YQ-SU(PSL)

The engine muffler mainly adopts porous sound absorption material to reduce noise. The sound absorption material is fixed on the inner wall of the airflow passage or arranged in the pipeline in a certain way. As the sound wave enters the resistive muffler, part of the acoustic energy is converted into heat dissipation energy by friction in the pores of porous materials, which weakens the acoustic wave passing through the muffler. Resistive muffler is a pure resistance circuit, sound absorption material and resistance are very similar. Therefore, this kind of silencing device is called resistive silencing. The noise elimination effect of duct muffler is poor in medium frequency and low frequency. It is composed of tubes and cavities with abrupt interface, just like an acoustic filter, similar to an electrical filter. Each chamber with a tube cavity is the mesh of the filter. The air quality in the tube cavity is equal to the inductance and resistance, which is called acoustic quality and acoustic resistance. The volume of air in this chamber is equivalent to the capacitance, which is called acoustic compliance. Like electric filtering, each tubule chamber has its own natural frequency. When the sound waves with various frequency components enter the short pipe, only the sound waves of specific frequency near the natural frequency of the mesh can pass through the mesh to reach the second short pipe orifice, while the sound waves of other frequencies can not pass through the mesh. They can only reflect back and forth in the chamber. Therefore, we call it the acoustic filter which has the filtering effect on the acoustic wave. The noise of some frequency components can be filtered out by selecting the appropriate combination of tube and cavity, so as to achieve the purpose of noise elimination. Anti noise muffler is suitable for eliminating medium frequency and low frequency noise.