There are known hydraulic in-line axial-flow pumps, in which a rotor of an electric motor of the pump is submerged in a delivery medium. The rotor and a stator of the electric motor of the pump are separated from each other by a thin tube. Therefore in such pump no sliding sealings are needed and the pump lifetime is much longer. A hydraulic rotor of the pump is mounted within a special hydraulic casing on a shaft journal of said electric motor rotor. Such pumps have many component parts.

Consequently, the technical problem to be solved by the present invention exists in how to join together a rotor of a pump electric motor and one or several hydraulic rotors of the pump in a hydraulic in-line axial-flow pump to form a unit.

The said technical problem is solved by the hydraulic in-line axial-flow pump of the invention with a submerged rotor of an electric motor, characterized in that a ferromagnetic tubular core of the rotor of the pump electric motor, which tubular core is provided with permanent magnets, is fastened to one or several hydraulic rotors having an axis that is coaxial with a geometrical axis of the tubular core, and that the axis of the hydraulic rotors is supported by a first bearing and by a second bearing and that a casing of the first bearing is fastened to a wall of a through-hole in a first half of pump housing by means of first tie rods and a casing of the second bearing is fastened to a wall of a through-hole in a second half of pump housing by means of second tie rods, the first and the second tie rods forming hydraulic guide members for the hydraulic rotors, and that the first and the second bearing are constructed by means of a thrust bearing and a radial bearing.

The hydraulic in-line axial-flow pump of the invention is characterized also in that the walls of the through-holes in the first and the second half, respectively, pump housing continuously pass into each other across an inner wall of the ferromagnetic tubular core.

The hydraulic in-line axial-flow pump of the invention is further characterized in that the permanent magnets are fastened to an outer wall of the ferromagnetic tubular core and that they are separated by a gap from an inner wall of a centering tube, outside which a stator of the pump electric motor is located.

The hydraulic in-line axial-flow pump of the invention is further characterized in that the centering tube is pressure cast on a stator core of the pump electric motor and sits close on both halves of the pump housing and a first sealing and a second sealing, respectively, are inserted between the centering tube and the corresponding half of the pump housing.

In the hydraulic in-line axial-flow pump of the invention the rotor of the pump electric motor and one or several hydraulic rotors of the pump are advantageously joined together into a unit.

The invention will now be explained in more detail by way of the description of an embodiment and with reference to the accompanying drawing representing, in the sole Figure, hydraulic in-line axial-flow pump of the invention.

In a hydraulic in-line axial-flow pump of the invention with a submerged rotor of an electric motor of the pump a ferromagnetic tubular core 8 of said rotor, preferably on its inner wall, is fastened to one or several hydraulic rotors of the pump. In Figure 1 the hydraulic rotors 7a, 7b are shown. The axis 6 of the hydraulic rotors 7a, 7b is coaxial with a geometrical axis A of the tubular core 8 of the rotor of the pump electric motor.

A casing 3a of a first bearing 5a, 4a is fastened to a wall la'of a through-hole in a first half la of the pump housing by means of first tie rods 2a. A casing 3b of a second bearing 5b, 4b is fastened to a wall lb'of a through-hole in a first half lb of the pump housing by means of second tie rods 2b.

In order to reduce the drag, in the preferred embodiment, the first tie rods 2a and the second tie rods 2b form hydraulic guide members for the hydraulic rotors 7a, 7b.

In order to reduce the drag, the walls la', lb'of the through-holes in the first and second halves la, lb, respectively, of the pump housing continuously pass into each other across an inner wall 8'of the ferromagnetic tubular core 8 continuously.

The hydraulic rotors 7a, 7b push a fluid flow F through the through-holes of the halves la and lb of the pump housing which are equipped to be attached to a pipe.

The tubular core 8 of the rotor of the pump electric motor is provided with permanent magnets 9. They are fastened to an outer wall of the ferromagnetic tubular core 8. The permanent magnets 9 are separated by a gap 9'from an inner wall of a centering tube lc. On its outer side in a special cave ld within both halves la, lb of the pump housing a stator core 10 and a stator winding 11 of the pump electric motor are located.

The axis 6 of the hydraulic rotors 7a, 7b is supported by the first bearing 5a, 4a and by the second bearing 5b, 4b. The first and the second bearings 5a, 4a; 5b, 4b, respectively, are constructed by means of thrust bearings 4a and 4b, respectively, and by means of radial bearings 5a and 5b, respectively.

The centering tube lc is pressure cast on the stator core 10 of the pump electric motor and sits close on both halves la, lb of the pump housing. The centering tube lc centers all component parts of the pump. A first sealing le and a second sealing lf, respectively, are inserted between the centering tube 1 c and the corresponding half la, lb of the pump housing. The centering tube le thus in a watertight manner separates the stator winding 11 from the rotor of the pump electric motor.

The electromagnetic torque exercised on the permanent magnets 9 is transferred through the tubular core 8 of the rotor on hydraulic rotors 7a, 7b of the pump, which generate the hydraulic pressure needed by the medium to flow in the axial direction.

Such pumps may actually be driven by an asynchronous electric motor, yet the number of its revolutions is limited by the mains frequency. The hydraulic rotors of the hydraulic axial-flow pumps, however, need a high specific number of revolutions.

For this reason in such pumps electronically commutated electric motors are used.