TROUBLE DIAGNOSIS DEVICE FOR EXHAUST GAS PURIFICATION SYSTEM AND TROUBLE DIAGNOSIS METHOD FOR EXHAUST GAS PURIFICATION SYSTEM

摘要

There are provided a trouble diagnosis device and a trouble diagnosis method for an exhaust gas purification system in which the presence or absence of a trouble of the exhaust gas purification system such as abnormality of a control system for the exhaust gas purification system, catalyst deterioration or the like can be determined with high precision, and the reliability of the exhaust gas purification system can be enhanced.;The device includes upstream-side NO_x flow rate calculating means, downstream-side NO_x flow rate calculating means, reduction condition determining means for determining whether at least one condition for performing normal reduction of NO_x is satisfied, upstream-side NO_x flow amount calculating means for integrating the upstream-side NO_x flow amount to calculate the amount of NO_x passing through the upstream side of the catalyst within a predetermined time when the condition concerned is determined to be satisfied, downstream-side NO_x amount calculating means for integrating the downstream-side NO_x flow amount to calculate the amount of NO_x passing through the downstream side of the catalyst within a predetermined time when the condition concerned is determined to be satisfied, and trouble determining means for comparing the upstream-side NO_x amount and the downstream-side NO_x amount to determine whether the exhaust gas purification system operates normally.