The EGR system, a key technology for reducing nitrogen oxide emissions from engines, originated in 1970, even predating three-way catalytic converter technology. However, due to the immaturity of electronic fuel injection technology at the time, it was impossible to precisely control exhaust gas recirculation and fuel injection, leading to increased fuel consumption. Therefore, this technology was temporarily shelved. With breakthroughs in electronic fuel injection technology, the EGR system regained its application and was given a new lease on life.
So, what exactly is the EGR system? EGR stands for Exhaust Gas Recirculation. Simply put, it involves reintroducing a portion of the exhaust gas from engine combustion back into the intake system for reuse. The purpose of this is to reduce nitrogen oxide (NOx) emissions in the exhaust gas. Its working principle lies in the fact that exhaust gas has a very low oxygen content and is rich in the inert gas carbon dioxide. When this part of the exhaust gas mixes with fresh air, it can lower the combustion temperature, reduce the formation of nitrogen oxides, improve fuel combustion efficiency, and reduce heat loss from the cylinder walls, thereby achieving environmental benefits.
While exhaust gas recirculation (EGR) systems offer numerous advantages, a key challenge in practical applications is precisely controlling the amount of exhaust gas mixed in. Typically, the amount of exhaust gas mixed in should not exceed 15% of the fresh air. Furthermore, exhaust gas recirculation must be cut off at engine idling or high speeds to avoid increasing fuel consumption. Therefore, a valve capable of precisely regulating the amount of exhaust gas-the EGR valve-is particularly important.
