Research on the dynamic characteristics of water hydraulic servo valves considering the influence of steady flow force

The International Thermonuclear Experimental Reactor remote-handling (ITER-RH) system powered by water hydraulics is a vision of the future. The 2D servo valve is a new type of servo valve, maybe suitable for the ITER-RH system. It has many advantages, including its fast response and strong anti-pollution ability. However, steady flow force is currently considered to be one factor that impacts the dynamic characteristics of servo valves. In this study, the influence of steady flow force on the dynamic characteristics was analyzed, and the structure was optimized accordingly. A mathematical model of the servo valve was built using theoretical analysis and numerical simulation. Results indicated that the amplitude bandwidth of the 2D water hydraulic servo valve was 169 Hz without considering the steady flow force, and it decreased to 162 Hz when the steady flow force was considered. Furthermore, a newly designed valve sleeve, to compensate for the axial steady flow force, was proposed by changing the angle of the inlet port designed in the valve sleeve to the spool axis. The maximum compensation capacity of the axial steady flow force was 35%, and the best angle of the inclined holes was approximately 120°. The optimized amplitude bandwidth of the 2D servo valve was 167 Hz. The results demonstrate that the optimized valve sleeve improved the dynamic response of the 2D servo valve.