An aftertreatment system for internal combustion engines

An aftertreatment system 280 of an internal combustion engine which comprises a turbine 250 and an exhaust pipe 275 connected to a turbine outlet 255. The system comprises, in a sequence along the exhaust pipe, a lean NOx trap (LNT) 281 and a particulate filter (DPF) 282. An air/fuel ratio sensor 285 is upstream of the LNT and downstream of the turbine outlet to determine the air/fuel ratio during LNT regeneration (DeNOx). A NOx sensor 286 is downstream of the LNT or DPF. Provided are first means 283 for determining a turbine temperature, and second means 284 for determining a temperature downstream of the LNT during desulphation (DeSOx). At least one of the first and second means is a temperature sensor. A method of operating the LNT comprises evaluating a NOx storage amount as a function of NOx from the engine, and a measurement from the NOx sensor, evaluating NOx emissions as a function of the NOx storage amount, requesting DeNOx if emissions exceed a threshold, and the temperatures are each above respective thresholds, and controlling regeneration using air/fuel ratio values which are below a threshold.