WO2024083401A1

WO2024083401A1 - Sensor element and measuring system produced therewith

Info

Publication number: WO2024083401A1
Application number: PCT/EP2023/074654
Authority: WO
Inventors: Anton RIEGER
Original assignee: Endress+Hauser Flowtec Ag
Priority date: 2022-10-18
Filing date: 2023-09-07
Publication date: 2024-04-25
Also published as: DE102022127160A1

Abstract

The invention relates to a sensor element comprising a main part (11) with a main part cavity (11*); a deformation body (12) made of an electrically conductive material, comprising a deformation cavity (12*); a reference body (13) made of an electrically conductive material; and a filling body (14) made of an electrically non-conductive (insulating) material, comprising a filling body cavity (14*). The reference body (13) is partly incorporated into the filling body (14) such that at least one reference body sub-segment (13a) is surrounded by the filling body, and the filling body (14) together with the reference body (13) (incorporated therein) is arranged within the main part cavity (11*) such that the reference body (13) and the main part (11) are mechanically coupled together via the filling body (14) while neverthelss being galvanically separated from each other. Additionally, the deformation body (12) and the main part (11) are mechanically coupled together, thereby forming a sensor cavity (1*) which involves the deformation cavity (12*), such that the main part (11) and the deformation body (12) are connected together, thereby establishing an electrically conductive connection, and the reference body (13) is partly arranged within the deformation body cavity, thereby forming a gap (1') between the deformation body (12) and the reference body (13). The reference body (13) and the deformation body (12) are arranged such that the deformation body inner surface and the reference body surface do not contact each other. Furthermore, the deformation body (12) is designed to carry out a vibrating movement about a static rest position and thereby move relative to the reference body (13) such that the deformation body (12) carries out a vibrating movement which changes the cavity thereof or the gap (1'), therefore changing a capacitance C1 that can be measured between the deformation body and the reference body.

Description

SENSOR ELEMENT AND MEASURING SYSTEM CREATED THEREFROM

The invention relates to a (capacitive) sensor element, in particular a sensor element for (capacitive) detection of pressure fluctuations in a Kärmänn vortex street formed in a flowing fluid and/or a sensor element which is designed to be contacted by a flowing fluid.

In process measurement and automation technology, measuring systems designed as vortex flow meters are often used to measure flow velocities of fluids or (measurement) fluids flowing in pipelines, in particular fast-flowing and/or hot gases (>100°C) and/or fluid flows with a high Reynolds number (Re>10000), or volume or mass flow rates corresponding to a particular flow velocity (u). Examples of such measuring systems are, among others, from US-A 47 16 770, US-A 60 03 384, US-B 69 10 387, US-B 69 38 496,

US-B 97 19 819, US-B 1 08 45 222 or US-B 1 09 48 321 and are also offered by the applicant itself, for example under the trade name "PROWIRL D 200", "PROWIRL F 200", "PROWIRL O 200",

"PROWIRL R 200" (http://www.de.endress.com/en/search?filter.text=prowirl).

The aforementioned measuring systems each have a bluff body which extends into the lumen of the respective pipeline, for example designed as a system component of a heat supply network or a turbine circuit, or into a lumen of a measuring tube inserted in the course of the same pipeline, and against which the fluid flows, in order to generate vortices lined up to form a so-called Kärmän vortex street within the partial volume of the fluid flow flowing immediately downstream of the bluff body. The vortices are generated on the bluff body with a detachment rate (1/fvtx) which is dependent on the flow velocity.

Furthermore, the measuring systems have a (vortex) sensor integrated into the bluff body or connected to it or downstream of it, namely in the area of the Kärmän vortex street in the flow, thus in the lumen of the protruding (vortex) sensor, which serves to detect pressure fluctuations in the Kärmän vortex street formed in the flowing fluid and to convert them into a sensor signal representing the pressure fluctuations, namely to deliver a - for example electrical or capacitive-electrical - signal that is related to a periodic fluctuation prevailing within the fluid as a result of counter-rotating vortices downstream of the bluff body. subjected to pressure or which has a signal frequency (~ f _v tx) corresponding to the detachment rate of the vortices.

For this purpose, the sensor has a (mechanical) sensor assembly formed by means of a substantially membrane-like, substantially disc-shaped thin deformation body made of metal (measuring membrane) and a sensor vane (“paddle”) extending from a substantially planar surface of the deformation body - usually rod-shaped, plate-shaped, wedge-shaped or paddle-shaped - which is designed to detect pressure fluctuations in the Kärmän vortex street, namely to convert them into movements of the deformation body corresponding to the pressure fluctuations. In particular, the deformation body and sensor vane are designed to be excited to forced oscillations around a common static rest position by (alternating) forces acting on the sensor vane that are dependent on the pressure fluctuations, such that the sensor vane carries out pendulum movements that elastically deform the deformation body.

The deformation body has an outer edge segment, usually in the form of a ring, which is designed to be hermetically sealed, for example, in a materially bonded manner, to a holder used to hold the deformation body on a wall of a pipe, such that the deformation body covers or hermetically seals an opening provided in the wall of the pipe and that the surface of the deformation body carrying the sensor flag faces the fluid-carrying lumen of the measuring tube or pipeline, so that the sensor flag protrudes into the same lumen. In addition, the deformation body is shaped such that at least one (deformation body) thickness, measured as a minimum thickness of an inner (deformation body) segment delimited by the outer edge segment, is much smaller than a (deformation body) diameter, measured as a largest diameter of an area delimited by the outer edge segment. In order to achieve the highest possible measurement sensitivity, namely the highest possible sensitivity of the sensor to the pressure fluctuations to be recorded and at the same time the highest possible mechanical natural or resonance frequency, namely above the highest detachment rate to be measured, for the (bending) vibration mode of the sensor assembly excited by the pressure fluctuations (outside resonance), deformation bodies of established measuring systems typically have a diameter-to-thickness ratio that is approximately in the order of 20:1. In order to make such sensors or measuring systems formed with them (despite the relatively high diameter-to-thickness ratio of the respective deformation body due to the measuring principle) also suitable for applications with high operating pressures of more than 10 bar and/or with high operating temperatures of more than 100°C - such as hot steam applications with (measured medium) temperatures of at least temporarily over 200°C and (measured medium) pressures of at least temporarily more than 100 bar or other, relevant pressure equipment directives, such as Directive 97/23/EC, 14 ProdSV, ASUE U-Stamp or 2014/68/EU, the measuring systems shown in US-B 97 19 819 also have a flange-shaped support device with a radial edge section and a cylindrical axial section, such that the deformation body is supported against the support device when a predetermined (increased) pressure is applied thereto, or the measuring systems shown in US-B 1 08 45 222 also have an overload protection device for protecting the deformation body against plastic or irreversible deformation, with a support bracket guided at a lateral distance from the sensor flag and two stops for the sensor flag held by the support bracket. Furthermore, US-B 1 09 48 321 shows measuring systems (suitable for high temperatures or high pressures) in which the deformation body is shaped in such a way that at least one area of the above-mentioned surface bearing the sensor flag, which is adjacent to the sensor flag, is convex. As shown in the above-mentioned US-A 60 03 384, sensor assemblies of the above-mentioned type can also typically have a compensating body, usually in the form of a rod, plate or sleeve, which extends from a surface of the deformation body facing away from the surface bearing the sensor flag and which serves in particular to compensate for forces or moments resulting from movements of the sensor assembly, for example as a result of vibrations in the pipeline, or to avoid undesirable movements of the sensor flag resulting therefrom.

For the purpose of generating the sensor signal, the respective sensor of the aforementioned measuring systems further comprises a corresponding converter element positioned directly on the aforementioned surface of the deformation body facing away from the surface carrying the sensor flag and/or in its vicinity. The converter element is formed by means of a (measuring) capacitor with variable (measuring) capacitance that is mechanically coupled to the respective deformation body and is designed to detect movements of the deformation body or of the compensation body that may be present, for example via a corresponding change in the measuring capacitance, and to modulate an electrical carrier signal.

The sensor assembly or the sensor formed with it is also connected to a converter electronics on a side facing away from the fluid-carrying lumen - typically encapsulated in a pressure- and impact-resistant manner, possibly also hermetically sealed to the outside. Converter electronics in industrial measuring systems usually have a corresponding digital measuring circuit electrically connected to the converter element via connecting cables, possibly with the interposition of electrical barriers and/or galvanic separation points or feedthroughs, for processing the at least one sensor signal generated by the converter element and for generating digital measured values for the respective measured variable to be recorded, namely the flow velocity, the volume flow rate and/or the Mass flow rate. The converter electronics of industrially suitable measuring systems or those established in industrial measurement technology, which are usually housed in a protective housing made of metal and/or impact-resistant plastic, also usually provide external interfaces that conform to an industrial standard, for example DIN IEC 60381-1, for communication with higher-level measuring and/or control systems, for example those formed by means of programmable logic controllers (PLCs). Such an external interface can, for example, be designed as a two-wire connection that can be integrated into a current loop and/or be compatible with established industrial field buses.

One disadvantage of measuring systems of the aforementioned type is that their respective sensors can and do regularly have a comparatively high or comparatively broadband (cross-)sensitivity to interfering vibrations coupled in via the pipeline due to a comparatively high proportion of moving mass (due to the measuring principle) and its unfavorable spatial distribution, accompanied by an unfavorable mechanical connection to the respective pipeline; this is regularly also in such a way that corresponding (broadband) interfering vibrations of the sensor contacted by the measuring medium also have frequencies in the range of the aforementioned detachment rate of the vortex, possibly also with the amplitudes of the aforementioned vibration amplitudes comparable to the movements of the deformation body (corresponding to pressure fluctuations induced by vortexes). A further disadvantage of such measuring systems is the high technical effort required for the construction of the (capacitive) converter element as well as the electrical connection of the converter element to the respective converter electronics, not least the cabling required for this.

Based on this, one object of the invention is to simplify the construction of sensors of the type in question and also to improve them so that they have, on the one hand, high pressure and temperature resistance and, on the other hand, high measurement sensitivity; this is particularly the case with correspondingly high operating pressures or temperatures and/or with, at the same time, low transverse sensitivity to any interference vibrations coupled in via the pipeline.

To achieve the object, the invention consists in a (capacitive) sensor element - for example a sensor element for (capacitive) detecting pressure fluctuations in a Kärmän vortex street formed in a flowing fluid and/or a sensor element which is designed to be contacted by a flowing fluid - which sensor element comprises: • a base body, for example sleeve-shaped and/or monolithic, for example made of an electrically conductive material and/or a metal, with a (base body) cavity having a, for example circular, open first end and a, for example circular, open second end;

• a deformation body, for example paddle-shaped and/or monolithic and/or serving as a sensor flag, made of an electrically conductive material, for example a metal, having an electrical conductivity of more than 10 ⁵ S/m at an (operating) temperature of 20°C, with a (deformation body) cavity having an open first end, for example a circular one, and a closed second end, for example designed as a blind hole;

• a reference body, for example rod-shaped and/or monolithic, made of an electrically conductive material, for example a metal, which has an electrical conductivity of more than 10 ⁵ S/m at an (operating) temperature of 20°C;

• and a, for example sleeve-shaped and/or monolithic, filler made of an electrically non-conductive (insulating) material, for example a glass, a plastic or a ceramic, having an electrical conductivity of less than 10' ⁸ S/m at an (operating) temperature of 20°C, with a (filler) cavity having an, for example circular, open first end and an, for example circular, open second end;

• wherein the reference body is partially embedded in the filler body in such a way that at least a first (reference body) sub-segment of the reference body is enveloped by the filler body, for example by forming a frictional connection and/or a form fit and/or a material bond, for example at least a second (reference body) sub-segment of the reference body adjacent to the same first reference body sub-segment is not enveloped by the filler body, and wherein the filler body is arranged together with the reference body (embedded therein) within the base body cavity in such a way that a (base body) surface of the base body facing the lumen of the base body cavity and a (filler body) surface of the filler body facing the same base body surface contact each other, for example by forming a frictional connection and/or a form fit and/or a material bond, and that the reference body and the base body are mechanically coupled to each other via the filler body, but are nevertheless galvanically separated from each other, for example electrically insulated, for example in such a way that a minimum electrical resistance R1 between reference body and the base body is not less than 10 MQ, for example greater than 50 MQ, at an (operating) temperature of 20°C;

• wherein the deformation body and the base body are mechanically coupled to one another to form a deformation body cavity, for example a sensor cavity involving both the deformation body cavity and a partial area of the base body cavity not occupied by the filler, in such a way that a first (base body) partial segment of the base body, which encompasses the first end of the base body cavity, and a first (deformation body) partial segment of the deformation body, which encompasses the first end of the deformation body cavity, are connected to one another to form an electrically conductive, for example hermetically sealed, connection, for example in a materially bonded and/or positively bonded and/or force-locked manner, and that the reference body, forming an (annular) gap, for example circumferential and/or at least partially hollow-cylindrical and/or non-rotationally symmetrical, between the deformation body and the reference body, is proportionally connected, namely with a sensor cavity adjacent to the first reference body partial segment (which protrudes from the filler or not enclosed by the filler) is arranged within the deformation body cavity;

• wherein the reference body and the deformation body are arranged such that an inner surface (of the deformation body), namely a surface of the deformation body facing (the lumen) of the deformation body cavity, for example a (circular) cylindrical surface, and a surface (of the reference body) facing the inner surface of the deformation body, for example a (circular) cylindrical surface only in sections, do not contact one another, for example in such a way that the reference body and the deformation body are galvanically separated from one another;

• and wherein the deformation body is designed to carry out oscillations around a static rest position, for example forced by (alternating) forces acting on the deformation body, and to be moved relative to the reference body in such a way that the deformation body can carry out or carries out (cantilever) oscillations which deform its (deformation body) cavity or the (ring) gap, thus changing a (sensor) capacitance C1 (of a capacitor formed by the deformation body, the filler body and the reference body) which is measurable between the deformation body and the reference body, for example when the deformation body is in a static rest position, not less than 5 pF and/or not more than 100 pF.

Furthermore, the invention also consists in a measuring system formed by means of such a sensor element and a (measuring) electronics electrically connected to the same sensor element for measuring at least one measured variable, for example a flow parameter or a material parameter, of a medium, for example guided in a pipeline and/or at least temporarily a fluid medium, for example a gas and/or a liquid, having a (measured medium) temperature of more than 100°C and/or acting on the deformation body (of the sensor element) with a pressure difference of more than 10 bar.

Furthermore, the invention also consists in using such a measuring system for measuring a flow parameter - for example a flow velocity and/or a volume flow rate and/or a mass flow rate - of a fluid medium, for example a steam, flowing in a pipeline, for example at a (measured medium) temperature of more than 100°C and/or with a pressure difference of more than 10 bar acting on the deformation body (of the sensor element).

According to a first embodiment of the invention, it is further provided that the deformation body is designed to be contacted by a fluid, for example a liquid and/or a gas or another fluid, which is flowing and/or at least temporarily has a (fluid) temperature of more than 100°C.

According to a second embodiment of the invention, it is further provided that the deformation body is designed to be surrounded by a flowing fluid, for example a liquid and/or a gas, formed, for example, into a Kärmän vortex street, for example to be elastically deformed by (alternating) forces exerted thereon by the fluid.

According to a third embodiment of the invention, it is further provided that the deformation body is designed to convert (alternating) forces acting on it, for example exerted by a fluid flowing around it and/or introduced via first and second (deformation body) outer surfaces, into (cantilever) vibrations deforming the (deformation body) cavity or the (ring) gap.

According to a fourth embodiment of the invention, it is further provided that the deformation body is designed to convert (alternating) forces exerted transversely to the (main) flow direction by a fluid flowing in a (main) flow direction, for example due to pressure fluctuations within a Kärmän vortex street formed in the flowing fluid, into (cantilever) vibrations deforming the (deformation body) cavity or the (ring) gap in a vibration direction pointing, for example, transversely to the (main) flow direction and/or in the direction of a (main) measuring direction of the sensor element. According to a fifth embodiment of the invention, it is further provided that the deformation body is designed to convert (alternating) forces exerted on it in a (main) measuring direction (of the sensor element) into (cantilever) vibrations that deform the (deformation body) cavity or the gap. Developing this embodiment of the invention further, it is further provided that a smallest width of the gap runs parallel to the (main) measuring direction or can be measured parallel to the (main) measuring direction, and/or that a largest width of the gap does not run parallel to the (main) measuring direction or cannot be measured parallel to the (main) measuring direction.

According to a sixth embodiment of the invention, it is further provided that the deformation body has a first (deformation body) outer surface, namely a (first) surface facing away from the deformation body cavity, for example convex and/or partially (circular) cylindrical and/or partially flat, and a second (deformation body) outer surface, namely a (second) surface facing away from the deformation body cavity, but nevertheless opposite the first (deformation body) outer surface, for example convex and/or partially (circular) cylindrical and/or partially flat. Developing this embodiment of the invention, the first and second (deformation body) outer surfaces are further configured to be contacted by a, for example, flowing, fluid, for example a liquid and/or a gas, for example in such a way that (alternating) forces generated by the fluid and causing (cantilever) vibrations deforming the (deformation body) cavity or the (ring) gap are introduced into the deformation body via the first and second (deformation body) outer surfaces.

According to a seventh embodiment of the invention, it is further provided that a (measuring) capacitor with a (sensor) capacitance C1 determined by the gap is formed by means of the deformation body, the filler body and the reference body, for example such that the (measuring) capacitor has a (measuring) sensitivity AC1/AX of more than 1 pF/mm in a (main) measuring direction or is set up to react to a 1 pm (deflection) movement AX of the deformation body in a (main) measuring direction with a change AC1 in the capacitance C1 of more than 1 fF. Developing this embodiment of the invention, it is further provided that the sensor element is designed such that the (measuring) capacitor has a (measuring) sensitivity AC1/AX in a (main) measuring direction, for example more than 1 pF/mm and/or the greatest, such that the (measuring) capacitor is set up to react to a (deflection) movement AX of the deformation body in a (main) measuring direction, for example more than 1 pm, with a change AC1 in the capacitance C1, for example more than 1 fF. The (measuring) capacitor can also advantageously have a transverse sensitivity AC1/AY in a direction deviating from the (main) measuring direction that deviates from the (measuring) sensitivity AC1/AX, for example by not less than 50% of the (measuring) sensitivity AC1/AX, for example such that the Transverse sensitivity AC1/AY is smaller than the (measurement) sensitivity AC1/AX and/or that the (measurement) capacitor is designed to react to a (deflection) movement AY of the deformation body in at least one, for example every, direction deviating from the (main) measurement direction with a change AC1 ' of the capacitance C1 which is smaller than the change AC1 (of the

Capacitance C1) with which the (measuring) capacitor reacts to an equally large (deflection) movement AX of the deforming body in the (main) measuring direction.

According to an eighth embodiment of the invention, it is further provided that the deformation body in the static rest position and the reference body are arranged coaxially at least, for example only, in sections, for example to form a capacitor.

According to a ninth embodiment of the invention, it is further provided that the reference body is at least, for example only, partially (circularly) cylindrical, for example such that a smallest (cylinder) diameter of the second reference body sub-segment is greater than 3 mm and/or that a smallest (cylinder) diameter of the first reference body sub-segment is greater than a smallest (cylinder) diameter of the second reference body sub-segment.

According to a tenth embodiment of the invention, it is further provided that a smallest distance between the deformation body and the reference body is greater than 0.01 mm, for example greater than 0.1 mm, and/or less than 1 mm, for example less than 0.5 mm.

According to an eleventh embodiment of the invention, it is further provided that a maximum distance between the deformation body and the reference body is greater than 0.02 mm, for example greater than 0.2 mm, and/or less than 10 mm, for example less than 5 mm.

According to a twelfth embodiment of the invention, it is further provided that a smallest width of the (annular) gap (1') is greater than 0.01 mm, for example greater than 0.1 mm, and/or smaller than 1 mm, for example smaller than 0.5 mm.

According to a thirteenth embodiment of the invention, it is further provided that a maximum width of the (annular) gap (1 ') is greater than 0.02 mm, for example greater than 0.2 mm, and/or smaller than 1 mm, for example smaller than 0.5 mm.

According to a fourteenth embodiment of the invention, it is further provided that a largest width of the (annular) gap (1 ') is more than 0.05 mm, for example more than 0.1 mm, larger than a smallest width of the (annular) gap (1 '). According to a fifteenth embodiment of the invention, it is further provided that the reference body has a (reference body) mass which is less than 10 g, for example such that a (partial segment) mass of the second reference body partial segment is not more than 5 g and/or not more than 60% of the (reference body) mass.

According to a sixteenth embodiment of the invention, it is further provided that the deformation body has a minimum wall thickness which is not less than 0.2 mm and/or not greater than 1 mm.

According to a seventeenth embodiment of the invention, it is further provided that the deformation body has a (deformation body) mass which is less than 50 g and/or not less than 4 g, for example such that the (deformation body) mass of the deformation body is greater than a (partial segment) mass of the second reference body partial segment.

According to an eighteenth embodiment of the invention, it is further provided that the deformation body has a (deformation body) length which is less than 50 mm and/or greater than 5 mm.

According to a nineteenth embodiment of the invention, it is further provided that the base body has a (base body) length which is greater than 5 mm and/or less than 100 mm, for example not greater than 50 mm.

According to a twentieth embodiment of the invention, it is further provided that the filler has a (filler) length which is greater than 5 mm and/or less than 100 mm, for example not greater than 50 mm.

According to a twenty-first embodiment of the invention, it is further provided that the reference body has a (reference body) length that is greater than 10 mm and/or less than 100 mm, for example such that a (partial segment) length of the second reference body partial segment is less than 50 mm and/or more than 10 mm and/or less than 50% of the (reference body) length and/or more than 10% of the (reference body) length. Developing this embodiment of the invention further, it is further provided that the base body, the reference body or the filler body are designed such that the filler body length is smaller than the base body length and/or that the filler body length is smaller than the reference body length and/or that the base body length is smaller than the reference body length. According to a twenty-second embodiment of the invention, it is further provided that the filler is arranged within the base body cavity in such a way that a partial area of the base body cavity surrounded by the first base body sub-segment (forming the first end of the base body cavity) is not filled by the filler or is not occupied by the filler.

According to a twenty-third embodiment of the invention, it is further provided that the reference body is embedded in the filler body in such a way that a third (reference body) sub-segment of the reference body, which is adjacent to the first reference body sub-segment but is nevertheless distant from the second (reference body) sub-segment, for example a rod-shaped one, is not enclosed by the filler body. Developing this embodiment of the invention further, it is further provided that the third (reference body) sub-segment (of the reference body) is not rotationally symmetrical with respect to an imaginary longitudinal axis of the same (reference body) sub-segment, for example in such a way that the third (reference body) sub-segment has a cross-section in the shape of a circular segment.

According to a twenty-fourth embodiment of the invention, it is further provided that the sensor element - which has a plurality of (natural) vibration modes in which the deformation body and/or the reference body each carry out or can carry out (mechanical) vibrations around a respective static rest position with a respective natural or resonance frequency - has a first vibration mode in which the deformation body, for example having only a single vibration node, can or does carry out (cantilever) vibrations in a first vibration direction corresponding, for example, to a (main) measuring direction (of the sensor element), and a second vibration mode in which the reference body, for example having only a single vibration node, can or does carry out (cantilever) vibrations in the same first vibration direction, and it is further provided that the natural frequency of the first vibration mode, for example more than 1000 Hz and/or less than 10 kHz, is different from the natural frequency, for example more than 1000 Hz and/or less than 10 kHz. the second vibration mode deviates by less than 500 Hz and/or by not more than 10 % of the natural frequency of the second vibration mode.

According to a twenty-fifth embodiment of the invention, it is further provided that the sensor element - which has a plurality of (natural) vibration modes in which the deformation body and/or the reference body each carry out or can carry out (mechanical) vibrations around a respective static rest position with a respective natural or resonance frequency - has a first vibration mode in which the deformation body, for example having only a single vibration node, (cantilever) vibrations in one, for example a (Main) measuring direction (of the sensor element) corresponding to the first vibration direction, a second vibration mode in which the reference body, for example having only a single vibration node, can or does carry out (cantilever) vibrations in the same first vibration direction, and a third vibration mode in which the deformation body, for example having only a single vibration node, can or does carry out (cantilever) vibrations in a second vibration direction pointing perpendicular to the first vibration direction, and a fourth vibration mode in which the reference body, for example having only a single vibration node, can or does carry out (cantilever) vibrations in the same second vibration direction, and it is further provided that the natural frequency of the first vibration mode, for example more than 1000 Hz and/or less than 10 kHz, differs from the natural frequency of the second vibration mode, for example more than 1000 Hz and/or less than 10 kHz, by less than 500 Hz. and/or deviates by no more than 10% of the natural frequency of the second vibration mode, and/or that the natural frequency of the third vibration mode, which is for example more than 1000 Hz and/or less than 10 kHz, deviates from the natural frequency of the fourth vibration mode, which is for example more than 1000 Hz and/or less than 10 kHz, by less than 500 Hz and/or by no more than 10% of the natural frequency of the second vibration mode, and/or that the natural frequency of the third vibration mode, which is for example more than 1000 Hz and/or less than 10 kHz, deviates from the natural frequency of the first vibration mode, which is for example more than 1000 Hz and/or less than 10 kHz, by less than 500 Hz and/or by no more than 10% of the natural frequency of the first vibration mode, and/or that the natural frequency of the third vibration mode, which is for example more than 1000 Hz and/or less than 10 kHz, of the natural frequency of the second vibration mode, which is for example more than 1000 Hz and/or less than 10 kHz, deviates by less than 1000 Hz and/or by no more than 20% of the natural frequency of the second vibration mode, and/or that the natural frequency of the fourth vibration mode, which is for example more than 1000 Hz and/or less than 10 kHz, deviates from the natural frequency of the second vibration mode by less than 500 Hz and/or by no more than 10% of the natural frequency of the second vibration mode, and/or that the natural frequency of the fourth vibration mode, which is for example more than 1000 Hz and/or less than 10 kHz, deviates from the natural frequency of the first vibration mode, which is for example more than 1000 Hz and/or less than 10 kHz, by less than 1000 Hz and/or by not more than 20 % of the natural frequency of the first vibration mode.

According to a twenty-sixth embodiment of the invention, it is further provided that the first (reference body) partial segment (of the reference body) has a (partial segment) length which is greater than 10 mm and/or less than 100 mm.

According to a twenty-seventh embodiment of the invention, it is further provided that the second (reference body) partial segment (of the reference body) has a (partial segment) length which is greater than 10 mm and/or less than 100 mm.

According to a twenty-eighth embodiment of the invention, it is further provided that the second (reference body) sub-segment (of the reference body), for example to increase a mutual (frequency) distance between natural or resonance frequencies of different vibration modes of the sensor element and/or to increase a (measurement) sensitivity AC1/AX of a capacitor C1 formed by means of the deformation body, the filler body and the reference body relative to a transverse sensitivity AC1/AY of the same capacitor C1, is not rotationally symmetrical with respect to an imaginary longitudinal axis of the same (reference body) sub-segment, for example in such a way that the second (reference body) sub-segment has a T-shaped cross-section.

According to a twenty-ninth embodiment of the invention, it is further provided that the base body consists of a material whose (linear) thermal expansion coefficient at an (operating) temperature of 20°C is more than 5-10 ^-6 K' ¹ , for example not less than more than 8-10' ⁶ K' ¹ , and/or less than 25-10' ⁶ K ^-1 , for example not more than 19-10' ⁶ K ^-1 .

According to a thirtieth embodiment of the invention, it is further provided that the reference body consists of a material whose (linear) thermal expansion coefficient at an (operating) temperature of 20°C is less than 11 -10 ⁶ K' ¹ .

According to a thirty-first embodiment of the invention, it is further provided that the filler consists of a material whose (linear) thermal expansion coefficient at an (operating) temperature of 20°C is more than 5-10 ^-6 K' ¹ , for example not less than 8-10 ^-6 K' ¹ , and/or less than 25-10' ⁶ K ^-1 , for example not more than 19-10 ^-6 K ^-1 .

According to a thirty-second embodiment of the invention, it is further provided that the filler consists of a material whose (linear) thermal expansion coefficient at an (operating) temperature of 20°C is more than 5-10 ^-6 K' ¹ , for example not less than 8-10 ^-6 K' ¹ , and/or less than 25-10' ⁶ K' ¹ , for example not more than 19-10 ⁶ K' ¹ , wherein the thermal expansion coefficient (of the material) of the base body is not smaller than the thermal expansion coefficient (of the material) of the reference body, for example such that the thermal expansion coefficient (of the material) of the base body at an (operating) temperature of 20°C is more than 1 -10' ⁶ K ^-1 , for example not less than 5-10' ⁶ K ^-1 , greater than the thermal expansion coefficient (of the material) of the reference body.

According to a thirty-third embodiment of the invention, it is further provided that the filler consists of a material whose (linear) thermal expansion coefficient at an (operating) temperature of 20°C is more than 5-10 ^-6 K' ¹ , for example not less than 8-10 ^-6 K' ¹ , and/or less than 25-10' ⁶ K' ¹ , for example not more than 19-10 ^-6 K' ¹ , whereby the thermal expansion coefficient (of the material) of the base body is not less than the thermal expansion coefficient (of the material) of the filler, for example such that the thermal expansion coefficient (of the material) of the base body at an (operating) temperature of 20°C is more than 1 -10 ^-6 K' ¹ , for example not less than 5-10 ^-6 K' ¹ , greater than the thermal expansion coefficient (of the material) of the packing.

According to a thirty-fourth embodiment of the invention, it is further provided that the filler consists of a material whose (linear) thermal expansion coefficient at an (operating) temperature of 20°C is more than 5-10 ^-6 K' ¹ , for example not less than 8-10 ^-6 K' ¹ , and/or less than 25-10' ⁶ K ^-1 , for example not more than 19-10 ^-6 K ^-1 , wherein the thermal expansion coefficient (of the material) of the reference body is not greater than the thermal expansion coefficient (of the material) of the filler, for example such that the thermal expansion coefficient (of the material) of the reference body is less than 1 -10 ^-6 K ^-1 smaller than the thermal expansion coefficient (of the material) of the filler.

According to a thirty-fifth embodiment of the invention, it is further provided that the base body, for example completely, consists of a metal, for example a (rust-proof) stainless steel (WNo. 1.4404).

According to a thirty-sixth embodiment of the invention, it is further provided that the reference body consists, for example entirely, of a metal, for example a nickel-based alloy (WNo. 2.4475).

According to a thirty-seventh embodiment of the invention, it is further provided that the filling body consists at least partially, for example completely, of a glass, for example a melting gas. According to a thirty-eighth embodiment of the invention, it is further provided that the sensor cavity is hermetically sealed.

According to a thirty-ninth embodiment of the invention, it is further provided that the base body and the filler body are non-positively connected to one another at least at an (operating) temperature of less than 400°C.

According to a fortieth embodiment of the invention, it is further provided that the filler body and the reference body are non-positively connected to one another at least at an (operating) temperature of less than 400°C.

According to a forty-first embodiment of the invention, it is further provided that the sensor cavity is filled with an (inert) gas, for example nitrogen and/or a noble gas. Alternatively, the sensor cavity can also be evacuated, for example.

According to a first development of the invention, the sensor element further comprises: a (first) connecting line electrically connected to the reference body, for example electrically conductively connected thereto.

According to a second development of the invention, the sensor element further comprises: a (second) connecting line electrically connected to the base body, for example electrically conductively connected thereto.

According to a first embodiment of the measuring system of the invention, the sensor element is further configured to react to a pressure difference of 1 bar acting on the deformation body in a (main) measuring direction (of the sensor element) with a change AC1 in the capacitance C1 of not less than 10 fF (femtofarrad) and/or not more than 1 pF (picofarrad).

According to a second embodiment of the measuring system of the invention, it is further provided that by means of the deformation body, for example by means of the deformation body and the base body, a reference potential, for example zero, is provided for at least one (signal) voltage to be processed by means of the measuring electronics or a ground (GND) of the measuring electronics is formed.

A basic idea of the invention is, among other things, to provide a (capacitive) sensor element with a high measuring sensitivity and a high pressure and/or temperature resistance by (only) measuring deformation movements of the deformation body relative to a placed (stationary) reference body directly, namely without a (thin) measuring membrane and a compensating body that follows its vibration movements, and converted (directly) into a change in the (sensor) capacitance or a corresponding (capacitive) electrical measurement signal. The sensor element according to the invention has a mechanical and electrical structure that is comparatively simple and robust and which also advantageously has a very small moving mass (due to the measuring principle). Along with this, the sensor element according to the invention advantageously also has a low cross-sensitivity to external interference vibrations, for example those coupled in via a connected pipeline.

The invention and advantageous embodiments thereof are explained in more detail below using exemplary embodiments which are shown in the figures of the drawing. Identical or equivalent or similarly functioning parts are provided with the same reference symbols in all figures; if this is required for clarity or if it otherwise seems sensible, previously mentioned reference symbols are omitted in subsequent figures. Further advantageous embodiments or further developments, in particular combinations of partial aspects of the invention which were initially only explained individually, also emerge from the figures of the drawing and/or from the claims themselves. In detail:

Fig. 1 shows a perspective side view of an embodiment of a measuring system according to the invention;

Fig. 2 shows schematically in a partially sectioned side view a measuring system according to Fig. 1;

Fig. 3a shows a side view of an embodiment of a sensor element according to the invention or suitable for the measuring system according to Fig. 1 or 2;

Fig. 3b a sensor element according to Fig. 3a or 3b in a sectional side view;

Fig. 4a, 4b in further different side views a sensor element according to Fig. 3a or 3b;

Fig. 5a, 5b a sensor element according to Fig. 3a or 3b in different sectional side views;

Fig. 6a in a perspective side view components (base body, filling body, reference body) of a sensor element according to Fig. 3a; and Fig. 6b shows a perspective side view of a deformation body of a sensor element according to Fig. 3a.

Fig. 1 and 2 show an embodiment of a measuring system MS for measuring at least one flow parameter, which may also vary over time, such as a flow velocity v and/or a volume flow V', of a (measurement) fluid flowing in a pipeline, for example a hot gas or liquid, in particular one that at least temporarily has a temperature of more than 100°C and/or is at least temporarily under high pressure, in particular of more than 10 bar. The pipeline can be designed, for example, as a system component of a heat supply network or a turbine circuit, and the (measurement) fluid or the measured substance can therefore be, for example, steam, in particular saturated steam or superheated steam, or, for example, (cooling) water or a condensate discharged from a steam line. However, the (measuring) fluid can also be, for example, water, a (compressed) natural gas or biogas or gaseous or liquefied hydrogen, thus the pipeline can also be, for example, a component of a natural gas or biogas plant, a pressurized or liquid hydrogen plant or a gas supply network, etc.

The measuring system MS has a sensor element 1 - shown again in various views in Fig. 3a, 3b, 4a, 4b, 5a, 5b, 6a and 6b, enlarged or partially sectioned - which (within the measuring system) can be provided or designed, for example, to detect pressure fluctuations in the (measurement) fluid flowing past the sensor element 1 in a (main) flow direction (of the measuring system MS) and to convert them into a (capacitive) electrical sensor signal s1 corresponding to the same pressure fluctuations. As can be seen from the combination of Fig. 1 and 2, the measuring system further comprises (measurement) electronics 2 - housed, for example, in a pressure- and/or impact-resistant protective housing 20 - which is connected to the sensor element or communicates with the sensor element 1 during operation of the measuring system. The measuring electronics 2 are especially designed to receive and process the sensor signal s1, for example to generate measured values XM representing at least one flow parameter, for example the flow velocity v or the volume flow rate V'. The measured values XM can, for example, be visualized on site and/or transmitted - wired via a connected field bus and/or wirelessly by radio - to an electronic data processing system, such as a programmable logic controller (PLC) and/or a process control station. The protective housing 20 for the measuring electronics 2 can, for example, be made from a metal, such as stainless steel or aluminum, and/or by means of a casting process, such as an investment casting or a pressure die casting process (HPDC); however, it can also be formed, for example, by means of a plastic molded part produced using an injection molding process. The sensor element 1 comprises, as shown in Fig. 3b and 5a respectively or as is readily apparent from a combination of Fig. 3a, 3b, 4a, 4b, 5a, 5b, 6a and 6b, a, in particular sleeve-shaped and/or monolithic, base body 11 with a (base body) cavity 11* having, for example, a circular, open first end and a (in particular, for example, an open second end, a, in particular paddle-shaped and/or monolithic, (serving as a sensor flag) deformation body 12 with a (deformation body) cavity 12* having, in particular, a circular, open first end (12a) and a closed second end, in particular designed as a blind hole, a, in particular rod-shaped and/or monolithic, reference body 13 and a, in particular sleeve-shaped and/or monolithic, filling body 14 with a (filling body) cavity 14* having a, in particular, circular, open first end and a, in particular, circular, open second end. According to a further embodiment of the invention, the deformation body 12 is in particular intended or set up to be contacted by (measurement) fluid during operation of the sensor or the measuring system formed thereby or to be surrounded by (measurement) fluid, in particular in a (main) flow direction of the measuring system, for example also formed into a Kärmän vortex street; this in particular in such a way that the fluid exerts (alternating) forces (F) on the deformation body 12 which (only) elastically deform the deformation body or excite the deformation body 12 to (cantilever) oscillations (AX). The reference body 13 can advantageously be designed to be (circularly) cylindrical at least in sections; for example, this can also be done in such a way that the reference body 13 is (circularly) cylindrical only in sections, as can also be seen from Fig. 6a.

According to a further embodiment of the invention, the base body 11 has a (base body) length L11 that is greater than 5 mm (millimeters) and/or less than 100 mm, in particular not greater than 50 mm, and/or the filler body has a (filler body) length L14 that is greater than 5 mm and/or less than 100 mm, in particular not greater than 50 mm, and/or the reference body 13 has a (reference body) length L13 that is greater than 10 mm and/or less than 100 mm. Alternatively or in addition, the filler body length can advantageously also be smaller than the base body length and/or smaller than the reference body length L13 and/or the base body length can advantageously be smaller than the reference body length. According to a further embodiment of the invention, the reference body has a (reference body) mass that is less than 10 g (grams), and/or the deformation body 12 has a (deformation body) mass that is not greater than 50 g and/or not less than 4 g.

The deformation body 12 and the reference body 13, and possibly also the base body 11, consist of electrically conductive material, in particular material that is highly conductive or has an electrical conductivity of more than 10 ⁵ S/m (Siemens per meter) at an (operating) temperature of 20°C, for example a metal, whereas the filling body 14 consists of electrically poorly or non-conductive (insulating) material, for example glass, plastic or ceramic, in particular one with an electrical conductivity of less than 10' ⁸ S/m at an (operating) temperature of 20°C. The base body 11 and the deformation body 12 can advantageously also be made of the same material, for example. In addition, the base body 11 and the deformation body 12 can also be components of one and the same monolithic molded part, which is cast, for example, or produced by a generative process such as 3D laser melting; the base body 11 and the deformation body 12 can also be designed as individual parts that are initially separate from one another or are only subsequently bonded to one another, for example welded or soldered to one another, and can therefore be made of materials that can be bonded to one another in a correspondingly bonded manner.

According to a further embodiment of the invention, the base body 11 consists of a material whose (linear) thermal expansion coefficient at an (operating) temperature of 20°C is more than 5-10 ^-6 K' ¹ , in particular not less than more than 8-10 ^-6 K' ¹ , and/or less than 25-10' ⁶ K' ¹ , in particular not more than 19- 10 ⁶ K ^-1 , and/or the reference body 13 consists of a material whose (linear) thermal expansion coefficient at an (operating) temperature of 20°C is less than 11 -1 O' ⁶ K' ¹ , and/or the filler body 14 consists of a material whose (linear) thermal expansion coefficient at an (operating) temperature of 20°C is more than 5- 10 ^-6 K' ¹ , in particular not less than 8-10' ⁶ K' ¹ , and/or less than 25-10' ⁶ K ^-1 , in particular not more than 19-10' ⁶ K ^-1 ; this in particular in such a way that the thermal expansion coefficient (of the material) of the base body 11 is not smaller than the thermal expansion coefficient (of the material) of the reference body 13 and/or that the thermal expansion coefficient (of the material) of the base body is not smaller than the thermal expansion coefficient (of the material) of the filler body 14 and/or that the thermal expansion coefficient (of the material) of the reference body is not greater than the thermal expansion coefficient (of the material) of the filler body 14. Advantageously, the materials for the base body ¹¹ , reference body 13 and filler ^body 14 can also be selected such that the thermal expansion coefficient (of the material) of the base body at an (operating) temperature of ²⁰ ° ^C is greater than the Thermal expansion coefficient (of the material) of the reference body 13, and/or that the thermal expansion coefficient (of the material) of the base body at an (operating) temperature of 20°C is greater than the thermal expansion coefficient (of the material) of the filler body 14 by more than 1 -10 ⁶ K ^-1 , in particular by not less than 5 - 10 ^-6 K' ¹ , and/or that the thermal expansion coefficient (of the material) of the reference body 13 is less than 1 -10 ^-6 K ^-1 than the thermal expansion coefficient (of the material) of the filler body 14. According to a further embodiment of the invention, the base body 11 consists at least partially, in particular completely, of a metal, for example a (rust-proof) stainless steel (WNr. 1 .4404), and/or the reference body 13 consists at least partially, in particular completely, of a metal, for example a nickel-based alloy (WNr. 2.4475), and/or the filling body 14 consists at least partially, in particular completely, of a glass, for example a melting gas.

In the sensor element according to the invention, the reference body 13 is partially embedded in the filler body 14 such that at least a first (reference body) sub-segment of the reference body 13 is enclosed by the filler body, in particular by forming a frictional connection and/or a form-fitting connection and/or a material connection, in particular at least a second (reference body) sub-segment of the reference body adjacent to the same first (reference body) sub-segment is not enclosed by the filler body; this is also the case, for example, such that the sensor element is intact at least up to an (operating) temperature of 400°C or that the reference body 13 and the filler body 14 are connected to one another in a frictional connection at least at an (operating) temperature of 400°C or less. According to a further embodiment of the invention, the reference body 13 is designed and embedded in the filling body 14 such that the first (reference body) partial segment 13a (of the reference body) has a (partial segment) length that is greater than 10 mm and/or less than 100 mm, and/or that the second (reference body) partial segment 13b (of the reference body) has a (partial segment) length L13b that is greater than 10 mm and/or less than 100 mm, and/or a (partial segment) mass that is not more than 5 g. Alternatively or in addition, a smallest (cylinder) diameter d13b of the aforementioned second reference body sub-segment 13b can be greater than 3 mm and/or advantageously be selected such that the smallest (cylinder) diameter d13b of the second reference body sub-segment 13b, as is also readily apparent from Fig. 5a or from a combination of Figs. 3b and 5a, is smaller than a smallest (cylinder) diameter dl 3a of the first reference body sub-segment 13a, and/or the reference body can also be designed and embedded in the filler body 14 such that the aforementioned (sub-segment) length of the second reference body sub-segment is less than 50% of the (reference body) length and/or more than 10% of the (reference body) length. Advantageously, the reference body 13 can also be designed and embedded in the filling body 14 in such a way that the aforementioned (deformation body) mass is greater than the aforementioned (partial segment) mass of the second reference body partial segment, and/or that the same (partial segment) mass of the second reference body partial segment is not more than 60% of the (reference body) mass.

According to a further embodiment of the invention, the reference body 13 is further embedded in the filler body in such a way that a third (reference body) sub-segment 13c of the reference body, which is adjacent to the first reference body sub-segment 13a but is nevertheless remote from the second (reference body) sub-segment, for example (also) rod-shaped, is not enveloped by the filler body 14 (in the same way as the previously designated second reference body sub-segment). Advantageously, for example for easy marking of an installation position, the third (reference body) sub-segment 13c can be designed to be non-rotationally symmetrical with respect to an imaginary longitudinal axis of the same (reference body) sub-segment, for example in such a way that the third (reference body) sub-segment 13c, as also indicated in Fig. 4b, has a circular segment-shaped or D-shaped cross-section.

The filler body 14 is arranged together with the reference body 13 (embedded therein) within the base body cavity 11* such that a (base body) surface of the base body facing the lumen of the base body cavity 11* and a (filler body) surface of the filler body facing the same base body surface contact each other (forming a frictional connection and/or a form-fitting connection and/or a material connection) and that the reference body 13 and the base body 11 are mechanically coupled to each other via the filler body 14, but are galvanically separated from each other or electrically insulated from each other; this is done, for example, in such a way that a minimum electrical resistance R1 between reference body 13 and base body 11 at an (operating) temperature of 20°C is not less than 10 MQ, in particular greater than 50 MQ, and/or that the base body 11 and the filler body 14 are connected to one another in a force-fitting manner at least at an (operating) temperature of 400°C or less. According to a further embodiment of the invention, the filler body 14 is also arranged within the base body cavity 11*, not least to protect against mechanical overloading or damage, in such a way that a portion of the base body cavity surrounded by the first base body sub-segment (forming the first end of the base body cavity) is not filled by the filler body 14 or is not occupied by the filler body 14. The base body and the reference body can advantageously be joined by means of primary forming to form the filler body within the base body cavity. The filler body can accordingly be formed, for example, directly within the base body by first placing the reference body within the base body cavity (corresponding to the installation position and location to be achieved) to form an (annular gap-shaped) gap at a distance from the base body, material useful for producing the filler body, for example in the form of granules and/or a melt, is placed in the gap and the filler body is then formed directly within the base body cavity by solidification of initially at least partially liquid, for example partially or melted, (filler body) material in the aforementioned gap.

The deformation body 12 and the base body 11 are also mechanically coupled to one another to form a deformation body cavity 12*, for example a sensor cavity 1* (11*+12*) involving both the deformation body cavity and a portion of the base body cavity not occupied by the filler body 14, in such a way that a first (base body) sub-segment of the base body 11 encompassing the first end of the base body cavity and a first (Deformation body) sub-segment of the deformation body 12 are connected to one another to form an electrically conductive, in particular hermetically sealed, connection (materially and/or positively and/or non-positively) and that the reference body 13, as shown in Fig. 5b or also readily apparent from a combination of Fig. 3b, 5a and 5b, is arranged within the deformation body cavity 12 to form a, in particular circumferential, (annular) gap 1 'between the deformation body 12 and the reference body 13, namely with a free second reference body sub-segment 13b adjacent to its first reference body sub-segment 13a (protruding from the filler body 14 or not enveloped by the filler body 14). According to a further embodiment of the invention, the deformation body 12 and the reference body 13 are further designed and arranged such that the deformation body 12 in the static rest position and the reference body 13 (forming a capacitor) are arranged coaxially at least in sections, for example also in such a way that the deformation body 12 and the reference body 13 are only arranged coaxially in sections. Furthermore, the sensor cavity 1* can advantageously be hermetically sealed and/or the (annular) gap 1' (as a whole) can not be designed to be rotationally symmetrical. Alternatively or in addition, the (annular) gap 1' can also be designed to be hollow-cylindrical at least in sections, for example also in such a way that the (annular) gap 1' is only hollow-cylindrical in sections. In the aforementioned case that the sensor cavity is hermetically sealed, it can also be evacuated (s _r @oHz = s _r = s/so = 1) or filled with an (inert) gas, in particular a noble gas (He, Ar) and/or nitrogen (N).

As shown schematically in Fig. 2, the deformation body 12 and the reference body 13 of the sensor element according to the invention are further arranged such that an inner surface (of the deformation body), namely a surface of the deformation body 12 facing (the lumen) of the deformation body cavity 12*, in particular a (circular) cylindrical surface, and a (reference body) surface of the reference body 13 facing the inner surface of the deformation body, for example only partially (circular) cylindrical, do not contact one another; this is particularly also the case in such a way that the reference body and the deformation body are galvanically separated from one another. According to a further embodiment of the invention, the reference body and the deformation body are arranged in particular such that a smallest distance a1 between the deformation body 12 and the reference body 13 is greater than 0.01 mm, for example also greater than 0.1 mm, and/or smaller than 1 mm, for example also smaller than 0.5 mm, and/or that a largest distance a2 between the deformation body 12 and the reference body 13 is greater than 0.02 mm, for example also greater than 0.2 mm, and/or smaller than 10 mm, for example also smaller than 5 mm. Alternatively or in addition, the reference body 13 and the deformation body 12 can advantageously also be arranged such that a smallest width b1 of the (annular) gap 1' is greater than 0.01 mm, in particular greater than 0.1 mm, and/or smaller than 1 mm, in particular smaller than 0.5 mm, and/or that a largest width b2 of the (annular) gap 1' greater than 0.02 mm, in particular greater than 0.2 mm, and/or smaller than 1 mm, in particular smaller than 0.5 mm, and/or that the above-mentioned largest width b2 of the (ring) gap 1' is more than 0.05 mm, in particular more than 0.1 mm, larger than the above-mentioned smallest width b1 of the (ring) gap 1'. The nominal (measuring) capacity C1 of the sensor element (in static rest position) can also be calculated, for example, based on the following calculation rule

be approximately specified (in advance) or determined (subsequently), whereby the sensor element-specific (dimensionless) coefficient K1 is advantageously chosen to be not less than 0.5 and/or not greater than 3 or, in the case that the sensor element 1 corresponds to an (ideal) cylinder capacitor, to be 2n (K1 = 2n = 2-3.1415...).

According to a further embodiment of the invention, the deformation body 12 further has a first (deformation body) outer surface 12', namely a (first) surface facing away from the deformation body cavity 12*, for example at least partially convex and/or partially (circular) cylindrical and/or partially flat, and a second (deformation body) outer surface 12", namely a (second) surface facing away from the deformation body cavity 12*, but nevertheless opposite the first (deformation body) outer surface, in particular at least partially convex and/or partially (circular) cylindrical and/or partially flat and/or structurally identical to the first (deformation body) outer surface. The first and second (deformation body) outer surfaces are in particular designed to be contacted by the (measuring) fluid, such that (alternating) forces F(t) generated by the fluid, in particular deforming the (deformation body) cavity or the (ring) gap 1' and causing (cantilever) vibrations, are introduced into the deformation body via the first and second (deformation body) outer surfaces. The aforementioned first and second (deformation body) outer surfaces can also advantageously be designed and arranged such that at least one surface normal of the first outer surface is aligned with an opposite surface normal of the second outer surfaces or that surface normals of the first and second outer surfaces run parallel to one another, in particular are coincident. The deformation body 12 can also be designed externally, for example, wedge-shaped or at least partially plate-shaped, as is quite common with such sensors or measuring systems formed therewith; This can also be the case, for example, if the aforementioned first and second outer surfaces are at least partially (plane-)parallel and/or at least partially anti-parallel.

In the sensor element according to the invention, the deformation body 12 is also particularly designed to perform oscillations around a static rest position, for example forced by (alternating) forces acting on the deformation body 12, and thereby to be elastically deformed or moved relative to the reference body 13, such that the deformation body 12 which can or does carry out (cantilever) oscillations AX(t) which deform the (deformation body) cavity 12* or the (annular) gap 1', and thus change the (sensor) capacitance C1 (of a capacitor formed by the deformation body 12, the filler body 14 and the reference body 13) which is measurable between the deformation body 12 and the reference body 13 and amounts to not less than 5 pF and/or not more than 100 pF, in particular when the deformation body is in a static rest position.

The aforementioned (alternating) forces F(t) exerted on the deformation body 12 can, as already indicated, be generated, for example, by the (measurement) fluid contacting or flowing around the deformation body 12 or introduced via the aforementioned first and second (deformation body) outer surfaces. For electrical connection to the aforementioned (measurement) electronics 2, the sensor element 1 according to a further embodiment also has a (first) connection line 11 that is electrically connected to the reference body 13, in particular that is electrically connected thereto. In addition, the sensor element can also have, for example, a further (second) connection line I2 that is also used for electrical connection to the (measurement) electronics, which can advantageously be electrically connected to the base body 11 or electrically connected thereto. Alternatively or in addition, a reference potential, for example zero, for at least one (signal) voltage to be processed by the measuring electronics can be provided by means of the deformation body 12 or by means of the deformation body 12 and the base body 11 or, advantageously, a ground (GND) of the measuring electronics 2 can also be formed.

According to a further embodiment of the invention, the deformation body 12 is furthermore particularly designed to convert (alternating) forces F(t) exerted transversely to the (main) flow direction by the (measuring) fluid flowing in a (main) flow direction (of the measuring system), for example due to pressure fluctuations within a Kärmän vortex street formed in the flowing fluid, into (cantilever) oscillations x(t) deforming the (deformation body) cavity or the (ring) gap 1' in an oscillation direction pointing in particular transversely to the (main) flow direction z and/or in the direction of a (main) detection or measuring direction x of the sensor element 1. The sensor element 1 or the measuring system formed therewith can advantageously be designed or aligned in such a way that a smallest width of the gap 1' runs parallel to the aforementioned (main) measuring direction x or can be measured parallel to the (main) measuring direction x, and/or that a largest width of the gap 1' does not run parallel to the aforementioned (main) measuring direction x or cannot be measured parallel to the (main) measuring direction x. Alternatively or in addition, the sensor element can advantageously be arranged in such a way that the surface normals of the aforementioned first and second (deformation body) outer surfaces are at least partially parallel to the aforementioned (Main) measuring direction x and/or at least partially orthogonal to the aforementioned (main) flow direction z.

According to a further embodiment of the invention, the deformation body 12 further has a (deformation body) thickness D12, measured as a maximum extension (of the deformation body 12) in the direction of the aforementioned (main) detection direction x of the sensor element 1 or as the greatest distance between the aforementioned first and second outer surfaces, which is significantly smaller than a (deformation body) length L12 of the deformation body 12, measured as a (maximum) extension (of the deformation body 12) in the direction (y) of the aforementioned base body length L11 or reference body length L13 or as a minimum distance between the aforementioned open first end of the deformation body cavity 12* and the aforementioned closed second end of the deformation body cavity 12*, plus the local wall thickness of the deformation body 12. In addition, the deformation body 12 a (deformation body) width B12, measured in a direction (z) that is orthogonal to both the direction (x) of the (deformation body) thickness D12 and the direction y) of the (deformation body) length L12, which is greater than the (deformation body) thickness D12. Advantageously, the (deformation body) width B12 can also be selected such that it is smaller than the (deformation body) length L12. Alternatively or additionally, the (deformation body) length L12 is not less than 5 mm and/or not more than 50 mm, and/or the deformation body 12 has a smallest (deformation body) wall thickness w12 that is not less than 0.2 mm and/or not greater than 1 mm. Advantageously, the deformation body 12 can also be designed or arranged such that the aforementioned smallest (deformation body) wall thickness w12 is located within at least one partial segment of the deformation body 12 adjacent to the lumen of the deformation body cavity 12* and comprising one of the aforementioned first and second outer surfaces or is measured in the aforementioned (main) detection direction x of the sensor element 1.

As already indicated, a (measuring) capacitor is formed in the sensor element according to the invention, in particular by means of the deformation body 12, the filler body 14 and the reference body 13; this in particular in such a way that the (measuring) capacitor has a (sensor) capacitance C1 which is also determined by the (annular) gap. According to a further embodiment of the invention, the (measuring) capacitor has a (measuring) sensitivity AC1/AX of more than 1 pF/mm (picofarad per millimeter) in the aforementioned (main) measuring direction, or the (measuring) capacitor is set up to react to a 1 pm (micrometer) (deflection) movement AX of the deformation body 12 in the aforementioned (main) measuring direction with a change AC1 in the capacitance C1 of more than 1 fF (femtofarad). Advantageously, the (measuring) capacitor or the sensor element formed thereby can also be designed such that the capacitor has a maximum (measurement) sensitivity AC1/AX in the aforementioned (main) measuring direction, in particular more than 1 pF/mm; this in particular in such a way that the (measurement) capacitor reacts to a (deflection) movement AX of the deformation body 12 in the aforementioned (main) measuring direction of more than 1 pm and/or less than 5 pm with a change AC1 in the capacitance C1 of more than 1 fF. Alternatively or in addition, the (measurement) capacitor or the sensor element formed thereby can advantageously be further designed such that the (measurement) capacitor has a transverse sensitivity AC1/AY in a direction deviating from the (main) measuring direction which deviates from the (measurement) sensitivity AC1/AX, for example by not less than 50% of the (measurement) sensitivity AC1/AX; this in particular also in such a way that the transverse sensitivity AC1/AY, in particular by not less than 50% of the (measurement) sensitivity AC1/AX, is smaller than the (measurement) sensitivity AC1/AX and/or that the (measurement) capacitor reacts to a (deflection) movement AY of the deformation body 12, in particular more than 1 pm, in at least one, in particular every, direction deviating from the (main) measurement direction with a change AC1 ' of the capacitance C1 which is smaller than the change AC1 (of the capacitance C1) with which the (measurement) capacitor reacts to a (deflection) movement AX of the deformation body 12 in the (main) measurement direction x.

Due to its specific design, the sensor element 1 also has, among other things, a large number of (natural) vibration modes in which the deformation body 12 and/or the reference body 13 each carry out or can carry out mechanical vibrations about a respective static rest position with a respective (mechanical) natural or resonance frequency; this in particular in such a way that the sensor element 1 has a first vibration mode in which the deformation body 12 can carry out or does carry out (cantilever) vibrations in a first vibration direction, for example also corresponding to the aforementioned (main) measuring direction (of the sensor element), and a second vibration mode in which the reference body 13 can carry out or does carry out (cantilever) vibrations in the same first vibration direction. The oscillations according to the first and/or second oscillation modes can in particular also be designed in such a way that they each have a natural frequency of more than 1000 Hz (Hertz) and/or less than 10 kHz (kilohertz) and/or only a single oscillation node. According to a further embodiment of the invention, the deformation body 12 and the reference body 13 are further coordinated with one another in such a way that the natural frequency of the first oscillation mode deviates from the natural frequency of the second oscillation mode by less than 500 Hz and/or by no more than 10% of the natural frequency of the second oscillation mode, not least in order to avoid (interference) oscillations that change the (sensor) capacity in an undesirable manner, for example with a frequency corresponding to one of the first and second natural frequencies, and thus falsify the actual measurement, that the natural frequency of the first oscillation mode deviates from the natural frequency of the second oscillation mode by less than 500 Hz and/or by no more than 10% of the natural frequency of the second oscillation mode. In addition to the above-mentioned first and second oscillation modes, the sensor element can also have a third oscillation mode in which the Deformation body 12, for example, having only a single vibration node, can or does carry out (cantilever) vibrations in a second vibration direction perpendicular to the aforementioned first vibration direction, and the sensor element can also have a fourth vibration mode in which the reference body 13, for example, having only a single vibration node, can or does carry out (cantilever) vibrations in the same second vibration direction. The vibrations according to the third and/or fourth vibration modes can, for example, be designed such that they each have a natural frequency of more than 1000 Hz and/or less than 10 kHz; In order to avoid any interference vibrations that may be caused thereby, this is advantageously also done in such a way that the natural frequency of the third vibration mode deviates from the natural frequency of the fourth vibration mode by less than 500 Hz and/or by no more than 10% of the natural frequency of the second vibration mode and/or that the natural frequency of the third vibration mode deviates from the natural frequency of the first vibration mode by less than 500 Hz and/or by no more than 10% of the natural frequency of the first vibration mode and/or that the natural frequency of the third vibration mode deviates from the natural frequency of the second vibration mode by less than 1000 Hz and/or by no more than 20% of the natural frequency of the second vibration mode and/or that the natural frequency of the fourth vibration mode deviates from the natural frequency of the second

Vibration mode deviates by less than 500 Hz and/or by no more than 10% of the natural frequency of the second vibration mode and/or that the natural frequency of the fourth vibration mode deviates from the natural frequency of the first vibration mode by less than 1000 Hz and/or by no more than 20% of the natural frequency of the first vibration mode. The aforementioned natural frequencies can be specifically adjusted, for example, by appropriately selecting the (geometric) dimensions of reference body 13 and deformation body 12, in particular their respective lengths, the deformation body wall thickness, the deformation body thickness or the reference body diameter, etc., as well as their respective materials or masses. According to a further embodiment of the invention, the second (reference body) sub-segment 13b (of the reference body 13), for example to increase a mutual (frequency) distance of natural or resonance frequencies of different vibration modes of the sensor element and/or to increase the aforementioned (measurement) sensitivity AC1/AX relative to the aforementioned transverse sensitivity AC1/AY, is not rotationally symmetrical with respect to an imaginary longitudinal axis of the same (reference body) sub-segment 13b, for example also in such a way that the second (reference body) sub-segment 13b, as also shown in Fig. 5b or 6a, has a T-shaped cross-section.

According to a further embodiment of the invention, the measuring system MS further comprises a

Pipe 3 which can be inserted into the course of the aforementioned pipeline with a - for example metallic wall 3* of the pipe, which extends from an inlet end 3+ to an outlet end 3# and which is designed to guide the fluid flowing in the pipeline. In the embodiment shown in Fig. 2 and 5a, a flange is provided at the inlet end 3+ and at the outlet end 3# to produce a leak-free flange connection with a corresponding flange on a line segment of the pipeline on the inlet or outlet side. Furthermore, the pipe 3 is essentially straight here, for example as a hollow cylinder with a circular cross-section, such that the pipe 3 has an imaginary straight longitudinal axis L3 imaginarily connecting the inlet end 3+ and the outlet end 3#. The sensor element 1 is inserted from the outside through an opening 3" formed in the wall into the lumen of the tube 3 and is fixed in the area of the same opening - for example, also detachably again - from the outside to the wall 3*, namely in such a way that the deformation body 12 projects into the same lumen. In particular, the sensor element 1 is inserted into the opening 3" in such a way that an essentially membrane-shaped (deformation body) sub-segment 12a of its deformation body 12 covers the opening 3" or hermetically seals it. The opening 3" can also be designed, for example, such that it has an (internal) diameter that is in a range between 10 mm and approximately 50 mm, as is quite common with measuring systems of the type in question. According to a further embodiment of the invention, a holder is also formed in the opening 3" to hold the sensor element 1 or its deformation body 12 on the wall 3*. The sensor element 1 can be fixed to the tube 3, for example, by means of a material-locking connection, in particular by welding or soldering, of the deformation body 12 and the wall 3*; however, it can also be detachably connected to the tube 3, for example by being screwed or screwed on. At least one sealing surface, for example a circumferential or circular ring-like one, can also be formed in the aforementioned holder, which is designed to work together with the deformation body 12 or its aforementioned (deformation body) sub-segment 12a and a sealing element, if provided, for example an annular or annular disk-shaped, to seal the opening 3" accordingly. Last but not least, for the above-described case that the sensor element 1 is inserted into the above-described holder and/or that the deformation body 12 is to be connected in a materially bonded manner to the wall 3* of the tube 3, the deformation body 12 or its (deformation body) sub-segment 12a can advantageously have a further sealing surface, for example an annular ring, formed into it in an edge region (outer or corresponding to the above-described sealing surface of the holder) that matches the sealing surface.

In the embodiment shown in Fig. 2, the measuring system is specifically designed as a vortex flow measuring device with a bluff body 4 arranged in the lumen of the pipe 3 - here upstream of the (built-in) sensor element 1 - which serves to cause a Kärmänsche vortex street in the flowing fluid. Sensor element 1 and bluff body 4 are in this case in the in particular dimensioned and arranged in such a way that the deformation body 12 projects into the lumen 3* of the tube 3 or the fluid guided therein in an area which, during operation of the measuring system, is regularly occupied by a (stationary) Kärmän vortex street, so that the alternating forces acting on the deformation body 12 or the pressure fluctuations detected by the sensor 1 correspond to periodic pressure fluctuations caused by counter-rotating vortices detached from the bluff body 4 at a detachment rate (~1/fvtx) and the sensor signal s1 has a signal frequency (~fvtx) corresponding to the detachment rate of the same vortex. In the embodiment shown here, the measuring system is also designed as a measuring system or a vortex flow measuring device in a compact design, in which the measuring electronics 2 are accommodated in a protective housing 20 which is held on the tube 3 - for example by means of a neck-shaped connecting piece 30. According to a further embodiment of the invention, the sensor element 1 and the tube 3 are also dimensioned such that the above-mentioned deformation body length L12 corresponds to more than half of a caliber DN of the tube 3 or less than 95% of the same caliber DN. The deformation body length L12 can, for example - as is quite common with a comparatively small caliber of less than 50 mm or as can also be seen from Fig. 2 - also be selected such that a free end of the deformation body 12 corresponding to the above-mentioned second end of the deformation body cavity 12 also has only a very small minimum distance from the wall 3* of the tube 3. In the case of tubes with a comparatively large caliber of 50 mm or more, the deformation body length L12 can, as is quite common with measuring systems of the type in question, also be significantly shorter, for example, than half of a caliber DN of the tube 3.

Claims

PATENT CLAIMS

1. (Capacitive) sensor element - in particular a sensor element for (capacitive) detection of pressure fluctuations in a Kärmänschen vortex street formed in a flowing fluid and/or a sensor element which is designed to be contacted by a flowing fluid - which sensor element comprises:

- a base body (11), in particular a sleeve-shaped and/or monolithic base body, in particular made of an electrically conductive material and/or a metal, with a first, in particular circular, open end and a second, in particular circular, open end

(base body) cavity (11*);

- a deformation body (12), in particular paddle-shaped and/or monolithic and/or serving as a sensor flag, made of an electrically conductive material, in particular a material having an electrical conductivity of more than 10 ⁵ S/m at an (operating) temperature of 20°C, in particular a metal, with a (deformation body) cavity (12*) having an, in particular circular, open first end and a closed second end, in particular designed as a blind hole;

- a reference body (13), in particular a rod-shaped and/or monolithic one, made of an electrically conductive material, in particular a metal, in particular one having an electrical conductivity of more than 10 ⁵ S/m at an (operating) temperature of 20°C;

- and a, in particular sleeve-shaped and/or monolithic, filler body (14) made of an electrically non-conductive (insulating) material, in particular a glass, a plastic or a ceramic, in particular one having an electrical conductivity of less than 10 ^-8 S/m at an (operating) temperature of 20°C, with a (filler body) cavity (14*) having an, in particular circular, open first end and an, in particular circular, open second end;

- wherein the reference body (13) is partially embedded in the filling body (14) such that at least a first (reference body) partial segment (13a) of the reference body (13), in particular by forming a frictional connection and/or a form-fitting connection and/or a material connection, is enveloped by the filling body, in particular at least a second (reference body) partial segment (13b) of the reference body (13) adjacent to the same first reference body partial segment is not enveloped by the filling body (14); - and wherein the filling body (14) is arranged together with the reference body (13) (embedded therein) within the base body cavity (11*), such that

- that a (base body) surface of the base body (11) facing the lumen of the base body cavity (11 *) and a (filler body) surface of the filler body (14) facing the same base body surface contact each other, in particular by forming a frictional connection and/or a form connection and/or a material connection

- and that the reference body (13) and the base body (11) are mechanically coupled to one another via a filler body (14), but are nevertheless galvanically separated from one another, in particular electrically insulated, in particular such that a minimum electrical resistance R1 between the reference body (13) and the base body (11) at an (operating) temperature of 20°C is not less than 10 MQ, in particular greater than 50 MQ;

- wherein the deformation body (12) and the base body (11) are mechanically coupled to one another to form a deformation body cavity (12*), in particular a sensor cavity (1*) involving both the deformation body cavity (12*) and a portion of the base body cavity (11*) not occupied by the filler body (14), such that

- that a first (base body) sub-segment of the base body (11) which encompasses the first end of the base body cavity (11*) and a first (deformation body) sub-segment of the deformation body (12) which encompasses the first end of the deformation body cavity (12*) are connected to one another, in particular in a materially bonded and/or positively bonded and/or non-positively bonded manner, to form an electrically conductive, in particular hermetically sealed, connection

- and that the reference body (13) is arranged within the deformation body cavity, forming a (ring) gap (1'), in particular a circumferential and/or at least partially hollow-cylindrical and/or non-rotationally symmetrical, between the deformation body (12) and the reference body (13), namely with a free second reference body sub-segment (13b) adjacent to its first reference body sub-segment (13a) (protruding from the filler body or not covered by the filler body);

- wherein the reference body (13) and the deformation body (12) are arranged such that a (deformation body) inner surface, namely a surface of the deformation body (12) facing (the lumen) of the deformation body cavity, in particular a (circular) cylindrical surface, and a (reference body) surface of the reference body (13) facing the same deformation body inner surface, in particular only partially (circular) cylindrical, do not contact each other, in particular such that the reference body (13) and the deformation body (12) are galvanically separated from each other;

- and wherein the deformation body (12) is designed to be deformed, in particular by

Deformation body (12) acting (alternating) forces forced, vibrations around a static rest position and to be moved relative to the reference body (13) in such a way that the deformation body (12) can or does carry out (cantilever) oscillations which deform its (deformation body) cavity or the (annular) gap (1'), thus changing a (sensor) capacitance C1 (of a capacitor formed by the deformation body, the filler body and the reference body) which is measurable between the deformation body and the reference body and amounts to not less than 5 pF and/or not more than 100 pF, in particular when the deformation body is in the static rest position.

2. Sensor element according to one of the preceding claims, wherein the deformation body is designed to be contacted by a fluid, in particular a liquid and/or a gas or another fluid, in particular a fluid that is flowing and/or at least temporarily has a (fluid) temperature of more than 100°C.

3. Sensor element according to one of the preceding claims, wherein the deformation body is designed to be surrounded by a flowing fluid, in particular a fluid formed into a Kärmän vortex street, in particular a liquid and/or a gas, in particular to be elastically deformed by (alternating) forces exerted thereon by the fluid.

4. Sensor element according to one of the preceding claims, wherein the deformation body is designed to convert (alternating) forces acting thereon, in particular exerted by a fluid flowing around it and/or introduced via first and second (deformation body) outer surfaces, into (cantilever) vibrations deforming the (deformation body) cavity or the (ring) gap.

5. Sensor element according to one of the preceding claims, wherein the deformation body is set up to convert (alternating) forces exerted transversely to the (main) flow direction by a fluid flowing in a (main) flow direction, in particular due to pressure fluctuations within a Kärmän vortex street formed in the flowing fluid, into (cantilever) oscillations deforming the (deformation body) cavity or the (ring) gap in an oscillation direction, in particular transversely to the (main) flow direction and/or in the direction of a (main) measuring direction of the sensor element.

6. Sensor element according to one of the preceding claims, wherein the deformation body has a first (deformation body) outer surface, namely a (first) surface facing away from the deformation body cavity, in particular a convex and/or partially (circular) cylindrical and/or partially flat surface, and a second (deformation body) outer surface, namely a (second) surface facing away from the deformation body cavity, but nevertheless facing the first (deformation body) outer surface opposite, in particular convex and/or partially (circular) cylindrical and/or partially flat, surface.

7. Sensor element according to the preceding claim, wherein the first and second (deformation body) outer surfaces are designed to be contacted by a, in particular flowing, fluid, in particular a liquid and/or a gas, in particular in such a way that (alternating) forces generated by the fluid and causing (cantilever) oscillations deforming the (deformation body) cavity or the (ring) gap are introduced into the deformation body via the first and second (deformation body) outer surfaces.

8. Sensor element according to one of the preceding claims, wherein the deformation body is designed to convert (alternating) forces exerted thereon in a (main) measuring direction (of the sensor element) into (cantilever) vibrations deforming the (deformation body) cavity or the gap.

9. Sensor element according to the preceding claim,

- wherein a smallest width of the gap (1’) runs parallel to the (main) measuring direction or is measurable parallel to the (main) measuring direction; and/or

- wherein a largest width of the gap (1’) does not run parallel to the (main) measuring direction or cannot be measured parallel to the (main) measuring direction.

10. Sensor element according to one of the preceding claims, wherein a (measuring) capacitor with a (sensor) capacitance C1 determined by the gap is formed by means of the deformation body, the filler body and the reference body, in particular such that the (measuring) capacitor has a (measuring) sensitivity AC1/AX of more than 1 pF/mm in a (main) measuring direction or is set up to react to a 1 pm (deflection) movement AX of the deformation body in a (main) measuring direction with a change AC1 in the capacitance C1 of more than 1 fF.

11. Sensor element according to the preceding claim, wherein the (measuring) capacitor has a (measuring) sensitivity AC1/AX in a (main) measuring direction, in particular more than 1 pF/mm and/or greatest, such that the (measuring) capacitor is set up to react to a (deflection) movement AX of the deformation body in a (main) measuring direction, in particular more than 1 pm, with a change AC1 in the capacitance C1, in particular more than 1 fF.

12. Sensor element according to the preceding claim, wherein the (measuring) capacitor has a transverse sensitivity AC1/AY in a direction deviating from the (main) measuring direction which deviates from the (measuring) sensitivity AC1/AX, in particular by not less than 50% of the (measuring) sensitivity AC1/AX, in particular such that the transverse sensitivity AC1/AY is smaller than the (measurement) sensitivity AC1/AX and/or that the (measurement) capacitor is designed to react to a (deflection) movement AY of the deformation body in at least one, in particular every, direction deviating from the (main) measurement direction with a change AC1 ' of the capacitance C1 that is smaller than the change AC1 (of the capacitance C1 ) with which the (measurement) capacitor reacts to an equally large (deflection) movement AX of the deformation body in the (main) measurement direction.

13. Sensor element according to one of the preceding claims,

- wherein the deformation body in the static rest position and the reference body, in particular forming a capacitor, are arranged coaxially at least, in particular only, in sections; and/or

- wherein the reference body is at least, in particular only, partially (circular) cylindrical, in particular such that a smallest (cylinder) diameter of the second reference body sub-segment is greater than 3 mm and/or that a smallest (cylinder) diameter of the first reference body sub-segment is greater than a smallest (cylinder) diameter of the second reference body sub-segment; and/or

- where a minimum distance between the deformation body and the reference body is greater than 0.01 mm, in particular greater than 0.1 mm, and/or less than 1 mm, in particular less than 0.5 mm; and/or

- where a maximum distance between the deformation body and the reference body is greater than 0.02 mm, in particular greater than 0.2 mm, and/or less than 10 mm, in particular less than 5 mm; and/or

- wherein a smallest width of the (annular) gap (1’) is greater than 0.01 mm, in particular greater than 0.1 mm, and/or less than 1 mm, in particular less than 0.5 mm; and/or

- wherein a maximum width of the (annular) gap (1 ’) is greater than 0.02 mm, in particular greater than 0.2 mm, and/or less than 1 mm, in particular less than 0.5 mm; and/or

- wherein a maximum width of the (annular) gap (1’) is more than 0.05 mm, in particular more than 0.1 mm, larger than a minimum width of the (annular) gap (1’); and/or

- wherein the reference body has a (reference body) mass which is less than 10 g, in particular such that a (partial segment) mass of the second reference body partial segment is not more than 5 g and/or not more than 60% of the (reference body) mass; and/or

- wherein the deformation body has a minimum wall thickness which is not less than 0.2 mm and/or not greater than 1 mm; and/or

- wherein the deformation body has a (deformation body) mass which is less than 50 g and/or not less than 4 g, in particular such that the (deformation body) mass of the deformation body is greater than a (partial segment) mass of the second reference body partial segment; and/or

- wherein the deformation body has a (deformation body) length which is less than 50 mm and/or greater than 5 mm.

14. Sensor element according to one of the preceding claims,

- wherein the base body has a (base body) length that is greater than 5 mm and/or less than 100 mm, in particular not greater than 50 mm; and/or

- wherein the filler has a (filler) length that is greater than 5 mm and/or less than 100 mm, in particular not greater than 50 mm; and/or

- wherein the reference body has a (reference body) length which is greater than 10 mm and/or less than 100 mm, in particular such that a (partial segment) length of the second reference body partial segment is less than 50 mm and/or more than 10 mm and/or less than 50% of the (reference body) length and/or more than 10% of the (reference body) length.

15. Sensor element according to the preceding claim,

- where the packing length is smaller than the base body length; and/or

- where the packing length is smaller than the reference body length; and/or

- where the base body length is smaller than the reference body length.

16. Sensor element according to one of the preceding claims, wherein the filling body is arranged within the base body cavity such that a partial region of the base body cavity surrounded by the first base body sub-segment (forming the first end of the base body cavity) is not filled by the filling body or is not occupied by the filling body.

17. Sensor element according to one of the preceding claims, wherein the reference body is embedded in the filler body in such a way that a third (reference body) sub-segment of the reference body which is adjacent to the first reference body sub-segment but is nevertheless remote from the second (reference body) sub-segment, in particular a rod-shaped, is not enclosed by the filler body.

18. Sensor element according to the preceding claim, wherein the third (reference body) sub-segment (of the reference body) is not rotationally symmetrical with respect to an imaginary longitudinal axis of the same (reference body) sub-segment, in particular such that the third (reference body) sub-segment has a cross-section in the shape of a circular segment.

19. Sensor element according to one of the preceding claims, wherein the sensor element has a plurality of (natural) vibration modes in which the deformation body and/or the reference body each execute or can execute (mechanical) vibrations about a respective static rest position with a respective natural or resonance frequency.

20. Sensor element according to the preceding claim,

- wherein the sensor element has a first vibration mode in which the deformation body, in particular only having a single vibration node, (cantilever) vibrations in a first direction corresponding to a (main) measuring direction (of the sensor element). direction of vibration, and a second vibration mode in which the reference body, in particular having only a single vibration node, can or does execute (cantilever) vibrations in the same first vibration direction;

- and wherein the natural frequency of the first vibration mode, in particular more than 1000 Hz and/or less than 10 kHz, deviates from the natural frequency of the second vibration mode, in particular more than 1000 Hz and/or less than 10 kHz, by less than 500 Hz and/or by not more than 10% of the natural frequency of the second vibration mode.

21 . Sensor element according to the preceding claim,

- wherein the sensor element has a third vibration mode in which the deformation body, in particular having only a single vibration node, can or does execute (cantilever) vibrations in a second vibration direction pointing perpendicular to the first vibration direction, and a fourth vibration mode in which the reference body, in particular having only a single vibration node, can or does execute (cantilever) vibrations in the same second vibration direction.

22. Sensor element according to the preceding claim,

- wherein the natural frequency of the third vibration mode, in particular more than 1000 Hz and/or less than 10 kHz, deviates from the natural frequency of the fourth vibration mode, in particular more than 1000 Hz and/or less than 10 kHz, by less than 500 Hz and/or by no more than 10% of the natural frequency of the second vibration mode; and/or

- wherein the natural frequency of the third vibration mode, in particular more than 1000 Hz and/or less than 10 kHz, deviates from the natural frequency of the first vibration mode, in particular more than 1000 Hz and/or less than 10 kHz, by less than 500 Hz and/or by no more than 10% of the natural frequency of the first vibration mode; and/or

- wherein the natural frequency of the third vibration mode, in particular more than 1000 Hz and/or less than 10 kHz, deviates from the natural frequency of the second vibration mode, in particular more than 1000 Hz and/or less than 10 kHz, by less than 1000 Hz and/or by no more than 20% of the natural frequency of the second vibration mode; and/or

- wherein the natural frequency of the fourth vibration mode, in particular more than 1000 Hz and/or less than 10 kHz, deviates from the natural frequency of the second vibration mode by less than 500 Hz and/or by no more than 10% of the natural frequency of the second vibration mode; and/or

- wherein the natural frequency of the fourth vibration mode, in particular more than 1000 Hz and/or less than 10 kHz, deviates from the natural frequency of the first vibration mode, in particular more than 1000 Hz and/or less than 10 kHz, by less than 1000 Hz and/or by not more than 20% of the natural frequency of the first vibration mode.

23. Sensor element according to one of the preceding claims,

- wherein the first (reference body) sub-segment (of the reference body) has a (sub-segment) length that is greater than 10 mm and/or less than 100 mm; and/or

- wherein the second (reference body) sub-segment (of the reference body) has a (sub-segment) length that is greater than 10 mm and/or less than 100 mm; and/or

- wherein the second (reference body) sub-segment (of the reference body), in particular for increasing a mutual (frequency) distance of natural or resonance frequencies of different vibration modes of the sensor element and/or for increasing a (measurement) sensitivity AC1/AX of a capacitor C1 formed by means of the deformation body, the filler body and the reference body relative to a transverse sensitivity AC1/AY of the same capacitor C1, is not rotationally symmetrical with respect to an imaginary longitudinal axis of the same (reference body) sub-segment, in particular such that the second (reference body) sub-segment has a T-shaped cross-section.

24. Sensor element according to one of the preceding claims,

- wherein the base body consists of a material whose (linear) thermal expansion coefficient at an (operating) temperature of 20°C is more than 5-10 ^-6 K' ¹ , in particular not less than more than 8-10 ^-6 K' ¹ , and/or less than 25-10' ⁶ K' ¹ , in particular not more than 19-10' ⁶ K'¹; and/or

- wherein the reference body consists of a material whose (linear) thermal expansion coefficient at an (operating) temperature of 20°C is less than 11 -10 ^-6 K'¹; and/or

- wherein the filler consists of a material whose (linear) thermal expansion coefficient at an (operating) temperature of 20°C is more than 5-10 ^-6 K' ¹ , in particular not less than 8-10 ^-6 K' ¹ , and/or less than 25-10' ⁶ K' ¹ , in particular not more than 19-10 ^-6 K' ¹ .

25. Sensor element according to the preceding claim,

- wherein the thermal expansion coefficient (of the material) of the base body is not less than the thermal expansion coefficient (of the material) of the reference body, in particular such that the thermal expansion coefficient (of the material) of the base body at an (operating) temperature of 20°C is greater than the thermal expansion coefficient (of the material) of the reference body by more than 1 -10 ^-6 K' ¹ , in particular by not less than 5-10 ^-6 K'¹; and/or

- wherein the thermal expansion coefficient (of the material) of the base body is not less than the thermal expansion coefficient (of the material) of the filler, in particular such that the thermal expansion coefficient (of the material) of the base body at an (operating) temperature of 20°C is greater than the thermal expansion coefficient (of the material) of the filler by more than 1 -10' ⁶ K ^-1 , in particular by not less than 5-10' ⁶ K ^-1 ; and/or - whereby the coefficient of thermal expansion (of the material) of the reference body is not greater than the coefficient of thermal expansion (of the material) of the filling body, in particular such that the coefficient of thermal expansion (of the material) of the reference body is less than 1 -1 O' ⁶ K' ¹ smaller than the coefficient of thermal expansion (of the material) of the filling body

26. Sensor element according to one of the preceding claims,

- the base body, in particular completely, consists of a metal, in particular a (rust-proof) stainless steel (WNr. 1.4404); and/or

- the reference body, in particular completely, consists of a metal, in particular a nickel-based alloy (WNr. 2.4475); and/or

- wherein the filling body consists at least partially, in particular completely, of a glass, in particular a melting gas; and/or

- wherein the sensor cavity is hermetically sealed; and/or

- wherein the base body and the filler body are connected to one another in a force-locking manner at least at an (operating) temperature of less than 400°C, and/or

- whereby the filler body and the reference body are force-fitted together at least at an (operating) temperature of less than 400°C.

27. Sensor element according to one of the preceding claims, wherein the sensor cavity is filled with an (inert) gas, in particular nitrogen and/or a noble gas.

28. Sensor element according to one of claims 1 to 26, wherein the sensor cavity is evacuated.

29. Sensor element according to one of the preceding claims, further comprising: a (first) connecting line electrically connected to the reference body, in particular electrically conductively connected thereto.

30. Sensor element according to one of the preceding claims, further comprising: a (second) connecting line electrically connected to the base body, in particular electrically conductively connected thereto.

31. Measuring system for measuring at least one measured variable, in particular a flow parameter or a material parameter, of a fluid measuring material, in particular a gas and/or a liquid, which is guided in a pipeline and/or at least temporarily has a (measured material) temperature of more than 100°C and/or acts on the deformation body (of the sensor element) with a pressure difference of more than 10 bar, comprising: a sensor element according to one of the preceding claims and (measurement) electronics electrically connected thereto.

32. Measuring system according to the previous claim,

- wherein the sensor element is designed to react to a pressure difference of 1 bar acting on the deformation body in a (main) measuring direction (of the sensor element) with a change AC1 in the capacitance C1 of not less than 10 fF and/or not more than 1 pF; and/or

- wherein by means of the deformation body, in particular by means of the deformation body and the base body, a reference potential, in particular zero, is provided for at least one (signal) voltage to be processed by means of the measuring electronics or a ground (GND) of the measuring electronics is formed.

33. Use of a measuring system according to one of the preceding claims for measuring a flow parameter - in particular a flow velocity and/or a volume flow rate and/or a mass flow rate - of a fluid measuring medium, in particular a steam, flowing in a pipeline, in particular a (measured medium) temperature of more than 100°C and/or acting on the deformation body (of the sensor element) with a pressure difference of more than 10 bar.