Abstract
Keywords:
Heavy-Duty Diesel Engine, Brake Power, Gas Exchange Simulations, Numerical Design of Experiment
Abstract:
In the general trend of truck profitability enhancement, average truck speed plays an important role. It can be improved by increasing engine brake power, thanks to higher speed driving down the slopes. Truck engines are equipped with two specific brake features: an exhaust shutter to increase the surface of the low-pressure loop in the P-V diagram and an additional exhaust valve lift to increase the surface of the high-pressure loop. For this last feature, gas exchange simulation is commonly used to optimize the exhaust cam profile. This paper reports on the optimization of two additional exhaust valve lifts by the mean of a Numerical Design of Experiment on an 11-liter heavy-duty diesel engine. The outputs of the simulations (brake power, maximum in-cylinder pressure, exhaust temperature and pressure, Variable Geometry Turbine position) were modeled versus the cam profile parameters with neural networks. The models were then used to optimize the cam profile parameters to get the highest brake power at 2100 and 1500 rpm within mechanical limits. Special care was given to robustness of the optimum solution by taking into account variability in the Variable Turbocharger position or exhaust cam profile.