EXPERIENCES FROM THE SWEDISH NATIONAL PROGRAM FOR ON–BOARD MEASUREMENT OF HEAVY–DUTY VEHICLES

Abstract:

Real life emissions are becoming more and more interesting, and technology to carry out high quality testing on-road is developing. Regulatory systems for certification of HD engines are mainly focusing on the emission performance of the engine instead of the vehicle. More electronic controlled components are used in modern diesel engines, engine and aftertreatment systems in combination are introduced to meet set requirements and “hybridization” of HDV´s is a hot topic. This will make it possible for manufacturer to design unique calibrations for engine management system covering almost every application. But is this really the case? Further, it must be verified whether late engine technology operates as expected during real life conditions compared to certification tests.

Since many years AVL MTC has been working with correlation between chassis dynamometer testing and engine testing in benches. In 2004, the program was extended to also cover the use of portable emission measurement systems (PEMS) when testing vehicles on-road.

On-road emission measurement can be used for different purposes. In a European project coordinated by JRC (EU Joint Research Center, Ispra, Italy), in-service testing of heavy-duty vehicles is carried out in pilot projects (PEMS-Pilot Projects). In Sweden, a national program for in-use service testing of HDV is in place since 2006 and other related activities are ongoing for development of “real life” emission factors and validation of emission performance from late engine technologies using EGR and SCR systems to meet the set standards.

The results underline that there is a differences in emission behavior when vehicles are tested on-road compared with testing engines/vehicles for certification purposes. When testing vehicles on the road, the selection of test route is essential for the emission results. When testing is carried out for development of “local” emission factors it can happen that the emission results are much higher then expected, despite that the engine itself meet emission standards when tested according to regulation.

Sweden accepts the highest gross vehicle weight among European countries. Recently, trucks with a gross combination weight of around 60 tons have been tested on-road.

Since 2004, heavy-duty vehicles meeting Euro I – Euro V requirements have been tested in applications such as city buses, medium size heavy duty trucks and heavy heavy-duty trucks.