Hydraulic control device

A hydraulic control device for rotating a camshaft of an internal combustion engine relative to a crankshaft, comprising a coupling member which is longitudinally displaceable by a fluid pressure and has an outer circumference with a first set of gear teeth provided at a first location and engageable with an inner set of gear teeth of the camshaft, and a second set of gear teeth provided at a second location of the outer circumference of the coupling member;

• a hollow cylindrical driving wheel supporting an end of said coupling member and having a central bore hole provided with a set of gear teeth engaging with said second set of gear teeth of said coupling member, so that two sets of gear teeth are formed, one of said sets of gear teeth being a spiral set of gear teeth and the other of said sets of gear teeth being a straight set of gear teeth, so that the camshaft is rotated relative to said driving wheel by a displacement of said coupling member;
• at least one piston acted upon by a pressure fluid and arranged in a hydraulic housing mountable on the camshaft and having at least one radial bore hole which receives said at least one piston;
• said hydraulic housing having
• a cylinder space;
• a ball bearing arranged eccentrically relative to an axis of the cam shaft so that said at least one piston slides at an inner circumference of said ball bearing;
• a plurality of fluid connections leading to said cylinder space in said hydraulic housing from a respective compression space of said at least one bore hole, said fluid connection being provided with at least one outlet valve;
• a double-acting piston arranged in said cylinder space and having a pressure limiting valve producing a fluid connection from an annular pressure space situated on one side of said double-acting piston to a large pressure space situated on the other side of said double-acting piston, said double-acting piston continuously contacting said coupling member.