Concepts of an Active Suspension for a Sport Car

The suspension of a car is responsible for the stability of the vehicle at a wide range of different road conditions and driving manoeuvres and it therefore defines the driving safety. Further main tasks of the suspension are to provide high ride comfort for the passengers and to reduce loads of both chassis and body components. In modern passenger cars the suspension has reached a state of maturity where major improvements of either driving safety or ride comfort can only be obtained by reducing the performance of the other criteria. The vehicle suspension can only provide a compromise between these two criteria. The optimisation for driving safety would demand a totally different set-up of the suspension’s springs and dampers than it is needed to achieve the optimal ride comfort. To solve that conflict of aims in a better way, great efforts are currently made by the automotive industry in order to develop and improve active suspension systems that are able to adjust spring and damping rates in dependence on the current driving situation. Since a couple of years, the first active systems are available in passenger cars of the premium segment. Such systems allow the enhancement of both ride comfort and driving safety at the same time. The main tasks of the thesis were to determine the desired functions and product requirements for the application of an active suspension in a sports car. The resulting product requirements were the basis for the generation of design concepts for an active suspension. As a further task of the thesis, the concepts were designed up to a certain development state within a defined vehicle environment. Finally, a concept evaluation was carried out using a systems engineering approach close to the German standard VDI 2225. The results of the concept evaluation give a good overview about the performance and available potential of the different concepts. Compared to an active suspension system with the active force generator integrated in the suspension strut, a hydraulic system with master-slave cylinder principle better fulfils the product requirement and provides a higher performance, mainly due the benefits of a more variable packaging. Moreover, it could be found out that an alternative double wishbone front axle design for the investigated vehicle provides better conditions for the application of the active suspension than the current McPherson axle. The results and conclusions of that work shall help to determine the potential of the active suspension concepts and support the decision for further development steps in that certain development case