This paper presents the development of a model-based air/fuel ratio controller for a high performance engine that uses, in addition to other usual signals, the throttle angle to enable predictive air mass flow rate estimation.
The objective of the paper is to evaluate the possibility to achieve a finer air/fuel ratio control during transients that involve sudden variations in the physical conditions inside the intake manifold, due, for example, to fast throttle opening or closing actions. The air mass flow rate toward the engine cylinders undertakes strong variation in such transients, and its correct estimation becomes critical mainly because of the time lag between its evaluation and the instant when the air actually enters the cylinders.
The approach to research consists of the use of a fuel film dynamics model-based compensator and of an algorithm that estimates, before the intake stroke, the amount of air that will enter the cylinder, using the throttle position signal as a feed-forward information about the mean intake manifold pressure.
The conclusion will show the possibility to enable some improvement in the air-fuel ratio control; experimental tests on-board the vehicle are in progress.