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The optimization of turbocharging systems for automotive applications has become crucial in order to increase engine performance and meet the requirements for pollutant emissions and fuel consumption reduction. Unfortunately, performing an optimal turbocharging system control is very difficult, mainly due to the fact that the flow through compressor and turbine is highly unsteady, while only steady flow maps are usually provided by the manufacturer. For these reasons, one of the most important quantities to be used onboard for optimal turbocharger system control is the rotational speed fluctuation, since it provides information both on turbocharger operating point and on the energy of the unsteady flow in the intake and exhaust circuits. This work presents a methodology that allows determining the instantaneous turbocharger rotational speed through a proper frequency processing of the signal coming from one accelerometer mounted on the turbocharger compressor.

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.

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.

The optimization of a high performance engine in order to achieve maximum power at full load and high speed can cause an unstable behavior when the engine is running at different conditions, thus making a robust combustion diagnosis for on board diagnostic EOBD/OBD II purposes (misfiring detection) particularly challenging. In fact, when a misfire occurs, its detection can be critical because of the high background noise due to high indicated mean effective pressure (IMEP) cyclic variability. A partial reduction of the high IMEP variability had been achieved by optimizing control parameters of a new prototype high performance V8/4.2 l engine. Spark advance and VVT phasing maps had in fact been re-designed based on in-cylinder pressure variability (cycle by cycle and cylinder by cylinder) analysis.

The paper presents the development of a model study whose results enable to evaluate the torque production non-uniformity between the cylinders of an Internal Combustion Engine (ICE). This non-uniformity can be due, for example, to different air breathing into the cylinders, to different injector characteristics, or to pathological operating conditions such as misfires or misfuels, as well as to other abnormal operating conditions. Between the nominal torque production and the one corresponding to the absence of combustion there exist, in fact, a series of possible intermediate conditions, each of them corresponding to a value of produced torque between the nominal value and the one corresponding to the lack of combustion (due for example to statistical dispersion in manufacturing, or aging in the injection system). The diagnosis of this type of non-uniformity is a very important issue in today's engine control strategies design.

Compression-ignited engines are still considered the most efficient and reliable technology for automotive applications. However, current and future emission regulations, which severely limit the production of NOx, particulate matter and CO2, hinder the use of diesel-like fuels. As a matter of fact, the spontaneous ignition of directly-injected Diesel leads to a combustion process that is heterogeneous by nature, therefore characterized by the simultaneous production of particulate matter and NOx. In this scenario, several innovative combustion techniques have been investigated over the past years, the goal being to benefit from the high thermal efficiency of compression-ignited engines, which results primarily from high Compression Ratio and lean and unthrottled operation, while simultaneously mitigating the amount of pollutant emissions.