Increasing load capacity of differential gears using a restriction free design method

Abstract The development of differential gearboxes for electric vehicles presents new challenges due to the increased torque from electric motors. Traditional bevel gear manufacturing methods, such as milling and forging, impose constraints on gear geometry, influencing load capacity and durability. This paper introduces a restriction-free design method for differential bevel gears using a novel calculation process implemented in the software next|gear. The proposed method allows for the section-wise definition of face gears, enabling a more precise and application-oriented adaptation of tooth geometry. A key element of this approach is the introduction of a conjugation strategy that optimizes the interaction between pinion and side gears. By employing Non-Uniform Rational B‑Splines (NURBS) for flank modifications, the method ensures smooth transitions and tailored load distribution across the contact area. Finite Element Analysis (FEA) is used to validate the impact of the new design on load capacity. The results show that the new method significantly reduces maximum contact stress and principal stresses in the tooth root, leading to improved durability and efficiency. Compared to conventionally designed gears, the new approach achieves a more homogeneous stress distribution, thereby enhancing performance under varying load conditions. This paper demonstrates that by leveraging the design freedom offered by forging, differential bevel gears can be optimized beyond traditional limitations, leading to increased load capacity and operational reliability.