Abstract
Energy efficiency and functional reliability are the two key requirements in the design of high-performance transmissions. Therefore, a representative analysis replicating real operating conditions is essential. This paper presents the thermoelastohydrodynamic lubrication (TEHL) of meshing spur gear teeth of high-performance racing transmission systems, where high generated contact pressures and lubricant shear lead to non-Newtonian traction. The determination of the input contact geometry of meshing pairs as well as contact kinematics are essential steps for representative TEHL. These are incorporated in the current analysis through the use of Lubricated Loaded Tooth Contact Analysis (LLTCA), which is far more realistic than the traditional Tooth Contact Analysis (TCA). In addition, the effects of lubricant and flash surface temperature rise of contacting pairs, leading to the thermal thinning of lubricant, are taken into account using a thermal network model. Furthermore, high-speed contact kinematics lead to shear thinning of the lubricant and reduce the film thickness under non-Newtonian traction. This comprehensive approach based on established TEHL analysis, particularly including the effect of LLTCA on the TEHL of spur gears, has not hitherto been reported in literature.
Highlights
Spur gears are used in a multitude of engineering applications, including but not limited to automotive transmissions
In order to evaluate the effect of Lubricated Loaded Tooth Contact Analysis (LLTCA) alone, the current study uses a standard one-dimensional non-Newtonian thermoelastohydrodynamic lubrication (TEHL) model of spur gear teeth pair with the instantaneous contact geometry and kinematics determined using the LLTCA, which is compared with the traditional Tooth Contact Analysis (TCA) method
Geometry used for the analysis is measured using a coordinate measuring machine It is Surface assumed that all gear teeth would undergo the same loading history during a typical (CMM) with a measurement sensitivity of ± 1.5 μm
Summary
Spur gears are used in a multitude of engineering applications, including but not limited to automotive transmissions. These are the induced root stresses and contact surface defects caused by the generated sub-surface stresses The latter form part of the current investigation, as they are more of concern for high-performance transmissions based upon spur gears. In order to evaluate the effect of LLTCA alone, the current study uses a standard one-dimensional non-Newtonian thermoelastohydrodynamic lubrication (TEHL) model of spur gear teeth pair with the instantaneous contact geometry and kinematics determined using the LLTCA, which is compared with the traditional TCA method. In this manner, the effect of LLTCA in a more accurate prediction of contact conditions becomes clear. Such an approach has not hitherto been reported in the literature
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