Automatic Transmission Gear Whine Simulation and Test Correlation

In order to effectively evaluate automatic transmission gear noise and vibration performance using a hemi-anechoic test facility, it is essential to understand the coupling mechanism between the transmission internals and the dynamometers and associated shafting. Once this coupling mechanism is well understood, each major frequency response of the resulting torsional vibration operating data can be properly categorized according to the source: transmission-internal, facility, or driveshaft. This knowledge helps noise and vibration engineers properly manage vibration peaks in transmission operating data by ensuring that the issue of concern is not inadvertently influenced by the facility system. Analytical simulations and tests were performed on a transmission operated in a hemi-anechoic facility to evaluate gear vibration using various driveshafts, followed by a program of vehicle testing. The objective of this study was to correlate the transmission gear whine simulation results with corresponding hemi-anechoic cell and vehicle level operating vibration data and to investigate if the hemi-anechoic test data could be used in vehicle level transmission gear whine target setting.