Patent ID: 7290513

Claim:
Device for changing the control times of gas-exchange valves in an internal combustion engine, the device comprising: a rotary piston adjustment device for angular adjustment of a camshaft relative to a crankshaft, with the following features: the device is mounted on a drive end of a camshaft supported in a cylinder head of the internal combustion engine and is a hydraulic actuator, which can be controlled as a function of various operating parameters of the internal combustion engine, the device includes a drive wheel, in driven connection with the crankshaft of the internal combustion engine, and a vane rotor, locked in rotation with the camshaft of the internal combustion engine, the drive wheel has a hollow space, which is formed by a hollow cylindrical peripheral wall and two lateral walls and in which at least one hydraulic work chamber is formed by at least two radial limit walls, the vane rotor has, on a periphery of a rotor hub thereof, at least one vane, which extends radially into the work chamber of the drive wheel and which sub-divides the work chamber into an A pressure chamber and a B pressure chamber, the pressure chambers are adapted to produce a pivoting motion or to fix the vane rotor relative to the drive wheel and thus the camshaft relative to the crankshaft through selective or simultaneous pressurization with a hydraulic pressure medium, the vane rotor is mechanically couplable with the drive wheel in a preferred base position within an adjustment region by a separate locking element when the pressure medium pressure falls below a pressure necessary for adjustment, the locking element is arranged in an axial bore hole in the rotor hub of the vane rotor and can be moved by a spring element into a locked position within a receptacle in one of the lateral walls of the drive wheel, the receptacle for receiving the locking element is connected hydraulically to at least one pressure chamber within the device via a pressure medium supply groove provided in an inner surface of a corresponding one of the lateral walls of the drive wheel, upon pressurization of the pressure chamber with the pressure medium supply groove, the locking element can move hydraulically into an unlocked position within the axial bore hole in the rotor hub of the vane rotor, a local stop is arranged within the pressure medium supply groove provided in the inner surface of the corresponding lateral wall of the drive wheel, which interrupts the pressure medium supply to the receptacle of the locking element when the vane rotor has been pivoted from the base position, in the side surface of the rotor hub of the vane rotor opposite the pressure medium supply groove there is a bypass, such that the local stop can be bypassed and a pressure medium supply to the receptacle of the locking element is possible only when the vane rotor has been pivoted into the base position.