Design and modeling of a novel continuously variable transmission

Enrico Nino Manes, Purdue University

Abstract

An iterative modeling strategy is applied to low power rubber-belt continuously variable transmissions (CVTs) with the aim to (1) gain understanding of the belt-pulley force interactions, particularly for helically constrained pulley halves, and (2) generate steady-state models of CVT behavior. In addition, new designs for driver pulleys are presented and evaluated which incorporate direct electro-mechanical actuation of the CVT. Two of these new designs are built and tested to evaluate their performance and to validate the modeling work. The results of the belt-pulley force interaction research indicates that (1) the iterative modeling strategy is a viable approach for discovering the physics that dominate the behavior of the CVT, (2) the torque distribution between helically constrained pulley halves is not equal, (3) the torque distribution between helically constrained pulley halves depends very strongly on the speed difference between the pulley halves, the shear stiffness properties of the belt, and the coefficient of friction between the belt and the pulley halves, and (4) there is considerable value to pursuing further the understanding of the physics of the load sharing on helically constrained pulley halves, because most driven pulleys for rubber-belt CVTs are of this type. The results of the steady-state modeling effort for CVTs indicates that (1) helically constrained driver pulley halves are probably not viable design options, and (2) understanding the load sharing on the driven pulley halves is key to modeling the complete CVT, especially for belt engagement and low ratio operation. The prototype evaluation showed that the new designs are viable, and confirmed the modeling predictions.

Degree

Ph.D.

Advisors

Starkey, Purdue University.

Subject Area

Alternative Energy|Automotive engineering|Mechanical engineering

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