Transient thermo‐elastohydrodynamic lubrication of gear teeth

During a gear mesh cycle, load, rolling and sliding velocities, curvature, and temperature change rapidly. In this paper, a transient, thermo-elastohydrodynamic lubrication model is presented that has been used to study the lubrication parameters at 250 contact points along the path of a contact. The working flanks were assumed to be smooth. The line load was calculated at every contact point, using the finite-element method. Dynamic loading was not considered. The steady-state temperature field of the working flanks was used to obtain the surface temperature at the inlet of each contact point, determined by an experimental-analytical method presented previously. In this model, the lubricant is considered to follow the Ree-Eyring constitutive equation. The influences of both pressure and temperature on density, thermal conductivity, and specific heat of the lubricant are also taken into account. Results are presented for an FZG type A gear pair lubricated with an FVA No. 4 reference oil; these include film shape, pressure and temperature distributions, as well as friction coefficient.