【作者】 张伟伟；

【导师】 张海军；

【作者基本信息】 南京农业大学 ， 工程硕士（专业学位）， 2015， 硕士

【摘要】 拖拉机作为农业生产中普遍使用的工具,其动力来源于发动机,经变速器后再传递到后桥系统,从而实现车辆的运行。在此过程当中,变速器起到传递转矩、改变转速的桥梁作用,其关键零部件的强度、刚度及箱体承载性能的优劣必然会影响拖拉机的工作质量。液压机械无级变速器(Hydro-mechanical Continuously Variable Transmission,简称HMCVT)同时具备液压传动中可控调速效率高和机械传动中传递功率大的优点,利用液压和机械功率流的汇流实现无级变速。将该无级变速器应用于非道路大功率拖拉机上不仅能够提高其动力性、燃油经济性,同时还能大幅度降低拖拉机实际操作的复杂性,具有较好的实用价值。本文以南京农业大学自主研发的大功率拖拉机用HMCVT实验样机为研究对象,首先对样机进行了拆装工艺性分析与箱体振动测试实验。其次,针对样机装拆存在的结构问题,提出了分层式铸造箱体以及控制系统零部件集成于箱体的改进设计。最后,运用Solid works对HMCVT所有零部件进行建模和虚拟装配,并运用ANSYS Workbench对箱体和输出轴进行有限元分析。主要研究内容包括:1.根据现有的HMCVT的实验台,分析了该实验台的组成。对该样机进行了拆装工艺性分析和箱体多个位置的振动速度测试,根据不同段位、不同转速以及不同负载等多种情况下测得振动速度大小,评定箱体的工作振动等级。2.对HMCVT的总传动方案组成及不同区段的功率传递路线进行了详细阐述,并介绍双联行星排的汇流机构的设计特点。针对HMCVT样机拆装工艺欠佳的问题,提出了分层式箱体结构设计方案。运用Solid works对HMCVT的所有零部件进行三维建模,并通过虚拟装配来完成结构的干涉检验工作,同时也为后文中有限元分析提供模型基础。3.将HMCVT的分层式箱体装配模型导入Workbench中,对其进行有限元静力学分析和模态分析。通过对HMCVT在HM1区段工况下箱体的静力学分析结果,来评定所设计分层式箱体的强度和刚度;通过箱体的模态分析,来评定箱体在外部激励运转时的稳定性。分析结果表明:所设计的HMCVT箱体刚度、强度、稳定性满足设计要求。4.对HMCVT输出轴进行有限元寿命分析,根据得到的输出轴的疲劳安全系数、疲劳寿命、损伤数值来判断其是否会发生疲劳破坏。分析结果表明:所设计的HMCVT输出轴满足疲劳安全设计要求。更多还原

【Abstract】 Tractors,the commonly tool in agricultural production,which power come from the engine.Then it transfer to the bridge through the transmission.Transmissions,as a bridge in the total running process,transmit torque all the constantly.Which key parts and the gearbox’s properties,such as strength、stiffness and life,will affect the working efficiency of the tractor inevitably.Hydro-mechanical Continuously Variable Transmission rely on hydraulic drive control speed regulation and the combination of mechanical transmission to realize step-less variable speed.It has the merits of the high transmitted power and high transmission efficiency at the same time.The transmission device which used on the high power vehicles not only can improve the power performance and fuel economy,but also can reduce the complexity of the operation.Above all,it has good practical value.This paper based on the independent research and development design of Nanjing agricultural university institute of technology in power tractor hydraulic mechanical automatic transmission on the experimental prototype.After performed the prototype’s disassembly and assembly experiment and the analysis of the gearbox vibration test,the design of the hierarchical casting gearbox is put forward,which can integrate control system integration.In the end,All parts modeling of HMCVT and the virtual assembly were made by Solid works.And the finite element analysis on gearbox and output shaft were made by ANSYS Workbench.The main research points were shown as below:1.Based on the HMCVT laboratorial bench,the components of the bench was analyzed.The disassembly and assembly process of the HMCVT was described detailedly.Many significant parts of prototype vibration velocity was tested.On the basis of measured vibration speed in different case,the reliability of the gear-casing could be assessed.2.The total transmission composition and different section transmission line of HMCVT was described in details,which included the institutions of the double plant row.Solid works,a kind of modeling software,was used to complete all parts of HMCVT modeling and virtual assembly and interference checking,which make basis for following analysis of the finite element.3.The simplified hierarchical gearbox assembly model was exported into ANSYS Workbench,where could made the finite element statics analysis and modal analysis.On the basis of the finite element statics analysis results of the gearbox in HM1,the strength and stiffness of the layering gearbox could be accessed.According to the modal analysis results of gearbox,the stability of the layering gearbox could be accessed.The analysis outcome showed that all the gear casing stiffness,strength and stability meet the requirements.4.Fatigue life of the finite element analysis of the HMCVT output shaft could be worked out.According to the analysis result of the Safety Factor、Life and Damage of the output shaft,whether it would happen to the fatigue damage could be judged.The analysis results showed that the output shaft meet the fatigue safety design requirements.更多还原