直齿圆柱齿轮弯曲强度等几何分析

齿轮作为一种重要的机械零件,其设计与制造直接影响着机械设备的实际性能与工作质量.由于齿轮的工作寿命与齿轮的最大弯曲应力的六次方成反比,因此精准地计算齿轮齿根的弯曲强度,是延长其使用寿命的必要保证.为了更精准地实现齿轮的弯曲应力的求解计算,本文提出了基于等几何法的齿轮弯曲强度分析算法,实现了对平面齿轮结构力学性能的等几何...     

Static stress analysis of a composite bevel gear using a three-dimensional finite element method

The possibility of using composite materials for power transmission spur gear, from a static strength point of view, have been proved by the authors in their previous study. In this present work an attempt has been made to study the behaviour of composite bevel gear from a static load point of view using a three-dimensional finite element method. The performance of two composite material bevel gears are presented and compared with a carbon steel gear. From a static strength point of view a glass epoxy bevel gear is slightly closer to a carbon steel bevel gear than a boron/epoxy bevel gear; but from a displacement point of view glass/epoxy deviates from that of carbon steel much more than boron/epoxy, unlike the case of a composite spur gear, where boron/epoxy was better both from strength and displacement points of view. Hence from the results it is concluded that composite materials such as boron/epoxy can be very much thought of as a material for power transmission bevel gears.     

人字齿轮啮合刚度计算与齿面载荷分布研究

为了精确地进行人字齿轮的强度计算和动态特性分析,首先建立了渐开线真实齿廓的人字齿轮三维模型,提出了一种基于有限元方法和齿轮啮合原理的准确计算人字齿轮啮合刚度和齿面载荷分布的有效方法.方法利用有限元方法计算齿面柔度系数,考虑了齿轮的动态啮合过程.运用该方法计算了一对人字齿轮模型,最后分析了斜齿轮和人字齿轮啮合刚度的关系,得出了斜齿轮和人字齿轮啮合刚度近似相等的结论,为后续的动力学分析提供了准确的刚度激励.     

含间隙齿轮传动系统的非线性动力学特性的研究

含间隙齿轮传动系统存在着丰富的非线性动力学行为,建立了两自由度齿轮传动系统的动力学模型,首先利用数值方法分析了齿轮传动系统的分岔和混沌动力学行为,然后将非光滑的间隙函数用光滑函数拟合,通过对系统进行多尺度摄动分析和计算,得到间隙函数拟合后的齿轮传动系统的非线性动力学现象,并与无拟合非光滑系统的数值结果进行比较分析,为含间隙齿轮传动系统的研究奠定了基础.     

挡位离散型车辆经济性加速策略的伪谱法优化

加速过程中, 车辆的油耗与驾驶员的操作策略密切相关. 本文通过最优控制方法定量化地研究了挡位离散型车辆的经济性加速策略. 将加速策略的辨识构建为一个Bolza型最优控制问题(Optimal control problem, OCP), 设计了考虑加速距离影响的经济性定量评价指标. 该问题含有离散型控制变量, 隶属于混合整型最优控制问题, 且性能函数和状态方程呈现强非线性. 为高效地求解该问题, 结合变速器挡位切换规律, 将该整型问题转化为多段光滑问题的协同优化, 采用Legendre伪谱拼接法实现变速器挡位、换挡时机、发动机力矩的数值求解. 解析分析了经济性加速策略的形成机理, 总结了实用化的经济性加速度选择策略和挡位切换规律. 仿真验证了所求策略的节油潜力.     

两自由度齿轮传动系统全局动力学研究

齿侧间隙的存在,使齿轮传动系统存在着丰富的非线性动力学行为.考虑两自由度齿轮传动系统的动力学模型,利用数值方法分析系统的分岔和混沌动力学行为.通过简单胞映射方法对非线性齿轮系统进行全局分析,得到系统的吸引子,吸引域等全局特性.结果显示:随着激振频率的变化,系统存在多个周期解共存以及周期解与混沌运动共存现象.最后利用系统的相轨线图与庞加莱截面图进行对比分析,在不同的初值条件下,系统呈现出不同的周期运动或混沌运动.利用简单胞映射方法的数值计算结果可以实现在不良参数条件下,通过合理控制系统的初值条件而获得理想的系统响应.     

Two-stage on-board optimization of merging velocity planning with energy management for HEVs

This paper proposes a two-stage hierarchy control system with model predictive control (MPC) for connected parallel HEVs with available traffic information. In the first stage, a coordination of on-ramp merging problem using MPC is presented to optimize the merging point and trajectory for cooperative merging. After formulating the merging problem into a nonlinear optimization problem, a continuous/GMRES method is used to generate the real-time vehicle acceleration for two considered HEVs running on main road and merging road, respectively. The real-time acceleration action is used to calculate the torque demand for the dynamic system of the second stage. In the second stage, an energy management strategy (EMS) for powertrain control that optimizes the torque-split and gear ratio simultaneously is composed to improve fuel efficiency. The formulated nonlinear optimization problem is solved by sequential quadratic programming (SQP) method under the same receding horizon. The simulation results demonstrate that the vehicles can merge cooperatively and smoothly with a reasonable torque distribution and gear shift schedule.     

直齿行星齿轮动力学建模与分析研究

建立了直齿行星齿轮的动力学模型.其中,齿与齿之间的啮合非线性由弹簧-阻尼器-间隙-啮合误差环节模拟.提出了一种以行星轮转角为变量的时变啮合刚度与时变啮合误差表达形式,解决了变转速下行星齿轮动力学模型的描述和求解问题.通过对动力学模型进行求解,分别研究了转速、齿侧间隙、啮合误差和负载等重要参数对行星齿轮动力学特性的影响.     

大型矿车用减速机齿轮系统的疲劳分析

提出一种基于"放大因子"、采用二维平面单元模拟三维实体动态工况的计算疲劳的方法,对某矿车减速机齿轮系统进行疲劳分析,得到太阳轮、行星轮和扭力管在不同抗拉强度下的疲劳寿命.结果表明:太阳轮和扭力管最易发生疲劳破坏;齿轮寿命对抗拉强度的依赖性较敏感;得出的齿轮系统热处理后的抗拉强度建议值能为设计提供参考,且该方法能大大提高计算效率.     

Development Of Cvt Control System And Its Use For Fuel‐Efficient Operation Of Engine

Continuously variable transmission (CVT) provides an automobile with the ability to change the gear ratio continuously, which can then improve not only ride quality such as acceleration performance but also fuel‐efficiency. However, to take advantage of the ability, a control system that can precisely control the gear ratio is required. This paper proposes such a control system for a belt‐driven CVT system. For controller design, first the CVT system is modeled by analytical and experimental approaches. The resultant static and dynamic characteristics provide a nonlinear first‐order model with an uncertain time constant and time delay. The nonlinear steady‐state gain is adjusted to one by a gain‐scheduled pre‐compensator. Thereby the plant model becomes a linear first‐order lag system with a dead time. The next step is controller design using the plant model. To guarantee stability and control performance against the parameter variation and time delay, the μ‐synthesis, a robust control method, is employed for feedback control. In addition, a feedforward controller is incorporated into the feedback control system to obtain better output response. The feedforward controller is given by a combination of the inverse system of the plant and a reference model that gives desired output response. As a result, the control system becomes a two‐degree‐of‐freedom control system. To evaluate the performance of the control system and its effectiveness on the fuel‐efficiency, computer simulation and driving tests were conducted. The simulation and experiment results prove that the proposed control system can make the gear ratio track a reference output quickly and precisely in the presence of the uncertainties. The results also show that the control system improves fuel‐efficiency by changing the gear ratio so that the engine torque and its revolution speed can satisfy optimum‐efficiency operating condition.     

CAE技术在高分子材料齿轮箱设计中的应用

为解决机车齿轮箱裂纹和漏油等故障,设计全新的满足使用要求的高分子材料齿轮箱.借助模态和模流仿真技术,分析齿轮箱的动态结构和成型过程,重点研究齿轮箱固有特性、成型工艺性和翘曲变形等,找出设计结构强度薄弱部位、成型困难部位和变形严重影响的装配部位.结果可以为齿轮箱的改进设计提供参考.     

基于Matlab的电动汽车变速器结构优化

为满足某电动汽车整车设计中要求在有限的空间内布置变速器的需求,介绍电动汽车变速器的基本结构,建立电动汽车变速器齿轮组结构紧凑性的目标函数,在保证变速器零件强度等条件下．使变速器齿轮组和轴系的结构紧凑．运用Matlab的Optimum Toolbox对变速器结构进行优化设计,结果表明变速器的几何尺寸减小,其结构变得紧凑．     

机器视觉测量中透视投影误差分析控制与补偿

在机器视觉齿轮倒角的测量系统中,轮廓测量是实现齿轮中心定位的关键因素。传统镜头成像时,由于透视投影特性,会引起齿轮轮廓圆直径的测量误差,进而影响轮廓圆的定位精度。针对此建立了透视投影误差的非线性模型,并对不同厚度齿轮轮廓圆直径的测量进行了误差分析与补偿。实验结果表明,该方法具有一定的实用价值,满足了齿轮轮廓圆测量的要求。     

Optimization of airplane wing structures under landing loads

A methodology is presented for the optimum design of aircraft wing structures subjected to landing loads. The stresses developed in the wing during landing are computed by considering the interaction between the landing gear and the flexible airplane structure. The landing gear is assumed to have nonlinear characteristics typical of conventional gears, namely, velocity squared damping, polytropic air-compression springing and exponential tire force-deflection characteristics. The coupled nonlinear differential equations of motion that arise in the landing analysis are solved by using a step-by-step numerical integration technique. In order to find the behavior of the wing structure under landing loads and also to obtain a physical insight into the nature of the optimum solution, the design of the typical section (symmetric double-wedge airfoil) is studied by using a graphical procedure. Then a more realistic wing optimization problem is formulated as a constrained nonlinear programming problem based on finite element modeling. The optimum solutions are found by using the interior penalty function method. A sensitivity analysis is conducted to find the effect of changes in design variables about the optimum point on the various response parameters on the wing structure.     

随机齿侧间隙下行星齿轮系统的修形方法研究

建立一个包含随机齿侧间隙、摩擦、时变啮合刚度等影响齿轮振动因素的行星齿轮系统动力学模型.使用非线性动力学方法对系统进行求解,并分析激励频率对系统的影响.提出修形的主动降噪措施对系统进行改进,重新计算行星齿轮系统的动力学方程.求解并分析激励频率对改进之后系统的影响,并和原始系统得到的结果对比,可以看出修形对于齿轮系统的减振是有效的.     

精确模型下汽车变速器齿轮的有限元分析

采用CAXA与SolidWorks软件相结合实现变速器齿轮的精确建模,有效提高了齿轮的设计效率。本文用AN-SYS软件对齿轮进行应力分析,与传统方法相比,有限元计算结果更精确,为齿轮的强度设计提供更可靠的依据。     

二级减速器齿轮传动性能分析和修形优化设计

为改善齿轮传动性能,分析某二级减速器齿轮的静强度、载荷分布和传递误差,发现其低速齿轮副的载荷分布偏载和传递误差相对较大。选取遗传算法V2,结合Romax Designer,对比分析几种齿廓修形与齿向修形的组合方式,其中最好的修形方式是将齿向鼓形修形和齿向斜度修形相结合。采取该方式对齿轮副进行优化,优化后低速齿轮副的传递误差比修形前减小92.41%,齿轮载荷分布得到改善,低速齿轮副的单位载荷降低,齿轮副的可靠性和使用寿命均提高。齿轮修形优化后的减速器传动更平稳,振动和噪声减小。     

基于双树复小波变换—最大熵谱估计和参数优化概率神经网络的齿轮箱故障诊断研究

齿轮振动信号具有非平稳性和非线性的特点。为了准确提取其故障特征并进行故障诊断,提出一种基于双树复小波变换(DTCWT)-最大熵谱估计(MESE)和惯性权重线性递减粒子群优化(LDWPSO)算法-参数优化概率神经网络(PNN)的齿轮故障诊断方法。首先,利用DTCWT把状态已知的齿轮振动信号分解为不同频带的模态分量。其次,采用MESE得到每个分量的最小偏差频谱估计,计算出不同频段的能量熵作为故障特征矩阵。然后利用LDWPSO算法寻找出最优神经网络参数——平滑因子。最后,将故障特征矩阵输入优化后的PNN模型,建立起故障特征和齿轮运行状况之间的数值化映射关系,进而完成齿轮故障诊断模型。经试验数据分析表明,采用提出的DTCWT处理齿轮的振动信号,并引入MESE处理关键分量,可以提取稳定的信号特征并降低噪声干扰。另外,相比于传统的PNN,基于改进的PNN的齿轮故障状态的数值化判别具有更高的诊断精度和稳定性。     

Research on Design Method of Non-Circular Gear Pair with Double Generating Angles

In order to enhance the bearing capacity of non-circular gear pair, the non-circular gear pair with double generating angles is proposed based on the design idea of unsymmetrical gear with double pressure angles. The tooth profile is designed by generating cutting theory, the pure rolling mathematic model that the center line of unsymmetrical rack roll along non-circular pitch curve is built, the digital model of non-circular gear with double generating angles is created through the second development method of CAD software, and then the drive characteristic and tooth strength are analyzed. The results show that the design method for double generating angles non-circular gear proposed in this paper is feasible, which is significant to improve the bearing capacity of non-circular gear pair.     

联动油缸机构的遗传优化设计

为使喷浆机器人纵向进给机构与巷道中线始终保持平行 ,采用了一组油缸联动机构 ,并用改进的遗传算法对其进行了优化设计。改进后的遗传算法采用浮点数编码 ,用惩罚函数处理等式和不等式的约束问题 ,使之适用于所有的非线性约束优化问题