Abstract
Type approval of engines for heavy-duty vehicle applications is based on engine dynamometer testing. Even if the latest duty-cycle is transient and in principle based on driving in urban, road and motorway traffic, it does not adequately reflect the multiplicity of applications that heavy vehicles are used. The duty-cycle of an urban bus is totally different from the driving of a long-haul truck-trailer combination. One major deficit is the lack of information regarding fuel consumption and subsequent CO2-emissions, because current type approval protocol does not address energy use at all, only the air quality emissions. Furthermore, as the emissions legislation and limit values are based on specific emissions, relatively little is known of the real on-road emissions in relation to kilometres driven and tonnes of goods transported. To create this kind of information VTT has since 2002 worked with a full-scale chassis dynamometer suitable for simulations of heavy truck and bus operations. The facility allows accurate determination of energy consumption and exhaust pollution over any transient duty-cycle. Furthermore, even uphill/downhill gradients are included, allowing very realistic simulations of real-world routes. GVW (gross vehicle weight) up to 60 tonnes can be simulated. Over a ten-year period VTT has tested more than 100 different trucks and more than 150 different busses. The database includes vehicles in all Euro classes from EU I to EU VI, and EEV for the busses. Size classes for HGV range from 18 tonnes up to 60 tonnes of gross vehicle weight. Many vehicles has been tested with several differ-ent payloads, and using multiple duty-cycles. The database allows us to create “generic” vehicles according to size, duty-cycle and level of emissions certification. KEYWORDS –TRUCK, BUS, EMISSIONS, MEASUREMENT, DUTY CYCLE