Gear transmission rattle: assessment of meshing forces under hydrodynamic lubrication

Abstract

The dynamic behavior of gear transmissions poses several challenges from the standpoint of design and requires the availability of more advanced models capable of simulating a wide range of operating conditions. In this paper, several formulations to represent efforts related to the lubricant in gear transmissions subjected to reduced torque levels has been assessed. Under these conditions, the lubrication regime is hydrodynamic and the dynamic behavior of the meshing contacts can happen in different scenarios depending on both the lubricant properties and operating conditions. Such problems are cumbersome in gear transmissions in which acoustic performance is a determining design factor, such as in car applications. In this regard, gear rattle is one of the subjects of concern by powertrain designers. In spite of several authors have approached this phenomena, the most recent interest is focused on the role played by the lubricant. The variety of fundamentals and aims of the developed models in this respect requires a better understanding of the effect taken into account by the different formulations in the accurate modeling of hydrodynamic lubrication in gears subjected to low torques. This is the reason why, in this work, several alternatives currently available in the literature to address the formulation of efforts in hydrodynamic regime was collected and presented. Such formulations were implemented in a transmission model previously developed by the authors which was used to simulate different operating conditions in order to assess the results obtained with each one of the considered formulations.