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US 2016/0108768 A1Published application
Method and system for variable cam timing device
AssigneeFord Global Technologies, LLC
InventorsJohn Eric Rollinger, Paul A. Pietrzyk, Ed Badillo, Jamie Charles Hanshaw
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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:
- during selected conditions,
- ramping a spool valve coupled to a cam torque actuated variable cam timing phaser from a detent region to a retard region;
- and
- mapping a transitional region between the detent and retard regions based on phaser movement away from a locked position, the phaser movement responsive to the ramping.
1 more element
A method, comprising:
- in response to a request for locking a cam timing phaser for more than a threshold duration,
- operating in a learning mode to map a transitional region between a detent region and a retard region of a spool valve coupled to the phaser, the transitional region mapped based on cam timing phaser motion out of the locked position relative to spool valve motion through the transitional region.
An engine system, comprising:
- an engine cylinder including valves;
- cams coupled to a camshaft for actuating the valves;
- a variable cam timing phaser for adjusting valve timing, the phaser actuated using torque from the cams;
- a solenoid driven spool valve for adjusting a position of the phaser;
- and
- a controller with computer readable instructions stored on non-transitory memory for:
- receiving a command for moving the phaser out of a locked position to a desired unlocked position;
- estimating an error between an actual unlocked position of the phaser relative to the desired unlocked position;
- and
- in response to the error being higher than a threshold,
- operating in a learning mode with the phaser commanded to the locked position to update a map of a transitional region between a detent region and a retard region of a spool valve based on motion out of the locked position relative to spool valve motion through the transitional region.
8 more elements
Dependencies are inferred from the claim text.