Breakdown diagnosing device for exhaust cleaning system, and breakdown diagnosing method for exhaust cleaning system

摘要

The present invention provides a failure diagnosis apparatus and a failure diagnosis method of an exhaust purification system that can accurately determine whether or not a failure of a control system of an exhaust purification system or a failure of an exhaust purification system such as catalyst deterioration is performed with high accuracy. to provide. ; An upstream NOx flow rate calculating means, a downstream NOx flow rate calculating means, a reducing condition determining means for determining whether or not at least one condition for reducing NOx is satisfied, and discriminating that the condition is satisfied The upstream side NOx flow rate calculation means for integrating the upstream side NOx flow rate, and calculating the amount of NOx that has passed through the catalyst upstream side within a predetermined time, and the downstream side NOx flow rate integrated when the condition is satisfied. Downstream NOx amount calculating means for calculating an amount of NOx that has passed through the catalyst downstream, and failure determining means for determining whether the exhaust purification system has been operated normally by comparing the upstream NOx amount and the downstream NOx amount. . ; Exhaust purification system, failure diagnosis device, upstream NOx flow rate calculation means, downstream NOx flow rate calculation means, reduction condition determination means, upstream side NOx amount calculation means, downstream NOx amount calculation means, failure determination means