Cummins Inc.
Ammonia sensor control, with NO.sub.x feedback, of an SCR aftertreatment system

Abstract:

An exemplary method includes determining an NH.sub.3 reference target in an exhaust conduit between a first SCR catalyst and a second SCR catalyst. The method includes determining a present amount of NH.sub.3 in the exhaust conduit between the first SCR catalyst and the second SCR catalyst, and determining an NH.sub.3 error term in response to the NH.sub.3 reference target and the present amount of NH.sub.3. The method further includes determining an amount of NO.sub.x downstream of the second SCR catalyst, and adjusting one of the NH.sub.3 reference target and a reductant doser command in response to the amount of NO.sub.x downstream of the second SCR catalyst. The method further includes providing a reductant doser command in response to the NH.sub.3 error term.