A multi-layer composite sound absorption device

Abstract

This invention discloses a multi-layer composite sound-absorbing device. The double-layer micro-perforated plate of this invention includes an upper micro-perforated plate and a lower micro-perforated plate, which are connected by a disc spring device. The upper and lower micro-perforated plates are connected around their perimeter by a frame, ensuring the disc spring device between them is compressed. The density gradient porous sound-absorbing material layer is composed of at least two layers of sound-absorbing material with different densities stacked together. This multi-layer composite sound-absorbing device is composed of resonant and resistive sound-absorbing materials, achieving excellent low-frequency broadband sound absorption, effectively solving low-frequency noise pollution problems in substations, converter stations, and other fields. By adjusting the plate spacing to change the compression state of the disc springs, different stiffness characteristics are obtained, thereby enhancing the resonant sound absorption effect for specific frequency bands of noise and specifically improving the sound absorption coefficient of the device for specific frequency bands of noise.

Description

Technical Field

[0001] This invention relates to the field of noise and vibration control technology, and in particular to a multi-layer composite sound-absorbing device. Background Technology

[0002] The low-frequency noise generated by transformers, reactors, and other equipment in substations has a long wavelength, slow attenuation, and strong penetrating power, making it easy to spread to densely populated areas and causing noise pollution. Low-frequency noise pollution from substations has become a focus of environmental protection efforts.

[0003] Currently, the main sound-absorbing materials used for low-frequency noise control in substations can be divided into resonant sound-absorbing materials and porous resistive sound-absorbing materials. The former dissipates sound energy through the resonance effect of the Helmholtz resonator, and common examples include micro-perforated sound-absorbing panels, aluminum fiber sound-absorbing panels, and sound-absorbing films. However, the absorption frequency range of this type of material is too narrow, making it difficult to address high-frequency noise from components such as fans in substations. Porous resistive sound-absorbing materials utilize the resistive viscosity between the air and the wall surface within the internal pore channels to achieve sound absorption. Common examples include rock wool, aluminum silicate, polyester fiber, and polyurethane. However, the low-frequency sound absorption performance of this type of material is limited.

[0004] To effectively control substation noise, it is necessary to broaden the sound absorption frequency band of materials in addition to enhancing their low-frequency sound absorption performance. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a multi-layer composite sound absorption device, which adopts an impedance composite sound absorption structure composed of a double-layer micro-perforated plate connected by disc springs and a density gradient porous sound absorption material layer, so as to achieve good control of substation noise.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a multi-layer composite sound absorption device, which includes a double-layer micro-perforated plate, a disc spring device and a density gradient porous sound absorption material layer;

[0007] The double-layer micro-perforated plate includes an upper micro-perforated plate and a lower micro-perforated plate. The upper micro-perforated plate and the lower micro-perforated plate are connected by a disc spring device. The upper micro-perforated plate and the lower micro-perforated plate are connected by a keel around their perimeter, so that the disc spring device between them is in a compressed state.

[0008] The density gradient porous sound-absorbing material layer is composed of at least two layers of sound-absorbing material with different densities stacked together.

[0009] This invention achieves low-frequency broadband sound absorption through the coupling effect of double-layer resonant sound absorption and resistive sound absorption of porous sound-absorbing materials. The innovative aspect of the sound-absorbing material structure lies in the fact that the double-layer micro-perforated plate is connected by a rib around its perimeter, keeping the disc springs between them compressed. By controlling the compression of the disc springs, the overall natural frequency of the double-layer micro-perforated plate + disc spring device is altered, aligning it with the 100Hz frequency point where substation noise is most severe, thereby enhancing the resonance effect and specifically improving the sound absorption coefficient of the device for noise in a specific frequency band. To also address sound absorption and noise reduction in other frequency bands, the double-layer micro-perforated plate + disc spring device is connected in series with a density-gradient porous sound-absorbing material layer, broadening the sound absorption frequency band through the composite of acoustic impedance characteristics.

[0010] Furthermore, the thickness of the upper and lower micro-perforated plates is 0.5-1.0 mm, the perforation rate is 1%-3%, and the micropore diameter is 50-400 μm.

[0011] Furthermore, the disc spring device adopts a hollow structure of a cone-shaped platform, wherein the top diameter d = 5-20mm, the top extension length L = 3-10mm; the bottom diameter D = 30-50mm, the height h = 10-50mm, and the plate thickness t = 2-5mm.

[0012] Furthermore, the disc spring is made of nylon, aluminum alloy, or carbon steel, preferably aluminum alloy. When the material is aluminum alloy, it has good elastic deformation function and variable stiffness characteristics. When the double-layer micro-perforated plate resonates, the potential energy stored in the disc spring is fully released, enhancing the resonance sound absorption effect.

[0013] Furthermore, the disc spring device is fastened to the lower micro-perforated plate by bottom bolts and pressed between the upper and lower micro-perforated plates.

[0014] Furthermore, the spacing between the upper and lower micro-perforated plates is 10mm-40mm. By adjusting the plate spacing, the compression state of the disc spring can be changed, thereby obtaining different dynamic stiffness characteristics, which in turn enhances the resonant sound absorption effect on noise in a specific frequency band and can specifically improve the sound absorption coefficient of the device for noise in a specific frequency band.

[0015] Furthermore, the material of the sound-absorbing material layer is rock wool, aluminum silicate, or polyester fiber sound-absorbing cotton.

[0016] Furthermore, the thickness of the sound-absorbing material layer is 50mm-100mm, and the density of the rock wool is 48-60kg / m³. 3 Aluminum silicate has a density of 96 kg / m³. 3 -128kg / m 3 Polyester fiber sound-absorbing cotton has a density of 30-60 kg / m³. 3 .

[0017] Furthermore, a hollow cavity with a thickness of 20-50 mm is provided between the lower micro-perforated plate and the density gradient porous sound-absorbing material. The intermediate cavity between the double-layer micro-perforated plate and the double-layer density gradient resistive sound-absorbing material enhances the resonant sound absorption effect of the dual-resonance structure. Compared with the conventional single-layer cavity structure, the double-layer cavity adjusts the impedance characteristics of the sound-absorbing structure and optimizes its low-frequency sound absorption performance.

[0018] Furthermore, the cross-section of the multi-layer composite sound-absorbing device is square, with a side length a = 100-300 mm.

[0019] Due to the adoption of the above technical solution, the beneficial effects of this invention are reflected in the following aspects:

[0020] (1) The double-layer micro-perforated plate compresses the disc spring to form an acoustic superstructure. By changing the compression state of the disc spring, the natural frequency of the structure is adjusted, the resonance effect is enhanced, and the thickness of the overall structure is effectively reduced.

[0021] (2) By stacking high and low density sound-absorbing materials, a density gradient structure is formed, which enhances the resistive energy dissipation effect on noise.

[0022] (3) By using double-layer micro-perforated plates and density gradient structure sound-absorbing materials, multiple sound absorption peaks are formed, effectively broadening the sound absorption frequency band. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the multi-layer composite sound-absorbing device of the present invention;

[0024] In the diagram: 1-Upper micro-perforated plate; 2-Lower micro-perforated plate; 3-Disc spring device; 4-Hollow cavity; 5-Low-density sound-absorbing material layer; 6-High-density sound-absorbing material layer.

[0025] Figure 2 This is a schematic diagram showing the dimensions of the disc spring device in this invention. Detailed Implementation

[0026] Example 1

[0027] A multi-layer composite sound absorption device comprises a double-layer micro-perforated plate, a disc spring device, and a layer of density-gradient porous sound-absorbing material. It achieves low-frequency broadband sound absorption through the coupling effect of the double-layer resonant sound absorption and the resistive sound absorption of the porous sound-absorbing material.

[0028] The double-layer microperforated plate (upper microperforated plate 1 and lower microperforated plate 2) has a thickness of 0.5 mm, a perforation rate of 1%, and a micropore diameter of 50 μm.

[0029] The disc spring device adopts a hollow structure with a cone-shaped platform, wherein the top diameter d = 5mm, the top extension length L = 3mm, the bottom diameter D = 30mm, the height h = 10mm, and the plate thickness t = 2mm.

[0030] The disc spring is made of nylon.

[0031] The disc spring device is fastened to the lower micro-perforated plate by bottom bolts and pressed between the two micro-perforated plates. By adjusting the plate spacing, the compression state of the disc spring is changed, thereby obtaining different dynamic stiffness characteristics. The distance between the upper micro-perforated plate 1 and the lower micro-perforated plate 2 is 10mm.

[0032] The density gradient porous sound-absorbing material layer is composed of two layers of sound-absorbing material with different densities (i.e., a low-density sound-absorbing material layer 5 and a high-density sound-absorbing material layer 6 stacked together). The type of sound-absorbing material is rock wool.

[0033] Each layer of the density gradient porous sound-absorbing material is 50mm thick, and the density of the rock wool in the upper low-density sound-absorbing material layer is 48kg / m³. 3 The density of the rock wool in the lower high-density sound-absorbing material layer is 60 kg / m³. 3 .

[0034] There is a hollow cavity between the bottom micro-perforated plate and the low-density sound-absorbing material layer, and the thickness of the hollow cavity is 20mm.

[0035] The cross-section of the multi-layer composite sound-absorbing device is square, with a side length a = 100 mm.

[0036] Example 2

[0037] A multi-layer composite sound absorption device comprises a double-layer micro-perforated plate, a disc spring device, and a layer of density-gradient porous sound-absorbing material. It achieves low-frequency broadband sound absorption through the coupling effect of the double-layer resonant sound absorption and the resistive sound absorption of the porous sound-absorbing material.

[0038] The double-layer microperforated plate (upper microperforated plate 1 and lower microperforated plate 2) has a thickness of 1.0 mm, a perforation rate of 3%, and a micropore diameter of 400 μm.

[0039] The disc spring device adopts a hollow structure with a cone-shaped platform, wherein the top diameter d = 20 mm, the top extension length L = 10 mm, the bottom diameter D = 50 mm, the height h = 50 mm, and the plate thickness t = 5 mm.

[0040] The disc spring is made of carbon steel.

[0041] The disc spring device is fastened to the lower micro-perforated plate by bottom bolts and pressed between the two micro-perforated plates. By adjusting the plate spacing, the compression state of the disc spring is changed, thereby obtaining different dynamic stiffness characteristics. The distance between the upper micro-perforated plate 1 and the lower micro-perforated plate 2 is 40mm.

[0042] The density gradient porous sound-absorbing material layer is composed of two layers of sound-absorbing material with different densities (i.e., a low-density sound-absorbing material layer 5 and a high-density sound-absorbing material layer 6 stacked together). The type of sound-absorbing material is polyester fiber sound-absorbing cotton.

[0043] Each layer of the density gradient porous sound-absorbing material is 100mm thick, and the upper low-density sound-absorbing material layer contains polyester fiber sound-absorbing cotton with a density of 30kg / m³. 3 The polyester fiber sound-absorbing cotton in the lower high-density sound-absorbing material layer has a density of 60 kg / m³. 3 .

[0044] There is a hollow cavity between the bottom micro-perforated plate and the low-density sound-absorbing material layer, and the thickness of the hollow cavity is 50mm.

[0045] The cross-section of the multi-layer composite sound-absorbing device is square, with a side length a = 300 mm.

[0046] Example 3

[0047] A multi-layer composite sound absorption device comprises a double-layer micro-perforated plate, a disc spring device, and a layer of density-gradient porous sound-absorbing material. It achieves low-frequency broadband sound absorption through the coupling effect of the double-layer resonant sound absorption and the resistive sound absorption of the porous sound-absorbing material.

[0048] The double-layer microperforated plate (upper microperforated plate 1 and lower microperforated plate 2) has a thickness of 0.8 mm, a perforation rate of 2%, and a micropore diameter of 200 μm.

[0049] The disc spring device adopts a hollow structure with a cone-shaped platform, wherein the top diameter d = 10 mm, the top extension length L = 5 mm, the bottom diameter D = 40 mm, the height h = 30 mm, and the plate thickness t = 4 mm.

[0050] The disc spring is made of aluminum alloy.

[0051] The disc spring device is fastened to the lower micro-perforated plate by bottom bolts and pressed between the two micro-perforated plates. By adjusting the plate spacing, the compression state of the disc spring is changed, thereby obtaining different dynamic stiffness characteristics. The distance between the upper micro-perforated plate 1 and the lower micro-perforated plate 2 is 30mm.

[0052] The density gradient porous sound-absorbing material layer is composed of two layers of sound-absorbing materials with different densities (i.e., a low-density sound-absorbing material layer 5 and a high-density sound-absorbing material layer 6 stacked together). The type of sound-absorbing material is aluminum silicate.

[0053] Each layer of the density gradient porous sound-absorbing material is 80mm thick, with the upper low-density sound-absorbing material layer containing aluminum silicate with a density of 96kg / m³. 3 The density of aluminum silicate in the lower high-density sound-absorbing material layer is 128 kg / m³. 3 .

[0054] There is a hollow cavity between the bottom micro-perforated plate and the low-density sound-absorbing material layer, and the thickness of the hollow cavity is 35mm.

[0055] The cross-section of the multi-layer composite sound-absorbing device is square, with a side length a = 200 mm.

[0056] The sound-absorbing device in the examples was processed into standard-sized samples, and its sound absorption coefficient was tested according to GB / T20247-2008 "Acoustic Reverberation Chamber Sound Absorption Measurement". Since the main peak frequency of substation noise is between 100-500Hz, only the sound absorption coefficient and overall noise reduction coefficient in this range were compared.

[0057] Table 1. Sound absorption test results of the sound-absorbing devices in Examples 1-3

[0058]

[0059] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A multi-layer composite sound-absorbing device, characterized in that, Includes a double-layer micro-perforated plate, a disc spring device, and a density gradient porous sound-absorbing material layer; The double-layer micro-perforated plate includes an upper micro-perforated plate and a lower micro-perforated plate. The upper micro-perforated plate and the lower micro-perforated plate are connected by a disc spring device. The upper micro-perforated plate and the lower micro-perforated plate are connected by a keel around their perimeter, so that the disc spring device between them is in a compressed state. The density gradient porous sound-absorbing material layer is composed of at least two layers of sound-absorbing material with different densities stacked together.

2. The multi-layer composite sound-absorbing device as described in claim 1, characterized in that, The thickness of the upper and lower micro-perforated plates is 0.5-1.0 mm, the perforation rate is 1%-3%, and the micropore diameter is 50-400 μm.

3. The multi-layer composite sound-absorbing device as described in claim 1, characterized in that, The disc spring device adopts a hollow structure with a cone-shaped platform, wherein the top diameter d = 5-20mm, the top extension length L = 3-10mm; the bottom diameter D = 30-50mm, the height h = 10-50mm, and the plate thickness t = 2-5mm.

4. The multi-layer composite sound-absorbing device as described in claim 1, characterized in that, The disc spring is made of nylon, aluminum alloy, or carbon steel.

5. The multi-layer composite sound-absorbing device as described in claim 1, characterized in that, The disc spring device is fastened to the lower micro-perforated plate by bottom bolts and pressed between the upper and lower micro-perforated plates.

6. The multi-layer composite sound-absorbing device as described in claim 1, characterized in that, The spacing between the upper and lower micro-perforated plates is 10mm-40mm. By adjusting the plate spacing, the compression state of the disc spring can be changed, thereby obtaining different dynamic stiffness characteristics and enhancing the resonant sound absorption effect on noise in specific frequency bands.

7. The multi-layer composite sound-absorbing device as described in claim 1, characterized in that, The material of the sound-absorbing material layer is rock wool, aluminum silicate, or polyester fiber sound-absorbing cotton.

8. The multi-layer composite sound-absorbing device as described in claim 7, characterized in that, The thickness of the sound-absorbing material layer is 50mm-100mm, and the density of the rock wool is 48-60kg / m³. 3 Aluminum silicate has a density of 96 kg / m³. 3 -128kg / m 3 Polyester fiber sound-absorbing cotton has a density of 30-60 kg / m³. 3 .

9. A multi-layer composite sound-absorbing device as described in claim 1, characterized in that, A hollow cavity is provided between the lower micro-perforated plate and the density gradient porous sound-absorbing material, and the thickness of the hollow cavity is 20-50mm.

10. A multi-layer composite sound-absorbing device as described in claim 1, characterized in that, Its cross-section is square, with a side length a = 100-300 mm.

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