Joint Air-Fuel Ratio and Torque Regulation Using Secondary Cylinder Air Flow Actuators

Abstract

Actuation schemes exist that permit the joint management of air and fuel flow into the cylinders of a spark ignition engine. With the exception of drive by wire systems, to-date, the transient control aspects of these schemes, collectively refered to here as secondary cylinder air flow actuators, has not received any attention from the control community. This paper takes a first step in the analysis of the simultaneous dynamic control of air fuel ratio and torque response using secondary actuators placed before the intake ports of the cylinders, when used in combination with standard fuel injectors and primary throttle regulated by the driver. The emphasis is on basic issues of designing a feedforward scheme to enhance actuator authority for feedback control, and the fundamental multivariable nature of the feedback problem. Enhanced transient air-to-fuel ratio performance improvement is shown to be possible without sacrificing engine torque response with respect to a conventional engine. In addition, this is achieved with overall higher manifold pressure, offering the possibility of reduced pumping losses in the engine, depending on the actual actuation scheme employed.