Gear Transmission Research Articles

Nonlinear Dynamic Modeling and Dynamic Characteristics Analysis of a Coaxial Reverse Closed Differential Herringbone Gear Transmission System Considering Floating Backlash

Nonlinear Dynamic Modeling and Dynamic Characteristics Analysis of a Coaxial Reverse Closed Differential Herringbone Gear Transmission System Considering Floating Backlash

Configuration synthesis and screening method for magnetic gear two-speed transmission for electric vehicles

Magnetic field modulated gears have contactless, lubrication-free and highly flexible transmission characteristics, which provide an inherent technological advantage in solving the vibration, jerk and lubrication problems of two-gear transmissions in electric vehicles. To this end, a magnetic gear two-speed transmission drive concept is proposed, and a configuration preference method for two-speed transmissions based on weighted directed topology maps is investigated. A directed weighted graph modulo adjacency matrix and topological evolution rules describing the structure of the system are established. Adjacency matrix ergodic evolution and isomorphism discrimination are investigated for single and two-stage magnetic gear two-speed transmissions, respectively. Through the constructed relative speed link identification algorithm, the speed ratio between any component is calculated quickly. A configuration preference method was established for the defined evaluation objectives via hierarchical analysis. Finally, a prototype was built based on the screening results. The test results showed that the optimal solution could accurately meet the design requirements and realize two-speed transmission. The accuracy of the configuration and screening method of the magnetic gear two-speed transmission system proposed in this article is verified. It provides a theoretical reference for the design of high-performance magnetic gear two-speed transmission.

Fault dynamics of six-branch coaxial herringbone gear transmission system

Fault dynamics of six-branch coaxial herringbone gear transmission system

Large eddy simulation and process research on abrasive flow precision machining of transmission spiral bevel gear

Transmission gear is the most basic part of mechanical transmission. The surface roughness of transmission gear affects its performance and service life, and traditional finishing has certain limitations. In this paper, the abrasive flow precision machining transmission gear is studied. Taking spiral bevel gears as the research object, the effect of different flow channel structures and different parameters on the machining effect is analyzed by using large eddy simulation numerical calculation method. The orthogonal test method is used to study the process of abrasive flow machining transmission gear. A numerical simulation of abrasive flow machining of spiral bevel gears was conducted under different inlet pressures, abrasive concentrations, and abrasive particle sizes. The optimal flow channel structure was utilized in this simulation. The change of different parameters of spiral bevel gear is analyzed, and the action law under different parameter conditions is obtained. The final surface roughness Ra value is increased from 2.5 μm to 0.08 μm, and the ideal flat surface is obtained. The effectiveness of abrasive flow machining of transmission gears is verified, which provides technical support for actual abrasive flow machining of transmission gears.

Dynamics Model and Its Verification of Aerospace Three-Ring Gear Reducer

This paper proposes a nonlinear dynamic modeling method based on the lumped mass approach to address the challenge of modeling the vibrations of the output external gear and internal gear plate in an aerospace three-ring gear reducer. A vibration model of bending–torsion coupling with 12 degrees of freedom was established by comprehensively considering factors such as the time-varying meshing stiffness, gear transmission error, tooth side clearance, bearing support stiffness, and damping. Finite element modal analysis and vibration test results verified the vibration model’s accuracy and applicability, indicating that the model is both precise and valid. The vibration model was solved using the fourth-order, five-level Runge–Kutta method. The results show that the symmetrical arrangement design of the internal gear plate cancels the vibrations in all directions and suppresses the vibration displacement response on the output shaft.

Numerical Characterization of Evolution Behaviors of Attractor in Gear Transmission with Multiple Excitations

Numerical Characterization of Evolution Behaviors of Attractor in Gear Transmission with Multiple Excitations

Dynamic Response of Electromechanical Coupled Motor Gear System with Gear Tooth Crack

The motor gear system (MGS) is recognized for its potential in enhancing transmission efficiency and optimizing space utilization. However, the system is subjected to challenges, notably the occurrence of abnormal vibrations. These issues stem from the dynamic interaction between the motor and gears, the presence of nonlinear factors in gear system, and the impact of gear faults, all of which contribute to complex vibration patterns. Traditional dynamic models have been found to be inadequate in effectively addressing the complexities associated with electromechanical coupling problems in MGS. To address these limitations, a comprehensive analysis approach is proposed in this paper, which is grounded in the development of an electromechanical coupling model. This method involves establishing a coupled dynamic model of the motor and gear system, integrating numerical simulations, and experimental validations to thoroughly analyze the vibration characteristics of the system. Through this multifaceted methodology, a detailed analysis of the system’s vibration characteristics is conducted. The results indicate that internal excitations from tooth root cracks not only directly affect dynamic characteristics of the gear transmission system (GTS) but also indirectly influence dynamic behavior of the motor, which offers valuable insights into modeling integrated MGS and provides significant solutions for fault diagnosis within these systems.

Weak compound fault identification of gearboxes based on improved symplectic geometric mode decomposition and optimized cyclic kurtosis deconvolution

Abstract Given the complex and harsh operating conditions of gear transmission systems, gearboxes are prone to compound faults. These faults, involving multiple types, often couple together, causing the weak fault pulse characteristics to be entirely masked by strong environmental noise. This significantly complicates the extraction of relevant fault information from the gearbox. To address these issues, this paper proposes a method for extracting compound fault features based on improved symplectic geometric mode decomposition (SGMD) and optimized cyclic bispectrum deconvolution (CYCBD). Firstly, considering the periodic impact characteristics of different fault types, morphological envelope cyclic bispectrum is proposed to cluster the initial components obtained from SGMD decomposition, thereby adaptively separating different fault features contained in the compound fault signals. An adaptive filter length search strategy is subsequently introduced to optimize the CYCBD by deconvolving each initial fault component, thereby eliminating the interference caused by complex transmission paths and substantial environmental noise, which, in turn, enhances weak periodic fault pulses. Following this, the enhanced signals are subjected to envelope demodulation to extract fault characteristic frequencies, enabling the identification of various types of faults. The effectiveness and feasibility of the proposed method are demonstrated through both simulation signals and actual experimental data related to gearbox compound faults. Compared with existing methods, the proposed method demonstrates superior performance in identifying weak compound faults under strong environmental noise.

Working ability of gear transmissions with gear wheels made of aluminum and titanium alloys

Working ability of gear transmissions with gear wheels made of aluminum and titanium alloys

The Impact of Bearing Housing Clearance in the Flender H4HV12B Gear Transmission on Potential Gear Tooth Demage

The article presents the impact of bearing housing clearance on the operation of a gear transmission, the consequences of operating the equipment under improper technical conditions, and the resulting implications. The article also describes vibration diagnostic methods as a tool for supporting the assessment of the technical condition and identifying the root causes of defects.

A model to study the effect of micropitting on the dynamic behaviour of a geared system

Geared transmission systems operate under increasingly severe conditions that tend to promote micropitting on the gear flanks. Micropitting leads to an increased local coefficient of friction, in particular due to an increase in the average roughness of the damaged surfaces. Micropitting is hard to predict, but also hard to detect, since it mainly affects the contact conditions, which affect friction forces. On global signals such as input/output torque, these friction forces are one to two orders of magnitude lower than the normal forces and tend not to be detectable due to the noise in the experimental setup. This paper aims at studying the effect of micropitting on the vibrational levels of a geared system, by coupling the gear dynamics model developed by Osman and Velex with the roughness-dependent coefficient of friction formulation from Xu et al., and by representing micropitting by a local increase of the composite roughness. The simulations show that micropitting has a clear impact on the system dynamic behaviour, especially in the direction perpendicular to the plane of contact. Finally, it was shown that the bearing forces and the pinion acceleration are suitable candidates for micropitting detection, even with noisy signals.

Dynamic investigation of a rack vehicle–track coupled system considering effect of multi-stage gear transmissions

Dynamic investigation of a rack vehicle–track coupled system considering effect of multi-stage gear transmissions

Early Failure Diagnosis of Scraper Conveyor Gearboxes Based on DS Evidence Theory and Multimodal Data Fusion

ABSTRACTA scraper conveyor is one of the important equipment to ensure reliable, efficient and stable mining and transportation of coal. As the most important transmission system of the scraper conveyor, the gearbox takes the role of transmitting power and torque. Due to the influence of working conditions in underground coal mines, the gear transmission system is often subject to the impact of nonuniform large loads, which is very prone to failures, and affected by environmental interference, it is difficult to detect the early abnormal signals of the scraper conveyor gearbox in the conventional industrial scenarios of fault monitoring methods. To ensure the stability and reliability of its work, this paper carries out the research on the multi‐parameter fusion of gearbox early fault diagnosis method under strong background noise interference. Aiming at the problem that the change of fluid physical and chemical characteristic parameters can reflect the early health condition of the gear transmission system and the single vibration signal is difficult to be extracted under the strong background noise, a model based on the fluid physical and chemical characteristic parameters and vibration signals is constructed by utilizing the RBF neural network and the Random Forest algorithm, and the body of evidence of the two models is fused at the decision‐making level through the DS evidence theory, which forms the fluid‐vibration multi‐parameter fusion judgment of the early fault diagnosis method of scraper conveyor gearbox. Through comparison, it is found that compared with the fusion methods, such as high‐dimensional variational self‐encoder, and single diagnosis methods, such as the Random Forest Algorithm, the method researched in this paper is more suitable for the early fault warning of the scraper conveyor gearbox of the well coal mine, and the experimental validation finds that the average accuracy rate of the early fault recognition can be up to 96.6%.

Design and simulation of reconfigurable modular snake robots with bevel gear transmission

With the advancement of technologies, robotics is playing an increasingly important role in various fields. The snake robot has attracted widespread academic attention due to its efficient and flexible movement characteristics. Nevertheless, its popularity and application range are constrained by complex control, low durability, and high cost. Given this, this study proposed a modular design framework based on the concept of modular design and a reconfigurable modular snake robot using bevel gear transmission. The snake robot consists of several basic module units with the same structure, which are restructured and reconfigured to achieve different shapes and functions. A standardized interface and communication protocol were optimized and designed, with each module containing an autonomous control unit and several execution units. The robot realized motion and tasks through the collaborative work of multiple modules to adapt to various work and environmental requirements. In addition, the research analyzes distributed control, improved motion control (using PID algorithm), energy management, safety design and other aspects, based on the cost data, improvement measures were proposed. At the same time, the work risks of the robot are analyzed, such as mechanical damage to the human body, adverse environment and electromagnetic interference, and corresponding solutions are proposed, and problems are found through durability testing and material improvement measures are proposed. Finally, based on SolidWorks software, a three-dimensional modeling and simulation analysis was conducted on the robot to verify its correctness. This study can provide inspiration for the design and research of snake robots.

Defect diagnosis of high contact ratio spur gear system with increasing level of fault

Breakage of tooth is common in power transmission gear systems with continuous running. Model of a system (virtual prototype) serves as a tool for generating large amount of data and can replace expensive experimentation. Dependability of a model depends on the purpose for which the data is generated. Two models of spur gear system are considered in this work: (1) block diagram-based planer kinematics model of spur gear system developed in Simulink environment which does not consider the support and torsional effects and (2) detailed CAD based multibody dynamics model (includes bearings, drive, coupling, connecting rod and supports) that considers backlash, axial and torsional effects developed using MBS ADAMS software. A custom-made high contact ratio gear system is fabricated for experiments. The time and frequency domain characteristics of experimental and simulated signals are compared to draw the conclusions of fault related symptom of the systems with increasing level of faults and the utility of models.

Transmission Gear NVH Analysis & Prognosis at end of Line Facility

Transmission Gear NVH Analysis & Prognosis at end of Line Facility

Establishment of a multi-clearance coupled 3D floating nonlinear model and vibration analysis for a coaxial reverse closed differential herringbone gear transmission system

Establishment of a multi-clearance coupled 3D floating nonlinear model and vibration analysis for a coaxial reverse closed differential herringbone gear transmission system

STRUCTURAL DESIGN OF NON-STANDARD GEAR TRANSMISSION

Non-standard gear transmissions are increasingly finding their applications in practice, primarily being designed for various applications. While standard circular gears are designed for a constant gear ratio, non-standard gears have a variable gear ratio that changes. This paper addresses the issue of designing non-circular gears for a specific range of gear ratios. An elliptical shape for the gears was chosen. The uniqueness of the proposed solution lies in selecting an ellipse as the evolute for creating the involute curve of the gear tooth.

An Active Control Method Based on the Study of Dynamic Characteristics of Integrated Electric Drive Systems

<div>Integrated electric drive systems are characterized by high power density, reliability, and controllability, making them increasingly prevalent in the realm of electric commercial vehicles. However, the direct coupling between the motor shaft and the transmission system has introduced a series of undesirable torsional vibration phenomena. To investigate the dynamic characteristics of electric drive systems in operation for electric commercial vehicles, a comprehensive modeling approach is employed. This modeling framework takes into account key factors such as gear backlash, structural flexibility, and electromagnetic spatiotemporal excitations. Based on this model, the influence of the electrical system on time-varying gear mesh stiffness, gear transmission error, bearing forces, and other factors is investigated. Building upon this foundation, the article proposes an approach for active harmonic voltage injection. This method effectively reduces torque fluctuations, decreases the amplitude and fluctuation of gear mesh stiffness and gear transmission error, lowers the vibration accelerations of each shaft, and enhances the reliability of the integrated electric drive system.</div>

Vibration source inversion-based fault diagnosis: Approach and application

The gear transmission system of industrial equipment is characterized by a highly integrated structure, non-stationary operating conditions, and large loads. Therefore, the attenuation of fault signal characteristics and the complexity of operating conditions in gear transmission systems significantly affect the effectiveness of vibration signal-based fault diagnosis. This paper proposes a unified diagnostic framework based on vibration source inversion for two typical transmission component fault signal phenomena: meshing frequency modulation sidebands and equally spaced fault characteristic frequency interval harmonic clusters. This approach incorporates the vibration transfer path analysis of passive subsystems and identifies bearing dynamic forces, followed by their decomposition, reconstruction, and sensitive frequency band localization. It enables accurate diagnosis of complex gear transmission systems under non-stationary conditions with limited vibration testing. The effectiveness and advantages of this method over existing mainstream signal processing techniques are validated through actual cases of gear and weak bearing fault diagnosis on a complex planetary gear transmission system test bench.