alma automotive: custom solutions for engine development and testIng

Research

  • Development of a Torsiometer for On-board Application

    Year: 2016

    Author: Vittorio Ravaglioli, Fabrizio Ponti, Enrico Corti, Alberto Cerofolini

    Download

    Read more

    Modern combustion control strategies require accurate combustion control to meet the requirements for pollutant emissions reduction. Optimal combustion control can be achieved through a closed-loop control based on indicated quantities, such as engine torque and center of combustion, which can be directly calculated through a proper processing of in-cylinder pressure trace. However, on-board installation of in-cylinder pressure sensors is uncommon, mainly because it causes a significant increase in the cost of the whole engine management system.

    In order to overcome the problems related to the on-board installation of cylinder pressure sensors, this work presents a remote combustion sensing methodology based on the simultaneous processing of two crankshaft speed signals. To maximize the signal-to-noise ratio, each speed measurement has been performed at opposed ends of the crankshaft, i.e. in correspondence of flywheel and distribution wheel. Since an engine speed sensor, usually faced to the flywheel, is already present on-board for other control purposes, the presented approach requires that an additional speed sensor is installed. Proper processing of the signals coming from the installed speed sensors allows extracting information about crankshaft's torsional behavior. Then, the calculated instantaneous crankshaft torsion can be used to real-time estimate both torque delivered by the engine and combustion phasing within the cycle.

    The presented methodology has been developed and validated using a light-duty L4 Common-Rail Diesel engine mounted in a test cell at University of Bologna. However, the discussed approach is general, and can be applied to engines with a different number of cylinders, both CI and SI.

    close

  • Engine Acoustic Emission Used as a Control Input: Applications to Diesel Engines

    Year: 2016

    Author: Fabrizio Ponti, Vittorio Ravaglioli, Federico Stola, Matteo De Cesare

    Download

    Read more

    The need for strategies that allow managing combustion in an adaptive way has recently widely increased. Especially Diesel engines aimed for clean combustion require a precise control of the combustion outputs.Acoustic emission of internal combustion engines contains a lot of information related to engine behavior and working conditions. Mechanical noise and combustion noise are usually the main contributions to the noise produced by an engine. Combustion noise in particular can be used as an indicator of the combustion that is taking place inside the combustion chamber and therefore as a reference for the control strategy.This work discusses the correlations existing between in cylinder combustion and the acoustic emission radiated by the engine and presents a possible approach to use this signal in the engine management system for control purposes. The application was tested by running several experimental tests, both in steady state and transient conditions, on a Diesel engine mounted in a test cell. Tests have been run in order to first identify the correlation existing between the different injection/combustion patterns that can be operated on the engine and the corresponding acoustic emission. Once the correlation between combustion process and engine noise has been identified it can be used to set up a closed-loop algorithm for optimal combustion control based on engine noise prediction.

    close

  • Accelerometer Based Methodology for Combustion Parameters Estimation

    Year: 2015

    Author: Andrea Businaro, Nicolò Cavina, , Enrico Corti, Giorgio Mancini, Davide Moro, Fabrizio Ponti, Vittorio Ravaglioli

    Download

    Read more

    Due to increasingly stringent emission regulations and the need of more efficient powertrains, obtaining information about combustion process becomes a key factor. Low-cost in-cylinder pressure sensors are being developed, but they still present long-term reliability issues, and represent a considerable part of the engine management system cost. Research is being conducted in order to develop methodologies for extracting relevant combustion information using standard sensors already installed on-board. The present work introduces a methodology for combustion parameters estimation, through a control-oriented analysis of structure-borne sound. The paper also shows experimental results obtained applying the estimation methodology to different passenger car engines.

    close

  • Acoustic Emission Processing for Turbocharged GDI Engine Control Applications

    Year: 2015

    Author: Cavina, N., Businaro, A., Mancini, G., De Cesare, M.

    Download

    Read more

    In the field of passenger car engines, recent research advances have proven the effectiveness of downsized, turbocharged and direct injection concepts, applied to gasoline combustion systems, to reduce the overall fuel consumption while respecting particularly stringent exhaust emissions limits. Knock and turbocharger control are two of the most critical factors that influence the achievement of maximum efficiency and satisfactory drivability, for this new generation of engines. The sound emitted from an engine encloses many information related to its operating condition. In particular, the turbocharger whistle and the knock clink are unmistakable sounds. This paper presents the development of real-time control functions, based on direct measurement of the engine acoustic emission, captured by an innovative and low cost acoustic sensor, implemented on a platform suitable for on-board application. The real-time signal processing algorithms can be integrated in the actual ECU software, in order to improve the engine controller performance. Experimental tests have been carried out in a test-cell environment, using a downsized and turbocharged GDI engine. In order to evaluate the acoustic signal processing algorithms performance, and to prove the effectiveness of the proposed methodology, knocking was externally induced by acting on the spark advance, while turbocharger operation was controlled over wide and fast speed transients.

    close

  • Automotive turbochargers power estimation based on speed fluctuation analysis

    Year: 2015

    Author: V. Ravaglioli, N. Cavina, A. Cerofolini, E. Corti, D. Moro, F. Ponti

    Download

    Read more

    Turbocharging technology will play a crucial role in the near future as a way to meet the requirements for pollutant emissions and fuel consumption reduction.

    However, optimal turbocharger control is still an issue, especially for downsized engines fitted with a low number of cylinders. As a matter of fact, automotive turbochargers are characterized by wide operating range and unsteady gas flow through the turbine, while only steady flow maps are usually provided by the manufacturer. In addition, in passenger cars applications, real-time turbocharger optimal control is even more difficult because of the lack of information about pressure/temperature in turbine upstream/downstream circuits and turbocharger rotational speed.

    In order to overcome these unknowns, this work presents a methodology for instantaneous turbocharger rotational speed determination through a proper processing of the signal coming from one accelerometer mounted on the compressor diffuser, or one microphone facing the compressor. The presented approach can be used to evaluate both turbocharger speed mean value and the amplitude of turbocharger speed fluctuations caused by the pulsating gas flow in turbine upstream and downstream circuits. Once turbocharger speed has been determined, it can be used to estimate power delivered by the turbine.

    The whole estimation algorithm has been developed and validated for a light duty turbocharged Common-Rail Diesel engine mounted in a test cell. However, the developed methodology is general and can be applied to different turbochargers, both for Spark Ignited and Diesel applications.

    close

  • Turbocharger Control-Oriented Modeling: Twin-Entry Turbine Issues and Possible Solutions

    Year: 2015

    Author: Cavina, N., Borelli, A., Calogero, L., Cevolani, R.

    Download

    Read more

    The paper presents possible solutions for developing fast and reliable turbocharger models, to be used mainly for control applications. This issue is of particular interest today for SI engines since, due to the search for consistent CO2 reduction, extreme downsizing concepts require highly boosted air charge solutions to compensate for power and torque de-rating. For engines presenting at least four in-line cylinders, twin-entry turbines offer the ability of maximizing the overall energy conversion efficiency, and therefore such solutions are actually widely adopted.

    This work presents a critical review of the most promising (and recent) modeling approaches for automotive turbochargers, highlighting the main open issues especially in the field of turbine models, and proposing possible improvements. The main original contribution is then on solving specific issues related to the twin-entry turbine, to develop a control-oriented model able to predict the machine behavior under all possible admission conditions.

    The results of this study have been applied to a V8 high-performance GDI engine with twin-entry turbochargers. Experimental data are shown throughout the paper, to demonstrate the benefits of the proposed approach.

    close

  • Assessment of the Influence of GDI Injection System Parameters on Soot Emission and Combustion Stability through a Numerical and Experimental Approach

    Year: 2015

    Author: Cavina, N., Businaro, A., Moro, D., Di Gioia, R.

    Download

    Read more

    The next steps of the current European and US legislation, EURO 6c and LEV III, and the incoming new test cycles will impose more severe restrictions on pollutant emissions for Gasoline Direct Injection (GDI) engines. In particular, soot emission limits will represent a challenge for the development of this kind of engine concept, if injection and after-treatment systems costs are to be minimized at the same time. The paper illustrates the results obtained by means of a numerical and experimental approach, in terms of soot emissions and combustion stability assessment and control, especially during catalyst-heating conditions, where the main soot quantity in the test cycle is produced. A number of injector configurations has been designed by means of a CAD geometrical analysis, considering the main effects of the spray target on wall impingement. The numerical CFD simulation has helped the definition of the injection system and of its control settings for a given operating condition, in terms of start of injection, injection pressure and number of pulses per stroke. Engine test bench experiments have finally been used to validate the numerical results, and to further optimize the injection system calibration in order to minimize soot emissions, while respecting combustion stability constraints. The main results are presented in the paper.

    close

  • Estimation Methodology for Automotive Turbochargers Speed Fluctuations Due to Pulsating Flows

    Year: 2015

    Author: Ponti F., Ravaglioli V., De Cesare M.

    Download

    Read more

    Turbocharging technique, together with engine downsizing, will play a fundamental role in the near future as a way to reach the required maximum performance while reducing engine displacement and, consequently, CO2 emissions. However, performing an optimal control of the turbocharging system is very difficult, especially for small engines fitted with a low number of cylinders. This is mainly due to the high turbocharger operating range and to the fact that the flow through compressor and turbine is highly unsteady, while only steady-flow maps are usually provided by the manufacturer. In addition, in passenger cars applications, it is usually difficult to optimize turbocharger operating conditions because of the lack of information about pressure/temperature in turbine upstream/downstream circuits and turbocharger rotational speed. This work presents a methodology suitable for instantaneous turbocharger rotational speed determination through a proper processing of the signal coming from an accelerometer mounted on the compressor diffuser or a microphone faced to the compressor. The presented approach can be used to evaluate turbocharger speed mean value and turbocharger speed fluctuation (due to unsteady flow in turbine upstream and downstream circuits), which can be correlated to the power delivered by the turbine. The whole estimation algorithm has been developed and validated for a light-duty turbocharged common-rail diesel engine mounted in a test cell. Nevertheless, the developed methodology is general and can be applied to different turbochargers, both for spark ignited and diesel applications.

    close

Page 1... 2... ... 15

OUR PARTNERS

National Instruments

ORGANIZATIONS WE SPONSOR

Unibo Motorsport

OUR AWARDS

NIDays 2013

© Copyright 2017 - Alma Automotive s.r.l.  -  P.IVA e C.F. 02315721205  -  Privacy  -  Credits