Evaluation of Hydraulic Pressure Drop using Manganin Wire and a Wiper-Cam-Operated Directional Valve

摘要

In this paper, we have constructed equipment to be effective in generating a hydraulic pressure drop that can be employed as a step function, mainly by means of a cam mechanism that operates a spool-type directional control valve and measures the pressure with a manganin wire and a Wheatstone bridge system. The wiper cam is specially designed to operate a hydraulic piston with quick return and to generate a pressure drop in the testing chamber within an extremely short time. Results show the pressure drop from 250 bars to zero requires only 0.45 ms. Furthermore, we also compare the characteristics of pressure drop with various chamber volumes and spool valve overlaps. Results show the best pressure-drop rate when the chamber volume and overlap are 4 cm~3 and 4 mm, respectively.