The working principle and structure of exhaust muffler

The exhaust muffler is manufactured from aluminized or stainless steel sheet. Usually the muffler consists of a resonance chamber, an expansion chamber and a set of porous tubes. Some are also filled with heat-resistant sound-absorbing material in the muffler, and the sound-absorbing material is mostly glass fiber or asbestos. The exhaust gas flows into the expansion chamber and the resonance chamber through the porous tube. During this process, the exhaust gas continuously changes the flow direction, gradually reduces and attenuates its pressure and pressure pulsation, consumes its energy, and finally reduces the exhaust noise.

It includes muffler shell, inner shell, inner and outer partitions, inlet and outlet pipes, etc. The muffler shell is welded by double-layer steel plates with a sandwich in between. The inner shell is corrugated and forms an exhaust passage with the inner wall of the outer shell. This structure is beneficial to the attenuation of sound pressure and the diffusion of sound waves, which can enhance the effect of sound reduction. Sometimes the muffler alone still cannot meet the standard of automobile exhaust noise. At this time, a resonator similar to a small muffler needs to be installed in the exhaust system.

A resonator in series with a muffler can further reduce the noise level. The muffler is installed between the catalytic converter and the tailpipe and near the center of the car. But sometimes due to space constraints, the muffler is often installed at the rear of the car. At this time, due to the low temperature of the muffler, more water vapor will condense into water in the muffler, causing the muffler to rust.