【作者】 陈勇；

【导师】 朱思洪；

【作者基本信息】 南京农业大学 ， 车辆工程， 2012， 硕士

【摘要】 近年来中国工程机械取得了长足的发展,但农用车辆、工程车辆及军用战车等非道路车辆悬架结构发展缓慢,已有的悬架性能较差,降低了车辆的安全性和使用寿命；车辆长期工作在道路情况恶劣的环境中,驾驶员承受低频高强度的振动,身心健康受到严重威胁。因此给座椅加装悬架系统是一种较为简捷的解决办法,研究其动态特性并改善其动态性能对于提高非道路车辆的乘坐舒适性有重要意义。本课题为改善非道路车辆驾驶员的乘坐环境,以CF700型拖拉机为研究对象,设计了一种可以在x、y和z向减振的三自有度座椅悬架系统；将人体等效简化为一个质量块置于座椅悬架之上,根据牛顿第二定律列出了其运动微分方程；在ADAMS软件中建立了带有人体的座椅悬架多体动力学模型；人体及悬架置于驾驶室内,建立了整车多体动力学模型,做了仿真研究。所完成的工作及得到的结论归纳如下：(1)设计了座椅悬架结构及分析了元器件的布置方案,构建了“人体—座椅”系统,利用多刚体系统动力学理论建立了人体在x、y和z向的运动微分方程,并推导出了前进方向和驾驶员左手方向的等效刚度、三方向加速度表达式；另外推导出了人体在俯仰和侧倾方向固有频率的表达式；分析了三自由座椅悬架系统动态特性的影响因素。结果表明拖拉机整机的质量属性、轮胎属性、行驶速度和悬架系统各向的刚度阻尼等参数共同影响座椅悬架的动态特性。(2)设计了座椅悬架各组成零件分析了各零部件之间的相互连接和传动关系。悬架系统由板件、空气弹簧、扭杆弹簧和磁流变减振器构成。确定了悬架结构的整体安装尺寸和工作行程,并对空气弹簧和磁流变减振器做了选型,校核了悬架系统中易失效零件。(3)根据座椅悬架结构,建立了座椅悬架的多体动力学模型；计算了建立轮胎模型所需的参数值,编写了前后轮轮胎文件；使用Pro/E软件建立了CF700拖拉机的车体模型,获取了人体、各零部件和车体的质量属性参数；在ADAMS软件中建立了带有人体的座椅悬架多体动力学模型；根据国标规定的标准较粗糙路面的参数值编写了用于仿真的路面文件(.rdf)；建立了整车及路面虚拟样机模型。(4)实地采集了CF700拖拉机在标准跑道上以不同速度行驶时人体在x、y和z向的加速度时域信号,对比检验了无座椅悬架的整车仿真结果,表明了人体在三向的加速度均方根仿真值和实地测试值基本相等,虚拟样机模型各参数设置合理；以此为基础,做了带有座椅悬架整车的仿真研究,垂直方向采用低频减振,俯仰和侧倾方向采用的是高频减振；仿真结果显示垂直、俯仰和侧倾方向上的固有频率分别为1.5Hz、23Hz和15Hz时在三个速度下三个方向的减振效果最好。本课题的研究对提高非道路车辆悬架研究的速度,改善驾驶员的乘坐舒适性,降低振动对其身心的危害有重要的意义和实用价值。更多还原

【Abstract】 Engineering machineries have made a great development in recent years in China, but suspension technics of off-road vehicles such like agriculture vehicles, engineering vehicles and military vehicles are developing very slow, and the existing suspensions behave poor performance, that make vehicles unsafe and short lifetime; vehicles usually work in harsh conditions, and drivers bear low frequencies and high intensity vibration, their physical and mental health have been threated. Install the tractor with a seat suspension is a simple way to solute the problem. It matters to research the dynamic characteristic and to improve the dynamic performance, and to improve comfortableness of these vehicles.This subject is to develop the drivers’working environment, and a three-degree seat suspension system could damp vibrations of x, y and z axes was designed; driver’s body was simply equivalent to a mass and placed on the seat suspension, the differential equations were listed out according to the Newton second law; the seat a multi body system (MBS) prototype model of the suspension together with body was created using ADAMS software; body and seat suspension were placed in the cabin, a full tractor MBS model was created; some simulations were carried out. Tasks have been finished and conclusions have been drawn are as below:(1) A seat suspension was designed, and the way how to arrange the components was analyzed; and a "body-seat" system was created; a differential equation about how did the body move along x, y and z axes was created using multi-body dynamic theory; equations of equivalent stiffness in the forward direction and the driver’s left hand direction were derived and together with acceleration equations in three axes directions; additionally, the equations about nature frequencies in pitch and roll direction were also derived; factors that influence the suspension system’s vibration characteristic were analyzed. The result showed that vibration characteristic was influenced commonly by tractor mass attribute, tires properties, running speeds, and properties of the suspension structure.(2) Parts of the suspension were designed and the connect relations and drive connections were analyzed. The suspension system includes boards, air spring, torsion spring and magneto-rheological (MR) damper. Overall dimensions and working stroke were assured; types of air spring and MR damper were chosen, and strength of critical parts was verified.(3) According to the suspension structure, MBS model of the seat suspension was created; Parameters of tires were calculated, and tire model files were compiled; the tractor body model of CF700was created with Pro/E software; parameters of the drive’s body, parts and the tractor body were gained; a rougher road file (.rdf) for simulation was compiled according to the national standard, full tractor MBS virtual prototype was created with ADAMS software.(4) The body’s acceleration time domain signal were collected in x, y and z directions when the CF700tractor running on the runways of field tests; results of simulation and test were compared and verified, and showed that the simulation values were approximately equal to the field test value, which means parameters of the non-seat virtual prototype were reasonable; based on the simulation before, the simulation with seat suspension was carried out, vertical direction used way of low frequency damping, pitch and roll direction used way of high frequency damping; and the result showed that the best frequencies of vertical, pitch and roll directions should be1.5Hz,23Hz and15Hz.Researches of this subject have important and practical significances for accelerating speed of suspension research, improving driver’s comfortableness, and decreasing the harm to physical and mental health.更多还原