It is additionally advantageous if the end plate or one end plate is sealed off with respect to the shaft by means of a further sealing means. To this end, the end plate, on its end face facing away from the rotor core, can have a bead surrounding the shaft, with the further sealing means being received in said bead. A groove is typically formed in the bead and receives the further sealing means. The further sealing means sealing off the end plate with respect to the shaft can be an O-ring.

In order to prevent the cooling fluid from escaping from the rotor core, it can be provided advantageously that a lamination stack of the rotor core has an outer sealing layer or a plurality of outer sealing layers formed one on the other, made of a resin material. A liquid barrier is formed by the outer sealing layer and closes off any potential leaks between the laminations. Two outer sealing layers are preferably provided. The sealing layers can be formed by immersing the lamination stack into the resin material once or a number of times.