The muffler, as the name implies, is designed to suppress (muffle) sounds produced by technical means and devices that exceed the "normal" noise level for the human ear, or to silence the action produced in order to conceal it.
Necessary
diagram with a technical description of the muffler
Instructions
Step 1
The most famous and widespread use of the muffler, mufflers installed on cars. A running gasoline, diesel and gas engine makes a lot of noise. At the dawn of the automotive industry, cars drove through the streets without mufflers, frightening passers-by and forcing horses harnessed to carts to shy away. However, this did not last long, and soon the roaring motors "bridled" the simplest jamming devices. Otherwise, they were threatened with expulsion from the city streets.
Step 2
A modern car muffler is designed to reduce the noise level of the outgoing exhaust gases to an acceptable value, as well as their temperature and toxicity. Sound is muffled by damping the high velocity of gases entering the device from the engine cylinders. From the cylinders, gases are fed directly to the muffler through the so-called "trousers" - the intake pipes or the exhaust manifold.
Step 3
Reducing the sound level with a muffler is achieved in several ways, based on the following physical principles:
- the principle of limitation, when due to the narrowing of the pipe and the subsequent transition to a large diameter, an acoustic resistance is created with the subsequent dissipation of sound energy;
- the principle of reflection, when sound energy is scattered from the reflective "mirrors" built into the body;
- the principle of resonance, when sound through the holes in the main pipe enters a closed cavity located on or next to the pipe. Sound energy is damped by a rapidly changing resonant frequency;
- the principle of absorption is based on the absorption of a sound wave by a special porous material.
Step 4
The most common design of an automobile muffler consists of three main components: a catalytic converter (catalyst), a front muffler and a rear muffler. In the catalyst, the toxicity of exhaust gases is reduced due to the afterburning of the mixture and the retention of residues of harmful substances in the honeycomb of the catalytic substance. The main (front) and secondary (rear) mufflers use sophisticated systems of internal structures to reduce the temperature and air velocity, absorbing the noise from the exhaust gases.
Step 5
Mufflers for gasoline engines may include lambda sensors. They determine the oxygen concentration in the exhaust gas. An electrical signal is sent to the electronic unit of the engine control system from them, and, depending on its value, an optimal fuel-air mixture is automatically formed.
