Thrust Analysis of the Linear Proportional Solenoid for a Hydraulic Control Valve

The linear proportional solenoid (LPS) is an actuator for a proportional control valve used in hydraulic pressure-control devices. The LPS must have a constant thrust over a designated displacement range, and the thrust must also increase in proportion to the exciting current. This paper deals with the effect of using dither to remove hysteresis phenomena, and describes numerical solutions for the thrust F and displacement x, which are characteristics of the LPS. Dither is a useful small-amplitude oscillation which is introduced to overcome the effect of hysteresis. When dither is applied, the maximum hysteresis of the thrust is decreased from 6% to 3%. The LPS consists of four different magnetic materials, and its F-x characteristic was calculated by the finite element method (FEM). The calculated F-x characteristics approximated the measured results to within an error of 2%. A newly proposed LPS, which maintains constant thrust over a broader range, is also described.