The European emission legislation is being adopted in other countries world-wide, in 2010 Euro 4 will be introduced in China and India.
Euro 4 emission compliance normally requires exhaust gas after treatment systems to be applied. With the high injection pressure offered by advanced fuel injection technology, and with AVL's combustion knowledge, exhaust after treatment system requirements can be minimized.
A dynamically controlled cooled EGR system is applied. For a combustion process optimized for high EGR rates, the air management system is important. The control strategy for a highly flexible fuel injection system, the metering of recirculated exhaust gas and for the variable geometry turbine (needed only for high performance engines) must consider transient conditions.
An OxiCat is added to support long term emission stability. Test results show a 10 to 20% margin to the legislated Euro 4 emissions limits. The fuel efficiency is equal to Euro 3 compliant engines without EGR.
The combustion system must be developed to be tolerant of high EGR rates with low soot-in-oil and to be insensitive regarding deterioration and production tolerances, and must be validated for a wide range of ambient boundary conditions. The heat rejection due to the higher EGR rates compared to Euro 3 engines requires an increase in the radiator cooling capacity.