Modeling and experimental validation of the solenoid valve of a common rail diesel injector

Common rail diesel injectors are multi-domain systems with complex interactions between mechanical, hydraulic and electrical components. For a detailed understanding of the dynamic behavior and for further performance improvements, often simulation models are indispensable. Injection dynamics is influenced by the opening and closing dynamics of the solenoid valve. Therefore an accurate simulation model of the solenoid valve is necessary for injector simulations. The objective of this study is to present a validated simulation model of the solenoid valve of a commercially available common rail diesel injector. For modeling the solenoid valve, a division into a mechanical and a magnetic submodel is done. The mechanical submodel is made up by a two mass system representing the pin and the armature of the solenoid valve. Contacts are modeled using linear-elastic spring-damper elements and viscous damping is considered for friction representation. The magnetic submodel is based on experimentally gained static magnetic force data. Therefore a test bench is presented, that allows to measure magnetic force-current characteristics of the solenoid at operation relevant air-gap values. Investigations by the author have shown, that transient effects of the solenoid during switching on and off the supply current cannot be neglected. In this study a semi-empirical approach is proposed to account for these transient effects, which are mainly caused by eddy-currents. In order to validate the model of the solenoid valve, dynamic displacement measurements of the pin are carried out. Comparisons between simulated and measured pin displacement data show excellent agreement.