A previously developed piston damage and exhaust gas temperature models are
coupled to manage the combustion process and thereby increasing the overall
energy conversion efficiency. The proposed model-based control algorithm is
developed and validated in a software-in-the-loop simulation environment, and
then the controller is deployed in a rapid control prototyping device and tested
online at the test bench. In the first part of the article, the exhaust gas
temperature model is reversed and converted into a control function, which is
then implemented in a piston damage-based spark advance controller. In this way,
more aggressive calibrations are actuated to target a certain piston damage
speed and exhaust gas temperature at the turbine inlet. A more anticipated spark
advance results in a lower exhaust gas temperature, and such decrease is
converted into lowering the fuel enrichment with respect to the production
calibrations. Moreover, the pollutant emissions associated with production
calibrations and the implementation of the developed controller are compared
through a GT-Power combustion model.
Finally, the complete controller is validated for both the transient and
steady-state conditions, reproducing a real vehicle maneuver at the engine test
bench. The results demonstrate that the combination of an accurate estimation of
the damage induced by knock and the value of the exhaust gas temperature allows
to reduce the brake specific fuel consumption by up to 20%. Moreover, the
stoichiometric area of the engine operating field is extended by 20%, and the
GT-Power simulations show a maximum CO reduction of about 50%.
