Method and system for variable cam timing device

摘要

Methods and systems are described for an engine with a cam torque actuated variable cam timing phaser. Phaser positioning control is improved by reducing inaccuracies resulting from inadvertent spool valve and/or phaser movement when the spool valve is commanded between regions. In addition, improved spool valve mapping is used to render phaser commands more consistent and robust.

主权项

1. A method for an engine, comprising:
moving a spool valve to move a cam torque actuated variable cam timing phaser to a locking position; holding the phaser at the locking position without engaging a locking pin for a duration; and after the duration, further moving the spool valve to engage the locking pin, wherein the phaser is held at the locking position without engaging the locking pin for the duration responsive to engine oil temperature being lower than a threshold, the threshold based on engine speed.