New Features on Noise, Vibration and Harshness Posed by the Next Generation of Vehicles

Abstract

Traffic noise is generally considered one of the most important sources of environmental pollution in urban and interurban areas. Each individual vehicle in the traffic flow contributes to the total emission by means of three different sub-sources: noise emitted by engine, exhaust and transmission; aerodynamic noise; and noise radiated during tire/road interaction. Those sub-sources play a different role depending on the characteristics of the traffic, i.e. for low speed traffic – less than 30km/h – mechanical noise coming from engine and drive chain is the prominent, whilst for high speed – above 30km/h – the main contribution is related to tire/road noise. The new generation of hybrid and electric vehicles (HEVs) will contribute to a reduction of noise pollution through reduced use or inexistence of the internal combustion engine. That feature, which is positive for environmental noise control, carries a negative connotation since low noise emissions of HEVs represent an actual danger to pedestrians. Also drivers of HEVs should adapt their driving style and behavior to the new features related to noise, vibration and harshness (NVH) inside the cabin. In order to solve that problem, warning sounds are being designed by HEVs manufacturers, but, it is not actually known how those new sounds will integrate into urban soundscapes. These and many other questions arise related to the increased presence of electric vehicles in city car fleets. The Research Group in Applied Mechanical Engineering of Miguel Hernandez University in Spain is currently coordinating the COST TU1105 Action “NVH analysis techniques for design and optimization of hybrid and electric vehicles”, together with the Noise and Vibration Research Group of KU Leuven in Belgium. The aim of the Action is to engage NVH experts from vehicle industry and renowned research groups in the accumulation, development and dissemination of novel analysis techniques to be developed for the next generation of vehicles and their drivers. In this article, new features posed by HEVs are discussed and latest developments on the topic are presented.