Environmental pollution is likewise characterized by noise
emissions. As a result, according to the European ambient noise
directive 2002/49/EG, noise pollution of inner-city areas, in
particular congested urban areas, is a major issue of the future
European policy. In areas of bus stops and roofed installations,
such as bus stations, there are high values of disturbing noise
emissions induced by urban bus traffic.
Concerning this matter, hybrid urban buses are able to offer
promising solutions for an effective noise emissions reduction. At
the Institut für Kraftfahrzeuge (ika), RWTH Aachen University, the
project "HYBOB," financed by the BMWi (Bundesministerium
für Wirtschaft und Technologie), is being conducted in cooperation
with the EvoBus GmbH/Daimler Buses. The project is aiming to design
and develop a highly sophisticated serial-hybrid diesel-electric
propulsion system for urban bus applications. Besides fuel
consumption reduction and lower CO2 emissions, the development and
implementation of innovative solutions for an effective noise
emissions reduction and also enhanced passenger comfort are major
NVH-related tasks of this project. Relevant NVH aspects, the
development process as well as current optimization results of the
ongoing project are represented in this paper.