Patent ID: 8145400

Claim:
A method for controlling a hydraulic actuator of a friction clutch, which comprises: a) a pump driven by an electric motor that is controlled by a control system; b) a pressure line, which contains a check valve and which runs from the pump to an actuator cylinder having an actuator piston acting on the friction clutch, with a pressure in the actuator cylinder to be controlled; and c) a fast drain valve, which is in flow communication with the actuator cylinder and includes a slider responsive to the pressure prevailing at the side of the pump facing it; the method comprising: determining a control variable for the electric motor from a desired pressure and an actual pressure in the actuator cylinder; and executing at least two different control algorithms depending on a sign of a difference between the desired pressure and actual pressure wherein, with a positive sign, the control algorithm is that of a cascade controller such that a desired speed (n des ) of the electric motor is determined in a first sub-controller from the desired pressure and the actual pressure in the actuator cylinder, a desired electrical parameter (I des ) is determined in a second sub-controller from the desired speed (n des ) and an actual speed (n act ) of the electric motor and a control variable for controlling the electric motor is determined in a third sub-controller from the desired electrical parameter (I des ) and an actual electric parameter (I act ).