Abstract
Keywords:
continuously variable transmission, simulation, power train modeling, efficiency, CVT
Abstract
Modern control techniques allow drive train components to operate under more optimal operating conditions than previously possible. Powerful electric servo-motors and modern controllers are necessary for the development and refinement of automated transmissions like the Double Clutch Transmission and the Continuously Variable Transmission, in order to arrive at fuel consumption, comfort and performance levels that are expected from today's power trains. In order to benchmark the effect of various improvement measures on fuel economy at an early stage in the development process based on above-mentioned technologies, detailed simulations can be made. This paper describes the results of a simulation study of the effects on efficiency and fuel economy of a vehicle equipped with a CVT, resulting from the introduction of the following new variator actuation and control techniques [1]:
• Replacement of the high pressure hydraulic pump by a servo-electromechanical actuation system (EMPAct) and
• Introduction of variator slip control
For this study, the TNO-Advance simulation package is used, in which detailed models of all loss contributions of the CVT were implemented. The fuel economy benefit of the EMPAct system in comparison to the conventional CVT is shown to be substantial, about 6% on the NEDC cycle.