【作者】 张明哲；

【导师】 冯增铭；

【作者基本信息】 吉林大学 ， 机械设计及理论， 2020， 硕士

【摘要】 目前,汽车工业经过长期的发展正在进行大转型,国内外汽车产商纷纷加入研制新能源汽车的行列,以望缓解能源危机。在新能源汽车发展过程中,纯电动车是一个重要的研究方向。为了更好地发挥纯电动车的性能,在纯电动车上配备两挡变速器变得尤为必要。因此,本文基于企业提供的参数数据,对纯电动车两挡变速器进行了分析和研究。本文首先对纯电动车的主要结构和国内外对两挡变速器的研究进行了介绍,在阐述了变速器工作原理后,基于企业提供的参数数据对两挡变速器的主要结构进行了三维建模。紧接着在RecurDyn中建立传动系统的动力学模型,依据驱动电机额定功率下的转速(2800rpm),对两挡变速器在不同工况下进行了动力学仿真,从速度、齿轮动态啮合力两方面验证了模型的正确性;分析了在一挡稳定工况下各个轴的应力,为两挡变速器轴的设计和优化提供了参考依据。在驱动转速为2800rpm和6000rpm时,对模型进行动力学分析得到了一挡工况各个轴承不同方向的轴承力,发现一挡齿轮对的啮合力使轴承3承受了较大的径向力,轴承力在6000rpm时会出现更大的波动。建立了一挡主动齿轮的刚柔耦合模型并进行了动力学仿真分析,在齿轮的最大应力云图中发现应力主要集中在啮合区域,通过对该齿轮的疲劳寿命预测分析,认为该齿轮满足设计使用要求。在输入速度为2800rpm时,对不同工况下变速器的上拨叉和下拨叉分别做了疲劳寿命分析,发现下拨叉未满足设计使用要求,通过倒圆角方法改进了下拨叉,重新分析后发现改进后的下拨叉满足设计使用要求。在完成了传动系统的动力学仿真分析后,使用Campbell图分析了不同转速工况下的轴承游隙,发现一挡工况时轴承3的振动主要受到输入轴、圆锥滚子和常啮合齿轮的影响;二挡工况时轴承1和轴承4的振动主要受到输入轴转速的影响,且轴承1在低频段时振动更加剧烈。最后通过等效辐射功率(ERP)方法分析了变速器壳体在不同工况下的振动情况,发现输入轴壳体端和输出轴壳体端振动剧烈;在对壳体进行模态分析后,发现壳体的前2阶模态在变速器运行过程中发生共振,随后根据ERP分析结果对壳体进行改进,重新分析后发现壳体1阶模态频率高于系统最高激励频率,降低了壳体发生共振可能性,同时壳体在不同工况下的ERP对比改进前的壳体都有减小,证明了壳体优化的有效性。本文以纯电动车两挡变速器为研究对象,对变速器的拨叉、齿轮、轴、轴承和壳体进行了动力学仿真和分析,对两挡变速器的研究和发展具有重要意义和参考价值。更多还原

【Abstract】 Through long-term development,the automobile industry is now undergoing a major transformation.Automobile manufacturers at home and abroad have joined in the development of new energy vehicles so as to alleviate the energy crisis.In the development process of new energy vehicles,electric vehicles have become an important research direction.In order to better exert the performance of electric vehicles,it is necessary to equip electric vehicles with two-speed transmissions.Therefore,this paper analyzes the two-speed transmission of the electric vehicle based on the parameter data provided by the enterprise.Firstly,the main structure of the electric vehicle and the research of two-speed transmission at home and abroad are introduced.After explaining the working principle of the transmission,the three-dimensional model of the main structure of the two-speed transmission is built based on the parameter data provided by the enterprise.Then the dynamics model of the transmission system is established using RecurDyn.According to the speed(2800rpm)under the rated power of the drive motor,the dynamics simulation of the two-speed transmission is carried out under different working conditions,and the correctness of the model is proved from the aspects of the speed and the dynamic meshing force of the gear.The stress of each shaft under the first gear stable working condition is analyzed,which offers the reference for the design and optimization for the two-speed transmission.When the driving speed reaches 2800 rpm and 6000 rpm,through the dynamics analysis of the model,the bearing forces in different directions of each bearing under the first gear condition are obtained.It is found that the meshing force of the first gear pair makes the bearing 3 bear a larger radial force,and the bearing force will fluctuate more at 6000 rpm.The rigid-flexible coupling model of the first-gear driving gear is established and the dynamics simulation analysis is carried out.It shows that the stress is mainly concentrated in the meshing area in the maximum stress nephogram of the gear.Through the predictive analysis of the fatigue life of the gear,it is considered that the gear meets the requirements of design and use.When the input speed is 2800 rpm,the fatigue life of the upper and the lower shift fork of the transmission under different working conditions are analyzed respectively.It is found that the lower shift fork does not meet the design service life,so it is improved by the fillet method.After re-analysis,the improved lower shift fork has met the design service life.After the dynamics simulation analysis of the transmission system is completed,the bearing clearance under different speed conditions is analyzed using Campbell.It is discovered that the vibration of bearing 3 is mainly affected by the input shaft,tapered roller and constant mesh gear in the first gear condition;the vibration of bearing 1 and bearing 4 is mainly affected by the input shaft speed in the second gear condition,and the vibration of bearing 1 is more intense in the low frequency section.Finally,the vibration situation of the transmission housing under different working conditions is analyzed by the ERP method,and it is found that the vibration of the input shaft housing end and the output shaft housing end is violent;after the modal analysis of the housing,it shows that the first two modes of the housing may resonate during the operation of the transmission.And then,the housing is improved according to the results of ERP analysis.Through the re-analysis,the founding is that the first mode frequency of the housing is higher than the maximum excitation frequency of the system,which reduces the possibility the resonance of the housing.At the same time,the ERP of the housing under different working conditions is reduced compared with the housing before improvement,which proves the effectiveness of the optimization for the housing.This paper,taking the two-speed transmission of the electric vehicle as the research object,conducts the dynamics simulation and the analysis of the shift fork,gear,shaft,bearing and housing of the transmission,which is of great significance and reference value for the research and development of the two-speed transmission.更多还原