【作者】 李迎春；

【导师】 刘敬平；

【作者基本信息】 湖南大学 ， 动力机械及工程， 2011， 硕士

【摘要】 计算机仿真是现代汽车技术研究和汽车开发设计的重要方法和工具,广泛应用在汽车开发设计的各个阶段。汽车性能模拟可以在汽车物理整车生产之前对其性能有较准确的预测,可以指导整车、发动机、传动系统之间的选型匹配,以达到动力性和经济性的最优结合。对于传统动力汽车,发动机是汽车的动力来源,同时也是燃料的直接消耗者和排放物的直接生成者,对汽车性能有着至关重要的影响。汽车的经济性由道路行驶时发动机的燃油消耗量决定,因此准确的分析出发动机的常用工况及其对汽车油耗的贡献率,并针对常用工况对发动机进行有侧重性的优化,对于汽车和发动机的设计开发具有非常重要的意义。然而汽车道路行驶对应的发动机工况分布散乱,很难分析出不同发动机工况对于汽车性能的影响大小。本文就是基于上述的研究意义,对汽车性能模拟和道路行驶对应发动机简化分析进行研究。首先,论文分析了当前国内外对于汽车性能模拟和道路行驶对应发动机工况分析的研究现状,基于目前商用软件的不足之处,指出研究的意义和目的。接着,对汽车动力学、运动学理论进行研究,并结合当前常用的汽车性能评价标准,分析汽车性能模拟的计算理论;基于对聚类分析方法的理解,结合道路行驶工况对应发动机工况的特点,提出基于聚类分析的发动机工况分区简化方法,并基于Excel-VBA编写了计算程序。然后,使用本文所编写程序对一款轿车的动力性、经济性进行模拟,并对汽车按国家道路试验工况行驶对应发动机工况进行简化分析,将得出的结果与试验结果及商用软件GT-Drive计算结果做对比,验证了所做理论研究的正确性和所编计算程序的精度及稳定性。最后,根据汽车和发动机正向开发不同阶段的工作内容,结合本文所编计算程序的功能,简要分析了计算程序在不同阶段的应用价值和应用方法,对本文所做研究在工程实践中的应用提供指导。结果表明,计算程序能够准确地预测汽车动力性、经济性,并得出发动机常用工况及其油耗贡献率,从而验证了计算理论的正确性和合理性。更多还原

【Abstract】 In modern times, computer simulation is important method and tool for vehicle technology study and vehicle design. It has been widespread adoption during every stage of vehicle design. Vehicle performance can be predicted exactly by simulation before it was manufactured, valuable advices for matching between vehicle, engine and transmission system can be obtain from simulation, then the optimum between dynamic and fuel economy can be obtain. As to traditional vehicle, engine is the only power source, and it is also the direct consumer of fuel and direct producer of emission, so it influence vehicle performance significantly. Fuel economy determined by engine fuel consumption during the driving cycle, so obtain the frequently-used operating points and optimize engine performance particularly are important for vehicle fuel economy optimization. However, engine operating points corresponding to a vehicle’s driving cycle are usually spread in a wide speed and load range and in somewhat a chaos manner; it is difficult to detect the contributions to the overall vehicle fuel economy of each individual operating points. This thesis is focused on developing an approach to simplify the engine operational map into several typical points so that to make it possible for emphasized analysis and optimization.Firstly, represent actuality about vehicle performance simulation and engine operating points corresponding to driving cycle simplification were discussed, deficiency of software existed was detected, then significance and purpose were put forward.Secondly, kinetics and kinematics of vehicle were discussed; theory of vehicle performance simulation was obtained base on vehicle performance evaluation criterion. According to theory of cluster analysis and characteristic of engine operating points, simplify and analyze method of engine operating points were put forward. And computation program was written in Excel-VBA.Then a vehicle dynamic and fuel economy were simulated in the computation program, and engine operating points corresponding to driving cycle were simplified. Compare simulation result with test result and simulation result of GT-Drive, correctness of theory and accuracy of computation program were validated.Finally, according to task of each stages during vehicle design, value and usage method in each stages were presented. This work showed that the computation program can be effectively used to predict vehicle dynamic and fuel economy; it can also be effectively used to analyze engine operating points corresponding to driving cycle. Then correctness and rationality of theory were validated.更多还原