Patent ID: 6276128
Filing Date: 2001-08-21
Classification: F01N,F02D,Y02T

Abstract:
A method for monitoring a conversion rate of an exhaust catalyst for an internal combustion engine having an electronic control device, comprising the steps of:a) cold starting the internal combustion engine;b) determining an exhaust-gas temperature value (TAB) prevailing upstream of the exhaust catalyst;c) detecting current temperature values (T.sub.vcat, T.sub.ncat) of exhaust gas present downstream and upstream of the exhaust catalyst with temperature sensors at least for a duration of a specific time window after the cold start, step c) including, in the control device for the beginning of the time window, c1) determining a catalyst temperature value (TKA), c2) correcting the exhaust-gas temperature value (TAB) with a catalyst temperature value (TKA) to form a temperature start value (TST), then in one step, c3) triggering a start signal (AS) of a starting point (tA) of the time window if the temperature start value (TST) has reached a given temperature threshold value (TSW);d) summating the temperature values (T.sub.ncat) currently present downstream of the exhaust catalyst at least during the time window to give a sum value (TT.sub.ncat);e) comparing the sum value (TT.sub.ncat) with a limit sum value (GT); andf) triggering an error signal if the comparing step shows that a specific deviation value (DHC) has been reached.