Efficiency Evaluation of Continuously Variable Transmissions Including a Planetary Gear Train

With their advantages, continuously variable transmissions have gained more popularity in the last decade by their use in mechanical transmission systems. The present paper aims to analysis the efficiency of the transmission based on the mechanical efficiency of the planetary gear train integrated in such transmission. In this analysis, we consider the mechanical efficiency of the transmission has been determined considering how the efficiency of the CVT members changes as a function of the operating conditions. The efficiency of the planetary gear train as a function of the configuration, speeds in his three input/output shafts, and also with respect to the power flow type. Results are compared with those obtained from other methods performance evaluation of the transmission, available in the literature.

Automatic Scallion Seedling Feeding Mechanism with an Asymmetrical High-order Transmission Gear Train

The current automatic scallion-transplanting machine is a complicated mechanism composed of two linkage mechanisms and two band carriers.It delivers seedlings ine ciently because of the movement limitations of the linkage mechanism.This paper proposes a new high-order non-circular gear train for an automatic scallion-seedling feeding mechanism.The proposed gear train has an asymmetrical transmission ratio;i.e.,its transmission ratio varies.This allows the mechanism’s execution component to move in a long displacement and rotate in a large rotation angle.The long displacement enables the execution component to reach the designed working position,and the large rotation angle allows it to feed a scallion in the required pose.A mathematical model for calculating the asymmetrical transmission ratio was established according to the closure requirements and the full-cycle motion of the driven gear pitch curve.Then,the parameter-design model of the new seedling-feeding mechanism was established,based on precise pose points and trajectory-shape control points.Moreover,an aided-design program was developed to obtain the parameter-solution domain of the scallion-seedling feeding mechanism.The mechanism parameters,which met the seedling-feeding function,were optimized to determine the transmission ratio,using a program and a kinematic simulation.Finally,a prototype of the mechanism was produced,and a seedling-feeding experiment was carried out.One-thousand seedlings were tested at a rate of 100 seedlings per minute,and the statistical success rate was 93.4%.Thus,the automatic scallion-seedling feeding mechanism significantly improves the e ciency of automatically transplanting scallions.

Configuration Synthesis and Performance Analysis of 9‑Speed Automatic Transmissions

Current research of automatic transmission(AT)mainly focuses on the improvement of driving performance,and configuration innovation is one of the main research directions.However,finding new configurations of ATs is one of the main limitations of configuration innovation.In the present study,epicyclic gear trains(EGTs)are applied to investigate mechanisms of 9-speed ATs.Then four kinematic configurations are proposed for automatic transitions.In order to evaluate the performance of proposed mechanisms,the lever analogy method is applied to conduct kinematic and mechanical analyses.The power flow analysis is conducted,and then transmission efficiencies are calculated based on the torque method.The comparative analysis between the proposed and existing mechanisms is carried out where obtained results show that proposed mechanisms have reasonable performance and can be used in ATs.The prototype of an AT is manufactured and the speed test is conducted,which proves the accuracy of analysis and the feasibility of proposed mechanisms.

Investigation of Self Excited Torsional Vibrations of Different Configurations of Automatic Transmission Systems during Engagement

The vehicle drive line system is subjected to torsional vibration from different sources of the system such as;engine fluctuating torque, Hook’s joint and the final drive. However, the essential source is the friction torque induced in the friction elements, during their engagement. In the automatic transmission system, the planetary gear set includes several friction elements such as;clutch, band brakes, and one way clutch. During the engagement, severe torsional vibration is induced by friction which is noticeable by the passengers in the form of what so called vehicle shunt. In present paper, a torsional vibration model for Drive Line (DL) system includes three different configurations of automatic transmission is constructed. A computer program using MATLAB subroutines is implemented to obtain the system response. Effect of system parameters on the dynamic behavior and stability has been investigated. The system damping and the trend of the friction coefficient have an essential effect on the dynamic behavior and stability of the system. The system response is now predictable with change of the system parameters which opens up the opportunity in future to control the vibration level.

Study of Stress Sources and Critical Stress Combinations for the Input Shaft of a Longitudinally Mounted Four Speed Automotive Automatic Transmission Model

In the present paper;two models of the input shaft for a Longitudinal Mounted four Speed Automotive Automatic Transmission for the first time were introduced to describe the input shaft critical loads. In the first model;the DC (Direct Clutch) connects two gears together. This gives no change in the set torque (the set output torque equal to the set input torque). In the second model;the ODB (Over Drive Brake) fixes one element of the planetary set. This is resulting, the gear set gives reduction ratio (the set output torque is not equal to the set input torque). So, the transmission input shaft is worked under two different working operating conditions of torque. Also, it is loaded by a two vertical loads which are coming from the turbine and planetary set loads respectively. They are shown that there are three critical combinations of forces (contact force, shear force, and normal force) applied on the input shaft. The critical forces can be possibility exist three types of cracks for the input shaft cross section they are: transverse (torsion stress), longitudinal (bending stress), and vertical (shear stress). The three cracks are studied in this article. The article considers three stress factors: shearing torsion stress, shear stress, and bending stress.

A761E自动变速器动力传递的分析及计算

A761E是丰田轿车上的6速电控自动变速器,由1个单排双级行星齿轮机构和2个单排单级行星齿轮机构组成,其内部共有12个换挡执行元件,这3排行星齿轮机构可产生6个前进挡和1个倒挡,根据不同挡位各执行元件的状态,可逐个分析各挡动力传动路线,通过对行星齿轮机构建立运动方程和分析约束条件,可逐个进行各挡传动比的计算。动力传动的分析及计算是自动变速器维修的理论基础和故障判断依据。

FA针摆传动摆线轮参数化设计

为快速实现FA针摆传动中复杂实体———摆线轮的自动化精确建模,通过建立描述摆线轮齿廓的数学模型,采用Pro/E提供的高级编程语言,完成了自动特征建模的参数化。设计人员只需输入摆线轮的已知设计参数,就可迅速准确地生成所需的三维实体模型。

某8AT变速箱行星齿轮动力流计算

通过对某8AT变速箱液力变矩器和行星齿轮的动力传动进行拆解分析,详细分析液力变矩器和行星齿轮的工作原理,对各个挡位下四组行星齿轮机构制动器和离合器的结合情况进行分析,并绘制出动力传递路线,计算出各个挡位的传动比。各挡位下行星齿轮动力流分析计算方法可以指导某8AT变速箱的故障诊断和维修,并为AT变速箱设计提供重要的理论参考。

基于MASTA高速比复合行星轮系传动效率仿真分析

针对高速比复合行星轮系传动效率较低、影响因素较多等问题,以某型斜齿轮高速比复合行星轮系为研究对象,基于MASTA对高速比复合行星轮系传动效率进行仿真分析。仿真结果表明:随着加载转速增加,高速比复合行星轮系中的轴承和齿轮啮合损失功率逐渐减小,风阻损失功率逐渐增加,传动效率逐渐减小;随着加载扭矩增加,高速比复合行星轮系中的轴承和齿轮啮合损失功率逐渐增加,风阻损失功率逐渐减小,传动效率逐渐增加。该研究可为高速比复合行星轮系传动效率提升、传动性能的改善等方面提供理论依据。

基于ANSYS Workbench的2K-H行星齿轮减速器行星轮系有限元分析

以三维软件UG为设计平台,有限元软件ANSYS Workbench为分析工具,对2K-H行星齿轮减速器的核心传动装置进行了静力学与模态特性分析.通过对行星轮系的静力学分析,得到了模型的等效应力、应变和安全因子云图.最后对行星轮系装配体进行了模态分析,得到了系统的前六阶模态振型,为后续行星轮系进一步的动力学及运动学分析奠定了基础.

基于仿真模型的AT变速器行星轮系均载试验技术研究

汽车液力自动变速器的行星轮系结构紧凑,进行均载试验研究时难以直接对齿轮的受力和变形进行测试。通过建立行星轮系接触分析模型计算轮系应力分布,重点分析了行星轮系销轴和行星架所受应力情况,证明了销轴及行星架特定位置的应力与对应行星轮所受载荷呈线性关系。理论证明了综合运用销轴、行星架应力响应计算得到的应力均载系数与行星轮均载系数具有较好的一致性,并以此为依据提出了一种基于应力测试技术的汽车液力自动变速器行星轮系均载系数的试验方法。

微型行星齿轮传动设计与分析

提出一种应用于某航空发动机中空气涡轮起动机的微型行星齿轮传动设计方案,对传动系统的构型进行结构设计、参数匹配;采用有限元分析软件ANSYS对其重要零部件进行强度校核,基于正交试验法对减速器结构进行优化,为微型行星减速结构在航空发动机起动机等航空产品中的推广与应用提供理论支撑。

基于Romax Designer的NGW型行星齿轮箱传动性能分析

针对有效评估NGW型行星齿轮箱传动性能的问题,在完成齿轮基本参数设计的基础上,采用Romax Designer分析行星传动系统的传动性能。首先,以齿根弯曲强度为设计准则,确定NGW型行星传动系统中齿轮基本参数;然后,通过无干涉啮合条件并以齿面接触疲劳强度的校核准则,验证了所设计的NGW型行星传动系统能够满足运动条件和齿面接触要求;最后,基于Romax Designer建立NGW型行星传动系统的几何模型,并分别以最大齿面接触应力和各齿轮传动误差与单位齿宽载荷为指标对这一模型展开静态分析和动态分析。研究结果表明:内/外啮合副的传动误差波动幅值均小于1.4μm,且各齿轮单位齿宽载荷波动值均小于90 N/mm,行星传动系统传动性能良好。

齿面粗糙度对风电齿轮箱行星轮系动力学特性影响

为研究齿面粗糙度对行星轮系动力学特性的影响,提出行星轮系齿轮副动态承载接触分析与系统振动位移耦合方法。以某型兆瓦级风电齿轮箱行星轮系为研究对象,基于分形理论对轮齿粗糙表面进行分形表征,通过齿轮副啮合变形协调条件,构建齿面动态承载接触状态与构件振动位移、粗糙齿面啮合误差以及摩擦力的关联关系,建立风电齿轮箱行星轮系动力学模型,分析粗糙齿面啮合误差与摩擦力对系统动态特性的影响。结果表明:随着粗糙度的增大,齿面载荷峰值与波动幅值增大,动态啮合刚度幅值出现明显波动,均载性能降低;增大粗糙度会降低行星轮系临界转速,在低转速区域内,其具有激励增振作用,而在临界转速区域附近,其具有阻尼减振作用;摩擦力主要影响行星轮系各构件振动位移,可改变动态啮合力在少齿啮合区的幅值。

行星轮系力学超材料及其连续可调力学性能

针对高可靠性复杂工况需求的连续可调力学特性,分别研究基于双层行星轮系和拉式行星轮系的连续刚度可调及振动传递率可调的力学超材料;应用空间梁单元建立弯曲梁的变径向载荷下刚度连续可调理论力学模型及模态分析模型,研究基于行星轮系的超材料刚度连续可调理论及模态振型特点,为基于行星轮系连续刚度可调及振动传递率可调的力学超材料提供理论支撑;建立基于双层行星轮系和拉式行星轮系单胞及2×2胞的力学超材料有限元模型,分别计算分析压缩弹性模量、剪切模量和振动传递率与控制变量的作用关系。研究结果表明:基于双层行星轮系和拉式行星轮系力学超材料的压缩弹性模量和剪切模量分别具有9~15倍和1~2.5倍连续可调范围,其振动传递率亦可通过控制变量进行调控;理论计算和仿真分析结果一致性较好。

特性参数连续可变复合传动的优化与选型

复合传动系的核心技术在于匹配,基于不同复合传动系统中各项评价指标实际的重要性与适应性,从所有可能适用的功率分流方案中选出最优方案,完成一次完整的优化选型设计。为避免优秀方案被漏选的问题,对12种复合传动的速比和转矩进行分析,根据传动系统各部件的转矩能力,提出传动路线中3个关键位置的转矩系数。以速比变化范围和3个转矩系数为目标函数,使用非支配遗传算法NSGA-II优化两个固定齿轮副传动比,得出12种复合传动的综合最优状态。基于评价指标重要性与适应性,提出一套行星排特性参数连续可变复合传动系统的分级多步选型方法,完成一次完整的优化选型设计。相比优化前的系统:速比范围提高24%,最大输出转矩提高18.92%,效率提高2.25%。

农业拖拉机用多段液压机械无级变速器设计

提出一种由单个普通行星排构成的简单高效拖拉机用多段液压机械无级变速器传动结构 ,分析了变速器的变速特性、转矩特性、平稳换段条件和液压功率分流比 ,通过装机实例表明其无级变速范围宽 ,在车辆常用工作速度段液压功率分流比低于 2 0 % ,在与中耕、犁耕、运输作业对应的高、中、低速度区间可分别实现 3个高效率纯机械档 ,有利于提高车辆的动力性和经济性。

割草调制机的调制机构设计与试验

针对割草调制机的压扁辊在机械调制作业过程中出现的不易调节问题,设计了一种新型割草调制机构.以提升作业效果和作业可靠性为主要设计目标,保证农艺要求为约束条件,采用理论分析的方法研究了该机构的作业要求、工作机理和机械性能,并对压扁辊的几何外形和传动机构进行了参数设计,最后进行了不同设计参数下的作业效果试验.试验结果表明:采用凹凸纹啮合间隙较小的压扁辊,以较大的压缩比并交错喂入时压扁比例达到53.71%,为各项试验因素水平中最优作业效果.

用杠杆模拟法建立行星变速器动力学模型

本文对用于行星式变速器分析的杠杆模拟法进行完善和拓展。系统地给出了杠杆模拟法的理论和应用方法,并将该方法推广成为行星式变速器动力学分析的通用方法。应用所提出的方法建立了AG4自动变速器的动力学模型。

复合行星齿轮传动系统虚拟样机仿真研究

根据Ravigneaux式复合行星齿轮传动系统的典型结构,分析了系统的传动比与啮合频率。为获得Ravigneaux式复合行星齿轮传动系统轮齿接触力的变化规律,运用三维CAD软件SolidWorks建立了系统的三维实体模型,以ADAMS软件为平台建立了系统的虚拟样机模型。给出基于Hertz接触理论的齿轮啮合传动时轮齿接触力的计算方法,验证了系统传动比,对小太阳轮与短行星轮啮合的综合接触力、x方向接触力和y方向接触力的变化规律及其频谱特性进行仿真研究。仿真结果表明,接触力的幅值波动显著,具有明显的周期性。x方向接触力和y方向接触力具有相同的频谱特征,相位相差约90°。频谱中出现小太阳轮的旋转频率和系统啮合频率的1至7倍频率成分,存在明显的调制特性。通过对Ravigneaux式复合行星齿轮传动系统虚拟样机仿真的研究,为改善系统动力学特性以及实现系统的动态设计提供了指导依据。