Self-fixing stator housing

Abstract

A stator casing of an eccentric screw pump with an elastomer stator inner part including a plurality of shell-like casing segments and a production method for such a stator casing, with which the outlay for maintenance work can be reduced. According to the invention, casing segments adjacent in the longitudinal direction of the stator casing are disposed offset with respect to one another around the longitudinal axis of the stator casing, wherein each casing segment includes connection means and at least four casing segments engage with one another and form a composite. For the production of the stator casing, the casing segments are acted upon by an axial force component as a result of clamping, wherein the casing segments engage with one another, as a result of which a radial force component is generated and the composite is formed.

Claims

1. A stator casing of an eccentric screw pump with an elastomer stator inner part comprising a plurality of shell-like casing segments, characterised in that casing segments adjacent in the longitudinal direction of the stator casing are disposed offset with respect to one another around the longitudinal axis of the stator casing, wherein each casing segment comprises at least one connector, and at least four casing segments engage with one another and form a composite stator casing, and each of the four casing segments are adapted to be removed from the stator casing for replacement.

2. The stator casing according to claim 1, the at least one connector is also at least one positioner.

3. The stator casing according to claim 1, the casing segments adjacent in the longitudinal direction of the stator casing being disposed offset through 90 with respect to one another around the longitudinal axis of the stator casing.

4. The stator casing according to claim 1, the stator casing further comprising at least six casing segments.

5. The stator casing according to claim 1, at least two of the casing segments having different lengths from each other.

6. The stator casing according to claim 1, the elastomer stator inner part further comprising holding elements which fix the stator casing.

7. A casing segment for a stator casing according to claim 1, the at least one connector being constituted tooth-like at an end face.

8. The casing segment according to claim 7, further comprising at least one tooth flank of the tooth-like end face running helically around the longitudinal axis.

9. The casing segment according to claim 7, further comprising tooth flanks of the tooth-like end face running helically around the longitudinal axis in a region of a recess.

10. The casing segment according to claim 7, the at least one connector further comprising a V- or U-shaped recess running out in the longitudinal direction of the stator casing at the end face of the casing segment.

11. The casing segment according to claim 7, further comprising a recess introduced along a part of structural elements extending radially from an outer side.

12. The casing segment according to claim 7, further comprising a locking element which projects into a recess and that a recess corresponding to the locking element is introduced in an end region of a positioner.

13. An eccentric screw pump with a stator casing comprising a plurality of shell-like casing segments according to claim 1.

14. The stator casing according to claim 1, wherein the casing segments are clamped together to form the composite stator casing.

15. The stator casing according to claim 1, wherein the casing segments comprise metallic material.

16. The stator casing according to claim 1, wherein the casing segments each have substantially the same shape.

17. A stator casing of an eccentric screw pump, comprising four shell-like casing segments adjacent in a longitudinal direction of the stator casing disposed offset with respect to one another around the longitudinal direction, each casing segment having a connector to connect adjacent casing segments with each other and form a composite stator casing, each of the casing segments adapted to be removed from the stator casing for replacement.

18. A method for producing a stator, which is clamped in an eccentric screw pump, with an elastomer stator inner part which is surrounded by a plurality of shell-like casing segments, comprising the steps of clamping the casing segments so that they are acted upon by a longitudinal axial force component, engaging the casing segments with one another so that a radial force component is generated and a composite stator casing is formed.

19. The method of claim 18, wherein each of the casing segments are adapted to be removed from the composite stator casing for replacement.

20. A method of maintaining a stator produced according to claim 18, comprising replacing one of the casing segments.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the figures, diagrammatically:

(2) FIG. 1 shows a stator with a stator casing comprising four shell-like casing segments,

(3) FIG. 2 shows a casing segment of a stator casing from FIG. 1,

(4) FIG. 3 shows two casing segments adjacent in the longitudinal direction of the stator casing, said casing segments being disposed offset through 90 around the longitudinal axis of the stator casing,

(5) FIG. 4 shows the exploded representation of an eccentric screw pump with a stator comprising six shell-like casing segments, wherein two relatively large casing segments are disposed distributed centrally on the circumference of the stator and two relatively small casing segments are disposed in each case at the end faces and

(6) FIG. 5 shows an eccentric screw pump as shown in FIG. 4, with clamped casing segments.

DETAILED DESCRIPTION OF THE INVENTION

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

(8) FIG. 1 shows the stator (2) of an eccentric screw pump (4), which is surrounded at its circumference by shell-like casing segments (6) of equal size, which form the stator casing (8). On account of the inventive embodiment of the casing segments (6), the latter are disposed at the outer side of the elastomer stator inner part (9). The latter is made of a rubber-like material with elastic properties, whereas the stator casing (8) is produced from a metallic material. The elastomer stator inner part (9) is provided at its ends, on the end face, with projections constituted as a collar (10), which are adjoined by the stator casing (8) at the end face, wherein the stator casing (8) is held axially between the collars (10) and, on account of the elastic properties of the stator inner part (9), is pretensioned.

(9) Furthermore, the stator casing (8) is provided with structural elements (12) extending radially from its outer side, said structural elements surrounding the stator casing (8) in a rib-like or web-like manner. The axially running structural elements (12) serve in particular to ensure sufficient rigidity of the stator casing (8) and the structural elements (12) running at the circumference essentially serve to take up compressive forces acting in the stator. In the region of the connection points (14) of the casing segments (6), the structural elements (12) of a segment (6) are each formed together with an adjacent segment (6).

(10) Since the casing segments (6) are clamped over the length of the stator casing (8), recesses (30) are provided in the structural elements (12) to accommodate the clamping elements (28).

(11) An individual casing segment (6) of the stator casing from FIG. 1, with a V-shaped recess (16) running out in the longitudinal direction of the stator casing (8) at the end face and with a self-supporting length L, is represented in FIG. 2. The two tooth-like connection means (18) thus constituted comprise a helically running tooth flank (20) with a contact face wound around its longitudinal axis. The starting point (22) of the recess at the same time represents the start of the tooth flanks (20). From there, a projection extending the inner area of the casing segment (6) and constituted as a locking element (24) projects into the recess. A recess (26) corresponding to the locking element (24) is also introduced at the tooth-like tip in an end region of the connection means (18). The ends of the connection means (18) are truncated, mainly to counteract their being wedged in the adjacent casing segment (6).

(12) The locking element (24) and the recess (26) on the one hand constitute an additional locking means, but on the other hand also serve to compensate for manufacturing tolerances in the production of the casing segments (6).

(13) As represented in FIG. 3, the casing segments (6) adjacent in the longitudinal direction, in the case of a stator casing (8) as shown in FIG. 1, are disposed offset through 90 with respect to one another around the longitudinal axis. The inner side of the casing segments (6), as also the outer side of the elastomer stator inner part (9) not represented here, is constituted polygonal. The two casing segments (6) form a stator casing composite at the connection side by means of the helically running areas (20) of the connection means (18) and also by means of the locking element (24) constituting the locking means and the associated recess (30).

(14) On account of the connection means (18), the casing segments (6) can be jointed together without auxiliary means in a particularly straightforward and secure manner. The surface size of the tooth flank (20) also plays a decisive role. Since the wall thickness of the stator casing (8), for the purpose of saving weight and material, is rather small compared to the size of the casing segments (6), the area (20) should as far as possible be greater than the wall thickness. This is achieved by the fact that the recess (16) of the casing segments (6) is introduced along a structural element (12). As a result of the increase in the size of the area (20), the locking effect of the connection means (18) is also increased.

(15) An eccentric screw pump (4) with a total of six shell-like casing segments (6) is shown in FIG. 4. In this embodiment, two shortened casing segments (6a, 6b) are disposed in each case at the end faces of the stator casing (8), which are disposed on the one hand on a fastening flange (32) and on the other hand on a pump housing (34). Two relatively large casing segments (6) surround the stator inner part (9) centrally, between the shortened casing segments (6a, 6b).

(16) FIG. 5 shows a ready-assembled eccentric screw pump (4), as already represented in FIG. 4, with a stator (2) clamped by means of clamping elements (28) between a pump housing (34) and a flange (32). The clamping elements (28) run in the longitudinal direction of the stator casing (8), for which reason all the structural elements (12) are provided with recesses (30) along the clamping elements (28). In this embodiment, metal rods (28) serve as clamping elements, the ends whereof are provided with a metric screw thread. By screwing on and tightening up the associated screw nuts (36), the individual casing segments (6) are fixed and form a stable casing (8) around the elastomer stator inner part (9).

(17) The eccentric screw pump (4) is specifically designed for straightforward and time-saving assembly and dismantling of the stator casing (8) in order to keep the expenditure for replacement of the elastomer stator inner part (9) as low as possible. It is particularly advantageous that, as a result of the inventive structure of the stator casing (8), wherein the stator casing (8) is constituted by a plurality of self-retaining and self-centering casing segments (6), the casing segments (6) can be fitted to the elastomer stator inner part (9) without additional auxiliary means and without special knowledge and can also be removed again when necessary. The production and repair of such a stator casing (8) is also relatively low-cost, since the casing segments (6), in the case of a stator casing (8) with four casing segments (6) of equal size disposed at the circumference of the stator inner part (9) as shown for example in FIG. 1, are identical in their shape.

LIST OF REFERENCE NUMBERS

(18) 2 stator 4 eccentric screw pump 6 casing segment 8 stator casing 10 collar 12 structural element 14 connection point 16 V-shaped recess 18 connection means/positioning means 20 tooth flank (helical) 22 start of the tooth flank 24 locking element 26 recess for locking element 28 clamping element 30 recess for clamping element 32 fastening flange 34 pump housing 36 screw nut L self-supporting length