| 摘要 |
The purpose of the present invention is to improve diagnostic accuracy by taking into account thermal degradation between regeneration intervals. Provided is a diagnostic device that is for an exhaust gas purification system and that comprises a DOC (21), a DPF (22), and an exhaust pipe injection device (23), wherein the diagnostic device comprises the following: a temperature sensor (25) for detecting the temperature of the DOC (21); a first DOC degradation degree calculation unit (41) for converting the integration time of the temperature inputted from the temperature sensor (25) between regeneration intervals into a thermal history time with respect to a predetermined set temperature, and also for calculating a degree of degradation of the DOC (21) on the basis of this thermal history time; a second DOC degradation degree calculation unit (42) for calculating the amount of heat generated in the DOC (21) on the basis of the temperature inputted from the temperature sensor (25) during a forced regeneration execution period, and also calculating a degree of degradation of the DOC (21) on the basis of this amount of heat generated; and a DOC failure diagnosis unit (43) for diagnosing a degradation state of the DOC (21) on the basis of the degrees of degradation inputted from the DOC degradation degree calculation units (41, 42). |
