EXHAUST EMISSION CONTROL SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide an exhaust emission control system which precisely detects an SCR internal temperature to optimize a urea water injection amount.SOLUTION: An exhaust emission control system includes an SCR 22 which is provided in an exhaust system of an engine 10 and reductively purifies NOx contained in the exhaust gas with ammonia produced from urea water being used as a reductant agent; a urea water injection device 21 which injects the urea water to the SCR 22; an electrode 27 which detects the electrostatic capacitance of the SCR 22; an SCR internal temperature calculation unit 51 which calculates the internal temperature of the SCR 22 on the basis of the electrostatic capacitance input from the electrode 27; a urea water injection control unit 52 which controls the injection of the urea water from the urea water injection device 21 on the basis of a predetermined reference injection amount; and an injection amount correction unit 53 which corrects the reference injection amount on the basis of the internal temperature input from the SCR internal temperature calculation unit 51.