Method and arrangement for maintaining a diesel particulate filter in a diesel engine exhaust system

A diesel engine system, comprising:

• a diesel engine;
• a DPF downstream of the engine;
• a pressure sensor arrangement for measuring pressure drop across the DPF;
• and
• a control system comprising a recursive filter arranged so that, upon provision of an estimate of soot mass loading in the DPF and a measurement b the pressure sensor arrangement of pressure drop across the DPF, an updated estimate of soot mass loading in the DPF is provided, and so that active regeneration of the DPF is triggered in response to at least one triggering condition, the at least one triggering condition including the updated estimate of soot mass loading, the estimate of soot mass loading comprising a first component determined as a function of the measured pressure drop across the DPF and assuming uniform soot mass distribution and a second, modeled non-uniform soot mass distribution component determined as a function of soot reaction rate and exhaust gas flow velocity in the DPF,
• wherein the pressure sensor arrangement at least periodically measures the pressure drop across the DPF, and the control system is adapted to periodically update the updated estimate of soot mass loading in view of respective ones of the at least periodic pressure drop measurements to generate a plurality of updated estimates of soot mass loading and to periodically calculate a standard deviation of the plurality of updated estimates of soot mass loading, the control system being adapted to trigger regeneration when the updated estimate of soot mass loading plus the standard deviation, or a function of the estimated error, of the plurality of updated estimates of soot mass loading exceeds a predetermined value.