Design of a Modular E-Axle for All-Terrain Heavy-Duty Applications Considering Gradient Weight Transfer

Abstract

This digest summarizes the design of a 9-tonne modular e-axle for all-terrain heavy-duty vehicles. A novel method based on axle loading and gradient weight transfer is proposed for the powertrain sizing. The e-axle is designed for 4×4, 6×6 and 8×8 vehicle configurations. The e-axle maintains compatibility with an existing independent suspension system, and is suitable for use in multiple sectors, including construction vehicles, forest machinery, fire trucks and highway vehicles. A parallel in-front-of-differential topology with one motor per axle is chosen as the optimum topology. The e-axle can be used in series-hybrid, battery electric and hydrogen fuel cell powertrains. A 27-tonne 6×6 vehicle is used as a case study to determine the e-axle's tractive effort requirements for one of the possible vehicle applications. Weight transfer while climbing is considered, and the worst-case axle loading/operating conditions are used for sizing the powertrain. The on-road and off-road performance of the hybrid 6×6 vehicle is evaluated. A three-speed transmission is required to meet the vehicle performance requirements.