A Zero-Spin Design Methodology for Transmission Components Generatrix in Traction Drive Continuously Variable Transmissions

With the advantages of high torque and low noise, traction drive continuously variable transmissions (TDCVTs) have a promising application in future vehicles. However, their efficiency is limited by spin losses caused by the different speed distributions between the contact areas of the traction. To overcome this shortcoming, this paper proposes a novel zero-spin design methodology applicable to any type of TDCVTs. The methodology analyzes the features of TDCVTs in terms of the variation of contact position and the shifting motion of traction components. It also establishes a mathematical model resulting in differential equations, whose general solution is the substitute for the equation of traction components generatrix. After applications of the methodology to two original TDCVTs, two zero-spin TDCVTs are proposed. A computational method of spin ratios, which are in direct proportion to spin losses, of four TDCVTs is introduced. The results of comparisons demonstrate that the proposed methodology can dramatically reduce the spin losses.