Acceleration simulation of a vehicle with a continuously variable power split transmission

Zhijian Lu, West Virginia University


A continuously variable transmission system has often been considered for automobiles. It offers the potential to allow the engine to operate at peak efficiency without disturbing the driver with discrete shifts. The application of CVTs in automobiles has been attempted for many years. This concept has been rapidly developed in the last twenty years. The shaft-to-shaft belt CVT is now the most commonly used CVT product in the automobiles. The main drawback of this kind of CVT is limited torque capacity and the modest power efficiency. This prevents the belt CVT from being used in the vehicles with large displacement engines.;A new concept involves a power split function. A continuously variable power split transmission (CVPST) is created by combining a V-belt CVT with a planetary gear train. The V-belt CVT is used as a control unit. By using this technology, the power flowing through the belt at low speeds is less than 50 percent. A step-up gearbox is used to expand the CVPST ratio for the applications in automobiles. The CVPST enhances the transmission torque capacity and improves the overall transmission efficiency.;This thesis involves the study of the CVPST system. Based on the analysis of the vehicle dynamics and the CVPST system, a computer program is developed. By using this program, the CVPST system design can be accomplished. The vehicle acceleration can be simulated to evaluate the CVPST performance. The acceleration simulation of vehicles equipped with standard (manual) and automatic transmissions is also possible to be carried out.