Study of Shaft Drive Continuously Variable Transmission

3rd Report, Increase of Torque-Transmitted Efficiency by Backup Roller

Abstract

The novel mechanism CVT (Shaft Drive CVT) was developed by the authors. The input and output shafts with conical disks are parallel and an idler shaft having conical rollers at both ends is placed perpendicular to the input/output shafts. This idler shaft transmits torque from the input shaft to the output shaft and its linear motion produces the speed variation by changing the contact point between the input/output disk and the idler roller. To improve the efficiency of the Shaft Drive CVT, the backup conical roller mechanism was devised. It is mounted to the opposite side of the idler roller, and contact with the input/output disk and the backup disk as well as the idler roller. It reduces the bearing loss of the input/output shaft because it supports the axial force of idler roller at the opposite side. The amount of transmitted torque is enlarged by this mechanism. The effectiveness of the backup rollers was confirmed by the experiments, and the efficiency of 98.4% was obtained at high ratio. The efficiency of 5 to 7 percentage points was improved on every speed ratio comparing with the case without backup rollers.