CN114341496B

CN114341496B - Stator for eccentric screw pump

Info

Publication number: CN114341496B
Application number: CN202080059862.5A
Authority: CN
Inventors: S·耶格尔; T·彼得汉斯尔
Original assignee: Arnold Jaeger Holding GmbH
Current assignee: Arnold Jaeger Holding GmbH
Priority date: 2019-07-16
Filing date: 2020-07-16
Publication date: 2023-10-13
Anticipated expiration: 2040-07-16
Also published as: WO2021009275A1; EP3767105B1; CN114341496A; PL3767105T3; EP3767105A1; ES2909699T3

Abstract

The invention relates to a stator (1) for an eccentric screw pump having a rotor, the stator (1) having an elastically flexible liner (3) comprising an outer surface (9), the liner (3) being surrounded by a rigid outer shell (2), the inner surface (4) of the liner (3) forming a double-ended, coarse-tooth thread and defining a pump cavity (5) extending in an axial direction (X) for receiving the rotor of the eccentric screw pump, the liner (3) of the stator (1) tapering in the axial direction (X), whereby the average wall thickness (W) of the liner (3) decreases continuously in the axial direction (X) starting from an end wall thickness (WE) located in the region of the suction side (7) of the stator (1) until a minimum average wall thickness (WM) is reached. According to the invention, the average wall thickness (W) of the lining (3) is increased at least in sections after reaching the minimum average wall thickness (WM), so that a widening (10) is formed in the lining (3) towards the pressure side (8) of the stator (1).

Description

Stator for eccentric screw pump

Technical Field

The invention relates to a stator for an eccentric screw pump having a rotor.

Background

The stator of the same type has a continuous and spiral (gewendelten) pump cavity formed by a liner made of elastomer, in which an eccentrically supported rotor is wound. Due to the eccentric support of the rotor, a chamber is formed between the rotor and the spiral liner during rotation of the rotor, which chamber is displaced to some extent from the suction side of the eccentric screw pump towards its pressure side, so that the medium is pushed or conveyed in the axial direction through the pump or stator.

Such a stator can be used in eccentric screw pumps, in particular for conveying media such as mortars, cements, oils, etc. In order to improve the power delivered by such a stator, it is provided, for example, in accordance with DE 195 31 A1, EP 1 522 729 B2 or DE 41 11 166 C2, that the liner tapers conically from the suction side to the pressure side. The elastic deflection of the lining is thereby adapted to the continuously increasing conveying pressure in the axial direction or conveying direction. Due to the conical shape of the stator, if the wall thickness of the housing remains unchanged over the entire stator and the housing is likewise adapted to the conical taper, then an equally adapted transition piece must be used for connecting to the next component in the eccentric screw pump.

In addition, the force acting on the liner through the medium is increased in the case of such a conical taper. If the medium has, for example, coarse material components, for example rock masses, these coarse material components exert a greater load on the lining in the regions which are less elastic and have already been tapered, so that the lining as a whole wears out more rapidly.

Disclosure of Invention

The object of the present invention is therefore to provide a stator with increased delivery power, which can be produced in a simple manner, has high stability and can be integrated in an eccentric screw pump in a simple manner.

For this purpose, according to the invention, it is provided that the average wall thickness of the lining of the stator decreases continuously (i.e. according to a continuous function of any extent) in the axial direction starting from the end wall thickness in the region of the preferably cylindrical suction side of the stator to a minimum average wall thickness; and the average wall thickness increases again at least in sections after reaching the minimum average wall thickness, so that a preferably cylindrical widening is formed in the liner up to the pressure side of the stator. It should be understood here that the average wall thickness of the lining, starting from the smallest average wall thickness, increases again immediately after reaching its smallest average wall thickness, or remains almost constant in a certain region first, after reaching its smallest average wall thickness, and then increases again in order to form a widening in the lining.

In this way, it is advantageously achieved that a suitable transition to the pressure side can be achieved in addition to adapting the average wall thickness of the liner in the axial direction to the pump pressure acting in the pump cavity of the stator. The widened portion also advantageously allows for a connection to the next component of the eccentric screw pump (for example by means of a conventional flange). In this case, for example, the wall thickness can also be set as it is on the suction side, so that if the end wall thickness on the pressure side is approximately identical to that on the suction side, the same connection, for example a flange, can advantageously be used for both sides of the stator.

Furthermore, the lining becomes more flexible again towards the pressure side, whereby the conveying medium, which is normally under high pressure on the pressure side, can be stabilized. Because the pressure increases only slightly in the widened portion of the pressure side when the lining becomes more deflected again. In contrast to this, the medium transported undergoes an increased pressure increase in the region of the lining which becomes increasingly hard, due to the continuous reduction of the average wall thickness in the region preceding the widening, which is also desirable for the pumping action in this region. However, in the region of the widening, no increased pressure increase occurs anymore and the medium is thus stabilized. In the stator according to the invention, an optimized transfer of the medium fed into the next component of the eccentric screw pump is thus generally possible.

An improved holding function can also be achieved by the design of the stator if, for example, the eccentric screw pump is switched off. If the pressure difference between adjacent chambers in the pump chamber is too high, a backflow of the medium fed in the pump chamber may occur. If a hard liner is chosen, backflow only occurs if the pressure differential between the chambers is high. As a result, as the pressure of the medium being conveyed becomes higher, the liner which hardens in the axial direction also prevents backflow, i.e. a higher pressure difference may exist before the medium being conveyed flows back.

Preferably, this configuration also makes it possible to: the stator is based on the axial trend of the average wall thickness of the liner:

in the region of the intake side of the stator, a premixing zone is formed, which serves to homogenize and/or pulverize the medium to be conveyed;

forming a stabilizing zone in the widened portion in the region of the pressure side of the stator; and the stabilization zone is used for stabilizing and gently transferring the medium conveyed in the eccentric screw pump;

a high-pressure zone with reduced medium backflow is formed between the premixing zone and the stabilization zone, said high-pressure zone being used to increase the pressure in the pump cavity when the eccentric screw pump is in operation on the basis of an at least locally continuously reduced average wall thickness in the axial direction and thus an increased stiffness of the liner, the pressure in the high-pressure zone being adapted at least locally with a higher pressure gradient than in the premixing zone and the stabilization zone.

The stator is thus divided into different regions that are axially spaced apart from one another by a targeted introduction of the course of the average wall thickness, wherein the transition is preferably defined in such a way that the average wall thickness of the liner remains unchanged at least in the premixing zone and/or in the stabilization zone. The medium thus fed can be adapted to the changed tapering shape of the liner in the high-pressure region or the resulting changed delivery power of the stator when the medium enters the stator and/or when the medium exits the stator.

The average wall thickness may also be constant in the portion of the high pressure region. For example, it can be provided that the average wall thickness of the liner is continuously reduced in the axial direction to a minimum average wall thickness in a first high-pressure region of the high-pressure region, which adjoins the premixing zone, and is maintained almost constantly at the minimum average wall thickness in a second high-pressure region of the high-pressure region.

The medium is thus advantageously provided with a zone in which the medium can be homogenized or crushed on the suction side and/or stabilized on the pressure side. Depending on the application and the medium to be conveyed, the respective region can be set in a targeted manner by selecting the respective axial extension or axial width and wall thickness of the lining in the respective region. The medium can then be "prepared" in the corresponding zone for the next zone in the stator or in the eccentric screw pump.

Since the medium is already comminuted or homogenized in the premixing zone, the lining is less strongly stressed in the high-pressure zone, for example with reduced deflection. Thus, the lining wear in the high pressure region is less intense. The medium is stabilized in the stabilization zone, so that a gentle transition or gentle outflow from the stator can be achieved.

For the tapering of the liner, provision is preferably made for the liner of the stator to taper conically in the axial direction, wherein the average wall thickness of the liner for this purpose, starting from the average wall thickness at the end face, decreases linearly or follows a nonlinear function at least in some regions, for example in the high-pressure region or in parts of the high-pressure region, in the axial direction toward the pressure side. Hereby a linear taper or a taper according to a non-linear function is achieved which can be simply formed, preferably by linearly tapering or following a non-linear function the outer surface of the liner, preferably with the pump diameter in the pump cavity remaining unchanged.

Alternatively, it can also be provided that the lining of the stator is tapered at least in sections in the axial direction in such a way that the contour of the outer surface of the lining, starting from the average wall thickness at the end face to the smallest average wall thickness, is increasingly closer to the contour of the inner surface of the lining which is formed as a double-start coarse thread. The tapering and thus the adaptation of the average wall thickness to the pressure acting in the pump cavity is thereby also enhanced, since the outer jacket is also preferably adapted to this double-ended shape of the outer surface, so that the tapering can also be seen from the outside.

In particular, a taper of this type can be provided in the first high-pressure region of the high-pressure region, so that a transition between a preferably cylindrical pre-mixing region and a second high-pressure region of the high-pressure region can occur, wherein the outer jacket is adapted to the double-ended shape of the outer surface in the second high-pressure region. This results in a transition from a cylindrical cross section to a spiral cross section, wherein the average wall thickness remains unchanged in the second high-pressure region. In this way, a mixing stator is formed which consists of a cylindrical premixing zone and a helical high-pressure zone in a second high-pressure zone. As a result of the continuous adaptation of the average wall thickness, the first high-pressure region then serves as a transition with a correspondingly hardened lining.

In order to achieve a close approximation of the outer surface to the double-ended inner surface, it is preferably provided that the B-dimension of the liner, starting from the average wall thickness at the end side, decreases continuously in the axial direction towards the pressure side at least locally, for example in the high-pressure region or in a part of the high-pressure region, while at the same time the a-dimension of the liner remains constant. Thereby, the manufacturing process can be simplified according to this alternative.

It is furthermore preferably provided that the average wall thickness of the lining increases suddenly or continuously after the minimum average wall thickness has been reached and, if necessary, after the minimum average wall thickness has been maintained constantly (see the second high-pressure region), in order to form a pressure-side widening. The continuous increase enables a gentle transition between the high-voltage region and the stable region and a simpler production. However, abrupt transitions can also be provided, for example, in order to stabilize and keep the subsequent pressure rise of the conveyed medium within limits.

It is furthermore preferably provided that the inner diameter of the outer jacket corresponds to the outer diameter of the lining, so that the outer jacket rests in a planar manner on the outer surface of the lining over the entire stator and thus assumes a conical or spiral course corresponding to the outer surface, said outer jacket preferably having a constant material thickness for this purpose. The outer cover is made of a harder material than the lining, preferably steel. This allows the outer envelope surrounding the liner (for example by means of a moulding process) to be adapted simply to the tapering shape of the liner.

Drawings

The invention is illustrated in more detail below by means of examples. In the figure:

fig. 1 shows a stator according to a first embodiment;

fig. 1a shows a sectional view of the stator according to fig. 1;

fig. 2 shows a stator in a further embodiment;

fig. 2a, 2b show sectional views of the stator according to fig. 2;

fig. 3 shows a further embodiment of a stator.

Detailed Description

In fig. 1, a stator 1 is provided, which has a tubular housing 2, which is preferably made of steel tubing, for example by molding. The outer envelope 2 encloses an elastically flexible liner 3, the inner surface 4 of which has a spiral or helical profile K4, in which a double-start coarse thread is formed. In the interior of the stator 1, a pump cavity 5 is thus formed, into which a rotor 6 (fig. 1 a) is inserted, wherein the rotor 6 is formed in the manner of a single-start, coarse thread and, if appropriate, rests against the elastically flexible lining 3 under pretensioning. The eccentrically mounted rotor can be wound around the pump cavity 5.

The stator 1 has a suction side 7 and a pressure side 8, wherein in the case of the stator 1 together with the rotor 6 being mounted in an eccentric screw pump (not shown), if the rotor 6 is in rotation, the medium to be conveyed, such as mud, cement or mortar, is conveyed in the chamber from the suction side 7 through the pump cavity 5 in the axial direction X to the pressure side 8. The pressure in the pump chamber 5 increases here toward the pressure side 8, so that a smaller pressure acts on the elastically deflected lining 3 than on the pressure side 8 on the suction side 7.

According to the embodiment in fig. 1, the liner 3 is designed to be conical on its outer surface 9, wherein the average wall thickness W of the liner 3 decreases initially continuously, i.e. as a continuous function, from a position close to the suction side 7 of the stator 1 in the axial direction X towards the pressure side 8. The contour K9 of the outer side 9 here extends at least in some regions linearly downward, i.e. according to a linear function, in the axial direction X from a position close to the suction side 7. This is achieved by: the elastic flexibility of the liner 3 on the suction side 7 is higher than, for example, in the middle region of the stator 1 or in the region of the stator 1 with the smallest wall thickness WM. That is, the liner 3 becomes harder and harder (almost linearly) towards the pressure side 8.

The tapering of the cone can be adjusted in such a way that the average pump diameter DP remains unchanged over the entire stator 1, so that no adaptation of the rotor 6 is necessary either. For this purpose, only the outer surface 9 tapers in the axial direction X toward the pressure side 8. In principle, however, a continuous adaptation of the average pump diameter DP, in particular a conical taper to the pressure side 8, can also be provided.

Starting from the minimum wall thickness WM of the liner 3, the stator 1 has a widening 10 towards the pressure side 8, by means of which the average wall thickness W is increased to the end wall thickness WE. The end wall thickness WE on the suction side 7 is preferably equal to the end wall thickness WE on the pressure side 8. Thereby, the elastic flexibility or hardness of the liner 3 is almost the same on each end side of the stator 1.

According to the sectional view in fig. 1a, an a-dimension a and a B-dimension B can be given for the stator 1, which give the thickness of the lining 3 in the Z-direction Z and in the Y-direction Y, respectively. In order to achieve a conical tapering of the lining 3 in the axial direction X, according to this embodiment, it is provided that not only the a-dimension a but also the B-dimension B continuously decrease in the axial direction X from the respective position. Whereby the average wall thickness W continues to decrease up to the minimum wall thickness WM. Since the outer shell 2 is in planar contact with, preferably adhered to or vulcanized on, the lining 3, the inner diameter D of the outer shell is thus also continuously reduced. The outer diameter E of the liner 3 is thus equal to the inner diameter D of the outer shell 2.

Due to the conical taper of the liner 3 from the intake side 7 and the subsequent widening 10 on the pressure side 8, the stator 1 is divided into three regions V, H, S or areas:

in the premixing zone V starting on the suction side 7 of the stator 1, a relatively small pressure acts in the pump cavity 5. At the same time, a high elastic flexibility or a low stiffness of the liner 3 is obtained due to the comparably high average wall thickness W in the pre-mix zone V. The pre-mixing zone V is therefore suitable for comminuting or precompression of a coarse-grained medium, such as cement, mortar or slurry (which may also contain coarse material components, such as rock masses), which is conveyed via the suction side 7, and for homogeneously mixing the coarse-grained medium into a homogeneous medium.

Due to the high degree of elastic deflection in the premixing zone V, the liner 3 can withstand the forces acting during comminution of these coarse material components without damaging the liner 3 significantly beyond normal wear. This is aided by the fact that a small pressure is also exerted in the premixing zone V in the pump cavity 5 and this small pressure increases only very slightly. Thereby, an optimized mixing can be ensured.

In the premixing zone V, the average wall thickness W is constantly maintained at the end wall thickness WE. From a certain position in the axial direction X, the premixing zone V transitions into the high-pressure zone H, wherein this begins by reducing the average wall thickness W of the liner 3. The elastic flexibility of the liner 3 is reduced due to the reduction of the average wall thickness W. At the same time, the pressure in the pump chamber 5 increases in the axial direction X, so that the medium fed also acts with a higher force on the liner 3. However, since the comminution and homogenization of the medium conveyed already takes place in the premixing zone V, the lining 3 is less strongly stressed in the high-pressure zone H, since the material components of the medium have smaller particle sizes.

At the same time, a higher delivery power can be achieved due to the reduced elastic deflection of the liner 3 in the high-pressure region H, more precisely in the axial direction X, since the material of the liner 3 provides an increasingly higher resistance to the medium to be delivered in the face of a backflow across the sealing line between the rotor 6 and the liner 3 of the stator 1. In this case, the pressure increases more strongly in the high-pressure region H than in the pre-mixing region V, due to the reduced average wall thickness W of the liner 3 or the increased hardness. In the high-pressure region H, for example, the coarse material components that are still present can also be crushed by the high pressure in the pump chamber 5 and the reduced elastic deflection of the lining 3. However, these coarse material components are only present individually and are reduced very strongly up to the minimum wall thickness WM, so that damage to the lining 3 beyond normal wear can be avoided as much as possible.

The backflow characteristic of the stator 1 can be improved due to the tapered structure of the high-pressure region H. If the pressure difference between adjacent chambers in the pump cavity 5 is too high, a backflow of the medium fed may occur. If a harder liner 3 is chosen, backflow will only occur if the pressure difference between the chambers is high. As a result, as the pressure of the medium fed in the pump cavity 5 becomes higher and higher, the liner 3, which hardens in the axial direction X, also prevents backflow, i.e. a higher pressure difference may exist before the fed medium flows back.

Starting from the minimum wall thickness WM, a stabilizing zone S follows in the axial direction X in the stator 1, said stabilizing zone being located in the region of the pressure side 8 or the widening 10. In the stabilization zone S, the average wall thickness W of the lining 3 increases again and then extends constantly, so that the elastic flexibility of the lining 3 increases again or the stiffness of the lining 3 decreases again. As a result, a slight pressure increase occurs in the pump cavity 5 on the output side, as in the premix zone V.

In the transition region to the next component of the eccentric screw pump, i.e. on the pressure side 8 of the stator 1, reduced wear thus occurs, and the conveyed medium is stabilized before the transition to the next component.

Furthermore, by increasing the average wall thickness W to the end wall thickness WE in the region of the widened portion 10, a connection to the next component of the eccentric screw pump can be provided (for example by means of a flange). On the suction side 7 and the pressure side 8 of the stator 1, identical or standardized flanges or connections can advantageously be used with identical end wall thicknesses WE. Based on the external shape of the stator 1, it can be clearly recognized that: in which direction of the stator 1 the eccentric screw pump should be fitted.

According to a further embodiment of the stator 1 shown in fig. 2, the reduction of the average wall thickness W in the axial direction X is achieved by adapting the outer surface 9 of the liner 3 continuously to the helical inner surface 4 of the liner 3. Accordingly, the outer surface 9 likewise forms a double-start coarse thread from a defined axial position. Since the outer shell 2 is applied in a planar manner to the outer surface 9 of the lining 3 or is adhered or vulcanized to said outer surface, the outer shell 2 follows the shape of the double-start coarse thread of the inner surface 4 from a defined axial position.

The stator 1 is thereby also divided in the axial direction X into a premixing zone V, a high-pressure zone H and a stabilization zone S, wherein an almost constant average wall thickness W is also initially formed in the premixing zone V, said average wall thickness being equal to the average wall thickness WE at the end side. A high degree of elastic flexibility of the lining 3 is thereby achieved over a certain area, whereby the medium conveyed through the suction side 7 can be crushed or mixed or homogenized without damaging the lining 3 significantly beyond normal wear.

From a certain axial position, the average wall thickness W of the lining 3 is continuously reduced (dotted line in fig. 2), which is achieved, as described above, by continuously adapting the outer surface 9 of the lining 3 to the double-start coarse thread formed by the inner surface 4. This also causes the liner 3 to taper continuously in the axial direction from the suction side 7 toward the pressure side 8. However, a difference from the embodiment in fig. 1 is that a reduction in the average wall thickness W or an increase in the hardness is achieved in the further steeper course, which further enhances the pumping effect because an increased pressure increase is achieved.

In the embodiment according to fig. 2, moreover, a high-pressure region H is formed by the continuous tapering of the liner in the axial direction X, in which the elastic deflection of the liner 3 is continuously reduced, while the pressure in the pump cavity 5 is increasingly greater. In this way, comminution of the coarse material components can take place at the beginning of the high-pressure region H (if still required), wherein damage to the lining 3 is avoided due to the still lower pressure in the pump cavity 5. In the subsequent axial extension, the medium to be conveyed is again homogenized, so that a low-wear conveyance with a maximum conveying power can be achieved in the region of the minimum wall thickness.

In the embodiment according to fig. 2, the average wall thickness W increases again starting from the minimum wall thickness WM in the region of the widening 10 and is then constant, so that a stabilizing region S is also formed here. In this stability zone, the pressure in the pump cavity 5 increases only slightly as a result of the small deflection, so that a low-wear and gentle transition with stable medium to the next component in the eccentric screw pump can be provided. The end wall thickness WE on the pressure side 8 is also equal to the end wall thickness WE on the suction side 7 in order to achieve the same connection on both end sides of the stator 1.

As can be seen from the sectional views of the embodiment shown in fig. 2a and 2B, which are assigned to fig. 2, the a-dimension a and the B-dimension B are adapted differently in order to form a continuous tapering of the lining 3 in the axial direction X. Fig. 2a shows a sectional view of the stator 1 in the premixing zone V, wherein the a-dimension a or the B-dimension B in this axial position corresponds substantially to the dimension A, B in fig. 1a with respect to the first embodiment. Fig. 2b shows a sectional view of the stator 1 in the high-pressure region H, i.e. after tapering. The a dimension a remains the same relative to the conditions in the pre-mix zone V (see fig. 2 a). Only the B dimension B is reduced relative to the conditions in the pre-mix zone V. Thus, a continuous tapering of the liner 3 in the axial direction is achieved by adapting the B dimension B only.

The half axes HA1, HA2 of the outer shell 2 or of the lining 3 are also shown in a corresponding manner. The first half axis HA1 pointing in the Z direction remains constant along the axial direction X, while the second half axis HA2 pointing in the Y direction continues to taper. Since the outer cover 2 is in planar contact with the lining 3, the outer cover 2 (inner surface) corresponds to the half axes HA1, HA2 of the lining 3 (outer surface).

The outer contour K9 of the double-ended spiral of the stator 1 is also thus obtained, which can be seen from the outside due to the simultaneous shape adaptation of the outer jacket 2 to the outer surface 9 of the liner 3. With this design, the division of the stator 1 into different zones V, H, S can also be assisted, since the elastic flexibility can be optimally adapted to the pressure conditions in the pump cavity 5 by adapting the wall thickness of the spiral in the axial direction.

In contrast to the embodiment in fig. 2, it is provided according to fig. 3 that the width VB of the premixing zone V in the axial direction X is increased compared to the previous embodiment. Thus, the method can specifically determine: for example, depending on the extension of the application area of the stator 1, a homogenization or mixing of the conveying medium should take place with low wear. The number of coarse material particles in the high-pressure region H can thereby be reduced and the wear of the lining 3 can thus be influenced in a targeted manner. The width SB of the stabilization zone S can also be adjusted accordingly in order to provide the medium with a sufficiently large area for stabilization and thus optimize the transition, for example, depending on the application range. The width HB of the high-pressure region H can also be selected accordingly in order to determine the range over which the supply power should be increased by a corresponding adaptation of the pressure gradient. This can be achieved in a coordinated manner with the course of the average wall thickness W in order to achieve a corresponding pressure increase in the conveying direction.

In the first exemplary embodiment according to fig. 1, the widths VN, HB, SB can also be determined correspondingly variably.

Fig. 3 also provides that the high-voltage region H is divided into two high-voltage regions H1, H2. In the first high-pressure region H1 of the high-pressure region H, the average wall thickness W initially continues to decrease in the axial direction X until the minimum average wall thickness WM is reached. In the second high-pressure region H2 of the high-pressure region H, the average wall thickness W is kept almost constant at the minimum average wall thickness WM. The average wall thickness W of the lining 3 then increases again from the smallest average wall thickness WM toward the pressure side 8 of the stator 1, so that a widening 10 in the lining 3 is formed on the pressure side 8.

With such a construction a "hybrid stator" is provided, which consists of a cylindrical stator in the premixing zone V and a double-ended helical stator in the second high-pressure zone H2 of the high-pressure zone H. The average wall thickness W within the two mixing components (cylindrical stator in the premixing zone V and double-ended helical stator in the second high-pressure region H2) is here different but constant in each case. The transition between the two mixing elements is ensured by a continuous adaptation of the average wall thickness W in the first high-pressure region H1, whereby an adaptation of the hardness of the lining is also achieved simultaneously as in the first embodiment variant in fig. 1 and 2. In the stabilization zone S, the widening 10 is formed by a continuous adaptation of the average wall thickness W.

List of reference numerals

1. Stator

2. Outer cover

3. Liner for a vehicle

4. Inner surface of liner 3

5. Pump cavity

6. Rotor

7. Suction side

8. Pressure side

9. The outer surface of the lining 3

10. Widened portion

A A size

B B size

Inner diameter of D outer cover 1

Outer diameter of E liner 3

DP average pump diameter

H high voltage region

H1 First high-voltage region of high-voltage region H

H2 Second high-voltage region of high-voltage region H

Width of HB high voltage region H

HA1 first half axis

HA2 second half shaft

K4 The profile of the inner surface 4 of the liner 3

K9 Contour of the outer surface 9 of the liner 3

S stability region

Width of SB stabilization zone

V Pre-mix zone

Width of VB Pre-mix zone V

W average wall thickness

WE end sidewall thickness

WM minimum wall thickness

In the X-axis direction

Y, Z Y, Z direction

Claims

1. Stator (1) for an eccentric screw pump having a rotor (6), the stator (1) having an elastically flexible liner (3) comprising an outer surface (9), the liner (3) being surrounded by a rigid outer cover (2),

the inner surface (4) of the liner (3) forms a double-ended coarse thread and defines a pump cavity (5) extending in the axial direction (X) for receiving a rotor (6) of an eccentric screw pump,

the lining (3) of the stator (1) tapers at least in sections in the axial direction (X), for which purpose the average wall thickness (W) of the lining (3) decreases continuously at least in sections in the axial direction (X) starting from the end wall thickness (WE) in the region of the intake side (7) of the stator (1) until a minimum average wall thickness (WM) is reached,

characterized in that the average wall thickness (W) of the lining (3) increases from the smallest average wall thickness (WM) toward the pressure side (8) of the stator (1) in turn at least in regions, so that a widening (10) is formed in the lining (3) toward the pressure side (8) of the stator (1).

2. Stator (1) according to claim 1, characterized in that it is based on the axial trend of the average wall thickness (W) of the liner (3):

in the region of the intake side (7) of the stator (1), a premixing zone (V) is formed, which serves to homogenize and/or pulverize the medium to be conveyed;

in the region of the pressure side (8) of the stator (1), a stabilization zone (S) is formed in the widening (10) for stabilizing and gently displacing the medium conveyed in the eccentric screw pump; and

a high-pressure region (H) is formed between the premixing region (V) and the stabilization region (S), said high-pressure region being used to increase the pressure in the pump cavity (5) when the eccentric screw pump is in operation, on the basis of an average wall thickness (W) which is continuously reduced at least in regions in the axial direction (X).

3. Stator (1) according to claim 2, characterized in that the average wall thickness (W) of the liner (3) remains unchanged in the premixing zone (V) and/or in the stabilization zone (S).

4. A stator (1) according to claim 2 or 3, characterized in that the average wall thickness (W) of the liner (3) continuously decreases in the axial direction (X) in a first high pressure region (H1) of the high pressure region (H), while being kept almost constant over the minimum average wall thickness (WM) in a second high pressure region (H2) of the high pressure region (H), said first high pressure region (H1) being adjacent to the premixing zone (V).

5. Stator (1) according to claim 1, characterized in that the lining (3) of the stator (1) tapers conically in the axial direction (X), for which purpose the average wall thickness (W) of the lining (3) decreases linearly in the axial direction (X) from the end wall thickness (WE) in the direction of the pressure side (8) or follows a nonlinear function.

6. Stator (1) according to claim 5, characterized in that the outer surface (9) of the liner (3) tapers linearly or follows a non-linear function in order to achieve a linear decrease or a non-linear function of the average wall thickness (W) starting from the end wall thickness (WE).

7. Stator (1) according to claim 1, characterized in that the lining (3) of the stator (1) tapers in the axial direction (X) in such a way that the contour (K9) of the outer surface (9) of the lining (3) starts from the end wall thickness (WE) to a minimum average wall thickness (WM) that is increasingly closer to the contour (K4) of the inner surface (4) of the lining (3) configured as a double-start coarse thread.

8. Stator (1) according to claim 7, characterized in that the B-dimension of the liner (3) decreases continuously from the end side wall thickness (WE) in the axial direction (X) towards the pressure side (8) while at the same time the a-dimension of the liner (3) remains unchanged, the a-dimension and the B-dimension giving the thickness of the liner (3) in the Z-direction and in the Y-direction, respectively.

9. Stator (1) according to claim 7, characterized in that a first half axis (HA 1) of the housing (2) pointing in the Z-direction remains unchanged along the axial direction (X), while a second half axis (HA 2) of the housing (2) perpendicular to said first half axis (HA 1) continues to decrease along the axial direction (X).

10. Stator (1) according to claim 7, characterized in that the contour (K9) of the outer surface (9) of the liner (3) is almost round in the region of the average wall thickness (W) equal to the end wall thickness (WE), while the contour (K4) of the inner surface (4) of the liner (3) configured as a double-start coarse thread extends parallel in the region of the average wall thickness (W) equal to the minimum average wall thickness (WM).

11. Stator (1) according to claim 1, characterized in that the average wall thickness (W) in the widened portion (10) on the pressure side (8) is equal to the end wall thickness (WE) on the suction side (7).

12. Stator (1) according to claim 1, characterized in that the average wall thickness (W) of the lining (3) is suddenly or continuously increased after reaching the minimum average wall thickness (WM) in order to constitute a pressure-side widening (10).

13. Stator (1) according to claim 1, characterized in that the average pump Diameter (DP) of the pump cavity (5) tapers at least locally equally towards the pressure side (8) in the axial direction (X) or remains unchanged over the entire stator (1) in the axial direction (X).

14. Stator (1) according to claim 1, characterized in that the inner diameter (D) of the cover (2) is equal to the outer diameter (E) of the liner (3) so that the cover (2) rests in a planar manner on the outer surface (9) of the liner (3) over the entire stator (1), the cover (2) being adapted by deformation to the contour (K9) of the outer surface (9).

15. Stator (1) according to claim 1, characterized in that the housing (2) has a material thickness which remains unchanged in the axial direction (X).

16. Stator according to claim 13, characterized in that the average pump Diameter (DP) of the pump cavity (5) tapers at least locally linearly in the axial direction (X) towards the pressure side (8).