Analysis of flow regimes and associated sources of dissipation in splash lubricated planetary gear sets

2021 ◽  
pp. 1-22
Author(s):  
Jean-Baptiste Boni ◽  
Christophe Changenet ◽  
Fabrice Ville
Keyword(s):  
Planetary Gear ◽  
Operating Conditions ◽  
Centrifugal Forces ◽  
Power Losses ◽  
Planetary Gears ◽  
Compact Size ◽  
Depth Analysis ◽  
Planetary Gear Sets ◽  
High Reduction ◽  
Oil Characteristics

Abstract Planetary gears are used in several applications given that they provide high reduction ratio in a compact size. Two kind of lubrication are used in this applications: injection or splash lubrication. In case of splash lubrication, the authors already highlighted the importance of the centrifugal effects leading to the formation of an oil ring inside the reducer, therefore giving a method to compute churning power losses. In this paper, another flow regime is underlined when centrifugal forces are not sufficient to turn the oil sump into a ring. In addition to this observation, an in-depth analysis is given regarding the dependence of the churning power losses with operating conditions and oil characteristics.

An Analytical and Numerical Investigation of Modulation Sidebands of a Planetary Gear Under Fluctuated External Torque

2018 ◽  
Author(s):  
Yunbo Yuan ◽  
Wei Liu ◽  
Yahui Chen ◽  
Donghua Wang
Keyword(s):  
Planetary Gear ◽  
Transmission Error ◽  
Operating Conditions ◽  
Radial Acceleration ◽  
External Torque ◽  
Gear Mesh ◽  
Planetary Gear Sets ◽  
Static Transmission Error ◽  
Frequency Modulations ◽  
Mesh Phasing

Certain operating conditions such as fluctuation of the external torque to planetary gear sets can cause additional sidebands. In this paper, a mathematical model is proposed to investigate the modulation mechanisms due to a fluctuated external torque (FET), and the combined influence of such an external torque and manufacturing errors (ME) on modulation sidebands. Gear mesh interface excitations, namely gear static transmission error excitations and time-varying gear mesh stiffness, are defined in Fourier series forms. Amplitude and frequency modulations are demonstrated separately. The predicted dynamic gear mesh force spectra and radial acceleration spectra at a fixed position on ring gear are both shown to exhibit well-defined modulation sidebands. Comparing with sidebands caused by ME, more complex sidebands appear when taking both FET and ME into account. An obvious intermodulation is found around the fundamental gear mesh frequency between the FET and ME in the form of frequency modulations, however, no intermodulation in the form of amplitude modulations. Additionally, the results indicate that some of the sidebands are cancelled out in radial acceleration spectra mainly due to the effect of planet mesh phasing, especially when only amplitude modulations are present.

On the Design of Planetary Gear Reducer with Simple Planet Gears

2013 ◽  
Vol 284-287 ◽  
pp. 867-871
Author(s):  
Long Chang Hsieh ◽  
Tzu Hsia Chen
Keyword(s):  
Engineering Design ◽  
Planetary Gear ◽  
Reduction Ratio ◽  
Gear Train ◽  
Planetary Gear Train ◽  
Ratio Equation ◽  
Planetary Gear Trains ◽  
Compact Size ◽  
Gear Trains ◽  
High Reduction

Planetary gear trains are commonly used in various transmissions due to the following reasons: compact size, light weight, and multi-degrees of freedom. For example, planetary gear trains can be designed for following functions: gear reducers for power machinery, internal gear hubs for bicycle, gear increasers for wind generator, gear reducers for robot. In general, the reduction of non-coupled planetary gear train is less than 10. The purpose of this paper is to introduce the planetary gear train with high reduction ratio. Coupled planetary gear train can be designed to has high reduction ratio. Hence, this paper focuses on innovative, kinematic, and engineering design of coupled planetary gear train with high reduction ratio. The coupled planetary gear train synthesized in this paper is a planetary gear train with simple planet gears. It can be used as the gear reducer for a robot. Refer to the train value equation, the reduction-ratio equation of coupled planetary gear train is derived for the design purpose. Then, the coupled planetary coupled gear train with simple planet gears is synthesized based on the above reduction-ratio equation. Finally, the corresponding engineering design drawing is accomplished.

scholarly journals Quasi-Static Load Sharing Characteristics of a Planetary Gear Set with Planet Journal Bearings

2020 ◽  
Vol 10 (3) ◽  
pp. 1113
Author(s):  
Zhiqiang Guo ◽  
Shenlong Li ◽  
Wei Wu ◽  
Liuyang Zhang
Keyword(s):  
Static Load ◽  
Dynamic Performance ◽  
Planetary Gear ◽  
Load Sharing ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Computation Method ◽  
Analysis Method ◽  
Planetary Gear Sets ◽  
Bearing Stiffness

The quasi-static load sharing characteristics of a planetary gear set with planet journal bearings are numerically investigated. The application of journal bearings instead of rolling bearings in planetary gear sets is an alternative to increase the rotation speed. Therefore, an effective analysis method is needed to estimate the dynamic performance of a planetary gear set with planet journal bearings. Here, an available load sharing factor computation method is developed considering the effect of the variable journal bearing stiffness. Results of an experiment are used to validate the effectiveness of the computation method. Furthermore, the load sharing characteristics of a planetary gear set with planet journal bearings are influenced by bearing parameters and operating conditions significantly due to the changing bearing stiffness of journal bearings. The effects on the load sharing factor and the bearing stiffness are studied in detail simultaneously based on the proposed analysis method. The load sharing factor of a planetary gear set with planet journal bearings has a similar variation with the bearing support stiffness under the same load. These researches provide a theoretical basis for the application of journal bearings in planetary gear sets.

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.

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.

Experimental and Theoretical Investigation of Quasi-Static System Level Behavior of Planetary Gear Sets

2021 ◽  
Vol 143 (10) ◽  
Author(s):  
Lokaditya Ryali ◽  
Abhishek Verma ◽  
Isaac Hong ◽  
David Talbot ◽  
Farong Zhu
Keyword(s):  
Load Distribution ◽  
Planetary Gear ◽  
Load Sharing ◽  
Operating Conditions ◽  
Experimental Methodology ◽  
System Level ◽  
Distribution Model ◽  
Design Parameters ◽  
Static System ◽  
Planetary Gear Sets

Abstract This study presents a unique experimental methodology that synchronously measures various quasi-static responses of a simple four-planet planetary gear set, namely, planet load sharing, overall transmission error (OTE), and floating sun gear orbits. Strain gauges mounted directly on the planet pins were used to monitor the load shared among the planets, which is a crucial design criterion for durability and performance. High-precision optical encoders were used to measure the OTE of the gear set to explore its diagnostic value in identifying system errors. Radial motions of the floating sun gear, which are critical to the self-centering and load sharing behavior of the gear set, were monitored using magnetic proximity probes. The influence of various design parameters and operating conditions such as planet mesh phasing, carrier pin position errors, gear tooth modifications, and input torque on the system’s response will be investigated by performing an extensive set of experiments in a repeatable and accurate manner. Finally, these experimental results will be recreated theoretically using the static planetary load distribution model of Hu et al. (2018, “A Load Distribution Model for Planetary Gear Sets,” ASME J. Mech. Des., 140(5), p. 53302) to not only validate the model but also comprehend the measured behavior.

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