Effects of multiple factors on water hammer induced by a large flow directional valve

© 2018 Journal of Mechanical Engineering. All rights reserved. The flow gain of the large flow poppet directional valve presently used on hydraulic-powered support is large, so water hammer occurs easily when the poppet valve closes. Thus, the hydraulic system, its components, and human safety are seriously threatened. To solve this problem, a plane-sealed large flow directional valve with different throttle windows, which must be taken into consideration when the mathematical model is established, is designed. The effects of spring stiffness and the shape of the throttle window on the hydraulic shock induced by the valve are analysed with the combination of simulation and experiments. It is obvious that the bigger the spring stiffness is, the greater the water hammer is produced. When the spring stiffness continues to increase, the valve becomes instable and causes much stronger water hammer. The area gains of the valves with different throttle windows (round type, triangular type, rectangle combined type) are different, and the corresponding instances of water hammer differ accordingly. Compared with the common round throttle window, the triangular window produces the lowest shock. Furthermore, the effects of the closing time and the type of control curve of the main valve on the water hammer are explored. It is helpful for the proportional control of the large flow water directional valve in the future. This study provides valuable references for the design of the large flow water valve and the corresponding control of water hammer.