Development Of Spool And Sleeve Overlap Value Evaluating System

As the crucial part of electro-hydraulic servo system, electro-hydraulic servo valvehas been widely used in aeronautics and astronautics. The demand for more applicationis growing, while the requirement for reliability is higher. The manufacture of electro-hydraulic servo valve has gradually transformed from small batch to mass production.However, the acceptance rate is less than30%according to the survey of factoriesproduce electro-hydraulic servo valve, which restrict the large scale manufacture ofelectro-hydraulic servo valve. Electro-hydraulic Servo Valve is consisted of valve spooland valve sleeve. The precision of the valve spool and valve sleeve is the key ofmachining. Overlap value is the axial mate dimension, which in practical machiningusually has a requirement of1-4μm to counteract errors in machining to ensureexcellent flow performance. Several apparatuses have been developed to measure theoverlap value. However, the situation that two valves show different features eventhough they have same overlap value still exists. The divergence usually appears aroundthe origin of pressure increments or static consumption. Apparatuses able to detectoverlap, pressure increments and static consumption at the same time have not beendeveloped yet. Thus an apparatus which can measure the three parameters during themachining process has a great significance on electro-hydraulic servo valvesmanufacture.In this work, the measuring principle and operating characteristics of smallopening servo valve are stated. A design scheme of testing system is proposedaccording to the evaluation indexes. The designing process is completed bymodularization. The general scheme is divided into two parts, the hardware and thesoftware. The hardware part includes mechanical part and electric control part. And themechanical part is consisted of test station, fixture and pump station. The pump stationis controlled by two pumps which lowers the power of the station. PLVE inner circuit isemployed to control the two proportional relief valves which realize the pressurestepless control of the system. The electrical part includes data collection via varioussensors, motion control of the precise mobile platform and the control of powerequipment and system pressure.The software is designed by using VC++andLabVIEW joint programming to deal with data acquisition, process control and dataprocessing. Finally the evaluating system of spool and sleeve overlap value is completeand the objective parameters are reached.