Abstract: An after-treatment system includes a selective catalyst reduction on filter (SCRF) device in communication with exhaust gases from an engine yielding treated exhaust gases. A nitrogen oxides (NOx) sensor is configured to measure the treated exhaust gases and has an output signal that is NOx and ammonia (NH3) cross-sensitive. A NOx sensor model is coupled to receive the output signal and mass flow data for the treated exhaust gases and provides a NOx model signal to an electronic control unit (ECU) that is operatively associated with the after-treatment system and the engine. The NOx model signal represents an exhaust gas NOx concentration estimate based upon an actual NOx concentration and an actual NH3 concentration of the exhaust gas. The ECU is operable upon the NOx concentration estimate to control the after-treatment system and the engine to effect an overall reduction in actual NOx concentration of the treated exhaust gases.

Abstract: An exhaust gas after-treatment system for an internal combustion engine that includes a selective catalyst reduction on filter (SCRF) exhaust gas after-treatment device in communication with exhaust gases from the internal combustion engine and having a treated exhaust gas output. An oxides of nitrogen (NOx) sensor is coupled to the treated exhaust gases and has a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive. A closed loop observer (CLO) is operatively coupled to receive the NOx sensor output signal and provides a NOx concentration signal to an electronic control unit that is operatively associated with the exhaust gas after-treatment system and the internal combustion engine.

Abstract: An automotive vehicle includes an internal combustion engine and an exhaust system. The exhaust treatment system includes a dosing system that injects NH3 into an exhaust gas stream generated by the engine. An SCR device stores an amount of the NH3 and converts NOx into diatomic nitrogen (N2) and water (H2O) based on the stored amount of the NH3. The vehicle further includes an SCR status estimator device and a controller. The SCR status estimator device determines an NH3 coverage ratio (R), which indicates a stored amount of NH3 with respect to a maximum NH3 storage capacity of the SCR device. The controller determines a target NOx reduction efficiency (?NOx) of the SCR device, and an NH3 coverage ratio set point (Rsp) based on the ?NOx. The controller also generates an NH3 control signal (u) that controls the dosing system based on a comparison between the R and the Rsp.

Abstract: An automotive vehicle includes an internal combustion engine and an exhaust system. The exhaust treatment system includes a dosing system that injects NH3 into an exhaust gas stream generated by the engine. An SCR device stores an amount of the NH3 and converts NOx into diatomic nitrogen (N2) and water (H2O) based on the stored amount of the NH3. The vehicle further includes an SCR status estimator device and a controller. The SCR status estimator device determines an NH3 coverage ratio (R), which indicates a stored amount of NH3 with respect to a maximum NH3 storage capacity of the SCR device. The controller determines a target NOx reduction efficiency (?NOx) of the SCR device, and an NH3 coverage ratio set point (Rsp) based on the ?NOx. The controller also generates an NH3 control signal (u) that controls the dosing system based on a comparison between the R and the Rsp.