Magnetic inductive flow measuring instruments and measuring tubes

Abstract

The invention relates to a magnetic-inductive flowmeter (1) for determining the flow of a medium, the magnetic-inductive flowmeter having a measuring tube (2) for guiding the medium along a longitudinal axis (L) of the measuring tube (2) and having two electrodes (3) for measuring a measurement voltage induced in the medium, wherein the measuring tube (2) has an inflow section (4), a measuring section (5) and an outflow section (6) arranged in sequence along the flow direction of the medium, wherein the inflow section (4) has a cross section that decreases in the flow direction, wherein the measuring section (5) has a constant cross section and is symmetrically designed with respect to a measuring section symmetry plane (MSE), wherein the measuring section symmetry plane (MSE) extends parallel to the longitudinal axis (L) of the measuring tube (2), and wherein the outflow section (5) has a cross section that increases in the flow direction. The object of specifying a magnetic-inductive flowmeter (1) in which the measuring accuracy is increased compared to magnetic-inductive flowmeters known from the prior art is achieved in that the outflow section (5) is at least partially designed asymmetrically with respect to the measuring section symmetry plane (MSE).

Description

Technical Field

[0001] The invention relates to a magnetic-inductive flowmeter for determining the flow of a medium, the magnetic-inductive flowmeter having a measuring tube for guiding the medium along its longitudinal axis and having two electrodes for measuring a measuring voltage induced in the medium, wherein the measuring tube has an inflow section, a measuring section and an outflow section arranged in sequence along the flow direction of the medium, wherein the inflow section has a cross section that decreases in the flow direction, wherein the measuring section has a constant cross section and is symmetrically constructed with respect to a measuring section symmetry plane, wherein the measuring section symmetry plane extends parallel to the longitudinal axis of the measuring tube, and wherein the outflow section has a cross section that increases in the flow direction. The invention also relates to a measuring tube for a magnetic-inductive flowmeter. Background Art

[0002] The measuring tube of the magnetic-inductive flowmeter has an inflow section, which is used to connect the magnetic-inductive flowmeter to a medium inlet. The measuring tube cross section is usually circular on the inlet side of the inflow section and is adapted to standardized tube sizes in order to ensure a problem-free connection to the medium inlet.

[0003] The measuring section follows the inflow section when viewed in the flow direction. The measuring section is defined as a region which is penetrated by the magnetic field and in which the actual flow measurement is achieved. The measuring section has a reduced cross section, thereby increasing the flow velocity of the medium. The increased flow velocity can increase the measurement accuracy or strengthen the measurement signal.

[0004] When "reduced cross section" is mentioned here, this is a simplified but easily understandable expression for "reduced area of ​​the cross section". This is reasonable, since without the geometrical properties, the flow velocity in the measuring section cannot be increased. When considering this, the cross section always results from a cut of the measuring tube perpendicular to the flow direction.

[0005] The measuring section is constructed symmetrically with respect to the measuring section symmetry plane, i.e., it is divided into two identical parts by the measuring section symmetry plane. The measuring section symmetry plane extends parallel to the longitudinal axis of the measuring tube, wherein the longitudinal axis direction of the measuring tube is defined as the direction along which the medium flows through the measuring tube as a whole (i.e., on average in cross section). In the case of a symmetrical measuring tube, the longitudinal axis is the center axis and the symmetry axis of the measuring tube. The inflow section, the measuring section and the outflow section are arranged one after the other along the longitudinal axis of the measuring tube. In other words, the measuring section symmetry plane divides the measuring section cross section into a first sub-cross section and a second sub-cross section, wherein the first sub-cross section corresponds to the second sub-cross section mirrored at the measuring section symmetry plane. When, in other words, the measuring section symmetry plane extends parallel to the longitudinal axis of the measuring tube, this does not necessarily mean that the longitudinal axis and the measuring section symmetry plane extend spaced apart from each other. Conversely, the longitudinal axis of the measuring tube can also be located in the measuring section symmetry plane.

[0006] In some embodiments, the measuring section has not only a reduced cross section but also a cross-sectional geometry that differs from the inlet side of the inflow section. In the prior art, a rectangular measuring section cross section is particularly preferred. The electrodes are then preferably arranged at the short sides of the measuring section, since the increased spacing of the electrodes from one another leads to an improved measurement signal.

[0007] If, in other words, the measuring section has a constant cross section, this means that the cross section remains constant with respect to its area and its shape.

[0008] The outflow section adjoins the measuring section when viewed in the flow direction. In the region of the outflow section, an increase in the cross section occurs again. On the outlet side of the outflow section, which can be connected to the medium outlet, the cross section is usually circular again and corresponds to a standardized tube size. The flow velocity of the medium is reduced by increasing the cross section. This causes an uneven flow in the region of the outflow section, which is particularly evident by the flow leaning against one side of the measuring tube, wherein leaning against the same measuring tube side is not mandatory. Due to the uneven, unpredictable and partly also temporally variable flow distribution, measurement inaccuracies arise in the flow determination. Summary of the invention

[0009] Starting from the described prior art, the invention is based on the object of specifying a magnetic-inductive flowmeter and a measuring tube for a magnetic-inductive flowmeter, in which the measuring accuracy is increased.

[0010] This object is achieved in the case of the magneto-inductive flowmeter according to the invention primarily and essentially in that the outflow section is designed at least partially asymmetrically with respect to the measuring section plane of symmetry.

[0011] According to the invention, it was first recognized that different flow measurement values ​​are determined depending on which side of the measuring tube the flow rests on. The invention is therefore based on the idea of ​​forcing the flow to rest on only one side of the measuring tube, which is achieved by configuring an asymmetrical outflow section. By forcing the flow to rest on only one side of the measuring tube in the case of the magnetic-inductive measuring instrument according to the invention, different measurement values ​​no longer occur, whereby the measurement accuracy of the flow is improved compared to known magnetic-inductive flow measuring instruments.

[0012] Typically, the measuring section has not just one, but multiple measuring-section symmetry planes. In one embodiment, the measuring section has a substantially rectangular cross section. If, that is, the cross section is constructed in a substantially rectangular manner, then all the following cross sections fall into this category, which have two parallel, opposite longitudinal sides, wherein the short sides that are also opposite do not necessarily have to be straight sides, but can also have a circular segment-shaped design in particular. In the case of such a measuring tube, in the design of the magnetic-inductive flowmeter according to the invention, a measuring section symmetry plane is selected that is parallel to the longitudinal side of the cross section. The measuring section cross section is divided by the measuring section symmetry plane, i.e., along its longitudinal extension.

[0013] In an alternative design, the measuring section has a square cross section, i.e., has four sides of equal length, which are each at right angles to one another. This also includes designs in which the corners are rounded. That is, the measuring tube has a substantially square cross section. Preferably, in such a design, a measuring section symmetry plane is selected, which extends parallel to one of the four sides of equal length of the measuring section. In particular, a symmetry plane is not selected, which cuts the measuring section diagonally, in which case two diagonally opposite corners are located in the measuring section symmetry plane.

[0014] However, the following embodiments are independent of the specific design or shape of the cross section of the measuring section and can be used in any arbitrary embodiment. It is only important that the measuring section has at least one measuring section symmetry plane.

[0015] A particularly preferred embodiment of the magnetic-inductive flowmeter is characterized in that the outflow section is designed asymmetrically over its entire length with respect to the measuring section symmetry plane. When the length of the outflow section is mentioned, this means the extension of the outflow section along the longitudinal axis of the measuring tube.

[0016] In an alternative embodiment of the magneto-inductive flowmeter, the outflow section is designed asymmetrically with respect to the measuring section symmetry plane over a restricted longitudinal extension. The outflow section thus has an asymmetry with respect to the measuring section symmetry plane only in a restricted region.

[0017] According to the invention, various embodiments are provided, with which an asymmetry of the outflow section with respect to the plane of symmetry of the measuring section is produced.

[0018] In a particularly preferred design, the asymmetry is constructed in such a way that the measuring section is arranged offset relative to the inflow section and relative to the outflow section in a direction perpendicular to the plane of symmetry of the measuring section. Such a design is particularly advantageous when the measuring section has a rectangular cross section. By offsetting the measuring sections, the asymmetry can be produced in a simple manner. The design has the advantage that no foreign bodies need to be introduced into the measuring tube, and in particular, the flow of the medium is not disturbed by unevenness of the inner surface of the measuring tube or by foreign bodies.

[0019] In another preferred design, the asymmetry is constructed in the following manner, that is, at least one embedding element is arranged in the outflow section. In one design, the embedding element is arranged in the outflow section of a measuring tube with an outflow section that is basically symmetrical about the measuring section symmetry plane. In another design, the embedding element is arranged in the outflow section of the measuring tube, and the outflow section is already constructed asymmetrically about the measuring section symmetry plane. Therefore, the asymmetry is strengthened by the embedding element. The embedding element itself is implemented differently in different designs. In a preferred design, the embedding element is formed by an epoxy resin layer. The design has the advantage that the size of the embedding element can still be selected when the embedding element is brought into the outflow section.

[0020] Overall, the asymmetrical design brought about by the insert element offers the advantage that an already produced measuring tube of a magneto-inductive flowmeter can be retrofitted in a simple manner, ie equipped with an asymmetrical outflow section.

[0021] Another preferred design is characterized in that the asymmetry is constructed by a stepped protrusion in the outflow section that reduces the cross section. Preferably, the stepped protrusion is constructed on the entire periphery of the outflow section. In order to then achieve the asymmetry, the protrusion on the first side of the plane of symmetry of the measuring section is at least partially flatter than on the second side of the plane of symmetry. In a preferred design (in which the entire measuring tube is joined together by two measuring tube parts), the stepped protrusion is formed by the joint seam. It is advantageous in the design to use a joint seam that interferes with the flow of the medium. When mentioning a stepped protrusion, this does not only mean this type of protrusion with a right angle. On the contrary, the protrusion can also have an angle less than or greater than 90 degrees or have a slightly rounded corner. The cross section of the measuring tube is reduced in the region of the stepped protrusion along the flow direction by the stepped protrusion.

[0022] In another preferred design, the asymmetry of the outflow section with respect to the plane of symmetry of the measuring section is constructed by an arch in the outflow section that reduces the cross section. Here, the arch is understood to be a protrusion that has a continuous extension. In the case of constructing the arch, the advantage over the stepped protrusion is that the eddy formation in the medium in the region of the arch is reduced relative to the eddy formation in the region of the stepped protrusion, because no reflection of the medium is generated at the step, but rather the medium flows through the arch. In order to achieve asymmetry, the arch is designed only on one side of the plane of symmetry of the measuring section or the arch is constructed more strongly on one side of the plane of symmetry of the measuring section than on the other side of the plane of symmetry of the measuring section.

[0023] The magneto-inductive flowmeters described so far are particularly suitable for applications in which the medium flows through the measuring tube in only one direction.

[0024] Some applications require a bidirectional flow of the medium through the measuring tube. Therefore, a particularly preferred embodiment of the magnetic-inductive flowmeter according to the invention provides that the inflow section is also designed at least partially asymmetrically with respect to the measuring section symmetry plane.

[0025] In order to prevent the formation of eddy currents in the region of the measuring section, it is provided in a particularly preferred embodiment of the magnetic-inductive flowmeter that the inflow section is designed asymmetrically over its entire length. Such an embodiment is preferred over an embodiment in which the asymmetry is only designed over a restricted longitudinal extension. Likewise, the invention also encompasses the design of the asymmetry only over a restricted longitudinal extension of the inflow section.

[0026] Any configuration of the asymmetry of the inflow section can be implemented and transferred accordingly for any configuration of the asymmetry of the outflow section.

[0027] In a particularly preferred embodiment of the magnetic-inductive flowmeter, the asymmetry of the inflow section is designed to correspond to the asymmetry of the outflow section. Both asymmetries are implemented in the same way. In an alternative embodiment of the magnetic-inductive flowmeter, the asymmetry of the inflow section is designed in a different way than the asymmetry of the outflow section.

[0028] In addition to the magnetic-inductive flowmeter, the present invention also relates to a measuring tube for a magnetic-inductive flowmeter. The measuring tube is used to guide a medium along the longitudinal axis of the measuring tube for a magnetic-inductive flowmeter and has an inflow section, a measuring section following the inflow section as seen in the flow direction, and an outflow section following the measuring section as seen in the flow direction. The inflow section has a cross section that decreases in the flow direction, the measuring section has a constant cross section and is constructed symmetrically with respect to a measuring section symmetry plane, the measuring section symmetry plane extends parallel to the longitudinal axis of the measuring tube, and the outflow section has a cross section that increases in the flow direction. In the case of the measuring tube, the aforementioned task is solved in that the outflow section is constructed at least partially asymmetrically with respect to the measuring section symmetry plane.

[0029] The asymmetry of the outflow section of the measuring tube is designed in particular according to one of the embodiments already described with respect to the magnetic-inductive flowmeter according to the invention. All embodiments made in connection with the magnetic-inductive flowmeter apply accordingly to the measuring tube according to the invention and vice versa.

[0030] In a particularly preferred embodiment of the measuring tube according to the invention, the measuring tube is designed in such a way that the inflow section is also designed at least partially asymmetrically with respect to the measuring section plane of symmetry. In particular, the inflow section is designed asymmetrically over its entire length. The asymmetry of the inflow section is also preferably designed according to one of the embodiments already described for the magnetic-inductive flowmeter according to the invention. The embodiments described here also apply accordingly. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] A number of possible improvements and configurations of the magnetic-inductive flowmeter according to the invention and of the measuring tube according to the invention are now provided in detail. For this purpose reference is made to the claims that are subordinate to the independent claims and to the description of preferred embodiments in conjunction with the drawings. In the drawings:

[0032] Figure 1a shows a magneto-inductive flowmeter with a first embodiment of a measuring tube having an asymmetrical outflow section,

[0033] Figure 1b Shown passing through Figure 1a Cross section of the measuring tube of the magnetic-inductive flow measuring instrument shown in

[0034] Figure 2a A second embodiment of the measuring tube with an asymmetrical outflow section is shown.

[0035] Figure 2b Shown through the Figure 2a The cross section of the measuring tube,

[0036] Figure 3a A schematic illustration of a third embodiment of a measuring tube with an asymmetrical outflow section is shown,

[0037] Figure 3b shows a schematic illustration of a fourth embodiment of a measuring tube with an asymmetrical outflow section,

[0038] Figure 3c shows a schematic illustration of a fifth embodiment of a measuring tube with an asymmetrical inflow section and an asymmetrical outflow section,

[0039] Figure 4 shows a plan view towards a measuring tube with a square measuring section,

[0040] Figure 5 A plan view toward a measuring tube with an oval measuring section is shown, and

[0041] Figure 6 The diagram shows a plan view toward a measuring tube having a circular measuring section. DETAILED DESCRIPTION

[0042] Figure 1a A schematic illustration of a magnetic-inductive flowmeter 1 according to the invention is shown. The magnetic-inductive flowmeter 1 has a measuring tube 2 for guiding the medium along the longitudinal axis L of the measuring tube. Electrodes 3 are used to measure the measurement voltage induced in the medium. The measuring tube 2 has an inflow section 4, a measuring section 5 and an outflow section 6, viewed in sequence along the flow direction of the medium marked by arrows. The inflow section 4 has a circular cross section on its input side 7. The cross section decreases in the extension of the inflow section 4.

[0043] The cross section of the inflow section 4 has a rectangular shape in the region where it transitions into the measuring section 5. The cross section does not change over the length of the measuring section 4, so that the entire measuring section 4 has a rectangular cross section with a constant cross-sectional area.

[0044] Only in the region of the outflow section 6 does the cross section increase again and also change in its shape, so that the outflow section 6 has a circular cross section at its outlet side 8. The measuring section 5 is constructed symmetrically with respect to the measuring section symmetry plane MSE, wherein the measuring section symmetry plane MSE is parallel to the longitudinal axis L of the measuring tube 2. In the embodiment shown, the longitudinal axis L of the measuring tube 2 is not located in the measuring section symmetry plane MSE. This is caused by the fact that the asymmetry of the outflow section 6 with respect to the measuring section symmetry plane MSE is constructed in such a way that the measuring section 5 is offset by a displacement Δ relative to the outflow section 6 and to the inflow section 4 in a direction perpendicular to the measuring section symmetry plane MSE (here downward). The displacement Δ can be very well adjusted in the Figure 1b As can be seen in the figure, a section along the line AA through the measuring tube 2 is shown. The displacement of the measuring section 5 also results in an asymmetrically designed inflow section 4. Therefore, the measuring tube 2 of the magnetic-inductive flowmeter 1 shown is also suitable for bidirectional flow of the medium.

[0045] FIG. 2 shows a measuring tube 2 which has only an asymmetrical outflow section 6. It is important to note that the measuring section 5 is defined as the region of the measuring tube which is penetrated by the magnetic field and in which the actual measurement takes place. This region has a constant cross section over its entire extension. Figure 2a The measuring section 5 of the measuring tube 2 ends before the stepped protrusion 9. The stepped protrusion 9 is arranged in the region of the outflow section 6. Figure 2a And in the shown along the Figure 2a The section plane of the line BB marked in Figure 2b As can be seen in the figure, the stepped projection 9 extends over the entire circumference of the outflow section 6 and causes a reduction in the cross section of the measuring tube in the region of the stepped projection 9. In the exemplary embodiment shown, the cross section of the measuring tube 2 before the stepped projection 9, as viewed in the flow direction, corresponds to the cross section of the measuring tube 2 after the stepped projection 9, as viewed in the flow direction. The asymmetry is achieved in that the step height on a first side 10 of the measuring section symmetry plane MSE is smaller than the step height on a second side 11 of the measuring section symmetry plane MSE. In the embodiment shown, the longitudinal axis L of the measuring tube is located in the measuring section symmetry plane MSE.

[0046] 3 shows a schematic illustration of various measuring tubes 2 in section. The measuring tubes 2 each have an inflow section 4 , a measuring section 5 and an outflow section 6 . Figure 3a A measuring tube 2 is shown in which the asymmetry of the outflow section 6 relative to the measuring section symmetry plane MSE is formed by an insertion element 12 arranged in the outflow section 6 .

[0047] exist Figure 3b In the case of the measuring tube 2 shown in FIG. 1 , the measuring section ends before a bend 13 which reduces the cross section and is located in the region of the outflow section 6 . This means that the asymmetry of the outflow section 6 is Figure 3b In the case of the measuring tube 2 shown in FIG. 1 , the camber 13 is formed by the camber 13. The camber 13 causes a reduction in the cross section in the region of the camber 13. In the exemplary embodiment shown, the cross section of the measuring tube 2 seen in the flow direction before the camber 13 corresponds to the cross section of the measuring tube 2 seen in the flow direction after the camber 13.

[0048] Figure 3c A measuring tube 2 is shown in which both the outflow section 6 and the inflow section 4 are designed asymmetrically with respect to the measuring section symmetry plane MSE. The asymmetry of the two sections is formed by the arrangement of the insertion element 12. Figure 3a Compared to the embedded element 12 shown in Figure 3c The engagement element 12 shown in FIG. 1 is of flatter design.

[0049] Figure 4 , 56 show a schematic top view toward the measuring tube 2. A perspective into the outlet side 8 of the outflow section 6 can be seen. The outflow section 6 has a circular cross section at its outlet side 8. Since the cross section decreases toward the measuring section 5, the Figure 4 , 5 6 and 7 , a cross section of the measuring section 5 can also be seen. Figure 4 , 5 6 serve to illustrate different measuring section symmetry planes MSE for different measuring section cross sections.

[0050] Figure 4 A measuring tube 2 is shown with a measuring section 5 having a square cross section. The corners of the measuring section 5 are slightly rounded. The square measuring section has a total of four measuring section symmetry planes MSE1, MSE2, MSE3 and MSE4, wherein the measuring section symmetry planes MSE1 and MSE2 are each parallel to one side of the cross section, while the measuring section symmetry planes MSE3 and MSE4 intersect the measuring section diagonally.

[0051] exist Figure 5 The measuring tube 2 shown in FIG. 1 has a measuring section 5 with an elliptical cross section. The elliptical measuring section has a total of two measuring section symmetry planes MSE1 and MSE2, wherein the measuring section symmetry plane MSE1 intersects the cross section along its longitudinal sides and the measuring section symmetry plane MSE2 intersects the cross section along its short sides.

[0052] Figure 6 A measuring tube 2 is shown with a measuring section 5 having a circular cross section. The circular measuring section 5 has an infinite number of measuring section symmetry planes MSE, of which three measuring section symmetry planes MSE1 , MSE2 and MSE3 are shown by way of example.

[0053] Reference numerals list

[0054] 1 Magnetic induction flow measuring instrument

[0055] 2 Measuring tube

[0056] 3 Electrodes

[0057] 4 Inflow section

[0058] 5 Measurement section

[0059] 6 Outflow section

[0060] 7 Inlet side of the inflow section

[0061] 8 Discharge side of outflow section

[0062] 9 Stepped protrusion

[0063] 10 Measure the first side of the section

[0064] 11 Second side of measuring section

[0065] 12 Embedded components

[0066] 13 Arch

[0067] L Longitudinal axis of the measuring tube

[0068] MSE measures the segment symmetry plane.

Claims

1. A magnetic-inductive flowmeter (1) for determining the flow of a medium, comprising a measuring tube (2) for guiding the medium along its longitudinal axis (L) and comprising two electrodes (3) for measuring a measuring voltage induced in the medium, wherein: The measuring tube (2) comprises an inflow section (4), a measuring section (5) and an outflow section arranged in sequence along the flow direction of the medium, wherein the inflow section (4) has a cross section which decreases in the flow direction, wherein the measuring section (5) has a constant cross section and is designed symmetrically with respect to a measuring section symmetry plane (MSE), wherein the measuring section symmetry plane (MSE) extends parallel to a longitudinal axis (L) of the measuring tube (2), and wherein the outflow section has a cross section which increases in the flow direction, It is characterized in that The outflow section is at least partially designed asymmetrically with respect to the measuring section symmetry plane (MSE); The asymmetry is formed by a stepped projection (9) in the outflow section which reduces the cross section.

2. The magnetic induction flow measuring instrument (1) according to claim 1, characterized in that: The measuring section (5) has a rectangular cross section, and the measuring section symmetry plane (MSE) is parallel to a long side of the cross section.

3. The magnetic induction flow measuring instrument (1) according to claim 1, characterized in that: The measuring section (5) has a square cross section, and the measuring section symmetry plane (MSE) is parallel to one side of the cross section.

4. The magnetic induction flow measuring instrument (1) according to claim 1, characterized in that: The outflow section is designed asymmetrically over its entire length with respect to the measuring section symmetry plane (MSE).

5. The magnetic induction flow measuring instrument (1) according to claim 1, characterized in that: The outflow section is designed asymmetrically with respect to the measuring section symmetry plane (MSE) over a restricted longitudinal extension.

6. The magnetic induction flow measuring instrument (1) according to claim 1, characterized in that: The stepped projection (9) is formed over the entire circumference of the outflow section, and the stepped projection (9) is at least partially formed flatter on a first side (10) of the measuring section symmetry plane (MSE) than on a second side (11) of the measuring section symmetry plane (MSE).

7. The magnetic induction flow measuring instrument (1) according to claim 1, characterized in that: The inflow section (4) is at least partially designed asymmetrically with respect to the measuring section symmetry plane (MSE).

8. The magnetic induction flow measuring instrument (1) according to claim 7, characterized in that: The inflow section (4) is designed asymmetrically over its entire length.

9. A magnetic-inductive flowmeter (1) for determining the flow of a medium, comprising a measuring tube (2) for guiding the medium along its longitudinal axis (L) and comprising two electrodes (3) for measuring a measuring voltage induced in the medium, wherein: The measuring tube (2) comprises an inflow section (4), a measuring section (5) and an outflow section arranged in sequence along the flow direction of the medium, wherein the inflow section (4) has a cross section which decreases in the flow direction, wherein the measuring section (5) has a constant cross section and is designed symmetrically with respect to a measuring section symmetry plane (MSE), wherein the measuring section symmetry plane (MSE) extends parallel to a longitudinal axis (L) of the measuring tube (2), and wherein the outflow section has a cross section which increases in the flow direction, It is characterized in that The outflow section is at least partially designed asymmetrically with respect to the measuring section symmetry plane (MSE); and The asymmetry is formed by the fact that the insertion element (12) is arranged in the outflow section.

10. The magnetic induction flow measuring instrument (1) according to claim 9, characterized in that: The measuring section (5) has a rectangular cross section, and the measuring section symmetry plane (MSE) is parallel to a long side of the cross section.

11. The magnetic induction flow measuring instrument (1) according to claim 9, characterized in that: The measuring section (5) has a square cross section, and the measuring section symmetry plane (MSE) is parallel to one side of the cross section.

12. The magnetic induction flow measuring instrument (1) according to claim 9, characterized in that: The outflow section is designed asymmetrically over its entire length with respect to the measuring section symmetry plane (MSE).

13. The magnetic induction flow measuring instrument (1) according to claim 9, characterized in that: The outflow section is designed asymmetrically with respect to the measuring section symmetry plane (MSE) over a restricted longitudinal extension.

14. The magnetic induction flow measuring instrument (1) according to claim 9, characterized in that: The inflow section (4) is at least partially designed asymmetrically with respect to the measuring section symmetry plane (MSE).

15. The magnetic induction flow measuring instrument (1) according to claim 14, characterized in that: The inflow section (4) is designed asymmetrically over its entire length.

16. A magnetic-inductive flowmeter (1) for determining the flow of a medium, comprising a measuring tube (2) for guiding the medium along its longitudinal axis (L) and comprising two electrodes (3) for measuring a measuring voltage induced in the medium, wherein: The measuring tube (2) comprises an inflow section (4), a measuring section (5) and an outflow section arranged in sequence along the flow direction of the medium, wherein the inflow section (4) has a cross section which decreases in the flow direction, wherein the measuring section (5) has a constant cross section and is designed symmetrically with respect to a measuring section symmetry plane (MSE), wherein the measuring section symmetry plane (MSE) extends parallel to a longitudinal axis (L) of the measuring tube (2), and wherein the outflow section has a cross section which increases in the flow direction, It is characterized in that The outflow section is at least partially designed asymmetrically with respect to the measuring section symmetry plane (MSE); and The asymmetry is formed by a curvature (13) in the outflow section which reduces the cross section.

17. The magnetic induction flow measuring instrument (1) according to claim 16, characterized in that: The measuring section (5) has a rectangular cross section, and the measuring section symmetry plane (MSE) is parallel to a long side of the cross section.

18. The magnetic induction flow measuring instrument (1) according to claim 16, characterized in that: The measuring section (5) has a square cross section, and the measuring section symmetry plane (MSE) is parallel to one side of the cross section.

19. The magnetic induction flow measuring instrument (1) according to claim 16, characterized in that: The outflow section is designed asymmetrically over its entire length with respect to the measuring section symmetry plane (MSE).

20. The magnetic induction flow measuring instrument (1) according to claim 16, characterized in that: The outflow section is designed asymmetrically with respect to the measuring section symmetry plane (MSE) over a restricted longitudinal extension.

21. The magnetic induction flow measuring instrument (1) according to claim 16, characterized in that: The inflow section (4) is at least partially designed asymmetrically with respect to the measuring section symmetry plane (MSE).

22. The magnetic induction flow measuring instrument (1) according to claim 21, characterized in that: The inflow section (4) is designed asymmetrically over its entire length.

23. A measuring tube (2) for a magnetic-inductive flowmeter (1), the measuring tube being used for guiding a medium along a longitudinal axis (L) of the measuring tube (2), the measuring tube having an inflow section (4), a measuring section (5) following the inflow section (4) as seen in the flow direction, and an outflow section following the measuring section (5) as seen in the flow direction, wherein: The inflow section (4) has a cross section which decreases in the flow direction, wherein the measuring section (5) has a constant cross section and is designed symmetrically with respect to a measuring section symmetry plane (MSE), wherein the measuring section symmetry plane (MSE) runs parallel to the longitudinal axis (L) of the measuring tube (2), and wherein the outflow section has a cross section which increases in the flow direction, It is characterized in that The outflow section is at least partially designed asymmetrically with respect to the measuring section symmetry plane (MSE); The asymmetry is formed by a stepped projection (9) in the outflow section which reduces the cross section.

24. The measuring tube (2) according to claim 23, characterized in that The inflow section (4) is at least partially designed asymmetrically with respect to the measuring section symmetry plane (MSE).

25. The measuring tube (2) according to claim 24, characterized in that The inflow section (4) is designed asymmetrically over its entire length.

26. A measuring tube (2) for a magnetic-inductive flowmeter (1), the measuring tube being used for guiding a medium along a longitudinal axis (L) of the measuring tube (2), the measuring tube having an inflow section (4), a measuring section (5) following the inflow section (4) as seen in the flow direction, and an outflow section following the measuring section (5) as seen in the flow direction, wherein: The inflow section (4) has a cross section which decreases in the flow direction, wherein the measuring section (5) has a constant cross section and is designed symmetrically with respect to a measuring section symmetry plane (MSE), wherein the measuring section symmetry plane (MSE) runs parallel to the longitudinal axis (L) of the measuring tube (2), and wherein the outflow section has a cross section which increases in the flow direction, It is characterized in that The outflow section is at least partially designed asymmetrically with respect to the measuring section symmetry plane (MSE); and The asymmetry is formed by the fact that the insertion element (12) is arranged in the outflow section.

27. The measuring tube (2) according to claim 26, characterized in that The inflow section (4) is at least partially designed asymmetrically with respect to the measuring section symmetry plane (MSE).

28. The measuring tube (2) according to claim 27, characterized in that The inflow section (4) is designed asymmetrically over its entire length.

29. A measuring tube (2) for a magnetic-inductive flowmeter (1), the measuring tube being used for guiding a medium along a longitudinal axis (L) of the measuring tube (2), the measuring tube having an inflow section (4), a measuring section (5) following the inflow section (4) as seen in the flow direction, and an outflow section following the measuring section (5) as seen in the flow direction, wherein: The inflow section (4) has a cross section which decreases in the flow direction, wherein the measuring section (5) has a constant cross section and is designed symmetrically with respect to a measuring section symmetry plane (MSE), wherein the measuring section symmetry plane (MSE) runs parallel to the longitudinal axis (L) of the measuring tube (2), and wherein the outflow section has a cross section which increases in the flow direction, It is characterized in that The outflow section is at least partially designed asymmetrically with respect to the measuring section symmetry plane (MSE); and The asymmetry is formed by a curvature (13) in the outflow section which reduces the cross section.

30. The measuring tube (2) according to claim 29, characterized in that The inflow section (4) is at least partially designed asymmetrically with respect to the measuring section symmetry plane (MSE).

31. The measuring tube (2) according to claim 30, characterized in that The inflow section (4) is designed asymmetrically over its entire length.

Images