Proactive fault finding in a 4/3-way direction control valve of a high pressure hydraulic system using the bond graph method with digital simulation

A bond graph model has been developed in this paper concerning a high pressure industrial hydraulic system. The accuracy of the bond graph model was verified by comparing its response to the response of an actual hydraulic system and the correlation of these results is high concerning the shape, magnitude and response times. Three different tests were conducted, depending on the motion profile of the valve spool, from which an important conclusion drawn is that a long duration in the valve spool return motion has the most noticeable effect on the maximum vertical travel of the load as it significantly reduces the load oscillation amplitude after the load has reached its topmost position. What follows is an increase of the residual pressure in the hydraulic cylinder top chamber with a lesser effect on the load maximum velocity. The results of this work are used for proactive fault finding in cases of valve spool malfunctions, particularly anomalies during the valve spool motion and can be used to optimize the valve spool motion profile.