Gearbox Structure Research Articles

Power Loss Evaluation of an E-Axle Gearbox Considering the Influence of Gear Oil Factors

An accurate power loss prediction in the gearbox is desirable for improving vehicle efficiency. To achieve this objective, evaluating the power loss is necessary. However, power loss is influenced by factors such as the gearbox structure, operating conditions, and gear oil formulation, making power loss evaluation a bottleneck in practice. Therefore, a systematic modeling methodology was developed to evaluate the gearbox power loss in an E-Axle that focuses on the influence of the gear oil factors in the load and no-load cases. The gearbox used in a light-duty truck E-Axle was tested to verify the proposed model. The test was performed under various operating speeds, input loads, and oil temperatures, and four types of gear oil with different formulations were also included to quantify their influence on the power loss. The results showed that the gearbox power loss was significantly influenced by the E-Axle operating conditions, oil temperatures, and different gear oil formulations, promoting different power losses. The comparison results showed good consistency between the predicted power loss and the measured data. The proposed methodology can be utilized to effectively predict the power loss of the E-Axle gearbox and further improve the E-Axle efficiency by selecting suitable oil formulations and adjusting oil temperatures.

Variable-scale evolutionary adaptive mode denoising in the application of gearbox early fault diagnosis

Due to the influence of gearbox structure complexity, vibration signals are always corrupted by heavy multiscale noise interference distributed in modulation frequency bands, which brings great challenge for early fault identification. However, conventional adaptive noise cancellation methods mainly focus on a comprehensive denoising effect while ignore improper reference induced by multiscale characteristics of noise interference. This will lead to two major problems. On one aspect, reference filtering at sensitive scales is not mutually independent, and it has a negative influence on each other. On the other aspect, improper reference may cause losses of fault-related information. These limitations greatly hinder the fault features identification, especially in an early fault stage of a fault. Aiming at these problems, this study proposes a novel variable-scale evolutionary adaptive mode denoising method (VEAMD) for weak feature enhancement of gearbox early fault diagnosis. First, to sense the multiscale distribution characteristics of a desired signal, an ergodic VMD process with a dual domain energy factor (DDEF) is presented, where a series of Wiener filters are adaptively designed. Secondly, the desired signal and a reference signal are input into these Wiener filters to generate multiple mode subsignals with wideband noise suppressed. Meanwhile, multiscale noise interferences are separated into different scales as reference bases for mode denoising. Third, via evolutionary digital filters (EDFs), a refined reference filtering is performed within mode scale to obtain multiple intrinsic mode subsignals (IMSs), namely mode denoising. Finally, the Pearson correlation coefficients between two parts of each subsignal pair is employed as a weight to synthesize a denoised signal. In this manner, VEAMD effectively tackles an improper reference at local scales by a series of adaptive mode denoising, achieving more significant noise cancellation capability and an effect of weak feature enhancement, which is conducive for a timely and accurate early gearbox fault diagnosis. Simulation and experiment prove the superiority of VEAMD over other four methods.

Calculating component temperatures in gearboxes for transient operation conditions

The knowledge of component temperatures during transient operation conditions is essential for an optimal design of a gearbox. This is because critical peak temperatures limit the transferable power as well as the load capacity. Moreover, understanding the thermal behavior of the gearbox is key to improving its efficiency. Therefore, the Thermal Network Method (TNM) of the calculation program WTplus was extended to calculate component temperatures in gearboxes for transient operation conditions. Specifically, the TNM considers the component masses and specific heat capacities of each node modelling the gearbox structure. This enables the algorithm to compute a corresponding system of differential equations and thus determine the temperature change over time. Therefore, WTplus can be used to identify critical gearbox component temperatures during load cycles. The applied method was validated with measurements collected at the FZG gear efficiency test rig.

Coupling fault diagnosis of wind turbine gearbox based on multitask parallel convolutional neural networks with overall information

With the development of smart grid, capacity of wind power that connects to the grid increases gradually, which makes the continuous and stable operation of wind turbine (WT) critically important. Therefore, by considering gearbox structure and operating condition, a diagnosis approach for coupling faults of WT gearbox is proposed based on multitask parallel convolutional neural network with reinforced input (RI-MPCNN). The overall information array of gearbox that fuses wavelet packet transform of vibration signals, domain knowledge of gearbox components and operating condition s used as RI-MPCNN input. Then, RI-MPCNN that has parallel sub-convolutional neural networks (sub-CNNs) and multiple classifiers realizes the diagnosis of coupling faults of multiple components simultaneously. Meanwhile, a reinforced input is added to each sub-CNN to improve the diagnosis accuracy of each component. It is notable that the proposed approach not only fuses the overall gearbox information at system level, but also realizes fault diagnosis at component level. In the approach evaluation based on two case studies, the proposed approach can improve diagnosis accuracies by about 3 and 20% compared with the existing methods, respectively.

Fault Diagnosis Method of Gearbox Based on Sound Pressure Signal Analysis

The gearbox structure is complex, so it is difficult to determine the root cause of the problem after abnormal sound appears. The method of sound pressure signal analysis is used to analyze the abnormal sound of gearbox. The spectrum analysis method is used as the data processing method. The sound pressure of a kind of abnormal sound of gearbox is collected. By analyzing its frequency characteristics and structural characteristics, it is judged that the gear is abnormal. The accuracy of the inference based on the result of sound pressure analysis is verified by the shape and position detection of the gear. The results show that through the frequency analysis of the sound pressure signal, the root cause of the gearbox problem can be accurately determined.

Analysis on Hover Control Performance of T- and Cross-Shaped Tail Fin of X-Wing Single-Bar Biplane Flapping Wing

The current flapping wing adopts T-shaped or cross-shaped tail fin to adjust its flight posture. However, how the tail fin will affect the hover control is not very clear. So, the effects of the two types of tail on flight will be analyzed and compared by actual flight tests in this paper. Firstly, we proposed a new X-wing single-bar biplane flapping-wing mechanism with two pairs of wings. Thereafter, the overall structure, gearbox structure, tail, frame, and control system of the flapping wing were designed and analyzed. Secondly, the control mechanism of hover is analyzed to describe the effect of two-tail fin on posture control. Thirdly, the Beetle was used as the control unit to achieve a controllable flight of flapping wing. The MPU6050 electronic gyroscope was used to monitor the drone’s posture in real time, and the Bluetooth BLE4.0 wireless communication module was used to receive remote control instructions. At last, to verify the flight effect, two actual flapping wings were fabricated and flight experiments were conducted. The experiments show that the cross-shaped tail fin has a better controllable performance than the T-shaped tail fin. The flapping wing has a high lift-to-mass ratio and good maneuverability. The designed control system can achieve the controllable flight of the flapping wing.

Structural Strength Analysis of Gearbox Casing Based on ABAQUS

In order to improve the transmission accuracy, static and dynamic characteristics of the transfer gearbox of a test bench, a numerical model is built by finite element software ABAQUS to analyze its static characteristics. The static analysis under typical working conditions are investigated to obtain the stress and the strain, and then the static reliability of the structure is checked, which provides theoretical basis and guidance for the structural optimization design of the gearbox. The research shows that the gearbox structure is reliable and has greater space for structure optimization, which can improve the transmission accuracy and static characteristics.

Topology optimization of transmission gearbox under multiple working loads

This article is concerned with topology optimization of transmission gearbox under multiple working loads by taking dynamic performance as research object. First, the dynamic excitation model and finite element model are established, the vibration responses of the key points on gearbox are obtained by applying dynamic excitation on finite element model based on modal dynamic method, and the simulation responses are compared with testing results to validate finite element model. Finally, the gearbox structure is optimized by utilizing topology optimization method, and the lightweight model of transmission gearbox structure is redesigned. The dynamic performance indexes such as natural frequency are improved obviously, which indicates that the topology optimization method is very effective in optimizing dynamic performance of complex gearbox structure. The research has an important theoretical significance and reference value for lightweight design of transmission gearbox structure.

Investigation on Planetary Bearing Weak Fault Diagnosis Based on a Fault Model and Improved Wavelet Ridge

Rolling element bearings are of great importance in planetary gearboxes. Monitoring their operation state is the key to keep the whole machine running normally. It is not enough to just apply traditional fault diagnosis methods to detect the running condition of rotating machinery when weak faults occur. It is because of the complexity of the planetary gearbox structure. In addition, its running state is unstable due to the effects of the wind speed and external disturbances. In this paper, a signal model is established to simulate the vibration data collected by sensors in the event of a failure occurred in the planetary bearings, which is very useful for fault mechanism research. Furthermore, an improved wavelet scalogram method is proposed to identify weak impact features of planetary bearings. The proposed method is based on time-frequency distribution reassignment and synchronous averaging. The synchronous averaging is performed for reassignment of the wavelet scale spectrum to improve its time-frequency resolution. After that, wavelet ridge extraction is carried out to reveal the relationship between this time-frequency distribution and characteristic information, which is helpful to extract characteristic frequencies after the improved wavelet scalogram highlights the impact features of rolling element bearing weak fault detection. The effectiveness of the proposed method for weak fault recognition is validated by using simulation signals and test signals.

Numerical simulation of gearbox structure dynamics focused on backlash influence

This paper deals with numerical investigation of the single–stage gearbox housing dynamic behaviour during low-torque operating conditions. First the modal properties of the key components are derived and experimentally evaluated on the physical model. Next the main simulations are performed in MBS (multi-body system) software, the model is based on the open loop test rig. The computational methods aim to represent dynamic behaviour of the gearbox housing key parts with respect to NVH parameters evaluation, which is done by surface normal velocity amplitude. The presented part of investigation also deals with different kind of input speed variability. The simulation results show that the variable input speed has strong influence on dynamic behaviour.

Structure Noise Performance Analysis and Optimization Research on a Low-Floor Gearbox

With the rail vehicle industry development and increasing request to the riding comfort, to reduce the structure vibration and noise caused by the gearbox is increasingly valued. Multibody dynamics method is proved to be very effective to structure optimization for noise control in gearbox design process. This paper aims to find an optimization way for the gearbox structure to increase the structure noise performance. Initially gear shafts and the casing were discretized using the finite element method, subsequently the multi-flexible body of low floor gearbox was established in the SIMPACK which considering the time-varying mesh stiffness and backlash, bearings were modelled via radial, axial and rotational stiffness elements, then the multi-flexible body dynamic response were analyzed and the structure noise was predicted. Finally, optimization schemes, in terms of gear modification and structure improvement, were proposed to improve the structure noise performance.

Gearbox fault diagnosis of high-speed railway train

Abstract This paper is aimed at detecting crack faults of a lubricant level viewport and upper viewport of a high-speed railway train gear box operating for a repair cycle from 200,000 to 300,000 km. This paper reports a series of test results involving vibration and dynamic stress tests to identify the occurrence of partial resonance and stress concentration points of the gear box structure under external excitation tests. The results of the tests were confirmed using both finite element analysis and modal analysis. This paper also describes the causes of the crack fault on the gear box body and provides a comprehensive analysis of the causes of the gearbox crack. With this approach the faults on the high-speed train gearbox structure were identified and corrective solutions suggested.

Analysis of time-domain signals of piezoelectric strain sensors on slow spinning planetary gearboxes

Currently, condition monitoring of gearboxes mainly relies on signals of mechanical vibrations (mostly acceleration; fewer velocity and distance) or very high-frequency acoustic emissions as well as oil particle and temperature data. Strains are rarely used, since the common measuring technique employing strain gauges can cause problems in harsh environmental conditions.In the following, time-domain signals of robust piezoelectric strain sensors applied on the surface of the ring gear of a gearbox are analyzed regarding their mechanical basics, measurement chains and inferable information. The gearbox specimen is a main gearbox of a wind energy converter (WEC), which is deployed on a WEC system test rig. It can be shown that the surface strain on fixed ring gears in tangential direction is mainly influenced by the transferred tooth forces between planets and ring gear but also by the stiffnesses and geometries of the ring gear itself and the supporting gearbox structure. A direct comparison of sensor connection in AC- and DC-coupling shows that with the utilized piezoelectric sensors in DC-coupling surface strain signals with very low frequencies down to 0.002Hz can be obtained. The acquired signals show a very high signal-to-noise-ratio and high repeatability even at very low revolution speeds. Furthermore a direct correlation to the dynamic torque, which is transferred by the gearbox, and to the planetary load sharing is found.

A new electronic gearbox for gear hobbing machines

This article presents a new kind of software-defined electronic gearbox for gear hobbing based on a theoretical model of the hobbing process. The electronic gearbox implementation and structure are studied in an embedded numerical control system (numerical control/computer numerical control). Data flow among the electronic gearbox modules is also analyzed in the numerical control system. Special G-codes with parameters are designed, and the electronic gearbox control implemented through numerical control programming is realized in a custom gear hobbing numerical control system. In addition, two different hobbing methods (axial and diagonal) are tested on the computer numerical control platform. Results show that the hobbing computer numerical control with the proposed electronic gearbox functions accurately, and error is measured using tracking errors in different axes and gear pitch error of the machined gear. As will be shown, the gear pitch error was found to be 0.0147 mm for axial hobbing and 0.0176 mm for diagonal hobbing.

Analysis Optimization and Experimental Verification of Herringbone Gear Transmission System

Aiming at effectively analyzing on power transmission processing of herringbone gear trains system, reasonably estimating the gearbox structure vibration and noise, finite element model is put forward considering fluid-solid coupling of gearbox. Time-varying dynamic loads calculating from the Ref. [5] are applied on each center coupling point of bearing holes. Dynamic response analysis is carried out on the gearbox by the transient dynamic analysis module of ANSYS software, and structural vibration acceleration of the gearbox investigation nodes is estimated. Tooth dimensional optimization design with multiple dynamic targets is carried out by the adaptive genetic algorithm. Optimization results show the vibration acceleration of teeth meshing line direction and gearbox machine feet are both significantly reduced under given load condition. Herringbone gear transmission experiment testing system with closed power flow is set up to verify the theoretical analysis. In order to verify herringbone gear dynamic systems vibration transmission theory and tooth surface modification effects, teeth meshing line direction vibration is measuring through high precision angle encoders of Heidenhain, and vibration acceleration of bearing seat and machine feet are measured by accelerometer.

Vibration and Noise Radiation Characteristics of Gear Transmission System

This paper presents a comprehensive procedure to calculate steady dynamic response and noise radiation generated by a gear reducer. In this process, the bearing force is obtained by solving the transmission system dynamic model, which is taken as the excitation of the gearbox, the noise generated by the gearbox vibration is researched by using FEM/BEM, so the dynamic characteristics of gear transmission and gearbox structure are demonstrated. Then the time history of node dynamic response and noise spectrum of the gearbox are obtained, and the effect of the excitation of frequency doubling of mesh frequency on the gearbox vibration and noise radiation is illustrated. The changes in radiated noise of gear reducers with load are calculated respectively by using both simulation and Kato's formulae, and results agree well with each other. The frequency range of the gearbox resonance is obtained by analyzing the spectral maps of the vibration and noise under the case of engine speed steadily increased. The study provides useful theoretical guideline to the design of the gearbox.

Fatigue Crack Detection at Gearbox Spline Component using Acoustic Emission Method

The spline section of helicopter gearbox structure is susceptible to fatigue crack, and non-redundant characteristic leads to the need for early flaw detection strategies. Acoustic Emission (AE) method relies on propagating elastic waves due to release of energy from active flaws. The initiation of damage is identified using the features of AE waveforms such as energy, amplitude and frequency centroid. The characteristics of the AE features are influenced by sensor type, sensor location and gearbox operational conditions. In this study, the AE data was collected from a helicopter gearbox with a notched spline section and realistic operational conditions using two different AE sensors located at two different positions. The data collection was conducted over one year under various operational conditions. The AE features were extracted from long duration waveforms (100 milliseconds) at every pre- defined time step (every 5 seconds). The frequency domain features of frequency centroid and energy distribution in various frequency bands were compared with gearbox operational conditions such as torque, lift, gyroscopic moment, and temperature. The influences of sensor location, sensor type and operational conditions on the AE features are presented in order to decouple their influences from the AE features due to damage. The comparison between the predicted crack growth time using the AE data and the observed crack initiation shows that the AE method using frequency domain features of streamed waveforms has great potential to identify the crack initiation when the sensor type and location are preserved.

Study on Dynamic Simulation of Wind Turbine Gearbox Based on Pro/E and ADAMS

Domestic wind turbines with 1.5MW gearbox as the research object, application of virtual prototyping technology (ADAMS) simulation of dynamics of wind turbine gearbox when braking .According to research gear box structure, size and other parameters, using Pro / E software to create a solid model of wind turbine gearboxes. After importing to the ADAMS software, add the necessary constraints and loads, virtual prototype model of the gearbox is established. The simulation of dynamics of wind turbine gearbox are carried out by using ADAMS, and the angular velocity of the in-out shaft, gear meshing force and the vibration when braking cloud are obtained. That result is match with the theoretical value through analysis and the accuracy of ADAMS simulation is verified. The simulation results show that the design level of wind turbine gearboxes can be improved by using the virtual prototype technology and lay a good foundation for further design.

The Herringbone Gear Box Modal Analysis and Experimental Study

In order to more accurately estimate the intrinsic mode of herringbone gear transmission box, fluid-structure interaction model of gear box and lubricants is established. Gear system natural frequencies and mode shapes is calculate out on the establishment of the fluid-solid coupling dynamics equations. The finite element models of gearbox and lubricating oil are build by ANSYS software, and the results of inherent characteristics are given. The top ten order natural frequency is distributed between 611.8HZand 2487HZ, and the first two order mode shape is respectively shown as the axial swing and horizontal swing. In order to verify the analysis results, the hammering method of single-input multiple-output (SIMO) is used to test gearbox structure modal. The results show that the mode shapes get from ANSYS analysis are consistent with the datas of experimental measurements, and the maximum deviation of natural frequency between experiment and theory is blew 15%. So it can be shown the fluid-structure interaction model in this paper is effective and reasonable.

Design for Reliability Based Methodology for Automotive Gearbox Load Capacity Identification

Robust and Axiomatic design, a property-based approach in design, is applied and integrated into a new methodology for developing Functional Requirements (FR) or Design Parameters (DP). The reliability of the design structure and the elementary reliability of the design components are used as a functional requirement of the automotive gearbox, in relation to the service life and operation conditions, and also as a design constraint in analytical relationships. For this purpose, elementary reliability and allowable stress are defined in a specific way. The automotive gearbox, operating under varying and random operation conditions, is used as a case study. The same design structure has to operate under different operation conditions. In these circumstances, the carrying capacity as a functional requirement is related to the operation conditions and operation regime. The model presented in this paper, as well as a computer program, enable identification of this carrying capacity. This paper discusses an interdisciplinary and multi-methodological integrated approach to the presented task. Experimental data regarding the failure probability of gearbox components and the probability of operation conditions processing, the decomposition of gearbox structure, and the elementary reliability treatment as a component of design property are only some of the methods applied.