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Cone CVTs
This category embeds all CVTs made up of one or more conical bodies which function together along their respective generatrices in order to achieve the variation.
In the single cone type, there is a revolving body (a wheel) that moves on the generatrix of the cone, thereby creating the variation between the inferior and the superior diameter of the cone.
In those CVTs comprising two or more cones (see GIF website), the cones are placed in opposition, with the smaller diameter of one cone facing the larger diameter of the other cone. The contact between all the possible diameters of the two cones is made by a ring interposed between the cones. The variation is obtained by moving the ring along the generatrix of the two cones.
In a CVT with oscillating cones, the torque is transmitted via friction from a variable number of cones ( according to the torque to be transmitted ) to a central, barrel-shaped hub. The side surface of the hub is convex according to a determined radius of curvature, which is smaller than the concavity radius of the cones. In this way, there will be only one ( theoretical ) contact point between each cone and the hub.
A revolutionary new CVT, the Warko, using this technology, was presented in Berlin during the 6th International CTI Symposium of Innovative Automotive Transmissions, on 3-7 December 2007.
A particular characteristic of the Warko is absence of a clutch: the engine is always connected to the wheels, and the rear drive is obtained by means of an epicyclic system in output. This system, named “power split”, allows the condition of geared neutral or "zero Dynamic": when the engine turns( connected to the sun gear of the epicyclic system), the variator ( which rotates the ring of the epicyclic system in the opposite sense to the sun gear), in a particular position of its range, will compensate for the engine rotation, having zero turns in output ( planetary = the output of the system ). As a consequence, the satellite gears roll within an internal ring gear.
Modularity, wide ratio range (= 9), high efficiency (95%), high torque capability (up to 500 Nm) and compactness (less than 36 cm length for 31 cm diameter and 60 kg) are the most important characteristics of the Warko.
The same device, with the same identical cone, in different configurations, covers the 90% of the engines produced all over the world, with a power range that goes from 60 to 200 Hp, gasoline and diesel. As a consequence, being manufactured by the millions, its production costs will be comparable to mechanical transmission costs.
