Angelo Palladino

A control oriented model of a Common-Rail System for Gasoline Direct Injection engine

Electronics has greatly contributed to the development of internal combustion engine. This progress has resulted in reducing environmental degradation, and yet continuing to support improvements in performance. Regarding gasoline engine, a considerable step forward has been achieved by Common Rail (CR) technology able to exactly regulate the injection pressure during whole engine speed range. As a consequence, the injection of a fixed amount of fuel is more precise and it is possible to perform multiple injections for combustion cycle. In this paper, the authors present a mean value model aimed at the control of a CR system for a Gasoline Direct Injection (GDI) engine. The model is based on the descriptions of electro-valve, including the actuator circuit, and the fuel pressure in the rail. The performances of the proposed model are finally depicted through comparisons with experimental data collected by a CR system mounted on a 2.0 liters spark ignition engine, showing a good accuracy and reliability.

Design and experimental validation of a model-based injection pressure controller in a common rail system for GDI engine

Progressive reductions in vehicle emission requirements have forced the automotive industry to invest in research and development of alternative control strategies. All control features and resources are permanently active in an electronic control unit, ensuring the best performance in terms of pollutant emissions and power density, as well as driveability and diagnostics. A way to attain these goals is the adoption of Gasoline Direct Injection (GDI) engine technology. In order to assist the engine management system design, through a better performance of GDI engine and the Common Rail (CR) system, in this work an injection pressure regulation to stabilize the fuel pressure in the CR fuel line is proposed and validated via experiments. The resulting control strategy is composed by a feedback integral action and a static model-based feed-forward action whose gains are scheduled as function of fundamental plant parameters. The tuning of the closed loop performance is then supported by an analysis of the phase margin and the sensitivity function. Preliminary experimental results confirm the effectiveness of the control algorithm in regulating the mean value rail pressure independently from engine working conditions, i.e. engine speed and time of injection, with limited design effort.

A model-based gain scheduling approach for controlling the common-rail system for GDI engines

The progressive reduction in vehicle emission requirements have forced the automotive industry to invest in research for developing alternative and more efficient control strategies. All control features and resources are permanently active in an electronic control unit (ECU), ensuring the best performance with respect to emissions, fuel economy, driveability and diagnostics, independently from engine working point. In this article, a considerable step forward has been achieved by the common-rail technology which has made possible to vary the injection pressure over the entire engine speed range. As a consequence, the injection of a fixed amount of fuel is more precise and multiple injections in a combustion cycle can be made. In this article, a novel gain scheduling pressure controller for gasoline direct injection (GDI) engine is designed to stabilise the mean fuel pressure into the rail and to track demanded pressure trajectories. By exploiting a simple control-oriented model describing the mean pressure dynamics in the rail, the control structure turns to be simple enough to be effectively implemented in commercial ECUs. Experimental results in a wide range of operating points confirm the effectiveness of the proposed control method to tame efficiently the mean value pressure dynamics of the plant showing a good accuracy and robustness with respect to unavoidable parameters uncertainties, unmodelled dynamics, and hidden coupling terms.

In cylinder air charge prediction for VVA system: Experimental validation

Automotive companies commonly adopt hardware-in-the-loop simulators to develop new control strategies in order to reduce the effort and the cost of the testing phase. This work aims at presenting a simple intake manifold air dynamics model, suited for HIL simulations, taking into account the nonlinear effects caused by VVA system during all its operating modes, i.e. full lift, early closure, late opening and multi lift. The performances of the proposed model are finally presented through comparisons with experimental data collected by a 1.4 liter Fiat SI engine, showing good reliability and excellent robustness.

Basic Concepts on GDI Systems

Gasoline Direct Engines offer many advantages as compared to PFI engines, as regard efficiency and specific power. To fully exploit this potential a particular attention must be paid to the in-cylinder formation process of air/fuel mixture. More demanding performance is required to the combustion system, since injectors must provide a fine fuel atomization in considerably short time, achieving a spray pattern able to interact with in-cylinder air motion and piston top surface. This is made possible through the Common Rail technology allowing an injection pressure one order of magnitude higher as compared with that of conventional PFI engines. Fuel economy can be obtained regulating load by mixture leaning, minimizing throttle usage at low loads where pumping losses are more significant, and requiring charge stratification for a stable ignition and combustion. Charge stratification can be pursued based mainly on the sole action of the fuel spray or on its interaction with a specially shaped surface on piston top or with the air bulk motion. Depending on the modality of stratification attainment, different combustion systems can be considered. The injector design has in turn a key role being the final element of fuel metering required to the desired spray pattern, injected fuel mass per injection event, resistance to thermal stress and deposits. Injector housing and orientation with respect to the combustion chamber has to be carefully chosen, exploiting in this regard the indications of computational fluid dynamics (CFD), provided by 3D simulations. Some fundamental scheme is provided for the whole high pressure fuel delivery plant, as employed in current vehicles equipped with GDI spark ignition engines.

Modelling of an internal combustion engine using power-oriented graphs and electrical analogy

In this paper, the power-oriented graphs (POG) technique is used for modelling an internal combustion engine through electrical analogy. The aim of the authors, starting from an analogy with electrical systems, is to simplify the approach eliminating the space dynamics, while preserving the time dynamics. In this way, one can obtain an engine description similar to an electric circuit, with all the useful consequences in terms of existence and numerical availability of the solution. The advantages are in the specific correspondence found between the engine components and variables with electrical counterparts. The main benefit achievable with this methodology is the simplicity to compose the whole engine model and customise it including the differential equations of the engine in state space form. The POG technique is a graphical modelling technique which uses only two basic blocks for modelling physical systems and the state space mathematical model of a system can be ‘directly’ obtained from the corresp...

Common Rail System for GDI Engines

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A modeling approach for engine dynamics based on electrical analogy

In this paper, a multi-cylinder, internal combustion engine model is presented. The paper is focused on a simple modular, physically based and lumped parameter (zero dimensional) approach, leading to a complete and coherent model structure. The model is conceived to be used with general purpose simulation software, as MATLAB/Simulink. The mean value outputs of the model (pressure, temperature, mass flow, torque) are compared with experimental data, collected by a Fiat 1.8 liter engine, in order to perform a standard identification and validation procedure.

Air Mass Flow Analysis for SI Engine: EGR and Scavenging

Abstract In order to lower the Nitrogen Oxides (NOx) concentration in internal combustion engine emissions and to improve performance, Exhaust Gas Recirculation (EGR) and Scavenging mechanism are introduced. EGR recirculates a fraction of the exhaust gas back into the cylinders, thus diluting the intake air. This lowers the maximum combustion temperature and, since the formation of NOx is heavily dependent on temperature, it results in a reduction of NOx concentration. Similarly, the Scavenging phenomenon is the air mass flowing from intake manifold directly to exhaust manifold, due to an overlap of intake and exhaust valves, without participating at the combustion. In this paper, the authors present a mean value engine model, aimed at the challenging purpose of the analysis of EGR and Scavenging. The model is based on an innovative approach for engine dynamics conceived mainly on the analogy with electric systems.

The POG technique for modelling engine dynamics based on electrical analogy

In this paper the Power-Oriented Graphs (POG) technique is used for modelling an internal combustion engine. The POG technique is focused on a new modular, physically based and lumped parameter approach, leading to a complete and coherent engine model structure. The aim of the authors, starting from an analogy with electrical systems, is to simplify the approach eliminating the space dynamics (multi-zone combustion and wave effects), while preserving the time dynamics. In this way, it is possible to obtain an engine description similar to an electrical circuit, with all the useful consequences in term of existence and numerical availability of the solution. The advantages are in the specific correspondence that is found between the engine components and variables (as throttle valve, cylinder, inertial flows) with electrical counterparts (current, voltage, resistance). The main benefit achievable with this methodology is the simplicity to compose the whole engine model and customize it including the differential equations of the engine in state space form, using the POG technique. The POG technique is a graphical modelling technique which uses only two basic blocks (the “elaboration” and “connection” blocks) for modelling physical systems. The state space mathematical model of a system can be “directly” obtained from the corresponding POG representation. The POG model of the considered combustion engine shows its internal structure from a “power” point of view