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US 2016/0108772 A1Published application
Method and system for variable cam timing device
AssigneeFord Global Technologies, LLC
InventorsPaul A. Pietrzyk, John Eric Rollinger, Jamie Charles Hanshaw, Ed Badillo, Gilbert Fournelle
Life of this patent
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Abstract
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.
Claims20
A method, comprising:
- moving cam timing via cam torque actuated hydraulic pressure separate from engine generated oil pressure via a spool valve;
- and
- in response to system oil pressure falling below a threshold, adjusting a position of the spool valve to reduce the system oil pressure applied to a locking circuit of the phaser.
A method, comprising:
- while cam torque generated hydraulic pressure in a phasing circuit of a cam torque actuated cam timing phaser is higher than a threshold,
- in response to engine speed generated hydraulic pressure applied on a locking circuit of the phaser being lower than a threshold, moving a spool valve of the phaser to a detent region to move and hold the phaser at a locking position with a locking pin engaged.
A method, comprising:
- during a first condition, when system oil pressure in a locking circuit of a variable cam phaser is lower than a threshold, holding the phaser in a mid-lock position with a locking pin engaged;
- and
- during a second condition, when system oil pressure is higher than the threshold, holding the phaser in the mid-lock position without engaging the locking pin by utilizing cam torque generated oil pressure.
Dependencies are inferred from the claim text.