1996 Volume 1996 Issue 3 Pages 385-390
Switching-and proportional-solenoid valves are mass-produced components for electrohydraulic servomechanisms. Quality of a servomechanism depends on the valve-dynamics and it is important for valves to respond as quick as possible. Main delay of a valve is resulted usually from the time-constant of solenoidinductance. It is compensated easily by energizing the solenoid with a highvoltage over-excitation circuit. However more quick operation is prevented from the eddy-current in the magnetic circuit. It interferes to permeate magnetic-flux into an armature. This paper clarifies the affect of eddy current on the switching speed of on/off-and proportional-solenoids by measuring the transient characteristics of the electric current and magnetic fl ux-flow, and next by calculating transient flux-flow on the process of permeating into the armature with the aid of newly-programmed FEM analysis. Over-excitation energizing and low-conductive material shorten the delay of a switching-solenoid valve from 7.9 ms to 0.8 ms and of a proportional valve from 40 ms to 1.7 ms.
