Central locking for a camshaft adjuster

A hydraulic camshaft adjuster for changing timing of gas exchange valves of an internal combustion engine, configured as a vane camshaft adjuster, the camshaft adjuster comprising:

• a stator configured to be connected to a crankshaft of the internal combustion engine;
• a rotor rotatably fixedly supported in the stator and configured to be connected to a camshaft;
• a line system supplying or discharging a hydraulic medium to or from at least two pressure chambers, a hydraulic switching valve connected therebetween, as well as with aid of pressure medium lines, the at least two pressure chambers each being divided into separate, oppositely acting working chambers by a rotor-fixed vane, a phase angle of the camshaft being selectively variable relative to the crankshaft;
• a control device in the vane and configured to selectively unblock and interrupt a flow connection between the working chambers;
• a locking device preventing a relative movement between the rotor and the stator, in that the rotor is fixed on the stator in a vane position, the interacting working chambers having a corresponding volume in the vane position;
• the locking device including at least one locking pin locking in a central locking position of a locking gate from a direction of an ADVANCE or RETARD stop position during a rotation of the rotor;
• the at least one locking pin being movable from a first switching position into a second switching position against a spring force by an application of the hydraulic medium;
• the hydraulic switching valve including three working ports as well as a P port as an inlet and a T port as an outlet and being adjustable into different control positions via a control element;
• in a first control position of the control positions, the P port and an A port communicating with the working chambers, a B port connected to the working chambers and being blocked at the switching valve, and the T port communicating with the control device of the vane via a C port;
• in a second control position of the control positions, the P port communicating with the working chambers via the A port, the B port communicating with the working chambers, and the T port as well as the C port communicating with the control device of the vane and the T port;
• in a third control position of the control positions, the A port and the B port being blocked at the switching valve, and the C port communicating with the P port and the control device of the vane;
• and
• in a fourth control position, the A port communicating with the T port and the working chambers, the B port communicating with the P port and the working chambers, and the C port communicating with the P port and the control device of the vane,
• the switching valve being switchable into a further control position during a starting strategy, the A port communicating with the P port and the working chambers, the B port communicating with the T port and the working chambers, and the C port communicating with the control device of the vane and the P port in the further control position.