Abstract
Time and cost effective power train NVH optimization requires vehicle oriented NVH development as in the end the vehicle sound quality has to meet the customers expectations. Therefore, the impact of power train (P/T) component and combustion process modifications onto vehicle interior sound quality has to be assessed continuously. To this end vehicle interior noise simulation (VINS) has been installed. Thus, additional P/T NVH optimization work during vehicle integration on the one hand is minimized, and over engineering is avoided on the other hand.
In recent years, VINS for effective P/T NVH optimization is established more and more for predicting the effects of e.g. global P/T vibration behavior, bracket weaknesses and component noise radiation with respect to interior noise quality. However, the influence of combustion process modifications on engine noise has to be quantified on an acoustic power train test bench first before the NVH relevance in respect to vehicle interior noise can be predicted by VINS. Methods for prediction of combustion process modifications on engine noise, based on cylinder pressure analysis, are established or under development, respectively. However, a method for prediction of engine calibration with regard to vehicle interior noise quality is not known so far. his paper deals with FEVs comprehensive approach for integration of combustion process optimization into the vehicle oriented P/T NVH development work. Based on an initial NVH analysis of the first prototype P/T with rough calibration status appropriate structure weighting functions for combustion and flow noise prediction are determined. In combination with the measured mechanical noise share the overall engine noise is estimated in respect to spectral content and time characteristics. The predicted engine noise serves as input for the consecutive vehicle interior noise simulation. Thus, the calibration process at the thermodynamic test bench is effectively supported to achieve excellent compromise in respect to all vehicle development targets, i.e. fuel consumption, exhaust emissions and interior noise. In this paper the new approach is presented with regard to methodology and application exemplarily for the idle calibration optimization on a direct injected passenger car Diesel engine.
The new methodology is a powerful tool for high quality vehicle oriented P/T NVH development to avoid P/T over-engineering and to minimize NVH fine-tuning during vehicle integration.