The European emission legislation for two-wheeler vehicles
driven by engines of ≤ 50 cm₃ is continuously developing. One of
the most important issues in the near future will be the
finalization of the European Commission's proposals for future
steps in the emissions regulations as well as the verification of
the impacts of current standards on the market. To have a basis for
the discussion about these topics, the Association for Emissions
Control by Catalyst (AECC) with the Institute for Internal
Combustion Engines and Thermodynamics of Graz University of
Technology (IVT) carried out an extensive test program to show the
actual emission situation of state-of-the-art mopeds including mass
and number of particulate matter as well as unregulated gaseous
components.
One of the main goals of these tests was to measure exhaust
emissions without any modifications to the engines of standard
production vehicles available on the European market. The selection
of test vehicles was carried out to get the best possible variety
of technologies representing the actual situation on the street. To
gain a significant overview of the emission situation as well as
the potential of different technologies, it was very important to
take vehicles from both the two-stroke and the four-stroke segment.
Within these main segments the range of vehicles should provide low
cost technologies as well as high end solutions for engine control
and exhaust gas aftertreatment. Beside the current and proposed
future UNECE R47 measurement procedures, the chosen two-wheelers
were also operated on the reduced speed WMTC part 1 cycle (this
being the closest match available for moped specifications) to
evaluate the influence of different testing procedures. Regarding
the current regulations in the automotive sector as a possible
future prospect for upcoming two-wheeler legislation, the emissions
of particulate matter were also considered using a gravimetric
measurement method as well as a particle counter to provide
information about the mass of particulate and number of particles.
Additionally, an FTIR measurement was included to provide
information about the composition of the gaseous fraction of the
exhaust gas. In respect of the proposed EURO 3 legislation the bag
sampling was divided in two parts for all test cycles, being able
to weight the results with different factors. Beside this overall
measurement, the online recorded data of air/fuel ratio, exhaust
gas temperatures and the development of emissions over cycle time
delivers detailed information. Finally, the emitted particulate
matter was analyzed with a Thermo Gravimetric Analyzer (TGA) to
identify the mass fraction of organic carbon. The results of the
conducted tests show a wide range of different emission results
depending on engine technologies and testing conditions and can
serve as a good basis for the consideration of the current
situation on the street and the examination of proposals for
further emission regulations.