Method For Adapting The Characteristic Curve Of The Nitrogen Oxide Sensor In An Internal Combustion Engine

A method for adapting a characteristic curve of a first nitrogen oxide sensor of an internal combustion engine with exhaust gas recirculation, the first nitrogen oxide sensor arranged upstream of an SCR catalytic converter, a second nitrogen oxide sensor arranged downstream of the SCR catalytic converter, a particle filter arranged upstream of the SCR catalytic converter, and a urea injection device arranged upstream of the SCR catalytic converter, wherein the method comprises:

• determining that the particle filter is in a regeneration phase;
• increasing an exhaust gas recirculation rate during the regeneration phase of the particle filter;
• interrupting a supply of urea by the urea injection device during the regeneration phase of the particle filter;
• acquiring first nitrogen oxide values from first nitrogen oxide signals generated by the first nitrogen oxide sensor during the regeneration phase of the particle filter;
• determining that the first nitrogen oxide values are within a first nitrogen oxide interval;
• acquiring second nitrogen oxide values from second nitrogen oxide signals generated by the second nitrogen oxide sensor during the regeneration phase of the particle filter;
• determining that the second nitrogen oxide values are within a second nitrogen oxide interval;
• and
• adapting the characteristic curve of the first nitrogen oxide sensor based at least in part on the second nitrogen oxide values.

An exhaust section for an internal combustion engine with exhaust gas recirculation, comprising:

• an SCR catalytic converter;
• a particle filter arranged upstream of the SCR catalytic converter;
• a first nitrogen oxide sensor arranged upstream of the SCR catalytic converter and configured to generate a first nitrogen oxide signal that indicates a nitrogen oxide value upstream of the SCR catalytic converter;
• a urea injection device is arranged upstream of the SCR catalytic converter and configured to inject a predetermined quantity of urea;
• a second nitrogen oxide sensor arranged downstream of the SCR catalytic converter and configured to generate a second nitrogen oxide signal that indicates a nitrogen oxide value downstream of the SCR catalytic converter;
• an ammonia sensor arranged downstream of the SCR catalytic converter and configured to generate an ammonia signal that indicates an ammonia value downstream of the SCR catalytic converter;
• and
• a control unit configured designed to receive at least the first nitrogen oxide signal, the second nitrogen oxide signal, and the ammonia signal and based on inputs:
• determine that the particle filter is in a regeneration phase;
• increase an exhaust gas recirculation rate during the regeneration phase of the particle filter;
• interrupt a supply of urea by the urea injection device during the regeneration phase of the particle filter;
• acquire first nitrogen oxide values from first nitrogen oxide signals generated by the first nitrogen oxide sensor during the regeneration phase of the particle filter;
• determine that the first nitrogen oxide values are within a first nitrogen oxide interval;
• acquire second nitrogen oxide values from second nitrogen oxide signals generated by the second nitrogen oxide sensor during the regeneration phase of the particle filter;
• determine that the second nitrogen oxide values are within a second nitrogen oxide interval;
• and
• adapt a characteristic curve of the first nitrogen oxide sensor based at least in part on the second nitrogen oxide values.