What is the difference between egr valve and PCV valve?

EGR valve is a control valve in exhaust gas recirculation. Exhaust gas recirculation refers to the technology of reintroducing a part of exhaust gas into the cylinder. The EGR valve is used to control the amount of exhaust gas re-entering the cylinder.

PCV valve is the control valve of crankcase forced ventilation system. When the engine is working, a part of the mixed gas in the cylinder will run into the crankcase, which will lead to the increase of crankcase pressure and the deterioration of oil. So the crankcase needs ventilation. PCV valves are usually one-way valves. Used to control the ventilation of crankcase.

EGR technology can reduce the fuel consumption of the engine under moderate load and the combustion temperature in the cylinder, thus reducing the emission of nitrogen oxides, reducing the exhaust temperature and reducing the tendency of knocking.