Patent ID: 8920758

Claim:
A method for operating an exhaust gas aftertreatment system with at least one first SCR device and at least one second SCR device and a single dosing device for reactant for the SCR devices disposed upstream of the first and second SCR devices in the exhaust gas flow direction, the method comprising: specifying a target overall efficiency η Des of the SCR devices, using modeling of the exhaust gas aftertreatment system, operate the SCR devices as a system by determining a target value ⊖ 1,Des depending on the target overall efficiency η Des , the target value ⊖ 1,Des representing the degree of charging of the first SCR device with reactant to charge both of the SCR devices, where the second SCR device is charged using the NH 3 slip past the first SCR device, and adjusting the dosing of the reactant to achieve the target value ⊖ 1,Des .