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Considerable efforts have been made in the automotive industry on powertrains in order to minimize the energy required by passenger cars. This can be done by improving factors such as the technologies used and the way the energy is used.Losses can be recovered from thermal irreversible power sources. The lost energy contained in the exhaust gases and the coolant can be recovered using two Rankine Machines. As Rankine Cycles work better on a stabilized operating point, a Series Hybrid Electric Vehicle (SHEV) would appear to have a great potential for this technology. The two Rankine machines can be chained: the high temperature machine recovers the lost exhaust gases energy, while the low temperature machine recovers both the lost energy coming from the coolant plus the energy coming from the low temperature side of the previous machine.

Pollutant emissions are a major issue from all existing internal combustion engines, especially from Diesel engines, with nitrogen oxides (NOx) and particulate matter (PM) receiving particular attention. Simultaneous reduction of NOx and PM often presents a challenge to Diesel engine researchers because of the inherent trade-off between them due to their contradictory responses to oxygen content in a fuel. The use of liquid or gaseous biofuels in internal combustion engines, benefits in the reduction of life-cycle CO2 emissions, but suffers from unfavorable NOx/PM emissions trade-off. Hence, it is essential to moderate NOx/PM emissions trade-off in order to effectively use the Rapeseed Methyl Ester (RME) fuel as an alternative to the fossil Diesel fuel in Diesel engines.

The paper presents a comparative study of various models used to estimate gas dynamics in internal combustion engine (ICE) ducts. 1D models provide a sufficient accuracy, but they are still not implementable on current ECUs. On the other hand, low order models can be real-time but their lack of accuracy and high calibration cost are still a challenging problem. This work aims at presenting a comparison of currently used gas dynamics models to predict transient phenomena in engine ducts. It emphasizes on 1D and low order models. To test under engine-like conditions, the intake path of a virtual engine implemented in GT-Power and a production two cylinder engine are used. Results show a contrast in the performance of the different models, which gives the possibility to evaluate the various approaches. Based on this assessment and depending on the application in hand, the models can be chosen properly to estimate the gas dynamics in internal combustion engine ducts.

Compressor models play a major role as they define the boost pressure in the intake manifold. These models have to be suitable for real-time applications such as control and diagnosis and for that, they need to be both accurate and computationally inexpensive. However, the models available in the literature usually fulfill only one of these two competing requirements. On the one hand, physics-based models are often too complex to be evaluated on line. On the other hand, data-based models generally suffer insufficient extrapolation features. To combine the merits of these two types of models, this work presents an extended approach to compressor modeling with respect to thermo- and aerodynamic losses. In particular, the model developed by Martin et al. [1] is augmented to explicitly incorporate friction, incidence and heat transfer losses. The resulting model surpasses the extrapolation properties of data-based models and facilitates the generation of extended lookup tables.

Several works have previously shown that the concept of pneumatic-combustion hybrid engine is an interesting alternative to the Electric Hybrid Vehicle, by leading to equivalent fuel savings for a probable lower cost. However, these studies have shown that the thermal insulation of the tank is a problem. Indeed, due to its size and its location, the adiabaticity of the pneumatic tank cannot be guaranteed. During a regenerative braking (pneumatic pump mode) the hot and pressurized air that is send to the tank cools, pressure drops and density increases. When reusing the air in pneumatic motor mode, the mass necessary to fill the cylinder is greater than the one that would have been necessary if the air was not cool at its stay in the tank. This phenomenon is the major cause to the quite low regenerative efficiency that has been observed on a prototype engine.

In Hybrid Electric Vehicles (HEV), the electrical hybridization offers different ways to reduce the fuel consumption: kinetic energy recuperation during vehicle deceleration, possibility of stopping the engine, and intelligent Energy Management System (EMS). Besides, with the future more stringent standards, there is a need to integrate the pollutant emissions in the EMS, since strictly reducing the fuel consumption can increase the emissions. The paper presents an optimal energy management strategy with constraints on pollutant emissions for gasoline-HEV, taking into account the 3-Way Catalyst Converter (3WCC). Based on a complete model of the powertrain, a mixed fuel consumption / pollutant emissions performance index is minimized with the Pontryaguin Minimum Principle (PMP) and two states, the battery State Of Charge and the 3WCC temperature.

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.

The amount of fresh air induced into the cylinder is the main parameter to be taken into account when developing the engine control laws. However, the instantaneous amount of induced air cannot be directly measured. Additionally, as the engine air ducting becomes more and more complex (high and low pressure exhaust gas recirculation, variable valve timing, pneumatic hybridization…), models used to develop engine control laws must be as predictive as possible. It has therefore been decided to use 1d aerodynamics simulation to provide accuracy to the control laws development and validation process. Commercial engine codes have been tested but did not give satisfactory results in terms of calculation time and flexibility. Additionally, in the case where no experimental data are available to determine valve discharge coefficient, simulation results were in total disagreement with the engine bench measurements.

Nowadays, numerical modeling/simulation is an essential tool. It is used in all the design stages in order to improve quality and to reduce costs and time-to-market. As models address increasingly multiphysics and complex phenomena throughout the V-cycle process, modelers are confronted, sooner or later, with the need for model reduction. This paper describes the set-up of a virtual prototyping platform and highlights the interest of integrating energetic aspects, which are used to compute new model reduction criteria. A similar energy approach, “MORA” using “Activity”, is already used by Bond Graphists in order to obtain the “Proper Model” ([7] and [8]). The methodology presented here (PEMRA: “Power & Energy -based Model Reduction Algorithm”), with new power and energy criteria, makes it possible to obtain a simpler and more accurate reduced model than with MORA methodology, while improving the system's energy information.

Model-based tuning is a way followed by car manufacturers to reduce development costs. In this context, a new methodology has been developed in order to adapt a tur-bocharged diesel engine in the case of non-standard external conditions. Indeed, variable geometry turbine and fuel injection command laws are developed for standard conditions (20°C, altitude=0m). Turbocharger and fuel injection actuators pre-positioning maps should be adjusted regarding the inducted air mass density (influenced by the external temperature and pressure), in order to meet thermal, mechanical and pollutant emissions constraints. In order to reduce the use of climatic tests bench and extreme conditions tests in foreign countries, a model of a turbocharged diesel engine coupled to an optimization loop has been used to take into account the effect of non-standard external conditions on pre-positioning maps.

A convenient way of modelling turbochargers is based on data maps. These models are easy to put into place, require low CPU charge and are control-oriented. Data relative to compressor and turbine are read from tables: pressure ratio and efficiency are determined as functions of mass flow rate and rotary speed on two distinct data maps. Nevertheless, this type of model has drawbacks: Usually, only higher turbocharger speed data are mapped (> 90000 rpm) although the low rpm zone is the most useful zone for normalized driving cycles simulations. Moreover, maps are poorly discretized, leading to the use of specific extra-interpolation methods (many are identified in [5]). These methods are purely mathematical, which gives inaccurate results in extrapolation zones. Relation between pressure ratio and efficiency is then broken (i.e., if one implements a pumping model for the compressor, the pressure ratio will be affected, but not the efficiency).

This paper presents energy management strategies for a new hybrid pneumatic engine concept, which is specific by its configuration: It is not a vehicle but only an engine itself which is hybridized. This arrangement could provide as much as 30% of fuel saving depending on the driving cycle. Therefore different energy management strategies are proposed and compared in this paper. The first of them is called Causal Strategy and implements a rule-based control technique. A second strategy called Constant Penalty Coefficient is based on minimization of equivalent consumption, where the use of each energy source is formulated in a comparative unit. The balance between consumption of different energy source (chemical or pneumatic) is reached by introduction of an equivalence factor. The third strategy is called Variable Penalty Coefficient, where the equivalence factor is consider as variable within the amount of pneumatic energy stored in the air-tank.

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.

Recrystallized Silicon carbide (R-SiC) honeycombs have been widely used over the last couple of years as filtration media for diesel particulates filtration in passenger cars applications. Although such filters are very reliable thanks to SiC good properties and smart designs, existing devices can still be improved. This paper describes several new features developed for R-SiC honeycomb filters in order to increase their durability and reduce their cost. Durability improvements can be obtained through the optimization of different filter properties such as thermo-mechanical resistance and thermal diffusivity. Specific tests have been performed in order to optimize new R-SiC filters.

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.

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.

In the last decade, the drastic strengthening of engine emission regulations has conducted the automotive industry towards more and more sophisticated engine control strategies requiring more and more sensor inputs and actuator outputs. The testing and setting up of the ECUs implementing such strategies becomes more and more difficult, requiring numerous engine tests on test benches. ECUTEST is a hardware and software package from KADRA CONSULTANTS that offers the following features: Simulation of sensors including variable reluctance sensor, lambda sensor, knock sensor… Measurement of output signals (injection, ignition, EGR…) timing and amplitude. A predefined test pattern can be replayed on the ECU to perform end of line testing. A real-time model can be used for testing and setting up embedded closed loop strategies. The present paper will cover the implementation of a real-time SI engine model on ECUTEST.

One way of improving electronic engine control is to get an insight into the combustion process, using a direct measurement method: this means the sensor must be put straight into the combustion chamber. The reference for analyzing combustion development is the cylinder pressure sensor. Due to the price of this sensor and the added complexity for cylinder head design and manufacturing, cylinder pressure sensors are not conceivable today for mass production. An alternative to the cylinder pressure sensor is the ionization sensor. It seems to be very promising for electronic engine control. Several publications have already demonstrated the benefits of ionization currents sensing for misfire detection, knock detection, closed loop ignition control, air-fuel ratio estimation. On the contrary, other publications have shown severe limitations of the ionization sensor. For example, fuel composition or additives can influence the ionization current.