Eccentric screw pump with easy-to-manufacture stator lining

Abstract

An eccentric screw pump comprising a rotor constituting a conveyor screw and a stator constituting screw flights, the rotor rotating during a conveying movement within the stator, the stator comprising a stator housing (5). Within the stator housing there is a stator lining which describes the screw flights. The stator lining is a sleeve. The sleeve is supported on its outer periphery in the stator housing via a support structure. The support structure constitutes a cavity. Depending on the joining position of the support structure to the sleeve, the support structure is shaped and dimensioned such that the support effect it provides is adapted to the local needs of the sleeve.

Description

Technical Field

[0001] The present invention relates to an eccentric screw pump comprising a specially designed stator according to the superordinate concept of claim 1, and a corresponding stator attached to the eccentric screw pump for the purpose of repairing or modernizing the eccentric screw pump. The present invention also relates to a stator lining for an eccentric screw pump according to the superordinate concept of claim 12, and a method for manufacturing a stator lining depicting a screw flight (Schneckengang) for an eccentric screw pump according to the superordinate concept of claim 13.

Background Art

[0002] Eccentric screw pumps have a wide variety of applications.

[0003] Eccentric screw pumps are a particularly preferred means when it is necessary to pump highly viscous fluids having viscosities and / or solids contents that are difficult to control. For this reason, eccentric screw pumps can also be used precisely in the development of mineral resources.

[0004] In this case, eccentric screw pumps are optimal for pumping fluids containing abrasive components. This is because the pumping effect of the eccentric screw pump is based on the principle of a moving conveying chamber. This moving conveying chamber is formed between a central conveyor screw and a double-pitch screw flight formed by a stator lining.

[0005] It is inevitable that a stator lining made of a material softer than a metal screw will wear over time.

[0006] In most cases, stator linings have been made of vulcanized materials such as plastic, or, to use a more general term, rubber. Materials referred to herein as “rubber,” or materials having rubber-like properties, have the advantage of providing very good seals. This is because the screw contact zone can continuously displace the contacted stator material by a magnitude greater than the microscopic, i.e., by a very small amount. This is an instantaneous displacement because the stator material returns to its original shape as soon as the local contact with the screw ends again (except for the minimum wear that is necessary each cycle).

[0007] Stator linings are tightly fitted to the geometric shape of the screw running through them. That is, the stator lining has the highly complex winding geometry of the multi-winding screw flight at its center. Therefore, to this day, stator linings are almost always cast or injection molded using a screw-shaped mold core. The mold core holds a clear (lichte) opening in the screw flight, which later houses the screw. After the injection molding or casting process is complete, the still-unsintered stator lining formed by casting / injection molding is vulcanized. The copying process is also still used, as harder materials are available.

[0008] To this day, this type of "copy turning" still possesses the characteristics of refined "craftsmanship" rather than being a fully automated process within the framework of industrial series production.

[0009] Harder materials referred to as "rubber" in this specification are not sufficiently resistant to pumped fluids in all applications. Furthermore, their manufacture requires considerable effort due to the mandatory vulcanization process.

[0010] Therefore, there is a growing need to construct well-functioning stator linings to further significantly streamline production. These stator linings can be made from alternative materials that do not rely on rubber-like materials and are significantly harder or significantly less elastic, without exhibiting rubber-elastic behavior. To provide a seal on stators made of such harder or less elastic materials that is comparable to that of a mobile conveying chamber acting to pump, the stator lining geometry must be guaranteed to be highly precise. Furthermore, the screw flights must be designed to be as close as possible to their geometrically optimal shape. Generous tolerances that can be easily compensated for as needed by the screw momentarily "displacing" (verdrangt) the rubber-like stator material slightly more or slightly less are not feasible.

[0011] For this reason, the manufacturing effort required to produce stator linings from alternative materials using today's known methods remains quite high, even considering the fact that the time-consuming copying process can be at least eliminated. This is because screw flights must be manufactured with extreme precision by machining, grinding, and / or erosion, or by first manufacturing complex injection molds. [Overview of the project] [Problems that the invention aims to solve]

[0012] Therefore, the object of the present invention is to provide an eccentric screw pump equipped with a stator lining that is easier to manufacture, uses a harder stator material, and has improved efficiency. [Means for solving the problem]

[0013] The first main claim provides a solution to this problem.

[0014] The solution is an eccentric screw pump comprising a rotor that constitutes a conveyor screw and a stator that constitutes a screw flight. The rotor rotates within the stator during conveying. In this case, the stator includes a stator housing made of a single or multi-part component. Within the stator housing is a stator lining that forms the screw flight. Within the screw flight, the rotor rotates and acts to pump. The stator housing can be divided. Therefore, optionally, an eccentric screw pump can also be constructed from multiple stator housing components connected in series in the conveying direction, along with the associated stator lining components. This generally applies to what is described below.

[0015] The central or essential component of the stator lining is a sleeve made of solid material, i.e., having a continuous, and therefore sealing, sleeve wall. This sleeve is supported in the stator housing via a support structure on its outer circumference. The support structure constitutes a macroscopic cavity and typically constitutes at least substantially the rest of the stator lining.

[0016] According to the present invention, the proposed solution is characterized in that the support structure is formed and dimensionally determined according to the position of the support structure's connection to the sleeve, so that the support effect provided by the support structure is adapted to the local needs of the sleeve.

[0017] The important point here is that the sleeve is usually very thin-walled, except for the start and end flanges. Therefore, the sleeve reversibly and elastically deflects by a certain amount under localized pressure that acts periodically as the screw contacts "mesh" or "squeeze" along its inner surface, thereby creating the required sealing pressure.

[0018] Here, according to the present invention, an optimized support structure comes into play. The support structure is formed according to the position of its connection to the sleeve so that the support effect provided by the support structure is suited to the local needs of the sleeve.

[0019] In particular, the effects of the present invention can be achieved by using the following design means.

[0020] It is possible to use wall thicknesses that vary depending on the location.

[0021] Therefore, for example, an increased thickness, i.e., the wall thickness or bearing capacity of the support structure, can be applied in the conveying direction, i.e., in the direction of the central longitudinal axis of the straight line around which the screw flight, usually composed of sleeves, winds. This takes into account the high pressure load generated at the outlet of the screw pump.

[0022] Additionally or alternatively, a thicker wall thickness can be provided when viewed circumferentially. For example, this may be necessary when the local radial gap between the sleeve and the stator housing, which should be bridged by the support, is larger and the support must extend beyond that gap.

[0023] Additionally or alternatively, the inclination of the walls constituting the support structure can be used as a design tool to influence the local spring effect of the support structure. This refers to the inclination of the walls relative to radials that protrude outward at a right angle from the stator centerline around which the screw flights, formed by the sleeves, wrap. Walls in this manner behave "softer" or "more flexible" to compressive stresses applied to them by the sleeves, which also generate bending stresses in the walls, than walls subjected to substantially only compressive stresses.

[0024] Alternatively or simultaneously, the local density of the support structure can be varied so that the support effect provided conforms to the local conditions. For example, it is conceivable to locally vary the cell density or honeycomb density using the options of the cellular or honeycomb configuration of the support structure, which will be described in more detail later. This can be done, for example, by further dividing even the free space, which is usually left free and surrounded by cells of this type, especially in the cells under load, into smaller cells, and the smaller cells can be made to be inscribed in the (larger) cells.

[0025] The support is typically carried out over the entire 360-degree circumference or substantially over the entire circumference by a correspondingly designed support structure. This does not mean that the support structure must not be interrupted in the circumferential direction.

[0026] Thus, according to the present invention, not only is a support structure provided that has only secondary or tertiary relevance in terms of design, but this support structure is designed in some way to hold the sleeve constituting the screw flight, at least temporarily, in a predetermined position. Therefore, it may be necessary to still provide a coating of elastomeric material on the running surface on the inner surface of the sleeve.

[0027] This design allows for a reduction in the amount of material required to manufacture the stator lining.

[0028] Furthermore, it is very easy to use other materials that do not exhibit rubber elasticity, at least in part, in the sense of vulcanized materials, and it is possible to manufacture them for the first time with reasonable effort, so that their use actually makes sense for the first time. The main reason for this is the fact that the supporting effect can be very sensitively controlled via the geometry, size, and spacing of the supporting wall and the cavities that are thereby partially or completely delimited. If it is configured as a thin wall and supported as required, it is thus possible to impart the necessary elasticity in operation even to a sleeve made of a rather hard or low-elastic plastic material, or even to a metal sleeve. In this case, the latter is usually very thin-walled and, advantageously, has a wall thickness corresponding to at most four or three times the largest solid particles pumped by the pump. In absolute terms, a wall thickness of 0.3 mm to 2.0 mm, and more preferably 0.4 mm to 0.7 mm, is a preferred selection method for the wall thickness of such a metal sleeve. A metallic support structure (usually in a filigree shape) can be formed on the outer periphery of such a metal sleeve, ideally by 3D printing. Alternatively, a plastic support structure can equally well be formed on the metal sleeve.

[0029] The cavities formed by the support structure are not only macroscopic and are merely the cavities formed from time to time in the minimum cavities of the porous material or other solid materials. The cavities preferably have a geometrically completely defined shape, except for a more or less large microscopic surface roughness, and generally form a non-random pattern as a whole. Optionally, the cavities can be completely or partially filled with another material, such as the material used for damping.

[0030] Possible preferred designs of the present invention It is particularly advantageous for the sleeve to have thin walls, not only as an independent main claim but also as a further development of an already established claim. In this case, the wall thickness of the sleeve is preferably 1 / 6 or less, more preferably 1 / 10 or less, and ideally 1 / 12 or less of the average inner radius (mittleren Innenradius) of the stator housing. Such a thin sleeve, without support, does not provide sufficiently large resistance to the rotor screw and behaves almost like a flexible hose. By narrowing and supporting it, such a sleeve can be given the desired flexible behavior. This is attractive when the sleeve itself is made of a material that is too rigid to be used as a stator lining for a screw spindle pump.

[0031] The fact that the sleeve wall thickness is substantially constant is particularly advantageous.

[0032] In other cases, it may be advantageous to proceed in a different manner. For this reason, separate protection is claimed. However, protection that further develops an already established claim is also claimed, in which case the sleeve is thin-walled. Nevertheless, the wall thickness of the sleeve varies locally, preferably up to + / -30%, more preferably up to + / -20%, and ideally up to + / -12.5%. Such a design is useful to contribute to improved sealing in areas of the screw that are actually meshing with the sleeve, in areas of higher pressure, such as the end of the screw flight opposite the suction side.

[0033] In some applications, it is particularly advantageous to manufacture the support structure from carrier cells. Each carrier cell defines or encloses a cavity. The clear cross-section of the cavity enclosed by such carrier cells preferably decreases in the radially outward direction. This can provide the sleeve with special elastic support. This is particularly applicable, though not exclusively, when the carrier cells are filled with damping material, and the damping material is thus held particularly well in the carrier cells that open radially outward.

[0034] It has proven particularly advantageous to implement the support structure using carrier cells that constitute a honeycomb, preferably having a hexagonal base surface. Such carrier cells that make up the honeycomb achieve particularly uniform support because the honeycomb forms an endless and seamless pattern in which it interlocks with each other. In addition, the honeycomb has the advantage of being able to absorb pressure only as needed. Instead, the honeycomb can also provide support against longitudinal and circumferential tensile forces that tend to expand the sleeve. The seamless honeycomb network behaves like a belt or a flexible belt.

[0035] Preferably, the wall thickness of the carrier cell corresponds to the average wall thickness of the sleeve (completely or at least + / - 15%, better at least + / - 7.5%). In this way, the accumulation of harmful substances is avoided. Even under the unavoidable effects of heating during operation, the stator lining can expand uniformly. Even overloads that may be caused by localized tension or excessive preload on the screw due to heat are avoided.

[0036] In some cases, it is particularly advantageous for the wall thickness of the carrier cell to increase in the radially outward direction. This ensures particularly high buckling resistance when it is necessary to fill a relatively large gap between the local outer surface of the sleeve and the stator housing.

[0037] It has been proven particularly advantageous to increase the wall thickness of the carrier cell in the direction of transport, because the pressure increases significantly in the region from the suction side to the opposite stator end due to the pumping effect. Stronger radial support for the sleeve, in particular, helps maintain the necessary pre-tension between the sleeve and the screw that locally engages along it, even in this higher-load region.

[0038] In some cases, it is particularly advantageous for the walls of a carrier cell to have a centerline that curves partially or entirely in cross-section, running from the inside to the outside. Such curved walls exhibit a stronger spring effect or flexibility in the radial direction, or from the inside to the outside, than straight walls in this direction. This can be used purposefully to adjust the locally required spring effect from the structural side.

[0039] Alternatively, it has been proven useful for the walls of the carrier cells to have a centerline running from the inside to the outside in cross-section, where this centerline is straight and at an angle to the local tangent of the sleeve. This also allows for a stronger spring effect in the radial direction or from the inside to the outside of the individual carrier cells. This can also be used to adjust the locally required spring effect from the structural side.

[0040] Particularly advantageous is that at least the sleeve, preferably the sleeve and support structure, are made of a non-vulcanized material. Ideally, this is a plastic that can be processed using additive manufacturing, ideally polyamide PA. Alternatively, depending on the circumstances, metallic materials that can be processed using additive manufacturing may also be considered.

[0041] From the standpoint of wear suppression and / or lubrication, the use of plastics filled with solid particles, such as metal particles (including, in some cases, bearing metal particles such as bearing bronze) or ceramic particles, may be attractive depending on the application. Alternatively, plastics filled with solid lubricant particles, such as MOS2 particles, may also be attractive.

[0042] Optionally, the sleeve is preferably composed of multiple different material layers viewed radially. For example, the outermost layer on the inner surface of the sleeve can be an abrasion protection layer, followed inwards by, for example, an adhesion promoting layer.

[0043] If the inner surface of the stator lining has a polygonal cross-section corresponding to the cross-section of the surrounding surface of the stator lining, it is particularly simple and reliable to secure the stator lining within the stator pipe to prevent twisting. Alternatively, screwing the stator to an adjacent section can also be considered.

[0044] Particularly advantageous is that the lubricant is supplied from the outer surface to the inner surface of the sleeve, ideally by diffusion or pressurization through the sleeve wall. This is especially true for sleeves made of plastic manufactured using 3D printing. Using 3D printing or additive manufacturing in particular allows for very sensitive control of the local porosity of the sleeve. It is possible to create pores in the sleeve wall at points or areas to be lubricated. These pores are sized such that the lubricant is pushed through the pores from the outside to the inside, without a large amount of fluid to be pumped being released through the pores from the inside to the outside. The latter is thought to be due to the pore size and / or the reverse pressure that introduces the lubricant into the sleeve from the outside.

[0045] A particularly preferred embodiment comprises a sleeve and, preferably, a sensor mounted on the outer surface of the sleeve. The sensor preferably monitors the local contour accuracy, deformation, and / or temperature of the sleeve. Typically, multiple such sensors are provided at different, spaced-apart positions.

[0046] It is particularly advantageous, not only as an independent main claim but also as a further development of an already established claim, that the support structure is designed to compensate for temperature, such that the screw flight, composed of the sleeve, does not narrow, or narrows only slightly, when the support structure is heated. This means that the support structure is designed not to hinder, or significantly hinder, the radially outward expansion of the sleeve caused by the temperature rise of the sleeve, despite being supported within the stator pipe. Thus, the sleeve can behave in the same way, or substantially the same way, as a pipe, which is known to be unrestricted by expansion and whose clear inner diameter increases when heated.

[0047] Independent protection is also claimed for a method described in the claims for manufacturing a stator lining 20 that paints screw flights for an eccentric screw pump. This method is characterized by: forming a sleeve by primary molding by additionally applying a material, preferably radially from the inside out; the sleeve paints screw flights; the outer surface of the sleeve is preferably integrally bonded to or integrally printed to carrier cells that constitute a cavity; the carrier cells are preferably similarly formed by primary molding by additionally applying a material.

[0048] Alternatively, the sleeve is manufactured by a conventional non-printing method by primary molding and / or formation. In this case, the aforementioned carrier cell, which can be optionally designed as described within the scope of the present invention, is printed thereon.

[0049] The sleeve can be printed in layers from multiple different materials. Preferably, the innermost radial layer uses a material that has a reduced coefficient of sliding friction with respect to steel compared to the other materials used for printing.

[0050] Optionally, it is also possible to use materials that are primarily or substantially different from the sleeve printing for all the walls that define the boundaries of the carrier cell.

[0051] Further design possibilities, operating modes, and advantages will become apparent from the following description of embodiments based on the drawings. [Brief explanation of the drawing]

[0052] [Figure 1] This is a diagram illustrating the basic structure of an eccentric screw pump. [Figure 2] This is a perspective view of the stator lining according to the first embodiment of the present invention. [Figure 3] This is a cross-sectional view through the stator lining shown in Figure 2, in a plane perpendicular to the central longitudinal axis around which the screw flight wraps. Note that, in reality, when looking inside the sleeve 21, no support structure 23 is visible on its flat inner surface. In this case, Figure 3 depicts the sleeve as transparent simply for clarity. [Figure 4] Figure 2 shows a longitudinal cross-sectional view through the stator lining. [Figure 5] This is a cross-sectional view of a further stator lining according to the second embodiment. [Figure 6] This is a cross-sectional view of the stator lining to explain why the inclined walls of the support structure make the support characteristics of the support structure softer. [Figure 7] This figure shows a further embodiment in which the wall thickness of the honeycomb that constitutes the support structure increases from the suction side to the pressure side. [Modes for carrying out the invention]

[0053] overview Figure 1 shows the eccentric screw pump 1, which forms the basis of the present invention, in its entirety.

[0054] The main components of this eccentric screw pump 1 are the suction housing 11 and the pump section 12 that is in fluid communication with it.

[0055] The suction housing 11 has an inlet 13 for the medium to be transported.

[0056] The transported medium is discharged through an outlet 14 located at the end of the pump section 12.

[0057] Preferably, a block structure is selected, even if it is not essential from a patent standpoint. The pump motor 15 is then flanged to the suction housing 11. The pump motor 15 typically drives the rotor, which is described in more detail below, via the cardanic powertrain 16.

[0058] The pump section consists of a stator 3, which has a rotating rotor inside.

[0059] The eccentric screw 2 constitutes the rotor. The eccentric screw 2 can be classified as a round screw (Rundgewindeschraube). Compared to a normal screw, the eccentric screw has a larger pitch, a larger thread depth, and a smaller core diameter. The stator 3 consists of a stator lining 20 and a stator pipe 5 that receives the stator lining inside. The stator lining is shaped to complement the rotor. The stator lining constitutes a "screw flight (Schneckengang)". The screw flight is equipped with twice the pitch length and additional threads. This arrangement creates a series of transport chambers 17 between the stationary stator 3 and the rotor 2, which rotates within it with an eccentric effect and is also called a screw due to its profiling. The transport chambers 17 move continuously and without changing shape from their inlet side, which is formed by a trumpet 18 in the suction housing 11, to their outlet side, i.e., the outlet 14. This pressurizes and transports the medium present in the transport chambers 17.

[0060] The rotational speed of the rotor allows for control of the movement speed of the conveying chamber 17 toward the outlet, and consequently, the theoretical conveying volume of the pump.

[0061] In addition to the number of stator windings, the tightness of the contact lines between the rotor and stator affects the pump's suction capacity and the achievable conveying pressure.

[0062] Structure according to the present invention Figure 2 shows a side perspective view of the entire stator lining 20 according to the first embodiment. For better understanding, it is recommended to view Figure 2 alongside Figure 3. The latter shows a vertical cross-section passing through the stator lining shown in Figure 2.

[0063] The sleeve 21, which forms the central part of the stator lining 20, is clearly visible in Figure 3. The sleeve 21 has a shape on its inner surface 24 that represents a screw flight. The screw flight is essentially fitted to a screw 2 (not shown here) that rotates within this screw flight 24 to produce the typical pumping effect of an eccentric screw pump. See also Figure 1 and related descriptions.

[0064] As can be clearly seen in Figure 2, the spiral-shaped path that the sleeve 21 has inside can be recognized from the topography of the outer surface 22 of the sleeve 21.

[0065] Furthermore, as can be clearly seen from a comparison between Figure 2 and Figure 3, the support structure 23 that constitutes the macroscopic cavity 25 is adjacent to the outer circumference of the sleeve 21 and is usually connected integrally. In this case, the support structure is composed of ring or pipe sections 26. Particularly advantageous, each ring or pipe section not only has a first wall section along the central longitudinal axis around which the screw flight, formed by the sleeve, winds, and a second wall section perpendicular thereto, but each ring or pipe section also has a further, not merely trivial, wall section running diagonally with respect to the aforementioned central longitudinal axis.

[0066] Particularly advantageous in this case, the pipe sections used in this embodiment are in the shape of a hexagonal honeycomb. These are connected to each other directly or share walls with adjacent ones. Preferably, each of these honeycomb rings 26 is equipped with a hexagonal cross-section along its entire length in the radially outward direction, surrounding a macroscopic cavity 25 at its center, as already briefly described. Each of these honeycomb rings has its radially outward open side in contact with the inner surface of the stator pipe, as shown in Figure 3.

[0067] In the embodiments shown herein, each cavity 25 is completely separated from adjacent cavities by a ring or pipe portion that divides it.

[0068] Based on this, it is easy to understand that each of the honeycomb-shaped rings 26 functions like a support column, thereby constituting the support structure 23.

[0069] Preferably, the support force, or spring effect, of each honeycomb ring 26 can be adjusted very precisely by correspondingly determining the wall thickness. The thicker the wall, the greater the support effect. In this case, the volume of the cavity surrounded by the support structure becomes smaller. In all of this, it is interesting that the support structure 23, or its honeycomb rings, or its cavity 25, has a mathematically descriptive, and therefore defined, shape. In this way, not only can the support effect be calculated very appropriately, but the stator lining 20 can also be manufactured additively, for example, by 3D printing.

[0070] The degree to which the support structure 23 concentrates its support on the sleeve 21 naturally depends on the individual case. The indicator for this is the load-bearing capacity value TW. The load-bearing capacity value TW indicates the percentage to which the virtual outer surface surrounding the outer circumference of the stator lining is supported by the stator housing. A useful load-bearing capacity value TW is 20% to 80%, and even better, 30% to 75%.

[0071] As you can see, the wall thickness of the sleeve, or the average wall thickness W1, W2, Wn, is minimal. In this embodiment, the wall thickness of the thin-walled sleeve 21 is limited to less than one-tenth of the radius that forms the clear opening of the stator housing.

[0072] In many cases, as shown in Figure 3, the wall thickness of the sleeve 21 is constant or substantially constant. In other cases, it is useful to locally vary the wall thickness of the sleeve. In most cases, the maximum variation should not exceed plus or minus 30% of the average value.

[0073] As can be seen, the wall thickness of the element can form a support structure 23 that corresponds (completely or substantially) to the wall thickness of the sleeve 21, for example, a honeycomb ring 26. Here, it may be particularly interesting to increase the wall thickness of the ring or pipe portion 26, or any other element that makes up the support structure 23 in its place, in the radially outward direction, in order to make the element particularly resistant to buckling. This is because the bending moment acting on the element naturally increases radially from the inside to the outside.

[0074] Furthermore, as can be clearly seen from Figure 3, the stator housing 5 has a clear cross-section on the inside that is polygonal, ideally octagonal. In other words, the inner surface of the stator housing 5 running in the circumferential direction is composed of numerous flat surface strips 27 arranged at angles to one another. In this way, the elements constituting the support structure 23 can be effectively supported on the inner surface of the stator housing 5. As a result, the stator lining 20 does not rotate at all during operation and remains stationary at all times.

[0075] Figure 5 shows another embodiment of the stator lining 20 according to the present invention.

[0076] Here again, the stator lining 20 includes a sleeve 21 made of solid material. The sleeve 21 airtightly holds the fluid pumped by the pump near the screw. This sleeve is also supported on its outer circumference via a support structure 23. The support structure 23 constitutes a macroscopic cavity 25, which is itself supported in the stator housing 5.

[0077] Here, the support structure 23 preferably consists of carrier cells that are closed in the circumferential direction. Here again, the cavities 25 each open toward the stator housing. As can be clearly seen from Figure 5, the clear cross-section of the cavities 25 surrounded by such carrier cells decreases in the radially outward direction. Thus, the cross-section constitutes an undercut in at least one cutting plane, but usually further constitutes an undercut all around in the radially outward direction.

[0078] Figure 6 shows an example of using the inclination of the walls constituting the support structure 23, which affects the local spring effect of the support structure 23, as a design tool. Here, compared to the radially outward internal pressure component represented by arrow P (which has already undergone force decomposition), the wall portion of the pipe section 26 shown here is inclined by an angle alpha. Therefore, this wall portion is subjected not only to compressive loads but also to bending moments. The larger the radial internal pressure component and the larger the angle alpha, the stronger the bending moment that results tends to rotate the wall clockwise (upper side of the cross-section shown) or counterclockwise (lower side of the cross-section shown). Such rotation causes the wall portion to flex and therefore behave more softly and easily. In other words, the larger the angle alpha, the greater the flexibility.

[0079] General matters Independently of, but also in combination with, and / or in combination with, other features herein, protection is also claimed for an eccentric screw pump comprising a rotor constituting a conveyor screw and a stator constituting a screw flight. In this case, the rotor rotates within the stator during conveying operation. The stator includes a stator housing 5 (made of one or more parts). Within the stator housing is a stator lining 20 that forms the screw flight. The stator lining is a sleeve made of solid material, which is supported in the stator housing via a support structure that forms a macroscopic cavity around its outer circumference.

[0080] Independently, but also in combination with, and / or in combination with other features herein, protection is also claimed for an eccentric screw pump comprising a rotor constituting a conveyor screw and a stator constituting a screw flight. In this case, the rotor rotates within the stator during conveying operation. The stator includes a stator housing (made of one or more parts). Within the stator housing is a stator lining that forms the screw flight. The stator lining is a sleeve made of solid material, which is supported (substantially or entirely) by the stator housing on its outer circumference only through its start and end flanges (or is completely self-supporting and therefore absent from the stator housing).

[0081] It should also be noted that, quite commonly, preferred plastic materials include ABS, PE, or HDPE, PVC, nylon, and polyester, as well as PP and PET or PTFE.

[0082] A very attractive option is to provide a stator lining with integrated cooling or heating channels. This not only allows for very effective dissipation of the frictional heat generated during operation, but also, optionally, allows for temperature-controlled contour adjustment. Thus, targeted heating or cooling can be performed to affect the preload between the screw and sleeve, either overall or locally.

[0083] The present invention further relates to a method for manufacturing a stator for an eccentric screw pump, such as the one in question.

[0084] Protection is also claimed for a method of manufacturing a stator lining 20 that forms screw flights, preferably having one or more of the features disclosed in claims 1 to 11 regarding the properties of the stator lining for an eccentric screw pump 1. This method is characterized by: forming a sleeve 21 by primary molding by additionally applying material (preferably radially from the inside to the outside); the sleeve 21 forms screw flights; the outer circumferential surface 22 of the sleeve 21 is coupled to carrier cells constituting a cavity 25, the carrier cells are preferably formed by primary molding, similarly by additionally applying material.

[0085] Furthermore, protection is also sought for methods of manufacturing eccentric screw pumps having such stator linings.

[0086] Furthermore, the fact that the wall thickness of the sleeve 21 is substantially constant is advantageous for one of the aforementioned and / or claimed eccentric screw pumps.

[0087] Furthermore, the topography of the outer circumferential surface 22 of the sleeve 21 showing a helical path within it is advantageous for one of the above-mentioned and / or claimed eccentric screw pumps.

[0088] Furthermore, an increase in the carrier cell wall thickness in the direction of transport is advantageous for one of the aforementioned and / or claimed eccentric screw pumps.

[0089] Furthermore, the fact that the walls of the carrier cell have a centerline running from the inside to the outside in cross-section, and that this centerline is curved, is advantageous for one of the aforementioned and / or claimed eccentric screw pumps.

[0090] Furthermore, it is advantageous for one of the above-mentioned and / or claimed eccentric screw pumps that the walls of the carrier cell have a centerline running from the inside to the outside in cross-section, and that this centerline is straight and at an angle with the local tangent to the sleeve 21.

[0091] Furthermore, it is advantageous for one of the above-mentioned and / or claimed eccentric screw pumps that at least the sleeve 21, preferably the sleeve 21 and the support structure 23, are made of a non-vulcanized material, preferably a plastic that can be processed using additive manufacturing, ideally polyamide PA, or alternatively a metallic material that can be processed using additive manufacturing.

[0092] It is advantageous for one of the above-mentioned and / or claimed eccentric screw pumps that the sleeve 21 preferably consists of metal, ceramic, or MOS2-filled plastic.

[0093] It is advantageous for one of the above-mentioned and / or claimed eccentric screw pumps that the sleeve 21 is preferably composed of multiple different material layers in a radial view.

[0094] It is advantageous for one of the above-mentioned and / or claimed eccentric screw pumps that the stator lining 20, together with the radially outer end of its support structure 23, defines a virtual encircling surface having a polygonal, preferably octagonal, cross-section.

[0095] It is advantageous for one of the above-mentioned and / or claimed eccentric screw pumps that the sleeve 21 preferably comprises sensors mounted on its outer circumferential surface 22 for monitoring contour guidance and / or temperature. [Explanation of Symbols]

[0096] 1. Eccentric screw pump 2. Eccentric screw, or simply screw. 3 stata 4 None 5. Stator pipe or stator housing 6 to 10 None 11 Suction Housing 12 Pump section 13 Entrance 14 Exit 15 Pump motor 16 Powertrain 17 Conveyor Chamber 18 Trumpet 19 None 20 Stator Lining 21 sleeves 22. Outer surface of the sleeve (which has a spiral-shaped path) 23 Support structure 24 Inside of the sleeve 25 Cavity 26 Usually a honeycomb-shaped ring, otherwise a ring or pipe section. 27 Flat surface strips inside the stator housing L - Center longitudinal axis TW Load Capacity W1, W2, Wn

Claims

1. An eccentric screw pump (1) comprising a rotor constituting a conveyor screw and a stator (3) constituting a screw flight, wherein the rotor rotates within the stator during conveying operation, and the stator (3) includes a stator housing (5) whose inner surface is composed of a number of flat surface strips (27) arranged at angles to each other in a cross section perpendicular to the central longitudinal axis, and a stator lining (20) forming the screw flight is present within the stator housing, the stator lining (20) being a sleeve (21), the sleeve being supported in the stator housing (5) via a support structure (23) on its outer circumference, the support structure being formed and dimensionally determined according to the coupling position of the support structure to the sleeve (21) such that the support effect provided by the support structure is suited to the local needs of the sleeve (21), The eccentric screw pump (1) is characterized in that the support structure (23) is composed of rings (26) and comprises a first wall portion along the central longitudinal axis around which the screw flight is wound and a second wall portion perpendicular thereto, and each ring comprises a further wall portion running diagonally with respect to the central longitudinal axis.

2. The eccentric screw pump (1) according to claim 1, characterized in that the support effect is adapted to the local needs of the sleeve (21) by providing an increasing wall thickness in the support structure (23) along the direction of the leak flow, or additionally or alternatively, by providing a thicker wall thickness when viewed along the circumferential direction, or additionally or alternatively, by using the inclination of the walls constituting the support structure (23) as a design means to adapt the support effect to the local needs of the sleeve (21), or additionally or alternatively, by changing the local density of the support structure (23) so that the given support effect is adapted to local conditions.

3. An eccentric screw pump (1) according to claim 1 or 2, comprising a rotor constituting a conveyor screw and a stator (3) constituting a screw flight, wherein the rotor rotates within the stator during conveying operation, the stator (3) includes a stator housing (5) (made of one or more parts), a stator lining (20) forming the screw flight is present within the stator housing, the stator lining (20) is a sleeve (21) made of a solid material, the sleeve is supported in the stator housing (5) via a support structure (23) on its outer circumference, and the support structure constitutes a cavity (25), wherein the sleeve (21) is thin-walled.

4. An eccentric screw pump (1) according to claim 1 or 2, comprising a rotor constituting a conveyor screw and a stator (3) constituting a screw flight, wherein the rotor rotates within the stator during conveying operation, the stator (3) includes a stator housing (5) (made of one or more parts), a stator lining (20) forming the screw flight is present within the stator housing, the stator lining (20) is a sleeve (21) made of solid material, the sleeve is supported in the stator housing (5) via a support structure (23) on its outer circumference, and the support structure constitutes a (macroscopic) cavity (25), wherein the sleeve (21) has a thin wall, and the wall thickness of the sleeve (21) varies locally.

5. An eccentric screw pump (1) according to claim 1 or 2, comprising a rotor constituting a conveyor screw and a stator (3) constituting a screw flight, wherein the rotor rotates within the stator during conveying operation, the stator (3) includes a stator housing (5) (made of one or more parts), a stator lining (20) forming the screw flight is present within the stator housing, the stator lining (20) is a sleeve (21) made of a solid material, and the sleeve has a support structure (23) on its outer circumference. An eccentric screw pump (1) is supported in the stator housing (5) via a support structure (23) and the support structure constitutes a (macroscopic) cavity (25), wherein the support structure (23) consists of carrier cells, each of the carrier cells defines or surrounds the cavity (25), the cavity (25) surrounded by the carrier cells opens toward the stator housing (25), and the clear cross-section of the cavity (25) surrounded by such carrier cells decreases in the radially outward direction.

6. The eccentric screw pump (1) according to claim 5, wherein the carrier cell constitutes a honeycomb or other pipe portion, and the honeycomb or other pipe portion comprises a wall structure having an elastic effect and / or damping effect.

7. The eccentric screw pump (1) according to claim 5, characterized in that the wall thickness of the carrier cell corresponds to the average wall thickness of the sleeve (21).

8. The eccentric screw pump (1) according to claim 7, wherein the inner circumferential surface of the stator housing (20) has a polygonal cross-section, and the polygonal cross-section corresponds to the cross-section of the surrounding surface of the stator lining (20).

9. The eccentric screw pump (1) according to claim 1 or 2, characterized in that the lubricant is supplied from the outer circumferential surface (22) to the inner circumferential surface (24) of the sleeve (21), normally extending to the area of ​​the inner lubricant pocket.

10. The eccentric screw pump (1) according to claim 1 or 2, wherein the sleeve (21) is provided with a sleeve wall region in which the porosity is increased at least locally relative to the other portion of the stator lining (20), so as to allow lubricant to be pumped through the relevant portion to the inner surface (24) of the sleeve (21) without the fluid pumped by the pump in the opposite direction being able to penetrate to the outside through the porous inner wall region.

11. An eccentric screw pump (1) according to claim 1 or 2, comprising a rotor constituting a conveyor screw and a stator (3) constituting a screw flight, wherein the rotor rotates within the stator during conveying operation, the stator (3) includes a stator housing (5) (made of one or more parts), and within the stator housing there exists a stator lining (20) that forms the screw flight, the stator lining (20) is a sleeve (21) made of a solid material, the sleeve is supported in the stator housing (5) via a support structure (23) on its outer circumference, the support structure (23) is designed to compensate for temperature, and the screw flight formed by the sleeve (21) does not narrow, or narrows only slightly, when the support structure (23) is heated.

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