EXHAUST EMISSION CONTROL SYSTEM FOR INTERNAL COMBUSTION ENGINE, INTERNAL COMBUSTION ENGINE AND EXHAUST EMISSION CONTROL METHOD FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide an exhaust emission control system for an internal combustion engine, the internal combustion engine and an exhaust emission control method for the internal combustion engine that can inhibit desorption of large amount of ammonia from a selective reduction type catalyst device and can highly accurately suppress ammonia slip to the atmosphere while reducing the size of or eliminating the necessity of an ammonia slip catalyst device, which is provided in an exhaust passage downstream of a selective reduction type catalyst device in conventional cases, even if a temperature of exhaust gas is raised when a temperature of the selective reduction type catalyst device is within a temperature range enabling storage control.SOLUTION: Based on a temperature detection value T obtained by a temperature sensor 23 and an ammonia estimated adsorption amount S to a selective reduction type catalyst device 14, supply control of urea water U by using an urea water supply device 20 and flow rate control of exhaust gas G2 passing through a bypass passage 31 having a heat exchange device 30 by using a three-way valve 32 are performed.SELECTED DRAWING: Figure 2