基于摩擦及泄漏补偿的被动电液测力建模与实验研究

Mathematical modeling and experimental research of passive electro-hydraulic force measurement based on the friction and leakage compensation

为提高液压系统静态下基于流体压力测量其负载的测量精度,基于弹塑性变形理论及流体力学连续方程和N-S方程,分别对液压缸摩擦及泄漏进行了分析,建立了液压缸活塞密封圈与内壁接触摩擦力方程及液压缸-活塞间油液泄漏剪切力方程,得到液压缸接触摩擦力与泄漏剪切力数学模型,利用Ansys与Fluent有限元软件分别对其接触摩擦力及泄漏流场进行仿真计算分析。在此基础上,搭建了被动静态电液测力实验系统,考虑活塞密封圈与缸内壁接触摩擦和液压缸-活塞间泄漏,基于建立的摩擦及泄漏模型,补偿得到了被动电液测力系统的测量精度,并将之与线性拟合法得到的测量精度进行了对比。实验结果表明,采用基于摩擦及泄漏补偿的被动电液测力测量精度比常规线性拟合法明显提高,从而为提高电液测力测量精度提供了一种新的思路与方法。

To improve the measurement accuracy of the static passive electro - hydraulic system, the friction and leakage of hydraulic cylinder are analyzed in the paper based on the theory of elastic - plastic deformation and fluid mechanics continuity equations and N - S equations. The numerical model of the contact stress between piston seal and the inner wall of the hydraulic cylinder and the tangential force produced by the leakage of oil between hydraulic cylinder and piston are established. The simulation of the contact stress and leakage flow field is done by Ansys and Fluent. The system of the static passive electro - hy- draulic force measurement is built. The measurement accuracy of the passive electro - hydraulic force measurement is concluded under the basis of the friction and leakage model compensation, the measurement accuracy based on the method of linear fitting is also done. The experiment results show that the measurement accuracy got by the friction and leakage compensation method is higher than the conventional linear fitting method. The theoretical basis and methods put forward to a new method for solving the problem of low accuracy by using the electro - hydraulic force measurement.