DE102021006414A1 - Stator for an eccentric screw pump - Google Patents

Abstract

The invention relates to a stator (1) for an eccentric screw pump, with a stator body (8) made of elastic material, in which a helical passage opening (9) for a rotor is integrated, extending over the length of the stator body (8). This stator is characterized in that cavities (10, 11) are integrated into the stator body (8) and distributed unevenly around the circumference of the through-opening (9), each of which extends over the length of the stator body (8) or along the length of the stator body (8) are arranged.

Description

The invention relates to an eccentric screw pump with a stator body made of elastic material, in which a helical passage opening (for a rotor) extending over the length of the stator body is integrated. B. has a slot-shaped cross-section or a (rounded) triangular cross-section.

In addition, the invention relates to a stator-rotor combination with such a stator and with a helical rotor, which preferably has a circular cross section.

Finally, the invention also relates to an eccentric screw pump with such a stator-rotor combination, i. H. with a stator and with a rotor and with a drive with which the rotor can be driven in rotation in the passage opening of the stator body and preferably with a coupling device with which the drive is connected to the eccentrically rotating rotor or its eccentrically rotating rotor end.

Such an eccentric screw pump is a pump from the group of rotating positive displacement pumps that are used to convey a wide variety of media and in particular liquid media and also highly viscous liquids in a wide variety of industrial sectors. The liquids to be pumped can also contain solids. The rotor is helical, preferably with a relatively large pitch and pitch and a relatively small core diameter. It is arranged eccentrically in the stator or in the passage opening of the stator and the stator or its helical interior (with elongated hole geometry) has one more thread than the rotor (with circular cross-section). In this case, the rotor rests on the inner surface of the stator or on the inner surface of the through-opening via one or more uninterrupted sealing lines. The sealing lines separate conveying chambers that move (continuously) from the suction side to the pressure side or from the inlet side to the outlet side as the rotor rotates. The sealing line or the sealing lines consequently separate and seal the delivery chambers from one another, so that the suction side of the stator is sealed off from the pressure side.

The stator is made of an elastic material. Elastic material means, in particular, an elastomer, e.g. B. a (synthetic) rubber or a rubber mixture. Optionally, composite materials made of an elastic material (e.g. elastomer) and another material, e.g. B. metal includes, as well as fiber-reinforced materials, z. B. a fiber reinforced elastic material.

The stators used in practice in progressing cavity pumps have proven themselves extremely well, but they can be further developed. This is because these are components of an eccentric screw pump that are subject to wear during operation. On the one hand, there is a need to minimize the wear of stators. On the other hand, it must be ensured that the function of the pump is not or only minimally impaired with increasing wear. This applies in particular to maintaining the sealing line and/or optimal conveying properties.

From the WO 2018/162360 A1 a stator and an eccentric screw pump of the type described at the outset are known, with the stator in the pressureless state having an oversize geometry that deviates from the target geometry with one or more oversize areas that are designed as material reserves beyond the target geometry in the direction of the rotor are and each extend over a limited length range. These oversize areas are dimensioned in such a way that, in the operating state with a predetermined operating pressure, the actual geometry approaches the target geometry and the target geometry is preferably set. Such a stator is particularly preferably used in an eccentric screw pump with a stator casing which can be clamped against the stator with a clamping device in order in this way to change the clamping of the stator and, if necessary, also to adjust it.

In practice, elastic stators are made by conventional manufacturing methods, e.g. B. manufactured by extrusion. Alternatively, in the DE 20 2016 100 894 U1 described the possibility of designing a stator casing and its lining as a combined 3D printed part.

In the US 9,309,767 B2 a stator for an eccentric screw pump is also described, in which cavities are integrated into the elastic material. The stator is characterized by a complex structure made up of a stator housing and a stator insert, with the stator insert in turn being composed of an insert body and an insert coating. A large number of cavities are integrated into the insert body. The through-opening of the stator has a star or flower-shaped symmetrical geometry and the openings in the insert body are symmetrically distributed around the through-opening. The insert body can also be constructed in the manner of a skeletal structure with cavities and webs. It there is also the possibility of filling these cavities with a filling material, e.g. B. to fill with a gas or a liquid or to evacuate the cavities. In this way, it should be possible to adjust the stator in terms of rigidity.

Another embodiment of a stator with integrated cavities is known from FIG US 10,527,037 B2 .

A stator with a through hole having a triangular or rounded-triangular cross section is z. B. in the DE 19 842 754 A1 described. Such a geometry is also referred to by the applicant as a tricam geometry.

Proceeding from the previously known state of the art, the invention is based on the technical problem of creating a stator of the type described at the outset, which is characterized by reduced wear and/or increased functionality while at the same time being simple to manufacture. In addition, a rotor-stator combination and an eccentric screw pump with such a stator are to be made available.

To solve this problem, the invention teaches in a generic stator of the type described above that cavities distributed around the circumference of the through opening are integrated into the stator body, which each extend over the length of the stator body or are arranged along the length of the stator body. Preferably, these cavities are unevenly distributed around the circumference of the through-opening.

In a first embodiment, these cavities can be in the form of channels which extend over the entire length of the stator body and are distributed around the circumference of the through-opening. The cross section of these channels can, for. B. be designed as a circle, triangle, hexagon or rhombus. In an alternative, second embodiment, the cavities do not form (continuous) channels, but rather rows of cavities that extend along the length of the stator and each have a plurality of cavities arranged one behind the other in the longitudinal direction. These rows of cavities are in turn distributed around the circumference of the through-opening, also preferably unevenly. For the rows of cavities, the same cross-sectional shapes mentioned above come into consideration as for the channels. In both cases, the channels or the rows of cavities preferably run parallel to the through-opening and consequently also in a helical shape.

In a preferred embodiment, a stator is used with a through-opening that has the shape of an elongated hole in cross section, so that the invention preferably relates to such stators. A through-opening with a slot-shaped cross-section means, in particular, a cross-section of two arcuate arcuate areas, e.g. B. two semicircles, and of two connecting areas connecting the arch areas, z. B. two parallel straight lines is formed. In an alternative embodiment, a stator with a through opening having a triangular or rounded-triangular cross-section can be used. Such a geometry is also referred to as “Tricam geometry” by the applicant. This cross section is made up of three arcuate arched areas. Each pair of a connection area, z. B. a straight or substantially straight connecting area, so that the three arcuate areas and the three connecting areas arranged in between form a triangular basic structure with “rounded corners”. Finally, the invention also includes embodiments with through-openings of other geometries, e.g. B. with a star-shaped or rounded star-shaped cross-section.

According to the invention, the volume of the elastic stator is not completely filled with elastic material, but cavities are integrated. Thus, preferably only the surfaces (i.e. the inner surface or wall and the outer surface or wall) of the elastomeric stator are manufactured in a certain material thickness and between the inner and outer wall or between the outer wall and the inner through-opening is through the cavities creates a suitable filling geometry. In this way it is possible to increase the wall thickness of the inner wall or its elasticity in the areas particularly susceptible to wear, e.g. B. in the radii of the slot to increase in order to achieve a longer service life.

According to the invention, the elasticity or the rigidity of the stator can be modeled separately for each point, e.g. B. depending on the expected wear at the respective point. First of all, this applies to the circumference of the stator body. However, the wall thickness and/or the structure of the filling geometry can also be varied in the axial direction in order to achieve different or variable behavior of the stator on the suction side and the pressure side. This allows, for example, to compensate for the different pressure conditions at the two ends of the stator in order to to ensure the smoothest possible operation of the rotor-stator system.

The fact that a harder material can be used compared to a "solid" stator is particularly advantageous, since the flexibility of a certain material is increased by the cavities. By using a harder material, the resistance and thus the service life of the stator or the stator surface can be increased and wear can be reduced. Due to the cavities, however, the desired elasticity or flexibility is perfectly achieved despite the harder material.

It is of particular importance that according to the invention there is the possibility of these cavities unevenly around the circumference of z. B. slot-shaped through-opening around. This means that the cavities, e.g. B. the channels or rows of cavities, can be distributed around the circumference of the through-opening and/or can be dimensioned in such a way that they have no symmetry with respect to the symmetry axes or symmetry points of the geometry, e.g. B. elongated hole geometry of the through-opening or also have a symmetry of the geometry (z. B. slot geometry) of the through-opening deviating symmetry.

In a particularly preferred embodiment, it is proposed that the stator body is designed with non-uniform clamping over the circumference of the through-opening, i. H. with non-uniform oversize of the rotor provided for the stator in relation to the stator. According to the invention, it is now possible to adapt the (uneven) distribution of the cavities around the circumference of the through-opening to the uneven distribution of the clamping or to design the distribution of the through-openings as a function of the uneven distribution of the clamping.

It is possible for the cavities to be distributed around the circumference of the through-opening in such a way that the stator has the same or substantially the same elastic resilience over the entire circumference, e.g. B. despite varying wall thickness of the stator body over the circumference. A stator with a slot-shaped through-opening and a circular outer cross-section has an uneven (total) wall thickness over the circumference, which is less in the area of the ends of the slots than in the area of the straight connecting areas of the slots. Despite this uneven wall thickness, the same or substantially the same elastic resilience can be achieved over the entire circumference of the stator via the cavities that are essential to the invention. The same applies to other geometries, e.g. B. for the rounded triangular cross-section or alternatively a rounded star-shaped cross-section. Alternatively, however, the invention also offers the possibility of setting the resilience/flexibility differently and very variably over the circumference of the geometry, namely through the cavities. So you can z. B. increase the resilience in wear-prone areas, z. B. in the radii.

The integration of cavities in the stator body means that the stator body is divided by the cavities (at least in some areas or over a partial circumference or over the entire circumference) into an inner wall with an inner wall thickness and an outer wall with an outer wall thickness, the cavities preferably between the inner wall and the outer wall. The inner wall faces the through opening, ie it is located between the cavities and the central through opening. According to the invention, it is preferably provided that this inner wall thickness, which is formed between the cavities and the inner through-opening, is uneven over the circumference. It is e.g. It is possible, for example, for an inner wall thickness that is uneven over the partial circumference of the respective arc area to be realized in an arch area or in several arch areas of the oblong hole geometry (or a triangular geometry). Alternatively or additionally, there is the possibility that in one or more straight connection areas of the (elongated hole) geometry, an inner wall thickness that is non-uniform over the length of the respective connection area is realized. With such a geometry, but also with other geometries of the through opening and/or the rotor, there is the possibility of adjusting the inner wall thickness by the distribution and/or dimensioning of the cavities, preferably depending on the areas with high or low clamping. For example, there is the possibility of realizing high clamping in areas with high wear and designing the cavities there in such a way that a high inner wall thickness is provided. Less clamping is achieved in areas with little wear and a smaller inner wall thickness can also be realized in these areas. This variation is z. B. over the partial circumference of the slot geometry or a rounded triangular geometry or alternatively a (rounded star-shaped geometry). With regard to the elongated hole geometry, reference is also made to the description of the figures and the drawings. For example, there is the possibility that the cavities are unevenly distributed around the partial circumference of one arch area or both arch areas, e.g. B. with uneven size and / o the uneven spacing or only over a partial circumference of the sheet area, z. B. over less than 3/4 of the partial circumference of the arch area.

The inner wall thickness is preferably greater in areas with higher clamping than in areas with lower clamping. Alternatively or additionally, there is the possibility of arranging cavities (e.g. channels) with a larger volume and/or greater cavity density in areas with higher clamping to increase the flexibility than in areas with lower clamping.

Overall, there are many adjustment options that can be used to optimize the functionality and minimize wear on the stator.

The stator body is particularly preferably made entirely of an elastic material over the entire cross section and the entire length, preferably homogeneously of a uniform, elastic material. The stator body is therefore not provided with additional parts made of a different material and in particular not with additional metal parts or metal tubes or is firmly connected, but it is a stator body made entirely of elastic material, which, however - as described above - with integrated reinforcing fibers or the like can be reinforced in terms of a composite material. It is also within the scope of the invention for a separate stator casing to be provided in addition to the stator body, which is not part of the stator body but instead surrounds the stator body as a separate component that can be detached and non-destructively disassembled in the assembled state.

The elastic stator body can be a stator body manufactured in one piece. Alternatively, the elastic stator as a longitudinally divided stator from several stator segments, z. B. two half-shells exist.

An embodiment is preferably implemented in which the stator casing can be clamped against the stator body, preferably in the radial direction, namely z. B. by a longitudinally divided shell of several distributed over the circumference and braced in the radial direction shell segments, which are also referred to as clamping elements. Such stators with a stator body that can be stretched are known and the known findings can be used, which, however, are realized according to the invention with a stator body with the cavities described. The advantages according to the invention can consequently be achieved particularly preferably with tensionable stators, i. H. and consequently in combination with the adjustment. In the case of wear-related readjustment, deformations in the geometry can be compensated for and thus optimal conveying properties can also be guaranteed with readjustment.

There is also the possibility of using electrical and electronic components in the cavities of the stator body, e.g. B. Sensors.

In particular, it is advantageous to integrate a plurality of sensors in the cavities of the stator, preferably distributed over the circumference and/or over the length of the stator. This allows precise monitoring of the status of the progressing cavity pump, e.g. the operating or wear status or a fault status. With a higher number of sensors, the measurement accuracy can be improved just as much as (through redundancy) the fail-safety of the system.

For example, sensors can be inserted into the cavities, with which the operating pressure of the eccentric screw pump is measured. These sensors can be connected to a monitoring device with which the status of the progressing cavity pump can be determined and/or monitored.

It is also optionally provided to fill the cavities with a different material, e.g. B. with a fluid (e.g. a liquid and/or a gas). This makes it possible to change the properties of the stator, e.g. B. to vary its flexibility over the filling and / or the pressure of the medium, and optionally also distributed variably over the circumference. The filling geometry can consequently be varied via such a fluid for adjustment, so that an adaptation of the properties in the sense of an adjustment is also possible as a function of wear. Depending on the viscosity of the medium z. B. affect the reaction speed of the stator to deformation and / or dampen. Alternatively or additionally, there is the possibility of cooling and/or tempering the stator using such a fluid.

During production, the stator body can be fitted with suitable connections for a fluid, e.g. B. be provided with pneumatic or hydraulic connections for a variation of the filling geometry for adjustment. Because the application of pressure, z. B. with a gas or a liquid-gas mixture is conceivable, so that the hardness of the stator can be varied by adjusting the pressure. Optionally, pressure sensors can be integrated into the cavities to To analyze the movement of the stator and to influence it.

The stator body can be produced very economically by extrusion, because modern extrusion devices or extrusion methods also enable the production of the helical geometry and thus the cavities, which preferably also run helically over the length, can be integrated into the elastic stator body in the course of extrusion. Alternatively, additive manufacturing processes such. B. 3D printing can be used. Alternatively, other manufacturing processes are possible, e.g. B. injection molding or compression molding.

As already mentioned, due to the cavities, the stator body can be used with greater hardness than previously customary stators without cavities. The stator body is preferably made of a material with a Shore A hardness of at least 70, preferably at least 75, particularly preferably at least 85. A preferred hardness range is z. B. 70 to 100 Shore A, z. B. 90 to 100 Shore A.

As an elastic material for the stator z. B. a synthetic rubber or a rubber mixture is used. Alternatively, silicones can be used. In principle, it can be fiber-reinforced, elastic materials. Especially in the case of production by 3D printing, the material can be varied over the cross section and/or over the length, i. H. different plastics or polymers can be used. As an alternative or additional material from which the stator body can be partially or completely made, z. B. a high performance polymer such. B. PTFE, POM or the like can be used. In connection with PTFE, it should be noted that this material is not very elastic, so that stators made of this material cannot usually be used with a clamp and consequently cannot be oversized. PTFE stators have not been produced with such a clamp to date. However, the use of cavities makes it possible to achieve the required flexibility, not through the material properties but through the geometry, so that flexible, pressure-resistant stators made of a non-elastic or less elastic material, e.g. B. made of PTFE. This means that although the stator body itself is designed to be elastic, it can optionally also be made from a non-elastic or less elastic material, e.g. B. made of PTFE or the like, since the elasticity is generated by the geometry.

For a stator body that is manufactured using the 3D printing process, e.g. B. polyethylene terephthalate glycol (PETG), polyether ether ketone (PEEK), polyether ketone ketone (PEKK) and nylon into consideration.

In addition, reinforcing materials can also be added to the elastic base material of the stator body. The reinforcement materials are preferably chopped or continuous fibers made of carbon, aramid or another material which imparts favorable strength, stiffness and/or tribological properties to the stator body.

Optionally, the cavities can be provided with a coating (internal coating). It can be z. B. be a non-stick coating, z. B. with a high-performance polymer (e.g. PEEK). Alternatively, a coating with special hydrophobic properties, e.g. B. to generate superhydrophobic surfaces. These are inert, so they do not get dirty as quickly and thus make it easier to clean the cavities, which is particularly advantageous when the pumps are used in applications with high hygienic requirements. Furthermore, the inner coating can be a coating to enable better heat transfer, e.g. B. a phenolic epoxy coating.

The cavities, e.g. B. channels can, moreover, evenly over the entire length of the stator body, d. H. with a uniform diameter and uniform distribution. However, there is also the possibility of varying the cavities over the length of the stator. This can be easily and economically realized in particular by additive manufacturing processes. There is thus another possibility of adapting the stator to specific conditions and optimizing it in terms of performance and/or service life.

The invention-essential cavities also create the possibility in the stator itself mechanical elements such. B. to integrate rods or the like, z. B. rods that extend between the suction side and pressure side and are fixed accordingly on the sides. Such rods that are passed through the stator body can replace conventional tie rods and at the same time give the stator additional stability. Such internal tie rods can be moved radially or braced axially. This allows a stator adjustment to be implemented.

Overall, the invention enables the optimization of conventional stators such. B. Facing energy efficiency and/or pressure stability. With suitably selected structures, it is also possible to cope with large temperature differences in the conveying process, which can lead to problems with classic stators due to the thermal expansion of the stators.

The invention also relates to a stator-rotor combination, i. H. the stator according to the invention is also protected in combination with a helical rotor, preferably of circular cross-section.

Finally, the invention also relates to an eccentric screw pump with such a stator-rotor combination, i. H. the stator, which is essential to the invention, is also protected as a component of an eccentric screw pump or in combination with an eccentric screw pump, this eccentric screw pump having the stator, the rotor and a drive with which the rotor is rotated in the passage opening of the stator body. A coupling device is also preferably provided between the drive and the eccentrically rotating end of the rotor. Overall, the stator according to the invention can be used in eccentric screw pumps with a fundamentally known structure and fundamentally known components.

• 1 einen vereinfachten Längsschnitt durch eine Exzenterschneckenpumpe,
• 2 einen (vereinfachten) Querschnitt durch eine Stator-Rotor-Kombination nach dem Stand der Technik,
• 3 den Stator aus 2 mit markierten Verschleißbereichen,
• 4 einen Querschnitt durch eine erfindungsgemäße Stator-Rotor-Kombination einer Exzenterschneckenpumpe (z. B. nach 1),
• 5 einen Stator in einer abgewandelten, erfindungsgemäßen Ausführungsform und
• 6 eine weitere Ausführungsform der Erfindung.

The invention is explained in more detail below with reference to drawings which merely represent exemplary embodiments. Show it

• 1 a simplified longitudinal section through an eccentric screw pump,
• 2 a (simplified) cross section through a stator-rotor combination according to the prior art,
• 3 the stator 2 with marked wear areas,
• 4 a cross section through an inventive stator-rotor combination of an eccentric screw pump (z. B. after 1 ),
• 5 a stator in a modified embodiment according to the invention and
• 6 another embodiment of the invention.

In the figures or in 1 an eccentric screw pump is shown which has a stator 1 and a helical rotor 2 rotating in the stator 1 . Furthermore, the pump has a pump housing 4, which (depending on the direction of operation) is referred to as the suction housing. In addition, the pump has a connecting piece 5, which is also referred to as a discharge nozzle. A drive for the eccentric screw pump is not shown, the drive acting on the rotor 2 via a coupling rod 6 that is merely indicated. The coupling rod 6 is connected via coupling joints to the rotor 2 on the one hand and to a drive shaft (not shown) on the other hand, only the joint 7 on the rotor side being shown of the coupling joints.

The stator 1 has a stator body 8 made of elastic material. A helical passage opening 9 is integrated into the stator body and extends over the entire length of the stator body. The rotor 2 driven by the drive rotates in this passage opening 9. The eccentric movement of the rotor 2 or the end of the rotor is made possible via the coupling rod and the joints.

In this exemplary embodiment, the through-opening 9 has a slot-shaped cross section. In the illustrated embodiment, this slot-shaped cross section consists of two arcuate arcuate areas 12, which are designed as semicircles, and two connecting areas 13, which connect the arcuate areas 12 and are designed as parallel straight lines in the exemplary embodiment. The rotor 2 has a circular cross section. During operation, the rotor 2 rests against the inner surface of the stator body 8 or the through-opening via one or more uninterrupted sealing lines, with these sealing lines separating conveying chambers from one another, which in the course of the rotation of the rotor move from the suction side S to the pressure side D (continuously ) move. The stator body 8 has a varying wall thickness W over the circumference.

Incidentally, in 1 recognizable that the stator body 8 is surrounded by a stator casing 3 . This stator casing is designed as a separate component (eg made of metal), ie it is not firmly connected to the stator body 8, but rather it surrounds the stator body 8 in a detachable manner and can therefore be removed from it without being destroyed. About the stator shell 3, the z. B. can be formed in several parts from several shell segments, z. B. the elastic stator body 8 can be clamped in the radial direction, so that the stator shell 3 also functions as a stator clamping device.

According to the invention, the configuration of the elastic stator body 8 is of particular importance. This stator body 8 is in various embodiments in the 4 , 5 and 6 shown. The 2 and 3 show, in contrast, a known from the prior art stator body 8. It can be seen that in the elastic stator body 8 - in contrast to the prior art - a plurality of cavities 10, 11 integ are ured, which extend in the exemplary embodiment as channels over the entire length of the stator body. Several channels 10, 11 are distributed around the circumference of the through-opening 9, specifically unevenly, ie the cavities 10, 11 are not evenly distributed over the entire circumference, but rather an uneven, asymmetrical distribution is realized, specifically with regard to the arrangement , the distances and/or the sizes of the cavities 10, 11. All of the cavities--like the through-opening 9--extend helically, with the cavities also being arranged helically as channels parallel to the helical through-opening 9.

In the 4 , 5 and 6 it can be seen in each case that the elongated hole geometry has a certain (basic) symmetry, ie the elongated hole is axisymmetric in its basic shape with respect to two axes that are not shown in detail. It is now of particular importance that in all exemplary embodiments 4 , 5 , 6 the cavities or the channels are distributed around the circumference of the through-opening 9 and/or dimensioned in such a way that they have no symmetry in relation to the symmetry axes of the elongated hole geometry. If the channels or passage openings are arranged in a certain symmetry around the circumference, then this symmetry deviates from the symmetry of the elongated hole geometry.

In the first embodiment according to 4 the cavities 10 are only arranged over a limited partial circumference of the two arched areas 12 of the oblong hole geometry, i.e. the cavities 10 do not extend over the entire arched area but are only arranged in approximately half of the respective arched area 12, while in the other half in the exemplary embodiment no cavities are provided. In this exemplary embodiment, no cavities are provided in the straight connecting regions 13 either, so that overall an uneven distribution is realized in relation to the circumference of the through-opening.

In contrast, the 5 and 6 each a modified embodiment, in which cavities 10, 11 are distributed over the entire circumference of the through opening 9, but in a highly uneven distribution, both with regard to the dimensioning and geometry of the cavities 10, 11 and with regard to the spacing of the cavities 10, 11 to the passage opening 9. This will be discussed in more detail below.

In all cases, the volume of the elastic stator body 8 is not completely filled with elastic material, but instead the cavities 10, 11 are integrated, which influence the rigidity or flexibility of the stator body. The asymmetrical distribution of the cavities around the circumference makes it possible to adjust the flexibility of certain stator areas in a targeted manner in order to achieve certain properties.

The cavities according to the invention are also of particular importance in the illustrated exemplary embodiments because a stator body 8 is preferably realized which is designed with non-uniform clamping over the circumference of the through-opening 9 . In the case of a rotor-stator combination, the oversize of the rotor provided for the stator in relation to the stator is referred to as clamping. This is initially based on the 2 and 3 are explained, which illustrate the state of the art. It can thus be seen that the rotor 2 has a larger outside diameter than the elongated hole geometry of the passage opening 9, ie the rotor 2 is oversized in relation to the stator body 8 and is consequently manufactured with a clamp. This applies to the state of the art 2 uniformly for the entire passage opening, ie the clamping K is in the prior art 2 the same size at all points of the passage opening. It is a standard stator with a non-uniform wall thickness W over the circumference, which is due to the fact that the stator body 8 has a circular outer circumference and a through opening 9 in the form of a slot. 3 shows a typical wear pattern of the stator body 8 2 . The different wall thickness W causes a different resilience of the elastic material and this leads to an uneven wear, which in 2 is indicated by the special wear areas V.

this inside 3 illustrated wear is counteracted by the measures according to the invention. For this, on 4 referred. So is in 4 First of all, it can be seen that the stator body 8 is designed with an uneven clamping around the circumference of the through-opening 9, because areas with higher clamping K1 and areas with lower clamping K2 are provided. This is by virtue of the 4 realized adapted slot geometry compared to the exact slot geometry shown in dot-dash lines recognizable, which also in the prior art 2 is realized.

A comparative view of 3 and 4 also shows that in the areas with higher wear a higher clamping K1 is realized than in areas with less wear. It is precisely in these areas with higher wear and high clamping that the inventions are now manure essential cavities 10 arranged. 4 consequently shows a non-solid stator according to the invention with cavities 10 and with an optimized elongated hole geometry, in which a different clamping is realized. The cavities 10 achieve that, despite the different wall thicknesses W, essentially the same resilience is achieved, specifically with the possibility of using a harder material overall for the stator body 8 . The principle of the invention is 4 shown simplified in an example in which cavities 10 are only arranged in a limited peripheral area, namely in areas with high clamping and/or high wear.

In contrast, the 5 a modified embodiment in which cavities 10 are integrated in the arched areas 12 and cavities 11 with a different geometry are integrated in the straight connecting areas 13 . It is important in the embodiment according to 5 that the cavities 10 in the arched areas 12 are distributed asymmetrically over the arched area, so that there is a varying distance between the cavities 10 and the through-opening 9 over the arched area.

In addition, it can be seen in the figures that the integration of the cavities 11, 12 in the stator body results in the stator body being formed through the cavities, at least in certain areas, into an inner wall with a possibly varying inner wall thickness W2, W3, W4 and an outer wall is subdivided with a wall thickness W1. The cavities 10, 11 are thus arranged between the inner wall and the outer wall. The inner wall is the wall facing through-opening 9, ie the wall thickness of the entire stator body, which is arranged between the cavities on the one hand and the through-opening on the other. In 5 it can be seen that the cavities are not only arranged over a partial area of the through opening, but that the cavities are also arranged in such a way that the inner wall thickness W is uneven over the circumference of the arched area 12, i.e. there are areas with a greater inner wall thickness W2 and areas with a smaller inner wall thickness W3. A further wall thickness W4 is realized in the straight connecting area 13 , which can vary over the length of the area 13 .

The same applies to the embodiment according to FIG 6 . On the one hand, cavities 10, 11 with different geometries are realized there. It can also be seen that the arrangement of these cavities results in areas with different inner wall thicknesses W2, W3 and W4.

The drawings only show a preferred embodiment with a slot-shaped cross section of the passage opening. Alternatively, however, the invention can also be implemented with a different geometry, in particular with a geometry of the through opening with a rounded triangular cross section (e.g. tricam geometry). With this geometry, too, an uneven wall thickness of the stator body is preferably implemented and the cross section has arcuate areas and (straight) connecting areas. The considerations described in connection with the elongated hole geometry can also be implemented with such a geometry. Finally, as an alternative, use in conjunction with a (rounded) star-shaped geometry can also be considered.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• WO 2018162360 A1 [0007]
• DE 202016100894 U1 [0008]
• US 9309767 B2 [0009]
• US 10527037 B2 [0010]
• DE 19842754 A1 [0011]

Claims (30)

Stator (1) for an eccentric screw pump, with a stator body (8) made of elastic material, in which a helical passage opening (9) for a rotor extending over the length of the stator body (8) is integrated, characterized in that in the Stator body (8) cavities (10, 11) distributed unevenly around the circumference of the through-opening (9) are integrated, each of which extends over the length of the stator body (8) or is arranged along the length of the stator body (8). stator after claim 1 , characterized in that the cavities (10, 11) are designed as channels extending over the entire length of the stator body (8) and distributed (unevenly) around the circumference of the through-opening (9). stator after claim 1 , characterized in that the cavities (10, 11) are arranged in cavity rows extending along the length of the stator, each having a plurality of cavities arranged longitudinally one behind the other, these cavity rows being (unevenly) distributed around the circumference of the through opening. stator after claim 2 or 3 , characterized in that the channels or the rows of cavities run helically parallel to the through opening (9). Stator after one of Claims 1 until 4 , characterized in that the passage opening (9) has a slot-shaped cross-section or a rounded triangular cross-section. stator after claim 5 , characterized in that the through-opening (9) has a slot-shaped cross-section of two arcuate arched areas (12), z. B. two semicircles, and of two connecting areas (13) connecting the arched areas, e.g. B. two parallel straight lines is formed. Stator after one of Claims 1 until 6 , characterized in that the cavities (10, 11), z. B. the channels or rows of cavities, are distributed around the circumference of the through-opening (9) and/or are dimensioned in such a way that they have no symmetry in relation to the symmetry axes or symmetry points of the geometry of the through-opening or a symmetry that deviates from the symmetry of the geometry of the through-opening . Stator after one of Claims 1 until 7 , characterized in that the stator body (2) has a non-constant wall thickness (W) over the circumference, where z. B. in the arcuate areas (12) of the elongated hole, a smaller wall thickness is provided than in the (straight) connecting areas (13) with a greater wall thickness. Stator after one of Claims 1 until 8th , characterized in that the stator body (8) is formed over the circumference of the through-opening (9) with a non-uniform clamping (K1, K2), ie with non-uniform oversize of the stator (1) provided rotor (2) opposite the stator. Stator after one of Claims 1 until 9 , characterized in that the cavities (10, 11) are distributed around the circumference of the through-opening (9) in such a way that the stator body (8) has the same or substantially the same elastic resilience over the entire circumference, e.g. B. despite varying wall thickness (W) of the stator body (8) over the circumference, or that over the circumference a specific different resilience is adjusted to z. B. to increase the resilience in wear-prone areas. Stator after one of Claims 1 until 10 , characterized in that the stator body (8) has an inner wall with an inner wall thickness (W2, W3, W4) that is uneven around the circumference. Stator after one of Claims 1 until 11 , characterized in that an inner wall thickness (W2, W3) that is non-uniform over the partial circumference of the respective arc area is provided in one or in both arch areas (12) of the oblong hole geometry or in one or more arch areas of a rounded triangular geometry. Stator after one of Claims 1 until 12 , characterized in that an inner wall thickness (W4) that is uneven over the length of the respective connection area is provided in one or in both straight connection areas (13) of the elongated hole geometry or in one or more connection areas of a rounded triangular geometry. Stator after one of Claims 1 until 13 , characterized in that the cavities (10, 11) around the partial circumference of an arch area or both arch areas are distributed unevenly, z. B. with non-uniform size and / or non-uniform spacing or only over a partial circumference of the sheet area, z. B. over less than 3/4 of the partial circumference. Stator after one of Claims 1 until 14 , characterized in that the inner wall thickness (W2, W3, W4) is greater in areas with higher clamping (K1) than in areas with lower clamping (K2). Stator after one of Claims 1 until 15 , characterized in that cavities (e.g. channels) with a larger volume and/or greater cavity density are arranged in areas with higher clamping (K1) to increase the resilience than in areas with lower clamping (K2). Stator after one of Claims 1 until 16 , characterized in that the stator body (8) consists entirely of an elastic material over the entire cross section and the entire length, preferably homogeneously of a uniform elastic material. Stator after one of Claims 1 until 17 , with a stator casing (3) which is separate from the stator body and which, in the assembled state, surrounds the stator body (8) so that it can be removed in a detachable and non-destructive manner. Stator after one of Claims 1 until 18 , characterized in that the elastic stator body (8) as a longitudinally divided stator body from a plurality of stator segments, z. B. half-shells. stator after Claim 18 or 19 , characterized in that the stator casing (3) can be clamped against the stator body (8), preferably can be clamped in the radial direction, and z. B. as a longitudinally divided shell of several distributed over the circumference and braced in the radial direction shell segments. Stator after one of Claims 1 until 20 , characterized in that in the cavities (10, 11) of the stator body (8) electrical or electronic components are used or used, for. B. Sensors. Stator after one of Claims 1 until 21 , characterized in that the stator body (8) by extrusion or by an additive manufacturing process, for. B. is made by 3D printing. Stator after one of Claims 1 until 22 , characterized in that the stator body (8) consists of an elastic, z. B. elastomeric material with a hardness of at least Shore A, z. B. at least 80 Shore A, preferably at least 90 Shore A is formed. Stator after one of Claims 1 until 23 , characterized in that the stator body (8) is made of a high-performance polymer or an engineering polymer, in particular polytetrafluoroethylene (PTFE), polyetheretherketone (PEEK) or polyoxymethylene (POM). Stator after one of Claims 1 until 24 , characterized in that the cavities are filled with a fluid, e.g. B. are filled or can be filled with a liquid, the resilience of the stator body being preferably influenced by the type and/or degree of filling and/or pressure of the medium. Stator after one of Claims 1 until 25 , characterized in that the cavities are provided with a coating, z. B. with a non-stick coating. Stator after one of Claims 1 until 26 , characterized in that the cavities are unevenly distributed over the length of the stator and/or have a different distribution and/or different dimensions over the length of the stator. Stator after one of Claims 1 until 27 , characterized in that through the cavities, z. B. through the channels, mechanical elements, z. B. rods, tie rods or the like are passed, the z. B. extend over the entire length of the stator, z. B. from a suction side to a pressure side. Stator-rotor combination with a stator (1) according to one of Claims 1 until 28 and with a helical rotor (2), which preferably has a circular cross-section. Eccentric screw pump with at least one stator-rotor combination claim 29 and with a drive with which the rotor (2) can be driven in rotation in the passage opening (9) of the stator body (8) and preferably with a coupling device (6, 7) with which the drive is connected to the eccentrically rotating rotor.

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