Design of a McPherson Strut based split link front suspension for a higher rear to front weight ratio SUV with minimal turning circle diameter.

Generally, in a rear wheel driven electric vehicle the weight distribution is greater in the rear as compared to front. This high rear to front weight ratio is prone to oversteer behavior during high-speed cornering. Oversteer deteriorates vehicle handling & is a critical safety concern in passenger cars. To compensate this inherent oversteer nature of such vehicles & produce required understeer gradient, the steering rack is placed ahead of the wheel center. The forward placement of steering rack induces toe-out behavior due to lateral toe compliance resulting in understeer behavior. Though this compensation measure produces lower Ackermann percentage resulting in higher turning circle diameter. A high turning circle diameter deteriorates vehicle maneuverability. This paper proposes a validated, patented & productionized design meant to obtain ideal understeer gradient with minimal turning circle diameter & a high suspension travel (approximately 185 mm). This is achieved through utilization of split link technology in a McPherson strut suspension & forward positioned steering rack. This paper elaborates on how through split links a variable knuckle arm length is achieved. This variable knuckle arm length facilitates in producing a higher rate of difference between inner to outer wheel steering turn angle thus effectively increasing Ackermann percentage resulting in low TCD. Furthermore, the proposed design allows decoupling of longitudinal & lateral compliance due to splitting of lower control arm into two links. This overall improves longitudinal compliance resulting in better ride plushness during bumps without compromising handling characteristics of the vehicle. The above-mentioned advantages are explained through kinematics & compliances results. The suspension geometry necessary for achieving above mentioned objectives requires compact spatial arrangement of ball joints of both split links raising packaging concerns. A unique arrangement & joinery of ball joint with respect to steering knuckle for eliminating dynamic packaging issues is also discussed. The optimization of profile & cross section of split links specifically to improve critical buckling load to prevent buckling is also elaborated through CAE results.