Duty Cycle Operation as a Possibility to Enhance the Fuel Economy of an SI Engine at Part Load

The potential of Duty Cycle Operation (DCO) of a Spark Ignited (SI) engine on part load has been investigated. DCO keeps an engine running at full throttle in a stop and go mode to speed up a flywheel as a short time energy storage device. So the actual power demand is covered by the flywheel instead of the convenient direct power transfer from the engine. This work includes the calculation of the theoretical potential and preliminary results of a test setup.

The results show a clear advantage of fuel consumption at the engine's low power output. The potential of DCO has proved to be higher than that of variable intake valve timing.