Continuously variable friction drive phaser

A method of adjusting a phase of a camshaft relative to a crankshaft by use of a variable-ratio friction drive phaser having an actuator which changes a tilt of a plurality of discs transmitting power between a cam plate coupled to the camshaft and a sprocket plate coupled to the crankshaft, comprising the steps of:

• a) a controller determining a desired phase and a current phase of the camshaft relative to the crankshaft;
• b) the controller calculating an actuation direction to move the actuator to change the phase of the camshaft relative to the crankshaft from the current phase to the desired phase;
• c) the controller sending a signal to the actuator to adjust the tilt of the plurality of discs to a determined position in the calculated actuation direction to advance or retard the camshaft relative to the crankshaft;
• and
• d) the controller sending a signal to the actuator to return the tilt of the plurality of discs to a holding position in which the phase of the camshaft relative to the crankshaft is maintained at the desired phase.