EXHAUST EMISSION CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide technology enable to maintain bed temperature of a NOx catalyst in a temperature range enabling SOx poisoning elimination during SOx poisoning elimination treatment.

SOLUTION: A poisoning elimination treatment means executing SOx poisoning elimination treatment eliminating poisoning of an occlusion reduction type NOx catalyst by sulfur oxide stops execution of SOx poisoning elimination treatment (S119), raises temperature of exhaust gas flowing into a NOx catalyst and executes exhaust gas temperature/bed temperature maintaining treatment maintaining bed temperature of the NOx catalyst in the temperature range enabling elimination of poisoning (S120) when temperature of exhaust gas flowing into the NOx catalyst drops to a first predetermined temperature or lower during execution of Sox poisoning elimination treatment, and stops execution of exhaust gas temperature/bed temperature maintaining treatment (S122) and executes SOx poisoning elimination treatment again (S114) when temperature of exhaust gas flowing into the NOx catalyst rises to a second predetermined temperature which is higher than the first predetermined temperature, or higher by execution of exhaust gas temperature/bed temperature maintaining treatment.

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