Modelling and Fuzzy-Threshold Control of SI Engine for Emission Reduction during Cold Start Phase

We present a controllable model of an internal combustion engine that captures the overlapping of the cylinder valves as a controllable parameter and its effect on engine efficiency and EGR rates. The model parameters have been calibrated for the EF7 engine and validated with experimental data. This model successfully estimates the performance and HC and NOx emissions concentration of the engine under cold start operating condition. A model-based fuzzy-threshold control strategy has been proposed in cold start operating condition. This strategy uses the overlapping angle of the cylinder inlet and outlet valves as an extra degree of freedom in comparison to the regular PID strategy in order to accelerate the warm-up duration the catalyst converter while reduces the exhaust harmful emissions during the warm-up phase. The proposed controller model has been verified in MATLAB Simulink environment and simulation results indicates 8.6% reduction of the start-up time of the catalyst converter and reduction of 3.5%, 8.5% and 7% of HC, NO and fuel consumption respectively during the catalyst warm-up phase.