Heat Characteristics Analysis of Electro-Hydraulic Servo Valve

A new method of building electro-hydraulic servo valve's thermal model is proposed. In this method, energy conservation equation of servo valve was obtained according to thermodynamics, which describes servo valve's heat conduction, heat convection, and heat radiation with other hydraulic components. Servo valve's thermal model and thermal characteristics model were built and simulated in AMESIM. Experiment was carried out in four working pressures ranging from 3 MPa to 12 MPa. Simulation and experimental results indicate that servo valve reaches thermal equilibrium in less than 2.5 h, and with pressure's increase, valve reaches thermal equilibrium more quickly with a higher steady temperature. Maximum and steady temperature error between simulation and experimental results are approximately 4.6 degrees C and 1.5 degrees C, and when lowering pressure, they both reduce. The temperature error can mainly result from motor's heat production in experiment, which will vanish when the whole hydraulic motor servo system is modeled. Therefore, experimental results verified the validity of valve's thermal characteristics model. The significance of this study is to provide a theoretical basis for subsequent researches of heat characteristics of other hydraulic components, which include hydraulic motor, valve block, hydraulic oil source, and so on.