Switch-Mode CVT: Torsion Spring

A Switch-Mode Continuously Variable Transmission is the mechanical analog of a boost converter circuit. The system uses a high-speed clutch to transfer packets of energy from a flywheel to a torsion spring, which drives the output. This project focuses on the design of a torsion spring, which can deflect 180 deg., has a linear spring rate, and fits into a car transmission. It must also have low inertia, to ensure efficiency, and be back-drivable, for regenerative braking. Two unique designs were prototyped then tested using a simulated drive-train consisting of a flywheel input, an electromagnetic clutch, and a disc brake or flywheel. By comparing qualitative and quantitative characteristics of each, the group chose one design which was developed full-scale and tested