Process for diagnosis of a lambda probe associated with the exhaust gas catalytic converter of an internal combustion engine

摘要

In a process for diagnosis of a lambda probe ( 6 ) associated with the exhaust gas catalytic converter ( 3 ) of an internal combustion engine ( 1 ), it is proposed that for a known first and second exhaust gas mass flow {m₁, m₂} through the exhaust gas catalytic converter ( 3 ) it is measured how large the respective time delay (Deltat₁, Deltat₂) is until a sudden change of the lambda signal (lambda_a) upstream from the exhaust gas catalytic converter ( 3 ) appears for the lambda signal (lambda_b) of the lambda probe ( 6 ) associated with the exhaust gas catalytic converter ( 3 ), and that based on the measured time delays (Deltat₁, Deltat₂) it is determined how large the catalytic converter-induced portion (Deltat_cat1, Deltat_cat2) which is dependent on the exhaust gas mass flow ({m₁, m₂}) is and how large the probe-induced portion (Deltat_probe1, Deltat_probe2) of the time delays (Deltat_probe1, Deltat_probe2) which is essentially independent of the exhaust gas mass flow ({m₁, m₂}) is, the probe-induced portion (Deltat_probe1, Deltat_probe2) being used as a diagnosis criterion for the lambda probe ( 6 ). According to the invention an improved diagnosis process is made available by which the current dynamics of the lambda probe ( 6 ) associated with the exhaust gas catalytic converter ( 3 ) can be determined more accurately and therefore a more reliable diagnosis is possible.