Theoretical research on the dynamic characteristics of electrohydraulic servo valve (EHSV) in deep sea environment

Electrohydraulic servo valve (EHSV) is a key component in deep-sea manipulator. Traditionally, it is recognized that the EHSV can be used just as on land because the pressure of sea depth is compensated and only the physical characteristics of working media needs to be considered. However, this is not the real situation. In this paper, the influences of structure deformation and working media on the dynamic characteristics of EHSV were considered. The mathematical model of EHSV was established, and the deformation of the spool and the valve sleeve under different seawater depths were simulated by ANSYS Workbench. The different fitting clearance under different seawater depths were obtained, and the dynamic performance of EHSV in deep sea environment was studied. The dynamic characteristic curve of the valve and the dynamic characteristic parameters such as setting time were obtained. The simulation results indicated that with the increase of seawater depth, the clearance between the spool and the valve sleeve was reduced, and setting time increased dramatically. At 12,000 m, the overshoot of the step response exceeds 40%. In addition, due to the deformation of the structure, the step curve of EHSV fluctuates near the stable value, the dynamic performance of EHSV deteriorated.