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.