Method for evaluating an exhaust NOx sensor in the exhaust system of spark ignition internal combustion engine

A method for evaluating a sensor signal of an exhaust NOx sensor that is disposed downstream of a three-way catalytic converter in an exhaust system of a spark ignition internal combustion engine, the method comprising:

• modeling an ammonia factor downstream of the three-way catalytic converter using an ammonia formation model;
• modeling a nitrogen oxide emission in the exhaust system downstream of the three-way catalytic converter using a nitrogen oxide model;
• separating the modeled ammonia factor and the modeled nitrogen oxide emission by a separation algorithm using the sensor signal of the exhaust NOx sensor;
• and
• providing quantitative information, via the separation algorithm, about tailpipe ammonia emissions and tailpipe nitrogen oxide emissions of the spark ignition internal combustion engine;
• and
• adjusting control of the spark ignition internal combustion engine based on said tailpipe ammonia emissions,
• wherein the ammonia formation model takes into account a catalytic converter temperature and a combustion air ratio in the exhaust system downstream of the three-way catalytic converter.

A method for evaluating a sensor signal of an exhaust NOx sensor that is disposed downstream of a three-way catalytic converter in an exhaust system of a spark ignition internal combustion engine, the method comprising:

• modeling an ammonia factor downstream of the three-way catalytic converter using an ammonia formation model;
• modeling a nitrogen oxide emission in the exhaust system downstream of the three-way catalytic converter using a nitrogen oxide model;
• separating the modeled ammonia factor and the modeled nitrogen oxide emission by a separation algorithm using the sensor signal of the exhaust NOx sensor;
• providing quantitative information, via the separation algorithm, about tailpipe ammonia emissions and tailpipe nitrogen oxide emissions of the spark ignition internal combustion engine;
• and
• adjusting control of the spark ignition internal combustion engine based on said tailpipe ammonia emissions,
• wherein the nitrogen oxide model takes into account a catalytic converter temperature of the three-way catalytic converter and a combustion air ratio in the exhaust system downstream of the three-way catalytic converter and takes into account an exhaust gas volume flow of the internal combustion engine.

A method for evaluating a sensor signal of an exhaust NOx sensor that is disposed downstream of a three-way catalytic converter in an exhaust system of a spark ignition internal combustion engine, the method comprising:

• modeling an ammonia factor downstream of the three-way catalytic converter using an ammonia formation model;
• modeling a nitrogen oxide emission in the exhaust system downstream of the three-way catalytic converter using a nitrogen oxide model;
• separating the modeled ammonia factor and the modeled nitrogen oxide emission by a separation algorithm using the sensor signal of the exhaust NOx sensor;
• providing quantitative information, via the separation algorithm, about tailpipe ammonia emissions and tailpipe nitrogen oxide emissions of the spark ignition internal combustion engine;
• and
• adjusting control of the spark ignition internal combustion engine based on said tailpipe ammonia emissions,
• wherein the ammonia emission determined by the separation algorithm and the ammonia factor modeled by the ammonia formation model are filtered via a Kalman filter.

A method for evaluating a sensor signal of an exhaust NOx sensor that is disposed downstream of a three-way catalytic converter in an exhaust system of a spark ignition internal combustion engine, the method comprising:

• modeling an ammonia factor downstream of the three-way catalytic converter using an ammonia formation model;
• modeling a nitrogen oxide emission in the exhaust system downstream of the three-way catalytic converter using a nitrogen oxide model;
• separating the modeled ammonia factor and the modeled nitrogen oxide emission by a separation algorithm using the sensor signal of the exhaust NOx sensor;
• providing quantitative information, via the separation algorithm, about tailpipe ammonia emissions and tailpipe nitrogen oxide emissions of the spark ignition internal combustion engine;
• and
• adjusting control of the spark ignition internal combustion engine based on said tailpipe ammonia emissions,
• wherein the nitrogen oxide emissions determined by the separation algorithm and the nitrogen oxide emissions modeled by the nitrogen oxide model are filtered via a Kalman filter.

A method for evaluating a sensor signal of an exhaust NOx sensor that is disposed downstream of a three-way catalytic converter in an exhaust system of a spark ignition internal combustion engine, the method comprising:

• modeling an ammonia factor downstream of the three-way catalytic converter using an ammonia formation model, the ammonia factor determining a deflection of the sensor signal of the exhaust NOx sensor caused by ammonia;
• modeling a nitrogen oxide emission in the exhaust system downstream of the three-way catalytic converter using a nitrogen oxide model;
• separating the modeled ammonia factor and the modeled nitrogen oxide emission by a separation algorithm using the sensor signal of the exhaust NOx sensor:
• providing quantitative information, via the separation algorithm, about tailpipe ammonia emissions and tailpipe nitrogen oxide emissions of the spark ignition internal combustion engine;
• and
• adjusting control of the spark ignition internal combustion engine based on said tailpipe ammonia emissions,
• wherein the nitrogen oxide model takes into account an engine speed and/or an engine torque of the internal combustion engine.

A method for evaluating a sensor signal of an exhaust NOx sensor that is disposed downstream of a three-way catalytic converter in an exhaust system of a spark ignition internal combustion engine, the method comprising:

• modeling an ammonia factor downstream of the three-way catalytic converter using an ammonia formation model, the ammonia factor determining a deflection of the sensor signal of the exhaust NOx sensor caused by ammonia;
• modeling a nitrogen oxide emission in the exhaust system downstream of the three-way catalytic converter using a nitrogen oxide model;
• separating the modeled ammonia factor and the modeled nitrogen oxide emission by a separation algorithm using the sensor signal of the exhaust NOx sensor;
• providing quantitative information, via the separation algorithm, about tailpipe ammonia emissions and tailpipe nitrogen oxide emissions of the spark ignition internal combustion engine;
• and
• adjusting control of the spark ignition internal combustion engine based on said tailpipe ammonia emissions,
• wherein the nitrogen oxide model takes into account an ignition angle of the spark plugs of the internal combustion engine.