Pump Shaft for a Multi-Stage Pump

Abstract

A pump shaft for a multi-stage pump, in particular a centrifugal pump, includes a peripheral groove region for the engagement of a relief device in order to introduce a force acting in the axial direction of the pump shaft. The groove region includes a plurality of grooves which are spaced apart in the axial direction.

Claims

1-15. (canceled)

16. A pump shaft for a multi-stage pump, comprising: a pump shaft having a circumferential groove region configured to receive and cooperate with a load-relieving device to impart a force acting in the axial direction of the pump shaft to the pump shaft, wherein the groove region in an axial direction of the pump shaft includes a plurality of grooves spaced apart from one another in the axial direction.

17. The pump shaft as claimed in claim 16, wherein the plurality of grooves are circumferential grooves separated from one another or are portions of a single-start or multi-start closed screwthread.

18. The pump shaft as claimed in claim 16, wherein a respective groove base of each of the plurality of grooves, viewed in the axial direction, has a shape of a segment of a circle.

19. The pump shaft as claimed in claim 18, wherein radii of the groove bases of the plurality of grooves relative to an axis of rotation of the pump shaft are different, and a radius of one of the plurality of grooves adjacent to an outer edge of the groove region is larger than a radius of one of the plurality of grooves in a central section of the groove region.

20. The pump shaft as claimed in claim 18, wherein radii of the groove bases of the plurality of grooves relative to an axis of rotation of the pump shaft are different, and a groove base depth of one of the plurality of grooves (4) arranged adjacent to an outer edge of the groove region is less than a groove base depth of a one of the plurality of grooves in a central section of the groove region.

21. The pump shaft as claimed in claim 16, wherein the plurality of grooves are separated from one another in the axial direction by pump shaft sections in the groove region, and pump shaft sections in the groove region have a radius from an axis of rotation of the pump shaft which coincides with a radius of the pump shaft adjacent to the groove region.

22. The pump shaft as claimed in claim 16, wherein the plurality of grooves having tooth tips form a sawtooth structure in the axial direction, and radii of the tooth tips of the sawtooth structure with respect to an axis of rotation of the pump shaft are the same.

23. The pump shaft as claimed in claim 22, wherein at least one of tooth bases of the sawtooth structure has a larger radius with respect to the axis of rotation of the pump shaft than a smaller radius of at least one other of the tooth bases of the sawtooth structure.

24. The pump shaft as claimed in claim 23, wherein the at least one other tooth base with the smaller radius is separated from an adjacent outer edge of the groove region by the at least one of the tooth bases with the larger radius, and the at least one other tooth base with the smaller radius is axially separated from the adjacent outer edge of the groove region and an outer edge at an axially opposite outer edge of the grove region by at least one of the tooth bases.

25. The pump shaft as claimed in claim 25, wherein the at least one other tooth base with the smaller radius is axially separated from the adjacent outer edge of the groove region and the outer edge at the axially opposite outer edge of the grove region by at least two tooth bases with larger radii than the smaller radius.

26. The pump shaft as claimed in claim 16, wherein at least one load-relieving groove which does not receive and engage the load-relieving device is provided in the pump shaft adjacent the groove region.

27. The pump shaft as claimed in claim 26, wherein the at least one load-relieving groove includes at two load-relieving grooves, and each of the two load-relieving grooves is located at respective opposite outer edge regions of the groove region.

28. A pump, comprising: a pump shaft having a circumferential groove region; and a load-relieving device, wherein the circumferential groove region is configured to receive and cooperate with the load-relieving device to impart a force acting in the axial direction of the pump shaft to the pump shaft, and the groove region in an axial direction of the pump shaft includes a plurality of grooves spaced apart from one another in the axial direction.

29. The pump as claimed in claim 28, wherein the load-relieving device is a ring configured to surrounds the pump shaft in the circumferential direction, and an inner circumference of the load-relieving device is configured to engage in the plurality of grooves of the groove region of the pump shaft.

30. The pump as claimed in claim 29, wherein the ring is a split ring.

31. The pump as claimed in claim 29, wherein the inner circumference of the load-relieving device includes a plurality of thread elements configured to engage in at least one of the plurality of grooves in the groove region.

32. The pump as claimed in claim 31, wherein at least one of the plurality of thread elements of the load-relieving device is radially shorter relative to an axis of rotation of the of the load-relieving device relative to another one of the plurality of thread elements, and the at least one radially shorter one of the plurality of thread elements is configured to engage one of the plurality of grooves adjacent to at an outer edge of the groove region.

33. The pump as claimed in claim 32, wherein the at least one radially shorter one of the plurality of thread elements includes two load-relieving grooves, and each of the two radially shorter thread elements engage respective ones of the plurality of grooves located at respective opposite outer edge regions of the groove region.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG. 1 shows a view in longitudinal section of a conventional pump,

[0038] FIG. 2 shows an enlarged detail from FIG. 1 in the region A,

[0039] FIG. 3 shows an enlarged detail around the region of a retaining ring groove of a pump according to an embodiment of the invention, and

[0040] FIG. 4 shows an enlarged detail from FIG. 3 in the region Z.

DETAILED DESCRIPTION

[0041] FIG. 1 shows a longitudinal section along the pump shaft 1 of a pump 10. By rotating the pump shaft 1, the impellers 102 which displace a fluid to be displaced are set in rotation. There is an inlet 101 here and a plurality of pump stages arranged in a row which are each provided with impellers 102 rotating about the pump shaft 1.

[0042] After the impellers 102 situated furthest downstream, the pumped fluid leaves the pump 10 via an outlet 103.

[0043] When the fluid is pumped, a force F parallel to the pump shaft is created which is imparted to the pump shaft 1 via a piston 104. Undesired relative movement of the pump shaft and other components of the pump 10 is consequently prevented.

[0044] The force F is here imparted by a reduced cross-section of the pump shaft 1 in which a load-relieving device 3 engages. The latter is thus not movable in the axial direction of the pump shaft. However, rotation of the pump shaft 1 is not affected as a result.

[0045] The groove in the pump shaft 1 of the pump 10 is highly stressed owing to the fact that it receives the axial thrust F and for this reason is also a potential location of a shaft breakage.

[0046] FIG. 2 shows an enlarged view of the region A from FIG. 1 in which the region around the groove 4 is illustrated on an enlarged scale. It can be seen that the axial thrust F typically transmitted by the piston 104 to the load-relieving device 3, i.e. the force F to be imparted to the pump shaft 1, is imparted to the pump shaft 1 via the groove region 2.

[0047] FIG. 3 shows an embodiment according to the invention of the groove region 2, in which a plurality of grooves 4 for receiving the force F are now provided. The load-relieving device 3 is here provided with a corresponding design such that a thread element of the load-relieving device 3 engages in the respective grooves 4. This engagement causes the force F which is to be diverted to be imparted without penetrating particularly deep into the cross-section of the pump shaft 1. This is advantageous because a more stable pump shaft 1, the stability of which is significantly increased, is now present at this location in contrast to the implementation with just one groove.

[0048] It should be noted that the load-relieving device does not necessarily need to be configured so that it 100% complements the groove region.

[0049] As can be seen in FIG. 4, it can be advantageous for uniform imparting of the force F to the pump shaft 1 if the thread elements 11, 12 of the load-relieving device 3 has thread elements 12, which are shortened in the radial direction toward their outer edges, viewed in the direction of the longitudinal section, for engagement in the associated grooves 5. This is represented in the present case with the aid of a sawtooth design 7 (in the direction of the longitudinal section of the pump shaft).

[0050] The grooves 5 at the outer edges of the groove region 2 can here be designed with exactly the same depth as all the other grooves. It is, however, also possible that the grooves at the edge of the groove region 2, in particular at the edge facing the piston 104, are less deep than other grooves 4.

[0051] In particular, the grooves 5 which are arranged at the edge facing the piston 104 are provided, in their base with the shape of a segment of a circle, with a larger radius than the other grooves 4 arranged in the central region.

[0052] It can thus be provided that the two right-hand thread elements 12 are radially shortened such that the two corresponding grooves 5 in the shaft 1 need to be configured so that they are less deep and at the same time larger radii can be provided here in their groove bases 5. This reduces the stress in the grooves 4 of the shaft 1.

[0053] Load-relieving grooves 8 are furthermore also provided, in particular in the directly adjoining vicinity of the outer edges of the groove region 2. However, such a load-relieving groove 8 can also be provided in the load-relieving device 3 itself. It is then a recess there which gets larger toward the piston 104 and causes each of the thread elements 11, 12 to introduce the same amount of force into the respective associated groove 4.

[0054] The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.