Fast estimation of combustion metrics in DI diesel engines for control-oriented applications

•Low-throughput semi-empirical models to estimate combustion metrics in diesel engines.•Low-throughput approach to set fuel injected quantities to a given torque target in engines.•Models implemented and validated under steady-state and transient conditions.•A low computational time of the order of 0.2–0.3 ms is required.•Brake mean effective pressure is accurately predicted (error of the order of 0.3 bar).

The present work has been focused on the development of low-throughput semi-empirical models to predict the peak firing pressure, indicated mean effective pressure and brake mean effective pressure in direct injection diesel engines. The models have been calibrated and assessed on a 1.6L GM Euro 6 diesel engine, on the basis of the results of experimental tests conducted at a dynamic test bench at GMPT-E (General Motors Powertrain-Europe). Model validation was carried out over “New European Driving Cycle” and “Worldwide Harmonized Light vehicle Test Procedure” missions. The performance of the semi-empirical models has been compared, in terms of prediction accuracy, robustness, inversion efficiency and computational expense, with that of a previously developed real-time physical combustion model. The thus developed semi-empirical models are characterized by a very low computational effort, and are therefore suitable for the development of innovative feed-forward control algorithms in the Engine Control Unit.