System, method, and apparatus for controlling an aftertreatment system having a particulate filter and a rich nox conversion device

A system, comprising:

• an internal combustion engine producing an exhaust gas flow;
• a particulate filter disposed in the exhaust gas flow;
• a NOx reduction catalyst disposed in the exhaust gas flow downstream of the particulate filter;
• a first oxygen sensor operationally coupled to the exhaust gas flow downstream of the NOx reduction catalyst;
• a second oxygen sensor operationally coupled to the exhaust gas flow between the particulate filter and the NOx reduction catalyst;
• and
• a controller comprising:
• an exhaust conditions module structured to interpret a first oxygen signal from the first oxygen sensor and a second oxygen signal from the second oxygen sensor;
• and
• a combustion control module structured to command a high engine-out air-fuel ratio in response to the first oxygen signal indicating a low oxygen content out of the NOx reduction catalyst and to command a low engine-out air-fuel ratio in response to the first oxygen signal indicating a high oxygen content out of the NOx reduction catalyst.

A method, comprising:

• determining an first oxygen content in an exhaust stream at a position downstream of a NOx reduction catalyst with a first oxygen sensor;
• determining a second oxygen content in the exhaust stream at a position downstream of a particulate filter and upstream of the NOx reduction catalyst with a second oxygen sensor;
• and
• operating an internal combustion engine in response to the first oxygen content and the second oxygen content, wherein the operating is performed to provide stoichiometric conditions for the second oxygen content and excess oxygen at the first oxygen content.