Patent ID: 6161428
Filing Date: 2000-12-19
Classification: F01N,F02D,Y02T

Abstract:
A method for checking an exhaust-gas catalytic converter for an internal combustion engine wherein an exhaust gas is generated having an oxygen content and said oxygen content having a mean value forward of said catalytic converter, the catalytic converter having an oxygen fill level which changes during operation of said engine, the method comprising the steps of:utilizing a rearward exhaust-gas probe to determine a value of the oxygen content of the exhaust gas rearward of said catalytic converter;in a first phase, changing the mean value of said oxygen content of the exhaust gas forward of said catalytic converter in a first direction which moves away from said value of said oxygen content determined rearward of said catalytic converter;determining the change of the oxygen fill level of said catalytic converter which results from the change of said mean value of said oxygen content andcontinuing said change of said oxygen fill level until:(a) said oxygen fill level exceeds a value (YO) which corresponds to an oxygen storage capacity of a catalytic converter which just still satisfies statutory requirements; or,(b) said rearward exhaust-gas probe reacts to the change of said oxygen fill level;causing a fault announcement to take place only when said rearward exhaust-gas probe reacts to said change of said oxygen fill level in said first phase; and,in a second phase, causing a further reaction of said rearward exhaust-gas probe to take place when there is a change of said mean value of said oxygen content forward of said catalytic converter in a second direction opposite to said first direction before said change of said oxygen fill level exceeds said value (YO).