An Experimental Investigation of the Efficiency of Planetary Gear Sets

2011 ◽  
Author(s):  
David C. Talbot ◽  
Ahmet Kahraman ◽  
Avinash Singh
Keyword(s):  
Power Loss ◽  
Planetary Gear ◽  
Mechanical Power ◽  
Tooth Surface ◽  
Inlet Temperature ◽  
Test Apparatus ◽  
Power Losses ◽  
Test Matrix ◽  
Planetary Gear Sets ◽  
Set Up

In this paper, results from an experimental study on power losses of planetary gear sets are presented. The experimental set-up includes a specialized test apparatus to operate a planetary gear set under tightly-controlled speed, load and oil temperature conditions, and instrumentation for an accurate measurement of power losses. The test matrix consisted of gear sets having 3 to 6 planets under loaded and unloaded conditions in order to separate load independent (spin) and load dependent (mechanical) power losses. The test matrix also included tests with planet gears having two levels of tooth surface roughness amplitudes as well as tests at varying oil inlet temperature. The results clearly indicate that spin power loss decreases with both reduction of number of planets and increase in oil temperature. Meanwhile, the mechanical power loss decreases with a decrease in oil temperature and reduction in gear surface roughnesses. Results also indicate that mechanical losses can be described by the power transmitted and lost by each planet branch.

An Experimental Investigation of the Efficiency of Planetary Gear Sets

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
David C. Talbot ◽  
Ahmet Kahraman ◽  
Avinash Singh
Keyword(s):  
Power Loss ◽  
Planetary Gear ◽  
Mechanical Power ◽  
Tooth Surface ◽  
Inlet Temperature ◽  
Experimental Setup ◽  
Test Apparatus ◽  
Power Losses ◽  
Test Matrix ◽  
Planetary Gear Sets

In this paper, results from an experimental study on power losses of planetary gear sets are presented. The experimental setup includes a specialized test apparatus to operate a planetary gear set under tightly controlled speed, load and oil temperature conditions, and instrumentation for an accurate measurement of power losses. The test matrix consisted of gear sets having three–six planets under loaded and unloaded conditions in order to separate load independent (spin) and load dependent (mechanical) power losses. The test matrix also included tests with planet gears having two levels of tooth surface roughness amplitudes as well as tests at varying oil inlet temperature. The results clearly indicate that spin power loss decreases with both reduction of number of planets and increase in oil temperature. Meanwhile, the mechanical power loss decreases with a decrease in oil temperature and reduction in gear surface roughnesses. Results also indicate that mechanical losses can be described by the power transmitted and lost by each planet branch.

Analysis on Transmission Efficiency of Planetary Gear Reducer

2014 ◽  
Vol 703 ◽  
pp. 413-416
Author(s):  
Bin Wang ◽  
Xian Xian Wang ◽  
Ping Wang
Keyword(s):  
Rotational Speed ◽  
Power Loss ◽  
Planetary Gear ◽  
Transmission Efficiency ◽  
Calculation Model ◽  
Mechanical Power ◽  
Power Losses ◽  
Efficiency Calculation

A transmission efficiency calculation model of planetary geared reducer was proposed in this paper. The power losses of meshed surfaces of sun-planet gears and planet-ring gears were analyzed in detail. Finally, the mechanical power losses and transmission efficiency of the planetary gear reducer were simulated to illustrate the influence of rotational speed and torque on mechanical power loss and transmission efficiency.

scholarly journals Investigation of the Influences of Thrust Loads Resulted by Helix Angle Directions of Planetary Gear Sets on Bearing Power Losses in Automotive Planetary Gear Trains

2021 ◽  
Vol 11 (19) ◽  
pp. 8827
Author(s):  
Hyun Sik Kwon
Keyword(s):  
Power Loss ◽  
Fuel Efficiency ◽  
Automatic Transmission ◽  
Reducing Power ◽  
Planetary Gear ◽  
Helix Angle ◽  
Transmission Model ◽  
Power Losses ◽  
Loss Analysis ◽  
Planetary Gear Sets

In the recent automotive industries, automotive technologies for improving fuel efficiency have focused on the developments of reducing power losses in a transmission. As a well-developed and conventional power transmitting system, an automatic transmission is still widely used in many automotive vehicles. The automatic transmission is co-axially designed with several planetary gear sets and other mechanical parts. The co-axial arrangements and gear helix angles make the transmission necessarily include bearings for supporting loads and allowing relative rotations. In this study, the influences of thrust loads yielded by helix angle directions of planetary gear sets on bearing power losses are presented by performing the structural and power loss analysis. Bearing power losses consist of mechanical and spin power losses. For calculating thrust loads and bearing rotations, a complete transmission model is constructed by using an example structure, and structural analysis is performed for the combinations of helix angle directions of the gear sets. Finally, bearing power losses are computed by using the bearing power loss model, and the results of the entire combinations of helix angle directions are discussed.

Mechanical power losses of full-complement needle bearings of planetary gear sets: Model and experiments

2015 ◽  
Vol 230 (5) ◽  
pp. 839-855 ◽  
Author(s):  
D Talbot ◽  
A Kahraman ◽  
AW Stilwell ◽  
A Singh ◽  
I Napau
Keyword(s):  
Power Loss ◽  
Elastohydrodynamic Lubrication ◽  
Planetary Gear ◽  
Mechanical Power ◽  
Experimental Investigations ◽  
Power Losses ◽  
Double Row ◽  
Baseline Design ◽  
Full Complement ◽  
Needle Diameter

Full-complement (loose) needle bearings are used widely in automatic transmissions as planetary gear set planet bearings due to their cost advantages and high load-carrying capacity. This study provides theoretical and experimental investigations of the efficiency performance of full-complement needle bearings in a planetary gear set. An experimental setup is introduced to measure planetary gear set power losses. A number of full-complement needle bearing variations as well as a baseline caged needle bearing arrangement are tested within ranges of speed, torque, and oil temperature as well as key bearing parameters such as needle diameter and number of needle rows. A mechanical power loss model of full-complement needle bearings is proposed next. The model employs an elastohydrodynamic lubrication formulation for rolling power losses and includes the effects of needle skewing and needle-to-needle sliding. Predicted mechanical power losses are compared to measurements to assess the accuracy of the model. Results indicate that (i) full-complement needle bearings are consistently less efficient than the corresponding caged-needle baseline design, and (ii) double-row bearings have higher efficiency than their single-row counterparts, while the influence of the needle diameter on power loss is somewhat secondary.

Mechanical Power Losses of Ball Bearings: Model and Experimental Validation

2021 ◽  
pp. 1-29
Author(s):  
Ahmet Dindar ◽  
Amit Chimanpure ◽  
Ahmet Kahraman
Keyword(s):  
Dynamic Model ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Mechanical Power ◽  
Ball Bearings ◽  
Power Losses ◽  
Euler Parameters ◽  
Surface Shear ◽  
Axial Forces ◽  
Set Up

Abstract A tribo-dynamic model of ball bearings is proposed to predict their load-dependent (mechanical) power losses. The model combines (i) a transient, point contact mixed elastohydrodynamic lubrication (EHL) formulation to simulate the mechanics of the load carrying lubricated ball-race interfaces, and (ii) a singularity-free dynamics model, and establishes the two-way coupling between them that dictates power losses. The dynamic model employs a vectoral formulation with Euler parameters. The EHL model is capable of capturing two-dimensional contact kinematics, velocity variations across the contact as well as asperity interactions of rough contact surfaces. Resultant contact surface shear distributions are processed to predict mechanical power losses of example ball bearings operating under combined radial and axial forces. An experimental set-up is introduced for measurement of the power losses of rolling-element bearings. Sets of measurements taken by using the same example ball bearings are compared to those predicted by the model to assess its accuracy in predicting mechanical power loss of a ball bearing within wide ranges of axial and radial forces.

Future Transmissions for Wind Turbines

2011 ◽  
Vol 86 ◽  
pp. 18-25 ◽  
Author(s):  
Bernd Robert Höhn
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Planetary Gear ◽  
Transmission Ratio ◽  
Constant Ratio ◽  
Constant Frequency ◽  
Planetary Gear Sets ◽  
Set Up ◽  
Electric Engine

Most transmissions for wind turbines are set up by multiple consecutively arranged planetary gear sets and/or normal gear sets. Therefore these transmissions have a constant ratio. In order to feed the electricity produced by the wind turbines into the grid, an electric conversion to a constant frequency of 50 Hz is necessary. FZG developed a new concept for transmissions of wind turbines based on a planetary gear. By superposition of a small electric engine the transmission ratio is continuously variable. This makes an electric conversion unnecessary and thereby increases the efficiency of the wind turbine.

Prediction of Mechanical Power Loss of Planet Gear Roller Bearings Under Combined Radial and Moment Loading

2013 ◽  
Vol 135 (12) ◽  
Author(s):  
D. Talbot ◽  
S. Li ◽  
A. Kahraman
Keyword(s):  
Load Distribution ◽  
Power Loss ◽  
Elastohydrodynamic Lubrication ◽  
Planetary Gear ◽  
Mechanical Power ◽  
Distribution Model ◽  
Roller Bearings ◽  
Modeling Methodology ◽  
Force Moment ◽  
Planet Gear

A modeling methodology is proposed to predict load-dependent (mechanical) power loss of cylindrical roller bearings under combined radial and moment loading with focus on planetary gear set planet bearings. This methodology relies on two models. The first model is a bearing load distribution model to predict load intensities along rolling element contacts due to combined force–moment loading. This model takes into account planet bearing macrogeometry as well as micromodifications to the roller and race surfaces. The second model is an elastohydrodynamic lubrication (EHL) model employed to predict rolling power losses of bearing contacts with load intensities predicted by the load distribution model. The bearing mechanical power loss methodology is applied to bearings of an automotive planetary gear set to quantify the sensitivity of mechanical power loss to key bearing, lubrication and surface parameters as well as operating speed, load and temperature conditions.

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