| 摘要 |
PROBLEM TO BE SOLVED: To improve the accuracy of diagnosis by taking into consideration thermal deterioration between regeneration intervals, related to a diagnostic device.SOLUTION: A diagnostic device of an exhaust emission control system having a DOC (diesel oxidation catalyst), a DPF (diesel particulate filter) and an in-exhaust pipe injection device 23 comprises: a temperature sensor 25 which detects a temperature of the DOC; a first DOC deterioration degree calculation part 41 which converts an integrated time of a temperature inputted between regeneration intervals from the temperature sensor 25 into a thermal history time with respect to a prescribed set temperature, and calculates a degree of the deterioration of the DOC on the basis of the thermal history time; a second DOC deterioration degree calculation part 42 which calculates a calorific value in the DOC on the basis of the temperature which is inputted from the temperature sensor 25 during a forcible regeneration execution period, and calculates a degree of the deterioration of the DOC on the basis of the calorific value; and a DOC fault diagnostic part 43 which diagnoses a deterioration state of the DOC on the basis of the degree of the deterioration inputted from the DOC deterioration degree diagnostic parts 41, 42. |
