EGR is the abbreviation for Engine Exhaust Gas Recirculation System, which means to suck the exhaust gas that has been burned by the engine back into the cylinder for combustion.

Don't underestimate this feature, it not only reduces emissions but also saves fuel. Today, let's talk about the topic of EGR.

If you have carefully observed your engine, you must have seen this thing in the picture below.

This is the EGR valve, with one end connected to the intake end and the other end connected to the exhaust end. The engine control system will control the EGR valve to open at the appropriate time, allowing a portion of the burned exhaust gas to re-enter the cylinder for combustion.

In theory, exhaust gas has no further utilization value. Why should it be sucked back into the cylinder?

People invented EGR mainly for exhaust emissions. Because the air contains a large amount of nitrogen, the temperature during engine combustion is very high, and as a result, nitrogen will generate a harmful component called nitrogen oxides. So the environmental protection department imposed restrictions on nitrogen oxides in car exhaust, and did not allow you to sell your car if it did not meet the standards. So the engineers began to think of ways to solve this problem.