Method of controlling a direct-injection gaseous-fuelled internal combustion engine system with a selective catalytic reduction converter

摘要

The disclosed method relates to controlling a direct-injection gaseous-fuelled internal combustion engine system to improve the conversion efficiency of an SCR converter that is operative to reduce levels of NOx. The method comprises detecting when said internal combustion engine is idling and timing the injection of a first quantity of fuel to begin injection when the engine's piston is near top dead centre; and controlling the temperature of exhaust gas to be above a predetermined temperature that is defined by an operating temperature range that achieves a desired conversion efficiency for said selective catalytic reduction converter, by: (a) timing injection of the gaseous fuel to begin after timing for injection said first quantity of fuel, and (b) increasing exhaust gas temperature by increasing a delay in timing for injecting the gaseous fuel, while limiting said delay to keep concentration of unburned fuel exiting said combustion chamber below a predetermined concentration.