高加速寿命试验下的干式离合器半联动热稳定性

针对干式离合器在半联动操作中的热失效问题, 研究了半联动过程中离合器的热稳定性。基于离合器半联动操作过程中的滑摩功, 得到了影响热稳定性的关键变量, 包括摩擦片轴向压力、相对滑磨转速和滑磨持续时间。结合干式离合器热模型和高加速寿命试验, 设计了强化加载剖面, 验证了摩擦片热模型的循环强化加载试验效果。为了分析高加速寿命试验下不同变量对热稳定性的影响程度, 通过正交试验和极差分析法, 研究了关键变量对摩擦片最高热点温度的影响。研究结果表明: 按影响程度由大到小排序, 3个关键变量依次为相对滑磨转速、滑磨持续时间和摩擦片轴向压力; 当发动机转速较低, 约为1 000 r·min^-1时, 热点温度始终保持在200℃以下的安全温度, 当发动机转速超过1 500 r·min^-1, 轴向压力超过2.0 kN, 滑磨持续时间超过8 s后, 热点温度将超过200℃的安全温度; 采取合适的半联动操作组合, 例如控制发动机的转速与频繁半联动操作的累计时间, 可以有效防止摩擦片热失效的发生。

Semi-linkage thermal stability of dry clutch under highly accelerated life test

Aiming at the problem of thermal failure of dry clutch during semi-linkage operation, the thermal stability of clutch in semi-linkage process was studied.Based on the sliding friction power of clutch during semi-linkage operation, the key variables effecting the thermal stability were acquired, including the axial pressure of friction plate, relative sliding speed and sliding friction duration time.With the combination of dry clutch thermal model and highly accelerated life test (HALT) method, the enhancement loading profile was designed, and the effect of cyclic enhancement loading test of friction plate thermal model was verified.In order to reflect the influence degrees of different variables on the thermal stability in highly accelerated life test, the effect of sensitive variables on the highest hot spot temperature of friction plate was studied by using orthogonal test and range analysis method.Analysis result indicates that according to the influence degrees from the great to the little, the order of key variables are relative sliding speed, sliding friction duration time and the axial pressure of friction plate respectively.When the engine is running at a lower speed of 1 000 r·min-1, the hot spot temperature is always under the safe temperature of 200 ℃.When the engine speed exceeds 1 500 r·min-1, the axial pressure of friction plate is more than 2.0 kN, and the sliding friction duration time is more than 8 s, the hot spot temperature will exceed the safe temperature of 200 ℃. With the right semi-linkage operation, such as controlling both the engine speed and the accumulation time of frequent semilinkage operation, the thermal failure of friction plate can be effectively prevented.