Noise legislations and the increasing customer demands determine the NVH-development of modern commercial vehicles. In this paper suitable engineering approaches will be discussed.
In order to meet the very stringent legislative requirements of the EEC and some other countries refinement of all vehicle noise sources is required. Cost-effective solutions, however, can only be found with low-noise powertrains, thus being able to avoid excessive noise packages on the vehicle. There is increasing demand, because modular systems should be ready to power a variety of different trucks and busses and allow for easy servicability.
With this focus on powertrain noise, the paper discusses and outlines the technological developments required to achieve sufficient noise reduction which aims towards a 1m engine noise level of 93 dBA measured in an acoustic test cell under rated conditions.
This very tough target for future engines can only be achieved with low-noise design concepts, with special consideration of the diesel injection and combustion system and a perfectly optimized powertrain structure. Potentials, analysis methods and the application of advanced simulation techniques in combination with experimental development and fine-tuning will be described in this paper and can be demonstrated by case studies.
Clearly, future demands will also include competitive noise quality inside and outside the vehicle, not only in drive, but also in idle condition. The AVL Annoyance Index can be successfully applied to support the noise quality development.