Abstract: A pump unit includes a pump housing and a rotor in the pump housing. The pump unit contactless magnetic levitating and driving the rotor. The pump housing has a bottom part and a cover, the bottom part having a cylindrical cup to receive the rotor and a substantially ring-shaped first sealing surface for a sealing interaction with the cover. The cover has a substantially ring-shaped second sealing surface for a sealing interaction with the first sealing surface. One of the first and second sealing surfaces is a ribbed surface with a radial sealing rib, which extends in the circumferential direction along the entire sealing surface, while the other of the first and second sealing surfaces is a smooth surface.

Abstract: An electromagnetic rotary drive includes a rotor having a magnetically effective core, and a stator, with which the rotor can be magnetically driven without contact and magnetically levitated without contact with respect to the stator. The rotor is actively magnetically levitated in a radial plane perpendicular to the axial direction. The stator has coil cores including a leg extending from a first end to a second end, and a transverse leg at the second end and extending from the longitudinal leg in a radial direction. The coil cores are arranged around the magnetically effective core with respect to a circumferential direction, and a concentrated winding surrounds each longitudinal leg. A cooling device includes a cooling conduit for cooling fluid. The cooling conduit has a section arranged in the circumferential direction in an interspace between the longitudinal leg of two coil cores.