DE102019126705A1 - Sensor, measuring tube and electromagnetic flow measuring point - Google Patents

Abstract

The invention relates to a magnetic-inductive flow measuring point, a measuring tube (2) and a measuring sensor (1) for detecting a flow rate-dependent measuring voltage induced in a flowing medium, comprising: - a housing (3); - a front body (4), which the Housing (3) closes at the end; - A field system, at least partially arranged in the housing (3), for generating a magnetic field, the field system having a coil core (5) and a coil (6), the coil (6) around the coil core (5) - a measuring circuit (24) for detecting the measuring voltage induced on measuring electrodes, the measuring circuit (24) being arranged in the housing (9); characterized in that the front body (4) has a through opening (7) and that the Coil core (5) extends through the opening (7) of the front body (4) and protrudes from an end face (8) of the front body (4).

Description

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 the measured voltage, according to Faraday's law of induction, depends on the speed of the flowing medium, the flow rate u and, with the addition of a known pipe cross-section, the volume flow V can be determined from the induced measurement voltage U.

In contrast to a magneto-inductive flow measuring device, magneto-inductive flow measuring probes with their usually circular cylindrical housing are inserted into a lateral opening of a pipeline and fixed in a fluid-tight manner. A special measuring tube is no longer necessary. The mentioned coil arrangement on the outer surface of the measuring tube is omitted because the magnetic field only exists in the area of the front end of the flow measuring probe protruding into the fluid or is generated in this area by a current flowing through its coil arrangement. For this purpose, the magnet system is usually arranged inside the housing and in the immediate vicinity of the measuring electrodes, so that an axis of symmetry of the generated magnetic field lines perpendicularly intersects the area between the measuring electrodes. The measuring electrodes are arranged either on the front surface or on the side surfaces of the housing.

So far there are only a few flowmeters that make use of Faraday's law of magnetic induction and at the same time are suitable for so-called single-use applications in which the interchangeability of the components in contact with the medium is required.

The DE 10 2016 118 064 A1 teaches a magnetic-inductive flowmeter which has a U-shaped measuring tube holder for exchangeable measuring tubes. The magnet system is located in the measuring device housing and the mating contacts for the measuring electrodes in the measuring tube are located in the measuring tube holder.

The invention is based on the object of providing an alternative solution for single-use applications.

The object is achieved by the measuring sensor according to claim 1, the measuring tube according to claim 5 and the magnetic-inductive flow measuring point according to claim 13.

• - ein Gehäuse;
• - einen Frontkörper, welcher das Gehäuse stirnseitig abschließt;
• - ein zumindest teilweise im Gehäuse angeordnetes Feldsystem zur Erzeugung eines Magnetfeldes, wobei das Feldsystem einen Spulenkern und eine Spule aufweist, wobei die Spule um den Spulenkern angeordnet ist;
• - eine Messschaltung zum Erfassen der an Messelektroden induzierten Messspannung,

wobei die Messschaltung im Gehäuse angeordnet ist;
und ist dadurch gekennzeichnet,
dass der Frontkörper eine durchgehende Öffnung aufweist und
dass der Spulenkern sich durch die Öffnung des Frontkörpers erstreckt und aus einer stirnseitigen Frontfläche des Frontkörpers hervorsteht.The sensor according to the invention for detecting a flow velocity-dependent measurement voltage induced in a flowing medium comprises:

• - a housing;
• - A front body which closes the housing at the front;
• - A field system arranged at least partially in the housing for generating a magnetic field, the field system having a coil core and a coil, the coil being arranged around the coil core;
• - a measuring circuit for recording the measuring voltage induced on measuring electrodes,

wherein the measuring circuit is arranged in the housing;
and is characterized by
that the front body has a through opening and
that the coil core extends through the opening of the front body and protrudes from an end face of the front body.

In conventional magnetic-inductive flow measuring probes, the field system is arranged in the housing and protected from the flowing medium in the pipeline by the casing of the housing and the front body. So that the magnetic flux density in the medium is maximized, the coil core of the field system is arranged as close as possible to the outer surface of the casing or the front surface of the front body.

For single-use applications, the sensor should be easy to install on an exchangeable measuring tube or disposable measuring tube. However, the sensor should not come into contact with the flowing medium. Therefore, the measuring transducer preferably also does not have any measuring electrodes that are in contact with the medium. However, the measuring circuit of the measuring transducer arranged in the housing is set up to tap a measuring voltage that is applied to measuring electrodes that are in contact with the flowing medium. A separable connection between the measuring circuit and the measuring electrodes is provided for this.

The front body, which is usually set up to form a separation between the field system and the medium, advantageously has an opening through which the coil core extends. If the measuring sensor is attached to the exchangeable measuring tube, the coil core comes into direct contact with the outer wall of the measuring tube or with a partition specially provided for the measuring sensor. Accordingly, the coil core is preferably separated from the channel of the measuring tube exclusively by the wall of the measuring tube or by the partition. According to the inventive embodiment, the distance between the coil core and the medium can be reduced and the resulting magnetic flux density in the medium can be maximized.

The housing and the front body can be formed in one piece.

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

One embodiment provides that the housing and the front body are designed in two parts,
wherein the housing is connected to the front body via a connecting body,
wherein the front body is at least partially enclosed by the connecting body and / or fixed in the connecting body, in particular being arranged pressed in.

For the production of the measuring transducer, it is advantageous if the front body and the housing are designed in two parts. As a result, the front body can be adapted to changing measurement conditions without having to fundamentally change the entire housing concept.

Furthermore, it is advantageous if the housing is connected to the front body via a connecting body and the front body is fixed in the connecting body. The fixation takes place through the deformation, in particular the pressing together of the connecting body. The connecting body is preferably tubular and at least partially engages around the coil core. In an advantageous embodiment, the housing encloses the connecting body, as a result of which a further stabilization of the measuring transducer is realized.

One embodiment provides that the measuring sensor has a return body for returning the magnetic field,
wherein the return body is formed by the connecting body.

The measuring transducer preferably has a feedback body which guides the magnetic field lines that emerge from the front area of the coil core back to the coil core and thus minimizes stray magnetic fields. In an advantageous embodiment, the return body is formed by the connecting body. In this case, the connecting body is at least partially formed from a soft magnetic material.

The connecting body thus serves to attach the front body to the housing and to guide the magnetic field.

One embodiment provides that the housing has a locking device, in particular a bayonet lock,
wherein the closure device is arranged coaxially to the connecting body and engages around it.
wherein the closure device is tensioned linearly via an elastic form element.

The housing preferably has a bayonet lock with which the measuring sensor can be fixed to the measuring tube, in particular to a receiving device of the measuring tube. To fix it, the sensor is inserted into the mounting device and fastened by turning the bayonet catch. The principle of a bayonet lock is well known. The elastic molded element can be an O-ring, for example.

• - einen Messrohrkörper, welcher aus einem elektrisch isolierenden Material gebildet ist;
• - einen Kanal zum Führen eines fließfähigen Mediums;
• - mindestens zwei Messelektroden zum Bilden eines galvanischen Kontaktes mit dem Medium und zum Abgreifen einer im fließenden Medium induzierten Messspannung;

und ist dadurch gekennzeichnet,
dass der Messrohrkörper eine Aufnahmevorrichtung zur Aufnahme eines Messaufnehmers, insbesondere des Messaufnehmers nach einem der vorherigen Ansprüche aufweist und
dass die Aufnahmevorrichtung ein Sackloch aufweist, zur Aufnahme eines Spulenkerns.The measuring tube according to the invention comprises:

• - A measuring tube body, which is formed from an electrically insulating material;
• - A channel for guiding a flowable medium;
• - At least two measuring electrodes for forming a galvanic contact with the medium and for tapping a measuring voltage induced in the flowing medium;

and is characterized by
that the measuring tube body has a receiving device for receiving a measuring transducer, in particular the measuring transducer according to one of the preceding claims, and
that the receiving device has a blind hole for receiving a coil core.

The measuring tube preferably has a receiving device which is designed to attach the measuring sensor to the measuring tube in an installation-friendly manner and to connect the two at least in a form-fitting manner. For this purpose, the receiving device has a blind hole into which the coil core of the measuring transducer is inserted.

The measuring tubes according to the invention serve as a single-use product in biopharmaceutical applications, ie the measuring tube is exchanged after each completed application. According to the invention, the measuring electrodes are also exchanged with the contaminated measuring tube.

The measuring electrodes preferably each have a longitudinal axis which runs in a common pipe cross section, perpendicular to the direction of flow. The measuring electrodes have contact surfaces that are in contact with the medium. A reference straight line connecting the two measuring electrodes, in particular the respective contact surfaces, runs perpendicular to the direction of flow.

One embodiment provides that the receiving device comprises a recess which, in particular, has a circular cross-section.

So that the measuring sensor remains firmly stuck in the receiving device, a recess is provided in the receiving device, which ensures that the contact area between the measuring tube body and the measuring sensor increases. The recess is designed as a recess and is shaped complementary to the shape of the housing of the measuring transducer.

One embodiment provides that the receiving device has a partition which separates part of the receiving device from the channel.

Receiving devices for attaching magnetic-inductive flow measuring probes to a pipeline are known. These are usually attached to an opening in the outer surface of the pipe. The flow measuring probe extends through the opening into the interior of the pipe and the medium flows around it.

The receiving device advantageously has a partition which separates the measuring transducer, in particular the coil core of the measuring transducer, from the flowing medium in the channel. This avoids time-consuming cleaning of the sensor after each use.

One embodiment provides that the measuring electrodes are attached in the receiving device.

It is particularly advantageous if the measuring electrodes are attached in the receiving device and not, as usual, in the measuring transducer itself. Inserting the measuring transducer into the receiving device simultaneously leads to an electrical connection of the measuring electrodes to the measuring circuit of the measuring transducer. If the measuring tube is exchanged after use, the measuring electrodes attached to the receiving device are also exchanged.

A reference straight line connecting two measuring electrodes, in particular the respective contact surfaces, preferably runs perpendicular to the direction of flow of the medium.

One embodiment provides that the channel has an inlet-side area, an outlet-side area and a measuring area located between the inlet-side and outlet-side area,
wherein the recording device is arranged in the measuring area,
wherein the channel has a first cross-section with a first cross-sectional area in the inlet-side area,
wherein the channel has a second cross-section with a second cross-sectional area in the measuring area,
wherein the second cross-sectional area is smaller than the first cross-sectional area.

The front areas of the measuring electrodes are preferably not located in the immediate vicinity of the inner wall of the measuring tube body, but rather protrude into the channel of the measuring tube, as is usually known from magnetic-inductive flow measuring probes. For this purpose, the measuring tube body is shaped in such a way that the measuring area of the measuring tube has a reduced cross-sectional area. The reduction of the flow cross-section also ensures flow conditioning.

One embodiment provides that the channel has a longitudinal axis,
wherein the channel in the measuring area is designed as a circular segment in at least one cross section perpendicular to the longitudinal axis,
wherein the channel has a longitudinal plane which is cut perpendicularly by a longitudinal axis of the receiving device,
wherein the longitudinal plane divides the channel into a first and a second section,
wherein the first section along the inlet-side area and along the measuring area is designed as a half cylinder.

One embodiment provides that the measuring tube body is made of an insulating material, in particular a plastic and preferably polyetheretherketones, polyaryletherketones, polyphenylsulfones, polyethersulfones, polysulfones, polyarylamides, glass and / or ceramics.

There is a demand for flowmeters with disposable measuring tubes for biopharmaceutical applications. For this, the materials that come into contact with the medium must be biocompatible and gamma-sterilizable. It is therefore particularly advantageous if the measuring tube is off one of the above materials is made, as these meet the biopharmaceutical requirements.

One embodiment provides that the receiving device and the measuring tube body are formed in one piece.

It is particularly advantageous if the receiving device and the measuring tube body are formed in one piece, as a result of which the measuring tubes can be manufactured easily and inexpensively. This can be realized, for example, by means of an injection molding process.

• - einen Messaufnehmer, insbesondere den erfindungsgemäßen Messaufnehmer, wobei der Messaufnehmer ein Gehäuse, eine Messschaltung, mindestens zwei Anschlusskontakte, eine Spule, einen Spulenkern und eine Frontfläche aufweist;
• - ein Messrohr, insbesondere das erfindungsgemäße Messrohr,

wobei das Messrohr einen Kanal, einen Messrohrkörper, mindestens zwei Messelektroden und eine Aufnahmevorrichtung aufweist;
und ist dadurch gekennzeichnet,
dass der Messaufnehmer derart ausgebildet, um mit dem Messrohr trennbar verbunden zu werden, und
dass der Messaufnehmer in die Aufnahmevorrichtung des Messrohres eingeführt ist,
wobei ein Endabschnitt des Spulenkerns durch eine Trennwand vom Kanal des Messrohres getrennt ist,
wobei die Trennwand und der Messrohrkörper des Messrohres einstückig ausgebildet sind.The magnetic-inductive flow measuring point according to the invention comprises:

• a measuring sensor, in particular the measuring sensor according to the invention, the measuring sensor having a housing, a measuring circuit, at least two connection contacts, a coil, a coil core and a front surface;
• - a measuring tube, in particular the measuring tube according to the invention,

wherein the measuring tube has a channel, a measuring tube body, at least two measuring electrodes and a receiving device;
and is characterized by
that the measuring transducer is designed in such a way that it can be detachably connected to the measuring tube, and
that the sensor is inserted into the receiving device of the measuring tube,
an end section of the coil core being separated from the duct of the measuring tube by a partition wall,
wherein the partition and the measuring tube body of the measuring tube are formed in one piece.

Magnetic-inductive flow measuring probes are passed through an opening in a pipeline and fastened in a fluid-tight manner. The field system is arranged in the housing and is protected from the medium by the front body and the housing wall. The generated magnetic field extends through the wall of the housing and the front body and into the medium. However, the housing of the flow measuring probe and the measuring electrodes are in contact with the medium. The areas and components in contact with the medium would therefore have to be replaced or laboriously cleaned after each use. For this reason, flow measuring probes in the known form are not suitable for single-use applications.

For single-use applications it is particularly advantageous if the housing of the measuring sensor and the measuring electrodes do not come into contact with the medium. This is achieved by a partition that separates the field system from the flowing medium. Connection contacts that are not in contact with the medium are designed to be connected to the measuring electrodes that are in contact with the medium in a separable manner.

Furthermore, it is advantageous if the sensor can easily be attached to and detached from the measuring tube. The receiving device according to the invention is provided for this purpose.

In conventional magnetic-inductive flowmeters, which are suitable for single-use applications, the measuring tube is inserted into a receptacle arranged in the housing. According to the invention, the measuring tube has a receiving device into which the measuring sensor can be inserted or attached. This results in two mounting options. In the first case, the measuring tube is attached and the sensor is guided into the receiving device by a straight movement. In the second case, the sensor is fixed and the measuring tube is attached to the sensor by means of a straight movement.

One embodiment provides that the receiving device is designed to be complementary to the measuring transducer, so that the measuring transducer can be inserted into the receiving device in a form-fitting manner.

This can be implemented, for example, by a molding or a recess in the area of the receiving device.

One embodiment provides that the measuring electrodes are electrically connected to the measuring circuit through the connection contacts.

In order to establish an electrical connection between the measuring electrodes and the measuring circuit, the measuring sensor has connection contacts which are electrically connected to the measuring circuit and which form a separable electrical contact with the measuring electrodes when the measuring sensor is inserted into the receiving device. Since the connection contacts do not come into contact with the medium, they do not have to be replaced after each use.

It is advantageous if the coil core and the connecting body are arranged coaxially.

It is advantageous if the receiving device is designed in such a way that the measuring tube can be connected to the measuring transducer in a form-fitting and / or force-fitting manner via a closure device.

It is advantageous if the receiving device has a recess for receiving the housing comprises, which has an annular cross-section.

It is advantageous if an O-ring is inserted in the plug-in device, in particular in the recess, which O-ring is designed to be deformed in the event of a non-positive connection of the measuring transducer to the measuring tube.

• 1: eine magnetisch-induktive Durchflussmesssonde nach dem Stand der Technik;
• 2: eine magnetisch-induktive Durchflussmesssonde in einer Rohrleitung nach dem Stand der Technik;
• 3: eine perspektivische Darstellung einer Ausgestaltung des erfindungsgemäßen Messaufnehmers;
• 4: ein Längsschnitt der Ausgestaltung des erfindungsgemäßen Messaufnehmers;
• 5: eine Frontansicht der Ausgestaltung des erfindungsgemäßen Messaufnehmers;
• 6: ein Längsschnitt einer Ausgestaltung des erfindungsgemäßen Messrohres;
• 7: eine Draufsicht der Ausgestaltung des erfindungsgemäßen Messrohres;
• 8: ein Querschnitt der Ausgestaltung des erfindungsgemäßen Messrohres;
• 9: eine perspektivische Darstellung der Ausgestaltung des erfindungsgemäßen Messrohres; und
• 10: ein Längsschnitt einer Ausgestaltung der erfindungsgemäßen magnetisch-induktiven Durchflussmessstelle.

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

• 1 : a magneto-inductive flow measuring probe according to the prior art;
• 2 : a magneto-inductive flow measuring probe in a pipeline according to the prior art;
• 3 : a perspective view of an embodiment of the measuring transducer according to the invention;
• 4th : a longitudinal section of the configuration of the measuring sensor according to the invention;
• 5 : a front view of the configuration of the measuring sensor according to the invention;
• 6th : a longitudinal section of an embodiment of the measuring tube according to the invention;
• 7th : a plan view of the configuration of the measuring tube according to the invention;
• 8th : a cross section of the configuration of the measuring tube according to the invention;
• 9 : a perspective view of the configuration of the measuring tube according to the invention; and
• 10 : a longitudinal section of an embodiment of the magnetic-inductive flow measuring point according to the invention.

Based on the perspective and partially sectioned representation of the 1 the measuring principle on which the invention is based is explained first. A flow measuring probe 1.01 comprises a generally circular cylindrical housing having a predetermined outer diameter 1.03 . This is adapted to the diameter of an opening in a wall of an in 1 not, however in 2 shown pipeline 1.13 is located and in which the flow measuring probe 1.01 is plugged in fluid-tight. In the pipeline 1.13 A medium to be measured flows into which the flowmeter probe 1.01 immersed practically perpendicular to the direction of flow of the medium indicated by the wavy arrows 1.12 is indicated. A front end protruding into the medium 1.02 of the housing 1.03 is with a front body 1.06 sealed fluid-tight from insulating material. By means of one in the housing 1.03 arranged coil arrangement 1.09 a magnetic field can be passed through the front surface into the medium 1.08 produce. One at least partially made of a soft magnetic material in the housing 1.02 arranged coil core 1.07 ends at or near the front end. A regression 1.10 who have favourited the coil assembly 1.09 and the coil core 1.07 encloses, the magnetic field reaching through from the front end is set up for this purpose 1.08 in the housing 1.03 traced back. The coil core 1.07 who have favourited the coil assembly 1.09 and a return 1.10 form a magnetic field generating device. A first and a second galvanic measuring electrode 1.04 , 1.05 are in the front body 1.06 arranged and touch the medium. At the measuring electrodes 1.04 , 1.05 an electrical measurement voltage induced on the basis of Faraday's law of induction can be determined by means of a measurement and / or evaluation unit 1.11 tap. The measuring voltage is at its maximum when the flow measuring probe is in the pipeline in this way 1.13 is built in that one through one of the two measuring electrodes 1.04 , 1.05 intersecting straight line and a longitudinal axis of the flow measuring probe spanned plane perpendicular to the flow direction 1.12 or the longitudinal axis of the pipeline 1.21 runs.

The 2 represents a flow measuring probe built into a pipeline 1.01 in longitudinal section. The flow measuring probe 1.01 is by means of a receiving device that has a screw-in connection 1.14 includes, in the wall of the pipeline 1.13 used and welded to her, for example, in the pipeline 1.13 attached fluid-tight. This structure of the measuring point is particularly useful since the screw-in connection is first 1.14 into the pipeline 1.13 can be inserted and welded into it and only then the flow measuring probe 1.01 into the screw-in connection 1.14 inserted, in turn screwed into it and by means of a seal 1.15 needs to be sealed. The first and second measuring electrodes 1.04 , 1.05 are on the front end 1.02 symmetrical about a center 1.06 of the front end 1.02 arranged. All measuring electrodes 1.04 , 1.05 lie on an imaginary straight line. The installation depth D indicates how deep the flow measuring probe protrudes into the medium or into the pipe.

The 3 shows three configurations of the measuring sensor according to the invention 1 . The sensor 1 is formed according to this embodiment by an adapted magnetic-inductive flow measuring probe. The sensor 1 is set up to be attached to an exchangeable measuring tube, in particular in a receiving device of a measuring tube (in 3 not, but in 6th shown) to be attached and to determine a flow rate measurement of the medium flowing through the measuring tube. It includes a housing 3 that extends up to the front body 4th extends and in the 3 is only partially shown. The pictured case 3 and the front body 4th are formed in two parts, but they can also be formed in one piece. In the case 3 a field system is arranged, comprising at least one coil core 5 and at least one coil. According to the first embodiment (left) and the second embodiment (center), the field system is exclusively in the housing 3 arranged. The field system is at least through the front body 4th spaced from the medium. According to the third embodiment (right), the coil core extends 5 through an opening 7th in the front body 4th and stands out from the front 8th of the front body 4th emerged. The longitudinal axis of the coil core 5 cuts the front surface 8th essentially perpendicular. The front body 4th is in a connecting body 9 attached, which at the same time as a return body 10 serves. For this, it is formed at least partially from a soft magnetic material. The feedback body 10 guides the magnetic field lines emerging from the front area of the coil core 5 exit back to the end of the coil core 5 . The front area of the coil core 5 is the part that comes out of the front body 4th protrudes and the end portion of the coil core 5 is the area that is in the housing 3 is located. The coil core can 5 and the return body 10 be formed in one piece or in two pieces. The front body 4th is a disc with a central opening 7th . The coil core 5 is circular cylindrical and the housing 3 tubular. The case 3 has a locking device 11 on, which is designed as a bayonet lock according to this embodiment. According to the three refinements, the measuring sensor 1 Connection contacts 26th which are electrically connected to a measuring circuit (not shown) and are set up to produce a separable contact with measuring electrodes or other electrodes that a measuring tube has. According to the first and third embodiment, the connection contacts are 26th designed to be resilient and adapted to the arrangement of the measuring electrodes or the connection contacts in the measuring tube. According to the second embodiment, the connection contacts are 26th as sockets for pins which are arranged on a circuit board or designed as part of a connector.

The 4th shows a longitudinal section through the design of the measuring transducer 1 . Inside the case 3 is a coil 6th arranged on the bobbin 5 is postponed and embraces this. The coil core 5 and the return body 10 are formed in one piece. The coil core 5 has three characteristic areas. The coil core is in a first area 5 shaped as a circular cylinder and has a first cross section. The coil core is in a further second area 5 again shaped as a circular cylinder. In the second area, however, it has a second cross section. It applies that the second cross section is larger than the first cross section. A third area of the coil core 5 is designed as a hollow cylinder. This third area is through the return body 10 educated. All three areas are arranged concentrically to the longitudinal axis of the sensor. According to this embodiment, the three areas form a one-piece body. A measuring circuit is located inside the housing 24 which is set up to measure the measuring voltage induced between two measuring electrodes. The front body 8th and the connecting body 9 are pressed together.

The 5 shows a front view of the configuration of the measuring sensor according to the invention 1 . The coil core 5 , the front body 4th , the feedback body 10 or the connecting body 9 and the hollow cylindrical part of the housing 3 are arranged concentrically to the longitudinal axis of the sensor. The case 3 encloses the connecting body 9 . Two connection contacts lie on an imaginary straight line.

The 6th shows an embodiment of the measuring tube according to the invention 2 . In 6th , 7th , 8th , 10 and 11 are the measuring electrodes 14th shown offset by 90 ° for a clearer representation. However, a measuring voltage proportional to the flow velocity in the longitudinal direction of the channel 13th To tap the flowing medium, a straight line intersecting the two measuring electrodes must run perpendicular to the direction of flow of the medium. The measuring tube 2 has a measuring tube body 12th on which one channel 13th forms through which the medium is passed. The measuring tube body also forms 12th a receiving device 15th . This has a blind hole 16 on, into which the coil core of the sensor (not shown) is inserted. The shape of the blind hole 16 is complementary to the shape of the coil core 5 educated. According to this embodiment, the blind hole has 16 at least partially on a circular cylindrical cross-section. Between the blind hole 16 and the inside of the measuring tube is a partition 18th that the inserted coil core 5 separates from the medium. Furthermore, the receiving device 15th a depression 17th which is designed to accommodate part of the housing of the measuring transducer and thus to ensure a stable attachment of the measuring transducer to the measuring tube. The depression 17th is shaped complementary to the shape of the part of the housing to be received. According to this embodiment, the recess 17th the shape of a circular ring. The measuring tube body 12th is formed from an electrically insulating material such as PEEK. On or in the measuring tube body 12th are two measuring electrodes 14th appropriate.

The channel 13th has different cross-sectional areas along the direction of flow. In the inlet and outlet area 19th , 20th the channel has a first cross-sectional area. In the middle area of the channel, which is also called the measuring area 21 because the field system and the measuring electrodes are located in this area 14th are located, the channel has a second cross-sectional area which is smaller than the first cross-sectional area. The purpose of this form is that the contact surfaces of the measuring electrodes that come into contact with the medium are spaced as far as possible from the measuring tube wall.

The 7th shows a plan view of the design of the measuring tube 2 . The blind hole 16 has a circular and the recess 17th an annular cross-section. The measuring electrodes 14th have an at least partially round cross-section.

The 8th shows a cross section in the measuring area through the measuring tube 2 and the receiving device 15th . The channel takes on the shape of a segment of a circle. The channel 13th has a longitudinal plane passing through a longitudinal axis 23 the receiving device 15th is cut vertically. This longitudinal plane divides the channel 13th into a first and a second section, the first section along the inlet-side area 19th , the outlet-side area 20th and the measuring range 21 is designed as a half cylinder.

The 9 shows a perspective view of the configuration of the measuring tube according to the invention.

The 10 shows a longitudinal section through an embodiment of the measuring transducer 1 , which is based on a further embodiment of the measuring tube 2 is attached and thus forms the magnetic-inductive flow measuring point according to the invention. The measuring tube 1 is in the cradle 15th of the measuring tube 1 inserted and fixed by means of the bayonet lock. The coil core 5 is through the partition 18th of the flowing medium in the canal 13th spaced. The measuring electrodes 14th protrude into the canal 13th and are designed to form a galvanic contact with the flowable medium. Connection contacts 26th are separable with the measuring electrodes 14th connected and form an electrical connection between the measuring electrodes 14th and the measuring circuit 24 . A deformable sealant 26th in the form of an O-ring is between the bayonet lock and the partition 18th arranged and serves as a force-fit connection between the sensor 1 and the measuring tube 2 to realize. When the bayonet lock is rotated, the O-ring is deformed and part of the bayonet lock gets caught in the connection device 15th .

List of reference symbols

1.01

Flow measuring probe

1.02

Front end

1.03

casing

1.04

first measuring electrode

1.05

second measuring electrode

1.06

Front body

1.07

Coil core

1.08

Magnetic field lines

1.09

Coil arrangement

1.10

return

1.11

Measuring, operating and / or evaluation unit

1.12

Direction of flow

1.13

Pipeline

1.14

Screw-in connection

1.15

poetry

1.16

Measuring electrode

1.17

Reference line

1

Sensor

2

Measuring tube

3

casing

4th

Front body

5

Coil core

6th

Kitchen sink

7th

opening

8th

Front surface

9

Connecting body

10

Feedback body

11

Locking device

12th

Measuring tube body

13th

channel

14th

Measuring electrode

15th

Cradle

16

Blind hole

17th

deepening

18th

partition wall

19th

upstream area

20th

downstream area

21

Measuring range

22nd

Longitudinal axis of the channel

23

Longitudinal axis of the receiving device

24

Measuring circuit

25th

Sealant

26th

Connection contacts

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 102016118064 A1 [0004]

Claims (15)

Measuring transducer (1) for detecting a flow rate-dependent measuring voltage induced in a flowing medium, comprising: - a housing (3); - A front body (4) which closes the housing (3) at the end; - A field system arranged at least partially in the housing (3) for generating a magnetic field, the field system having a coil core (5) and a coil (6), the coil (6) being arranged around the coil core (5); - A measuring circuit (24) for detecting the measuring voltage induced on measuring electrodes, the measuring circuit (24) being arranged in the housing (9); characterized in that the front body (4) has a through opening (7) and that the coil core (5) extends through the opening (7) of the front body (4) and protrudes from an end face (8) of the front body (4) . Sensor (1) Claim 1 , the housing (3) and the front body (4) being designed in two parts, the housing (3) being connected to the front body (4) via a connecting body (9), the front body (4) being connected by the connecting body (9) is at least partially enclosed and / or fixed in the connecting body (9), in particular is arranged pressed in. Sensor (1) Claim 2 wherein the measuring sensor (1) has a feedback body (10) for returning the magnetic field, the feedback body (10) being formed by the connecting body (9). Measuring sensor (1) according to one of the preceding claims, wherein the housing (3) has a locking device (11), in particular a bayonet lock, wherein the closure device (11) is arranged coaxially to the connecting body (9) and engages around it. wherein the closure device is clamped linearly via an elastic molded element. Measuring tube (2), comprising: - a measuring tube body (12); - A channel (13) for guiding a flowable medium; - At least two measuring electrodes (14) for forming a galvanic contact with the medium and for tapping a measuring voltage induced in the flowing medium; characterized in that the measuring tube body (12) has a receiving device (15) for receiving a measuring sensor (1), in particular the measuring sensor (1) according to one of the preceding claims, and that the receiving device (1) has a blind hole (16) for receiving a coil core (5). The measuring tube (2) Claim 5 wherein the receiving device (15) comprises a recess (17) which in particular has a circular cross-section. The measuring tube (2) Claim 5 and / or 6, wherein the receiving device (15) has a partition (18) which separates part of the receiving device (15) from the channel (13). Measuring tube (2) after one of the Claims 5 to 7th , wherein the measuring electrodes (14) are attached in the receiving device (15). Measuring tube (2) after one of the Claims 5 to 8th , wherein the channel (13) has an inlet-side area (19), an outlet-side area (20) and a measuring area (21) lying between the inlet-side and the outlet-side area (19, 20), the receiving device (15) in the measuring area (21) is arranged, wherein the channel (13) in the inlet-side area (19) has a first cross-section with a first cross-sectional area, the channel (13) in the measuring area (21) has a second cross-section with a second cross-sectional area, the second cross-sectional area being smaller than the first cross-sectional area. The measuring tube (2) Claim 9 , wherein the channel (13) has a longitudinal axis (22), wherein the channel (13) in the measuring region (21) is designed in at least one cross section perpendicular to the longitudinal axis as a segment of a circle, the channel (13) having a longitudinal plane which is defined by a The longitudinal axis (23) of the receiving device (15) is cut perpendicularly, the longitudinal plane dividing the channel (13) into a first and a second section, the first section as a half-cylinder along the inlet-side area (19) and along the measuring area (21) is trained. Measuring tube (2) after one of the Claims 5 to 10 , the measuring tube body (12) made of an insulating material, in particular a plastic and preferably polyetheretherketone (PEEK), polyaryletherketone (PAEK), polyphenyl sulfone (PPSU), Polyethersulfone (PESU), Polysulfone (PSU), Polyarylamide (PARA), glass and / or ceramic is manufactured. Measuring tube (2) after one of the Claims 5 to 11 , wherein the receiving device (15) and the measuring tube body (12) are integrally formed. Magnetic-inductive flow measuring point, comprising: - a measuring sensor (1), in particular the measuring sensor (1) according to one of the Claims 1 to 4th wherein the measuring sensor (1) has a housing (3), a measuring circuit (24), at least two connection contacts (26), a coil (6), a coil core (5) and a front surface (8); - A measuring tube (2), in particular the measuring tube (2) according to one of the Claims 5 to 12th wherein the measuring tube (2) has a channel (13), a measuring tube body (12), at least two measuring electrodes (14) and a receiving device (15); characterized in that the measuring transducer (1) is designed to be detachably connected to the measuring tube (2), and that the measuring transducer (1) is inserted into the receiving device (15) of the measuring tube (2), an end section of the coil core (5) is separated from the channel (13) of the measuring tube (12) by a partition (18), the partition (18) and the measuring tube body (12) of the measuring tube (2) being formed in one piece. Electromagnetic flow measuring point according to Claim 13 , wherein the receiving device (15) is designed to be complementary to the measuring transducer (1) so that the measuring transducer (1) can be inserted into the receiving device (15) in a form-fitting manner. Electromagnetic flow measuring point according to one of the Claims 13 to 14th , wherein the measuring electrodes (14) are electrically connected to the measuring circuit (24) through the connection contacts.

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