Magnetic induction type flow measuring instrument and magnetic circuit device

Abstract

The present invention relates to a magnetic-inductive flowmeter having a measuring tube for guiding an electrically conductive medium, a magnetic circuit device extending outside the measuring tube for generating and guiding a magnetic field penetrating the measuring tube at least partially perpendicular to the flow direction of the medium, and two electrodes (4) for dividing a measurement voltage induced in the medium. The present invention aims to provide a magnetic-inductive flowmeter which is distinguished by an improved measurement sensitivity, thereby achieving the above-mentioned goal in that each pole shoe has a first side facing a first coil and a second side opposite to the first side, and in order to input a magnetic field into the pole shoe, at least two input areas are respectively constructed on the first side of the pole shoe.

Description

Technical Field

[0001] The present invention relates to a magnetic-inductive flowmeter having a measuring tube for guiding an electrically conductive medium, a magnetic circuit device extending outside the measuring tube for generating and guiding a magnetic field through the measuring tube at least partially perpendicular to the flow direction of the medium, and two electrodes for dividing a measuring voltage induced in the medium, wherein the magnetic circuit device has at least one first coil and a first pole shoe and a second pole shoe for generating a magnetic field, wherein a magnetic field is formed between the pole shoes, wherein the measuring tube is arranged between the two pole shoes, and wherein the electrodes are arranged on mutually opposite sides of the measuring tube, and wherein a virtual connecting line between the two electrodes extends perpendicularly to the flow direction and perpendicularly to the direction of the magnetic field. Background Art

[0002] The aforementioned magnetic-inductive flowmeters are generally known from the prior art and are used to determine the flow rate of a medium. The measuring principle underlying the flow measurement is based on the charge separation of particles in a magnetic field. This charge separation results in an induced voltage, or measured voltage, which is proportional to the flow velocity of the charge carriers moving in the medium. From this flow velocity, the flow rate in the measuring tube can be inferred. The charge separation principle presupposes that the direction of flow of the medium in the measuring tube and the orientation of the magnetic field penetrating the medium are not aligned in the same direction. While a perpendicular alignment of the measuring tube and the magnetic field is desirable, as this maximizes the charge separation effect, it is not absolutely necessary. A reasonable assessment is that the magnetic field "substantially" penetrates the measuring tube when the magnetic circuit device generates a magnetic field that penetrates the measuring tube at least partially perpendicular to the flow direction, but at least one component of the magnetic field penetrates the measuring tube perpendicular to the flow direction.

[0003] The magnetic circuit arrangement includes at least one coil that generates a magnetic field. The generated magnetic field is usually guided to the pole shoes via magnetic field-guiding elements. The pole shoes serve to guide the magnetic field lines of force out of the magnetic circuit in a defined manner; the magnetic field penetrates the space between the pole shoes. In magnetic-inductive flowmeters, the pole shoes are preferably implemented as pole shoe plates, which have a relatively small thickness and are therefore referred to as pole shoe plates below. However, the present invention is not transferable to other pole shoe designs.

[0004] A magnetic-inductive flowmeter is known from DE 10 2012 014 266 A1. The magnetic circuit arrangement of the magnetic-inductive flowmeter described therein comprises, in addition to two pole plates, a total of four coils that generate a magnetic field. Two coils are arranged on opposite sides of the measuring tube and the pole plates. The two coils on each side are arranged in series, with electrodes arranged between the two coils. The coils are connected to one another and to a pole plate via a respective yoke element, thereby creating a closed magnetic circuit arrangement overall. The magnetic field or its magnetic lines of force generated in the coils are fed into the pole plate centrally via the yoke element on the side of the pole plate facing the coils.

[0005] Because the measuring accuracy of magnetic-inductive flowmeters depends on the strength of the generated magnetic field and its homogeneity, continuous efforts are being made to further optimize the homogeneity of the magnetic field in order to achieve even better measuring results. The external dimensions of magnetic-inductive flowmeters are also important in practice; the goal is to design the measuring instrument itself as compactly as possible so that it can be used in the most space-saving manner possible. Summary of the Invention

[0006] It is therefore an object of the present invention to specify a magneto-inductive flowmeter which is distinguished by improved measuring sensitivity.

[0007] The previously stated and derived tasks are solved in the magneto-inductive flowmeter described at the beginning of this article in that each pole shoe has a first side facing the first coil and a second side opposite the first side, and at least two input areas are respectively constructed on the first side of each pole shoe for inputting the magnetic field into the pole shoe.

[0008] According to the present invention, it was initially recognized that the homogeneity of the magnetic field generated between the pole shoes depends substantially on the input of the magnetic field into the pole shoes, that is, in particular on the number of input regions through which the magnetic field or the magnetic field lines generated by the coil are introduced into the pole shoes. Therefore, unlike in the prior art, the magnetic field generated by the coil is input into the pole shoes via at least two input regions at a first side surface of the pole shoes. In the prior art, each side surface has only one input region.

[0009] The input region is the area where magnetic field lines are introduced into the pole shoe. Therefore, in terms of structural design, the input region is the area where the pole shoe contacts or is connected to other magnetic field-guiding or magnetic field-generating elements of the magnetic circuit device. By forming at least two input regions on one side of the pole shoe, and moreover on the same side of the pole shoe, the homogeneity of the magnetic field between the pole shoes is improved. This improved homogeneity of the magnetic field leads to improved measuring sensitivity of the magneto-inductive flowmeter.

[0010] A design has proven particularly advantageous in which the input region is formed close to the edge, that is, in each case in the outer quarter of the longitudinal extension of the first side surface of the pole shoe. This not only results in a favorable magnetic field distribution between the pole shoes, but also in structural design advantages, which will be discussed in more detail below.

[0011] The input area can be implemented in different ways in terms of design structure. In a preferred design of a magnetic-inductive flowmeter, the coil is arranged on the side of the electrode. In one design, the coil is used to generate the magnetic field. The coil is connected to the first side of the first pole shoe via a substantially Y-shaped yoke element and to the first side of the second pole shoe via another substantially Y-shaped yoke element. Here, the Y arms of the yoke element are connected to the pole shoe, so that each of the two input areas is formed on the first side of the pole shoe. When referring to a Y-shaped yoke element, this refers to all designs in which the yoke element consists of two parts. Such a yoke element, for example, also belongs to the category of Y-shaped yoke elements, in which the Y main trunk turns linearly into the first Y arm, and the second Y arm itself is formed at a right angle and further branches off from the Y main trunk at a right angle. The yoke element can also be configured in an H-shape, for example. The two Y-shaped yoke elements are preferably configured identically.

[0012] Another particularly preferred embodiment of a magnetic-inductive flowmeter is characterized in that the magnetic circuit arrangement includes a second coil, so that the magnetic field passing through the measuring point is generated by the two coils. In a preferred embodiment, the second coil is arranged on the side of the pole shoe opposite the first coil, with the second side of the pole shoe thus facing the second coil. To input the magnetic field into the pole shoe, at least two additional input regions per pole shoe are formed on the second side of the pole shoe. This is preferably achieved by connecting the second coil to the first side of the first pole shoe via a first Y-shaped yoke element and to the first side of the second pole shoe via a second Y-shaped yoke element. The input regions on the second side of the pole shoe are also preferably formed in the outer quarter of the longitudinal extension of the second side of the pole shoe. The magnetic circuit arrangement thus includes a total of two coils and at least four input regions per pole shoe, two of which are formed on the first side of the pole shoe and two on the second side of the pole shoe.

[0013] In another preferred embodiment of the magnetic-inductive flowmeter according to the present invention, the magnetic circuit arrangement also includes two coils. However, unlike the previously described embodiment, the second coil is arranged on the same side of the pole shoe as the first coil. The two coils are preferably arranged one behind the other as viewed in the flow direction, and more preferably, the electrode is arranged between the coils. Each of the two coils inputs a magnetic field into the pole shoe via at least one input region, thus achieving a total of at least two input regions.

[0014] In another embodiment of the magnetic-inductive flowmeter according to the invention, the magnetic circuit device comprises four coils, so that the magnetic field penetrating the measuring tube is generated by the four coils. Two coils are arranged on each side of the measuring tube, that is, on each side of an electrode. The two coils are preferably arranged one behind the other on each side, as viewed in the flow direction. It is particularly preferred that the electrode be arranged further between the two coils, that is, after the first coil and before the second coil, as viewed in the flow direction.

[0015] In this embodiment, it is further provided that each coil is at least indirectly connected to the first pole shoe via an input region and to the second pole shoe via an input region. Thus, with a total of four coils, at least two input regions are formed on the first side of the pole shoe and at least two input regions are also formed on the second side of the pole shoe.

[0016] By preferably constructing the input region in the outer region of the first and second side surfaces of the pole shoe and arranging the coil next to the electrode, i.e. before and after the electrode when viewed in the flow direction, the advantage is achieved that a lot of structural space is provided for the coil, which can thus be constructed to extend from the first pole shoe to the second pole shoe.

[0017] In a preferred embodiment of a magnetic-inductive flowmeter, the coil is designed as a long coil. A long coil is a coil whose length is significantly greater than its diameter. Particularly preferred is a coil in which the coil length corresponds to at least ten times the diameter. The ratio of the coil length to its diameter, when referring to a long coil, depends in particular on the nominal width of the coil. With a nominal width of DN 150, a long coil is defined when the coil length corresponds to at least ten times the diameter. With a nominal width of DN 600 and greater, a long coil is defined when the coil length corresponds to at least twenty times the diameter. Long coils have the advantage over short coils, whose length and coil radius are of the same order of magnitude, that the magnetic field within the coil is uniform, or significantly more uniform, than within a short coil. Furthermore, long coils produce significantly less undesirable stray fields, thereby reducing susceptibility to interference from stray fields. Due to the significantly smaller stray fields, shielding measures for stray fields can be simplified or eliminated. The design according to the invention therefore differs fundamentally from the prior art magnetic-inductive flowmeters described in the introduction to the specification, in which the coil is arranged between the electrode and the pole shoe and is therefore designed to fit into the limited space. Long coils also have the advantage that they can be manufactured in a material-saving manner.

[0018] In the previously described preferred embodiment of the magnetic-inductive flowmeter according to the invention, it is also possible to connect the coil to the pole shoe via a yoke element, in particular also via a Y-shaped yoke element. When using a Y-shaped yoke element, it is then possible to easily implement more than two input regions per side of the pole shoe.

[0019] It is advantageous to design the magnetic circuit of a magnetic-inductive flowmeter to be as simple as possible in terms of structural design, in particular to minimize the number of components used, so as to further improve the uniformity of the magnetic field, since interfering eddy current fields can be generated by the connecting sections or connection points between the two components. In another embodiment of the magnetic-inductive flowmeter, the coil is directly connected to the pole shoe. When the coil is directly connected to the pole shoe, it means that no separate yoke element is used. This can reduce the number of connection points in the magnetic circuit. Preferably, the coils each have a coil core, and the coil core is connected to the pole shoe. The coil core is here understood to be the section surrounded by the coil turns, wherein the coil core can also extend beyond the coil turns without significant difference. The length by which the coil core extends beyond the turns is preferably less than one-tenth of the length of the section of the coil core surrounded by the turns. In particular, the length should only be selected to just allow connection to the pole shoe.

[0020] In a particularly preferred embodiment, the coil core has a groove into which the pole shoe is inserted. The groove is advantageously designed as a slot, wherein the width of the slot-shaped groove preferably corresponds substantially to the thickness of the pole shoe, so that the pole shoe can be inserted into the slot-shaped groove. For this purpose, the pole shoe is preferably correspondingly curved on its first side.

[0021] In another embodiment, the coil is designed in an arc shape, in particular in a circular arc shape. The bending radius of the coil particularly preferably corresponds to the outer radius of the measuring tube, so that the coil can be arranged on the measuring tube in a space-saving manner.

[0022] It is known in the prior art to design a measuring tube such that it has a measuring section with a substantially rectangular cross-section perpendicular to the flow direction. This measuring section of the measuring tube is the area of the measuring tube that is penetrated by the magnetic field. When referring to a substantially rectangular cross-section, the measuring tube is typically designed such that the longitudinal sides of the rectangular cross-section are arranged parallel to one another, while the short sides of the cross-section do not necessarily need to be straight. Rather, the short sides are typically curved. In such measuring tubes, the electrodes are arranged on the short cross-sectional sides of the measuring section. Furthermore, flowmeters with such measuring tubes provide for pole shoes to be arranged on the longitudinal sides of the measuring section, that is, on the long sides of the rectangular cross-section. One embodiment of a magnetic-inductive flowmeter according to the present invention is distinguished by having a measuring tube with a substantially rectangular cross-section, wherein the pole shoes are arranged on the longitudinal sides of the measuring section. To mechanically reinforce the measuring section, reinforcing ribs are formed in the measuring section. The reinforcing ribs are preferably formed on the longitudinal sides of the measuring section. According to the present invention, recesses corresponding to the reinforcement ribs and intended to accommodate the reinforcement ribs are formed in the pole shoe plates arranged on both longitudinal sides of the measuring section, in particular placed on the measuring section. This allows the pole shoe plates to be positioned as close as possible to the measuring tube, thereby minimizing the distance between the two pole shoe plates. Depending on the design of the reinforcement ribs and the corresponding recesses in the pole shoe plates, the reinforcement ribs can also serve to secure the pole shoe plates.

[0023] In another embodiment, the measuring tube has a positioning element and a positioning recess for the positioning element is formed in the pole shoe. In contrast to the reinforcing ribs, the positioning element does not have the function of reinforcing the measuring tube or the measuring section, but serves to position the magnetic circuit device and, in particular, to fix the pole shoe.

[0024] By forming grooves in the pole piece, stray fields and eddy currents in the pole piece are also reduced, thereby further improving the homogeneity of the magnetic field. Furthermore, due to the reduced stray fields and eddy currents, faster switching of the magnetic field is achieved.

[0025] This demonstrates a particularly preferred design for a magnetic-inductive flowmeter in terms of its construction: the first and second pole shoe plates are each formed from a first pole shoe sub-plate and a second pole shoe sub-plate. The first pole shoe sub-plate of the first pole shoe plate and the first pole shoe sub-plate of the second pole shoe plate are connected to each other via magnetic field-guiding elements of the magnetic circuit device, in particular, one or more coils and / or one or more magnetic field-guiding yoke elements. The second pole shoe sub-plate of the first pole shoe plate and the second pole shoe sub-plate are likewise connected to each other via magnetic field-guiding elements of the magnetic circuit device, in particular, one or more coils and / or one or more magnetic field-guiding yoke elements. Thus, the magnetic circuit device as a whole consists of two parts. This design has the particular advantage that it greatly simplifies the installation of the magnetic-inductive flowmeter. The two parts of the magnetic circuit device can be prefabricated and then simply plugged into the measuring tube of the magnetic-inductive flowmeter. If the pole shoe sub-plates also have the previously described positioning recesses, then after the parts of the magnetic circuit device are plugged in, the positioning elements act through the positioning recesses, thereby securing the two parts of the magnetic circuit device to the measuring tube.

[0026] The two-part design of the pole shoe further suppresses the formation of stray fields and eddy currents.

[0027] In an embodiment of the magnetic circuit arrangement with four coils, the corresponding pole shoe plates are connected to one another, for example, by two coils in each case. The second pole shoe plate of the first pole shoe plate and the second pole shoe plate of the second pole shoe plate are then likewise connected to one another by two coils.

[0028] The present invention relates not only to a magnetic-inductive flowmeter but also to a magnetic circuit device for such a device. The magnetic circuit device according to the invention is used to generate and guide a magnetic field and comprises at least one first coil for generating the magnetic field and a first pole plate and a second pole plate, wherein a magnetic field is formed between the pole plates. A measuring tube of the magnetic-inductive flowmeter can be arranged between the pole plates, so that, in operation, the measuring tube is penetrated by the magnetic field.

[0029] The magnetic circuit device according to the present invention is outstanding in that each pole shoe has a first side facing the first coil and a second side opposite the first side, and at least two input points per pole shoe are respectively formed on the first side of the pole shoe for inputting the magnetic field into the pole shoe.

[0030] The magnetic circuit device according to the present invention can be designed, in particular, according to at least one of the features characterizing the magnetic circuit device of the magnetic-inductive flowmeter according to the present invention, as described above. Therefore, all statements regarding advantageous different design options made in conjunction with the magnetic circuit device of the magnetic-inductive flowmeter according to the present invention also apply to the magnetic circuit device according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] There are now numerous possibilities for designing and expanding the magnetic-inductive flowmeter according to the invention and the magnetic circuit arrangement according to the invention. Reference is made to the claims subordinate to the independent claims and to the description of preferred embodiments in conjunction with the drawings. In the drawings:

[0032] FIG1 is a first design of a magnetic induction flowmeter with a first design of a magnetic circuit device;

[0033] Figure 2 It is the second design of the magnetic circuit device;

[0034] Figure 3 It is the third design of the magnetic circuit device;

[0035] FIG4 is a magnetic induction flow meter with a fourth design of a magnetic circuit device;

[0036] Figure 5 In a first perspective view, the magnetic circuit device of FIG. 4 is shown;

[0037] FIG6 shows the magnetic circuit device of FIG4 in a second perspective view;

[0038] Figure 7 In a third perspective view, the magnetic circuit device of FIG. 4 is shown;

[0039] Figure 8 It is the fifth design of the magnetic circuit device;

[0040] Figure 9 is a measuring tube of a magnetic-inductive flowmeter; and

[0041] Figure 10 It is the sixth design of the magnetic circuit device. DETAILED DESCRIPTION

[0042] Figure 1 shows a magnetic-inductive flowmeter 1 with a measuring tube 2, which is used to guide an electrically conductive medium. The magnetic-inductive flowmeter 1 has a magnetic circuit device 3 extending outside the measuring tube 2 for generating and guiding a magnetic field at least partially perpendicular to the flow direction of the medium through the measuring tube 2. The flow direction of the medium is indicated by an arrow. Furthermore, the magnetic-inductive flowmeter 1 has two electrodes 4, which are used to divide the measurement voltage induced in the medium. Electrodes 4 are not visible in Figure 1. The magnetic circuit device 3 also has a coil 5 for generating a magnetic field and a first pole plate 6 and a second pole plate 7. The measuring tube 2 is arranged with a measuring section 8 between two opposing pole plates 6 and 7. A magnetic field is generated between the pole plates 6 and 7, which penetrates the measuring tube 2. The two electrodes 4 are also arranged on opposite sides of the measuring tube 2, with an imaginary connecting line (not shown) between the two electrodes 4 extending perpendicular to the flow direction and perpendicular to the direction of the magnetic field.

[0043] The two pole shoes 6, 7 are designed such that they have a first side 9 and a second side 10. The first side 9 of the pole shoes 6, 7 faces the coil 5, and the second side 10 is opposite the first side 9, thus being located on the side of the pole shoes 6, 7 facing away from the coil 5. To input the magnetic field generated in the coil 5 into the pole shoes 6, 7, two input regions 11 are formed on the first side 9 of each pole shoe 6, 7. The input regions 11 are located in the outer quarter of the longitudinal extension of the first side 9 of each pole shoe 6, 7. The input regions 11 are thus formed in the edge regions of the pole shoes 6, 7. This design of the magnetic circuit device 3 ensures that a uniform magnetic field is formed between the two pole shoes 6, 7. To input the magnetic field generated in the coil 5 into the pole shoes 6, 7, the coil 5 is connected to both the first pole shoe 6 and the second pole shoe 7 via a Y-shaped yoke element 12.

[0044] exist Figure 2 shows another embodiment of the magnetic circuit device 3. In the embodiment shown, the magnetic circuit device has two coils 5, so that the magnetic field penetrating the measuring tube 2 is generated by the two coils 5. The second coil 5 is arranged on the side of the pole shoe 6, 7 opposite the first coil 5, so that the second side 10 of the pole shoe 6, 7 faces the second coil 5. To input the magnetic field generated by the second coil 5, two additional input regions 11 are formed on the second side 10 of each pole shoe 6, 7. Thus, a total of two coils 5 are used to generate the magnetic field, with a total of four input regions 11 being formed for each pole shoe 6, 7. The second coil 5 is likewise connected to the pole shoe 6, 7 in the input regions 11 via a Y-shaped yoke element 12. The coil 5 is designed as an elongated coil.

[0045] In the design of the magnetic circuit device 3 shown in Figures 1 and 2, one or more coils 5 are arranged in close proximity to the electrode 4, that is, at the same level as the electrode 4, as viewed in the flow direction. Due to the close proximity of the coil 5 to the electrode 4, stray fields from the coil 5 may affect the electrode 4 during operation of the magnetic-inductive flowmeter 1. This influence can be minimized by arranging a shielded metal housing around the coil 5. The metal housing is preferably designed to absorb undesired stray fields and couple them into the pole pieces 6 and 7. The metal housing is not shown in the figures.

[0046] Figure 3 Another embodiment of a magnetic circuit device 3 with two coils 5 is shown. Figure 2 The illustrated embodiment differs in that the two coils 5 are not arranged centrally on the second side 9 of the pole shoe plates 6, 7, but, viewed in the flow direction, are arranged at the level of the inlet point 11. This arrangement of the coils 5 has the advantage that the influence of the coils 5 on the electrodes 4 is minimized, since the distance between the electrodes 4 and the coils 5 is increased.

[0047] The electrodes 4 and the coils 5 are arranged one behind the other, viewed in the flow direction, and are not arranged at the same height. In this embodiment, the yoke element 12 is of H-shaped design.

[0048] FIG4 shows another embodiment of a magnetic-inductive flowmeter 1 , in which the magnetic-inductive flowmeter 1 includes a measuring tube 2 and a magnetic circuit 3 . Electrodes 4 are also provided for dividing the measuring voltage. The magnetic circuit 3 is particularly well visible in the perspective view shown. The magnetic circuit 3 includes a total of four coils 5 , which are designed to generate a magnetic field. Two of the coils 5 are arranged on a first side 9 of the pole shoes 6 , 7 , while the other two coils 5 are arranged on a second side 10 of the pole shoes 6 , 7 . The two coils 5 on each side of the pole shoes 6 , 7 are arranged one behind the other and parallel to one another, as viewed in the flow direction. One or more electrodes 4 are arranged on each side between the two coils 5 , that is, after the first coil 5 and before the second coil 5 , as viewed in the flow direction. Preferably, and as shown, the coils 5 are arranged at equal distances from the electrodes. Each of the coils 5 is connected to the pole shoes 6 , 7 via an input region 11 . Each of the coils 5 is thus connected to the pole shoe 6 via an input region 11 and to the second pole shoe 7 via another input region 11. Not shown, but encompassed by the invention, is the possibility that each of the four coils 5 is connected to the pole shoe 6, 7 via more than one input region 11. This can be done as in Figures 1 to 3 This is achieved, for example, by using a Y-shaped yoke element, as shown in FIG.

[0049] As can be seen in the figure, coil 5 is designed as a long coil. The advantage of a long coil is that the coil length l corresponds to a multiple of the coil diameter; in particular, the coil length l corresponds to at least ten times the diameter. This results in a uniform magnetic field within the coil. Furthermore, significantly less undesirable stray fields occur, which has a positive impact on interference susceptibility and improves energy efficiency. Furthermore, the use of a long coil eliminates the need for shielding measures against any stray fields that occur, or significantly simplifies these measures.

[0050] In addition, especially in Figure 5 and 7 As can be seen in the figure, the coil 5 is designed in the shape of a circular arc. The radius of the circular arc is matched to the measuring tube geometry, that is, to the outer diameter of the arc-shaped area of the measuring section 8 of the measuring tube 2, so that the coil 5 can be arranged closely to the measuring tube 2, so that a magnetic circuit device 3 can be formed as a whole, which is very close to the measuring section 8 of the measuring tube 2. In this way, a compact magnetic-inductive flowmeter 1 can be formed in a simple way. The coil 5 has a coil core 14, which is essentially surrounded by the turns of the coil 5 and protrudes from the turns of the coil by an insignificant part. The protruding part of the coil core 14 is Figure 7 , which can be clearly seen in FIG. To reduce the number of connection points within the magnetic circuit device 3 and thus reduce potential sources of eddy current fields or magnetic stray fields, in the illustrated embodiment, the pole shoe core 14 is directly connected to the pole shoe plates 6, 7. To this end, the coil core 14 has a groove 15 at each end, which is designed as a slot and into which the pole shoe plates 6, 7 are inserted. The pole shoe plates 6, 7 thus have a connecting section 16 connected to the coil core 14. In the illustrated embodiment, the connecting section 16 of the pole shoe plates 6, 7 is designed to be curved.

[0051] In order to reinforce the measuring section 8, reinforcing ribs 17 are formed on the measuring tube 2 in the region of the measuring section 8. The pole shoe plates 6, 7 of the magnetic circuit device 3 have corresponding recesses 18 for accommodating the reinforcing ribs 17. These recesses 18 for the reinforcing ribs can be particularly well positioned in the measuring tube 2. Figure 5 and Figure 6 As can be seen in the figure, a further perspective view is shown in the figure Figure 4 Magnetic circuit device 3 shown. By forming recesses 18 for reinforcing ribs 17, it is ensured that pole shoes 6, 7 are arranged very close to measuring section 8 and therefore close to each other, thereby improving the homogeneity of the magnetic field formed between pole shoes 6, 7. In addition, the formation of stray fields and eddy currents is reduced by the recesses 18, thereby further improving the homogeneity of the magnetic field formed between pole shoes 6, 7.

[0052] In order to fix and position the magnetic circuit device 3 on the measuring tube 2, a positioning element 19 is provided, which is particularly Figure 4As can be seen in FIG. Each side, i.e., each pole shoe 6, 7, is provided with a total of four positioning elements 19. The pole shoes 6, 7 have corresponding positioning grooves 20 through which the positioning elements 19 are guided. The formation of the positioning grooves 29 also reduces the formation of stray fields and eddy currents.

[0053] Particularly advantageous is a design in which the pole shoe plates 6 and 7 are constructed from two parts: the first pole shoe plate 6 includes a first pole shoe sub-plate 21 and a second pole shoe sub-plate 22, and the second pole shoe plate 7 includes a first pole shoe sub-plate 23 and a second pole shoe sub-plate 24. The first pole shoe sub-plate 21 of the first pole shoe plate 6 is connected to the first pole shoe sub-plate 23 of the second pole shoe plate 7 via a coil 5. The second pole shoe sub-plate 22 of the first pole shoe plate 6 is connected to the second pole shoe sub-plate 24 of the second pole shoe plate 7 via two further coils 5. The entire magnetic circuit device 3 is thus constructed from two parts, namely, a first part 25 and a second part 26 that are not connected to each other. This design has the advantage of significantly simplifying the assembly of the magnetic circuit device. The two parts 25 and 26 can, for example, be plugged into the measuring section 8 of the measuring tube 2. After the two parts 25 and 26 are plugged in, the positioning element 18 can then be connected to the measuring tube 2 through the positioning opening 20. Alternatively, the positioning element 19 can be connected to the measuring tube 2 or formed integrally with it, and the parts 25, 26 can be locked with the positioning element 19 when inserted into the measuring section 8 of the measuring tube 2. The two parts 25, 26 of the magnetic circuit device 3 are thus fixed to the measuring tube 2 and can no longer perform any significant relative movement relative to the measuring tube 2. Figure 5 and 6 The magnetic circuit device 3 consisting of two parts can be seen very clearly. Figure 5 Shows a three-dimensional view of the magnetic circuit device 3. Figure 6 A top view of the magnetic circuit device 3 is shown in FIG.

[0054] The magneto-inductive flowmeter 1 can have a measuring tube 2 with measuring sections of different geometries. Figure 1 and 4 The measuring section 8 shown in FIG is designed to be rectangular and therefore has a rectangular flow cross section. In particular, the measuring section has two flat sides, on which the pole shoe plates are arranged. In another embodiment, the measuring section 8 of the measuring tube 2 has a circular flow cross section. Figure 7 In FIG. 3 , a magnetic circuit device 3 is shown, which is advantageously designed for use with a measuring tube 2 having a measuring section 8 with a rectangular flow cross section, whereas in FIG. Figure 8 , a magnetic circuit arrangement 3 is shown, which is advantageously designed for use with a measuring tube 2 having a measuring section 8 with a circular flow cross section.

[0055] The pole shoe plates 21, 22, 23, 24 are divided into a first section 28 and a second section 29 in each of the two embodiments. The first section 28 and the second section 29 are at an inner angle to each other. Layout. Interior corner This refers to the angle between the first section 28 and the second section 29 on the side of the pole shoe plates 21 , 22 , 23 , 24 facing the measuring tube 2 arranged between the pole shoe plates 6 , 7 . This is preferably achieved by bending the first section 28 away from the second section 29. Figure 7 In the magnetic circuit device 3 shown, the inner angle Greater than 180°. This results in a nearly rectangular shape of the magnetic circuit device 3. Figure 8 In the magnetic circuit device 3 shown, the inner angle Less than 180°. This results in a nearly circular shape of the magnetic circuit device 3.

[0056] exist Figure 2 and 3 The magnetic circuit device 3 shown in FIG. 1 also has an internal angle between the first section 28 and the second section 29 that is greater than 180°. Since the pole shoe plates 6, 7 are constructed in one piece, they have a first section 28 and two second sections 29, which adjoin the first section 28 on both sides. The magnetic circuit device 3 shown is accordingly designed for a measuring tube 2 with a measuring section 8 having a rectangular flow cross section.

[0057] Figure 9 The measuring tube 2 of a magnetic-inductive flowmeter 1 is shown. The rectangular measuring section 8, which has reinforcing ribs 17, is particularly clearly visible here. The reinforcing ribs 17 are arranged in a cross-shaped pattern on the measuring section 8. Furthermore, the fastening sections 27 for fastening positioning elements 19 can be seen. These positioning elements 19 can preferably be screwed into the measuring tube 2, for example. The fastening sections 27 then have a counterthread corresponding to the thread formed on the positioning elements 19.

[0058] Figure 10 Another view of a magnetic circuit device 3 is shown. The magnetic circuit device 3 has two pole shoes 6, 7 and also two coils 5. Both coils 5 are arranged on the first side 9 of the pole shoes 6, 7. In the example shown, the pole shoes 6, 7 are designed so that they do not have additional positioning recesses 20. Although not shown, all designs of the pole shoes 6, 7 as described above in conjunction with the two coils arranged on the first side 9 of the pole shoes 6, 7 are part of the present invention.

[0059] Reference Signs List

[0060] 1 Magnetic induction flow meter

[0061] 2 Measuring tube

[0062] 3 Magnetic circuit device

[0063] 4 electrodes

[0064] 5 Coils

[0065] 6 First pole shoe plate

[0066] 7 Second pole shoe

[0067] 8 measurement sections

[0068] 9. First side of the pole shoe

[0069] 10 Second side of the pole shoe

[0070] 11 Input Area

[0071] 12 Yoke element

[0072] 14 Coil core

[0073] 15 grooves

[0074] 16 Connection section of the pole shoe

[0075] 17 reinforcement ribs

[0076] 18 Grooves for reinforcing ribs

[0077] 19 Positioning elements

[0078] 20 Positioning groove

[0079] 21 First pole shoe sub-plate of the first pole shoe plate

[0080] 22 The second pole shoe sub-plate of the first pole shoe plate

[0081] 23 First pole shoe sub-plate of the second pole shoe plate

[0082] 24 The second pole shoe sub-plate of the second pole shoe plate

[0083] 25 The first part of the magnetic circuit device

[0084] 26 The second part of the magnetic circuit device

[0085] 27 Fastening section for positioning element

[0086] 28 First Segment

[0087] 29 Second Section

Claims

1. A magnetic-inductive flowmeter (1) comprising a measuring tube (2) for guiding an electrically conductive medium, a magnetic circuit device (3) extending outside the measuring tube (2) for generating and guiding a magnetic field at least partially perpendicular to the flow direction of the medium through the measuring tube (2), and two electrodes (4) for dividing a measurement voltage induced in the medium, wherein: The magnetic circuit device (3) comprises at least one first coil (5) for generating a magnetic field and a first pole shoe (6) and a second pole shoe (7), wherein a magnetic field is formed between the pole shoe plates (6, 7), wherein the measuring tube (2) is arranged between the two pole shoe plates (6, 7), and wherein the electrodes (4) are arranged on mutually opposite sides of the measuring tube (2) and a fictitious connecting line extends between the two electrodes (4) perpendicular to the flow direction and perpendicular to the magnetic field direction. It is characterized by: Each pole shoe (6, 7) has a first side surface (9) facing the first coil (5) and a second side surface (10) opposite the first side surface (9), and in order to input a magnetic field into the pole shoe (6, 7), at least two input areas (11) of each pole shoe (6, 7) are respectively configured on the first side surface (9) of the pole shoe (6, 7), and the coil (5) is configured as an elongated coil, wherein the length (l) of the coil (5) corresponds to at least ten times the diameter of the coil (d).

2. The magnetic-inductive flowmeter (1) according to claim 1, characterized in that The input regions (11) are each formed in the outer quarter of the longitudinal extension of the first side surface (9) of the pole shoe plates (6, 7).

3. The magnetic-inductive flowmeter (1) according to claim 1 or 2, characterized in that The first coil (5) is arranged on the side of the electrode (4) and is connected to the pole shoe plates (6, 7) at the input region (11) via a respective Y-shaped yoke element (12).

4. The magnetic-inductive flowmeter (1) according to claim 1 or 2, characterized in that The magnetic circuit device (3) has a second coil (5), so that the magnetic field passing through the measuring tube (2) is generated by the two coils (5), the second coil (5) is configured as an elongated coil (5) and is arranged on the side of the pole shoe (6, 7) opposite the first coil (5), so that the second side (10) of the pole shoe (6, 7) faces the second coil (5), and for inputting the magnetic field into the pole shoe (6, 7), at least two further input areas (11) per pole shoe (6, 7) are configured on the second side (10) of the pole shoe (6, 7).

5. The magnetic-inductive flowmeter (1) according to claim 1 or 2, characterized in that The magnetic circuit device (3) has a second coil (5), so that the magnetic field passing through the measuring tube (2) is generated by two coils (5), and the second coil is constructed as an elongated coil (5) and is arranged on the same side of the pole shoe plate (6, 7) as the first coil (5).

6. The magnetic-inductive flowmeter (1) according to claim 1 or 2, characterized in that The magnetic circuit device (3) has four coils (5), so that the magnetic field penetrating the measuring tube (2) is generated by the four coils (5), the coils (5) are configured as elongated coils, two coils (5) are arranged one behind the other on the side of each electrode (4) when viewed in the flow direction, and each coil (5) is at least indirectly connected to the first pole shoe (6) and the second pole shoe (7) via an input region (11), in particular, the two coils (5) on each side are arranged parallel to each other, in particular, each electrode (4) is arranged between the coils (5) on one side when viewed in the flow direction.

7. The magnetic-inductive flowmeter (1) according to claim 1 or 2, characterized in that The coil (5) or the coils (5) are configured in an arc shape.

8. The magnetic-inductive flowmeter (1) according to claim 6, characterized in that The coils are directly connected to the pole shoes (6, 7), in particular the coils (5) each have a coil core (14), and the coil core (14) is connected to the pole shoes (6, 7).

9. The magnetic-inductive flowmeter (1) according to claim 1 or 2, characterized in that The measuring tube (1) has a rectangular measuring section (8), wherein the pole shoe plates (6, 7) are arranged on the longitudinal sides of the measuring section (8), the measuring tube (2) has reinforcing ribs (17), and grooves (18) corresponding to the reinforcing ribs (17) are formed in the pole shoe plates (6, 7) for the reinforcing ribs (17).

10. The magnetic-inductive flowmeter (1) according to claim 1 or 2, characterized in that The measuring tube (2) has a positioning element (19), and a positioning recess (20) for the positioning element (19) is formed in the pole shoe plates (6, 7).

11. The magnetic-inductive flowmeter (1) according to claim 1 or 2, characterized in that The first pole shoe plate (6) and the second pole shoe plate (7) are respectively formed by a first pole shoe sub-plate (21, 23) and a second pole shoe sub-plate (22, 24); the first pole shoe sub-plate (21) of the first pole shoe plate (6) and the first pole shoe sub-plate (23) of the second pole shoe plate (7) are connected to each other, in particular, by one or more coils (5) and / or one or more magnetic field guiding yoke elements (12); and the second pole shoe sub-plate (22) of the first pole shoe plate (6) and the second pole shoe sub-plate (24) of the second pole shoe plate (7) are connected to each other, in particular, by one or more coils (5) and / or one or more magnetic field guiding yoke elements (12); thus, the magnetic circuit device (3) as a whole consists of two parts.

12. A magnetic circuit device (3) for a magnetic-inductive flowmeter (1) for generating and guiding a magnetic field, the magnetic circuit device comprising at least one first coil (5) for generating a magnetic field and a first pole shoe (6) and a second pole shoe (7), wherein: A magnetic field is formed between the pole shoes (6, 7), wherein a measuring tube (2) can be arranged between the pole shoes (6, 7). It is characterized in that each pole shoe (6, 7) has a first side surface (9) facing the first coil (5) and a second side surface (10) opposite the first side surface (9), and in order to input the magnetic field into the pole shoe (6, 7), at least two input areas (11) of each pole shoe (6, 7) are respectively configured on the first side surface (9) of the pole shoe (6, 7), and the coil (5) is configured as an elongated coil, wherein the length (l) of the coil (5) corresponds to at least ten times the diameter of the coil (d).

13. The magnetic circuit device (3) according to claim 12, characterized in that The magnetic circuit arrangement (3) is designed according to at least one of the features characterizing the magnetic circuit arrangement (3) according to claims 2 to 11.

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