Research on Efficiency and Load Sharing Characteristics of High-Speed-Ratio Planetary Gear Transmissions

2015 ◽  
Author(s):  
Jianbin Liang ◽  
Datong Qin ◽  
Wei Wen ◽  
Jun Jiang
Keyword(s):  
High Speed ◽  
Planetary Gear ◽  
Load Sharing ◽  
Speed Ratio ◽  
Contact Ratio ◽  
Low Loss ◽  
Position Errors ◽  
Manufacturing Errors ◽  
Profile Errors ◽  
Tooth Profile Errors

Wolfrom planetary gear (WPG), James Ferguson planetary gear (JFPG) and plus-planetary gear (PPG), feature high speed ratios and a low number of gears, but their efficiency is low and their performance is sensitive to manufacturing errors. In this paper, low-loss gears are used to improve the efficiency of these high-speed-ratio planetary gear transmissions. The methods to achieve the low-loss gears are optimizing modification coefficients and addendum coefficients simultaneously in order to equalize approach-contact ratio and recess-contact ratio. Besides, the sensitivity of the load sharing performance to manufacturing errors is analyzed in the view of load sharing characteristics. A load sharing model, which includes position errors of planet bearings and tooth profile errors of planets, is built up to obtain the load sharing characteristics of WPG, JFPG and PPG. Load sharing performance of WPG, JFPG and PPG with manufacturing errors are analyzed. And effects of load sharing measures are compared.

A Three-Dimensional Load Sharing Model of Planetary Gear Sets Having Manufacturing Errors

2015 ◽  
Author(s):  
Nicholas D. Leque ◽  
Ahmet Kahraman
Keyword(s):  
Three Dimensional ◽  
Planetary Gear ◽  
Load Sharing ◽  
Distribution Model ◽  
Gear Mesh ◽  
Position Errors ◽  
Proposed Model ◽  
Manufacturing Errors ◽  
Manufacturing Tolerancing ◽  
Planetary Gear Sets

Planet-to-planet load sharing is a major design and manufacturing tolerancing issue in planetary gear sets. Planetary gear sets are advantageous over their countershaft alternatives in many aspects, provided that each planet branch carries a reasonable, preferably equal, share of the torque transmitted. In practice, the load shared among the planets is typically not equal due to the presence of various manufacturing errors. This study aims at enhancing the models for planet load sharing through a three-dimensional formulation of N-planet helical planetary gear sets. Apart from previous models, the proposed model employs a gear mesh load distribution model to capture load and time dependency of the gear meshes iteratively. It includes all three types of manufacturing errors, namely constant errors such as planet pinhole position errors and pinhole diameter errors, constant but assembly dependent errors such as nominal planet tooth thickness errors, planet bore diameter errors, and rotation and assembly dependent errors such as gear eccentricities and run-outs. At the end, the model is used to show combined influence of these errors on planet load sharing to aid designers on how to account for manufacturing tolerances in the design of the gears of a planetary gear set.

An Experimental Study of the Influence of Manufacturing Errors on the Planetary Gear Stresses and Planet Load Sharing

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
H. Ligata ◽  
A. Kahraman ◽  
A. Singh
Keyword(s):  
Experimental Study ◽  
Planetary Gear ◽  
Load Sharing ◽  
Position Errors ◽  
Manufacturing Errors ◽  
Time Histories ◽  
Analysis System ◽  
The Individual ◽  
Torque Values ◽  
The Impact

In this paper, results of an experimental study are presented to describe the impact of certain types of manufacturing errors on gear stresses and the individual planet loads of an n-planet planetary gear set (n=3–6). The experimental setup includes a specialized test apparatus to operate a planetary gear set under typical speed and load conditions and gear sets having tightly controlled intentional manufacturing errors. The instrumentation system consists of multiple strain gauges mounted on the ring gear and a multichannel data collection and analysis system. A method for computing the planet load-sharing factors from root strain-time histories is proposed. Influence of carrier pinhole position errors on gear root stresses is quantified for various error and torque values applied to gear sets having three to six planets. The results clearly indicate that manufacturing errors influence gear stresses and planet load sharing significantly. Gear sets having larger number of planets are more sensitive to manufacturing errors in terms of planet load-sharing behavior.

scholarly journals Investigation of Dynamic Load Sharing Behavior for Herringbone Planetary Gears considering Multicoupling Manufacturing Errors

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Fei Ren ◽  
Jinchen Ji ◽  
Guofu Luo ◽  
Shaofu Zhao ◽  
Liya Zhao ◽  
...  
Keyword(s):  
Planetary Gear ◽  
Load Sharing ◽  
Gear Train ◽  
Actual Structure ◽  
Lumped Parameter ◽  
Manufacturing Errors ◽  
Main Components ◽  
Gyroscopic Effects ◽  
Profile Errors ◽  
Sharing Behavior

In this study, based on the lumped-parameter theory and the Lagrange approach, a novel and generalized bending-torsional-axial coupled dynamic model for analyzing the load sharing behavior in the herringbone planetary gear train (HPGT) is presented by taking into account the actual structure of herringbone gears, manufacturing errors, time-dependent meshing stiffness, bearing deflections, and gyroscopic effects. The model can be applied to the analysis of the vibration of the HPGT with any number of planets and different types of manufacturing errors in different floating forms. The HPGT equivalent meshing error is analyzed and derived for the tooth profile errors and manufacturing eccentric errors of all components in the HPGT system. By employing the variable-step Runge–Kutta approach to calculate the system dynamic response, in conjunction with the presented calculation approach of the HPGT load sharing coefficient, the relationships among manufacturing errors, component floating, and load sharing are numerically obtained. The effects of the combined errors and single error on the load sharing are, respectively, discussed. Meanwhile, the effects of the support stiffness of the main components in the HPGT system on load sharing behavior are analyzed. The results indicate that manufacturing errors, floating components, and system support stiffness largely influence the load sharing behavior of the HPGT system. The research has a vital guiding significance for the design of the HPGT system.

An Experimental Investigation of the Influence of Manufacturing Errors on the Planetary Gear Stresses and Load Sharing

2007 ◽  
Author(s):  
Haris Ligata ◽  
Ahmet Kahraman ◽  
Avinash Singh
Keyword(s):  
Planetary Gear ◽  
Load Sharing ◽  
Position Errors ◽  
Manufacturing Errors ◽  
Time Histories ◽  
Analysis System ◽  
Set Up ◽  
The Individual ◽  
Torque Values ◽  
The Impact

In this paper, results of an experimental study are presented to describe the impact of certain types of manufacturing errors on gear stresses and the individual planet loads of an n-planet planetary gear set (n = 3 to 6). The experimental set-up includes a specialized test apparatus to operate a planetary gear set under typical speed and load conditions and gear sets having tightly controlled intentional manufacturing errors. The instrumentation system consists of multiple strain gauges mounted on the ring gear and a multi-channel data collection and analysis system. A method for computing the planet load sharing factors from root strain time histories is proposed. Influence of carrier pinhole position errors on gear root stresses are quantified for various error and torque values applied to gear sets having 3 to 6 planets. The results clearly indicate that manufacturing errors influence gear stresses and planet load sharing significantly. Gear sets having larger number of planets are more sensitive to manufacturing errors in terms of planet load sharing behavior.

A Three-Dimensional Load Sharing Model of Planetary Gear Sets Having Manufacturing Errors

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
N. Leque ◽  
A. Kahraman
Keyword(s):  
Three Dimensional ◽  
Planetary Gear ◽  
Load Sharing ◽  
Distribution Model ◽  
Gear Mesh ◽  
Position Errors ◽  
Proposed Model ◽  
Manufacturing Errors ◽  
Manufacturing Tolerancing ◽  
Planetary Gear Sets

Planet-to-planet load sharing is a major design and manufacturing tolerancing issue in planetary gear sets. Planetary gear sets are advantageous over their countershaft alternatives in many aspects, provided that each planet branch carries a reasonable, preferably equal, share of the torque transmitted. In practice, the load shared among the planets is typically not equal due to the presence of various manufacturing errors. This study aims at enhancing the models for planet load sharing through a three-dimensional (3D) formulation of N planet helical planetary gear sets. Apart from previous models, the proposed model employs a gear mesh load distribution model to capture load and time dependency of the gear meshes iteratively. It includes all the three types of manufacturing errors, namely, constant errors such as carrier pinhole position errors and pinhole diameter errors, constant but assembly dependent errors such as nominal planet tooth thickness errors, planet bore diameter errors, and rotation, and assembly dependent errors such as gear eccentricities and run-outs. At the end, the model is used to show combined influence of these errors on planet load sharing to aid designers on how to account for manufacturing tolerances in the design of the gears of a planetary gear set.

scholarly journals Analytical study of floating effects on load sharing characteristics of planetary gearbox for off-road vehicle

2020 ◽  
Vol 12 (7) ◽  
pp. 168781402094046
Author(s):  
Woo-Jin Chung ◽  
Joo-Seon Oh ◽  
Hyun-Woo Han ◽  
Ji-Tae Kim ◽  
Young-Jun Park
Keyword(s):  
Safety Factor ◽  
Planetary Gear ◽  
Load Sharing ◽  
Position Error ◽  
System Level ◽  
Load Factor ◽  
Road Vehicle ◽  
Design Modification ◽  
Planetary Gearbox ◽  
Position Errors

Uneven load sharing of a planetary gear set is the main cause of preventing the miniaturization and weight reduction of a planetary gearbox. Non-torque loads and carrier pinhole position errors are the main factors that worsen the load-sharing characteristics. However, their effects are seldom analyzed at a system level especially for an off-road vehicle. To make up this gap, some simulation models are proposed to investigate the effects of floating members on the load-sharing characteristics and the strength of a planetary gear set with non-torque load and carrier pinhole position error. When the error is not considered, the mesh load factor converges to unity irrespective of the type and number of floating members and the safety factors for pitting and bending are increased slightly. When the carrier pinhole position error is considered, the mesh load factor dramatically worsens. Although it is improved using the floating members, it does not converge to unity. However, the bending safety factor of the planet gear with the error is increased by 26%. This indicates that the design modification for the original planetary gearbox is needed to satisfy the safety factor requirement, but the problem is solved using only floating members.

Influence of Gear Rim Deflections on Planetary Gear Set Behavior

2009 ◽  
Author(s):  
H. Ligata ◽  
A. Kahraman ◽  
A. Singh
Keyword(s):  
Deformable Body ◽  
Planetary Gear ◽  
Load Sharing ◽  
Ring Gear ◽  
Hoop Strain ◽  
Position Errors ◽  
Study Results ◽  
Planetary Gear Sets ◽  
Support Conditions ◽  
Major Factors

In this study, results of an experimental and theoretical study on the influence of rim thickness of the ring gear on rim deflections and stresses, and planet load sharing of a planetary gear set are presented. Experimental study consists of measurement of ring gear deflections and strains for gear sets having various numbers of planets, different ring gear rim thicknesses as well as various carrier pin hole position errors. Root and hoop strain gauges and displacement probes are placed at various locations so that the variations due to external splines of the stationary ring gear can also be quantified. A family of quasi-static deformable-body models of the test gear planetary gear sets is developed to simulate the experiments. The predictions and the measurements are compared to assess the accuracy of the models within wide ranges of parameters. Influence of rim thickness on ring gear stresses and deflections and planet load sharing are quantified together with the interactions between the rim flexibility and the spline conditions. The results from this study confirm that the ring gear deflections and the ring gear support conditions must be included in the design process as one of the major factors.

A Closed-Form Planet Load Sharing Formulation for Planetary Gear Sets Using a Translational Analogy

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
H. Ligata ◽  
A. Kahraman ◽  
A. Singh
Keyword(s):  
Closed Form ◽  
Discrete Model ◽  
Deformable Body ◽  
Planetary Gear ◽  
Load Sharing ◽  
Position Errors ◽  
Model Predictions ◽  
Planetary Gear Sets ◽  
Torsional System

A simplified discrete model to predict load sharing among the planets of a planetary gear set having carrier planet position errors is presented in this study. The model proposes a translational representation of the torsional system and includes any number of planets positioned at any spacing configuration. The discrete model predictions are validated by comparing them to (i) the predictions of a deformable-body planetary gear set model and (ii) planet load sharing measurements from planetary gear sets having three to six planets. A set of closed-form planet load sharing formulas are derived from the discrete model for gear sets having equally-spaced planets for conditions when all of the planets are loaded. These formulas allow, in an accurate and direct way, calculation of planet loads as a function of position errors associated with each planet.

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