DE102020111126A1 - Measuring tube, method for manufacturing a measuring tube and magnetic-inductive flow meter - Google Patents

Abstract

The invention relates to a measuring tube (1) for guiding a flowable medium, in particular for a magnetic-inductive flow measuring device, comprising: a carrier tube (2); wherein the support body (3) is arranged in the support tube (2), the support body (3) having a jacket surface with at least one opening (5), the liner (4) extending through the at least one opening (5), the Measuring tube (1) has a measuring, inlet and outlet section (6, 7, 8), the support body (3) delimiting a cross-sectional area in a cross section, the cross-sectional area in the measuring section (6) being smaller than in the inlet and / or outlet section (7, 8); - a filler body (9), the filler body (9) being arranged between the support body (3) and the carrier tube (2), the filler body (9) in particular being arranged exclusively in the measuring section (6) is, wherein the liner (4) and the filler body (9) touch, a method for producing a measuring tube and a magnetic-inductive flow meter.

Description

The invention relates to a measuring tube for guiding a flowable medium, a method for producing a measuring tube and a magneto-inductive flow measuring device for determining a measured variable that is dependent on the flow rate.

Electromagnetic flowmeters are used to determine the flow rate and volume flow of a flowing medium in a pipeline. An electromagnetic flowmeter has a magnet system that generates a magnetic field perpendicular to the direction of flow of the flowing medium. Individual coils are usually used for this. In order to achieve a predominantly homogeneous magnetic field, pole pieces are additionally shaped and attached in such a way that the magnetic field lines run essentially perpendicular to the transverse axis or parallel to the vertical axis of the measuring tube over the entire pipe cross-section. A pair of measuring electrodes attached to the outer surface of the measuring tube picks up an electrical measuring voltage or potential difference that is perpendicular to the direction of flow and to the magnetic field, which occurs when a conductive medium flows in the direction of flow when a magnetic field is applied. Since, according to Faraday's law of induction, the measured voltage depends on the speed of the flowing medium, the induced measurement voltage U can be used to calculate the flow rate u and, with the addition of a known pipe cross-section, the volume flow 11 be determined.

Magnetic-inductive flowmeters are widely used in process and automation technology for fluids with an electrical conductivity of around 5 µS / cm. Corresponding flow measuring devices are sold by the applicant in a wide variety of embodiments for different areas of application, for example under the name PROMAG.

Electromagnetic flowmeters are sensitive to the flow profile of the medium. Depending on the pipe system and measuring device, measurement errors of several percent can occur. Therefore, a straight tube, the length of which corresponds to at least five to ten times the nominal diameter of the measuring tube, is usually installed on the face on the inlet side. However, applications are known in which this minimum distance, the so-called inlet section, cannot be maintained. This is the case, for example, when a pipe system is in a confined space. The in DE 10 2014 113 408 A1 disclosed invention in which a narrowing of the pipe diameter in the measuring area leads to a conditioning of the flow, which leads to a reduction of flow influences, so that a 0-DN inlet section can be used.

In the DE 10 2013 114 428 A1 A magneto-inductive flowmeter is disclosed with a measuring tube, which has a support tube, a helical recess worked into the support tube, a support body and a liquid applied liner which extends through openings in the support body and, after hardening, via the helical recess in the support tube this is positively connected. The support body has a cylindrical basic shape, the diameter of which decreases in a partial area of the measuring area towards the center. As a result, an intermediate space is formed between the support body inserted in the support tube and the support tube itself.

The disadvantage of this variant is that when the liquid liner is applied, material shrinks in the gap. This leads to a rough and unclean liner surface and, in the worst case, to material breaks in the liner caused by mechanical stress.

The invention is based on the object of remedying the problem.

The object is achieved by the measuring tube according to claim 1, the method for producing a measuring tube according to claim 9 and the magnetic-inductive flow measuring device according to claim 15.

• - ein Trägerrohr;
• - einen insbesondere rohrförmigen Stützkörper zum Stabilisieren eines insbesondere flüssig applizierten Liners,
  • wobei der Stützkörper im Trägerrohr angeordnet ist,
  • wobei der Stützkörper eine Mantelfläche mit mindestens einer Öffnung aufweist,
  • wobei sich der Liner durch die mindestens eine Öffnung erstreckt,
  • wobei das Messrohr einen Mess-, Einlauf- und Auslaufabschnitt aufweist,
  • wobei der Stützkörper in einem Querschnitt eine Querschnittsfläche begrenzt,
  • wobei die Querschnittsfläche im Messabschnitt geringer ist als im Einlauf- und/oder Auslaufabschnitt;
• - einen Füllkörper,
  • wobei der Füllkörper zwischen dem Stützkörper und dem Trägerrohr angeordnet ist,
  • wobei der Füllkörper insbesondere ausschließlich im Messabschnitt angeordnet ist,
  • wobei sich der Liner und der Füllkörper berühren.

The measuring tube according to the invention for guiding a flowable medium, in particular for a magnetic-inductive flow measuring device, comprises:

• - a support tube;
• - an in particular tubular support body for stabilizing an in particular liquid applied liner,
  • wherein the support body is arranged in the support tube,
  • wherein the support body has a lateral surface with at least one opening,
  • wherein the liner extends through the at least one opening,
  • wherein the measuring tube has a measuring, inlet and outlet section,
  • wherein the support body delimits a cross-sectional area in a cross section,
  • wherein the cross-sectional area in the measuring section is smaller than in the inlet and / or outlet section;
• - a packing,
  • wherein the filling body is arranged between the support body and the carrier tube,
  • wherein the filling body is arranged in particular exclusively in the measuring section,
  • whereby the liner and the filler body touch.

A carrier tube is to be understood as an elongated hollow body which usually has a length that is greater than its diameter. The support tube is made of a material, preferably steel or cast iron. Support tubes generally have a circular cross-sectional shape, but support tubes with rectangular, oval and other cross-sectional shapes are also known. Carrier tubes are suitable for use in pipelines in which flowable media such as liquids, gases or free-flowing solids are conveyed.

For the use of the measuring tube in a magnetic-inductive flow measuring device, it is essential that the part of the measuring tube that comes into contact with the medium is electrically insulating. Either electrically insulating support pipes are used for this, or conventional support pipes made of steel or cast iron are provided with an electrically insulating coating, the so-called liner. Hard rubber or plastics such as polyurethanes (PE), perfluoroalkoxy polymers (PFA) or polytetrafluoroethylene (PTFA) are usually used as liner material. These are either applied to the carrier tube in a liquid state or drawn into the carrier tube in a solid state.

The support body is inserted into the carrier tube and serves to stabilize a liquid-applied liner. For this purpose, the support body extends over the entire longitudinal axis of the support tube and is embedded in the material forming the liner. The support bodies known from the prior art are tubular, i.e. the cross-sectional area delimited by the support body is constant over the entire longitudinal axis of the support body, in particular constant within the manufacturing tolerance. In addition, the support body generally extends over the entire inner wall of the support tube. According to the invention, the support body has a clear cross-sectional area in the measuring area which is smaller than the clear cross-sectional area in the inlet area and / or outlet area. Such a reduction in the effective flow cross-section ensures a conditioning of the flow profile in the measuring area and thus a lower flow profile sensitivity.

An opening or several openings are provided in the support body so that the liquid applied liner material on the one hand connects positively to the support body and on the other hand can spread between the carrier tube and the support body in order to embed the support body in the liner. The openings can be designed as perforations or formed by stretching the support body. The support body can be a perforated sheet metal or expanded metal which only has openings in sections or is provided with openings throughout.

In order to ensure that the liner is secured against rotation, according to the relevant prior art, at least one recess is provided in the inner wall of the carrier body, into which the liner extends and thus can form a positive connection between the liner and the carrier tube after curing Prevents twisting of the liner. For this, however, it is essential that the support body has an opening through which the liquid liner material can first flow in order to also reach the depressions. The depressions are usually designed as a helical, thread-like notch, as a dovetail or as an annular groove.

The measuring tube has at least three sections, an inlet section, an outlet section and a measuring section arranged between the inlet section and the outlet section. Additional transition areas can be provided between the inlet section and the measuring section and between the outlet section and the measuring section. The flow measuring device for determining a measured variable that is dependent on the flow rate, in particular the device for tapping a measuring voltage induced in the flowable medium, is arranged in the measuring section.

According to the invention, a filler body is arranged in the measuring area in such a way that it at least partially fills the space formed between the support body and the carrier tube. It can be solid or porous, one-part or multi-part. The filler body is at least partially formed as a hollow cylinder. However, it can also take on the cross-sectional shape of the support body in the measuring area.

The filling body according to the invention is primarily not used to support the support body against the inner wall of the support tube, but rather to avoid material loss when the liquid liner is applied to the support body and thus to produce a flawless liner, in particular a liner surface that is as flawless as possible.

When the liquid liner material is applied, it flows through the opening or openings in the support body and extends along the inner surface of the filling body. As a result, the liner touches the filler body at least partially, for example on an inner surface of the filler body. It also extends the liner is between the support body and filler body. If the filler body is porous, the liquid liner material flows into the porous structures of the filler body and ensures that the liner is anchored to the filler body.

Advantageous refinements of the invention are the subject of the subclaims.

One embodiment provides that the filler body is designed as a hollow cylinder in the measuring section,
wherein a material thickness of the filling body in a first section of the measuring tube between the inlet section and the measuring section decreases in the direction of the inlet section, and / or
wherein the material thickness of the filling body in a second section of the measuring tube between the outlet section and the measuring section decreases in the direction of the outlet section.

Such a configuration has the advantage that fewer spaces are formed between the support tube and the support tube, in which there can be material shrinkage. In addition, a good connection of the filling body to the carrier tube is ensured at the same time, so that less mechanical stress is transferred to the supporting body when the measuring tube is manufactured.

A decrease in the material thickness is implemented according to the invention by changing, i.e. reducing or increasing the cross-sectional area of the filler body in the longitudinal direction.

One embodiment provides that the filler body is circular in cross section and has an inner diameter,
wherein in a first section of the measuring tube between the measuring section and the inlet section, the inside diameter increases in the direction of the inlet section, and / or
wherein in a second section of the measuring tube between the measuring section and the outlet section, the inside diameter increases in the direction of the outlet section.

The material thickness of the filling body does not necessarily have to decrease in the first section and in the second section. According to an advantageous embodiment, the filler body is flexible and band-shaped, which clings to the outer surface of the support body and yields when the support body is deformed without accepting a reduction in the material thickness. According to this embodiment, the measuring tube has sections in which the filling body does not touch the inner surface of the support tube.

One embodiment provides that the support body comprises a perforated sheet metal, in particular a perforated sheet metal, an expanded metal or a grid.

A perforated sheet, also known as a perforated plate, is a perforated sheet made of stainless steel, aluminum, zinc, brass, copper, steel or plastic. The perforated plate has openings which are each designed as a round hole, square hole, elongated hole and / or hexagonal hole. In addition, the openings can have any other desired shape. The openings are produced, for example, by means of a punching process or a laser / water jet / flame cutting process.

An expanded metal comprises an expanded metal mesh made of stainless steel, aluminum, zinc, brass, copper, steel or plastic with rhombus meshes, diamond meshes, long web meshes, hexagonal meshes, square meshes or round meshes. In addition, the meshes can have any other desired shape. Expanded metals are produced, for example, by introducing staggered cuts while stretching a sheet at the same time.

A grid comprises an arrangement of elongated pieces, usually evenly spaced, or a mesh of wires. Corrugated grids, stamped grids or wire grids are suitable as grids.

One embodiment provides that the carrier tube and the filler body are monolithic.

According to a further advantageous embodiment, the filler body is not to be understood as a separate component, but rather as a part of the support tube. This can be worked into the carrier tube, for example, by means of an exciting manufacturing process. Thus, the carrier tube and filler body are monolithic. The advantage of the design is that a further additional component can be dispensed with, as a result of which the assembly of the measuring tube is facilitated.

The support body is accordingly either formed in at least two parts and is preformed or is formed in one piece and at least partially cylindrical. In the latter case, the support body is deformed in the installed state in the support tube, i.e. the inlet and / or outlet section is widened after the support body has been inserted.

One embodiment provides that the filler body is designed to be open-pored,
wherein the liner extends into pores of the filler body.

It is advantageous if the filler body has pores. So the material of the liner can be in extend the pores and thus ensure an anchoring between the filler body and liner. Such a configuration is necessary because if a filler body is present in the measuring area, the liner cannot spread to the depressions in the support tube, where sufficient form-fitting anchoring is usually provided.

The porous material of the filling body can in principle be plastic, for example an open-cell plastic foam, or a ceramic, for example a foam ceramic, or a sintered metal with pores, made of sintered balls, in particular sintered bronze.

One embodiment provides that the filling body comprises a sintered material, in particular sintered balls, which are connected to one another by a sintering process and form pores,
wherein the liner extends in the pores of the filler body.

The material of the filling body is advantageously a sinterable metal, in particular sintered bronze. This material does not fuse into a compact material in the sintering process, but still has sufficient porosity. At the same time, metal is usually more mechanically resistant than plastic and also more thermally resilient. Foam ceramics are often hard and resistant, but tend to break when exposed to vibrations and thermal expansion. The use of such measuring tubes would therefore be limited. In contrast, sintered bronze in particular can be processed very well. Due to the metallic ductility, there is also no material breakage in the event of vibrations. It is particularly advantageous if the material of the filler body is sintered spheres which are connected to one another by a sintering process and which have pores in the spaces between the spheres. As a result, a further improved resistance to pressure loads can be achieved. It is precisely this functionality that is very important when designing a sealing strip of a measuring tube. The sintered balls are particularly preferably made of bronze. For an optimal pore size for connecting the liner, the sintered spheres should have a diameter of more than 0.1 mm.

The filler body is produced separately by filling the sintered balls into a specially provided sintering tool or sintering mold and subsequent thermal treatment in a sintering process in which the sintered balls are connected to one another and thus form the open-pored filler body.

One embodiment provides that the filler body has a recess,
wherein the liner extends in the recess,
wherein the liner is at least positively connected to the filler body.

• - Bereitstellen eines insbesondere teilweise rohrförmigen Stützkörpers und eines, insbesondere einteiligen hohlzylindrischen Füllkörpers,
  • wobei der Stützkörper in einem Querschnitt oder in allen Querschnitten kreisringförmig ausgebildet ist und einen Innendurchmesser aufweist,
• - Anordnen des Füllkörpers um den Stützkörper in eine vorgesehene Position;
• - Einführen des Stützkörpers mit dem angeordneten Füllkörper in einen Trägerrohr;
• - Applizieren und Aushärten lassen eines flüssigen, den Liner bildenden Linermaterials auf den Stützkörper,
  • wobei sich das Linermaterial durch eine Öffnung in einer Mantelfläche des Stützkörper erstreckt und den Füllkörper berührt.

The method according to the invention for producing a measuring tube, in particular a measuring tube according to the invention, comprises the method steps:

• - Provision of an in particular partially tubular support body and an in particular one-piece hollow cylindrical filler body,
  • wherein the support body is circular in a cross-section or in all cross-sections and has an inner diameter,
• - Arranging the filling body around the support body in an intended position;
• - Introducing the support body with the arranged filling body into a carrier tube;
• - Application and hardening of a liquid liner material forming the liner on the support body,
  • wherein the liner material extends through an opening in a lateral surface of the support body and contacts the filler body.

Advantageous refinements of the invention are the subject of the subclaims.

• - Verformen des Stützkörpers, so dass ein Verhältnis zwischen Innendurchmesser des Stützkörpers in einem Messabschnitt und Innendurchmesser des Stützkörpers in einem Einlauf- und/oder einem Auslaufabschnitt von eins abweicht.

One embodiment provides for the process step:

• Deforming the support body, so that a ratio between the inner diameter of the support body in a measuring section and the inner diameter of the support body in an inlet and / or an outlet section deviates from one.

One embodiment provides that the filler body is at least partially hollow-cylindrical before the support body is deformed,
wherein, after the deformation of the support body, the inside diameter of the support body increases in a first subsection between the measuring section and the inlet section of the measuring tube in the direction of the inlet section, and / or
wherein after the deformation of the support body, the inside diameter of the support body increases in a second partial section between the outlet section and the measuring section of the measuring tube in the direction of the outlet section.

One embodiment provides that the support body is designed in two parts,
wherein the packing has an inlet and an outlet,
wherein when the filling body is arranged, a first support body is inserted into the inlet of the filling body and a second support body is inserted into the outlet of the filler body.

One embodiment provides that the first support body delimits a first cross-sectional area in a first cross-section and delimits a second cross-sectional area in a second cross-section,
wherein the first cross-sectional area is smaller than the cross-sectional area of the filling body and the second cross-sectional area is larger than the cross-sectional area of the filling body.

One embodiment provides that the filler body is pushed onto the support body.

• - ein erfindungsgemäßes Messrohr oder ein mittels dem erfindungsgemäßen Verfahren zur Herstellung eines Messrohres hergestelltes Messrohr;
• - eine am Messrohr angeordnete Vorrichtung zum Abgreifen einer im fließfähigen Medium induzierten Messspannung; und
• - eine am Messrohre angeordnete Vorrichtung zum Erzeugen eines das Messrohr durchsetzenden Magnetfeldes.

The magnetic-inductive flow measuring device according to the invention for determining a measured variable that is dependent on the flow rate comprises:

• a measuring tube according to the invention or a measuring tube produced by means of the method according to the invention for producing a measuring tube;
• - A device arranged on the measuring tube for tapping a measuring voltage induced in the flowable medium; and
• - A device arranged on the measuring tube for generating a magnetic field penetrating the measuring tube.

Not essential to the invention, but important for a controlled, defined channel diameter, support sleeves are arranged on the inlet and outlet side in the measuring tube and ensure that the support body is fixed in the longitudinal direction of the support tube and the liner has a reproducible and clearly defined edge in the inlet and outlet.

• 1: eine perspektivische und teilweise geschnittene Darstellung einer Ausgestaltung des erfindungsgemäßen Messrohres;
• 2: einen Längsschnitt durch eine Ausgestaltung des erfindungsgemäßen Messrohres;
• 3: einen Längsschnitt durch eine weitere Ausgestaltung des erfindungsgemäßen Messrohres;
• 4: einen Längsschnitt durch eine weitere Ausgestaltung des erfindungsgemäßen Messrohres;
• 5: eine Ausgestaltung des erfindungsgemäßen Verfahrens zur Herstellung eines Messrohres;
• 6: eine weitere Ausgestaltung des erfindungsgemäßen Verfahrens zur Herstellung eines Messrohres;
• 7: eine weitere Ausgestaltung des erfindungsgemäßen Verfahrens zur Herstellung eines Messrohres; und
• 8: eine Ausgestaltung eines erfindungsgemäßen magnetisch-induktiven Durchflussmessgerätes.

The invention is explained in more detail with reference to the following figures. It shows:

• 1 : a perspective and partially sectioned illustration of an embodiment of the measuring tube according to the invention;
• 2 : a longitudinal section through an embodiment of the measuring tube according to the invention;
• 3 : a longitudinal section through a further embodiment of the measuring tube according to the invention;
• 4th : a longitudinal section through a further embodiment of the measuring tube according to the invention;
• 5 : an embodiment of the method according to the invention for producing a measuring tube;
• 6th : a further embodiment of the method according to the invention for producing a measuring tube;
• 7th : a further embodiment of the method according to the invention for producing a measuring tube; and
• 8th : an embodiment of a magnetic-inductive flow measuring device according to the invention.

the 1 shows a perspective and partially sectioned illustration of an embodiment of the measuring tube according to the invention 1 . The measuring tube 1 comprises a support tube designed as a round tube 2 Made of metal with a channel for guiding a flowable medium. In addition, the carrier tube 2 an inner surface which, depending on the application, is provided with an electrically insulating inner coating, which is also referred to as a liner (in 1 not illustrated). There are several methods of making a support tube 2 to be provided with a liner. On the one hand, the liner can be designed as a solid body in the form of a hose or a tube which is inserted into the carrier tube 2 is drawn in and the ends of which are flanged. Alternatively, the liner can be formed from liner mats which are placed on the inner surface of the support tube 2 to be glued. According to the invention, the liner material forming the liner is in liquid form during the manufacture of the measuring tube and is applied to the inner surface of the carrier tube 2 poured. The liner material is, for example, perfluoroalkoxy polymers (PFA). The measuring tube points to the support of the liquid applied liner material 1 an at least partially tubular support body 3 to stabilize on, which extends along the inner surface of the support tube 2 extends. The support body 3 has at least one opening 5 through which the liquid liner material can flow and thus to a recess provided 20th can get. At the in 1 The embodiment shown is the support body 3 as a rolled and welded perforated sheet - for reasons of clarity, there were only individual openings 5 pictured - and the recess 20th designed as a helical recess in the form of an internal thread. Alternatively, the packing 9 be designed as an expanded metal or a grid, and the opening 5 take any form. In the cured state, the liner extends through the opening 5 and in the recess 20th so that an anchoring of the liner on the support pipe 2 is realized. The support body 3 is supported by two support sleeves arranged at the ends 23 fixed against a shift in the longitudinal direction. For more details on the support sleeves 23 is on the DE 10 2013 114 429 A1 referenced.

According to the invention, the measuring tube 1 a measuring section 6th in which the Support body 3 limited cross-sectional area in the support tube 2 is less than in the inlet section 7th and / or run-out section 8th . Which runs through the inner surface of the support tube 2 and the support body 3 forming cavity is with an in particular partially hollow-cylindrical filler body 9 at least partially filled out. The packing 9 is exclusively in the measuring section 6th arranged. The packing 9 points in the measuring section 6th a constant material thickness which decreases in the direction of the inlet and / or outlet of the measuring tube. The packing 9 includes a cross-sectional area that is constant in the measuring range and increases in the direction of the inlet and / or outlet of the measuring tube.

The liquid applied liner material flows through the in the measuring section 6th arranged openings 5 in the support body 3 and thus touches the packing 9 . It is therefore advantageous if the packing 9 is designed such that the liner is anchored to it. In the embodiment shown, this is due to the open pores of the filler body 9 realized, with the liquid liner material in the pores of the filler body 9 flows, whereby the liner extends into the pores after hardening. The packing 9 comprises a sintered material. The sintered balls forming the sintered material are connected to one another in a sintering process, as a result of which pores are formed between the sintered balls.

The measuring tube shown is suitable for use in a magnetic-inductive flow meter. This is what the carrier tube shows 2 , the support body 3 and the packing 9 two openings for measuring electrodes 21 on. In addition, is in the support tube 2 and in the support body 3 an opening for a level monitoring electrode or a temperature sensor 22nd brought in.

the 2 shows a longitudinal section through the in 1 depicted embodiment of the measuring tube according to the invention. Dashed lines indicate the boundaries of the individual sections. The measuring tube is divided into 5 sections, the inlet section 7th , first section 10 , Measuring section 6th , second section 11 and outlet section 8th . The middle area of the measuring tube is located between the first section 10 and second section 11 arranged measuring section 6th . At least in the measurement section 6th the sensor is also arranged for detecting a measured variable that is dependent on the flow rate. When the measuring tube is used in a magnetic-inductive flow measuring device, the sensor is the device for tapping a measuring voltage induced in the flowable medium. Also in the measurement section 6th In this case, the device for generating a magnetic field penetrating the measuring tube is arranged. The inlet section 7th is the entrance and the outlet section 8th is arranged at the exit. The first part 10 is between the inlet section 7th and measuring section 6th arranged, the second section 11 between measuring section 6th and outlet section 8th is arranged. The measurement section 6th refers to the section of the measuring tube in which the through the support body 3 limited cross-sectional area is not only smaller than in the remaining area of the measuring tube, but also constant. The section in which the cross-sectional area is not constant is called the first partial section 10 and / or second section 11 designated. In the inlet section 7th and / or run-out section 8th is the cross-sectional area as in the measurement section 6th constant. However, the cross-sectional area of the support body is in the inlet section 7th and / or run-out section 8th larger than in the measuring section 6th .

The packing 9 and the support body 3 are in the measurement section 6th hollow-cylindrical, with a substantially constant wall thickness. In the embodiment shown, the filling body is in contact 9 the outer circumferential surface of the support body 3 and also the inner surface of the support tube 2 in the measuring section 6th . In the first section 10 and / or second section 11 takes the cross-sectional area of the support body 3 and the packing 9 essentially continuously increasing. The packing 9 extends exclusively in the measuring section 6th , first section 10 and / or second section 11 .

the 3 shows a longitudinal section through a further embodiment of the measuring tube according to the invention. The configuration shown differs from that in 2 depicted embodiment essentially in that the filling body 9 and the support tube 2 are monolithic. A dotted reference line indicates the course of the support tube 2 if - neglecting the depression - the cross-sectional area of the support tube as in 2 would be essentially constant. The one through the support body 3 and the imaginary reference line bounded area is in this case the packing 9 .

the 4th shows a longitudinal section through a further embodiment of the measuring tube according to the invention, which differs from the one shown in FIG 2 depicted embodiment differs essentially in that the filling body 9 the inner surface of the support tube 2 in the measuring section 6th does not affect and that the wall thickness of the packing 9 is essentially constant in the longitudinal direction. The through the packing 9 limited cross-sectional area is in the measuring section 6th constant and increases in the longitudinal direction without decreasing the wall thickness. The shape of the packing 9 adapts to the shape of the support body 3 at.

the 5 shows an embodiment of the method according to the invention for producing a Measuring tube. The essentially continuous hollow cylindrical filler body 9 is on a tubular support body 3 pushed into an intended position. Between support body 3 and packing 9 Preferably, no cavity is formed in this case. Then either the support body 3 in the inlet section 7th and / or run-out section 8th widened so that the cross-sectional area is larger there than in the central area, the measuring section 6th , or the measurement section 6th narrowed. The expansion leads to the fact that the wall thickness of the filling body 9 does not remain constant, but in the direction of the inlet section 7th and / or outlet section 8th decreases. The narrowing also leads to the cross-sectional area in the measuring section 6th decreases and the cross-sectional area of the support body 3 and packing 9 Longitudinal direction increases. The wall thickness of the packing 9 in the longitudinal direction can in this case - but does not have to be mandatory - remain constant.

In a final step, the support body 3 with the packing 9 inserted together into a carrier tube, fixed and a liquid liner material applied to form the liner.

the 6th shows a further embodiment of the method according to the invention for producing a measuring tube in which the support body 3 Is formed in two parts. The packing 9 has an inlet 12th and an outlet 13th on, with a first support body 14th into the inlet 12th and a second support body 15th into the outlet 13th to be led. The first support body 14th limited in a first cross-section 16 a first cross-sectional area and in a second cross-section 17th a second cross-sectional area. The cross-sectional area is in the second cross-section 17th larger than the cross-sectional area in the first cross-section 16 .

The last step is the packing 9 with the first support body 14th and second support body 15th inserted together into a carrier tube, fixed and a liquid liner material applied to form the liner.

According to one embodiment, the cross-sectional area is in the first cross-section 16 smaller than the cross-sectional area of the filler body 9 and the cross-sectional area in the second cross-section 17th larger than any cross-sectional area of the filler body 9 .

the 7th shows a further embodiment of the method according to the invention for producing a measuring tube in which the filler body 9 and the support tube 2 are monolithic. In that case the support body is 3 formed at least in two parts. The individual parts of the support body 3 have a first cross section 16 having a cross-sectional area that is less than a cross-sectional area in a second cross-section 17th . The individual parts of the support body 3 are laterally in the inlet and outlet of the support tube 2 introduced.

Alternatively, the support body introduced into the carrier tube 3 be in one piece. In that case, after inserting the support body 3 into the carrier tube 2 the support body 3 widened so that the outer surface on the inner surface of the support tube 2 is applied. According to the embodiment shown, only the input section and the output section of the support body are used 3 widened. The middle area in the measurement section 6th remains essentially constant. An additional fixation can be dispensed with.

In a final step, a liquid liner material is used to form the liner on the support body 3 applied.

the 8th shows an embodiment of a magnetic-inductive flow measuring device according to the invention 24 . The electromagnetic flowmeter 24 has a measuring tube according to the invention with an electrically insulating liner 4th , a device for tapping an induced measurement voltage 18th and a device for generating a magnetic field 19th on. The device for tapping an induced measurement voltage 18th and the device for generating a magnetic field 19th is with an operating, measuring and / or evaluation circuit 25th electrically connected. The device for tapping an induced measurement voltage 18th comprises at least two diametrically arranged measuring electrodes. The device for generating a magnetic field 19th comprises two diametrically arranged coils with coil cores and pole pieces, which are arranged on an outer surface of the support tube, and a field return, which connects the coil cores of the two coils to one another.

List of reference symbols

1

Measuring tube

2

Support tube

3

Support body

4th

Liner

5

opening

6th

Measuring section

7th

Inlet section

8th

Outlet section

9

Packing

10

first section

11

second section

12th

inlet

13th

Outlet

14th

first support body

15th

second support body

16

first cross section

17th

second cross section

18th

Device for tapping an induced measurement voltage

19th

Device for generating a magnetic field

20th

deepening

21

Opening for measuring electrode

22nd

Opening for level monitoring electrode / temperature sensor

23

Support sleeve

24

Electromagnetic flow meter

25th

Operating, measuring and / or evaluation circuit

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102014113408 A1 [0004]
• DE 102013114428 A1 [0005]
• DE 102013114429 A1 [0049]

Claims (15)

Measuring tube (1) for guiding a flowable medium, in particular for a magnetic-inductive flow measuring device (24), comprising: - A carrier tube (2); - an in particular tubular support body (3) for stabilizing an in particular liquid applied liner (4), wherein the support body (3) is arranged in the carrier tube (2), wherein the support body (3) has a lateral surface with at least one opening (5), wherein the liner (4) extends through the at least one opening (5), wherein the measuring tube (1) has a measuring, inlet and outlet section (6, 7, 8), wherein the support body (3) delimits a cross-sectional area in a cross section, wherein the cross-sectional area in the measuring section (6) is smaller than in the inlet and / or outlet section (7, 8); - a packing (9), wherein the filling body (9) is arranged between the supporting body (3) and the carrier tube (2), wherein the filling body (9) is arranged in particular exclusively in the measuring section (6), the liner (4) and the filler body (9) touching one another. Measuring tube (1) Claim 1 , wherein the filling body (9) in the measuring section (6) is designed as a hollow cylinder, with a material thickness of the filling body (9) in a first section (10) of the measuring tube (1) between the inlet section (7) and measuring section (6) in the direction of the inlet section ( 7) decreases, and / or wherein the material thickness of the filling body (9) decreases in a second section (11) of the measuring tube (1) between the outlet section (8) and the measuring section (6) in the direction of the outlet section (8). Measuring tube (1) Claims 1 and / or 2, the filler body (9) being circular in cross section and having an inner diameter, the inner diameter in the direction of the inlet section in a first section (10) of the measuring tube (1) between the measuring section (6) and the inlet section (7) (7) increases, and / or wherein in a second section (11) of the measuring tube (1) between the measuring section (6) and the outlet section (8) the inner diameter increases in the direction of the outlet section (8). Measuring tube (1) after at least one of the Claims 1 until 3 wherein the support body (9) comprises a perforated sheet metal, in particular a perforated sheet metal, an expanded metal or a grid. Measuring tube (1) after at least one of the Claims 1 until 4th , wherein the support tube (2) and the filler body (9) are monolithic. Measuring tube according to at least one of the preceding claims, wherein the filling body (9) is open-pored, wherein the liner (4) extends into pores of the filling body (9). Measuring tube according to at least one of the preceding claims, wherein the filling body (9) comprises a sintered material, in particular sintered balls, which are connected to one another by a sintering process and form pores, wherein the liner (4) extends in the pores of the filling body (9). Measuring tube according to at least one of the preceding claims, wherein the filling body (9) has a recess, wherein the liner (4) extends in the recess, wherein the liner (4) is at least positively connected to the filler body (9). Method for producing a measuring tube (1), in particular a measuring tube (1) according to at least one of the Claims 1 until 8th , comprising the method steps: - providing an in particular partially tubular support body (3) and an in particular one-piece hollow cylindrical filling body (9), the supporting body (3) being circular in one cross-section or in all cross-sections and having an inner diameter, - arranging the filling body (9) around the support body (3) in an intended position; - Introducing the support body (3) with the arranged filling body (9) into a carrier tube (2); - Application and hardening of a liquid, a liner (4) forming liner material on the support body (3), wherein the liner material extends through an opening (5) in a lateral surface of the support body (3) and touches the filler body (9). Procedure according to Claim 9 - Deforming the support body (3) so that a ratio between the inner diameter of the support body (3) in a measuring section (6) and the inner diameter of the support body (3) in an inlet section (7) and / or an outlet section (8) deviates from one . Procedure according to Claim 10 , wherein the filling body (9) is at least partially hollow-cylindrical before deforming the support body (3), wherein after the deformation of the support body (3) the inner diameter of the support body (3) increases in a first section (10) between the measuring section (6) and inlet section (7) of the measuring tube (1) in the direction of the inlet section (7), and / or wherein after the deformation of the support body (3), the inside diameter of the support body (3) increases in a second section (11) between the outlet section (8) and the measuring section (6) of the measuring tube (1) in the direction of the outlet section (8). Procedure according to Claim 11 , wherein the support body (3) is designed in two parts, the filling body (9) having an inlet (12) and an outlet (13), with a first support body (14) in the inlet (12) when the filling body (9) is arranged of the filling body (9) is introduced and a second supporting body (15) is introduced into the outlet (13) of the filling body (9). Procedure according to Claim 12 , the first support body (14) delimiting a first cross-sectional area in a first cross-section (16) and delimiting a second cross-sectional area in a second cross-section (17), the cross-sectional area in the first cross-section (16) being smaller than the cross-sectional area of the filling body (9) and the cross-sectional area in the second cross-section (17) is greater than any cross-sectional area of the filling body (9). Procedure according to Claim 9 and / or 10, the filling body (9) being pushed onto the supporting body (3). Magnetic-inductive flow measuring device (24) for determining a measured variable that is dependent on the flow rate, comprising: - a measuring tube (1) according to at least one of the Claims 1 until 8th or by means of the method for producing a measuring tube (1) according to at least one of the Claims 9 until 14th manufactured measuring tube (1); - A device arranged on the measuring tube (1) for tapping a measuring voltage (18) induced in the flowable medium; and - a device arranged on the measuring tube for generating a magnetic field (19) penetrating the measuring tube.

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