Fundamental study of low fuel consumption control scheme based on combination of direct fuel injection engine and continuously variable transmission

Concern for the environment has led to very severe regulations on fuel consumption and exhaust emissions. Especially fuel consumption has become a more important index which represents technology of car makers. The paper therefore proposes a scheme to minimize rate of fuel consumption by a direct fuel injection engine used by combination with a continuously variable transmission. Target values for the engine and the transmission which minimize fuel consumption ensuring driving performance are calculated based on the nonlinear optimization method. The engine and the transmission are cooperatively controlled in order to achieve these target values. The simulation in the acceleration test and the 10-15 mode test showed that the proposed method is effective to achieve low fuel consumption ensuring driving performance.