Static-Dynamic Characteristics Analysis Of Proportional Valve With Pilot Control By The High-Speed Switching Valve Bridge

With the continuous development of electro-hydraulic control technology,the engineering machinery industry has higher requirements for the control accuracy and response speed of hydraulic components and systems.As the most important control component in the entire hydraulic system,the di gitalization and intelligence of hydraulic control valves have become urgent.Compared with the traditional proportional valve controlled by analog signals through pressure reducing valve as the pilot stage,the digital proportional valve controlled by digital signals through a high-speed switching valve bridge as the pilot stage has the advantages of simple and compact structure,superior control performance,and strong anti-pollution performance.Therefore,more and more digital proportional valves have been widely used in the engineering machinery industry.This paper takes a certain type of digital proportional valve as the research object,and uses mathematical modeling,simulation analysis,and experimental verification to conduct detailed research and analysis on the static flow characteristics and displacement dynamic response characteristics of digital proportional valves.This provides theoretical basis and experimental evidence for the subsequent optimization of digital proportional valve characteristics.The specific research content of this paper includes:(1)Analyzed the research background and significance of the high-speed switching valve bridge pilot control proportional valve,elaborated on the research status of high-speed switching valve bridge pilot control technology,the development overview of digital proportional valves both domestically and abroad,and the research status of their static and dynamic characteristics.Based on the existing static and dynamic characteristic problems,this paper puts forward the research content.(2)The structure composition,working principle,and control mechanism of the digital proportional valve were analyzed in detail.The force equation and flow equation of the pilot stage model and the main valve model were derived by using parameter measurement and numerical calculation,and the mathematical model of the entire digital proportional valve was systematically established.(3)Through the analysis of the static and dynamic characteristics of the existing U-shaped throttling grooves structure proportional valve,it is known that there are problems such as poor micro-motion characteristics and low flow control accuracy.Therefore,this paper proposes a new throttling grooves with slope-diverge-shaped and conducts CFD flow field simulation on two different throttling grooves.The simulation results show that the slope-diverge shaped throttling grooves has better improvement on the micro-motion characteristics and flow control characteristics of the digital proportional valve.(4)Using AMESim and LabVIEW software,a closed-loop simulation model from control signal to pilot high-speed switching valve bridge to main valve system and its joint simulation testing platform for static and dynamic characteristics testing were established.The influence of these factors on the static and dynamic characteristics of digital proportional valves was analyzed by changing the PWM signal duty cycle,pilot oil supply pressure,main valve throttling grooves structure,and main valve reset spring stiffness.(5)A static and dynamic characteristic testing system for digital proportional valves was designed and built,and its static flow characteristics and displacement dynamic response characteristics were experimentally verified.The experimental results show that in terms of static characteristics,the slope-diverge-shaped throttling grooves has a more gradual flow gain during valve opening,and has better opening and closing characteristics.During the working phase,the linearity of the flow curve is better,and there is higher flow control accuracy.In terms of dynamic characteristics,compared with the U-shaped throttling grooves,the overshoot of the slope-diverge-shaped throttling grooves displacement response is reduced by 5.3%,and the time for the spool displacement to reach steady state is shortened by 0.18 s.