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.

Internal Gear Strains and Load Sharing in Planetary Transmissions: Model and Experiments

2007 ◽  
Author(s):  
Avinash Singh ◽  
Ahmet Kahraman ◽  
Haris Ligata
Keyword(s):  
System Analysis ◽  
Gear Tooth ◽  
Planetary Gear ◽  
Load Sharing ◽  
Companion Paper ◽  
System Level ◽  
Outer Diameter ◽  
Ring Gear ◽  
Analysis Model ◽  
Position Errors

This paper presents results of a comprehensive experimental and theoretical study to determine the influence of certain key factors in planetary transmissions on gear stresses and planetary load sharing. A series of tests are conducted on a family of planetary gear sets, and strains are recorded at various locations on the outer diameter and gear tooth fillet of the ring gear. Pinion position errors are introduced as a representative key manufacturing tolerance, and the resultant changes in the planetary behavior are observed. The experimental data is compared to the predictions of a state-of-the-art multi-body contact analysis model — ‘Gear System Analysis Modules’ (GSAM). This model is capable of including the influences of a number of system-level variables and quantifying their impact on gear strains. The model predictions are shown to compare well with the measured strain at the ring gear outer diameter and tooth fillet. GSAM predictions of planet load sharing are then used to quantify the influence of pin hole position errors on the 3, 4, 5, and 6 planet test gear sets. These predictions also agree well with the planet load sharing experiments presented in a companion paper [20].

Internal Gear Strains and Load Sharing in Planetary Transmissions: Model and Experiments

2008 ◽  
Vol 130 (7) ◽  
Author(s):  
Avinash Singh ◽  
Ahmet Kahraman ◽  
Haris Ligata
Keyword(s):  
System Analysis ◽  
Gear Tooth ◽  
Planetary Gear ◽  
Load Sharing ◽  
Companion Paper ◽  
System Level ◽  
Outer Diameter ◽  
Ring Gear ◽  
Analysis Model ◽  
Position Errors

This paper presents results of a comprehensive experimental and theoretical study to determine the influence of certain key factors in planetary transmissions on gear stresses and planetary load sharing. A series of tests are conducted on a family of planetary gear sets, and strains are recorded at various locations on the outer diameter and gear tooth fillet of the ring gear. Pinion position errors are introduced as a representative key manufacturing tolerance, and the resultant changes in the planetary behavior are observed. The experimental data are compared to the predictions of a state-of-the-art multibody contact analysis model—Gear System Analysis Modules (GSAM). This model is capable of including the influences of a number of system-level variables and quantifying their impact on gear strains. The model predictions are shown to compare well with the measured strain at the ring gear outer diameter and tooth fillet. GSAM predictions of planet load sharing are then used to quantify the influence of tangential pinhole position errors on three-, four-, five-, and six-planet test gear sets. These predictions also agree well with the planet load sharing experiments presented in a companion paper.

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.

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.

Influence of the Carrier Pinhole Position Errors on the Load Sharing of a Planetary Gear Train

2018 ◽  
Vol 19 (4) ◽  
pp. 537-543 ◽  
Author(s):  
Jeong-Gil Kim ◽  
Young-Jun Park ◽  
Sang-Dae Lee ◽  
Joo-young Oh ◽  
Jae-Hoon Kim ◽  
...  
Keyword(s):  
Planetary Gear ◽  
Load Sharing ◽  
Gear Train ◽  
Planetary Gear Train ◽  
Position Errors

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.

Influence of Ring Gear Rim Thickness on Planetary Gear Set Behavior

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
A. Kahraman ◽  
H. Ligata ◽  
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. The 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 pinhole 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 quasistatic deformable-body models of the test planetary gear sets is developed to simulate the experiments. The predictions and measurements are compared with the assessment of the accuracy of the models within wide ranges of parameters. The 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.

scholarly journals Reducing mass while improving the operational behavior: form optimization of planetary gearbox housings

2021 ◽  
Author(s):  
Julian Theling ◽  
Jens Brimmers ◽  
Christian Brecher
Keyword(s):  
Planetary Gear ◽  
Load Sharing ◽  
Structural Elements ◽  
Structural Vibrations ◽  
Tooth Contact Analysis ◽  
Balanced Design ◽  
Planetary Gearbox ◽  
Gear Mesh ◽  
Low Mass ◽  
The Individual

AbstractThe optimization of load sharing between planets is one of the most important goals in planetary gearbox design. Unevenly distributed load will cause locally higher flank pressures and therefore, less durability of gears and bearings. Furthermore, unevenly distributed or fluctuating loads can cause excitations in the gear mesh and structural vibrations. The load sharing in planetary gear stages depends on the individual stiffness conditions in each mesh position. The stiffness is not only influenced by the gear geometry but also by the surrounding structural elements like shafts, housings and torque arms. In wind industry these components are often designed very stiff in order to reduce their effect on the operational behavior.Within this paper, a method is presented, which allows combining the structural optimization process with a tooth contact analysis for planetary gearboxes. By means of this combined approach, it is possible to optimize the housing structure of the ring gear in terms of mass reduction while keeping the operational behavior in focus. With a weighted design objective function, it is possible to decide whether the main objective should be load distribution, excitation behavior, low mass or a balanced design.

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