Minimizing fuel consumption is emerging as the next major challenge for engine control and calibration, even as the requirements of complying with ever lower transient emissions regulations cannot be underestimated. Meeting these difficult and apparently conflicting emissions and efficiency goals is becoming increasingly onerous as engine and aftertreatment control complexity increases. Conventional engine calibration techniques are by nature time-intensive, ad-hoc and repetitive, resulting in low productivity of test facilities and engineering effort. Steady state engine mapping methods, such as design of experiments, do little to ensure transient emissions compliance or fuel consumption optimization.
A new model-based Rapid Transient Calibration system has been developed, tested and validated using a 2007 production-specification Detroit Diesel Series 60 heavy-duty diesel engine. This system has demonstrated a significant reduction in the time required to calibrate compared to conventional calibration methods by moving an appreciable proportion of the engineering effort from the physical transient dynamometer test cell to the virtual, computational desktop environment, thus offering significant reductions in product development costs and schedules. Significant improvements in actual fuel consumption were shown at the same or lower overall integrated emissions levels in real-world validation testing, proving that this new process offers considerable advantages over conventional calibration methods.
This paper details the first complete beginning-to-end validation of this rapid transient calibration optimization process. The calibration process commences with a limited data collection campaign in a transient emissions test cell and is then transferred to the computational environment where high-fidelity dynamically predictive engine emissions and performance models are created.
The engine calibration is then optimized off-line using these transient models in conjunction with a set of optimization and constraint functions. To prove the accuracy of the method, a number of engine calibration data sets, each optimized for a different emissions target, are then validated on the engine back in the transient emissions test cell.