Method and device for adjusting the friction coefficient of a friction clutch situated in a hybrid power train

A method for adjusting a torque characteristic curve or a friction coefficient of a friction clutch situated in a hybrid power train between an electric machine and a combustion engine, actuated by a clutch actuator, comprising:

• adjusting the torque characteristic curve or friction coefficient by a torque transmitted by the friction clutch, the torque being determined when starting the combustion engine by the electric machine,
• wherein the adjusting step includes the following steps:
• actuating the friction clutch to crank-start the combustion engine in accordance with an old torque characteristic curve, in such a way that the friction clutch transmits a target torque definitely sufficient to start the combustion engine;
• detecting a change in speed of the combustion engine;
• determining an actual clutch torque from the change in engine speed, a moment of inertia and a torque of the combustion engine;
• and
• adjusting the old torque characteristic curve or friction coefficient so that the target torque matches an actual torque.