Planetary Set Research Articles

RECOGNITION OF A LANDSCAPE TECHNO-SPHERE AS A NEW GEOSPHERE

The second half of XX century – the beginning of XXI century are characterized by the active development of a global ecological crisis, which is described by a critical state of the environment and excessive anthropogenization of a geographical sphere. The changes which lead to the formation of absolutely new techno-genic landscapes occur at very fast rates in current geo-spheres. The purpose of the work is to substantiate the recognition of a new geo-sphere – a landscape techno- sphere – based on the previous experience and our field research. The main tasks of the research are to analyze specific features and properties of a landscape techno-sphere; to identify its upper and lower borders; to study a structural organization of all options of a landscape sphere with available techno-substances; to characterize briefly the main stages of the development of a techno- sphere.
 The research of a landscape techno-sphere is a complicated process and it is based on the use of classical and innovative methodological principles of contemporary geography. A parallel application of three scientific paradigms is the foundation: system, model and ecological. They do not contradict each other; they rather compliment the studying of the interaction between nature and engineering. A system approach allows considering a techno-sphere as a complicated system of a lower taxonomic range of a landscape sphere and a geographical sphere. The following generally accepted scientific methods are used in the paper: analysis, synthesis, comparison, generalization, systematization, induction and deductions.
 The article substantiates the existence of a new geosphere – the landscape techno-sphere, which is formed by the planetary set of landscape-technical systems. it is noted that it does not have a continuous distribution, but is constantly increasing in size and gradually goes beyond the landscape. The specific features and properties of the landscape techno-sphere are analyzed in detail. Taking into account the criterion of the presence of a zone of direct contract of three blocks of landscape-technical systems (managerial, technical and natural), the upper and lower limits of the landscape techno-sphere are identified. The structure of all variants of the landscape sphere in the presence of technological substances is considered. The main periods of development of the landscape techno-sphere are briefly described. It is concluded that man will never be able to control landscape-technical systems on a planetary scale. However, applying the methods and principles of engineering landscape research, it is possible to achieve optimal interaction of the three blocks of landscape-technical systems and to extend their functional suitability.

Coordinated control strategy for mode switching of power-split hybrid electric bus

In the dynamic process of mode switching of the power-split hybrid electric bus, the vehicle will have longitudinal shock due to the drastic change of the two motors’ torque and the engine’s slow response. To solved this problem, this paper will focus on the process of switching from pure electric mode to hybrid drive mode, considered the operational state changes before and after engine ignition, limited the torque fluctuation transmitted from the front planetary set to the output shaft based on the idea of motor compensation, and calculated the motor compensation torque of the rear planetary set to compensate the torque fluctuation of the output shaft, to reduce the jerk. Firstly, the dynamic models of the transmission system before and after the engine ignition are established, respectively, and then the dynamic torque of the engine is estimated by XGBoost. The estimated value is input into the model predictive controller (MPC) to track the engine speed and calculate the torque fluctuation generated by the front planetary set on the output shaft. Then, according to the estimated value of the engine torque and the predicted value of the engine’s speed, the compensation torque is calculated by the sliding mode controller (SMC). Finally, the vehicle model is built with AVL CRUISE and MATLAB/Simulink software to verify the mode switching control effect of hybrid electric bus under typical urban conditions in China. The results showed that this control strategy significantly reduces the jerk of the mode switching process.

Meshing Stiffness Parametric Vibration of Coaxial Contrarotating Encased Differential Gear Train

Planetary gears are widely used in mechanical transmission systems, but the vibration and noise affect their reliability and life. In this paper, the torsional dynamic model of an encased differential planetary gear with coaxial contrarotating outputs considering the time-varying meshing stiffness, damping, and phase difference of all gear pairs is established. By solving the equations of the derived system, three types of natural frequencies with different multiplicities of the system are obtained. The multiscale method is used to study the parametric vibration stability caused by the time-varying meshing stiffness, and the results are verified by numerical simulation. The dynamic characteristics of elastic meshing force are analyzed from time domain and frequency domain. The variation of the dynamic load factor of each gear pair with input speed and the relationship between its peak position and the natural frequency of the derived system are discussed. The results show that there is an unequal coupling phenomenon of meshing frequency between the meshing forces of different planetary sets. In the absence of external excitation, the meshing stiffness parameters not only excite the main resonance response of the system but also cause superharmonic resonance, subharmonic resonance, and combined resonance.

Planetary gearbox spectral modeling based on the hybrid method of dynamics and LSTM

It is the prerequisite for mechanical diagnosis to clarify the mapping relations between vibrations and damage conditions based on the dynamic model analyses and the systematic experiments. However, there is a certain deviation from the actual measurements in the existing planetary dynamic modeling methods which utilizes linear models or just considering simple non-linear factors. To solve the problem, the hybrid spectral modeling method based on the fault dynamics analysis and the long short-term memory (LSTM) network is proposed in this paper. Firstly, the response of several parts in planetary sets are simulated by the classical dynamic method. Then, as an exploratory attempt, an LSTM network is used to rectify the predicted spectral deviation caused by the over-simplification and parameter errors of the dynamic models. From the inputs of simulated spectral sequences of the several components, the LSTM successfully predicts the spectral sequence of the observation. Finally, by the overlapping weighted average, the power spectral density of the planetary system is estimated through the Welch method. The effectiveness and superiority of the proposed method are verified via the experimental data of a planetary gearbox test rig.

IFRS and Investors’ Trading Pattern: A Conceptual Framework

Research aim: The purpose of this study is to provide a conceptual model that guides in examining the capital market effects of IFRS adoption from the perspective of investors’ trading patterns, particularly those behaviors that tend to defy the validity of EMH, in this context; herding behavior. Design/ Methodology/ Approach: The study is conceptual in nature. It relies on a review of the prior academic literature on economic and informational consequences of IFRS adoption published in prominent academic journals. Research findings: The study finds that despite an enormous amount of research thus far, in this area, substantive empirical evidence on economic and informational consequences of IFRS adoption appears to be far from reach. So far, many questions surrounding the capital market effect of IFRS adoption are yet to be fully resolved. More specifically, it is noted that one of the relatively under-researched areas in the current literature is the nexus between IFRS and investors’ trading behaviors. Theoretical contribution/ Originality: To the researchers’ knowledge, this study is first to explicitly explore the nexus between IFRS and investors’ herding practices, while highlighting the role of the national economic culture. Practitioner/ Policy implication: The results of this study are expected to be of interest to academics, regulators, and policymakers in performing a cost-benefit analysis of this planetary set of reporting benchmark, and to the investing public and other market participants who trade based on market fundamentals, treating them as principal indicators for future market movements. Research limitation/ Implication: The study suggests the use of national economic culture to moderate the effect of IFRS on investors’ trading behavior. Nonetheless, this does not imply that there are no other significant factors or even more significant than culture but based on evidence documented in the prior studies there is no support for the contention that national economic culture is inconsequential. Keyword: IFRS Adoption, Herding, National Economic Culture Type of manuscript: Conceptual paper JEL Classification: G14, G15, M41

Influence of Time-varying Mesh Stiffness Excitation on Vibration of Planetary Automatic Transmission

Based on the energy method, the time-varying mesh stiffness models of the internal and external meshing of the planetary gears are established. The translationrotation coupled dynamics differential equation of the planetary transmission system is established through the concentrated mass method. Analyze the influence of time-varying mesh stiffness excitation on the vibration of planetary gear transmission. The results show that the vibration response of the planetary gear sets is mainly related to the connection form under the excitation of the time-varying mesh stiffness. The time-varying mesh stiffness has the greatest influence on the vibration of the planet gear. The vibration of the planet gear is obviously more serious than the other components of the same planetary. When multiple planetary gear sets are connected, the vibration of the output component is smaller than the other components. Moreover the vibration of the input planetary set is generally greater than the rear planetary set except the planet gear.

Ideas for Testing of Planetary Gear Sets of Automotive Transmissions

Abstract The article describes the concept of modular stand, where is possible to provide tests of gear pairs with fixed axes from mechanical automotive gearboxes, as well as tests of separate planetary sets from automatic gearboxes. Special attention in the article will be paid to the variant dedicated for testing of planetary gear sets. This variant is particularly interesting because: 1) it is rarely described in the literature, and 2) this topology allows big simplification with respect to testing of standard gearwheels. In the planetary closed-loop stand it is possible to directly link two identical planetary sets. Without any bracing flange or other connecting clutches, shafts or gear sets, just two planetary sets face-to-face will be assembled and connected to the electric motor.

Performance Analysis of a Hybrid Power Cutting System for Roadheader

An electrohydraulic hybrid power cutting transmission system for roadheader under specific working condition was proposed in this paper. The overall model for the new system composed of an electric motor model, a hydraulic pump-motor model, a torsional planetary set model, and a hybrid power train model was established. The working mode characteristics were simulated under the conditions of taking the effect of cutting picks into account. The advantages of new hybrid power cutting system about the dynamic response under shock load were investigated compared with the traditional cutting system. The results illustrated that the hybrid power system had an obvious cushioning in terms of the dynamic load of cutting electric motor and planetary gear set. Besides, the hydraulic motor could provide an auxiliary power to improve the performance of the electric motor. With further analysis, a dynamic load was found to have a high relation to the stiffness and damping of coupling in the transmission train. The results could be a useful guide for the design of cutting transmission of roadheader.

Non-Linear Vibration of Planetary Set with Flexible Supports of Sun and Ring Gears

Non-Linear Vibration of Planetary Set with Flexible Supports of Sun and Ring Gears

The principles of selecting floating members of 2K-H planetary gears for load balancing design

This paper studies the load balancing problems caused by manufacturing and assembly errors of 2K-H planetary gear train. Based on the geometric equivalent relationship and spring mechanical model of load transfer, the relations between the load balancing of planetary gears and the mesh clearance and meshing stiffness are derived. Besides, the vector method is also derived to calculate the meshing clearance which is a result of the deviation of the component center caused by manufacturing errors and assembly errors. On the basis of the meshing clearance calculation formulas, the balanced load structure based on floating members is analyzed, and the results show: 1) when the number of planet gears is [Formula: see text], the floating of the basic members can compensate for the errors of the planet wheels; 2) when the number of planet gears is [Formula: see text], the errors of the planet wheels cannot be compensated by floating the basic components, and the compensation can only be made through the floating of the planetary gear. In addition, a number of recommendations are proposed to improve the performance of the planetary gear train set.

ステップドピニオン式遊星歯車装置の振動挙動

It is well known that the characteristics of exiting force of planetary gear mesh are varied with gear mesh phase between pinions in single pinion type planetary gear set and that the sideband phenomenon occurs in the sequentially phased planetary gear set. This sideband phenomenon is one in which the (Z-1) or (Z+1) order component level is higher than the mesh order (Z) component level. The notation (Z-1) or (Z+1) means the mesh order (Z) minus or plus one carrier revolution. In this study, the relationship between gear mesh phase and vibration behavior is investigated in the stepped pinion type planetary gear set which has two mesh order component and is operated at wide frequency range. The formulae of mesh force of 6 degrees of freedom acting in sun gear, carrier and ring gear respectively are derived for stepped type planetary gear set. From the experimental and calculated results, the same side band phenomena were also observed in the stepped type planetary set. By taking into account the side band order component of gear mesh, it was revealed that the influence of gear mesh phase on the characteristics of unit case vibration is varied by frequency range. It is considered that the dominant direction component of exiting force for the case vibration of applied unit moves from transverse direction at low- frequency range to rotation direction at high-frequency range.

Simulating the Torque and Angular Speed Distribution within a Heavy Vehicle’s Planetary Gearbox

Simulating the real-time working of a system a complex challenge that had been developed lately within almost all fields of activity, of course including mechanical engineering as well. If one wants to reveal the torque and angular speed distribution onto the elements of a planetary gearbox, issuing a virtual model was previously needed. This model should replicate both the physical structure and the real working behavior.The modeled and simulated gearbox is a planetary type one. The power flows along the gearbox throughout three simple planetary mechanisms (sun gear and crown type) by successively locking different components with the aid of some multi-plate clutches (acting as locking clutches or brakes). The simulation of the friction element’s engagement is achieved by introducing a physical signal that replaces the pressure of the hydraulic command system. We mention that the pressure evolution has been previously experimentally determined, in order to model the force that acts on the actuator’s piston that, at its turn, presses the plates.The paper reveals the working cycles of the friction elements as well as the working modes of the planetary sets. It also reveals the time histories of the power flowing throughout the gearbox. The friction elements are modeled considering their three working stages: fully disengaged, partially engaged and fully engaged. The planetary sets are modeled starting from Willis equation for the speed distribution. For the torque distribution we used the energy conservation law as well as the torque balance law.Should be also mentioned that the virtual simulating model took into account the effects of the twisting vibrations, spinning inertia of the mechanical components and shafts’ elasticity.

Study of Stress Sources and Critical Stress Combinations for the Input Shaft of a Longitudinally Mounted Four Speed Automotive Automatic Transmission Model

In the present paper; two models of the input shaft for a Longitudinal Mounted four Speed Automotive Automatic Transmission for the first time were introduced to describe the input shaft critical loads. In the first model; the DC (Direct Clutch) connects two gears together. This gives no change in the set torque (the set output torque equal to the set input torque). In the second model; the ODB (Over Drive Brake) fixes one element of the planetary set. This is resulting, the gear set gives reduction ratio (the set output torque is not equal to the set input torque). So, the transmission input shaft is worked under two different working operating conditions of torque. Also, it is loaded by a two vertical loads which are coming from the turbine and planetary set loads respectively. They are shown that there are three critical combinations of forces (contact force, shear force, and normal force) applied on the input shaft. The critical forces can be possibility exist three types of cracks for the input shaft cross section they are: transverse (torsion stress), longitudinal (bending stress), and vertical (shear stress). The three cracks are studied in this article. The article considers three stress factors: shearing torsion stress, shear stress, and bending stress.

Advanced Power Transmission System

Different researches are adopted to modify and enhance automatic transmission by every means. Whereas, torque converter that represents the most important component in such transmission suffers from some problems that are not completely solved. In this paper, power transmission system is herein introduced as a unique power transmission system that is not affected by torque converter problems. This power transmission operates with power splitting concept and is composed of conventional torque converter connected to planetary sets. Three clutches are used to shift the operating modes and unique positive displacement hydraulic couplings are utilized to regulate performance in power paths. Also, a modified model used to predict torque converter performance is utilized with planetary gear kinetics to assess the transmission performance. Moreover, the present system operates with high performance. Unlike the automatic transmission that operates in line, the present system operates with infinity number of operational bands for each engine speed.

Sources of time‐varying contact stress and misalignments in wind turbine planetary sets

AbstractRecent data shows that 90% of large wind turbines include a gearbox, and industry forecasts expect this figure to remain relatively stable. With global annual volumes (2009) of around 18,600 units, the quality, cost and performance of gearboxes is of paramount importance to the wind sector. The industry has been focusing some attention on gearbox reliability, as demonstrated by a growth in the number of specific seminars and collaborative programs on this topic. One aspect that needs to be brought to an industry‐wide forum is the understanding of the complexity of bearing design in the gearbox and the careful attention that needs to be paid to ensure a reliable gearbox design. This paper seeks to address this issue by clear demonstration of design issues using a model of the gearbox from the National Renewable Energy Lab's Gearbox Reliability Collaborative. Detailed models are presented with focus on determining the quality of the function of the planetary gear stages. Key design drivers are discussed such as the quality of alignment at the gears and bearings and the loads and stresses seen on these components. Under a design load case with a significant rotor off‐axis moment the stresses in the planet gears and bearings are investigated. It is shown how the misalignment of the planet pins varies with the rotation of the planetary set and how subsequently time‐varying contact stresses and load distributions occur in the planet gears and bearings. These factors strongly influence the fatigue life of the gearbox components as well as the level of vibration. Design tools are then used to demonstrate how small variations in the clearances of the planet carrier bearings can have a big effect on the quality of the design. Numerical studies show where optimal clearance settings lie and how the misalignment of the planetary set can be improved. Furthermore, a demonstration is made of how redesign of the bearing arrangement and subsequent optimization of the planet tooth geometry further improves the misalignment and results in significantly reduced time‐varying contact stresses, better load distribution and reduced vibration. It is illustrated that small clearances, such as in the carrier bearings, can have a large effect on the performance of the design and a study shows how to identify and reduce time‐varying misalignment and contact stresses resulting in lower vibration, lower fatigue and a more reliable product. Copyright © 2011 John Wiley & Sons, Ltd.

Dual-Mode Power-Split Transmission for Hybrid Electric Vehicles

In this paper, an innovative power-split device (PSD) is introduced, and its application in a hybrid powertrain system is studied. The new PSD is a mechanism that allows operation in two different power-split modes through locking/unlocking of two clutches. In one mode, the PSD operates similar to a standard planetary gear unit, and in the other mode, it works the same as a compound planetary set. A well-known analogous system is the Toyota Hybrid System (THS) and is used for comparison purposes. It is demonstrated that by the new system, the transmission losses are reduced by a considerable extent, and thus, the efficiency is improved. A controller is designed based on fuzzy logic, which receives the battery state of charge (SOC), the vehicle speed, and the power that is requested at the wheels to coordinate each component in such a way as to optimize the entire system efficiency. A numerical optimization algorithm is applied to sustain the SOC in high regions and shift engine operating points to higher efficiency regions. Simulation results demonstrate notable improvements in fuel economy and performance characteristics.

Analysis of Nonlinear Characteristics of Double-Crank Ring-Plate-Typed Pin-Cycloid Gear Planetary Drive

Double-crank ring-plate-typed pin-cycloid gear planetary drive conquers shortcomings of a traditional pin-cycloid gear planetary drive, whose load-capacity is restricted by rotation-arm bearing dimension. The load-capacity of this kind of new drive is improved greatly and the efficiency of whole machine is 94%. In order to know dynamics reliability of this drive , nonlinear characteristics of double-crank ring-plate-typed pin-cycloid gear planetary drive are analyzed from two sides of transmission error and dynamic meshing process in this paper. A sensitive analytic mathematic model of rod dimension error is set up by kinematics theory. Based on ring-plate-type cycloid drive dynamic meshing characteristics, a rigidity-flexibility combined model of pin-cycloid planetary drive is set up by ANSYS/LS-DYNA module. Meshing process between pin-cycloid gear is simulated by FEM. Instantaneous stress, distortion and dynamic meshing rigidity are computed. Analytical results show that nonlinear meshing rigidity and transmission errors are two main dynamic exciters which cause prototype to vibrate. So, rod dimension error should be reduced in order to increase meshing accuracy, and meshing rigidity of new prototype should be increased in order to reduce vibration. Nonlinear characteristics of the drive can offer some theoretical bases for design of new prototype.

A non-linear dynamic model for planetary gear sets

A discrete non-linear torsional vibration model of a single-stage planetary set is proposed in the current study. The model includes all possible power flow configurations, any number of planets in any spacing arrangement and any planet mesh phasing configurations. It also includes time variation of gear mesh stiffnesses as well as clearance (backlash) non-linearities. The non-linear equations of motion are solved semi-analytically using multi-term harmonic balance method (HBM) in conjunction with inverse discrete Fourier transform and Newton-Rapson method. The HBM solutions are compared with numerical simulation results to demonstrate the accuracy of the HBM formulation. Another comparison with predictions of a deformable-body dynamic model is also provided to assess the accuracy of the discrete model. Limited parametric studies are presented at the end, to show the influence of key gear design parameters on dynamic response.

Separation with Multi-Layer Coil Counter-Current Chromatography (MLCCC)

Counter-current chromatography (CCC) is a low-pressure, all-liquid chromatographic technique which requires no solid support. [ 1 ] Commonly it utilizes two immiscible solvent phases plus an auxiliary solvent which is miscible in both phases. The mobile phase is pumped through the stationary phase, causing the compounds to partition between two immiscible solvents, based on the partition coefficients of the solutes. MLCCC is an advanced form of CCC and employs teflon tubing wound onto a bobbin, which is centrifugally rotated in a planetary fashion [ 2 ] (Fig. 1). The planetary motion sets up alternating zones of mixing and settling which travel along the length of the coil and result in the partitioning of the components. The main advantages of CCC over conventional chromatography techniques are the absence of a solid support, the use of inexpensive solvents, and complete recovery of highly functional and reactive compounds. In contrast to other forms of CCC, MLCCC can be used on both an analytical and preparative scale. Due to high centrifugal forces, an increase in the number oftheoretical plates is achieved, thereby allowing up to 50000 mixing zones to occur per hour. This results in efficient partitioning and separation of the components in a complex mixture. Hence MLCCC is beginning to be more widely accepted as a method of choice for the separation and isolation of highly polar natural products.