Preliminary Analysis of a Hydraulic Variable Valve Actuation Loss Model for the Control-Oriented Base Engine Calibration

摘要

The achievement of the increasingly stringent emission limits for new passenger cars led to the development of complex engine architectures needed to perform advanced management strategies. Therefore, Variable Valve Actuation (VVA), Exhaust Gas Recirculation (EGR), Gasoline Direct Injection (GDI), turbocharging and powertrain hybridization have largely equipped modem internal combustion engines. Such complex systems provide a large set of degrees of freedom available for the engine regulation, introducing many new control variables within the control systems. The engine management software may contain hundreds of parameters that must be calibrated. Aim of the engine base calibration process is to identify proper values for the map, scalar and vector calibration parameters so that the values estimated by the functions are as close as possible to those that can be measured at the test bench in the same operating condition for the same quantity. Thousands of operating conditions can be analyzed and the physical quantities needed for the engine base calibration are acquired and recorded in a datasheet. This dataset is then used to calibrate the Engine Electronic Control Unit functions. The experimental activity, which can last several weeks, is the most critical stage of the process in terms of time and cost of implementation. Moreover, as the powertrain complexity increases, the calibration effort grows exponentially. In addition, the system complexity featured by current engines requires a further increase in experimental tests needed to achieve a reliable calibration. To overcome this criticality, authors, in previous papers, have proposed the adoption of a 0D-1D thermo-fluid dynamic simulation method used to generate mathematical and physical models of the engine behavior starting from a small subset of the engine operating conditions usually tested for calibration purposes. In particular, 0D-1D CFD simulation codes, after being reliably calibrated, could be useful