| 摘要 |
PROBLEM TO BE SOLVED: To provide an exhaust emission control system in which the slip of NH3 due to excess urea water injection is prevented.SOLUTION: The exhaust emission control system includes: an SCR 41 which uses ammonia formed from urea water as reductant and removes NOx from exhaust gas; a urea water injection device 60 for injecting the urea water into an exhaust passage 12 upstream from the SCR 41; an estimated adsorption amount calculating part 51 for calculating the estimated adsorption amount of the ammonia adsorbed to the SCR 41; a urea water injection control part 52 for performing the injection control of the urea water injection device 60 on the basis of the estimated adsorption amount; and an estimated adsorption amount changing part 53 for changing the estimated adsorption amount used for the injection control into a value increased/reduced by a predetermined amount, when predetermined conditions are established to possibly cause a deviation between the actual adsorption amount of the ammonia adsorbed to the SCR 41 and the estimated adsorption amount. |
