Preliminary Design and Validation of a 3D-Printed Continuously Variable Transmission for an Electric Vehicle Prototype

This paper aims to present the developments on the design of a new 3D-printed continuously variable transmission (CVT) developed for an electric vehicle prototype competing in Shell Eco-marathon electric battery category, a world-wide energy efficiency competition sponsored by Shell. The proposed system is composed of a polymeric conic pulley assembled in the motor axle and directly coupled to the rear tire of the vehicle. The conical shape allows to implement a continuous variation of the pulley diameter in contact with the tire. The motor with the pulley was mounted over a board with linear bearings, allowing the speed ratio to change by moving the board laterally. In the manufacturing process, additive manufacturing tools such as 3D printing by fused deposition modeling were used to simplify the manufacturing process reducing costs and time. A computational simulation model of the vehicle prototype with the CVT was also created in Matlab/Simulink environment and the simulated results were compared to experimental data acquired with the manufactured variable transmission. The designed powertrain allows mass reduction, better vehicle performance and increased speed range output using a simple and easily manufactured 3D-printed solution.