Two-Stage Electro Thermal Supported HC (Hydro Carbon) Conversion

Many diesel engines have to work at load profiles which, due to the low exhaust gas temperatures, necessitate active regeneration procedures to ensure continued engine operation and the reliability of the particulate filter. An active regeneration may be initiated via inner engine measures such as late injection. However, due to high maintenance interval and run time requirements for non-road applications the combustion of soot accumulated in the diesel particulate filter (DPF) often is realized via downstream processes. Known methods for this purpose are burner systems, systems based on downstream hydrocarbon injection (HCI) and subsequent hydrocarbon (HC) -conversion due to a catalyst or a combination of both. This paper describes an autarkic system using two-stage electro-thermal supported hydrocarbon conversion. This system is capable to regenerate a DPF within the entire engine operating range and it is less complex than flame burner systems. Compared to the systems that work only with HC-dosing, the described system has the advantage that it is able to regenerate a DPF at low exhaust gas temperatures. It has the additional benefit that it can be used for thermal management of any exhaust aftertreatment system, ensuring early light off even under adverse engine operating conditions such as cold start and prolonged idling. The system is NO ₂ - neutral and does not need an additional operating fluid like a fuel borne catalyst.