DE102007004826A1 - Measuring device for magnetically inductive flow meter, has measurement cross section for flow measure of medium flowing through measurement cross section - Google Patents

Abstract

The measuring device (1) has a measuring tube (2), which has a measurement cross section (5) for flow measure of the medium flowing through the measurement cross section. The measuring device also has a guiding system (4) for retaining and positioning a magnetic field generation unit and two measuring electrodes (3) in the area of the measurement cross section. The measuring tube has polyetheretherketone (PEEK) and particularly, completely made of polyetheretherketone. An independent claim is also included for a method for manufacturing a measuring device.

Description

The The invention relates to a measuring device for or in a magnetic inductive flowmeter, a method for producing such a measuring device and a magnetic inductive flowmeter.

U_i

= induzierte Spannung

k

= mediumabhängige Konstante

B →

= Magnetfeldstärke

D

= Messelektrodenabstand

ν →

= mittlere Geschwindigkeit des Mediums.

The invention relates to the field of measurement technology for pipelines. Pipelines are used in particular to transport liquid or gaseous media. When transporting them, there is often a need to determine the exact flow rate of the medium. This is possible using the principle of magnetic induction. The flow rate can be determined with the aid of a magnetic field and two measuring electrodes. The generated magnetic field penetrates the measuring tube and the medium flowing in it. This magnetic field should be aligned perpendicular to the flow direction of the medium to be measured and thus to the tube longitudinal axis. If a medium containing charge carriers is penetrated by the magnetic field, the charge carriers are deflected by the magnetic field transversely to the direction of flow and transversely to the magnetic field. If measuring electrodes are located on the tube walls, a voltage drops between them. One speaks of an induced voltage that can be tapped and measured via the measuring electrodes. Preferably, the measuring electrodes are aligned on the tube walls both perpendicular to the magnetic field and perpendicular to the tube longitudinal axis. Simplified then applies the context: U i = k · B → · D · ν → With

U _i

= induced voltage

k

= medium-dependent constant

B →

= Magnetic field strength

D

= Measuring electrode distance

ν →

= mean velocity of the medium.

From this context, it is apparent that with a constant magnetic field B → and a constant measuring tube inner diameter (measuring electrode distance) D, the induced voltage U _i increases proportionally with increasing flow velocity v → of the medium. As a result, the flow rate and thus the amount of the medium can be determined easily and reliably.

Essential for this Measuring principle is the orthogonal orientation of the magnetic field with respect to longitudinal axis of the measuring tube and the measuring electrodes. Furthermore, it should be avoided that the magnetic field in the operation of the measuring device with respect Displaced measuring tube and the measuring electrodes. Furthermore, should at the alignment of different measuring devices of a series of the magnetic field the measuring tube reproducibly be consistent.

Become frequent to guarantee these aspects elaborate Apparatus or constructions for positioning and holding a magnetic field generating device used on the measuring tube. This elaborate Apparatuses require relatively high Cost of the whole construction. additionally are time-consuming in the assembly of the magnetic field generating device Adjustment work necessary, to ensure an exact arrangement of this device on the measuring tube, so as to ensure a reproducible flow measurement. Shifts in operation, for example due to vibrations, have to these adjustments are made again.

In front In this background, the present invention has the object a simple yet effective way to hold and position to provide a magnetic field generating device on a measuring tube and additionally a high effectiveness to ensure the magnetic field generating device.

These The object is achieved by a Measuring device with the features of claim 1 and / or with a measuring device with the features of claim 44 and / or by a flow meter with the features of Pa tentanspruches 54 solved. Further, in claim 59, a method for producing the Measuring device according to the invention described.

Accordingly, a measuring device for or in a flowmeter provided with a measuring tube, which has a measuring cross section for flow measurement has a medium flowing through the measuring cross-section and which beyond molded guide means for holding and positioning a magnetic field generating device has in the region of the measuring cross-section. Further, in the area of the measuring cross section measuring electrodes arranged such that a dependent of the flow rate electrical signal can be tapped if a magnetic field is the measuring cross section penetrates.

Furthermore, a measuring device equipped with a magnetic field generating device is preferably proposed. The measuring device has the already explained measuring tube and the measuring electrodes. Furthermore, the equipped measuring device includes a magnetic field generating device, which is arranged between the guide means such that the magnetic field generating device located in the immediate vicinity of the measuring cross section and generates a magnetic field perpendicular to the longitudinal axis of the measuring tube. Due to the immediate proximity of the magnetic field generating device to the measuring cross section only a small field strength for the penetration of the measuring tube and the medium flowing through it is necessary.

Further a magnetically inductive flow meter is provided, which is the measuring device according to the invention having.

Of Another is a method of manufacturing a measuring device for or provided in a magnetic inductive flowmeter. In this process At the beginning, the measuring electrodes are placed in an injection mold, being the cavity the injection mold formed as a negative to a measuring tube is. In a second process step, a plastic melt into the cavity the injection mold injected until it is completely filled, with the measuring electrodes be enveloped by the melt.

Of the Invention is based on the idea, a measuring device with a To provide measuring tube on which a magnetic field generating device reliable and is exactly positioned. To accomplish this, will be on the measuring tube molded Füh medium provided. By a suitable embodiment of the guide means magnetic field generating devices mounted with different geometries and characteristics on the measuring tube become. The magnetic field generating device can thus be connected to the respective Be adapted application. About that It is also possible relatively long guideways to lead to realize the magnetic field generating device. By the exact Positioning is an accurate alignment of the field generated by the magnetic field generating device Magnetic field with respect the measuring electrodes possible and thus a very accurate and reproducible induced voltage tapped.

Furthermore do not have the guide means only a positioning function, but additionally holding the magnetic field generating device on the measuring tube. Holding the magnetic field generating device in at least five degrees of freedom (two translational + three rotatory) is through such guiding means easy to implement. As a result, in particular the handling of Simplified measuring device during assembly.

In the dependent claims find advantageous embodiments, developments and improvements the invention.

Prefers are the guiding means in one piece with manufactured the measuring tube. Unitary is to be understood as meaning that between the measuring tube and the guide means no seam or the like is present. By an integral structure of the measuring device can the necessary number of steps in their production be reduced. A production is thus extremely economical possible. Alternatively you can the guiding means also later be molded to the measuring tube. If a polymeric material is used is, for example, by injecting the guide means possible to the measuring tube. The guiding means can but also by other joining methods, as for example by gluing and / or screws, on the measuring tube be attached. Advantageously, it is possible thereby different Materials for to use the measuring device.

Prefers the measuring tube has an inner flow channel, wherein the Orientation of the flow channel defines the flow direction and the measuring cross section as part of the flow channel in this is aligned perpendicular to the flow direction of the medium. Especially Preferably, the orientation of the measuring cross section is perpendicular to Flow direction selected, because at this orientation the maximum possible induced voltage can be tapped. This goes in particular from the already introduced mathematical, vectorial dependence the induced voltage of the flow rate. Since in general, z. B. due to vibration, interference voltages It is useful when dimensioning that the relevant induced voltage, which represents the flow rate, significantly larger than a possible interference voltage is.

Further Preferably, the measuring tube in the axial direction three geometrically differently formed sections on. The first paragraph is located in the area of the measuring cross-section, the second sections each at the pipe ends and the third sections between the second sections at the pipe ends and the first section in the Area of the measuring cross-section.

The first section in the region of the measuring cross-section is preferably prismatic, in particular with a rectangular cross-sectional area, in the flow channel and / or on the measuring tube outside. The second sections at the tube ends are designed to be constant in relation to their cross-sections in the flow channel and / or on the measuring tube outside. Preferably, in these sections, the flow channel is designed as a hollow cylinder and the measuring tube outside as a cylinder. In the third sections, which lie between the sections at the tube ends and the section in the flow channel, the Querschnittsflä tapers surface of the flow channel to the measuring cross-section. However, the maximum cross-sectional dimension at the measuring tube outside surface remains constant in these third sections. This constancy of the maximum cross-sectional dimension on the measuring tube outer surface is due to the rib reinforcements, which compensate for cross-sectional changes on the measuring tube outside.

Becomes in the area of the measuring cross section both in the flow channel and at the measuring tube outside a rectangular cross-sectional area selected becomes a parallelism the flow channel surfaces and the measuring tube exterior surfaces, thereby ensuring a constant wall thickness between these surfaces is conditional.

Further The flow channel preferably has a smaller diameter in the measuring cross section Cross sectional area as outside of the measuring cross section. Particularly preferably, the area of the measuring cross section about half the cross sectional area of the Flow channel outside of the measuring cross section. By this reduction in cross-sectional area, will the velocity of the medium flowing through the flow channel elevated and thereby a relatively large voltage can be tapped become. The relationship the induced voltage with respect to possible interference voltages is thus relatively high and the flow rate can be determined exactly be, as clearly between induced voltage and interference voltage can be differentiated. By increasing the flow rate, will about that It also reduces the likelihood of getting in the measuring cross-section Form deposits. Furthermore, the flow profile is smoothed and thus the occurrence of any turbulent currents that have an impact could be on the knife, reduced. additionally the necessary inlet section is reduced. This makes it possible for that the measuring device directly behind irregularities in the pipe system, to Example behind a manifold, can be installed.

Further preferably, the guide means parallel to one another and tangentially with respect to an aligned with the longitudinal axis of the measuring tube coaxially reference diameter D ₁ are arranged, wherein for the reference diameter D _1: 0 <D ₁ <D ₀ with D ₀ as the greatest cross-sectional outside dimension of the measuring tube. Particularly preferably, the guide means are designed as guide rails. The magnetic field generating device is arranged between these guide rails to the measuring tube and away from it. By this type of embodiment of the guide means, a particularly simple assembly of the magnetic field generating device is possible. Also, the positioning can be easily accomplished, since the magnetic field generating device with respect to the measuring tube in only one degree of freedom, namely the direction of displacement, is movable. Thereby, the magnetic field generating device is held in five degrees of freedom and simplifies the assembly, since the likelihood that the magnetic field generating device moves from its mounting position, is minimized possible.

Of Furthermore, the guide rails are preferred Grooves for guiding the magnetic field generating device during assembly. These guide grooves are located both on the measuring tube facing as well as the measuring tube opposite side of the guide rails and can individually to different magnetic field generating devices be adjusted. The grooves thus serve for reliable guiding, positioning and holding different variants of magnetic field generating devices.

Further Preferably, four or eight guide rails are integrally formed on the measuring tube.

Become the longitudinal ends side by side arranged guide rails connected with fictitious straights, so limit this line and the guide means in a projection in both the axial and in the radial direction rectangular areas. These surfaces in turn, borders a prismatic body, in particular a cuboid. This body serves to accommodate the magnetic field generating device.

Of Further preferred are the guide means as at least two trough-shaped housing parts educated. Two housing parts each are opposite each other arranged on the measuring tube and serve to accommodate the components of Magnetic field generating device. In these housing parts is in each case an upper part and a lower part of a magnetic field generating device can be inserted. This type of training of the guiding means, ensures a exact guidance and positioning the components of the magnetic field generating device. Due to the exact positioning, an exact alignment of the Magnetic field generating device with respect to the measuring tube guaranteed. Further, by the guide the trough-shaped trained guide means a simple installation of the magnetic field generating device possible.

Furthermore, the guide means preferably have at their longitudinal ends first positioning elements which are in particular designed as positioning pins and serve for the positioning and / or attachment of the measuring tube to a circuit board and / or a circuit board segment. Further preferably, the measuring tube and / or the guide means integrally formed thereon have second positioning elements which are aligned orthogonally with respect to the first positioning elements tet and also preferably designed as a positioning pin. By means of these first and second positioning elements, it is easily possible to attach and position the measuring tube to surrounding devices. For this purpose, the positioning pins are in corresponding recesses, z. B. in a board to be connected, plugged. By such a plug-in system, these compounds, depending on the selected dimensions of the positioning pins and the corresponding recesses, be made detachable. Because the second positioning elements are aligned orthogonally with respect to the first positioning elements, it is possible to connect components which lie laterally of the measuring tube. The first and second positioning elements thus enable simple positioning and fixing of the measuring tube with respect to surrounding components.

Prefers the measuring tube further includes longitudinal and / or transverse ribs increase strength. Through these ribs is achieved that for manufacturing of the measuring tube a relatively lower Material required is and the measuring tube nevertheless has a high strength and / or stability. Accordingly, a measuring tube with reinforcing ribs has a smaller one Weight as a measuring tube with equal strength but with huge wall thickness on. Further, especially when the measuring tube is in a casting process is manufactured, material accumulations and resulting casting defects, such as a dip of the material at these points, avoided. The ribs are preferred also arranged in the second and / or in the third section of the measuring tube.

Further Preferably, the measuring tube has an electrically insulating material, in particular an injection-molded plastic, a glass and / or a ceramic on. Since the magnetic field is the medium through the measuring tube wall must pass through, the measuring tube must not be ferromagnetic, because such a measuring tube would deflect the magnetic field.

by virtue of the complex geometry of the measuring tube, it makes sense to use a plastic material to use. Complicated geometries can be relatively easily injection molded getting produced. Preference is here for the measuring tube, a polymeric Material such as PEEK (PEEK = polyetheretherketone) used. PEEK is a high temperature resistant thermoplastic material which reduces its melting temperature at about 335 ° Celsius Has. Instead of using PEEK, other ketones can be used as well for example PEK, PEEEK, PEEKEK or PEKK. Such Polyether ketone materials are resistant to almost all organic and inorganic Materials resistant. Furthermore, these materials are also advantageous because they are up to a temperature of about 280 ° Celsius resistant to Hydrolysis are. However, such materials are typical against UV radiation and corrosive Materials or in oxidizing conditions unstable, causing such polyether ketones are protected by a dedicated housing have to. In summary, therefore, PEEK can be compared to others Plastics a very good chemical and thermal resistance having. This is an employment of one equipped with such a material Measuring tube even with aggressive flow media with a high Temperature possible. Further preferred is PEEK due to its high strength and Stiffness preferably used.

Further preferred materials for manufacturing the measuring tube are PPS (= Polypheylene sulfide) and IXEF (= polyarylamide). Both materials have a high resistance to chemicals, temperature resistance and strength on.

Of Further preferably, the ends of the measuring tube are designed as a nozzle and / or rejuvenate in the axial direction to the pipe ends. This is one a simple connection of the measuring tube to surrounding components, in particular pipe sections in front of and behind the measuring tube, possible. rejuvenated the measuring tube at the pipe ends, so the connection as a Pressed composite can be realized with surrounding pipe sections. Alternatively you can through the use of flanges at the pipe ends, adhesive, bolt and / or screw connection for the connection will be used.

Further The measuring tube ends preferably have third positioning elements Position the measuring tube on the surrounding pipe sections. By this positioning the assembly is simplified and a possible one Twisting and / or an offset of the measuring tube with respect to the surrounding Avoiding pipe sections. These third positioning elements can thereby In particular, be designed as a positioning, the corresponding in Wells of the surrounding pipe sections are plugged.

Furthermore preferred, has the measuring tube on its outer surface in the region of the measuring cross-section at least one flat recess transverse to the longitudinal axis of the measuring tube, on which at least the core of the magnetic field generating device can be applied. Through this recess, the wall thickness becomes local reduced and the for the magnetic field reduces necessary energy. The magnetic field generating device can therefore be made extremely compact, since no large wrapped Cores are necessary.

advantageously, the measuring cross section in the region of the recess is additionally rectangular executed. A parallelism at least one of the measuring cross-section walls to the planar recess requires a constant wall thickness. attenuation effects the magnetic field, due to different wall thicknesses in the Measuring cross section, are thus avoided.

Furthermore The recess preferably has an additional characteristic Fixation of the magnetic field generating device in longitudinal and / or Transverse direction of the measuring tube. By such a form, will the exact positioning of the cores of the magnetic field generating device in terms of ensured the measuring cross section. Though is already through the guide Accurate positioning achieved by an additional positioning expression close the measuring cross section, the accuracy of the positioning of the Magnetic field generating device, however, be further increased.

advantageously, the two measuring electrodes on the measuring tube are opposite each other and perpendicular to the flow direction and the magnetic field in the first Section are arranged. Due to the already introduced law concerning the Relation of magnetic field and electrode alignment can by this arrangement the greatest possible tension be tapped.

Further Preferably, the measuring electrodes are designed as metal pins. Prefers the measuring electrodes at least partially have a circular cross-section on. If measuring electrodes are used with such a base, so can used as electrode starting materials inexpensive wires and / or rods become. Assign the measuring electrodes to the outside of the measuring tube Thread on, so the measuring electrode very simple, z. B. over a Threaded connection, to be contacted. A solder joint of the measuring electrodes with a wire is thus bypassed and excessive heating and / or a possible damage of the measuring tube does not occur. Also, such a screw connection easily solvable. This is especially for Maintenance work advantageous.

Further Preferably, the measuring electrodes protrude in the region of the measuring cross section in the flow channel. Are the measuring electrodes with the medium in Contact, the voltage is tapped galvanically and a Cleaning of the measuring electrodes takes place through the medium.

Of Further preferably, the measuring electrodes are flow channel side galvanically isolated from the medium. This will prevent that the measuring electrodes are attacked and / or corroded by the medium and furthermore the medium becomes dirty.

Further Preferably, the measuring electrodes are designed in two parts in the longitudinal direction. By this bipartite makes it possible for the a part of the measuring electrode, a first material and for the second measuring electrode part to use a second material, the material flow channel side a good contact with the medium and the outside Measuring electrode part another property, such. B. a good one solderability, having. Indicates the outer measuring electrode part good solderability on, so can a contacting of the measuring electrodes at a low Temperature development can be achieved and the measuring tube is not overheated and possibly damaged.

Further Preferably, the first measuring electrode part is fixed to the measuring tube wall connected and has a bore, wherein the bore is made such that the second measuring electrode part can be pressed into this bore is. In this way, lets the measuring electrode perform in two parts and yet between the first and second measuring electrode part very simply a good electrical Establish contact. To while the pressing of the second measuring electrode part a detachment of the first measuring electrode part of the measuring tube wall to avoid points this further preferably in the region of the measuring tube wall circumferentially additional Fuse characteristics, such as knurling, on.

Further Preferably, the first measuring electrode part is fixed to the measuring tube wall connected and has a thread, wherein the second measuring electrode part is screwed to this thread. The thread on the first measuring electrode part Can be either as an external thread on the outside diameter or be realized in the form of a threaded hole. Furthermore Preferably, the first measuring electrode part circumferentially has an anti-rotation characteristic, such as for example, knurling on so that the first measuring electrode part when tightening the second measuring electrode part does not detach from the measuring tube wall. Of further preferred is on the flow channel remote side the measuring tube wall around the first measuring electrode part a circumferential Well provided, in which an O-ring is arranged. This O-ring is dimensioned such that between this and the measuring tube wall and / or the first measuring electrode part, a radial forming sealing area. For this purpose, the O-ring has a larger outer diameter on as the circumferential diameter of the circumferential recess and has Further, a cord diameter that is greater than the distance from the first measuring electrode part to the peripheral diameter of the recess.

Of Further preferably, the measuring device has a storage device on, in the Meßrohrkenndaten, in particular with regard to the expression and the dimensions the measuring cross-section and / or the guide means are deposited. Furthermore, can Information regarding the measuring electrodes, z. B. their materials and / or their characteristics, be stored. This data can, for. From a display device, are displayed. The specific data of the respective measuring tube stand thus, for example for Maintenance work, available. About that It is also possible that a standardized evaluation electronics, with a variety of different Measuring devices is used, the stored data reads out and derive evaluation parameters from this.

Further Preferably, the measuring tube has at least one temperature sensor. The signals of this temperature sensor can also evaluated and displayed. This is a simple control the temperature of the measuring tube possible and if a limit temperature exceeded will, from which damage the measuring device can occur Is it possible, immediately activities to take. Particularly preferred is the measuring electrode itself as a temperature sensor accomplished or from a temperature sensor contacted because metal measuring electrodes have a high thermal conductivity and thus the temperature very accurately, with only a small delay can be determined.

Of Further preferred is a device for changing the dimensions and / or the expression provided the measuring cross section. By such a device it is advantageously possible to react to different flow rates. This is how it is added high flow rates the area of the measuring cross section increased which does not cause too high pressures and / or flow rates occur in the measuring tube. If the flow rate of the medium decreases, this is how the area becomes reduces the measuring cross-section, thereby ensuring that the entire Measuring cross section is traversed by the medium.

Further Preferably, the flow channel has a coating, in particular to increase Abrasion strengthening and / or chemical resistance on. Also can Coatings to increase the shape and vacuum stability be used. By such a coating is a high Life of the measuring tube ensured.

The Magnetic field generating device preferably has a respective E-shaped upper and lower part, wherein the respectively wound core of the upper and Lower part to the measuring cross section is radially aligned and the Pole shoes of the shell with respect to the Bottoms and the pole shoes of the lower part with respect to the upper part, both sides of the measuring tube slightly spaced apart. By this type of arrangement of the shell and the lower part, becomes a guide reaches the field lines of the magnetic field. A small air gap between the pole shoes and the upper part or the lower part, reduces the lead the field lines imperceptible. Due to the guidance is using a magnetic field a low magnetic field strength necessary and the upper and the lower part of the magnetic field generating device can be made relatively compact. An additional Element to make the contact between upper and lower part, is not necessary.

Further Preferably, the magnetic field generating means has an upper and a lower, radially oriented to the measuring tube prismatic core on. The upper and lower core is formed by a particular spangenförmig electrically conductive connecting means fixed to the measuring tube. By this connection means is on both sides of the measuring tube, an electrical contact between the upper and lower core made. The already executed advantageous leadership of Field lines of the magnetic field, is on both sides of the measuring tube through ensures the connection means. The connecting means may preferably be designed as a clasp. By this kind of execution the magnetic field generating device, are the upper and lower core Extremely easy and inexpensive to manufacture components.

Additionally preferred becomes a populated measuring device proposed, which is a measuring tube, measuring electrodes, a magnetic field generating device and further comprises an evaluation. The evaluation electronics is arranged on the measuring tube and connected to the measuring electrode and the Magnetic field generating device electrically connected.

These Evaluation electronics preferably has a single board segment which is positioned on positioning elements on the measuring tube and is attached. Such a board segment is often to used various electronic components and their connections to connect with each other so that they are mounted together in a housing of an electronic device can be. By these electronic components can electrical and electronic functions required for operation of the flowmeter are required, executed become. Such functions relate to the measurement and evaluation of Measurement results and possibly derived controls.

Also preferably, the transmitter has at least a first and a second rigid circuit board segment, wherein the circuit board segments are interconnected via flexible conductor film sections both mechanically and electronically. The evaluation electronics are furthermore positioned and fastened to positioning elements on the measuring tube such that the evaluation electronics at least partially surround the measuring tube in the radial direction. Particularly preferably, the transmitter has three rigid circuit board segments. Due to this design of the board of the transmitter, electronic components can be arranged on a plurality of rigid circuit board segments, and yet the overall structure remains compact, since the transmitter is foldable on the flexible conductor film sections. This foldability is used to arrange the evaluation electronics on the measuring tube in such a way that it at least partially surrounds the measuring tube in the radial direction. As a result, the assembled measuring device can be made very compact.

alternative the transmitter may preferably have a one-piece board, the board is groove-shaped Recesses, around which the board at least partially is foldable. The board is also on such positioning elements the measuring tube positionable and attachable, that this the measuring tube at least partially encloses in the radial direction. Also through this type of execution a very compact overall structure can be achieved.

Further Preferably, the evaluation completely on a flexible Conductor film applied. Also in this form, the transmitter the measuring tube to be arranged at least partially surrounding this. A compact design of the structure is thus also possible.

Of Further preferably, a magnetic inductive flowmeter is provided, which is a measuring device according to the invention, a housing shell and above also has a threaded connector cover. Preferably, the housing jacket a circular one Floor space on and is made of a metal, especially a stainless steel. About that In addition, a display device is preferred within the housing shell arranged, which indicates at least the flow rate of the medium.

advantageously, has the threaded connector cover fastening means, with which this type with the measuring device and the housing shell connected is that the longitudinal axis of the Threaded socket cover with the longitudinal axis of the Measuring tube coincides.

Further Preferably proposed is a method for producing a Measuring device for or in a flowmeter. First is provided an injection mold, the cavity as a negative is formed to a measuring tube, wherein shrinkage dimensions in their Manufacturing are considered. Subsequently The measuring electrodes are inserted into the injection mold. To the closing the injection mold is the extruder screw with the injection channel connected and the plastic melt into the cavity of the injection mold injected. While of the filling process the measuring electrodes are surrounded by the melt.

Of Further preferred is then the plastic melt hardened, this being in a temperature chamber, at a low temperature can happen. Once the complete measuring tube has hardened, it will it demolds and possible Anstoß and the like removed. Subsequently, further value creation steps, such as As the installation of such a measuring tube in a flow meter, done.

The Invention will be described below with reference to exemplary embodiments with reference explained in more detail on the accompanying figures of the drawing. This shows:

1a . 1b the measuring device according to the invention in a side view and in a sectional view;

2a - 2c that of the measuring device according to the invention according to a preferred embodiment in different views;

3a . 3b the measuring device according to the invention with a magnetic field generating device according to a first preferred embodiment in the disassembled and mounted state;

4a - 4c the measuring device according to the invention with a magnetic field generating device according to a second preferred embodiment in disassembled and assembled state;

4d - 4f an upper / lower part of a magnetic field generating device in a front view according to preferred embodiments;

5A . 5B a measuring electrode according to two preferred embodiments;

6A . 6B the measuring device according to the invention and a circuit carrier in disassembled and assembled state;

7A - 7D a populated measuring device and two covers in disassembled and assembled state in different views;

8A - 8C a flowmeter with the measuring device according to the invention according to a first and a second preferred embodiment;

9 a flowchart in which the main process steps and material flows are shown.

In In the figures of the drawings, the same reference numerals designate the same or functionally identical elements and components, unless otherwise stated is specified.

The measuring device according to the invention is in 1a in a side view and in 1b shown in a sectional view. Basic component of the measuring device 1 is the measuring tube 2 with a measuring cross section 5 in which the measuring tube 2 has a defined measuring cross-sectional area. In the area of the measuring cross section 5 are measuring electrodes 3 arranged. Formed on the measuring tube outside surface are also guiding means 4 for holding and positioning a magnetic field generating device, wherein the guide means integral with the measuring tube 2 are executed. In the measuring device according to the invention 1 , the magnetic field generating device is such between the guide means 4 positionable, that the magnetic field perpendicular to the flow direction of the medium through the measuring tube 2 is produced. The measuring electrodes are again perpendicular to both the direction of flow and the magnetic field that can be generated 3 arranged, via which a signal voltage can be tapped, which is dependent on the flow rate and the magnetic field strength. Due to the guidance means 4 the magnetic field generating device can neither longitudinal nor transverse with respect to the measuring tube 2 to be moved. As a result, an exact positioning of the magnetic field generating device, both with respect to the measuring electrodes 3 as well as the measuring cross-section 5 guaranteed.

The measuring device according to the invention is according to in a preferred embodiment is in 2a in a side view, in 2 B in a sectional view and in 2c shown in an isometric view. The measuring device 1 has a measuring tube 2 as well as measuring electrodes 3 on. In the longitudinal direction, the measuring tube 2 a measuring channel 6 with a measuring cross section 5 on, with the measuring cross section 5 is aligned perpendicular to the flow direction of the medium. In addition, the cross section of the measuring channel is reduced 6 from the measuring tube ends 11 in the direction of the measuring cross section 5 , As a result of this reduction in the cross-sectional area, an acceleration of the medium becomes the measuring cross-section 5 reached and a higher signal voltage can be tapped. In order to be able to pick up the greatest possible signal voltage, the measuring electrodes are 3 arranged opposite each other and perpendicular to the flow direction of the medium. Furthermore, the measuring electrodes 3 in the measuring channel 6 in contact with the flowing medium. To make a transition of the charge carriers from the measuring electrodes 3 on the medium or from the medium to the measuring electrodes 3 to avoid are the measuring electrodes 3 galvanically from the measuring channel 6 separated by flowing medium. The measuring electrodes 3 penetrating the measuring tube wall and are electrically contacted on the outside of the measuring tube in order to tap the signal flow dependent on the flow rate. An electrical contact is z. B. by soldering with a wire possible. Alternatively, the measuring electrode 3 at least partially have a thread and the electrical contact via a screw. Furthermore, the measuring tube 2 formed on its outside guide means 4 on. In the illustrated preferred embodiment, these are designed as guide rails. These guide rails are arranged parallel to each other and tangent to the measuring tube 2 formed. By this type of arrangement of the guide means 4 is a magnetic field generating device perpendicular to the measuring tube 2 movable. To guide this movement of the magnetic field generating device, the guide means 4 inner longitudinal grooves 7a and / or outer longitudinal grooves 7b on. Depending on the design of the magnetic field generating device, a guide is provided by the inner longitudinal grooves 7a and / or the outer longitudinal grooves 7b taken over, wherein the magnetic field generating device in its end position in close proximity to the measuring cross section 5 located. It is obvious that the management means 4 not necessarily have to be designed as guide rails. The guiding means 4 may also be formed wall-shaped, wherein the guide rails shown quasi the cornerstone of the wall-shaped guide means 4 would form. By wall-shaped guide means 4 A container is formed, with an opening on the side facing away from the measuring tube, through which a magnetic field generating device can be inserted.

The guiding means 4 also have first positioning elements 8th on. This first positioning elements 8th are executed in the illustrated preferred embodiment as a positioning and at the longitudinal ends of the guide means 4 arranged. Through the positioning pins 8th is a positioning of the measuring device 1 with respect to surrounding components, such. As a circuit substrate and / or a housing possible. Depending on the design of the positioning pins and the respective bore around the surrounding component into which they are introduced (not shown), either a positioning (clearance fit) and / or a fixation (press fit) with respect to the surrounding components can take place. The same applies for the second positioning elements 9 , In the illustrated preferred embodiment, these are also designed as positioning pins, which are arranged on the guide means such that these second positioning elements perpendicular to the first positioning elements 8th are aligned. A positioning and / or a fixation with respect to surrounding components is through these second positioning pins 9 also possible.

Furthermore, the measuring tube 2 between the management tools 4 a flat recess 12 on. This recess 12 is in the range of the measuring cross section 5 arranged. If the magnetic field generating device has a planar core, then it lies on the planar recess 12 at. To achieve additional positioning security, has the recess 12 an expression 14 for positioning the magnetic field generating device. This expression is in addition to the management tools 4 achieved an exact positioning of the core of the magnetic field generating device. A displacement of the magnetic field generating device in the axial and / or transverse direction with respect to the measuring tube 2 will be prevented. The expression 14 for fixing the magnetic field generating device can be adapted to the core of the magnetic field generating means increased and / or deepened.

In addition, the measuring tube points 2 in the illustrated preferred embodiment in the axial direction extending ribs 10 , to increase the strength of the measuring tube 2 on. However, it is obvious that these ribs 10 not necessarily as longitudinal ribs but also as circumferential ribs or as a combination form of longitudinal ribs and circumferential ribs may be formed.

Furthermore, the pipe ends 11 designed such that at these surrounding components, such. B. more pipe elements can be attached. In the illustrated preferred embodiment, the meter tube ends 11 shaped like a stump. Through this nozzle form, a simple connection to other pipe elements both before and after the measuring device is possible. It can be seen that the measuring tube ends 11 do not need to be formed nozzle-shaped, but also other types of connections, such. B. flange, screw or the like, are possible. In addition, at the Messrohrenden third positioning 13 arranged, with which a positioning with respect to surrounding pipe elements is possible. In the illustrated embodiment, these positioning elements 13 designed as a positioning pin, other forms are also possible.

In addition, the measuring device 1 a hole in which a temperature sensor 15 is appropriate. With the temperature sensor 15 is beyond the detection of the flow rate, a detection of the temperature of the measuring device 1 possible.

alternative This can also be a temperature insensitive sensor, such as a PTC sensor, used in the manufacture of the measuring tube directly from the plastic from which the measuring tube consists, overmoulded becomes.

The 3a and 3b show a measuring device with a magnetic field generating device according to a first preferred embodiment. 3a shows the embodiment in a side view in disassembled state, 3b the same measuring device with magnetic field generating device in the assembled state in an isometric view. At the measuring tube 2 are molded guide means 4 arranged, which are formed wall-shaped. Together, the wall-shaped guide means 4 on two sides of the measuring tube 2 a container, with an opening on the side facing away from the measuring tube. The magnetic field generating device consists of an upper part 17a a lower part 17b as well as a clasp 17c , In the illustrated preferred embodiment, both top are 17a as well as lower part 17b formed prismatic with a rectangular base. The coil windings are arranged around the lateral surface of the prisms. The top 17a and the lower part 17b is in each case in that of the guidance means 4 formed upper and lower containers so inserted, that the base of the upper part 17a and the lower part 17b in the direction of the measuring tube 2 is aligned. The wall-shaped guide means 4 are so pronounced that this exact guidance and positioning of the upper part 17a and bottoms 17b guarantee. The guiding means 4 such on the measuring tube 2 formed that the magnetic field generated by the magnetic field generating device both perpendicular to the measuring electrodes 3 as well as perpendicular to the flow direction of the medium. To a movement of the shell 17a and the lower part 17b radially with respect to the measuring tube 2 to restrict is also a clasp 17c provided with a final fixation of the upper part 17a and bottoms 17b he follows. This clasp 17c has recesses 17d for the measuring electrodes 3 on. Is the clasp 17c made of a ferromagnetic material, a guide of the field lines of the magnetic field generated by the magnetic field generating means takes place on both sides of the measuring tube. By this Feldli nienführung, despite a low magnetic field strength, a sufficiently high signal voltage can be tapped. The magnetic field generating device can therefore be realized extremely compact. It is obvious that the clip does not necessarily have to be designed as one element, but that also z. Two on both sides of the measuring tube 2 arranged clasps fulfill the same function. Furthermore, the upper part must 17a and the lower part 17b not be designed as a prism with a rectangular base. A round design of the base or a polygonal design is also possible.

The 4a . 4b and 4c also show a measuring device with a magnetic field generating device according to a second preferred embodiment. 4a shows a side view of the embodiment in a disassembled state and the 4b and 4c the measuring device and the magnetic field generating device in a mounted state in a side view and in an isometric view. The measuring device 1 has the same features as the preferred embodiment, which in the 2a - 2c is shown and has already been discussed. At the measuring tube 2 are guiding means 4 molded, which are pronounced as guide rails. The four guide rails 4 are parallel to each other and arranged tangentially on the measuring tube. The magnetic field generating device consists of an upper part 18a as well as a lower part 18b , As in 4d Shown in a front view, the top part knows 18a and the lower part 18b two pole shoes 18c and a wrapped core 18d on. Like from the 4a - 4c can be seen, are the pole pieces 18c pin-shaped pronounced. Both the top 18a as well as the lower part 18b is in the direction of the measuring tube 2 in the guide rails 4 insertable. The leadership of the shell 18a and the lower part 18b takes place in each case by the at the guide means 4 attached outer longitudinal grooves 7b , As in the 4b and 4c shown, touches the pole piece 18c of the top 18a the lower part 18b and the pole piece 18c of the lower part 18b the top 18a at the side of the measuring tube 2 , By this touch of the upper part 18a and the lower part 18b , a lateral, electrically conductive contact and a good field line of the magnetic field is achieved. Accordingly, in this embodiment, a small magnetic field strength and thus only a compact magnetic field generating device is necessary. To a movement of the shell 18a or of the lower part 18b to avoid against the insertion direction, a clasp can also be used. However, it is also possible that a fixing takes place by surrounding components mounted in a further value-adding step. This is possible because of the already existing contacting of the pole shoes 18c a contact must not be made by an additional electrically conduct the element. It can be seen that the design of the upper part chosen here 18a and the lower part 18b is merely exemplary and other forms are possible. A guide of an upper part or a lower part could in another embodiment also on the inner longitudinal grooves 7a respectively.

The 4e and 4f show the formation of the upper part or lower part of the magnetic field generating device, according to two further preferred embodiments. In 4e is the wrapped core 18d not prismatic but T-shaped. This will cause the coil windings 18e between the base 18f the upper part or lower part and the T-shaped core 18d trapped. Slipping of the coil winding 18e is thus excluded. According to another, in 4f illustrated preferred embodiment, is the core 18d the upper part or lower part pyramid-shaped. Slipping of the coil winding 18e can also be advantageously avoided, since the coil windings 18e between the base 18f and the pyramidal core 18d are trapped.

The 5a shows a two-part measuring electrode according to a first preferred embodiment. This measuring electrode consists of a first measuring electrode part 26 and a second measuring electrode part 27 , The first measuring electrode part 26 is arranged on the flow channel side and is in contact with the medium flowing therein. To accomplish this, the first measuring electrode part 26 directly into the wall of the measuring tube 2 be embedded. This first measuring electrode part 26 consists of a precious metal, which is not attacked by the medium. Furthermore, the first measuring electrode part has 26 on the flow channel side facing away from a bore. In this hole, a second measuring electrode part 27 be pressed. For this purpose, this bore has a slightly smaller diameter than the outer diameter of the second measuring electrode part 27 on. To move the first measuring electrode part 26 during the pressing of the second measuring electrode part 27 to avoid has the second measuring electrode part 26 circumference an expression that is formed, for example, knurled and positively connected to the measuring tube wall. On the second measuring electrode part 27 becomes an evaluation electronics 19 which a receiving bore 32 for the second measuring electrode part 27 has, plugged. An electrical contact of the second measuring electrode part 27 with the transmitter 19 via a solder joint 31 , To a good solderability of the second measuring electrode part 27 To ensure this is made of a good solderable material, such as brass.

The 5b shows a measuring electrode, which consists of a first measuring electrode part 26 and a second measuring electrode part 27 consists, according to a second preferred embodiment. The first measuring electrode part 26 is also in the flow channel in contact with the medium and is to inside the wall of the measuring tube 2 embedded. The measuring tube wall has a recess on its side facing away from the flow channel 33 , In this depression 33 , is an O-ring 29 inserted in such a way that between the peripheral wall of the recess 33 and the circumference of the first measuring electrode part 26 Training seals. The O-ring 29 has a larger outer diameter than the circumferential diameter of the recess 33 , Furthermore, the O-ring has 29 a larger cord diameter than the distance from the second measuring electrode portion 27 to the peripheral wall of the recess 33 is. As a result, a radial seal is possible. The O-ring 29 Therefore, it does not have to be compressed in the axial direction in the mounted state in order to form the sealing points, but it already deforms during assembly. The second measuring electrode part 27 is on the external thread 30 of the first measuring electrode part 26 screwed. In this case, the second measuring electrode part 27 designed such that this at least partially into the recess 33 protrudes into it. Slipping of the O-ring 29 is thereby prevented. A contacting also takes place in that an evaluation 19 which a receiving bore 32 has, with this on the second measuring electrode part 27 attached and then via a solder joint 31 will be contacted.

The 6A and 68 show one 1 with a magnetic field generating device 17 equipped measuring device and a circuit carrier 19 , 6A shows this in a plan view in a disassembled state 1 . 6B shows the measuring device with a mounted circuit carrier in an isometric view. The measuring device 1 has the already explained positioning pins 8th on. These positioning pins 8th correspond to those in the circuit carrier 19 introduced holes 19c , circuit support 19 has rigid conductor segments 19a as well as flexible conductor segments 19b on. Between two rigid conductor segments 19a is a flexible conductor segment 19b arranged. This allows a bending of the circuit carrier 19 on the flexible conductor segments 19b without damaging the electronics. After inserting the positioning elements 8th in the corresponding holes 19c of the circuit board 19 can the circuit carrier 19 around the measuring device 1 on the flexible conductor segments 19b be folded. This makes a very compact design of the overall structure possible.

The 7A - 7D show a populated measuring device 20 as well as two lids 21 , The 7A shows the equipped measuring device 20 as well as the lids 21 in disassembled condition. The 7B shows the assembled measuring device and the lid in the assembled state in a side view, the 7C the assembled assembly in a sectional view and the 7D this in an isometric view. The equipped measuring device 20 consists of a measuring tube 2 with measuring electrodes 3 , a magnetic field generating device 17 as well as a circuit carrier 19 , The lids 21 are each at a measuring tube ends 11 of the measuring tube 2 assembled. To between the covers 21 and the measuring tube 2 To ensure a good connection, the measuring tube end points 11 a thread which leads to a corresponding thread on the inner surface 21a of the lid 21 fits. Other connection types, such. B. a conical connection between the lid 21 and measuring tube 2 , are also possible.

The 8A - 8C show a flow meter 16 , which the measuring device according to the invention 1 having. The flowmeter 16 has two lids 21 and a housing shell 22 on, this being the measuring device 1 , the magnetic field generating device 17 and enclose the circuit carrier. Furthermore, the flowmeter has 16 a socket 23 on. 8A shows the flowmeter according to the invention, wherein the display and Bedienpaneel 24 in the housing shell 22 in the direction of the longitudinal axis of the flowmeter 16 is indented. 8B shows the flowmeter according to the invention 16 according to a second preferred embodiment, wherein the display and Bedienpaneel 24 from the housing shell 22 is arranged to the outside raised. Both flowmeters 16 have a connection 23 on, with what data of the flowmeter 16 are readable. This can z. B. data relating to the operating parameters of the flowmeter and / or the flow rate and / or the temperature of the medium.

9 shows the inventive method for producing the measuring device according to the invention. In the first method step S1, the measuring electrodes 3 inserted in an injection mold. Subsequently, the injection mold is closed, an extruder connected to the gate and in step S2, the plastic melt 25 injected into the injection mold until the cavity is completely filled. A burr-free of the inner channel can be achieved by the use of a cross-lockable slide. In step S3, the plastic melt is cured. Subsequently, in step S4, the cured measuring tube is removed from the mold and in step S5, anvils, risers and auxiliary structures are removed. In further value creation steps, the measuring device thus produced 1 be installed in a flow meter.

Although the present invention has been described above with reference to preferred embodiments, it is not limited thereto, but modifiable in a variety of ways. So it is possible, for example, that a contacting of the measuring electrodes directly with the circuit carrier at whose assembly is made. This is possible, for example, via appropriately designed holes in the circuit carrier, which have an electrically conductive material and are connected directly to the electronics of the circuit carrier. If the measuring electrodes are inserted in these holes during assembly, the contacting takes place. Also, the measuring electrodes do not necessarily have a round cross-section. Rectangular or polygonal cross sections of the measuring electrodes are also possible.

1

measuring device

2

measuring tube

3

measuring electrode

4

guide means

5

Measuring section

6

Flow channel

7

groove

7a

inner grooves

7b

outer longitudinal grooves

8th

first Locators

9

second Locators

10

ribs

11

Measuring tube end

12

recess

13

third Locators

14

Characteristic of Fixation of the magnetic field generating device

15

temperature sensor

16

Flowmeter

17

Magnetic field generating means

17a

Magnetic field generating device - upper prismatic core

17b

Magnetic field generating device - lower prismatic core

17c

Magnetic field generation means lanyard-shaped clasp

17d

Magnetic field generating means recess

18a

Magnetic field generation means-E-form shell

18b

Magnetic field generation means-E-form base

18c

Magnetic field generation means-E-form pole pieces

18d

Magnetic field generation means-E-form core

18e

Magnetic field generator coil windings

18f

Magnetic field generating device base

19

evaluation

19a

rigid conductor segment

19b

flexible conductor segment

19c

drilling

20

Fitted measuring device: Measuring tube with measuring electrodes + magnetic field generating device + circuit support

21

Threaded connector-cover

21a

Lid inner surface

22

housing jacket

23

socket

24

Display- and control panel

25

Plastic melt

26

first Measuring electrode member

27

second Measuring electrode member

28

knurled

29

seal

30

thread

31

soldered point

32

location hole

33

deepening

S0

Provide an injection mold

S1

insert the measuring electrode

S2

inject the plastic melt

S3

Harden

S4

unmolding

Claims (60)

Measuring device ( 1 ) for or in a magnetic inductive flowmeter ( 16 ), with a measuring tube ( 2 ), which has a measuring cross-section ( 5 ) for flow measurement of the measuring cross section ( 5 ) flowing through medium and which also guide means ( 4 ) for holding and positioning a magnetic field generating device in the region of the measuring cross section ( 5 ) having; with at least two measuring electrodes ( 3 ), which in the region of the measuring cross-section ( 5 ) is arranged such that a dependent of the flow rate electrical signal can be tapped when a magnetic field is the measuring cross section ( 5 ) penetrates. Measuring device ( 1 ) according to claim 1, characterized in that the guide means ( 4 ) subsequently to the measuring tube ( 2 ) are molded and / or molded. Measuring device ( 1 ) according to claim 1, characterized in that the guide means ( 4 ) in one operation in one piece with the measuring tube ( 2 ) are made. Measuring device ( 1 ) according to at least one of the preceding claims, characterized in that the measuring tube ( 2 ) an inner flow channel ( 6 ), wherein the orientation of the flow channel ( 6 ) defines the flow direction of the medium and the measuring cross section ( 5 ) as part of the flow channel ( 6 ) in this flow channel ( 6 ) is aligned perpendicular to the flow direction. Measuring device ( 1 ) according to at least one of the preceding claims, characterized in that the measuring tube ( 2 ) in the axial direction having geometrically differently shaped sections, which have mutually different cross-sectional areas. Measuring device ( 1 ) according to claim 5, characterized in that a first section in the region of the measuring cross-section ( 5 ) is arranged and that second portions are arranged at the tube ends and third portions between the first and second portions. Measuring device ( 1 ) according to claim 6, characterized in that, the first section in the flow channel ( 6 ) and / or on the measuring tube outside prismatic, in particular with a rectangular cross-sectional area is executed. Measuring device ( 1 ) according to claim 6 and 7, characterized in that in the first and / or second sections, the cross-sectional area in the flow channel ( 6 ) and / or on the measuring tube outside is constant. Measuring device ( 1 ) according to at least one of claims 6 to 8, characterized in that the second sections in the flow channel ( 6 ) is designed as a hollow cylinder and / or on the measuring tube outside as a cylinder. Measuring device ( 1 ) according to at least one of claims 6 to 9, characterized in that in the third sections, the cross-sectional area of the flow channel ( 6 ) tapers to the first portion before the second portions. Measuring device ( 1 ) according to at least one of claims 6 to 10, characterized in that in the third sections the maximum cross-sectional dimension on the measuring tube outside is constant towards the first section. Measuring device ( 1 ) according to at least one of claims 6 to 11, characterized in that the cross-sectional area in the first section corresponds approximately to half the cross-sectional area in the second section. Measuring device ( 1 ) according to at least one of the preceding claims, characterized in that the guide means ( 4 ) parallel to each other and tangentially with respect to the longitudinal axis of the measuring tube ( 2 ) are arranged for the reference diameter d1 0 <d1 <d0 with d0 as the largest cross-sectional outer dimension of the measuring tube ( 2 ). Measuring device ( 1 ) according to at least one of the preceding claims, characterized in that the guide means ( 4 ) are formed as guide rails, in which the magnetic field generating device relative to the measuring tube ( 2 ) is slidably arranged back and forth. Measuring device ( 1 ) according to claim 14, characterized in that the guide rails first longitudinal grooves ( 7a ) on the side facing the measuring tube longitudinal axes and / or second longitudinal grooves ( 7b ) on the side facing away from the measuring tube longitudinal axes for guiding the magnetic field generating device. Measuring device ( 1 ) according to claim 14 and 15, characterized in that on the measuring tube ( 2 ) four or eight guide rails are formed. Measuring device ( 1 ) according to at least one of claims 14 to 16, characterized in that the guide rails and the longitudinal ends of two adjacently located guide rails connecting straight lines, each rectangular surfaces and this surface in turn limit a prismatic formed body. Measuring device ( 1 ) according to at least one of claims 1 to 13, characterized in that the guide means ( 4 ) at least two trough-shaped housing parts form on the measuring tube ( 2 ) are arranged opposite one another and serve to receive components of the magnetic field generating device. Measuring device ( 1 ) according to at least one of the preceding claims, characterized in that the guide means ( 4 ) at their longitudinal ends first positioning elements ( 8th ), in particular positioning, have, the positioning and / or attachment of the measuring tube ( 2 ) on a circuit board and / or a circuit board segment of an evaluation ( 19 ) serve. Measuring device ( 1 ) according to claim 19, characterized in that the measuring tube ( 2 ) and / or the guidance means ( 4 ) second positioning elements ( 9 ), in particular positioning pins, which are orthogonal with respect to the first positioning elements ( 8th ) and the positioning and / or attachment of the measuring tube ( 2 ) on a circuit board and / or a circuit board segment of an evaluation ( 19 ) serve. Measuring device ( 1 ) according to at least one of the preceding claims, characterized in that the measuring tube ( 2 ) for increasing the strength and / or stability longitudinal and / or transverse ribs ( 10 ) having. Measuring device ( 1 ) according to claim 21, characterized in that the longitudinal and / or transverse ribs ( 10 ) in the second and / or third Ab section of the measuring tube ( 2 ) are arranged. Measuring device ( 1 ) according to at least one of the preceding claims, characterized in that the measuring tube ( 2 ) comprises an electrically insulating material, in particular an injection-molded plastic, a glass and / or a ceramic. Measuring device ( 1 ) according to at least one of the preceding claims, characterized in that the measuring tube ( 2 ) PEEK and in particular is made entirely of PEEK. Measuring device ( 1 ) according to at least one of the preceding claims, characterized in that the measuring tube ends ( 11 ) are designed as a nozzle and / or in the axial direction of the measuring tube ( 2 ) to the measuring tube ends ( 11 ) taper to the measuring tube ( 2 ) to surrounding components of the flowmeter ( 16 ). Measuring device ( 1 ) according to claim 25, characterized in that at least one measuring tube end ( 11 ) a third positioning element ( 13 ) for positioning the measuring tube ( 2 ) to one at this end of the measuring tube ( 11 ) has coupling component. Measuring device ( 1 ) according to at least one of the preceding claims, characterized in that the measuring tube ( 2 ) on its outer surface in the region of the measuring cross-section ( 5 ) at least one continuous recess ( 12 ) transversely to the longitudinal axis of the measuring tube ( 2 ), on which at least one wrapped portion of a core of the magnetic field generating device can be applied. Measuring device ( 1 ) according to claim 27, characterized in that the recess ( 12 ) has a flat surface. Measuring device ( 1 ) according to claims 27 and 28, characterized in that the recess ( 12 ) an additional expression ( 14 ) for fixing the magnetic field generating device in the longitudinal and / or transverse direction of the measuring tube ( 2 ) having. Measuring device ( 1 ) according to at least one of the preceding claims, characterized in that two measuring electrodes ( 3 ) are provided and these on the measuring tube ( 2 ) are arranged opposite each other and perpendicular to the flow direction and the magnetic field in the first section. Measuring device ( 1 ) according to at least one of the preceding claims, characterized in that the measuring electrodes ( 3 ) is designed as metal pins, in particular with one, the respective pin on the outer surface at least partially surrounding the thread form. Measuring device ( 1 ) according to at least one of the preceding claims, characterized in that the measuring electrodes ( 3 ) at least partially has a circular base. Measuring device ( 1 ) according to at least one of the preceding claims, characterized in that the at least two measuring electrodes ( 3 ) in the region of the measuring cross section ( 5 ) into the flow channel ( 6 protrude). Measuring device ( 1 ) according to at least one of the preceding claims, characterized in that the at least two measuring electrodes ( 3 ) galvanically from the flow channel ( 6 ) are separated. Measuring device ( 1 ) according to at least one of the preceding claims, characterized in that the measuring electrodes ( 3 ) are made in two parts. Measuring device ( 1 ) according to claim 35, characterized in that a first part of the measuring electrode ( 3 ) at the flow channel ( 6 ) and a second part of the measuring electrode ( 3 ) outside the measuring tube ( 2 ) is arranged. Measuring device ( 1 ) according to claims 35 and 36, characterized in that the first part comprises a non-corrosive material and / or the second part comprises a material which is readily solderable. Measuring device ( 1 ) according to one of claims 35 to 37, characterized in that the first part ( 26 ) is fixedly connected to the measuring tube wall and has a bore, wherein the bore is designed such that the second part ( 27 ) can be pressed into this hole. Measuring device ( 1 ) according to one of claims 35 to 37, characterized in that that the first part ( 26 ) is fixedly connected to the measuring tube wall and has a thread, wherein the second part ( 27 ) on this thread ( 30 ) is screwed tight. Measuring device ( 1 ) according to at least one of the preceding claims, characterized in that the measuring tube ( 2 ) has a memory device, in the Meßrohrkenndaten, in particular with regard to the expression and the dimensions of the measuring cross-section ( 5 ) and / or the guiding means ( 4 ) and / or information regarding the Mes electrodes ( 3 ) are deposited. Measuring device ( 1 ) according to claim 40, characterized in that the measuring tube ( 2 ) at least one temperature sensor ( 15 ), for measuring the temperature of the medium. Measuring device ( 1 ) according to at least one of the preceding claims, characterized in that a device for changing the dimensions and / or the shape of the measuring cross-section ( 5 ) is provided. Measuring device ( 1 ) according to at least one of the preceding claims, characterized in that on the inner surface of the flow channel ( 6 ) has a coating, in particular for increasing the abrasion resistance and / or the chemical resistance. Fitted measuring device ( 20 ) with a measuring device ( 1 ) according to one of the preceding claims, comprising a magnetic field generating device which is arranged between the guide means ( 4 ) is arranged to a magnetic field perpendicular to the longitudinal axis of the measuring tube ( 2 ) in the region of the measuring cross section ( 5 ), to create. Fitted measuring device ( 20 ) according to claim 44, characterized in that the magnetic field generating device has a respective E-shaped upper and lower part, wherein the respectively wound core ( 18d ) of the upper and lower part ( 18a . 18b ) to the measuring cross section ( 5 ) is oriented radially and the pole pieces of the upper part ( 18a ) with respect to the lower part ( 18b ) and the pole shoes of the lower part with respect to the upper part, on both sides of the measuring tube ( 2 ) are arranged slightly spaced. Fitted measuring device ( 20 ) according to claim 44 and 45, characterized in that the magnetic field generating means an upper and a lower radial to the measuring tube ( 2 ) oriented prismatic core ( 17a . 17b ) having. Fitted measuring device ( 20 ) according to claim 46, characterized in that the upper and the lower core of a particular spangenförmig formed, electrically conductive connecting means ( 17c ) on the measuring tube ( 2 ) and the connecting means ( 17c ) on both sides of the measuring tube ( 2 ) an electrical contact between upper and lower core ( 17a . 17b ). Fitted measuring device ( 20 ) according to at least one of claims 46 and 47, characterized in that the upper and / or the lower core ( 17a . 17b ) rests in the first section on the flat measuring tube outer surface. Equipped measuring device ( 20 ) according to at least one of the claims 44 to 48, with evaluation electronics ( 19 ), which on the measuring tube ( 2 ) and with the measuring electrode ( 3 ) and the magnetic field generating device is electrically connected. Fitted measuring device ( 20 ) according to claim 49, characterized in that the evaluation electronics ( 19 ) has a single board segment, which at positioning elements ( 8th . 9 ) on the measuring tube ( 2 ) is positioned and fastened. Fitted measuring device ( 20 ) according to claims 49 and 50, characterized in that the evaluation electronics ( 19 ) at least two rigid board segments ( 19a ), wherein between two adjacent board segments ( 19a ) a flexible conductor film section ( 19b ) is provided. Fitted measuring device ( 20 ) according to claims 49 and 50, characterized in that the evaluation electronics ( 19 ) has a one-piece board, wherein the board has at least one groove-shaped recesses, which divides the board into at least two board segments. Fitted measuring device ( 20 ) according to claim 51 and 52, characterized in that the board segments on the first and / or the second positioning elements ( 8th . 9 ) on the measuring tube ( 2 ) is positioned and fixed and that the circuit board segments are foldable to each other in such a way that this the measuring tube ( 2 ) in the radial direction at least partially enclose. Magnetic inductive flowmeter ( 16 ), which is a measuring device ( 1 ) according to at least one of the preceding claims, with a housing shell ( 22 ), which is tubular; with one of the housing shell ( 22 ) enclosed measuring device ( 1 ) according to one of the claims 1 to 51; with at least one threaded connector cover ( 21 ), which has fastening means with which this on the housing shell ( 22 ) and / or the measuring device ( 1 ) is attachable. Magnetic inductive flowmeter ( 16 ) according to claim 54, characterized in that the housing jacket ( 22 ) has a circular base. Magnetic inductive flowmeter ( 16 ) according to at least one of claims 54 and 55, characterized in that the housing jacket ( 22 ) has a metal, in particular a stainless steel. Magnetic inductive flowmeter ( 16 ) according to at least one of claims 54 to 56, characterized in that inside the housing shell ( 22 ) is arranged a display device for displaying at least the flow rate of the medium. Magnetic inductive flowmeter ( 16 ) according to at least one of claims 54 to 57, characterized in that the threaded connector cover ( 21 ) in such a way with the measuring device ( 1 ), that the longitudinal axis of the threaded connector cover ( 21 ) and the longitudinal axis of the measuring device ( 1 ) coincide. Method for producing a measuring device ( 1 ) according to any one of claims 1 to 44, comprising the steps of: - providing (S0) an injection mold having a cavity which acts as a negative to a measuring tube ( 2 ) of the measuring device ( 1 ) is trained; Inserting (S1) at least two measuring electrodes ( 3 ) in the injection mold; Injection (S2) of a plastic melt ( 25 ) into the cavity, the measuring electrodes ( 3 ) is surrounded by the plastic melt. A method according to claim 59, characterized in that after the injection of the plastic melt ( 25 ) hardened (S3) and then the cured measuring tube ( 2 ) is demoulded (S4).