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Parameterized Diesel Engine Combustion Modeling for Torque Based Combustion Property Estimation

Chalmers University of Technology-Mikael Thor, Bo Egardt, Tomas McKelvey, Ingemar Andersson
Published 2012-04-16 by SAE International in United States
Combustion model structures based on Vibe functions are outlined and investigated in this work. The focus of the study is the use of such model structures for estimation of diesel combustion properties by reconstructing in-cylinder pressure from measurements of crankshaft torque. Investigated combustion properties include the start and phasing of the combustion as well as maximum values of the in-cylinder pressure and its derivative. The accuracy associated with the proposed estimation method is evaluated using ideal torque data, i.e. torque calculated from in-cylinder pressure, that is generated using both simulations and experiments. The results indicate that the uncertainty associated with the estimation of a selected combustion property tends to increase if that property is located close to TDC, where the signal-to-noise ratio is low for a torque signal. The results also show that the ideal torque based estimation of combustion phasing and maximum in-cylinder pressure generally is very accurate while the estimation of start of combustion and the maximum in-cylinder pressure derivative suffers more from disturbances and model imperfections.
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Modeling, Identification, and Separation of Crankshaft Dynamics in a Light-Duty Diesel Engine

Chalmers University of Technology-Mikael Thor, Ingemar Andersson, Tomas McKelvey
Published 2009-06-15 by SAE International in United States
Mathematical models of a torque sensor equipped crankshaft in a light-duty diesel engine are identified, validated, and compared. The models are based on in-cylinder pressure and crankshaft torque data collected from a 5-cylinder common-rail diesel engine running at multiple operating points. The work is motivated by the need of a crankshaft model in a closed-loop combustion control system based on crankshaft torque measurements. In such a system a crankshaft model is used in order to separate the measured crankshaft torque into cylinder individual torque contributions. A method for this is described and used for IMEP estimation.Not surprisingly, the results indicate that higher order models are able to estimate crankshaft torque more accurately than lower order models, even if the differences are small. For IMEP estimation using the cylinder separation method however, these differences have large effects on accuracy. Here, the performance of higher order models is significantly better than for lower order models. Also, models of odd model order perform better than models of even model order. On average, a 9th order model estimates IMEP…
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Parameterized Diesel Engine Heat Release Modeling for Combustion Phasing Analysis

Chalmers University of Technology-Mikael Thor, Ingemar Andersson, Tomas McKelvey
Published 2009-04-20 by SAE International in United States
Different Vibe function model structures for parameterized diesel engine heat release models are investigated. The work is motivated by the need of such models when closed-loop combustion control is implemented based on torque domain combustion phasing analysis.Starting from the studied model structures, models are created by estimating the model parameters using a separable least squares approach. After this, the models are evaluated according to two different performance criteria. The first criterion rates the ability of the estimated models to describe reference mass fraction burned traces. The second criterion assesses how accurately the models estimate the reference combustion phasing measure.As expected, the analysis shows that the models based on the most flexible model structure achieve the best results, both regarding mass fraction burned estimation and combustion phasing estimation. However, even if the less complex models describe the mass fraction burned traces with lower accuracy, these models are able to estimate the combustion phasing measure surprisingly well.
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Evaluation of a Closed Loop Spark Advance Controller Based on a Torque Sensor

SAE International Journal of Passenger Cars - Electronic and Electrical Systems

Chalmers University of Technology, Sweden-Ingemar Andersson, Thomas McKelvey, Mikael Thor
  • Journal Article
  • 2008-01-0987
Published 2008-04-14 by SAE International in United States
A closed loop spark advance control system was evaluated on a Volvo V70 5-cylinder spark ignited engine. The system utilises a crankshaft mounted torque sensor for combustion monitoring which provides individual cylinder combustion phasing information and enables individual cylinder spark advance control. The spark advance control system can compensate for changes in combustion operating conditions and hence limit the need for calibration.The spark advance control system was used in a mode of cylinder balancing where the control target is to keep the combustion phasing in all cylinders at a defined setpoint. This control law was evaluated in vehicle tests in an emission test chamber, running pre-defined driving cycles FTP72 and Highway Fuel Economy Test. Analysis shows that the combustion phasing was kept close to the selected setpoint during both tests and, hence, robustness in that sense was demonstrated.The torque ratio concept is used for combustion phasing monitoring based on crankshaft torque measurements. Analysis of the 50% torque ratio as a measure for combustion phasing shows that it is equivalent to 50% burned mass fraction.
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An Experimental Evaluation of Torque Sensor Based Feedback Control of Combustion Phasing in an SI-engine

Chalmers University of Technology-Stefan Larsson, Ingemar Andersson
Published 2005-04-11 by SAE International in United States
Feedback control of combustion phasing based on a crankshaft integrated torque sensor was developed for a spark ignited five cylinder engine. A cylinder individual measure for combustion phasing, called 50% torque ratio, is extracted from the torque signal and used by a spark advance controller. The estimated torque ratio is based on a simplified estimation algorithm where torsional resonances in the crankshaft are neglected, thus limiting the operating range up to a maximum of about 2000 rpm. The torque ratio measure has been compared with the existing measure 50% burned mass fraction, and proven to be a reliable measure for combustion phasing. The spark advance controller has been evaluated by using internal EGR changes as combustion disturbances and an examination of its cylinder balancing properties was performed.
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A Comparison of Combustion Temperature Models for Ionization Current Modeling in an SI Engine

Signals and Systems Chalmers University of Technology Mecel AB-Ingemar Andersson
Published 2004-03-08 by SAE International in United States
Combustion temperature models for spark ignited engines are investigated in this work. The temperature models are evaluated as sub-models of a model for the thermal part of ionization current.Three different combustion temperature models were investigated; a single-zone model, a mixed two-zone model and an unmixed two-zone called a kernel-zone model. The combustion temperature is derived from cylinder pressure. The ionization current model structure also contain sub-models for formation of nitric oxide (NO) and its thermal ionization. The model output is compared to the measured ionization currents with respect to peak amplitude and position.Also, two models for NO formation are evaluated. The first is a fixed NO molar fraction model and the second is a reaction rate controlled NO formation model based on the extended Zeldovich reaction scheme.It is shown that a kernel-zone model shows better performance in both peak amplitude and peak position than both the single-zone model and the mixed two-zone model. Both NO formation models showed equal performance for high temperature combustion but the rate controlled NO model can make an important contribution…
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An Analytic Model for Cylinder Pressure in a Four Stroke SI Engine

Vehicular Systems, Linköping Univ.-Lars Eriksson
Vehicular Systems, Linköping Univ. / Mecel AB-Ingemar Andersson
Published 2002-03-04 by SAE International in United States
An analytic model for cylinder pressures in spark ignited engines is developed and validated. The main result is a model expressed in closed form that describe the in-cylinder pressure development of an SI engine. The method is based on a parameterization of the ideal Otto cycle and takes variations in spark advance and air-to-fuel ratio into account. The model consists of a set of tuning parameters that all have a physical meaning. Experimental validation on two engines show that it is possible to describe the in-cylinder pressure of a spark ignited combustion engine operating close to stoichiometric conditions, as a function of crank angle, manifold pressure, manifold temperature and spark timing.
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Modeling of Combustion and Non-Equilibrium Ionization in Spark Ignition Engines

Kazan State Technical Univ.-Viatcheslav Naoumov, Aleksey Demin
Mecel AB-Ingemar Andersson, Andrey Sokolov
Published 2002-03-04 by SAE International in United States
The combustion of hydrocarbon fuels in cylinders of Spark Ignition (SI) engine is accompanied with various non-equilibrium chemical transformations, which are responsible for the operational and ecological parameters of the engine.Chemical non-equilibrium model and computer code of the combustion in a cylinder of SI engine was developed. It is based on the chemical kinetic model of combustion and interaction of combustion products. The model of the ionization current in a cylinder of SI engine was developed and added.The created model provides the important understanding of such sophisticated processes as combustion products behavior, chemical and thermal ionization, production of pollutants etc. The model predicts two peaks in the ionization current with good amplitude and phasing performance. It illuminates physical processes including chemical and thermal ionization. The model predicts two major peaks in the ionization current with sufficient amplitude and phasing performance for a given class of engines.
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Ion Sensing for Combustion Stability Control of a Spark Ignited Direct Injected Engine

Linköping Univ.-Lars Eriksson
Mecel AB-Ingemar Andersson
Published 2000-03-06 by SAE International in United States
The combustion stability of a direct injected spark ignited engine depends on the injection timing and it is desirable to have controller that minimizes the combustion variability.A novel approach for determining combustion stability in stratified mode is presented that rely on the ionization current and enables closed loop control of the injection timing. The co-efficient of variation for IMEP is used as a measure of combustion stability and a connection between maximum torque and low combustion variability is pointed out. The coefficient of variation of the ion current integral is well correlated with the coefficient of variation for IMEP. Furthermore, it is shown how the integral of the ion current together with COV(ion integral) can be used to determine the combustion stability and to distinguish high combustion stability from misfire.
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