Design And Research Of Large Flow Safety Valve For Hydraulic Support

As an important production equipment in coal mine collection work,hydraulic support can be used to control coal pressure of coal mining face and provide reliable working space for coal mining equipment.The safety valve is the key component in the hydraulic system of the hydraulic support,which plays the role of control and protection for the support.Once the safety valve fails,it will lead to the column cylinder burst or the piston rod fracture and bending when the support is working,which poses a serious threat to the life safety of coal mine production and staff.Therefore,it has important theoretical and practical value to study the safety valve for hydraulic support circuit protection.According to the design standards and performance indicators,combined with the working characteristics of various structural safety valves,a differential large flow safety valve is designed.According to the working principle and theoretical formula of the safety valve,the size structure of the safety valve is determined,and the balance chamber structure is optimized and adjusted.The internal flow field of the safety valve is simulated by using the fluid calculation software pumplinx.It is found that the annular groove with a diameter of 10 mm can achieve rapid pressure relief at the outlet of the safety valve,but it will also lead to backflow and vortex at the outlet.Therefore,the difference between the annular groove on the valve body and the outlet should be less than 1 mm.The flow field of the optimized 8mm annular groove safety valve with opening percentage of 20%,42% and 100% was simulated.The results show that with the increase of the opening amount,the flow field inside the valve core is divided by the two outlets of the valve body,and there are three obvious pressure zones from the inlet to the balance chamber,in which the pressure at the inlet end is the minimum and the velocity is the maximum;The balance chamber has the largest pressure and the smallest velocity.And with the increase of the opening,the mass flow difference between the two outlets of the valve body will increase with the increase of the longitudinal internal and external pressure difference between the two outlets of the valve bodyAMESim software is used to simulate the safety valve under the condition of constant current source,and the influence of spring stiffness,damping hole,spool quality and other factors on the characteristics of the safety valve is analyzed.Firstly,the safety valve with different spring stiffness is simulated,and it is found that the pressure overshoot and valve core vibration amplitude of the safety valve will increase with the increase of spring stiffness.Through comparative simulation,the optimal value of spring stiffness is 160 n / mm.The results show that the inlet pressure overshoot will decrease with the increase of the diameter of the damping hole,but the vibration amplitude of the valve core will increase with the increase of the diameter of the damping hole.Through simulation analysis,the optimal value of the diameter of the damping hole is 2.6 mm.It is found that when the total overflow area is less than the inlet area,the pressure value of the flow field inside the valve core is very high,and the pressure overshoot is very small;When the total overflow area is larger than the inlet area,the inlet pressure overshoot will increase with the increase of overflow hole diameter.However,the overlap amount,spool mass and differential area have little influence on the design of the safety valve.According to the designed safety valve,the accumulator loading impact test model is established.The accumulator is flushed for 20 s and 17 s,and the impact test is carried out on the safety valve.The simulation results show that the safety valve has good dynamic characteristics.In this paper,combined with theoretical design and simulation,a new type of safety valve is designed,and its internal flow field characteristics and opening characteristics are studied,which is of great significance to improve the design system of high pressure and large flow safety valve and coal mine safety production.There are 63 figures,8 tables and 57 references in this paper.