Takashi Imanishi

The Latest Technology of Traction Drive Half-Toroidal CVT

In recent years, CVTs (Continuously Variable Transmission) for automobiles has been steadily increasing in the background of global environmental issue. Improvements of fuel economy of the vehicles are one of the key items for reducing the CO2 gas generation. Comparing to conventional step gear transmissions, the continuously variable ratio changing provides the better fuel consumption with the optimized operation of internal combustion engines. Traction drive CVT has the capability especially for high power automotive applications. In November 1999, traction drive half-toroidal CVT units shown in Fig. 1, were installed in mass-production vehicles for the first time in the worldai][1]. This CVT has a simple structure, but it had not been commercialized for 120 years mainly because of poor endurance performance. In this application, one traction contact point is transmitting power of more than 50kW. A lot of tribological technologies have been provided to achieve such a large power transmission.