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US 2016/0108776 A1Published application
Method and system for variable cam timing device
AssigneeFord Global Technologies, LLC
InventorsPaul A. Pietrzyk, John Eric Rollinger, Ed Badillo
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 for an engine, comprising:
- indicating degradation of a variable cam timing phaser based on cam torque oscillations being higher than a threshold, the cam torque oscillations learned during a condition while a spool valve of the variable cam timing phaser is outside a no-fly zone.
A method, comprising:
- while a spool valve of the variable cam timing phaser is outside a no-fly zone, mapping an average amplitude of cam torque oscillations as a function of engine speed and cam position;
- and
- after the mapping, indicating degradation of the phaser based on instantaneous cam torque oscillations being higher than the mapped average amplitude.
An engine system, comprising:
- an engine cylinder including valves;
- cams coupled to a camshaft for actuating the valves;
- a cam position sensor coupled to each cam;
- an engine speed sensor;
- 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:
- mapping cam torsion oscillations as a function of engine speed and cam position while engine speed is steady, and while the spool valve is commanded to one of a retard and advance region;
- and
- in response to instantaneous cam torsion oscillations at a given engine speed being higher than a threshold, the threshold based on the mapping, indicating degradation of the phaser.
8 more elements
Dependencies are inferred from the claim text.