Nonlinear Modeling and Analysis of Direct Acting Solenoid Valves for Clutch Control

The purpose of this paper is to develop a comprehensive nonlinear model of a typical direct acting solenoid valves utilized for clutch control in wet dual clutch transmissions. To do so, mathematical models of the integrated electrohydraulic solenoid valve and wet clutch piston assembly are developed in the Simulink environment of Matlab. Through simulation the operating characteristics of the control valve are analyzed, demonstrating that the valve achieves dual functionalities of high flow and accurate pressure control depending on demands. This is realized through the designed force balancing of the valve spool. The dependency of the system to system variables on input pressure and the influence of air content on dynamic response of the valve are investigated. The resilience of output pressure is demonstrated to these variables, indicating strong system reliability. Finally, the model is then validated using in situ experimental testing on a powertrain test rig. The comparison of experimental and simulated results for steady state pressure as well as step and ramp input responses demonstrate good agreement.