| 摘要 |
PROBLEM TO BE SOLVED: To provide an exhaust emission control system and an exhaust emission control method capable of preventing a reduction in the NOx eliminating rate of an exhaust emission control device such as a selective reduction type catalyst, and of compatibly improving a fuel consumption rate and exhaust gas performance without reducing the NOx eliminating rate during the light load operation of an engine and during the high load operation of the engine to be good in the fuel consumption rate, as well.SOLUTION: An exhaust gas passage 12 between a turbine 13t and an exhaust emission control device 30 is formed with a radiation exhaust gas pipe 12A. Radiation surface area increasing members 12Ba, 12Bb are provided on the radiation exhaust gas pipe 12A. Thus, when an internal combustion engine 10 continuously operates at a rated output, a radiation surface area S of a portion of the radiation exhaust gas pipe 12A becomes an optimum radiation surface area S1 to keep a temperature Tg of exhaust gas G flowing into the exhaust emission control device 30 to be a preset eliminating rate holding upper limit temperature T2 or lower. |
