Patent ID: 8534050

Claim:
An exhaust gas aftertreatment system for a diesel engine, comprising: a controller operably coupled to the diesel engine, the controller configured to induce the diesel engine to combust a lean air/fuel mixture during a first time interval so as to produce an output exhaust gas flow comprising a first concentration of a hydrocarbon (HC) and carbon monoxide (CO), and to combust a rich air/fuel mixture in at least one cylinder during a second time interval after the first time interval such that the output exhaust gas flow comprises a concentration of HC that is less than approximately about 1% greater than the first concentration of HC; a diesel oxidation catalyst coupled downstream of the diesel engine, the diesel oxidation catalyst receiving the exhaust gases from the diesel engine and oxidizing CO to obtain an exothermic reaction which increases a temperature of the exhaust gases flowing through the diesel oxidation catalyst to greater than a threshold temperature level; and an SCR catalyst coupled downstream of the diesel oxidation catalyst, the SCR catalyst receiving the exhaust gases greater than the threshold temperature level and reducing NO x in the exhaust gases, wherein the controller is also configured to induce the diesel engine to combust the lean air/fuel mixture during a third time interval following the second time interval.