What Is The Role Of EGR?

The EGR valve is used to reduce the emission of nitrogen oxides (NOX) in the exhaust gas. Nitrogen and oxygen will only undergo chemical reaction under high temperature and high pressure conditions. The temperature and pressure in the engine combustion chamber meet the above conditions, especially during forced acceleration. 　

When the engine is running under load, the EGR valve opens, allowing a small amount of exhaust gas to enter the intake manifold and enter the combustion chamber together with the combustible mixture. At idle, the EGR valve is closed and almost no exhaust gas is recirculated to the engine.

Automobile exhaust gas is a non-combustible gas (without fuel and oxidant) and does not participate in combustion in the combustion chamber. It reduces the combustion temperature and pressure by absorbing part of the heat generated by combustion to reduce the amount of nitrogen oxide generated. 

The amount of exhaust gas entering the combustion chamber increases as the engine speed and load increase.

Exhaust gas recirculation is a method of introducing part of the exhaust gas to the fresh air (or mixed gas) that is sucked into the cylinder and recirculating it to participate in the combustion during the operation of the engine. Its role is to reduce NOx emissions.