Research On Engine's Electromagnetic Valvetrain

In engines equipped with electromagnetic valvetrain, the motion of the valves can be flexibly controlled as the engine working condition varies. Thus the engine's fuel economy, emissions and torque output performance will be significantly improved. The electromagnetic valvetrain is known as a novel fully flexibly variable valvetrain with simple structure, quick system response, and excellent valve seating performance. In this thesis, an electromagnetic valvetrain based on moving coil linear actuator was presented and researched by theoretical analysis, simulation and experiment. This thesis lays a foundation for further research and development of the electromagnetic valvetrain.The main works and fruits of the thesis are as follows:(1) Some types of electromagnetic linear actuator were evaluated based on the require-ment of electromagnetic valvetrain. The system scheme of the electromagnetic valvetrain was presented based on the moving coil electromagnetic linear actuator, and the system working principle was analyzed. Two electromagnetic valve actuator prototypes were developed aims at using in internal combustion-linear generator, and meeting the high engine speeds and limited mounting space, respectively. The design details of electromagnetic valvetrain were presented.(2) The multi-field coupled system model of electromagnetic valvetrain were established. The configuration of electromagnetic valvetrain was designed by finite element analysis, and the electromagnetic force was obtained. The influence of system parameters on system char-acteristics was obtained by system simulation, the dynamic performance of electromagnetic valvetrain was also obtained. The system simulation models were established based on Mat-lab/Simulink and Maxwell&Simplorer respectively. The superiority of multi-field coupled sim-ulation has been demonstrated. The simulation model provides a powerful platform for control methodology.(3) The thesis presents an sectional valve motion control strategy for electromagnetic valvetrain based on inverse system method. By linearization of the nonlinear electromagnetic valvetrain system, a pseudo linear system can be obtained. The state feedback control is used to control the valve motion. A state variable observer was designed to estimate the unmeasurable state variables. The proposed control method was also compared to the PID control method in simulation. The seating performance evaluating indicators were proposed. The control of valve seating velocity and holding force was investigated. Both the theoretical analysis and experiment show that the inverse system method is effective.(4) The power consumption of electromagnetic valvetrain was analyzed in the thesis. The detailed power losses derivation of electromagnetic valvetrain was discussed. Then the power consumption at various engine speeds and valve operating modes were obtained by experi-ments. An engine performance simulation model was established, and the power consumption and pumping losses at various valve operating modes were shown and compared, which lays a foundation for valve operating modes selection.(5) The control system of electromagnetic valvetrain was built based on DSP. The static and dynamic experiment setup were also developed, and the system experiments were carried out. The simulation results were compared with the experiment results, and the simulation models prove validity. The freedom and stability of the electromagnetic valvetrain were eval-uated, which lay a foundation for the further research and application of the electromagnetic valvetrain.