EP1222396B1 - Stator with rigid retaining ring - Google Patents

Abstract

On an eccentric screw pump or an eccentric screw motor, both the outer wall and the inner wall of the jacket (21) have a helicoid form. In order to stabilise the cross-sectional profile of the jacket (21) in the vicinity of the ends and to allow it to be simply coupled to the other housing sections (5, 6), a retaining ring (28) sits on each end of the jacket (21). The retaining ring contains a through channel (32), whose cross-sectional surface has a form which substantially corresponds to the cross-sectional surface that is delimited by the inner wall (23) or outer wall (24).

Description

The essential components of an eccentric screw pump are the stator, the rotor running in it and the Drive for the rotor. The rotor has the shape of a one or multi-turn screw and rotates in the hole of the stator, which is also a helical shape has, the number of gears of the bore of the stator is higher than the number of turns of the screw of the rotor.

To the required seal between the stator and To achieve the rotor is the stator with an elastomer Provide lining against which the rotor rests sealed. Sickle or arise between the rotor and the stator Banana - shaped chambers, which differ from one another when the rotor runs move the suction side to the pressure side. In these chambers the medium is promoted.

Eccentric screw pumps are suitable for the transport of viscous media under high pressure and for conveying Media with solid particles. In addition, this Use the design principle as a motor if that Medium is pressed into the arrangement under high pressure, whereby the rotor in the stator is rotated. Applications of this are so-called underground drilling motors.

Both the stator and the are due to their function Rotor wear parts that require regular replacement require. This requires a disassembly that is natural should be as easy as possible, especially then when it comes to pumps or motors of large design is.

The stator is two different Construction forms known. With one type of construction the lining is in a smooth cylindrical Tube, the screw-shaped contour being exclusive limited to the elastomeric lining. The elastomer Lining is thus in the area of the thread tips more flexible than in the area of the thread valleys. With pumps In this way, a lower pressure can be generated per stage, because the greater flexibility in the area of the thread tips limits the maximum pressure.

In the other design, the jacket is also again a tube, but that in turn is screw-shaped is deformed. The lining has everywhere constant both in the longitudinal direction and in the circumferential direction Wall thickness. This allows comparative achieve very high pressures.

While in the embodiment with a cylindrical jacket the connection to the other pump housing parts is proportionate is simple, it is screw-shaped reshaped tube problematic. The cross section of the pipe has in the simplest embodiment with a two-course Screw the shape of a racetrack-like shape Ovals, the available end face of the Coat is comparatively narrow. Accordingly difficult is the seal and the attachment to the pump housing to accomplish.

In addition, the screw is designed Coat at the ends sensitive to deformation due to of the pressure built up inside. While in the middle area of the stator contribute to the adjacent stator areas to stabilize this area in its shape, free edges appear at the ends, which is on the print side can easily lead to deformation and thus to a Pressure loss, which is the maximum possible pressure of the pump limited.

To a stator according to the latter embodiment is designed to be detachably mounted in a pump, it is known from EP 0 935 072 A1, at both ends to use one connection tube each. The two Tubes are attached to the actual stator tube by tie rods pressed. In order to allow a certain lateral fixation, is each tube on the system side for the tube of the Stator provided with an annular bead, the course of about has the shape of a race track oval. Because of the helical External shape of the stator tube arise proportionately large empty spaces where the stator wall diverged from the bead wall while large interiors arise where the bead in the area of its apex rests on the outer wall of the stator tube.

Based on this, it is an object of the invention To create eccentric screw pump or motor, its stator has a screw-shaped jacket and which can be easily connected to the rest of the housing, its ends without any significant increase in the axial Length effective against shape changes due to static Pressure of the medium are protected.

This object is achieved by an eccentric screw pump or an eccentric screw motor with the Features of claim 1 solved.

Die komplizierte Geometrie des Statorendes wird in eine Geometrie überführt, die leicht mit den Teilen des Pumpengehäuses verbindbar ist. Dabei wird gleichzeitig eine ausreichend große Fläche zum Unterbringen von Dichtungen geschaffen. Die Flächen sind groß genug, um ein Zerquetschen der Dichtung wirksam zu verhindern.

With the help of the end ring, the through opening of which continues the screw-shaped shape of the interior of the stator casing, two things can be achieved:

The complicated geometry of the stator end is converted into a geometry that can be easily connected to the parts of the pump housing. At the same time, a sufficiently large area is created to accommodate seals. The areas are large enough to effectively prevent the seal from crushing.

The front ring also allows for no extension the stator end against expansion due to the design of the stator secure, especially the straight section of the jacket cross-section sensitive to deformation sinks. These areas are stabilized by the front ring and get a similar strength as this is accordingly in the middle area of the stator applies.

For example, the end ring can be used as a flange plate be formed with a corresponding flange on Pump head or lying flat on top of each other at the connection head can be screwed.

The fundamentally different embodiment the front ring consists of a narrow ring with a circular outer contour that fits into a corresponding one Stepped bore, which is designed as a seat, on the pump head or can be plugged into the connection head. Here too correspondingly large sealing surfaces are created. The coat of the stator in the sections that are not very curved of the cross-sectional profile particularly reinforced because in these areas the face ring results from the cylindrical Has a particularly large wall thickness and is rigid.

To the brow ring with the coat of the To connect stator, there are basically two embodiments in question. In one case the front ring shows a through opening that seen along its length has a constant cross section, the cross section with essentially corresponds to the outer cross section of the jacket, so that the brow ring is like a kind of mother on the Coat can be screwed on. To screw it on too far of the face ring on the jacket is to be prevented a shoulder is formed on the coat. The shoulder can either by applying material to the location of the shoulder be formed, or by starting from the front of the Jacket is removed on the outer peripheral surface material. The easiest way to remove the material is by the outer surface of the jacket over the length over which the front ring is to be screwed on, is turned over. As a result, the outer contour is only changed at those points where the mantle has the greatest radial extent Has. It is understood that the inner contour of the opening in the brow ring to this modified outer contour of the jacket is adjusted so that only a very small assembly gap between the through hole and the outer peripheral surface of the coat comes about. This embodiment has about it furthermore the advantage that the brow ring at its weakest point receives a usable wall thickness.

The other of the two variants mentioned above exists in the use of a face ring where the through hole is designed as a stepped bore, so that in the front ring a shoulder arises, which is when the Brow ring on the coat on the end face. In in this case the cross section of one section corresponds the stepped bore of the outer cross section of the jacket during the small section of the stepped bore a fairly accurate continuation of the interior of the jacket represents.

In all cases, a right-angled position of the End faces of the end ring opposite the axis of the jacket guaranteed.

The attached brow ring can be used for further improvement the stability with the jacket cohesively become. This is conveniently done by the face the jacket is welded to the front ring. On exclusive welding on the outside would also be conceivable, but would have a gap on the inside left over who may work under load, and could damage the solid lining.

Fig. 1 eine Exzenterschneckenpumpe in einer perspektivischen Darstellung und teilweise aufgeschnitten,

Fig. 2 den Stator der Exzenterschneckenpumpe nach Fig. 1, in einem Längsschnitt,

Fig. 3 ein Ende des Stators mit dem aufgesetzten Stirnring mit abgeschnitten dargestellten Mantel und

Fig. 4 den Stirnring und einen Abschnitt des Mantels, in einer perspektivischen Explosionsdarstellung.

An exemplary embodiment of the subject matter of the invention is shown in the drawing, in which:

1 is an eccentric screw pump in a perspective view and partially cut away,

2 shows the stator of the eccentric screw pump according to FIG. 1, in a longitudinal section,

Fig. 3 shows one end of the stator with the attached end ring with the jacket shown cut off and

Fig. 4, the end ring and a portion of the shell, in a perspective exploded view.

Fig. 1 shows a schematic, perspective Representation of an eccentric screw pump according to the invention 1. The eccentric screw pump 1 includes a pump head 2, a stator 3, in which a broken off in Fig. 2 Illustrated rotor 4 rotates, as well as a connection head 5th

The pump head 2 has a substantially cylindrical Housing 6 on that at one end with an end cover 7 is provided, sealed by a Drive shaft 8 is guided to the outside. In the housing 6 Radially opens a connecting piece 9, which on a mounting flange 11 ends. Located inside the housing 6 as usual with eccentric screw pumps Coupling to the drive shaft 8, which is not connected to one shown drive motor is connected to the rotor 4 non-rotatably coupled.

The front end of the housing remote from the cover 7 6 is provided with a clamping flange 12, the diameter of which is larger than the diameter of the substantially cylindrical Housing 6. The clamping flange 12 contains one Stepped bore 13, which with the interior of the housing 6th flees. There is a flat contact shoulder in the stepped bore 14 formed against which the stator 3 with one end is pressed.

The connection head 5 has one with the clamping flange 12 cooperating clamping flange 15, which also contains a stepped bore in the other end of the stator 3 is used. One is aligned with the stepped bore outgoing pipeline 16.

Between the two clamping flanges 12 and 15 is with A total of 4 tie rods 17 sealed the stator 3 tightened. To accommodate a total of 4 tie rods 17 the two clamping flanges 12 and 15, each with four aligned holes 18 provided on a Pitch circle that is larger than the outer diameter of the housing 6 or the tube 16. Through these holes 18 guide the rod-shaped tie rods 17 through. On the from the opposite clamping flange 12 or 15 Side are screwed onto the tie rods 17 nuts 19, with the help of the two clamping flanges 12 and 15 to be tightened to each other.

The stator 3 consists, as shown in FIG. 2, of a tubular one Jacket 21 with constant wall thickness, the one Interior 22 surrounds. The jacket 21 is made of steel, one Steel alloy, light metal or a light metal alloy. It is shaped so that its inner wall 23 has the outer shape a multi-start screw. Its outside 24 has a similar shape and borders a cross-sectional area that corresponds to the wall thickness of the jacket 21 is larger than the cross-sectional area, which is delimited by the inner wall 23.

The jacket 21 ends at its ends with end faces 25 and 26, which are rectangular with respect to a longitudinal axis 27 run. The longitudinal axis 27 is also the axis of the jacket 21, or of the interior 22.

In the simplest case it has a two-start screw the cross section of the interior 22 and thus also the cross section, which the outer surface 22 surrounds, each at right angles seen to the longitudinal axis 27, the shape of an oval similar to a racetrack. To this oval geometry to the To adjust stepped bore 13, sits on the jacket 21 a reducer or front ring 28 at each end. It exists made of the same material as the jacket 21.

The shape of the end ring 28 and the exact outer geometry of the jacket 21 in the region of the end ring 28 3 and 4 explained in detail below with reference to FIGS.

The end ring 28 is planar in the longitudinal direction End face 29 bounded by a cylindrical Outer peripheral surface 31 connects. Through the front ring 28 leads a through opening 32 which is enclosed by a wall 33 is. The through opening 32 has a cross-sectional area, which essentially with the cross-sectional area matches the outer wall 24 of the jacket 21st circumscribed. The shapes are not exactly the same. The Difference arises from that given below Explanation of the stator geometry.

The through opening 32 has a helical shape Shape, the number of gears and the slope with the number of gears and the slope of the helical shape of the Outer wall 24 of the jacket 21 matches.

The jacket 21 is, as shown in FIG. 4, on his Outside turned over. This creates in those areas the cross-sectional area through the outer wall 24 is defined, a reduction in diameter follows the outer wall 24 in the region of the overturn a cylinder surface 34th

The overturn leaves with a two-start screw a total of two crescent shoulders 35 arise have a distance from the ends 24, 26 that is the length corresponds to the overturn and the two in one Plane that is parallel to a plane, which is defined by the front end 25 or 26. The axial Depth of rotation i.e. the distance between the shoulders 35 there is something of the respectively adjacent end 25 or 26 less than the thickness of the end ring 28.

Retains despite the overturning of the outer peripheral surface the outer wall 24 also in the area between the front end 25 or 26 and the adjacent shoulders 35 a helical Shape whose slope is the slope of the mantle 21 beyond the shoulders 35 matches.

As a result of the overturning, the wall thickness of the jacket 21 on the thread tips between the shoulders 35 and adjacent end 25 or 26 slightly less than in the other areas. The reduction in wall thickness is limited on the thread tips.

The cross-sectional area of the through hole 32, such as it is delimited by the wall 33 corresponds to the cross-sectional area, the outer wall 24 of the jacket 21 in the area between shoulder 35 and the next adjacent one Front end 25 and 26 bounded.

As a result of this configuration of the end ring 28, it can similar to a nut screwed onto a screw will be screwed onto the outside of the jacket 21, until its opposite end face 29 Front surface abuts the shoulders 35.

After putting on the end ring 28 the configuration obtained as shown in Fig. 3. Between the plane surface 29 and the adjacent end 25 or 26 arises a groove 37 which is closed in itself. In the area the groove 37 is after the end ring 28, the end ring 28 with the relevant end face 25 or 26 welded. The result is that in FIG. 2 recognizable weld seams 38.

Both end rings 28 are identical, though the wall thickness of the end ring 28 on the left side of the Figure 2 in the sectional view is smaller than the wall thickness of the face ring 28 on the right side. this has its cause is that the cross-sectional profiles on the Face 25 against the cross-sectional area on the End face 26 are rotated by 90 °.

Inside, the jacket 21 is all over Length provided with a continuous lining 39. The Lining 39 is made of an elastomeric material, for example Rubber and has the same wall thickness at every point on.

The lining goes on both ends of the stator 3 39 each in one piece in a seal 41 or 42 about. The seals 41, 42 have the shape of a plan Rings, the outer peripheral surface 43 with the outer peripheral surface 31 of the respective end ring 28 is flush. The one Side of the seal 41, 42 is integral with the flat surface 29 of the relevant end ring 28 connected while the flat surface 44 lying away from it shows away from the stator 3 and represents the actual sealing surface.

The lining 39 is also in the area of the weld seams 38 held integrally.

When the stator 3 shown in the stepped bores 13 of the two clamping flanges 12 and 15 is inserted the relevant seals 41,42 on the shoulder 14 in of the respective stepped bore 13. By tensing the Tie rods 17 are the clamping flanges 12 and 15 with their Shoulders 14 sealingly pressed against the seals 41 and 42.

Zunächst wird aus einem ursprünglich zylindrischen Rohr durch Kaltverformen der Mantel 21 erzeugt, der die gewünschte schrauben-förmige Gestalt aufweist. Sodann wird der Mantel 21 ausgehend von seinen beiden Stirnenden 25 und 26 auf der Außenseite ein Stück weit überdreht, um die sichelförmigen Schultern 35 zu erzeugen. Beim Überdrehen des Mantels 21 wird das Material nur im Bereich der Gewindespitzen, die von der Außenwand 24 gebildet sind, abgetragen, jedoch nicht so weit, dass das Wandmaterial im Bereich der Gewindespitzen vollständig verschwindet. Die Schultern haben beispielsweise bei einem Stator 3 mit einen größten Außendurchmesser von 140 mm, eine radiale Tiefe von ca. 4 mm.

Anschließend werden auf jedem Ende des Mantels 21 die Stirnringe 28 aufgeschraubt, soweit bis sie an Schultern 35 anstoßen. Danach wird der betreffende Stirnring 28 mit dem Stirnende 25 oder 26 längs der Kehlnut 37 verschweißt. Eine weitere Verschweißung kann außen erfolgen.

The stator 3 described is produced as follows:

First, the jacket 21, which has the desired helical shape, is produced from an originally cylindrical tube by cold working. Then, starting from its two ends 25 and 26 on the outside, the jacket 21 is turned a little over to produce the crescent-shaped shoulders 35. When the jacket 21 is over-tightened, the material is only removed in the area of the thread tips formed by the outer wall 24, but not to the extent that the wall material completely disappears in the area of the thread tips. For example, in the case of a stator 3 with a largest outer diameter of 140 mm, the shoulders have a radial depth of approximately 4 mm.

Then the end rings 28 are screwed onto each end of the jacket 21 until they abut shoulders 35. Thereafter, the face ring 28 in question is welded to the face end 25 or 26 along the groove 37. Another weld can be done on the outside.

The face rings 28 are then with the jacket 21st both cohesively and positively connected. The Flat surface 29 extends at right angles to the longitudinal axis 27.

As soon as the stator 3 is prepared by then the lining 39 in the jacket 21 and on the flat surfaces 29 applied in one piece. The stator 3 is finished and can, as explained above, in the eccentric screw pump 1 can be used.

As already described, the seals 41 and 42 go in one piece and without any separation surface in the rest Area of lining 39 over. There is no such thing Gap, which at some point the interior 22 inside the lining 39 with the inside 23 of the jacket 21 combines. When conveying aggressive media, for example let the coat 21 corrode, there is none Danger of the medium being separated by any gaps the lining 39 and the seals 41, 42 to the jacket 21 could penetrate. The inside 23 of the jacket 21 is effectively sealed. There is also no risk that the funded medium the cohesive connection between the lining 39 and the inside 23 of the jacket 21 could damage and penetrate this interface.

Apart from that the seals 41 and 42 are hermetic the interior 22 in the interior of the lining 39 seal the jacket 21, they also protect the interface between the lining 39 and the inner wall 23 of the Jacket 21 against detachment or the penetration of promoted Medium, for example, from the print side.

The rotor 4, which rotates in the lining 39, creates constant flexing work and strives for the lining 39 to take along in its direction of rotation. Because of the sealing system and the preload with which the rotor 4 abuts the lining 39 and deforms it, pushes the rotor 4 constantly material during its rotation the lining 39 in front of her in the circumferential direction. This leads to the above-mentioned flexing work and the driving effect in the circumferential direction.

In a central region of the lining 39 is each Volume element of the walk zone in each case by adjacent Areas of the lining in the axial and circumferential directions recorded.

However, this condition applies to the prior art not for the ends of the lining. One lying on the edge Volume element has a free end edge that the flexing forces exclusively through the cohesive Composite of the volume element are included. There are here no adjacent volume element, which the forces with records, which is why there is an increased risk that the cohesive connection between the the lining 39 and the jacket 21 is dissolved. This would make the lining 39 loose and in this area the effect that was originally only at the end of the lining 39 has occurred, is increasingly shifting towards the axial center i.e. towards the other forehead the stator 3.

Prevent the integrally molded seals 41 and 42 this effect. They ensure that for a volume element the lining 39 similar at the ends Fortifications prevail, as in one of middle area remote from the forehead. The Walkzone at the front end is also fixed by the seal and is thus connected to the jacket 21 at both axial ends. The integrally molded seal 41 and 42 protects mechanically the fluid connection between the lining 39 and the jacket 21 against dissolving or tearing.

The inventive design of the stator 3 was detailed above using an eccentric screw pump as Application example explained. However, the expert knows that an eccentric screw pump is also operated as a motor can be when a medium is under high pressure through the stator 3 is pressed through. Also exist in this case the same problems as with the eccentric screw pump above have been explained.

As can be seen from the above explanation, the serve two shoulders 35 essentially as an assembly aid to Before welding, fix the face ring in the correct position 28 to ensure on the jacket 21.

Instead of providing the shoulders on the jacket 21 it is also conceivable to design the through opening 32 in steps, such that they are in a thickness direction of the Front ring 28 lying area a cross-sectional area having the cross-sectional area corresponding to the outer wall 24 is defined while another is on it adjacent area a smaller but similar shape Has cross-sectional area. So that the shoulder in the Front ring 28 relocated after assembly, in the way generated shoulder surface, abuts the end face 25 or 26.

As can be seen from the illustration, the front ring works 28 like a kind of bandage, the shape of the coat 21 additionally fixed in the area of its ends 25, 26 or stabilized.

With an eccentric screw pump or an eccentric screw motor the jacket 21 has both on its outer wall as well as a screw-shaped one on its inner wall Shape up. To the cross-sectional profile of the jacket 21 in Stabilize area of its ends and a simple To enable coupling with the other housing parts 5.6 a face ring 28 sits on each end of the jacket 21. The end ring 28 contains a through opening 32, the Cross-sectional area in terms of their shape essentially with the cross-sectional area that corresponds to the Inner wall 23 or the outer wall 24 is delimited.

Claims (22)

1. Eccentric screw pump or motor (1)
   with a stator (3), which has a tubular shell (21) made of a firm material with an inside (23) and an outside (24), wherein the shell (21) has a constant wall thickness, and the interior (22) of the shell (21) has a screw-like structure and the contour of the outside (24) of the shell (21) follows the contour of the inside (23) of the shell (21),
   with a lining (39), which is located in the shell (21) and has a constant thickness over a region of its length, and
   with an end ring (28), which is arranged on at least one end of the shell (21) and which contains a passage (32), which has a substantially similar structure to the interior (22) of the stator (3), characterised in that the passage (32) runs over the thickness of the end ring (28) in a screw formation with the same pitch and number of thread turns as the interior (22) of the stator.
2. Eccentric screw pump or motor according to Claim 1, characterised in that the end ring (28) is structured in such a way that it can be screwed at least a small distance onto the shell (21) in a similar manner to a threaded nut, wherein the shell (21) assumes the function of the screw.
3. Eccentric screw pump or motor according to Claim 1, characterised in that the cross-sectional area of the passage (32) is not smaller than the cross-sectional area of the interior (22) of the shell (21) at any point.
4. Eccentric screw pump or motor according to Claim 1, characterised in that the passage (32) essentially constitutes a continuation of the interior (22) of the shell (21), possibly with a different inside width.
5. Eccentric screw pump or motor according to Claim 1, characterised in that for at least a small distance, the passage (32) essentially constitutes a continuation of the screw, which is defined by the outer wall (24) of the shell (21).
6. Eccentric screw pump or motor according to Claim 1, characterised in that over a section of its length, the cross-sectional area of the passage (32) is smaller than the cross-sectional area of the outer contour of the shell (21).
7. Eccentric screw pump or motor according to Claim 1, characterised in that the end ring (28) contains a stepped opening, which is divided into two sections in longitudinal direction, of which the first section is adapted to the outer structure of the shell (21) and the second section essentially constitutes a continuation of the interior (22) of the shell (21).
8. Eccentric screw pump or motor according to Claim 1, characterised in that the shell (21) is provided with a shoulder (3 5) on the end, on which the end ring (28) sits.
9. Eccentric screw pump or motor according to Claim 8, characterised in that on at least one of its ends, the shell (21) is provided with a reduction in its outer dimensions, which extend at least over a portion of its outer periphery, and that the shoulder (35) is formed as a result of the reduced dimension.
10. Eccentric screw pump or motor according to Claim 9, characterised in that in the region of the reduction in diameter, the outer contour of the shell (21) follows a cylindrical surface.
11. Eccentric screw pump or motor according to Claim 1, characterised in that the end ring (28) contains a passage (32), which has the same cross-sectional area at all points.
12. Eccentric screw pump or motor according to Claim 1, characterised in that the end ring (28) is integrally connected to the material of the shell (21).
13. Eccentric screw pump or motor according to Claim 12, characterised in that the end ring (28) is welded to the shell (21).
14. Eccentric screw pump or motor according to Claim 13, characterised in that the weld (41) lies on the face (25, 26) of the shell (21).
15. Eccentric screw pump or motor according to Claim 1, characterised in that the shell (21) is made of steel, a steel alloy, light metal or a light metal alloy.
16. Eccentric screw pump or motor according to Claim 1, characterised in that the end ring (28) has a radially outwardly extending surface (29).
17. Eccentric screw pump or motor according to Claim 16, characterised in that the radially outwardly extending surface (29) is a plane surface.
18. Eccentric screw pump or motor according to Claim 1, characterised in that the end ring (28) is a casting.
19. Eccentric screw pump or motor according to Claim 1, characterised in that the end ring (28) is finished on its outside (31) by cutting over a section of its length.
20. Eccentric screw pump or motor according to Claim 1, characterised in that the end ring (28) has a circular outer contour.
21. Eccentric screw pump or motor according to Claim 1, characterised in that the lining (39) is formed by an elastomer.
22. Eccentric screw pump or motor according to Claim 21, characterised in that the lining (39) continues at least into the end ring (28).

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