Mehrlenker-Torsionsachse – Modellierung, Entwicklung und Erprobung einer bauraumsparenden Verbundhinterachse für eine verbesserte Batterieintegration in BEVs der Kleinwagenklasse

The integration of large battery packs into battery electric vehicles poses a particular challenge in the compact vehicle class, as available packagespace is limited by conventional axle designs such as the twist beam axle. To address
this issue, the Multi-Link Torsion Axle (MLTA) was developed at the Institute of Automotive Lightweight Design. Its novel kinematic behavior enables optimized vehicle integration and creates additional space for the battery package.
This work deals with the modeling, development, and experimental evaluation of the MLTA, with a focus on its elastokinematic behavior. For this purpose, an MBS solver was developed that is capable of modeling and analyzing both the kinematics and elastokinematics of suspension systems. Based on this solver, an MBS model of the MLTA was created. In the next step, a prototype axle was designed, built, and integrated into a test vehicle.
The experimental evaluation included KnC-measurements, objective driving tests, and subjective evaluation by experienced test drivers and untrained everyday drivers. For comparison, a production vehicle equipped with additional masses was used to emulate the characteristic mass and center-of-gravity properties of a BEV.
The KnC results confirm the potential of the MLTA. Kinematic advantages were observed particularly in wheel-center recession and anti-lift behavior. Weaknesses were found in camber compliance due to deviations of the prototype bushings from the target specifications. However, simulation results show that the desired compliance behavior can be achieved if the specified bushing characteristics are met. Objective driving tests show high agility and a significantly reduced longitudinal acceleration during obstacle crossing compared to the reference suspension. Compared to the reference axle, the MLTA received lower ratings in the subjective evaluation, clearly indicating the need for series-level tuning in future development.