Patent ID: 7237517

Claim:
A camshaft adjuster for an internal combustion engine comprising a control valve ( 3 ) having a control piston ( 5 ) slidably supported in a valve housing ( 6 ), an operating unit ( 4 ) for adjusting the angular position of the camshaft ( 12 ) relative to the crankshaft of the internal combustion engine, a drive unit ( 8 ) with an electric motor ( 15 ) and a transmission structure ( 16 ) for moving the control piston ( 5 ) in a forward direction ( 17 ) against the force (f spring ) of a spring ( 9 ) into an equilibrium position between the force of the spring ( 9 ) and the adjustable force generated by the drive unit ( 8 ), said transmission structure ( 16 ) being non-self-locking and said spring ( 9 ) being capable of moving the control piston ( 15 ) and the drive unit ( 18 ) in a backward direction against a control force (f control ) provided by drive unit ( 8 ) in the equilibrium position.