Centrifugal pump

Abstract

A centrifugal pump (1) includes a pump casing and a shaft (11) which is rotatably mounted therein and on which an impeller (10), for delivering fluid, is arranged rotationally fixed. A cartridge shaft seal (13) is arranged between the shaft (11) and an opening (16) of the casing, through which opening the shaft (11) is led. The cartridge shaft seal (13) includes a sleeve (22) which surrounds the shaft (11) at least in the region of the opening 16 and which is connected to the shaft (11) releasably and rotationally fixed, by way of a clamping device (29) which is arranged on the outer side of the sleeve (22). The clamping device (29) includes clamping jaws (32) which only engage on the outer side of the sleeve (22) and non-positively connect the sleeve (22) to the shaft (11).

Claims

1. A single-stage or multi-stage centrifugal pump comprising: a pump casing; a shaft rotatably mounted in the pump casing; at least one impeller arranged on the shaft in a rotationally fixed manner for delivering fluid; and a cartridge shaft seal arranged between the shaft and an opening of the casing, through which opening the shaft is led, the cartridge shaft seal comprising a sleeve surrounding the shaft at least in the region of the opening and a clamping device comprising: screws; and at least two clamping components which surround the sleeve in sections and which, via the screws arranged tangentially or parallel to the at least two clamping components, are connected to one another such that clamping forces acting on the sleeve via the clamping components are exerted by way of tightening the screws, each clamping component comprising at least one clamping jaw which bears on the sleeve and which is adapted to an outer contour of the sleeve or an outer contour of the shaft or both an outer contour of the sleeve and an outer contour of the shaft, the sleeve being releasably and rotationally fixedly connected to the shaft via the clamping device, the clamping device being arranged on an outer side of the sleeve, wherein the clamping components of the clamping device engage only on an outer side of the sleeve such that the sleeve is only non-positively connected to the shaft, and wherein the sleeve comprises a first axial section and a second axial section and the at least two clamping components of the clamping device only engage with the outer contour of the first axial section of the sleeve.

2. A centrifugal pump according to claim 1, wherein the clamping device is releasably connected to the sleeve.

3. A centrifugal pump according to claim 1, wherein each screw connects two adjacent clamping components to one another and is arranged perpendicularly to a radial partition plane of the clamping components which are to be connected.

4. A centrifugal pump according to claim 1, wherein the at least two clamping components are configured in an identical manner.

5. A centrifugal pump according to claim 1, wherein the sleeve is at least partially deformable by the clamping jaw such that the inner contour of the sleeve at least partially adapts to the outer contour of the shaft.

6. A centrifugal pump according to claim 1, wherein: each clamping component has a guide surface which is distanced to the sleeve and which is actively connected to a mating guide surface which is arranged on the adjacent clamping component; the guide surfaces lie in a plane which lies parallel to a middle longitudinal axis of the next adjacent screw or parallel to a tangent to the sleeve or at an acute angle.

7. A centrifugal pump according to claim 6, wherein the guide surfaces and the mating guide surfaces are each arranged between a screw which connects two clamping components to one another and the outer periphery of the sleeve.

8. A centrifugal pump according to claim 6, wherein a guide surface and a mating guide surface are formed on a guide pin and on a recess which receives the guide pin.

9. A centrifugal pump according to claim 1, wherein a clamping jaw extends over a peripheral angle of the sleeve, between 30 and 50.

10. A centrifugal pump according to claim 1, wherein a clamping component comprises a further contact surface which is provided for contact of the clamping component on the sleeve and which is peripherally distanced to the clamping jaw.

11. A centrifugal pump according to claim 10, wherein the clamping component comprises a region between the clamping jaw and the further contact surface, said region being distanced to the sleeve and extending over an angular region of between 80 and 110.

12. A centrifugal pump according to claim 1, wherein the at least one contact surface of each clamping jaw is adjacent to a guide surface of the same clamping component and is arranged away from this guide surface.

13. A centrifugal pump according to claim 1, wherein the peripheral arrangement of the clamping jaws is effected such that clamping forces acting upon the sleeve are greater in a transverse direction to a longitudinal axis of the connecting screw than clamping forces which are directed in a longitudinal direction or parallel to the screw.

14. A cartridge shaft seal for a centrifugal pump including a pump casing, a shaft rotatably mounted in the pump casing and at least one impeller arranged on the shaft in a rotationally fixed manner for delivering fluid, the cartridge shaft seal being arranged between the shaft and an opening of the pump casing, through which opening the shaft is led, the cartridge shaft seal comprising: a sleeve surrounding the shaft at least in the region of the opening; and a clamping device comprising: screws; and at least two clamping components which surround the sleeve in sections and which, via the screws arranged tangentially or parallel to the at least two clamping components, are connected to one another such that clamping forces acting on the sleeve via the clamping components are exerted by way of tightening the screws, each clamping component comprising at least one clamping jaw which bears on the sleeve and which is adapted to an outer contour of the sleeve or an outer contour of the shaft or both an outer contour of the sleeve and an outer contour of the shaft, the sleeve being releasably and rotationally fixedly connected to the shaft via the clamping device, the clamping device being arranged on an outer side of the sleeve, wherein the clamping components of the clamping device engage only on an outer side of the sleeve such that the sleeve is only non-positively connected to the shaft, and wherein the sleeve comprises a first axial section and a second axial section and the at least two clamping components of the clamping device only engage with the outer contour of the first axial section of the sleeve.

15. A cartridge shaft seal according to claim 14, further comprising: a first slide ring; a second slide ring, the first slide ring being rotationally, fixedly arranged close to the opening of the pump casing and comprising an axial sliding and sealing surface which bears on an axial sliding and sealing surface of the second slide ring, provided for being rotationally, fixedly arranged on the shaft passing through the casing opening, wherein the clamping device, arranged on the sleeve comprises a plurality of clamps; spring means for subjecting the sliding and sealing surfaces to an axial force onto one another; and sealing means for sealing the slide rings.

16. A cartridge shaft seal according to claim 14, wherein each screw connects two adjacent clamping components to one another and is arranged perpendicularly to a radial partition plane of the clamping components which are to be connected.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings:

(2) FIG. 1 is a greatly simplified, perspective representation a multi-staged inline centrifugal pump with a connected motor;

(3) FIG. 2 is a longitudinal sectional view through the head of the pump casing with the motor stool;

(4) FIG. 3 is a greatly simplified, longitudinal sectional view through the cartridge shaft seal;

(5) FIG. 4 is a lateral view of the cartridge shaft seal; and

(6) FIG. 5 is a sectional view along the section line V-V in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(7) Referring to the drawings, the pump represented in FIG. 1 is a multi-stage centrifugal pump 1 of the inline construction type with a vertical, i.e. upright rotation axis. In the manner known per se, the pump comprises a foot 2, with which the pump 1 stands on the ground and with which the pump 1 can be fastened at the ground side. A cylindrical jacket component 3 extends from the pump foot 2 and is received towards the top by a pump head 4 which comprises a motor stool 5, to whose upper flange an electric motor 6 is fastened. A pump casing comprises the foot 2, the jacket 3 and the head 4.

(8) The foot 2 comprises a first connection flange 7 of a suction conduit as well as a second connection flange 8 of a delivery conduit which is arranged on the same axis at the other side to this. Pump stages, each comprising of an impeller 10 and a diffuser connecting thereto are arranged within the region of the jacket 3, so that the fluid which enters through the suction conduit at the first connection flange 7 into the pump casing runs from the bottom to the top through the pump stages amid an increase of pressure. The outlet of the last stage is led via an annular channel. The annular channel inner wall is formed by the outer wall of the diffusers and the annular channel outer wall is formed by the jacket 3. The annular channel leads the fluid back into the foot 7 and there to the delivery conduit on the second connection flange 8. The diffusers as well as the jacket 3 are clamped between the pump head 4 and the pump foot 2 by way of four tie-rods 9. The impellers 10, of which that one of the last pump stage is visible in FIG. 2, are seated on a shaft 11 in a rotationally fixed manner, said shaft 11 being led out of the pump casing in the region of the pump head 4 and there being connected to the free shaft end of the electric motor 6 by way of a coupling 12. The leading of the shaft 11 through the pump head 4 is realized by way of a cartridge shaft seal 13, the construction of which is evident in detail from FIGS. 3-5.

(9) The cartridge shaft seal 13 comprises a carrier 14 having an annular configuration and comprises an outer thread 15, with which the carrier 14 is fastened in a corresponding inner thread of an opening 16 of the pump casing, in particular of the pump head 4, amid the integration of an O-ring 17. Here, a flange 18 of the carrier 14 bears on the upper side of the pump head 4 in a manner surrounding the opening 16. A stationary slide ring 20 has a lower side that forms the actual sliding and axial sealing surface and on which the upper side of a rotating slide ring 21 bears as a mating surface. The stationary slide ring 20 is fixed in this carrier 14 in a rotationally fixed manner amid the integration of an O-ring 19. The rotating slide ring 21 is seated on a sleeve 22, rotationally fixed but axial movable thereto. The sleeve surrounds the shaft 11 in the region of the casing opening 16 and being connected to the shaft 11 in a rotationally fixed manner. The sleeve 22 is sealed with respect to the shaft 11 by way of an O-ring 23 and this O-ring 23 and is seated within a ring 24 which is fixedly connected to the sleeve 22. The ring 24 comprises two diametrically arranged lugs 25 which extend upwards from the upper side of the ring 24 and are seated in a ring 27 in a manner engaged with corresponding recesses 26. The ring is connected to the rotating slide ring 21 rotationally fixed and axially supporting this via a helical spring 28 which is arranged between the rings 24 and 27. An O-ring 40 which bears axially on the side of the slide ring 21 which is away from the sliding surface 21, as well as opposite and away from this, in a groove-like recess of the ring 27 which is open to the top, radially inwardly on the sleeve 22, is integrated between the rotating slide ring 21, the ring 27 and the sleeve 22. A sealing means is comprised of the O-rings. Inasmuch as this is concerned, the construction of the cartridge shaft seal 13 corresponds largely to the known cartridge shaft seals as are installed with Grundfos pumps of the type CR, which is referred to inasmuch as this is concerned.

(10) The fastening of the cartridge shaft seal 13 at the casing side is effected by way of the carrier 14. The fastening of the sleeve 22 at the shaft side is effected by way of a clamping device 29 which annularly encompasses the sleeve 22 and comprises two identically configured clamping components 30 which are connected to one another by way of two screws 31 and are non-positively fixed on the sleeve 22. With this configuration, the force action is so high that the sleeve 22 elastically deforms in the region of the clamping device 29 and is non-positively pressed onto the shaft 11, so that a non-positive fit is effected in the axial as well as rotation direction. The clamping device 29 is non-positively fixed on the sleeve 22 and this sleeve 22 is non-positively fixed on the shaft 11, by way of tightening the screws 31.

(11) In FIG. 3, the sleeve 22 protrudes out of the carrier 15 by an upper first axial section 22a and is only embraced by the clamping device 29 in that upper first axial section 22a. A lower second section 22b is embraced by the carrier 14. In order to facilitate the insertion of the shaft 11, the upper end 22c of the first axial section 22a of the sleeve 22 facing away from the second section 22b comprises a slightly (e.g. 1-10%) widened inner contour.

(12) The clamping components 30 comprise clamping jaws 32 which are adapted to the outer contour of the sleeve 22 and bear on this. These clamping jaws extend over an angle of the periphery of the sleeve 22 of 43 and are arranged diametrically to one another. Seen in the peripheral direction, a region which is designed distanced to the sleeve 22 and which extends over an angle of 95 connects to a clamping jaw 32 of a clamping component 30, after which a further contact surface 33 as a support surface connects, wherein this however only extends over a few degrees of the periphery. A peripheral extension of about 170 therefore results for each clamping component 30, so that a free space of a few degrees remains at the ends.

(13) Defined contact surfaces are formed via the support surfaces 33 and the clamping jaws 32 and the force application is effected by way of the screws 31. The screws 31 each have longitudinal axes 34 that are arranged perpendicularly to a radial partition plane 35 and parallel to tangents to the sleeve 22.

(14) The clamping jaws 32 and the support surfaces 33 are arranged close to the partition plane 35 and each clamping jaw 32 lies away from the sliding surface 36 of the same clamping component 30. The sliding surfaces 36 lie tangentially or parallel to this and parallel to the axes 34 of the screws 31, and are in contact with the mating sliding surfaces 37. These sliding surfaces 36 and mating sliding surfaces 37, which bear on one another in pairs, form guides and determine the direction, in which the clamping components 30 are movable to one another. They ensure that the screws 31 are kept largely free of transverse forces and together with the clamping jaws 32 form a formation which is roughly wedge shaped in cross section and which ensures that on moving the clamping components 30 to one another, thus on tightening the screws 31, transverse forces upon the sleeve 22 are produced, and these forces are larger than the longitudinal forces upon the clamping jaws, said longitudinal forces being caused by the tensile force of the screws 31. With this configuration, it is ensured that on tightening the screws 31 with the required torque, precisely that clamping force which is necessary to non-positively fix the sleeve 22 on the shaft 11 is provided. These surfaces 36, 37 can possibly be inclined by a few degrees, in order to further increase the clamping forces.

(15) Alternatively, but not represented in the embodiment example, the sliding surfaces and mating sliding surfaces can also each be formed by a pin and a recesses, provided as a matching piece to the pin. The clamping component on the one side comprises a pin and on the other side a recess, so that a peripheral surface of the pin forms a sliding surface and an inner peripheral surface of the recess forms a mating sliding surface.

(16) In the represented embodiment, the clamping device 29 is formed by two identical clamping components 30 and two screws 31, wherein the screws with their head rest on a head rest surface of the clamping component 30, are led through a bore-like recess (bore) 38 and are fixed in a blind hole 39 which is provided with an inner thread. For assembly, the cartridge shaft seal 13 is pushed over the free end of the shaft 11 and is fixed by way of screwing the carrier 14 into the opening 16 of the pump casing. After the clamping components 30 have been loosely connected to one another by way of screws 31, the clamping device 29 is then likewise pushed from above over the shaft 11, until the clamping device 29 lies loosely on the upper side of the carrier 14. The screws 31 are then uniformly tightened with a predefined torque, whereupon the clamping device 29 is non-positively fastened on the sleeve 22 in a manner such that the sleeve 22 is deformed elastically towards the shaft 11 and is fixed there, likewise non-positively.

(17) The cartridge shaft seal 13 can also be removed in the reverse sequence after undoing the screws 31. Since the clamping device 29 is only non-positively connected to the shaft 22, the complete cartridge shaft seal 13 can be taken apart and possibly repaired by way of exchanging worn parts. Since the sleeve 22 only bore non-positively on the shaft 11, the surface of the shaft 11 remains uncompromised due to this, so that the O-ring 23 which seals the sleeve 22 with respect to the shaft 11 can neither be damaged on disassembly nor on assembly of the cartridge shaft seal 13.

(18) While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

APPENDIX

List of Reference Numerals

(19) 1centrifugal pump 2pump foot 3jacket/jacket component 4pump head 5motor stool 6electric motor 7first connection flange suction conduit 8second connection flange delivery conduit 9tie rod 10impellers 11shaft 12coupling 13cartridge shaft seal 14carrier 15outer thread 16opening in the pump casing 17O-ring 18flange 19O-ring 20slide ring stationary 21slide ring rotating 22sleeve 22afirst axial section of the sleeve 22bsecond axial section of the sleeve 22cend of the first axial section of the sleeve 23O-ring 24ring 25lug 26recesses 17ring 28helical spring 29clamping device 30clamping components 31screws 32clamping jaws angle over which the clamping jaws extend angle between the clamping jaw and further contact surface 33further contact surface, support surface 34longitudinal axis of 31 35partition plane 36sliding surfaces/guide surfaces 37mating sliding surfaces/mating guide surfaces 38recess 39pocket hole 40O-ring