Multi-Link Torsion Axle (MLTA) - A New Rear Axle Concept for Battery Electric Vehicles 2021-01-0929

A typical rear axle in front-wheel driven Battery Electric Vehicles (BEVs) of the compact and subcompact segments is the twist-beam axle. Its transversal beam requires major lateral and vertical package space and is a limiting factor of the battery package in the underbody.

In this work a new rear axle concept the so-called Multi-Link Torsion Axle (MLTA) is introduced. The goal of the new concept is to reposition the transversal beam of common twist-beam axles rewards to the wheel centres. This opens up an increased and connected volume in the underbody of the vehicle that can directly be allocated to the battery design space. In this way, the battery space can be increased by up to 30% in comparison to the conventional twist beam axle. To keep a desirable pitching behaviour under braking the reversed twist-beam is integrated in a longitudinal Watt’s linkage which enables an instantaneous centre of motion in front of the wheel. Other advantages of the concept are a structural toe-in behaviour due to lateral forces, a decoupling of lateral and longitudinal elasto-kinematics as well as an integrated impact protection by the components of the MLTA in case of a side or rear crash.

This paper shall introduce the new rear axle concept and its potential regarding the packaging of BEVs as well as the kinematic optimisation of the new mechanism. Additionally, multi-body simulations are used to compare the MLTA to a common twist-beam axle (TBA) to show the expected performance of the new concept.