Exhaust Gas RECIRCULATION (EGR) System: Notes
When the combustion gas temperature becomes high, generation of the environment polluting NOx (nitrogen oxides) increases rapidly. Exhaust gas recirculation system is used to decrease the volume of NOx generated. Exhaust gas recirculation system re-circulates exhaust gas inside the intake manifold. It increases specific heat of the combustion gases and reduces combustion speed to lower the combustion temperature and reduce the volume of NOx generated. In addition, exhaust gas temperature is lowered by installing a water-cooled EGR cooler to enhance these effects. Furthermore, an EGR temperature sensor is mounted on the EGR pipe between the EGR valve and the intake manifold to check the exhaust gas temperature. ECM calculates the exhaust gas recirculation introduction volume according to engine operating conditions and controls the exhaust gas recirculation valve opening angle at optimum. Also, immediately after the power supply mode of electric motor switch ON signal is input, it drives fully closed stepper motor and performs initialisation.