Abstract:
Mixture strength control system effectiveness depends on
its capacity to deal with air and fuel transport processes inside
the intake manifold: the prediction of air mass flow to the
engine cylinders and the compensation for the fuel lag during
engine transients. These issues are all likely to be of extreme
importance with the transient air/fuel ratio control strategies.
This paper introduces an innovative model-based air/fuel
ratio control strategy for SI engines. It is based on a previously
published modeling approach for the air dynamics inside intake
manifolds, which is based on the formulation of the mass,
momentum and energy conservation equations and named as
Method Of Interconnected Capacities. The proposed strategy
uses a fuel compensator that is based on a macroscopical
modeling of the fuel film dynamical behavior inside the intake
manifold, which is derived from the Aquino model.
A wide range of severe transient tests obtained from the
experimentation of a single-cylinder research engine (type AVL
5401), equipped with port-fuel injection system, is presented.
The results obtained have proved the effectiveness of the
proposed strategy in controlling the air/fuel ratio in SI engines
in a better way compared to the traditional control systems.