Eccentric Screw Pump Having A Stator Linking Which is Simpler to Produce

Abstract

The invention relates to an eccentric screw pump, including a rotor, which forms a conveying screw, and a stator, which forms a screw flight and in which the rotor rotates during conveying operation, wherein: the stator includes a stator housing, in which a stator lining is disposed, the stator lining reproducing the screw flight; the stator lining is a sleeve which is supported, at its outer periphery, on the stator housing by means of a support structure which forms cavities; the support structure is designed and dimensioned, in accordance with the location of its connection to the sleeve, in such a way that the supporting effect provided by the support structure is matched to the local needs of the sleeve.

Claims

1. An eccentric screw pump having a rotor forming a screw conveyor and a stator forming a screw flight, in which the rotor revolves during conveying operation, wherein the stator comprises a stator housing, in which a stator lining is located, which reproduces the screw flight, wherein the stator lining is a sleeve, which supports itself on its outer periphery on the stator housing via a support structure, which forms cavities, characterized in that as a function of the location of its connection to the sleeve, the support structure is designed and dimensioned so that the support effect provided by it is matched to the local needs of the sleeve.

2. The eccentric screw pump according to claim 1, characterized in that the support effect is matched to the local needs of the sleeve in that an increasing wall thickness of the support structure is provided along the leakage flow direction, or in that the support effect is additionally or alternatively matched to the local needs of the sleeve in that, viewed along the peripheral direction, a larger wall thickness is provided, or that the support effect is additionally or alternatively matched to the local needs of the sleeve in that the degree of the inclination, which influences the local spring effect of the support structure, of the wall forming the support structure is used as embodiment means or in that additionally or alternatively, the local density of the support structure is varied so that the imparted support effect is matched to the local conditions.

3. The eccentric screw pump preferably according to claim 1, having a rotor forming a screw conveyor and a stator forming a screw flight, in which the rotor revolves during conveying operation, wherein the stator comprises a (one- or multi-part) stator housing, in which a stator lining is located, which reproduces the screw flight, wherein the stator lining is a sleeve made of solid material, which, on its outer periphery, supports itself on the stator housing via a support structure, which forms cavities, characterized in that the sleeve is thin-walled and that its wall thickness is preferably not more than , better not more than 1/10 and ideally not more than 1/12 of the average inner radius of the stator housing.

4. The eccentric screw pump according to claim 1, having a rotor forming a screw conveyor and a stator forming a screw flight, in which the rotor revolves during conveying operation, wherein the stator comprises a (one- or multi-part) stator housing, in which a stator lining is located, which reproduces the screw flight, wherein the stator lining is a sleeve made of solid material, which, on its outer periphery, supports itself on the stator housing via a support structure, which forms (macroscopic) cavities, characterized in that the sleeve is thin-walled and that the wall thickness of the sleeve varies locally, preferably by maximally +/30%, better by maximally +/20%, ideally by maximally +/12.5%.

5. The eccentric screw pump, preferably according to claim 1, having a rotor forming a screw conveyor and a stator forming a screw flight, in which the rotor revolves during conveying operation, wherein the stator comprises a (one- or multi-part) stator housing, in which a stator lining is located, which reproduces the screw flight, wherein the stator lining is a sleeve made of solid material, which, on its outer periphery, supports itself on the stator housing via a support structure, which forms (macroscopic) cavities, characterized in that the support structure consists of support cells, which each define or enclose, respectively, a cavity, wherein the cavity enclosed by them preferably opens out towards the stator housing, wherein the clear cross sectional surface of the cavity, which is enclosed by such a support cell, preferably decreases in the radially outward direction.

6. The eccentric screw pump according to claim 5, characterized in that the support cells form honeycombs or other tube sections, which preferably have a honeycomb structure with resilient and/or damping effect and which ideally form a hexagonal base surface.

7. The eccentric screw pump according to claim 5, characterized in that the wall thickness of the support cells corresponds to the average wall thickness of the sleeve (completely or at least at +/15%, better at least at +/7.5%).

8. The eccentric screw pump according to claim 7, characterized in that the inner peripheral surface of the stator housing has a polygonal cross section, which corresponds to the cross section of the enveloping surface of the stator lining.

9. The eccentric screw pump according to claim 1, characterized in that lubricant is supplied to the inner peripheral surface from the outer peripheral surface of the sleeve, ideally by means of diffusion or compression through the sleeve wall, for the most part all the way into the region of a lubrication pocket on the inner side.

10. The eccentric screw pump according to claim 1 characterized in that at least locally with respect to other sections of the stator lining, the sleeve is provided with a sleeve wall region having a porosity, which is increased in such a way that lubricant can be pushed through the respective locations, all the way to the inner surface of the sleeve, without the fluid pumped in the opposite direction being able to enter to the outside via the porous inner wall region.

11. The eccentric screw pump, according to claim 1, having a rotor forming a screw conveyor and a stator forming a screw flight, in which the rotor revolves during conveying operation, wherein the stator comprises a (one- or multi-part) stator housing, in which a stator lining is located, which reproduces the screw flight, wherein the stator lining is a sleeve made of solid material, which, on its outer periphery, supports itself on the stator housing via a support structure, which forms (macroscopic) cavities, characterized in that the support structure is designed so that it effects a temperature compensation in such a way that the screw flight formed by the sleeve does not constrict or constricts only less strongly in the case of a heat-up of the support structure.

12. A stator lining for an eccentric screw pump, characterized in that the stator lining having a rotor forming a screw conveyor and a stator forming a screw flight, in which the rotor revolves during conveying operation, wherein the stator comprises a stator housing, in which a stator lining is located, which reproduces the screw flight, wherein the stator lining is a sleeve, which supports itself on its outer periphery on the stator housing via a support structure, which forms cavities, characterized in that as a function of the location of its connection to the sleeve, the support structure is designed and dimensioned so that the support effect provided by it is matched to the local needs of the sleeve.

13. A method for producing a stator lining reproducing a screw flight for an eccentrical screw pump, characterized in that a sleeve is primarily shaped by means of additive material application, preferably in the axial direction, progressing from the bottom to the top, which reproduces the screw flight and the outer peripheral surface of which preferably merges into support cells integrally forming in cavities, which are preferably likewise originally shaped by means of additive material application.

14. The method for producing a stator lining reproducing a screw flight according to claim 13, characterized in that the sleeve is printed in layers of several, at least two, different materials, wherein a material, which, compared to steel or ceramic or compared to the otherwise used rotor material, respectively, has a coefficient of sliding friction, which is decreased compared to the material otherwise used for printing, is preferably used for the radially innermost layer.

15. The method for producing a stator lining reproducing a screw flight according to claim 13, characterized in that a different material is entirely, predominantly or essentially used for printing the walls delimiting the support cells than for printing the sleeve.

16. The eccentric screw pump preferably according to claim 2, having a rotor forming a screw conveyor and a stator forming a screw flight, in which the rotor revolves during conveying operation, wherein the stator comprises a (one- or multi-part) stator housing, in which a stator lining is located, which reproduces the screw flight, wherein the stator lining is a sleeve made of solid material, which, on its outer periphery, supports itself on the stator housing via a support structure, which forms cavities, characterized in that the sleeve is thin-walled and that its wall thickness is preferably not more than , better not more than 1/10 and ideally not more than 1/12 of the average inner radius of the stator housing.

17. The eccentric screw pump according to claim 2, having a rotor forming a screw conveyor and a stator forming a screw flight, in which the rotor revolves during conveying operation, wherein the stator comprises a (one- or multi-part) stator housing, in which a stator lining is located, which reproduces the screw flight, wherein the stator lining is a sleeve made of solid material, which, on its outer periphery, supports itself on the stator housing via a support structure, which forms (macroscopic) cavities, characterized in that the sleeve is thin-walled and that the wall thickness of the sleeve varies locally, preferably by maximally +/30%, better by maximally +/20%, ideally by maximally +/12.5%.

18. The eccentric screw pump, preferably according to claim 2, having a rotor forming a screw conveyor and a stator forming a screw flight, in which the rotor revolves during conveying operation, wherein the stator comprises a (one- or multi-part) stator housing, in which a stator lining is located, which reproduces the screw flight, wherein the stator lining is a sleeve made of solid material, which, on its outer periphery, supports itself on the stator housing via a support structure, which forms (macroscopic) cavities, characterized in that the support structure consists of support cells, which each define or enclose, respectively, a cavity, wherein the cavity enclosed by them preferably opens out towards the stator housing, wherein the clear cross sectional surface of the cavity, which is enclosed by such a support cell, preferably decreases in the radially outward direction.

19. The eccentric screw pump according to claim 2, characterized in that lubricant is supplied to the inner peripheral surface from the outer peripheral surface of the sleeve, ideally by means of diffusion or compression through the sleeve wall, for the most part all the way into the region of a lubrication pocket on the inner side.

20. The eccentric screw pump according to claim 2 characterized in that at least locally with respect to other sections of the stator lining, the sleeve is provided with a sleeve wall region having a porosity, which is increased in such a way that lubricant can be pushed through the respective locations, all the way to the inner surface of the sleeve, without the fluid pumped in the opposite direction being able to enter to the outside via the porous inner wall region.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0051] FIG. 1 shows an overview of an eccentric screw pump in general.

[0052] FIG. 2 shows a perspective view of a stator lining of a first exemplary embodiment of the invention.

[0053] FIG. 3 shows a cross section through the stator lining according to FIG. 2, in a plane perpendicular to the central longitudinal axis, around which the screw flight winds, whereby it is important to note that in reality, when looking into the sleeve 21, the support structure 23 cannot be seen on the smooth inner peripheral surface of said sleeveonly for the sake of clarity, FIG. 3 was drawn here as if the sleeve were transparent.

[0054] FIG. 4 shows a central longitudinal section through the stator lining according to FIG. 2.

[0055] FIG. 5 shows a cut-out of a further stator lining according to a second exemplary embodiment.

[0056] FIG. 6 shows a cut-out of the stator lining, on the basis of which it can be explained why obliquely inclined walls of the support structure make the support characteristic of the support structure softer.

[0057] FIG. 7 shows a further exemplary embodiment, in the case of which the wall thickness of the honeycombs forming the support structure increases from the suction side to the pressure side.

DETAILED DESCRIPTION

[0058] FIG. 1 shows the eccentric screw pump 1, which forms the base of the invention, as a whole.

[0059] The main components of such an eccentric screw pump 1 are the suction housing 11 and the pump section 12, which is in flow connection therewith.

[0060] The inlet 13 for the medium to be conveyed is formed on the suction housing 11.

[0061] The conveyed medium is output via the outlet 14, which is arranged on the end of the pump section 12.

[0062] The block construction is preferably selected, even if such a block construction is not mandatory with regard to patent law. The pump motor 15 is then flanged to the suction housing 11. The pump motor 15 drives the rotor, which will be described in more detail next, via the mostly gimbal-mounted drive train 16.

[0063] The pump section is formed by means of the stator 3 having the rotor revolving therein.

[0064] The rotor forms an eccentric screw 2, which can be classified as round threaded screw. Compared to a normal screw, the eccentric screw has a larger pitch, a larger flight depth and a smaller core diameter. The stator 3 consists of a stator lining 20 and a stator tube 5, which receives the stator lining in it. The stator lining is formed complementary to the rotor. It forms a screw flight, which, however, is equipped with twice the pitch length and an additional thread. Due to this arrangement, a row of conveying chambers 17 is created between the resting stator 3 and the rotor 2, which rotates therewith with eccentric effect and which is also referred to as screw due to its profiling. The conveying chambers 17 move continuously and without change of shape from their entrance side formed by the trumpet 18 on the suction housing 11 to their exit side, i.e., to the outlet 14. The medium located in the conveying chambers 17 is pressurized and conveyed thereby.

[0065] The movement speed of the conveying chambers 17 can be controlled via the speed of the rotor in the direction of the exit side and the theoretical pump conveying quantity can thus be controlled.

[0066] In addition to the number of the stator windings, the tightness of the contact line between rotor and stator influences the absorption capacity and the conveying pressure of the pump, which can be reached.

[0067] FIG. 2 shows a stator lining 20 according to a first exemplary embodiment in a perspective manner from the side in overall view. For a better understanding, it is suggested to view this FIG. 2 side by side with FIG. 3. The latter shows a vertical section through the stator lining illustrated by FIG. 2.

[0068] The sleeve 21, which forms the central part of the stator lining 20, can be seen well on the basis of FIG. 3. The sleeve 21 is shaped so that, on its inner surface 24, it represents a screw flight, which is largely matched to the screw 2, which is not illustrated here, which revolves in this screw flight 24 and produces the typical pumping effect of an eccentric screw pump in this way, see also FIG. 1 and the corresponding explanations.

[0069] It can be understood well on the basis of FIG. 2 that the topography of the outer peripheral surface 22 of the sleeve 21 reveals the screw-shaped course of the sleeve, which the latter has in its interior.

[0070] As can likewise be seen well on the basis of the comparison of FIGS. 2 and 3, a support structure 23, which forms macroscopic cavities 25, adjoins the outer periphery of the sleeve 21 and, as a rule, in integral connection. In the case at hand, the support structure is formed by rings or tube sections 26, respectively. It is particularly favorable that each ring or tube section, respectively, does not only have first wall portions along and second wall portions orthogonally to the central longitudinal axis, around which the screw flight formed by the sleeve winds, but that each ring or tube section also does not only comprise insignificant further wall portions, which run obliquely to said central longitudinal axis.

[0071] The tube sections in the form of hexagonal honeycombs, which are used here in the case of this exemplary embodiment, are particularly favorable thereby. Of these honeycombs, each is connected to its immediate neighbors or shares a wall with them, respectively. Each of them is preferably equipped here over the entire length in the radially outward direction with a hexagonal cross section, honeycomb-like rings encloses in its center a macroscopic cavity 25, as has already been mentioned briefly earlier. Each of these honeycomb-like rings abuts on its radially outward, open side against the inner surface of the stator tube, as it is shown by FIG. 3.

[0072] Each cavity 25 in the case of the embodiment shown here is thereby in each case completely separated from the adjacent cavities by means of the ring or tube section delimiting it.

[0073] Based on this, it can now be understood easily that each of the honeycomb-like rings 26 in each case acts like a support post and thus forms the support structure 23.

[0074] It readily makes sense that the support force or spring effect, respectively, of each preferably honeycomb-like ring 26 can be set highly accurately, in that the thickness of its wall is dimensioned accordingly. If the wall thickness becomes larger, the support effect also increases. The volumes of the cavities, which are enclosed by the support structure, then in each case become smaller. That said, it is of interest that the support structure 23 or the honeycomb-like rings thereof, respectively, or the cavities 25 thereof, respectively, have a mathematically describable and thus defined shape. The support effect cannot only be calculated very well in this way but the stator lining 20 can also be produced very well additively, can thus, for example, be manufactured by means of 3D printing.

[0075] It goes without saying that it depends on the individual case, how intensively the support structure 23 supports the sleeve 21. The support value TW is the measure for this. It specifies, with how many percent the imaginary jacket surface, which encases the outer periphery of the stator lining, is supported on the stator housing. Meaningful support values TW lie between 20% and 80%, better yet between 30% and 75%.

[0076] As can be seen, the wall thickness or average wall thickness W1, W2, Wn, respectively, of the sleeve is small. In the case of this exemplary embodiment, the wall thickness of the thin-walled sleeve 21 is limited to less than one tenth of the radius, which describes the clear opening of the stator housing.

[0077] The wall thickness of the sleeve 21 is constant or essentially constant in many cases, as it is also illustrated in FIG. 3. In other cases, it makes sense to allow the wall thickness of the sleeve to vary locally. A maximum variation of plus minus 30% around an average value should not be exceeded in most cases.

[0078] As can be seen, the wall thickness of the elements can form the support structure 23, thus, for example, of the honeycomb-like rings 26, which correspond to the wall thickness of the sleeve 21 (completely or essentially). It can be of particular interest here to allow the wall thickness of the rings or tube sections 26, respectively, or of the other elements taking their place, respectively, which form the support structure 23, to increase in the radially outward diction, in order to make the respective elements particularly resistant to kinking. This is so because the bending moment straining them obviously increases from the inside to the outside in the radial direction.

[0079] It can also be seen well on the basis of FIG. 3 that the stator housing 5 has a clear cross section on the inside, which is polygonal, ideally octagonal. This thus means that the inner surface of the stator housing 5 running in the peripheral direction is formed by a number of flat surface strips 27, which are arranged at an angle to one another. The elements, which form the support structure 23, are able in this way to support themselves effectively on the inner surface of the stator housing 5, so that the stator lining 20 does in no way also rotate during operation, but always remains stationary.

[0080] FIG. 5 shows a different exemplary embodiment of a stator lining 20 according to the invention.

[0081] Here, the stator lining 20 again also comprises a sleeve 21 made of solid material, which holds the fluid to be pumped in the vicinity of the screw in a pressure-tight manner. On its outer periphery, this sleeve also supports itself via a support structure 23, which forms macroscopic cavities 25 and supports itself on the stator housing 5.

[0082] It is the case here that the support structure 23 consists of support cells, which are preferably self-contained in their peripheral direction. Here, the cavity 25 in each case also opens out towards the stator housing. It can be seen well on the basis of FIG. 5 that the clear cross sectional surface of the cavity 25, which is enclosed by such a support cell, decreases in the radially outward direction. Viewed in the radially outward direction, the cross sectional surface thus forms an undercut at least in a sectional plane, but mostly all around beyond it.

[0083] FIG. 6 clarifies an example case, in which the degree of the inclination, which influences the local spring effect of the support structure 23, of the wall, which forms the support structure (23), is used as design means. In contrast to the inner pressure component, which is directed radially to the outside and which is illustrated here by means of the arrows P (already subjected to the resolution of forces), the wall sections of the tube section 26, which can be seen here, are inclined by the angle alpha. They are thus not only loaded by means of compressive forces but also experience a bending moment. The larger the radial inner pressure component and the larger the angle alpha, the stronger the tendency of the bending moment generated thereby to rotate the wall clockwise (on the top side of the shown cut-out) or counter-clockwise (on the bottom side of the shown cut-out). Due to such a rotation, the wall section tends to deflect and thus behaves in a softer, more resilient mannerwherein the resilience is larger, the larger the angle alpha.

[0084] Regardless of the claims established so far, but also in combination therewith and/or with other features of this specification, protection is also claimed for an eccentric screw pump having a rotor forming a screw conveyor and a stator forming a screw flight, in which the rotator revolves during conveying operation, wherein the stator comprises a (one- or multi-part) stator housing 5, in which a stator lining 20 is located, which reproduces the screw flight, wherein the stator lining is a sleeve made of solid material, which, on its outer periphery, supports itself on the stator housing via a support structure, which forms macroscopic cavities.

[0085] Regardless of the claims established so far, but also in combination therewith and/or with other features of this specification, protection is also claimed for an eccentric screw pump having a rotor forming a screw conveyor and a stator forming a screw flight, in which the rotor revolves during conveying operation, wherein the stator comprises a (one- or multi-part) stator housing, in which a stator lining is located, which reproduces the screw flight, wherein the stator lining is a sleeve made of solid material, which, on its outer periphery, supports itself (essentially or completely) only via its start and end flanges on the stator housing (or is completely self-supporting and thus stator housing-free).

[0086] It should likewise be noted very generally that the plastic materials, which are preferably used, are ABS, PE or HDPE, PVC, nylon and polyester, respectively, as well as PP and PET or also PTFE.

[0087] It is a very attractive option to provide the stator lining with integrated cooling or heating ducts. Not only the frictional heat developing during operation can be dissipated highly effectively in this way. In contrast, a temperature-guided contour adaptation control is optionally also possible. Heating or cooling can thus be performed systematically, in order to influence the preloading between screw and sleeve as a whole or locally.

[0088] The invention further relates to a method for producing the stator of such an eccentric screw pump, as it is discussed here.

[0089] Protection is also claimed for a method for producing a stator lining (20) reproducing a screw flight, preferably having one or several features, which claims 1 to 11 disclose for the nature of the stator lining, for an eccentric screw pump 1, characterized in that a sleeve 21 is primarily shaped by means of additive material application (preferably in the radial direction, progressing from the inside to the outside), which reproduces the screw flight and the outer peripheral surface 22 of which merges into support cells forming cavities 25, which are preferably likewise originally shaped by means of additive material application.

[0090] Protection is furthermore also claimed for a method for producing an eccentric screw pump having such a stator lining.

[0091] It is further advantageous for one of the above-described and/or claimed eccentric screw pumps that the wall thickness of the sleeve 21 is essentially constant.

[0092] It is further advantageous for one of the above-described and/or claimed eccentric screw pumps that the topography of the outer peripheral surface 22 of the sleeve 21 shows the screw-shaped course in its interior.

[0093] It is further advantageous for one of the above-described and/or claimed eccentric screw pumps that the wall thickness of the support cells increases in the direction of the conveying direction.

[0094] It is further advantageous for one of the above-described and/or claimed eccentric screw pumps that, in the cross section, the walls of the support cells have a central line running from the inside to the outside, which is curved.

[0095] It is further advantageous for one of the above-described and/or claimed eccentric screw pumps that, in the cross section, the walls of the support cells have a central line running from the inside to the outside, which is straight and draws an angle with the local tangent of the sleeve 21.

[0096] It is further advantageous for one of the above-described and/or claimed eccentric screw pumps that at least the sleeve 21, preferably the sleeve 21 and the support structure 23, consists of a non-vulcanized material, preferably a plastic, which can be processed by means of additive manufacture, ideally a polyamide PA or alternatively a metal material, which can be processed by means of additive manufacture.

[0097] It is further advantageous for one of the above-described and/or claimed eccentric screw pumps that the sleeve 21 consists of a plastic, which is preferably filled with metal, ceramic or MOS2.

[0098] It is further advantageous for one of the above-described and/or claimed eccentric screw pumps that the sleeve 21preferably viewed in the radial directionis constructed of several different material layers.

[0099] It is further advantageous for one of the above-described and/or claimed eccentric screw pumps that with the radially outward ends of its support structure 23, the stator lining 20 defines an imaginary enveloping surface with polygonal, preferably octagonal cross section.

[0100] It is further advantageous for one of the above-described and/or claimed eccentric screw pumps that, preferably fastened to its outer peripheral surface 22, the sleeve 21 has a sensor, preferably for monitoring the contour guidance and/or the temperature.