轴瓦表面波纹度对柴油机连杆大头轴承润滑特性的影响

Effects of Bearing Surface Waviness on Lubrication Characteristics of Connecting Rod Big End Bearing of Diesel Engine

柴油机连杆大头轴瓦表面在加工过程中存在波纹度,表面波纹度严重影响轴承接触表面的润滑性能。针对这一问题,建立考虑表面波纹度的连杆组弹性流体动力学模型,分析不同波纹度幅值、阶次和数量对连杆大头轴承润滑特性影响规律。结果表明:随着波纹度幅值、阶次和数量的增加,最小油膜厚度总体先增大后减小,总摩擦功耗先减小后增大,表明合理分布的表面波纹度对轴承性能有积极影响,可提升轴承的润滑性能;基于Box-Behnken试验设计与响应面法对柴油机连杆大头轴承润滑特性进行研究,以轴瓦表面波纹度的幅值、阶次和数量为优化变量,以最小油膜厚度和总摩擦功耗为优化目标进行响应面分析,并结合带精英策略的非支配排序遗传算法进行优化。结果表明:不同轴瓦表面波纹度对连杆大头轴承润滑特性影响差异较大;相较轴瓦光滑表面,优化后最小油膜厚度增加了11%;总摩擦功耗降低了14%。

The surface of the diesel connecting rod big end bearing bush has waviness during the machining process,and the surface waviness seriously affects the lubrication performance of the bearing contact surface.Aimed at this problem,an elasto-hydrodynamic model of the connecting rod group considering the surface waviness was established,and the influence of different amplitude,order,and number of waviness on the lubrication characteristics of connecting rod big end bearing was analyzed.It is found that with the increase of the amplitude,order,and number of waviness,the minimum oil film thickness generally increases and then decreases,and the total friction power consumption first decreases and then increases,indicating that a reasonable distribution of surface waviness has a positive impact on bearing performance and can improve the lubrication performance of bearings.Based on the Box-Behnken design and response surface method,the lubrication characteristics of diesel connecting rod big-end bearings were studied.The amplitude,order and number of the bearing surface waviness were used as optimization variables,and the minimum oil thickness and total friction power consumption were optimized.The target was optimized by response surface and combined with Non-dominated Sorting Genetic Algorithm-Ⅱ(NSGA-Ⅱ).The results show that different bearing bush waviness has a great influence on the lubrication characteristics of the connecting rod big end bearing.Compared with the smooth surface of the bush,the minimum oil film thickness after optimization is increased by 11%,the total friction power consumption is reduced by 14%.