Document DE 10 2011 121 042 A1 discloses a cooling assembly for an electric machine with a rotor with a plurality of permanent magnets, which are arranged in a magnet pocket each. A plurality of axially running first cooling channels is arranged on an inner circumference of a rotor core and at least one passage opening between an interior of the rotor and a first cooling channel is arranged in a rotor carrier, wherein an oil-guiding ring is arranged at each end of the rotor core, in which oil-guiding ring there are arranged channels for fluidic coupling of a first cooling channel and magnet pocket or end-face openings of the magnet pocket.

The object of the invention consequently is to describe a possibility for the robust operation of an electric machine cooled via a rotor assembly.

This object is achieved in accordance with the invention by a rotor assembly of the kind described at the outset, further comprising a separation element which has a separation portion extending in the circumferential direction at an inner radius of the shaft, wherein the separation portion separates an interior of the shaft into a first shaft portion, in which the cooling channel extends, and into a second shaft portion, wherein the separation element comprises a sealing means, which seals off the shaft portions with respect to one another.

The present invention proceeds from the consideration of separating the interior of the shaft into two shaft portions and sealing these fluid-tight with respect to one another by the sealing means. An undesirable discharge of a cooling fluid can thus be prevented, which advantageously enables a more robust operation of the electric machine.