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Growing concerns about the emissions of internal combustion engines have forced the adoption of aftertreatment devices to reduce the adverse impact of diesel engines on health and environment. Diesel particulate filters are considered as an effective means to reduce the particle emissions and comply with the regulations. Research activity in this field focuses on filter configuration, materials and aging, on understanding the variation of soot layer properties during time, on defining of the optimal strategy of DPF management for on-board control applications. A model was implemented in order to simulate the filtration and regeneration processes of a wall-flow particulate filter, taking into account the emission characteristic of the engine, whose architecture and operating conditions deeply affect the size distribution of soot particles.

The research and development activities on diesel injection systems have focused some key-factors that improve the solenoid actuated injector performance, especially in the frame of the multi-event injection strategies. This paper deals with a 3-D numerical investigation that highlights the nozzle flow features of different injector layouts. A comparison between a last generation standard injector and an optimized unit characterized by an improved dynamics, different number of holes and reduced maximum lift is performed. By means of transient numerical simulations, the behavior of the fuel flows, the tendency to cavitation development and the response to the deviation from the standard operating conditions (highlighted by introducing a radial perturbation on the lift motion) are investigated.

Many efforts are being currently devoted to the development of diagnostic techniques based on nonintrusive measurements aimed at defining the injection parameters able to optimize the combustion process. Previous papers of the authors have demonstrated a direct relationship between in-cylinder pressure and engine block vibration signals. Besides, it was also shown sensitivity of the engine surface vibration to variation of injection parameters, when the accelerometer is placed in sensitive location of the engine block. Moreover, in the accelerometer signal, a frequency band in which such a relationship is very strict has been selected. The aim of the present work is to establish a reliable relation between the main characteristics of the in-cylinder pressure curve and the vibration trend, by means of a deeper insight into the engine block signal. The final objective is to monitor the combustion behavior by means of a non-intrusive transducer.

The optimization of the combustion process in diesel engines is one of the challenges to improve performance, emissions, fuel consumption and NVH characteristics. This work constitutes one of the last steps of a comprehensive research program in which vibration sensors are used with the purpose of developing and setting up a methodology that is able to monitor and optimize the combustion process by means of non-intrusive measurements. Previously published results have demonstrated the direct relationship that exists between in-cylinder pressure and engine block vibration signals, as well as the sensitivity of the engine surface vibration to variation of injection parameters when the accelerometer is placed in a sensitive location of the engine block.

To ensure compliance with emerging Diesel emission standards and demands for reduced fuel consumption, the optimization of the engine operation is imperative under both stationary and real operation conditions. This issue imposes a strict control of the combustion process that requires a closed-loop algorithm able to provide an optimal response of the engine system not only to warm-up, accelerations, changes in the slope of the road, etc., but also to engine aging and variations of fuel properties. In this paper, with the final purpose of accomplishing an innovative control strategy based on non intrusive measurement, the engine block vibration signal is used to extract useful information able to characterize the in-cylinder pressure development during the combustion process. In the previous research activity, the same methodology was applied to stationary operation of the engine.