Design and Prove of Concept of an Innovative Active Fluid Suspension System

The content of this work is the presentation of the prototype of a new active suspension system with an active air spring. As being part of the Collaborative Research Unit SFB805 “Control of Uncertainties in Load-Carrying Structures in Mechanical Engineering”, funded by the Deutsche Forschungsgemeinschaft DFG, the presented active air suspension strut is the first result of the attempt to implement the following requirements to an active suspension system: • Harshness and wear: Reduced coulomb friction, i.e. no dynamic seal. • Reduced complexity • Plug and drive solution: Connected to the electrical power infrastructure of the vehicle. • Vehicle and customer application by software and not by hardware adaption. These requirements were defined at the very beginning of the project to address uncertainties in the life cycle of the product and the market needs. The basic concept of the active suspension strut is the dynamic alteration of the load carrying area. This load carrying area is the area A of a roller bellows and defined by A:=F/(p-pₐ). F denotes the resulting force of the strut, p the absolute gas pressure and pₐ the ambient pressure. The alteration of this load carrying area is realized by a mechanical power transmission, from a rotational movement to four radial translated piston segments. Due to the radial movement of the piston segments, the load carrying area increases and so does finally the axial compression force F. The prototype presented in this paper serves as a demonstrator to prove the concept of the shiftable piston segments. This prototype is designed to gather information about the static and dynamic behavior of the roller bellows. Measurements show the feasibility of the concept and the interrelationship between the piston diameter and the resulting compression force