Low flow force spool structure design and multi-objective optimization of servo-proportional valve

Servo-proportional valves are gradually being introduced into aircraft electro-hydraulic systems as performance improves. Reducing the flow force of the valves is beneficial in improving the rapidity and stability of valve operation. Meanwhile, maintaining the flow linearity of the valves in the structural design can prevent the reduction of the stability margin of the load system flow control. Therefore, a non-throttling port spool guide bevel is designed to reduce the flow force based on the relationship between the jet angle and the flow force. A step structure is designed to maintain the flow linearity and alleviate the flow force reversal problem. To obtain the best parameters of the structure, a joint optimization simulation platform is built by combining the CFD (Computational Fluid Dynamics) technique and a multi-objective genetic algorithm. Finally, the simulations show that the optimized spool structure can reduce the overall flow force by 37.3% and the maximum flow force by 28.5%, while the flow linearity is basically unchanged.