EXHAUST GAS CLEANING DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide an exhaust gas cleaning device for an internal combustion engine which can accurately calculates a concentration of urea water and detect that the concentration of the urea water is lower than a prescribed value.SOLUTION: The exhaust gas cleaning device 2 includes: an NOamount calculation part 15 which calculates the amount of NOcleaned by an SCR catalyst 8; a necessary urea water amount calculation part 17 which calculates the necessary urea water amount needed for cleaning the NOamount calculated by the NOamount calculation part 15; a urea water consumption calculation part 36 which calculates the amount of the urea water consumption actually supplied to a communication path 32 within a predetermined time; and a urea water concentration calculation part 33 which calculates an actual urea water concentration based on the necessary urea water amount calculated by the necessary urea water amount calculation part 17, and the urea water consumption calculated by the urea water consumption calculation part 36.