Powertrain and Driveline Integration Using Transfer Path Analysis in the New Saab 9-5 2010-01-1418
The competition in the automotive market enforces shorter vehicle development time in order to get products faster to the market. In addition the customer expectation on interior noise, vibration and harshness (NVH) refinement is increasing and has an important impact of the perception of the product. The focus on fuel economy and CO2 reduction leads also to significant challenges in the vehicle development, which may result in trade-offs for NVH performance. Today's direct injection turbo charged diesel and gasoline engines exhibit both high low-end torque, which gives the customer a pleasant drive quality and improved fuel economy. However, the NVH integration challenges become significant due to mainly structure borne noise transfer through both the driveline itself and the powertrain mounting systems. In addition, the impulsive noise due to the combustion process itself in especially diesel engines needs to be refined. The impulsiveness is often denoted as diesel knocking and is transferred into the passenger compartment both structure borne and airborne. The scope of this paper describes application of different transfer path analysis techniques, i.e. frequency and time domain, and their advantages and disadvantages in combination with objective evaluation parameters as a method to describe the phenomena of booming as well as diesel knocking. The effectiveness of achieving the customer expected noise & vibration performance, i.e. the remedy selection, depends heavily of which transfer path method applied and the associated data analysis method for each given problem. Finally, the efficiency of the remedies is validated by implementing those in hardware and finally reassessed in the vehicle.