Labyrinth resonator and pipeline noise elimination device based on same
Technical Field
The invention relates to a pipeline silencing device, in particular to a pipeline silencing device based on a labyrinth resonator.
Background
The pipeline silencer is widely used in the fields of automobiles, aerospace, ships and the like. Conventional resistive and reactive pipe mufflers suffer from a number of deficiencies. For example, resistive mufflers use sound absorbing materials to effectively control high frequency noise, but are difficult to control low frequency noise and are not suitable for high temperature and unclean environments. Reactive mufflers typically employ an expansion cavity structure and a bypass resonator structure, primarily for low and mid frequency noise control. The side branch resonator structure comprises a Helmholtz resonator and a quarter wave pipe, wherein the quarter wave pipe is a closed pipe arranged on the main pipeline, and when the length of the pipe is 1/4 times of the wavelength of incident sound waves, the pipe resonates, consumes sound energy and plays a role in sound wave filtering. For low frequency noise, such as 100Hz noise, the required wavelength tube length is about 0.8m, which usually occupies a relatively large space. The quarter-wave tubes currently in use mainly have the following problems: (1) the quarter-wave tube is generally perpendicular to the air inlet pipeline, and for low-frequency noise elimination, the pipeline is long and occupies a large space; (2) because of resonance noise elimination, the lower the resonance frequency, the narrower the noise elimination band.
Disclosure of Invention
In order to overcome the defects in the prior art, the quarter-wave tube which is originally perpendicular to the main silencing pipe is folded and coiled along the axial direction (sound wave incidence direction), the axial line of the quarter-wave tube forms a spiral plane curve, and the tube forms a labyrinth coplanar tube, so that the purposes of saving space and having a compact structure are achieved; meanwhile, the quarter-wave tubes with different tube lengths are connected in parallel or in series along the main pipeline, so that the silencing bandwidth can be increased, and multi-channel silencing is realized.
The invention is realized by the following technical scheme:
the labyrinth resonator comprises a front panel, a labyrinth layer and a rigid back plate, wherein the front panel, the labyrinth layer and the rigid back plate are sequentially and fixedly connected. A through hole is processed in the center of the front panel; the labyrinth layer comprises a frame and a plurality of clapboards with different lengths positioned in the frame, the clapboards are connected end to end and enclose into a spiral shape, and a labyrinth-shaped air channel is formed between the clapboards and the frame; the inlet of the labyrinth-shaped air channel is connected with the through hole of the front panel.
And a sealing plate is arranged on the labyrinth passage in the direction vertical to the passage side wall, and the sealing plate is fixedly connected with the passage side wall.
In order to solve the technical problem, the invention also provides a pipeline silencing device based on the labyrinth resonator.
The pipeline silencing device comprises a main pipeline with a square cross section and four labyrinth resonators with the same pipe length, wherein the four labyrinth resonators are symmetrically distributed on four side walls of the main pipeline.
The main pipeline the central position of four lateral walls of main pipeline on process and have the through-hole of square, the through-hole symmetric distribution of square.
The labyrinth resonator is arranged on the side wall of the main pipeline, and the inlet of the labyrinth resonator is connected with the through hole on the side wall of the main pipeline.
Preferably, the cross section of the air channel of the labyrinth resonator is square, and the area of the air channel is the same as that of the square through hole on the side wall of the main pipeline.
Preferably, the wall thickness of the labyrinth resonator is the same as that of the main pipeline.
The labyrinth resonator based pipeline silencer has air passage length capable of being changed via changing the position of the sealing plate.
The labyrinth resonator based pipeline noise elimination device is provided with labyrinth resonators with different air channel lengths along the axial direction of a main pipeline, and can eliminate noise in different frequency bands.
The invention has the beneficial effects that: the labyrinth resonator-based pipeline noise elimination device adopts a space folding method to fold a quarter-wave tube vertically arranged with a main pipeline into a coplanar labyrinth-shaped pipeline to form a labyrinth-shaped resonator, so that the space required by the structure can be greatly reduced, and the labyrinth-shaped resonator has high use value under the condition of rare space; the labyrinth resonators are symmetrically arranged along the periphery of the main pipeline, so that the silencing bandwidth under a certain frequency can be widened; the labyrinth resonators with different air channel lengths are arranged along the axial direction of the main pipeline, so that multi-band noise elimination can be realized, and the purpose of low-frequency broadband noise elimination is achieved.
Drawings
FIG. 1 is a schematic diagram of a basic quarter wave tube converted into a labyrinth resonator;
fig. 2 is an external view of a labyrinth resonator;
FIG. 3 is an exploded view of a labyrinth resonator;
FIG. 4 is an external view of the pipe muffler assembly;
FIG. 5 is a partial cross-sectional view of the pipe muffler assembly;
FIG. 6 is an exploded view of the pipe muffler assembly;
FIG. 7 is a dimensional view of a labyrinth resonator and a pipe silencer;
FIG. 8 is a diagram of the sound transmission loss of the muffling pipeline when the labyrinth resonators are arranged in parallel with the main pipeline;
FIG. 9 is a diagram of sound transmission loss of a muffling pipeline when a plurality of labyrinth resonators are arranged in series;
fig. 10 is a sound transmission loss diagram of a silencing pipeline when a plurality of labyrinth resonators are arranged in series and in parallel in an air inlet system of an automobile engine.
Wherein, 0 is the quarter wave pipe, 1 is the maze syntonizer, 2 is the main pipeline of eliminating the noise.
Detailed Description
In order that the objects, technical solutions and advantages of the present invention will be more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings.
As shown in fig. 1 and 2, in order to overcome the disadvantages that the conventional quarter wave pipe occupies a large space and is difficult to arrange in a power mechanical device with a narrow space, the quarter wave pipe 0 originally perpendicular to the main silencing pipe is folded and coiled along the axial direction (sound wave incidence direction), the axial line forms a spiral plane curve, and the pipe forms a labyrinth-type coplanar pipe, namely a labyrinth-type resonator 1.
Referring to fig. 3, the labyrinth resonator 1 includes a front panel 11, a labyrinth layer 12 and a rigid back plate 13, and the front panel 11, the labyrinth layer 12 and the rigid back plate 13 are sequentially and fixedly connected. A through hole 14 is processed at the central position of the front panel 11; the labyrinth layer 12 comprises a frame 121 and a plurality of clapboards 122 with different lengths, wherein the clapboards 122 are connected end to end and form a spiral shape, and a labyrinth-shaped air channel is formed between the clapboards 122 and the frame 121; the inlet of the labyrinth-shaped air channel is connected with the through hole of the front panel.
A sealing plate 123 is arranged on the labyrinth-shaped air channel in the direction vertical to the side wall of the channel, and the sealing plate 123 is fixedly connected with the side wall of the channel. The sealing plate 123 acts to vary the length of the air passage and thus the length of the quarter wave tube, to achieve sound attenuation at the target frequency.
Referring to fig. 4 and 5, the pipeline noise elimination device based on the labyrinth resonator 1 includes a main pipeline 2 with a square cross section, four labyrinth resonators 1 with the same tube length and symmetrically distributed on four side walls of the main pipeline, and labyrinth resonators 1 with different tube lengths and arranged along the axial direction of the main pipeline.
Referring to fig. 6, square through holes 24 are formed in the central positions of the four side walls 21 of the main pipe 2, and the square through holes 24 are symmetrically distributed.
Referring to fig. 6, in actual manufacturing, the labyrinth resonator 1 is installed on the side wall 21 of the main pipe 2, the front panel 11 of the labyrinth resonator 1 is the side wall 21 of the main pipe, and the inlet 14 of the labyrinth resonator 1 is the through hole 24 on the side wall of the main pipe.
Preferably, the cross section of the air passage of the labyrinth resonator 1 is square, and the area of the air passage is the same as that of the square through hole 24 on the side wall of the main pipe 2.
Preferably, the wall thickness of the labyrinth resonator 1 is the same as that of the main pipe 2; in order to avoid sound-solid coupling, the wall thickness is 1mm-2 mm.
Referring to fig. 5 and 6, based on the pipe silencing device of the labyrinth resonator 1, the labyrinth resonators 1 with different air passage lengths are axially arranged along the main pipe 2 to perform silencing in different frequency bands.
Referring to fig. 6, in the noise elimination design, the length of the air channel of the labyrinth resonator 1 can be determined according to the main noise elimination frequency; by changing the position of the sealing plate 123, the length of the air passage of the labyrinth resonator 1 can be changed.
Referring to fig. 5, 6 and 7, the labyrinth resonator 1 has a square cross-section of the air passage, and has an area corresponding to the main pipe sideThe square through-holes 24 in the wall 21 have the same area and have a side length of a2(ii) a The cross section of the main pipeline 2 is square, and the side length is a1。
In the present invention, the labyrinth resonator 1 is used as a bypass pipe of the muffler device, and the sound transmission loss thereof is as follows:
m is the ratio of the cross-sectional area of the labyrinth resonator 1 to the cross-sectional area of the main pipeline 2, and m is (a)2/a1)2λ is the wavelength of the acoustic wave, L is the acoustic length of the air channel center line of the labyrinth resonator 1, expressed as the sum of the actual length Ls of the air channel center line and the end correction length, and L is LSUsing the boundary element method to obtain the end correction length as follows:
in contrast to the installation position of the sealing plate 123 of fig. 7, the actual length Ls of the air passage center line can be expressed as:
and n is the number of times of the air channel is folded.
Example 1: parallel connection of a plurality of labyrinth resonators 1 of the same size
Sound waves incident in the direction of the main pipe, a1=10cm,a2When n is 4, the actual length Ls of the air channel center line of the labyrinth resonator 1 is 49cm, the end correction length is 0.78cm, and the acoustic length L of the air channel center line is 49.78 cm. If only one labyrinth resonator 1 is arranged on one side of the main pipeline, the noise elimination frequency band is very narrow as can be seen from fig. 8; if four labyrinth resonators 1 of the same size are mounted on the four side walls, which corresponds to four resonators connected in parallel, fig. 8 shows that the sound damping bandwidth is increased.
Example 2: series connection of a plurality of labyrinth resonators 1 of different sizes
As shown in fig. 7, a is a series connection of a plurality of resonators having different air passage lengths1=10cm,a22cm, the acoustic length of the air channel center line of the labyrinth resonator 1 is L1=49.78cm,L2=40.78cm,L3=32.78cm,L424.78 cm; the result of the numerical calculation is shown in fig. 9, and it can be seen from fig. 9 that when a plurality of resonators are connected in series, noise in different frequency bands can be eliminated in a targeted manner.
Example 3: silencing of air inlet of certain automobile engine
Taking the example of an automobile engine intake system, the typical length of the air intake is 0.6m, corresponding to a frequency of 140Hz at 1/4 wavelengths, for a firing frequency of a 4-cylinder 4-stroke engine of 4200 r/min. At the engine intake valve body, inserting the labyrinth resonator 1 having the same length as the air pipe, the pipe acoustic length L of the labyrinth resonator 1 being 0.68m, will generate stable transmission loss at the 1/4 wavelength frequency. In order to cover a wide frequency, it is required to use a plurality of labyrinth resonators 1 having different air passage lengths corresponding to 2000 to 5000r/min (67 to 167Hz) of the above-described engine, and the acoustic lengths of the ducts are 1.26 to 0.51m, respectively. At the opening of the engine intake duct, 3 labyrinth resonators 1 with different channel lengths are installed side by side in a concentrated manner, and fig. 10 shows the transmission loss of the silencer, and obviously, the transmission loss is the largest at 67Hz, 140Hz and 167 Hz.
The scope of the present invention includes, but is not limited to, the above embodiments, and the present invention is defined by the appended claims, and any alterations, modifications, and improvements that may occur to those skilled in the art are all within the scope of the present invention.