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  • 1.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    CHEPP – A Chemical Equilibrium Program Package for Matlab2005In: SAE technical paper series, ISSN 0148-7191, Vol. 4, no 113, p. 730-741Article in journal (Refereed)
    Abstract [en]

    A program package, that calculates chemical equilibrium and thermodynamic properties of reactants and products of a combustion reaction between fuel and air, has been developed and validated. The package consists of the following four parts: 1) A program for calculating chemical equilibrium. 2) A database that contains thermochemical information about the molecules, which comes from the GRI-Mech tables. 3) A GUI that allows the user to easily select fuels, fuel/air ratio for the reaction, and combustion products. 4) A set of functions designed to access the thermochemical database and the chemical equilibrium programs. Results are validated against both the NASA equilibrium program (Gordon and McBride, 1994) and the program developed by Olikara and Borman (1975). It is shown that the new method gives results identical to those well recognized Fortran programs.

  • 2.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Mean Value Models for Exhaust System Temperatures2003In: SAE technical paper series, ISSN 0148-7191, Vol. 111, no 3Article in journal (Refereed)
    Abstract [en]

    Exhaust temperatures are important for turbine and catalyst performance. A set of exhaust temperature models suitable for turbo matching as well as design and analysis of engine control systems are developed and investigated. The models are lumped parameter heat transfer models, that fall within the category of mean value engine models. The model is developed for describing exit temperatures from the exhaust manifold and temperature drops in pipe sections in the exhaust system. The components used to model the exhaust temperature are: engine out temperature, temperature drop in a straight pipe, and a set of heat transfer modes. The model is validated using data from three different engines. It is shown that, for a spark ignited engine operating at MBT and stoichiometric conditions, it is sufficient to model the engine out temperature as a linear function of mass flow. Recommendations for tuning the model are also given. A thorough survey of exhaust heat transfer literature is also made together with a comparative summary of the different heat transfer modes that are present in the exhaust.

  • 3.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Requirements for and a Systematic Method for Identifying Heat-Release Model Parameters1998In: SAE technical paper series, ISSN 0148-7191, Vol. 107, p. 898-908Article in journal (Refereed)
    Abstract [en]

    Heat release analysis by using a pressure sensor signal is a well recognized technique for evaluation of the combustion event, and also for combustion diagnostics. The analysis includes tuning of several parameters in order to accurately explain measured data. This work presents and investigates a systematic method for estimating parameters in heat release models and minimizing the arbitrary choices. In order for the procedure to be systematic there are also the requirements on the model, that it includes no inherent ambiguities, like over-parameterization with respect to the parameters and to the information contained in the measurements. The fundamental question is which parameters, in the heat release model, that can be identified by using only cylinder pressure data. The parameter estimation is based on established techniques, that constructs a predictor for the model and then minimizes a least-squares objective function of the prediction error. The study is performed on data measured on a SAAB 2.3 liter, four stroke four cylinder, normally aspirated, gasoline engine.

  • 4.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Spark Advance for Optimal Efficiency1999In: SAE technical paper series, ISSN 0148-7191, Vol. 108, p. 789-798Article in journal (Refereed)
    Abstract [en]

    Most of todays spark-advance controllers operate in open loop but there are several benefits of using feed-back or adaptive schemes based on variables deduced from the cylinder pressure. A systematic study of how different engine conditions change the deduced variables, at optimal ignition timing, is performed. The analysis is performed using a one-zone heat-release model and varying the model parameters. The deduced variables that are studied are: position of the pressure peak, mass fraction burned levels of 30%, 45%, 50%, and 90%, and the pressure ratio. For MBT timing the position for 45% mass fraction burned changed least under a large variety of changes in burn rate. Cycle-to-cycle variations do not have a significant effect and it suffices to evaluate the mean values for the burn rate parameters. The pressure ratio produces values similar to the mass fraction burned and requires no separate treatment.

  • 5.
    Eriksson, Lars
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Andersson, Ingemar
    Chalmers.
    An Analytic Model for Cylinder Pressure in a Four Stroke SI Engine2003In: SAE technical paper series, ISSN 0148-7191, Vol. 111, no 3Article in journal (Refereed)
    Abstract [en]

    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.

  • 6.
    Eriksson, Lars
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Nielsen, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Glavenius, Mikael
    Mecel AB.
    Closed Loop Ignition Control by Ionization Current Interpretation1998In: SAE technical paper series, ISSN 0148-7191, Vol. 106, no SAE Technical Paper 970854, p. 1216-1223Article in journal (Refereed)
    Abstract [en]

    The main result of this paper is a real-time closed loop demonstration of spark advance control by interpretation of ionization current signals. The advantages of such a system is quantified. The ionization current, obtained by using the spark plug as a sensor, is rich on information, but the signal is also complex. A key step in our method is to use parameterized functions to describe the ionization current. The results are validated on a SAAB 2.3 l, normally aspirated, production engine, showing that the placement of the pressure trace relative to TDC is controlled using only the ionization current for feedback.

  • 7.
    Eriksson, Lars
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Nielsen, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Nytomt, Jan
    Mecel AB.
    Ignition Control by Ionization Current Interpretation1997In: SAE technical paper series, ISSN 0148-7191, Vol. 105, no SAE Technical Paper 960045, p. 165-171Article in journal (Refereed)
    Abstract [en]

    Spark advance setting in spark-ignited engines is used to place the in-cylinder pressure curve relative to the top dead center. It is demonstrated that ionization current interpretation is feasible to use for spark advance control to optimize engine performance. A feedback scheme, not a calibration scheme, based on ionization current is proposed. It is thus related to pressure sensor feedback schemes, that have reported good results, but have not yet proven cost effective due to the cost of the pressure sensor. The method proposed here is very cost effective since it uses exactly the same hardware and instrumentation (already used in production cars) that is used to utilize the spark plug as a sensor to detect misfire and as a sensor for knock control. The only addition for ignition control is further signal interpretation in the electronic engine control unit.</P> A key idea in our method is to use parameterized functions to describe the ionization current. These parameterized functions are used to separate out the different phases of the ionization current. Special emphasis is made to get a correct description of the pressure development. The results are validated on a SAAB 2.3 l production engine by direct comparison with an in-cylinder pressure sensor (used only for validation, not for control), but also by using a physical model relating the ionization current to the pressure.

  • 8.
    Klein, Marcus
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Nilsson, Ylva
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Compression Estimation from Simulated and Measured Cylinder Pressure2003In: SAE technical paper series, ISSN 0148-7191, Vol. 111, no 3Article in journal (Refereed)
    Abstract [en]

    Three methods for estimating the compression from measured cylinder pressure traces are described and evaluated for both motored and fired cycles against simulated and measured cylinder pressure. The first two rely upon a model of polytropic compression, and it is shown that they give a good estimate of the compression ratio for simulated cycles for low compression ratios. For high compression ratios, these simple models lack the information about heat transfer. The third method includes a standard heat transfer and crevice effect model, together with a heat release model and is able to estimate the compression ratio more accurately.

  • 9.
    Nyberg, Mattias
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Nielsen, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Model Based Diagnosis for the Air Intake System of the SI-Engine1998In: SAE technical paper series, ISSN 0148-7191, Vol. 106, p. 9-20Article in journal (Refereed)
    Abstract [en]

    Because of legislative regulations like OBDII, on-board diagnosis has gained much interest lately. A model based approach is suggested for the diagnosis of the air intake system of an SI-engine. Important research issues are modeling concepts, residual generation and evaluation, overall performance, and limiting factors. The diagnosis system is based on a non-linear semi-physical model and uses a combination of different residual generation methods. It is capable of detecting and isolating faults in the throttle actuator, throttle sensor, air mass flow sensor and manifold pressure sensor. The scheme is experimentally validated on a real production engine.

  • 10.
    Pettersson, Magnus
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Nielsen, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Hedström, Lars-Gunnar
    Scania, Södertälje, Sweden.
    Transmission-Torque Control for Gear Shifting with Engine Control1997In: SAE technical paper series, ISSN 0148-7191, article id 970864Article in journal (Refereed)
    Abstract [en]

    By using engine controlled gear shifting, a manual transmissioncan be automated without using the clutch duringthe shift event.The main contribution of this paper is a novel extensionof the existing system using active handling ofdriveline resonances. The strategy is based on a modelof the transmission torque, which is derived by usingexperimental data from a heavy truck. A key step isthe design of a criterion for a controller that drives thetransmission torque to zero with damped resonances andwith a control signal realizable by the engine.The proposed solution offers a possibility to optimizethe time needed for a gear shift, which is important sincethe vehicle is free rolling when in gear-shift condition.Furthermore, neutral gear can successfully be engagedalso when facing initial driveline oscillations and loaddisturbances.

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