Abstract
The large flow electro-hydraulic directional valves are the key operating components for automation of the hydraulic roof supports in the coal mine. Cracking is a common failure mode of the valve. Effects of the buffer damp diameter, the valve type and the static pressure on the stress of the valve were researched. The valve dynamic behavior was investigated by AMESim. The transient collision stresses of the inlet valve sleeve of the main control valve under different buffer damp diameters and different valve types were investigated by ANSYS/LS-DYNA. The static stress analysis was conducted in ANSYS too. Results show that the valve failure is due to the fatigue of the inlet valve sleeve when suffered from the collision stress wave in the valve opening process, rather than the lack of component strength. The buffer damp diameter, the key parameter of the valve, has a significant effect on the collision stress of the inlet valve sleeve. The integrated type valve has a better stress state compared to the separated type valve. This paper provides an effective method to solve the fracture problems of hydraulic directional valves. It is also significant for the design and optimization of hydraulic components.