On the Modelling of an Electro-Hydraulic Valve Actuator for Camless Engines

Electro-Hydraulic Valve Actuators (EHVAs) are proposed as an enabling technology for implementation of advanced combustion concepts via Variable Valve Actuation (VVA) of intake and exhaust valves separately, with benefits of pollution reduction and improvement of efficiency for internal combustion engines. In this regard, the mathematical modelling of an EHVA system for camless engines is tackled in this report. The system complexity, nonlinear properties and time delay phenomena of the hydraulic actuator make the modeling, identification and control challenging. Model parameters are estimated via an off-line parameter identification procedure which combines least square method, regression model and nonlinear optimization routines. The combined approach is applied to a wide set of experimental data. The resulting model aims to predict system dynamics and be exploited for synthesizing cycle-by-cycle control algorithms for valve lift.