Two-stage Gearbox Research Articles

Computing solution spaces for gear box design

AbstractThe design of gear boxes is a complex challenge characterized by conflicting requirements and seemingly circular dependencies. Existing tools support engineers but focus on a single predefined design, often leading to costly iterative processes and non-optimal solutions. Solution Space Engineering (SSE) alleviates this by generating multiple designs represented by solution spaces. For this, a particular model structure is needed, and thus restructuring existing models, e.g., from industry standards. The application of solution spaces to a two-stage gear box is presented.

Structural design and dynamic characteristics analysis of braided composite two-stage gear transmission system

In order to realize the lightweight design of the transmission system, the braided composite material is applied to the two-stage gear transmission system. According to the structural characteristics of the two-stage gear reducer box, the whole box is designed to be assembled with the braided base and the box wall. Woven composite materials are applied to the web parts of mixed metal composite gears to realize the design goal of lightweight gears. Then, under the assumption of ignoring the influence of friction, bearings and other factors on the system, the dynamic model of the two-stage gear transmission system considering the box is established. By normalizing and dimensionless processing of the equations, the dimensionless differential equations of motion are obtained. The fourth-order Runge–Kutta method is used to analyze the relationship between the connection parameters and the dynamic characteristics of the system under the two working conditions of rigid and flexible connection between the composite base and the box wall.Through the analytical analysis of vibration displacement of two-stage gear reducer and box, the theoretical basis is found for the numerical analysis results. Finally, the dynamic characteristics of the transmission system are studied by vibration resonance analysis through high and low frequency interference. It is found that in a certain frequency range, with the decrease of the mass and moment of inertia of the transmission parts corresponding to the mixed metal composite gear, the amplitude-frequency characteristic Q of the lightweight gear and gearbox transmission system is slightly lower than that of the common gear and gearbox system, and the stability of the system is increased, and the dynamic characteristics of the system are improved.

A Condition-Based Maintenance of Two-Stage Gearbox Using Analytical Ferrography

A Condition-Based Maintenance of Two-Stage Gearbox Using Analytical Ferrography

Investigation on the Lubrication Heat Transfer Mechanism of the Multilevel Gearbox by the Lattice Boltzmann Method

In a gear transmission system in a closed space, the heat transfer between gears and fluids presents highly nonlinear characteristics due to the complex physical processes involved in heat exchange and fluid motion, and constructing and solving the thermodynamic model of the gearbox becomes a task that involves considerable difficulty. This paper takes a conical–cylindrical two-stage gearbox as the research object, proposes a fluid–solid coupled dynamics model based on the lattice Boltzmann (LBM) combined with the large eddy simulation (LES) method, and the adopted lattice model is the D3Q27 velocity model, which is used to numerically simulate the distribution of the flow field inside the gearbox and undertake in-depth research on the fluid motion law of the complex gear transmission system in the enclosed space. The model is solved to reveal the laws determining the gear speed and the effects of the lubricant’s dynamic viscosity and thermal conductivity coefficient on the gear heat dissipation efficiency. By adopting the lattice Boltzmann method, we can simulate the fluid flow and heat transfer inside the gearbox more efficiently, which provides a new way to closely understand the thermodynamic behavior of closed complex gear transmission systems. The application of this method is expected to provide strong support for thermal performance optimization and the design of gear transmission systems.

Low noise optimization of two-stage gearbox housing structure based on acoustic contribution analysis and topology optimization

Low noise optimization of two-stage gearbox housing structure based on acoustic contribution analysis and topology optimization

Design of 10:1 Speed Reducer for an Elevator

This work aims to design a mechanical transfer system that allows us to integrate the need for power and speed ratio existing in the industry to obtain a safe mechanism ensuring the transmission system, which is optimal for maintenance. The methodology consists of two-stage gearbox design features a gear mechanism with a gear ratio of 10 to 1 to decrease the output speed and increase the motor torque. The gearbox design parameters were calculated using the Excel program; for the simulations the SolidWorks program was used. To check the gear analysis, the calculation of the safety factor of the pinion, the gears and the material validation are evidenced.

Assessment of local faults in helical geared system using vibro-acoustic signals based on higher order spectrum analysis

Geared transmission system plays an important role in modern technology to transmit both power and motion. The power transmission and control requirements in manufacturing, aviation, transportation, energy industries require uninterrupted operation under high efficiency.Increase in fatigue load cycles in a geared transmission system thereby leading to negative impact on contact surfaces of gear tooth, which result in non-unifor m power transmission, increase in dynamic response, and decrease in efficiency followed by catastrophic tooth failure.The wear propagated on gear teeth contact causes a variation in the dynamic response of geared system. It is widely acceptedthat the local/distributed faults developed on rolling/sliding contact elements can be detected by using vibration and/oracoustic monitoring and analysis techniques.This paper describes the results of experimental studies carried out to detect and diagnose the simulated faults in the helical gear tooth of a two stage helical gearbox.The helical gear was mounted in a two-stage gearbox operating under controlled speed and load conditions. The vibration and airborne sound signals obtained from the gearbox were considered to attain a reliable fault related information by using a higher-order spectrum analysis technique. The fault related features extracted from the vibration and the acoustic data post processed by using bispectrum analysis provided a better diagnostic information to detect progressive faulty operating conditions viz., 20%, 40%, 60%, 80% and 100% tooth removal cases in the gearbox.

Consideration of multi-variable uncertainty using the GPC method for the dynamic study of a two-stage gearbox of a wind turbine

This paper deals with the problem of the uncertainties interaction in the design parameters of a two-stage gearbox of a wind turbine. The purpose of the dynamic study is to minimize the linear displacements in order to have more stability. The uncertainty consideration using a unique parameter, allowed the identification of the influence of this latter on the dynamic response, in addition to its extreme values. The examination of multivariate parameters investigates the interaction of these parameters. Thus, the gear system dynamic behavior was studied by taking into account the uncertainty with a suggested diagram: uncoupled form to evaluate the impact of each parameter and coupled form based on the progressive interaction of uncertain dynamic parameters using the multivariate uncertainty method. For this purpose, the generalized polynomial chaos approach (GPC) was applied to simulate the dynamic behavior of the wind turbine gearbox. The obtained results were then verified using Monte Carlo simulations.

Multi-objective optimization of gearbox based on panel acoustic participation and response surface methodology

Aiming at noise problem of two-stage gearbox, this paper uses the panel acoustic contribution analysis (PACA) and response surface methodology to conduct structural-borne acoustics analysis and multi-objective optimization of gearbox. Using this optimization, optimal layout and parameters of the added ribs can be determined. The dynamic model of a spur gear-shaft-bearing system is built in consideration of the time-varying mesh stiffness, the time-varying bearing stiffness, and the flexibility of the shaft, while dynamic load of the bearing is obtained through solving the model. The dynamic load of bearings is considered as excitation to analyze the vibration and noise radiation characteristics of housing. Furthermore, acoustic transfer vector, modal acoustic contribution and PACA are used to select the region with the most acoustic contribution. The variable ribs structure model (VRSM) is established in this region. Finally, the VRSM are adopted to optimize the housing. The optimization model based on the peak sound pressure level (PSPL) and the ribs mass (Rm) is established by using response surface method. Through multi-objective optimization, the variable in VRSM can be modified or deleted to reduce the radiated noise of the gearbox. The optimization results demonstrate that the PSPL after optimization is decreased by 4.88 dB at frequency of 3130 Hz. At the same mass, the noise reduction effect of VRSM is 12% higher than that of standard rib. Therefore, the optimization effect of the housing structure is obvious. PACA-VRSM-RSM- NSGA-II technology provides a new research scheme for reducing the vibration and noise of the gearbox.

MODERNIZATION OF THE MACHINE FOR HYDROTHERMAL TREATMENT OF GRAIN

The purpose of hydrothermal processing of grain is to change its initial technological properties in the direction ofstabilization and maintaining them at the optimal level for the further process of processing it into the final product - flour or cereals.The use of devices of continuous action allows the steaming process to become more efficient, while hydrothermal treatmentoccupies a special place in the technology of processing cereals, obtaining them high consumer properties. The analysis of designs ofdevices of continuous action, shows that the most widespread have devices of horizontal type where the main working body of thesteamer has functions of transportation and hashing. This design allows to achieve uniformity of steaming during processing of theproduct. To achieve a flexible change in the exposure of steaming, it is proposed to introduce a two-stage variator in the drive of theworking body, which will significantly change the steaming time and use the apparatus for steaming more different crops, and toensure a constant set steam pressure the design of which allows to carry out these operations without pressure losses. In the two-stageversion of the variator, the rotation from its drive shaft by means of a V-belt is transmitted to the intermediate shaft, and from it bymeans of an additional V-belt to the main working shaft. The gear ratio is adjusted by turning the glasses and their synchronous shiftin the axial direction.At the same time there is a simultaneous movement of movable conical disks, transfer of a V-belt and anadditional V-belt to other diameters. We use sluice gates with a flat sealing surface and a fluoroplastic gasket to supply grain to theworking chamber under pressure and unload it. This design allows the most effective sealing of the working chamber under pressureand to maintain the working pressure within the specified limits, with continuous loading and unloading of the device. Thecalculations show the feasibility and efficiency of modernization of the steamer by ensuring the tightness of the unloader and theuniformity of the speed of the product processed in the working chamber by using a two-stage gearbox or drive motor with afrequency converter.

A sparse feature extraction method based on the shiftinvariable dictionary applied in the diagnosis of gearbox with multiple faults

Abstract The vibration signals of gearbox often contain complex components, such as the gear engagement, shafts rotation, bearings, and vibration of the box, and they brings a big challenge to fault diagnosis of gearbox. Furthermore, there are many fault types of gearbox, and the fault characteristics of them are possibly the same. For example, the pass frequency of the missing tooth or root crack in the gear on the input shaft are both equal to the rotation frequency of input shaft. In thus circumstance, traditional diagnosis methods are inapplicable, because we can’t determine which type of faults. In this paper, we proposed a dictionary learning with the shift-invariant dictionary to extract the fault features in a sparse way, and afterwards hidden Markov model (HMM) is utilized to identify the fault type from extractive features. We used the proposed method to diagnose the experimental data from a benchmark two-stage gearbox and there are nine different health conditions introduced to the pinion on the input shaft, and the diagnosis result verifies the good performance of the novel scheme in the fault diagnosis of gearbox.

Optimizing the partial gear ratios of the two-stage worm gearbox for minimizing total gearbox cost

Optimizing the design of a worm gearbox is complex to get due to considering multiple objectives and numerous main design parameters. Hence, a more consistent and robust optimization technique will be considered in obtaining the optimized results. This paper presents the optimization process of the Two-Stage Worm Gearbox with the objective function of minimizing total gearbox cost. Ten main design parameters are chosen as input parameters for evaluating their impacts on the response of the partial gear ratio u2. In this study, the simulation experiments were used, which do not need cost to perform all potential tests. In order to do this, a 2^(10-3) model and using 1/16 fractional model were selected due to the limitation of the built-in function in Minitab@18. Moreover, the screening experiments are purposely used to determine the number of parameters, which has a minor influence on the response. Compared to using the Taguchi technique, the model of 2^11 corresponding to L32 or 32 tests is a simple method to achieve the objectives. The results show that Total gearbox ratio exhibits the biggest effect on the response compared to others. Furthermore, the interactions between these factors to the remaining are significant. The high reliability of the proposed model is verified by simulation experiments. The random tendency of data shows that u2 is not crucially influenced by other than the input parameters. The data in versus order prove that the response is not varied to the time factor. Moreover, the coefficients of adjusted R2 and R2 are both greater than 99 %, it can be concluded that the proposed regression model is appropriate. The proposed optimization process in this study is reliable and the optimal design method can provide a useful reference on performance improvement of other worm gears.

Experimental investigation of the generator mode for a brushless dc motor at an increased rotational speed

This article deals with a commercially available direct drive brushless DC motor that was investigated in the generator mode at an increased speed above the rated one. During the conducted experiments the increase of the generator rotational speed was carried out due to a three-phase asynchronous motor with 5.5 kW rated power and 2920 rpm rated speed, which was further increased by a two-stage belt gearbox with a reduction ratio from 0.16 to 1.6. However, with an increase in the rotational speed, the magnetic losses also increase, which in turn increase the required value of the input mechanical power and lead to thermal overload of the brushless DC machine. An increase the generator rotational speed leads to an increase of the EMF value and, at the same value, of the stator current, leads to an increase the generated power. Throughout the experiment, the voltage was rectified using a diode bridge and bulk capacitor, after that it was connected to a load resistance. The presented calculations of the magnetic power losses for different electrical steel grades clearly demonstrate the nonlinear dependence between the magnetic field frequency and its magnitude. Experimental studies were carried out at different speeds of rotation of a brushless DC machine in a very wide range from 140 rpm to 5228 rpm, moreover, the values of the output power were obtained depending on the rotational speed. It is concluded, that in the generator mode of the brushless DC machine, it is necessary to take into account the feature of the operation at wind power plants, autonomous power supply such as hybrid power plants. In the first case, it is worth limiting the rotational speed from the driven mechanism, and in the second case, this mode of operation may be necessary for partial boosting of output power for short-term use.

Modeling the Business Value of an Early Fault Detection System using Monte Carlo Simulation

The automotive industry is undergoing a period of rapid advancement, as OEMs race to develop the next generation of electric and autonomous vehicles. Many manufacturers are investing in prognostics technology, which has made advancements mainly in the aerospace industry over the past couple decades. Unlike aerospace applications, which have relatively more safety-critical systems, it can be more challenging to identify a business case for developing a prognostics or early fault detection system for an automotive application. In the retail setting, early fault detection systems may increase warranty costs, and the benefits to customer satisfaction may not be worth this additional cost. For fleet managers who own and operate many vehicles, however, a business case can be made based on the value of preventing unexpected downtime and unnecessary maintenance. Developing a reliable early fault detection algorithm for a complex system can be an expensive undertaking, requiring many parts, months of data collection, and possibly years of effort, so it is important to understand the possible return on investment for the effort.
 
 In this paper, we present a method to model the business value of an early fault detection system. The method is generic and may be applied to any system where the failure modes are purely fatigue based (i.e. abuse modes are excluded), and the failure rate of each part in the system can be independently modelled using a time-to-failure probability density function. The model is based on Monte Carlo simulation, and the assumptions and limitations are explored. The model can be used to estimate the expected savings from implementing an early fault detection system and derive requirements on the true positive and false positive rates required for the fault detection system to meet its business objectives. An example is presented with application to a two-stage gearbox, such as one that may be found in an electric vehicle powertrain. The example shows how to estimate the parameters for each component, how to estimate the costs associated with failure, and ultimately how to interpret the model outputs and drive business decisions.

Analysis of Dynamic Characteristics of the Multistage Planetary Gear Transmission System with Friction Force

Multistage planetary gear transmission system has been widely utilized in engineering practice due to the salient characteristics, such as high bearing load and large speed ratio. This paper addresses a two-stage planetary gearbox and establishes a system coupling torsional dynamical model which considers the time-varying mesh stiffness, friction forces, and interstage coupling factors. Meanwhile, the friction and lubrication states are classified to comprehensively analyze the calculation of friction coefficients under different conditions. Considering the time-varying influence of friction on the tooth surface under the condition of fluid lubrication, the vibration response under parametric excitation is solved by a numerical method. A multistage planetary transmission test bench is built in the back-to-back form so as to test the vibration of the two-stage planetary gearbox. It shows that the simulation results of the dynamical model are consistent with the test data. Consideration of the calculation of friction on the tooth surface and the friction coefficients is helpful for the establishment of the more accurate dynamical model and lays the foundation for the structural design, fault diagnosis, and dynamic optimization of the multistage planetary gear transmission system.

Frequencies estimation of gearbox vibration signal based on normalized lattice filter with RLS-based algorithm

In this paper, in order to estimate the meshing frequencies of a gearbox online, based on its vibration signal, an adaptive notch filter with a normalized lattice structure is proposed as an estimator. The notch filter exhibits a high degree of robustness and a low level of estimation errors, due to the minimal dynamic range of the node energies of the normalized lattice structure. A novel lattice recursive least square (NLRLS) algorithm, which introduces a correlation value between the vibration signal and the output signal of the estimation filter into the LRLS algorithm, is used as the adaptive algorithm for the notch filter. Theoretical analysis and simulation results show that the NLRLS algorithm exhibits greater stability than the LRLS algorithm for vibration signals where prior information is lacking. The meshing frequency estimation experiment is performed on a two-stage gearbox experimental platform. A triangular cascade structure is used to connect multiple notch filters to achieve multi-frequency estimation. The experimental results show that the notch filters can estimate meshing frequencies quickly and accurately, which verifies its effectiveness.

Electric traction drive of an agricultural tractor

In the article, the task of expanding the range of work in speed and moment of traction electric drive of an agricultural tractor is considered. We propose to achieve this goal through the use of a two-stage gearbox based on a three-row planetary gear. It is proposed to shift gear ratio by eliminating one row of the gearbox from the process of converting mechanical energy. Evaluation of the effect of the proposed solution was tested on a refined mathematical model, in which the electric drive is presented as a complex “frequency converter with vector control - motor - working body. The obtained simulation results allow us to argue that with the correct operation of the system in long-term operation, energy savings of up to 12% can be achieved (for various types of soil and operating modes: arable land, driving), and for transient processes - 7-8%.

Influence of long-wave deviations on the quasi-static and dynamic excitation behavior at higher speeds

The scarcity of fossil fuels and increasing oil prices are among the factors that have led to a rising ownership of electric cars [1]. Noise reduction also plays a major role primarily in the drive train of motor vehicles. Noise and vibration excitation differ between a combustion engine and an electric motor. While the disturbing noises of auxiliaries, e.g. gear noise, have been largely masked by combustion engines, theses noises are no longer masked due to the use of electric motors [2]. Therefore, gear noise is perceived more pronounced. Considering the subjective perception and the excitation by rotational frequencies, that fall into the sensitive hearing range of high-speed gearboxes, the focus must be increasingly placed on manufacturing and assembly related long-wave deviations, such as wobble, pitch errors and eccentricities.This report investigates the effects of long-wave deviations of gears in gearboxes on the excitation and noise behavior. Quasi-static investigations were carried out to verify the influences of long-wave deviations on the long-wave excitation behavior. Therefore, the transmission error was measured, which describes the rotational fluctuation between input and output and represents the excitation.This investigation verifies according to the simulativ investigation by Brecher et al. that there is no transmission error dependency on the load [3]. In addition, this investigation proves the macro geometry-independent long-wave excitation in case of eccentricity. The reason for the invariant excitation behavior lies in the effective deviation in the gear mesh which in this case is independent of the mentioned parameters.In addition to the quasi-static tests, investigations of the structure-borne noise were carried out at higher speeds (input rotational speed up to nIn = 11,500 rpm). For these investigations, a two-stage gearbox with a test gear set was used and two different eccentricities and wobbles were manufactured. The analysis of these investigations confirm an increased excitation as a result of the deviations. Especially in natural frequency ranges, the excitation in the first rotational order is amplified by the considered long-wave deviations.The experimental results prove the importance of a function-oriented tolerance system for long-wave deviations, which lead to corresponding long-wave excitations. Furthermore, the findings constitute the first basis for the derivation of these tolerance limits.

An Improved Computational Method for Vibration Response and Radiation Noise Analysis of Two-Stage Gearbox

In this work, an improved computational method for the prediction of the vibration and noise of a gearbox that considers the flexibility of the shaft is developed. Based on the finite element method (FEM), a coupled dynamic model of a spur gear-shaft-bearing system is established, and the time-varying mesh stiffness (TVMS), the time-varying bearing stiffness (TVBS), and the flexibility of the shaft are considered. The Newmark integration method (NIM) is utilized to obtain the dynamic load of the bearing. Furthermore, the proposed model is validated by experiments. The bearing load is then considered to be the excitation of the housing, and the radiated noise is calculated via the finite element method/boundary element method (FEM/BEM). The effects of the shaft flexibility on the bearing response and radiated noise are discussed based on the proposed method. The results demonstrate that, when the shaft flexibility is considered, the system undergoes the bending vibration of the shaft, and the vibration amplitude and excitation frequency components of the bearing load decrease significantly. Additionally, the main resonance mode of the gearbox is changed, and the radiated noise is enhanced. The effects of the input speed and shaft stiffness on the bearing response and radiated noise are also investigated. The results provide a theoretical basis for the further development of the vibration and noise reduction of gearboxes.

Experimental Characterization of the Coupling Stage of a Two-Stage Planetary Gearbox in Variable Operational Conditions

This paper presents an experimental characterization of a two-stage planetary gearbox (TSPG) designed at the Laboratory of Robot Mechatronics (LARM2) in the University of Rome Tor Vergata. The TSPG operates differentially as function of the attached load and the internal friction forces caused for the contact between gears. Experiments under varying load conditions are developed in order to analyze the usefulness of the gearbox to avoid excessive torques on its internal elements. The analysis of the dynamic torques is presented as an indicator of stability in the gearbox operation. The results show that the actuation of the second operation stage reduces the torques 57% in the output shaft and 65% in the input shaft. The efficiency of the gearbox is estimated as 40% in presence of high internal friction forces.