Reduction of exhaust smoke emissions following extended diesel engine idling

摘要

A diesel engine equipped with an exhaust gas particulate filter includes a control system that reduces exhaust gas smoke emissions normally resulting from an extended period of engine idling. The control method periodically raises the exhaust gas temperature in order to purge the particulate filter of water and hydrocarbons that build up during extended engine idling and cause exhaust smoke. A timer records the elapsed period during which the engine remains at idle and the exhaust temperature is below a threshold level. When the recorded time period exceeds a preselected value, the filter is purged by elevating the exhaust gas temperature to a level sufficient to oxidize the gaseous hydrocarbons and evaporate any water that may have accumulated in the filter.