The main structure of the car muffler

Car mufflers can be divided into three categories: resistive mufflers, resistive mufflers and impedance composite mufflers according to the principle and structure of noise elimination.



  1. Resistant muffler

Resistant muffler is a kind of muffler unit, such as expansion room, resonance room, etc., is composed of pipes, partitions and other components. Sound waves are reflected and interfered during propagation, reducing the sound energy to achieve the purpose of sound elimination. Resistant muffler has a limited muffling frequency band, and usually has good muffling effect for low and mid frequency bands, but poor muffling effect for high frequency. Trucks mostly use resistant mufflers.



  2. Resistive muffler

Resistive muffler is a muffler that is filled with sound-absorbing materials around the pipe through which the internal exhaust gas passes to absorb sound energy to achieve sound attenuation. It has good muffling effect on medium and high frequency, and it is rarely used as a car exhaust muffler. It is usually used in combination with a resistant muffler.



  3. Impedance compound muffler

Impedance composite muffler is a muffler composed of a combination of resistant muffler units and sound-absorbing materials. It has the common characteristics of resistant and resistive mufflers. It has a good muffling effect for low, medium and high frequency noise. The main function is to reduce the exhaust noise of the engine and enable the high-temperature exhaust gas to be discharged safely and effectively. As a part of the exhaust pipe, the muffler should ensure smooth exhaust, low resistance and sufficient strength. The muffler must withstand 500℃~700℃ high temperature exhaust to ensure that it will not be damaged or lose its muffling effect within the specified mileage of the car. Related application vehicle noise mainly comes from vehicle exhaust noise. Without the muffler, the noise can reach more than 100 decibels at a certain speed. The second is engine noise and tire noise. The engine noise can reach more than 90 decibels when the car is running normally, and the tire noise can reach about 95 decibels when the vehicle speed is above 90 km/h. Therefore, adding a muffler to the exhaust system can reduce vehicle exhaust noise by 20-30 decibels. In terms of engines, replacing diesel engines with gasoline engines can reduce engine noise by 6-8 decibels.