CN116085572A - Electroacoustic coupling-based pipeline low-frequency noise control device - Google Patents
Electroacoustic coupling-based pipeline low-frequency noise control device Download PDFInfo
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- CN116085572A CN116085572A CN202310148575.7A CN202310148575A CN116085572A CN 116085572 A CN116085572 A CN 116085572A CN 202310148575 A CN202310148575 A CN 202310148575A CN 116085572 A CN116085572 A CN 116085572A
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- 230000008878 coupling Effects 0.000 title claims abstract description 25
- 238000010168 coupling process Methods 0.000 title claims abstract description 25
- 238000005859 coupling reaction Methods 0.000 title claims abstract description 25
- 238000011144 upstream manufacturing Methods 0.000 claims abstract description 38
- 230000030279 gene silencing Effects 0.000 claims abstract description 15
- 230000001066 destructive effect Effects 0.000 claims description 3
- 230000007547 defect Effects 0.000 abstract description 2
- 230000000694 effects Effects 0.000 description 10
- 238000013016 damping Methods 0.000 description 6
- 230000005540 biological transmission Effects 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 230000001743 silencing effect Effects 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000001902 propagating effect Effects 0.000 description 2
- 230000003584 silencer Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L55/00—Devices or appurtenances for use in, or in connection with, pipes or pipe systems
- F16L55/02—Energy absorbers; Noise absorbers
- F16L55/033—Noise absorbers
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/172—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using resonance effects
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Multimedia (AREA)
- Mechanical Engineering (AREA)
- Soundproofing, Sound Blocking, And Sound Damping (AREA)
Abstract
The invention aims to provide a pipeline low-frequency noise control device based on electroacoustic coupling, which comprises an upstream loudspeaker, a downstream loudspeaker and a coupling circuit, wherein a main pipe section for noise control comprises an upstream air inlet pipe section, a middle silencing pipe section and a downstream outlet pipe section, the silencing pipe section is respectively provided with the upstream loudspeaker and the downstream loudspeaker, the upstream loudspeaker and the downstream loudspeaker are connected through the coupling circuit, the pipe wall of the silencing pipe section is provided with a sliding rail, the downstream loudspeaker is arranged on a movable side plate, and the side plate can do transverse translational motion along the sliding rail on the pipe wall. The invention can overcome the defect of single silencing frequency band of the traditional H-Q tube fixing structure. And by utilizing electroacoustic coupling characteristics, the sound path difference between the main pipeline and the bypass pipeline is created, the flexibility of the muffler device is improved, and the structural size is reduced.
Description
The application is a divisional application with the name of electroacoustic coupling-based pipeline low-frequency noise control device, wherein the application number of the main application is 202110046347.X, and the application date is 2021.01.14.
Technical Field
The invention relates to a noise control device, in particular to a pipeline noise control device.
Background
The pipeline noise control method is mainly divided into active control and passive control. The active control method mainly utilizes the principle of mutual superposition of sound waves to control noise, the structure of the system is complex, a certain time is needed to achieve the stability of the system, and the applicable working scene is limited. Passive control methods have been developed for many years and are widely used to effectively eliminate mid-to-high frequency noise. According to the noise control principle, if the passive control device is applied to low-frequency noise control, the noise cancellation band is narrow, and the size of the device is limited by the wavelength of the sound wave, and is generally large.
The Herschel-Quincke (H-Q) pipe is a relatively typical low frequency, passive control muffler device that uses the sound path difference of sound propagating between the main pipe and the bypass pipe to make the sound waves of the sound at the junction of the main and bypass pipes have a phase difference so as to achieve the muffling effect. The disclosed patent CN101956884a describes a semi-active device with an adjustable H-Q bypass line, which widens the effective sound absorption bandwidth of the conventional H-Q device, and makes the muffler device have better sound absorption effect at medium and low frequencies, but the device complicates the conventional H-Q line, and adds a controller and other devices, so that the volume of the muffler device becomes large, and the tightness of the complicated bypass line with variable length is also a difficult problem in engineering. If the H-Q pipe is used for low frequency noise control, the low frequency performance is limited by the length of the bypass pipe, i.e. the length of the bypass pipe must be long to eliminate the low frequency noise.
Disclosure of Invention
The invention aims to provide a pipeline low-frequency noise control device based on electroacoustic coupling, which has a sound attenuation effect in a specific frequency band.
The purpose of the invention is realized in the following way:
the invention provides a pipeline low-frequency noise control device based on electroacoustic coupling, which comprises an upstream loudspeaker, a downstream loudspeaker and a coupling circuit, wherein a main pipe section for noise control comprises an upstream air inlet pipe section, a middle silencing pipe section and a downstream outlet pipe section, the silencing pipe section is respectively provided with the upstream loudspeaker and the downstream loudspeaker, the upstream loudspeaker and the downstream loudspeaker are connected through the coupling circuit, the pipe wall of the silencing pipe section is provided with a sliding rail, the downstream loudspeaker is arranged on a movable side plate, and the side plate can transversely move in a translational manner along the sliding rail on the pipe wall.
Preferably, the sliding side plate moves along the sliding rail to adjust the distance between the upstream speaker and the downstream speaker so that the distance between the upstream speaker and the downstream speaker matches the resonance frequency, and the distance between the upstream speaker and the downstream speaker is equal to (2N-1)/2 times the wavelength corresponding to the resonance frequency, wherein N is a positive integer.
Preferably, the spacing between the upstream speaker and the downstream speaker is equal to a half wavelength corresponding to the resonance frequency.
Preferably, the noise is divided into two paths after entering the main pipe section, the first path is directly transmitted to the downstream loudspeaker through the upstream air inlet pipe section and the middle silencing pipe section, the second path reaches the surface of the upstream loudspeaker to cause vibration of the vibrating diaphragm to generate induced electromotive force, the downstream loudspeaker sounds due to the induced current, and the two paths of sound waves are converged at the downstream loudspeaker to generate destructive interference.
Preferably, a sealed back chamber is arranged outside both the upstream speaker and the downstream speaker.
Preferably, the upstream speaker and the downstream speaker are both moving coil speakers.
The invention has the advantages that: the invention can overcome the defect of single silencing frequency band of the traditional H-Q tube fixing structure. And by utilizing electroacoustic coupling characteristics, the sound path difference between the main pipeline and the bypass pipeline is created, the flexibility of the muffler device is improved, and the structural size is reduced.
Drawings
FIG. 1 is a schematic diagram of two paths of sound waves at a downstream speaker in a superimposed manner;
FIG. 2 is a schematic diagram of the structure of the present invention;
fig. 3 shows the transmission loss of the device when the distance between the two loudspeakers is 1 m.
Detailed Description
The invention is described in more detail below, by way of example, with reference to the accompanying drawings:
referring to fig. 1-3, the electroacoustic coupling-based pipeline low-frequency noise control device comprises a main pipeline section, an upstream loudspeaker 3, a back cavity 2, a coupling circuit 4, a downstream loudspeaker 5, a back cavity 6, a side plate 7 and a limiting block 9, wherein the main pipeline section comprises an upstream air inlet pipeline section 1, a middle silencing pipeline section and a downstream outlet pipeline section 8.
After the incident sound wave enters the muffling pipe section from the air inlet pipe section 1 of the main pipe section, the incident sound wave is transmitted out from the outlet pipe section 8, and the amplitude of the incident sound wave is reduced. Wherein an upstream speaker 3 is arranged at the side of the main pipeline near the air inlet pipe section 1, a closed back cavity 2 is arranged at the back of the upstream speaker 3, and the upstream speaker 3 is connected with a downstream speaker 5 through a coupling circuit 4. The pipe wall of the silencing pipe section is provided with a sliding rail, the downstream loudspeaker 5 is arranged on a movable side plate 7, the side plate can move horizontally and horizontally along the sliding rail of the pipe wall, and a closed back cavity 6 is arranged on the back of the downstream loudspeaker 5. The limiting block 9 is arranged on the pipe wall of the outlet pipe section 8 and is used for limiting one end, close to the outlet pipe section 8, of the side plate 7. The upstream speaker 3 and the downstream speaker 5 are both moving coil speakers. The upstream loudspeaker and the downstream loudspeaker are replaceable, and the loudspeaker which is optimally matched with the upstream loudspeaker and the downstream loudspeaker can be selected according to different noise source characteristics, namely the peak frequency of the noise source corresponds to the resonance frequency of the selected loudspeaker. The silencer belongs to passive silencer, and the system has no external energy input. Two or more moving coil speakers are placed in sequence along the transmission direction of noise in the duct. The loudspeaker groups are connected through a coupling circuit. The position parameters and the coupling circuit parameters of the loudspeaker group are adjustable, so that the coverage of noise in different frequency bands is realized.
The two loudspeakers are connected through a coupling circuit, the two loudspeakers form an equivalent bypass pipe section connected with the main pipe section in parallel, and the air inlet pipe section 1 and the outlet pipe section 8 are respectively positioned at two ends of the main pipe section. Noise enters the main pipe section and then is divided into two paths, one path reaches the surface of the upstream loudspeaker 3 to cause vibration of the vibrating diaphragm to generate induced electromotive force, induced current is further formed in two coupled loudspeaker loops, the downstream loudspeaker 5 sounds due to the induced current, and the other path is directly transmitted to the downstream loudspeaker 5 through the main pipe section. The two acoustic waves finally converge at the downstream speaker 5, and destructive interference occurs due to the different transmission phases of the two acoustic waves, so that noise propagating downstream after the convergence is reduced (as shown in fig. 1). At the same time, the downstream speaker 5 is mounted on a side plate 7 which is slidable along the slide rail. The position of the downstream loudspeaker 5 is thus adjustable, which provides another measure of adjusting the sound path difference between the main pipe section and the equivalent bypass pipe section.
The speaker group is externally arranged with a sealed back cavity to prevent leakage of the speaker to the external environment.
From acoustic knowledge, when two rows of sound waves with the same wavelength and the same amplitude meet, the sound waves are overlapped, if the phase difference of the two rows of sound waves is 180 degrees or expressed as an odd multiple of half wavelength, the wave crests and wave troughs of the two rows of sound waves meet exactly and cancel each other, and a noise elimination effect is generated, which is also a mechanism followed by active noise control. In the present invention, the wave crest or wave trough of the sound wave which is transmitted from the intake pipe section 1 and runs to the upstream speaker 3 excites the vibration of the speaker diaphragm, and induced electromotive force is generated inside the speaker, so that the downstream speaker 5 connected thereto sounds. Because of the rapid circuit transfer, the speaker system corresponds to immediately transferring sound waves at the upstream speaker 3 to the downstream, with little time delay. Thus, based on the superposition principle of sound waves, when the distance L between two speakers is exactly equal to (2N-1)/2 times the wavelength (n=1, 2,3 …), the sound-deadening effect is just achieved. According to the theory of sound wave superposition, when the distance L between two loudspeakers is equal to (4N-3,4N-1)/4 times of wavelength, the two loudspeakers have certain silencing effect, and when the distance is exactly equal to (2N-1)/2 times of wavelength, the silencing effect is the best. The design of the invention can enable the distance L between the two speakers to change along with the position movement of the side plate (as shown in figure 2), namely, the position of the downstream speaker 5 can be enabled to move to the corresponding position along with the side plate, so that the optimal silencing effect of the corresponding frequency band is obtained.
The noise reduction effect calculation method of the present invention is as follows.
The mechanical impedance of a moving coil speaker can be expressed as: z is Z m ＝δ+jωM+K/jω+A 2 /jωC a
Wherein C is a ＝V/ρ 0 c 0 2 An equivalent acoustic reactance added for a back sealing chamber of a loudspeaker, V is the volume of the back chamber, A is the effective vibration area of the surface of a loudspeaker diaphragm, omega is the angular frequency,
is an imaginary number ρ 0 、c 0 Is the density of the air and the speed of sound in the air. K is the equivalent stiffness of the mechanical part of the loudspeaker, M is the equivalent mass of the mechanical part of the loudspeaker, and delta is the equivalent damping of the mechanical part of the loudspeaker.
The resonant frequency of the loudspeaker can thus be expressed as:
when two loudspeakers are connected to form a closed loop, the electrical impedance in the loop will produce an equivalent mechanical impedance Δz= (Bl) 2 /2(R e +jωL e )。
Where Re is the direct current resistance of the speaker, le is the coil inductance, bl is the product of the magnetic induction of the magnetic field gap and the effective line length of the coil in the magnetic field (unit: T x m).
The equivalent impedance thus created acts on the equivalent damping and equivalent mass of the loudspeaker system, so that the shift in the resonant frequency of the loudspeaker becomes:
the adopted moving coil loudspeaker has the following mechanical impedance characteristics measured by Thiele/Small parameters: damping δ=1.67 Ns/M, mass m=6.5 g, stiffness k=1000N/M. Therefore, according to the theoretical formula, the resonance frequency of a single loudspeaker in the connected system is f L =170 Hz. At the resonance frequency, the sound wave transmitted to the surface of the loudspeaker diaphragm more easily excites vibration of the diaphragm, thereby completing transmission of acoustic energy, and thus the sound damping effect at the resonance frequency range is also the best.
According to the characteristic of the loudspeaker, the downstream side plate is slid to adjust the distance between the two loudspeakers, so that the distance between the two loudspeakers is matched with the resonance frequency, namely, the distance is equal to half wavelength corresponding to the resonance frequency. The present invention will be described in detail with reference to this position.
By adapting the inherent characteristics of the loudspeaker of the present invention, the downstream side plate on which the downstream loudspeaker 5 is mounted is displaced by l=c 0 /(2f L ) The position is such that the sound-damping device obtains an optimal sound-damping effect at the frequency.
According to the control principle, the noise control condition of the pipeline can be obtained:
the effective muffling effect was evaluated with a muffling amount of more than 5 dB, and the effective muffling frequency band shown in fig. 3 from the calculation result substantially matches the theoretical predicted muffling frequency band.
Through the analysis, the muffler device has good sound absorption effect in a low frequency band.
Claims (6)
1. A pipeline low-frequency noise control device based on electroacoustic coupling is characterized in that: the main pipe section of noise control comprises an upstream air inlet pipe section, a middle silencing pipe section and a downstream outlet pipe section, wherein the upstream loudspeaker and the downstream loudspeaker are respectively arranged on the silencing pipe section, the upstream loudspeaker and the downstream loudspeaker are connected through the coupling circuit, a sliding rail is arranged on the pipe wall of the silencing pipe section, the downstream loudspeaker is arranged on a movable side plate, and the side plate can do transverse translational motion along the sliding rail on the pipe wall.
2. The electroacoustic coupling based pipeline low frequency noise control device of claim 1, wherein: the sliding side plate moves along the sliding rail to adjust the distance between the upstream loudspeaker and the downstream loudspeaker, so that the distance between the upstream loudspeaker and the downstream loudspeaker is matched with the resonance frequency, and the distance between the upstream loudspeaker and the downstream loudspeaker is equal to (2N-1)/2 times of the wavelength corresponding to the resonance frequency, wherein N is a positive integer.
3. The electroacoustic coupling based pipeline low frequency noise control device of claim 2, wherein: the spacing between the upstream and downstream speakers is equal to a half wavelength corresponding to the resonant frequency.
4. The electroacoustic coupling based pipeline low frequency noise control device of claim 2, wherein: noise is divided into two paths after entering the main pipe section, the first path is directly transmitted to a downstream loudspeaker through an upstream air inlet pipe section and a middle silencing pipe section, the second path reaches the surface of the upstream loudspeaker to cause vibration of a vibrating diaphragm, induced electromotive force is generated, the downstream loudspeaker sounds due to the induced current, and two paths of sound waves are converged at the downstream loudspeaker to generate destructive interference.
5. The electroacoustic coupling based pipeline low frequency noise control device according to any one of claims 1 to 4, wherein: a sealed back chamber is disposed outside both the upstream speaker and the downstream speaker.
6. The electroacoustic coupling based pipeline low frequency noise control device according to any one of claims 1 to 4, wherein: the upstream speaker and the downstream speaker are both moving coil speakers.
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| CN202310148575.7A CN116085572A (en) | 2021-01-14 | 2021-01-14 | Electroacoustic coupling-based pipeline low-frequency noise control device |
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| CN202110046347.XA CN112901887A (en) | 2021-01-14 | 2021-01-14 | Pipeline low-frequency noise control device based on electroacoustic coupling |
| CN202310148575.7A CN116085572A (en) | 2021-01-14 | 2021-01-14 | Electroacoustic coupling-based pipeline low-frequency noise control device |
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| CN116085572A (en) * | 2021-01-14 | 2023-05-09 | 哈尔滨工程大学 | Electroacoustic coupling-based pipeline low-frequency noise control device |
| US11812219B2 (en) * | 2021-07-23 | 2023-11-07 | Toyota Motor Engineering & Manufacturing North America, Inc. | Asymmetry sound absorbing system via shunted speakers |
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2021
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| US2043416A (en) * | 1933-01-27 | 1936-06-09 | Lueg Paul | Process of silencing sound oscillations |
| GB1357330A (en) * | 1970-07-01 | 1974-06-19 | Secr Defence | Dynamic silencing systems |
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