Transient EHL gear contact simulation

Abstract

The aim of this work is to simulate the contact of gear tooth flanks under realistic operating conditions. This implies the calculation of film heights, the hydrodynamic as well as the dry pressure distribution and the resulting forces on the gearwheels. Especially the dynamic behavior of gearwheels during tooth impacts is of great interest, because preliminary investigations showed that the lubricant has an extensive wide range of influence in such situations. These impacts are critical for automotive gear-rattle noises (noises caused by loose parts movement under engine excitation). Nevertheless, with the presented model highly-loaded power-transmitting gear contactsmay also be investigated in order to determine vibration under load or lubrication conditions. To simulate the contacts two different solutions of the Reynolds equation were developed:Asimplified analytical and a numerical one.Both consider the wedge and the squeeze termof the Reynolds equation to allowfor a full transient analysis.The analytical solution is accomplished using assumptions for the gap shape and the pressure in themiddle of the gap.The numerical problemis solved using fastmultilevel multi-integration algorithms. The method is implemented as a force element in the multi-body simulation environment SIMPACK. Therefore it is easy to transfer the developed element to other models and use it for a multitude of different engineering problems.After implementation of themodel several simulations have been donewith gearbox models. The pressure distributions, gap heights, type of friction (hydrodynamic/ mixed/dry) and resulting forces of all flanks in contact can be determined. Furthermore, with the use of a very detailed elastic multi-body model of the transmission, direct determination of housing vibrations is possible. The results are validated with measurements on a special test bench. © Springer-Verlag 2013.