Partial EHL friction coefficient model to predict power losses in cylindrical gears

Arana, Aitor; Larrañaga, Jon; Ulacia, I.

doi:10.1177/1350650118778655

Cited by 15 publications

(14 citation statements)

References 36 publications

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“…Accurate calculation of sliding friction coefficient on tooth surface is of great significance to reduce the power loss, increase the load capacity of tooth and improve the transmission performance of gear system. [1][2][3] The calculation method of sliding friction coefficient on tooth surface includes: (1) the sliding friction coefficient on tooth surface is replaced with the average sliding friction coefficient. 4,5 The method is relatively simple but imprecise because the sliding friction coefficient on tooth surface is related to the relative sliding velocity, entrainment velocity, lubricant viscosity, load, curvature radius and surface roughness of the meshing point on tooth surface; (2) the sliding friction coefficient on tooth surface comes from the test formula, which is obviously more accurate than the first one, 6,7 but these formulas are all taken from the specific test environment, such as lubrication type, temperature, velocity, load and surface roughness, which may be different from the actual calculation environment of the user; (3) the sliding friction coefficient on tooth surface is to improve the experimental formula, 8,9 so that it can be used more widely.…”

Section: Introductionmentioning

confidence: 99%

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

Wang

Mao

2020

Proceedings of the Institution of Mechanical Engineers, Part J:

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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.

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Section: Introductionmentioning

confidence: 99%

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

Wang

Mao

2020

Proceedings of the Institution of Mechanical Engineers, Part J:

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“…They presented the coefficient of friction or power losses predictions in the gear contact surfaces using elastohydrodynamic lubrication (EHL) models. [21][22][23][24][25][26][27][28][29][30] Like many EHL analyses, this physics-based approach needs an important computational effort.…”

Section: Introductionmentioning

confidence: 99%

Frictional dynamic model predictions of FZG-A10 spur gear pairs considering profile errors

Féki

Hammami

Ksentini

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part J:

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In this work, a nonlinear dynamic model of an FZG-A10 spur gear was investigated by taking into account for the actual time-varying gear mesh stiffness and the frictional effects between meshing gear teeth to evaluate the influence of the dynamic effects on frictional gear power loss predictions. The equations of motion of the generalized translational-torsional coupled dynamic system derived from Lagrange principle was extended compared to authors’ previous work in order to account for time dependent coefficient of friction and profile errors. The dynamic response of spur gears, computed by an iterative implicit scheme of Newmark, is changed due to the presence of coefficient of friction and profile errors. A dynamic analysis was performed and the influence of frictional effect including tooth shape deviations, in particular, was scrutinized since a time-dependent coefficient of friction is deeply related to the gear surface roughness and all parameters dependent on gears error profiles are introduced in the proposed model. The predicted meshing gear power losses with constant and local friction coefficient were compared. The influence of constant and variable profile errors considered in the local coefficient of friction formulation was also studied and their corresponding root mean square (RMS) power loss was compared to the experimental results. The results using FZG A10 spur gear pairs running under several operating conditions (different loads and speeds) validate the superiority of the proposed model against previous similar models.

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“…Some of them are referenced. [37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56] The geometrical separation of contacting tooth surfaces has an important role in the mixed EHL. Nowadays, in all the hypoid gears, appropriate tooth surface modifications are introduced to reduce the sensitivity of the gear pair to tooth errors and misalignments inherent in the gear box and to avoid the very dangerous edge contact.…”

Section: Introductionmentioning

confidence: 99%

Improvements in the mixed elastohydrodynamic lubrication and in the efficiency of hypoid gears

Simon

2019

Proceedings of the Institution of Mechanical Engineers, Part J:

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In this paper, the influence of the manufacturing parameters on the conditions of mixed elastohydrodynamic lubrication is investigated. On the basis of the obtained results, recommendations are formulated to improve the mixed EHL and the efficiency of face-milled hypoid gears. A full numerical analysis of the mixed EHL in hypoid gears is applied. The equation system and the numerical procedure are unified for a full coverage of all the lubrication regions, including the full film, mixed, and boundary lubrication. In the hydrodynamically lubricated areas, the calculation method employed is based on the simultaneous solution of the Reynolds, elasticity, energy, and Laplace's equations. In the asperity contact areas, the Reynolds equation is reduced to an expression equivalent to the mathematical description of dry contact problem. The real geometry and kinematics of the gear pair based on the manufacturing procedure are applied; thus, the exact geometrical separation of the mating tooth surfaces is included in the oil film shape, and the real velocities of these surfaces are used in the Reynolds and energy equations. The transient nature of gear tooth mesh is included. The oil viscosity variation with respect to pressure and temperature and the density variation with respect to pressure are included. The non-Newtonian behaviour of the lubricant is considered. Using this model, the pressures, film thickness, temperatures, and power losses in the mixed lubrication regime are predicted. The effectiveness of the presented method is demonstrated by using hypoid gear examples.

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Partial EHL friction coefficient model to predict power losses in cylindrical gears

Cited by 15 publications

References 36 publications

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

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

Frictional dynamic model predictions of FZG-A10 spur gear pairs considering profile errors

Improvements in the mixed elastohydrodynamic lubrication and in the efficiency of hypoid gears

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