Stator for an eccentric screw pump

Abstract

The invention relates to a stator (1) for an eccentric screw pump, having at least one sleeve-like stator housing (2) and at least one elastically deformable stator cladding (6) enclosed circumferentially radially on the outside by the stator housing (2) with respect to a longitudinal centre axis (L) of the stator (1), an outer lateral face (19) of said stator cladding being in contact with an inner lateral face (17) of the stator housing (2). In order to produce a stator (1) by means of which a backflow of a conveying medium to the suction side of the eccentric screw pump can be largely minimised more permanently, the outer lateral face (19) of the stator cladding (6) and the inner lateral face (17) of the stator housing (2) conically taper at least over the majority of their respective axial lengths from a pressure side of the stator (1) to a suction side of the stator (1), wherein the stator cladding (6) is arranged in the stator housing (2) to be axially displaceable by a length, specifying a section (S), in the direction of the suction side of the stator (1) under radial elastic deformation.

Description

[0001] Stator for an eccentric screw pump

[0002] Technical area

[0003] The invention relates to a stator for an eccentric screw pump, comprising at least one sleeve-shaped stator housing and at least one elastically deformable stator lining which is enclosed radially outwardly circumferentially by the stator housing with respect to a longitudinal center axis of the stator and which is in contact with an inner circumferential surface of the stator housing.

[0004] State of the art

[0005] Progressing cavity pumps are traditionally used primarily for pumping thick, highly viscous, and abrasive media. For this purpose, a progressing cavity pump comprises a stator and a rotor rotatably mounted within the stator, which is usually driven at its suction end to operate the progressing cavity pump.

[0006] DE 20 2021 106 537 U1 discloses an eccentric screw pump with a rotor forming a conveyor screw and a stator forming a screw flight, in which the rotor rotates during the conveying operation of the eccentric screw pump. The stator has a stator housing in which a stator lining is located, which forms the screw flight.

[0007] In order to keep the backflow of a pumped medium from the pressure side of a stator to the suction side of the stator as low as possible, the stator lining can be manufactured with a certain undersize in relation to the rotor, so that the rotor elastically deforms the stator lining in a contact area with the stator lining. However, operational movements of the rotor relative to the stator lining inevitably lead to abrasion or wear on the stator lining or its inner surface forming the screw flight. This reduces the contact force between the rotor and the stator lining, whereby a helical contact line between the rotor and the stator lining can be interrupted, which is accompanied by increased backflow of the pumped medium and thus a reduced effectiveness of the eccentric screw pump.To counteract this, the stator lining or the entire stator must be replaced at regular intervals with a new stator lining or a new stator, which results in downtime of the progressing cavity pump and incurs maintenance costs.

[0008] Disclosure of the invention

[0009] An object of the invention is to provide a stator for an eccentric screw pump with which a backflow of a pumped medium to the suction side of the eccentric screw pump can be permanently minimized as far as possible.

[0010] This problem is solved by the independent patent claim. Advantageous embodiments are presented in the dependent patent claims, the following description, and the figures, wherein these embodiments, each taken individually or in combination of at least two of these embodiments, may represent an advantageous and / or further developing aspect of the invention.

[0011] A stator according to the invention for an eccentric screw pump has at least one sleeve-shaped stator housing and at least one elastically deformable stator lining which is enclosed radially on the outside circumferentially by the stator housing with respect to a longitudinal center axis of the stator and which is in contact with an inner circumferential surface of the stator housing, wherein the outer circumferential surface of the stator lining and the inner circumferential surface of the stator housing taper conically at least over the largest part of their respective axial length from a pressure side of the stator to a suction side of the stator and the stator lining is arranged in the stator housing so as to be axially displaceable by a distance of a predetermined length in the direction of the suction side of the stator under radial elastic deformation.

[0012] The terms “axial” and “radial” throughout this application refer to the longitudinal center axis of the stator.

[0013] During pumping operation of an eccentric screw pump equipped with a stator according to the invention, a pressurized pumping medium leaves the eccentric screw pump, which is inevitably applied to an axial pressure end of the stator lining. Due to the inventive axial displaceability of the stator lining in the stator housing, with radial elastic deformation of the stator lining radially inward by a predetermined length toward the suction side of the stator, the stator lining is, in a sense, axially prestressed toward the suction side of the stator by the pressure acting on its pressure end.Since the outer surface of the stator lining and the inner surface of the stator housing in contact therewith taper conically at least over most of their respective axial length from the pressure side of the stator to the suction side of the stator, for example with the same conicity, this axial prestressing of the stator lining generates a radial prestressing force acting radially inwards on the stator lining, which can cause an elastic deformation of the stator lining radially inwards in order to be able to urge the stator lining against a rotor arranged in a rotor receiving space of the stator lining.

[0014] If wear or material removal occurs on the inner surface of the stator lining that defines the rotor receiving space, a counterforce generated by the contact between the stator lining and the rotor, which acts radially outward against the radial preload force acting on the stator lining, is reduced. This allows the stator lining to be elastically deformed further radially inward while the axial preload of the stator lining remains constant. The pressure acting on the axial pressure end of the stator lining further axially displaces or displaces the stator lining in the stator housing toward the suction side of the stator due to the reduced radial counterforce and the associated reduced static friction between the stator housing and the stator lining.

[0015] This allows the radial contact force between the stator lining and the rotor to be automatically adjusted during operation of a suitably equipped eccentric screw pump, without the need for any mechanical, electromechanical, pneumatic, or hydraulic adjustment devices or the like. This automatic contact force adjustment reliably and in a structurally simple manner prevents a helical contact line between the rotor and the stator lining from being interrupted by wear or material removal on the inner surface of the stator lining. This would inevitably result in a significantly increased backflow of the pumped medium to the suction side of the stator, which must be avoided at all costs to maintain the efficiency of a suitably equipped eccentric screw pump.Due to the present invention, the stator lining instead has a contact with the rotor of almost constant quality over a longer operating period, so that a stator or a correspondingly equipped eccentric screw pump with permanently consistent tightness can be provided.

[0016] The sleeve-shaped stator housing has an annular cross-sectional area, which can be circular or polygonal. The stator housing can be made partially or entirely of a metal or a metal alloy. At least one mechanical interface, for example a connecting flange, can be provided on a suction side of the stator housing for connecting the stator to a conveying medium supply unit of an eccentric screw pump, via which the conveying medium can be supplied to the stator.

[0017] The stator lining can be manufactured, for example, by injection molding, additive manufacturing, or mechanical material removal. The production of the stator lining can alternatively or additionally include a sintering process. The stator lining can be formed partially or entirely from a material selected from a group comprising at least one metal, at least one metal alloy, and at least one plastic or plastic composite material, for example, a plastic fiber composite material.

[0018] The stator according to the invention can be used in particular for producing an eccentric screw pump for conveying thick, highly viscous and abrasive conveying media.

[0019] According to an advantageous embodiment, the stator housing has a hollow cylindrical pressure-side end section on the pressure side, a hollow cylindrical suction-side end section on the suction side and a central section arranged between the two end sections, wherein an inner diameter of the pressure-side end section is greater than an inner diameter of the suction-side end section, wherein an inner circumferential surface of the central section tapers conically from the pressure-side end section to the suction-side end section, wherein an axial length of the suction-side end section corresponds at least to an axial length of the pressure-side end section, wherein an inner circumferential surface of the pressure-side end section is formed circumferentially on the inner circumferential surface of the stator housing,radially inwardly facing shoulder merges into an inner circumferential surface of the central section and an inner circumferential surface of the suction-side end section merges seamlessly into the inner circumferential surface of the central section, and wherein the stator lining has, on the pressure side, a pressure-side piston end section guided axially displaceably in the pressure-side end section, on the suction side, a suction-side piston end section guided axially displaceably in the suction-side end section, and an intermediate section arranged between the piston end sections, the outer circumferential surface of which tapers conically from the pressure-side piston end section to the suction-side piston end section,The axial displaceability of the stator lining can be determined by an axial length of the pressure-side end section of the stator housing and a thickness of the pressure-side piston end section of the stator lining, which is given in the axial direction. The pressure-side piston end section of the stator lining is displaceably mounted in the pressure-side end section of the stator housing in the manner of a piston. The suction-side piston end section of the stator lining is displaceably mounted in the manner of a piston in the suction-side end section of the stator housing. The pressure-side end section and / or the suction-side end section of the stator housing can be circularly hollow-cylindrical. The axial displaceability of the stator lining is limited on one side by the radially inward-facing shoulder formed circumferentially on the inner surface of the stator housing.by the pressure-side piston end section of the stator lining axially abutting or resting against the shoulder. The maximum axial adjustment length, or the distance by which the stator lining can be axially displaced, can be selected and determined via the axial length of the pressure-side end section of the stator housing, so that the stator can be individually adapted to the respective application. The suction-side end section of the stator housing can, for example, transition seamlessly into the central section via a circumferential curve.

[0020] According to a further advantageous embodiment, at least one recess is formed on the outer surface of the stator lining, radially outwardly spaced from a rotor receiving space formed axially continuously on the stator lining from the pressure side of the stator to the suction side of the stator, and radially open on the outside. This makes the stator lining less massive and thus elastically deformable radially inward with less effort. The shape of the recess and / or the number of recesses, and thus the elastic deformability of the stator lining, can be individually adapted to the respective application.The recess is open on the outer surface of the stator lining, i.e. at least partially formed as a depression on the outer surface of the stator lining, and extends radially inwards to a distance from the rotor receiving space. When the stator lining is inserted into the stator housing, the recess is completely closed radially on the outside by a stator housing section. The recess can be formed completely circumferentially on the stator lining so that the stator lining has as consistent an elastic deformability as possible over its circumference. Two or more corresponding recesses can also be formed circumferentially offset from one another on the stator lining, each of which can extend over only part of the circumference of the stator lining, wherein these recesses can or cannot be arranged axially offset from one another.The rotor receiving space, which runs axially continuously through the stator lining, serves to receive a rotor of an eccentric screw pump and for this purpose has at least one screw flight or at least one screw contour, which can be adapted to the respective intended use of a correspondingly equipped eccentric screw pump and can otherwise be of conventional design, for example.

[0021] According to a further advantageous embodiment, the recess is formed at least partially in a helical configuration around the stator lining. As a result, the recess is formed circumferentially around the stator lining and extends over part of the axial length of the stator lining. A winding direction (right-handed or left-handed) of the recess around the longitudinal center axis of the stator can be formed taking into account a winding direction of the worm contour on the inner surface of the stator lining surrounding the rotor receiving space. In particular, these winding directions can be in the same direction.Two or more correspondingly spiral-shaped recesses can also be formed on the stator lining, which can run parallel to one another, wherein two recesses arranged adjacent to one another can each be separated from one another by a helically extending partition wall.

[0022] According to a further advantageous embodiment, the stator lining has at least one inner lining section arranged radially on the inside, which has the rotor receiving space, and at least one outer lining section arranged radially on the outside of the inner lining section, via which outer lining section the inner lining section is supported radially on the outside on a stator housing, wherein a depth of the recess varies according to an outer circumferential surface of the inner lining section, wherein the outer circumferential surface of the inner lining section corresponds to an enlargement of a screw contour on an inner circumferential surface of the stator lining enclosing the rotor receiving space, and wherein the inner lining section has a constant material thickness. Due to this embodiment of the inner lining section, it has essentially uniform stability properties over its axial length.It has deformability properties that can only be varied by the geometry of the inner lining section, which is defined by the screw contour. The inner lining section can be monolithically connected to the outer lining section and, in particular, can be made partially or entirely of the same material as the outer lining section.

[0023] According to a further advantageous embodiment, at least one anti-rotation recess extending over part of the axial length of the stator lining or at least one anti-rotation projection extending over part of the axial length of the stator lining is formed on the outer circumferential surface of the stator lining, wherein at least one anti-rotation projection engaging in the anti-rotation recess of the stator lining or at least one anti-rotation recess into which the anti-rotation projection of the stator lining engages is arranged on the inner circumferential surface of the stator housing. This can prevent the stator lining from rotating about the longitudinal center axis of the stator relative to the stator housing during operation of a correspondingly equipped eccentric screw pump. This embodiment is particularly advantageous when the stator lining is frustoconical in shape.This configuration can be omitted, for example, if the stator lining has a polygonal, for example, square, hexagonal, or octagonal, cross-sectional area, which is possible in an alternative advantageous embodiment of the invention. The anti-rotation projection on the stator housing can, for example, be designed as a longitudinally extending strip that is mechanically fixed to the stator housing shell. Alternatively, the anti-rotation projection can be connected monolithically or integrally to the stator housing.

[0024] According to a further advantageous embodiment, the inner surface of the stator housing and the outer surface of the stator lining are at least partially polygonal. This prevents the stator lining from rotating about the longitudinal center axis of the stator relative to the stator housing during operation of a correspondingly equipped eccentric screw pump. The inner surface of the stator housing and the outer surface of the stator lining can be partially or completely square, hexagonal, or octagonal, for example. An anti-rotation projection and a cooperating anti-rotation recess are not required with this embodiment.

[0025] According to a further advantageous embodiment, only the inner circumferential surface of the central section of the stator housing and the outer circumferential surface of the intermediate section of the stator lining are polygonal. The pressure-side end section and / or the suction-side end section of the stator housing can be circularly hollow-cylindrical, while the pressure-side piston end section and / or the suction-side piston end section of the stator lining can be circularly disk-shaped with a central opening.

[0026] According to a further advantageous embodiment, the stator lining is formed from a material selected from a group comprising at least one metal, at least one metal alloy, and at least one plastic or plastic composite material. As a result, the stator lining is hard, for example, compared to an elastomeric stator lining, and thus not as elastically deformable. A thermosetting or thermoplastic plastic, for example, can be used as the plastic. A fiber-reinforced or powder-reinforced plastic, for example, can be used as the plastic composite material. A fiber-reinforced plastic can have, for example, glass fibers, carbon fibers, ceramic fibers, aramid fibers, boron fibers, basalt fibers, steel fibers, natural fibers, or nylon fibers as reinforcing fibers.The powder-reinforced plastic can be, for example, a polyvinylidene fluoride, a tetrafluoroethylene-hexafluoropropylene copolymer, a perfluoroalkoxy polymer, or the like. The powder-reinforced plastic can be provided with a carbon or graphite powder. In the case of a plastic or plastic composite material, this preferably has a hardness value of at least 65, preferably of at least 80, particularly preferably of at least 90, on the Shore D hardness scale. If such a hard plastic or plastic composite material is used, a coating that is more elastic than the stator lining, for example a rubber coating, can be arranged on an inner surface of the stator lining facing the rotor receiving space. Aluminum or copper, for example, can be used as the metal for the stator lining.Metal alloys used for the stator lining can be, for example, steel, an aluminum alloy or a copper alloy.

[0027] In the following, the invention is explained by way of example with reference to the attached figures using preferred embodiments, wherein the features explained below can represent an advantageous and / or further developing aspect of the invention both individually and in different combinations with one another.

[0028] Short description of the characters

[0029] It shows:

[0030] Fig. 1 is a schematic and perspective view of an embodiment of a stator according to the invention;

[0031] Fig. 2 is a further schematic and perspective view of the stator shown in Fig. 1;

[0032] Fig. 3 is a schematic end view of the stator shown in Figs. 1 and 2;

[0033] Fig. 4 is a schematic longitudinal sectional view of the stator shown in Figs. 1 to 3, taken along section plane IV-IV of Fig. 3; Fig. 5 is a schematic and perspective view of the stator lining of the stator shown in Figs. 1 to 4;

[0034] Fig. 6 is a schematic side view of an inner lining portion of the stator lining shown in Figs. 1 to 5;

[0035] Fig. 7 is a schematic and perspective view of a further embodiment of a stator according to the invention;

[0036] Fig. 8 is a further schematic and perspective view of the stator shown in Fig. 7;

[0037] Fig. 9 is a schematic side view of the stator shown in Figs. 7 and 8;

[0038] Fig. 10 is a schematic longitudinal sectional view of the stator shown in Figs. 7 to 9 according to the section plane XX of Fig. 9; and

[0039] Fig. 11 is a schematic and perspective view of the stator lining of the stator shown in Figs. 7 to 10.

[0040] Detailed description of the characters

[0041] In the figures, identical or functionally identical components are provided with the same reference numerals. A repeated description of such components may be omitted below to avoid unnecessary repetition.

[0042] Fig. 1 shows a schematic and perspective view of an embodiment of a stator 1 according to the invention for an eccentric screw pump (not shown). Among other things, the suction side of the stator 1 facing the viewer of Fig. 1 is shown.

[0043] The stator 1 has a sleeve-shaped stator housing 2 made of a metal or a metal alloy. The stator housing 2 has a hollow cylindrical pressure-side end section 3 on the pressure side, a hollow cylindrical suction-side end section 4 on the suction side, and a hollow truncated cone-shaped central section 5 arranged between the two end sections 3 and 4. An inner diameter of the pressure-side end section 3 shown in Fig. 4 is larger than an inner diameter of the suction-side end section 4 shown in Fig. 4. An outer diameter of the pressure-side end section 3 shown in Fig. 4 is also larger than an outer diameter of the suction-side end section 4 shown in Fig. 4, wherein the pressure-side end section 3 and the suction-side end section 4 have the same wall thickness. An axial length of the suction-side end section 4 shown in Fig. 4 corresponds to one shown in Fig.4 shown axial length of the pressure-side end section 3.

[0044] An inner circumferential surface of the central section 5, shown in Fig. 4, tapers conically from the pressure-side end section 3 to the suction-side end section 4. An outer circumferential surface 30 of the central section 5 also tapers conically from the pressure-side end section 3 to the suction-side end section 4, such that the central section 5 has the same wall thickness throughout. An inner circumferential surface of the pressure-side end section 3, shown in Fig. 4, merges into an inner circumferential surface of the central section 5, shown in Fig. 4, via a shoulder, shown in Fig. 4, which is formed circumferentially on the inner circumferential surface of the stator housing 2, shown in Fig. 4, and points radially inward. An inner circumferential surface of the suction-side end section 4, shown in Fig. 4, merges seamlessly into the inner circumferential surface of the central section 5, as shown in Fig. 4.

[0045] In addition, the stator 1 has an elastically deformable stator lining 6 which is enclosed radially on the outside by the stator housing 2 with respect to a longitudinal center axis L of the stator 1 and which is in contact with the inner surface of the stator housing 2 shown in Fig. 4. On the stator lining 6, a rotor receiving space 7 is formed which is axially continuous with respect to the longitudinal center axis L of the stator 1 from the pressure side of the stator 1 facing away from the viewer in Fig. 1 to the suction side of the stator 1 shown, for receiving a rotor (not shown) of the eccentric screw pump. A screw contour 9 is formed on an inner surface 8 of the stator lining 6 which encloses the rotor receiving space 7.

[0046] The stator lining 6 is formed from a material selected from a group comprising at least one metal, at least one metal alloy and at least one plastic or plastic composite material having a hardness value of at least 65 on the Shore D hardness scale.

[0047] 4 and 5 and the inner surface of the stator housing 2 shown in Fig. 4 each taper conically over most of their respective axial length from the pressure side of the stator 1 to the suction side of the stator 1. The stator lining 6 has, on the pressure side, a pressure-side piston end section shown in Figs. 2 to 5, which is guided axially displaceably in the pressure-side end section 3, on the suction side, a suction-side piston end section 10 which is guided axially displaceably in the suction-side end section 4 and is disc-shaped with a central opening 15, and an intermediate section shown in Figs. 4 and 5, which is arranged between the pressure-side piston end section and the suction-side piston end section 10 and whose length is shown in Figs.4 and 5 tapers conically from the pressure-side piston end section to the suction-side piston end section 10.

[0048] The stator lining 6 has a radially inwardly arranged inner lining section 11, which has the rotor receiving space 7, and an outer lining section 12 arranged radially outwardly of the inner lining section 11, via which outer lining section 12 the inner lining section 11 is supported radially outwardly on a stator housing 2. An outer circumferential surface of the inner lining section 11 shown in Figs. 4 and 6 corresponds to an enlargement of the screw contour 9 on the inner circumferential surface 8 of the stator lining 6 enclosing the rotor receiving space 7. The inner lining section 11 has a constant material thickness, as shown in Fig. 4.

[0049] As shown in Fig. 4, the stator lining 6 is arranged in the stator housing 2 so as to be axially displaceable under radial elastic deformation by a distance of predetermined length shown in Fig. 4 in the direction of the suction side of the stator 1.

[0050] On the outer surface of the stator lining 6 shown in Figs. 4 and 5, there are recesses arranged radially outwardly at a distance from the rotor receiving space 7, which are open radially outward and are shown in Figs. 4 and 5, each of which is formed helically circumferentially on the stator lining 6. A depth of the respective recess shown in Fig. 4 varies according to the depth shown in Figs.

[0051] 4 and 6 shown outer surface of the inner lining section 11.

[0052] On the outer surface of the stator lining 6 shown in Figs. 4 and 5, an anti-rotation recess extending over part of the axial length of the stator 1 is formed. On the inner surface of the stator housing 2 shown in Fig. 4, an anti-rotation projection engaging in the anti-rotation recess of the stator lining 6 is arranged.

[0053] Fig. 2 shows a further schematic and perspective view of the stator 1 shown in Fig. 1. The pressure side of the stator 1 is shown, which faces the viewer of Fig. 2. Also shown is the pressure-side piston end section 13 of the stator lining 6, which is disk-shaped with a central opening 14.

[0054] Fig. 3 shows a schematic end view of the stator 1 shown in Figs. 1 and 2, in particular an end view of the pressure side of the stator 1.

[0055] Fig. 4 shows a schematic longitudinal sectional view of the stator 1 shown in Figs. 1 to 3 according to the sectional plane IV-IV of Fig. 3.

[0056] Fig. 4 shows that the inner diameter d1 of the pressure-side end section 3 is larger than the inner diameter d2 of the suction-side end section 4. Furthermore, Fig. 4 shows that the outer diameter D1 of the pressure-side end section 3 is larger than the outer diameter D2 of the suction-side end section 4, such that the pressure-side end section 3 and the suction-side end section 4 have the same wall thickness. Furthermore, Fig. 4 shows that the axial length L2 of the suction-side end section 4 corresponds to the axial length L1 of the pressure-side end section 3.

[0057] The inner surface 16 of the central section 5 tapers conically from the pressure-side end section 3 to the suction-side end section 4. The hollow-cylindrical inner surface 28 of the pressure-side end section 3 merges into the inner surface 16 of the central section 5 via a radially inward-facing shoulder 18 formed circumferentially on the inner surface 17 of the stator housing 2. The hollow-cylindrical inner surface 29 of the suction-side end section 4 merges seamlessly into the inner surface 16 of the central section 5.

[0058] Fig. 4 further shows that the outer circumferential surface 19 of the stator lining 6 is in contact with the inner circumferential surface 17 of the stator housing 2. The outer circumferential surface 19 of the stator lining 6 and the inner circumferential surface 17 of the stator housing 2 each taper conically over most of their respective axial lengths from the pressure side of the stator 1 shown on the left in Fig. 4 to the suction side of the stator 1 shown on the right in Fig. 4. The stator lining 6 has, on the pressure side, the pressure-side piston end section 13 which is guided axially displaceably in the pressure-side end section 3, on the suction side the suction-side piston end section 10 which is guided axially displaceably in the suction-side end section 4 and the intermediate section 20 arranged between the piston end sections 10 and 13. Only the outer circumferential surface 21 of the intermediate section 20 tapers conically from the pressure-side piston end section 13 to the suction-side piston end section 10.Each piston end section 10 or 13 has an annular piston groove 22 that is open radially outwards.

[0059] The outer surface 23 of the inner lining section 11 corresponds to an enlargement of the screw contour 9 on the inner surface 8 of the stator lining 6 surrounding the rotor receiving space 7. The inner lining section 11 has a constant material thickness.

[0060] The stator lining 6 is arranged in the stator housing 2, subject to radial elastic deformation according to the arrow P, by a distance S of a predetermined length in the direction of the suction side of the stator 1. The length of the distance S is defined by the axial length of the pressure-side end section 3 and a thickness of the pressure-side piston end section 13, which is given in the axial direction. On the suction side, the distance S is limited by the shoulder 18.

[0061] On the outer surface 19 of the stator lining 6, a plurality of recesses 24 are formed, each arranged radially outwardly at a distance from the rotor receiving space 7, which are open on the radial outside and each are formed helically around the stator lining 6. The depth of the respective recess 24 in the radial direction varies according to the outer surface 23 of the inner lining section 11. Recesses 24 arranged adjacent to one another are each separated from one another by a helically extending partition wall 25, which forms part of the outer lining section 12 of the stator lining 6.

[0062] On the outer surface 19 of the stator lining 6, an anti-rotation recess 26 is formed, extending over part of the axial length of the stator 1. On the inner surface 17 of the stator housing 2, an anti-rotation projection 27 is arranged, engaging in the anti-rotation recess 26 of the stator lining 6. The anti-rotation projection 27 is monolithically connected to the stator housing 2 and is arranged on the central section 5 of the stator housing 2 such that it extends over most of the axial length of the central section 5. The anti-rotation recess 26 is formed on the intermediate section 20 of the stator lining 6 such that it extends over most of the axial length of the intermediate section 20.

[0063] Fig. 5 shows a schematic and perspective view of the stator lining 6 of the stator 1 shown in Figs. 1 to 4. It mainly shows the conical shape of the stator lining 6 or the intermediate section 20.

[0064] Fig. 6 shows a schematic side view of the inner lining section 11 of the stator lining 6 shown in Figs. 1 to 5. The outer lining section shown in Figs. 1 to 5 has been omitted in order to better illustrate the design of the inner lining section 11. It is shown that the outer circumferential surface 23 of the inner lining section 11 is an enlargement of the screw contour shown in Figs. 1 to 5.

[0065] Fig. 7 shows a schematic and perspective view of another embodiment of a stator 1 according to the invention for an eccentric screw pump (not shown). Among other things, the pressure side of the stator 1 facing the viewer of Fig. 7 is shown.

[0066] The stator 1 has a sleeve-shaped stator housing 2 made of a metal or a metal alloy. The stator housing 2 has a hollow cylindrical pressure-side end section 3 on the pressure side, a hollow cylindrical suction-side end section 4 on the suction side, and a polygonal and conical central section 5 arranged between the two end sections 3 and 4.

[0067] An inner diameter of the pressure-side end section 3 shown in Fig. 10 is larger than an inner diameter of the suction-side end section 4 shown in Fig. 10. An outer diameter of the pressure-side end section 3 shown in Fig. 10 is also larger than an outer diameter of the suction-side end section 4 shown in Fig. 10, wherein the pressure-side end section 3 and the suction-side end section 4 have the same wall thickness. An axial length of the suction-side end section 4 shown in Fig. 10 corresponds to an axial length of the pressure-side end section 3 shown in Fig. 10.

[0068] An inner circumferential surface of the central section 5, shown in Fig. 10, tapers conically from the pressure-side end section 3 to the suction-side end section 4. An outer circumferential surface 30 of the central section 5 also tapers conically from the pressure-side end section 3 to the suction-side end section 4, such that the central section 5 has the same wall thickness throughout. An inner circumferential surface of the pressure-side end section 3, shown in Fig. 10, merges into the inner circumferential surface of the central section 5, shown in Fig. 10, via a shoulder, shown in Fig. 10, formed circumferentially on the inner circumferential surface of the stator housing 2, shown in Fig. 10, and pointing radially inwards. An inner surface of the suction-side end section 4 shown in Fig. 10 merges seamlessly into the inner surface of the middle section 5 shown in Fig. 10, as shown in Fig. 10.

[0069] In addition, the stator 1 has an elastically deformable stator lining 6 which is enclosed radially on the outside by the stator housing 2 with respect to a longitudinal center axis L of the stator 1 and which is in contact with the inner surface of the stator housing 2 shown in Fig. 10 by means of an outer circumferential surface shown in Figs. 10 and 11. On the stator lining 6, a rotor receiving space 7 is formed which is axially continuous with respect to the longitudinal center axis L of the stator 1 from the pressure side of the stator 1 facing the viewer in Fig. 7 to the suction side of the stator 1 facing away from the viewer in Fig. 7 for receiving a rotor (not shown) of the eccentric screw pump. A screw contour 9 is formed on an inner surface 8 of the stator lining 6 which encloses the rotor receiving space 7.The stator lining 6 is formed from a material selected from a group comprising at least one metal, at least one metal alloy and at least one plastic or plastic composite material having a hardness value of at least 65 on the Shore D hardness scale.

[0070] The outer surface of the stator lining 6 shown in Fig. 10 and 11 and the inner surface of the stator housing 2 shown in Fig. 10 each taper conically over most of their respective axial length from the pressure side of the stator 1 to the suction side of the stator 1. The stator lining 6 has, on the pressure side, a pressure-side piston end section 13 which is guided axially displaceably in the pressure-side end section 3 and is disk-shaped with a central opening 14, on the suction side, a suction-side piston end section shown in Figs. 8, 10 and 11 which is guided axially displaceably in the suction-side end section 4, and an intermediate section shown in Figs. 10 and 11 which is arranged between the pressure-side piston end section 13 and the suction-side piston end section and whose intermediate section is shown in Figs.10 and 11 tapers conically from the pressure-side piston end section 13 to the suction-side piston end section.

[0071] The stator lining 6 has a radially inwardly arranged inner lining section 11, which has the rotor receiving space 7, and an outer lining section 12 arranged radially outwardly of the inner lining section 11, via which outer lining section 12 the inner lining section 11 is supported radially outwardly on a stator housing 2. An outer circumferential surface of the inner lining section 11 shown in Fig. 10 corresponds to an enlargement of the screw contour 9 on the inner circumferential surface 8 of the stator lining 6 surrounding the rotor receiving space 7. The inner lining section 11 has a constant material thickness, as shown in Fig. 10. The inner lining section 11 can be designed according to Fig. 6.

[0072] As shown in Fig. 10, the stator lining 6 is arranged in the stator housing 2, subject to radial elastic deformation by a predetermined length in the direction of the suction side of the stator 1. Recesses are formed on the outer surface of the stator lining 6, spaced radially outward from the rotor receiving space 7, radially open on the outside, and shown in Figs. 10 and 11, each of which extends helically around the stator lining 6. The depth of the respective recess shown in Fig. 10 varies according to the outer surface of the inner lining section 11 shown in Fig. 10.

[0073] The inner surface of the stator housing 2 shown in Fig. 10 and the outer surface of the stator lining 6 shown in Figs. 10 and 11 are each at least partially polygonal. In particular, only the inner surface of the central section 5 of the stator housing 2 shown in Fig. 10 and the outer surface of the intermediate section of the stator lining 6 shown in Figs. 10 and 11 are polygonal.

[0074] Fig. 8 shows a further schematic and perspective view of the stator 1 shown in Fig. 7. It shows the suction side of the stator 1, which partially faces the viewer of Fig. 8. Also shown is the suction-side piston end section 10 of the stator lining 6, which is disk-shaped with a central opening 15.

[0075] Fig. 9 shows a schematic side view of the stator 1 shown in Figs. 7 and 8. It is shown in particular that the end sections 3 and 4 of the stator housing 2 are cylindrical and the central section 5 of the stator housing 2 is conical.

[0076] Fig. 10 shows a schematic longitudinal sectional view of the stator 1 shown in Figs. 7 to 9 according to the sectional plane XX of Fig. 9. The worm contour shown in Figs. 7 to 9 is omitted in Fig. 10.

[0077] Fig. 10 shows that the inner diameter d1 of the pressure-side end section 3 is larger than the inner diameter d2 of the suction-side end section 4. Furthermore, Fig. 10 shows that the outer diameter D1 of the pressure-side end section 3 is larger than the outer diameter D2 of the suction-side end section 4, such that the pressure-side end section 3 and the suction-side end section 4 have the same wall thickness. Furthermore, Fig. 10 shows that the axial length L2 of the suction-side end section 4 corresponds to the axial length L1 of the pressure-side end section 3. The inner surface 16 of the central section 5 tapers conically from the pressure-side end section 3 to the suction-side end section 4. The inner surface 28 of the pressure-side end section 3 merges into the inner surface 16 of the central section 5 via a radially inwardly facing shoulder 18 formed circumferentially on the inner surface 17 of the stator housing 2.The inner surface 29 of the suction-side end section 4 merges seamlessly into the inner surface 16 of the middle section 5.

[0078] Fig. 10 further shows that the outer circumferential surface 19 of the stator lining 6 is in contact with the inner circumferential surface 17 of the stator housing 2. The outer circumferential surface 19 of the stator lining 6 and the inner circumferential surface 17 of the stator housing 2 each taper conically over most of their respective axial lengths from the pressure side of the stator 1 shown on the left in Fig. 10 to the suction side of the stator 1 shown on the right in Fig. 10. The stator lining 6 here has, on the pressure side, the pressure-side piston end section 13 which is guided axially displaceably in the pressure-side end section 3, on the suction side the suction-side piston end section 10 which is guided axially displaceably in the suction-side end section 4 and the intermediate section 20 arranged between the piston end sections 10 and 13.Only the outer circumferential surface 21 of the intermediate section 20 tapers conically from the pressure-side piston end section 13 to the suction-side piston end section 10. Each piston end section 10 or 13 has an annular piston groove 22 which is open radially outwards.

[0079] The outer surface 23 of the inner lining section 11 corresponds to an enlargement of the screw contour 9 on the inner surface 8 of the stator lining 6 surrounding the rotor receiving space 7. The inner lining section 11 has a constant material thickness.

[0080] The stator lining 6 is arranged in the stator housing 2 so as to be axially displaceable by a distance S of a predetermined length in the direction of the suction side of the stator 1, subjected to radial elastic deformation according to the arrow P. The length of the distance S is defined by the axial length of the pressure-side end section 3 and a thickness of the pressure-side piston end section 13, which is given in the axial direction. On the suction side, the distance S is limited by the shoulder 18. In the state shown in Fig. 10, the stator lining 6 has been displaced axially by a portion of the distance S in the direction of the suction side of the stator 1 and is thus shown in an intermediate position.

[0081] On the outer surface 19 of the stator lining 6, a plurality of recesses 24 are formed, each arranged radially outwardly at a distance from the rotor receiving space 7 and open radially outwardly, each of which is formed helically around the stator lining 6. The depth of the respective recess 24 in the radial direction varies according to the outer surface 23 of the inner lining section 11. Recesses 24 arranged adjacent to one another are each separated from one another by a helically extending partition wall 25, which forms part of the outer lining section 12 of the stator lining 6.

[0082] Fig. 11 shows a schematic and perspective view of the stator lining 6 of the stator 1 shown in Figs. 7 to 10. It mainly shows the conical and polygonal shape of the stator lining 6 and the intermediate section 20.

[0083] List of reference symbols

[0084] 1 stator

[0085] 2 stator housings

[0086] 3 pressure-side end section of 2

[0087] 4 suction-side end section of 2

[0088] 5 Middle section of 2

[0089] 6 Stator lining

[0090] 7 Rotor receiving space

[0091] 8 inner surface of 6

[0092] 9 Screw contour

[0093] 10 pressure-side piston end section

[0094] 11 inner lining section

[0095] 12 outer lining section

[0096] 13 pressure-side piston end section

[0097] 14 Breakthrough at 13

[0098] 15 Breakthrough at 10

[0099] 16 inner surface area of ​​5

[0100] 17 inner surface of 2

[0101] 18th level

[0102] 19 Outer surface area of ​​6

[0103] 20 intermediate section of 6

[0104] 21 outer surface of 20

[0105] 22 Piston groove

[0106] 23 outer surface of 11

[0107] 24 recess

[0108] 25 Partition wall

[0109] 26 Anti-rotation recess

[0110] 27 Anti-rotation projection

[0111] 28 inner surface of 3

[0112] 29 inner surface of 4

[0113] 30 outer surface of 5

[0114] D1 outer diameter of 3 d1 inner diameter of 3 D2 outer diameter of 4 d2 inner diameter of 4

[0115] L Longitudinal center axis of 1

[0116] L1 axial length of 3 L2 axial length of 4

[0117] P Arrow (movability of 6)

[0118] S route

Claims

Patent claims 1. Stator (1) for an eccentric screw pump, comprising at least one sleeve-shaped stator housing (2) and at least one elastically deformable stator lining (6) which is enclosed radially on the outside by the stator housing (2) with respect to a longitudinal center axis (L) of the stator (1), and which is in contact with an inner circumferential surface (17) of the stator housing (2) by means of an outer circumferential surface (19), characterized in that the outer circumferential surface (19) of the stator lining (6) and the inner circumferential surface (17) of the stator housing (2) taper conically at least over the largest part of their respective axial length from a pressure side of the stator (1) to a suction side of the stator (1), and the stator lining (6) is arranged in the stator housing (2) so as to be axially displaceable by a distance (S) of a predetermined length in the direction of the suction side of the stator (1), subjected to radial elastic deformation.

2. Stator (1) according to claim 1, characterized in that the stator housing (2) has a hollow cylindrical pressure-side end section (3) on the pressure side, a hollow cylindrical suction-side end section (4) on the suction side and a central section (5) arranged between the two end sections (3, 4), wherein an inner diameter (d1) of the pressure-side end section (3) is greater than an inner diameter (d2) of the suction-side end section (4), wherein an inner circumferential surface (16) of the central section (5) tapers conically from the pressure-side end section (3) to the suction-side end section (4), wherein an axial length (L2) of the suction-side end section (4) corresponds at least to an axial length (L1) of the pressure-side end section (3), wherein an inner circumferential surface (28) of the pressure-side end section (3) has a circumferentially on the inner surface (17) of the stator housing (2) formed, radially inwardly facing shoulder (18) merges into the inner surface (16) of the central section (5) and an inner surface (29) of the suction-side end section (4) merges steplessly into the inner surface (16) of the central section (3), and the stator lining (6) has on the pressure side a pressure-side piston end section (13) guided axially displaceably in the pressure-side end section (3), on the suction side a suction-side piston end section (10) and an intermediate section (20) arranged between the piston end sections (10, 13), the outer circumferential surface (21) of which tapers conically continuously from the pressure-side piston end section (13) to the suction-side piston end section (10).

3. Stator (1) according to claim 1 or 2, characterized in that on the outer circumferential surface (19) of the stator lining (6) at least one recess (24) is formed which is open on the outside and is arranged radially outwardly and spaced from a rotor receiving space (7) which is formed axially continuously on the stator lining (6) from the pressure side of the stator (1) to the suction side of the stator (1) with respect to the longitudinal center axis (L).

4. Stator (1) according to claim 3, characterized in that the recess (24) is formed at least partially helically circumferentially on the stator lining (6).

5. Stator (1) according to claim 3 or 4, characterized in that the stator lining (6) has at least one radially inwardly arranged inner lining section (11), which has the rotor receiving space (7), and at least one outer lining section (12) arranged radially outwardly of the inner lining section (11), via which outer lining section (12) the inner lining section (11) is supported radially outwardly on a stator housing (2), wherein a depth of the recess (24) varies according to an outer circumferential surface (23) of the inner lining section (11), wherein the outer circumferential surface (23) of the inner lining section (11) corresponds to an enlargement of a worm contour (9) on an inner circumferential surface (8) of the stator lining (6) enclosing the rotor receiving space (7), and wherein the inner lining section (11) has a constant material thickness.

6. Stator (1) according to one of claims 1 to 5, characterized in that at least one anti-rotation recess (26) extending over part of the axial length of the stator (1) or at least one anti-rotation projection extending over part of the axial length of the stator (1) is formed on the outer circumferential surface (19) of the stator lining (6), wherein at least one anti-rotation projection extending over part of the axial length of the stator (1) is formed on the inner circumferential surface (17) of the stator housing (2) securing recess (26) of the stator lining (6) engaging anti-rotation projection (27) or at least one anti-rotation recess into which the anti-rotation projection of the stator lining (6) engages is arranged.

7. Stator (1) according to one of claims 1 to 5, characterized in that the inner circumferential surface (17) of the stator housing (2) and the outer circumferential surface (19) of the stator lining (6) are at least partially polygonal.

8. Stator (1) according to claim 7, characterized in that only the inner circumferential surface (16) of the central section (5) of the stator housing (2) and the outer circumferential surface (21) of the intermediate section (20) of the stator lining (6) are polygonal.

9. Stator (1) according to one of claims 1 to 8, characterized in that the stator lining (6) is formed from a material selected from a group comprising at least one metal, at least one metal alloy and at least one plastic or plastic composite material.

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