Patent ID: 6301878
Filing Date: 2001-10-16
Classification: F02D,G01N,Y02T

Abstract:
A method for cleaning exhaust of an internal combustion engine having a catalyst and a lambda probe disposed in an exhaust gas tract, the lambda probe being disposed upstream from the catalyst, the lambda probe outputting a .lambda.o substantially close to lambda=1, the method comprising the steps of:determining a relationship between a downstream NOx concentration and a lambda value such that a lambda value substantially greater than 1 indicates a substantially greatly increased NOx concentration;determining a relationship between a downstream NH.sub.3 concentration and a lambda value such that a lambda value substantially less than 1 indicates a substantially greatly increased NH.sub.3 concentration;disposing an NOx measuring pickup having a cross-sensitivity to NH.sub.3 downstream from the catalyst;measuring a downstream NOx concentration with the pickup;measuring a downstream NH.sub.3 concentration with the pickup; andcorrecting .lambda.o based on a relationship between a lambda from the lambda probe and the downstream NOx concentration.