Powertrain Efficiency Optimization of the Torotrak Infinitely Variable Transmission (IVT)

This paper reports the results arising from Torotrak's efficiency optimization program based upon the current Torotrak Series III Infinitely Variable Transmission (IVT) prototype (Fig.1), which was designed for the North American SUV (Sport Utility Vehicles) and luxury car market segment. System optimization is achieved in a number of ways including a variable hydraulic endload system, optimized variator design (in order to minimize variator power loss), minimized referred (or reflected) inertia and reduced power recirculation. The results are presented for the following attributes:

• Contact/Variator Module/Transmission efficiency.
• Powertrain specific fuel consumption (SFC).
• Fuel economy. U.S. City, Highway and Metro Highway drive cycle improvements compared to the standard Ford Expedition 4AT.
• Vehicle performance. Launch and acceleration performance compared to the standard Ford Expedition 4AT.