Closed-loop camshaft phaser control

摘要

Internal combustion engine variable valve timing control with a camshaft phaser (10) for varying rotational phase between a camshaft (40) and a crankshaft (38) in response to a control command determined through a hybrid control strategy without resort to direct temperature measurement. For a range of phase errors requiring high response compensation, a control strategy emphasizing rapid response (212-220), such as a bang-bang strategy (212-216), is deployed. For a range of phase errors (208) requiring high accuracy compensation (230-250), a control strategy emphasizing high precision, such as a proportional-plus-integral strategy (236-240), is deployed. The phase error ranges are updated periodically (318;344) to account for changes in operating conditions. The control command includes an offset (408) which varies in response to a periodically estimated control deadband (410-422) to affirmatively account for the deadband with each issued control command (430). <IMAGE> <IMAGE>