EXHAUST PURIFYING APPARATUS FOR INTERNAL COMBUSTION ENGINE

摘要

An exhaust purifying apparatus for an internal combustion engine includes a NOx removing catalyst, an oxidation catalyst, and a controller which is configured to calculate the amount of NOx contained in exhaust gas that has passed through the oxidation catalyst. The controller is configured to execute an abnormality diagnosis process that determines the existence of an abnormality in the NOx removing catalyst if NOx removal efficiency obtained from the amount of NOx is less than or equal to a predetermined value. The controller is configured to execute the abnormality diagnosis process after executing a desorption process that desorbs unburned fuel adsorbed by the NOx removing catalyst if an execution condition of the abnormality diagnosis process is met.

主权项

1. An exhaust purifying apparatus for an internal combustion engine, the exhaust purifying apparatus comprising:
a NOx removing catalyst, which is located in an exhaust passage and removes NOx in exhaust gas using urea water added to the exhaust gas; an oxidation catalyst, which is located at a part of the exhaust passage downstream of the NOx removing catalyst; and a processor, which is configured to:
calculate an amount of NOx contained in the exhaust gas that has passed through the oxidation catalyst;execute an abnormality diagnosis process that determines that there is an abnormality in the NOx removing catalyst if NOx removal efficiency obtained from the calculated amount of NOx is less than or equal to a predetermined value; andexecute the abnormality diagnosis process after executing a desorption process that desorbs unburned fuel adsorbed by the NOx removing catalyst if an execution condition previously set for performing the abnormality diagnosis process is met.