Study On The Characteristics Of Electro-hydraulic Proportional Flow Valve Based On The Flow Feedback

Poppet type metering valves have many benefits including low leakage andbig flow capacities and an economical design. It has been developed veryquickly in the past decades.80’s of last century, Professor Andersson putforward the Valvistor valve based on the flow feedback principle, whichcombining the advantages of cartridge valve and electro-hydraulic proportionaldirectional valve. The main poppet amplifies the small flow through the pilotcircuit, it has many benefits including low leakage and big flow capacities andan economical design, has become the focus of domestic and foreign scholars, itis widely used in hydraulic systems. Therefore, to study the influence ofstructure parameters on the static and dynamic performance and stability ofValvistor valve has the important theory significance to the design and theperformance improvement of the valve.This paper carries on the theoretical analysis to the Valvistor valve,according to the working principle of the valve and the flow continuity equation,a nonlinear mathematical model of the valve has been established. Throughreasonable hypothesis and linear processing, it is reduced to a first order system.The Stability criterion of the Valvistor valve is achieved according to the Routhcriterion. The structural parameters, which influence the static and dynamicperformance and the stability of the valve, are analyzed by using mathematicalmodels. The performance and stability of the valve are analyzed using the rootlocus. The results of root locus were compared with the stability criterion of theValvistor valve, to provide theoretical guidance for the simulation and experiment.Experiment bench of two stage proportional flow valve has been set up. Theexperimental data were collected using dSPACE. The static and dynamiccharacteristic of the pilot valve and the main valve have been studied by usingthe experiment bench. The hydraulic system model of the valve is established byusing the simulation software—SimulationX. Because structural parameters ofthe pilot valve are not clear, Experimental data are imported the simulationmodel, using the experimental results to correct the simulation model. Thesimulation results are consistent with experimental results, which verify thecorrectness of the simulation model. The static and dynamic characteristics ofelectro-hydraulic proportional flow valve are studied using the experimentbench and simulation model. Get the flow characteristic curve and thedisplacement characteristic curve, step response and Bode plot of the valve areobtained. The valve’s working bandwidth is about12Hz, and its frequencyresponse curve doesn’t appear resonance peak and has the feature of a typicalfirst-order lag link. The simulation results prove the validity of the theoreticalanalysis. Experimental and simulation results show that increasing the pressuredrop and the width of the slot will increase the response speed of the spool, butwill reduce the stability of the valve. Reducing control chamber volume willincrease the stability of the valve. The results of simulation and verify thetheoretical analysis.The shortcomings of existing pressure-compensated control valve is lowaccuracy and the instantaneous flow overshoot when load mutation. The motiondetection of flow rate is not easy to achieve. In this paper, the differentialpressure displacement compensation principle is applied to Valvistor valve.Constitute a new principle of flow control valve to realize the accurate control offlow. Through experiment and simulation model, the new principle of flowcontrol valve is studied in detail. The results show that the flow control valvewhich using the new principle has high precision.