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A Method for Developing Specific Reference Cycles or Alternatively Test Cases for Commercial Vehicles and Their Auxiliary Systems
Abstract:
In contrast to passenger cars, commercial vehicles exist in many layouts for different customer applications. The Daimler AG provides with their Mercedes Benz Trucks a product portfolio of 6 commercial vehicles (Econic, Atego, Axor, Actros, Zetros, Unimog), which are available in a multiplicity of model variants.
Therefore, the well-known driving cycles of passenger cars such as NEDC (Europe), the 10-15 mode (Japan), the FTP & FTP75 (USA) and others cannot be used in regard to fuel consumption or dimensioning of a commercial vehicle [1, 6, 15]. A diversification of type and usage of the commercial vehicles is obligatory necessary, as already shown in publications of Holloh et al. [10]
However, this paper offers a method which uses collected data from customers, in order to develop objective reference cycles or test cases. This described method can be equally used for both, creating the reference cycles of commercial vehicles mentioned above, as well as passenger cars. Especially when moving on to the more complex operating strategies and operating points or vehicles with many different auxiliary systems, this method is an even better assistant to create possible impartial test cases. With the help of these test cases, systems can be analyzed in respect to their behaviour regarding different quantities, like emissions of the combustion engine, power consumption of different auxiliary systems and others. The most important aspect of this method is that it is able to take the interdependency of different auxiliary systems to each other as well as to the whole vehicle into account by classifying operating points with an arbitrary wide range of different operating conditions and their respective frequencies.
In contrast to the World Heavy Duty Cycle (WHDC) this method does not only analyze the engine [14] but also the whole vehicle. The reference cycles or test cases developed this way can be used for (simple) testing or determination of new (sub-) systems, which are comprehensible and representative for different particular customer applications. However, this method does not take misuse maneuvers, which may damage the (sub-) systems, into account but only the most likely operating points during customer operation.
This paper describes the developed method using the example of a light duty vehicle as used in distribution of goods and its possibilities for generating an impartial representative reference cycle.