Study on static and dynamic characteristics of the electro-hydraulic proportional directional valve

Electro-hydraulic proportional directional valves are widely used in precision engineering fields, where their operational stability and reliability are critical to the performance of hydraulic systems. However, high pressure and high-frequency responses significantly affect the hydraulic forces acting on the spool, while deformations caused by pressure and thermal loads may further compromise its performance. Therefore, analyzing and compensating for hydraulic forces, as well as investigating the deformation behavior of the spool under pressure and thermal loads, are essential for enhancing its stability and reliability. Based on CFD numerical calculation methods and fluid-thermal-solid multi-physics coupling technology, the study systematically investigates the characteristics of hydraulic forces and the deformation behavior of the spool. First, Fluent was used to simulate the fluid domain under steady-state and transient conditions, obtaining pressure and velocity contour maps, flow rate curves, and the hydraulic forces acting on the spool in different structural cavities formed by the valve sleeve and spool at different valve opening degrees. The analysis identified the best cavity configuration for compensating hydraulic forces between the valve sleeve and spool. Secondly, orthogonal experimental design and numerical simulation were conducted for the arc-shaped transition cavity, followed by multi-objective optimization using a genetic algorithm. The optimized structure reduced the steady-state hydraulic force to varying extents, with a maximum reduction of 23%. Finally, the fluid-thermal-solid multi-physics coupling technology was employed, selecting the optimal structure with the best hydraulic force compensation effect for analysis. The results show that the deformation of the spool in both radial directions increase as the valve opening increases. At a valve opening of 1 mm, the maximum radial deformation in the Z direction is 7.0471 μm. Additionally, with the increase in temperature, the maximum deformation in both the Y and Z directions shows a linear growth trend.