Research On Estimation Of Radial Clearance And Fillet Angle Of Servo Valve Based On Pneumatic Flow Curve

As a key component of hydraulic system,electro-hydraulic servo valve is widely used in aerospace and other national defense fields.The slide valve pair composed of valve sleeve and valve spool is the core component of servo valve,which requires high machining accuracy,and the machining error is generally within 1～3 microns.Diametral clearance and fillet are two main geometric characteristics of slide valve pair,and their machining quality directly affects the output characteristics of servo valve.It is difficult to directly measure the diametral clearance and fillet of slide valve pair,so it is of great significance to study a high-efficiency and low-cost measurement method.In this thesis,the influence of diametral clearance and fillet on pneumatic flow curve is analyzed,and the estimation of diametral clearance and fillet of servo valve is studied by using support vector regression method.Support vector regression needs training samples,but it is difficult to measure the diametral clearance and fillet size of slide valve corresponding to different pneumatic flow curves,resulting in fewer samples.We use the CFD finite element simulation to get the pneumatic flow curves corresponding to different diametral clearances and fillets,and solve the demand of data samples by machine learning.According to the symmetrical characteristics of servo valve,an effective simplified model of valve port is established based on Fluent,reasonable grid division is carried out,corresponding algorithms and initial conditions are set,and finally pneumatic flow simulation curves under different diametral clearance and fillet conditions are obtained.The pneumatic measurement system of slide valve pair is built to verify the validity of simulation data.In order to solve the over-range problem of flowmeter in the measurement system,an air circuit system is designed,in which the throttle valve is connected in series with the air inlet circuit,and the flow curve is corrected by pressure.The mechanical system,automatic control system and software system are designed to complete the pneumatic measurement of servo valve,and compared with the simulation data,the simulation data is verified to be valid.The research in this thesis belongs to regression problem,we use the support vector regression method to estimate the diametral clearance and fillet of servo valve.The pneumatic flow curve obtained by simulation is preprocessed,and the simulation data is used to train and test the support vector regression model.The flow data measured by the gas path measurement system is substituted into the trained regression model,and we should obtain the estimated values which are within the error range from the actual measured values of diametral clearance and fillet.Compared with the estimated results of BP neural network,it is concluded that the support vector regression has better effect.The support vector regression model based on pneumatic flow simulation curve training can accurately estimate the diametral clearance and fillet of the actual slide valve pair samples.