Book Description

The main goal of approval test cycles should be to provide a reliable basis for an honest raking of different engines and engine technologies, both relative to each other and to the limits that are set by the legislative authorities. The engine load during the test cycle, therefore, must to a certain extent represent real-life conditions. Most existing approval test cycles indeed seem to have been based to some degree upon measured or statistical data from real- life, and are therefore expected to be representative of actual vehicle use. It appears very hard, however, to find out the exact background or the development process of any of the cycles. In large study that was carried out at the TNO Road-Vehicles Research Institute in cooperation with the Graz Technical University, the representativity of existing approval test cycles was determined, with a particular emphasis on test cycles for heavy duty vehicles, and rules were formulated for the development of new representative cycles. The comparison between the engine load during heavy duty approval test cycles and that in real-life is based on on-road measurement data from all kinds of heavy-duty vehicles. Using statistics on the use of heavy-duty vehicles in practice, these data are used to define "the average heavy-duty engine load in real-life". The results of the comparison between the load in the so defined practice and that during approval tests show, amongst others, that the forthcoming European Stationary Cycle very well represents the average European heavy-duty vehicle use. On the other hand it shows that the new European Transient Cycle shows some non-representative characteristics. This underlines that the use of well founded background research on representative driving cycles and heavy-duty engine use is a primary condition for the development of driving cycles and approval test cycles.