| abstract |
The present invention is a method for monitoring a LNT (Lean NOx Trap) catalyst, a reducing agent used for NOx regeneration in a rich mode operation of reducing NOx occluded in the LNT catalyst to nitrogen, and not used for NOx regeneration. It is to detect whether the LNT catalyst deteriorates through the ratio of the reducing agent slipped to the rear end of the.n n n The present invention is a process for detecting the signal of the first and second lambda sensor in the operation mode to reduce the NOx occluded in the LNT catalyst, the reducing agent slips without reacting with the amount of reducing agent consumed for NOx reduction in the signal of the first and second lambda sensor Detecting the amount, calculating the slip ratio of the reducing agent using the amount of the reducing agent and the amount of the reducing agent, and comparing the slip ratio of the calculated reducing agent with a threshold to diagnose whether the LNT catalyst is deteriorated. Include.n n n n LNT catalyst, reducing agent, rich mode, deterioration detection, slip ratio, lambda sensor |