An electro-hydraulic water proportional directional valve with coaxially dual-drive servo mechanism and its control performance

The switch valve commonly used on the mining hydraulic powered roof support (HPRS) has disadvantages of large pressure shock and discontinuous flow rate, making it difficult to achieve accurate control of the position and posture of HPRS. This not only affects the production efficiency of mining equipment but also poses potential risks to the safety production in coal mining engineering. To address these issues, this study develops a highly compact 3/2 water proportional directional valve (PDV) equipped with improved dual-drive servo mechanism. The mathematical model of the PDV is established, followed by analysis and optimization of key parameters affecting its dynamic response characteristics using Design of Experiments (DOE) and Sobol methods. In the step response process, the opening delay time, opening time and closing time are 4 ms, 9 ms and 31 ms respectively. The above indicators are 0.04s, 0.961s, and 1.02s in the ramp response process. A pressure-displacement correlative experimental method is proposed to indirectly reflect the displacement of the main inlet spool. Simulation and experimental results demonstrate that the newly developed PDV exhibits excellent dynamic response characteristics, enabling continuous, stable, low impact, and high-precision open-loop control of the main inlet spool. Experiment with load characteristics proves that proportional control mode effectively mitigates pressure shock generated by the main valve during both opening and closing processes. An important conclusion about the new dual-drive mechanism is found that insufficient pilot spring stiffness could result in the leakage of the pilot valve port, which significantly decrease the dynamic performance of the PDV. • A new 3/2 water PDV with double-drive mechanism is developed. • Key structural parameters are determined by DOE and Sobol methods. • A pressure-displacement coupling experimental method is designed. • The pilot spring stiffness significantly affects dynamic response characteristics. • The new water PDV exhibits excellent steady and dynamic characteristics.