Hydraulic camshaft adjuster for an internal combustion engine

A hydraulic camshaft adjuster (1) for an internal combustion engine having a camshaft (2), a hydraulic operating unit (4) for adjusting the angular position of the camshaft (2) relative to a camshaft drive, said hydraulic operating unit (4) comprising an inner operating member (11) mounted on the camshaft (2) for rotation therewith and an outer operating member (12) rotatably supported on the inner operating member and defining therebetween operating chambers to which hydraulic fluid can be supplied and from which hydraulic fluid can be discharged for adjusting the relative angular positions of the inner and the outer operating members (11, 12), the outer operating member (12) being operatively connected to a crankshaft of the internal combustion engine for driving the camshaft (2), a hydraulic control valve (3) with a valve housing (6) including a control piston (5) for controlling the supply of hydraulic fluid to, and its discharge from, the hydraulic operating unit (4), said valve housing including at least one pressure channel (22) extending along a longitudinal section thereof for supplying hydraulic fluid to the hydraulic operating unit (4) via the hydraulic control valve (3), the pressure channel (22) being in the form of an open groove extending along the outside of the valve housing (6) and a sleeve (24) surrounding at least a part of the valve housing (6) and tightly covering the pressure channel (22), and an electromagnetic operating unit (8) for operating the hydraulic control valve (3).