METHOD OF CONTROLLING NOx BY PNA

摘要

Methods and systems are provided for reducing engine cold-start emissions. An exhaust system having a passive NOx adsorber (PNA) may store NOx during an engine cold-start until conditions are optimal for release of the stored NOx to a downstream SCR catalyst. Based on PNA conditions, including a NOx load and a PNA bed temperature, adjustments to EGR rate and/or injection timing may be made to achieve a catalytically favorable ratio of NOx species upstream of the SCR catalyst, after the SCR catalyst has reached its light-off temperature.

主权项

1. A method for an engine, comprising:
adjusting one of a fuel injection timing and an EGR rate responsive to loading of a passive NOx adsorber (PNA) to maintain a NOx species ratio upstream of an SCR catalyst in an exhaust after-treatment device.