Analysis of Lubricating Performance for Involute Gear Based on Dynamic Loading Theory

An integrated model for gear pair that combines the dynamic load with the mixed elastohydrodynamic lubrication (EHL) theory is proposed in this paper covering the film squeeze effect as well as the friction force generated from the rough surfaces. Comparisons between the two models of load which are, respectively, based on minimum elastic potential energy (MEPE) criterion and dynamic motion equations built up in this paper are discussed. The results show that at low speed the loads calculated by the two models are similar. However, with increasing speed, the load exhibits dynamic characteristics gradually and reaches the highest value at resonant speed. Besides, the effects of the helix angle and the lubricant viscosity are also analyzed. Increasing the ambient viscosity could intensify the film stiffness and viscous damping. Gear with larger helix angle could weaken the impact phenomenon at the shift points where one tooth-pair disengages. Moreover, it is symmetric with regard to the pressure and film thickness across the face width for spur gear. Differently, the pressure for helical gear has a higher value at the dedendum of pinion where the film becomes thinner. In addition, speeding up the pinion would generally result in higher dynamic load and film pressure but thicker film thickness.