The Research On Stability Of Counterbalance Valve In Over-running Load Condition

Hydraulic counterbalance valve is component, which refers to that in hydrauliccounterbalance circuits, it can produce certain back pressure and use to balance the weightof the actuators, in the over-running load condition and prevent the moving parts ofexecutive component free falling due to the influence of gravity, as a result it cause seriousaccidents, and achieve control actuators drop speed and improve overall hydraulic stiffness.Hydraulic balance valve in balancing circuit can realize the balance of the system smoothly,whose performance directly influences the whole machine working smoothly, reliabilityand efficiency of system. Hydraulic balancing valve is a key component in hydrauliccounterbalance circuits to achieve balance function, its performance is directly related tothe work of the machine stability, reliability and efficiency of the system.Hydraulic lifting system is an important subsystem of the truck crane hydraulicsystem, whose functions are to achieve weight lifting and falling. In the process of heavyfall, when the movement direction of the load and hoisting are the same, that is, inover-running load condition, the system is prone to produce pressure surges and thedynamic performance of instability. Under the condition of closing motor variables andinvariable hoisting, the influence factors of the stability of hydraulic lifting system aremainly concentrated in the counterbalance valve of the lifting system. Therefore,researching the relationship between counterbalance valve structural parameters and thestability of hydraulic lifting system has the theoretical and practical applicationsignificance.This dissertation is funded by the University-enterprise cooperation project of " Atransformation of domestic counterbalance valve " and develop the relationship betweencounterbalance valve structural parameters and the stability of the truck crane liftingsystem. in over-running load condition, weight lifting system declines jitter as the research object, based on AMESim (Advanced Modeling Environment for Simulations ofengineering systems) software simulation platform, counterbalance valve and variablemotor are established, as well as hydraulic lifting system a HCD(Hydraulic ComponentDesign) model of hydraulic lifting system, respectively. By using transfer functionmethod and dynamic simulation analysis and experimental verification methods, we studythe relationship between the hydraulic lifting system and the structural parameters ofcounterbalance valve. The main contents of this project can be summarized as following;(1)The working principle and defects of several kinds of common balance loop areanalyzed, respectively; then compare the current development of domestic and foreigncounterbalance valve.(2)Introduce the oil control counterbalance valve work principle; the mathematicalmodel of single-stage counterbalance system is established based on a transfer functionmethod.(3) The HCD model of the counterbalance valve and variable motor developed in theAMESim environment, respectively. According to the inherent characteristics of thecomponent, set parameters, verify the correctness of the model HCD. On the basis of themodel is correct, set the model of the hydraulic lifting system.(4)Experiments were carried out aimed to study the dynamic performances of thehydraulic lifting system. Mainly, in the process of hoisting falling, zero load and10t load,the motor load pressure, volume raise pressure, winding down were carried on thesimulation and experimental validation, respectively. The experimental results agree withthe simulation results, it validates the correctness of the simulation model and the relatedtheory.(5)Hydraulic winch system HCD model, respectively Poppet spring, the control pistonarea, the relationship between the pre-compression force of the valve orifice area gain anda spool spring and hydraulic winch system stability were studied between. Based onHydraulic lifting system HCD model, the relationship between the spring of valve core,control piston area, valve core and valve throttle mouth area of gain and thepre-compression force of the valve core spring and the stability of hydraulic lifting system is studied.