Introduction to car exhaust system
Introduction to car exhaust system
SNW introduces the knowledge of automobile exhaust system. It mainly includes four parts: the function of the exhaust system, the composition of the exhaust system, the key components of the exhaust system, and the development of the exhaust system.
1. Exhaust system functions
(1) Guide the engine exhaust so that the exhaust gas from each cylinder can be discharged smoothly.
(2) Due to the influence of the opening and closing of the exhaust valve and the reciprocating motion of the piston, the exhaust air flow is in the form of pulsation. When the exhaust valve is opened, there is a certain pressure and a certain amount of energy. Strong exhaust noise will be generated when the gas is discharged. , so an exhaust muffler is installed in the exhaust system to reduce exhaust noise.
(3) Reduce the content of exhaust pollutants CO, HC, NOX, NMHC, etc. to achieve exhaust purification.
2. Exhaust system composition
The exhaust system mainly consists of pre-catalyst assembly, particle trap assembly, GPF hose, front muffler assembly, rear muffler assembly, rubber hanging block, heat shield, sealing ring/pad, etc.
3. Key components of the exhaust system
3.1 Catalytic converter
The three-way catalytic converter assembly is the main component for purifying exhaust from cars and other engine stationary pollution sources. It uses three precious metals, platinum, palladium and rhodium, as catalysts to oxidize and reduce carbon monoxide, hydrocarbons and nitrogen oxides in the exhaust to generate carbon dioxide, nitrogen and water, thereby achieving purification results.
3.2 Catalyst carrier
There are two types of carriers: ceramic carrier and metal carrier
Ceramic carrier: cordierite
2MgO-2Al2O3-5SiO2
This kind of carrier has high temperature resistance and good adhesion properties, but it ignites slowly.
Metal carrier: iron-chromium alloy
Iron, chromium, aluminum
Yttrium and/or Cerium
This kind of carrier has a faster ignition speed but poor adhesion performance.
3.3. Gasoline Particle Filter
The National VI emission regulations impose stricter requirements on particulate matter emissions from gasoline vehicles. Compared with the National V regulations, the particulate matter mass (PM) limit has dropped by 33%, and a new limit requirement for particulate matter quantity (PN) has been added. The particle trap GPF is one of the means to reduce particulate matter emissions from the perspective of post-emission treatment. After installing GPF in the vehicle exhaust system, nearly 90% of particulate matter emissions can be filtered. However, after GPF captures a certain amount of particulate matter, it needs the engine to create conditions for high-temperature regeneration, ultimately forming a virtuous cycle of "capture-regeneration-capture".
3.4 Muffler assembly
The muffler assembly consists of a front muffler and a rear muffler. Mufflers are generally required to have large silencing volume and frequency range, small exhaust resistance (i.e. exhaust back pressure) and good durability.
According to the muffler mechanism, it can be divided into three categories: resistive muffler, resistance muffler and impedance composite muffler.
In the current design of automobile mufflers, the main structure adopts the principle of resistive muffler, and some of the structures adopt the principle of resistive muffler. These resistive mufflers are often integrated with the resistive muffler to form a hybrid muffler. device.
4. Development of exhaust system
4.1. Exhaust system final design
Develop exhaust system performance parameters based on engine parameters:
(1) Pre-catalyst, main catalyst or GPF volume;
(2) The volume of secondary and main consumers;
(3) Exhaust pipe diameter.
About SNW
SNW is mainly engaged in the Manufacturing and Wholesale of automobile exhaust system parts,The exhaust system parts mainly includes exhaust manifolds, headers, downpipes, cat-back systems,aluminum alloy intake pipes, T-pipe, Y pipe, X pipe, H pipe and other performance parts
