Abstract
In recent years, oil hydraulic spool valves have been widely used in electricmechanical control systems. However, the steady axial flow forces in the oil hydraulic spool valves are produced by the internal oil flow, and control of oil hydraulic spool valves becomes difficult owing to the effect of the steady axial flow forces.
In this paper, whole domain of fluid inside a spool valve is simulated by the boundary element method.Shapes of sleeves are modified, and steady axial flow forces, flow patterns and boundary pressure distribution are calculated and compared. It is found that when a sleeve takes a shape shown in Fig.6, the steady axial flow forces applied on the spool are greatly decreased, and the angle θn of injection fluid at jet orifice also increases due to coanda effect of the flow.
