AGMA 09FTM10-2009 pdf free download.AGMA Technical Paper The Effect of Flexible Components on the Durability, Whine,Rattle, and Efficiency of an Automotive Transaxle Geartrain System by A. Korde and B.K. Wilson, Romax Technology, Inc.
Further studies usin9 the same geartrain system CAE tools have shown the importance of including representative boundary conditions, such as the driveline downstream inertia and gearbox housing loads, and the resulting effect on noise, vibration and durability predictions [6). Clearly, the flexible housing containing the geartrain was a critical component enabling the correct mesh misalignment to be predicted as part of the total system, therefore allowing a more robust non-linear gear contact study to be performed. Additional investigations also showed that the downstream effects of the durability rig (inertia, dynamics) can inacivertently effect the outcome of the durability testing itself, compared to how the geartrain would perform in the actual vehicle. The study demonstrated that durability rig testing, without proper analysis, may provide an incorrect indication of actual durability performance, possibly leading to unexpected failures in the field.
An issue not clearly demonstrated for geartrain systems such as transmissions and transaxies used in various industrial applications is the need for induding flexible components as part of the system analysis, specifically for analysis of performance attributes such as gear durability, whine, rattle, and total system efficiency with predictions for individual component efficiency contributions. For transmissions with rigid housings, explicitly designed to not deflect significantly even under high geartrain loads, perhaps the flexibility of the housing is not so critical for the making accurate gear mesh misalignment predictions for instance. However, for applications where the gearbox housing is optimized for weight, using materials such as aluminum and magnesium with thin-walled designs, housing flexibility becomes exceedingly important when analyzing geartrain deflections not only for high loads, but across a wide range of loading
conditions.
This paper will investigate the housing flexibility issue using a generic manual transaxle used in an automotive as an example. The transaxle was modeled using the advanced CAE tool previously referenced [1-6], both with and without the housing as shown in Figure 1. AIl gear, bearing and shating details were the same, except that the outer bearing race connections to the condensed finite element model of the housing were set to ground for the configuration without the housing. Therefore, the differences between the performance attributes analyzed and presented below represent the effect of the housing. Additional capabilities inherent to the inclusion of the housing as part of the geartrain system analysis will also be demonstrated.
Mesh misalignment For the purposes of the mesh misalignment investigation, the aforementioned transaxle was analyzed with the powerflow of the system set through first gear only, predicting the alignment effects at the first gear and final drive mesh locations,as indicated in Figure 2.AGMA 09FTM10 pdf download.