Frequency-adjustable sound absorption wall based on Helmholtz resonators

Abstract

The utility model discloses a frequency-adjustable sound absorption wall based on Helmholtz resonators, which comprises the Helmholtz resonators and a gear rack transmission mechanism, and the Helmholtz resonators are vertically and horizontally arranged and bonded to form the sound absorption wall. A piston plate is arranged in the Helmholtz resonator, a rack is fixedly connected to the piston plate, the gear drives the rack to do linear motion, the piston plate is driven to do reciprocating motion, the size of a cavity of the Helmholtz resonator is changed, and therefore the sound absorption frequency of the sound absorption wall is changed. Sound absorption of the sound absorption wall is based on the principle of Helmholtz resonance, and common low and medium frequency noise in daily life can be absorbed. The size of the cavity is controlled by adjusting the transmission part of the structure so as to absorb noise of different frequencies, and the frequency modulation function of the sound absorption wall is achieved. The sound absorption wall has the advantages of being simple in frequency modulation method and easy to implement, and has good application prospects in the building industry.

Description

Technical Field

[0001] The invention relates to the field of architectural acoustics and noise control, and in response to the constantly changing external environment, changes its own sound absorption structure in real time to achieve broadband sound absorption, and is specifically a frequency-adjustable sound absorption wall based on a Helmholtz resonator. Background Art

[0002] In real life, there are many places where noise reduction is needed, but the uncertainty of external noise brings many difficulties to noise control. Traditional sound absorption and noise reduction mainly reduces the noise level by arranging sound-absorbing materials on the noise source or propagation path to reduce the reflection and refraction of sound. Traditional sound-absorbing structures are mostly made of porous fiber materials or simple micro-perforated plates, which show good sound absorption performance in the medium and high frequency bands. However, due to the long wavelength, strong penetration and slow attenuation of low-frequency noise, traditional sound-absorbing materials have poor absorption performance. Therefore, sound absorption in the low-frequency band requires a structure thickness equivalent to the wavelength, so it has to face the problem of heavy volume and high cost.

[0003] For the suppression of low-frequency noise, resonant sound-absorbing structures are usually used, such as Helmholtz resonators, micro-perforated plates, and thin-film sound absorbers. However, these sound absorbers have the disadvantage of a narrow sound absorption frequency band, and the sound absorption frequency strongly depends on the size of the sound absorption structure. In practical applications, after the sound-absorbing material or structure design is installed, its size remains unchanged, so the noise reduction frequency range is fixed. If you want to change the sound absorption frequency, you must redesign and assemble the structure. However, the environmental noise is complex and changeable, and this fixed structure is obviously unable to adapt, and the noise reduction effect on noise outside the design frequency range is very weak. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that the existing sound absorber cannot change its own structure, and disclose a frequency-adjustable sound-absorbing wall based on a Helmholtz resonator. The designed frequency-adjustable sound-absorbing wall can change the resonant sound absorption frequency of the structure itself according to the frequency of the external environmental noise, thereby realizing the frequency-adjustable function of the structure.

[0005] In order to achieve the above technical purpose, the technical solution adopted by the utility model is:

[0006] A frequency-adjustable sound-absorbing wall based on a Helmholtz resonator, comprising: a Helmholtz resonator, a gear rack transmission mechanism;

[0007] The Helmholtz resonator comprises: a rectangular cavity and a piston plate; a circular hole neck is provided on the front end surface of the rectangular cavity to form a cylindrical channel, and a square through hole is provided on the rear end surface of the rectangular cavity; the piston plate is vertically placed in the rectangular cavity and is in contact with the upper, lower, left and right inner wall surfaces of the rectangular cavity without gaps, thereby ensuring that there is no gap inside the adjustable Helmholtz resonator;

[0008] The gear rack transmission mechanism comprises: a rack, a gear, a rotating shaft and a motor; wherein a gear shaft hole is opened on the gear; the gear and the rack are meshed together, one end of the rack is suspended in the air, and the other end passes through a square through hole and is fixedly connected to the geometric center of the piston plate; one end of the rotating shaft is fixedly connected to the motor, and the other end passes through a row of gear shaft holes continuously, and a row of gears is uniformly controlled by only one motor; the motor is fixedly installed on the base of the sound-absorbing wall, and both ends of the rotating shaft are supported by bearings;

[0009] The forward and reverse rotation of the motor drives the shaft to rotate, which in turn drives a row of gears to rotate forward and reverse. The forward and reverse rotation of the gears drives the rack to move back and forth, which in turn drives the piston plate to move linearly.

[0010] Multiple Helmholtz resonators are connected in series in a row to form a row-shaped sound-absorbing structure; multiple row-shaped Helmholtz resonators are connected in parallel to form a complete frequency-adjustable sound-absorbing wall.

[0011] As a further improved technical solution of the present invention, the cross-sectional area of ​​the piston plate is the same as the internal cross-sectional area of ​​the rectangular cavity; the diameter of the rotating shaft is equal to the diameter of the gear shaft hole; the gear and rack have equal widths and equal numbers of teeth, and the teeth on the gear and rack are all straight teeth, and the gear and rack are externally meshed.

[0012] As a further improved technical solution of the present invention, the frequency-adjustable sound-absorbing wall based on the Helmholtz resonator is made of rigid materials, including metal, ceramic, and concrete.

[0013] The beneficial effects of the utility model are:

[0014] The utility model proposes a frequency-adjustable sound-absorbing wall based on a Helmholtz resonator, which is composed of a Helmholtz resonator and a gear rack transmission mechanism; the basic unit of the sound-absorbing wall is an adjustable Helmholtz resonator, and each unit is controlled in batches through a transmission device, so as to increase the sound absorption effect by connecting multiple sound absorbers in parallel; the resonance cavity of each unit is surrounded by a piston plate and the inner wall of a rectangular cavity; sound waves are incident from the circular hole neck at the front end, and when the incident frequency of the sound waves is the same as the natural frequency of the system, the sound waves and the resonance cavity will resonate, and the air in the cavity is equivalent to an "air cavity". In the gas spring, the air will vibrate violently at the circular hole neck, and the sound energy will be consumed in the vibration process due to overcoming the friction resistance; the adjustable sound absorption structure can change its own structure according to the frequency of the external sound; when the noise frequency is high, the wavelength is short, and the volume of the corresponding resonance cavity can be reduced by the meshing of the gear rack behind the piston plate; on the contrary, when the noise is in the low frequency band, the wavelength is long, and the volume of the resonance cavity can be increased by the rotation of the motor, effectively avoiding the problems of heavy volume and high cost; in addition, the frequency modulation is carried out by the gear rack mechanism, which has the advantages of flexible frequency modulation and high precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The utility model is a schematic diagram of a frequency-adjustable sound-absorbing wall (back sound surface) based on a Helmholtz resonator.

[0016] Figure 2 The utility model is a schematic diagram of a frequency-adjustable sound-absorbing wall (sound-receiving surface) based on a Helmholtz resonator.

[0017] Figure 3 It is a cross-sectional view of a Helmholtz resonator 1 in a frequency-adjustable sound-absorbing wall based on a Helmholtz resonator according to the utility model.

[0018] Figure 4 It is a partial enlarged view of a gear rack transmission mechanism 2 in a frequency-adjustable sound-absorbing wall based on a Helmholtz resonator of the utility model.

[0019] Figure 5 (a) is a cross-sectional view of the utility model of a frequency-adjustable sound-absorbing wall based on a Helmholtz resonator when the volume of the resonance cavity is the smallest during the frequency modulation process.

[0020] Figure 5 Middle (b) is a cross-sectional view of the utility model when the volume of the resonance cavity is half of the maximum volume during the frequency modulation process of the adjustable frequency sound-absorbing wall based on the Helmholtz resonator.

[0021] Figure 5 Middle (c) is a cross-sectional view of the utility model when the volume of the resonance cavity is at its maximum during the frequency modulation process of a frequency-adjustable sound-absorbing wall based on a Helmholtz resonator.

[0022] Reference numerals:

[0023] 1-Helmholtz resonator; 11-rectangular cavity; 111-circular hole neck; 112-square through hole; 12-piston plate; 2-gear rack transmission mechanism; 21-rack; 22-gear; 221-gear shaft hole; 23-rotating shaft; 24-motor. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the utility model clearer, the technical solution of the utility model will be clearly and completely described below in conjunction with the drawings in the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] Example 1: Figure 1 and Figure 2As shown, as a specific embodiment of the utility model, a frequency-adjustable sound-absorbing wall based on a Helmholtz resonator is disclosed, which can be used in the fields of architectural acoustics and noise control. The frequency-adjustable sound-absorbing wall based on a Helmholtz resonator includes a Helmholtz resonator 1 and a gear rack transmission mechanism 2.

[0026] like Figure 3 As shown, the Helmholtz resonator 1 includes: a rectangular cavity 11 and a piston plate 12; a circular hole neck 111 is opened on the front end surface of the rectangular cavity 11 to form a cylindrical channel, and a square through hole 112 is opened on the rear end surface of the rectangular cavity 11; the piston plate 12 is vertically placed in the rectangular cavity 11, and is in gapless contact with the upper, lower, left and right inner wall surfaces of the rectangular cavity 11, thereby ensuring that there is no gap inside the adjustable Helmholtz resonator.

[0027] like Figure 4 As shown, the gear rack transmission structure 2 includes: a rack 21, a gear 22, a rotating shaft 23 and a motor 24, wherein a gear shaft hole 221 is opened on the gear 22; the gear 22 and the rack 21 are meshed together, one end of the rack 21 is suspended, and the other end passes through the square through hole 112 and is fixedly connected to the geometric center of the piston plate 12; one end of the rotating shaft 23 is fixedly connected to the motor 24, and the other end continuously passes through a row of gear shaft holes 221, and a row of gears 22 is uniformly controlled by only one motor 24; the motor 24 is fixedly installed on the base of the sound-absorbing wall, and the rotating shaft 23 is supported by a bearing.

[0028] The motor 24 drives the shaft 23 to rotate by forward and reverse rotation, and then drives a row of gears 22 to rotate forward and reverse together. The forward and reverse rotation of the gears 22 drives the rack 21 to move back and forth, and then drives the piston plate 12 to move linearly. As the position of the piston plate 12 in the rectangular cavity 11 changes, the purpose of changing the volume of the resonance cavity is achieved, thereby absorbing noises of different main frequencies accordingly.

[0029] A plurality of Helmholtz resonators 1 are connected in series in a row to form a row-shaped sound absorption structure; a plurality of row-shaped Helmholtz resonators are connected in parallel to form a complete frequency-adjustable sound absorption wall.

[0030] The cross-sectional area of ​​the piston plate 12 is the same as the internal cross-sectional area of ​​the rectangular cavity 11; the diameter of the rotating shaft 23 is equal to the diameter of the gear shaft control 221; the gear 22 and the rack 21 have equal widths and the same number of teeth, and the teeth on the gear 22 and the rack 21 are all straight teeth, and the gear 22 and the rack 21 are externally meshed.

[0031] Figure 5The frequency modulation process of the sound absorption wall is shown, taking the cross-section of a Helmholtz resonator 1 as an example. The motor 24 drives the gear 22 to rotate, the gear 22 drives the rack 21 to move, and then drives the piston plate 12 to make a linear motion; as the position of the piston plate 12 in the rectangular cavity 11 changes, the volume of the resonance cavity is changed, thereby correspondingly absorbing noises of different main frequencies. Figure 5 (a) is a schematic diagram showing that the distance between the piston plate 12 and the circular hole neck 111 is the minimum, and the volume of the corresponding resonance cavity is also the smallest; Figure 5 Middle (b) is a schematic diagram showing that the distance between the piston plate 12 and the circular hole neck 111 is half the value, and the volume of the corresponding resonance cavity is half the maximum volume; Figure 5 (c) is a schematic diagram showing that the distance between the piston plate 12 and the circular hole neck 111 is at the maximum value, and the volume of the corresponding resonance cavity is also the largest. Figure 5 It can be seen that as long as the driving motor rotates forward and reverse, the size of the resonance cavity of the Helmholtz resonator 1 can be adjusted arbitrarily, thereby changing the sound absorption frequency of the sound absorption wall, and the frequency modulation is flexible and simple.

[0032] The gear 22 and the rotating shaft 23 are axially positioned by keyway positioning to prevent the gear 22 from axial displacement.

[0033] Each Helmholtz resonator 1 is arranged vertically and horizontally and fixedly bonded to form a sound absorbing wall.

[0034] The sound-absorbing wall needs to have a certain strength and avoid sound-solid coupling. Its constituent materials should be rigid materials, which can be metal, ceramic, or concrete. The corresponding preparation methods are mechanical processing, sintering, and casting.

[0035] Finally, it should be noted that the above content is only used to illustrate the technical solution of the utility model, rather than to limit the protection scope of the utility model. Simple modifications or equivalent substitutions of the technical solution of the utility model by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the utility model.

Claims

1. A frequency-adjustable sound-absorbing wall based on a Helmholtz resonator, characterized in that: include: Helmholtz resonator (1), rack and pinion transmission mechanism (2); The Helmholtz resonator (1) comprises: a rectangular cavity (11) and a piston plate (12); a circular hole neck (111) is provided on the front end surface of the rectangular cavity (11) to form a cylindrical channel, and a square through hole (112) is provided on the rear end surface of the rectangular cavity (11); the piston plate (12) is vertically placed in the rectangular cavity (11) and is in contact with the upper, lower, left and right inner wall surfaces of the rectangular cavity (11) without any gap; The rack and pinion transmission mechanism (2) comprises: a rack (21), a gear (22), a rotating shaft (23) and a motor (24); wherein a gear shaft hole (221) is provided on the gear (22); the gear (22) and the rack (21) are meshed together, one end of the rack (21) is suspended in the air, and the other end passes through a square through hole (112) and is fixedly connected to the geometric center of the piston plate (12); one end of the rotating shaft (23) is fixedly connected to the motor (24), and the other end passes through a row of gear shaft holes (221) in succession, and a row of gears (22) are uniformly controlled by one motor (24); The motor (24) rotates forward and reversely to drive the rotating shaft (23) to rotate, thereby driving a row of gears (22) to rotate forward and reversely. The forward and reverse rotation of the gears (22) drives the rack (21) to move back and forth, thereby driving the piston plate (12) to move linearly; A plurality of Helmholtz resonators (1) are connected in series in a row to form a row-shaped sound absorption structure, and a plurality of row-shaped Helmholtz resonators are connected in parallel to form a complete frequency-adjustable sound absorption wall.

2. The frequency-adjustable sound-absorbing wall based on the Helmholtz resonator according to claim 1 is characterized in that: The cross-sectional area of ​​the piston plate (12) is the same as the internal cross-sectional area of ​​the rectangular cavity (11); the diameter of the rotating shaft (23) is equal to the diameter of the gear shaft hole (221); the gear (22) and the rack (21) have the same width and the same number of teeth, and the teeth on the gear (22) and the rack (21) are both straight teeth, and the gear (22) and the rack (21) are externally meshed.

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