Patent ID: 8584638

Claim:
A camshaft adjuster for a camshaft which serves to actuate cylinder valves of an internal combustion engine, wherein retardation torques in a direction of retarded cylinder valve opening times are imparted back to the camshaft adjuster by the camshaft when cams are running on, and oppositely directed advance torques in a direction of advanced cylinder valve opening times are imparted back to the camshaft adjuster by the camshaft when cams are running off, the camshaft adjuster comprising: a pressure chamber and an adjusting member arranged in the pressure chamber, the adjusting member divides the pressure chamber into a first chamber part and a second chamber part, wherein pressure medium can be supplied to the first chamber part and the second chamber part and the pressure medium can be discharged from the first chamber part and the second chamber part, such that the adjusting member is movable by a pressure difference between the first chamber part and second chamber part, resulting in a rotation of the camshaft, wherein, when a relatively high pressure prevails in the first chamber part, the camshaft is rotated in the direction of advanced cylinder valve opening times, and when a relatively high pressure prevails in the second chamber part, the camshaft is rotated in the direction of retarded cylinder valve opening times, and wherein a supply and discharge of pressure medium is controllable by a control device, a torque mode or a pump mode can be selectively set by the control device, wherein in the torque mode, predominantly camshaft torques are utilized to build up pressure in the first chamber part or in the second chamber part, and in the pump mode, a pressure build-up in the first chamber part or in the second chamber part is realized predominantly by the pressure medium provided by a pressure medium pump, wherein the control device comprises a valve piston which is arranged in a valve housing, the valve piston is rotatable and axially displaceable relative to the valve housing, the torque mode or the pump mode is settable by axial relative displacement of the valve piston with respect to the valve housing, and the supply and discharge of the pressure medium to and from the first and second chamber parts is controllable by relative rotation of the valve piston with respect to the valve housing.