Constant Power Continuously Variable Transmission (CP-CVT): Operating Principle and Analysis

Abstract

The paper is the first of a series of papers that present an original constant power continuously variable transmission (CP-CVT) traction drive. This paper presents the basic functional principle and demonstrates the device’s characteristics of constant power. The device belongs to the well-known toroidal traction drive family. It comprises of two input discs, one conical and the other toroidal, a conical output disc, and a number of spherical balls. The rotation axis of each ball is self-adjusted according to its geometrical position relative to the input and output discs. A variation of the output torque makes the balls change their position relative to the discs and thus causes a change of the transmission ratio. The kinematics and dynamics of the balls are first performed and then the formulas that relate the power transmitted to the kinematics and geometric parameters are deducted. Finally it is concluded that the CP-CVT presented offers good functional steady power characteristics that could fit the automobile industry requirements.