Sound absorption structure combining micro-perforated plate and homocentric-square-shaped acoustic cellular structure and application

Abstract

The invention discloses a sound absorption structure combining a micro-perforated plate and a concentric-square-shaped acoustic cellular structure and application, and belongs to the technical field of mechanical noise control. The sound absorption structure comprises the micro-perforated plate and the concentric-square-shaped acoustic cellular structure; the homocentric-square-shaped acoustic cellular structure comprises a plurality of cavities with openings in the top ends, the depths and the sectional dimensions of the cavities are gradually reduced, and the cavities are nested one by one from outside to inside from large to small; the top ends of the plurality of cavities are fixed on the lower surface of the micro-perforated plate; the micro-perforated plate is provided with a plurality of plate micropores penetrating through the upper surface and the lower surface of the micro-perforated plate, and the plurality of plate micropores are positioned in the range of the innermost cavity; and except the outermost cavity, the bottoms of the rest cavities are provided with a plurality of cellular micropores penetrating through the upper and lower surfaces of the cavities. The thickness of the structure is adjustable, and the multi-cell combined structure of the structure has the advantage of wide sound absorption frequency band in low and medium frequency noise.

Description

Technical Field

[0001] The present invention belongs to the technical field of mechanical noise control, and relates to a sound absorbing structure, in particular to a sound absorbing structure combining a micro-perforated plate with a "return-shaped" acoustic cell structure and its application. Background Art

[0002] In the field of mechanics, noise refers to the sound or vibration produced by mechanical equipment or systems. Noise is a very important issue in the field of mechanics, affecting the safety, reliability, efficiency, human health and living environment of mechanical equipment. Therefore, it is necessary to control noise artificially.

[0003] There are two main types of noise reduction technologies at present: active noise reduction and passive noise reduction. Active noise reduction is mainly active control, which uses a secondary speaker to emit a manually set controlled sound source to cancel out the interference of the primary sound source, thereby achieving the purpose of noise reduction. Although active noise reduction technology can effectively reduce noise, it also has some disadvantages, such as: active noise reduction technology requires complex electronic control systems and speaker systems; active noise reduction technology may cause interference from surrounding equipment or personnel; active noise reduction technology requires high-precision noise detection equipment and software; active noise reduction technology requires regular maintenance and updates. In general, active noise reduction technology can effectively reduce noise, but it is necessary to weigh and consider when choosing noise reduction technology.

[0004] Passive noise reduction technology reduces noise by weakening the noise source, cutting off the noise radiation path, and adding sound-absorbing materials to improve the structure. The simplest and most direct way is to design two or more back cavities in series. Jiang Zhaoxu and others proposed a series structure of three-layer micro-perforated plates and back cavities with different perforation rates. This structure has effective noise reduction characteristics in the low-frequency range; Wu Jinwu and others designed a retractable sound-absorbing structure with a decreasing diameter of the micro-perforated plate. This structure has good sound absorption effects in medium and low frequencies. Based on the form of the series back cavity structure, more scholars have designed different back cavity structures to study their sound absorption characteristics. Xie Suchao and others studied a multi-cavity composite sound-absorbing structure, in which the cavity of the structure is provided with a partition, which divides the cavity into multiple parallel cavities, in order to broaden the sound absorption frequency band; Li Heming and others designed an acoustic structure including a micro-perforated plate and a cavity, in which the cavity is provided with a partition, which divides the cavity into two inner and outer back cavities, solving the problem of absorbing low-frequency sound wave energy; Jin Guangjian and others provided a micro-perforated plate sound absorber and design method, in which an inner rigid wall is provided in the back cavity of the sound absorber, thereby dividing the sound absorption back cavity into multiple curved back cavities of different sizes, realizing the absorption of low-frequency noise; Chen Yun and others invented a sound-absorbing structure of a honeycomb cavity with a perforated corrugated plate obliquely inserted into a uniform resonant cavity, which improves the sound absorption performance. The design of the micro-perforated back cavity structure has been extensively studied and applied, and the existing room for improvement is very limited. Therefore, researchers began to explore more innovative solutions, such as the acoustic superstructure cell form. This new structural design not only breaks through the limitations of traditional micro-perforated back cavity, but also provides better acoustic performance.

[0005] Acoustic superstructure cells are also a type of passive noise reduction. Acoustic superstructure cells are structures composed of specially designed units that can exhibit acoustic properties that exceed those of traditional materials. Usually, special structures need to be designed to affect the propagation characteristics of sound waves. Wu Huagen and others designed an acoustic superstructure cell with a micro-perforated plate and a polygonal maze cavity with several partitions to achieve continuous broadband sound absorption; Guo Mengyuan and others proposed a high-order micro-perforated superstructure material, the principle of which is to stimulate high-order characteristics by adding perforated plates inside traditional micro-perforated metamaterials. This structure has excellent low-frequency broadband sound absorption characteristics. There are fewer designs for acoustic superstructure cells, and there is a lot of room for improvement. Therefore, the present invention mainly proposes a "return-shaped" acoustic cell structure, whose unique geometric design and acoustic performance show broad application potential in the field of acoustic control. Summary of the invention

[0006] In view of the shortcomings of the existing acoustic cellular structure technology, the present invention provides a sound-absorbing structure and application combining a micro-perforated plate and a "U-shaped" acoustic cellular structure, so as to realize the absorption of low and medium frequency noise by the micro-perforated plate sound-absorbing structure, achieve the purpose of broadening the sound absorption frequency band, improve the sound absorption performance and also improve the structural strength of the sound absorber.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A sound-absorbing structure combining a micro-perforated plate and a "U-shaped" acoustic cellular structure comprises a micro-perforated plate and a "U-shaped" acoustic cellular structure; the "U-shaped" acoustic cellular structure comprises a plurality of cavities with top openings, the depths and cross-sectional dimensions of the plurality of cavities gradually decrease, and the cavities are nested one by one from large to small from outside to inside; the tops of the plurality of cavities are all fixed on the lower surface of the micro-perforated plate; the micro-perforated plate has a plurality of plate micropores penetrating its upper and lower surfaces, and the plurality of plate micropores are located within the range of the innermost cavity; except for the outermost cavity, the bottoms of the remaining cavities have a plurality of cellular micropores penetrating their upper and lower surfaces.

[0009] To optimize the above technical solutions, the specific measures taken also include:

[0010] Furthermore, the number of the “U-shaped” acoustic cell structure is one.

[0011] Furthermore, there are multiple "U-shaped" acoustic cellular structures, and the multiple "U-shaped" acoustic cellular structures are all fixed on the lower surface of the micro-perforated plate; the cellular micropores of the micro-perforated plate are divided into multiple groups, corresponding to the innermost cavities of the multiple "U-shaped" acoustic cellular structures respectively.

[0012] Furthermore, the plate micropores are circular, square, triangular or diamond-shaped; and the apertures of the plurality of plate micropores are the same.

[0013] Furthermore, the cellular micropores are circular, square, triangular or diamond-shaped; and the pore diameters of the multiple cellular micropores in the same cavity are the same.

[0014] Furthermore, the cavity of the "U-shaped" acoustic cell structure is a polygon such as a cube, a cuboid, a cylinder or a rhombus.

[0015] The present invention also provides the application of the sound absorption structure combining the above-mentioned micro-perforated plate with the "Yu-shaped" acoustic cell structure in sound absorption.

[0016] The beneficial effects of the present invention are:

[0017] 1. The sound-absorbing structure provided by the present invention does not need to use porous sound-absorbing and noise-reducing materials, and has strong durability and good environmental performance.

[0018] 2. The sound absorption structure provided by the present invention has excellent medium and low frequency broadband sound absorption characteristics. Specifically, the multi-cell combination structure has a sound absorption coefficient of more than 0.5 in the frequency range of 600Hz-720Hz and 740Hz-1910Hz for medium and low frequency noise, and the normal incidence sound absorption coefficient of the structure reaches more than 0.8 at 940Hz-1660Hz.

[0019] 3. The sound-absorbing structure provided by the present invention has a compact structure and high noise control efficiency, and has broad application prospects in medium and low frequency noise control. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of the external structure of the sound absorbing structure of Example 1;

[0021] Figure 2 is a cross-sectional view of the sound absorbing structure of Example 1;

[0022] Figure 3 is a schematic structural diagram of the "U-shaped" acoustic cell structure of Example 1;

[0023] Figure 4 is a cross-sectional view of the “U-shaped” acoustic cell structure of Example 1;

[0024] Figure 5 is a data diagram of the sound absorption results of the sound absorption structure of Example 1;

[0025] Figure 6 is a schematic diagram of the external structure of the sound absorbing structure of Example 2;

[0026] Figure 7 is a cross-sectional view of the sound absorbing structure of Example 2;

[0027] Figure 8 is a schematic structural diagram of the "U-shaped" acoustic cell structure of Example 2;

[0028] Fig. 9 is a cross-sectional view of the “U-shaped” acoustic cell structure of Example 2;

[0029] Fig.10 is a data diagram of the sound absorption results of the sound absorption structure of Example 2;

[0030] Fig.11 is a schematic diagram of the external structure of the sound absorbing structure of Example 3;

[0031] Fig.12 is a cross-sectional view of the sound absorbing structure of Example 3;

[0032] Fig.13 is a schematic structural diagram of the "U-shaped" acoustic cell structure of Example 3;

[0033] Fig.14is a cross-sectional view of the “U-shaped” acoustic cell structure of Example 3;

[0034] Fig.15 is a data diagram of the sound absorption results of the sound absorption structure of Example 3;

[0035] The marks in the attached drawings are: 1, micro-perforated plate; 11, plate micro-holes; 2, "U-shaped" acoustic cellular structure; 21, cavity; 22, cellular micro-holes. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with specific embodiments and drawings.

[0037] Example 1

[0038] like Figure 1 and 2 As shown, this embodiment provides a sound absorption structure combining a circular micro-perforated plate and a double-layer “U-shaped” acoustic cell structure, including a micro-perforated plate 1 and a “U-shaped” acoustic cell structure 2.

[0039] like Figure 1-4 As shown, the "U-shaped" acoustic cellular structure 2 includes two cavities 21 with openings at the top ends, and the depths and cross-sectional dimensions of the two cavities 21 gradually decrease, and they are nested one by one from large to small from outside to inside. The top ends of the two cavities 21 are fixed on the lower surface of the micro-perforated plate 1. The micro-perforated plate 1 has a plurality of plate micropores 11 that penetrate its upper and lower surfaces, and the plurality of plate micropores 11 are located within the range of the inner cavity 21. The bottom of the inner cavity 21 has a plurality of cellular micropores 22 that penetrate its upper and lower surfaces. Sound waves propagate from the plate micropores 11 in the micro-perforated plate 1 to the inner cavity 21, and then the sound waves propagate from the cellular micropores 22 at the bottom of the inner cavity 21 to the outer cavity 21.

[0040] The micro-holes 11 in the micro-perforated plate 1 are circular, have the same pore diameters, and are densely arranged.

[0041] The bottom of the inner cavity 21 of the “U-shaped” acoustic cellular structure 2 has cellular micropores 22 with the same aperture.

[0042] The “U-shaped” acoustic cell structure 2 and the micro-perforated plate 1 are both circular.

[0043] The sound waves form an acoustic resonance effect in the plate micropores 11 on the micro-perforated plate 1 and the inner cavity 21 of the "Yi-shaped" acoustic cell structure 2, generating an absorption peak. The sound waves propagate from the cell micropores 22 at the bottom of the inner cavity 21 of the "Yi-shaped" acoustic cell structure 2 to the outer cavity 21 of the "Yi-shaped" acoustic cell structure 2, and the friction resistance generated by the viscous resistance inside the fluid converts the sound energy into heat energy dissipation, thereby further absorbing the sound energy and forming an acoustic absorption effect.

[0044] In this embodiment, specific parameters of the sound absorbing structure are shown in Table 1-3.

[0045] Table 1 Parameters of the micro-perforated plate of Example 1

[0046] Micro perforated plate diameter / mm Micro perforated plate thickness / mm Plate micropore radius / mm Plate micropore depth / mm 100 5 1 5

[0047] Table 2 Parameters of the inner cavity of the “U-shaped” acoustic cell structure of Example 1

[0048] Diameter / mm Wall thickness / mm Cavity depth / mm Cell micropore radius / mm Cell micropore depth / mm 60 10 30 1.165 10

[0049] Table 3 Parameters of the outer cavity of the “U-shaped” acoustic cell structure of Example 1

[0050] Diameter / mm Wall thickness / mm Cavity depth / mm 100 10 50

[0051] The sound absorption effect curve of the sound absorption structure of this embodiment is as follows: Figure 5 As shown. Figure 5 It can be seen that between 210Hz-285Hz, the sound absorption coefficient is greater than 0.5, and between 225Hz-270Hz, the normal-incident sound absorption coefficient of the structure reaches above 0.8.

[0052] Example 2

[0053] like Figure 6 and 7 As shown, this embodiment provides a sound absorption structure combining a circular micro-perforated plate and a double-layer “U-shaped” acoustic cell structure, including a micro-perforated plate 1 and a “U-shaped” acoustic cell structure 2.

[0054] like Figure 6-9 As shown, the "U-shaped" acoustic cellular structure 2 includes two cavities 21 with openings at the top ends, and the depths and cross-sectional dimensions of the two cavities 21 gradually decrease, and they are nested one by one from large to small from outside to inside. The top ends of the two cavities 21 are fixed on the lower surface of the micro-perforated plate 1. The micro-perforated plate 1 has a plurality of plate micropores 11 that penetrate its upper and lower surfaces, and the plurality of plate micropores 11 are located within the range of the inner cavity 21. The bottom of the inner cavity 21 has a plurality of cellular micropores 22 that penetrate its upper and lower surfaces. Sound waves propagate from the plate micropores 11 in the micro-perforated plate 1 to the inner cavity 21, and then the sound waves propagate from the cellular micropores 22 at the bottom of the inner cavity 21 to the outer cavity 21.

[0055] The micro-holes 11 in the micro-perforated plate 1 are circular, have the same pore diameters, and are densely arranged.

[0056] The cell micropores 22 at the bottom of the inner cavity 21 of the “U-shaped” acoustic cell structure 2 are circular, have the same pore diameters, and are densely arranged.

[0057] The “U-shaped” acoustic cell structure 2 and the micro-perforated plate 1 are both circular.

[0058] In this embodiment, specific parameters of the sound absorbing structure are shown in Table 4-6.

[0059] Table 4 Parameters of the micro-perforated plate of Example 2

[0060] Micro perforated plate diameter / mm Micro perforated plate thickness / mm Plate micropore radius / mm Plate micropore depth / mm 100 5 0.5 5

[0061] Table 5 Parameters of the inner cavity of the “U-shaped” acoustic cell structure of Example 2

[0062]

[0063]

[0064] Table 6 Parameters of the outer cavity of the “U-shaped” acoustic cell structure of Example 2

[0065] Diameter / mm Wall thickness / mm Cavity depth / mm 100 10 50

[0066] The sound absorption effect curve of the sound absorption structure of this embodiment is as follows: Figure 6 As shown. Figure 6 It can be seen that between 210Hz-295Hz, the sound absorption coefficient is greater than 0.5, and between 235Hz-265Hz, the normal-incident sound absorption coefficient of the structure reaches above 0.8.

[0067] Example 3

[0068] like Fig.11 and 12 As shown, this embodiment provides a sound absorption structure combining a square micro-perforated plate with a 2×2 arranged multi-cell double-layer “U-shaped” acoustic cell structure, including a micro-perforated plate 1 and four “U-shaped” acoustic cell structures 2.

[0069] like Figure 11-14 As shown, each "U-shaped" acoustic cellular structure 2 includes two cavities 21 with openings at the top, and the depth and cross-sectional dimensions of the two cavities 21 gradually decrease, and they are nested one by one from large to small from outside to inside. The tops of the two cavities 21 are fixed on the lower surface of the micro-perforated plate 1. The micro-perforated plate 1 has a plurality of plate micropores 11 that penetrate its upper and lower surfaces, and the plurality of plate micropores 11 are located within the range of the inner cavity 21. The bottom of the inner cavity 21 has a plurality of cellular micropores 22 that penetrate its upper and lower surfaces. Sound waves propagate from the plate micropores 11 in the micro-perforated plate 1 to the inner cavity 21, and then the sound waves propagate from the cellular micropores 22 at the bottom of the inner cavity 21 to the outer cavity 21.

[0070] The plate micropores 11 in the microperforated plate 1 are circular. The plurality of plate micropores 11 are divided into four groups, corresponding to the inner cavity 21 of different "reciprocating" acoustic cell structures 2. The plate micropores 11 in the same group have the same aperture, while the plate micropores 11 in different groups have different apertures.

[0071] The cell micropores 22 at the bottom of the inner cavity 21 of the "U-shaped" acoustic cell structure 2 are all circular. The cell micropores 22 of the same "U-shaped" acoustic cell structure 2 have equal apertures and are densely arranged, while the cell micropores 22 of different "U-shaped" acoustic cell structures 2 have different apertures.

[0072] The cavities 21 of the four "U-shaped" acoustic cellular structures 2 are in the shape of a cube / rectangle. The depths of the inner cavities 21 of the four "U-shaped" acoustic cellular structures 2 are the same, and the depths of the outer cavities 21 are not equal.

[0073] In this embodiment, specific parameters of the sound absorbing structure are shown in Tables 7-11.

[0074] Table 7 Parameters of the micro-perforated plate of Example 3

[0075] Micro perforated plate length / mm Micro perforated plate width / mm Micro perforated plate thickness / mm 112 112 2

[0076] Table 8 Parameters of the micropores of the microperforated plate of Example 3

[0077]

[0078] Table 9 Parameters of the inner cavity of the “U-shaped” acoustic cell structure of Example 3

[0079] Length / mm Width / mm Cavity depth / mm Wall thickness / mm 30 30 30 1

[0080] Table 10 Parameters of the cell micropores in the inner cavity of the “return-shaped” acoustic cell structure of Example 3

[0081]

[0082] Table 11 Parameters of the outer cavity of the “U-shaped” acoustic cell structure of Example 3

[0083]

[0084]

[0085] The sound absorption effect curve of the sound absorption structure of this embodiment is as follows: Fig.15 As shown. Fig.15 It can be seen that between 600Hz-720Hz and 740Hz-1910Hz, the sound absorption coefficient is greater than 0.5, and at 940Hz-1660Hz, the normal-incident sound absorption coefficient of the structure reaches above 0.8, and the combined structure achieves wide-band sound absorption.

[0086] In the present invention, unless otherwise specified, the scientific and technical terms used herein have the meanings commonly understood by those skilled in the art.

[0087] It should be noted that the terms such as "upper", "lower", "left", "right", "front", "back", etc. cited in the invention are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments in their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0088] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A sound absorbing structure combining a micro-perforated plate and a "U-shaped" acoustic cell structure, characterized in that: Including micro-perforated plates and "U-shaped" acoustic cell structures; The "U-shaped" acoustic cell structure includes multiple cavities with openings at the top, the depths and cross-sections of the multiple cavities gradually decrease, and they are nested one by one from large to small and from outside to inside; The top ends of the plurality of cavities are fixed to the lower surface of the micro-perforated plate; The micro-perforated plate has a plurality of plate micro-holes, and the plurality of plate micro-holes are located within the range of the innermost cavity; Except for the outermost cavity, the bottoms of the remaining cavities have multiple cellular micropores.

2. The sound absorbing structure combining the micro-perforated plate and the "U-shaped" acoustic cell structure according to claim 1 is characterized in that: The number of the "U-shaped" acoustic cell structure is one.

3. The sound absorbing structure combining the micro-perforated plate and the "U-shaped" acoustic cell structure according to claim 1 is characterized in that: There are multiple "U-shaped" acoustic cellular structures, and the multiple "U-shaped" acoustic cellular structures are all fixed on the lower surface of the micro-perforated plate; the cellular micropores of the micro-perforated plate are divided into multiple groups, which respectively correspond to the innermost cavities of the multiple "U-shaped" acoustic cellular structures.

4. The sound absorbing structure combining the micro-perforated plate and the "U-shaped" acoustic cell structure according to claim 1 is characterized in that: The plate micropores are circular, square, triangular or diamond-shaped; and the apertures of the plurality of plate micropores are the same.

5. The sound absorbing structure combining the micro-perforated plate and the "U-shaped" acoustic cell structure according to claim 1 is characterized in that: The cellular micropores are circular, square, triangular or rhombus-shaped; and the pore diameters of the multiple cellular micropores in the same cavity are the same.

6. The sound absorbing structure combining the micro-perforated plate and the "U-shaped" acoustic cell structure according to claim 1 is characterized in that: The cavity of the "U-shaped" acoustic cell structure is a cube, a rectangular parallelepiped, a cylinder or a polygon.

7. Application of a sound absorbing structure combining a micro-perforated plate as claimed in any one of claims 1 to 6 with a "U-shaped" acoustic cell structure in sound absorption.

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