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The objective of this paper is to present and to validate a numerical model of a single-cylinder pneumatic-combustion hybrid engine. The model presented in this paper contains 0-D sub-models for non-spatially distributed components: Engine cylinder, Air tank, wall heat losses. 1-D sub-models for spatially distributed components are applied on the compressive gas flows in pipes (intake, exhaust and charging). Each pipe is discretized, using the Two-Steps Lax-Wendroff scheme (LW2) including Davis T.V.D. The boundaries conditions used at pipe ends are Method Of Characteristics (MOC) based. In the specific case of a valve, an original intermediate volume MOC based boundary condition is used. The numerical results provided by the engine model are compared with the experimental data obtained from a single cylinder prototype hybrid engine on a test bench operating in 4-stroke pneumatic pump and 4 stroke pneumatic motor modes.

Data maps are easy to put in place and require very low calculation time. As a consequence they are often valued over fully physic-based models. This is particularly true when it is question of turbochargers. However, even if these maps are directly provided by the manufacturer, they usually do not cover the entire engine operating range and are poorly discretized. That's why before implementing them into any model they need to be interpolated and extrapolated. This paper introduces a new interpolation/extrapolation method based on the idea of integrating more physics into the widespread Jensen and Kristensen's method [6]. It essentially relies on the turbo machinery equation analysis performed by Martin during his PhD thesis [9, 10, 11] and the interpolation and extrapolation strategies that he proposed. In most cases the new strategies presented in this paper rely on improvements of the models he proposed.

Torque based engine control seems to be the trend for the future for powertrain management (automatic gearbox, hybrid vehicles). Today, torque estimation is best achieved using cylinder pressure transducers. This paper proposes a method to achieve a good accuracy of the torque using Bézier curves to reconstruct the cylinder pressure peak from the low frequency embedded pressure measurements. As is, IMEP cannot be used on a cycle to cycle basis for engine torque control, due to the very high cycle to cycle variability of SI engines. To improve the quality of the IMEP feedback data, this paper proposes a moving horizon filtering method.

To meet future pollutant emissions standards, it is crucial to be able to estimate the cycle by cycle composition of the combustion chamber charge. This charge consists of fresh air, fuel and residual gas from the previous cycle. Unfortunately, the residual gas fraction cannot be directly measured. Therefore, a model of residual gas fraction as a function of engine parameters and operating parameters has been developed. The model has been calibrated with exhaust pipe hydrocarbon measurements using a successive dilution method.

In the past few years, the increasing market penetration of downsized engines has reduced the pollutant emissions of internal combustion engines. The addition of a turbocharger to the air path has usually enabled the dynamic performances of the vehicles to be maintained. However, in the development process, deciding on the appropriate set of components is not straightforward and a lengthy fitting process is usually required to find the right turbocharger. Car manufacturers usually have access to a limited library of compressors and turbines which have actually been built and for which measurement campaigns have been carried out. This study is motivated by the need to extend the libraries available for simulation in order to provide a substantial increase in freedom in the matching process.

Nowadays, (engine) downsizing using turbocharging appears as a major way for reducing fuel consumption. With this aim in view, the air actuators (throttle, Turbo WasteGate) control is needed for an efficient engine torque control especially to reduce pumping losses and to increase efficiency. This work proposes Nonlinear Model Predictive Control (NMPC) of the air actuators for turbocharged SI engines where the predictions are achieved by a neural model. The results obtained from a test bench of a Smart MCC engine show the real time applicability of the proposed method based on on-line linearization and the good control performances (good tracking, no overshoot) for various engine speeds.

The optimization of fuel efficiency and the minimization of the residual gas fraction require individual cylinder control of the amounts of inducted air mass and injected fuel mass. Determination of an individual cylinder air/fuel ratio (AFR) regulator is based on the measured AFR for each cylinder, using 4 proportional UEGO sensors. The innovative character of this study describes a unified and robust individual cylinder AFR estimator, using a single measuring point: a proportional oxygen sensor located in the exhaust manifold. The model used for the estimator is a state model such that the dimension of the state and measurement matrices are unique, whatever the manifold configuration and the sensor position (confluence point or exhaust manifold: unified model), the engine speed (robust model).