Working Principle Of Muffler

(1) Principle of resistive muffler
Principle Explanation
Resistive mufflers mainly use porous sound-absorbing materials to reduce noise. Fixing sound-absorbing materials on the inner wall of the airflow channel or arranging them in a certain way in the pipeline constitutes a resistive muffler. When sound waves enter a resistive muffler, a portion of the sound energy is converted into heat energy through friction in the pores of the porous material and dissipated, weakening the sound waves passing through the muffler. A resistive muffler is like an electrical pure resistance circuit, and the sound-absorbing material is similar to a resistor.

Noise reduction frequency characteristics
Good noise reduction effect for medium and high frequencies, but poor noise reduction effect for low frequencies.

(2) Principle of Resistance Muffler
Principle Explanation
A resistant muffler is composed of a combination of tubes and chambers with abrupt interfaces, resembling an acoustic filter, similar to an electrical filter. Each chamber with a tube is a mesh of the filter, and the air quality in the tube is equivalent to the electrical inductance and resistance, known as acoustic mass and acoustic resistance; The volume of air in a small chamber is equivalent to an electrical capacitance, known as acoustic compliance. When sound waves containing various frequency components enter the first short tube, only sound waves of certain frequencies near the natural frequency of the first mesh can pass through the mesh and reach the second short tube mouth, while sound waves of other frequencies cannot pass through the mesh and can only reflect back and forth in the small chamber, thus achieving the purpose of noise reduction.

Noise reduction frequency characteristics
Suitable for eliminating mid to low frequency noise. Resistance silencers, also known as reflective silencers, are used in the vast majority of original vehicles, and there is no need to worry about the sound-absorbing foam becoming ineffective over time, making them relatively durable. When it is composed of various soundproof units such as expansion chambers and resonance chambers through pipes, partitions, etc. inside, sound waves reflect and interfere during propagation, reducing sound energy. The noise reduction frequency band is limited, and it usually has good noise reduction effect for low and medium frequency bands, but poor noise reduction effect for high frequency bands. Resistance mufflers are often used in trucks.

(3) Principle of Impedance Composite Muffler
Principle Explanation
Its characteristic is that it has both an expansion chamber and sound-absorbing fibers. A muffler composed of a combination of resistant sound-absorbing units and sound-absorbing materials, which combines the characteristics of the first two types of mufflers.

Noise reduction frequency characteristics and other features
The corresponding frequency range is wide, the volume is more flexible, but the cost is relatively high.