According to the function and operating characteristics of water hydraulic relief valves in a high-pressure water pipe system, a novel one-stage relief valve with a one-way damper was designed and analyzed in this study. The one-way damper consists of a damping chamber and a check valve. Moreover, a damping orifice is bored along the axis of the check-valve spool. When the main spool moves to open the valve port, the check valve is fully open, and the damping orifice generates no damping force on the main spool; otherwise, the check valve is completely closed, and the damping orifice produces a damping force on the main spool. Furthermore, based on a mathematical model describing the dynamic characteristics of the relief valve, the effect of the one-way damper on the dynamic characteristics of the relief valve was simulated and analyzed, and certain optimal parameters of the one-way damper were obtained (e.g., the diameter and length of the damping orifice and the initial volume of the damping chamber). Lastly, the experimental results obtained from a prototype of the relief valve, which was manufactured to the optimal dimensions, demonstrated that the pressure overshoot was 7.5%, the response time was 1.43 × 10−2 s, and the transition time was 3.9 × 10−2 s. Thus, the one-way damper could significantly improve the dynamic characteristics of the relief valve.
Water hydraulic components have been developed rapidly in recent years. However many problems such as low lubricity and leakage limited the performance of them, especially water proportional valves. A proportional valve- hydraulic cylinder system with tap water as working medium is chosen as object to investigate the performance of water hydraulic system. With regarding to the weaknesses of the selected 4/3 proportional valve including lag, dead zone and nonlinearity, an integral separation PI arithmetic based close-loop controller is developed. Experiments results verified the electro-hydraulic proportional system of fast response speed and high accuracy.
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