Hydraulic camshaft adjuster

The invention relates to a hydraulic camshaft adjuster (1) for adjusting the control times of gas exchange valves of an internal combustion engine, comprising a stator (2) which is rotatable synchronously with a crankshaft of the internal combustion engine, and comprising a rotor (3) which is arranged so as to be able to rotate relative to the stator (2) and which is rotatable synchronously with acamshaft (30). A plurality of ribs (8, 9, 10) are provided on the stator (2), which ribs divide an annular chamber (11) between the stator (2) and the rotor (3) into a plurality of pressure chambers(12, 13, 14). A rotor hub (4) and a plurality of blades (5, 6, 7) extending radially outwardly from the rotor hub (3) are formed on the rotor (3), which blades divide the pressure chambers (12, 13, 14) into two groups of working chambers (15, 16, 17, 18, 19, 20) which have a different effective direction and which can be acted on by a pressure medium (22) flowing in or out in a pressure medium circuit. The hydraulic camsha