The silencing effect of different materials also varies.
The resistive car muffler is mainly composed of porous tubes and sound-absorbing fibers (absorbent cotton). The sound absorption coefficient of the latter material varies with physical properties such as density and diameter, that is, the higher the fiber density, the smaller the diameter, and the higher the sound absorption coefficient. At the same time, the impact on the noise reduction effect is also related to the overall noise reduction effect. Of course, various factors such as cross-sectional circumference, effective length, and cross-sectional area also affect the noise reduction effect. The larger the circumference and effective length, the better the noise reduction effect.
1、 How does a resistive car muffler emit gas?
A resistive muffler is composed of porous tubes and sound-absorbing fibers. When exhaust gas comes into contact with the fibers through the porous tubes, it produces vibration, generates heat energy due to friction and bonding, and converts noise during this process, thus also known as the sound-absorbing process.
Resistive silencers have the characteristic of small volume, so most original car drums prefer to use resistive silencers. If you want to fully utilize their noise reduction function, the installation position is generally closer to the engine direction. Many experimental results have shown that resistive mufflers have a better suppression effect on engine mid to high frequency noise than mid frequency and mid frequency mufflers. Similarly, the performance of anti ventilation is exactly opposite to that of resistance.
2、 Composite (shaped) muffler.
As its name suggests, the structure of the composite car muffler combines the characteristics of the first two types of mufflers, namely both suction cotton and expansion chamber. As mentioned above, the two types of mufflers have their own strengths and weaknesses at corresponding engine speeds. The composite structure can balance the two characteristics well and has a large volume, but the cost is relatively high.
3、 Resistance muffler
There is no sound-absorbing cotton in this structure, also known as a reflective muffler, which is mainly composed of partitions and expansion chambers. A regular car muffler has three expansion chambers of different sizes. The exhaust is used to reflect and interfere with each other (friction) in these chambers to achieve noise reduction effect. Larger chambers are more conducive to noise processing, but their size is also limited by the shape of the chassis. SUVs such as Audi Q7 and BMW X5 have this advantage. In addition, due to different usage methods, the volume of the resistant muffler is larger than its resistance, so it is often installed at the rear. The obvious suppression effect on medium and low frequency noise has won many praises from the original factory.
The quality of a muffler directly affects the driving experience, and the better the silencing effect, the better the silencing effect of the car.
