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Due to the large pressure difference between the front and back of the valve, the pilot-operated regulating valve is prone to blocking flow, and there are multiple closed cavities connected by small holes in the valve, and the flow channel is complex. If the structure design of the spool component is improper, it will seriously affect the safe and stable operation of the regulating valve. In this paper, based on the principle of multi-stage step-down and compressible medium throttling equation, the structure of the pilot valve spool assembly is preliminarily designed to prevent blocking flow. The main influencing parameters affecting the stability of the valve core of the pilot regulating valve are analyzed, and the sample space is designed by the orthogonal method. The numerical simulation analysis of the force of different test samples under different openings is carried out to study the influence of different structural parameters on the force of the valve core. Based on the trend analysis of range and influencing factors, the influence of structural parameters of regulating valve on the stability of the valve core and the optimal structural parameters of valve core assembly under this working condition are studied. ANSYS CFX software was used to calculate the flow field in the valve under the optimal working opening of different experimental samples of the control valve, and the flow field in the valve and the force of the valve core of different test samples were obtained. The analysis results show that the structural parameters affecting the stability of the spool mainly include the equivalent diameter of the main spool opening, the effective diameter of the pilot valve seat throttling, and the pilot valve damping hole. The experimental sample 16 has a large force in the whole adjustment range, floating around 12 % of 1700 N. Under the small opening of the pilot-operated regulating valve, the equivalent diameter d of the main spool opening has the greatest influence on the force of the spool. When the opening is 40 %–80 %, the structural parameter that has the greatest influence on the force of the pilot control valve spool is the main spool lifting height h. In the optimal working range of the regulating valve (30%–70%), the structural parameter that has the greatest influence on the force of the pilot regulating valve spool is the lifting height of the pilot valve spool, and its optimal size is 4.0 mm. The opening diameter of the main valve core has the second influence on the force of the valve core, and its optimal size is 2.0 mm.
Li et al. (Sun,) studied this question.