Search Results

After some general considerations about the extended use of Continuously Variable Transmissions (CVT's) for lightweight vehicles, which clearly show the two-fold advantage, the first of a very simple, compact and well integrated with engine transmission, the second to make possible the calibration of the engine only in a limited operating range, the efficiency of this type of transmission is investigated. A theoretical analysis of CVTs is carried out, in order to identify all the characterizing physical parameters. The design of a specific test rig is then presented. Since the transmission ratio depends on forces equilibrium, the centerline force appears to be the most important characterizing parameter. The new system is particularly conceived for small power output, i.e. minimum friction losses.

The future urban mobility strategies, especially in cities with high population density, include the individual transportation means as one of the main components to contribute to the solution of the two fundamental problems, namely the traffic concentration and the individual satisfaction. Following the consolidated trend, the 2000's vehicles shall be characterized by extremely reduced environmental impact in terms of pollutant emissions, noise, fuel consumption (low carbon dioxide production). In this sense the two-wheelers appear the most favorable candidate provided that a suitable propulsive unit is available. The present work describes the development of a propulsive unit characterized by a direct injected two-stroke engine with FAST technology, an electronic engine management system and a very efficient CVT transmission.