Bond graph dynamics of a rubber-belt continuously variable transmission

This paper analyses the system dynamics of a rubber-belt continuously variable transmission (CVT), which is widely adopted in the modem scooter powertrain systems. Dynamic mathematical models were derived from the physical configuration of the CVT directly via a bond graph approach. The CVT mainly consists of a varying-diameter driving pulley and another flange-moveable driven pulley, interconnected by a V-shaped rubber belt. Effective belt diameters of both driving and driven pulleys are controlled by a speed governor and a torque regulator, respectively. Each component was functionally analysed, employing the field theory in the bond graph technique. Mathematical equations were derived and then solved on a Matlab platform. Both static and dynamic performance simulations were examined for future electronic control implementation.