacing between each layer of strip plates, both the acoustic impedance of the micro-slits between each layer of strip plates and the acoustic impedance of the micropores formed by the staggered strip plates in the upper and lower layers are adjusted. The combined acoustic impedance generated by the combination of the micro-slit acoustic impedance and the micropore acoustic impedance can adapt to the sound absorption and noise reduction requirements of different frequencies, and can improve the sound absorption ability of different frequencies, that is, the adjustable noise reduction device can adjust its sound absorption frequency band (the sound absorption frequency band refers to the frequency range corresponding to the best sound absorption effect), and improve the sound absorption ability of the different sound absorption frequency bands it adjusts, improving the adaptability to different working conditions, thereby improving the sound absorption and noise reduction effect.

[0010] Preferably, the driving mechanisms on the same side are simultaneously connected to multiple strip plates of the same layer to drive the multiple strip plates of the same layer to move simultaneously.

[0011] In this solution, the driving mechanisms on the same side are simultaneously connected to multiple strip plates of the same layer, enabling the multiple strip plates of the same layer to maintain the same spacing adjustment, and the adjustment changes of each micropore are consistent, simplifying the structure and the adjustment method, and having good stability.

[0012] Preferably, the driving mechanism includes a driver, a support rod corresponding to each strip plate, and two connecting rods connecting adjacent support rods; a chute is provided on the support rod, the two connecting rods are cross-arranged and rotatably connected at the midpoint, and one end of the connecting rod is slidably connected to the chute; the output end of the driver is connected to one of the support rods to drive the support rod to move.

[0013] In this solution, through the above structural arrangement, a telescopic rhombus driving mechanism is formed; among them, the two connecting rods form a pair of telescopic rhombus moving mechanisms, and multiple pairs of rhombus moving mechanisms connecting multiple support rods are connected to form an integrally telescopic structure. The driver drives one of the support rods to move to drive the integrally telescopic rhombus moving mechanism connected thereto to expand and contract, thereby driving the strip plates connected to the support rods to move horizontally to adjust the spacing between the strip plates. Such a rhombus driving mechanism has a simple structure, and the same adjustment spacing can be maintained between each strip plate, and the structure is stable and reliable.

[0014] Preferably, a shaft member is inserted through the sliding groove, and one ends of the spaced multi-layer strip plates and the connecting rod are all connected to the same shaft member, and the shaft member slides within the sliding groove.

[0015] In this solution, the spaced multi-layer strip plates and the connecting rod are both connected to the same shaft member, realizing the synchronous adjustment of the spacing between the multi-layer strip plates, that is, the variation amounts of the conditional spacings of each layer are the same. Compared with adjusting the spacing of each layer of strip plates separately, this synchronous adjustment method simplifies the structure and facilitates the adjustment and control of the micro-slit acoustic impedance and the micro-hole acoustic impedance.

[0016] Preferably, a limiting groove is further provided on the side of the sound absorption chamber, and the bottom end of the support rod is clamped in the limiting groove; a pulley is provided on the side surface of the bottom end of the support rod, and the pulley is in sliding fit with the top surface of the limiting groove.

[0017] In this solution, clamping the bottom end of the support member in the limiting groove limits the movement space of the support member and makes its movement stable. Through the sliding fit of the pulley with the top surface of the limiting groove, the rhombus driving mechanism can stretch freely, and the overall movement of the rhombus driving mechanism is stable.

[0018] Preferably, the multi-layer strip plates arranged in a staggered manner form micro-holes with gradually increasing diameters from the outside of the cover plate to the inside of the sound absorption chamber.

[0019] In this solution, compared with straight through-holes, the adjustable noise reduction device adopts gradually increasing diameter gradient micro-holes, which can further improve its sound absorption ability; and by adjusting different gradient diameter ranges, the frequency range of sound absorption can be increased, improving the adaptability of sound absorption and noise reduction.

[0020] Preferably, the inclination angle range of the diameter of the micro-holes from the outside of the cover plate to the inside of the sound absorption chamber is 5° to 10°.

[0021] In this solution, adopting the above inclination angle range ensures that the gradient micro-holes have a good sound absorption effect.

[0022] Preferably, the thickness of the strip plate is not greater than 1.5 mm, and the total thickness of the multi-layer strip plates is not greater than 10 mm.

[0023] In this solution, a single strip plate adopting the above thickness range will not be too thin to ensure the structural strength. And the total thickness of the multi-layer strip plates adopting the above thickness range makes the overall thickness not too thick to cause excessive acoustic resistance.

[0024] A noise reduction adjustment method, the noise reduction adjustment method uses the adjustable noise reduction device as described above to perform noise absorption adjustment, the adjustable noise reduction device is installed on the noise generating device, and the noise reduction adjustment method includes:

[0025] Start the driving mechanism to drive the slats on each layer to move, completing one movement adjustment; wherein, in each of the movement adjustments, the slats on the same layer move by a set movement distance to gradually increase or decrease the spacing between the slats, and the slats on different layers are configured with the set movement distance according to a set change rule;

[0026] After each of the movement adjustments is completed, measure the corresponding sound pressure value at the noise source close to the noise generating device, thereby obtaining a sound pressure measurement value;

[0027] Compare the sound pressure measurement values obtained after several movement adjustments to obtain the minimum sound pressure measurement value, and record the spacing between the slats on each layer corresponding to the minimum sound pressure measurement value as the confirmed spacing of the slats on each layer.

[0028] In this solution, through the above steps, the noise reduction adjustment method adjusts the micro-slit acoustic impedance between the slats on each layer at a set movement distance within the same layer and adjusts the micro-hole acoustic impedance formed by the slats offset up and down between layers according to a set change rule. The combined acoustic impedance generated by the combination of the micro-slit acoustic impedance and the micro-hole acoustic impedance can adapt to the sound absorption and noise reduction requirements of different frequencies, improve the sound absorption ability of different frequencies, enhance the adaptability to different working conditions, and thus improve the sound absorption and noise reduction effect. Among them, by comparing the sound pressure measurement values obtained after several movement adjustments, the minimum sound pressure measurement value is obtained. This minimum sound pressure measurement value is the sound pressure value after the adjustable noise reduction device has absorbed sound to the greatest extent after adjustment, ensuring the best sound absorption effect.

[0029] Preferably, drive multiple slats on the same layer to move simultaneously.

[0030] In this solution, by driving multiple slats on the same layer to move simultaneously, the same spacing adjustment can be maintained between multiple slats on the same layer, and the adjustment changes of each micro-hole are consistent, simplifying the adjustment method.

[0031] Preferably, the set change rule is an increasing change rule.

[0032] In this solution, by adopting an increasing change rule to form a gradually increasing micro-hole structure, the sound absorption ability can be further improved; and by adopting different increasing change amounts, the frequency range of sound absorption can be increased, enhancing the adaptability of sound absorption and noise reduction.

[0033] An oil fume extractor, in which the adjustable noise reduction device as described above is installed, and / or the noise reduction adjustment method as described above is used to perform noise reduction treatment on the exhausted oil fume.

[0034] In this solution, the range hood improves the structural strength through the above adjustable noise reduction device and / or the above noise reduction adjustment method. At the same time, it avoids the adverse factor of excessive sound resistance caused by increasing the plate thickness and can match the characteristic impedance of the air, thereby improving the sound absorption and noise reduction effect. Moreover, it can adjust the sound absorption frequency band of the adjustable noise reduction device, improve the sound absorption ability at different frequencies, and thus improve the adaptability to different working conditions and the sound absorption and noise reduction effect.

[0035] The positive and progressive effects of the present invention are as follows: The adjustable noise reduction device, the noise reduction adjustment method, and the range hood improve the structural strength. At the same time, they avoid the adverse factor of excessive sound resistance caused by increasing the plate thickness and can match the characteristic impedance of the air, thereby improving the sound absorption and noise reduction effect. Moreover, they can adjust the sound absorption frequency band of the adjustable noise reduction device, improve the sound absorption ability at different frequencies, and thus improve the adaptability to different working conditions and the sound absorption and noise reduction effect. Brief Description of the Drawings

[0036] Figure 1 It is a schematic structural diagram of the adjustable noise reduction device according to Embodiment 1 of the present invention.

[0037] Figure 2 It is a top view of the adjustable noise reduction device according to Embodiment 1 of the present invention.

[0038] Figure 3 It is Figure 2 a cross-sectional view taken along the B-B direction in

[0039] Figure 4 It is a side view of the adjustable noise reduction device according to Embodiment 1 of the present invention.

[0040] Figure 5 It is Figure 1 an enlarged schematic structural diagram of the partial area A in

[0041] Figure 6 It is a comparison diagram of the sound absorption coefficient curves with different hole side lengths when the adjustable noise reduction device according to Embodiment 1 of the present invention adopts square microholes with straight through holes. Among them, the abscissa is the frequency at which the microhole structure absorbs external noise, and the ordinate is the sound absorption coefficient.

[0042] Figure 7 It is a schematic diagram of the microhole structure when the adjustable noise reduction device according to Embodiment 1 of the present invention adopts gradually changing microholes.

[0043] Figure 8 It is a comparison diagram of the sound absorption coefficient curves between the gradually changing microholes and the straight through holes when the adjustable noise reduction device according to Embodiment 1 of the present invention adopts gradually changing microholes. Among them, the abscissa is the frequency at which the microhole structure absorbs external noise, and the ordinate is the sound absorption coefficient.

[0044] Figure 9When the adjustable noise reduction device of Embodiment 1 of the present invention adopts a gradient micropore, it is a comparison diagram of the sound absorption coefficient curves in two different gradient pore size ranges. Among them, the abscissa is the frequency at which the micropore structure absorbs external noise, and the ordinate is the sound absorption coefficient.

[0045] Figure 10 It is a step flowchart of the noise reduction adjustment method of Embodiment 2 of the present invention.

[0046] Figure 11 It is a specific step flowchart of the noise reduction adjustment method of Embodiment 2 of the present invention when it is used for sound absorption and noise reduction of a range hood.

[0047] Explanation of reference numerals:

[0048] Adjustable noise reduction device 1

[0049] Sound absorption chamber 2

[0050] Cover plate 3

[0051] The first layer 31

[0052] The second layer 32

[0053] The third layer 33

[0054] The fourth layer 34

[0055] The fifth layer 35

[0056] The sixth layer 36

[0057] Strip board 4

[0058] Extension rod 41

[0059] Micro slit 5

[0060] Micropore 6

[0061] Drive mechanism 7

[0062] Driver 71

[0063] Support rod 72

[0064] Chute 721

[0065] Connecting rod 73

[0066] Shaft part 74

[0067] Limit groove 8

[0068] Pulley 9 Detailed implementation manners

[0069] The present invention will be further described below by way of embodiments, but the present invention is not limited to the scope of the described embodiments.

[0070] Embodiment 1

[0071] This embodiment provides an adjustable noise reduction device 1, which is used in a range hood or other products that generate noise and the user needs to reduce the noise.

[0072] The adjustable noise reduction device 1 includes a sound absorption chamber 2 and at least two layers of cover plates 3 covering the sound absorption chamber 2. Each layer of cover plate 3 includes a plurality of strip plates 4 arranged in parallel and at intervals. The strip plates 4 of adjacent upper and lower layers are staggered to form a plurality of micropores 6 communicating with the sound absorption chamber 2. A plurality of driving mechanisms 7 are provided on the side of the sound absorption chamber 2. The driving mechanisms 7 on different sides are respectively connected to the strip plates 4 of different layers. The driving mechanism 7 is used to drive the strip plates 4 to move to adjust the distance between the strip plates 4 of the same layer.

[0073] Specifically, as Figures 1 - 5 shown, this embodiment shows an adjustable noise reduction device 1 with a six-layer staggered micro-perforated plate. Its sound absorption chamber 2 is a square sound absorption box body. The top opening of the sound absorption box body is covered with six layers of cover plates 3. The distance from the bottom layer of the cover plate 3 to the bottom of the sound absorption box body constitutes the thickness of the sound absorption chamber 2. In application, according to the need of the sound absorption effect, the thickness of the sound absorption chamber 2 can be calculated in advance to achieve the best sound absorption effect of the chamber. In the depth direction from the outside of the cover plate 3 to the inside of the sound absorption chamber 2, there are the first layer 31, the second layer 32, the third layer 33, the fourth layer 34, the fifth layer 35 and the sixth layer 36, a total of six layers of cover plates 3. In the length and width directions, each layer of cover plate 3 has 10 strip plates 4 arranged in parallel and at intervals. The six layers of cover plates 3 are alternately staggered at 90 degrees to form 81 micropores 6, and each micropore 6 communicates with the sound absorption chamber 2. There is a driving mechanism 7 on each of the two sides of the sound absorption chamber 2. Each driving mechanism 7 is respectively connected to the strip plates 4 stacked alternately and staggeredly. The driving mechanism 7 drives the strip plates 4 on the corresponding side to adjust the distance between the strip plates 4 of the same layer.

[0074] In such a structure of the staggered micro-perforated plate, in the depth direction from the outside of the cover plate 3 to the inside of the sound absorption chamber 2, the pores formed between the strip plates 4 include the micro-slits 5 between the strip plates 4 and the square micropores 6 surrounded by the staggered strip plates 4 of the upper and lower layers. Therefore, when sound propagates, the acoustic impedance of the pores includes the micro-slit acoustic impedance and the micropore acoustic impedance. According to the principle of sound propagation, the formula for the micro-slit acoustic impedance can be deduced as:

[0075] ;

[0076] In the formula: is the perforation constant, ŋ is the air viscosity coefficient, is the air density, h is the chamber thickness, is the slit width (i.e., the distance between two strip plates 4). Among them, The formula for In this formula, d is the micropore diameter, w is the acoustic angular frequency (w = 2πf, f is the frequency in Hz), is the air density, and µ is the air dynamic viscosity.

[0077] The acoustic impedance of the micropore The formula for

[0078] ;

[0079] In the formula: ŋ is the air viscosity coefficient, is the air density, is the cross-section ratio of the micropore to the upper and lower slit widths, the real part of the acoustic impedance, w is the acoustic angular frequency (w = 2πf, f is the frequency in Hz), is the side length of the micropore 6. Among them, The formula for the real part of the acoustic impedance is:

[0080] , in the formula: ŋ is the air viscosity coefficient, t is the plate thickness, is the air density, is the speed of sound in air, which is a constant, and d is the micropore diameter.

[0081] When the pore structure of the offset type micro-perforated plate of this embodiment is adopted, its overall acoustic impedance is not a simple series-parallel connection of two acoustic impedances, but a comprehensive acoustic impedance. The overall acoustic impedance designed with this pore structure The corresponding formula for it is:

[0082] ;

[0083] In the formula: is the acoustic impedance of the micro-slit in the above formula, is the acoustic impedance of the micropore in the above formula, is the micro-slit porosity (the micro-slit porosity is the ratio of the total area of all micro-slits between the strip plates 4 to the total area of the cover plate 3 on the plane), is the perforation rate of the micropore cross-section (the perforation rate is the ratio of the total cross-sectional area of all micropores to the total area of the cover plate 3 on the plane), is the speed of sound in air, which is a constant.

[0084] Substitute the above formula for the acoustic impedance of the micro-slit and the formula for the acoustic impedance of the micropore into the formula for the overall acoustic impedance to obtain:

[0085] ;

[0086] According to the above formula, when the air density and the chamber thickness h are relatively fixed, by adjusting the spacing between the slat plates 4, the size of the micro-slits 5 and the cross-sectional area of the micro-holes 6 can be adjusted, and by superimposing two different acoustic impedances, the overall acoustic impedance is increased .

[0087] The adjustable noise reduction device 1 forms a multi-layer micro-perforated panel sound absorption structure with a staggered type through the sound absorption chamber 2 and the multi-layer staggered cover plates 3. Among them, on the one hand, by superimposing the multi-layer cover plates 3, the overall plate thickness is increased, and the structural strength is improved; on the other hand, by adjusting the slat plates 4 (quantity, width, spacing, etc.), a plurality of upper and lower slat plates 4 are staggered with each other to form a plurality of micro-holes 6, which can improve the perforation rate and avoid the adverse factor of excessive acoustic resistance caused by increasing the plate thickness, and can match the characteristic impedance of the air (the characteristic impedance of the air refers to the hindrance of the air to the propagation of sound waves under specific conditions), thereby improving the sound absorption and noise reduction effect. And, by adjusting the spacing between the slat plates 4 of each layer, both the acoustic impedance of the micro-slits between the slat plates 4 of each layer and the acoustic impedance of the micro-holes formed by the staggered slat plates 4 of the upper and lower layers are adjusted. The combined acoustic impedance generated by the combination of the micro-slit acoustic impedance and the micro-hole acoustic impedance can meet the sound absorption and noise reduction requirements of different frequencies, and can improve the sound absorption ability of different frequencies, that is, the adjustable noise reduction device 1 can adjust its sound absorption frequency band (the sound absorption frequency band refers to the frequency corresponding to the best sound absorption effect), and improve the sound absorption ability of the different sound absorption frequency bands it adjusts, improve the adaptability to different working conditions, and thus improve the sound absorption and noise reduction effect.

[0088] In other embodiments, according to the requirements of the sound absorption effect, the number of layers of the cover plate 3, the quantity, thickness, width, etc. of the slat plates 4 can be adjusted accordingly, and are not limited to the structural form of six-layer plates.

[0089] Among them, such as Figure 1As shown in the figure, the driving mechanism 7 on the same side is simultaneously connected to multiple strip plates 4 of the same layer of the cover plate 3 to drive the multiple strip plates 4 of the same layer of the cover plate 3 to move simultaneously. In other embodiments, each strip plate 4 can also be provided with a driving mechanism 7 for position adjustment. However, in that case, the overall driving mechanism 7 for all strip plates 4 will be relatively complex, which is not conducive to manufacturing and installation. Different from this embodiment, by using the driving mechanism 7 on the same side to simultaneously connect multiple strip plates 4 of the same layer, the same spacing adjustment can be maintained between the multiple strip plates 4 of the same layer, and the adjustment changes of each micropore 6 are consistent, which simplifies the structure and the adjustment method, and has good stability. Here, multiple strip plates 4 of the same layer can be such that all strip plates 4 are connected to one driving mechanism 7, or the strip plates 4 of the same layer can be divided into two groups or multiple groups, and multiple strip plates 4 in each group are connected to one driving mechanism 7, and the configuration method is flexible.

[0090] As Figures 3 - 5 shown, in this embodiment, the driving mechanism 7 includes a driver 71, a support rod 72 correspondingly connected to each strip plate 4, and two connecting rods 73 connecting two adjacent support rods 72; a sliding groove 721 is formed on the support rod 72, the two connecting rods 73 are cross - arranged and rotatably connected at the mid - point, forming a structure similar to a scissor cross; and one end of the connecting rod 73 is slidably connected to the sliding groove 721; the output end of the driver 71 is connected to one of the support rods 72 to drive the support rod 72 to move. Through such a structural form, a telescopic rhombic driving mechanism 7 is formed; among them, the two connecting rods 73 form a pair of telescopic rhombic movable mechanisms, and multiple pairs of rhombic movable mechanisms connecting multiple support rods 72 are interconnected into a structure that can be telescopically moved as a whole. The driver 71 drives one of the support rods 72 to move to drive the overall rhombic movable mechanism connected thereto to expand and contract, thereby driving the strip plate 4 connected to the support rod 72 to move horizontally to adjust the spacing between the strip plates 4. Such a rhombic driving mechanism has a simple structure, and the same adjustment spacing can be maintained between each strip plate 4, and the structure is stable and reliable.

[0091] In other embodiments, there are various forms of the driving mechanism 7, and it is not limited to the rhombic driving mechanism 7 of this embodiment. Any driving form that can achieve the above - mentioned adjustment of the spacing between the strip plates 4 can be adopted.

[0092] As Figure 5As shown, a shaft member 74 is inserted through the sliding groove 721. One ends of the spaced multi-layer strip plates 4 and the connecting rod 73 are both connected to the same shaft member 74, and the shaft member 74 slides within the sliding groove 721. Specifically, from top to bottom, the strip plates 4 of the first layer and the third layer that are spaced and stacked are connected to the same shaft member 74 through their side extension rods 41, while the strip plate 4 of the fifth layer is connected to another shaft member 74 through its side extension rod 41. To further simplify the structure, the strip plates 4 of the first layer 31, the third layer 33, and the fifth layer 35 can also be connected to the same shaft member 74, so that the synchronous adjustment of the spacing between the multi-layer strip plates 4 can be achieved, that is, the variation amounts of the conditions spacing of each layer are the same. Compared with the separate adjustment of the spacing of each layer of strip plates 4, this synchronous adjustment method simplifies the structure and facilitates the adjustment and control of the acoustic impedance of the micro-slits 5 and the acoustic impedance of the micro-holes 6.

[0093] As Figure 5 shown, a limiting groove 8 is further provided on the side of the sound-absorbing chamber 2; the bottom end of the support rod 72 is clamped in the limiting groove 8; a pulley 9 is provided on the side surface of the bottom end of the support rod 72, and the pulley 9 is slidably matched with the top surface of the limiting groove 8. Clamping the bottom end of the support member in the limiting groove 8 limits the movement space of the support member and makes its movement stable. Through the sliding fit of the pulley 9 with the top surface of the limiting groove 8, the rhombic drive mechanism 7 can stretch and contract freely, and the overall movement of the rhombic drive mechanism 7 is stable.

[0094] When applying the adjustable noise reduction device 1 of this embodiment, the spacing between the upper and lower layer strip plates 4 can be adjusted to be the same, so that the micro-holes 6 form straight through-holes, or the spacing between each layer of strip plates 4 can be adjusted, and from the outside of the cover plate 3 to the inside of the sound-absorbing chamber 2, the multi-layer strip plates 4 arranged in a staggered manner form micro-holes 6 with gradually increasing diameters.

[0095] Figure 6 An example of adjusting the square micro-holes 6 to a straight through-hole type is shown, where the hole side length gradually increases from 0.4 mm to 2 mm. In this curve graph, the abscissa is the frequency at which the micro-hole 6 structure absorbs external noise, and the ordinate is the sound absorption coefficient. The sound absorption coefficient is the different sound absorption capabilities exhibited by the micro-hole 6 structures with different side lengths, corresponding to the overall acoustic impedance of the micro-hole 6 structure. It can be found from this curve graph that as the pore diameter l changes, the sound absorption center frequency moves towards the low frequency.

[0096] Using the adjustable noise reduction device 1 designed in this embodiment, since the adjustment method between the upper and lower layer strip plates 4 is relatively flexible, in application, the spacing of the strip plates 4 can be adjusted according to the specific sound absorption frequency band requirements of the actual product to achieve noise reduction adjustment, or various combinations of this structure can be carried out for multi-band noise reduction adjustment.

[0097] Furthermore, the multi-layer strip plates 4 can also be adjusted into gradually increasing diameter gradient micro-holes 6. For example, the following table and Figure 7The shown tapered micropore 6 has a large end and a small end with different diameters:

[0098]

[0099] Among them, the cone angle rad is arctan((L2 - L1) / 4t) = 6.5, and L2 is the middle diameter size when L1 gradually changes to L3.

[0100] Figure 8 The schematic diagram shows the comparison of the sound absorption coefficient curve 1 when using the above-mentioned tapered micropore 6 with the sound absorption coefficient curve 2 with a straight-through hole of the small end diameter L1 and the sound absorption coefficient curve 3 with a straight-through hole of the large end diameter L3. It can be seen from the figure that compared with the straight-through micropore 6, under the same cavity thickness, the tapered micropore 6 can achieve the best sound absorption coefficient at a lower sound absorption frequency and has a higher peak value of the sound absorption coefficient at this frequency, which is helpful for better sound absorption effect.

[0101] For another example, the two different ranges of tapered micropores 6 and their corresponding two sound absorption coefficient curves shown in the following two parameter tables (as Figure 9 shown):

[0102] Curve 4

[0103]

[0104] Curve 5

[0105]

[0106] From Figure 9 it can be seen that the adjustable noise reduction device 1 has sound absorption peaks at different frequencies in different ranges of micropores 6 (that is, it has the best sound absorption coefficient at this frequency). Curve 4 has the largest sound absorption coefficient at a frequency close to 600 Hz, while curve 5 has the highest sound absorption coefficient at a frequency close to 1600 Hz. Therefore, by adjusting different ranges of tapered micropores 6, the frequency at which the best sound absorption effect can be achieved can be adjusted, and compared with the traditional straight-through hole type micro-perforated plate, the sound absorption coefficient of the tapered micropore 6 is higher and its thickness increase is not significant.

[0107] Compared with the straight-through hole, when the adjustable noise reduction device 1 uses a tapered micropore 6 with a gradually increasing diameter, its sound absorption ability can be further improved; and by adjusting different tapered diameter ranges, the frequency range of sound absorption can be increased, improving the adaptability of sound absorption and noise reduction.

[0108] In other embodiments, the inclination angle of the diameter of the gradient micropores 6 from the outside of the cover plate 3 to the inside of the sound absorption chamber 2 (i.e., the taper angle size from the small end to the large end) can be adjusted according to the required effect, and preferably, the inclination angle range is 5° to 10°, ensuring a good sound absorption effect.

[0109] In this embodiment, the thickness of each strip 4 is not greater than 1.5 mm, and the total thickness of the multi-layer strips 4 stacked is not greater than 10 mm. Using the above thickness range for a single strip 4 will not be too thin to ensure the structural strength. And using the above thickness range for the total thickness of the multi-layer strips 4 makes the overall thickness not too thick to cause excessive acoustic resistance.

[0110] Embodiment 2

[0111] This embodiment provides a noise reduction adjustment method, which uses the adjustable noise reduction device 1 as in Embodiment 1 to adjust the absorption of noise. The adjustable noise reduction device 1 is installed on the noise generating device. As Figure 10 shown, the noise reduction adjustment method includes:

[0112] S1. Start the driving mechanism 7 to drive the strips 4 of each layer to move and complete one movement adjustment; wherein, in each movement adjustment, the strips 4 of the same layer move at a set movement distance to gradually increase or decrease the distance between the strips 4, and the strips 4 of different layers are configured with set movement distances according to a set change rule;

[0113] S2. After each movement adjustment is completed, measure the corresponding sound pressure value at the noise source near the noise generating device to obtain the sound pressure measurement value;

[0114] S3. Compare the sound pressure measurement values obtained after several movement adjustments to obtain the minimum sound pressure measurement value, and record the distance between the strips 4 of each layer corresponding to the minimum sound pressure measurement value as the confirmed distance between the strips 4 of each layer.

[0115] Among them, in step S1, when adjusting the distance between the strips 4 of different layers, the set change rule can have various forms. For example, it can gradually increase or decrease, or it can be based on a curve of a certain mathematical formula to determine the change value of the distance between the strips 4 of different layers. Therefore, such a change rule is not limited to gradually increasing or decreasing.

[0116] Through the above steps, the noise reduction adjustment method adjusts the spacing of the strip plates 4 in each layer at a set moving distance within the same layer and according to a set variation law between layers. In the depth direction of the multi-layer micro-perforated plates, the acoustic impedance of the micro-slits 5 between the strip plates 4 in each layer is adjusted, and the acoustic impedance of the micro-holes 6 formed by the strip plates 4 offset up and down is also adjusted. The combined acoustic impedance generated by the combination of the acoustic impedance of the micro-slits 5 and the acoustic impedance of the micro-holes 6 can meet the requirements of sound absorption and noise reduction at different frequencies, improve the sound absorption ability at different frequencies, enhance the adaptability to different working conditions, and thus improve the sound absorption and noise reduction effect. Among them, by comparing the sound pressure measurement values obtained after several moving adjustments, the minimum sound pressure measurement value is obtained. This minimum sound pressure measurement value is the sound pressure value after the adjustable noise reduction device 1 absorbs sound to the greatest extent after adjustment, ensuring the best sound absorption effect.

[0117] Among them, according to the form of the driving mechanism 7 of the adjustable noise reduction device 1 in Embodiment 1, the driving method in Step S1 can specifically be: driving multiple strip plates 4 in the same layer to move simultaneously. In other embodiments, if each strip plate 4 is connected to a corresponding driving mechanism 7, simultaneous driving cannot be achieved, and its structure and driving operation are relatively complex. Instead, in this embodiment, by driving multiple strip plates 4 in the same layer to move simultaneously, the same spacing adjustment can be maintained between the multiple strip plates 4 in the same layer, and the adjustment changes of each micro-hole 6 are consistent, simplifying the adjustment method.

[0118] The set variation law in this embodiment is an increasing variation law, forming a gradually increasing micro-hole 6 structure, which can further improve the sound absorption ability; and by using different increasing variation amounts, the frequency range of sound absorption can be increased, enhancing the adaptability of sound absorption and noise reduction.

[0119] Figure 11 A specific example of applying the noise reduction adjustment method when the adjustable noise reduction device 1 is applied to an oil fume extractor is shown. Among them, the above Step S2 is divided into Step S2-1 and Step S2-2. Step S2-1 is to collect noise signals using a noise measurement device. The sampling rate refers to the maximum noise frequency of 6.4 kHz that the noise measurement device can identify when collecting external noise; Step S2-2 is to perform conversion calculations in the calculation module inside the noise measurement device based on the collected noise signals to obtain the measured sound pressure value P. Since in specific applications, the initial sound pressure value P0 of the noise will be collected first before the moving adjustment (i.e., Step S1) is performed, therefore, in Figure 11In the step flow chart, steps S2-1 and S2-2 are included before step S1. After starting the movement adjustment step S1, each time a movement adjustment is made (the pitch increment of the movable strip 4 each time is 0.4 mm), the adjustment count N is incremented by one, and then it returns to steps S2-1 and S2-2 to measure the sound pressure value after the noise is absorbed, obtaining P1, P2, P3…PN until the set number of movement adjustments is reached. In step S3, it is also divided into steps S3-1 and S3-2. In step S3-1, the minimum sound pressure measurement value Pmin is obtained by comparing the obtained sound pressure measurement values P1, P2, P3…PN. Then in step S3-2, the pitch of the strip 4 corresponding to the minimum sound pressure measurement value Pmin is confirmed as the pitch of the strip 4 with the best sound absorption effect, and the confirmed pitch is output. At this time, after the movement adjustment in the previous steps, the pitch of the strip 4 is no longer the pitch of the strip 4 with the best sound absorption effect. Therefore, in step S4, the pitch of the upper and lower layers of the strip 4 is adjusted according to the output confirmed pitch of the strip 4, so that the adjustable noise reduction device 1 can obtain the best sound absorption effect.

[0120] It should be noted here that the advantage of the initial sound pressure value P0 is that the measured sound pressure value after each subsequent movement adjustment should be smaller than P0, so as to detect whether the adjustment of the noise measurement device and / or the adjustable noise reduction device 1 is effective.

[0121] Embodiment 3

[0122] This embodiment provides an oil fume machine, in which an adjustable noise reduction device 1 as in Embodiment 1 is installed, and the noise reduction adjustment method as in Embodiment 2 can be used to perform noise reduction treatment on the discharged oil fume. Through the above adjustable noise reduction device 1 and / or the above noise reduction adjustment method, the structural strength is improved, and at the same time, the adverse factor of excessive acoustic resistance caused by increasing the plate thickness is avoided, and it can be matched with the characteristic impedance of the air, thereby improving the sound absorption and noise reduction effect. And it can adjust the sound absorption frequency band of the adjustable noise reduction device 1, improve the sound absorption ability at different frequencies, and thus improve the adaptability to different working conditions and the sound absorption and noise reduction effect.

[0123] Although the specific embodiments of the present invention have been described above, those skilled in the art should understand that this is only an example, and the protection scope of the present invention is defined by the appended claims. Without departing from the principles and essence of the present invention, those skilled in the art can make various changes or modifications to these embodiments, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. An adjustable noise reduction device, characterized in that: The adjustable noise reduction device comprises a sound absorbing chamber and at least two layers of cover plates covering the sound absorbing chamber, each layer of the cover plates comprises a plurality of parallel and spaced strips, and the plurality of strips in adjacent upper and lower layers are staggered to form a plurality of micro-holes connected to the sound absorbing chamber; A plurality of driving mechanisms are arranged on the side of the sound absorbing chamber, and the driving mechanisms on different sides are respectively connected to the strips at different layers; the driving mechanisms are used to drive the strips to move so as to adjust the spacing between the strips at the same layer.

2. The adjustable noise reduction device according to claim 1, characterized in that: The driving mechanism on the same side is connected to a plurality of the strips on the same layer at the same time, so as to drive the plurality of the strips on the same layer to move simultaneously.

3. The adjustable noise reduction device according to claim 2, characterized in that: The driving mechanism includes a driver, a support rod corresponding to each of the slats, and two connecting rods connecting two adjacent support rods; a slide groove is provided on the support rod, the two connecting rods are cross-arranged and rotatably connected at the midpoint, and one end of the connecting rod is slidably connected to the slide groove; the output end of the driver is connected to one of the support rods to drive the support rod to move.

4. The adjustable noise reduction device according to claim 3, characterized in that: A shaft member is inserted into the slide groove, and the spaced-apart multiple layers of strips and one end of the connecting rod are all connected to the same shaft member, and the shaft member slides in the slide groove.

5. The adjustable noise reduction device according to claim 3, characterized in that: The side of the sound absorbing chamber is also provided with a limiting groove, and the bottom end of the support rod is clamped in the limiting groove; A pulley is provided on the side surface of the bottom end of the support rod, and the pulley is slidably matched with the top surface of the limiting groove.

6. The adjustable noise reduction device according to claim 1, characterized in that: From the outside of the cover plate to the inside of the sound absorbing chamber, the multiple layers of the staggeredly arranged strips form micropores with gradually increasing diameters.

7. The adjustable noise reduction device according to claim 6, characterized in that: The diameter of the microholes has an inclination angle ranging from 5° to 10° from the outside of the cover plate to the inside of the sound absorbing chamber.

8. The adjustable noise reduction device according to any one of claims 1 to 7, characterized in that: The thickness of the strips is not greater than 1.5 mm, and the total thickness of the multiple layers of the strips is not greater than 10 mm.

9. A noise reduction adjustment method, characterized in that: The noise reduction adjustment method uses an adjustable noise reduction device as described in any one of claims 1 to 8 to adjust the noise absorption, and the adjustable noise reduction device is installed in the noise generating equipment. The noise reduction adjustment method includes: The driving mechanism is started to drive the slats of each layer to move, and a movement adjustment is completed; wherein, in each movement adjustment, the slats of the same layer move at a set movement distance to gradually increase or decrease the spacing between the slats, and the slats of different layers are configured with the set movement distance according to a set change rule; After completing each movement adjustment, measuring the corresponding sound pressure value at the noise source close to the noise generating device, thereby obtaining a sound pressure measurement value; The sound pressure measurement values ​​obtained after several times of movement and adjustment are compared to obtain a minimum sound pressure measurement value, and the spacing between the slats of each layer corresponding to the minimum sound pressure measurement value is recorded as the confirmed spacing of the slats of each layer.

10. The noise reduction adjustment method according to claim 9, characterized in that: A plurality of the strips on the same layer are driven to move simultaneously.

11. The noise reduction adjustment method according to claim 9, characterized in that: The changing rule of the setting is an increasing changing rule.

12. A range hood, characterized in that: The range hood is installed with an adjustable noise reduction device as described in any one of claims 1 to 8, and / or utilizes a noise reduction adjustment method as described in any one of claims 9 to 11 to perform noise reduction treatment on the exhausted fumes.

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