Foto del docente

Davide Moro

Full Professor

Department of Industrial Engineering

Academic discipline: ING-IND/08 Fluid Machinery

Dean of Scuola di Ingegneria

Research

Keywords: ICE Nocive emission control Indirect measurement of an automotive turbocharger rotational speed ICE indicated and load torque estimation HCCI engines

1- Three methods are proposed for the real-time estimation of the torque indicated in a Diesel engine, based respectively on the harmonics of the speed signal, on the torsional analysis of the dual mass flywheel and on an accelerometric sensor.

This activity involves the development and validation of three methodologies aimed at estimating the indicated torque in real time, information that can have multiple repercussions in the areas of engine control and diagnosis. A first method, based on the signal of an inductive sensor facing a phonic wheel, allows, through a simplified mechanical model of the engine and the car, to correlate the harmonic components of the indicated speed and torque. Through an experimental correlation between the average component of the indicated torque and its harmonic with combustion frequency it is possible to obtain an estimate of the indicated torque. A second method is based on the analysis of the behavior of the double mass flywheel keyed on the crankshaft. Using the information coming from two inductive sensors, mounted upstream and downstream of the flywheel, it is possible to measure the relative torsion between the two discs of the flywheel, and obtain an estimate of the indicated torque. A last method involves the use of an accelerometric sensor mounted on the cylinder head, whose signal has harmonic components with a combustion frequency that can be correlated with the average component of the indicated torque.

2- Compliance with the limits of consumption and emissions for the near future can be achieved with the combustion technology by compression of a homogeneous charge, which requires the development of a sophisticated control methodology, the objective of the research.

Despite the progress that technology has made in the control of automotive engines. the request of the international community is to continue the further reduction of polluting emissions, with the simultaneous reduction of consumption: these are the terms that represent the main challenge for the automotive industry in the coming years. The aim of the research is to develop control strategies in the field of HCCI combustion applied to Diesel engines. The success of this technology lies in the ability to ensure the occurrence of the conditions necessary to trigger combustion at the desired angular momentum. Since the injection system must generate a homogeneous mixture between the air and the diesel fuel, to limit the NOx, the injection is brought forward to the beginning of the compression phase, when there are no conditions to activate combustion. A very refined control is needed to ensure the thermodynamic conditions and the composition of the filler in order to activate, taking into account the delays, the combustion reactions immediately after the top dead center. For this technology, control is essential because it helps stabilize combustion. The result can be achieved with the synergy between the modeling of the components, which influence the preparation of the charge in the cylinder, the combustion modeling connected to the parameters of influence and the development of the control strategy, which allows to verify, cylinder by cylinder and cycle per cycle, the positioning of the combustion and intervening to bring it back to the set point position.

3- The availability of the rotation speed measurement of the supercharging group allows to monitor the behavior of the group and obtain information that can optimize the overall behavior of the engine.

In supercharged engines, the use of variable geometry turbines is increasingly widespread, where there is a mobile stator blade to regulate the flow conditions of the flow rate of the combustion products discharged from the engine and which flow into the turbomachine. For checking the functioning of the supercharger and above all for ensuring a rapid dynamic response to load variations, knowledge of the rotation speed is essential, but this size is not yet available in the engine control unit at the moment, as they are not yet reliable sensors for the direct detection of the size due to the required life and the characteristics of the environment in which the sensor is to be mounted. The research aims to create an indirect speed measurement system based on the analysis of the acoustic emission. This type of system has the advantage of presenting low costs, it is not in direct contact with the supercharger and seems to adapt well to the average life of the vehicle but requires a particular development of the signal processing in order to make the information available in real time.