EXHAUST EMISSION CONTROL SYSTEM

摘要

PROBLEM TO BE SOLVED: To efficiently reduce NOx occluded in an NOx occlusion reduction type catalyst for purification.SOLUTION: An exhaust emission control system includes: an NOx occlusion reduction type catalyst 32 occluding NOx in exhaust gas in an exhaust lean state and reducing NOx occluded in an exhaust rich state for purification; and an NOx purge rich control section 140 for making exhaust gas rich by repeating at predetermined intervals at least one of fuel injection control out of post injection and exhaust pipe injection so as to reduce NOx occluded in the NOx occlusion reduction type catalyst 32 for purification.SELECTED DRAWING: Figure 1