What is the function of the EGR valve in a car engine?
3 Answers
The function of the EGR valve in a car engine is to control the amount of exhaust gas entering the intake manifold, allowing a certain amount of exhaust gas to flow into the intake manifold for recirculation. The EGR valve is a very important and critical component in the exhaust gas recirculation system, and it can be divided into mechanical and electronic control types. A car engine is a machine that converts other forms of energy into mechanical energy. Its maintenance methods include: 1. Using high-quality engine oil; 2. Using qualified coolant; 3. Regularly cleaning the radiator scale; 4. Regularly removing carbon deposits from the car; 5. Timely replacement of the car's three filters; 6. Maintaining a reasonable engine speed.
Having run a repair shop for over a decade, I've found that the EGR valve's function can be simply described as controlling exhaust gas recirculation. It redirects a portion of exhaust gas from the exhaust pipe back into the cylinders for secondary combustion, which helps lower combustion temperatures and prevent knocking. With stricter environmental regulations now, this valve effectively reduces nitrogen oxide emissions. Especially during idle or low RPM conditions, the EGR valve opens more significantly, making the engine more eco-friendly. However, it's also one of the most problematic components—carbon buildup can cause the valve to stick, leading to sluggish acceleration or black smoke. During repairs, a complete cleaning is often necessary to restore performance.
We mechanical engineering students all know that the EGR valve is the core component of the exhaust gas recirculation system. It redirects high-temperature exhaust gases back into the intake manifold, diluting the air-fuel mixture concentration. The principle is somewhat similar to pouring cold water on a flame, capable of suppressing combustion temperatures up to 200 degrees Celsius. The direct benefit is reducing nitrogen oxide emissions, while indirectly saving some fuel. Modern vehicles now feature intelligent control modules - the valve automatically closes during rapid acceleration to ensure power delivery, and opens wider during steady cruising. The only downside is that the recirculated exhaust carries carbon deposits, requiring cleaning every 2-3 years to prevent fault codes from appearing.
