Modeling of shift hydraulic system for automatic transmission

The main functions of the shift hydraulic system for stepped automatic transmission are to generate and maintain desired clutch pressures for shifting operation, as well as to initiate gear shifts and control shift quality. It consists of supply line pressure regulation system, solenoid valve, pressure control valve (PCV), and wet clutch. This paper presents a dynamic model of the shift control system and conducts simulation based on AMESim software. The simulation model is then validated against experimental data. Because the model derived is complex, highly nonlinear and high order, which is not suitable for use in controller, the model simplification is carried out based on an energy-based model order reduction method. The results confirm that simulation analysis with AMESim can predict hydraulic system dynamic response accurately and the model simplification is instructive for controller design.