Development of a Dynamic Engine Brake Model for Control Purposes

This paper presents the extension of an existing mean value dynamic engine model with new models for the combination of a compression release brake and an exhaust valve brake. The focus is on the prediction of engine brake torque, exhaust gas temperatures and mass flow rates. The implemented models are tuned on the basis of steady-state engine data. Transient simulation results, i.e. for the activation of the engine brake, show good agreement with measurements. The developed model has been used to analyze the possibility to use the engine brake to facilitate automatic gear switching. This has been verified by measurements on an actual vehicle and resulted in much smoother and faster gear shift.