Optimization of a Continuously Variable Transmission with Emission Constraints

An optimization technique was developed which can be used to compute the optimal control strategy for an engine-continuously variable transmission (CVT) configuration subject to emission constraints. The engine/CVT system is represented as a function of the four independent variables: spark advance, air/fuel ratio, exhaust gas recirculation percentage, and CVT gear ratio. The Generalized Lagrange Multiplier Technique is used to optimize these variables at a set of drive shaft torque/speed points which represent operation of the vehicle over a drive cycle. Results are presented for idealized CVT's.