Concept Design of a Parking Brake Module for Standstill Management and Wheel Individual Brake Torque Generation for EVs with Unconventional Service Brake Topology

For electric vehicles the ability for regenerative braking reduces the use of friction brakes. Particularly on the rear axle of vehicles with reduced dynamic requirements such as urban vehicles, this can offer a potential for downsizing or, in extreme cases, even the elimination of the friction brakes on the rear axle. Due to the fact that the rear axle service brakes also represent the typical parking brake location in SoA (State-of-Art) vehicles, a rigorous rethinking of the parking brake concept is necessary to incorporate safe vehicle standstill management for such novel brake system topology. This research study introduces a novel parking brake design that covers SoA but also legal requirements while retaining potentials associated with the elimination of the rear service brakes such as cost and packaging. Also, the novel approach aims for a combination of traditional parking brake functionality and certain dynamic brake torques that are typically delivered by wheel individual service brake interventions. For instance, an uneven brake torque distribution to the wheels is desirable for accelerating on inhomogeneous road surfaces (μ-split situations), which is negatively affected by eliminating the service brakes. Beginning with a systematic comparison of multiple parking brake topologies that evaluates different locations for the parking brake in the driven axle’s powertrain, a promising approach is designed and dimensioned in detail.