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US 10,294,833 B2Granted
Method and system for variable cam timing device
AssigneeFord Global Technologies, LLC
InventorsPaul A. Pietrzyk, John Eric Rollinger, Gilbert Fournelle
Life of this patent
Estimating the term…
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.
Claims19
A method for an engine, comprising:
- during a first condition, moving a cam timing phaser to a locking position without prepositioning and holding the phaser in the locking position without engaging a locking pin, wherein moving the phaser to the locking position without prepositioning during the first condition includes moving a spool valve solenoid to a retard region when a current position of the phaser is advanced of the locking position, and moving the spool valve solenoid to an advance region when the current position of the phaser is retarded of the locking position;
- during a second condition, moving the phaser to the locking position with prepositioning and holding the phaser in the locking position with the locking pin engaged, wherein moving the phaser to the locking position with prepositioning during the second condition includes moving the spool valve solenoid to preposition the phaser advanced of the locking position, and then moving the spool valve solenoid to a detent region during camshaft torsional pulses;
- and
- during a third condition, moving the phaser to the locking position without prepositioning and holding the phaser in the locking position with the locking pin engaged, wherein an engine speed is higher in the second condition as compared to the third condition.
1 more element
A method for an engine, comprising:
- during a first condition, moving a cam timing phaser to a locking position without prepositioning and holding the phaser in the locking position without engaging a locking pin, wherein moving the phaser to the locking position without prepositioning during the first condition includes moving a spool valve solenoid to a retard region when a current position of the phaser is advanced of the locking position, and moving the spool valve solenoid to an advance region when the current position of the phaser is retarded of the locking position;
- during a second condition, moving the phaser to the locking position with prepositioning and holding the phaser in the locking position with the locking pin engaged, wherein moving the phaser to the locking position with prepositioning during the second condition includes moving the spool valve solenoid to preposition the phaser advanced of the locking position, and then moving the spool valve solenoid to a detent region during camshaft torsional pulses;
- and
- during a third condition, moving the phaser to the locking position without prepositioning and holding the phaser in the locking position with the locking pin engaged, wherein moving the phaser to the locking position without prepositioning during the third condition includes moving the spool valve solenoid to the detent region from a null region between camshaft torsional pulses, and wherein the camshaft torsional pulses are retard torsional pulses estimated based on camshaft position relative to crankshaft position.
1 more element
A method for an engine, comprising:
- during a first condition, moving a cam timing phaser to a locking position without prepositioning and holding the phaser in the locking position without engaging a locking pin, and, in response to a command to move the phaser out of the locking position to a desired position, moving a spool valve solenoid to one of an advance region and a retard region and using closed loop cam position control to move the phaser to the desired position;
- and
- during a second condition, moving the phaser to the locking position with prepositioning and holding the phaser in the locking position with the locking pin engaged, and, in response to the command to move the phaser out of the locking position to the desired position, ramping the spool valve solenoid through a null region until the locking pin disengages, then moving the spool valve solenoid to one of the advance region and the retard region, and using closed loop cam position control to move the phaser to the desired position, wherein the first condition includes an engine speed that is lower than a threshold speed.
Dependencies are inferred from the claim text.