Method for operating an active oil separator and device for separating oil

A method for operating an active oil separator for separating oil from exhaust air of a crankcase of a motor vehicle with an internal combustion engine, the method comprising:

• detecting an engine operating state of the internal combustion engine via a detection device, the engine operating state being determined by an engine load and/or an engine speed of the internal combustion engine;
• determining, via a determination device, a first SET rotational speed of the oil separator as a function of the detected engine operating state and a first characteristic map, wherein the first characteristic map specifies the first SET rotational speed of the oil separator as a function of the engine operating state;
• determining, via the determination device, a maximum SET rotational speed of the oil separator as a function of the first SET rotational speed in such a manner that the maximum SET rotational speed is at least as high as the first SET rotational speed;
• determining, via the determination device, a preferred SET rotational speed on the basis of the maximum SET rotational speed such that the preferred SET rotational speed is, at most, as large as the maximum SET rotational speed;
• and
• controlling an electric motor to drive the oil separator at the preferred SET rotational speed via a control device,
• wherein an oil temperature of the internal combustion engine is detected via the detection device, wherein a second SET rotational speed of the oil separator is determined via the determination device as a function of the detected oil temperature and a second characteristic map, wherein the second characteristic map specifies the second SET rotational speed of the oil separator as a function of the oil temperature, wherein the determination of the maximum SET rotational speed of the oil separator via the determination device additionally takes place as a function of the second SET rotational speed such that the maximum SET rotational speed is at least as high as the second SET rotational speed.