Experimental Research on Variable Hydraulic Resistors of Servo-hydraulic Valves

For the nowadays industry, the hydrostatic actuation is indispensable, thus reducing the energy losses in valves that control the parameters of hydraulic energy, it has become an area of interest in applied research. The paper aims to conduct a study on hydraulic resistors, following the hydrodynamic forces that appear in an adjustable valve like a load for the valve actuator. Three types of holes (circular, rectangular, triangular) for the sleeve were assembled with each of the three spools chamfered at different angles resulting different geometry for the active edge. The results show that the variant in which the openings are rectangular and the edge of the piston is tapered at an angle of 60°, develop the lower hydrodynamic force and thus lower energy dissipation. The paper presents the experimental setup used, which offers the possibility of monitoring also the noise during operation, being able to establish the time of cavitation occurrence using spectral analyzes. The optimizations achieved by reducing the hydrodynamic forces, are important in terms of energy.