Combined stepped extension tube sound absorption device

Abstract

The application provides a combined stepped extension pipe sound absorption device, which comprises an aluminum honeycomb core material, the aluminum honeycomb core material comprises a plurality of honeycomb cells, and a stepped extension pipe is arranged in each honeycomb cell; each stepped extension pipe has different specifications; the two surfaces of the aluminum honeycomb core material are respectively sealed with a microporous plate and a rigid backing; one end of the stepped extension pipe has a gap with the rigid backing; the other end of the stepped extension pipe is tightly connected with micropores of the microporous plate, and the size of the hole at the end of the stepped extension pipe is the same as the size of the circular small hole of the microporous plate. The application utilizes the Helmholtz resonance principle and the heat loss and viscous loss in the sound transmission process, realizes low-frequency band sound absorption and wide-frequency sound absorption on the basis of ensuring the thickness of the device, and makes the device have good mechanical bearing performance while having sound absorption effect. The application has simple structure, very low cost and very wide engineering application value.

Description

Technical Field

[0001] This invention belongs to the field of noise reduction technology, specifically relating to a combined stepped extension tube sound absorption device. Background Technology

[0002] With the improvement of living standards, noise pollution has become an issue that cannot be ignored. The development of high-performance sound-absorbing devices can meet the key needs of current environmental protection and comfort research. In railway and highway transportation systems, sound-absorbing devices are used in the design of various vehicles to ensure that noise is controlled within a reasonable range during operation, protecting passengers and precision instruments. Furthermore, sound-absorbing devices are indispensable in various fields such as construction and aerospace.

[0003] Sound absorption devices can be structurally classified into porous material sound absorption devices and Helmholtz resonant sound absorption devices. Designing and improving different materials, and combining different types of sound absorption devices, can significantly enhance their sound absorption effect. Helmholtz resonant sound absorption devices utilize the principle of Helmholtz resonance. Sound waves enter the cavity through slits or micropores, resonating within the cavity and converting sound energy into heat energy, thus absorbing noise. Existing research has found that the sound absorption capacity of Helmholtz resonant sound absorption devices is significantly affected by the micropores and the cavity itself. By modifying the micropores and the cavity, absorption of noise at different frequencies can be achieved. In the research and design process, high-frequency noise can often be effectively absorbed by porous materials, while mid- and low-frequency noise requires absorption by Helmholtz-type sound absorption devices. For a typical Helmholtz resonator, a deep cavity can absorb lower frequency noise, but this also means that such a structure occupies more space in applications such as vehicles. Therefore, how to achieve mid-to-low frequency sound absorption in the smallest possible space is a problem that sound absorption devices urgently need to solve.

[0004] Traditional Helmholtz-type sound-absorbing devices use micro-perforated plates and a back cavity behind the plate as their basic structure. Since the absorption frequency is affected by the cavity depth and the diameter of the micropores, achieving low-frequency sound absorption requires extremely small micropores and a very deep cavity, placing stringent spatial requirements on the sound-absorbing structure. Furthermore, ordinary perforated plates have a single resonant frequency and a narrow absorption frequency range, enabling them to absorb only specific types of noise. Simultaneously, traditional micro-perforated plate sound-absorbing structures have poor structural strength and cannot withstand loads and impacts in application scenarios. Summary of the Invention

[0005] This invention addresses design goals such as a wide sound absorption bandwidth, low sound absorption frequency, and excellent impact resistance and load-bearing capacity. It employs the basic mechanism of Helmholtz resonance, where noise enters the Helmholtz resonant cavity through micropores (gap), and the resonance at a specific frequency converts sound energy into heat energy, achieving perfect noise absorption. Based on a honeycomb core material, this invention improves the load-bearing performance of the sound absorption device. By adding multi-stage extension tubes to the ends of the micropores in the microporous plate, absorption of noise in different frequency domains is achieved. The parallel arrangement of different cavities further broadens the sound absorption bandwidth of the device. The addition of multi-stage extension tubes significantly reduces the thickness of the sound absorption device, enabling its application in the space-constrained interiors of trains, automobiles, airplanes, and ships.

[0006] The specific technical solution is as follows:

[0007] A combined stepped extension tube sound absorption device includes an aluminum honeycomb core material, which comprises multiple honeycomb cells, each of which contains a stepped extension tube; each stepped extension tube has different specifications.

[0008] The aluminum honeycomb core material is sealed with a microporous plate and a rigid backing on both sides; one end of the stepped extension tube has a gap of more than 2mm with the rigid backing; the other end of the stepped extension tube is tightly connected to the micropores of the microporous plate, and the opening size at the end of the stepped extension tube is the same as the size of the circular small hole of the microporous plate.

[0009] Each stepped extension tube comprises four sections, namely the first section, the second section, the third section, and the fourth section, which are cylindrical cavities of different lengths and diameters, and the four cylindrical cavities are connected in sequence.

[0010] The aluminum honeycomb core material consists of seven honeycomb cells arranged in parallel.

[0011] The rigid backing surface is provided with multiple raised hexagonal sealing devices, each of which has the same size as the inner hexagon of the aluminum honeycomb core cell, for a tight connection between the rigid backing and the honeycomb core.

[0012] The circular holes of the microplate are coaxial with the hexagonal inscribed circles of the aluminum honeycomb core cells.

[0013] This invention provides a combined stepped extension tube sound-absorbing device that cleverly utilizes the Helmholtz resonance principle and the heat and viscous losses during sound transmission. While ensuring the device's thickness, it achieves low-frequency and wide-band sound absorption, and also provides excellent mechanical load-bearing performance while maintaining sound absorption. This invention has a simple structure and very low cost. It can be densely installed in rail vehicles such as high-speed rail, urban rail, and subways, as well as in ship cabins, in any location requiring solutions to low- and mid-frequency noise. It can also be used as a load-bearing component in train bodies, aircraft cabin floors, etc., demonstrating its wide range of engineering applications. Attached Figure Description

[0014] Figure 1 This is an assembly diagram of the device of the present invention;

[0015] Figure 2 This is an exploded view of the present invention;

[0016] Figure 3 This is a schematic diagram of the stepped extension tube structure of the present invention;

[0017] Figure 4 This is a schematic diagram of the sound absorption principle of the present invention. Detailed Implementation

[0018] This invention discloses a combined stepped extension tube sound-absorbing device, such as... Figure 1 and Figure 2 The diagram shows an aluminum honeycomb core material 3, which comprises seven honeycomb cells, each of which contains a stepped extension tube 2; each stepped extension tube 2 has a different specification.

[0019] The aluminum honeycomb core material 3 is sealed on both sides with a microporous plate 1 and a rigid backing 4. The microporous plate 1 has small circular holes, which are arranged identically within the aluminum honeycomb core 3. Each hole corresponds to a cavity within the aluminum honeycomb core 3. The circular holes in the microporous plate 1 are coaxial with the inscribed circles of the hexagonal cells of the aluminum honeycomb core 3. One end of the stepped extension tube 2 has a gap of more than 2 mm with the rigid backing 4 to ensure that sound waves can be effectively transmitted into the extension tube. The other end of the stepped extension tube 2 is tightly connected to the micropores of the microporous plate 1, and the opening size at the end of the stepped extension tube 2 is the same as the size of the circular holes in the microporous plate 1.

[0020] like Figure 3 As shown, the stepped extension tube 2 is manufactured by 3D printing from stainless steel microtubes. Each stepped extension tube 2 includes four sections, namely the first section 21, the second section 22, the third section 23, and the fourth section 24. The four sections are cylindrical cavities of different lengths and diameters. The four cylindrical cavities are connected in sequence and form a whole.

[0021] The aluminum honeycomb core material 3 comprises seven honeycomb cells arranged in parallel; each cell contains a stepped extension tube 2 of different sizes.

[0022] The rigid backing 4 has multiple raised hexagonal sealing devices on its surface. Each hexagonal sealing device has the same size as the inner hexagonal ring of the aluminum honeycomb core 3 cell, which is used to tightly connect the rigid backing 4 and the honeycomb core 3.

[0023] The microporous plate 1, the aluminum honeycomb core 3, and the rigid backing 4 together form a chamber that is connected to the outside world only by micropores, and the stepped extension tube 2 is located inside the chamber.

[0024] The invention basis and working principle of this combined stepped extension tube sound absorption device are as follows: When sound waves are transmitted to the surface of the device, they first enter the stepped extension tube 2 through the small holes of the microporous plate 1. The chambers of different diameters and lengths of the stepped extension tube 2 form different Helmholtz resonant cavities. The sound waves resonate in the resonant cavities of different sizes. According to the Helmholtz resonance principle, the resonance converts the energy of the sound waves into heat energy. After passing through the stepped extension tube 2, the sound waves enter the cavity composed of the microporous plate 1, the aluminum honeycomb core material 3, and the rigid backing 4. At this time, the cavity and the microporous plate 1 form a Helmholtz resonant cavity, and the sound waves resonate in the cavity, further attenuating their energy.

[0025] Besides the sound wave energy attenuation caused by Helmholtz resonance, which contributes to the sound absorption effect of the device, the micropores in the microperforated plate 1 and the stepped extension tube 2 form a thin tubular structure, causing sound waves to attenuate during transmission due to heat loss and viscous loss. Compared to traditional microperforated plate structures, the stepped extension tube 2 effectively extends the length of the microperforated plate 1, increasing the heat loss and viscous loss of sound waves. Simultaneously, this device conforms to the sound absorption theory of microperforated plates, as the stepped extension tube 2 effectively increases the plate thickness. The introduction of the stepped extension tube 2 gives this sound absorption device better low-frequency sound absorption performance.

[0026] This combined stepped extension tube sound-absorbing device can achieve good sound absorption for low-frequency noise with a thickness of only 1 / 2 to 1 / 3. Each stepped extension tube 2 has four cylindrical cavities of different sizes. This structural design can excite Helmholtz resonances in a wider frequency range, greatly broadening the sound absorption frequency band of the structure.

[0027] This device consists of seven sound-absorbing chambers, each containing a stepped extension tube of a different size. This design allows each chamber to generate Helmholtz resonance at different frequencies. The seven chambers are arranged in parallel, and when sound waves are incident, the absorption frequencies superimpose, effectively absorbing noise over a wide frequency range. Figure 4 As shown.

[0028] Meanwhile, compared to micro-perforated panels, the cavity of this structure has significantly improved structural strength due to the support of the aluminum honeycomb core. The excellent mechanical properties and low density characteristics of the aluminum honeycomb core make this sound-absorbing device an excellent load-bearing structure, which can be applied in scenarios such as high-speed train carriage floors and ship engine room walls.

Claims

1. A combined stepped extension tube sound-absorbing device, characterized in that, The aluminum honeycomb core material (3) includes multiple honeycomb cells, and each honeycomb cell contains a stepped extension tube (2); each stepped extension tube (2) has different specifications. The aluminum honeycomb core material (3) is sealed with a microporous plate (1) and a rigid backing (4) on both sides respectively; one end of the stepped extension tube (2) has a gap with the rigid backing (4); the other end of the stepped extension tube (2) is tightly connected to the micropores of the microporous plate (1), and the opening size at the end of the stepped extension tube (2) is the same as the size of the circular small hole of the microporous plate (1); The stepped extension tube (2) includes four sections, namely the first section (21), the second section (22), the third section (23), and the fourth section (24), which are cylindrical cavities of different lengths and diameters, and the four cylindrical cavities are connected in sequence.

2. The combined stepped extension tube sound absorption device according to claim 1, characterized in that, The aluminum honeycomb core material (3) comprises seven parallel honeycomb cells arranged in a row.

3. The combined stepped extension tube sound-absorbing device according to claim 1, characterized in that, The rigid backing (4) has multiple raised hexagonal sealing devices on its surface. Each hexagonal sealing device has the same size as the inner hexagonal circle of the aluminum honeycomb core material (3) cell, and is used to tightly connect the rigid backing (4) and the honeycomb core material (3).

4. The combined stepped extension tube sound-absorbing device according to claim 1, characterized in that, The circular holes of the microporous plate (1) and the hexagonal inscribed circles of the honeycomb cells of the aluminum honeycomb core material (3) are coaxial.

5. The combined stepped extension tube sound-absorbing device according to claim 1, characterized in that, The stepped extension tube (2) has a gap of more than 2 mm between one end and the rigid backing (4).

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