Patent ID: 6938592

Claim:
In a variable cam timing (VCT) system ( 10 a ) having a feedback control loop wherein an error signal ( 36 ) relating to at least one sensed position signal of either a crank shaft position ( 24 a ) or at least one cam shaft position ( 22 a ) is fed back for correcting a predetermined command signal ( 12 ), the system further having a valve ( 14 ) for controlling a relative angular relationship of a phaser ( 42 ) and having a variable force solenoid ( 20 ) for controlling a translational movement of the valve ( 14 ), an improved control method comprising the steps of: providing a dither signal ( 38 ) sufficiently smaller than the error signal ( 36 ); as temperature varies, changing at least one parameter relating to the dither signal ( 38 ); and applying the dither signal ( 38 ) upon the variable force solenoid ( 20 ), thereby using the dither signal ( 38 ) for overcoming a system hysteresis without causing excessive movement of valve ( 14 ).