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Research

  • Comparison between Formula 1 and CART Acoustic Emission Analysis

    Year: 2002

    Author: Nicolò Cavina

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    The paper presents the application of signal processing algorithms to racing engines acoustic emission signals. The proposed methodology has shown to be effective in extracting from such signals information related to the main powertrain performance parameters, such as engine speed, gear ratios and driver's strategy. The objective of the paper is to compare performance parameters of racing engines that have participated in two different Championships, FIA Formula One World Championship (Formula 1) and CART Champ Car Series (CART). The comparison is quite interesting, since the two formulas differ not only in terms of regulations (and therefore in terms of admissible powertrain layouts), but also in terms of circuits where the races take place. For example, ovals are quite common in CART, and that is not the case of Formula 1: This fact is reflected in the different way the engine and the gearbox are operated during the race.

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  • Misfire Detection Based on Engine Speed Time-Frequency Analysis

    Year: 2002

    Author: Nicolò Cavina, Enrico Corti, Giorgio Minelli, Gabriele Serra

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    The paper presents the development of a methodology for detecting the misfire event using the time-frequency analysis of the instantaneous engine speed signal. The diagnosis of this type of malfunctioning operating condition is enforced by OBD requirements over the whole operating range of the engine, and many different approaches have been developed in the past in order to solve this problem.

    The novel approach presented here is based on the observation that the misfire causes an impulsive lack of torque acting on the engine crankshaft, and thus it causes the excitation of damped torsional vibrations at frequencies characteristic of the system under study. In order to enlighten the presence of this torsional vibration (and therefore detect the misfire event), information contained in the instantaneous crankshaft speed fluctuations have been processed in the time-frequency domain. A misfire detection parameter has then been defined showing a good capability of diagnosing the misfire occurrence.

    The procedure has been setup and validated running a supercharged 2 liter V6 SI engine in an engine test cell; in-cylinder pressure signals have been acquired together with the instantaneous engine speed, in order to verify the capability of the methodology.

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  • Formula 1 Engine Evolution Analysis Using the Engine Acoustic Emission

    Year: 2002

    Author: Fabrizio Ponti

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    This paper presents some results of a methodology capable of extracting instantaneous engine speed information from acoustic emission measurements, obtained from Formula 1 (F1) vehicles during qualifying or race sessions, from the early races in 50s-60s until present days. The results presented in the paper show that, from this signal, it is possible to gain information regarding the instantaneous engine speed (that in racing engines is strongly related to the power developed by the engine itself), but also regarding the way the combustions are distributed within an engine cycle, the time needed for a gear shift, the gear ratios employed, the driving strategy and so on.
    The analysis conducted in this work is applied to acoustic emission data recorded by microphones placed on-board the investigated cars. In recent years each F1 vehicle has been equipped with its own microphone while, in early races, in-car microphones had not been systematically used. It is anyway possible to find in the literature some recordings coming from microphones placed on board, during tests or even qualifying and race sessions.
    The analysis has shown to be insensitive from the type of microphone employed and from its position on-board the vehicle; even the signal coming from a low-cost microphone showed to be good enough for successfully applying the developed methodology. This made possible a useful comparison between the information obtained from all the engine acoustic emission signals available in the literature, thus allowing to analyze F1 powertrain evolution over the last four decades.

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  • Evaluation of Wide Open Throttle Torque Production based on Engine Acoustic Emission

    Year: 2002

    Author: Davide Moro, Fabrizio Ponti

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    The paper presents the development of a methodology for the evaluation of the Wide-Open-Throttle (WOT) torque production when the engine is running free. Under such conditions the engine speed shows a sudden increase due to the high engine torque production associated with the WOT conditions, and to the absence of a load connected to the engine. The acoustic emission of the engine contains information related to this speed increase and thus to the engine torque production.
    The methodology unveils the information contained in the engine acoustic emission to estimate the torque produced under WOT operating conditions. This estimation can be performed without the need of coupling the engine to a brake, and does not require installing any additional sensor.
    For this reason the approach here presented could be very useful for engine testing at the end of the assembly line. In fact, since the test to be performed is very fast and does not require to couple the engine to a brake, it allows to dramatically reduce the time needed for the testing procedure. This means cost reduction and the possibility to perform such testing procedure on all the produced engines.
    Experimental tests have been performed in order to set-up the methodology on an L4 1.2 liter engine. The approach has been finally applied to the same engine, whose injection timing and spark advance were controlled to modify its torque production. The procedure showed a good capability to estimate WOT torque production, and to detect abnormal conditions that were induced by appropriately controlling injection and ignition.

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  • Strategies to Evaluate Power Output in Racing Engines. Case Study: 2002 World Offshore Class I Regulations

    Year: 2002

    Author: Enrico Corti, Davide Moro

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    To establish a fair competition between racing vehicles is not an easy task, if different types of engine are allowed to participate (within the same class). In the Motorsports world there are several Championships where the regulations leave to the project manager substantial freedom in the vehicle-engine layout definition: The 2002 World Offshore Class I Championship (WOCC) seems to be an excellent example, since both gasoline and diesel (naturally aspirated and turbocharged) engines are admitted to race.
    The paper presents a power output comparison method that could be useful both for the organizers to establish a fair competition as well as for the racing engineers to decide what's the optimal layout.
    Since the analysis regards the maximum power, BMEP and engine speed have to be evaluated under such condition for the engines to be compared. This operation is done on a statistical basis, which means that the results of the analysis are not numerically exact, but they offer useful tools to make a meaningful comparison.
    The engine performance is then calculated, considering the limitations imposed by the WOCC regulations. The power deliverable by diesel turbocharged engines is found to be much higher than that obtainable from other engines allowed to participate in the same class. Several solutions have been considered in order to obtain the same power output from different engines, and therefore to re-establish a fair competition.
    A reduction of the turbocharging pressure (through a standard pop-off valve), a limitation of the intake air mass flow (through a Venturi-type duct or a diaphgram), and a limitation on fuel consumption, may all be used to reduce the gap. The method allows to propose changes in the regulations and to determine reliable values for performance limitation parameters.

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  • Energy based model of a common rail injector

    Year: 2002

    Author: Riccardo Morselli, Enrico Corti, Giorgio Rizzoni

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    In order to develop a precise control of the fuel injection in diesel engines as a means to reduce noise and fuel consumption, while improving torque and power performances, a model of the fuel injection system is required. This paper proposes a simple energy-based model of a common rail injector, one of the most complex and important part of the injection system. The injector model has been validated comparing some simulation results with real experimental data. A complete model of the whole common rail injection system is also proposed as a basis for the development of the diesel engines control strategies.

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  • On-board indicated pressure and torque estimation in engines with a high number of cylinders

    Year: 2002

    Author: Enrico Corti, Davide Moro

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    In recent years engine control development focused the attention on torque-based models, that allow improving driveability and implementing traction control strategies. The design of such a torque-based engine control strategy requires the knowledge of the torque produce by the engine, which depends on fuel injection time, spark advance, throttle opening, EGR command, [[ellipsis]] In the actual engine control strategies this is mainly done by means of static maps stored in the ECU memory. The real engine torque production under every operating condition can be evaluated by means of the in-cylinder pressure estimation, thus allowing a torque based closed loop control strategy. Many approaches are present in the literature showing the possibility of on-board estimating the actual torque produced by the engine not simply by using static maps, but estimating it through other measured signals. Most of the methodologies that do not require a specific sensor placed on the engine are based either on the engine speed fluctuations (measured by a pick-up facing the flywheel teeth) or on the engine block vibrations (measured by the knock sensor), performing better for engines with a low number of cylinders. The paper presents an original methodology based on the instantaneous engine speed fluctuations, that has been usefully applied to engines with higher number of cylinders. The methodology is based on the observation of the speed fluctuations in a crankshaft window inside the expansion stroke and on the hypothesis that there exists a strong correlation between these engine speed fluctuations and pressure inside the selected cylinder. This relationship has been characterized using Frequency Response Functions (FRF) for each steady-state engine operating condition. In the following the FRFs have been used to perform in-cylinder pressure and then indicated torque estimation under every operating condition, and a specific signal processing algorithm has been developed in order to apply the procedure during speed and load engine transients. The experimental tests have been conducted mounting a six-cylinder turbo-charged spark-ignited engine in a test cell. The application on-board a vehicle of the same methodology seems to be feasible due to the quickness of the algorithm employed and the presence on-board of all the sensors required for the implementation.

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  • Power Oriented Modeling of a Common Rail Injector

    Year: 2002

    Author: Riccardo Morselli, Enrico Corti, Giorgio Rizzoni

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    The common rail injection system has allowed torque and power performance of diesel engines to improve greatly, while reducing fuel consumption and conforming to emissions standards. This paper proposes a simple but effective energy-based model of a common rail injector as a basis for the implementation of the advanced fuel injection control strategies. The proposed model has been validated comparing the simulation results with real experimental data. The obtained results show how the dynamic behavior of the injector is well captured by the model.

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