Strategies for Reducing NO _X - and Particulate Matter Emissions in Diesel Hybrid Electric Vehicles

In hybrid electric vehicles the combination of diesel engine and electric motor obviously provides lowest fuel consumption. However, compared with the Otto hybrid system, there are relatively high NO_x and particulate matter emissions. This paper describes investigations of various strategies for a significant reduction of exhaust gas emissions in diesel hybrid electric vehicles.

By reducing the dynamic operation of the combustion engine by supplementing the engine torque demand with an electric motor and limiting the maximum engine torque, the NO_x emissions could be reduced by more than 30% and the particulate matter emissions by more than 20%, without influencing the fuel consumption compared to hybrid electric vehicles with conventional operation strategy.