EHL lubrication in spur and helical gear pairs

Gear efficiency is highly relying on elasto-hydrodynamic lubrication (EHL), and gear lubrication is significantly dependent upon non stationary conditions in gear pairs. Furthermore, the presence of lubricant is the main responsible of the damping effect in gear pair vibration. For these reasons, gear vibration and gear lubrication are to be considered as coupled problems. In the present work, a dynamic model of gear pairs taking into account for EHL lubrication is presented. The multilevel technique is used to solve the EHD lubrication problem, together with the equation describing the relative motion of the mating gears. Gear lubrication conditions at different gear rotation speed are investigated, in order to point out the effect of coupling between a thin lubricant film and elastic deformations in contacting bodies; a comparison between a dry contact and a lubricated contact is drawn, in order to clarify the amount of damping introduced by the lubricant film.