Bearing arrangement and wear indicator for a liquid ring vacuum pump

Abstract

A liquid-ring vacuum pump comprises a pump casing and a shaft eccentrically mounted in the pump casing. An impeller and a rotor of a drive motor are connected to the shaft. A disk cam is arranged parallel to the impeller. A first main bearing for the shaft is arranged between the impeller and the rotor of the drive motor, on the plane of the disk cam. The impeller is arranged between the first main bearing and a second main bearing. The arrangement of the bearings prevents the shaft from bending, thus allowing the leakage gap between the impeller and the disk cam to be kept small.

Claims

1. A liquid-ring vacuum pump having a pump housing, having a shaft which is mounted eccentrically in the pump housing, an impeller and a rotor of a drive motor being connected to the shaft, and having a control disk defining a plane which is arranged parallel to the impeller, a first main bearing and a second main bearing being provided for the shaft, the first main bearing being arranged between the impeller and the rotor, and the impeller being arranged between the first main bearing and the second main bearing, characterized in that the first main bearing is arranged in the plane of the control disk, and the pump further comprises an operating liquid, wherein during operation of the pump, the impeller, impeller vanes, the control disk, and the operating liquid form chambers, and the control disk opens and closes the chambers, wherein a leakage gap is formed between the impeller and the control disk, and the control disk comprises openings through which a medium to be pumped can enter and exit the chambers.

2. The liquid-ring vacuum pump as claimed in claim 1, characterized in that the first main bearing is held in a housing part which is arranged adjacently with respect to the control disk.

3. The liquid-ring vacuum pump as claimed in claim 2, characterized in that the first main bearing is designed to absorb radial forces and axial forces from the shaft.

4. The liquid-ring vacuum pump as claimed in claim 2, characterized in that the second main bearing is designed to absorb radial forces from the shaft.

5. The liquid-ring vacuum pump as claimed in claim 2 wherein the drive motor has a stator, characterized in that the rotor and the stator of the drive motor form a hydrodynamic bearing for the shaft.

6. The liquid-ring vacuum pump as claimed in claim 2, characterized in that a run-on ring is provided on a side of the rotor of the drive motor opposite to the impeller.

7. The liquid-ring vacuum pump as claimed in claim 2, characterized in that the shaft has an axial position defined by the impeller bearing against an end face of the first main bearing.

8. The liquid-ring vacuum pump as claimed in claim 1, characterized in that the first main bearing is designed to absorb radial forces and axial forces from the shaft.

9. The liquid-ring vacuum pump as claimed in claim 8, characterized in that the second main bearing is designed to absorb radial forces from the shaft.

10. The liquid-ring vacuum pump as claimed in claim 8 wherein the drive motor has a stator, characterized in that the rotor and the stator of the drive motor form a hydrodynamic bearing for the shaft.

11. The liquid-ring vacuum pump as claimed in claim 8, characterized in that a run-on ring is provided on a side of the rotor of the drive motor opposite to the impeller.

12. The liquid-ring vacuum pump as claimed in claim 1, characterized in that the second main bearing is designed to absorb radial forces from the shaft.

13. The liquid-ring vacuum pump as claimed in claim 12, characterized in that the rotor and the stator of the drive motor form a hydrodynamic bearing for the shaft.

14. The liquid-ring vacuum pump as claimed in claim 12, characterized in that a run-on ring is provided on a side of the rotor of the drive motor opposite to the impeller.

15. The liquid-ring vacuum pump as claimed in claim 1 wherein the drive motor has a stator, characterized in that the rotor and the stator of the drive motor form a hydrodynamic bearing for the shaft.

16. The liquid-ring vacuum pump as claimed in claim 15, characterized in that a run-on ring is provided on a side of the rotor of the drive motor opposite to the impeller.

17. The liquid-ring vacuum pump as claimed in claim 1, characterized in that a run-on ring is provided on a side of the rotor of the drive motor opposite to the impeller.

18. The liquid-ring vacuum pump as claimed in claim 17, characterized in that the run-on ring concurrently serves as a wear indicator.

19. The liquid-ring vacuum pump as claimed in claim 1, characterized in that the shaft has an axial position defined by the impeller bearing against an end face of the first main bearing.

20. The liquid-ring vacuum pump as claimed in claim 1, characterized in that during operation, the impeller has a rotation and generates force in a direction of the first main bearing as a result of the rotation during operation of the pump.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following text, the invention will be described by way of example using one advantageous embodiment with reference to the appended drawing, in which:

(2) FIG. 1 shows a diagrammatic cross-sectional view of a pump.

DETAILED DESCRIPTION

(3) A liquid-ring vacuum pump in FIG. 1 comprises a housing 14 with a base 15. A shaft 19 is mounted in the housing 14, which shaft 19 extends transversely through the housing 14 from the left-hand end as far as the right-hand end. The shaft 19 supports a rotor 20 of a drive motor of the pump on one side and an impeller 21 on the other side, by way of which impeller 21 the gas to be delivered is transported.

(4) The housing 14 is composed in the axial direction of three housing parts 16, 17, 18, the impeller 21 being accommodated in the housing part 18 which is shown on the left in FIG. 1 and the drive motor being accommodated in the housing part 16 which is shown on the right. The drive motor comprises the rotor 20 which is connected to the shaft 19 and a stator 24 which is connected to the housing part 16. Electrical energy is fed to the drive motor via a power supply 25, with the result that the shaft 19 is set in rotation together with the impeller 21. The medium to be transported is delivered by way of the rotation of the impeller 21, as will be explained in greater detail below.

(5) The shaft 19 is mounted by way of a first main bearing 23 and a second main bearing 26 which are arranged on both sides of the impeller 21 at a slight distance from the impeller 21. The first main bearing 23 is held in the central housing part 17 and extends from there just beyond the plane of the control disk 22. The second main bearing 26 is situated in the end side of the housing part 18 and extends from the end of the shaft 19 as far as the impeller 21. The two main bearings 23, 26 are arranged in the region in which the strongest forces are transmitted to the shaft 19 by the impeller 21.

(6) Only low forces still act on the shaft 19 between the first main bearing 23 and the other end of the shaft 19. The drive motor 19 forms its own hydrodynamic bearing as a result of the thin gap between the rotor 20 and the stator 24, which gap is filled with operating liquid during operation of the pump. The shaft 19 has play in the run-on ring 27 which is provided at the other end of the shaft. The run-on ring 27 therefore does not absorb any bearing forces during normal operation, but rather serves for additional safety if the main bearings 23, 26 become worn. It can be determined by way of a suitable sensor on the run-on ring 27 if bearing forces are occurring in the run-on ring 27. The occurrence of bearing forces can be understood as an indication of the start of wear of the pump.

(7) The impeller 21 is mounted eccentrically in the housing part 18 which forms the actual pump housing. When the impeller rotates, an operating liquid is set in motion, with the result that a liquid ring which moves with the impeller is produced in the pump housing. Depending on the angular position of the impeller, the liquid ring penetrates to a greater or lesser depth into the chambers 30 of the impeller. As a result, the liquid ring acts as a piston which moves up and down in the chambers 30. The gas to be delivered is sucked in the region in which the volume of the chamber 30 is increased, and is output again in the region in which the volume of the chamber 30 is decreased.

(8) Ducts which are not shown in FIG. 1 are provided in the central housing part 17 for the supply and discharge of the gas. The ducts open in a control disk 22 which is provided with openings 32. The openings 32 are arranged in such a way that the gas can enter into the chamber 30 and exit the chamber 30 in the correct region.

(9) There necessarily has to be a gap between the control disk 22 and the impeller 21, in order that the impeller 21 can rotate freely. At the same time, said gap forms a leakage gap 31 of the pump, through which leakage gap 31 the gas to be delivered can escape from one chamber 30 into the next chamber 30. On the opposite side of the impeller 21, the chambers 30 are closed by way of a wall which protrudes as far as into the liquid ring during operation of the pump.

(10) In order to keep the leakage gap 31 small between the impeller 21 and the control disk 22, the impeller 21 has to be positioned exactly in the longitudinal direction. In the pump, the position of the impeller 21 is defined by virtue of the fact that the impeller bears against an end face of the first main bearing 23. The first main bearing 23 is held in the central housing part 17, with the result that the bearing forces are transferred to there and not to the control disk 22. Starting from the central housing part 17, the first main bearing 23 protrudes somewhat beyond the control disk 22 in the direction of the impeller 21. If the impeller 21 bears against the end face of the first main bearing 23, the impeller therefore maintains a defined distance from the control disk 22. The impeller 21 is designed in such a way that a force which acts in the direction of the control disk 22 is produced during operation of the pump. As a result, the impeller 21 assumes the desired position in the pump automatically.