A passively regulated full-toroidal continuously variable transmission

This work presents a novel self-regulated toroidal continuously variable transmission (ART-CVT) that features a passive control of the speed ratio, achieved with no need for supplementary actuation system. The proposed transmission system is based on a full-toroidal CVT topology which combines a specially shaped geometry of the conjugate profiles with a pre-load system to create a correlation between the speed ratio and the input torque. Such a solution is conceived to reduce the complexity that is usually associated with active regulated systems and it is envisaged to be applicable to low-power/low-cost systems such as small wind turbines, powered-two-wheelers, or bicycles. We illustrate a simplified mathematical model that is able to describe the response of the proposed ART-CVT in quasi-static steady-state operational conditions. Additionally, we propose a case-study in a realistic scenario: a design for an ART-CVT that matches the requirements of a low-power wind turbine coupled with a synchronous generator directly connected to the grid without additional power converters. The achieved results show that an ART-CVT is able to reach working conditions close to the maximum theoretical aerodynamic performance without any active regulation.