The model-based control system is attractive to install next-generation combustion technologies, such as HCCI (Homogeneous Charge Compression Ignition) and PCCI (Premixed Charge Compression Ignition) combustion with higher thermal efficiency and low emissions since their ignition and combustion are low robustness. It derives suitable control inputs to ensure the reference values during engine operation and has also potential to replace the conventional control map which requires a huge number of experiments. On the other hand, the model-based control for engines requires the reference values for combustion, such as heat rerelease timing and/or its heat rerelease value and the others, although the conventional control map basically determines the manipulation variables of actuators by control inputs. Then, the design of the reference values for combustion is discussed. The reference for a steady-state condition is probably enough, but the reference for the transient condition is important to utilize the benefit of the model-based control system considering fuel consumption, noise and emissions. In this study, for the advanced diesel combustion which uses compression-ignition and combustion with pre-mixture by multiple fuel injections, the design method of the reference values for combustion for the transient state condition with the engine speed and the injection quantity are changing simultaneously. Specifically, a statistical method using transient operation test results and a method based on model prediction were proposed and compared in engine experiments. The statistical method was developed based on the experiment results under simple acceleration operations and the model-based method considered the dynamics by the first-order delay. The combustion in this study has a characteristic that shows the two-stage heat release that can achieve both higher thermal efficiency and low combustion noise. So the reference values are evaluated to implement two-stage heat release properly. In addition, a base model for the model-based control to use the reference values by the proposed methods is our original control-oriented model developed before. As a result, the designed methods were evaluated at both defined simple transient conditions and WLTC mode considering real road conditions. The statistical method was able to set the best reference values that implement two-stage heat release at almost all transient conditions. But the method based on model prediction showed performance closer to that of the statistical method than using the reference map based on stationary test results. It is clarified that designing the reference values for combustion during transient operation by the model prediction is effective and such a method has the potential to reduce the process to determine the combustion reference of model-based control.


Study on Design Method of Combustion Reference Values for Model-Based Control of Advanced Diesel Engine

Division / Sponsors: 
Internal Combustion Engine Division (ICED)

Paper Proceedings: https://asmedigitalcollection.asme.org/ICEF/ICEF2020/volume/84034

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