Samenvatting
Public transport has become increasingly important in urban areas because of congested streets and emission problems caused by road traffic. To minimize the exhaust emissions, passenger cars are more and more being excluded from city centres and increased bus services are being offered. As a consequence of this, the buses in use must fulfil extremely low emission levels. Methane, propane and butane offer a big potential to fulfil the requirements of low emission systems. The paper reports about LPG- and CNG-gas-engines with oxygen sensor and 3-way-catalyst developed by MAN/ÖAF and their use in city buses. Components of the system are described and emission data for the LPG-engine as well as the CNG-engine are given. (A)