CN203347888U - SCR muffling mechanism - Google Patents

Abstract

The utility model relates to an SCR noise reduction mechanism, which comprises a cylinder body with an open front end and a closed rear end, an air outlet tailpipe is inserted on the rear end wall of the cylinder body, and two perforated partitions are arranged in the middle of the cylinder body. Two perforated partitions divide the inner cavity of the cylinder into an expansion cavity in the front, a sound-absorbing material-filled cavity in the middle, and a resonance cavity in the rear; After a perforated partition, it communicates with the expansion chamber, and a plurality of resonance chamber perforations communicating with the resonance chamber are opened on the pipe wall of the gas outlet tail pipe. The utility model increases the transmission loss of the silencer through the reasonable combination of resistive and resistive noise reduction structures, and achieves a good noise reduction effect.

Description

A kind of SCR silencer mechanism

technical field

The utility model relates to the field of SCR mufflers, in particular to an SCR muffler mechanism.

Background technique

When the engine is working, the exhaust gas needs to be continuously discharged into the atmosphere. The exhaust pressure of the engine is about 0.3-0.5Mpa, and the temperature is about 500-700°C, which indicates that the exhaust gas has a certain amount of energy. The pulsation of the exhaust pressure is caused in the exhaust pipe. If the engine exhaust is discharged directly into the atmosphere, it will inevitably produce strong noise. The function of the exhaust muffler is to eliminate the exhaust noise by gradually reducing the exhaust pressure and attenuating the pulsation of the exhaust pressure.

There are usually four evaluation indicators for the noise reduction effect of noise reduction components and systems, transmission loss, insertion loss, sound pressure level difference and sound pressure level. The muffler is divided into active muffler and passive muffler, and passive muffler is divided into resistive muffler and resistive muffler. Resistive muffler mainly uses some sound-absorbing materials. When sound waves pass through the muffler, part of the sound energy is absorbed, thereby achieving the purpose of sound absorption. Resistive muffler means that when sound energy passes through the muffler, the acoustic impedance changes, and part of the sound energy is reflected back to the sound source, reducing the transmitted sound energy. The SCR muffler is used in the automobile exhaust system. This kind of muffler uses the SCR catalytic converter to purify the exhaust gas, and then uses the muffler mechanism at the rear to deal with the noise. In the existing SCR muffler, in order to reduce the power loss ratio and exhaust back pressure of the diesel engine, the insertion loss often fails to meet the design requirements, and the acoustic performance of the SCR muffler is poor.

If an SCR noise reduction mechanism can combine the above-mentioned resistance and resistance structures, it will reduce the noise of the exhaust of the engine in a wider frequency band, which will increase the insertion loss and improve the acoustics of the silencer. Improved performance.

Utility model content

The technical problem to be solved by the utility model is to provide an SCR noise reduction mechanism combined with resistive and resistive structures for noise reduction, simple in structure and good in noise reduction effect.

In order to solve the above-mentioned technical problems, the SCR silencer mechanism of the utility model includes a cylinder body with an open front end and a closed rear end. The rear end wall of the cylinder body is inserted with an exhaust tailpipe. There are two perforated partitions, the two perforated partitions divide the inner cavity of the cylinder into the expansion cavity in the front, the sound-absorbing material filling cavity in the middle and the resonance cavity in the rear; the exhaust tailpipe passes through the resonance cavity in the cylinder The cavity, the sound-absorbing material filling cavity and the two perforated partitions communicate with the expansion cavity, and the wall of the gas outlet tail pipe is provided with a plurality of resonance cavity perforations that communicate with the resonance cavity.

The sound-absorbing material filling cavity is filled with glass fiber sound-absorbing material, and the sound-absorbing material forms a sound-absorbing layer in the cavity.

The pipe wall of the gas outlet tail pipe is provided with a plurality of sound-absorbing internal perforations that can lead into the sound-absorbing material filling cavity.

The perforated partition is densely covered with a plurality of partition through holes.

The opening at the inner extension end of the exhaust tail pipe is a trumpet-shaped diversion port.

With the above structure, the opening at the front end of the barrel is connected to the front half of the SCR muffler, and the sound wave enters from the intake pipe of the SCR muffler, passes through the SCR catalytic carrier at the front, and then enters the expansion chamber of the present invention. The expansion chamber makes The sudden change of the section of the pipe causes the change of the acoustic impedance, so that part of the sound wave propagating along the pipe is reflected back to the sound source; at the same time, the change of the length of the expansion cavity is used to make the difference between the sound wave propagating forward and the reflected wave on different pipe sections A phase difference of 180o is generated and interferes with each other, so as to achieve the purpose of noise reduction, reduce the transmitted sound energy, and improve its acoustic performance; adding a resonant cavity can eliminate noise in a specific frequency band. Under the action of the air column in the aperture, the air column in the aperture vibrates. During the vibration, the frictional damping converts part of the sound energy into heat energy and dissipates it. Only a small amount of sound energy is radiated out, achieving the purpose of noise reduction; filling between the two perforated partitions The sound-absorbing material can eliminate or reduce high-frequency noise. When the sound wave passes through, it enters the sound-absorbing layer from the inner perforation of the sound-absorbing layer and the through-hole of the partition plate. When the sound wave propagates in the glass fiber sound-absorbing material, the sound energy is converted by friction It is dissipated for heat energy, which improves the acoustic performance and achieves the purpose of reducing exhaust noise. To sum up, the utility model increases the transmission loss of the muffler and achieves a good noise reduction effect through a reasonable combination of resistive and resistive noise reduction structures.

Description of drawings

Below in conjunction with accompanying drawing and specific embodiment the utility model is described in further detail:

Fig. 1 is the structural representation of the utility model;

Fig. 2 is a schematic structural view taken along the A-A direction in Fig. 1;

Fig. 3 is a structural schematic diagram of the utility model installed at the rear end of one of the SCR mufflers.

Detailed ways

Referring to the accompanying drawings, the SCR silencer mechanism of the present invention includes a cylinder body 1 with an open front end and a closed rear end. The rear end wall of the cylinder body 1 is inserted with an exhaust tailpipe 2, and the middle part of the cylinder body 1 is provided with two perforations. The partition 3, the two perforated partitions 3 divide the inner cavity of the cylinder into an expansion chamber 4 at the front, a sound-absorbing material filling chamber 5 at the middle and a resonance chamber 6 at the rear. The air outlet tailpipe 2 passes through the resonance chamber 6, the sound-absorbing material filling chamber 5 and two perforated partitions 3 in the cylinder body 1, and then communicates with the expansion chamber). 6 communicated resonant cavity perforations 60 . Wherein, the sound-absorbing material filling cavity 5 is filled with glass fiber sound-absorbing material and the sound-absorbing material forms a sound-absorbing layer in the cavity. The perforated partition 3 is densely covered with a plurality of partition through holes 30 . The pipe wall of the air outlet tail pipe 2 is provided with a plurality of sound-absorbing internal perforations 50 that can lead into the sound-absorbing material filling cavity 5 . The opening at the inner extension end of the air outlet tailpipe 2 is a trumpet-shaped diversion port 21 .

Referring to Figure 3, the utility model is installed at the rear of the SCR muffler, the front of the SCR muffler is provided with an intake pipe 8, and the exhaust gas enters the mixing chamber 7 of the SCR muffler through the intake pipe 8, and then passes through the SCR catalytic carrier 9 to carry out purification treatment, and the exhaust gas after treatment directly enters the expansion cavity 4 of the utility model, and the expansion cavity 4 makes the section of the pipeline change abruptly, thereby causing a change in acoustic impedance, so that part of the sound waves propagating along the pipeline are reflected back to the sound source. In addition, a reasonable length of the expansion cavity 4 can be set, so that the forward propagating sound wave and the reflected wave on different pipe sections have a phase difference of 180o, and interfere with each other, so as to achieve the purpose of noise reduction. In order to eliminate the noise of a specific frequency band, a resonant cavity 6 is added. When the sound wave enters the resonant cavity 6 from the perforated hole 60 of the resonant cavity, under the action of the sound wave, the air column in the aperture vibrates, and the frictional damping during the vibration converts a part of the sound energy into Heat energy is dissipated, and only a small amount of sound energy is radiated. Filling the sound-absorbing material between the two perforated partitions 3 can eliminate or reduce high-frequency noise. When the sound wave passes through, it enters the sound-absorbing layer from the inner perforation 50 of the sound-absorbing plate and the through-hole 30 of the partition, and the sound wave is eliminated by the glass fiber. When propagating in the material, the friction converts the sound energy into heat energy and dissipates it, so as to achieve the purpose of noise reduction.

To sum up, the utility model is not limited to the above specific embodiments. Those skilled in the art can make several changes and modifications without departing from the spirit and scope of the present utility model. The protection scope of the utility model should be based on the claims of the utility model.

Claims (5)

1. An SCR silencer mechanism, comprising a cylinder body (1) with an open front end and a closed rear end, and an air outlet tailpipe (2) is inserted on the rear end wall of the cylinder body (1), characterized in that the cylinder body The middle part of (1) is provided with two perforated partitions (3), and the two perforated partitions (3) divide the inner cavity of the cylinder into the expansion chamber (4) at the front and the sound-absorbing material filling chamber (5) at the middle. and the resonance cavity (6) at the rear; the outlet tailpipe (2) passes through the resonance cavity (6), the sound-absorbing material filling cavity (5) and two perforated partitions (3) in the cylinder (1) Afterwards, it communicates with the expansion cavity (4), and a plurality of resonance cavity perforations (60) communicating with the resonance cavity (6) are opened on the pipe wall of the gas outlet tail pipe (2). 2. The SCR noise reduction mechanism according to claim 1, characterized in that the noise reduction material filling cavity (5) is filled with glass fiber noise reduction material and the noise reduction material forms a glass fiber noise reduction layer in the cavity. 3. The SCR noise reduction mechanism according to claim 2, characterized in that the pipe wall of the outlet tailpipe (2) is provided with a plurality of sound-absorbing internal perforations that can pass into the sound-absorbing material filling cavity (5) (50). 4. The SCR noise reduction mechanism according to claim 2, characterized in that the perforated partition (3) is densely covered with a plurality of partition through holes (30). 5. The SCR noise reduction mechanism according to any one of claims 1 to 4, characterized in that the opening at the inner extension end of the outlet tailpipe (2) is a trumpet-shaped diversion port (21).

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