A camshaft phaser wherein camshaft oscillatory torque resulting from opening
and
closing of an associated engine valve is employed to controllably adjust the degree
of advance or retard of the rotor. All advance chambers communicate with a first
annular passage, and all retard chambers communicate with a second annular passage.
Valve means connecting the first and second annular passages are controllable by
a solenoid-actuated piston to permit selective flow of oil between the advance
and retard chambers to alter the angular position of the rotor with respect to
the stator. The solenoid windings are selectively actuable in response to an engine
control module. Preferably, the phaser is a sealed unit, filled with oil at manufacture
and requires no oil connection with the oil recirculation system of an engine upon
which the phaser is mounted. The phaser is independent of engine oil pressure for actuation.