Diagnostic operation strategy for diesel oxidation catalyst aging level determination using NO_xsensor NO₂interference

摘要

A method of determining aging of a diesel oxidation catalyst (DOC) in an engine exhaust system includes receiving a first sensor signal from a first nitrogen oxides (NOx) sensor positioned in exhaust flow upstream of the DOC. The first sensor signal is indicative of an amount of NOx in the exhaust flow upstream of the DOC. The method further includes receiving a second sensor signal from a second NOx sensor positioned in the exhaust flow downstream of the DOC. The second sensor signal is indicative of an amount of NOx downstream of the DOC. A difference between the first sensor signal and the second sensor signal is calculated by a controller. A DOC aging level based on a predetermined correlation between the difference and DOC aging can then be determined by the controller if at least one predetermined operating condition is satisfied.

主权项

1. A method of determining aging of a diesel oxidation catalyst (DOC) in an engine exhaust system comprising:
receiving a first sensor signal from a first nitrogen oxides (NOx) sensor positioned in exhaust flow upstream of the DOC; wherein the first sensor signal is indicative of an amount of NOx in the exhaust flow upstream of the DOC; receiving a second sensor signal from a second NOx sensor positioned in the exhaust flow downstream of the DOC; wherein the second sensor signal is indicative of an amount of NOx in the exhaust flow downstream of the DOC; calculating via a controller a difference between the first sensor signal and the second sensor signal; determining via the controller whether at least one predetermined operating condition is satisfied; determining via the controller a DOC aging level based on a predetermined correlation between the calculated difference and DOC aging only if the predetermined operating condition is satisfied; determining a mass flow rate of NOx flowing past the first NOx sensor based at least partially on the first sensor signal; determining an amount of time over which a predetermined amount of NOx passes the first NOx sensor at the mass flow rate; periodically receiving additional sensor signals from the first and the second NOx sensors during the amount of time; and wherein said calculating the difference includes averaging differences between the first and the second sensor signals and the additional sensor signals periodically received during the amount of time.