EP1552149B1 - Stator for a progressive cavity pump - Google Patents

Description

Technical area

The invention relates to a stator for an eccentric screw pump with a helical rotor. The stator has a likewise helically shaped cavity for receiving the rotor and usually consists of an elastic material which is enclosed by a rigid jacket.

State of the art

In the prior art rotors either a solid or a composite of several segments rigid jacket for receiving the elastic material of the rotor is used.

The DE 100 42 335 A1 shows a tube jacket for a push-in of an eccentric screw pump. The rotor shell consists of two longitudinal pipe segments, which are pivotally connected to each other in the axial direction, which come to lie adjacent to each other in the closed state of the pipe shell and are fixed together with at least one locking device in its closed position.

The two longitudinal pipe segments have a size corresponding inner radius in which a rotor receiving elastic lining comes into concern. After the pipe jacket consists of only two longitudinal pipe segments and these pipe longitudinal segments span only a specific cavity cross-section, this construction is only suitable for use for a certain pump size.

Next is in the US 4,313,717 discloses a rotor shell, which consists of three identical, axially arranged shell segments, which are clamped together by means of a belt. In this case, therefore, 3 adapted to the circumference of the rotor shroud segments and the corresponding clamping means for clamping the rotor shell to the rotor itself are necessary. Without these clamping means, the shell segments can not be held on the rotor.

From the DE 33 12 197 C2 is an eccentric screw pump with a jacket, which has by positive engagement interconnected segments known. The edges of adjacent segments are designed such that they engage each other in the manner of tongue and groove. These tongue and groove fasteners have contact surfaces so that they do not move relative to each other. Furthermore, these fasteners are provided exclusively at the ends of the segments, while along the other outer surfaces even a distance of the segments from each other is provided to allow adjustment of the diameter for adaptation according to the rotor wear. For this purpose, however, additional clamping means are necessary.

These prior art rotors of eccentric cam pumps have the disadvantage that for any size, e.g. H. For each diameter of a rotor, a special jacket, which is adapted to this diameter, must be provided. Thus, design costs, tooling costs and manufacturing costs for the jacket are again incurred for each type of pump. In addition, results in a wide production program a lot of effort in warehousing for different types of pumps.

Presentation of the invention

The invention has for its object to make the stator of a Exzenterschnekkenpumpe such that a cost-effective and simplified construction is possible.

Inventive solutions to this problem are specified in the claims 1 and 25. Further developments of the invention are the subject of the dependent claims.

The stator for eccentric screw pumps according to the invention comprises a hollow body made of elastic material, which is enclosed by a shell of segments.

The longitudinal sides, at least several, but preferably all segments, are formed such that adjacent segments along the circumferential angle are variably connected to each other to produce a load-bearing positive connection and the surfaces of the individual segments are predominantly in a plane. In a typical case, such an angular range is about 10 °. By this embodiment of the compound different numbers of elements to different diameters of the coats can be combined. Thus, for example, 10, 11, 12, 13 or even 14 segments can be combined to form a jacket, each with the segment number corresponding diameter. Similarly, segments of different widths can be combined. This is Already with a few (for example two) different profiles by corresponding combinations and different numbers a variety of different diameters of the shell feasible. The specification of the length of a segment always refers to the extension in the longitudinal direction of the stator.

Furthermore, in a particularly advantageous embodiment of the invention, the individual segments are designed such that the result of the connection of several segments is a closed shell in polygonal shape. This polygon shape now engages in a corresponding polygonal shape of the outside of the hollow body of elastic material, so that there is a form fit for transmitting the torque.

The segments themselves can be made from a variety of different materials. Particularly suitable are metallic, ceramic, elastomeric or thermoplastic materials. Likewise, the segments may consist of combinations of different materials. Thus, for example, a combination of a metallic longitudinal edge and an elastomer disposed between the longitudinal sides to compensate for tolerances can be used.

In another advantageous embodiment of the invention, the connection between the individual segments is designed in the manner of tongue and groove. However, it is essential for the embodiment according to the invention that the segments connected in this way are movable relative to one another.

In a further advantageous embodiment of the invention, the connection of the segments with each other is designed such that they can be pushed together in the longitudinal direction. Thus, the entire unit is particularly low, by simply pushing the segments together, mountable. Another embodiment of the invention provides that the segments have bores extending in the longitudinal direction.

Furthermore, the longitudinal sides of segments by additional fasteners, such as bolts, pins, rods or rivets, may be connected together in the longitudinal direction.

In a further advantageous embodiment of the invention, the longitudinal sides of the segments on circular, interlocking profiles. This circular arrangement makes it particularly easy to realize mobility in a large angular range.

Another embodiment of the invention provides that the longitudinal sides of the segments have angular profiles, such as polygonal or dovetail profiles. In order to ensure sufficient mobility here appropriate distances are provided.

Another embodiment of the invention provides that the length of individual segments is shorter than the length of the hollow body. Thus, at least two segments can be arranged one behind the other in the longitudinal direction of the hollow body.

Furthermore, advantageously at least two longitudinally successive segments can be laterally, i. in the direction of the circumference of the hollow body, be offset from each other. The offset preferably corresponds to the width of a single segment.

In a particularly advantageous embodiment, at least two segments are connected together in the form of chain links. A particularly simple and inexpensive design of the arrangement results when all the segments are connected together in the form of a large chain. So is, Particularly in the case of a large number of small chain links, optionally in the longitudinal direction or in the direction of the circumference, adaptation to the desired length of the hollow body or the circumference of the hollow body is possible.

Advantageously, at least a plurality of segments in the form of chain links are provided with spacers or integrated connecting elements. As a result, several such segments can be combined into a composite in a first preassembly step. Such pre-assembly is possible in a simple manner with an automatic assembly machine. For final assembly to the hollow body then only a few rows of chain links, for example by means of bolts, must be connected to each other. With a suitable arrangement of the connecting elements, the last chain link can be mounted rotated in a row by 180 degrees, so that the row of chain links is flush.

In a further advantageous embodiment of the invention means are provided for limiting the angular range of movement of the segments with each other. As a result, the mobility of the mounted polygon can be restricted in order to simplify the mountability, to prevent jamming of the segments with each other or to increase the rigidity of the shell.

In a further advantageous embodiment of the invention, an additional non-positive connection of the longitudinal sides of the segments is provided. Such a connection can be, for example, a welded connection or also an adhesive connection. Such a connection is usefully made after the individual segments have been pushed together. Thus, by means of the frictional connection, the individual segments can be fixed together in a predetermined angle corresponding to the final configuration.

In another embodiment of the invention, an additional frictional connection between at least one, preferably a plurality of segments and the hollow body made of elastic material is provided. Such a connection can take place, for example, by vulcanization or gluing.

Another embodiment of the invention provides that at least one segment has a surface with a particularly high roughness or additional holding teeth or a corrugation. This particular surface of the segment faces the hollow body. Due to the rough surface, the friction between the segments and the hollow body can be substantially increased, whereby the twisting / twisting of the hollow body is avoided during the rotation of the rotor.

In a further advantageous embodiment of the invention, at least one segment has at least one additional contact surface for supporting the hollow body. Thus, the contact surface of the hollow body at the segments, d. H. the area of the introduction of force between the hollow body and the segments to be increased. This leads to a higher stability and a lower deformation of the hollow body.

In a further advantageous embodiment of the invention, the hollow body made of elastic material is designed such that it overlaps the segments at the end faces. This results in a sealing of the segments by the elastic material of the hollow body.

A further embodiment of the invention provides that at least some segments consist of a mechanically rigid material which has a substantially higher stiffness relative to the hollow body of elastic material.

In a further advantageous embodiment of the invention, at least some of the segments have an elastic material.

A further embodiment of the invention is that at least one clamping means is provided, with which the diameter of the shell consisting of segments can be fixed or adjusted. This makes it possible to make an adjustment of the diameter with increasing wear of the hollow body made of elastic material.

Another embodiment of the invention provides additional support rings, which support the segments from the outside. As a result, the individual segments can not deform outward even at high pressures in the hollow body. The equipment with support rings can be made variable, so that according to the pressure in the hollow body at higher pressure, a correspondingly higher number of support rings is used.

In a further advantageous embodiment of the invention, the thermal expansion coefficient of the segments is dimensioned such that it compensates for the coefficient of thermal expansion of the hollow body of elastic material.

In a further embodiment of the invention, at least one loosely insertable anti-twist device is provided between the hollow body and the stator jacket. This can for example consist of a rod or a profile, which is advantageously inserted in the longitudinal direction and represents a positive connection between the shell and the hollow body.

An inventive hollow body of a stator made of elastic material for eccentric screw pumps according to the invention has a helical cavity for receiving a rotor and an outer side with a polygonal cross-section. The polygonal outer side is doing with a frictional connection the polygonal inside of the shell. It is immaterial whether the individual faces of the polygon are the same size or different. It is essential that the hollow body has a plurality of longitudinally extending surfaces.

Description of the drawings

• Fig. 1 zeigt in allgemeiner Form schematisch eine erfindungsgemäße Vorrichtung.
• Fig. 2 zeigt einen erfindungsgemäßen Mantel in perspektivischer Ansicht.
• Fig. 3 zeigt ein einzelnes Segment.
• Fig. 4 zeigt Segmente unterschiedlicher Länge.
• Fig. 5 bis 7 zeigen unterschiedliche Kombinationen von Segmenten
• Fig. 8 zeigt Segmente mit Stützringen
• Fig. 9 bis 19 Anordnung mit kurzen Elementen

The invention will now be described by way of example without limitation of the general inventive idea by means of embodiments with reference to the drawings.

• Fig. 1 shows in a general form schematically a device according to the invention.
• Fig. 2 shows a jacket according to the invention in a perspective view.
• Fig. 3 shows a single segment.
• Fig. 4 shows segments of different lengths.
• Fig. 5 to 7 show different combinations of segments
• Fig. 8 shows segments with support rings
• Fig. 9 to 19 Arrangement with short elements

In Fig. 1 a device according to the invention is shown in section. A stator for eccentric screw pumps has a hollow body 1 of preferably elastic material. In a helical cavity 2, a likewise helical rotor 3 is accommodated. The outer contour of the hollow body 1 made of elastic material has a polygonal cross-section. The jacket, which comprises the hollow body, consists of a plurality of segments 4a, 4b, 4c, which extend in the longitudinal direction (axially) of the hollow body. The segments are positively connected with each other. The compound is resilient to train and thus limits the extent of the circumference of the hollow body.

In Fig. 2 a sheath according to the invention is shown in perspective. This jacket consists in this example of 12 segments, three of which are exemplified by 4a, 4b, 4c. Of course, versions with other segment numbers, such as 10 segments or 14 segments can be realized. In any case, at least three segments are necessary to enclose a cavity. The upper limit for the number of segments results from the cost-effectiveness of the assembly. So a coat with an extremely high number of segments will be mountable only at high cost. Unless he is, as described later, realized in the form of a chain.

Fig. 3 finally shows a single segment 4 in section. The connection of the individual segments with each other takes place here by a first connecting element 5, which is in engagement with a second connecting element 6 of another segment. Due to the special embodiment proposed here, the segments are movable relative to one another in a certain angular range.

In Fig. 4 For example, segments of different widths are shown, from which coats of different diameters can be produced by combination. These are hereinafter referred to as Type 1 (11), Type 2 (10), Type 3 (9) and Type 4 (8). Of course, any dimensions of segments are the subject of the invention.

In Fig. 5 a combination of 6 segments of the type 4 (8) and the type 3 (9) is shown, wherein the segments of different types are each alternately combined.

In Fig. 6 is shown another combination of different segments. There are five segments of type 4 (8) and type 2 (10) each alternately combined. This results opposite to in Fig. 5 illustrated arrangement a different shape of the outer contour and another diameter.

In Fig. 7 a combination of 12 similar type 3 (9) segments is shown. The representations of the different combinations of segments in the various figures are not to scale.

Fig. 8 shows an arrangement in which preferably for receiving higher pressures additional support rings 12a, 12b, 12c are mounted. Such support rings preferably run along the circumference and may themselves again have fastening means such as bores, on the one hand for fixing to the segments and on the other hand for fixing the support rings themselves or the entire device. Furthermore, end rings 13a, 13b are shown, which additionally support the segments at their ends. The support can be made here preferably in the longitudinal direction but also radially, as in the support rings described above.

In Fig. 9 a further advantageous embodiment of the invention is shown in which the individual segments 4a, 4b, 4c are connected together in the form of a chain. For this purpose, the segments at their ends holes through which fasteners such as bolts 18, rivets or others can be inserted.

Fig. 10 shows a single segment 4 of an arrangement accordingly Fig. 9 , In the enlarged view, the holes 15 and the bearing surfaces 14 can be seen. The bearing surfaces serve, as far as they are associated with the hollow body of elastic material facing inside of the chain, for supporting the hollow body. Thus, a large-scale support of the chain and thus a trouble force in the hollow body can be realize. A corresponding nearly closed inner surface is in Fig. 9 to recognize.

Fig. 11 shows another chain-like arrangement of the individual segments 4a, 4b, 4c. In the enlarged section, the interaction of the individual chain links is clearly visible. The connection of the individual segments to a chain takes place again with the help of the holes and the fastening elements, not shown here, which are held in these holes.

In Fig. 12 is a single segment 4 of the chain-like arrangement Fig. 11 shown. The bore 15 serves to connect a plurality of segments. The holding teeth 16 serve to increase the friction between the segments and the hollow body made of elastic material.

Fig. 13 shows a further chain-like arrangement of individual segments 4a, 4b, 4c, wherein the segments are connected by bolts other than by additional connecting elements.

Fig. 14 shows in a detailed view individual segments with connecting elements 17, which simultaneously establish a defined distance between segments. Depending on the design, the connecting elements can fix the individual segments in arbitrary axes to each other. Thus, for example, a lateral or a fixation in the longitudinal direction of the stator is possible.

Fig. 15 shows in a detailed view of the fully assembled segments with associated fasteners. This arrangement of the segments results in a relatively rigid composite. Thus, the overall rigidity of the shell is significantly increased. This is particularly advantageous at high pressures.

In Fig. 16 a chain-like arrangement is shown in which the individual segments have particularly large bearing surfaces. This results in an almost closed inner surface.

Fig. 17 shows a single segment of the assembly Fig. 16 , Here is the enlarged support surface 14 is particularly easy to see.

Fig. 18 shows a further embodiment of the segments of an arrangement Fig. 16 , In this case, the support surface on additional retaining teeth 16.

Fig. 19 shows another chain-like arrangement with gaps between the chain-shaped segments.

LIST OF REFERENCE NUMBERS

1

Hollow body made of elastic material

2

helical cavity

3

rotor

4, 4a, 4b, 4c

segments

5

First connection element

6

second connecting element

7

Outside of the hollow body

8th

Segment Type 4

9

Segment Type 3

10

Segment type 2

11

Segment Type 1

12a, 12b, 12c

supporting rings

13a, 13b

end rings

14

bearing surface

15

drilling

16

retaining teeth

17

connecting element

18

bolt

Claims (25)

1. A stator for eccentric screw pumps, comprising a hollow body (1) of elastic material, which comprises a helical hollow space (2) for accommodating a rotor (3) and is provided on the outer side with a casing, wherein the casing comprises a plurality of elements (4, 4a, 4b) connected to one another and extending in the axial direction, so that adjacent segments are connected to one another in a varying manner along the circumferential angle in order to produce a form-fit connection capable of being subjected to tensile load,
   characterised in that the surfaces of the individual segments lie predominantly in a plane, as a result of which different diameters of the casing can be combined from the different number of segments.
2. A device according to claim 1,
   characterised in that approximately a polygonal shape results from the connection of a plurality of segments to form a closed casing and the outer side (7) of the hollow body of elastic material has approximately a polygonal shape with a number of surfaces corresponding to the number of the segments along the circumference, so that a form-fit connection between the hollow body of elastic material and the mutually connected segments results.
3. The device according to claim 1 or 2,
   characterised in that
   the longitudinal sides of at least two segments (4, 4a, 4b) are constituted in such a way that adjacent segments engage in one another and produce a form-fit connection capable of being subjected to tensile load.
4. The device according to any one of the preceding claims,
   characterised in that
   the longitudinal sides of a plurality of segments (4, 4a, 4b) are constituted in such a way that they can be pushed together in the longitudinal direction.
5. The device according to any one of the preceding claims,
   characterised in that
   a plurality of segments comprise bores (15) running in the longitudinal direction.
6. The device according to any one of the preceding claims,
   characterised in that
   a plurality of segments (4, 4a, 4b) are connected to one another in the longitudinal direction by fastening elements, such as for example bolts (18).
7. The device according to any one of the preceding claims,
   characterised in that
   the longitudinal sides of a plurality of segments comprise circular profiles engaging into one another.
8. The device according to any one of the preceding claims,
   characterised in that
   the longitudinal sides of a plurality of segments comprise angular profiles engaging into one another.
9. The device according to any one of the preceding claims,
   characterised in that
   the length of the individual segments is shorter than the hollow body and at least two rows of segments are disposed behind one another in the longitudinal direction of the hollow body.
10. The device according to any one of the preceding claims,
    characterised in that
    at least two segments following one another in the longitudinal direction are preferably offset laterally with respect to one another by the width of a segment.
11. The device according to any one of the preceding claims,
    characterised in that
    at least two segments are connected to one another in the form of chain links.
12. The device according to claim 10,
    characterised in that
    at least two segments comprise connecting elements which are integrated in the form of chain links and which connect the individual chain links to one another.
13. The device according to any one of the preceding claims,
    characterised in that
    means are provided for limiting the angular range of the movement of the segments with respect to one another.
14. The device according to any one of the preceding claims,
    characterised in that
    an additional friction-locked connection of the segments with one another is provided.
15. The device according to any one of the preceding claims,
    characterised in that
    an additional friction-locked connection is provided between the segments and the hollow body of elastic material.
16. The device according to any one of the preceding claims,
    characterised in that
    at least one segment comprises, at a side facing the hollow body, a surface with a particularly high degree of roughness or additional retaining teeth.
17. The device according to any one of the preceding claims,
    characterised in that
    at least one segment comprises at least one additional seating surface for supporting the hollow body.
18. The device according to any one of the preceding claims,
    characterised in that
    the hollow body of elastic material overlaps the end faces of the segments.
19. The device according to any one of the preceding claims,
    characterised in that
    the casing comprises segments which are made of a material which has a much greater stiffness compared to the hollow body of elastic material.
20. The device according to any one of the preceding claims,
    characterised in that
    the casing comprises segments of elastic material.
21. The device according to any one of the preceding claims,
    characterised in that
    at least one additional clamping means is provided for reducing the diameter of the casing comprising individual segments.
22. The device according to any one of the preceding claims,
    characterised in that
    additional support rings (12a, 12b, 12c) are provided, which support the segments from the outer side.
23. The device according to any one of the preceding claims,
    characterised in that
    the thermal expansion coefficient of the segments is dimensioned corresponding to the thermal expansion coefficient of the hollow body of elastic material, so that the latter is compensated for.
24. The device according to any one of the preceding claims,
    characterised in that
    at least one loose insertable anti-rotation means is provided between the hollow body and the stator.
25. A hollow body (1) of a stator for eccentric screw pumps according to claim 1 of elastic material, which comprises a helical hollow space (2) for accommodating a rotor (3),
    characterised in that
    the outer side of the hollow body has a polygonal cross-section.

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