Automotive silencers can be divided into three categories based on their sound attenuation principles and structures: reactive silencers, resistive silencers, and impedance composite silencers.

1. Resistance muffler refers to the sound wave that reflects and interferes with the propagation of various noise reduction units such as expansion chambers and resonance chambers formed by internal components such as pipelines and partitions, reducing the sound energy to achieve the purpose of noise reduction. The noise reduction frequency band of the resistant muffler is limited, and it usually has good noise reduction effect on low and medium frequency bands, but poor noise reduction effect on high frequency bands. Freight cars often use resistant mufflers.

2. The resistive muffler E is a muffler that fills the surrounding pipes of the internal exhaust with sound-absorbing materials to absorb sound energy and achieve the purpose of noise reduction. It has good noise reduction effect on medium and high frequencies, and is rarely used solely as a car exhaust muffler. It is usually combined with a reactive muffler for use.

3. Impedance composite silencers are silencers composed of resistance silencing units and sound absorbing materials, which share the common characteristics of resistance and resistance silencers. It has a good noise reduction effect on low, medium, and high frequency noise.

Main functions

Reduce engine exhaust noise and ensure safe and effective discharge of high-temperature exhaust gases. As a part of the exhaust pipeline, the muffler should ensure smooth exhaust, low resistance, and sufficient strength. The muffler should withstand high temperature exhaust from 500 ℃ to 700 ℃ to ensure that it is not damaged or loses its sound attenuation effect within the specified driving range of the car.

Related applications

Car noise mainly comes from car exhaust noise. If no muffler is added, the noise can reach over 100 decibels at a certain speed. Next are engine noise and tire noise. Engine noise can reach over 90 decibels during normal car operation, while tire noise can reach around 95 decibels at speeds above 90 kilometers per hour. Therefore, adding a muffler to the exhaust system can reduce car exhaust noise by 20-30 decibels. In terms of engine, replacing Diesel engine with Petrol engine can reduce engine noise by 6-8 decibels.