Search Results

As fuel prices continue to be unstable the drive towards more fuel efficient powertrains is increasing. For engine original equipment manufacturers (OEMs) this means engine downsizing coupled with alternative forms of power to create hybrid systems. Understanding the effect of engine downsizing on vehicle interior NVH is critical in the development of such systems. The objective of this work was to develop a vehicle model that could be used with analytical engine mount force data to predict the vehicle interior noise and vibration response. The approach used was based on the assumption that the largest contributor to interior noise and vibration below 200 Hz is dominated by engine mount forces. An experimental transfer path analysis on a Dodge Ram 2500 equipped with a Cummins ISB 6.7L engine was used to create the vehicle model. The vehicle model consisted of the engine mount forces and vehicle paths that define the interior noise and vibration.

As engines and powertrains become quieter, sound quality becomes more important as an indicator of product quality. As a consequence, there is a heightened need to reduce gear noise. The objective of this work was to identify the source and cause of a modulated gear whine. The approach taken to identify the source of the modulation involved running a full powertrain on a spin stand and minimizing the number of meshing gear pairs until the offending pairs were identified. Further experimental testing and analysis models were employed to determine the cause of the modulation. From proximity probe measurements and backed up by the analytical model, it was determined that one of the gear mesh suffered from inadequate bearing support and off-center gear loads. This condition caused a tilt in one of the meshing gears which created a sideband that modulated with the primary meshing frequency of the transfer gear at cruise speed.