alma automotive: custom solutions for engine development and testIng

Research

  • Individual Cylinder Combustion Control Based on Real-Time Processing of Ion Current Signals

    Year: 2007

    Author: Nicolò Cavina, Davide Moro, Luca Poggio, Daniele Zecchetti, Riccardo Nanni, Andrea Gelmetti

    Download

    Read more

    The paper presents the main results of a research activity focused on the analysis, development, and real time implementation of a closed-loop, individual cylinder combustion control system, based on ion sensing technology.

    The innovative features of the proposed control system consist of extracting combustion quality related information from the ion current signal, and of using such information, together with pre-defined look-up-tables, for feedback control of the spark advance throughout the entire engine operating range. In particular, the ion current signal processing algorithm that is carried out in real-time, initially determines whether knocking is affecting or not the actual combustion process. Based on such evaluation, the closed-loop spark advance controller uses different signal processing algorithms to continuously determine individual cylinder spark advance deviations with respect to a pre-defined, base spark advance look up table, common to all the engine cylinders, and to store them in the Electronic Control Unit memory.

    The main result is therefore a spark advance controller that is continuously able to adapt its actuations both to engine/components variations (either due to ageing or to manufacturing component dispersion), as well as to varying external conditions (fuel quality, air temperature,…), in order to maximize torque production (or overall efficiency), cylinder by cylinder and combustion by combustion, even if the specific operating condition is affected by knock insurgence.

    The proposed control strategy has been successfully tested on a V12 6.0 liter and on a V12 6.2 liter high performance engines, and it is now part of the control system of V12 6 liter and V8 4 liter Ferrari engines.

    close

  • Common Rail Multi-Jet Diesel Engine Combustion Model Development for Control Purposes

    Year: 2007

    Author: Fabrizio Ponti, Enrico Corti, Gabriele Serra, Matteo De Cesare

    Download

    Read more

    Multi-jet injection strategies open significant opportunities for the combustion management of the modern diesel engine. Splitting up the injection process into 5 steps facilitates the proper design of the combustion phase in order to obtain the desired torque level, whilst attempting a reduction in emissions, particularly in terms of NOx.
    Complex 3-D models are needed in the design stage, where components such as the injector or combustion chamber shape have to be determined. Alternatively, zero-dimensional approaches are more useful when fast interpretation of experimental data is needed and an optimization of the combustion process should be obtained based on actual data. For example, zero-dimensional models allow a quick choice of optimum control settings for each engine operating condition, avoiding the need to test all the possible combinations of engine control parameters.
    In this paper a zero-dimensional model suitable for multi-jet engines with up to 4 injections is proposed, in order to synthesize the experimental results that have been obtained running a 1.3 liters multi-jet diesel engine in a test cell. The effects of Pilot injection rate on the heat release after the following injections in the same pattern are particularly emphasized: tests with different injection patterns have been run, focusing the attention on the very first part of the combustion process, where the fuel injected in the Pilot and Pre injections is burned.
    The model is finally employed to perform the optimization of the injection and intake control parameters for a single engine operating condition as an example of what has been done throughout the entire engine operating range. The optimization has been performed on the basis of the torque, noise and emission outputs obtained.

    close

  • Knock Indexes Thresholds Setting Methodology Technical Paper

    Year: 2007

    Author: Enrico Corti, Davide Moro

    Download

    Read more

    Gasoline engines can be affected, under certain operating conditions, by knocking combustions: this is still a factor limiting engines performance, and an accurate control is required for those engines working near the knock limit, in order to avoid permanent damage. HCCI engines also need a sophisticated combustion monitoring methodology, especially for high BMEP operating conditions.
    Many methodologies can be found in the literature to recognize potentially dangerous combustions, based on the analysis of the in-cylinder pressure signal. The signal is usually filtered and processed, in order to obtain an index that is then be compared to the knock threshold level.
    Thresholds setting is a challenging task, since usually indexes are not intrinsically related to the damages caused by abnormal combustions events. Furthermore, their values strongly depend on the engine operating conditions (speed and load), and thresholds must therefore vary with respect to speed and load.
    The knock phenomenon is associated to a steep increase in the combustion speed: some of the indexes proposed in the literature are based on the evaluation of the Rate of Heat Release (ROHR) by means of the in-cylinder pressure signal. The filtering operation, in this case, is crucial: in this paper a novel methodology for ROHR filtering is proposed, consisting in the application of a zero-dimensional model based on Wiebe functions. The observation of reconstructed Heat Release traces leads to determine whether the combustion will lead to knock or not. The methodology allows defining a knock index which is essentially dependent on the knocking-combustion rate, and therefore operating conditions-independent. This means that it can be used as a knock intensity reference for other indexes, making it possible to associate to the given index for the given operating condition a proper threshold level.

    close

  • Real-Time Evaluation of IMEP and ROHR-related Parameters

    Year: 2007

    Author: Enrico Corti, Davide Moro, Luca Solieri

    Download

    Read more

    Combustion control is one of the key factors to obtain better performance and lower pollutants emissions, for diesel, spark ignition and HCCI engines. This paper describes a real-time indicating system based on commercially available hardware and software, which allows the real-time evaluation of Indicated Mean Effective Pressure (IMEP) and Rate of Heat Release (ROHR) related parameters, such as 50%MFB, cylinder by cylinder, cycle by cycle. This kind of information is crucial for engine mapping and can be very important also for rapid control prototyping purposes.
    The project objective is to create a system able to process in-cylinder pressure signals in the angular domain without the need for crankshaft encoder, for example using as angular reference the signal coming from a standard equipment sensor wheel. This feature can be useful both for test bench and on-board tests. In order to gain reliable results or acceptable precision on ROHR-related parameters (ROHR peak & 50%MFB, for example) a high sampling rate is required for the in-cylinder pressure. Since the angular reference signal can have low angular resolution (6 degrees with a typical sensor wheel), the in-cylinder pressure signal sampling rate must be higher than the crankshaft signal frequency. The choice for this application has been to use a high sample rate on a time base for the cylinder pressure signal, performing the transformation from the time domain to the angular domain (necessary in order to evaluate the indicating parameters) by means of an interpolation algorithm.
    The system features a signal conditioning module allowing to plug directly VRS/Hall effect/encoder as reference sensors; the signals, thus converted to TTL level, are digitally sampled at high frequency for the crankshaft position recognition. In-cylinder pressure signals, instead, are sampled @ 100kHz. The conversion of these samples from the time domain to the angular domain is triggered by the sensor wheel signal. The algorithm used for the conversion can be time and memory consuming: the paper shows that the methodology used is crucial in order to save hardware resources, i.e. to increase the number of analyzed signals.
    As regards the hardware choice, many requirements have been taken into account: portability, sampling rate, computational power, programming language, external devices interface etc. The final solution is based on a portable Real-Time/FPGA based hardware, which allows performing all the necessary I/O functions and calculations in real time, even at high engine speed and with a high number of cylinders.

    close

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