Control of NOx storage catalyst rich regeneration using downstream lambda sensor, terminates process as function of lambda gradient

摘要

Termination of regeneration takes place at a time (ts) which is a function of the lambda value gradient. Preferred features: The instant of termination is determined from threshold values associated with the gradient of lambda value signal increase. These are a first threshold value (S1), a second value for variation of the gradient ( DELTA U), or first and second threshold values (S1, S2). On termination, the engine combustion air ratio is raised. Regeneration is stopped on presence of a desired quality signal up to the end point. It is stopped as a function of: combustion air ratio and/or exhaust gas mass flowrate and/or exhaust gas temperature and/or catalyst temperature and/or current lambda value ahead of NOx storage catalyst (22). Regeneration is not discontinued, should engine loading be removed during the process.