Search Results

In modern internal combustion engines a greater reduction of CO₂ emissions is required in order to significantly reduce fuel consumption and minimize the emissions of polluting gases, allowing them to fall within the strict limits set by current regulations. In a conventional engine control system, it is not possible to optimize the efficiency of the alternator in terms of emissions and fuel consumption, due to a constant voltage which is imposed and is not modifiable. On the contrary, in a system capable of controlling the voltage of the alternator, referring to such an alternator as "smart" hereafter, it would be possible to optimize its efficiency as a function of the vehicle/engine working points. This system requires first and foremost a communication protocol between the alternator and engine control unit, and a special sensor that gets data on the charging status of the battery.

The development of embedded control systems is still a relatively new and young discipline. There is consequently a lack of tools, methods and models to support, in particular, the early architectural design stages. In this paper a new environment for embedded control systems development is presented, which supports the modelling of such systems at a high abstraction level. The tool allows control engineers and software developers to focus on the control system aspects instead of the aspects of the platform. Two application examples will explain the important capability of this tool to provide a timing analysis before production code generation.

Modern engine control systems need to know the exact air mass flow drawn by engine. For cost reasons, engines of medium and small displacement are not equipped with an air flow meter and so the air mass flow must be estimated by means of a specific algorithm using other sensors’ data based on a simplification of manifold filling dynamics model [1]. In the last years this algorithm has been modified in order to consider the dependency of air mass flow also on the atmospheric pressure. The actual implementation of this algorithm anyhow does not ever guarantee a correct estimation in altitude. In this paper an algorithm that uses a novel, simple and effective dependency of the air mass flow on the atmospheric pressure will be presented. As a first step, a new data acquisition in altitude has been performed, in order to better understand how the atmospheric pressure variation influences engine functionality and, in particular, the intake efficiency.

In the automotive world the “electronics and software” are continuously increasing. In this scenario the correct definition and, more in general, correct management of requirements in the development process of software is a key factor for continuous success. The real-time characteristic of control functions software makes the development process more complex and articulated. This paper describes a more formal approach in the software requirements specification which is based on a requirements model. The purpose of the model is to define the syntax and semantic elements in an unambiguous way. These elements are based on three classes of requirements: “simple requirement”, “composite requirement” and “composite with a finite state machine requirement”. The paper gives a description of every class of requirement, and the capability of model elements composition to describe more complex requirements is shown.

Spark-ignited engines equipped by a three-way catalyst require a precise control of the air fuel ratio fed to the combustion chamber. A stoichiometric mixture is necessary for the proper working of the catalyst in order to meet the legislation requirement. A critical part of the air fuel ratio control is the feed-forward compensation of the fuel dynamics. Conventional strategies are based on a simplified model of the wall-wetting phenomena whose parameters are stored in off-line computed look-up tables. Unfortunately, errors in the parameters calibration over the whole engine map deteriorate the control performances in terms of emissions. In this paper an automatic procedure for a rapid and efficient identification of the wall-wetting parameters is presented. The whole procedure has been experimentally tested on a vehicle by using a test bench.