WO2006058863A1 - Device for determining and/or monitoring the flow rate of a measured medium - Google Patents

Device for determining and/or monitoring the flow rate of a measured medium Download PDF

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Publication number
WO2006058863A1
WO2006058863A1 PCT/EP2005/056225 EP2005056225W WO2006058863A1 WO 2006058863 A1 WO2006058863 A1 WO 2006058863A1 EP 2005056225 W EP2005056225 W EP 2005056225W WO 2006058863 A1 WO2006058863 A1 WO 2006058863A1
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Prior art keywords
temperature
temperature sensor
temperature sensors
flow
measuring medium
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PCT/EP2005/056225
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German (de)
French (fr)
Inventor
Oliver Popp
Mohammed Khan
Chris Gimson
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Endress+Hauser Flowtec Ag
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Publication of WO2006058863A1 publication Critical patent/WO2006058863A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
    • G01F1/6842—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow with means for influencing the fluid flow
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F5/00—Measuring a proportion of the volume flow

Definitions

  • the invention relates to a thermal or calorimetric device for determining and / or monitoring the flow of a flowing through a pipe or through a measuring tube measuring medium with two temperature sensors and a control / evaluation unit.
  • the measuring medium is a flowable medium, in particular a liquid, a vaporous or a gaseous medium.
  • thermal flow meters usually use two as possible identically designed temperature sensors.
  • both temperature sensors are usually installed in a measuring tube in which the flow of a measuring medium is measured.
  • One of the two temperature sensors is a so-called passive temperature sensor; it detects the current temperature of the medium to be measured.
  • the second temperature sensor is a so-called active temperature sensor, which is heated by a heating unit.
  • the heating unit is either an additional resistance heater, or the temperature sensor itself is a resistance element, e.g. a RTD (Resistance Temperature Device) sensor, which is heated by conversion of an electrical power (e.g., by increased sense current).
  • RTD Resistance Temperature Device
  • Corresponding temperature sensors are offered and sold, for example, by Honeywell.
  • Temperature sensor so heated that sets a fixed temperature difference between the two temperature sensors.
  • it has also become known to feed in a regulating / control unit a time-constant heating power.
  • the dissipation of the heat from the heated temperature sensor via heat conduction, heat radiation and optionally also free convection takes place within the measuring medium. If the medium to be measured is in motion, an additional cooling of the heated temperature sensor is added by the colder medium flowing past. Due to the measuring medium flowing past, heat transport due to forced convection also occurs here. Consequently, in order to maintain the fixed temperature difference between the two temperature sensors, a higher heating power is required for the heated temperature sensor. In the case of the supply of a time-constant heating power, the temperature difference between the two temperature sensors decreases as a result of the flow of the measuring medium.
  • thermo-physical properties of the medium itself and the pressure prevailing in the medium If the corresponding flow-dependent characteristic curves have been created for these parameters or if the corresponding parameters are known in the functional equations, the mass flow rate of the measuring medium can be determined exactly.
  • Thermal measuring instruments based on the principle described above are offered and sold by Endress + Hauser under the name 't-mass'.
  • the two temperature sensors are pin-shaped or straight and arranged parallel to each other.
  • the arrangement of the temperature sensors with respect to the flow direction of the measuring medium and the measuring medium itself may have a relatively large influence on the measurement result.
  • the installation position of the flowmeter in the pipeline is usually chosen so that it is ensured that the measuring medium with the temperature sensors in continuous thermal contact.
  • Possible installation positions are the lateral installation position with vertically arranged pipelines, or the temperature sensors are located at a horizontally arranged pipeline in the upper, in the lower area or in the lateral area of the pipeline. In the latter case, the positioning in the lateral region of the pipeline is advantageous insofar as in this type of assembly neither deposits after air cushion can adversely affect the function of the meter.
  • the two temperature sensors are positioned behind one another in the direction of flow, there is the risk that heat energy is transported by the heatable temperature sensor to the passive temperature sensor arranged downstream in the direction of flow, whereby this does not provide the correct temperature of the measuring medium. If the two temperature sensors are positioned transversely to the flow direction, then temperature gradients transverse to the flow direction have a negative effect on the measurement result. Such temperature gradients occur e.g. in that on one side of the pipeline, e.g. due to a heating source arranged there, a higher temperature prevails than on the other side of the pipeline.
  • the object of the invention is to propose a calorimetric flowmeter whose measured values are essentially independent of the installation position in the measuring tube or in the pipeline.
  • the object is achieved in that the two temperature sensors in one The measuring medium facing the region of a housing and are in thermal contact with the flowing through the pipe or through the measuring tube measuring medium that the two temperature sensors in the flow direction (x) and transverse to the flow direction (y) in each case in a defined x-distance and in a first temperature sensor is designed to be heated, that a second temperature sensor provides information about the current temperature of the measuring medium, and that the control / evaluation unit based on the temperature difference between the two temperature sensors and / or based on the the heating power supplied to the first temperature sensor determines the flow of the measuring medium through the pipe or through the measuring tube.
  • the x-distance and / or the y-distance between the two temperature sensors is such that a transmission of thermal energy from the heated temperature sensor to the temperature sensor, the temperature of the medium measures, is approximately zero.
  • An alternative or additive embodiment of the device according to the invention suggests that the y-distance and / or the x-distance between the two temperature sensors are / is such that a transmission of mechanical energy through the Karman vortex street, the is caused by the first temperature sensor in the flow direction, is approximately zero on the downstream in the flow direction second temperature sensor.
  • the x-distance between the two temperature sensors is minimized such that a transversely to the flow direction of the measuring medium occurring temperature gradient at least approximately has no influence on the temperature measurement of the two temperature sensors.
  • a heating unit is provided which is assigned to the heatable temperature sensor, or in the first temperature sensor and / or in the second temperature sensor is an RTD sensor, ie a Resistance Temperature Device.
  • control / evaluation unit controls the heating unit or the heatable temperature sensor so that the heatable temperature sensor is acted upon by a constant heat output; Subsequently, the control / evaluation unit determines the flow of the measuring medium in the pipeline or in the measuring tube, based on the temperature difference between the first temperature sensor and the second temperature sensor.
  • control / evaluation unit controls the heating unit or the heatable temperature sensor so that there is an approximately constant temperature difference between the first temperature sensor and the second temperature sensor; Subsequently, the control / evaluation unit determines the flow of the measured medium in the pipeline or in the measuring tube on the basis of the heating power supplied to the heatable temperature sensor.
  • control / evaluation unit is designed so that it measures the flow continuously and / or that it detects whether the flow at least falls below or exceeds a predetermined limit.
  • the thermal flow meter operates as a switch. It therefore only recognizes whether or not the measuring medium flows through the pipeline or the measuring tube.
  • An embodiment of the device according to the invention further suggests that both temperature sensors are designed so that they are heatable, and that the control / evaluation unit controls the two temperature sensors so that either one of the two temperature sensors supplies the temperature of the medium and that the other temperature sensor is heated.
  • the measurement result is then obtained, for example, by averaging the measured values from the different measurements.
  • FIG. 1 is a schematic representation of a thermal flow measuring device
  • FIG 3 shows an embodiment of the arrangement of the temperature sensors in the thermal flow meter according to the invention.
  • Fig. 1 shows a schematic representation of the thermal according to the invention
  • the flowmeter 1 is attached via a screw thread 9 in a nozzle 4, which is located on the pipe 2.
  • a nozzle 4 In the pipe 2 is the flowing measuring medium 3.
  • the flowmeter 1 it is possible to form the flowmeter 1 with integrated measuring tube as an inline measuring device.
  • the temperature measuring device 6 is located in the measuring medium 3 facing the region of the housing 5.
  • the control of the temperature sensors 11, 12 and / or the evaluation of the temperature sensors 11, 12 supplied measurement signals via the control / evaluation unit 10, the in the case shown in the converter 7 is arranged. Via the connection 8, the communication with a remote, not separately shown in FIG. 1 control point.
  • At least one of the two temperature sensors 11, 12 may be an electrically heatable resistance element, a so-called. RTD sensors, act.
  • a conventional temperature sensor for example a PtIOO or PtIOOO or a thermocouple, to which a thermally coupled heating unit 13 is assigned.
  • the heating unit 13 is arranged in the housing 5 in FIG. 1 and thermally coupled to the heatable temperature sensor 11, 12, but largely decoupled from the measuring medium.
  • the coupling or decoupling is preferably carried out via the filling of the corresponding intermediate spaces with a thermally highly conductive or a thermally poorly conductive material. Preferably, this is a potting material used.
  • the flowmeter 1 according to the invention it is possible with the flowmeter 1 according to the invention to measure the flow continuously; Alternatively, it is possible to use the flowmeter 1 according to the invention as a flow switch, which always indicates the change of a switching state, if at least a predetermined limit is exceeded or exceeded.
  • both temperature sensors 11, 12 are designed to be heatable, wherein the desired function of the first temperature sensor 11 or the second temperature sensor 12 of the control / evaluation unit
  • control / evaluation unit 10 is determined. For example, it is possible for the control / evaluation unit 10 to actuate the two temperature sensors 11, 12 alternately as active or passive temperature sensors 11, 12 and to determine the flow measured value via an averaging of the measured values supplied by the two temperature sensors 11, 12.
  • FIG. 2 a the two temperature sensors 11, 12 are arranged one behind the other as viewed in the flow direction S, while they are arranged next to one another transversely to the flow direction S in FIG. 2 b.
  • the disadvantages of the solution shown in Fig. Ia can be seen in that on the one hand, the eddy current, at the first temperature sensor
  • the second temperature sensor 12 excites to mechanical vibrations.
  • the second temperature sensor 12 begins to vibrate at its resonant frequency, which can lead to material fatigue.
  • the fluid measuring medium which flows past the first heatable temperature sensor 11, heated by this.
  • the second temperature sensor 12 does not provide the correct temperature of the measuring medium 3, but measures an elevated temperature.
  • the heating of the measuring medium 3 causes a measurement error in the flow measurement, which results from the quotient of the measured from the second temperature sensor 12 elevated temperature of the measuring medium 3 and the temperature difference between the two temperature sensors 11, 12. In the worst case, this can cause the second temperature sensor
  • the two temperature sensors 11, 12 are arranged transversely to the flow direction S side by side.
  • this arrangement is very critical if a temperature gradient occurs transversely to the flow direction S within the measuring tube or the pipe. In particular, with small diameters of the pipe 2, this results in significant measurement errors in the determination of the flow.
  • a temperature gradient transverse to the flow direction S in the measuring medium 3 is caused, for example, by the fact that an external heat source or a heat sink is located on one side of the pipe 2.
  • Fig. 3 shows an embodiment of the arrangement of the temperature sensors 11, 12 in the inventive thermal flow meter 1.
  • the first temperature sensor 11 is designed to be heated, while the second temperature sensor 12 measures the temperature of the measuring medium 3.
  • the two temperature sensors 11, 12 are arranged offset in the flow direction x and transversely to the flow direction y in each case in a defined x-distance and in a defined y-distance to each other.
  • the x-distance and / or the y-distance between the two temperature sensors 11, 12 are so dimensioned that a transmission of thermal energy from the heatable temperature sensor 11 to the temperature sensor 12, the Temperature of the measuring medium 3 measures, approximately zero.
  • the x-distance between the two temperature sensors 11, 12 is minimized such that a temperature gradient occurring transversely to the flow direction S of the measuring medium 3 at least approximately has no influence on the temperature measurement of the two temperature sensors 11, 12 and thus has on the flow measurement.
  • a heating unit is provided, which is assigned to the heatable temperature sensor 11, or the first temperature sensor 11 and / or the second temperature sensor 12 is an RTD sensor, ie a resistance temperature device.
  • the y-distance and the x-distance between the two temperature sensors 11, 12 are dimensioned so that a transmission of mechanical energy via the Karman vortex street, by the first in the flow direction S temperature sensor 11, in response to the mung direction S subsequent second temperature sensor 12 is approximately zero.
  • Heisenberg's estimation Wienerner Heisenberg: Absolute Dimensions of Karman Vortex Motion, Technical Notes, National Advisory Committee for Aeronautics, No. 126, 1922

Abstract

The invention relates to a thermal flowmeter comprising two temperature sensors (11, 12) and a control/evaluation unit (10). The two temperature sensors (11, 12) are disposed in an area of a housing (7) facing the measured medium (3) while being in thermal contact with the measured medium (3) that flows through the pipe (2) or the measuring tube. Furthermore, the two temperature sensors (11, 12) are positioned so as to be offset to each other at a defined x distance and a defined y distance in the direction of flow (x) and perpendicular to the direction of flow (y). The first temperature sensor (11) is embodied so as to be heatable while the second temperature sensor provides data on the current temperature of the measured medium (3). The control/evaluation unit (10) determines the flow rate of the measured medium (3) through the pipe (2) or the measuring tube based on the difference in temperature between the two temperature sensors (11, 12) and/or based on the heating capacity fed to the first temperature sensor (11).

Description

Beschreibung description
Vorrichtung zur Bestimmung und/oder Überwachung des Durchflusses eines MessmediumsDevice for determining and / or monitoring the flow of a measuring medium
[0001] Die Erfindung bezieht sich auf eine thermische bzw. kalorimetrische Vorrichtung zur Bestimmung und/oder Überwachung des Durchflusses eines durch eine Rohrleitung oder durch ein Messrohr strömenden Messmediums mit zwei Temperatursensoren und einer Regel-/Auswerteeinheit. Bei dem Messmedium handelt es sich um ein fließfähiges Medium, insbesondere um ein flüssiges, ein dampfförmiges oder ein gasförmiges Medium.The invention relates to a thermal or calorimetric device for determining and / or monitoring the flow of a flowing through a pipe or through a measuring tube measuring medium with two temperature sensors and a control / evaluation unit. The measuring medium is a flowable medium, in particular a liquid, a vaporous or a gaseous medium.
[0002] Herkömmliche thermische Durchflussmessgeräte verwenden meist zwei möglichst gleichartig ausgestaltete Temperatursensoren. Für industrielle Anwendung sind beide Temperatursensoren üblicherweise in ein Messrohr eingebaut, in dem der Durchfluss eines Messmediums gemessen wird. Einer der beiden Temperatursensoren ist ein sog. passiver Temperatursensor; er erfasst die aktuelle Temperatur des Messmediums. Bei dem zweiten Temperatursensor handelt es sich um einen sog. aktiven Temperatursensor, der über eine Heizeinheit beheizt wird. Als Heizeinheit ist entweder eine zusätzliche Widerstandsheizung vorgesehen, oder bei dem Temperatursensor selbst handelt es sich um ein Widerstandselement, z.B. um einen RTD-(Resistance Temperature Device) Sensor, der durch Umsetzung einer elektrischen Leistung (z.B. durch erhöhten Messstrom) erwärmt wird. Entsprechende Temperatursensoren werden beispielsweise von der Firma Honeywell angeboten und vertrieben.Conventional thermal flow meters usually use two as possible identically designed temperature sensors. For industrial applications, both temperature sensors are usually installed in a measuring tube in which the flow of a measuring medium is measured. One of the two temperature sensors is a so-called passive temperature sensor; it detects the current temperature of the medium to be measured. The second temperature sensor is a so-called active temperature sensor, which is heated by a heating unit. The heating unit is either an additional resistance heater, or the temperature sensor itself is a resistance element, e.g. a RTD (Resistance Temperature Device) sensor, which is heated by conversion of an electrical power (e.g., by increased sense current). Corresponding temperature sensors are offered and sold, for example, by Honeywell.
[0003] Üblicherweise wird in einem thermischen Durchflussmessgerät der beheizbareUsually, in a thermal flow meter, the heatable
Temperatursensor so beheizt, dass sich eine feste Temperaturdifferenz zwischen den beiden Temperatursensoren einstellt. Alternativ ist es auch bekannt geworden, über eine Regel-/Steuereinheit eine zeitkonstante Heizleistung einzuspeisen.Temperature sensor so heated that sets a fixed temperature difference between the two temperature sensors. Alternatively, it has also become known to feed in a regulating / control unit a time-constant heating power.
[0004] Tritt in dem Messrohr kein Durchfluss auf, so erfolgt die Ableitung der Wärme von dem beheizten Temperatursensor über Wärmeleitung, Wärmestrahlung und ggf. auch freie Konvektion innerhalb des Messmediums. Ist das zu messende Medium in Bewegung, kommt eine zusätzliche Abkühlung des beheizten Temperatursensors durch das vorbeiströmende kältere Medium hinzu. Durch das vorbeiströmende Messmedium tritt hier zusätzlich ein Wärmetransport infolge einer erzwungenen Konvektion auf. Um unter diesen Umständen die feste Temperaturdifferenz zwischen den beiden Temperatursensoren aufrecht zu erhalten, ist folglich eine höhere Heizleistung für den beheizten Temperatursensor erforderlich. Im Falle der Einspeisung einer zeitkonstanten Heizleistung verringert sich infolge des Durchflusses des Messmediums die Temperaturdifferenz zwischen den beiden Temperatur-sensoren. [0005] Es besteht ein funktionaler Zusammenhang zwischen der zum Beheizen des Temperatursensors notwendigen Heizenergie und dem Durchfluss, insbesondere dem Masse- durchfluss eines vorgegebenen Messmediums durch eine Rohrleitung bzw. durch das Messrohr. Parameter sind - wie bereits angedeutet - die thermophysikalischen Eigenschaften des Messmediums selbst und der im Messmedium herrschende Druck. Sind die entsprechenden vom Durchfluss abhängigen Kennlinien für diese Parameter erstellt bzw. sind die entsprechenden Parameter in den Funktionsgleichungen bekannt, lässt sich der Massedurchfluss des Messmediums exakt bestimmen. Thermische Messgeräte, die auf dem zuvor beschriebenen Prinzip beruhen, werden von Endress+Hauser unter der Bezeichnung 't-mass' angeboten und vertrieben.If no flow occurs in the measuring tube, then the dissipation of the heat from the heated temperature sensor via heat conduction, heat radiation and optionally also free convection takes place within the measuring medium. If the medium to be measured is in motion, an additional cooling of the heated temperature sensor is added by the colder medium flowing past. Due to the measuring medium flowing past, heat transport due to forced convection also occurs here. Consequently, in order to maintain the fixed temperature difference between the two temperature sensors, a higher heating power is required for the heated temperature sensor. In the case of the supply of a time-constant heating power, the temperature difference between the two temperature sensors decreases as a result of the flow of the measuring medium. There is a functional relationship between the heating energy necessary for heating the temperature sensor and the flow, in particular the mass flow of a given measuring medium through a pipeline or through the measuring tube. Parameters are - as already indicated - the thermo-physical properties of the medium itself and the pressure prevailing in the medium. If the corresponding flow-dependent characteristic curves have been created for these parameters or if the corresponding parameters are known in the functional equations, the mass flow rate of the measuring medium can be determined exactly. Thermal measuring instruments based on the principle described above are offered and sold by Endress + Hauser under the name 't-mass'.
[0006] Üblicherweise sind die beiden Temperatursensoren stiftförmig bzw. gerade und parallel zueinander angeordnet. Dabei haben die Anordnung der Temperatursensoren bezüglich der Strömungsrichtung des Messmediums und das Messmedium selbst unter Umständen einen relativ großen Einfluss auf das Messergebnis.Usually, the two temperature sensors are pin-shaped or straight and arranged parallel to each other. In this case, the arrangement of the temperature sensors with respect to the flow direction of the measuring medium and the measuring medium itself may have a relatively large influence on the measurement result.
[0007] Die Einbauposition des Durchflussmessgeräts in die Rohrleitung ist üblicherweise so gewählt, dass gewährleistet ist, dass das Messmedium mit den Temperatursensoren in stetigem thermischem Kontakt ist. Mögliche Einbaupositionen sind die seitliche Einbauposition bei vertikal angeordneten Rohrleitungen, oder die Temperatursensoren befinden sich bei einer waagerecht angeordneten Rohrleitung im oberen, im unteren Bereich oder im seitlichen Bereich der Rohrleitung. Im letzten Fall ist die Positionierung im seitlichen Bereich der Rohrleitung insofern günstig, da bei dieser Art der Montage weder Ablagerungen nach Luftpolster die Funktion des Messgeräts negativ beeinflussen können. Je nach Einbauposition tritt nun aber bei den bekannten parallel angeordneten, stiftförmigen Temperatursensoren das Problem auf, dass die Messwerte in Abhängigkeit von der Einbauposition variieren. Sind die beiden Temperatursensoren in Strömungsrichtung hintereinander positioniert, so besteht die Gefahr, dass von dem beheizbaren Temperatursensor Wärmeenergie zu dem in Strömungsrichtung nachfolgend angeordneten passiven Temperatursensor transportiert, wodurch dieser nicht die korrekte Temperatur des Messmediums liefert. Sind die beiden Temperatursensoren quer zur Strömungsrichtung positioniert, so wirken sich Temperaturgradienten quer zur Strömungsrichtung negativ auf das Messergebnis aus. Derartige Temperaturgradienten treten z.B. dadurch auf, dass auf einer Seite der Rohrleitung, z.B. infolge einer dort angeordneten Heizquelle, eine höhere Temperatur herrscht als auf der anderen Seite der Rohrleitung.The installation position of the flowmeter in the pipeline is usually chosen so that it is ensured that the measuring medium with the temperature sensors in continuous thermal contact. Possible installation positions are the lateral installation position with vertically arranged pipelines, or the temperature sensors are located at a horizontally arranged pipeline in the upper, in the lower area or in the lateral area of the pipeline. In the latter case, the positioning in the lateral region of the pipeline is advantageous insofar as in this type of assembly neither deposits after air cushion can adversely affect the function of the meter. Depending on the installation position, however, the problem arises in the case of the known parallel, pin-type temperature sensors that the measured values vary depending on the installation position. If the two temperature sensors are positioned behind one another in the direction of flow, there is the risk that heat energy is transported by the heatable temperature sensor to the passive temperature sensor arranged downstream in the direction of flow, whereby this does not provide the correct temperature of the measuring medium. If the two temperature sensors are positioned transversely to the flow direction, then temperature gradients transverse to the flow direction have a negative effect on the measurement result. Such temperature gradients occur e.g. in that on one side of the pipeline, e.g. due to a heating source arranged there, a higher temperature prevails than on the other side of the pipeline.
[0008] Der Erfindung liegt die Aufgabe zugrunde, ein kalorimetrisches Durchfluss- messgerät vorzuschlagen, dessen Messwerte im wesentlichen unabhängig sind von der Einbauposition in dem Messrohr bzw. in der Rohrleitung.The object of the invention is to propose a calorimetric flowmeter whose measured values are essentially independent of the installation position in the measuring tube or in the pipeline.
[0009] Die Aufgabe wird dadurch gelöst, dass die beiden Temperatursensoren in einem dem Messmedium zugewandten Bereich eines Gehäuses angeordnet und in thermischem Kontakt mit dem durch die Rohrleitung bzw. durch das Messrohr strömende Messmedium sind, dass die beiden Temperatursensoren in Strömungsrichtung (x) und quer zur Strömungsrichtung (y) jeweils in einem definierten x- Abstand und in einem definierten y-Abstand versetzt zueinander angeordnet sind, dass ein erster Temperatursensor beheizbar ausgestaltet ist, dass ein zweiter Temperatursensor Information über die aktuelle Temperatur des Messmediums bereitstellt, und dass die Regel-/ Auswerteeinheit anhand der Temperaturdifferenz zwischen den beiden Temperatursensoren und/oder anhand der dem ersten Temperatursensor zugeführten Heizleistung den Durchfluss des Messmediums durch die Rohrleitung bzw. durch das Messrohr ermittelt.The object is achieved in that the two temperature sensors in one The measuring medium facing the region of a housing and are in thermal contact with the flowing through the pipe or through the measuring tube measuring medium that the two temperature sensors in the flow direction (x) and transverse to the flow direction (y) in each case in a defined x-distance and in a first temperature sensor is designed to be heated, that a second temperature sensor provides information about the current temperature of the measuring medium, and that the control / evaluation unit based on the temperature difference between the two temperature sensors and / or based on the the heating power supplied to the first temperature sensor determines the flow of the measuring medium through the pipe or through the measuring tube.
[0010] Gemäß einer vorteilhaften Weiterbildung der erfindungsgemäßen Vorrichtung sind/ ist der x- Abstand und/oder der y-Abstand zwischen den beiden Temperatursensoren so bemessen, dass eine Übertragung von thermischer Energie von dem beheizbaren Temperatursensor auf den Temperatursensor, der die Temperatur des Mediums misst, näherungsweise Null ist.According to an advantageous embodiment of the device according to the invention, the x-distance and / or the y-distance between the two temperature sensors is such that a transmission of thermal energy from the heated temperature sensor to the temperature sensor, the temperature of the medium measures, is approximately zero.
[0011] Eine alternative oder additive Ausgestaltung der erfindungsgemäßen Vorrichtung schlägt vor, dass der y-Abstand und/oder der x- Abstand zwischen den beiden Temperatursensoren so bemessen sind/ist, dass eine Übertragung von mechanischer Energie über die Karman'sche Wirbelstraße, die durch den in Strömungsrichtung ersten Temperatursensor hervorgerufen ist, auf den in Strömungsrichtung nachfolgenden zweiten Temperatursensor näherungsweise Null ist.An alternative or additive embodiment of the device according to the invention suggests that the y-distance and / or the x-distance between the two temperature sensors are / is such that a transmission of mechanical energy through the Karman vortex street, the is caused by the first temperature sensor in the flow direction, is approximately zero on the downstream in the flow direction second temperature sensor.
[0012] Insbesondere wird es im Zusammenhang mit der erfindungsgemäßen Vorrichtung als vorteilhaft angesehen, dass der x- Abstand zwischen den beiden Temperatursensoren derart minimiert ist, dass ein quer zur Strömungsrichtung des Messmediums auftretender Temperaturgradient zumindest näherungsweise keinen Einfluss auf die Temperaturmessung der beiden Temperatursensoren hat.In particular, it is considered advantageous in connection with the device according to the invention that the x-distance between the two temperature sensors is minimized such that a transversely to the flow direction of the measuring medium occurring temperature gradient at least approximately has no influence on the temperature measurement of the two temperature sensors.
[0013] Wie bereits erwähnt, ist entweder eine Heizeinheit vorgesehen, die dem beheizbaren Temperatursensor zugeordnet ist, oder bei dem ersten Temperatursensor und/oder bei dem zweiten Temperatursensor handelt es sich um einen RTD-Sensor, also um ein Resistance Temperature Device.As already mentioned, either a heating unit is provided which is assigned to the heatable temperature sensor, or in the first temperature sensor and / or in the second temperature sensor is an RTD sensor, ie a Resistance Temperature Device.
[0014] Eine vorteilhafte Ausgestaltung der erfindungsgemäßen Vorrichtung sieht vor, dass die Regel-/Auswerteeinheit die Heizeinheit bzw. den beheizbaren Temperatursensor so ansteuert, dass der beheizbare Temperatursensor mit einer konstanten Heizleistung beaufschlagt ist; anschließend bestimmt die Regel-/ Auswerteeinheit anhand der Temperaturdifferenz zwischen dem ersten Temperatursensor und dem zweiten Temperatursensor den Durchfluss des Messmediums in der Rohrleitung bzw. in dem Messrohr, bestimmt. Alternativ ist vorgesehen, dass die Regel-/Auswerteinheit die Heizeinheit bzw. den beheizbaren Temperatursensor so ansteuert, dass zwischen dem ersten Temperatursensor und dem zweiten Temperatursensor eine näherungsweise konstante Temperaturdifferenz herrscht; anschließend bestimmt die Regel-/ Auswerteeinheit anhand der dem beheizbaren Temperatursensor zugeführten Heizleistung den Durchfluss des Messmediums in der Rohrleitung bzw. in dem Messrohr.An advantageous embodiment of the device according to the invention provides that the control / evaluation unit controls the heating unit or the heatable temperature sensor so that the heatable temperature sensor is acted upon by a constant heat output; Subsequently, the control / evaluation unit determines the flow of the measuring medium in the pipeline or in the measuring tube, based on the temperature difference between the first temperature sensor and the second temperature sensor. Alternatively, it is provided that the control / evaluation unit, the heating unit or controls the heatable temperature sensor so that there is an approximately constant temperature difference between the first temperature sensor and the second temperature sensor; Subsequently, the control / evaluation unit determines the flow of the measured medium in the pipeline or in the measuring tube on the basis of the heating power supplied to the heatable temperature sensor.
[0015] Darüber hinaus ist vorgesehen, dass die Regel-/Auswerteeinheit so ausgestaltet ist, dass sie den Durchfluss kontinuierlich misst und/oder dass sie erkennt, ob der Durchfluss zumindest einen vorgegebenen Grenzwert unter- oder überschreitet. Im zuletzt genannten Fall arbeitet das thermische Durchflussmessgerät als Schalter. Es erkennt also nur, ob Messmedium durch die Rohrleitung bzw. das Messrohr fließt oder nicht.In addition, it is provided that the control / evaluation unit is designed so that it measures the flow continuously and / or that it detects whether the flow at least falls below or exceeds a predetermined limit. In the latter case, the thermal flow meter operates as a switch. It therefore only recognizes whether or not the measuring medium flows through the pipeline or the measuring tube.
[0016] Eine Ausführungsform der erfindungsgemäßen Vorrichtung schlägt des- weiteren vor, dass beide Temperatursensoren so ausgestaltet sind, dass sie beheizbar sind, und dass die Regel-/ Auswerteeinheit die beiden Temperatursensoren so ansteuert, dass wahlweise einer der beiden Temperatursensoren die Temperatur des Messmediums liefert und dass der andere Temperatursensor aufgeheizt wird. Das Messergebnis wird dann beispielsweise durch eine Mittelwertbildung der Messwerte aus den unterschiedlichen Messungen gewonnen.An embodiment of the device according to the invention further suggests that both temperature sensors are designed so that they are heatable, and that the control / evaluation unit controls the two temperature sensors so that either one of the two temperature sensors supplies the temperature of the medium and that the other temperature sensor is heated. The measurement result is then obtained, for example, by averaging the measured values from the different measurements.
[0017] Die Erfindung wird anhand der nachfolgenden Figuren näher erläutert. Es zeigt:The invention will be explained in more detail with reference to the following figures. It shows:
[0018] Fig. 1: eine schematische Darstellung eines thermischen Durchflussmess-geräts,1 is a schematic representation of a thermal flow measuring device,
[0019] Fig. 2: mögliche Anordnungen der beiden TemperatursensorenFig. 2: possible arrangements of the two temperature sensors
[0020] a) in Strömungsrichtung hintereinanderA) in the flow direction one behind the other
[0021] b) quer zur Strömungsrichtung nebeneinanderB) transversely to the flow direction next to each other
[0022] Fig. 3: eine Ausführungsform der Anordnung der Temperatursensoren bei dem erfindungsgemäßen thermischen Durchflussmessgerät.3 shows an embodiment of the arrangement of the temperature sensors in the thermal flow meter according to the invention.
[0023] Fig. 1 zeigt eine schematische Darstellung des erfindungsgemäßen thermischenFig. 1 shows a schematic representation of the thermal according to the invention
Durchflussmessgeräts 1. Das Durchflussmessgerät 1 ist über ein Schraubgewinde 9 in einem Stutzen 4, der sich an der Rohrleitung 2 befindet, befestigt. In der Rohrleitung 2 befindet sich das strömende Messmedium 3. Alternativ ist es möglich, das Durchflussmessgerät 1 mit integriertem Messrohr als InlineMessgerät auszubilden.Flowmeter 1. The flowmeter 1 is attached via a screw thread 9 in a nozzle 4, which is located on the pipe 2. In the pipe 2 is the flowing measuring medium 3. Alternatively, it is possible to form the flowmeter 1 with integrated measuring tube as an inline measuring device.
[0024] Die Temperaturmesseinrichtung 6 befindet sich in dem dem Messmedium 3 zugewandten Bereich des Gehäuses 5. Die Ansteuerung der Temperatursensoren 11, 12 und/oder die Auswertung der von den Temperatursensoren 11, 12 gelieferten Messsignale erfolgt über die Regel-/Auswerteeinheit 10, die im gezeigten Fall im Umformer 7 angeordnet ist. Über die Verbindung 8 erfolgt die Kommunikation mit einer entfernten, in der Fig. 1 nicht gesondert dargestellten Kontrollstelle.The temperature measuring device 6 is located in the measuring medium 3 facing the region of the housing 5. The control of the temperature sensors 11, 12 and / or the evaluation of the temperature sensors 11, 12 supplied measurement signals via the control / evaluation unit 10, the in the case shown in the converter 7 is arranged. Via the connection 8, the communication with a remote, not separately shown in FIG. 1 control point.
[0025] Wie bereits zuvor erwähnt, kann es sich bei zumindest einem der beiden Temperatursensoren 11, 12 um ein elektrisch beheizbares Widerstands-element, um einen sog. RTD-Sensoren, handeln. Selbstverständlich kann in Verbindung mit der erfindungsgemäßen Lösung auch ein üblicher Temperatursensor, z.B. ein PtIOO oder PtIOOO oder ein Thermoelement eingesetzt werden, dem eine thermisch angekoppelte Heizeinheit 13 zugeordnet ist. Die Heizeinheit 13 ist in der Fig. 1 im Gehäuse 5 angeordnet und thermisch an den beheizbaren Temperatursensor 11, 12 gekoppelt, aber von dem Messmedium weitgehend entkoppelt. Die Ankopplung bzw. die Entkopplung erfolgt bevorzugt über die Auffüllung der entsprechenden Zwischenräume mit einem thermisch gut leitenden bzw. einem thermisch schlecht leitenden Material. Bevorzugt kommt hierzu ein Vergussmaterial zum Einsatz.As already mentioned above, at least one of the two temperature sensors 11, 12 may be an electrically heatable resistance element, a so-called. RTD sensors, act. Of course, in conjunction with the solution according to the invention, a conventional temperature sensor, for example a PtIOO or PtIOOO or a thermocouple, to which a thermally coupled heating unit 13 is assigned. The heating unit 13 is arranged in the housing 5 in FIG. 1 and thermally coupled to the heatable temperature sensor 11, 12, but largely decoupled from the measuring medium. The coupling or decoupling is preferably carried out via the filling of the corresponding intermediate spaces with a thermally highly conductive or a thermally poorly conductive material. Preferably, this is a potting material used.
[0026] Wie bereits an vorhergehender Stelle beschrieben, ist es mit dem erfindungsgemäßen Durchflussmessgerät 1 möglich, den Durchfluss kontinuierlich zu messen; alternativ ist es möglich, das erfindungsgemäße Durchflussmessgerät 1 als Durchflussschalter zu verwenden, der immer dann die Änderung eines Schaltzustandes anzeigt, wenn zumindest ein vorgegebener Grenzwert unter- oder überschritten wird.As already described above, it is possible with the flowmeter 1 according to the invention to measure the flow continuously; Alternatively, it is possible to use the flowmeter 1 according to the invention as a flow switch, which always indicates the change of a switching state, if at least a predetermined limit is exceeded or exceeded.
[0027] Vorteilhafter Weise ist darüber hinaus vorgesehen, dass beide Temperatursensoren 11, 12 beheizbar ausgestaltet sind, wobei die gewünschte Funktion des ersten Temperatursensors 11 oder des zweiten Temperatursensors 12 von der Regel/ AuswerteeinheitAdvantageously, it is further provided that both temperature sensors 11, 12 are designed to be heatable, wherein the desired function of the first temperature sensor 11 or the second temperature sensor 12 of the control / evaluation unit
10 bestimmt ist. Beispielsweise ist es möglich, dass die Regel-/Auswerteeinheit 10 die beiden Temperatursensoren 11, 12 alternierend als aktiven oder passiven Temperatursensor 11, 12 ansteuert und den Durchflussmesswert über eine Mittelung der von beiden Temperatursensoren 11, 12 gelieferten Messwerte bestimmt.10 is determined. For example, it is possible for the control / evaluation unit 10 to actuate the two temperature sensors 11, 12 alternately as active or passive temperature sensors 11, 12 and to determine the flow measured value via an averaging of the measured values supplied by the two temperature sensors 11, 12.
[0028] In Fig. 2 sind bekannte Anordnungen der beiden Temperatursensoren dargestellt. In Fig. 2a sind die beiden Temperatursensoren 11, 12 in Strömungsrichtung S gesehen hintereinander angeordnet, während sie in Fig. 2b nebeneinander quer zur Strömungsrichtung S angeordnet sind. Die Nachteile der in Fig. Ia gezeigten Lösung sind darin zu sehen, dass einerseits der Wirbelstrom, der an dem ersten Temperatursensor2, known arrangements of the two temperature sensors are shown. In FIG. 2 a, the two temperature sensors 11, 12 are arranged one behind the other as viewed in the flow direction S, while they are arranged next to one another transversely to the flow direction S in FIG. 2 b. The disadvantages of the solution shown in Fig. Ia can be seen in that on the one hand, the eddy current, at the first temperature sensor
11 erzeugt wird, den zweiten Temperatursensor 12 zu mechanischen Schwingungen anregt. Im schlimmsten Fall beginnt der zweite Temperatursensor 12 mit seiner Resonanzfrequenz zu schwingen, was zu einer Materialermüdung führen kann. Andererseits wird das fluide Messmedium, das an dem ersten beheizbaren Temperatursensor 11 vorbeiströmt, durch diesen erwärmt. Nachfolgend stellt der zweite Temperatursensor 12 nicht die korrekte Temperatur des Messmediums 3 bereit, sondern misst eine erhöhte Temperatur. Durch die Erwärmung des Messmediums 3 wird ein Messfehler bei der Durchflussmessung verursacht, welcher sich aus dem Quotienten der von dem zweiten Temperatursensor 12 gemessenen erhöhten Temperatur des Messmediums 3 und der zwischen den beiden Temperatursensoren 11, 12 vorgegebenen Temperaturdifferenz ergibt. Im schlimmsten Fall kann dies dazu führen, dass der zweite Temperatursensor11 is generated, the second temperature sensor 12 excites to mechanical vibrations. In the worst case, the second temperature sensor 12 begins to vibrate at its resonant frequency, which can lead to material fatigue. On the other hand, the fluid measuring medium, which flows past the first heatable temperature sensor 11, heated by this. Subsequently, the second temperature sensor 12 does not provide the correct temperature of the measuring medium 3, but measures an elevated temperature. The heating of the measuring medium 3 causes a measurement error in the flow measurement, which results from the quotient of the measured from the second temperature sensor 12 elevated temperature of the measuring medium 3 and the temperature difference between the two temperature sensors 11, 12. In the worst case, this can cause the second temperature sensor
12 durch den Einfluss des ersten heizbaren Temperatursensors 11 und insbesondere im Falle eines gasförmigen Messmediums durch das vorbeiströmende bereits heiße Messmedium 3 immer weiter aufgeheizt wird, wodurch der erste Temperatursensor 11 zwecks Aufrechterhaltung der vorgegebenen Temperaturdifferenz ebenfalls immer weiter aufgeheizt wird. Um diese Gefahr auszuschließen, ist es daher unbedingt erforderlich, dass in Strömungsrichtung und quer zur Strömungsrichtung ein gewisser Abstand zwischen den beiden Temperatursensoren 11, 12 besteht. Letztlich ist dies auch aus Fertigungsgründen notwendig.12 by the influence of the first heatable temperature sensor 11 and in particular in Case of a gaseous medium is heated by the flowing past already hot medium 3 more and more, so that the first temperature sensor 11 is also heated in order to maintain the predetermined temperature difference also more and more. In order to exclude this danger, it is therefore absolutely necessary for there to be a certain distance between the two temperature sensors 11, 12 in the flow direction and transverse to the flow direction. Ultimately, this is also necessary for manufacturing reasons.
[0029] In Fig. 2b sind die beiden Temperatursensoren 11, 12 quer zur Strömungsrichtung S nebeneinander angeordnet. Wie bereits erwähnt, ist diese Anordnung sehr kritisch, wenn innerhalb des Messrohres bzw. der Rohrleitung ein Temperaturgradient quer zur Strömungsrichtung S auftritt. Insbesondere bei kleinen Nennweiten der Rohrleitung 2 ergeben sich hierdurch erhebliche Messfehler bei der Bestimmung des Durchflusses. Verursacht wird ein Temperaturgradient quer zur Strömungsrichtung S in dem Messmedium 3 beispielsweise dadurch, dass sich auf einer Seite der Rohrleitung 2 eine externe Wärmequelle oder eine Wärmesenke befindet.In Fig. 2b, the two temperature sensors 11, 12 are arranged transversely to the flow direction S side by side. As already mentioned, this arrangement is very critical if a temperature gradient occurs transversely to the flow direction S within the measuring tube or the pipe. In particular, with small diameters of the pipe 2, this results in significant measurement errors in the determination of the flow. A temperature gradient transverse to the flow direction S in the measuring medium 3 is caused, for example, by the fact that an external heat source or a heat sink is located on one side of the pipe 2.
[0030] Fig. 3 zeigt eine Ausführungsform der Anordnung der Temperatursensoren 11, 12 bei dem erfindungsgemäßen thermischen Durchflussmessgerät 1. Der erste Temperatursensor 11 ist beheizbar ausgestaltet, während der zweite Temperatursensor 12 die Temperatur des Messmediums 3 misst. Die beiden Temperatursensoren 11, 12 sind in Strömungsrichtung x und quer zur Strömungsrichtung y jeweils in einem definierten x- Abstand und in einem definierten y-Abstand versetzt zueinander angeordnet.Fig. 3 shows an embodiment of the arrangement of the temperature sensors 11, 12 in the inventive thermal flow meter 1. The first temperature sensor 11 is designed to be heated, while the second temperature sensor 12 measures the temperature of the measuring medium 3. The two temperature sensors 11, 12 are arranged offset in the flow direction x and transversely to the flow direction y in each case in a defined x-distance and in a defined y-distance to each other.
[0031] Vorteilhafter Weise sind bzw. ist der x- Abstand und/oder der y-Abstand zwischen den beiden Temperatursensoren 11, 12 so bemessen, dass eine Übertragung von thermischer Energie von dem beheizbaren Temperatur-sensor 11 auf den Temperatursensor 12, der die Temperatur des Mess-mediums 3 misst, näherungsweise Null ist. Insbesondere wird es im Zusammenhang mit der erfindungsgemäßen Vorrichtung als vorteilhaft angesehen, dass der x- Abstand zwischen den beiden Temperatursensoren 11, 12 derart minimiert ist, dass ein quer zur Strömungsrichtung S des Messmediums 3 auftretender Temperaturgradient zumindest näherungsweise keinen Einfluss auf die Temperaturmessung der beiden Temperatursensoren 11, 12 und damit auf die Durchflussmessung hat. Wie bereits erwähnt, ist entweder eine Heizeinheit vorgesehen, die dem beheizbaren Temperatursensor 11 zugeordnet ist, oder bei dem ersten Temperatursensor 11 und/oder bei dem zweiten Temperatursensor 12 handelt es sich um einen RTD-Sensor, also um ein Resistance Temperature Device.Advantageously, the x-distance and / or the y-distance between the two temperature sensors 11, 12 are so dimensioned that a transmission of thermal energy from the heatable temperature sensor 11 to the temperature sensor 12, the Temperature of the measuring medium 3 measures, approximately zero. In particular, it is considered advantageous in connection with the device according to the invention that the x-distance between the two temperature sensors 11, 12 is minimized such that a temperature gradient occurring transversely to the flow direction S of the measuring medium 3 at least approximately has no influence on the temperature measurement of the two temperature sensors 11, 12 and thus has on the flow measurement. As already mentioned, either a heating unit is provided, which is assigned to the heatable temperature sensor 11, or the first temperature sensor 11 and / or the second temperature sensor 12 is an RTD sensor, ie a resistance temperature device.
[0032] Alternativ oder additiv sind bzw. ist der y-Abstand und der x- Abstand zwischen den beiden Temperatursensoren 11, 12 so bemessen, dass eine Übertragung von mechanischer Energie über die Karman'sche Wirbelstraße, die durch den in Strömungsrichtung S ersten Temperatursensor 11 hervorgerufen ist, auf den in Strö- mungsrichtung S nachfolgenden zweiten Temperatursensor 12 näherungsweise Null ist. Laut einer Abschätzung von Heisenberg (Werner Heisenberg: 'Absolute Dimensions of Karman Vortex Motion', Technical Notes, National Advisory Committee for Aeronautics, No. 126, 1922) ist das Verhältnis zwischen der Breite h der Karman' sehen Wirbelstraße im Verhältnis zum Durchmesser d des den Durchfluss des Messmediums 3 störenden Temperatursensors 11 ein Faktor 1,54. Daher ist der zweite Temperatursensor 12 bevorzugt so angeordnet, dass er außerhalb der Karman' sehen Wirbelstraße mit einer Breite von h = 1,54 ■ d liegt. [0033] BezugszeichenlisteAlternatively or additively, the y-distance and the x-distance between the two temperature sensors 11, 12 are dimensioned so that a transmission of mechanical energy via the Karman vortex street, by the first in the flow direction S temperature sensor 11, in response to the mung direction S subsequent second temperature sensor 12 is approximately zero. According to Heisenberg's estimation (Werner Heisenberg: Absolute Dimensions of Karman Vortex Motion, Technical Notes, National Advisory Committee for Aeronautics, No. 126, 1922), the ratio between the width h of the Karman vortex street in relation to the diameter d of the flow of the measuring medium 3 interfering temperature sensor 11 a factor of 1.54. Therefore, the second temperature sensor 12 is preferably arranged to be outside the Karman vortex street with a width of h = 1.54 ■ d. [0033] List of Reference Numerals
1. erfindungsgemäße Vorrichtung1. inventive device
2. Rohrleitung / Messrohr2nd pipeline / measuring tube
3. Messmedium3. Measuring medium
4. Stutzen4. neck
5. Gehäuse5. Housing
6. Temperaturmesseinrichtung6. Temperature measuring device
7. Umformer7. Converter
8. Verbindungsleitung8. Connecting line
9. Gewinde9. Thread
10. Regel-/Aus werteeinheit10. Control / evaluation unit
11. Erster Temperatursensor11. First temperature sensor
12. Zweiter Temperatursensor12. Second temperature sensor
13. Heizeinheit 13. Heating unit

Claims

Ansprücheclaims
[0001] 1. Vorrichtung zur Bestimmung und/oder Überwachung des Durchflusses eines1. Device for determining and / or monitoring the flow of a
Messmediums (3) durch eine Rohrleitung (2) bzw. durch ein Messrohr mit zwei Temperatursensoren (11, 12) und einer Regel-/Auswerteeinheit (10), wobei die beiden Temperatursensoren (11, 12) in einem dem Messmedium (3) zugewandten Bereich eines Gehäuses (7) angeordnet und in thermischem Kontakt mit dem durch die Rohrleitung (2) bzw. durch das Messrohr strömende Messmedium (3) sind, wobei die beiden Temperatursensoren (11, 12) in Strömungsrichtung (x) und quer zur Strömungsrichtung (y) jeweils in einem definierten x- Abstand und in einem definierten y-Abstand versetzt zueinander angeordnet sind, wobei ein erster Temperatursensor (11) beheizbar ausgestaltet ist, wobei ein zweiter Temperatursensor (12) Information über die aktuelle Temperatur des Messmediums (3) bereitstellt, und wobei die Regel- /Aus werteeinheit (10) anhand der Temperaturdifferenz zwischen den beiden Temperatursensoren (11, 12) und/oder anhand der dem ersten Temperatursensor (11) zugeführten Heizleistung den Durchfluss des Messmediums (3) durch die Rohrleitung (2) bzw. durch das Messrohr ermittelt.Measuring medium (3) through a pipe (2) or through a measuring tube with two temperature sensors (11, 12) and a control / evaluation unit (10), wherein the two temperature sensors (11, 12) in a the measuring medium (3) facing Are arranged in a region of a housing (7) and in thermal contact with the through the pipe (2) or through the measuring tube flowing measuring medium (3), wherein the two temperature sensors (11, 12) in the flow direction (x) and transversely to the flow direction ( y) in each case in a defined x-distance and in a defined y-offset from each other, wherein a first temperature sensor (11) is designed to be heated, wherein a second temperature sensor (12) provides information about the current temperature of the measuring medium (3) , And wherein the control / evaluation unit (10) on the basis of the temperature difference between the two temperature sensors (11, 12) and / or based on the first temperature sensor (11) supplied heating power the flow ss of the measuring medium (3) through the pipe (2) or determined by the measuring tube.
[0002] 2. Vorrichtung nach Anspruch 1, wobei der x- Abstand und der y-Abstand zwischen den beiden Temperatursensoren (11, 12) so bemessen ist, dass eine Übertragung von thermischer Energie von dem beheizbaren Temperatursensor2. Apparatus according to claim 1, wherein the x-distance and the y-distance between the two temperature sensors (11, 12) is dimensioned such that a transmission of thermal energy from the heated temperature sensor
(11) auf den Temperatursensor (12), der die Temperatur des Messmediums (3) misst, näherungsweise Null ist.(11) is approximately zero on the temperature sensor (12), which measures the temperature of the measuring medium (3).
[0003] 3. Vorrichtung nach Anspruch 1 oder 2, wobei der y-Abstand und der x- Abstand zwischen den beiden Temperatursensoren (11, 12) so bemessen ist, dass eine Übertragung von mechanischer Energie über die Karman'sche Wirbelstraße, die durch den in Strömungsrichtung (S) ersten Temperatursensor (11) hervorgerufen ist, auf den in Strömungsrichtung (S) nachfolgenden zweiten Temperatursensor3. Apparatus according to claim 1 or 2, wherein the y-distance and the x-distance between the two temperature sensors (11, 12) is dimensioned such that a transmission of mechanical energy through the Karman vortex street, by in the flow direction (S) first temperature sensor (11) is caused on the downstream in the flow direction (S) second temperature sensor
(12) näherungs weise Null ist.(12) is approximately zero.
[0004] 4. Vorrichtung nach Anspruch 1, 2 oder 3, wobei der x- Abstand zwischen den beiden Temperatursensoren (11, 12) derart minimiert ist, dass ein quer zur Strömungsrichtung (S) des Messmediums (3) auftretender Temperaturgradient zumindest näherungs weise keinen Einfluss auf die Temperaturmessung der beiden Temperatursensoren (11, 12) hat.4. Apparatus according to claim 1, 2 or 3, wherein the x-distance between the two temperature sensors (11, 12) is minimized such that a transverse to the flow direction (S) of the measuring medium (3) occurring temperature gradient, at least approximately has no influence on the temperature measurement of the two temperature sensors (11, 12).
[0005] 5. Vorrichtung nach Anspruch 1, 2, 3 oder 4, wobei eine Heizeinheit (13) vorgesehen ist, die dem beheizbaren Temperatur- senior (11) zugeordnet ist.5. Apparatus according to claim 1, 2, 3 or 4, wherein a heating unit (13) is provided, which is assigned to the heated temperature senior (11).
[0006] 6. Vorrichtung nach einem oder mehreren der vorhergehenden Ansprüche, wobei es sich bei dem ersten Temperatursensor (11, 12) und/oder bei dem zweiten Temperatursensor (12, 11) um jeweils einen RTD-Sensor, also um ein Resistance Temperature Device, handelt.6. Device according to one or more of the preceding claims, wherein it is in the first temperature sensor (11, 12) and / or in the second Temperature sensor (12, 11) by one RTD sensor, ie a Resistance Temperature Device acts.
[0007] 7. Vorrichtung nach einem oder mehreren der vorhergehenden Ansprüche wobei die Regel-/Auswerteeinheit (10) so ausgestaltet ist, dass sie den Durchfluss kontinuierlich misst und/oder dass sie erkennt, ob der Durchfluss zumindest einen vorgegebenen Grenzwert unter- oder überschreitet.7. The device according to one or more of the preceding claims wherein the control / evaluation unit (10) is configured so that it continuously measures the flow and / or that it detects whether the flow exceeds or exceeds at least a predetermined limit ,
[0008] 8. Vorrichtung nach Anspruch 1, 4 oder 5, wobei beide Temperatursensoren (11,8. Apparatus according to claim 1, 4 or 5, wherein both temperature sensors (11,
12) so ausgestaltet sind, dass sie beheizbar sind, und wobei die Regel- /Aus werteeinheit (10) die beiden Temperatursensoren (11, 12) so ansteuert, dass wahlweise einer der beiden Temperatursensoren (12; 11) die Temperatur des Messmediums (3) liefert und dass der andere Temperatursensor (11; 12) aufgeheizt wird. 12) are designed such that they can be heated, and wherein the control / evaluation unit (10) controls the two temperature sensors (11, 12) such that either one of the two temperature sensors (12, 11) controls the temperature of the measuring medium (3 ) and that the other temperature sensor (11; 12) is heated.
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US10942080B2 (en) 2015-01-07 2021-03-09 Homeserve Plc Fluid flow detection apparatus
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