Divided stator casing

Abstract

A stator for eccentric screw pumps with a stator casing for an elastomer body for accommodating a rotor, the elastomer body being provided with at least one collar, wherein the collar is disposed in a recess between the stator casing and a connection body, wherein the fixing of the elastomer body in the stator casing is to be improved. The stator casing includes for this purpose open cavities, recesses and/or elevations at least at one side on the end face.

Claims

1. A stator for eccentric screw pumps comprising: a stator casing, an elastomer body for accommodating a rotor, said elastomer body being disposed within said stator casing, said elastomer body having at least one collar at one end of said elastomer body, said collar projecting outward away from a longitudinal axis of said elastomer body, wherein the collar is disposed in a recess between the stator casing and a connection body, wherein the stator casing comprises open cavities, recesses and/or elevations at least at one side on an end face of the stator casing, and wherein the collar is configured to be pressed against the end face and project axially into said open cavities, recesses and/or elevations.

2. The stator according to claim 1, wherein a distance between the stator casing and the connection body is smaller than a thickness (s) of the collar.

3. The stator according to claim 1, wherein the stator casing comprises a profiled body.

4. The stator according to claim 3, wherein the stator casing comprises a chamber profile.

5. The stator according to claim 4, wherein a wall thickness of the chamber profile is smaller than a thickness (s) of the collar.

6. The stator according to claim 1, wherein the stator casing comprises multiple parts.

7. The stator according to claim 6, wherein the stator casing is a longitudinally divided stator casing comprising at least two partial shells.

8. The stator according to claim 7, wherein the partial shells are connected to one another detachably.

9. The stator according to claim 8, wherein the partial shells are connected to one another by means of a form-fit connection and by means of a closure unit.

10. The stator according to claim 9, wherein the closure unit comprises a quick-action closure.

11. The stator according to claim 10, wherein the quick-action closure comprises a screw-snap closure.

12. The stator casing for a stator according to claim 1.

13. The stator according to claim 1, wherein said elastomer body comprises a helical recess for accommodating said rotor.

14. The stator according to claim 1, wherein said stator casing comprises an inner casing wall and an outer casing wall, said collar projecting radially outward over said inner casing wall of said stator casing.

15. The stator according to claim 14, wherein said collar projects radially outward below said outer casing wall.

16. The stator according to claim 14, wherein said stator casing comprises a plurality of partition walls which connect said inner casing wall to said outer casing wall, each partition wall extending along a radial axis of said stator casing.

17. The stator according to claim 1, wherein said collar extends a circumference of the elastomer body.

18. The stator casing for a stator, said stator casing comprising: an interior configured to house an elastomer body for accommodating a rotor, said elastomer body having at least one collar at one end of said elastomer body, said collar extending outward away from a longitudinal axis of said elastomer body, said collar being disposed in a recess between the stator casing and a connection body; and open cavities, recesses and/or elevations at least at one side of said stator casing on an end face of said stator casing; wherein said open cavities, recesses and/or elevations are configured to receive a portion of said collar projecting axially therein.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows the front section of an eccentric screw pump with a stator clamped between connection bodies,

(2) FIG. 2 shows the cross-section of the two-part stator shown in FIG. 1,

(3) FIGS. 3, 4, 5 show various embodiments of the closure unit,

(4) FIG. 6 shows the elastomer body provided at both ends with a collar, said elastomer body having a polygonal outer side,

(5) FIG. 7 shows a magnified detail of the clamped stator in the region of the stator/connection body connection, in a longitudinal cross-section representation.

(6) Identical parts are provided with the same reference numbers in all the figures.

DETAILED DESCRIPTION OF THE INVENTION

(7) FIG. 1 represents a front section of an eccentric screw pump 2 with a stator 10 clamped by means of threaded rods 8 between the closure bodies, housing 4 and connection flange 6. Stator 10 comprises a longitudinally divided stator casing 16, comprising two partial shells 12, 14, for an elastomer body 20 for accommodating a rotor, said elastomer body being provided with at least one collar 18. Stator casing 16 is produced from an aluminium alloy.

(8) Eccentric screw pump 2 is provided with two support feet 22 for assembling pump 2 on a pumping station provided for the purpose. With the aid of threaded rods 8, by tightening up threaded nuts 24, collar 18 is clamped between stator casing 16 and connection body 4, 6 to an extent such that stator casing 16 abuts against connection body 4, 6. The two partial shells 12, 14 are connected to one another on the one hand by means of a form-fit connection 26 and on the other hand by means of a closure unit 28. Closure unit 28 is located beneath a protective cover 30.

(9) FIG. 2 represents a cross-section of two-part stator 10 shown in FIG. 1. Stator 10 has a polygonal inner side and comprises an upper partial shell 12 and a lower partial shell 14, which are connected to one another on the one hand over the entire stator casing length by means of a form-fit connection 26 and on the other hand by means of an opposite-lying closure element 28 acting over the entire stator casing length. Form-fit connection 26 is constituted by a hook-shaped holding element 32 integrally moulded at one end of upper partial shell 12, said holding element engaging in a depression 34 introduced at the opposite end of lower half-shell 14. Disposed opposite form-fit connection 26 is closure unit 28, which represents a kind of screw-snap connection 36. The ends of partial shells 12, 14 run radially outwards on this side of stator 10 and are provided with bores for a fastening screw 38 introduced from above, said fastening screw being screwed into a link rod 40 provided with an internal thread. Disposed between the screw head and upper partial shell 12 is an intermediate plate 42 provided with through-bores, said intermediate plate serving in particular to distribute the forces acting during the screwing.

(10) A recess is introduced into the two partial shells 12, 14 at the end face of the radially running ends of partial shells 12, 14, said recesses forming a cable duct 44 for a sensor. This cable duct 44, on account of the special arrangement, opens during the dismantling of partial shells 12, 14. The dismantling essentially takes place by the fact that fastening screw 38 is loosened to an extent such that the latter, together with intermediate plate 42, can be folded away from stator 10 around rotational axis 46 of link rod 40. Closure unit 28 is thus opened and partial shells 12, 14 can be unfolded around form-fit connection 26 and removed. The assembly of partial shells 12, 14 takes place in an analogous manner in the reverse order.

(11) Partial shells 12, 14 are connected to one another by means of a plurality of such screw-snap connections 36. Fastening screws 38 can however be folded away from stator 10 in a work cycle, since the latter are coupled with one another by threaded rod 40 and intermediate plate 42. In order that the closure elements cannot fall out of the accommodation introduced into lower partial shell 14 after the folding-open, a loss prevention device 48 constituted as a radially running web is disposed beneath threaded rod 40. In order to protect closure unit 28 against soiling, protective cover 30 fitted on stator 10 is provided by means of snap closures.

(12) As can also be seen from FIG. 2, stator 10 comprises a chamber profile. Chambers 50 are constituted by an outer stator casing wall 52, an inner stator casing wall 54 and partition walls 56 running between the latter along stator 10. Chambers 50 represent, according to the invention, open cavities into which collar 18 of elastomer body 20 can dig in.

(13) FIGS. 3, 4 and 5 show various embodiments of the closure unit. Thus, FIG. 3 represents a closure unit wherein screwing of stator casing 16 takes place by means of clamping strips 60, which can be pushed into stator casing 16. In this embodiment, an opening in upper partial shell 12 smaller than the screw head serves as a loss prevention device for fastening screws 62, so that screw 62 can become unscrewed via the opening (not represented here) only as far as is possible inside stator casing 16, i.e. until the screw head abuts against the inner side of upper partial shell 12. A part of fastening screw 62 is still located inside clamping strip 60, so that screw 62 does not fall into the profile interior.

(14) FIG. 4 represents a closure unit 28, wherein a closure of partial shells 12, 14 takes place by means of a closure strip 64, which is drawn up to stator casing 16 by means of a fastening screw 66 and a threaded nut 68 integrated into upper partial shell 12 and as a result of which the two partial shells 12, 14 are closed on account of conically running contact faces 70.

(15) A closure unit 28 with pressure screws 72 is represented in FIG. 5. A strip 74 formed into a U-profile serves as a closure strip, said strip being provided with an internal thread for pressure screw 72. For the distribution of the pressure force, a steel strip 76 is pushed as an intermediate plate into upper partial shell 12, 14. The two partial shells are provided with a longitudinally running groove-shaped recess 78 for accommodating steel strip 76 and guiding U-profile strip 74.

(16) FIG. 6 shows, in a cross-section and a longitudinal section, elastomer body 20 made in a rubber-like material provided with a collar 18 at both ends, said elastomer body having a polygonal outer side. Collar 18 has a collar thickness s and a collar height h.sub.1, h.sub.2. Elastomer body 20 comprises a double-lead helical recess 80 for accommodating the rotor.

(17) When eccentric screw pump 2 is assembled, collar 18 first projects out of connection body 4, 6, since collar thickness s is greater than depth d of the recess in connection body 4, 6. Only after the clamping of stator 10 between connection bodies 4, 6 is the collar pressed into the recess in connection body 4, 6, until stator casing 16 then abuts against connection body 4, 6 in the assembled state of pump 2. Collar 18 is pressed into open chambers 50 of stator casing 16 at the end face, which leads to digging-in of collar 18 and therefore also to improved fixing of elastomer body 20 in stator casing 16.

(18) On account of the polygonal cross-sectional shape of elastomer body 20, different collar heights with h.sub.1<h.sub.2 result over its circumference. Effective digging-in into stator casing 16 is achieved by the fact that collar 18 has a height h.sub.1 which is greater than the wall thickness of inner stator casing wall 54. In order to arrive at the improved fixing of elastomer body 20 according to the invention, at least a collar height h.sub.2 has to be selected that is greater than the wall thickness of inner stator casing wall 54. The purpose of greater collar height h.sub.1, h.sub.2 is that collar 18 projects radially over inner stator casing wall 54, as result of which collar 18 digs in firmly into inner stator casing wall 54. Partition walls 56 in stator casing 16 likewise lead to an additional fixing of collar 18, which counteracts a rotational motion of collar 18.

(19) FIG. 7 shows a magnified detail of clamped stator 10 in the region of the stator/connection body connection, in a longitudinal cross-sectional representation. Closure body 4, 6 comprises a recess accommodating collar 18 and has a shape corresponding to collar 18. Depth d of the recess is smaller than collar thickness s, so that collar 18, which projects over inner stator casing wall 54, is pressed into chamber 50. Outer stator casing wall 52 and a part of partition wall 56 abut against the end face of closure body 4, 6, as a result of which a defined force acts on collar 18, which leads to the penetration of shoulder 18 into open chamber 50 of stator casing 16.

(20) Eccentric screw pump 2 is specifically designed for an effective and reliable operation of the pump, wherein stator 10 can be assembled and dismantled in a straightforward manner. In order to be able to fix elastomer body 20 particularly securely in stator casing 16, stator casing 16 comprises open cavities 50, recesses and/or elevations at least at one side on the end face. Digging-in of collar 18 of elastomer body 20 thus occurs, as a result of which an additional friction-locked and form-fit connection between collar 18 and stator casing 16 is achieved.

LIST OF REFERENCE NUMBERS

(21) 2 eccentric screw pump 4 pump housing 6 connection flange 8 threaded rod 10 stator 12 upper partial shell 14 lower partial shell 16 stator casing 18 collar 20 elastomer body 22 support foot 24 threaded nut 26 form-fit connection 28 closure unit 30 protective cover 32 holding element 34 depression 36 screw-snap connection 38 fastening screw 40 link rod 42 intermediate plate 44 cable duct 46 rotational axis 48 loss prevention device 50 chamber 52 outer stator casing wall 54 inner stator casing wall 56 partition wall 60 clamping strip 62 fastening screw (clamping strip) 64 closure strip 66 fastening screw (closure strip) 68 threaded nut 70 contact face 72 pressure screw 74 U-profile strip 76 steel strip 78 recess