Design and Development of a Continuously Variable Transmission (CVT) for High Efficiency and Low Weight Heavy Duty Applications

The PhD project aims to develop a new type of CVT for application on a street sweeper, using the Jarchow model which involves the use of a multi-range transmission with hydraulic first mode. The further innovative aspects of the transmission concern the simulation of an energy recovery system and the optimization of the hydraulic units efficiency through the study of innovative coatings applicable to rotating groups of pumps and hydraulic motors. As regards the development of the transmission, Simcenter Amesim simulation software was used. The results showed that applying a CVT input coupled with HSM (hydraulic starting mode) allows the use of only 6-7 kW, and therefore decreases the power of the ICE which is initially equal to 25 kW. As for the innovative coatings, both superhydrophobic coatings and textured coatings were tested in order to evaluate their applicability in the hydraulic field. For the superhydrophobic coatings the mechanical resistance was tested through scratch tests and tensile tests, while for the textured coatings tribological tests were performed to evaluate the CoF. Very promising results have been obtained from tribological tests on textured coatings, while the poor resistance and durability, shown by the failure analysis, limits the application of CVT input coupled in the hydraulic field.