Multi-objective Optimization of High-Speed Solenoid Valve for Biodiesel Electronic Unit Pump

Background: A larger response delay of a high-speed solenoid valve will cause inaccurate fuel injection timing and imprecise cycle injection quantity, resulting in diesel engine emission and increased fuel consumption. Objective: Biodiesel as an ideal alternative fuel has exceptional advantages in energy conservation, emission reduction, and low-carbon environmental protection; however, matching with Electronic Unit Pump (EUP) and its impacts on solenoid valve operation need to be further studied. Method: In the present work, a numerical model of EUP fueled with biodiesel was established in an AMESim environment, which was validated by the experiment. Then, combined with the Design of Experiments (DOE) method, key parameters influencing the solenoid valve response delay were predicted: armature residual air gap, spring preload, poppet valve half-angle, valve needle diameter, and poppet valve diameter. Finally, taking the response delay time of solenoid valve as targets, multi-objective optimization model for high-speed solenoid valve was established using NSGA-II (non-dominated sorting genetic algorithm-II) genetic algorithm in modeFRONTIER platform. Results: The optimized results showed that the delay time of the solenoid valve closing is reduced by 6%, the opening delay time is reduced by 20.8%, the injection pressure peak is increased by 1.8MPa, which is beneficial to accurate injection quantity and the application of biodiesel in diesel engines.

Effects of Control Valve's Structure Parameters on the Circulation Characteristics for an Electronic Unit Pump

The control valve is an essential component of electronic unit pump (EUP) fuel injection systems; it controls the flow rate with high-precision electrical signals. Thus, high precision and flexibility are required in the working process of a fuel injection system. The flow capacity (indicated by mass flow rate) of a control valve is an important technical indicator in the discharge of EUP fuel injection systems. In this study, the transient flow characteristics within control valve during the discharge of an EUP were evaluated using a computational fluid dynamics (CFD) approach. Three essential structural parameters of EUP control valve were investigated, and their effects on circulation characteristics were evaluated. The variation trends were observed, and the changes in significant physical parameters and crucial physical field distributions were analyzed. During the investigation, the visualization of internal flow of control valve provided more detailed information of flow fields. This study shows the effect of each parameter on flow characteristics and indicates that cavitation is the lowest for the case of 0.20 mm valve core lift; the length of slit is the shortest for the case of 7 mm seal diameter, therefore, the mass flow rate of export is the highest; at 139 deg seal cone angles, fuel velocity is the highest, therefore, 139 deg is the best seal cone angle.