Veniero Giglio

Modeling of an Electromechanical Engine Valve Actuator Based on a Hybrid Analytical--FEM Approach

The use of an electromechanical valve actuator (EMVA) formed by two magnets and two balanced springs is a promising tool to implement innovative engine management strategies. This actuator needs to be properly controlled to reduce impact velocities during engine valve operations, but the use of a position sensor for each valve is not possible for cost reasons. It is therefore essential to find sensorless solutions based on increasingly predictive models of such a mechatronic actuator. To address this task, in this paper, we present an in-depth lumped parameter model of an EMVA based on a hybrid analytical-finite-element method (FEM) approach. The idea is to develop a model of EMVA embedding the well-known predictive behavior of FEM models. All FEM data are then fitted to a smooth curve that renders unknown magnetic quantities in analytical form. In this regard, we select a single-wise function that is able to describe global magnetic quantities as the flux linkage and force both for linear and saturation working regions of the materials. The model intrinsically describes all mutual effects between two magnets. The goodness of the dynamic behavior of the model is finally tested on a series of transient FEM simulations of the actuator in different working conditions.

Robust Discrete-Time MRAC With Minimal Controller Synthesis of an Electronic Throttle Body

The electronic throttle body (ETB) is a fundamental actuator for regulating the air mass coming into an internal combustion engine; hence, it is used to control the engine torque in any modern drive-by-wire configuration. To cope with the nonlinear and discontinuous dynamics of this automotive device, in this paper a novel discrete-time model reference adaptive control (MRAC) method is designed and experimentally tested on an ETB installed on a 2-L engine. The control strategy extends the class of the minimal control synthesis (MCS) algorithms for discrete-time systems by adding an explicit discrete-time adaptive integral action and an adaptive robust term. An in-depth experimental investigation shows that the proposed control method is a viable solution as it is robust with respect to nonlinear torques acting on the plant, and it guarantees better performance than those provided by other MRAC strategies especially for small reference signals around the limp-home position where plant nonlinearities strongly affect the ETB dynamics.

Analysis of Advantages and of Problems of Electromechanical Valve Actuators

The electromechanical devices proposed in technical literature are very flexible. However, their working principle (fixed lift, fixed lifting time and variable valve events) imposes the use of different strategies, such as cylinder or port deactivation to enable work at partial loads. This happens in particular at low loads. The present paper aims to evaluate the effect of the design and of the strategies adopted to vary the load (cylinder or port deactivation etc) on performance and on pollutant formation of a stoichiometric DISI engine. The calculations were performed by a commercial onedimensional code (Wave produced by Ricardo). This tool was also used to give inputs to the design of the electromechanical actuator. The electromechanical design of the actuator was carried out with the aid of the code Flux2D produced by Cedrat. This code allows the complete simulation of transients and of the electrical losses of the actuator. The system requirements of performing the first lift at engine start up and catching in normal operation were analyzed. In this way a fairly realistic picture of the main advantages and of the typical problems of Electromechanical Valve Actuators was outlined.

An MRAC Approach for Tracking and Ripple Attenuation of the Common Rail Pressure for GDI Engines

Abstract Gasoline Direct Injection (GDI) spark ignition engines equipped with the Common Rail (CR) system strongly improve engine performance in terms of fuel consumption and pollutant emission reduction. As a drawback the fuel pressure in the rail has to be kept as constant as possible to the demanded pressure working set-points in order to achieve the advantages promised by this technology. In this work a Model Reference Adaptive Control (MRAC) algorithm based on the Minimal Control Synthesis (MCS) strategy is proposed to reduce the residual pressure in the rail. Numerical results based on a CR mean value model, previously proposed in the literature and experimentally validated, show that a very satisfactory attenuation of the pressure ripple as well as pressure tracking are attained in different working conditions. A quantitative comparison with a classical gain scheduling model-based control approach confirms furthermore the effectiveness of the proposed adaptive control strategy.

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.

Model-Based Control of the Air Fuel Ratio for Gasoline Direct Injection Engines via Advanced Co-Simulation: An Approach to Reduce the Development Cycle of Engine Control Systems

Nowadays, the precise control of the air fuel ratio (AFR) in spark ignition (SI) engines plays a crucial role in meeting the more and more restrictive standard emissions for the passenger cars and the fuel economy required by the automotive market as well. To attain this demanding goal, the development of an advanced AFR control strategy embedding highly predictive models becomes mandatory for the next generation of electronic control unit (ECU). Conversely, the adoption of more complex control strategies affects the development time of the ECU increasing the time-to-market of new engine models. In this paper to solve the AFR control problem for gasoline direct injection (GDI) and to speed up the design of the entire control system, a gain scheduling PI model-based control strategy is proposed. To this aim, AFR dynamics are modeled via a first order time delay system whose parameters vary strongly with the fresh air mass entering the cylinders. Nonlinear relations have been found to describe the behavior of model parameters in function of air mass. Closed loop performances, when this novel controller is nested in the control loop, are compared to those provided by the classical PI Ziegler–Nichols control action with respect to different cost functions. Model validation as well as the effectiveness of the control design are carried out by means of ECU-1D engine co-simulation environment for a wide range of engine working conditions. The combination in one integrated designing environment of control systems and virtual engine, simulated through high predictive commercial one dimensional code, becomes a high predictive tool for automotive control engineers and enables fast prototyping.

Downsizing of SI Engines by Turbo-Charging

During most of the operating conditions occurring on a vehicle driving cycle, a reciprocating IC engine works at low load and low speed, with poor fuel efficiency. In this regard downsizing appears as a major way of improving fuel consumption of Spark Ignition Engines. In fact, downsized engines have smaller friction surfaces and can work on the same vehicle and on the same driving cycle with higher mean effective pressure and higher efficiency. In this paper the main technical trends and problems related to SI engine downsizing are reviewed and discussed. Assuming a stoichiometric boosting, a simulation code is used to outline a strategy to improve low end torque of a downsized DISI engine. In the numerical experiments volumetric efficiency is enhanced by an optimal configuration of the inlet system. For the same objective, assuming a Variable Valve Timing, a proper selection of maximum lift and opening duration of the inlet valve allows a reduction of the reverse flow of fresh mixture. The optimization of the exhaust system and of the lift diagram of the exhaust valve leads both to the enhancement of volumetric efficiency and to the reduction of residual exhaust gas, with beneficial effects on knock phenomenon. An evaluation of fuel consumption gains resulting from downsizing is made as well, with reference to a New European Driving Cycle.Copyright

Adaptive Tracking Control of a Common Rail Injection System for Gasoline Engines: A Discrete-Time Integral Minimal Control Synthesis Approach

Over the last decade, gasoline direct injection engines have proven to be a promising solution to reduce both emission and fuel consumption. The achievement of superior performance strongly relies on its fuel injection system based on the common rail (CR) device. In order to tame the CR pressure dynamics without any a priori knowledge of the plant parameters, we design a novel model reference adaptive control strategy that extends the discrete-time minimal control synthesis algorithm. Indeed, an explicit discrete-time adaptive integral action is added to improve closed-loop performance. Experimental results support the analytical proof of stability, and confirm the effectiveness of the novel algorithm to solve both the regulation and the tracking control problem in a wide range of working conditions. The closed-loop performance is quantitatively evaluated via engineering indices.

Experimental Validation of a Hybrid Analytical-FEM Model of an Electromagnetic Engine Valve Actuator and Its Control Application

In this paper, a detailed mathematical model of an electromechanical valve actuator based on double electromagnets to actuate engine valves for camless engines is experimentally validated. The model was derived from an hybrid analytical finite element method approach and is here used as an effective tool to reproduce with high accuracy the behavior of such a variable valve timing actuator for different maneuvers of interest for camless engine applications. Experimental results of a model-based control strategy are also shown to give a first insight of its use for control purposes.