CVT stands for Continuously Variable Transmission. This technology allows the transfer of power through a range of speed/torque ratios from engine input to output; this transfer of power happens continuously and without interruption, which allows for the operation at the lowest possible speed and the highest possible load, partially avoiding the low efficiency region of the engine map. The contrast is between both manual transition and conventional automatic transmission that use discrete ratios and usually disengage when changing speed or load. Using CVT will resolve the compromises in reliability, durability, efficiency and controllability with low cost.

CVT Benefits:

• No gear shift
• Continuous transmission of torque
• Control of engine speed independently of vehicle speed
• Ability to operate engine at peak power over wider range of vehicle speeds
• Ability to operate at most fuel efficient point for required output power

Control Objectives:

CVT Disadvantages:

• Mechanical efficiency of variator
• Parasitic efficiency of transmission system and controller
• Compromise between fuel economy and torque margin to achieve driveability (avoiding elastic band feel)

CVT Efficiency:

• All CVT variators have losses due to the power transfer which appears as a speed or slip
• CVTs are hydraulically controlled and the pump takes power as in a conventional automatic transmission
• Efficiency is more variable for CVT than geared discrete ratio systems