Control apparatus and method for operating an internal combustion engine

A controller for a vehicle internal combustion engine exhaust gas after-treatment system, the internal combustion engine having a diesel exhaust fluid (DEF) system and a selective catalyst reduction filter (SCRF), the exhaust gas treatment system including a 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 coupled to the treated exhaust gas output, the NOx sensor having a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive, and an electronic control unit (ECU) operatively coupled to the internal combustion engine and the exhaust gas after-treatment system, the controller comprising:

• a closed loop observer (CLO) operatively coupled to receive the NOx sensor output signal and to provide a CLO output signal to the ECU, the ECU comprising a first controller having a first microprocessor, the first microprocessor comprising a first program stored therein, the CLO comprising a second controller having a second microprocessor, the second microprocessor comprising a second program stored therein wherein the CLO output signal at least includes an exhaust gas NOx concentration estimate and the ECU is programmed to provide the SCRF exhaust gas after-treatment device a DEF injection signal for the DEF system to inject a measured quantity of DEF into the exhaust gases upstream the SCRF to effect an overall reduction in actual NOx concentration with the exhaust gases, wherein the CLO output signal at least includes an NH3 storage estimate of the SCRF when an NH3 slip evident condition is verified and when a linearized model is coherent with the NH3 slip evident condition.

A method of controlling a vehicle internal combustion engine exhaust gas after-treatment system, the internal combustion engine having a diesel exhaust fluid (DEF) system and a selective catalyst reduction filter (SCRF), the exhaust gas treatment system including a 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 coupled to the treated exhaust gas output, the NOx sensor having a NOx sensor output signal that is NOx and ammonia (NH3) cross-sensitive, and an electronic control unit (ECU) operatively coupled to the internal combustion engine and the exhaust gas after-treatment system, the method comprising:

• providing via a closed loop observer (CLO) operatively coupled to receive the NOx sensor output signal an exhaust gas NOx concentration estimate to the ECU, the ECU comprising a first controller having a first microprocessor, the first microprocessor comprising a first program stored therein, the CLO comprising a second controller having a second microprocessor, the second microprocessor comprising a second program stored therein, the ECU being programmed to provide the SCRF exhaust gas after-treatment device a DEF injection signal for the DEF system to inject a measured quantity of DEF into the exhaust gases upstream the SCRF;
• and
• injecting the measured quantity of DEF into the exhaust gases upstream the SCRF to effect an overall reduction in actual NOx concentration with the exhaust gases responsive to the NOx concentration estimate, wherein the CLO output signal at least includes an NH3 storage estimate of the SCRF when an NH3 slip evident condition is verified and when a linearized model is coherent with the NH3 slip evident condition.