Experimental Investigations of Forced Air Cooling for Continuously Variable Transmission (CVT)

In the recent past, the non-geared (step less) transmission scooters are becoming more popular mainly due to ease of driving without gear shift hassle. Typically these scooters transmit the power through a continuously variable transmission commonly called as CVT. The CVT of a scooter is generally air cooled and located in a protective chamber. This chamber reduces the heat transfers between the CVT and the atmosphere. The temperature reached inside the chamber during the operation of the CVT is quite high, especially when the CVT is operated in hot environment. This may reduce the service life of the drive-belt since it generally decreases when the average operating temperature increases. Along with V belt, high temperature inside CVT chamber also deteriorates durability of centrifugal clutch liner, bush, centrifugal rollers and other CVT parts. Therefore, it is necessary to limit the operating temperature of the CVT system.

The main objective of this research is to investigate temperature of CVT parts and optimize the air flow path and air flow rate inside CVT chamber. Tests were carried out to measure the surface temperature distribution of CVT parts and air temperature distribution inside CVT chamber under different vehicle test conditions. This study has contributed to measure the temperature and identify the main causes affecting CVT cooling. Results with improved CVT chamber cooling were also plotted.