Modelling and Control of an Active Throttle for SI Engines

Abstract An active throttle is introduced in order to regain some of the losses encountered with conventional throttle valves on SI engines and to deliver supplemental electric energy. This throttle consists of an axial turbine connected with an electric generator. The turbine has variable stator blades. Additionally the system contains two conventional throttle valves in order to supply enough mass flow at the demanded pressure over the entire operating range of the engine. The control strategy for the various inputs of the system is described. In the European Test cycle the system can either improve the fuel efficiency by up to 5% or supply the battery with up to an additional 7 Ah.