Patent ID: 8342144

Claim:
An engine control strategy for a hydraulic camshaft adjuster with mechanical central locking, comprising: at least one rotor and one stator between which chambers A and chambers B, which can be acted on hydraulically, are provided for controllable rotation of the rotor and the stator relative to one another, at least two locking pistons which are mounted in the rotor in an axially movable fashion and which can be pressed elastically into a locking slot for the mechanical central locking of the rotor and the stator, at least one hydraulic system with at least in each case one oil line to chamber the A, to the chamber B and to the locking pistons of at least one electrically controllable solenoid valve, with it being possible for the locking pistons to be acted on by means of a controlled supply of current to the solenoid valve in such a way that the locking pistons can be pressed out of the locking slot in order to separate the rotor and the stator, having at least one engine control unit which, when the engine is shut down, receives at least one “ignition off” signal and at least one signal relating to the present angular position of the camshaft adjuster, compares the angular position with at least one zone definition stored in the engine control unit, forms control commands from said comparison and outputs said control commands to the electrical solenoid valve, wherein, in a zone A N , in which the rotor of the camshaft adjuster is at an angle ≧α with respect to a CLP in a LATE direction, the solenoid valve is supplied with full current in order to adjust the rotor of the camshaft adjuster in an EARLY direction and to connect the locking pistons to the tank for locking in CLP, in a zone A R , in which the rotor of the camshaft adjuster is at an angle <α with respect to the CLP in the LATE direction, the solenoid valve is initially not supplied with current in order to adjust the rotor of the camshaft adjuster in the LATE direction into the zone A N and the solenoid valve is subsequently supplied with full current in order to adjust the rotor of the camshaft adjuster in the EARLY direction again and to connect the locking pistons to the tank for locking in CLP, in a zone B R , in which the rotor of the camshaft adjuster is at an angle <β with respect to the CLP in the early direction, the solenoid valve is initially supplied with full current in order to adjust the rotor of the camshaft adjuster in the EARLY direction into a zone B N in which the rotor of the camshaft adjuster is at an angle >β with respect to the CLP in the early direction, and the control valve is thereafter not supplied with current in order to adjust the rotor of the camshaft adjuster in the LATE direction and to connect the locking pistons to the tank for locking in CLP, in the zone B N , the control valve is not supplied with current in order to adjust the rotor of the camshaft adjuster in the LATE direction and to connect the locking pistons to the tank for locking in CLP.