Research On Pressure Characteristics Of Intelligent Fluid Supply System Of Hydraulic Support

With the increasing demand of coal consumption in China,high efficiency and high production has become the pursuit goal of coal mining,and the development of coal industry in the direction of intelligence has become a necessary trend.At present,the pressure fluctuation and impact of the hydraulic support liquid supply system is large,so it is difficult to realize the accurate displacement control of each actuator of the hydraulic support;the pressure changes greatly under different working modes of the hydraulic support,which seriously affects the speed of the hydraulic support to follow the machine.The hydraulic support liquid supply system has a decisive influence on the running efficiency of the support following machine.Improving the liquid supply quality of the hydraulic support liquid supply system is one of the core technologies to realize the intelligence of coal mines.Therefore,the research on the technology of reducing pressure fluctuation can ensure the speed of hydraulic support and provide technical support for the realization of the intelligent coal mine.Firstly,in view of the large fluctuation of system pressure in the current hydraulic support liquid supply system,an intelligent hydraulic support system is proposed,and its control principle is theoretically analyzed.By analyzing the pressure regulation principle and working characteristics of the existing unloading valve,a digital unloading valve for the intelligent hydraulic supply system of hydraulic support is designed,which can slow down the opening and closing process of the unloading valve and realize the Pressure shocks and flow pulsations caused by the opening and closing of digital relief valves.Secondly,the simulation models of digital unloading valve and mechanical pilot valve are established respectively.The dynamic characteristics of the opening and closing process of the digital unloading valve and the mechanical unloading valve are compared and analyzed,and the influence of the main parameters on the dynamic characteristics of the digital unloading valve is simulated and studied.It is concluded that the digital unloading valve can effectively slow down the opening and closing process of the unloading valve main valve,and can effectively slow down the pressure shock and flow pulsation caused by the sudden opening and sudden closing of the valve core.For the inlet orifice of the pilot valve of the digital unloading valve,increasing the diameter and reducing the length can effectively reduce the flow overshoot of the main valve,reduce the impact,and reduce the range of system pressure fluctuations;for the orifice of the main valve control circuit,Reducing the diameter and increasing the length can effectively reduce the flow overshoot of the main valve and reduce the impact on the system,but the range of system pressure fluctuation becomes larger.The damping hole parameters at different positions have different effects on the stability of the unloading valve.Too good or poor throttling damping effect will easily cause the unloading valve to become unstable;increasing the spring preload and spring stiffness of the main valve can increase the unloading The valve loading pressure has little effect on the flow overshoot of the main valve;increasing the half cone angle of the main valve reduces the unloading pressure and loading pressure of the unloading valve,and the flow overshoot of the main valve increases.Then,according to the schematic diagram of the hydraulic support intelligent liquid supply system,its simulation model is established.The influence of liquid supply volume,leakage volume and pipeline length on the system pressure fluctuation characteristics was analyzed when the support was not in action;the rated liquid supply flow rate system and the intelligent liquid supply system were simulated and compared for different support action types and support action numbers.,to verify that the intelligent liquid supply system achieves the goals of reducing pressure fluctuations and ensuring the running speed of the support,effectively improving the liquid supply quality of the hydraulic support liquid supply system,and using the downhole measured pressure data to verify the effectiveness of the simulation model.Finally,by building a hydraulic support liquid supply system test platform,the system pressure and flow are measured by using a pressure transmitter and a flow sensor.The test results are compared with the simulation results to verify the reliability of the simulation again.