Design evolution of Novel Subframe for a Multilink Rear Suspension of an e-SUV

As there is a major shift in customer demand for energy efficient transportation, electric vehicle development has taken prominence worldwide as they provide pollution free and noise free mobility. The subframe being an important structural component of the chassis system, the designers always find it challenging to provide best-in-class rear subframe (RSF) optimized in terms of cost and weight within the available packaging space especially in an electric sport vehicular boundary. The main function of rear subframe is to transmit forces to BIW without deflections hence for this it should be very stiff. At the same time, it should be light in weight and simpler to industrialize. In the present work, the design evolution of a novel sub-frame assembly for a multilink rear suspension of a born electric sports utility vehicle (e-SUV) platform is detailed. With increased rear axle weight contributed by the battery weight and rear mounted motor, the design evolution of the rear subframe (RSF) to overcome the inherent challenges is elaborated. The present RSF assembly consists of a uniquely designed cross member structure and a novel motor mounting concept on the long member for the complexity in the finalized hard points for the suspension linkages, to meet the electric vehicle packaging requirement. The RSF was designed for light weighting to withstand the increased stresses due to 20% higher vehicle weight of the e-SUV compared to the conventional internal combustion engine (ICE) vehicle. Furthermore, the weight of the RSF was optimized by using a lower sheet metal panel thickness of 1.6mm with conventional sheet metal material grade to reduce the cost and weight by 10% without compromising the durability and NVH targets. Strategic arrangements of reinforcements and novel construction aided the RSF to overcome the handicap of increased stresses and reduced weight. Thus, the design evolution of the novel RSF assembly is detailed in the present work.