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.

Gear Drive Mechanism for Continuous Variable Valve Timing of IC Engines

Continuous variable valve actuating (CVVA) technology provides high potential in achieving high performance, low fuel consumption and pollutant reduction. To get full benefits from (CVVT) various types of mechanisms have been proposed and designed. Some of these mechanisms are in production and have shown significant benefits in improving engine performance. In this investigation a newly designed gear drive mechanism that controls the intake valve opening (IVO) and closing (IVC) angles is studied. The control scheme is based on maximizing the engine brake power (P) and specific fuel consumption (BSFC) at any engine speed by continuously varying the phase between the cam shaft angle and the crank shaft angle. A single-cylinder engine is simulated by the “LOTUS” software to find out the optimum phase angle for maximum power and minimum fuel consumption at a given engine speed. The mechanism is a planetary gear drive designed for precise and continuous control. This mechanism has a simple design and operation conditions which can change the phase angle without limitation.

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.

Performances of a Balanced Hydraulic Motor with Planetary Gear Train

The current research of a balanced hydraulic motor focuses on the characteristics of the motor with three planet gears.References of a balanced hydraulic motor with more than three planet gears are hardly found.In order to study the characteristics of a balanced hydraulic motor with planetary gear train that includes more than three planet gears,on the basis of analysis of the structure and working principle of a balanced hydraulic motor with planetary gear train,formulas are deduced for calculating the hydraulic motor＇s primary performance indexes such as displacement,unit volume displacement,flowrate fluctuation ratio,etc.Influences of the gears＇ tooth number on displacement and flowrate characteristics are analyzed.In order to guarantee the reliability of sealing capability,the necessary conditions that tooth number of the sun gear and the planet gears should satisfy are discussed.Selecting large unit volume displacement and small displacement fluctuation ratio as designing objectives,a balanced hydraulic motor with three planet gears and a common gear motor are designed under the conditions of same displacement,tooth addendum coefficien and clearance coefficient.By comparing the unit volume displacement and fluctuation ratio of the two motors,it can be seen that the balanced hydraulic motor with planetary gear train has the advantages of smaller fluctuation ratio and larger unit volume displacement.The results provide theoretical basis for choosing gear tooth-number of this kind of hydraulic motor.

非圆齿轮-连杆组合式水稻钵苗膜上移栽机构优化设计与试验

为实现机械化一体式水稻钵苗膜上移栽要求,提出非圆齿轮-连杆组合式行星轮系移栽机构,用一套机构实现取苗、送苗、破膜挖穴和栽植4个工序协同配合作业,满足水稻钵苗膜上移栽所需的轨迹与姿态要求。对移栽机构进行理论分析并建立运动学模型,结合优化目标,基于Matlab GUI平台开发了数字可视化优化设计软件,通过人机交互获得1组满足移栽要求的机构参数。根据优化参数对机构开展结构设计与三维建模,通过ADAMS软件完成了虚拟样机仿真验证。研制了水稻钵苗膜上移栽机构物理样机与多功能试验测试台架,开展了移栽机构在空转和带苗状态下运动学特性和工作性能试验,结果表明,理论轨迹、虚拟样机仿真轨迹和物理样机台架试验轨迹在误差允许范围内保持一致,验证了移栽机构设计的一致性与正确性,性能试验结果:取苗成功率为94%,移栽成功率为92.36%,栽植株距变异系数为2.67%,满足移栽作业要求,验证了水稻钵苗膜上移栽机构设计的合理性与可行性。

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.

高接低栽式差速变姿态行星轮系栽植机构设计与试验

针对目前旱地蔬菜钵苗移栽机大多适用于大株距(大于260 mm)移栽且投接苗与栽植位置作业高度差大、移栽性能不佳等问题,本文提出一种高接低栽式差速变姿态行星轮系栽植机构。根据中小株距蔬菜钵苗移栽农艺指导与机构设计要求,解析双行星架差速行星轮系栽植机构工作原理并建立其运动学理论模型;结合所提出优化目标构建目标函数,开发了基于Matlab GUI的栽植机构计算机辅助分析优化设计软件,通过人机交互方式获得1组较优的机构设计参数组合。通过三维建模与装配以及ADAMS软件虚拟仿真,初步验证了机构正确性与合理性。开展栽植机构物理样机试制与试验台架系统开发研究,通过空转试验测试,验证了栽植机构实际作业轨迹、姿态与虚拟仿真及理论设计的一致性;开展栽植机构接苗与栽植性能试验,试验结果表明,栽植机构在接苗与栽植各项试验指标均较为优秀,能够满足栽植机构预期设计要求与旱地移栽机械标准,验证了该机构的可行性与实用性。

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。

重载行星轮系安装误差对系统均载性能的影响

行星轮安装误差的存在会导致行星轮系产生不均载问题,进而会影响减速器的传动性能和寿命。以往的研究未明确定义不同角度下的安装误差对系统均载性能的影响,并且关于多行星轮对系统均载影响的研究(在不同安装误差和不同输入功率下)也较少。为此,研究了实际应用中行星轮系安装误差对系统均载性能的影响。首先,以重载四行星轮系为研究对象,建立了行星轮径向和切向安装误差的综合误差表达形式;然后,基于轮系的传动模型,分析了单行星轮不同安装误差角和误差数值对系统均载的影响;最后,在单行星轮的基础上分析了不同工况和误差配置下多行星轮对系统均载的影响。研究结果表明:行星轮的切向安装误差对系统均载影响最大,径向安装误差对系统均载影响最小,当单行星轮安装误差数值为60μm,安装误差角θ从径向往切向方向靠近时,行星系统的均载系数增大了9.6%;误差绝对值越大,均载系数越大,当单行星轮安装误差数值从-30μm到-60μm时,系统的均载系数增大了4.6%;多行星轮存在切向安装误差对系统均载的影响可以用有效误差来衡量;齿轮承载范围内,随着输入功率的增大,安装误差对系统均载的影响逐渐减小。

裂纹故障下的行星轮系唯象建模及其故障诊断

故障机制是故障诊断的基础,动态建模是研究故障机制的重要手段。现有的行星轮系动态建模主要包括动力学建模和唯象建模两方面。动力学建模难度大,且更多关注单个零部件的动力学特性;唯象建模则从宏观层面对系统特性进行描述。因此,建立行星轮系振动唯象模型,对行星轮系故障机制研究大有裨益。齿根裂纹是行星轮系中常见的故障类型之一。为此,建立了行星轮系正常与裂纹故障下的振动唯象模型,基于冲击动力学理论,计算了轮齿进入啮合时的啮合冲击力及其对动载因数的影响;在此基础上,建立了考虑啮合冲击影响的行星轮系振动唯象模型,得到了正常、太阳轮裂纹、行星轮裂纹等不同健康状态下的振动唯象模型响应;采用均方根、峭度等统计指标对模型响应进行分析,对比了各项统计指标在反映裂纹故障状态时的敏感性。结果表明,峭度可以作为有效反映行星轮系裂纹故障的指标之一。

基于自注意机制胶囊网络的行星齿轮箱故障诊断

针对实际工程中行星齿轮箱故障数据有限、诊断准确率不高的问题,提出一种基于自注意机制胶囊网络的故障诊断方法。直接将采集到的行星齿轮箱振动信号作为输入,用首层宽卷积层提取浅层特征,过滤输入中的高频噪声;引入自注意机制关注信号关键特征;再次将所提特征输入胶囊层,进一步提取特征并实现故障分类;采用行星齿轮箱实验平台数据对所提方法进行实验验证。实验结果表明:在样本数量有限的情况下,所提方法仍能取得不错的诊断准确率。

数学建模在水稻插秧机作业优化中的应用

为了降低插秧机的作业故障次数、提升插秧效率和插秧质量,对数学建模在水稻插秧机作业优化中的应用进行了研究。为了有效提升作业效率和作业质量,分插机构的传动部件改进为非圆齿轮行星系,并针对传动装置建立数学模型并分析。为了验证水稻插秧机的结构是否合理,对其进行了仿真试验,结果表明:水稻插秧机的结构合理,可将其应用于实际生产。

Design and experiment of double planet carrier planetary gear flower transplanting mechanism

At present,there is a lack of miniaturized and highly reliable plug seedling transplanting mechanism in flowerpots planting operation,in order to meet the needs of large displacement and high vertical uprightness for flower transplanting,the paper combined the transmission characteristics of the non-circular gear planetary gear train with the swing flexibility of the cam gear and proposed a double planet carrier planetary gear transplanting mechanism.The linkage of the mechanism performs variable speed rotation relative to the first planet carrier,the linkage serves as the second planet carrier,and the transplanting arm performs variable speed swing relative to the linkage.A mathematical model of a single planetary carrier mechanism was first established using the method of open linkage group solution domain synthesis,then established the kinematic equations of the second planet carrier and the transplanting arm.The two parts are combined to form the mathematical solution model of the proposed mechanism.The initial trajectory was planned according to the trajectory requirements of seedlings planting operation,the non-circular gear pitch curve in the first planet carrier was obtained and the length of the first planet carrier is 120 mm.Then using the key points’angular deviation between the initial trajectory and the improved trajectory to obtain the cam parameters which driving the transplant arm,consequently determined the length of the second planet carrier is 69.25 mm and the length of the transplant arm is 112.4 mm.Finally,the prototype of the mechanism was manufactured,and the test verified the correctness of the design method of the double planet carrier planetary gear flower potting transplanting mechanism.The transplanting success rate of this mechanism reached 94.43%,and the plug seedlings planted in flowerpots had high uprightness.This research can provide a reference for the automatic development of research on flower transplanting machines.

Design and experimental study of a planetary gearing mechanism based on twice unequal amplitude transmission ratio

To obtain the optimal seedling taking trajectory,this study proposed the adjustment of the total transmission ratio curve by using human-computer interaction.On the basis of this design method,a planetary non-circular gear mechanism was designed that can realize the twice unequal amplitude transmission ratio to meet the seedling harvesting requirements.The cubic non-uniform B-spline curve was used to fit the twice unequal amplitude transmission ratio curve,and the transmission ratio was freely distributed in two levels.The seedling pick-up mechanism was designed by controlling the seedling taking track and the corresponding attitude directly through the local section of the total transmission ratio,and the gear pitch curve was directly controlled by the transmission ratio.The kinematics model of the seedling pick-up mechanism was also established.Furthermore,the influence of the total transmission ratio on the seedling picking track,the ratio of the wave crest to the amplitude,and the mechanism parameters were discussed.A human-computer interactive optimization software was developed using Matlab,and a set of optimal parameters for the seedling pick-up mechanism was obtained to meet the transplanting requirements.By using the Adams software,the virtual prototype simulation of the seedling pick-up mechanism was completed,and the idle experiment for the track and attitude of the prototype was conducted through high-speed camera technology.The theoretical,simulated,and experimental trajectories were consistent with each other.Results revealed that the success rate of the seedling picking exceeded 90%when the rotation speeds were 40 r/min,50 r/min,and 60 r/min,and the qualified rate of the matrix decreased with the increase in rotating speed.Moreover,the number of damaged plants increased with the increase in rotating speed.The experimental results showed that the seedling pick-up mechanism designed using the proposed method demonstrated a good effect and met the required seedling picking performance.

电子机械制动器的建模、仿真和实验研究

为了解决目前车辆普遍装配液压制动系统存在的响应滞后问题,以实验室某目标车型为例,对其匹配的电子机械制动器(EMB)进行了设计建模、仿真分析和实验研究。首先,根据车型参数确定制动间隙与最大制动力并完成了制动效能的校核工作,采用“电机+行星齿轮减速器+滚珠丝杠”的选型进行了组合设计,使用CATIA对EMB各部件进行了三维建模,利用ANSYS/Workbench对制动钳钳体进行了力学性能仿真分析;然后,根据EMB各部件间力学与几何关系分别建立了对应的数学模型,在MATLAB/Simulink中建立EMB整体仿真模型后完成了对电机转速特性、堵转转矩特性及EMB最大夹紧力的仿真;最后,搭建了实验平台,结合实验结果对仿真结果进行了验证。研究结果表明:EMB工作时的最大应力为安全极限的34.87%,制动间隙消除速度提高了42.31%,达到最大制动夹紧力的时间降低了45.82%,显著提升了目标车型的制动性能。

机电复合传动高线速转子-行星齿轮系统耦合振动特性

机电复合传动系统作为未来传动形式的主要发展方向,有着传递功率大,运转速度高等特点。在运行过程中转子自身由于高转速所带来的振动会与行星齿轮啮合时产生的振动相互影响,从而形成转子-行星齿轮系统耦合振动过程。建立了机电复合传动转子-行星齿轮系统耦合振动动力学模型,分析了不同转速下转子-行星齿轮系统振动特性,开展了转子-行星齿轮系统模态分析并将模态分析结果与振动特性进行了对比,通过研究转子-行星齿轮系统的振动特性,揭示了系统振动随转速升高而增大,在经过一定转速区间时振动会维持在一定水平内,随着转速继续升高,系统振动又将逐渐增大。通过研究得到了齿轮系统与驱动电机转子耦合作用下的振动特性,为机电复合传动系统高速化设计提供了理论依据。

气体钻井发电机涡轮设计与性能试验

近年,电磁波和微波随钻测量传输技术被应用于气体钻井井眼轨迹的测量与控制,但由于电池供电功率较低,无法满足大于3000 m井深的随钻测控需求,井下发电机技术可有效提高传输功率,只是气体密度低且可压缩,涡轮和导轮构成的常规组件无法驱动井下发电机正常运转。文章在研究了二维流场中涡轮叶片的速度矢量三角形基础上,结合气体钻井工况分析了涡轮的输出转速、扭矩关系,提出借助行星轮机构提高涡轮输出抗扭特性的设计思路,设计出适用于气体钻井的井下发电机驱动涡轮,使发电机在负载改变时依然可维持稳定输出,并运用计算流体动力学软件(CFD)对涡轮进行全三维流场仿真模拟,通过测试装置验证了发电机的输出效果。结果表明:发电机稳态输出功率可达500 W,满足气体钻井随钻测量传输电磁波和微波传输的大功率需求。

行星齿轮传动动态均载特性研究进展

齿面载荷的分配状况,极大程度影响着行星传动系统功率分流这一特性的发挥。为研究行星齿轮传动系统中均载特性的有关问题,对目前该问题的研究现状进行了总结。阐述了与均载有关的基本问题,比较剖析了行星传动中均载特性的分析方法与计算模型,梳理了目前使用较多的均载方式和均载机构。通过整理分析发现,误差是影响载荷分布不均的根本原因,改善均载最有效的方法就是降低系统对误差的敏感程度;多级行星轮系动力学分析与非线性因素的影响是目前研究均载问题的重点方向;浮动零部件以及柔性化零部件仍是目前常用的均载方法。

舵机减速机构动力学仿真与振动特性研究

鱼雷在运输和实航时环境复杂,会遇到各种外界激振源的影响,使舵机减速机构的传动精度降低,从而影响整个系统的制导精度和可靠性。以三级行星齿轮和蜗轮蜗杆减速机构为研究对象,建立动力学虚拟仿真模型,采用有限元分析法对其进行模态分析,得出固有频率和振型;将随机载荷的功率谱密度函数作为输入进行随机振动分析,仿真结果表明,舵机减速机构的输入轴、一级太阳轮齿以及蜗轮蜗杆啮合处所受振动量级较大,设计时需重点关注。