An idle speed controller for reduced cyclic variability and fuel consumption

In this paper a proposed idle speed controller consisting of decoupled manifold pressure and spark retard control loops is presented. The controller incorporates a model predictive element in the selection of the bypass valve duty cycle, which is used to set the intake manifold pressure. A similar approach is easily adaptable to throttle by wire systems. A simulation model incorporating the cyclic variability of combustion generated torque is presented, and simulation results are provided that illustrate the effectiveness of the proposed control algorithm at not only handling cyclic variability but also potentially reducing the engine idle speed. This latter point ensures fuel economy of a given engine can be improved without adversely impinging on vehicle noise, vibration and harshness quality. Key-Words: Idle speed control, model predictive control, cyclic variability, fuel economy.