Planetary Reducer Research Articles

Optimal Design of a Compound Planetary Reducer Using a Nonlinear Optimization Method

The growth of the robotics industry has led to rising demand for reducers that increase torque efficiently while reducing motor speed. Among them, compound planetary reducers can be effectively used in robots because they can achieve high gear ratios with smaller volume. The design of conventional reducers comprises the method of setting a gear ratio to design the gear dimensions and calculating efficiency through dynamic analysis. However, this method suffers from repeated designing and analysis, which makes it very time-consuming. Therefore, this study defines the problem of reducer design as the problem of optimization by setting an objective function, constraints, and boundary conditions, and proposes to obtain the results in a short period of time using the Sequential Least Squares Programming(SLSQP) method. Using the SLSQP method, optimization results can be obtained as real numbers, making it suitable for use in compound planetary friction reducers with no constraints on the selection of gear dimension. For the design problem of the conventional compound planetary gear reducer in which the module value exists, an additional optimal design method considering the module is proposed. To compare the optimal results, we have made a 30:1 compound planetary friction reducer and a 50:1 compound planetary gear reducer using 3D printing. A gear ratio evaluation experiment was conducted to evaluate the performance of the actual manufactured prototype reducers.

Contribution analysis of vibration transmission path of planetary reducer box based on velocity involvement loss

Planetary reducer box undertakes the vibration transmitted from gear transmission system to bearing, and further transmits the vibration to the base. Research on the transmission path contribution of reducer box has an important guiding role in reducing vibration. This paper first analyzed the contribution of each vibration path of the gearbox based on the velocity intervention loss, so as to identify the main transmission path of the gearbox vibration; then the vibration test of the gearbox is carried out to verify the correctness of the transmission path model. The results show that the vibration transmission path of the right bearing of the gearbox is the main transmission path, and the established vibration transmission path dynamics model of the gearbox can well reveal the contribution law of the vibration transmission path of the gearbox.

Triboelectric sensor for planetary gear fault diagnosis using data enhancement and CNN

The planetary gear transmission system is characterized by a complex structure and is often exposed to harsh working conditions, resulting in high failure damage rate. The self-powered sensing system based on the triboelectric nanogenerator provides an ideal scheme for online monitoring of the planetary gear operating condition. In this paper, a triboelectric planetary gear sensor (TPGS) is proposed for real-time monitoring of the speed and gear faults of the planetary reducer. The sensor is integrated at the tooth crest and root meshing gap of the planetary gear and the ring gear, which ensures the integrity of the gear structure and function. The results of the sensing experiment show that TPGS can be used to detect the speed of the planetary reducer in the range of 10–1000 rpm. Moreover, the speed detection error rate is less than 0.4%. To identify the gear faults, the stacked autoencoder (SAE) is used to enhance the data collected by TPGS, combined with convolutional neural network (CNN). The results show that the classification accuracy reached 100%. In this paper, a theoretical and experimental basis for development and online fault monitoring of a new intelligent gearbox with self-awareness and self-regulation is provided.

МЕТОДИКА ОЦЕНКИ МОДАЛЬНЫХ ПАРАМЕТРОВ ПЛАНЕТАРНЫХ РЕДУКТОРОВ МОТОР-КОЛЕС КАРЬЕРНЫХ САМОСВАЛОВ ПРИ ИХ ЭКСПЛУАТАЦИОННОЙ ВИБРОДИАГНОСТИКЕ

Technical condition diagnostics of the planetary reducers of motor wheels in mining dump trucks electromechanical power units requires the study of dynamic processes caused by shock pulses in gearings when tooth remating. The levels of the occurring vibrations are determined by the natural frequencies and natural modes of reducer. The article describes calculation method based on the study of the developed dynamic model of a two-row planetary reducer of a motor wheel, describing the torsional vibrations of its elements and differing from the known ones by taking into account the compound motion of the planetary row satellites, the axes of which rotate together with the carrier. The calculation of natural frequencies and modes of vibrations is reduced to the computation of eigenvalues and eigenvectors of a matrix of special form based on the application of the iterative numerical method of Jacobi rotations. As an example, the calculation is given for gears of the motor wheel reducer of BELAZ mining dump trucks of the 7530 and 7531 series with a load capacity of 220 and 240 tons, respectively. The calculation of the natural frequencies of reducer performed makes it possible to determine those harmonic components of vibration-inducing disturbances in the form of shock pulses which cause resonance phenomena in the mechanism contributing to a significant increase of dynamic loads levels and accelerating the processes of lifetime expense of gear trains. In addition, the analysis of natural modes parameters makes it possible to determine the reducer elements with the highest vibration activity and monitor during vibration monitoring the technical condition of gear trains that limit the reliability of the mechanism.

Hybrid 3K Compound Planetary Reduction Gearbox With a Roller Transmission Mechanism

Reduction gears are used in the joints of the robots. While precision and efficiency are required for industrial robot gearboxes, humanoid robots are expected to become more popular in the future. Flexibility must be considered in humanoid robots, and high back drivability shall be required. In this study, we aimed at realizing high efficiency, and high-precision reduction gears with high reduction ratios by maximizing the efficiency equation, hybridizing a 3K compound planetary reduction gearbox and traction drive, experimentally determining the efficiency, backlash, and angular velocity variation, and demonstrating the effectiveness of the proposed mechanism from a control perspective. In the experiments, we achieved a maximum forward driving efficiency of 90.90%, backward driving efficiency of 90.58%, and a minimum backlash of 1.18 arcmin.

DESIGN AND PERFORMANCE ANALYSIS OF AN IN-WHEEL HUB REDUCER

In order to reduce the greenhouse effect caused by CO2 emissions, a lot of car manufacturers are developing battery electric vehicles (BEVs). Almost all of these vehicles have a traditional powertrain layout with the drive unit located in the car body. However, in recent years, a new technology called in-wheel motors has appeared. It significantly improves handling and manoeuvrability of vehicles but it also presents a challenge for both researchers and manufacturers. Since the motors are fitted into a limited space, they must provide high torque and high efficiency. When a reducer is used, the amount of torque needed is decreased several times, hence the overall dimensions of the motor are reduced. This paper studies a number of issues such as the basic concepts of the in-wheel hub drive systems, traction balance, preliminary gear ratio and possible design solutions for reducers used in in-wheel hub drive units. Characteristics of single-stage planetary and cycloidal reducers are analysed in detail. The results show that planetary reducers have an advantage if a lower gear ratio is needed.

Dynamic behaviour of a planetary reducer with double planet gears

Abstract. Planetary reducers have a wide and significant application in modern machine industry. They are extremely compact and reliable, and they can achieve a wide range of gear ratios as well as high efficiency. Since they often operate in extremely changeable working conditions, such as often starting and stoping, it is both interesting and desirable to study their dynamic behaviour. This paper presents a dynamic model of a planetary reducer with double planet gears created by applying Lagrange's equations of the second kind. After a planetary gear reducer has been designed and a CAD model created, the dynamic model was made. Most of characteristic values needed for solution of the equations are taken from the CAD model. Due to their complexity, the equations are solved in math simulation software. A lot of interesting results concerning the dynamic behaviour of the model are obtained, which can be helpful in understanding the dynamic occurrences in the inside of a planetary gearbox. At the end of the paper, conclusions are drawn, and further research directions in this area are given.

Belief reliability modeling and analysis for planetary reducer considering multi-source uncertainties and wear

The planetary reducer is a common type of transmission mechanism, which can provide high transmission accuracy and has been widely used, and it is usually required with high reliability of transmission characteristics in practice. During the manufacturing and usage stages of planetary reducers, uncertainties are ubiquitous and wear is inevitable, which affect the transmission characteristics and the reliability of planetary reducers. In this paper, belief reliability modeling and analysis considering multi-uncertainties and wear are proposed for planetary reducers. Firstly, based on the functional principle and the influence of wear, the performance margin degradation model is established using the hysteresis error as the key performance parameter, where the degradation is mainly caused by the accumulated wear. After that, multi-source uncertainties are analyzed and quantified separately, including manufacturing errors, uncertainties in operational and environmental conditions, and uncertainties in performance thresholds. Finally, the belief reliability model is established based on the performance margin degradation model. A case study of a planetary reducer is applied and the reliability sensitivity analysis is implemented to show the practicability of the proposed method. The results show that the proposed method can provide some suggestions to the design and manufacturing phases of the planetary reducer.

ANALYSIS OF OPERABILITY OF THE SPECIAL VEHICLE TRANSMISSION

The work is devoted to the analysis of the transmission of a special vehicle (SV) for moving on various surfaces, in particular on stepped ones, designed for people with disabilities. Based on the analysis of various vehicles for the movement of people with disabilities, a model of a SV was created. The main difference of proposed SV is the possibility of using the movement of the passenger՚s center of mass relative to the chassis of a SV for stabilization of the movement. A kinematic scheme of the SV transmission which includes the planetary reducer was created. The reducer provides movement of SV at various modes. Also SV transmission was modeled in the Solidworks software. The analysis of the performance of this transmission when moving a SV on various surfaces was made on base of created 3D-model. Based on the analysis, the efficiency of the transmission of a SV was proved both when moving on a straight surface, and in walking mode when overcoming steps.

Overview of Robotic Reducer Testing Technology

As a high-performance precision reduction transmission equipment with large transmission ratio, high transmission efficiency, high transmission accuracy, stable transmission and low noise, reducer has been widely used in many fields such as industrial robots. The definition of the reducer is studied, the development history of the reducer is briefly introduced, and the classification and characteristics of the reducer are summarized, including traditional reducer, RV reducer, harmonic planetary reducer and cycloid reducer, A new generation of reducer and influencing factors such as transmission accuracy, transmission efficiency, backlash, torsional stiffness, noise, and assembly. The problem of precision reducer is analyzed, and finally the application and development trend of reducer are studied.

Structure Design and Experimental Study of Pin-Cycloidal Planetary Reducer for the Pitch of High-Power Wind Turbine

In recent years, with the development of manufacturing technology and production capacity, wind power industry has been developed rapidly.A new type of pin-cycloidal planetary reducer was proposed in this studyfor the actuator of the pitch of high-power wind turbines. Based on the transformation mechanism method, the transmission efficiency of the reducer was calculated by analyzing the pin-cycloidal meshing efficiency, bearing efficiency, and output mechanism efficiency. Prototype testing were combined to systematically and deeply study the design theory of the reducer for the pitch of high-power wind turbines. Finally, a new design was proposed for a reliable two-stage pin-cycloidal planetary reducer with a strong bearing capacity and multi-tooth meshing on the hard gear surface that can be applied to the pitch system of high-power wind turbines.

Intelligent Optimization Design of the Cutting Unit’s Transmission System of a Shearer Based on Robustness

To improve the robustness of the shearer cutting part and reduce the manufacturing cost, in this study, the gear transmission system of a shearer’s cutting unit can be divided into three basic components: single-gear-on-one-shaft form, the planetary reduction form, and double-gears-on-one-shaft form. The dynamic differential equations of each structure are established in this study, and the volume functions of the three basic components are obtained. The characteristics of the internal excitation of the gear transmission system are analyzed, and a scheme for solving the motion parameters of each component is formulated based on the harmonic balance method. Based on the parameters, such as tooth width, tooth number, and modulus, as optimized variables, a robust optimization method minimizing the multi-parameter evaluation function, which is weighted linearly by dimensionless vibration and volume of the gear transmission system, is presented. The gear transmission system of a sample shearer’s cutting unit is optimized using the proposed method. The results show that the transmission system’s size decreases by 5.4%, the drum’s maximum torsional acceleration decreases by 17.8%, and the first gear’s maximum torsional acceleration decreases by 9.6%. Thus, we conclude that the optimum design method decreases a shearer’s manufacturing cost and decreases the cutting unit’s failure rate.

PERSPECTIVES OF CYCLOID TRANSMISSION

In modern mechanical engineering, transmissions with the use of an involute tooth profile are widespread. However, one of the main disadvantages of these transmissions is that they exposure to wear. In this study, research on the cycloid profile is conducted as an alternative option. Cycloid profiles are one of the profiles applied to the teeth in order to transmit motion. Although cycloid profiles are mainly used in instrumentation, satellites are made of cycloid profile in planetary gears. Cycloid profile teeth are less exposed to wear during operation. Practically, the shape of cycloidal teeth does not allow them to break, so there is no bending deformation in the teeth. In planetary gear transmission, the satellites are usually made of a cycloid profile. Cycloid profile teeth are exposed to less wear. Currently, planetary gear reducers are widely used mainly in the oil industry, drilling equipments, in the lifting mechanisms, gearboxes, on chain conveyors, rotary tables, in robotics, manufacturing, mechanical and chemical engineering fields and so on. The increased load capacity of the cycloid pinion gears is due to the multi-pair contact surface and it has a superior adhesion profile than the involute profile. The loading schemes of cycloidal and evolvent profile teeth shows that the normal force in contact Fn and its dangerous section on the tooth of the cycloidal profile is much less than in the case when the tooth has an involute profile. This is due to the fact that with cycloid profile transmission the number of teeth simultaneously transmitting the load is significantly greater than when implementing the same transmission with involute teeth. Cycloid profile gear reducers can be considered as a modern solution to current requirements such as high efficiency, smooth and quiet work, ability to accept short-term maximum loads, small overall size, minimum technical requirements etc. The simulation of the real load conditions and interference generated during the rotation of the shaft was developed in Solidworks in order to determine the contact stresses and the contact areas resulting from these stresses of the teeth of the gear and satellites of cycloid profile planetary gear reducers. This simulation determines the values of the teeth involved in the contact, the interference of those teeth, the contact areas and the contact stresses generated in these areas, depending on the angle of rotation of the shaft. The profile of the proposed teeth allows to achieve the minimum size with the maximum transmission ratio. Keywords: cycloid profile, cycloid transmission, planetary reducer, interference, simulation, contact area.

Research on the vibro-acoustic propagation characteristics of a large mining two-stage planetary gear reducer

Abstract In this paper, a computational model is proposed to predict the noise radiation of a planetary gear reducer. In addition, a system-level vibro-acoustic model of a two-stage planetary gear reducer is also established, and the dynamic contact equations of engagement are deduced to investigate the dynamic loads at the interface of bearing-housing and ring-housing in operation, using a large mining two-stage planetary reducer as a test mechanism. Moreover, the frequency response of the planetary transmission has been derived, the radiation noises from the two-stage planetary gear train are analyzed, the simulation results agree well with the experimental results. This research can be guide structural optimization of planetary gear mining reducer.

МОДЕЛИРОВАНИЕ УПРАВЛЕНИЯ ПРИВОДОМ ПЕРЕКЛЮЧЕНИЯ ПЕРЕДАЧ И ПРИВОДОМ МЕХАНИЗМА ПОВОРОТА БЫСТРОХОДНОЙ ГУСЕНИЧНОЙ МАШИНЫ С БОРТОВЫМИ КОРОБКАМИ ПЕРЕДАЧ

The relevance of the topic of investigation is connected with the current trends in gearbox automation and request to lighten slew control of caterpillar vehicles. The purpose set can’t be achieved only in a physical modeling of a drive: the problem is too multiversion and a physical modeling does not guarantee an optimum solution. 
 The scientific novelty of the investigation consists in the authors’ creation of simulator of gearbox drive and slew mechanism drive consisting of an electromotor, a planetary reducer, a crank mechanism, a hydraulic distributor and hydro-cylinder. 
 As a consequence, there is realized a parametric investigation possibility of drive numerous parameter impact upon its performance characteristics. By means of the mathematical modeling the drive parameters ensuring the fulfillment of the requirements specification are substantiated. 
 In the second part of the paper there are shown modeling results of caterpillar vehicle acceleration in a low and the fourth gears and a slew at a speed of 5 m/sec. The result comparison of mathematical modeling and experimental investigations is carried out. The data of experiments, in which took part the authors of the paper, confirm completely the adequacy of the simulator developed. In such a way, the simulator of caterpillar vehicle motion is supplemented with the reliable model of a gearbox drive and a slew mechanism drive in machinery with the border gearboxes. The paper material is used in the design of a similar drive of a new machine.

МОДЕЛИРОВАНИЕ УПРАВЛЕНИЯ ПРИВОДОМ ПЕРЕКЛЮЧЕНИЯ ПЕРЕДАЧ И ПРИВОДОМ МЕХАНИЗМА ПОВОРОТА БЫСТРОХОДНОЙ ГУСЕНИЧНОЙ МАШИНЫ С БОРТОВЫМИ КОРОБКАМИ ПЕРЕДАЧ

The relevance of the topic of investigation is connected with the current trends in gearbox automation and request to lighten slew control of caterpillar vehicles. The purpose set can’t be achieved only in a physical modeling of a drive: the problem is too multiversion and a physical modeling does not guarantee an optimum solution. 
 The scientific novelty of the investigation consists in the authors’ creation of simulator of gearbox drive and slew mechanism drive consisting of an electromotor, a planetary reducer, a crank mechanism, a hydraulic distributor and hydro-cylinder. 
 As a consequence, there is realized a parametric investigation possibility of drive numerous parameter impact upon its performance characteristics. By means of the mathematical modeling the drive parameters ensuring the fulfillment of the requirements specification are substantiated. 
 In the second part of the paper there are shown modeling results of caterpillar vehicle acceleration in a low and the fourth gears and a slew at a speed of 5 m/sec. The result comparison of mathematical modeling and experimental investigations is carried out. The data of experiments, in which took part the authors of the paper, confirm completely the adequacy of the simulator developed. In such a way, the simulator of caterpillar vehicle motion is supplemented with the reliable model of a gearbox drive and a slew mechanism drive in machinery with the border gearboxes. The paper material is used in the design of a similar drive of a new machine.

Development of Marine Turning Gear Based on Helical Planetary Reducer

Development of Marine Turning Gear Based on Helical Planetary Reducer

Modal analysis and experimental research on a planetary reducer with small tooth number difference

To comprehensively analyze the modal characteristics of the planetary reducer with small tooth number difference, based on shaft–bearing–gear–shell coupling, a finite element modal analysis model was established in ABAQUS. The teeth meshing sites were constrained by binding, bearings were simulated by spring elements, and then the natural frequencies and corresponding vibration modes of the reducer were obtained by applying the Lanczos method. Further, a hammering modal experiment on the reducer was carried out utilizing LMS Test.Lab. The modal data were analyzed using a modal identification method, and the modal frequencies and damping ratios were achieved, also the experimental modal parameters were validated according to the modal assurance criterion. The research results indicate that the lowest-order natural frequency of the reducer is 148.53 Hz, which is much higher than the rotation frequency of the eccentric shaft, double gear, and output gear. Also, the two-stage gear mesh frequencies are away from the natural frequencies, therefore the reducer under normal operating conditions will not cause coupling resonance. This research provides a theoretical basis and experimental reference for the dynamic structure optimization of the planetary reducer.

Моделирование математической модели дифференциального планетарного редуктора в программе ANSYS

Моделирование математической модели дифференциального планетарного редуктора в программе ANSYS

Simulation model of oscillations of the “sun gear – satellites” pair of turboprop engine planetary reduction gearbox in the presence of defects of tooth flanks

Defects of planetary reduction gearboxes of turboprop engines often cause excitation of high-frequency oscillations that bring about failures of compressor structural elements. The vibration behavior of these reduction grarboxes is a broadband process with the presence of a large quantity of vibration components, which significantly complicates the search for informative diagnostic indicators of defects. In order to simplify the procedure of identifying the vibrations caused by defects of toothed gearing a simulation model of the vibration behavior of a turboprop engine differential gear unit is proposed. The model takes into account kinematics and design of the gearbox, determines the structure of its vibration behavior in the presence of defects on the tooth flanks. Using the example of a commonly occurring defect in the form of wear of the teeth of the solar gear satellites pair the adequacy of the model to the actual vibration behavior of the mechanism is shown.