Driving Safety of Electric Vehicles with Unconventional Service Brake Topology


ISBN 9783844095623
168 Seiten, Taschenbuch/Paperback
CHF 67.50
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The increasing market share of electric vehicles (EVs) leads to novel questions regarding brake system design. To maximise efficiency and cover strict particulate emission standards, a novel and disruptive braking system concept could be beneficial, in which the conventional friction brakes of the rear axle are replaced by a central axle brake module integrated into the driveline. This arrangement eliminates wheel-individual service brake intervention on the rear axle, which are generally used for electronic stability control (ESC). This thesis discusses the driving dynamics potentials and challenges of such a system.



To demonstrate the lateral dynamics potential of the new brake system topology, a proposal for a dedicated vehicle dynamics controller (VDC) is introduced into a software-in-the-loop simulation environment. The investigations on lateral dynamics identify certain limitations in under- and over-steering-critical situations. Performance degradations during braking and acceleration on inhomogeneous (µ-split) surface are also discussed. Especially the acceleration case represents a clear physical limitation that can only be solved by bespoke hardware measures, e.g. limited slip differentials (LSDs).



This work puts special emphasis on the development of a methodology for the assessment and selection of passive LSDs. It extends known approaches for the quantification of driving dynamics properties such as the Milliken-Moment-Method, but also considers the impact of LSDs in daily driving conditions. As an alternative, a novel parking brake concept is presented that combines conventional parking brake functionality but also supports climbing ability on µ-split. This multi-disc brake concept is mounted on the differential housing and is acting on the axle shafts.
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