Control-Oriented Model of a Dual Equal Variable Cam Timing Spark Ignition Engine

Abstract

A control-oriented engine model is developed to represent a spark ignited engine equipped with a variable cam timing mechanism over a wide range of operating conditions. Based upon laboratory measurements a continuous, nonlinear, low-frequency phenomenological engine model is developed. With respect to a fixed-cam timing engine, the VCT mechanism alters the mass air flow into the cylinders, the torque response, and the emissions of the engine. The developed model reflects all of these modifications and includes a representation of the breathing process, torque and emission generation, and sensor/actuator dynamics. The model has been validated with engine-dynamometer experimental data and can be used in powertrain controller design and development.