Hydraulic control device

A hydraulic control device for rotating a cam shaft of an internal combustion engine, comprising a hollow-cylindrical sprocket wheel driven by an internal combustion engine and having a central bore hole with a set of gear teeth at its inner circumference;

• a coupling member longitudinally displaceable by a hydraulic pressure and having a first location on an outer circumference of the coupling member provided with a first set of gear teeth engageable with a set of gear teeth located at an inner circumference of said cam shaft, and a second location provided on the outer circumference of the coupling member having a second set of gear teeth engaging with said set of gear teeth at the inner circumference of said central bore hole of said sprocket wheel, so as to form two gear teeth pairs, one of said gear teeth pairs constituting spiral gear teeth and the other of said gear teeth pairs constituting spur gear teeth;
• an electromagnetic valve arranged so that said coupling member is axially displaced by said hydraulic pressure controlled by said electromagnetic valve so as to bring about a relative rotation of said cam shaft relative to said sprocket wheel;
• a main piston acting on said coupling member and arranged so that said hydraulic pressure acts on said main piston;
• a main housing mounted on said drive wheel to which said cam shaft is also connectable;
• an axial piston pump connected to said main housing having axial bore holes being substantially parallel to a central axis of said cam shaft, and a plurality of additional pistons which are located in said axial bore holes;
• each piston having an outer rounded portion which contacts a wobble plate;
• outlet valves arranged at an outlet side of said bore holes and connected to a pressure space in the pump housing adjacent said main piston, said electromagnetic valve controls the hydraulic pump by controlling a pressure in said pressure space, said main piston and said coupling member arranged so that a mechanical force providing means acts on said coupling member against a force on said main piston.