Development of a 6 power-roller half-toroidal CVT - Mechanism and efficiency

A half-toroidal double-cavity CVT with transmission capacity of 390 Nm was successfully commercialized in 1999. Following this success came the challenge to develop a CVT with higher torque-transmitting capability; but in a more compact size. The primary design goal is to be able to transmit 430 Nm of torque using six power rollers instead of the conventional four-roller design. This CVT has new mechanical and design issues to ensure equal torque transmission among all six power rollers, and to ensure stability of the speed ratio control mechanism. This paper describes the synchronizing mechanism of these six power rollers and the measurement of power-roller motion and efficiency.