Design of an epicycloidal geartrain for a four-wheel drive Formula Student electric vehicle.

Formula Student or Formula SAE is a competition between student teams in charge of designing, building and testing a new formula-style race car per each season. Those vehicles are divided into three classes: Combustion, Electric and Driverless. The competition consists in both a static part where the design, the cost-performance relationship and the marketing aspects of the project are evaluated by the judges and a dynamic part where the vehicle must race in four different type of events. Each dynamic event highlights different aspects of the car performance, from standstill acceleration to lateral grip, reliability and energy efficiency. In 2005 Politecnico di Torino’s Formula Student team called Squadra Corse PoliTo was founded and since then fifteen cars have been built. Seven of them are powered by an Internal Combustion Engine, one is a Hybrid Electric Vehicle, while the last six cars built are Battery Electric Vehicles. SC18integrale is the vehicle presented by Squadra Corse PoliTo for the 2018/2019 racing season. It is a four-wheel drive Battery Electric Vehicle with four independent in-wheel motors. The motors need a devoted gearbox in order to match the vehicle’s traction requirement. Due to the in-wheel position both the weight and the volume of the gearbox are critical parameters. The weight impacts on the unsprung masses, while a small volume is beneficial for suspension hardpoints package. In this thesis the project of the SC18integrale epicycloidal transmission is presented in all its aspects, from the concept design until the track validation. The first phase of the design after the target has been set is the development of the transmission model and of the gear life calculation, carried by KISSsoft and KISSsys software tools, then the integration of the gearbox with the wheel assembly is studied. Finally the mechanical design of each component and of the assembly is detailed. Catia V5 is the software used for the development of CAD models while Altair Hyperworks the software used to carry the structural FEA. The experimental validation is done on track during the pre-season tests, the racing events and the post-season test phase.