Minimization of Fuel Consumption in Four Stroke Six Cylinder Engines Using Idle Speed Control

In a distressed economy with increasing cost of fuel, it is necessary to achieve control of automobile engine over transient behavior and meet performance objectives within the planned life of the vehicle. In this paper the objective is to design a model predictive controller (MPC) that will minimize fuel consumption in a four stroke cylinder engine using idle speed control. Engine speed is most often affected by unexpected disturbances, and the higher the engine speed at idle the higher the consumption of fuel. Non linear dynamic equations of an idle speed engine were obtained and later transformed to equivalent linear equation by linearization method. The designed MPC was integrated with a linearized equation of the plant. The MPC approach was used to forecast and control the four stroke six cylinder engine model in the presence of unexpected disturbance to achieve the desired objective. Simulations were performed in Matlab/Simulink and the results obtained showed that at different instances when disturbances entered the system, with MPC controller in the loop, the instability introduced by the disturbance was eliminated and the referenced idle speed tracked. There by maintaining the engine idle speed at 600 RPM.