Research On The Measuring System Of Servo Proportional Valve Overlap

Servo proportional valve is a new type of industrial-grade electro-hydraulic control valve with performance between electro-hydraulic proportional valve and electro-hydraulic servo valve.It has the characteristics of fast response,no zero dead zone,strong anti-pollution ability,and low price.,Suitable for occasions that require high control accuracy and response speed of the electro-hydraulic control system.At present,the domestic research progress on servo proportional valves is relatively backward,and most of the servo proportional valves used in the industrial field are imported products.In this thesis,the key matching size of the valve core and valve sleeve that needs to be controlled during the processing of the servo proportional valve is studied.The servo proportional valve overlap measurement system is developed.The industrial grade anti-wear hydraulic oil HM46 is used as the measurement medium.The moving position of the spool and the flow rate of the corresponding valve port are used to calculate the superimposed amount of the servo proportional valve for further grinding processing.The main research contents of this paper are as follows:1.The development status of domestic and foreign servo proportional valves has been investigated,and it is understood that there is a big gap between the development of domestic servo proportional valves and foreign countries.The research status of domestic and foreign superposition measurement systems and error control methods are analyzed,and the main factors that affect test errors are obtained.The flow-type hydraulic measurement method is determined to be used in the developed measurement system,and a system design scheme is proposed.2.Study the principle of the flow-type hydraulic measurement method,analyze the influence of the change of the flow coefficient and the gap and fillet existing in the actual processing on the measurement of the superimposed amount during the measurement process,so as to obtain a more accurate calculation of the superimposed amount formula.A servo proportional valve flow channel model is established,and the flow field simulation is carried out through FLUENT to explore the influence of the flow state and the shape of the valve port on the flow rate,which verifies the accuracy of the theoretical calculation formula.3.The measurement system is designed according to the principle of superposition measurement.Design the hydraulic schematic diagram and select the components according to the requirements,and complete the structural design of the hydraulic system.The drive system of the valve to be tested is designed,and the transition block for the valve to be tested is designed.Different types of servo proportional valves can be tested by replacing the transition block,and the valve is improved by making the pressure measurement point as close as possible to the valve port.The measurement accuracy of the differential pressure at the mouth.Finally,the control circuit of the hydraulic system is designed,and the signal conversion circuit board and the relay control circuit board are designed according to the needs.4.Use LabVIEW to write measurement system software,collect and process sensor data,receive and transmit user instructions,perform closed-loop control on valve port pressure and oil temperature to improve detection accuracy,and apply multi-threaded processing programs and data The processing program enables the user to select the working side of the valve port to be measured and the flow meter used in the entire test process.The test process and the calculation of the overlap amount are automatically performed by the measurement system software,which reduces the user’s workload.5.Finished the manufacturing of the superposition measurement system,and conducted experimental tests on it.The results show that the accuracy of the displacement sensor is ±0.8μm,the repeatability test accuracy of the overlap amount is±0.7μm,and the valve port pressure difference and oil temperature closed-loop control accuracy is high,which can meet the needs of servo proportional valve overlap measurement.The actual matching and grinding experiment of the servo proportional valve spool was carried out.The spool was ground according to the superimposed amount measured by the measurement system,and the servo proportional valve spool and sleeve that met the requirements were obtained,which verified the practicability of the measurement system.