Practical methods to control gear whine in transmission manufacturing process
Gear whine of automotive transmissions should be controlled since it is of a nuisance. While many methods are used to control gear whine at gear design stage, this paper deals with it in transmission manufacturing process including gear manufacturing and transmission assemblies. There are high percentages of effects on transmission error and gear whine in these two processes. Idle gear whine noise can be reduced by the introduction of hard finishing which can optimize the gear shapes and surfaces. Bending of helical gear is found playing an important role in generating high frequency gear whine. It is significant for transmission assemblies to study the correlations of End of Line (EOL) and vehicles. The satisfying correlations can identify and control gear whine of an assembled transmission. All the methods mentioned above have been applied in transmission manufacturing process and good results have been achieved.
Practical Methods for Managing the Gear Whine Phenomena
Unprecedented competition among the worldwide automotive manufacturers has benefited the consumer, resulting in higher levels of overall quality while simultaneously reducing the time-to-market for new models. One subjective differentiator of automotive quality is the noise and vibration performance, as evident by the quieter interiors even in vehicles not typically associated with the luxury banner, such a large trucks. In essence, passenger compartments devoid of objectionable road and wind noise have become a fundamental customer requirement expected in all vehicles regardless of cost, thereby reducing the broadband masking content of the interior. This reduction of masking has the potential to make tonal noise more prominent and annoying, by increasing the tone-to-noise ratio, and as result, the perception of quality may suffer. Gear whine is one such tonal noise phenomena that must be diligently managed by automotive engineers in order to avoid objectionable passenger compartment noise. This can be quite challenging, since many gear design features implemented for increased durability are often counter productive for noise. Sources of gear whine include powertrain components such as automatic and manuals transmissions, axles, transfer cases, power-take of units, engine accessory drives, and an assortment of other potential noise makers. This paper will attempt a technology review of various practical methods for managing the gear whine phenomena, including the use of Quality Function Deployment charts, dynamic transmission error with parametric gear models, and response surface modeling for gear design optimization.Copyright © 2007 by Ford Motor Company
Gear-Tooth Stresses at High Speed
If the maximum stress in a gear tooth is less than the fatigue limit for the material, the tooth should not fail even after indefinitely prolonged running. Fatigue data collected in the conventional way suggest that the number of stress cycles required to cause failure of a given material under any particular stress is independent of the time-rate of repetition of stress. It should therefore be permissible to stress any gear, regardless of its speed, up to the fatigue limit for its material, although this suggestion may need modification because of the difference between the impulsive nature of the application of load to a gear, and the more gradual fluctuation of stress in a fatigue-test specimen of the Wohler type.Where high-speed gears have failed under stresses apparently lower than the fatigue limit, it becomes necessary to consider whether the actual stress was as low as had been supposed. Errors of pitch and profile in gear teeth may cause actual stresses to be higher than nominal stresses by an am...