Dynamic Characteristics And Control Methods Of Large Flow Water-based Proportional Valve For Mine

Intelligent mechanized mining equipment is the only way for the development of the wisdom of mine.As one of the "three machines" in fully mechanized mining,the hydraulic support supports and manages the coal seam roof,It provides safe working space for underground personnel and equipment,It also cooperates with the scraper conveyor and coal shearer to carry out self-moving operations such as sliding,pulling,posture adjustment.Electro-hydraulic control valve as the core control element,its characteristics greatly affect the effect and safety of hydraulic support.At present,all hydraulic supports are controlled by large flow switching valves.Since the flow cannot be continuously adjusted,there are two problems in use:On the one hand,the positioning of the hydraulic cylinder is inaccurate,resulting in inaccurate adjustment of the support posture and push-pull position,affecting the support effect of the hydraulic support on the top plate and the straightness control of the support and push-slip.On the other hand,the on-off valve directly opens and closes,and the flow rate changes abruptly,resulting in severe pressure impact,which is easy to cause damage to pipelines,joints,seals and other components.For this phenomenon,the urgent need to address the flow of hydraulic support uncontrollable problems.The thesis clarifies the working principle of the new large-scale water-based proportional valve for mining.And establish the mathematical model of each subsystem such as pilot valve and main valve,and establish the mathematical model of the whole valve.Using the AMESim simulation platform,analyze the influence of various parameters of the pilot return spool on the dynamic characteristics of the entire valve.Analysis of dynamic response characteristics of the triangle wave,square wave,ramp,step,etc.entire valve control signal to optimize the parameters of the valve body structure and a control signal.Aiming at the problem that there is more nonlinear interference in the proportional valve,resulting in hysteresis and serious oscillation in the hydraulic circuit.In this paper,the friction characteristics of the proportional valve are studied,and experiments are conducted to analyze the relationship between the friction force of the proportional valve and the pressure and the movement speed of the valve core.Finally get the modified friction Lu Gre model,this is of great significance to eliminate the harm caused by friction and improve the control accuracy of the proportional valve.At the same time,it can provide an accurate theoretical model for the compensation of friction nonlinearity.Aiming at the problem of low spool position control accuracy,the thesis designs a fuzzy PID position controller to correct the position of the main spool.Simulink and AMESim are used to carry out joint simulation to analyze the response characteristics of the spool position under the fuzzy PID controller.The results show that under the optimization of the fuzzy PID controller,the action process of the proportional valve is more stable,indicating that the fuzzy PID control method can make the proportional valve have better response performance.Theoretical modeling and simulation studies show that the position feedback can be used to control the position of the spool,and then achieve the purpose of flow control,which provides a certain reference for the development of the test prototype of the hydraulic support water-based proportional valve.