湿式换挡离合器接合过程黏性转矩计算研究

Viscous Torque Calculation for Engaging Process of Wet Shifting Clutch

湿式离合器接合过程一般分为纯油膜剪切、混合摩擦、粗糙接触3个阶段,其中黏性转矩发生在纯油膜剪切阶段和混合摩擦阶段。在考虑压差作用和离心力作用下分别计算径向流速和流量,根据修正的雷诺方程牛顿内摩擦定律分别建立摩擦副间油膜厚度模型和黏性转矩计算模型;利用Simulink仿真模块计算得到油膜厚度和黏性转矩;通过引入系数方程修正黏性转矩公式,并通过实验测试和数据采集分析,确定方程中的自变量系数。黏性转矩试验测试曲线与计算曲线的对比验证了计算模型的正确性。计算结果表明:黏性转矩受离心力和压力差作用影响较大;由于流体的可压缩性和流动性使得控制油压作用减弱,由转速导致的离心力对黏性转矩影响则被加强,因此转速对黏性转矩的影响远大于控制油压的影响。

The phase of the occurrence of the viscous torque is determined by the division of the wet clutch engagement process.They are pure oil film shear stage and mixed friction stage.By considering the effect of the pressure and centrifugal force,radial velocity and flow were calculated.According to the modified Reynolds equation and Newton＇ s law friction, the model of oil film thickness variation and the viscous torque were established, and it was simulated by Simulinkl.The coefficient equation was introduced to modify the theoretical formula, and the coefficient of independent variable in the coefficient equation was determined by testing the actual torque with many experiments.The result of comparison between the test curve and the calculated curve of the viscous torque shows that the calculation formula of viscous torque can reflect the experimental situation better.The calculation results show that the centrifugal force and the pressure difference have great impact to the viscous torque.Due to the compressibility of the fluid flow, the hydraulic control effect is reduced, the influence of centrifugal force caused by the speed of the viscous torque is enhanced, so the influence of rotational speed on the viscous torque is larger than that of control pressure.