Stator For An Eccentric Screw Pump, An Eccentric Screw Pump And A Method For Producing A Stator

Abstract

A stator for an eccentric screw pump with an internal hollow space with a helically coiled inner contour for accommodating a rotor. The stator includes a stator core arranged in a stator casing, which stator core includes at least two radially separable core parts. According to the invention, the at least two radially separable core parts are each made from a metallic material or a technical ceramic material. The stator casing is a stator tube and is made of a metallic material. The stator casing is shrink-fitted onto the stator core. The invention also relates to an eccentric screw pump and a method for producing a stator.

Claims

1. A stator for an eccentric screw pump with an internal hollow space with a helically coiled inner contour for accommodating a rotor, wherein the stator comprises a stator core arranged in a stator casing, wherein the stator core comprises at least two radially separable core parts, wherein the at least two radially separable core parts are each made from a metallic material or a technical ceramic material, that the stator casing is constituted by a stator tube made of a metallic material and that the stator casing is shrink-fitted onto the stator core or that the stator core is shrink-fitted into the stator casing.

2. The stator according to claim 1, wherein the core parts each comprise a partial inner contour and wherein the partial inner contours of the at least two core parts in the assembled stator core form the inner contour of the stator core.

3. The stator according to claim 1, wherein at least one first core part comprises at least one positioning pin on a contact face with respect to at least one second core and wherein the at least one second core part comprises at least one corresponding recess for receiving the positioning pin at a corresponding position of a contact face with respect to the at least one first core part.

4. The stator according to claim 1, wherein the stator core composed of at least two core parts, before the shrinking-on of the stator casing or before the shrink-fitting into the stator casing at an ambient temperature in a temperature range between 5° C. and 25° C., has an outer circumference which is slightly greater than the inner circumference of the stator casing at an ambient temperature in a range between 5° C. and 25° C.

5. An eccentric screw pump comprising a stator with an internal hollow space with a helically coiled inner contour for accommodating a helical rotor, wherein meandering delivery spaces for the transport of material to be delivered are formed by the rotor and the stator during the operation of the eccentric screw pump, wherein the stator comprises a stator core arranged in a stator casing, wherein the stator core comprises at least two radially separable core parts, wherein the at least two radially separable core parts are each made from a metallic material or a technical ceramic material, that the stator casing is constituted by a stator tube made of a metallic material and that the stator casing is shrink-fitted onto the stator core or that the stator core is shrink-fitted into the stator casing.

6. The eccentric screw pump according to claim 5, wherein the core parts each comprise a partial inner contour and wherein the partial inner contours of the at least two core parts in the assembled stator core form the inner contour of the stator core.

7. A method for producing a stator comprising a stator core arranged in a stator casing, the stator core comprising an internal hollow space with a helically coiled inner contour for accommodating a rotor, wherein the stator core comprises at least two radially separable core parts, wherein the at least two radially separable core parts of the stator core are produced from a metallic material or a technical ceramic material, that the stator casing is produced as a stator tube made from a metallic material and that the stator casing is shrink-fitted onto the stator core or that the stator core is shrink-fitted into the stator casing.

8. The method according to claim 7, wherein the stator core is produced from two core parts, which are split through a plane through the central stator longitudinal axis.

9. The method according to claim 7, wherein a duly constituted partial inner contour is introduced into the respective core parts by multiaxial profile milling, in such a way that the core parts assembled to form the stator core constitute the inner contour of the stator core.

10. The method according to claim 7, wherein at least one positioning pin is provided on at least one first core part on a contact face with respect to at least one second core part and wherein at least one corresponding recess for receiving the positioning pin is formed on at least one second core part at a corresponding position of a contact face with respect to the at least one first core part, wherein the at least two core parts are joined together in such a way that the at least one positioning pin of the at least one first core part engages in the at least one corresponding recess of the at least one second core part.

11. The method according to claim 7, wherein the stator core composed of at least two core parts, before the shrink-fitting into the stator casing at an ambient temperature in a temperature range between 5° C. and 25° C., has a first outer circumference which is slightly greater than the inner circumference of the stator casing at an ambient temperature in a range between 5° C. and 25° C., wherein the stator core composed of at least two core parts is cooled to a first temperature, wherein the cooled stator core at the first temperature has a second outer circumference which is slightly smaller than the inner circumference of the stator casing, wherein the cooled stator core is pushed into the stator casing, so that the radial spacing between the cooled stator core and the stator casing is identical overall, wherein the stator core is shrink-fitted into the stator casing by a temperature equalisation between the stator core and the stator casing and/or by adaptation to an ambient temperature.

12. The method according to claim 7, wherein the stator core composed of at least two core parts, before the shrinking-on of the stator casing at an ambient temperature in a temperature range between 5° C. and 25° C., has a first outer circumference which is slightly greater than the inner circumference of the stator casing at an ambient temperature in a range between 5° C. and 25° C., wherein the stator core composed of at least two core parts is cooled to a first temperature, and wherein the stator casing is heated to a second temperature, wherein the cooled stator core at the first temperature has a second outer circumference which is slightly smaller than the inner circumference of the heated stator casing, wherein the cooled stator core is pushed into the heated stator casing, so that the radial spacing between the cooled stator core and the heated stator casing is identical overall, wherein the stator casing is shrink-fitted onto the stator core by the temperature equalisation between the stator core and the stator casing and/or by cooling to an ambient temperature.

13. The method according to claim 11, wherein the stator core is cooled to a first temperature in a first temperature range between −50° C. and −250° C. and/or wherein the stator casing is heated to a second temperature in a second temperature range between 35° C. and 150° C.

14. The method according to claim 11, wherein the stator core is cooled with liquid nitrogen to a first temperature of approx. −200° C.

15. The stator according to claim 2, wherein at least one first core part comprises at least one positioning pin on a contact face with respect to at least one second core part and wherein the at least one second core part comprises at least one corresponding recess for receiving the positioning pin at a corresponding position of a contact face with respect to the at least one first core part.

16. The method according to claim 8, wherein a duly constituted partial inner contour is introduced into the respective core parts by multiaxial profile milling, in such a way that the core parts assembled to form the stator core constitute the inner contour of the stator core.

17. The method according to claim 12, wherein the stator core is cooled to a first temperature) in a first temperature range between −50° C. and −250° C. and/or wherein the stator casing is heated to a second temperature) in a second temperature range between 35° C. and 150° C.

18. The eccentric screw pump according to claim 5, wherein at least one first core part comprises at least one positioning pin on a contact face with respect to at least one second core part and wherein the at least one second core part comprises at least one corresponding recess for receiving the positioning pin at a corresponding position of a contact face with respect to the at least one first core part.

19. The eccentric screw pump according to claim 5, wherein the stator core composed of at least two core parts, before the shrinking-on of the stator casing or before the shrink-fitting into the stator casing at an ambient temperature in a temperature range between 5° C. and 25° C., has an outer circumference which is slightly greater than the inner circumference of the stator casing at an ambient temperature in a range between 5° C. and 25° C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Examples of embodiment of the invention and its advantages are explained in greater detail below with the aid of the appended figures. The size ratios of the individual elements with respect to one another in the figures do not always correspond to the actual size ratios, since some forms are represented simplified and other forms magnified compared to other elements for the sake of better clarity.

[0026] FIG. 1 show diagrammatic views of the main components of a stator according to the invention before the assembly of the stator.

[0027] FIG. 2 shows a diagrammatic view of a stator produced according to the invention.

[0028] FIG. 3 show diagrammatically the process steps for producing a stator according to the invention.

DETAILED DESCRIPTION

[0029] Identical reference numbers are used for identical or identically acting elements of the invention. Furthermore, for the sake of clarity, only reference numbers that are required for the description of the given figure are represented in the individual figures. The represented embodiments only represent examples as to how the device according to the invention or the method according to the invention can be constituted and do not represent a conclusive limitation.

[0030] FIGS. 1A and B show diagrammatic views of the main components of a stator 1 according to the invention for the assembly of stator 1 (see FIG. 2) and FIG. 2 shows a diagrammatic view of a stator 1 produced according to the invention. FIG. 1A shows two core parts 3a, 3b which together form a stator core 2. Stator core 2 comprises an essentially cylindrical outer casing 6. Core parts 3a, 3b each comprise a partial contour 8a, 8b, which form the inner contour 7 of stator 1 after assembly of core parts 3a, 3b (see FIG. 2). Partial contours 8a, 8b are produced by multiaxial profile milling with high precision. It is important here that the two core parts 3a, 3b have a common reference point. The one core part 3a comprises two alignment pins 9-1, 9-2 at its contact faces 5a with respect to second core part 3b and second core part 3b comprises two pin locators 10-1, 10-2 at corresponding positions of its contact faces 5b with respect to first core part 3a. The two core parts 3a, 3b are joined together and pinned in position with one another with the aid of alignment pins 9-1, 9-2 and pin locators 10-1, 10-2.

[0031] FIG. 1B shows a stator casing 4, for example a steel tube. Core parts 3a, 3b are preferably produced oversized, i.e. pinned core parts 3a, 3b form a stator core 2, which in the unassembled state has an outer circumference which is greater than the inner circumference of tubular stator casing 4.

[0032] FIG. 3 show diagrammatically the process steps for the production of a stator 1 according to the invention. At the start, the components of the stator, in particular stator core 2 composed of at least two pinned core parts 3 and stator casing 4, have ambient temperature T(U) (see FIG. 3A).

[0033] In a first process step I, pinned stator core 2 is cooled, whereby heat Q1 is extracted from the latter, as a result of which the stator core is cooled to a first temperature T(1), which lies below ambient temperature T(U). For example, pinned stator core 2 is cooled to approx. −200° C. by means of liquid nitrogen. As a result of the cooling of stator core 2, the material from which core parts 3 of stator core 2 are formed shrinks, so that the outer circumference of stator core 2T(1) cooled to first temperature T(1) is smaller than the outer circumference of stator core 2 at normal ambient temperature T(U).

[0034] In parallel with this, stator casing 4 is heated to a second temperature T(2) by supplying heat Q2. As a result of the heating, stator casing 4 expands. In particular, the material of stator casing 4 is selected such that the inner circumference of stator casing 4 is increased by heating.

[0035] In particular, the outer circumference of stator core 2T(1) cooled to first temperature T(1) is smaller than the inner circumference of heated stator casing 4T(2).

[0036] In a second process step II, cooled stator core 2T(1) is pushed into stator casing 4T(2) (see FIG. 4C) and positioned, care being taken to ensure that the radial spacing between stator core 2T(1) and stator casing 4T(2) is identical overall.

[0037] In a third process step III, a continuous heat exchange between stator core 2 and stator casing 4 leads to a temperature equalisation between stator core 2 and stator casing 4, as a result of which stator casing 4 shrinks onto stator core 2. In stator casing 1 thus produced, a permanently fixed connection is thus produced between stator core 2 and stator casing 4.

[0038] This permanently fixed connection is resistant particularly in the event of temperature fluctuations between 15° C. to 300° C. in the ongoing operation of an eccentric screw pump with a stator 1, since no adhesives are used which can spread at high temperatures.

[0039] The invention has been described by reference to a preferred embodiment.

[0040] A person skilled in the art can however imagine that modifications or changes to the invention can be made without thereby departing from the scope of protection of the following claims.