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.

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.

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.

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.

scholarly journals Effect of roughness on meshing power loss of planetary gear set considering elasto-hydrodynamic lubrication

2020 ◽  
Vol 12 (2) ◽  
pp. 168781402090842
Author(s):  
Xinlei Wang ◽  
Changle Xiang ◽  
Chunming Li ◽  
Shenlong Li ◽  
Yimin Shao ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Dynamic Model ◽  
Friction Force ◽  
Power Loss ◽  
Hydrodynamic Lubrication ◽  
Planetary Gear ◽  
Tooth Surface ◽  
Gear Pair ◽  
Surface Geometry ◽  
Loss Calculation

Meshing power loss is one of the most important parts in power loss calculation of planetary gear set. However, most of the conventional methods assumed the friction coefficient between gears as a constant value in the meshing power loss calculation, and most importantly, the influence of gear tooth surface geometry is usually ignored, for example, roughness. Therefore, a new meshing power loss calculation model for planetary gear set that considers tooth surface roughness is proposed on the basis of elasto-hydrodynamic lubrication method. With the proposed model, a planetary gear set dynamic model that considers friction force between gears is first established to study the time-varying meshing forces, sliding speeds, and curvature radii of the gear pairs. Then, an elasto-hydrodynamic lubrication model of the gear pair contact interface is constructed to investigate and modify the friction force distribution in the gear meshing process of the dynamic model iteratively until the meshing forces converge to stable values. Furthermore, the relationship between the tooth surface roughness and film thickness is studied in the elasto-hydrodynamic lubrication model. After that, the meshing power loss is calculated based on the obtained meshing forces, friction coefficients, sliding speeds, and so on. The results show that there is a sudden growth of the meshing power loss at the end of the meshing cycle, which has a good agreement with the meshing force impact. And, it is found that tooth surface roughness has a direct influence on the meshing power loss of sun–planet gear pair, which yields an increasing tendency as the surface roughness growing.

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