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.

Design of Vegetable Pot Seedling Pick‑up Mechanism with Planetary Gear Train

It has been challenging to design seedling pick-up mechanism based on given key points and trajectories,because it involves dimensional synthesis and rod length optimization.In this paper,the dimensional synthesis of seedling pickup mechanism with planetary gear train was studied based on the data of given key points and the trajectory of the endpoint of seedling pick-up mechanism.Given the positions and orientations requirements of the five key points,the study first conducted a dimensional synthesis of the linkage size and center of rotation.The next steps were to select a reasonable solution and optimize the data values based on the ideal seedling trajectory.The link motion was driven by the planetary gear train of the two-stage gear.Four pitch curves of noncircular gears were obtained by calculating and distributing the transmission ratio according to the data.For the pitch curve with two convex points,the tooth profile design method of incomplete noncircular gear was applied.The seedling pick-up mechanism was tested by a virtual prototype and a physical prototype designed with the obtained parameter values.The results were consistent with the theoretical design requirements,confirming that the mechanism meets the expected requirements for picking seedlings up.This paper presents a new design method of vegetable pot seedling pick-up mechanism for an automatic vegetable transplanter.

Design and Experiment of Non-circular Combined Gear Train Beating-up Mechanism

The most important performance of a beating-up mechanism is that the dwelling time of the sley must ensure the completion of the weft insertion. To meet this requirement, a new non-circular combined gear train beating-up mechanism which is composed of two-stage planetary gear trains is proposed. The first-stage is a Fourier planetary gear train and the second-stage is a non-circular planetary gear train. For designing of this new mechanism, the ideal kinematic equations of the sley are constructed first. Then the kinematic model of the first-stage Fourier planetary gear train is established and the reverse solution for the pitch curves of the second-stage non-circular gears is deduced. With a computer-aided design program, the influences of several important parameters on the pitch curves of the second-stage non-circular gears are analyzed, and a set of preferable structural parameters are obtained. Finally, a test bed of this mechanism is developed and the experimental results show that this new beating-up mechanism can achieve the designed dwelling time, namely it can meet the requirements of beating-up process.

The Mesh Efficiency of the Planetary Mechanism of 2K-H[D] Style

The mesh efficiency of the planetary mechanism of 2K - H[D] style is discussed. It comes to a new formula. Usually, an approximate value is taken as the mesh efficiency of a planetary mechanism. If the formula is used, the theoretical value of mesh efficiency can be gotten. The theoretical mesh efficiency can help engineers to know the true efficiency of 2K - H[D] style when it runs. The mesh efficiency serves the transmitting efficiency of a planetary mechanism.

不等速行星轮系机构混合多位姿综合方法及应用

为使不等速行星轮系机构能够实现精准取放任务,提出一种混合多位姿运动综合方法。将不等速行星轮系机构视为平面2R开链机构与非圆齿轮传动机构的组合,以理想运动轨迹上关键位姿(精确与近似)数据为约束,基于杆长不变条件建立平面2R开链机构混合多位姿运动综合模型,并利用同伦算法求解获得最优结构参数;给出了非圆齿轮传动比计算与分配方法,实现了不等速行星轮系机构的混合多位姿运动综合。将此运动综合方法应用于农业机械领域取苗机构的设计可满足蔬菜穴盘苗精准取放移栽要求,通过虚拟仿真分析、物理样机实验验证了所提方法的正确性。

青菜高密度移栽机植苗机构的设计与试验

目前国内移栽机尚无成熟的适用于青菜等多行密植蔬菜移栽的植苗机构;针对小株距小行距、高效率的密植移栽要求,设计了一种非圆齿轮行星轮系八行同步植苗机构,并进行了运动学仿真和田间移栽试验。对非圆齿轮行星轮系进行了运动学建模与分析,开发了植苗机构辅助分析与优化设计软件;分析了不同机构参数对植苗轨迹姿态的影响,并通过人机交互的方式得到一组满足青菜小株距移栽要求的机构参数;建立了八行同步植苗机构的三维模型,利用虚拟样机仿真技术绘制出仿真轨迹,并与理论轨迹进行对比,以验证植苗机构三维设计的正确性;开展了田间移栽试验,以验证该机构的可行性和实用性。试验结果表明:在作业转速为15r/min、前进速度为55mm/s的情况下,八行植苗机构的作业株距和行距均为110mm,平均植苗成功率为93.9%,移栽密度超过70株/m2,试验移栽效率为240株/min,表明该机构在机械化密植移栽作业中有较高的应用价值。该研究为高密度移栽机植苗机构的研发提供了理论和试验依据,促进了密植型蔬菜钵苗机械化移栽的进程,为密植移栽机的进一步研究提供技术支持和参考。

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。

Optimization design and test of rice plug seedling transplanting mechanism of planetary gear train with incomplete eccentric circular gear and non-circular gears

In order to solve the problem of the high-speed mechanized transplanting of rice plug seedlings,the design requirements of transplanting mechanism for rice plug seedlings were analyzed and a kind of rice plug seedling transplanting mechanism of planetary gear train based on the drive with incomplete eccentric circular gear and non-circular gears was designed innovatively.The laboratory kinematics was examined.The working principle of the transplanting mechanism for rice plug seedlings was studied,kinematics analysis of the transplanting mechanism was carried out and its kinematic model was set up.A human-computer interaction optimization method was used to optimize the parameters of the transplanting mechanism.The computer aided analysis and optimization software of the transplanting mechanism based on Visual Basic 6.0 was developed.Through analyzing the influence of design variables on the optimization objectives of the transplanting mechanism,a set of parameters of the transplanting mechanism which meet the requirements of transplanting trajectory and posture for transplanting rice seedlings were obtained by means of human-computer interaction.The structure of the transplanting mechanism was designed according to this set of parameters,and its virtual prototype and physical prototype were set up and manufactured,respectively.The kinematic simulation test and high-speed photography kinematic test of the transplanting mechanism were conducted to obtain its kinematic performances,such as transplanting trajectory and posture.The results of bench test,simulation analysis and theoretical analysis were almost in agreement,which verified the correctness of the theoretical model and design results of the transplanting mechanism,indicating that the optimized transplanting mechanism can satisfy the requirements of transplanting rice seedlings and be applied in the rice plug seedling transplanter.

Analytical geometry method of planetary gear trains

This paper presents an analytical geometry method for kinematics and efficiency of planetary gear trains (PGTs). The novel method which is capable of evolution and contrast analysis of mechanism kinematics, can be applied to any typical one-and two-degree-of-freedom plane PGTs containing any number of simple, compound or complex-compound planetary gear sets. The efficiency analysis of this method features a systematized and programmed process and its independence of the speed ratio. The primary contribution of this work lies in the integration of quantitative calculation, qualitative evolution and comparative analysis of kinematics of PGTs into one diagram, and in the integration of kinematics and efficiency analysis into a single method system. First, the analytical geometry method is defined, its basic properties are given, and the systematization procedure to perform kinematic analysis is demonstrated. As an application, analytical geometry diagrams of common PGTs are exhibited in the form of a list, whose kinematic characteristics and general evolution tendency are discussed. Then, with the mapping of PGTs onto the angular speed plane, the efficiency formula of analytical geometry, which has an extremely concise form, and a simple method for power flow estimation are put forward. Moreover, a general procedure is provided to analyze the efficiency and power flow. Finally, four numerical examples including a complicated eleven-link differential PGTs are given to illustrate the simpleness and intuitiveness of the analytical geometry method.

旋转式水稻钵苗移栽机构的机理分析与参数优化

通过分析国内外水稻钵苗移栽机的缺点与不足,根据水稻钵苗移栽机的特征与优点,提出一种以椭圆-不完全非圆齿轮为传动机构的旋转式水稻钵苗移栽机构,使水稻移栽达到高产高效率的移栽水平。首先,在分析该移栽机构工作原理的基础上,建立了椭圆-不完全非圆齿轮机构的运动学模型。然后基于Visual Basic 6.0可视化编程软件,开发了椭圆-不完全非圆齿轮行星轮系水稻钵苗移栽机构的辅助分析与优化软件。最后,通过分析各参数对移栽轨迹的影响,利用人机交互的优化方法,得到了一组较优的符合水稻钵苗移栽要求的结构参数,该研究可为旋转式水稻钵苗移栽机构的设计提供参考。

偏心齿轮-非圆齿轮行星轮系在后插旋转式分插机构中的应用

针对步行式水稻插秧机的工作要求,将偏心齿轮—非圆齿轮行星轮系应用于水稻插秧机后插式分插机构的设计中,研制出偏心齿轮-非圆齿轮后插旋转式分插机构。分析了偏心齿轮—非圆齿轮行星轮系的运动学特性,建立运动学模型,并自主开发了分插机构辅助分析与优化软件,通过人机交互优化方式对该分插机构进行参数优化,完成了该分插机构的二维和三维设计,并进行了虚拟样机试验,试验结果表明:该分插机构可以形成"海豚形"插秧静轨迹,满足步行式水稻插秧机的工作要求。

行星齿轮传动动力学特性研究进展

行星齿轮传动由于结构紧凑、承载能力强等优点而广泛应用在各个工业领域。振动和噪声是行星齿轮传动的主要问题。本文从动力学模型、自由振动、响应求解、均载及振动抑制等几个方面对国内外行星齿轮传动系统弹性动力学及相关研究进行了综述。介绍了行星齿轮传动弹性动力学研究中常用的纯扭转振动模型、横向—回转耦合振动模型以及有限元模型,对三种常用的响应求解方法进行了分析和评述。最后指出了需要进一步研究的几个问题。

一种新型行星轮系机构的研究

分析现有行星轮系机构,提出一种新型的基于偏心圆-不完全非圆齿轮间歇传动行星轮系机构,在一个工作周期内,实现行星轮相对行星架作非匀速间歇转动。介绍该机构的工作原理和运动学特性,建立行星轮系机构模型。开发该行星轮系机构的计算机辅助分析软件,通过人机交互方式得出一组满足非匀速间歇传动的结构参数。基于该参数对该行星轮系机构进行设计及试验,并将该行星轮系机构成功应用于穴盘苗取苗机构的创新设计,并进行取苗试验,从而验证了该行星轮系机构理论模型的正确性和可行性。

B样条非圆齿轮行星轮系水稻钵苗移栽机构的设计与优化

钵苗移栽可以提高产量,对中国粮食安全具有重要意义。在分析水稻钵苗移栽机构最新研究进展的基础上,该文作者发明了基于三次非均匀有理B样条曲线的非圆齿轮行星轮系钵苗移栽机构。选取非圆齿轮节曲线上的13个型值点来控制和表达非圆齿轮的节曲线形状,通过该移栽机构的运动学分析,在确定优化目标的基础上,建立了夹秧片姿态和尖点轨迹的目标函数,将目标函数转化为优化数学模型。利用MATLAB GU平台,开发出该移栽机构的计算机辅助分析与优化软件,通过人机对话调整型值点,优化夹秧片姿态和尖点轨迹,从而获得了一组满足水稻钵苗移栽要求的结构参数。建立三维模型,并利用Admas进行虚拟样机仿真,验证了该移栽机构数学模型的正确性。

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.

水稻钵苗移栽机变性卵形齿轮分秧机构的运动机理分析

针对水稻钵苗移栽机的工作要求,将变性卵形齿轮行星轮系应用于其分秧机构的设计中,设计了一种新型的旋转式分秧机构;在分析变性卵形齿轮行星轮系运动学特性的基础上,建立了分秧机构的运动学模型,编写了分秧机构辅助分析与优化软件以及变性卵形齿轮齿廓生成软件;通过人机交互方式对该分秧机构结构参数进行优化,得到了最优参数。借助虚拟仿真技术,验证了该分秧机构形成的带有"针形"凸起的"桃形"静轨迹,能够满足水稻移栽机的工作要求。

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。

非圆齿轮行星轮系引纬机构的反求设计与运动学分析

为了分析非圆齿轮行星轮系引纬机构的运动学特性并获得一组较优的参数,建立了该机构的运动学分析模型,基于Visual Basic 6.0平台编写了该机构的辅助分析与运动仿真软件,分析了几个重要参数对机构中非圆齿轮节曲线的影响,得到了一组较优的机构参数。对该组参数下的引纬机构进行运动仿真分析,在相同筘幅和织机主轴转速条件下,对非圆齿轮行星轮系引纬机构和TT96剑杆织机引纬机构的运动学特性进行了比较,结果表明非圆齿轮行星轮系引纬机构具有较小的最大速度值和最大加速度值,能够满足引纬要求。

二阶自由非圆齿轮行星系钵苗移栽机取苗机构

为满足旱田钵苗移栽取苗机构理想鹰嘴形工作轨迹要求,提出了连续传动的二阶自由非圆齿轮行星轮系取苗机构,以实现取苗爪周期性二次不等幅摆动规律。利用曲线拟合方法构建自由传动比函数,建立机构不等速传动的数学模型,编写机构分析软件,确定传动比函数和机构参数,研制取苗机构并进行了高速录像试验。结果表明,该型取苗机构的工作轨迹和理论计算吻合,能够实现取苗深度35 mm,取苗爪在钵体中穴口小于5 mm,取苗爪入钵和出钵段姿态满足工作要求。

行星齿轮传动啮合效率分析

齿轮的基本啮合效率是计算行星齿轮传动效率的基础.指出了齿轮传动在升速和减速时基本啮合效率不相等,升速时比减速时要高,这不同于以往的观点.为论证此结论,采用了一种新方法,分析了内啮合、外啮合直齿轮和斜齿轮传动的基本啮合效率,推导了它们在升速和减速两种状态时,基本啮合效率精确的计算公式,并以2K-H行星齿轮传动为例进行了分析.