Active array composite muffler

Abstract

The present invention discloses an active array composite muffler, comprising an array muffler and an active muffler system. The array muffler comprises a plurality of muffler columns arranged in an array. The active muffler system comprises a controller, a reference sensor adjacent to the array muffler inlet, a secondary speaker embedded within the muffler columns, and an error sensor adjacent to the array muffler outlet. The array muffler and the active muffler system are integrated together in a segmented or non-segmented composite manner. By combining active muffler technology with a traditional array muffler, the present invention overcomes the limitations of traditional passive mufflers in their poor low-frequency noise control, effectively improving the muffler's low-frequency noise reduction and achieving broadband muffler performance.

Description

Technical Field

[0001] The invention belongs to the field of noise pollution prevention and control, and particularly relates to an active array type composite muffler. Background Art

[0002] In recent years, the number of complaints about noise nuisance has remained high, ranking second among all environmental pollution factors. Based on the noise generation mechanism, it can be divided into three categories: airflow noise, mechanical noise, and electromagnetic noise. The passive control measure for airflow noise is to install a silencer.

[0003] Silencer can be divided into resistive silencer, reactive silencer and impedance composite silencer, among which resistive silencer is suitable for medium and high frequency silencer; reactive silencer is suitable for medium and low frequency silencer, but its airflow resistance and volume are both large; impedance composite silencer is suitable for broadband silencer, but also has the problem of large airflow resistance. Array silencer is a new type of silencer with great potential in recent years. For example, the patent specification with announcement number CN207690491U discloses a new type of array silencer, which includes a silencer shell and a plurality of silencer columns. A plurality of support rods are installed in parallel at the openings at both ends of the silencer shell. The plurality of silencer columns are arranged in an array inside the silencer shell. The two ends of the silencer columns are fixed on the support rods. The silencer column includes a silencer column shell, a sound absorbing layer and a waterproof layer. The two ends of the silencer column shell are blocked by a guide cap, and the guide cap is connected to the support rod. The sound absorbing layer is filled inside the silencer column shell, and the waterproof layer is wrapped around the outside of the sound absorbing layer. Compared with the plate-type silencer, the array-type silencer has a larger effective ventilation area, is suitable for large air volume ventilation systems, and has better noise reduction performance in the medium and high frequency bands.

[0004] Active noise cancellation technology achieves low-frequency noise cancellation by generating a series of secondary sounds with the same amplitude but opposite phase as the primary noise (the noise to be eliminated) and utilizing the destructive interference of sound waves. For example, the patent specification with the announcement number CN104749903B discloses an active noise cancellation device, comprising: a first loudspeaker for generating secondary noise that interferes with the primary noise; an error sensor for detecting the remaining noise after the interference as a residual noise signal; a control unit for collecting the residual noise signal and correspondingly controlling the first loudspeaker to emit secondary noise; a standard sensor for detecting the primary noise; and a second loudspeaker, wherein the first compensating noise emitted by the second loudspeaker is used to eliminate the interference of the secondary noise on the standard sensor. Therefore, combining active noise cancellation technology with an array silencer can effectively improve the low-frequency noise cancellation of the silencer and achieve broadband noise cancellation.

[0005] At present, active silencer technology is widely used in the silencer of a single airflow channel, and has also begun to be used in the field of multiple airflow channels that are not connected to each other (i.e., independent of each other). However, there have been no reports of its application in multiple airflow channels that are connected to each other (such as the airflow channels of array silencers). Summary of the Invention

[0006] The object of the present invention is to provide an active array type composite muffler to achieve broadband muffler of airflow noise.

[0007] An active array composite muffler comprises an array muffler and an active muffler system. The array muffler includes a plurality of muffler columns arranged in an array. The active muffler system includes a controller, a reference sensor located near the inlet of the array muffler, a secondary speaker embedded within the muffler columns, and an error sensor located near the outlet of the array muffler. The array muffler and active muffler system are integrated in a segmented or non-segmented composite manner. The controller preferably employs a multi-channel active adaptive controller.

[0008] This solution combines active silencer technology with traditional array silencers, breaking through the limitations of traditional passive silencers in controlling low-frequency noise, effectively improving the low-frequency noise reduction of the silencer and achieving broadband noise reduction.

[0009] Preferably, when the array muffler and the active muffler system are integrated in a segmented composite manner, the secondary speaker is embedded in the end of the muffler column, and the bell mouth of the secondary speaker faces the outlet end of the muffler.

[0010] Preferably, a guide head is installed at the end of the silencer column of the array silencer, and the secondary speaker is embedded in the guide head.

[0011] Preferably, when the array silencer and the active silencer system are integrated in a non-segmented composite manner, the secondary speaker is embedded in the side of the middle or rear section of the silencer column, and the horn of the secondary speaker is flush with the side of the silencer column.

[0012] Preferably, the array-distributed silencer columns are divided into a number of basic silencer units, and each of the basic silencer units is equipped with an independent active silencer system.

[0013] Because the complexity of the adaptive control algorithm in an active noise cancellation system increases exponentially with the number of channels, and the algorithm's stability and robustness decrease, the number of channels in the active noise cancellation system should be minimized, as far as possible. To this end, the m×n noise cancellation columns of the array noise cancellation system are divided into Int(m / a)×Int(n / b) basic noise cancellation units (Int represents an integer rounded to the number in parentheses). Each basic noise cancellation unit contains a×b noise cancellation columns, and each basic noise cancellation unit is equipped with an independent active noise cancellation system. This division of the basic noise cancellation units effectively reduces the number of channels in the active noise cancellation system and improves the stability and robustness of the adaptive control system.

[0014] Preferably, the number of secondary speakers installed in each basic sound-attenuating unit is less than the number of sound-attenuating columns in the basic sound-attenuating unit, and the number of secondary speakers is an even number, forming a secondary speaker array that directionally emits secondary sound within the range of the basic sound-attenuating unit. By adjusting parameters such as the number and spacing of the secondary speakers, the distribution range of the secondary sound energy generated by the secondary speaker array within the basic sound-attenuating unit can be controlled.

[0015] Preferably, the reference sensor in each basic silencer unit is arranged inside the basic silencer unit at 10 to 30 cm from the inlet of the silencer; and the error sensor in each basic silencer unit is arranged inside the basic silencer unit at 10 to 30 cm from the outlet of the silencer.

[0016] The above arrangement can reduce the influence of turbulent noise generated by drastic changes in air flow velocity and flow direction at the air flow inlet and outlet sections of the muffler, thereby improving the stability of the active muffler system.

[0017] The reference sensor picks up the sound produced by the secondary speaker while receiving the primary noise, forming secondary acoustic feedback. To reduce the secondary acoustic feedback, preferably, the secondary speaker of each basic sound-absorbing unit is arranged in a mirror-like manner with the longitudinal section located at the center of the basic sound-absorbing unit as a mirror image.

[0018] Secondary acoustic feedback is more severe when the secondary speaker is close to the reference sensor. When the primary noise is single-frequency, the active noise cancellation effect is best achieved when the distance between the secondary speaker and the error sensor is three and a half wavelengths or five and a half wavelengths of the active noise cancellation frequency. Therefore, the secondary speaker array should be placed away from the reference sensor, and the distance from the error sensor should be carefully considered, preferably within 1 meter of the error sensor. It should be noted that there is an optimal distance between the secondary speaker array and the error sensor, which is generally determined through debugging.

[0019] The working principle of the present invention is as follows: the array muffler is divided into several basic muffler units, and each basic muffler unit has an independent active muffler system. The reference sensor is located in the basic muffler unit at a certain distance from the muffler inlet section, and is used to collect primary noise, and transmit the primary noise to the multi-channel active adaptive controller to control the directional sound of the secondary speaker array. The error sensor is located in the basic muffler unit at a certain distance from the muffler outlet section, and is used to collect error signals, and feed the error signals back to the multi-channel active adaptive controller. The multi-channel active adaptive controller regulates the output of the secondary speaker array based on the received error signal. It should be noted that when the multi-channel active adaptive controller performs multi-channel adaptive calculations, it should consider the attenuation of the primary noise in the array muffler that does not incorporate active muffler technology.

[0020] Beneficial effects of the present invention:

[0021] Active silencer technology is combined with traditional array silencers to break through the limitation of traditional passive silencers in controlling low-frequency noise, effectively improve the low-frequency silencer's capacity, and achieve broadband silencer. The active array composite silencer is divided into several basic silencer units, and the air flow channels between each basic silencer unit are connected to each other. By adjusting the number and spacing of speakers, the distribution range of the secondary sound energy generated by the speaker array in the basic silencer unit can be directionally controlled, effectively controlling the influence of secondary sound between different silencer units. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a front view of the active array composite muffler of the present invention;

[0023] Figure 2 Schematic diagram of the structure of the active array composite muffler of Example 1;

[0024] Figure 3 for Figure 2 AA section view;

[0025] Figure 4 Schematic diagram of the structure of the active array composite muffler of Example 2;

[0026] Figure 5 for Figure 4 BB section view. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] Example 1

[0029] See also Figure 1 、 Figure 2 and Figure 3 This embodiment is a segmented composite active array composite muffler, which includes an array muffler and an active muffler system. The array muffler includes m×n muffler columns 1, which are divided into a number of basic muffler units 2. The active muffler system includes a controller 3, a reference sensor 4 adjacent to the inlet section of the array muffler, a secondary speaker 5 embedded in the end of the muffler column of the array muffler, and an error sensor 6 adjacent to the outlet section of the array muffler.

[0030] In this embodiment, the 7×7 silencer columns 1 in the array silencer are divided into 9 2×2 basic silencer units 2, and each basic silencer unit 2 is installed with an independent active silencer system. The remaining 13 silencer columns 1 are not installed with an active silencer system because they cannot form a 2×2 basic silencer unit. In each independent active silencer system, the reference sensor 4 is located inside the basic silencer unit at a distance of 10 cm from the silencer inlet section, and the error sensor 6 is located inside the basic silencer unit at a distance of 10 cm from the silencer outlet section. The secondary speaker 5 is embedded in the end of the silencer column 1 of the array silencer, and the horn of the secondary speaker 5 faces the outlet end of the array silencer. The controller 3 is fixed inside the silencer column 1, and the reference sensor 4 and the error sensor 6 are fixed inside the basic silencer unit 2.

[0031] Example 2

[0032] See also Figure 1 、 Figure 4 and Figure 5 This embodiment is a non-segmented active array composite muffler, which includes an array muffler and an active muffler system. The array muffler includes m×n muffler columns 1, which are divided into a number of basic muffler units 2. The active muffler system includes a controller 3, a reference sensor 4 adjacent to the inlet section of the array muffler, a secondary speaker 5 embedded in the side of the middle or rear section of the muffler column of the array muffler, and an error sensor 6 adjacent to the outlet section of the array muffler.

[0033] In this embodiment, the 7×7 silencer columns 1 in the array silencer are divided into 9 2×2 basic silencer units 2, and each basic silencer unit 2 is installed with an independent active silencer system. The remaining 13 silencer columns 1 are not installed with an active silencer system because they cannot form a 2×2 basic silencer unit. In each independent active silencer system, the reference sensor 4 is located inside the basic silencer unit at a distance of 10 cm from the silencer inlet section, and the error sensor 6 is located inside the basic silencer unit at a distance of 10 cm from the silencer outlet section. The secondary speaker 5 is embedded in the side of the middle or rear section of the silencer column 1 of the array silencer, and the secondary speakers 5 are arranged facing each other, with the secondary speakers 5 horns facing each other. The controller 3 is fixed inside the silencer column 1, and the reference sensor 4 and the error sensor 6 are fixed inside the basic silencer unit 2.

[0034] In the two aforementioned embodiments, the primary noise entering the muffler is detected by reference sensor 4 and transmitted to controller 3. The error signal at the muffler outlet is detected by error sensor 6 and fed back to controller 3. Based on the received primary noise and error signals, controller 3 performs multi-channel adaptive calculations to adjust the output of the secondary speaker array 5 in real time. The combination of an active muffler system and an array muffler effectively improves the muffler's low-frequency sound attenuation, achieving broadband sound attenuation.

[0035] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An active array composite muffler, characterized in that: The invention comprises an array muffler and an active muffler system, wherein the array muffler comprises a plurality of muffler columns distributed in an array, and the active muffler system comprises a controller, a reference sensor adjacent to the inlet of the array muffler, a secondary speaker embedded in the muffler column, and an error sensor adjacent to the outlet of the array muffler. The array muffler and the active muffler system are integrated together in a non-segmented composite manner. When the array muffler and the active muffler system are integrated in a non-segmented composite manner, the secondary speaker is embedded in the side of the middle section or rear section of the muffler column, and the horn of the secondary speaker is flush with the side of the muffler column; The array-distributed muffler columns are divided into a plurality of basic muffler units, each of which is equipped with an independent active muffler system. The number of secondary speakers installed in each basic muffler unit is less than the number of muffler columns in the basic muffler unit, and the number of secondary speakers is an even number, forming a secondary speaker array. The secondary loudspeaker of each basic sound-absorbing unit is arranged with the longitudinal section located at the center of the basic sound-absorbing unit as a mirror image.

2. The active array composite muffler according to claim 1, characterized in that: It also includes that when the array muffler and the active muffler system are integrated in a segmented composite manner, the secondary speaker is embedded in the end of the muffler column, and the horn of the secondary speaker faces the outlet end of the muffler.

3. The active array composite muffler according to claim 2, characterized in that: A flow guide head is installed at the end of the muffler column of the array muffler, and the secondary speaker is embedded in the flow guide head.

4. The active array composite muffler according to claim 1, characterized in that: The reference sensor in each basic muffler unit is arranged in the basic muffler unit at a distance of 10 to 30 cm from the inlet of the muffler; the error sensor in each basic muffler unit is arranged in the basic muffler unit at a distance of 10 to 30 cm from the outlet of the muffler.

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