Application of Fluid Dynamics Model to Estimate Cylinder Intake Volume

In a conventional fuel metering control system (speed density method) for an internal combustion engine, the fuel injection amount during transient operation is usually determined by using mapped data and various settings in a feedforward system predetermined through experimentation. However, this still does not necessarily represent the ideal level of compensation under a diverse range of environmental conditions. In order to satisfy various demanding requirements, such as reducing emissions, it is vital that the controllability of the air excess ratio(λ) be enhanced. The main technological obstacle that needs to be overcome is how best to determine accurately the required fuel amount from the engine in the feedforward system. To enable accurate prediction of the cylinder intake air volume, physical formulas of fluid dynamics were used to facilitate formulation of a model for the dynamic behavior of the intake air. In order to allow real-time calculation, an extremely simple yet highly accurate injection fuel amount calculation was used, in which certain elements are combined with the conventional speed density method. This enabled the controllability of λ to be dramatically enhanced. In addition, the number of transient fuel compensation items were substantially reduced.