A thermodynamic Mean Value Model of the intake and exhaust system of a turbocharged engine for HiL/SiL applications.

Abstract

Nowadays requirements towards a reduction in fuel consumption and pollutant emissions of Internal Combustion Engines (ICE) keep on pushing Manufacturers to improve engines performance through the enhancement of existing subsystems (e.g., electronic fuel injection, VVT/VVA systems) and the introduction of specific devices (e.g., turbochargers, exhaust gas recirculation systems, after treatment components). Automotive engines have become very complex plants, and mathematical models are useful tools in the design of control systems. To define mathematical models for control oriented applications, an original library [1] has been developed in Simulink ® by the authors for the simulation of last generation automotive engines. Typical engine components and sub-systems are described through specific blocks that can be assembled to build up a whole engine model [2,3,4]. A “quasi-steady” (QS) approach was followed for non-volume components (as compressor, turbine, intercooler, EGR valve and cooler, etc.), while “filling-and-emptying” (F&E) techniques were used for volumes (e.g., intake and exhaust manifolds). Library blocks were then used to assembly a sub-model of the intake and exhaust system, fitted with a VGT turbocharger, intercooler, EGR circuit with cooler and throttle. The simulation procedure, which is based on a detailed physical modelling of the gas path, was then integrated in a HiL test bench from dSpace Gmbh at Magneti Marelli Powertrain facilities. After calibration and validation –with reference to a small Common Rail Diesel engine- it was widely used in SiL/HiL testing. In the paper the model is presented and several results obtained in the validation phase are reported, showing its capabilities to simulate the behaviour of the intake and exhaust system in “real-time” within HiL testing environments.