Selective catalytic reduction dosing control

An exhaust system for treating exhaust gas emitted by an internal combustion engine, configured to perform a selective catalytic reduction (SCR) of exhaust gas, the exhaust system comprising:

• a controller configured to:
• compute a diagnostic adaptation factor for an SCR device of the exhaust system based on an on-board diagnostic signal;
• and
• input an amount of a reductant into the SCR device by configuring the exhaust system according to the diagnostic adaptation factor, wherein configuring the exhaust system comprises using the diagnostic adaptation factor as a target NH3 storage level of the SCR device;
• wherein computing the diagnostic adaptation factor comprises:
• determining a diagnostic factor based on the on-board diagnostic signal;
• comparing the diagnostic factor with a predetermined threshold;
• and
• in response to the diagnostic factor being greater than the predetermined threshold, computing the diagnostic adaptation factor as a maximum of the diagnostic factor and a predetermined long-term adaptation factor, and
• in response to the diagnostic factor not being greater than the predetermined threshold, computing the diagnostic adaptation factor as a minimum of the diagnostic factor and the predetermined long-term adaptation factor.

A computer-implemented method for controlling a selective catalytic reduction (SCR) device of an exhaust system of an internal combustion engine, the method comprising:

• computing a diagnostic adaptation factor for an SCR device of the exhaust system based on an on-board diagnostic signal;
• and
• inputting an amount of reductant into the SCR device by configuring the exhaust system according to the diagnostic adaptation factor, wherein configuring the exhaust system comprises using the diagnostic adaptation factor as a NH3 set-point of the SCR device;
• wherein computing the diagnostic adaptation factor further comprises:
• determining a diagnostic factor based on the on-board diagnostic signal;
• comparing the diagnostic factor with a predetermined threshold;
• and
• in response to the diagnostic factor being greater than the predetermined threshold, computing the diagnostic adaptation factor as a maximum of the diagnostic factor and a predetermined long-term adaptation factor, and
• in response to the diagnostic factor not being greater than the predetermined threshold, computing the diagnostic adaptation factor as a minimum of the diagnostic factor and the predetermined long-term adaptation factor.