Investigation of NVH Characteristics of a Downsizing Vehicle 2014-01-2042

The automotive industry permanently enhances Downsizing concepts due to environmental commitments and energy consumption concerns. Even in the category of city- and supermini-cars, great efforts are made for the development of highly charged engines with small displacement. So far the main focus of these developments is set on the reduction of CO₂ emissions and fuel consumption. However these are not the only aspects, which have to be fulfilled by the vehicle in order to meet the demands of the customers and to be successful in competition. The NVH characteristics of such Downsizing vehicles have to match a class-specific level, which can only be achieved by additional measures. Regarding this, a view of the dynamic behavior of the entire vehicle is required.

At the Institut für Kraftfahrwesen Aachen (ika) the potential for reducing fuel consumption and CO₂ emissions of a Downsizing concept is investigated using a city-car as reference. For this purpose, among other things, the three-cylinder-engine of the reference car is replaced by a highly charged two-cylinder-engine with same power output but smaller displacement. Apart from the environmental aspects the NVH behavior of the Downsizing concept is investigated and optimized in a holistic approach including measurements and simulations. Focus of this paper is the analysis and the improvement of the NVH-phenomenon “shuffle”, which is excited by load change procedures of the two-cylinder-engine. With the help of a simulation model several measures for reducing “shuffle” are evaluated with respect to the acceleration of the vehicle. The measurements, the developed simulation model and the corresponding results are represented in this paper.