Engine A/F and Torque Control using Secondary Throttles

The proper functioning of a catalytic converter requires precise regulation of A/F to the stoichiometric value. The control of A/F is usually based on regulating the fuel ow in proportion to air ow changes imposed by the driver. However, due to the relatively long time delays in the fuel feedback loop, the controller cannot properly compensate for rapid air ow changes. To overcome this de ciency, the possibility of air ow control has been suggested by implementing secondary throttles in the intake runners. In this paper, a new structure for A/F and torque control is proposed to enhance the global performance of a secondary throttles engine.