Planetary Gear Train Research Articles

Optimization Design for the Planetary Gear Train of an Electric Vehicle under Uncertainties

The planetary gear train is often used as the main device for decelerating and increasing the torque of the drive motor of electric vehicles. Considering the lightweight requirement and existing uncertainty in structural design, a multi-objective uncertainty optimization design (MUOD) framework is developed for the planetary gear train of the electric vehicle in this study. The volume and transmission efficiency of the planetary gear train are taken into consideration as optimization objectives. The manufacturing size, material, and load input of the planetary gear train are considered as uncertainties. An approximate direct decoupling model, based on subinterval Taylor expansion, is applied to evaluate the propagation of uncertainties. To improve the convergence ability of the multi-objective evolutionary algorithm, the improved non-dominated sorting genetic algorithm II (NSGA-II) is designed by using chaotic and adaptive strategies. The improved NSGA-II has better convergence efficiency than classical NSGA-II and multi-objective particle swarm optimization (MOPSO). In addition, the multi-criteria decision making (MCDM) method is applied to choose the most satisfactory solution in Pareto sets from the multi-objective evolutionary algorithm. Compared with the multi-objective deterministic optimization design (MDOD), the proposed MUOD framework has better reliability than MDOD under different uncertainty cases. This MUOD method enables further guidance pertaining to the uncertainty optimization design of transportation equipment, containing gear reduction mechanisms, in order to reduce the failure risk.

Investigations on crack propagation and meshing characteristics of planetary gear train considering crack closure effect

The shape of spatial crack is more complex in practice and crack closure will occur due to deformation, which will result in partial contact of the crack surfaces. In previous researches, a simple linear plane assumption for the gear crack trajectory was usually made and the crack closure effect was ignored. Based on the principle of linear elastic fracture mechanics, a three-dimensional numerical model of planetary gear train crack propagation considering the initial crack location, ring gear backup ratio and constraint mode is built in this study. Considering the crack closure effect and the obtained crack trajectory, the meshing characteristics (including the time varying meshing stiffness (TVMS) and contact pressure) are investigated. The results indicate that when considering the crack closure effect, the reduction in the TVMS of the cracked gear decreases and the influence of the foundation crack closure effect on TVMS is greater than that of tooth crack closure effect. Appropriately constraining the outer rim of the thinner ring gear can help avoid catastrophic foundation crack, but the TVMS is more sensitive to the change in the backup ratio when only the pin support is restrained. The uneven distribution trend of cracked tooth contact pressure depends on the nonpenetrating crack type.

Design and free vibration characteristics of linkage planetary gear trains

Design and free vibration characteristics of linkage planetary gear trains

Size and efficiency based comparison of kinematically equivalent two-carrier planetary gear trains

The subject of this paper is a two-carrier planetary gear train (PGT) which was developed for a specific purpose. This PGT may be used for applications in which a negative transmission ratio in the range -3…-143 is required. In this case, the mechanical and dimensional properties of the PGT have been analyzed for nominal negative transmission ratios of -30 and -40. All possible combinations of simple component PGT ideal torque ratios providing those transmission ratios were obtained. Only the combinations providing the minimum radial dimensions of the PGT assembly were selected. Subsequent analysis has shown that the PGT radial dimensions will be minimized when the ratio of the reference diameters of the planetary unit ring gears is close to unity, meaning that the PGT casing will be cylindrical rather than stepped. This paper also provides an overview of the DVOBRZ software package used to synthesize the different gearbox layouts for the required transmission ratio, combined with a basic introduction to single speed two-carrier PGTs for better understanding. The DVOBRZ software was used to select all the acceptable gearboxes were selected from the set of generated PGTs according to the criteria of minimum dimensions and acceptable efficiency range. This set of PGTs was checked for kinematic feasibility and construction concepts were created for feasible layouts.

On the using of two-carrier planetary gear trains with two compound and four external shafts as change-gears

An overview of all possible structural schemes of two-carrier planetary gear trains (PGTs) with two compound and four external shafts is made. One of possible application of these PGTs is as change-gears. A few cases of this application are presented and investigated through the torque method. Kinematical possibilities of PGTs in question as function of parameters of component simple PGTs are discussed.

Design and experimental study of a planetary gearing mechanism based on twice unequal amplitude transmission ratio

To obtain the optimal seedling taking trajectory, this study proposed the adjustment of the total transmission ratio curve by using human-computer interaction. On the basis of this design method, a planetary non-circular gear mechanism was designed that can realize the twice unequal amplitude transmission ratio to meet the seedling harvesting requirements. The cubic non-uniform B-spline curve was used to fit the twice unequal amplitude transmission ratio curve, and the transmission ratio was freely distributed in two levels. The seedling pick-up mechanism was designed by controlling the seedling taking track and the corresponding attitude directly through the local section of the total transmission ratio, and the gear pitch curve was directly controlled by the transmission ratio. The kinematics model of the seedling pick-up mechanism was also established. Furthermore, the influence of the total transmission ratio on the seedling picking track, the ratio of the wave crest to the amplitude, and the mechanism parameters were discussed. A human-computer interactive optimization software was developed using Matlab, and a set of optimal parameters for the seedling pick-up mechanism was obtained to meet the transplanting requirements. By using the Adams software, the virtual prototype simulation of the seedling pick-up mechanism was completed, and the idle experiment for the track and attitude of the prototype was conducted through high-speed camera technology. The theoretical, simulated, and experimental trajectories were consistent with each other. Results revealed that the success rate of the seedling picking exceeded 90% when the rotation speeds were 40 r/min, 50 r/min, and 60 r/min, and the qualified rate of the matrix decreased with the increase in rotating speed. Moreover, the number of damaged plants increased with the increase in rotating speed. The experimental results showed that the seedling pick-up mechanism designed using the proposed method demonstrated a good effect and met the required seedling picking performance. Keywords: seedling pick-up mechanism, second unequal amplitude, planetary gear train, seedling picking experiment DOI: 10.25165/j.ijabe.20221501.6168 Citation: Liu J G, Yu G H, Tong Z P, Hua Y. Design and experimental study of a planetary gearing mechanism based on twice unequal amplitude transmission ratio. Int J Agric & Biol Eng, 2022; 15(1): 155–163.

Računska metodologija za sintezu konfiguracija sistema epicikličkog zupčastog prenosa sa više planetarnih zupčanika

Epicyclic Gear Transmission Systems (EGTs) find a wide variety of applications in automatic transmission systems due to their flexibility to deliver a variety of speed ratios. The design of EGT involves the enumeration of all possible layouts, typically called structural synthesis. Thus, the structural synthesis of an EGT consists of defining a topology for EGT with coupled planetary gear trains (PGTs) along with constraining elements such as connections, brakes, and clutches while delivering a definite transmission ratio between the input and output shafts. Given the number of PGTs, permanent connection, clutches, and brakes, the methodology systematically introduces these elements of PGTs to deliver the given number of distinct speed ratios. Determining the number of distinct speed ratios for a given combination of brakes and clutches has been expressed as a transformation of a graph representation of the EGT layout. A computer program has been developed for the structural synthesis of EGTs and validated against the 3 epicyclic, 6-speed EGT systems. The viability aspects of the synthesized structure are carried out. Also, an isomorphism test is addressed in the synthesis methodology to detect unique EGT structures at every synthesis stage.

Design and teaching feedback of switching steering transmission device in production line

The transmission device is composed of rotary motion mechanism and vertical motion mechanism. The rotary motion mechanism is composed of synchronous belt transmission planetary gear train composed of synchronous belt transmission and upper and lower connecting arms to ensure that the product rotates 90° counterclockwise and 90°clockwise; The vertical motion mechanism is composed of cylinder, ball and spline transmission technology. The transmission device is flexibly implanted into the curriculum with the carrier of new technology and new process, which feeds back the teaching, and takes the curriculum thought and politics as the guide to implement the teaching.

Critical Analysis of Design of Ravigneaux Planetary Gear Trains

Critical Analysis of Design of Ravigneaux Planetary Gear Trains

Analysis of nine-speed planetary change-gears through the torque method

An alternative method for kinematic and power analysis of compound gear train is presented, which uses the torques and lever analogy of a given gear train. The method combines the accuracy of the Willis analytical method with the clarity of the graphic method of Kutzbach. Unlike these methods, the torque method allows determining not only the gear ratio, but the magnitude and direction of power flows, and hence the determination of efficiency of a given compound planetary gear train. The application of the method is illustrated with example of novel arrangement of complex nine-speed change-gear. Structural, kinematic, and power (efficiency) analysis are made. A software for these analysis facilitation is developed. A numerical example is presented and discussed.

Graph representation of planetary gear trains: A review

The various graphical representations of planetary gear trains (PGTs), including basic assumptions and graph rules, are first reviewed in this paper. They revealed that they had close relationships. Their similarity has stimulated the development of a unified graphical representation. When there are multiple joints in a graph, it can be reconfigured without affecting the information contained in the graph. To accomplish this, a rooted graph in which a multiple joint represents either the housing of the mechanism and/or a transfer vertex of a multi-planet fundamental geared entity is employed.

Optimization of two-speed planetary gearbox with brakes on single shafts

This paper deals with configurations of complex planetary gear trains consisting of two planetary gear trains of basic type. These gear trains are formed by linking shafts from different component gearsets and contain two carriers, and therefore designated as two-carrier planetary gear trains with four external and two coupled shafts. The structural configurations are pointed out, and additional research has been made into gear trains using coupled external shafts for torque input and output, with the controlling brakes acting on single external shafts. The kinematic schemes have been created for all analyzed PGT variants, and the available transmission ratio ranges calculated for both speeds. The transmission ratio is changed by alternating the activation of each brake, enabling their use as transmissions with two transmission ratios in transportation technology and other engineering applications. Extreme transmission ratio changes have been determined for each analyzed PGT design solution. Also, relations of ideal torque ratios to the required transmission ratios of component planetary gear trains for both speeds have been calculated. These relations enable the selection of compound gear train designs which will achieve the required pair of transmission ratios. The optimal design parameters for the adopted configuration were determined, and the optimal transmission solution for the given input data selected.

A calculation method of transmission efficiency for RV reducer

RV reducer is the core component of industrial robot. It is of great significance to raise the transmission efficiency of RV reducer for improving the transmission performance of industrial robot. RV reducer belongs to the 2K-V type planetary gear train and consists of an equal speed ratio mechanism. Therefore, according to the structural characteristics of RV reducer, the virtual power theory and split power theory are adopted, and a calculation method of transmission efficiency for RV reducer is proposed. Firstly, the structure of a common RV reducer is introduced. Related structural analysis, kinematic analysis, and loaded analysis are given. Secondly, RV reducer is represented by the method of graph theory. By the virtual power theory and split power theory, the power flow direction is determined, and the values of split powers are calculated. Finally, according to the graph representation for RV reducer and the calculation principle of meshing power loss of planetary gear, the power losses of meshing gear pairs are calculated, respectively. According to the input and output values described in graph representation of RV reducer, the formula of transmission efficiency for RV reducer is derived. The calculation of transmission efficiency for RV-40E reducer is considered as an example. The result is compared with previous work on the subject, and the relations between design parameters and transmission efficiency of RV reducer are discussed.

Stability Analysis of a Planetary Gear Train Having Repeated Natural Frequencies

A Planetary gear trains (PGTs) are widely used in numerous engineering fields, such as automotive, aerospace, and wind turbines, etc. In the dynamic model of geared systems, the time-varying meshing stiffness causes parametric resonances or instability. This paper investigates the instability caused by the time changing meshing stiffness in a PGTs with three symmetrically arranged planet gears. Focus is placed on the instability related to the repeated natural frequencies. The multiple scales method is used in the analysis, and the analytical results are verified with numerical simulation based on Floquet theory.

Application of incidence matrix to topological structure and kinematic analysis of multi-planet gear trains

In this paper, a matrix notation is presented to decompose the structure of any planetary gear train (PGT) into its constituted fundamental geared entities (FGEs). The representation of the PGTs by matrices motivates the need for a method for discretizing PGTs into FGEs. This paper proposes a novel method for the structural decomposition of PGTs with the aim of dividing the structure into several independent substructures with single DOF. This is accomplished by determining the transfer vertices and second level vertices in matrix form. Although there are a large number of existing analysis methods, there is no method yet that entirely performs the kinematic analysis of multi-planet gear trains automatically in the computer in a simple way. Understanding the topological properties of existing PGTs is very useful for benchmark synthesis to explore all possible designs that are based on existing ones. Also, any type of FGEs with any number of links can be investigated without knowing the exact size of gears.

Dynamically Balanced Pointing System for CubeSats: Study and 3D Printing Manufacturing

The increasing presence of additive manufacturing (AM) in the space sector prompted us to investigate the feasibility of a single degree of freedom (DoF) pointing system (PS) made by means of a compound planetary gear train system (C-PGTS) integrating a dynamic balancing system (DBS) and entirely realized in AM. We analyzed in detail the dynamics of the system dealing with the design and the realization of the prototype. Of fundamental importance for this paper is the careful selection of materials for AM suitable for the prohibitive conditions of space. The results, deriving from the comparison between the experimental part and the simulations, underline the correct dimensioning of the PS and the fundamental importance of DBS in maintaining the satellite attitude. The results also confirm the capabilities of AM in the production of complex mechanical systems, allowing high precision, combined with interesting mechanical properties and low weight.This suggests the potential of AM in the space domain, both for structural parts and active components, such as those listed in this work.

Reversing Behavior of Planetary Gear Train Influenced by Support Stiffness of Driving Shaft

Planetary gear trains (PGTs) are widely used in many machines and are one of the most important mechanisms in hybrid and electric vehicles. Previous research, based on empirical knowledge gained from the automobile industry, indicates that high carrier-support stiffness and low ring-gear support stiffness are required to reduce ring-gear errors. Therefore, here, we evaluate the vibration characteristics of a PGT as a function of the support stiffness, which is varied by inserting urethane rubber into the driving shaft. We conducted experiments using a 2K-HV-type tester, which contains a coaxially rotating and revolving planet gear shaft based on a universal joint. This mechanism allows the observation of the inner workings of the mechanism with the use of a transparent acrylic carrier. We were able to detect the so-called “bounce” phenomenon consisting of a swaying motion when the rotation of the ring gear is reversed, and this result was confirmed by our internal observations of the mechanism. It is evident that the index of vibration increases due to the bounce phenomenon because the reversal of the ring gear causes a larger vibration than that of the carrier because the ring gear can vibrate without restraint, unlike the planet gear that is sandwiched between the sun and ring gears. Furthermore, the influence of the radial support stiffness of the driving shaft, load torque to the output shaft, and acceleration time of the reversing gear on the “bounce” phenomenon were evaluated. We found that a larger load torque corresponds to a greater difference depending on the acceleration conditions of the sun gear. During reversal, at the moment when the rotation speed is zero and rotation recommences, the ring gear exerts the maximum force, and the larger is the load torque, the greater is the effect of the difference in acceleration.

I-SA Algorithm Based Optimization Design and Mode-Switching Strategy for a Novel 3-Axis-Simpson Dual-Motor Coupling Drive System of PEV

Pure electric vehicle (PEV) equipped with a dual-motor coupling drive system can make full use of the high efficiency working range of the motor in order to improve vehicle efficiency. In order to further expand the application range of the system and to improve its practical application, this paper designs and proposes a new dynamic coupling drive system of three axis-double working modes, which is based on the Simpson planetary gear train. The new system adopts two planetary gears (P1 and P2), and the two sun gears of double rows, planetary carrier of P1 and gear ring of P2 are bunded. The power output of the P1 gear ring (mode 1) and P2 planetary carrier (mode 2) is realized by a controlling wet clutch. This paper adopts the linear interpolation method, least square method and 5-fold CV cross validation method to establish the full load speed characteristics and efficiency characteristics models of two motors (13 and 30 kW). This paper proposes an optimization design method based on an improved simulated annealing (I-SA) algorithm for new system parameter matching and working mode switching strategy determination. The results show that the modeling accuracy of the two motors is high, and the mean value of MAPE is 4.337%. The proposed optimization design method achieves the demand goal of PEV effectively. The I-SA algorithm has good effectiveness and fast convergence, the mean efficiency of the optimized PEV is 83.91% under all working conditions, the maximum speed is 142.56 km/h and the power utilization rate of the dual-motor is 100%. This study proposes a new hardware system and a design optimization method on software and provides a direct reference for the research of PEV drive systems by combining hardware with software.

Layout Guide for Design of a Novel Wheelchairs with Circumferential Linkage using Microsoft Word

In recent decades, the aging of the world’s population has intensified, and the number of people with disabilities caused by various disasters and diseases has gradually increased. Most of the elderly, frail and disabled people will choose wheelchairs as their means of transportation. However, ordinary wheelchairs are unable to climb stairs, especially in cities, which seriously limits the range of activities of wheelchair users and affects their daily life. Hence, it is of great significance and value to design an intelligent building climbing wheelchair with appropriate price, stability and safety. This paper designs a multi-functional planetary height adjustable building climbing wheelchair with simple structure and low price. Firstly, a multi-functional building climbing wheelchair based on planetary gear train is designed by using modular design idea, including ground walking mechanism, in place steering mechanism, center of gravity adjustment mechanism and Seat leveling mechanism. The working principle and design characteristics of each mechanism are analyzed in detail. Then, through the analysis of the mathematical model of the climbing mechanism, the dimensional parameters of the three-star wheel set are determined. According to the power demand of wheelchair, the power system is selected and analyzed. It provided a new possibility for the wheelchair application and also for those in need.

Simulation and experimental test of load-sharing behavior of planetary gear train with flexible ring gear

Simulation and experimental test of load-sharing behavior of planetary gear train with flexible ring gear