Patent ID: 8001768
Filing Date: 2011-08-23
Classification: F01N,F02D,Y02T

Abstract:
1. A method for managing an exhaust gas feedstream from a spark-ignition, direct-fuel injection internal combustion engine to an exhaust aftertreatment system including a first converter element including a first lean-NOx reduction catalyst upstream of a second converter element, comprising: determining temperatures of the first lean-NOx reduction catalyst and the second converter element; operating the engine in a homogeneous charge combustion mode when the temperature of the first lean-NOx reduction catalyst is less than a first threshold; operating the engine in a stratified charge combustion mode when the temperature of the first lean-NOx reduction catalyst is within an allowable operating temperature range; selectively operating the engine in the stratified charge combustion mode and diverting flow of exhaust gas to the second converter element; selectively operating the engine in the homogeneous charge combustion mode to regenerate the first lean-NOx reduction catalyst; and, selectively operating the engine in the homogeneous charge combustion mode and selectively diverting the flow of exhaust gas to the second converter element.