WO2022129034A1

WO2022129034A1 - Flow measuring apparatus and method for measuring the volume flow rate of a fluid

Info

Publication number: WO2022129034A1
Application number: PCT/EP2021/085669
Authority: WO
Inventors: Jens Bönninghoff; Björn Schönfeldt; Benedikt Gnacke
Original assignee: Kracht Gmbh
Priority date: 2020-12-15
Filing date: 2021-12-14
Publication date: 2022-06-23
Also published as: DE102020133560A1

Abstract

The invention relates to a flow measuring apparatus for measuring the volume flow rate of a fluid, said apparatus comprising a housing (5a, 5b, 5c) having a measuring chamber (3) which has a fluid inlet (3a) and a fluid outlet (3b). A measuring mechanism (1a, 1b, 2a, 2b, 2c, 6, 7) is located in the measuring chamber (3), by means of which measuring mechanism at least one mechanical sensor component (2a, 2b, 2c), which is rotatably mounted in the measuring chamber (3) and which interacts magnetically with at least one electrical sensor component (6) outside the measuring chamber (3), is made to rotate in accordance with a fluid (4) flowing between the fluid inlet (3a) and the fluid outlet (3b). The at least one mechanical sensor component (2a, 2b, 2c) comprises a shaft (2a, 2b) which can be rotated about an axis of rotation and which comprises a magnetisable material in a shaft region (2c) located in the measuring chamber (3), and the at least one shaft region (2c) comprising magnetisable material interacts with at least two, preferably exactly two, electrical sensor components (6). Each electrical sensor component (6) is formed by a magnetic field sensor (6) and each magnetic field sensor (6) is located outside the measuring chamber (3) at a distance from the shaft region (2c) interacting therewith in a distance direction, and at least one stationary permanent magnet (7) located outside the measuring chamber (3) is associated with the magnetic field sensors (6) and is preferably arranged so as to cover a magnetic field sensor (6) as viewed in the distance direction. A magnetic field can be generated with the at least one permanent magnet (7) at the location of the magnetic field sensors (6), and each of the magnetic field sensors (6), as viewed in the distance direction, covers a partial surface region on the magnetisable material, in particular on the surface of the shaft region (2c) interacting therewith, the distance of which partial surface region from the magnetic field sensor (6) can be varied depending on the rotational position of the shaft (2a, 2b). The invention also relates to a method for measuring the volume flow rate of a fluid (4).

Description

Flow measuring device and method for measuring the volume flow of a fluid

The invention relates to a flow measuring device for measuring the volume flow of a fluid, comprising a housing with a measuring chamber which has a fluid inlet and a fluid outlet, a measuring mechanism being arranged in the measuring chamber with which, depending on a fluid flowing between the fluid inlet and the fluid outlet, at least one the measuring chamber rotatably mounted mechanical sensor component can be set in rotation, which is magnetically interacting with at least one electrical sensor component outside the measuring chamber.

The invention also relates to a method for measuring the volume flow of a fluid with a fluid measuring device comprising a housing with a measuring chamber that has a fluid inlet and a fluid outlet, wherein a measuring mechanism is arranged in the measuring chamber with which, depending on a fluid flowing between the fluid inlet and the fluid outlet, the fluid flows at least one mechanical sensor component which is rotatably mounted in the measuring chamber and which interacts magnetically with at least one electrical sensor component outside the measuring chamber is rotated.

Such flow measuring devices and methods for measuring the volume flow of a fluid are known in the prior art, for example from publication US Pat. No. 9,581,474 B1, DE 10 2006 011 310 A1 and also EP 3 580 527 B1. The measuring mechanisms described in the two first-mentioned publications include at least one rotatable displacement element in the measuring chamber, with the rotation of a displacement element generated by the fluid flow being recorded by measurement. Either a single gear wheel is named as the displacement element or two gear wheels meshing with one another as displacement elements that are in engagement. A respective displacement element, for example a gear wheel, is arranged on a shaft, with the respective shaft being mounted so as to be rotatable about its central shaft axis, for example in roller bearings, in particular cylindrical bearings or ball bearings.

In the version with only one rotatable displacement element, e.g. gear wheel, the fluid to be pumped is enclosed between the displacement element and the measuring chamber wall, e.g. between the spaces between the teeth and the measuring chamber wall. In particular, the spaces between the teeth can be designed asymmetrically in relation to the flow direction in order to achieve a preferred direction of rotation of the displacement element during flow.

In the embodiment with two meshing displacement elements, e.g. meshing gear wheels, an inflow and through between the two engaging displacer elements, a backflow is generated, e.g. between the meshing gears, in particular between the tooth of one of the gears and the space between the teeth of the other, with the difference between the inflow and the backflow forming the effective fluid flow between the inlet and outlet. . The defined volume conveyed during the rotation of the displacement elements per a specific angle of rotation is V = 2 x VRi - VR2, where VR1 is the volume enclosed in a first spatial region at the specific angle of rotation for each of the two displacement elements and VR2 is the is volume enclosed in a second region of space at the given angle of rotation.

In the case of gear wheels, the specific angle of rotation can preferably correspond to the pitch angle, ie 360 degrees/number of teeth of the gear wheel. Within a circumferential section with the angular extension of the pitch angle mentioned, there is then exactly one tooth gap for each displacement element, which defines the volume VRi of the first spatial area with the adjoining measuring chamber walls. In the meshing area of both gears, the volume VR2 is delimited and defined by the space between the teeth of one gear and the tooth of the other gear engaging therein.

Versions can also be provided in which a respective displacement element is designed as a screw spindle, oval wheel, etc. is trained.

These aforementioned designs are preferably characterized in that the flow path between fluid inlet and fluid outlet is interrupted by the displacement elements without rotation of the displacement elements, so that fluid flow through the measuring chamber is only possible with rotation of one or the two displacement elements. With the rotation of the displacement element or elements, the fluid thus flows through the device in portions with a defined fluid volume, e.g. according to the volume V mentioned above, per a specific angle of rotation, e.g. A very precise volume measurement of the fluid flowing through the device is thus possible using the known size of the defined fluid volume mentioned and the number of portions that have flowed per total revolution.

Devices of the type mentioned at the outset are also known, for example from the last-mentioned publication, in which the measuring mechanism has an impeller in the measuring chamber, in particular in the case of so-called impeller meters. Here the impeller by a fluid flow between Fluid input and fluid output of the measuring chamber rotated about its axis of rotation. Such an impeller can also be arranged on a shaft that is rotatably mounted about the axis of rotation.

In such a device, the flow path of the fluid through the measuring chamber is usually not interrupted when the impeller is stationary. Devices of this type are suitable for reliable measurement essentially only in the case of flows above a certain limit volume flow which is suitable for causing the impeller to rotate.

The invention relates to devices and methods of every possible type for forming a measuring mechanism, by means of which at least one mechanical sensor component is set in rotation by the fluid flow, in particular to devices of the types mentioned above, with implementation of the measuring mechanism with displacement elements being preferred to implementation with impellers is.

In the prior art mentioned above, it is known to measure the rotation of a displacement element or impeller in that the mechanical sensor component, which is rotated when the fluid flows through the measuring mechanism in the measuring chamber, has at least one magnet. Such a magnet can be arranged in/on the shaft that carries a displacement element or the impeller or in the displacement element or impeller itself the magnet rotating pole. It is still part of the mass moved with the measuring mechanism.

With an electrical sensor component arranged outside of the measuring chamber, the mechanical sensor component of the prior art, in particular the at least one magnet, interacts magnetically to the extent that the rotating magnetic field on the electrical Sensor component generates a measurement signal, for example depending on the magnetic field strength at the location of the electrical sensor component.

In general, and in particular therefore also valid for the invention, there is a magnetic interaction of the mechanical sensor component with the electrical sensor component, e.g. to the effect that the rotation of at least one element of the mechanical sensor component changes the measurement signal of an element of the electrical sensor component by changing the at the location of the mentioned element of the electrical sensor component present magnetic field.

An electrical sensor component includes, for example, a Hall Effect sensor or a GMR (Giant Magneto Resistance) or TMR (Tunnel Magneto Resistance) or AMR (Anisotropic Magneto Resistive) or EMR (Extraordinary Magneto Resistance) or CMR type sensor (Colossal Magneto Resistive) or GMI (Giant Magnetic Inductance) principle, or as mentioned in the latter publication, simply a coil or is designed as such an element.

In the prior art documents mentioned, the sensor generates an electrical signal which is dependent on the rotational angle position of the magnet or the magnetic field generated by it in relation to the sensor. The signal generated by a magnetic field sensor can be further evaluated in the prior art and also in the invention in order to form information about the volume flow or the volume conveyed. A measured signal can be, for example, a voltage or current signal that constantly changes with the rotation of the measuring mechanism, for example that changes sinusoidally with the rotation. The signal can also be formed by voltage or current pulses, in particular such that a predetermined number of pulses is generated per total revolution of the measuring mechanism and/or at least one element of a mechanical sensor component. It can also be provided to convert between the aforementioned signal forms, ie one of the aforementioned Forming signals from another, e.g. forming pulses from a sine signal. All of the sensors mentioned above, and in principle any sensors that enable magnetic interaction, as well as the procedures mentioned can also be used in the invention.

The problem with this type of magnetic interaction is that the magnet generating the magnetic field to be measured is arranged in the measuring chamber and is therefore in contact with the medium, which is disadvantageous in the case of corrosive media or fluids conveying magnetic particles.

As mentioned, in the prior art mentioned, the magnet is part of the mass to be moved by the measuring mechanism and thus also increases the inertia of the measuring mechanism and thus influences the starting behavior.

Furthermore, the magnetic interaction of the magnet or its rotating magnetic field with the sensor or with metallic elements lying around the measuring chamber generates a braking torque acting on the measuring mechanism, in particular due to eddy currents, which makes precise volume measurement more difficult, or at least must be taken into account as a disturbance variable. This braking effect is greater the further the rotating magnet is radially removed from the axis of rotation.

It is also considered to be disadvantageous that typical series deviations in the production of magnets lead to inhomogeneities in the rotated magnetic field, which makes it difficult to evaluate the generated signal.

Particularly in applications in which high-precision measurement of even very small volumes is important, the devices of the type mentioned at the beginning with magnets arranged on the measuring mechanism for generating a rotating magnetic field are therefore to be regarded as disadvantageous. A further disadvantage can be seen in the fact that the devices of the named prior art with only one magnetic field sensor in the electrical sensor component cannot detect the direction of rotation of the measuring mechanism and thus also not the direction of flow of the fluid through the device.

It is therefore an object of the invention to provide a device and a method with which the effect of braking torques on the measuring mechanism can be avoided or at least reduced, in particular the arrangement of magnets rotated by the fluid flow and generating the magnetic field to be measured on the measuring mechanism avoid. It is also an object of the device according to the invention and the method to be able to identify the flow direction of the fluid through the device.

This object is achieved in a device of the type mentioned at the outset in that the at least one mechanical sensor component comprises a shaft which can be rotated about an axis of rotation, which is driven by the measuring mechanism during its rotation and which comprises a magnetizable material in a shaft region located in the measuring chamber, is preferably formed from a magnetizable material at least in this shaft region, and the shaft region comprising at least one magnetizable material interacts with at least two, preferably exactly two, electrical sensor components, each electrical sensor component being formed by a magnetic field sensor, and each magnetic field sensor to the one interacting with it Shaft region is arranged spaced apart in a distance direction outside of the measuring chamber, and the magnetic field sensors is assigned at least one stationary permanent magnet lying outside of the measuring chamber, preferably the one in the Distance direction considered a respective magnetic field sensor is arranged overlapping, with the at least one permanent magnet at the respective location of the magnetic field sensors, a magnetic field can be generated, each of the magnetic field sensors viewed in the distance direction on the magnetizable Material, in particular on the surface of the shaft area interacting with it, covers a partial surface area of the magnetizable material/the surface, which is variable depending on the rotational position of the shaft at a distance from the respective magnetic field sensor.

The aforesaid spacing direction is the direction in which a respective magnetic field sensor is spaced from the magnetizable material with which it interacts. The covered partial area is the projection of the magnetic field sensor on the magnetizable material viewed in this direction. According to the embodiments described below, the direction of spacing is preferably a direction parallel to the extension of the axis of rotation of the shaft with the interacting shaft area, i.e. axially to the axis of rotation or perpendicular to the extension of the axis of rotation of the shaft with the interacting shaft area, i.e. radially to the axis of rotation.

In the method mentioned at the outset, the object is achieved in that the rotation of at least one shaft used as a mechanical sensor component increases the distance between each of at least two magnetic field sensors used as electrical sensor components, which is penetrated by the magnetic field of at least one permanent magnet assigned to the magnetic field sensors, and one shaft area comprising magnetizable material is changed, and in this case a field strength that changes locally with the rotational position of the at least one shaft with the change in distance, in particular direction-specific field strength components, of the magnetic field acting at the location of the respective magnetic field sensor as a function of the rotational position is measured using each magnetic field sensor.

If an axial direction is referred to in the description of the invention, it is a direction parallel to the extension of the axis of rotation of the at least one shaft, in particular the axes of rotation of possibly two existing shafts at a distance lie parallel to each other. If a radial direction is referred to in the description of the invention, it is at least a direction in a plane perpendicular to the extension of the axis of rotation of the at least one shaft, in particular with a directional vector of this radial direction intersecting the axis of rotation of a shaft referred to.

The at least one shaft driven by the measuring mechanism, the shaft area of which interacts magnetically, can preferably be a shaft that directly carries an element of the measuring mechanism that is rotated by the fluid flow and is in contact with the fluid, e.g. a displacement element, such as a gear wheel or a impeller. In this case, this shaft is driven directly by the measuring mechanism. An indirect drive can also be provided.

In contrast to the prior art mentioned, the measurement of the rotational angle position of the measuring mechanism or at least one shaft or both shafts in the measuring mechanism is not based on the measurement of a magnetic field rotating with the measuring mechanism.

Rather, in the case of the invention, at least one permanent magnet arranged in a stationary manner in the housing outside the measuring chamber generates a magnetic field, in particular with several permanent magnets, a resulting magnetic field is generated at the location of the at least two magnetic field sensors, so that at least to this extent it can be regarded as static or stationary despite the rotation of the measuring mechanism , than that the position of the poles of the generated magnetic field is not changed by the rotation of the measuring mechanism, especially since the poles are in the at least one permanent magnet and this remains in the device even when the measuring mechanism rotates.

Furthermore, the at least one permanent magnet in the invention is not part of the measuring mechanism and therefore does not contribute to its mass to be moved. The measuring mechanism according to the invention can thus be designed with less mass inertia than is the case in the prior art. This can make it easier Start-up of the measuring mechanism can be achieved, especially with small volume flows.

Since the magnetic field to be measured does not rotate with the measuring mechanism, braking torques that can act on the measuring mechanism are significantly reduced compared to the prior art, if not completely eliminated.

The measuring principle and the magnetic interaction in the invention are based on the fact that the magnetic field generated at the location of the at least two magnetic field sensors with the at least one permanent magnet, although it does not rotate with the rotation of the measuring mechanism, does so due to the rotation of the measuring mechanism and the resulting rotation of the at least one magnetizable shaft area is influenced and this influence is measured by the respective magnetic field sensor. With each of the at least two magnetic field sensors, an electrical signal dependent on the influence can be formed, which depends on the rotational angular position of one or the respective interacting wave area, since the influence changes with this angular position of the shaft or the wave area.

According to the invention, an influence can result, for example, from the fact that the magnetizability of the at least one shaft region due to the magnetizable material provided in this region, in particular which of the respective magnetic field sensor with which it interacts, if necessary the at least two or exactly two magnetic field sensors separated by a measuring chamber wall opposite, and due to the change in distance of the magnetizable material resulting from the rotation, in particular the surface of the interacting shaft area to the respective magnetic field sensor, there is a change in the magnetic field generated by the at least one permanent magnet at the location of the magnetic field sensor, in particular due to the fact that the magnetizable material of the Shaft range depending on the rotation angle position more or less penetrates far into the generated magnetic field, preferably because the surface of the interacting wave area, in particular the partial surface area lying on it and covered by the magnetic field sensor (in the projection), is more or less far away from the at least one permanent magnet that generates the magnetic field, i.e. the Distance changes with rotation.

In order to generate magnetizability of the at least one shaft region, it can be provided, for example, that the shaft region, preferably at least its surface, on which the magnetic field sensor projection lies, is made of a magnetizable material, preferably completely, in particular completely over the cross section perpendicular to the axis of rotation . The entire shaft can also be made of a magnetizable material.

However, the invention can also provide for the shaft area, in particular its surface, to be made of a magnetizable material only in some areas. For example, magnetizable material can be arranged at a radial distance from the axis of rotation and viewed in the circumferential direction over a full 360 degrees, i.e. annularly, or only in certain areas on or in non-magnetizable material of the shaft or the shaft area, e.g. in non-magnetizable material of the shaft area or embedded in its surface.

The shaft can thus also be made of a non-magnetizable material, e.g. a ceramic, in particular with the exception of the interacting shaft region, which interacts magnetically with at least one magnetic field sensor. The surface of the shaft can thus also simultaneously form one of the bearing surfaces of a sliding bearing, which supports the respective shaft with an interacting shaft area.

A soft-magnetic material can preferably be selected as the magnetizable material, eg a steel, preferably a magnetizable high-grade steel. In principle, a metal can be used as the soft-magnetic material, e.g solid, bound powder, sheet, crystalline or amorphous ribbon. Ceramic ferritic materials can also be used. The metallic materials preferably include ferromagnetic metals such as iron or cobalt or nickel, preferably in the form of crystalline alloys, amorphous alloys or nanocrystalline alloys. Ceramic materials preferably include ferrites based on metal oxides, for example made of manganese-zinc (MnZn) or nickel-zinc.

A magnetizable material within the meaning of the invention is understood to mean a material that is not itself magnetic, in particular that does not itself generate a magnetic field at least originally in the absence of the magnetic field of the at least one permanent magnet mentioned. If the magnetizable material should have a remanence, this is irrelevant for the measuring principle in the invention, since the material remains constantly magnetized due to the constant presence of the at least one permanent magnet in the device and during rotation the magnetic moments in the material are always with respect to the Permanent magnets generated field remain aligned, so the magnetic moments in the material do not rotate with the rotation of the shaft area. Under the effect of the at least one permanent magnet present, the magnetizable material in the device preferably does not have its own magnetization independent of the at least one permanent magnet, which would be superimposed on the magnetic field of the at least one permanent magnet.

In one possible embodiment, the change in the magnetic field can consist, for example, in that the field strength is changed in terms of its absolute amount at the location of the respective magnetic field sensor, e.g. by angle-dependent bundling or unbundling of the field lines and/or that the direction of the magnetic field is varied depending on the distance. For example, soft-magnetic materials lead to a concentration of the field lines and thus to an increase in the magnetic field passing through them. The influencing of the magnetic field at the location of each of the at least two magnetic field sensors used can be understood, for example, in general in such a way that the magnetic field at the location of the respective magnetic field sensor is distorted as a function of the rotation angle, in particular with a distortion meaning a change in direction of the magnetic field lines, thus the magnetic field vector and/or also a Change in the absolute magnetic field strength can be understood in all or only one directional component.

This further opens up the possibility that different types or sensors with different measuring principles can be used as magnetic field sensors. In particular, it can be provided that a respective magnetic field sensor is selected such that it is suitable for detecting the field strength at the location of the sensor or its sensitive area with regard to at least one predetermined field direction. For example, typical sensors based on the Hall effect or also sensors of the GMR, TMR, AMR, EMR, CMR or GMI measuring principle, which are to be regarded as known in specialist circles, are suitable. The invention thus has the advantage of being able to use a large number of commercially available sensors. Suitable sensors are, for example, of the TMR4018 type from MultiDimension Technology.

A further essential aspect of the invention is the use of at least two, preferably exactly two, magnetic field sensors as respective electrical sensor components, in particular in the covering of partial surface areas of the magnetizable material, in particular the surface of the at least one interacting wave area. Each magnetic field sensor generates an electrical signal depending on the influence on the magnetic field during rotation, in particular depending on the strength of at least one predetermined directional component of the magnetic field at the location of the magnetic field sensor. The surface of the rotatable shaft that faces the respective magnetic field sensor, or the surface of the rotatable shaft that is opposite the magnetic field sensor in the distance direction in the interacting area, is preferably designed in such a way that with respect to each of the magnetic field sensors used, the distance is parallel or perpendicular, in particular depending on the configuration of the invention to the axis of rotation of the shaft, between the partial surface area covered by the respective magnetic field sensor in the distance direction on the surface and the magnetic field sensor with the rotational angular position of the shaft, preferably, with the distance at any point in time or at any possible rotational angle position of the interacting shaft area or the interacting shaft areas at least two of the magnetic field sensors used, in particular all of them used, are different.

This results in different signals being measured for each possible angular position of rotation of the one interacting shaft or the two interacting shafts or the respective shaft regions with the at least two, preferably exactly two, magnetic field sensors, and with continuous rotation of the at least one shaft, the signal curves of the signals of two different magnetic field sensors are different from each other, preferably phase-shifted.

The phase shift results, for example, from the angle by which the magnetic field sensors are spaced apart around the axis of rotation of the shaft, provided the magnetic field sensors mentioned interact with the same shaft range. In general, the phase shift can result from that angle by which the vectorially considered distance directions of two different magnetic field sensors with regard to the same reference position in the respective interacting wave range are spaced apart from one another, in particular if these wave ranges interact with two different wave ranges with regard to their geometric or topological configuration are designed identically around the respective axis of rotation. The direction of rotation of the shaft and thus the direction of the fluid flow in the device according to the invention can be inferred from the signal differences, preferably from the phase shift, in particular its sign. From the angle of rotation already determined using only one of the signals, particularly when using at least one displacement element, preferably two displacement elements, using the defined volume of fluid that can flow through the device per angle unit or per specific angle of rotation, the volume flowed through or the volume flow are closed.

In one possible embodiment, the invention can provide that the interacting shaft region of a shaft is formed by the axial shaft end of the shaft and a respective magnetic field sensor is arranged in the direction of the axial shaft extension at a distance from the magnetizable material of the shaft end interacting with it outside the measuring chamber and in viewed from the axial direction on the magnetizable material of the shaft end, in particular on the axial end face of the shaft end, covers a partial surface area of the entire surface, which is variable depending on the rotational position of the shaft at a distance from the respective magnetic field sensor. In this embodiment of the invention, the initially mentioned distance direction is axial, or parallel to the axis of rotation of the shaft with the interacting shaft area.

In this case, the magnetic field at the location of the interacting magnetic field sensor is influenced by the rotation of the surface of the magnetizable material axially opposite the magnetic field sensor, which can coincide with the partial surface area mentioned on the axial end face of the shaft end, provided that the magnetizable material is arranged in the end face , Preferably the entire end face of the shaft end is made of magnetizable material. A respective shaft always has two shaft ends. The interacting shaft end of the two shaft ends is preferably always the one which is arranged closer to the magnetic field sensor of the two shaft ends, ie in particular whose axial end face faces the magnetic field sensor.

The invention can also provide an alternative design of the interacting shaft area, in which this is formed by an area extending in the circumferential direction around the axis of rotation of the shaft, in which the magnetizable material is unevenly distributed around the axis of rotation. In this case, a respective magnetic field sensor, viewed in the radial direction to the axis of rotation, covers a partial surface area on the magnetizable material of the shaft area, in particular on the radial lateral surface of the shaft area, which is variable depending on the rotational position of the shaft at a distance from the respective magnetic field sensor. In this embodiment, the distance direction mentioned at the outset is therefore radial to the axis of rotation of the shaft with the interacting area.

A respective magnetic field sensor, in particular its center, is preferably radially spaced from the axis of rotation at an axial position relative to the axis of rotation, which also corresponds to the axial position of the interacting shaft region, in particular its center, on the shaft.

The magnetizable material can preferably form a ring eccentric to the axis of rotation on or in the interacting shaft area. This can be formed from a disk made of magnetizable material, which has a bore that is eccentric to the center of the disk and through which the shaft passes. This results in the uneven distribution around the axis of rotation due to the eccentricity of the ring to this, in particular so that the center of the disk rotates around the axis of rotation. The material can also be distributed around the axis of rotation in the manner of a cam.

In this embodiment, two interacting shaft areas can be provided on a single shaft, in particular one of two shafts in the measuring mechanism, which are axially directly next to each other without a distance or are also axially spaced.

The invention can have a measuring mechanism with only one rotating shaft, e.g. in measuring mechanisms with an impeller or also in devices with only one rotating displacement element. The device can also have two engaging displacement elements in the measuring mechanism, in particular two gear wheels or two screw spindles. In this case, the measuring unit of the device has two shafts that rotate when a fluid flows, specifically the respective shaft that carries one of the two displacement elements.

In a possible preferred first embodiment, the invention can provide that the at least two, in particular exactly two, magnetic field sensors interact with the same wave range of a wave, in particular the wave range of a single wave or only the wave range of one of two waves, in particular in such a way that with the Rotation results in a varying influence on the measured values of the magnetic field sensors.

In a device of this first embodiment with two shafts, the other shaft also rotates, but preferably has no interaction with the magnetic field sensors, or during the rotation it always has the same interaction, preferably not causing any measured value change that varies with the rotation. An influencing of the magnetic field sensors as a function of the rotation therefore only occurs with regard to the shaft range of one of the two shafts.

In this first embodiment, it can be provided, for example, that the at least two, in particular exactly two magnetic field sensors with interact in the same shaft area, are arranged in a different radial direction at a distance from the axis of rotation of this shaft outside the measuring chamber and a different partial surface area on the surface of one shaft area is covered by the magnetic field sensors.

The angular spacing between two magnetic field sensors around the axis of rotation of this one shaft viewed in the direction of rotation defines the size of the phase shift of the measurement signals of these two magnetic field sensors relative to one another. Since all magnetic field sensors interact with the same wave range, the measured values of the sensors preferably have the same shape, in particular the same curve apart from a scaling, and preferably an identical curve.

In a possible second embodiment of a device with two shafts/two displacement elements, the invention can also provide that of the at least two magnetic field sensors, a first magnetic field sensor group interacts magnetically with the shaft area of one shaft and a second magnetic field sensor group interacts magnetically with the shaft area of the other shaft. The respective groups each include at least one magnetic field sensor, in particular exactly one each when the total number of all magnetic field sensors is two.

In the second embodiment, exactly two magnetic field sensors can be used in the device. Provision can be made here for the magnetic field sensors to be spaced radially in different radial directions from the axis of rotation of the shaft of the respective interacting shaft region, in particular with the shaft regions of both shafts being of identical design, in particular with regard to the geometry or topology of the end faces or lateral surfaces. The first and also the second embodiment can preferably be provided both in the case of an interaction with magnetizable material in/on an end face area of the shaft end and on/in the lateral surface area of the shaft.

A third embodiment can provide that of the at least two magnetic field sensors, a first magnetic field sensor group, in particular with exactly one magnetic field sensor, with a first shaft range of a shaft, in particular one of two shafts, and a second magnetic field sensor group, in particular with exactly one magnetic field sensor, with a second shaft range of the same wave is interactive.

This design is preferably provided if the respective shaft regions are such in which the magnetizable material is arranged unevenly distributed around the axis of rotation of one shaft, preferably the interaction with the magnetizable material takes place in / on the lateral surface of the shaft in the respective shaft region. The lateral surface is generally understood to be the surface that results with a radial distance, in particular a radial distance that varies here, in the circumferential direction around the axis of rotation.

In a preferred development of the second embodiment, the shaft areas, in particular the shaft ends/the end faces or the lateral surfaces, in their preferably identical geometry/topology, are designed mirror-symmetrically in each case with respect to a mirror plane that includes the axis of rotation. Starting from a reference position in which the two mirror planes are parallel, it follows that due to the radial spacing of the magnetic field sensors in different radial directions, the magnetic field sensors generate signals that are phase-shifted with respect to one another, in particular the signal of a second magnetic field sensor relative to the signal of a first magnetic field sensor by an angle is phase-shifted, which is considered the angular distance of both directional vectors in the direction of rotation of the corresponds to the second wave whose wave range interacts with the second sensor.

Alternatively, it can also be provided that the shaft regions of both shafts are identical in terms of surface geometry/topology, in particular with the aforementioned mirror symmetry, and are oriented relative to one another with an angular difference in their rotational positions, in particular an angular difference in the alignment of their mirror planes in a reference position wherein the magnetic field sensors are radially spaced in the same or opposite radial direction from the axis of rotation of the shaft of the respectively interacting shaft region. In this case, the phase shift results according to the angular difference in the shaft areas and the sign of the phase shift depends on the directions of the spacing of the magnetic field sensors from the shafts/rotational axes.

As a further alternative, the corrugated areas can also have different geometric shapes. In this case, there is a characteristic signal curve of the signals from the magnetic field sensors or also a characteristic signal curve of the difference in signals from two magnetic field sensors.

In order to realize different distances of the magnetizable material in/on the shaft end, in particular on/in the end face of the shaft, to the respective magnetic field sensor with the rotation of the shaft, different configurations of the shaft end can be provided. This is generally achieved by the fact that the axial end face of the shaft end interacting with the magnetic field is not, at least not exclusively, oriented in a plane perpendicular to the axis of rotation, viewed over its entire diameter, in particular if the magnetizable material is in / on or at least adjacent to the Face is arranged, preferably the face of magnetizable material is formed over the entire cross-section of the face. Preferably, an interacting shaft area, in particular the shaft end, e.g two magnetic field sensors result. The term pairing should not be understood as being limited to a number of two measured values if more than two magnetic field sensors are used. In this way, it is possible to conclude from the measured values recorded a particular existing absolute rotational angle position, since the position is unambiguous for every possible pair of measured values.

As exemplified in the previous statements, an interacting shaft area, e.g.

In a preferred embodiment, the invention can provide that with an interacting shaft end, the axial end face of the shaft end is designed as a flat surface overall in a single plane, with the plane not being oriented perpendicularly to the axis of rotation of the shaft, preferably at an angle of 10 to 80 degrees, preferably 30 to 60 degrees, particularly preferably oriented at an angle of 45 degrees to the axis of rotation. This embodiment is particularly preferred because the rotation can generate a sinusoidal signal curve of the signal generated by the respective magnetic field sensor, and its further evaluation with regard to the angular position correlated to the signal is particularly simple. This version in particular is suitable for inferring the absolute rotational angle position. This embodiment also has the mirror symmetry mentioned.

But it can also be provided that the axial end face of the shaft end is designed as a stepped surface with at least two steps in the axial Direction of different heights, preferably with each stage extending around the axis of rotation over an angular range of 360 degrees / n with n = number of stages. As a result, a signal that changes step by step with the change in angle can be generated at each magnetic field sensor. Each step change can preferably be associated with a specific fixed angular amount of rotation.

It can also be provided that the axial end face of the shaft end, in particular when viewed in cross section parallel to the axis of rotation, is curved continuously or in steps in a first direction perpendicular to the axis of rotation and has no curvature in a second direction perpendicular to the first, or that the axial end face, in particular viewed in cross section parallel to the axis of rotation, has at least two, preferably exactly two, planar sub-areas with different angles not equal to 90 degrees to the axis of rotation. The angles of both partial surfaces to the axis of rotation can be the same in amount and differ only in the sign. The design can have the mirror symmetry mentioned, but it does not have to be.

In a preferred development of the invention, it can be provided that the at least one shaft has at least one channel that extends through the entire shaft, preferably in the axial direction, with which the measuring chamber areas at both shaft ends are fluidically connected. This has the advantage, on the one hand, that the design as a hollow shaft saves material and thus moving mass on the measuring mechanism and, on the other hand, that two fluid-filled dead spaces of the device arranged at both ends of the shaft are fluidically connected by the channel, in particular resulting in pressure equalization can be achieved between these dead spaces. This is particularly advantageous if the displacement element driving the shaft or the shaft is designed with sliding bearings, since with this design an axial displacement of the shaft due to pressure differences can then be avoided. The invention can provide, if two engaging, eg meshing displacement elements are provided, that the shafts of both displacement elements are hollow, in particular each with a channel extending completely through the shaft.

Furthermore, it can be provided that in this design of a shaft with a channel, each magnetic field sensor, in particular at least its area sensing the magnetic field, if it interacts with the shaft end, does not, preferably not in some areas, cover the channel cross section. Thus, the axial projection of at least the sensitive area of the respective magnetic field sensor lies completely on the material of the end face of the shaft, which in particular is ring-shaped when viewed in the axial projection.

It is preferably provided that the at least two magnetic field sensors, in particular the exactly two magnetic field sensors that interact with the same shaft region, are arranged at an angular distance of 90 degrees from one another with respect to the axis of rotation of the shaft and at a predetermined, preferably identical, radial distance from the axis of rotation. In this way, signals that are phase-shifted by 90 degrees can be generated by the magnetic field sensors, which is also particularly advantageous if the signal generated is sinusoidal. In general, the magnetic field sensors can have any desired angular spacing other than 0 degrees around the axis of rotation in order to achieve a phase shift with this angular spacing.

In general, it can be provided, in particular if the magnetic field sensors interact with different shaft areas, e.g are arranged at an angle a, for example 90 degrees, to one another in order to produce a phase shift of the signals of a degrees to one another. The respective reference angular position can, for example, at the Location of both wave ranges are that has a fixed, for example, respectively the smallest distance to the magnetic field sensor, insbesondre both wave ranges with respect. Geometry / topology are identical.

In the execution of the interaction with only one wave area or several wave areas on different waves, the arrangement of all magnetic field sensors in the same plane is particularly preferred, preferably a plane perpendicular to the axis of rotation of the at least one shaft.

In an embodiment of the interaction with different shaft regions on the same shaft, the arrangement of the magnetic field sensors is preferably such that they are arranged at the same radial distance and one behind the other in the axial direction.

In order to generate the at least essentially static magnetic field and only locally influenced magnetic field, the invention provides that at least one permanent magnet is used, in particular precisely one permanent magnet.

This can be arranged in such a way that it covers both or all magnetic field sensors at the same time, when viewed in the respective distance direction, e.g. in the direction or perpendicular to the axis of rotation of the at least one shaft, at least in regions, in particular completely, the sensors within the considered in the distance direction Projection of the permanent magnet are, but preferably in the axial direction of spacing of the permanent magnet is not intersected by the axis of rotation of the shaft, so is completely radially outside of this, at least with respect to the axis of rotation of that shaft with the interacting shaft end.

Such a single permanent magnet can preferably be formed such that its poles are spaced apart in the direction of spacing of the magnetic field sensors. Preferably, each of exactly two magnetic field sensors is covered by one of the two poles, as viewed in particular in FIG mentioned distance direction present for the respective embodiment of the invention. What is achieved in particular is that the field line density at the sensor location is particularly high in each case.

The invention can also provide that each magnetic field sensor is assigned its own permanent magnet. In this case, each permanent magnet can preferably cover the assigned magnetic field sensor in the above sense, i.e. each magnetic field sensor is preferably within the axial projection of the permanent magnet assigned to it, particularly viewed in the distance direction mentioned at the beginning and present for the respective embodiment of the invention. Preferably, a geometric center of a respective permanent magnet can be aligned in the distance direction, in particular axially or radially aligned with the sensitive area, in particular the center of the sensitive area, of the associated magnetic field sensor.

In such an embodiment with permanent magnets assigned to each magnetic field sensor, the invention can provide that the different permanent magnets, in particular in the direction of rotation or in the axial direction, are polarized alternately, in particular are polarized axially or radially relative to the axis of rotation, i.e. in particular the poles of each magnet are spaced in the direction of the axis of rotation of the shaft or radially.

Preferably, none of the permanent magnets is crossed by an axis of rotation, which can result in this preferred arrangement in the event of an interaction with a shaft end if the (radial) cross sections of the magnets are preferably smaller than twice the radial spacing of the magnetic field sensors from the (respective) ) axis of rotation.

In particular, with exactly two magnetic field sensors and two associated permanent magnets, the magnets complement each other to form a closed one magnetic circuit, in which the sensors are also located and reinforce each other.

The above-mentioned versions are particularly preferred if all magnetic field sensors interact with the same shaft range, preferably the same shaft end.

At least one of the magnetic field sensors, in particular all magnetic field sensors and the associated permanent magnet can preferably be arranged on opposite sides of a circuit board carrying the magnetic field sensor(s), preferably on opposite sides of a circuit board carrying the magnetic field sensor(s) and the respectively assigned permanent magnet. As a result, the respective magnetic field sensor can be arranged particularly close to one of the poles of the associated permanent magnet, in particular spaced apart only by the thickness of the circuit board. The assigned permanent magnet can be the same for all or several magnetic field sensors, in particular the assigned magnet can also be different for each magnetic field sensor.

The invention can preferably also provide that the at least one interacting wave area and at least one magnetic field sensor, preferably the at least two magnetic field sensors, are arranged on both sides of a non-magnetic and non-magnetizable closure element with which the measuring chamber is closed. This closure element can be tightly connected to the measuring chamber, e.g. by welding, soldering, gluing or screwing, preferably closing an opening through which the measuring chamber can be fitted with at least the shaft, the end of which interacts with one or more magnetic field sensors.

Such a closure element can be a plate or else a pot or an immersion sleeve which is immersed in the fluid in the measuring chamber and in itself accommodates the at least one magnetic field sensor, in particular also the associated permanent magnet.

A preferred embodiment provides that the measuring mechanism has two displacer elements which are in engagement with one another and which can each be rotated about their own axis of rotation, with both axes of rotation being parallel at a distance and with a shaft driven by the displacer element being arranged around the axis of rotation of each of the displacer elements , in particular the shaft carries the displacement element directly, and at least one of the shafts has a magnetically interacting shaft area, e.g. a shaft end.

As mentioned above, the invention can also provide that when two displacement elements are used in the measuring mechanism, each displacement element causes its assigned shaft to rotate and each of these two shafts has a shaft area that interacts magnetically with at least one of at least two magnetic field sensors, preferably with exactly one of exactly two magnetic field sensors interacts.

In this case, the arrangement is preferably chosen such that the magnetic field sensors, as described above, generate signals that are phase-shifted with respect to one another during the rotation of the two synchronously rotating shafts.

These different configurations with only one or two interacting shaft areas make it possible to flexibly consider installation space requirements.

The displacement elements are particularly preferably designed as gear wheels that mesh with one another, but can also be designed as oval wheels or screw spindles. In principle, an embodiment of the device as an impeller meter is also possible, in which the impeller drives one shaft with the magnetically interacting shaft end.

Preferred embodiments are explained below with reference to the figures. FIG. 1 first of all schematically illustrates the working principle of a device according to the invention and the method based on a measuring mechanism with displacement elements.

According to FIG. 1, the two displacement elements are designed as gear wheels 1a and 1b. These are in meshing engagement with one another, are each arranged on a shaft 2a or 2b and are located in a measuring chamber 3, in which the shafts 2a, 2b are also mounted so as to be rotatable about their respective axes of rotation.

The measuring chamber 3 has a fluid inlet 3a and a fluid outlet 3b, which are separated by the displacement elements 1a and 1b.

Between each of the displacement elements 1 a and 1 b as well as the measuring chamber wall 3c radially surrounding it and the measuring chamber walls lying axially above and below the displacement elements (not shown here), several displacement spaces 1c are formed in the circumferential direction around each displacement element, here specifically by each tooth gap 1c. With the direction of flow according to the arrows at the inlet and outlet, the displacement elements 2a, 2b rotate according to the directions of rotation shown there by arrows. The fluid is thus transported from the inlet to the outlet in each displacement chamber with a specific and known volume Vi _c .

Between the meshing displacement elements 1a, 1b, a cavity 1d is also formed between a tooth, for example, of the displacement element 1a and an interdental space, for example, of the displacement element 1b, which also has a specific volume Vid known in the method. In this cavity 1d, which is newly formed with each new intervention, fluid is returned from the outlet to the inlet. With each rotation through an angle, which corresponds to the angular distance between adjacent teeth, a conveyed volume of V = 2xVi _c - Vid results. When there is a pressure difference between the fluid inlet 3a and fluid outlet 3b, the fluid 4 is thus conveyed through the device while the displacement elements 1a, 1b rotate. The flowing fluid 4 sets the measuring mechanism in rotation. The rotation is measured via at least one of the co-rotating shafts 2a or 2b, so that the quantity of the fluid can be determined using the known volume V and the angle covered during the rotation, which is measured.

FIG. 2 shows a device of the type according to the invention in a technically more concrete form in a sectional plane tilted by 90 degrees to FIG. The device has a housing 5, here with a lower housing part 5a and an upper housing part 5b and a housing attachment 5c. The measuring chamber 3 is formed in the housing 5 between the lower part 5a and the upper part 5b, with a fluid inlet 3a and a fluid outlet 3b, as well as the displacement elements 1a, 1b, only one of which can be seen in FIG. The fluid flows through the measuring chamber 3 . The “dry” part of the device is accommodated in the housing attachment, in particular the magnetic field sensors 6 and the at least one permanent magnet 7, which are carried here by a common circuit board 8 on opposite sides of the circuit board 8. This housing attachment 5c thus forms a sensor cover for the device.

FIG. 3 shows a preferred embodiment of the device in yet another section plane of the device. In this embodiment, a magnetic interaction of the shaft area at the shaft end 2c is only provided for one of the two shafts, namely the shaft 2a.

It can be seen here that the shaft 2a on the left here of the displacement element 1a has a free, here upper shaft end 2c, in particular which is arranged here beyond the two shaft bearings. In the device, this shaft end 2c forms the (single here) mechanical sensor component, which interacts magnetically with two electrical sensor components 6 . Each electrical sensor component includes a magnetic field sensor 6, each at the Underside of the circuit board 8 is arranged, which points to the shaft end 2c. On the side of circuit board 8 facing away from shaft end 2c, this device has an associated permanent magnet 7 for each magnetic field sensor 6, which covers the associated magnetic field sensor in the axial direction of the axes of rotation of shafts 2a, 2b.

The direction of the distance, ie the direction of the distance from the magnetic field sensor to the interacting shaft area, here the shaft end 2c, is axial with respect to the axis of rotation 2d.

In the distance between the interacting shaft end 2c and the magnetic field sensors 6, the measuring chamber 3 is closed by a closure element 3c, which is preferably not magnetizable.

FIG. 4 shows an axial view of the arrangement, from which it can be seen that the magnets 7 completely cover the sensors 6 in the projection and that the sensors 6 and magnets 7 are each radially spaced from the axis of rotation 2d of the shaft 2a. The radial distance is greater than the radial cross section of the magnets 7. The sensors 6 and magnets 7 have an angular distance of 90 degrees about the axis of rotation 2d. The effect of this is that the two sensors 6 generate a signal curve that is phase-shifted by 90 degrees with respect to one another.

The magnetic interaction between the one mechanical sensor component (2a, 2c) and the two electrical sensor components 6 is based on the fact that the sensors 6 are each located in the magnetic field of the magnets 7 and measure this magnetic field, i.e. each generate an electrical signal dependent on the magnetic field.

This magnetic field is changed, or distorted or disturbed, by the rotation of the interacting shaft end 2c when the measuring mechanism rotates. In order to bring about this, the shaft end 2c has an axial end face which, in this embodiment, forms a completely flat plane which is at an angle transversely to the axis of rotation 2d, ie is neither perpendicular nor parallel to it. The angle may preferably range from 10 to 45 degrees.

The shaft end 2c or at least the end face comprises a magnetizable material or is made entirely of such a material. The axial projections of the sensors 6 each lie on partial surface areas of the end face whose distance from the respective sensor 6 changes when the shaft 2a rotates. Due to the sloping plane of the end face, the partial surface area under one magnetic field sensor 6 is at a different distance from the sensor 6 than the partial surface area under the other sensor 6. In each angular position, the magnetic field measured by the respective sensor 6 is different compared to the other sensor 6 affected, i.e. both sensors measure different signals, the signals being 90 degrees out of phase due to the angular spacing of the sensors.

The magnetic interaction is based here, for example, on the fact that the magnetizable material of the shaft end 2c concentrates the magnetic field on the sensor 6 more at a smaller distance than at a greater distance. It is thus measured with the sensors 6, the fluctuating concentration of the magnetic field at the sensor location, which is generated by the magnetizable material at the shaft end 2c, in particular in the axial end face during rotation.

The angular position can thus be deduced from the signal level of the signal from each of the sensors 6, the direction of rotation of the shaft 2c and thus the direction of flow of the fluid being able to be deduced from the sign of the phase shift between the signals of both sensors. The angular position can be determined not only relatively but also absolutely, in particular if a different value pair of measured values of both magnetic field sensors results for each possible angular position. In this embodiment, sinusoidal signals are preferably generated in each case with the sensors. Provision can be made to convert at least one of the signals into pulses and then to deduce the volume that has flowed through from a counted number of pulses.

FIG. 5 shows a detail of an alternative embodiment of the device. Here the arrangement of the sensors 6 is identical to the embodiment in FIGS. 2, 3 and 4. What is different, however, is that only one permanent magnet 7 is used. This also covers both sensors 6 and, as in FIG. 4, is valid for each of the two magnets and not crossed by the axis of rotation 2d. All other features are identical to those in FIGS. 2, 3 and 4.

Figures 6 show variant embodiments of the interacting end 2c of the shaft 2a. Figure 6A shows a section of an embodiment that has already been implemented in Figures 2 to 5 with regard to the end face geometry, i.e. the axial end face of the shaft end 2c is completely flat, with the plane being transverse to the axis of rotation 2d, i.e. at an angle not equal to 90 degrees.

In addition, it is visualized that the shaft 2a is hollow and has a channel 2e that extends completely through the shaft and is thus suitable for connecting the areas of the measuring chamber 3 at both ends of the shaft through the shaft in a pressure-equalizing manner. This embodiment can be used in the embodiments of FIGS. 2 to 4 and all other possible embodiments.

FIG. 6B shows a variant of the shaft end in which the end face has exactly two planar partial faces with different angles not equal to 90 degrees to the axis of rotation 2d. FIG. 6C shows a variant in which, compared to FIG. 6B, the radially outer areas of the shaft end 2c merge into the shaft jacket surface in a curved manner.

In FIG. 6D, the end face is continuously curved in a first direction perpendicular to the axis of rotation, which lies here in the plane of the paper, and is designed without curvature in a second direction, here lying perpendicular to the plane of the paper.

In FIG. 6E, the end face is designed as a stepped surface, here with two steps of different heights in the axial direction.

With regard to Figures 6, it should be noted in general that these do not only represent sections, but side views of the shaft, i.e. the profile of the end face perpendicular to the plane of the paper is aligned with the representation shown in all planes parallel to the plane of the paper. All versions of Figures 6 can be used in the versions of Figures 2 to 5, as well as all other possible versions.

FIG. 7 shows an embodiment variant in which both shafts 2a and 2b have respective shaft ends 2c which form magnetically interacting shaft regions. . One of the two magnetic field sensors 6 is assigned to each of the two shaft ends 2c, and each magnetic field sensor 6 is assigned its own permanent magnet 7, which in particular covers the sensor 6 in the axial direction. Compared to FIG. 3, the arrangement of the magnetic field sensors 6 can thus be spatially rectified. It can also be seen that the shaft ends 2c of both shafts 2a, 2b are identical in terms of geometry or topology. According to this representation, there is also a position in which the shaft ends are oriented the same in space or in the device, which can be seen here, for example, from the fact that the highest tip of the shaft end is on the right in the figure. Starting from this position, both shafts rotate in opposite directions. The magnetic field sensor 6 have have different configurations due to the identical shaft orientation and thus generate a phase-shifted signal curve.

FIG. 8 shows a further alternative, in which the displacement elements 1a, 1b in the measuring chamber 3 of the housing 5 are designed as screw spindles which engage with one another. The shaft 2a of the two shafts 2a, 2b has two shaft regions 2d, 2c2, each of which interacts with a different magnetic field sensor 6. In this example, the shaft portions 2d, 2c2 are formed around the axis of rotation 2d in front of the axial end of the shaft 2a.

Each shaft area 2d, 2c2 has magnetizable material that is unevenly distributed around the axis of rotation 2d, e.g. in the form of a respective circular disc made of magnetizable material fastened eccentrically to the axis of rotation 2d on the shaft 2a. Both shaft areas 2d, 2c2, or circular discs can be identical in their respective geometry, but are attached to the shaft 2a offset in rotation angle to one another and therefore point in each rotation angle position at the respective pointing to the magnetic field sensor 6 and covered by this in the radial projection Partial surface area on the lateral surface at a different distance, which leads to a different influence on the magnetic field at the location of the respective magnetic field sensor 6. The distance at the lateral surface of the shaft area 2c2 is smaller than in the shaft area 2d.

Each magnetic field sensor 6 is assigned its own permanent magnet 7 here, in particular one that covers the sensor in the radial direction. The arrangement of circuit board 8, permanent magnets 7 and magnetic field sensors 6 is arranged in an immersion sleeve 3c in the measuring chamber 3 here.

In contrast to the previously shown embodiments, here the magnetic field sensors 6 are not in the axial direction of distance, but in the radial direction of distance relative to the axis of rotation 2d, the interacting one Shaft area 2d, 2c2 opposite, here the circular discs or generally the radial lateral surfaces of the shaft 2a in the two shaft areas 2d and 2c2.

Claims

36

Flow measuring device for measuring the volume flow of a fluid, comprising a housing (5a, 5b, 5c) with a measuring chamber (3) which has a fluid inlet (3a) and a fluid outlet (3b), with a measuring unit (1a , 1b, 2a, 2b, 2c, 6, 7) with which at least one mechanical sensor component ( 2a, 2b, 2c) can be set in rotation, which magnetically interacts with at least one electrical sensor component (6) outside the measuring chamber (3), characterized in that a. the at least one mechanical sensor component (2a, 2b, 2c) comprises a shaft (2a, 2b) which can be rotated about an axis of rotation and which comprises a magnetizable material in a shaft region (2c) located in the measuring chamber (3), and b. the shaft region (2c) comprising at least one magnetizable material interacts with at least two, preferably exactly two, electrical sensor components (6), each electrical sensor component (6) being formed by a magnetic field sensor (6), and c. each magnetic field sensor (6) is arranged at a distance from the wave region (2c) interacting with it in a distance direction outside the measuring chamber (3), and d. at least one stationary permanent magnet (7) located outside of the measuring chamber (3) is assigned to the magnetic field sensors (6) and has a respective magnetic field sensor (6) in the distance direction 37 is arranged overlapping, with the at least one permanent magnet (7) being able to generate a magnetic field at the respective location of the magnetic field sensors (6), e. Each of the magnetic field sensors (6) viewed in the distance direction on the magnetizable material, in particular on the surface of the shaft area (2c) interacting with it, covers a partial surface area which, depending on the rotational position of the shaft (2a, 2b), is at a distance from the respective magnetic field sensor ( 6) is variable. smeasuring device according to claim 1, characterized in that a. at least two, in particular exactly two, magnetic field sensors (6) interacting with the same shaft region (2c) of a shaft (2a), in particular the shaft region (2c) of a single shaft (2a) or the shaft region (2c) of one of two shafts (2a, 2b). and are each arranged in a different radial direction at a distance from the axis of rotation (2d) of this shaft (2a, 2b) outside the measuring chamber (3) and the magnetic field sensors (6) each cover a different partial surface area on the surface of one shaft area (2c). , or b. of the at least two magnetic field sensors (6), a first magnetic field sensor group, in particular with exactly one magnetic field sensor, with the shaft area (2c) of one shaft (2a) and a second magnetic field sensor group, in particular with exactly one magnetic field sensor, with the shaft area (2c) of the other shaft (2b) is interactive, or c. of the at least two magnetic field sensors (6), a first magnetic field sensor group, in particular with precisely one magnetic field sensor, with a first shaft region (2d) of a shaft (2a), in particular one of two shafts (2a, 2b) and a second Magnetic field sensor group, in particular with precisely one magnetic field sensor, interacts with a second shaft region (2c2) of the same shaft (2a). Flow measuring device according to one of the preceding claims, characterized in that the interacting shaft region (2c, 2d, 2c2) of a shaft (2a, 2b) a. is formed by the axial shaft end of the shaft (2a, 2b) and a respective magnetic field sensor (6) is arranged in the direction of the axial shaft extension at a distance from the magnetizable material of the shaft end (2c) interacting with it outside the measuring chamber (3) and in the axial viewed from the direction on which the magnetizable material of the shaft end (2c), in particular on the axial end face of the shaft end (2c), covers a partial surface area which is variable depending on the rotational position of the shaft (2a, 2b) at a distance from the respective magnetic field sensor (6), or b. is formed by an area extending in the circumferential direction around the axis of rotation (2d) of the shaft (2a, 2b), in which the magnetizable material is unevenly distributed around the axis of rotation, in particular the magnetizable material forms a ring eccentric to the axis of rotation, preferably in which the magnetizable material is evenly distributed, and a respective magnetic field sensor, viewed in the radial direction to the axis of rotation, covers a partial surface area on the magnetizable material of the shaft area (2d, 2c2), in particular on the radial lateral surface of the shaft area (2d, 2c2), which, depending on the rotational position of the Shaft (2a, 2b) at a distance from the respective magnetic field sensor (6) is variable. Flow measuring device according to one of the preceding claims, characterized in that the axial end face of the at least one interacting shaft end (2c), in particular all interacting shaft ends (2c) a. is designed as a flat surface overall in a single plane, the plane not being oriented perpendicularly to the axis of rotation (2d) of the shaft (2a, 2b), preferably at an angle of 10 to 80 degrees, particularly preferably at an angle of 45 degrees, to the axis of rotation (2d) is oriented, or b. is designed as a stepped surface with at least two steps of different heights in the axial direction, preferably with each step extending around the axis of rotation (2d) over an angular range of 360 degrees/n with n=number of steps, or c. is curved continuously or in steps in a first direction perpendicular to the axis of rotation (2d) and has no curvature in a second direction perpendicular to the first direction, or d. has at least two, preferably exactly two, planar partial surfaces with different angles not equal to 90 degrees to the axis of rotation (2d). Flow measuring device according to one of the preceding claims, characterized in that the at least one shaft (2a, 2b) has at least one channel (2e) which extends through the entire shaft (2a, 2b), preferably in the axial direction, with the measuring chamber areas on both sides of the Shaft ends are fluidly connected. Flow measuring device according to one of the preceding claims, characterized in that the directional vectors of the directions of the radial spacing of the at least two magnetic field sensors (6) from the axis of rotation (2d) of the shaft (2a, 2b) of the shaft region (2c , 2d, 2c2) are arranged at an angle a, in particular a=90 degrees, to one another. Flow measuring device according to one of the preceding claims, characterized in that each magnetic field sensor (6) is assigned its own permanent magnet (7). Flow measuring device according to Claim 7, characterized in that the different permanent magnets (7) which are adjacent to one another in the direction of rotation about the same axis of rotation (2d) are polarized in alternation, in particular are polarized axially or radially relative to the axis of rotation (2d). Flow measuring device according to one of the preceding claims, characterized in that at least one of the magnetic field sensors (6), in particular all magnetic field sensors (6) and the respective associated permanent magnet (7) are arranged on opposite sides of a circuit board (8) carrying the magnetic field sensor or sensors (6). is/are preferably arranged on opposite sides of a circuit board (8) carrying the magnetic field sensor (6) and the at least one associated permanent magnet (7). Flow measuring device according to one of the preceding claims, characterized in that the at least one interacting shaft area (2c, 2d, 2c2) and at least one magnetic field sensor (6), preferably the at least two magnetic field sensors (6) on both sides of a non-magnetic and non-magnetizable closure element (3c) are arranged, with which the measuring chamber (3) is closed. Flow measuring device according to one of the preceding claims, characterized in that the measuring mechanism has two mutually engaging displacement elements (1a, 1b) which can each be rotated about their own axis of rotation (2d), each displacement element ( 1 a, 1 b) a shaft (2a, 2b) driven by the displacement element (1 a, 1 b) is arranged, in particular the shaft (2a, 2b) 41 carries the displacement element (1a, 1b) directly, and at least one of the shafts (2a, 2b) has a magnetically interacting shaft end (2c). Method for measuring the volume flow of a fluid (4) with a fluid measuring device comprising a housing (5a, 5b, 5c) with a measuring chamber (3) which has a fluid inlet (3a) and a fluid outlet (3b), wherein in the measuring chamber (3 ) a measuring mechanism is arranged, with which at least one mechanical sensor component (2a, 2b, 2c) rotatably mounted in the measuring chamber (3) is set in rotation as a function of a fluid (4) flowing between the fluid inlet (3a) and the fluid outlet (3b), which interacts magnetically with at least one electrical sensor component (6) outside the measuring chamber (3), characterized in that the rotation of at least one shaft (2a, 2b) used as a mechanical sensor component increases the distance between each of at least two magnetic field sensors each used as an electrical sensor component (6), each of the magnetic field associated with at least one of the magnetic field sensors (6) and the respective magnetic field sensor (6) in the distance direction-covering permanent magnets (7) and a shaft area comprising magnetizable material is changed, and with each magnetic field sensor (6) a field strength that changes locally with the rotational position of the at least one shaft (2a, 2b) with the change in distance, in particular direction-specific field strength components , the magnetic field acting at the location of the respective magnetic field sensor (6) is detected by measurement as a function of the rotational position.