Pump assembly

Patent metadata

Field	Value
Publication number	US-10024324-B2
Application number	US-201214368852-A
Country	US
Kind code	B2
Filing date	Dec 19, 2012
Priority date	Dec 27, 2011
Publication date	Jul 17, 2018
Grant date	Jul 17, 2018

Abstract

A pump assembly includes an electric drive motor having a stator and a permanent magnet rotor, at least one impeller connected to the rotor via a rotor shaft, a thrust bearing accommodating axial forces acting on the impeller and rotor shaft in operation, and at least one radial bearing arranged on the rotor shaft. The rotor and stator are designed such that a magnetic axial force, acting in the direction of the rotation axis of the rotor and acting on the rotor in the direction of the inflow direction into the impeller, is produced between the rotor and the stator. The rotor shaft and rotor are mounted displaceably in the axial direction relative to the stator, and with an axial displacement of the rotor shaft in the inflow direction into the impeller, the bearing surfaces of the radial bearing lying opposite one another at least partly disengage.

First claim

The invention claimed is:

1. A pump assembly comprising:
an electric drive motor having a stator and a rotor designed as a permanent magnet rotor;
at least one impeller connected to the rotor via a rotor shaft;
a thrust bearing designed to accommodate axial forces acting on the at least one impeller and the rotor shaft upon operation of the pump assembly; and
at least one radial bearing arranged on the rotor shaft, the radial bearing having a first bearing surface located on the outer periphery of the rotor shaft and a second, fixed bearing surface,
wherein the rotor and the stator are designed such that a magnetic axial force is produced between the rotor and the stator, acting in an axial direction (X) of the rotor and acting on the rotor in an inflow direction (E);
wherein the rotor shaft with the rotor is mounted in a displaceable manner in the axial direction (X) relative to the stator; and
wherein the radial bearing is designed such that, with an axial displacement of the rotor shaft in the inflow direction (E), the first bearing surface and the second bearing surface of the radial bearing lying opposite one another at least partly disengage from each other in an idle state of the pump assembly.

2. The pump assembly according to claim 1 , wherein a hydraulic axial force acting on the at least one impeller and the rotor shaft upon operation of the pump assembly is larger than the oppositely directed magnetic axial force.

3. The pump assembly according to claim 1 , wherein the stator peripherally surrounds the rotor.

4. The pump assembly according to claim 1 , wherein the rotor and the stator are designed and arranged such that, at least upon operation of the pump assembly, an axial middle (MR) of the rotor is spaced from an axial middle (MS) of the stator, in a direction opposite to the inflow direction (E).

5. The pump assembly according to claim 1 , wherein the at least one impeller is fixed in the axial direction on the rotor shaft.

6. The pump assembly according to claim 1 , wherein the rotor shaft is movable such that it can axially displace in the inflow direction (E), in an idle condition of the pump assembly.

7. The pump assembly according to claim 6 , wherein the thrust bearing has a movable first bearing surface axially fixed on the rotor shaft and a fixed second bearing surface, and the thrust bearing is designed such that the movable first bearing surface and the fixed second bearing surface disengage from each other with a displacement of the rotor shaft in the inflow direction (E).

8. The pump assembly according to claim 1 , wherein the radial bearing is designed as a sliding bearing, and the second bearing surface is formed in a stationary bearing ring.

9. The pump assembly according to claim 1 , wherein in a region adjacent the first bearing surface, a diameter of the rotor shaft is reduced compared to a diameter of the first bearing surface on the rotor shaft.

10. The pump assembly according to claim 1 , wherein the first bearing surface and the second bearing surface lying opposite one another are dimensioned in their axial extension and are arranged relative to one another such that with the axial displacement of the rotor shaft the first bearing surface and the second bearing surface disengage from each other by more than 50%.

11. The pump assembly according to claim 1 , further comprising a suction seal arranged adjacent to the at least one impeller such that, with an axial displacement of the rotor shaft in the inflow direction (E), the suction seal and the at least one impeller at least partly disengage.

12. The pump assembly according to claim 4 , wherein the rotor shaft is displaceable by an amount smaller than or equal to an axial distance (a) between the axial middle (MR) of the rotor and the axial middle (MS) of the stator, the axial distance existing upon operation of the pump assembly.

13. The pump assembly according to claim 1 , wherein the thrust bearing has a stationary thrust bearing surface formed on a face of a stationary surface axially facing the impeller, and wherein the pump assembly further comprises an emergency bearing surface facing the stationary thrust bearing surface and formed on the at least one impeller on an axial side facing the rotor.

14. The pump assembly according to claim 13 , wherein the stationary thrust bearing surface is formed by an axial face-side of a stationary bearing ring of the thrust bearing of the rotor shaft.

15. The pump assembly according to claim 13 , wherein the at least one impeller is arranged such that the emergency bearing surface can be brought into bearing contact with the stationary thrust bearing surface by the axial displacement of the rotor shaft, wherein upon operation of the pump assembly, the emergency bearing surface is axially spaced from the stationary thrust bearing surface.

16. The pump assembly according to claim 15 , wherein the spacing of the emergency bearing surface to the stationary thrust bearing surface is smaller or equal to an axial distance (a) between an axial middle (MR) of the rotor and an axial middle (MS) of the stator, the axial distance existing upon operation of the pump assembly.

17. The pump assembly according to claim 1 , further comprising at least one sealing element arranged either between the rotor shaft and a stationary bearing ring, or between the at least one impeller and a stationary bearing ring, such that the sealing element can be brought into sealing bearing contact by the axial displacement of the rotor shaft.

18. The pump assembly according to claim 1 , wherein the first bearing surface and the second bearing surface lying opposite one another are dimensioned in their axial extension and are arranged relative to one another such that with the axial displacement of the rotor shaft the first bearing surface and the second bearing surface disengage from each other by more than 75%.

Assignees

• Grundfos Holding As

Inventors

• Blad Thomas

Classifications

• F04D13/0633 Primary

  Details of the bearings · CPC title

• F04D29/049

  Roller bearings · CPC title

• F04D29/041

  Axial thrust balancing · CPC title

• F04D29/042

  Axially shiftable rotors (F04D29/041 takes precedence {; control by creating a by-pass F04D15/0027}) · CPC title

• F04D29/0413

  hydrostatic; hydrodynamic thrust bearings · CPC title