Estudo de aplicabilidade de um CVT de engrenagens planetárias por meio de análise cinemática e numérica

Abstract

The development of power transmission systems was fundamental in the consolidation of the modern automotive industry. Amongst these transmission systems, it’s worth highlighting the continuously variable transmissions (CVT), that, as the name implies, allows for a continuous variation of the speed and torque ratios between two extremes. This work explores a type of planetary gear train CVT with two degrees of freedom, in which one of the inputs is connected to an internal combustion engine (ICE) and the other to an auxiliary electric motor (EM), such that a predictable output can be obtained. For this transmission, equations for torque and rotation that describe the kinematic behavior of the system were used, and an algorithm was coded to numerically test the model’s applicability. The results show several configurations which allow the system to operate as a functional CVT, but it can be seen that the electric motor would need to have a high precision in it’s rotation control as well as to be capable of operating in relatively high speeds, even though it’s power and torque requirements remain low. Finally, it can be concluded that the studied planetary gear train CVT has promising possibilities for applications in a combustion driven passenger vehicle, but that future studies would be needed for tackling issues that exceed the scope of this work.