The Transient and Thermal Effects on EHL Performance of a Helical Gear Pair

A non-Newtonian numerical solution system for the transient thermo-elastohydrodynamic lubrication (TEHL) model has been proposed for a helical gear pair with the finite line contact theory. This model is used to comprehensively show the transient effect, temperature effect, operating condition and the non-Newtonian behaviors on the lubricating performance. The results indicate that, the transient effect is insignificant except the area of engaging-in and engaging-out along the line of action (LOA). Besides, due to the pitch point position on the contact line, the temperature distributions in different meshing positions along LOA is significantly differentiated. In the single tooth contact region, the variation of film thickness is delayed for the load variation. By introducing the thermal effect, the film thickness has been reduced and the difference of friction coefficient is significant between the isothermal and thermal model. The effect of input torque and speed is significant for the lubrication performance. As the input torque increases, the squeeze effect has been enhanced during the engaging-in region. Finally, the influence of characteristic shear stress of the Eyring fluid on the pressure and film thickness is negligible. The results indicate that the TEHL model with non-Newtonian fluid predicts more realistic friction coefficient