Electric fluid pump having a cooled wet section

1. An electric fluid pump comprising:

a pump shaft having a longitudinal axis;

an electric pump drive having a wet section configured to drive the pump shaft;

a rotor arranged on the pump shaft having a plurality of cavities that are arranged with a circumferential spacing allowing an axial flow through the rotor that during rotary operation of the rotor, produces an at least partially axially directed fluid flow in the wet section of the electric pump drive; and

a stator surrounding the rotor across an annular gap,

wherein openings for the plurality of cavities are formed on each axial rotor end,

wherein an opening on one axial rotor end configured as a fluid output is situated radially further out than an opening on an opposite axial rotor end configured as a fluid input,

wherein each of the plurality of cavities are substantially triangular in radial cross section and are separated from one another by spoke-shaped webs,

wherein each of the plurality of cavities is delimited by an outer rotor wall, an inner wall proximate to the pump shaft, respective spoke-shaped webs, and the respective rotor ends,

wherein a radial cavity dimension measured between the outer rotor wall and the inner wall proximate to the pump shaft is substantially constant along an axial length and greater than a diameter of the openings for the plurality of cavities on each axial rotor end.

2. The electric fluid pump as claimed in claim 1 , wherein the openings are holes in axial end walls of the rotor.

3. The electric fluid pump as claimed in claim 1 , further comprising a module to be cooled by the wet section.

4. The electric fluid pump as claimed in one of claim 1 , wherein the at least partially axially directed fluid flow is designed as an annular flow that passes through:

the at least one rotor cavity,

a radially outer opening,

the annular gap between the rotor and the stator; and

a radially inner opening.

5. The electric fluid pump as claimed in claim 1 , wherein the wet section of the electric pump drive is bounded by a can that extends between the rotor and the stator and surrounds the rotor.

6. The electric fluid pump as claimed in claim 3 , wherein the module to be cooled is an electric/electronic module.

7. The electric fluid pump as claimed in claim 1 , wherein the radial cavity dimension of the plurality of cavities is greater than a radial dimension of the fluid input and the fluid output.