Effects of gear modifications on the dynamic characteristics of wind turbine gearbox considering elastic support of the gearbox

The reliability and service life of wind turbines are directly influenced by the dynamic performance of the gearbox under the time-varying wind loads. The control of vibration behavior is essential for the achievement of a 20-year service life. We developed a rigid-flexible coupled dynamic model for a wind turbine gearbox. The planet carrier, the housing, and the bedplate are modelled as flexibilities while other components are assumed as rigid bodies. The actual three points elastic supporting are considered and a strip based mesh model is used to represent the engagement of the gear pairs. The effects of gear tooth modifications on the dynamics were investigated. Finally, we conducted a dynamic test for the wind turbine gearbox in the wind field. Results showed that the contact characteristics of gear pairs were improved significantly; the peak-to-peak value of transmission error of each gear pair was reduced; the amplitudes of the vibration acceleration and the structural noise of the wind turbine gearbox were lowered after suitable tooth modification.     

大兆瓦级风电齿轮箱耦合动态特性及结构噪声分析

风电齿轮箱是风电机组的重要组成部分,其动态性能的好坏直接影响整个机组的性能。建立了具有两级行星加一级平行轴齿轮传动的大兆瓦级风电齿轮箱齿轮-传动轴-轴承-箱体系统耦合非线性动力学有限元模型,采用Lanczos法对齿轮箱系统进行耦合模态分析。在综合考虑直斜齿轮时变啮合刚度、齿轮误差及齿轮啮合冲击等内部激励因素综合作用影响下,运用直接积分法对整个风电齿轮箱系统进行了动态响应求解,从而获得齿轮箱各点的振动位移、速度及加速度动态评价指标,并且对系统结构噪声进行了分析。研究结果可为大兆瓦级风电齿轮箱的动态性能优化提供参考。     

随机风作用下风力发电机齿轮传动系统动载荷计算及统计分析

针对风力发电机齿轮传动系统在随机风作用下失效率高的问题,在模拟真实风速的基础上,建立考虑外部随机风载及内部齿轮时变啮合刚度、轴承时变刚度及综合传递误差等激励因素的风力发电机齿轮传动系统齿轮-轴承耦合动力学模型,通过对动力学模型进行仿真计算,得到各齿轮副的动态啮合力和各支承轴承的动态接触力。结合有限单元法和赫兹接触理论,得到关键零部件的应力时间历程,采用雨流计数法对应力时间历程进行统计分析,得到传动系统各关键零部件承受载荷的应力谱及概率分布函数。研究结果为风力发电机齿轮传动系统的动态可靠性分析和疲劳寿命预测奠定基础。     

风电齿轮齿根弯曲应力及裂纹特性分析

以风电齿轮为例,利用有限元分析软件ABAQUS,建立了太阳轮简化力学模型,并进行了齿根弯曲应力的分析计算。分析结果与传统计算方法得出的结果基本一致,从而验证了简化模型的正确性。在此基础上,研究了齿轮齿根裂纹特性,分析了初始裂纹长度和外加载荷对应力强度因子(SIF)的影响。结果表明,随着初始裂纹长度的增加,应力强度因子也随之增加,并且应力强度因子与载荷等比例增加。在初始裂纹长度和载荷相同的情况下,应力强度因子KⅠ远大于KⅡ和KⅢ,即在弯曲应力作用下张开型裂纹为风电齿轮轮齿折断失效的主要原因。     

基于动力学的风电增速箱多级齿轮传动系统可靠性评估

针对风力发电机齿轮传动系统在变风速工况下失效率高的问题,在模拟真实风速的基础上,建立了考虑外部随机风载及内部轮齿时变啮合刚度、轴承时变刚度、综合传递误差等激励因素的风力发电机齿轮传动系统齿轮-轴承耦合动力学模型,通过对动力学模型进行仿真计算,得到了各齿轮副的动态啮合力和各支承轴承的动态接触力,并求得齿轮的使用系数、齿轮和轴承的载荷系数。在此基础上,建立了基于动力学的风电齿轮传动系统可靠性评估模型,并求得了各零件及传动系统的可靠度,较全面地评价了随机风载作用下风力发电机齿轮传动系统的可靠性,为风力发电机齿轮传动系统可靠性设计和动态优化奠定了基础。     

考虑强度退化和失效相关性的风电齿轮传动系统动态可靠性分析

针对随机风作用下风力发电机齿轮传动系统失效率高的问题,研究了随机风引起的风力发电机传动系统外部风载荷以及内部由齿轮、轴承刚度及综合啮合误差等引起的内部动载荷激励,基于集中质量法建立了风电齿轮传动系统齿轮-轴承耦合动力学模型。在对模型进行仿真求解的基础上,分别求得了传动系统中各齿轮和轴承的动态接触应力-时间历程。将载荷作用过程视为随机过程,推导出随机载荷作用下的等效载荷累计分布函数,从系统层面上建立了基于应力-强度干涉理论的风力发电机齿轮传动系统动态时变可靠性模型,模型考虑了零件的失效相关性和强度退化因素,研究了失效相关性和强度退化对风电齿轮传动系统可靠度和失效率的影响规律,为风力发电机齿轮传动系统动态设计和可靠性优化设计奠定了基础。     

变风速运行控制下风电传动系统的动态特性

基于齿轮系统动力学的方法对风电传动系统进行研究。运用基于自回归模型的线性滤波法(Auto-regressive,AR)建立的风速模型对实际风场的随机风速进行模拟;根据风力发电机在实际情况中的运行控制策略获得风力发电机齿轮传动系统的时变输入转矩激励;综合考虑风力发电机齿轮传动系统中各个齿轮副的时变啮合刚度、各个滚动轴承的刚度、各个轮齿综合啮合误差等内部激励,采用集中参数质量法建立风力发电机齿轮传动系统的耦合动力学模型;在此基础上建立风力发电机齿轮传动系统的动力学微分方程并进行仿真计算,分别求解风力发电机齿轮传动系统的固有频率、振动响应、动态啮合力和滚动轴承动态轴承力。研究结果为风力发电机传动系统的动态性能优化设计和可靠性设计奠定了基础。     

风电行星齿轮系统变载荷激励动力学模型及其响应特性

针对风电行星齿轮系统变载变速的运行特点,通过分析系统构件为刚体和弹性体时的受力情况,应用运动合成原理,提出了变载荷激励下行星齿轮系统动力学模型的建立方法,并推导出系统的运动微分方程。在此基础上,分析了行星齿轮系统的内外部激励因素及其对系统动载荷和动载系数的影响机理。计算并分析了某MW级风电行星齿轮系统的动态响应,结果表明：系统的时变啮合刚度和时变轴承刚度主要影响响应频率的数值大小和系统的振动能量;外部变载荷使响应频率中存在明显的低频成分,并影响各阶振动间的能量分配;齿轮啮合力的动载系数主要受到外部变载荷的影响,而轴承力的动载系数同时受到系统内部激励和外部激励的影响。研究结果为风电齿轮箱的疲劳寿命分析和动态优化设计奠定了基础。     

太重Ⅲ型风力发电增速齿轮箱有限元分析

风电增速齿轮箱在兆瓦级风力发电机中属易过载和损坏率较高的部件,对其性能进行分析,预测其性能并进行优化是十分必要的.本文中利用ANSYS软件对太重Ⅲ型两级行星一级平行轴1.5MW风力发电增速齿轮箱进行有限元分析,对太重Ⅲ型风力发电增速齿轮箱各级齿轮强度进行校核,得到了各级齿轮副的齿廓和齿向修形数据;对行星轮系载荷均载特性、主箱体组件、行星架、花键联接等进行分析,得到了风力发电增速齿轮箱各级零部件强度和刚度等相关数据,为风电增速齿轮箱的可靠性评估及优化设计奠定基础.     

Application of similarity theory to load capacity of gearboxes

This study suggests the theoretical methodology to construct a small-sized similarity model having the same load capacity as a large gearbox. The prototype gearbox was a 2-MW wind turbine gearbox consisting of two planetary gear stages and one parallel shaft gear stage, and the specifications of its 1/4 scale similarity model were determined by applying similarity theory. The constructed similarity model was validated by comparing load capacity parameters with those of the prototype gearbox using analysis tool. The validation results showed that the nominal tooth root and contact stresses of the similarity model and prototype gearbox were identical, whereas the tooth root and contact stresses satisfied the similarity condition within 2% difference. Furthermore, most factors that influenced the tooth root and pitting stress limits were identical. Thus, information related to load capacity, one of the major design evaluation criteria for gears, of large-size gearbox can be replicated by its similarity model. Although this is a theoretical methodology and still has many difficulties to apply to practical situations, these results have opened up the possibility of applying similarity theory to load capacity of gearboxes. Because the load capacity is the primary cause of commercial gearbox failure, this result also shows the possibility of life similarity in the gearbox application, although some further study is needed.     

Optimization of helix angle for helical gear system

A method is presented to optimize the helix angle of a helical gear from the viewpoint of the transmission error, which is the deflection of the teeth due to the transmitted load. The deflection of the gear teeth is calculated by using the bending and shear influence function, which is formulated from the common formula for deflection obtained from FEM, and the contact influence function based on Hertzian contact theory. Tooth contact analysis is performed to calculate the contact lines of the helical gear, where the deflection of the tooth is measured. A numerical example is presented to explain a method to optimize the helix angle of a helical gear system. The relation between the contact ratio and transmission error is investigated through calculations of the variation in the transmission error with the helix angle. This paper was recommended for publication in revised form by Associate Editor Hong Hee Yoo     

Dynamic characteristics analysis and experimental research on a new type planetary gear apparatus with small tooth number difference

Aimed at an internal mesh planetary gear with small tooth number difference (PGSTD) reducer, this paper proposes dynamic characteristics analysis. First, static finite element (FE) analysis is performed to check the structural strength with the stress distribution in the gear teeth. Second, by means of the dynamic contact FE method, the internal dynamic excitations of teeth mesh are obtained, including mesh stiffness excitation, transmission error excitation and mesh impact excitation. According to the established model for dynamic FE modal analysis, the natural frequencies and mode shapes of the planetary gear apparatus (PGA) are calculated, and its structural dynamic response and acceleration noise are researched with the comprehensive consideration of internal and external excitations. Finally, the noise and vibration testing on the PGA is carried out by utilizing the vibration test equipment. The results confirm that the predicted values are consistent with the experimental results.     

风电齿轮箱动态响应分析及实验测量

运用达朗伯原理建立了风电齿轮箱传动系统的纯扭转集中参数动力学模型,箱体模型采用有限元法建立,通过作用在箱体支撑孔上的轴承力建立了齿轮箱动力学模型.采用龙格-库塔法求解了传动系统的轮齿动态啮合力,计算了箱体在动态啮合力作用下的振动响应.同时对齿轮箱进行了实验测量,并把测量得到的齿轮箱振动响应数据和模型计算的结果进行了对比,验证了模型的正确性.通过这些分析,为风电齿轮箱动态设计中减少振动噪声、提高承载能力与可靠性奠定了基础.     

功率分流技术在风电齿轮箱中的应用

从功率分流的原理、功率分配、实例应用等方面对差动行星齿轮传动中的功率分流技术进行了探讨,对风电齿轮箱的设计有一定的指导和帮助。     

随机风载作用下风力发电机齿轮传动系统动态可靠性分析

运用最小二乘支持向量机(Sparse least squares support vector machines,SLS-SVM)机器学习方法建立风场随机风速模型,根据随机风速模型和空气动力学理论得到随机风引起的系统外部载荷激励,建立考虑齿轮时变啮合刚度和滚动轴承时变刚度的风力发电机行星齿轮传动系统齿轮—轴承耦合动力学模型,并对动力学模型进行仿真计算,分别得到各齿轮副的动态啮合力和滚动轴承动态接触力。以此为基础,将载荷作用过程视为随机过程,推导出随机载荷作用下的等效载荷累计分布函数。根据应力—强度干涉理论建立风力发电机齿轮传动系统各齿轮和轴承的动态可靠性模型,利用二阶矩和摄动方法求出各齿轮、轴承的动态可靠性指标,并计算出动态可靠度,研究各齿轮、轴承和传动系统的动态可靠度随时间的变化规律,为风力发电机齿轮传动系统动态可靠性设计奠定了基础。     

风机行星齿轮系统齿轮裂纹故障诊断

针对风力发电机实际行星齿轮系统,由于幅值及相位调制现象(各种制造误差不可避免等原因所导致)带来的故障诊断难题,搭建了含各种制造误差的动力学模型。模型考虑了出现裂纹故障以后,故障对时变啮合刚度以及传递误差的影响,通过数值求解,对比行星轮、太阳轮以及齿圈出现故障后与正常齿轮系统的包络谱结构特性,总结了故障特征频率。在风力发电机齿轮箱实验台上进行裂纹故障试验验证,结果表明所总结的故障特征频率可以作为风力发电机裂纹故障诊断及定位的依据。     

Effects of dynamics in gear tooth contact

Investigation of surface contact effects in gears at speed is complificated by dynamic effects. To find true loadings on the contacts in a gear drive it is necessary to measure transmission error and then model the gearbox dynamics. This allows prediction of tooth loads and contact times and gives the bearing vibration forces which excite the gearcase and its supports to radiate noise     

基于光谱分析技术的风机齿轮箱系统维护策略研究

风机齿轮箱中轴承和齿面的磨损是齿轮箱最常见的累积故障,当齿轮箱中的系统部件的累积磨损达到一定量时就会严重威胁到整个风电机组的正常运行,甚至大大降低其使用寿命。基于光谱分析技术对风机齿轮箱进行维护策略的研究,依据设备的不同累积磨损情况建立3种不同维护方式下的齿轮箱的维护策略,基于概率模型建立齿轮箱系统的时间成本模型,以最少维护时间成本为优化目标,利用蒙泰卡罗方法模拟设备随机衰退过程对巡检周期进行仿真,仿真结果表明提出的方案可行且有效。     

474汽车变速器倒档锥度环的结构改进

474汽车变速器五倒档同步器在挂倒档时，倒档锥度环和倒档止动环只起着同样的作用就是定位，防止五档同步器齿套、五档同步器滑块向后滑出，所以同步器齿环就没有发挥其应有的作用。所以将两者合二为一，材料则采用强度和耐磨性能都比较高的合金钢20CrMo。为了降低变速器的成本，在原来的基础上倒档锥度环和倒档止动环合并。采取单件试生产、台架实验、道路实验相结合的方法，证明此结构可行。能满足变速器总成的要求。     

水平轴风力发电机组偏航轴承的建模及有限元法分析

偏航轴承是决定风电机组运行性能的关键部件之一.首先应用三维建模软件Pro/E建立了外圈带齿的偏航轴承的模型,而后在有限元分析软件ANSYS中,对静载荷作用下的轴承外圈轮齿进行分析.分析结果证明了轮齿折断是齿轮传动过程中失效的主要形式之一,也说明了Pro/E软件和ANSYS软件的结合使用能有效地分析机械系统在载荷作用下的性能.