Abstract
Keywords: environment, recuperation, mobility, hybrid drive
Dwindling petroleum resources at the same time as a worldwide increase in petroleum consumption and the growing demands related to exhaust gas emission quality pose engine and vehicle developers with a major challenge. This also leads to a developmental concentration on fuel savings and the reduction of emissions.
The development of hybrid drives permits an increase in the efficiency of the transport systems and a reduction in the emission of exhaust gas. The brake energy generated in the braking process is temporarily stored and re-supplied to the driveline. Owing to their highly dynamic mode of operation vehicles in municipal service, in particular buses are especially suitable for hybridisation and the recuperation of brake energy.
Today the hybrid drives built and tested by MAN for city buses are based on decades of experience. Development from hybrid drives with a flywheel store and the storage of the brake energy in hydraulic accumulators has led to diesel-electric drives in which brake energy is stored in electric reservoirs. Batteries, ultracapacitors or a combination of both may be installed. By this, the driveline can be optimised for its specific service. By building and testing the hybrid buses to date MAN has been able to demonstrate their suitability for day to day service.
With the development level it has already achieved MAN is getting closer to economically viable service. Diesel-electric hybrid drives can be considered to be a transitional technology on the way to electric vehicles of the future. One key parameter therefore is the energy density of electric storage systems, which has to be further increased.
The use of hybrid vehicles can be seen in the contradictory context between economy and ecology. Ultimately, widespread introduction of hybrid technology in bus drives will depend on the general political and economic conditions.
The report shows a comparison of different drive systems recorded on the same bus line.