换挡离合器摩擦元件周向间歇接触温度场研究

A Study on the Temperature Field of Friction Elements in Shifting Clutch with Circumferential Intermittent Contact

考虑温度和滑摩速度对摩擦因数的影响,建立了宏观维度下换挡离合器摩擦元件周向间歇接触温度场迭代计算模型,研究了与花键齿数相对应的间歇接触对温度场和摩擦因数的影响,并通过温度测量实验对模型进行了验证。结果表明:间歇接触会导致对偶片表面出现高温区,高温区分布与花键齿数相对应,对偶片表面最高温度与平均温度均随花键齿数增加而降低,对偶片温升与花键齿数和滑摩时间呈非线性相关。相同滑摩条件下,不同花键齿数对应的摩擦因数随滑摩时间增加而逐渐增大至同一最大值,在摩擦因数达到最大值前,花键齿数较少的对偶片对应的摩擦因数较大。换挡工况下,花键齿数较少的摩擦元件较快进入干摩擦状态,在较短时间内便可达到较大的摩擦因数;车辆蠕行等离合器长时滑摩工况下,花键齿数较多的摩擦元件局部温升较小,具有较好的热安全性。

With consideration of the effects of temperature and sliding velocity on friction coefficient, an it-erative model for calculating the temperature field of circumferential intermittent contact between friction elements ofshifting clutch under macro-dimension is established to study the influence of intermittent contact, corresponding tothe number of spline teeth, on temperature field and friction coefficient, and the model is validated by friction coef-ficient measuring experiments. The results show that intermittent contact may result in high temperature zones appearon the surface of friction disks, and the distribution of the high temperature regions corresponds to the number ofspline teeth. The highest temperature and average temperature of friction disks lower with the increase of the numberof spline teeth, and the temperature rise in friction disks exhibits nonlinear correlation with the number of splineteeth and sliding time. Under the same sliding condition, with the sliding time extending, the friction coefficients,corresponding to different number of spline teeth gradually increases to the same maximum value, and before thefriction coefficient reaches the maximum value, the friction coefficient corresponding to fewer spline teeth is larger.Under shifting condition, the friction disks with less spline teeth quicker enter the state of dry friction and reach lar-ger friction coefficient in shorter period of time. Under the long time sliding conditions such as when the vehiclecreeps with foot on clutch, the friction disks with more spline teeth have less local temperature rise with better ther-mal safety.