Fluid-dynamic design optimization of hydraulic proportional directional valves
This article proposes an effective methodology for the ﬂuid-dynamic design optimization of the sliding spool of a hydraulic proportional directional valve: the goal is the minimization of the ﬂow force at a prescribed ﬂow rate, so as to reduce the required opening force while keeping the operation features unchanged. A full three-dimensional model of the ﬂow ﬁeld within the valve is employed to accurately predict the ﬂow force acting on the spool. A theoretical analysis, based on both the axial momentum equation and ﬂow simulations, is conducted to deﬁne the design parameters, which need to be properly selected in order to reduce the ﬂow force without signiﬁcantly affecting the ﬂow rate.
A genetic algorithm, coupled with a computational ﬂuid dynamics ﬂow solver, is employed to minimize the ﬂow force acting on the valve spool at the maximum opening. A comparison with a typical single-objective optimization algorithm is performed to evaluate performance and effectiveness of the employed genetic algorithm. The optimized spool develops a maximum ﬂow force which is smaller than that produced by the commercially available valve, mainly due to some major modiﬁcations occurring in the discharge section. Reducing the ﬂow force and thus the electromagnetic force exerted by the solenoid actuators allows the operational range of direct (single-stage) driven valves to be enlarged.