Soot pre-loading of particulate matter aftertreatment devices as means for reducing hydrocarbon emissions during cold start

摘要

Methods and systems for reducing hydrocarbon emissions from an internal combustion engine. The engine's exhaust aftertreatment system has at least a particulate matter (soot) filter and means for actively regenerating the particulate matter filter. During operation of the engine, the soot loading state of the particulate matter filter is monitored. The filter is regenerated when required, but the regeneration is controlled so that the particulate matter filter retains a small level of soot loading. This soot “pre-loading” ensures hydrocarbon reduction during the next cold start.

主权项

1. A method of reducing the hydrocarbon content of exhaust from an engine, comprising:
providing an exhaust aftertreatment system having at least a particulate matter filter; providing a filter regenerator operable to actively regenerate the particulate matter filter; determining an amount of soot loadin of the s articulate matter filter that will result in a desired efficiency of hydrocarbon reduction during cold start engine conditions, thereby determining an amount of soot to be retained by the particulate matter filter after regeneration; storing maximum soot load data representing a maximum soot load level at which time the particulate matter filter is to be regenerated; storing pre-load soot level data representing the amount of soot to be retained by the particulate matter filter after regeneration; during operation of the engine performing the following tasks: receiving current soot load data representing the current soot loading state of the particulate matter filter; regenerating the particulate matter filter when the current soot load data indicates that the maximum soot load level has been reached; and ceasing the regenerating process when the particulate matter filter retains the pre-load soot level.