Numerical and experimental investigation on opening direction steady axial flow force compensation of converged flow cartridge proportional valve

This paper proposes a method to optimize a structure that can compensate the steady axial flow force acting on the spool in a converged flow cartridge proportional valve. The negative flow force working on the origin conical poppet, which can be as large as 13% of the control force, acts as a big disturbance to the conical spool position adjustment, resulting in poor lowering speed control performance of the proportional valve or even instability of the conical spool. Firstly, by introducing a damping tail structure to the conical poppet, the direction and the value of the flow forces can be regulated, and through changing parameters of damping tail, the optimal structure can be obtained. Computational fluid dynamics (CFD) calculations were conducted to analyze how the damping tail parameters affect the flow forces and obtain the best parameter combinations. A test rig was set up to verify the effect of above methods. Good agreement of the CFD calculations and experiment results indicates that the proposed methods can provide guidance for the flow force regulation of other valve poppets.