A low-frequency broadband flat plate sound absorption structure

Abstract

The present invention discloses a low-frequency broadband flat-plate sound-absorbing structure, comprising a frame, a front panel and a back panel fixedly arranged on the upper and lower sides of the frame, and a sound-absorbing body enclosed by the frame, the front panel and the back panel for absorbing low-frequency noise; a plurality of sound-absorbing holes are arranged on the front panel, one side of the sound-absorbing holes faces the sound source, and the other side is connected to the sound-absorbing body. The sound-absorbing body is composed of a plurality of partitions arranged in parallel in the frame, one end of the partition is fixed to the inner wall of one side of the frame, and the other end is gap-matched with the inner wall of the other side of the frame; the partition divides the space in the frame into serpentine channels, and the channels are provided with frame inner walls for separation, and the channels between adjacent frame inner walls form a MIE-type resonance cavity. The present invention has a compact structure, light weight, low surface density, a wide low-frequency sound absorption band, and good low-frequency sound absorption performance.

Description

Technical Field

[0001] The invention relates to a sound absorbing structure, in particular to a low-frequency broadband flat plate sound absorbing structure. Background Art

[0002] With the development of modern society, the quality of life is constantly improving, and environmental problems, especially noise problems, are becoming more and more serious. In recent years, my country's transportation facilities have been gradually improved, transportation has developed rapidly, the impact of environmental noise has been expanding, and traffic noise problems have become increasingly prominent. The control of noise pollution has become a problem that needs to be solved urgently worldwide. Expressways, subways, high-speed railways and air transportation are the symbols of urban modernization, but the noise problem of modern transportation vehicles during high-speed driving has always affected people's normal work, study and rest. Because the passing noise has the characteristics of low frequency, temporary and concentrated, it makes the control of passing noise very difficult. In view of this, the development of a low-frequency and broadband flat sound-absorbing structure is particularly important for improving people's living environment and improving people's quality of life.

[0003] At present, the control and management of passing noise in China mainly adopts sound insulation barriers. Traditional sound insulation barriers are generally a combination structure of double-layer steel plates and porous sound-absorbing materials. This technical solution has poor low-frequency sound absorption effect and general overall sound insulation performance. New low-frequency sound absorption structures usually adopt a sound absorption mechanism of local resonance and porous materials, which has a certain absorption effect on low-frequency passing noise, but its structure is relatively thick, the low-frequency sound absorption performance is general, and the application range is relatively narrow. For example, the Chinese patent with publication number CN1512482 discloses a sound-absorbing material and its manufacturing method and application, wherein the sound-absorbing material has wavy folds, and the convex surface of the wavy folds has fine gaps; the sound absorption principle of this technical solution is the same as the sound absorption principle of micro-perforated plates, and the sound absorption performance is similar to that of micro-perforated plates, so its sound absorption bandwidth is narrow and the low-frequency sound absorption performance is poor. The Chinese patent with publication number CN1219989A discloses a track noise control device, including a sound-absorbing plate installed on the rails of the track, which is supported on the rails by elastic elements and self-supporting across the space between the rails; this technical solution absorbs the passing noise from the train through the combined action of the anechoic resonant cavity and porous lightweight building material particles, but is limited by the height of the rails, the thickness of the structure is relatively thin, and the volume of the anechoic resonant cavity is relatively small, so its low-frequency sound absorption performance is relatively poor. In view of this, it is particularly important to develop an efficient, low-frequency, broadband sound-absorbing structure to control and manage environmental noise. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a flat sound absorbing structure for low-frequency broadband sound absorption.

[0005] Technical solution: The low-frequency broadband flat-plate sound-absorbing structure described in the present invention comprises a frame, a front panel and a back panel fixed on the upper and lower sides of the frame, and a sound-absorbing body enclosed by the frame, the front panel and the back panel for absorbing low-frequency noise; a plurality of sound-absorbing holes are arranged on the front panel, one side of the sound-absorbing holes faces the sound source, and the other side is connected to the sound-absorbing body.

[0006] Furthermore, the sound absorber is composed of a plurality of partitions arranged in parallel in the frame, one end of the partition is fixed to the inner wall of one side of the frame, and the other end is loosely matched with the inner wall of the other side of the frame; the partition divides the space in the frame into a serpentine channel, and the channel is provided with a frame inner wall for separation, and the channel between adjacent frame inner walls forms a MIE type resonance cavity. At the same time, in order to ensure the stability of the sound absorption process, each MIE type resonance cavity is correspondingly provided with a sound absorption hole connected thereto, ensuring that the number of sound absorption holes matches the number of MIE type resonance cavities of the sound absorber, and the cross-sectional shape of the sound absorption hole is circular or quadrilateral.

[0007] Furthermore, the sound absorption frequency of the MIE type resonant cavity decreases as the distance between the inner walls of the frame increases. This is because the MIE type resonant cavity is a Fabry-Perot (FP) type resonant structure, and its sound absorption performance is related to its cavity depth, cavity cross-sectional shape, and cavity volume. By adjusting the cavity volume, the sound absorption coefficient and sound absorption frequency band can be designed. Usually, the number of MIE type resonant cavities is 3 to 25. Considering the low-frequency acoustic impedance matching problem, the preferred number of resonant cavities here is 9.

[0008] The partitions are arranged at equal intervals, and the spacing between adjacent partitions is 4-20 mm, preferably 4 mm. Under the premise of ensuring the overall rigidity of the structure, the low-frequency sound absorption performance of the flat sound absorption structure is improved and its low-frequency sound absorption band is broadened.

[0009] Furthermore, the sound absorbing structure has a length of 50-300 mm, a width of 50-200 mm, and a depth of 30-250 mm; the frame is connected to the front panel and the back panel by ultrasonic welding.

[0010] Working principle: When the sound wave is incident vertically on the front panel of the structure, part of the sound wave is reflected due to the effect of the panel, thereby reducing the transmitted sound energy and improving the sound insulation performance of the flat sound-absorbing structure; at the same time, part of the sound wave enters the sound-absorbing body through the sound-absorbing hole. When the incident wavelength matches the acoustic impedance of the MIE-type resonant cavity, vertical resonance is generated, and the sound wave oscillates in the resonant cavity, overcoming friction resistance and consuming sound energy to achieve the purpose of sound absorption; at the same time, the sound wave propagates in the resonant cavity, and due to the slow wave effect, part of the sound energy is consumed, thereby improving the overall sound absorption performance of the structure. Usually, a single MIE-type resonant cavity corresponds to a resonant frequency and absorbs sound waves at the resonant frequency. However, due to the adjacent coupling between the resonant cavities, multiple coupled resonant frequencies are generated, thereby broadening the sound absorption frequency range and improving the overall sound absorption performance of the structure.

[0011] Beneficial effects: Compared with the prior art, the present invention has the following significant features:

[0012] 1. The overall structure of the present invention is compact, light in weight and low in surface density;

[0013] 2. The low-frequency sound absorption band of the present invention is relatively wide, and the low-frequency sound absorption performance is good;

[0014] 3. The sound absorption performance of the present invention is related to the structural parameters. By changing the structural parameters to design the sound absorption frequency band and improve the sound absorption coefficient, the low-frequency sound insulation performance is ensured to be good, and the existing low-frequency sound absorption / insulation layer can be widely replaced. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the structure of the present invention;

[0016] Figure 2 It is a front view of the present invention;

[0017] Figure 3 is a top view of the present invention;

[0018] Figure 4 yes Figure 2 AA direction cross-sectional view;

[0019] Figure 5 yes Figure 3 BB direction cross-sectional view;

[0020] Figure 6 is the sound absorption characteristic curve of the present invention;

[0021] Figure 7 It is the transmission loss characteristic curve of the present invention. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with the embodiments and drawings.

[0023] like Figure 1-5 As shown, the flat sound absorbing structure includes a front panel 1, a frame 2, a back panel 3 and a sound absorbing body 4 formed thereby, which are connected by ultrasonic welding. The flat sound absorbing structure has an outer dimension of 128 mm (W) × 128 mm (D) × 30 mm (H); the sound absorbing body 4 is composed of 24 parallel partitions 41, the spacing between adjacent partitions 41 is 4 mm, one end of the partition 41 is fixed to the inner wall of one side of the frame 2, and the other end is gapped with the inner wall of the other side of the frame 2, the gap size is 6 mm, the partition 41 divides the space inside the frame 2 into a serpentine channel, eight frame inner walls 5 are arranged on the channel, and the channel between adjacent frame inner walls 5 forms a MIE type resonance cavity 7, and a total of 9 MIE type resonance cavities 7 are arranged in a zigzag shape in the sound absorbing body 4.

[0024] like Figure 3 As shown, 9 narrow rectangular sound-absorbing holes 6 are arranged on the front panel 1, which correspond to 9 MIE-type resonance cavities respectively, namely, No. 1 sound-absorbing hole, No. 2 sound-absorbing hole, No. 3 sound-absorbing hole, No. 4 sound-absorbing hole, No. 5 sound-absorbing hole, No. 6 sound-absorbing hole, No. 7 sound-absorbing hole, No. 8 sound-absorbing hole and No. 9 sound-absorbing hole from top to bottom; wherein, the length of the MIE-type resonance cavity corresponding to the No. 1 sound-absorbing hole is 429 mm, which can absorb noise at 200-205 Hz; the length of the MIE-type resonance cavity corresponding to the No. 2 sound-absorbing hole is 408 mm, which can absorb noise at 210-215 Hz; the length of the MIE-type resonance cavity corresponding to the No. 3 sound-absorbing hole is 388 mm, which can absorb noise at 221-226 Hz; the length of the MIE-type resonance cavity corresponding to the No. 4 sound-absorbing hole is 369 mm, which can absorb noise at 232-238 Hz; the length of the MIE-type resonance cavity corresponding to the No. 5 sound-absorbing hole is 350mm, which can absorb noise at 245~251 Hz; the length of the MIE-type resonance cavity corresponding to the No. 6 sound-absorbing hole is 333mm, which can absorb noise at 258~265 Hz; the length of the MIE-type resonance cavity corresponding to the No. 7 sound-absorbing hole is 317mm, which can absorb noise at 271~277 Hz; the length of the MIE-type resonance cavity corresponding to the No. 8 sound-absorbing hole is 300mm, which can absorb noise at 286~290 Hz; the length of the MIE-type resonance cavity corresponding to the No. 9 sound-absorbing hole is 208.5mm, which can absorb noise at 296~300 Hz. At the same time, due to the proximity coupling between adjacent resonance cavities, the sound absorption frequency range is widened to 200~300Hz.

[0025] like Figures 6 and 7The above flat-plate sound-absorbing structure was subjected to finite element simulation analysis to obtain its sound absorption characteristics and transmission loss characteristics. When the overall thickness of the structure is 30 mm, the low-frequency sound absorption performance of the flat-plate sound-absorbing structure is good, and the average sound absorption coefficient of the structure in the design frequency band of 200-300 Hz is about 0.67; at the same time, the overall sound insulation performance of the flat-plate sound-absorbing structure is good, and the average sound insulation of the structure in the design frequency band of 200-300 Hz is about 25 dB.

[0026] The flat plate sound absorption structure of this embodiment is used for noise control in high-speed train carriages, and the flat plate sound absorption structure is used to replace the existing low-frequency sound absorption / insulation layer. The flat plate sound absorption structure has good low-frequency sound absorption performance and can effectively reduce the reverberation noise in the carriage during high-speed running of the train; at the same time, the flat plate sound absorption structure has good low-frequency sound insulation performance and can effectively isolate the passing noise of the train during high-speed running, thereby improving the riding comfort of passengers.

Claims

1. A low-frequency broadband flat-plate sound-absorbing structure, characterized in that: The invention comprises a frame (2), a front panel (1) and a back panel (3) fixedly arranged on the upper and lower sides of the frame (2), and a sound absorbing body (4) enclosed by the frame (2), the front panel (1) and the back panel (3) for absorbing low-frequency noise; the front panel (1) is provided with a plurality of sound absorbing holes (6), one side of the sound absorbing holes (6) faces the sound source, and the other side is connected to the sound absorbing body (4); the sound absorbing body (4) is composed of a plurality of partitions (41) arranged in parallel in the frame (2), one end of the partition (41) is fixed to the inner wall of one side of the frame (2), and the other end is gap-matched with the inner wall of the other side of the frame (2); the partition (41) divides the space inside the frame (2) into a serpentine channel, the channel is provided with a frame inner wall (5) for separation, and the channel between adjacent frame inner walls (5) forms a MIE type resonance cavity (7).

2. The low-frequency broadband flat-plate sound absorbing structure according to claim 1, characterized in that: The MIE type resonance cavity (7) is correspondingly provided with a sound absorption hole (6) connected thereto, and the cross-sectional shape of the sound absorption hole (6) is circular or quadrilateral.

3. The low-frequency broadband flat-plate sound absorbing structure according to claim 2, characterized in that: The sound absorption frequency of the MIE type resonance cavity (7) decreases as the distance between the inner walls (5) of the frame increases.

4. The low-frequency broadband flat-plate sound absorbing structure according to claim 1, characterized in that: The number of the MIE type resonant cavities (7) is 3 to 25.

5. The low-frequency broadband flat-plate sound absorbing structure according to claim 1, characterized in that: The partitions (41) are arranged at equal intervals, and the interval between adjacent partitions (41) is 4 to 20 mm.

6. The low-frequency broadband flat-plate sound absorbing structure according to claim 1, characterized in that: The sound absorbing structure has a length of 50 to 300 mm, a width of 50 to 200 mm, and a depth of 30 to 250 mm.

7. The low-frequency broadband flat-plate sound absorbing structure according to claim 1, characterized in that: The frame (2) is connected to the front panel (1) and the back panel (3) by ultrasonic welding.

Images