Effect of a half-toroidal continuously variable unit on the dynamics of a complete powertrain: A parametric free vibration analysis

Abstract

The paper presents a simplified parametric model of a half-toroidal continuously variable unit (CVU) by using a finite element (FE) method in which the continuously variable speed unit is discretized into lumped masses and damper and spring elements. Linearized FE elements have been used to model the contact between the toroids and the rollers. All the FE elements, including the CVU model, are integrated into the complete powertrain system. Free torsional vibration analysis of the complete powertrain system has been carried out. Significant changes are observed in the natural frequencies as well as the modal shapes of the complete powertrain with respect to different gear ratios of the CVU and the various contact torsional stiffness. A potential problem with the powertrain system has also been identified, and remedial action has been proposed. The system characteristics have further been investigated with a lock-up clutch incorporated in the powertrain system.