Feed-forward control of purge flow in internal combustion engines

Presented is a feed-forward controller that coordinates engine fueling with a purge event to reduce air-fuel ratio excursions. The controller employs a linear parameter-varying model to estimate the necessary changes in fuel pulse-width based on a hydrocarbon sensor located in the purge line. Synchronization between the purge fuel vapor arrival at the intake manifold and the fueling command is realized using a transport delay model. The proposed controller is experimentally validated on a Ford 5.4-L port injected engine and a 3.6-L EcoBoost engine. Significant reductions in air-fuel ratio excursions are achieved during the steady-state engine operating conditions associated with highway conditions.