An extremely compact, high torque continuously variable power transmission for large hybrid terrain vehicles

The planetary gear hybrid power train (PGHP) is known as one of the most compact speed reduction system. The PGHCVT (Planetary Gear Hybrid Continuous Variable Transmission) introduced in this paper varies continuously the reduction ratio by using an additional external, speed controlled, power source to the traditional thermal engine. The movement of the annular gear in the opposite way to the carrier P (Figure-2). In this way, when the annular is still, the minimum speed ratio is achieved. As the annular speeds up the speed ratio increases up to obtaining a still carrier. Theoretically, reverse ratio is possible by further increasing annular speed. However, speed limits on the annular gearing usually prevent the obtainment of a still carrier or a reverse motion. In any case, even a single stage planetary gearing obtains an extremely large transmission ratio variation. An example of 4WD (four Wheel Drive) vehicle is introduced in this paper with a preliminary design of the gearing system. The efficiency of the transmission is extremely high due to the very limited number of sliding contacts.