复杂机车振动环境下牵引电机轴承服役寿命评估

牵引电机是铁路机车的动力源, 其关键零部件(支承轴承等)的服役性能直接影响机车传动系统的稳定性和可靠性. 对于重载机车, 传统轴承服役寿命评估方法主要基于定载荷工况, 难以准确评估轨道不平顺等复杂外部激励作用下电机轴承的服役寿命. 因此, 本文根据车辆-轨道耦合动力学理论, 考虑轨道车辆运行过程中的轮轨相互作用和齿轮啮合作用, 建立了具有牵引动力传动系统的机车-轨道耦合动力学模型; 采用线性损伤累积准则和ISO 281标准计算方法, 评估了复杂机车振动环境下牵引电机轴承的服役寿命. 结果表明, 在轨道随机不平顺激励下, 机车轮轨垂向力、齿轮啮合力、牵引电机内部转子离心力、不平衡磁拉力等明显增大; 在复杂机车振动环境中, 电机轴承内部滚子-滚道相互作用加剧, 传动端与非传动端轴承的疲劳寿命缩短; 随着线路状态的不断恶化和机车运行速度的提高, 牵引电机轴承的预测寿命里程不断减小; 由于传动端轴承承受较大的外部动态载荷, 传动端轴承的服役寿命明显低于非传动端轴承. 本文提出的评估方法可为机车牵引电机轴承的设计、选型和寿命评估提供理论指导. 

SERVICE LIFE EVALUATION OF TRACTION MOTOR BEARINGS IN COMPLICATED VIBRATION ENVIRONMENT OF A LOCOMOTIVE

Traction motor is the power source of the railway locomotive, therefore, the stability and reliability of the locomotive transmission system are directly affected by the service lives of its key components (e.g., the support bearings, etc). For the heavy haul locomotive, the traditional evaluation methods are mainly based on the fixed load conditions, therefore, it is difficult to accurately evaluate the service lives of motor bearings under complex external excitations such as track random irregularities. Based on the vehicle-track coupling dynamics, a locomotive-track coupled dynamics model with traction power transmission system considering the specific structures of the traction motor and rolling bearing is established. In addition, the effect of the impact wheel-rail interaction and gear engagement is considered in this study. Besides, the service lives of traction motor bearings in the complex vibration environment of a locomotive are assessed based on the linear damage accumulation criterion and ISO 281 standard. Results indicate that the vertical wheel-rail interactive force, gear meshing force, the centrifugal force of rotor, and unbalanced magnetic pull increase obviously under the external excitation induced by the track random irregularity. In the complex vibration environment of the locomotive, the interactions between the roller and race in motor bearings are intensified, and the corresponding fatigue lives of the driving end and non-driving end motor bearings are shortened. Furthermore, with the continuous deterioration of the line state and the improvement of the locomotive running speed, the predicted life mileages of the motor bearings decrease in the increasingly harsh service environment. Because of the large external dynamic loads, the service life of the driving end bearing is shorter than that of the non-driving end one. This evaluation method proposed in this study can provide a theoretical guidance for the design, selection, and service life prediction of motor bearings used in the locomotive.