The first fluid-guiding elements 33 are each formed as a protrusion of one of the elevations 28, 29 and support the radially inner pair of permanent magnets 3c, 3d. The second fluid-guiding elements 34 are formed as circular free elevations within the cooling channel portion 21 and support the radially outer pair of permanent magnets 3a, 3b. A movement of the permanent magnets 3a-3d out from the magnet pockets 7a-7b (see FIG. 2) is thus prevented. The first fluid-guiding elements 33 are accordingly arranged radially further inwardly than the second fluid-guiding elements 34. The first fluid-guiding element 33 and the second fluid-guiding element 34 on one side of the plane 36 also form a partial cooling channel portion, which improves the flow cross-section of the cooling fluid flowing into the radially outer clearances of the magnet pockets 7a-7d (see FIG. 2).

The third fluid-guiding elements 35 are likewise formed as free elevations and extend arcuately in the radial direction. The third fluid-guiding elements 35 are radially inwardly distanced from one another by less than the first arc length and radially outwardly are distanced from one another further than radially inwardly. The third fluid-guiding elements 35 are likewise used to improve the flow cross-section for the cooling fluid flowing into the radially inner clearances of the radially outer magnet pockets 7a, 7b (see FIG. 2).