Patent ID: 6378295
Filing Date: 2002-04-30
Classification: F01N,F02D,Y02T

Abstract:
A method of cleaning an exhaust gas of an internal combustion engine having a three-way catalytic converter disposed in an exhaust tract and a lambda probe disposed upstream of the three-way catalytic converter and exhibiting two-step action, which comprises:controlling operation of the internal combustion engine to fluctuate a lambda value of a raw exhaust gas at the lambda probe about a predetermined mean value; measuring, in a trimming controller, a concentration of an exhaust gas component downstream of the three-way catalytic converter with an amperometric measuring sensor made from a solid-state electrolyte and having a first measuring cell connected to a second measuring cell, a first electrode, a second electrode, an outer electrode, and a reference electrode exposed to ambient air; measuring, in the first measuring cell, an oxygen concentration through a first Nernst voltage between the first electrode and the reference electrode exposed to ambient air, and controlling, in the first measuring cell, the oxygen concentration by a first oxygen-ion pumping current between the first electrode and the outer electrode, and measuring, in the second measuring cell, the oxygen concentration through a second Nernst voltage between the second electrode and the reference electrode; tapping a voltage between the outer electrode and the reference electrode in conjunction with a series connection of the first and second measuring cells, and using the voltage as a signal, dependent on the oxygen concentration and indicating two-step action, for trimming control; and correcting predetermined mean values in dependence on the measured concentration of the exhaust gas component downstream of the three-way catalytic converter.