EXHAUST EMISSION CONTROL DEVICE OF INTERNAL COMBUSTION ENGINE

PROBLEM TO BE SOLVED: To provide an exhaust emission control device of an internal combustion engine capable of supplying a reasonable quantity of urea aqueous solution by always calculating an appropriate NOx discharge amount regardless of whether regeneration control of a DPF is in execution or not, thereby achieving excellent NOx elimination characteristics, and of preventing wasteful consumption of the urea aqueous solution and slip. SOLUTION: A map in preliminary temperature-raising control according to a process in forced regeneration of a DPF, a map in raising control and a map in lowering control are set, separately from a map in normal control, as a map for calculating an NOx discharge amount, and an NOx discharge amount is calculated from a map according to a current operation state (S4, 16, 18); and the urea aqueous solution is supplied by driving an injection nozzle based on a urea supply amount obtained from the calculated NOx discharge amount (S8). COPYRIGHT: (C)2008,JPO&INPIT