基于动力学仿真的行星轮系损伤检测方法

为了解决行星轮系的损伤检测问题,提出了基于动力学仿真的损伤检测方法。针对2K-H行星轮系,首先建立了健康与损伤状态的动力学模型,在分析模型仿真信号的基础上,提取了基于残差信号频谱边带的特征,然后采用仿真信号和试验数据对该特征进行了验证。验证结果表明,对于太阳轮缺齿损伤,该特征不仅具有理想的检测效果,而且具有较强的抗干扰能力。     

Fault identification method for planetary gear based on DT-CWT threshold denoising and LE

Planetary gear is widely used in large-scale complex mechanical systems. However, because of the particularity of planetary gear transmission, serious wear and fatigue crack failures often occur in the sun gear, planet gears, and inner gear ring. In addition, every type of fault will experience different degradation processes. Improving the operation reliability of mechanical equipment through fault diagnosis of planetary gears and monitoring their degradation process is beneficial. This paper proposes a planetary gear fault identification method based on Dual-tree Complex wavelet transform (DT-CWT) threshold denoising and Laplacian eigenmaps (LE). The noise reduction processing of the original signal is achieved by the DT-CWT threshold denoising method, which takes full advantage of DT-CWT and is combined with the wavelet threshold of rigrsure principle. The original high-dimensional feature set, including the time domain features, frequency domain features, permutation entropy, and fractal box dimension of the denoised signal, is constructed from multi-angles. To solve the problems of excessively large feature dimension and the existence of redundant information, the LE algorithm is used to reduce the dimension of the original high-dimensional feature set, and the low-dimensional sensitive features are obtained. Through the above method, the effective identification of different fault states and different degradation states of the planetary gear are achieved.     

某型直升机行星齿轮机构弹流润滑研究

分析了某型直升机主减速器行星齿轮机构弹流润滑工况,研究了该齿轮系弹性润滑最薄弱啮合部位,计算得出了行星齿轮传动机构中齿宽、齿轮模数和压力角等齿轮参数对弹性润滑油膜厚度的影响,提出了改进直升机主减速器行星齿轮机械润滑状态的新思路和具体改进方案,结果证明增加行星轮和太阳轮的齿宽、模数和齿轮啮合角及提高润滑油粘度和粘压系数,可有效地改进齿轮润滑,减少齿面失效,提高行星齿轮传动机构的可靠性。     

行星轮系动力学新模型及其故障响应特性研究

行星轮系中零部件多、结构复杂,建模难度大。行星轮既自转又公转,导致啮合点到固定在箱体上的传感器之间的距离时刻变化,从而产生振动传递路径时变效应,增加了振动响应的复杂性。现有的动力学模型大多针对正常情况下的行星轮系进行建模,而且未考虑振动传递路径时变效应对振动响应的影响。针对以上不足,推导了行星轮系正常、裂纹及剥落三种情况下的时变啮合刚度算法,考虑振动传递路径时变效应的影响,建立了相应的动力学模型,求解得到行星轮系正常、裂纹及剥落时的动态响应,并分析了它们的频谱特性。搭建了行星齿轮箱试验台以获取振动响应信号,与模型响应信号进行了对比分析,结果验证了动力学模型的准确性,为行星轮系的健康监测提供了理论依据。     

行星线齿变速器基于装配误差的传动精度分析

针对一种以线齿轮为核心传动元件的行星线齿变速器,研究了装配误差对其传动精度的影响。介绍了该行星线齿变速器的结构组成及不同传动方案的特点,建立了轮系空间啮合坐标系,以及啮合时线齿行星轮、线齿太阳轮以及外线齿圈的参变量之间的定量关系;分析了外线齿圈与线齿行星轮之间以及线齿行星轮与线齿太阳轮之间的角度误差和位移误差的产生原因,并采用齿面接触分析方法(TCA),对行星线齿变速器的装配误差模型进行了数值分析。结果表明,在行星线齿变速器的装配中,绕水平轴旋转的角度误差、外线齿圈纵截面内的位移误差以及线齿行星轮横截面内的位移误差,对传动精度有较大影响。研究对该行星线齿变速器的设计和装配具有指导意义。     

Study on planetary gear fault diagnosis based on entropy feature fusion of ensemble empirical mode decomposition

Because planetary gear is characterized by its small size, light weight and large transmission ratio, it is widely used in large-scale, low-speed and heavy-duty mechanical systems. Therefore, the fault diagnosis of planetary gear is a key to ensure the safe and reliable operation of such mechanical equipment. A fault diagnosis method of planetary gear based on the entropy feature fusion of ensemble empirical mode decomposition (EEMD) is proposed. The intrinsic mode functions (IMFs) with small modal aliasing are obtained by EEMD, and the original feature set is composed of various entropy features of each IMF. To address the insensitive features in the original feature set and the excessive feature dimension, kernel principal component analysis (KPCA) is used to process the original feature set. Kernel principal component extraction and feature dimension reduction are performed. The fault diagnosis of planetary gear is eventually realized by applying the extracted kernel principal components and learning vector quantization (LVQ) neural network. The experiments under different operation conditions are carried out, and the experimental results indicate that the proposed method is capable of extracting the sensitive features and recognizing the fault statuses. The overall recognition rate reaches to 96% when the motor output frequency is 45 Hz and the load is 13.5 N m, and the fault recognition rates of the normal gear, the gear with one missing tooth and the broken gear can reach to 100%. The recognition rates of different fault gears under other operation conditions also can achieve better results. Thus, the proposed method is effective for the diagnosis of planetary gear faults.     

考虑随机制造误差的风力机行星齿轮系统动力学特性

为研究综合传递误差的随机波动对风力发电机齿轮传动系统动力学特性的影响,考虑齿轮时变啮合刚度、综合传递误差等因素,建立风力发电机行星齿轮传动系统纯扭转动力学模型。以随机风速引起的齿轮系统转矩波动作为行星齿轮系统的外部激励,对某1.5 MW风力发电机行星齿轮传动系统的动力学特性进行仿真分析,得到系统各响应量时域内的统计特征和齿轮副间的动态啮合力统计特征。分析表明：行星架、行星轮和太阳轮在扭转方向上的振动特性与外部载荷相关,其振动位移与外部载荷波动有相似变化的趋势;综合传递误差随机分量的离散程度对行星齿轮系统的动态特性和齿轮副间的动态啮合力有较大影响。随着综合传递误差随机分量离散程度的增加,行星架、太阳轮和行星轮在扭转方向上的振动幅值明显增加;综合传递误差随机分量的随机性使齿轮副间动态啮合力产生随机波动,随机分量离散程度越大,动态啮合力波动越明显;当随机分量的离散程度达到某一值时,齿轮啮合过程发生脱离,引发啮合冲击。     

Vibration signal modeling of a planetary gear set with transmission path effect analysis

For a planetary gear set, the transducer-perceived vibration signal contains vibration information from multiple sources including the sun gear, planet gears, and the ring gear. All these vibration sources are subject to corresponding transmission path effects. In this paper, a comprehensive vibration signal model for a planetary gear set is proposed considering all the vibration sources and transmission path effects. Vibration sources were generated with a nonlinear two-dimensional lumped-parameter dynamic model. Transmission path effects are modeled as two parts: the part inside the gearbox to the casing and the other part along the casing to the transducer position. Given the gear sizes, the transmission path effect modeling parameters are estimated. Then the influences of different transmission paths on resultant vibration signals are analyzed. Some vibration characteristics are revealed for one healthy planetary gear set. These vibration characteristics are validated with lab experimental data in both time domain and frequency domain.     

Crack Fault Classification for Planetary Gearbox Based on Feature Selection Technique and K-means Clustering Method

During the condition monitoring of a planetary gearbox, features are extracted from raw data for a fault diagnosis.However, different features have different sensitivity for identifying different fault types, and thus, the selection of a sensitive feature subset from an entire feature set and retaining as much of the class discriminatory information as possible has a directly effect on the accuracy of the classification results. In this paper, an improved hybrid feature selection technique(IHFST) that combines a distance evaluation technique(DET), Pearson's correlation analysis, and an ad hoc technique is proposed. In IHFST, a temporary feature subset without irrelevant features is first selected according to the distance evaluation criterion of DET, and the Pearson's correlation analysis and ad hoc technique are then employed to find and remove redundant features in the temporary feature subset, respectively, and hence,a sensitive feature subset without irrelevant or redundant features is selected from the entire feature set. Further, the k-means clustering method is applied to classify the different kinds of health conditions. The effectiveness of the proposed method was validated through several experiments carried out on a planetary gearbox with incipient cracks seeded in the tooth root of the sun gear, planet gear, and ring gear. The results show that the proposed method can successfully distinguish the different health conditions of a planetary gearbox, and achieves a better classification performance than other methods. This study proposes a sensitive feature subset selection method that achieves an obvious improvement in terms of the accuracy of the fault classification.     

复式直齿行星排行星轮轴向力研究

在车辆的传动系统中,复式直齿行星排的行星轮与行星架之间存在轴向作用力,导致止推垫圈磨损严重。分析了复式直齿行星排长行星轮轴向力的产生机理,建立了行星轮滚针轴承负荷分布与轴向力计算模型。通过仿真分析与试验研究,指出了影响行星轮轴向力的主要因素及其对轴向力的影响规律。为复式直齿行星排行星轮轴向力的研究提供了分析方法,为复式行星排的设计改进提供了依据。     

基于EEMD的行星齿轮箱齿轮裂纹损伤定位

针对行星齿轮式变速箱的齿轮裂纹损伤难以提取特征频率和定位的问题,提出基于总体平均经验模式分解(ensemble empirical mode decomposition,简称EEMD)的齿轮局部损伤频率解调分析方法。该方法在建立的齿轮局部损伤振动信号模型的基础上,分别对太阳轮、齿圈、行星轮的裂纹损伤信号进行EEMD分解和频率解调分析,通过频谱图提取齿轮的局部损伤特征频率,从而识别变速箱中裂纹损伤齿轮的位置。综合仿真分析和试验结果表明,基于EEMD的齿轮局部损伤频率解调分析方法可以有效地提取太阳轮、齿圈和行星轮的裂纹损伤特征频率,实现行星齿轮式变速箱中齿轮裂纹损伤的定位。     

基于包络加窗同步平均的行星齿轮箱特征提取

行星齿轮箱由于行星轮通过效应、太阳轮与行星架的旋转及时变工况,导致其振动响应存在时变传递路径及非平稳性等特点,且传统的同步平均将不能直接应用于行星齿轮箱。笔者在国外加窗同步平均的基础上提出一种能有效克服时变传递路径及非平稳性的基于包络信号角域加窗同步平均的行星齿轮箱故障特征提取方法。首先,基于谱峭度提取出行星齿轮箱振动信号的包络信号;其次,再利用计算阶比跟踪技术对包络信号进行等角度重采样,行星架每旋转一圈,选择合适的窗函数对角域信号进行多齿宽加窗截取;最后,验证齿轮啮合齿序特征,根据重排齿序对加窗信号进行重构振动分离信号,对振动分离信号进行角域同步平均,提取行星齿轮箱故障特征。行星齿轮箱故障实测信号分析表明,该方法能有效提取行星齿轮箱故障特征。     

Model-based analysis and fault diagnosis of a compound planetary gear set with damaged sun gear

The vibration properties of compound planetary gears are more complicated than that of simple ones. This paper aims to investigate the fault properties of a compound planetary gear set in chipped sun gear conditions using model-based method. A three-dimensional lumped-parameter nonlinear dynamic model for the compound planetary gear set is established. This model considers the time-varying mesh stiffness (TVMS), the mesh phase relations, and gear chipping defects. The analytical equations are derived to quantify the TVMS reduction induced by the chipped gear based on the improved potential energy method. Further, the simulations are performed to demonstrate the fault features of sun gears with single or multiple chipped teeth in different gear stages. Moreover, the theoretical derivations are validated through the experimental signals analysis.     

行星齿轮变速传动的弹流润滑研究

基于弹性流体动力润滑理论,针对行星齿轮变速器内齿轮主动和太阳轮主动的2种工况,分别求出行星齿轮与太阳轮啮合以及与内齿轮啮合时,沿啮合线在啮合点的最小油膜厚度。结果表明:齿轮在节点啮合的润滑情况可以体现齿轮的润滑状况;太阳轮主动的工况,行星轮与内齿轮啮合的润滑条件最差;提高润滑油的黏度可以增加齿轮润滑油膜厚度;增加齿轮压力角的方法提高齿轮油膜厚度的效果明显;提高齿轮啮合的油膜厚度对改善齿轮的润滑状态,降低齿轮的生产成本,具有实际使用价值。     

基于模态叠加法的大型立式行星传动齿轮箱动力学分析及测试

根据某大型立式行星传动齿轮箱的结构和动态性能特点,建立了其直齿行星传动的平移-扭转耦合集中参数动力学模型,基于模态叠加法采用ADAMS动力学分析软件对齿轮箱的高速轴、低速轴、行星轮和太阳轮等构件进行了动力学特性分析,得到了整个传动系统的频响函数和模态频率。通过理论分析与现场测试结果进行对比,分析了该行星传动系统固有特性对齿轮箱产生的振动及噪声的影响。     

A study on load-sharing structure of multi-stage planetary transmission system

Unequal load distribution is a crucial factor in decreasing bearing capacity and stability of the planetary transmission system. In this paper, a dynamical model of two-stage helical planetary gear transmission system is established based on lumped-parameter method and Lagrange general function. Nonlinearity of gear tooth backlash and error is taken into account. Four load-sharing structures are proposed to study the load-sharing performance. A method to calculate dynamic sensitivity of load-sharing coefficient to errors is presented that can provide a reference to component precision determination in order to make planetary system have a better load distribution. Finally, a numerical method of load-sharing performance is validated by a test. These results provide fundamental basis for multi-stage planetary gear transmission system design.     

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。     

2K-V型摆线针轮减速器的动态回转传动误差分析

利用Pro/E创建参数化实体模型,导入ADAMS建立2K-V型摆线针轮减速器的虚拟样机.通过多刚体动力学仿真分析,获得转角误差曲线,并对比分析摆线轮修形造成的径向间隙等因素对传动精度的影响情况.为深入研究精密齿轮传动系统的动态传动精度,探索精密齿轮传动系统传动精度主动控制的方法和新传动结构设计提供了有效方法.     

Dynamic characteristics of a planetary gear system based on contact status of the tooth surface

Studies on the planetary gear have attracted considerable attention because of its advantages, such as compactness, large torque-to-weight ratio, vibrations, and high efficiency, which have resulted in its wide applications in industry, wind turbine, national defense, and aerospace fields. We have established a novel dynamic model of the planetary gear transmission by using Newton’s theory, in which some key factors such as time-variant meshing stiffness, phase relationships, and tooth contact characteristics are considered. The influences of gear axial tipping, operating conditions, and the meshing phase on the contact characteristics and the dynamic characteristics were researched systematically. It was found that the contact area of the tooth surface was moved due to the axial gear tipping, which obviously affected the meshing stiffness. With the increase in the inclination angle of the sun gear, the meshing stiffness decreases, which produces an evident influence on the high natural frequency in the planetary transmission system. In terms of the dynamic characteristics of the system, the component of rotating frequency appeared in the dynamic meshing force of the sun gear and the planetary gear. Moreover, the floating track of the center wheel varied significantly and exhibited an oval distribution as the inclination angle of the sun gear changed. When the inclination angle of the sun gear increased, the rotating frequency component increased significantly, but the other meshing frequency components remained unchanged; meanwhile, the deformation of the floating track also increased. If the inclination angle of the sun gear changes, the vibration state of the system and the collision impact could become more serious, and the lifetime of the planetary transmission system will reduce. Furthermore, when the load was increased, we found that the gear-tooth contact zone transformed from line contact to surface contact, the meshing stiffness increased, the effect of high natural frequency on the planetary transmission system became more evident, but its low-order natural frequency remained stable. With regard to the dynamic characteristics of the system, the components of the major frequency at the external gearing remained unchanged, but the rotation frequency of the sun gear and the meshing frequency amplitude increased linearly with the increase in load. In conclusion, the variation in the meshing stiffness of the planetary gear system had minor impact on the low-order natural frequency, but had a significant impact on the high natural frequency of the planetary transmission system due to the phase variation of the gear.     

不同误差下风电齿轮箱均载与太阳轮轨迹关系研究

建立风电齿轮箱行星传动系统静力学模型,对比理论模型下的均载与实验下的均载,确定理论模型的正确性。将太阳轮、行星轮、内齿圈和行星架等构件的误差分为两类误差,以不同误差构件数量为基础,分别分析在两类误差作用下的均载与太阳轮轨迹中心方位角,并与综合误差作用下的均载与太阳轮轨迹中心方位角进行对比。建立了两类误差下的均载、综合误差下的均载与太阳轮轨迹中心方位角之间的关系,发现了太阳轮轨迹中心变化的平行四边形法则。此误差对行星传动系统均载的影响提供了新的研究思路。