METHOD OF CONTROLLING NOx PURIFICATION SYSTEM AND NOx PURIFICATION SYSTEM

摘要

A method of controlling NOx purification system (1) including NOx occlusion reduction catalyst (22) and control unit (30) capable of NOx regeneration control and sulfur poisoning regeneration control, wherein the level of deterioration of NOx occlusion reduction catalyst (22) by sulfur poisoning is estimated on the basis of the amount of oxygen adsorbed and occluded on the NOx occlusion reduction catalyst (22) immediately after a termination of rich air fuel ratio condition of NOx regeneration control. Accordingly, excess sulfur poisoning regeneration can be avoided through estimating with high accuracy of the level of sulfur poisoning on the NOx occlusion reduction catalyst (22) and performing of sulfur poisoning regeneration at appropriate frequency, thereby preventing deterioration of mileage.