【作者】 邱宇；

【导师】 许敏；

【作者基本信息】 上海交通大学 ， 车辆工程， 2012， 硕士

【摘要】 润滑系统是汽油发动机中最重要的子系统之一,为发动机各个摩擦副提供动力润滑,其性能的好坏直接影响了发动机的性能和寿命。而当前能源形势日益严峻,提高发动机燃油经济性的需求越来越迫切。如何通过对润滑系统性能进行优化,使发动机的摩擦损失以及机油泵的驱动功率降低,从而对降低发动机功率损耗,提高燃油经济性做出贡献是本文研究的课题。本文首先对发动机润滑系统最重要的两种耗油件:主轴承和连杆大头轴承进行研究,采用基于多体动力学的弹性流体动力学方法,获得了详细的轴承性能。针对多体动力学计算时间长,优化成本高的问题,开创性地利用kriging插值估计方法建立轴承的近似模型。利用拉丁超立方采样(LHS)方法进行实验设计(DOE),对轴承的众多参数进行筛选,获得了6个最重要的参数作为设计变量参与优化设计。采用非支配遗传算法(NSGA)对轴承进行基于近似模型的多目标优化,降低了轴承的机油流量和摩擦功耗。全转速范围内平均降低14.14%的摩擦功耗,最大降低686.27W。然后在优化的轴承基础上,对原机润滑系统管路管径进行优化,使得润滑管路流阻降低。在轴承机油流量降低和管路流阻降低的双重优化作用下,在油压达到原机水平的前提下,机油泵排量从原机的8.80ml/rev减小至7.989ml/rev,全转速范围内驱动功率平均降低11.02%,最大降低了71.46W。更多还原

【Abstract】 Lubrication system is one of the most significant subsystems in gasoline Internal Combustion Engine, it provides hydrodynamic lubrication for friction pairs of the engine. The performance of lubrication system determines the performance and life of the engine directly. And nowadays the energy crisis becomes more and more serious, people pay more and more attention on improving engine fuel economy. Therefore, the project which this paper worked on is to investigate how to reduce the friction loss of the engine and driven power of the oil pump by optimizing lubrication system, so that the engine fuel economy can be improved due to lubrication system optimization.In this paper, main bearings and conrod bigend bearings, which are two most important oil consumers of lubrication system, were investigated using multi-body dynamics (MBD) and elasto-hydrodynamics (EHD), detailed bearing performance was obtained. Owning to the high computation cost of MBD and EHD, Kriging interpolation method was implemented in this paper, to establish approximation models of engine bearings pioneeringly. Latin Hypercube Sampling (LHS) was used to conduct Design of Experiment (DOE). Bearings parameters screening was first proceeded, 6 parameters were chosen from lots of parameters as design variables to attend the optimization. Multi-objective optimization of the bearings based on approximation models was conducted using Non-dominated Genetic Algorithm (NSGA). Oil Consumption and friction loss of the bearings were reduced. Over a whole speed range, the friction loss of the engine dropped 14.14%, up to 686.27W was saved. And then the pipes diameters of lubrication system were optimized based on optimized bearings, in order to reduce the flow resistance. Under the optimization of both bearings and lubrication pipes, the same oil pressure level was reached as premise, the oil pump size was reduce from 8.80 ml/rev to 7.989 ml/rev, the driven power was dropped 11.02% over the whole speed range, up to 71.46W driven power was saved. Finally, compared with baseline engine, the economy was improved up to 0.7964%.更多还原