Parametric Studies of Mechanical Power Loss for Helical Gear Pair Using a Thermal Elastohydrodynamic Lubrication Model

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Mingyong Liu ◽  
Peidong Xu ◽  
Chunai Yan
Keyword(s):  
Friction Coefficient ◽  
Thermal Effect ◽  
Power Loss ◽  
Elastohydrodynamic Lubrication ◽  
Mechanical Efficiency ◽  
Helical Gear ◽  
Tribological Performance ◽  
Mechanical Power ◽  
Gear Pair ◽  
Helical Gear Pair

In this study, a comprehensive mechanical efficiency model based on the thermal elastohydrodynamic lubrication (TEHL) is developed for a helical gear pair. The tribological performance of the helical gear pair is evaluated in terms of the average film thickness, friction coefficient, mechanical power loss, mechanical efficiency, etc. The influence of basic design parameters, working conditions, thermal effect, and surface roughness are studied under various transmission ratios. Results show that the contribution of thermal effect on the tribological performance is remarkable. Meanwhile, the rolling power loss constitutes an important portion of the total mechanical power loss, especially around the meshing position where the pitch point is located in the middle of contact line and the full elastohydrodynamic lubrication (EHL) state with the friction coefficient less than 0.005. The proper increase of normal pressure angle and number of tooth can improve the tribological performance. The influence of helix angle on the mechanical efficiency is less significant. A positive addendum modification coefficient for pinion and a negative addendum modification coefficient for wheel are good for improving the mechanical efficiency. The results provide the tribological guidance for design of a helical gear pair in engineering.

Analysis of mechanical power loss of a helical gear pair based on the starved thermal-elastohydrodynamic lubrication model

2019 ◽  
Vol 72 (3) ◽  
pp. 333-340
Author(s):  
Mingyong Liu ◽  
Peidong Xu ◽  
Jinxi Zhang ◽  
Huafeng Ding
Keyword(s):  
Surface Roughness ◽  
Tribological Properties ◽  
Power Loss ◽  
Elastohydrodynamic Lubrication ◽  
Helical Gear ◽  
Mechanical Power ◽  
Gear Pair ◽  
Content Type ◽  
Helical Gear Pair ◽  
Film Lubrication

Purpose Power loss is an important index to evaluate the transmission performance of a gear pair. In some cases, the starved lubrication exists on the gear contact interface. The purpose of this paper is to reveal the mechanical power loss of a helical gear pair under starved lubrication. Design/methodology/approach A starved thermal-elastohydrodynamic lubrication (EHL) model is proposed to evaluate the tribological properties of a helical gear pair. The numerical result has been validated against the published simulation data. Based on the proposed model, the influence of thermal effect, working conditions, inlet oil-supply layer and surface roughness on the mechanical power loss and lubrication performance has been discussed. Findings Results show that the thermal effect has a significant effect on the tribological properties of helical gear pair, especially on mechanical power loss. For a specified working condition, there is an optimal oil supply for gear lubrication to obtain the state of full film lubrication. Meanwhile, it reveals that the mechanical power loss increases with the increase of the surface roughness amplitude. Originality/value In this paper, a starved thermal-EHL model has been developed for the helical gear pair based on the finite line contact theory. This model can be used to analyze the tribological properties of gear pair from full film lubrication to mixed lubrication. The results can provide the tribological guidance for design of a helical gear pair.

A calculation method of sliding friction coefficient on tooth surface for helical gear pair based on loaded tooth contact analysis and elastohydrodynamic lubrication theory

2020 ◽  
pp. 135065012096689
Author(s):  
Cheng Wang ◽  
Mao Ken
Keyword(s):  
Friction Coefficient ◽  
Sliding Friction ◽  
Elastohydrodynamic Lubrication ◽  
Helical Gear ◽  
Tooth Surface ◽  
Gear Pair ◽  
Tooth Contact Analysis ◽  
Sliding Friction Coefficient ◽  
Loaded Tooth Contact Analysis ◽  
Helical Gear Pair

The sliding friction coefficient on tooth surface is related to power loss, carry capacity and transmission performance of gear. Reasonable transmission analysis of gear pair is the premise of accurate calculation of sliding friction coefficient on tooth surface. However, for helical gear pair, the line contact without considering machining error/installation error/modification of gear is usually adopted to replace the major axis of ellipse caused by contact load. Therefore, in this paper, contact path on tooth surface, length of contact line, load distribution on tooth surface and loaded transmission errors are accurately calculated by loaded tooth contact analysis (LTCA). Combing with elastohydrodynamic lubrication (EHL) theory, a calculation method of sliding friction coefficient on tooth surface for helical gear pair is proposed.

A Helical Gear Pair Pocketing Power Loss Model

2013 ◽  
Author(s):  
David Talbot ◽  
Ahmet Kahraman ◽  
Satya Seetharaman
Keyword(s):  
Fluid Dynamics ◽  
Power Loss ◽  
Control Volume ◽  
Fluid Pressure ◽  
Helix Angle ◽  
Helical Gear ◽  
Gear Pair ◽  
Dynamics Model ◽  
Gear Mesh ◽  
Helical Gear Pair

A new fluid dynamics model is proposed to predict the power losses due to pocketing of air, oil, or an air-oil mixture in the helical gear meshes. The proposed computational procedure treats a helical gear pair as combination of a number of narrow face width spur gear segments staggered according to the helix angle and forms a discrete, fluid dynamics model of the medium being pocketed in the gear mesh. Continuity and conservation of momentum equations are applied to each coupled control volume filled with a compressible fluid mixture to predict fluid pressure and velocity distributions from, which the instantaneous pocketing power loss is calculated. The proposed model is exercised in order to investigate fluid pressure and velocity distributions in time, as well as pocketing power loss as a function of speed, helix angle and oil-to-air ratio.

Research on Dynamic Model of Double Helical Gear Pair Based on TCA and LTCA

2019 ◽  
Vol 24 (3) ◽  
pp. 476-484 ◽  
Author(s):  
Cheng Wang ◽  
Shouren Wang ◽  
Gaoqi Wang
Keyword(s):  
Friction Coefficient ◽  
Dynamic Model ◽  
Dynamic Models ◽  
Sliding Friction ◽  
Helical Gear ◽  
Tooth Surface ◽  
Gear Pair ◽  
Axial Vibration ◽  
Sliding Friction Coefficient ◽  
Helical Gear Pair

Numerous dynamic models of spur gears, helical gears, bevel gears, and face gears can be found in various studies. However, studies that focus on the dynamic model of a double helical gear pair are quite limited. The author proposed a model of a double helical gear pair by only considering the axial vibration. The author did not consider the friction and multiple backlashes in the proposed model. The friction force of the tooth surface and backlash are important factors that can cause complex non-linear phenomena in gear pairs. Therefore, a dynamic model of a double helical gear pair that takes into consideration the axial vibration, friction and multiple backlashes is proposed. Firstly, based on the tooth contact analysis (TCA) of a double helical gear pair, the path of contact and meshing time from engagement to disengagement are obtained. The formula for determining the sliding friction coefficient is introduced. Based on TCA and the dynamic meshing force provided by the subsequent dynamics model of double helical gear pair, the sliding friction coefficient of the tooth surface is calculated. Secondly, the stiffness excitation, gear-into impact excitation and error excitation (including the axial displacement caused by the errors of manufacture and installation under low speed) are calculated according to the existing research results. Following this, a dynamic model of a double helical gear pair that takes into consideration the axial vibration, friction and multiple backlashes is both built and solved. Finally, an example is presented to verify the corresponding results.

A Computational Study on the Mechanical Power Loss of a Spur Gear Pair Under the Thermal Tribo-Dynamic Condition

2015 ◽  
Author(s):  
Sheng Li
Keyword(s):  
Power Loss ◽  
Computational Study ◽  
Dynamic Condition ◽  
Elastohydrodynamic Lubrication ◽  
Static Condition ◽  
Spur Gear ◽  
Mechanical Power ◽  
Gear Pair ◽  
Gear Mesh ◽  
Six Degree Of Freedom

This study proposes a formulation for the description of the gear mesh mechanical power loss under the thermal tribodynamic condition. A six degree-of-freedom motion equation set that models the vibratory motions of a general spur gear pair is coupled with the governing equations for the description of the gear thermal mixed elastohydrodynamic lubrication to include the interactions between the gear dynamics and gear tribology disciplines in the modeling of the gear mesh mechanical power loss. The important role of the gear thermal tribo-dynamics in power loss is demonstrated by comparing the predictions of the proposed model to those under the thermal quasi-static condition, and the iso-thermal tribo-dynamic condition, respectively.

Dynamic model of a helical gear pair considering tooth surface friction

2020 ◽  
Vol 26 (15-16) ◽  
pp. 1356-1366 ◽  
Author(s):  
Cheng Wang
Keyword(s):  
Friction Coefficient ◽  
Dynamic Model ◽  
Sliding Friction ◽  
Surface Friction ◽  
Helical Gear ◽  
Tooth Surface ◽  
Gear Pair ◽  
Tooth Contact Analysis ◽  
Sliding Friction Coefficient ◽  
Helical Gear Pair

The tooth surface friction is one of the main sources of gear vibration and noise. The current challenging problems in research of a helical gear pair dynamics considering tooth surface friction include the following: (1) Calculation accuracy of the tooth surface friction factor needs to be improved. (2) The meshing process of a helical gear pair has not been fully taken into account in a dynamic model. To solve these problems, a dynamic model of a helical gear pair considering tooth surface friction is proposed in this article. First, based on the tooth contact analysis and loaded tooth contact analysis of a helical gear pair, excitation of time-varying meshing stiffness, the sliding friction coefficient on tooth surface, and the arm of friction force are preliminarily calculated. Second, the dynamic model of a helical gear pair considering tooth surface friction is built and solved, in which the dynamic meshing force/speed/displacement is calculated. The sliding friction coefficient on tooth surface, arm of friction force, and dynamic equations form a coupled system. By decoupling calculation, the model system equations are solved. Finally, an example is presented to verify the proposed model.

Effects of Working Conditions on TEHL Performance of a Helical Gear Pair With Non-Newtonian Fluids

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Mingyong Liu ◽  
Caichao Zhu ◽  
Huaiju Liu ◽  
Huafeng Ding ◽  
Zhangdong Sun
Keyword(s):  
Working Conditions ◽  
Power Law ◽  
Elastohydrodynamic Lubrication ◽  
Helical Gear ◽  
Gear Pair ◽  
Power Law Fluid ◽  
Finite Line Contact ◽  
Lubrication Performance ◽  
Finite Line ◽  
Helical Gear Pair

A thermal elastohydrodynamic lubrication (TEHL) finite line contact model is developed for a helical gear pair lubricated with an Eyring fluid or a power-law fluid in order to investigate the effects of the working conditions. A lubrication analysis within a meshing period shows that the differences between the Eyring and Newtonian solutions mainly lie in the film temperature and the shear stress. For the power-law fluid, the power index n has a significant effect on the film thickness. The effects of load and speed on lubrication performance along the line of action are discussed.

Thermal elastohydrodynamic lubrication analysis of helical gear pair under starved lubrication condition

2019 ◽  
Vol 31 (7) ◽  
pp. 321-334 ◽  
Author(s):  
Mingyong Liu ◽  
Jinxi Zhang ◽  
Peidong Xu ◽  
Hao Cai ◽  
Haofeng Ku ◽  
...  
Keyword(s):  
Elastohydrodynamic Lubrication ◽  
Helical Gear ◽  
Gear Pair ◽  
Lubrication Condition ◽  
Starved Lubrication ◽  
Helical Gear Pair

A Transient Mixed Elastohydrodynamic Lubrication Model for Helical Gear Contacts

2020 ◽  
Vol 143 (6) ◽  
Author(s):  
A. S. Chimanpure ◽  
A. Kahraman ◽  
D. Talbot
Keyword(s):  
Power Loss ◽  
Contact Region ◽  
Elastohydrodynamic Lubrication ◽  
Sensitivity Study ◽  
Helical Gear ◽  
Operating Conditions ◽  
Mechanical Power ◽  
Distribution Model ◽  
Rolling Velocity ◽  
Gear Mesh

Abstract In this study, a non-Newtonian, transient, isothermal, mixed elastohydrodynamic lubrication (EHL) model is proposed for helical gear contacts. The model accounts for nonelliptical contacts subject to spatially varying sliding and rolling velocity fields that are not aligned with any principal axis of the contact region, which is the case for helical gear contacts. The time-varying changes pertaining to key contact parameters and relative motion of roughness profiles on mating tooth surfaces are captured simultaneously to follow the contact from the root to the tip of a tooth while accounting for the transient effect due to relative motions of the roughness profiles. Actual tooth load distributions, contact kinematics, and compliances of helical gear contacts are provided to this model by an existing helical gear load distribution model. Measured three-dimensional roughness profiles covering the entire meshing zone are incorporated in the analyses to investigate its impact on the EHL conditions as well as mechanical power loss. Results of a parametric sensitivity study are presented to demonstrate the influence of operating conditions and surface roughness on the EHL behavior and the resultant gear mesh mechanical power loss of an example helical gear pair. The accuracy of the proposed mixed-EHL model is assessed by comparing the mechanical power loss predictions to available experimental results.

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