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A major issue in the development of the future engines (diesel or gasoline) lies in the architecture and the control of the air intake system. In this context many setups are envisaged, and in particular the turbocharging systems are becoming more and more complex: variable geometry turbines, double stage turbochargers, variable geometry compressors… For these new architectures, the engine control strategies need to be modified in order to address the specific issues related either to the new system in itself or to its integration in the global engine. Renault and IFP have studied together, from a control point of view, the integration of a double stage turbocharger in a diesel engine. This paper presents the works undertaken during this study. The structure of the paper follows the different stages of the project.

Improving the simulation support in engine development projects is a very attractive way to reduce cost and duration of such projects while increasing the deliverable quality. Thanks to advanced models and specific know-how, this paper presents a new step which consists in the use of simulation as a virtual engine bench for control design when the real engine is not yet available. In a first part, the goals and requirements of such a simulation approach are described. Then, the specific case of a two-stage turbocharger Diesel engine application from an IFP-RENAULT control design study is presented. At first, the virtual bench design is detailed from a methodological point of view. The engine simulator development and its use as a virtual control bench are then described. The control strategies design is presented, but also the anticipation of potential limitations such as inadequate turbocharger behavior or system failure detection management.

In nowadays diesel engine, the turbocharger system plays a very important role in the engine functioning and any loss of the turbine efficiency can lead to driveability problems and the increment of emissions. In this paper, a VGT turbocharger fault detection system is proposed. The method is based on a physical model of the turbocharger and includes an estimation of the turbine efficiency by a nonlinear adaptive observer. A sensitivity analysis is provided in order to evaluate the impact of different sensors fault, (drift and bias), used to feed the observer, on the estimation of turbine efficiency error. By the means of this analysis a robust variable threshold is provided in order to reduce false detection alarm. Simulation results, based on co-simulation professional platform (AMEsim© and Simulink©), are provided to validate the strategy.

Torque balancing for diesel engines is important to eliminate generated vibrations and to correct injected quantity disparities between cylinders. The vibration phenomenon is important at low engine speed and at idling. To estimate torque production from each cylinders, the instantaneous engine speed from the crankshaft is used. Currently, an engine speed measurement every 45° crank angle is sufficient to estimate torque balance and to correct it in an adaptive manner by controlling the mass injected into each cylinder. The contribution of this article is to propose a new approach of estimation of the indicated torque of a DI engine based on a nonstationary linear model of the system. On this model, we design a linear observer to estimate the indicated torque produced by each cylinder. In order to test it, this model has been implemented on a HiL platform and tested on simulation and with experimental data.