A METHODOLOGY TO DETERMINE THE MASS FUEL INJECTED DURING A TRANSIENT PROCESS IN A HEAVY-DUTY ENGINE WITH EGR SYSTEM

摘要

The actual engines are controlled with an Electronic Control Unit (ECU). These ECUs dispose several maps to determine the mass fuel injected into the cylinders. Normally, the implemented maps at ECU are the result of a lot of tests over the engine in standard bench [1]. At this moment, in these tests, the EGR percentages are not taken into account to implement the injection maps. The objective of this article is to show a methodology to improve the injection maps during a load transient process in turbocharger engines with EGR during a load transient process. The soot emissions during a transient process could be avoided with the limitation of the 1/AFR (mass fuel/air in the cylinder) under a target value. This target value can be fixed or can be directly related to other parameters like function mode (crankshaft speed, intake pressure, %EGR, …). In this article, the relationship between AFR and the EGR percentage is taken into account to obtain the correct injected mass of fuel. This communication explains a methodology used in the Engine Department of the University Polytechnics of Valencia. In order to get an optimum fuel limitation map has been necessary to use both, result from the engine bench tests and result from a model named Wave Actions Model (WAM). This modelling program has been developed entirely at our Department. It has been employed and validated as an important tool in order to analyse many thermodynamics processes in internal combustion engines [2], [3], [4], [5] and [6].