Effects of design and operating parameters on the static and dynamic performance of an electromagnetic valve actuator

The electromagnetic valve (EMV) actuation system is a new technology for improvement in fuel efficiency and reduction in emissions in spark ignition (SI) engines. It can provide more flexibility in valve event control compared with conventional variable valve actuation devices. However, a more powerful and efficient actuator design is needed for this technology to be applied in mass production engines. This paper presents the effects of design and operating parameters on the static and dynamic performances of the actuator. Employing the finite element method (FEM), the flow pattern of the magnetic flux is analysed and the resultant magnetic forces of several cases of core and armature designs are calculated. A computer simulation model has been set up to identify the dynamic behaviour of the EMV system. The effects of external disturbances such as cylinder pressure, armature neutral position and current supply time are also analysed. To verify the accuracy of the simulation model, an experimental study is also carried out on a prototype actuator. It is found that there is relatively good agreement between the experimental data and the results from the simulation model. The newly designed actuator is successfully operated on the test bench up to about 6000 r/min, which is the range of rated speed of most production SI engines. Through the whole speed range, the actuator maintains good performance in valve timing and event control.