Magnetic-inductive flow meter

Abstract

The invention relates to a magnetic-inductive flow meter for determining a flow-rate-based measurement variable of a medium, comprising: - a measuring tube (10) for guiding the medium; - two measuring electrodes (21, 22); - an electronic measuring circuit (30) which is electrically connected to the two measuring electrodes (21, 22), - a coil assembly (41) for generating a magnetic field which at least partly passes through the measuring tube (10), the coil assembly (41) comprising a first coil (45a), the first coil (45a) comprising a first coil body (46a), the first coil body (46a) having a first and second coil core receiving area (SKA1, SKA2), the first coil core receiving area (SKA1) being spatially separated from the second coil core receiving area (SK2), in particular transversely to an imaginary main axis (SHA) of the first coil body (46a), and - a magnetic field guide (40), the magnetic field guide (40) having a first and a second coil core (47a, 47b), the first coil core (47a) being situated in the first coil core receiving area (SKA1), and the second coil core (47b) being situated in the second coil core receiving area (SKA2).

Description

[0001] Magnetic-inductive flow meter

[0002] The invention relates to a magnetic-inductive flow meter for determining a flow velocity-dependent measured quantity of a medium.

[0003] Magnetic-inductive flowmeters are used to determine the flow velocity and / or volumetric flow rate of a free-flowing, electrically conductive medium in a pipeline. A magnetic-inductive flowmeter always includes a magnetic field-generating device designed to produce a magnetic field perpendicular to the horizontal axis of the measuring tube. This is typically achieved using a coil arrangement with a single coil or with several opposing coils. To ensure a largely homogeneous magnetic field, pole pieces can be shaped and attached so that the magnetic field lines run essentially perpendicular to the transverse axis across the entire cross-section of the pipe.A pair of measuring electrodes attached to the outer surface of the measuring tube detects an inductively generated electrical voltage. This voltage arises when a conductive medium flows along the longitudinal axis of the measuring tube under an applied magnetic field. Since the detected voltage depends on the velocity of the flowing medium according to Faraday's law of induction, the flow velocity and, with the addition of a known cross-sectional area of ​​the measuring tube, the volumetric flow rate of the medium can be determined from the voltage.

[0004] DE 10 2015 109 747 A1 and DE 10 2010 001 393 A1 each disclose a magnetic-inductive flowmeter with a magnetic system comprising coil cores made of a multitude of electrical steel sheets stacked and stamped in the longitudinal direction of the measuring tube. A disadvantage of such solutions is that each individual electrical steel sheet must be manufactured in such a way that the end section contacting the measuring tube is adapted to the outer surface of the measuring tube. Thus, a separate coil core is required for each nominal diameter of the measuring tube.

[0005] The invention is based on the objective of providing a remedy.

[0006] The problem is solved by the magnetic-inductive flowmeter according to claim 1.

[0007] The magnetic-inductive flow meter according to the invention for determining a flow velocity-dependent measured quantity of a medium comprises:

[0008] - a measuring tube for guiding the medium;

[0009] - two measuring electrodes;

[0010] - an electronic measuring circuit which is electrically connected to the two measuring electrodes, - a coil arrangement for generating a magnetic field which penetrates the measuring tube at least partially, wherein the coil arrangement comprises a first coil, wherein the first coil comprises a first coil body, wherein the first coil body has a first and second coil core receptacle, wherein the first coil core receptacle is spatially separated from the second coil core receptacle, in particular transversely to an imaginary principal axis of the first coil body,

[0011] - a magnetic field guide, wherein the magnetic field guide comprises a first and a second coil core, wherein the first coil core is arranged in the first coil core receptacle, wherein the second coil core is arranged in the second coil core receptacle.

[0012] Typically, the coils used in conventional magnetic-inductive flowmeters have exactly one coil former. This former is designed to accommodate exactly one coil core. The invention requires that the coil former accommodate at least two separate coil cores. This allows the same measurement performance to be achieved with less material, or even, in some cases, better measurement performance than with conventional magnetic systems. The two coil cores can be identical components, or their sub-units can be identical components.

[0013] Advantageous embodiments of the invention are the subject of the dependent claims.

[0014] One embodiment provides that the first coil body has at least one partition wall which separates the first coil core receptacle from the second coil core receptacle.

[0015] One embodiment provides that the first coil body has a feedthrough chamber through which at least one signal cable, at least partially a level monitoring electrode, at least partially a reference electrode and / or a fixing bolt extends.

[0016] One embodiment provides that the feedthrough chamber lies between the first coil core receptacle and the second coil core receptacle and is separated from the first coil core receptacle by at least one partition wall.

[0017] One embodiment provides that the first and / or second coil core receptacle has an angular, in particular a rectangular, contour in a longitudinal section through the first and / or second coil core receptacle. Another embodiment provides that the first and / or second coil core (each) comprises a plurality N of coil core laminations stacked in the circumferential direction of the measuring tube, wherein at least two adjacent coil core laminations of the plurality of coil core laminations each have a coil core lamination main axis which runs parallel to an imaginary main axis of the first coil body, and wherein the at least two adjacent coil core laminations are positioned offset from each other in the direction of their respective coil core lamination main axis.

[0018] This has the advantage that a magnetic system suitable for magnetic-inductive flowmeters with a nominal diameter range of DN350 to DN900 can be realized with only a few identical parts – some of which only require a simple basic shape. This eliminates the need for diameter-specific coil cores and reduces manufacturing costs.

[0019] Furthermore, this ensures that the magnetic field is coupled into the medium in the most ideal way possible, as air inclusions between the measuring tube and the coil core are avoided.

[0020] One embodiment provides that the first and / or second coil core has a surface that can be described by a first curvature R1, wherein an outer lateral surface of the measuring tube can be described by a second curvature R2, wherein the first curvature R1 does not deviate from the second curvature R2 by more than 50%, in particular not by more than 25% and preferably not by more than 10%.

[0021] One embodiment provides that the coil former has a first collar for the first coil core receptacle, which is designed in such a way as to prevent the first coil core, in particular the coil core laminations, from fanning out, and / or wherein the coil former has a second collar for the second coil core receptacle, which is designed in such a way as to prevent the second coil core, in particular the coil core laminations, from fanning out.

[0022] One embodiment provides that the coil arrangement comprises a second coil, wherein the second coil comprises a second coil body, the second coil body having a third and fourth coil core receptacle, the third coil core receptacle being spatially separated from the fourth coil core receptacle, particularly in the circumferential direction of the measuring tube, the magnetic field guide comprising a third and a fourth coil core, the third coil core being arranged in the third coil core receptacle, the fourth coil core being arranged in the fourth coil core receptacle, the magnetic field guide comprising a first and second magnetic field guide plate, the first magnetic field guide plate connecting the first coil core to the third coil core and the second magnetic field guide plate connecting the second coil core to the fourth coil core.or the first magnetic field guide plate connects the first coil core to the second coil core, and the second magnetic field guide plate connects the third coil core to the fourth coil core.

[0023] One embodiment provides that the first and second magnetic field guide plates are separated from each other by a gap, so that the first magnetic field guide plate is in contact exclusively with the first and third coil cores of the magnetic field guide and the second magnetic field guide plate is in contact exclusively with the second and fourth coil cores of the magnetic field guide.

[0024] One embodiment provides that the first magnetic field guide plate is pressed onto the first coil core via a first fixing body, which is in particular curved and preferably non-magnetic, and / or wherein the second magnetic field guide plate is pressed onto the second coil core via the first fixing body, and in particular directly.

[0025] One embodiment provides that the first fixing body is overbent in the assembled state, so that a bending radius of the first fixing body does not deviate by more than 10%, in particular 5% and preferably 1%, from a bending radius of a surface of the first and / or second coil core facing the first fixing body.

[0026] The invention is explained in more detail with reference to the following figures. They show:

[0027] Fig. 1 : a partial section of a cross-section through an embodiment of the magnetic-inductive flowmeter according to the invention;

[0028] Fig. 2: a further partial section of a cross-section through the design of the magnetic-inductive flowmeter of Fig. 1;

[0029] Fig. 3: a perspective view of the design of the magnetic-inductive flowmeter according to the invention of Fig. 1;

[0030] Fig. 4: an exploded view of a further embodiment of the magnetic-inductive flowmeter according to the invention; and

[0031] Fig. 5: a schematic representation of stacked coil cores. Fig. 1 shows an upper partial view of a cross-section through an embodiment of the magnetic-inductive flowmeter 1a according to the invention. Fig. 2 shows a further partial view of a cross-section through the embodiment of the magnetic-inductive flowmeter 1a according to the invention. Fig. 3 shows a perspective view of the embodiment of the magnetic-inductive flowmeter 1a according to the invention. The magnetic-inductive flowmeter 1a is designed to determine a flow velocity-dependent measured quantity of a medium. The flow velocity-dependent measured quantity is typically the current flow velocity of the flowable and electrically conductive medium to be monitored.Alternatively, the flow velocity-dependent measured quantity can be a volume flow or – if the medium density is known – a mass flow.

[0032] The magnetic-inductive flowmeter 1a comprises a measuring tube 10 for guiding the medium, which is particularly conductive and flowable. The measuring tube 10 includes a support tube 102. This support tube can be metallic or made of an electrically insulating plastic. If the support tube 102 is metallic, its inner surface is usually provided with an electrically insulating material, also referred to as a liner 101. The measuring tube 10 typically has a hollow cylindrical shape, at least in some sections; however, magnetic-inductive flowmeters with a rectangular cross-section are also known. The measuring tube 10 has an inner surface that is in contact with the medium during operation and an outer surface MF that faces away from the medium.The measuring tube 10 itself has a characteristic nominal diameter DN, which is usually between 10 and 3000 millimeters for magnetic-inductive flow meters.

[0033] To determine the measured values ​​of the flow velocity-dependent quantity, the magnetic-inductive flowmeter typically has at least two measuring electrodes 21, 22 (see Fig. 3). The two measuring electrodes 21, 22 are arranged opposite each other and are intersected by an imaginary measuring electrode axis MEA. The measuring electrode axis MEA runs perpendicular to a longitudinal axis LA of the measuring tube and to a principal axis MFA of the generated magnetic field, or to an axis of symmetry of the magnetic field. The measuring electrode axis MEA does not necessarily have to pass through the center point of the measuring tube 2, but can also intersect the measuring tube 10 off-center. The at least two measuring electrodes 21, 22 shown are in contact with the medium; that is, when a medium flows through the measuring tube 10, the at least two measuring electrodes 21, 22 are in direct contact with the medium. For this purpose, at least two measuring electrodes 21, 22 are each inserted into a designated measuring electrode opening (e.g.The measuring electrodes are arranged (e.g., in the form of a through-opening) of the measuring tube 10. However, capacitive measuring electrodes (not shown) are also known which measure through the wall of the support tube 102 and / or the liner 101 and thus do not need to be in direct contact with the medium. The at least two measuring electrodes 21, 22 are electrically connected to an electronic measuring circuit 30 (shown schematically in Fig. 3). The measuring circuit 30 is configured to determine a measuring voltage induced at the two measuring electrodes and to determine the flow velocity-dependent measured quantity as a function of the induced measuring voltage. The measuring circuit 30 can be part of the sensor or part of a transmitter (not shown), as shown.

[0034] Furthermore, magnetic-inductive flowmeters are also known which have two, three, or more measuring electrodes on each side of the measuring tube. A longitudinal plane perpendicular to the measuring tube axis MEA divides the measuring tube into a first and second measuring tube side. The illustrated embodiment of the magnetic-inductive flowmeter 1a has a total of six measuring electrodes 21, 22, 24, 25, 26, 27. Three measuring electrodes are provided per measuring tube side. The three measuring electrodes 21, 24, 25 of the first measuring tube side and / or the three measuring electrodes 22, 26, 27 of the second measuring tube side can be electrically connected (i.e., short-circuited) to each other via an electrically conductive connecting element (cable or sheet metal part).

[0035] To generate a magnetic field that penetrates at least part of the measuring tube 10, the magnetic-inductive flowmeter 1a has a coil arrangement 41. The coil arrangement 41 comprises at least one coil arranged on the outer surface MF of the measuring tube 10. The at least one coil can be a cylindrical coil. Typically, two opposing coils are used.

[0036] The illustrated coil arrangement 41 has a first coil 45a, which itself comprises a first coil former 46a, in particular a monolithic one, around which a coil wire 48 is wound. The coil former 46a can be made of a non-magnetic plastic. According to the invention, the coil former 46a is configured such that it has a first and a second coil core receptacle SKA1, SKA2. The coil core receptacles SKA1, SKA2 can, for example, each be configured as a continuous chamber. According to the invention, the first coil core receptacle SKA1, in particular transversely to an imaginary principal axis SHA of the first coil former 46a, is completely spatially separated from the second coil core receptacle SKA2. This ensures that the coil cores arranged in the respective coil core receptacles are completely magnetically decoupled from one another.The imaginary principal axis SHA of the first coil body 46a runs parallel to the imaginary principal axis MFA of the generated magnetic field and perpendicular to a longitudinal axis LA of the measuring tube. The first coil body 46a can be a plastic part manufactured by injection molding.

[0037] The first coil former 46a can have at least one partition 44a, as shown, which separates the first coil core receptacle SKA1 from the second coil core receptacle SKA2. The partition 44a can extend in the direction of the longitudinal axis LA, with its longitudinal extent being greater than its transverse extent to the longitudinal direction of the measuring tube 10. The partition 44a at least partially delimits the first coil core receptacle SKA1.

[0038] Furthermore, the first coil body 46a can have a feedthrough chamber DK through which at least one signal cable 100, at least partially a level monitoring electrode 20, at least partially a reference electrode 23, and / or a fixing bolt 71 extend. The signal cable 10 is configured to connect the measuring electrodes of one side of the measuring tube, or the measuring electrode of one side of the measuring tube, to the measuring circuit 30. The level monitoring electrode 20 is electrically connected to the measuring circuit 30. This circuit is configured to determine a level in the measuring tube 10, for example, by measuring the impedance at the level monitoring electrode 20. The reference electrode 23 is electrically connected to a reference potential. The fixing bolt is configured to fix the first coil 46a in a fixed position on the measuring tube 10.The feedthrough chamber DK can be located between the first coil core receptacle SKA1 and the second coil core receptacle SKA2 and can be separated from the first coil core receptacle SKA1 by at least one partition wall 44a. The feedthrough chamber DK is free of magnetic or magnetizable materials. For example, the feedthrough chamber DK can be predominantly filled with air or a potting compound (e.g., silicone).

[0039] The first coil former 46a can have a further partition 44b, which at least partially delimits the second coil core receptacle SKA2 and ensures that the first coil core receptacle SKA1 is separated from the second coil core receptacle SKA2. The further partition 44b also separates the second coil core receptacle SKA2 from the feedthrough chamber DK.

[0040] The first and / or second coil core receptacle SKA1, SKA2 can each have a non-circular contour in a longitudinal section, i.e., for example, an angular, particularly a rectangular, contour. The first and / or second coil core receptacle SKA1, SKA2 can each have planar surfaces adapted to a shape or surface of the coil core to be accommodated. In the prior art, coil formers are typically used in which the coil core receptacle has a cylindrical base shape. In the aforementioned case, the coil formers have only exactly one coil core receptacle, which is enclosed by the hollow cylindrical base of the coil former.

[0041] The coil arrangement 41 can further comprise a second coil 45b with a second coil former 46b around which a coil wire 48 is wound. The coil former 46b can have a third and fourth coil core receptacle SKA3, SKA4, which are separated from each other by partitions 44c, 44d. The first and second coil formers 46a, 46b can be identical parts. Furthermore, the magnetic-inductive flowmeter 1a according to the invention has a magnetic field guide 40. The magnetic field guide 40 comprises magnetizable components which are suitable and configured to guide the magnetic field generated by the coil arrangement outside the measuring tube 10. The illustrated magnetic field guide 40 comprises, for example, a first and second coil core 47a, 47b which are configured to increase the magnetic flux density in the first coil 45a.The first coil core 47a is arranged in the first coil core receptacle SKA1 and the second coil core 47b is arranged in the second coil core receptacle SKA2.

[0042] The first coil core 47a can, as shown, comprise a plurality N of coil core laminations 147a, ... , 147n stacked circumferentially around the measuring tube 10. In contrast to what is taught in DE 10 2015 109 747 A1 and DE 10 2010 001 393 A1, the coil core laminations 147a, ... , 147n are stacked transversely to the longitudinal axis LA and not along the longitudinal axis LA of the measuring tube. This has the advantage that the respective end sections of the coil core laminations 147a, ... , 147n do not need to have a shape adapted to the radius of the measuring tube in order to achieve ideal contact between the first coil core 47a and the outer surface of the measuring tube 10. Thus, coil core laminations adapted to the respective nominal diameter of the measuring tube 10 are no longer necessary. At least two adjacent coil core laminations 147i, 147i+1 of the plurality of coil core laminations 147a, ... , 147n each have a coil core lamination main axis SKHA1 , SKHA2 (see Fig.5) which runs parallel to an imaginary principal axis SHA of the first coil body 46a. The at least two adjacent coil core laminations 147i, 147i+1 can be positioned offset from each other in the direction of their respective coil core lamination principal axis SKHA1, SKHA2. Additionally, it may be required that all coil core laminations 147a, ... , 147n are arranged offset from each other in the direction of the imaginary principal axis SHA of the first coil body 46a. The first coil core receptacle SKA1 is designed such that, after the coil core laminations 147a, ... , 147n have been attached, their displacement in the circumferential direction and in the longitudinal direction of the measuring tube 10 is limited. However, displacement in the mounting direction remains possible. Only then is it possible to adapt the contact surface of the first coil core 47a to the outer surface MF of the measuring tube or to a first pole shoe 80a resting on the outer surface MF.Only the first fixing element 50a prevents the individual coil core laminations 147a, ... , 147n from shifting in the assembly direction or against the assembly direction.

[0043] The first coil core 47a can have a surface that can be described by a first curvature R1. The outer surface MF of the measuring tube 10, facing away from the medium, can be described by a second curvature R2. The first curvature R1 does not deviate from the second curvature R2 by more than 50%, in particular not by more than 25%, and preferably not by more than 10%. Preferably, the first curvature R1 is identical to the second curvature R2. The first coil former 46a can have a first collar 72a for the first coil core receptacle SKA1, which is designed such that it prevents the first coil core 47a, in particular the coil core laminations 147a, ... , 147n, from fanning out. The first collar 72a can form part of the boundary of the first coil core receptacle SKA1. Furthermore, the first collar 72a can be described as the enclosure of the end areas of the coil core laminations 147a, ... , 147n.

[0044] The first coil former 46a can further have a second collar 72b for the second coil core receptacle SKA2, which is designed such that it prevents the second coil core 47b, in particular the coil core laminations 147a, ... , 147n forming the second coil core 47b, from fanning out. The second collar 72b can form part of the boundary of the second coil core receptacle SKA2.

[0045] The first coil core 47a and / or the second coil core 47b can be arranged at least in a form-fitting manner, in particular exclusively in a form-fitting manner, in the first coil core receptacle SKA1 or the first and second coil core receptacles SKA1, SKA2.

[0046] Furthermore, the magnetic field guide 40 can include a first pole shoe 80a, in particular a curved one, which rests on the outer surface MF of the measuring tube. The first pole shoe is designed to distribute the magnetic field lines emerging from the first coil. The first coil core 47a and / or the second coil core 47b can rest, at least partially and directly, on the first pole shoe 80a.

[0047] The first pole shoe 80a can comprise two pole shoe parts 80a', 80a" which are spaced apart from each other offset in the direction of the longitudinal axis LA of the measuring tube 10. A gap 81 for guiding a signal cable can thus be present between the two pole shoe parts 80a', 80a". The signal cable serves to connect one of the at least two measuring electrodes to the measuring circuit 30.

[0048] The first coil core 47a and / or the second coil core 47b can be arranged such that it bridges the two pole shoe parts 80a', 80a". The two pole shoe parts 80a', 80a" can each be a strip-shaped sheet made of stacked electrical steel sheets.

[0049] It is advantageous if there is a distance S between the first and second coil cores such that S < 100 millimeters, particularly S < 60 millimeters, and S > 1 millimeter, particularly S > 30 millimeters. The coil core laminations 147a, 147n can be individual electrically insulated sheets. An electrical sheet is typically a cold-rolled strip of iron-silicon alloy. Electrical sheets used in magnetic systems are subject to standards EN 10106 and EN 10107. According to the design, the electrical sheets are loosely stacked. This means that there is no material bond between the individual coil core laminations 147a, ... , 147n. They can therefore be moved relative to each other in the stacked but not yet fully assembled state.This ensures that the contact surface of the coil core adapts to the outer surface of the measuring tube during assembly, thus preventing an air gap.

[0050] The individual coil core laminations 147a, ... , 147n, designed as identical parts, can assume a polygonal (e.g., rectangular) contour. A longitudinal section through the coil core (or the stacked coil core laminations 147a, ..., 147n) extending to the main axis SKHA1, SKHA2 of the individual coil core laminations 147a, ... , 147n can also result in a polygonal (e.g., rectangular) contour.

[0051] Furthermore, at least one coil core lamination 147a, ... , 147n, or all coil core laminations 147a, ... , 147n, can each have a recess 140 for guiding a signal cable. The recess 140 can be located above the gap 81.

[0052] Furthermore, as shown in Fig. 2, the coil arrangement 41 can include a second coil 45b. This coil also has a second coil former 46b, around which a coil wire 48 is wound to form the second coil. The second coil former 46b has a third and fourth coil core receptacle SKA3, SKA4. These are spatially separated in the circumferential direction of the measuring tube 10. The first and second coil formers 46a, 46b can be identical components.

[0053] The magnetic field guide 40 can comprise a third and a fourth coil core 47c, 47d, wherein the third coil core 47c is arranged in the third coil core receptacle SKA3 and the fourth coil core 47d is arranged in the fourth coil core receptacle SKA4. The first, second, third, and fourth coil cores 47a-d can be identical parts, i.e., the coil cores can each be formed from identical coil core laminations.

[0054] The magnetic field guide 40 can further comprise a first and second magnetic field guide plate 43a, 43b, which is configured to guide the magnetic field lines outside the measuring tube from the first coil 46a to the second coil 46b. For this purpose, the first magnetic field guide plate 43a, which connects the first coil core 47a to the second coil core 47b, and the second magnetic field guide plate 43b, which connects the third coil core 47b to the fourth coil core 47d, can be in direct contact with each other. Thus, the end regions of the first and second magnetic field guide plates 43a, 43b can overlap at the level of the measuring electrodes. Alternatively, the first and second magnetic field guide plates 43a, 43b can also be butted together. Furthermore, the first and second magnetic field guide plates 43a, 43b rest on the surfaces of the corresponding coil cores facing away from the measuring tube 10.The magnetic field guide plates positioned above the coil cores offer corresponding magnetic advantages for measurement performance. The magnetic field remains more concentrated on the measuring tube axis, resulting in a lower CALF (Circular Acuity Fault). This allows the width of the magnetic system to be reduced, enabling a slimmer design. The magnetic field guide plates are fixed above the measuring tube 10 using injection-molded plastic spacers 60. The spacers 60 are designed to fit all nominal diameters, varying only in quantity. Cable guides are directly attached to these spacers 60, allowing the grounding cable, signal cable, and / or coil power cable to be routed across the entire length of the measuring tube to the other side. The ends of the magnetic field guide plates are overlapped on the spacer 60 above the signal electrode and secured there. This is achieved using screws or rivets.

[0055] The magnetic-inductive flowmeter 1a can further comprise a first fixing element 50a. This element is designed to fix the first and second magnetic field guide plates 43a, 43b in a fixed position. For this purpose, it is curved and preferably non-magnetic. The first fixing element 50a is arranged such that it presses the first magnetic field guide plate 43a, 43b directly against the first coil core 47a or the first coil core 47a and the second coil core 47b. Furthermore, the first fixing element 50a can be arranged such that it presses the second magnetic field guide plate 43b directly against the second coil core 47b.

[0056] The first fixing element 50a can be bent in the assembled state such that the bending radius of the first fixing element 50a does not deviate by more than 10%, in particular 5% and preferably 1%, from the bending radius of a surface of the first and / or second coil core 47a, 47b facing the first fixing element 50a. The first fixing element 50a can be made of a non-magnetic and also non-magnetizable material. Stainless steel (e.g., 1.4301) is particularly suitable as a material.

[0057] A second fixing body 50b can also be provided, which is arranged opposite the first fixing body and is designed to press the second magnetic field guide plate 43b onto the third and fourth coil cores 47c, 47d or the first magnetic field guide plate 43b onto the third coil core 47c and the second magnetic field guide plate 43b onto the fourth coil core 47d.

[0058] The magnetic-inductive flowmeter 1a can further comprise a housing 200, which is designed to protect the measuring electrodes, measuring circuit, coil arrangement, and magnetic field guide. Magnetic-inductive flowmeters are also known in which the measuring circuit 30 is arranged outside the housing 200 in a separate transmitter housing (not shown).

[0059] Fig. 4 shows an exploded view of a further embodiment of the magnetic-inductive flowmeter 1b according to the invention. Fig. 4 shows the first coil 45a with the coil former 46a and the first and second coil cores 47a, 47b arranged in the first and second coil core receptacles SKA1, SKA2. Fig. 4 also shows the first fixing element 50a. The following description also applies to the second coil (not shown) and the area around the second coil. The embodiment shown differs essentially from the embodiment of Fig.1 to 3 by the fact that the first and second magnetic field guide plates 43a, 43b are separated from each other by an (air) gap 130, such that the first magnetic field guide plate 43a is in contact exclusively with the first coil core 47a and third coil core 47c of the magnetic field guide 40, and the second magnetic field guide plate 43b is in contact exclusively with the second and fourth coil cores 47d of the magnetic field guide 40. There is no direct contact between the two magnetic field guide plates 43a, 43b.

[0060] The magnetic field guide 40 has a first and second magnetic field guide plate 43a, 43b, each configured to guide the magnetic field lines outside the measuring tube 10 from the first coil 46a to the second coil 46b and from the second coil 46b to the first coil 46a, respectively. The two magnetic field guide plates 43a, 43b are arranged such that the first magnetic field guide plate 43a, in particular exclusively, connects the first coil core 47a to the third coil core 47c, and the second magnetic field guide plate 43b, in particular exclusively, connects the second coil core 47b to the fourth coil core 47d.

[0061] The first fixing element 50a can, as shown, at least partially cover the gap 130. The first fixing element 50a is preferably made of a non-magnetic and non-magnetizable material. Alternatively, the first fixing element 50a can also be designed and arranged such that the gap 130 is completely exposed, thus forming an air gap that is uncovered in the radial direction.

[0062] Fig. 5 shows a schematic representation of stacked coil core laminations 147a, ... , 147n, which form a coil core according to the invention. The coil core shown comprises n coil core laminations, where n is a natural number greater than or equal to 2. The two outermost coil core laminations are designated 147a and 147n. Between the two outermost coil core laminations 147a, 147n, n-2 coil core laminations are arranged. Beneath these, there are at least two adjacent coil core laminations 147i, 147i+1, each having contact surfaces that are in contact with each other. The coil core lamination 147i has a coil core lamination main axis SKHA1 and the coil core lamination 147i+1 has a coil core lamination main axis SKHA2. The coil core sheet main axis SKHA1 , SKHA2 are parallel to the assembly direction and define the direction in which the two adjacent coil core sheets 147i,147i+1 can be displaced.In addition to the two adjacent core laminations, further core laminations can also be displaceable along their own core lamination axis. This core lamination axis is perpendicular to a transverse axis of the respective core lamination. Displacement of the core laminations perpendicular to their core lamination axis is limited or prevented by the wall of the coil former that forms the core receptacle.

[0063] REFERENCE MARK LIST

[0064] Magnetic-inductive flowmeter 1a, 1b

[0065] Measuring tube 10

[0066] Level monitoring electrode 20

[0067] Measuring electrode 21, 22, 24, 26, 27

[0068] Reference electrode 23

[0069] Measuring circuit 30

[0070] Magnetic field guidance 40

[0071] Coil arrangement 41

[0072] Magnetic field guide plate 43a, 43b

[0073] Partition wall 44a, 44b

[0074] Coil 45a, 45b

[0075] Coil bodies 46a, 46b

[0076] Coil core 47a, 47b, 47c, 47d

[0077] Coil wire 48

[0078] Polschuh 49a, 49b

[0079] Fixer bodies 50a, 50b

[0080] Holder 60

[0081] Fixing bolt 71

[0082] Collar 72a, 72b

[0083] Polschuh 80a, 80b

[0084] Pole shoe part 80a', 80a"

[0085] Gap 81

[0086] Signal cable 100

[0087] Liner 101

[0088] Carrier tube 102

[0089] Gap 130

[0090] Coil core sheet 147a, ... , 147i, 147i+1, ..., 147n

[0091] Case 200

[0092] Coil core holder SKA1, SKA2, SKA3, SKA4

[0093] Implementing Chamber DK

[0094] Main axis SHA

[0095] Coil core sheet main axis SKHA1, SKHA2

[0096] Outer surface area MF

Claims

PATENT CLAIMS 1. Magnetic-inductive flow meter for determining a flow velocity-dependent measured quantity of a medium, comprising: - a measuring tube (10) for guiding the medium; - two measuring electrodes (21 , 22); - an electronic measuring circuit (30) which is electrically connected to the two measuring electrodes (21 , 22), - a coil arrangement (41) for generating a magnetic field penetrating the measuring tube (10) at least partially, wherein the coil arrangement (41) comprises a first coil (45a), wherein the first coil (45a) comprises a first coil body (46a), wherein the first coil body (46a) has a first and second coil core receptacle (SKA1, SKA2), wherein the first coil core receptacle (SKA1) is spatially separated from the second coil core receptacle (SK2), in particular transversely to an imaginary principal axis (SHA) of the first coil body (46a), - a magnetic field guide (40) wherein the magnetic field guide (40) comprises a first and a second coil core (47a, 47b) wherein the first coil core (47a) is arranged in the first coil core receptacle (SKA1) wherein the second coil core (47b) is arranged in the second coil core receptacle (SKA2).

2. Magnetic-inductive flowmeter according to claim 1, wherein the first coil body (46a) has at least one partition (44a) which separates the first coil core receptacle (SKA1) from the second coil core receptacle (SKA2).

3. Magnetic-inductive flowmeter according to claim 1 or 2, wherein the first coil body (46a) has a feedthrough chamber (DK) through which at least one signal cable, at least partially a level monitoring electrode (20), at least partially a reference electrode (23) and / or a fixing bolt (71) extends.

4. Magnetic-inductive flowmeter according to claim 3, wherein the feedthrough chamber (DK) is located between the first coil core receptacle (SKA1) and the second coil core receptacle (SKA2) and is separated from the first coil core receptacle (SKA1) by the at least one partition wall (44a).

5. Magnetic-inductive flowmeter according to one of the preceding claims, wherein the first and / or second coil core receptacle (SKA1 , SKA2) has an angular, in particular a rectangular, contour in a longitudinal section through the first and / or second coil core receptacle (SKA1 , SKA2).

6. Magnetic-inductive flowmeter according to one of the preceding claims, wherein the first and / or second coil core (47a, 47b) (each) comprises a plurality N of coil core laminations (147a, ... , 147n) stacked in the circumferential direction of the measuring tube (10), wherein at least two adjacent coil core laminations (147i, 147i+1) of the plurality of coil core laminations (147a, ... , 147n) each have a coil core lamination main axis (SKHA1 , SKHA2) which runs parallel to an imaginary main axis (SHA) of the first coil body (46a), wherein the at least two adjacent coil core laminations (147i, 147i+1 ) are positioned offset from each other in the direction of the respective coil core lamination main axis (SKHA1 , SKHA2).

7. Magnetic-inductive flowmeter according to claim 6, wherein the first and / or second coil core (47a, 47b) has a surface which can be described by a first curvature R1, wherein an outer lateral surface (MF) of the measuring tube (10) can be described by a second curvature R2, wherein the first curvature R1 does not deviate from the second curvature R2 by more than 50%, in particular not by more than 25% and preferably not by more than 10%.

8. Magnetic-inductive flowmeter according to one of claims 6 or 7, wherein the coil body has a first collar (72a) for the first coil core receptacle (SKA1) which is designed in such a way as to prevent the first coil core (47a), in particular the coil core laminations (147a, ... , 147n), from fanning out, and / or wherein the coil body has a second collar (72b) for the second coil core receptacle (SKA2) which is designed in such a way as to prevent the second coil core (47b), in particular the coil core laminations (147a, ... , 147n), from fanning out.

9. Magnetic-inductive flowmeter according to one of the preceding claims, wherein the coil arrangement (41) comprises a second coil (45b), wherein the second coil (45b) comprises a second coil body (46b), wherein the second coil body (46b) has a third and fourth coil core receptacle (SKA3, SKA4), wherein the third coil core receptacle (SKA3) is spatially separated from the fourth coil core receptacle (SK4), particularly in the circumferential direction of the measuring tube (10), wherein the magnetic field guide (40) comprises a third and a fourth coil core (47c, 47d), wherein the third coil core (47c) is arranged in the third coil core receptacle (SKA3). wherein the fourth coil core (47d) is arranged in the fourth coil core receptacle (SKA4), wherein the magnetic field guide (40) comprises a first and second magnetic field guide plate (43a, 43b), wherein the first magnetic field guide plate (43a) connects the first coil core (47a) to the third coil core (47c) and the second magnetic field guide plate (43b) connects the second coil core (47b) to the fourth coil core (47d), or the first magnetic field guide plate (43a) connects the first coil core (47a) to the second coil core (47b) and the second magnetic field guide plate (43b) connects the third coil core (47b) to the fourth coil core (47d).

10. Magnetic-inductive flow meter according to claim 9, wherein the first and second magnetic field guide plates (43a, 43b) are separated from each other by a gap (130), so that the first magnetic field guide plate (43a) is in contact exclusively with the first and third coil cores (47c) of the magnetic field guide (40) and the second magnetic field guide plate (43b) is in contact exclusively with the second and fourth coil cores (47d) of the magnetic field guide (40).

11. Magnetic-inductive flowmeter according to claim 9 or 10, wherein the first magnetic field guide plate (43a) is pressed onto the first coil core (47a) via a first fixing body (50a), in particular a bent and preferably non-magnetic, and / or wherein the second magnetic field guide plate (43b) is pressed onto the second coil core (47b) via the first fixing body (50a), in particular directly.

12. Magnetic-inductive flowmeter according to claim 11, wherein the first fixing body (50a) is bent in the assembled state, such that a bending radius of the first fixing body (50a) does not deviate by more than 10%, in particular 5% and preferably 1%, from a bending radius of a surface of the first and / or second coil core (47a, 47b) facing the first fixing body (50a).

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