【作者】 周伟；

【导师】 申福林；

【作者基本信息】 长安大学 ， 车辆工程， 2009， 硕士

【摘要】 随着我国城市化建设进程的加快,城市规模不断扩大,人口激增,居民出行量的增加对公共交通系统提出了更高的要求。为了提高城市客车的运输能力,各大城市正逐步采用运输效率更高的低地板和超低地板城市客车,而低地板和超低地板城市客车不同于普通城市客车的关键技术就是采用了门式驱动桥和大落差前桥,以实现降低地板高度、提高上下车方便性和运输效率的目标。大落差前桥作为低地板和超低地板城市客车的关键总成之一,不仅承担着整车三分之一的载荷,受力情况复杂,而且与整车的转向性、操纵稳定性、制动安全性和通过性等密切相关。因此,掌握大落差前桥的结构特点,全面了解其在客车运行中的受力状态,以及强度、刚度、抗冲击性、疲劳特性和可靠性等方面的要求,对设计开发出满足使用要求的产品就显得十分重要。本文以某国产超低地板城市客车用大落差前桥为例,利用三维建模软件UG建立了前桥的三维实体模型,再将模型导入有限元分析软件ANSYS中得到大落差前桥的有限元分析模型;通过对前桥模型的静力分析和典型工况的强度校核,找出了危险关键点的位置并分析应力值过大的原因,提出了相应的改进方案;根据静力分析结果对前桥进行了疲劳寿命分析,得出关键点的许用循环次数,结果表明达到了汽车转向桥疲劳寿命的设计要求。最后,利用ANSYS对前桥模型进行了模态分析,得到前桥低阶固有频率,通过与由路面激振产生的振动频率比较,得出该前桥结构合理,能够满足我国低地板和超低地板城市客车的使用要求。本文的研究结果,可为开发国产大落差前桥提供参考。更多还原

【Abstract】 With the speeded-up of urbanization in China, city scale and population is expanding sharply. Higher requirements of public transport system are proposed by increasing of residents’ travelling. In order to improve the city-bus’s transport capacity, major cities are gradually adopting low-floor and ultra-low-floor city-bus which have higher transport efficiencies. The key technology of the low-floor and ultra-low-floor city-bus different from ordinary city-bus is the Portal Axle. This can achieve lower floor height; improve the convenience of getting off and on and the transport efficiency.As one of the critical assemblies on low-floor and ultra-low-floor city-bus, Portal Axle do not only bear one-third of the vehicle’s load, but also endure complex forces. It is relates to the vehicle’s steering, handling stability, braking security and capability of transition. Therefore, to master the structural features of Portal Axle, to get a comprehensive understanding of its force status when it is in the operation and requirements on strength、stiffness、impact resistance and fatigue characteristics reliability, to design and develop products to meet the using requirements are very important.This paper made a city-bus with Portal Front Axle for the prototype. The three-dimensional solid model of front axle was framed by the three-dimensional modeling software UG. The finite element analysis model was obtained through importing the model into the finite element analysis software ANSYS. We found the positions of dangerous key points and the reasons of excessive stress value on key points through static stress analysis and intensity checking in accordance with the typical situation and proposed the correspond programs of improvements; We had a fatigue life analysis of Portal Front Axle in accordance with static analysis results and received the allowable cycle numbers on key points. The results showed that the front axle met the design requirements of fatigue life. Finally, a modal analysis was carried on by using ANSYS. The natural frequency of Portal Front Axle was obtained. Compared with the vibration frequency generated by road vibration, we got the result that the front axle’s structure was reasonable and could meet the requirement of the low-floor and ultra-low floor city-bus using.Research results in this paper can provides reference for the development of China-made Portal Front Axle.更多还原