Patent ID: 7380528

Claim:
A method for operating a hydraulic actuator for a gas-exchange valve of an internal combustion engine, comprising: selectively connecting and disconnecting, with the aid of a valve device, a working chamber of the actuator and a fluid reservoir, wherein a hydraulic fluid is stored under pressure the fluid reservoir, and wherein a lift of the actuating element of the actuator is dependent on a fluid volume present in the working chamber; and ascertaining an instantaneous operating performance of the actuator by: a) briefly connecting the working chamber to the fluid reservoir; b) recording a corresponding pressure drop in the fluid reservoir; c) determining a corresponding lift from the pressure drop in the fluid reservoir, with the aid of predetermined geometric variables of the actuator; and d) forming at least one value pair that includes the lift of the actuating element and an open duration time period during which the working chamber of the actuator is connected to the fluid reservoir.