Abstract
Solenoid has been widely used as a highly reliable and short stroke actuator. However, the main defects are the delay of the actuator motion and its low driving efficiency. Analyzing the various driving parameters, three major factors of solenoid delay are found: mechanical delay caused by movable inertia, current delay by solenoid inductance, and magnetic flux delay by eddy-current. This paper introduces two improvement methods: a driving circuit which utilizes the constant current of a choke coil to make the solenoid current response faster, and a ferrite core which is widely used as a radio frequency magnetic material to decrease the eddy-current loss. These ideas reduce both current delay and magnetic flux delay and also improve the driving efficiency of the actuator. The resulting motion indicates a very small dead time, which is considered very good for servoactuator.
High speed solenoid actuator is applied to develop a direct-drive servo-valve and a linear hydraulic servo system. A lthought here is room for improvementt, h e results indicatet he capability of this solenoid actuator to the highly efficient servo system.