Abstract:The traditional proportional relief valve shows great pressure fluctuation and pressure deviation because the regulating spring stiffness is not enough under high pressure or large flow conditions, which makes the pressure regulating spring easy to fatigue and increase vibration and noise, it can reduce its life and reliability. The electro-hydraulic proportional relief valve with dynamic pressure feedback pilot chamber was studied based on G-type π bridge hydraulic resistance network, and the design method of hydraulic stiffness instead of spring stiffness of pilot valve was proposed, so it can improve response speed of the pilot valve core and stability to reduce pressure fluctuation and pressure deviation and there was no spring fatigue. Further structure and principle, theoretical modeling and simulation analysis of the new relief valve were carried out, the prototype was machined according to the optimized structure parameters and the dynamic and static characteristic of the new valve was verified by experiments. The results showed that the pressure deviation of the new relief valve was low under high pressure condition, especially it was 72% lower than that of traditional proportional relief valve and the minimum was 0.53MPa when the inlet pressure was 26.25MPa. In addition, it had good dynamic characteristics, the minimum pressure overshoot was 0.94%, and the spool vibration was decreased and worked smoothly. Finally, the relief valve was used in ZL50G loader to replace the relief valve and back pressure solenoid valve on the original moving arm oil circuit, and the influence of the relief valve on the operation of the working device under no-load condition was analyzed. The pressure fluctuation of the relief valve was reduced by 70% and the vibration and noise of the system were reduced.
