Improvements of quickness in high speed on-off valve

High speed on-off valve is mass-produced components for electrohydraulic serveo mechanisms. 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 solenoid-inductance. It is compensated easily by energize the solenoid with a high-voltage over-excitation circuit. However more quick operation is prevented from the eddy-current in the magnetic circuit It interferes to permeate magnetic-flux into armature. This paper clarifies the effect of eddy current on the switching speed of on-off solenoid by measuring the transient characteristics of the electric current and magnetic flux-flow, and next by calculating transient flux-flow on the process of permeating into the armature with the aid of newly-programmed FEM analysis. The author applied C2051 microcomputer controller, devised a new generator for PWM signal, thus also improved the quickness of the valve. Over-excitation energizing and low-conductive material shorten the delay of a switching-solenoid valve.