Perspective Development of Friction Continuous Variable Transmissions

The chapter proposes and analyzes a differential variable transmission (DVT) with a wide range of regulation satisfying, relatively small part of the input power to be transmitted by the friction joints, and a high mechanical efficiency and lack of “circulating” power are determined. To meet these requirements, it is to connect a classic variable transmission (CVT) as a closing unit in a differential gear mechanism with externally-internally engaging wheels and guide (AI—planetary gear) has been proposed. The transmission, as well as the conditions for the lack of “circulating” power, is determined. The synthesis of a friction variator with theoretically zero geometric sliding between the working surfaces when changing the transmission ratio is introduced, that is, the adjustment takes place with centroid rolling. The working surfaces are obtained by rotating the centroid pairs around their axes, provided that their point of intersection always lies on the common tangent of the two contours. With the help of elements of differential geometry, the first order system equations have been derived and solved in an analytical form, whose integrals uniquely define the centroid pairs.