Study on the influence of flow force on a large flowrate directional control valve

This paper focuses on analyzing the characteristic of the flow forces acting on a large flowrate directional valve (1200L/min). The flow area of the notches on the spool is calculated and the mathematic model of the spool is presented. The change rule of the total steady flow force is obtained through numerical simulation. The nonlinear response of the spool valve is explained reasonably and the input forces needed to make this valve closing reliability are given out respectively. The results show that the total flow force promotes the spool movement at the beginning but suppresses it after the spool displacement reaches a certain value. Furthermore, the vibration is caused by the dynamic force balance acting on the spool, leading to the large input force to make sure the relative ports closed. It is proposed that each pair of ports of the large flowrate directional control valve should be designed to the same structure to weaken these problems.