The feed channel or the feed channels can run in the radial direction. The axial extent of the rotor assembly is thus prevented from being extended by a fluid line that is connected to a feed channel, thus enabling a space-saving design of the rotor assembly. The connection element expediently comprises at least one cooling fluid connection on its lateral surface, which cooling fluid connection is fluidically connected to the feed channel or one feed channel.

In accordance with an alternative embodiment of the rotor assembly according to the invention, the first cooling channel extends between a free end of the shaft and the second cooling channel, wherein a fifth cooling channel adjoining the fourth cooling channel extends to the other free end of the shaft. In this way, the cooling fluid can be supplied at one free end and can be discharged at another free end of the shaft. The separation portion of the separation element then advantageously seals off the shaft fully at an axial position between the end faces. In this embodiment as well a fluid-guiding element can be provided which typically has through-holes so that a fluidic connection of the first cooling channel to the second cooling channel is formed.

With regard to the rotor core of the rotor assembly according to the invention it is preferred if a plurality of magnet pocket arrangements are each formed from a plurality of the magnet pockets, the clearances thereof forming a cooling channel portion each of the third cooling channel. This makes possible an improved cooling of the rotor assembly, in which the third cooling channel is divided into the plurality of cooling portions.