A Diesel Engine Model, including Compression Brake, for Powertrain Control
Paper i proceeding, 2002
A diesel engine model, designed for studying events
during automated gear shifting in a heavy duty truck is
presented. It will be used for developing and evaluating
powertrain control strategies. The deceleration in
engine speed to the new synchronous speed, during
an upshift, is of special intereset. The straightforward
approach is to cut fuel and wait for the engine to slow
down due to friction and pumping losses. In many
cases, this approach is too slow, and the engine compression
brake needs to be activated.
The engine model, assuming quasi-steady, bidirectional
thermodynamic flow with constant specific
heat capacities, is implemented using Modelica. A
simple model of the hydraulic circuit that governs the
activation of the compression brake mode is incorporated
in the model.
Problems related to the simulation of the engine brake
systems are discussed. They are handled by empirical
correction factors. Measurements from rapid engine
speed decelerations are used for verification.