Application of Multi-objective Optimization for Optimization of Half-toroidal Continuously Variable Transmission

Among different goals defined in vehicle design process, fuel consumption (FC) is one of the most important objectives, which significantly has taken into account lately, both by the customers and vehicle manufacturers. One of the significant parameters which impacts the vehicle FC is the efficiency of vehicle's power train. In this paper, a half-toroidal continuously variable transmission (CVT) is considered as the vehicle power train. Its efficiency is sensitive to its geometry, and variation of its geometry can result the vehicle FC reduction. On the other hand, geometry variation affects its weight and fatigue life, which are considered as major contributing factors in the power train design. This paper aims to optimize half-toroidal CVT in order to minimize its weight, FC of the vehicle equipped with it, and provide the desired fatigue life. After introducing half-toroidal CVT, the method of calculating the mentioned objective functions is presented. A specific importance weight for each objective is considered. These weights are functions of their related objectives. A single objective optimization is implemented for each objective, and their optimal values are obtained. Then, these objectives are optimized simultaneously using Global Criterion method.