EP1504242A1 - Ultrasonic transducer for an ultrasonic flow-rate meter - Google Patents

Ultrasonic transducer for an ultrasonic flow-rate meter

Info

Publication number
EP1504242A1
EP1504242A1 EP03752748A EP03752748A EP1504242A1 EP 1504242 A1 EP1504242 A1 EP 1504242A1 EP 03752748 A EP03752748 A EP 03752748A EP 03752748 A EP03752748 A EP 03752748A EP 1504242 A1 EP1504242 A1 EP 1504242A1
Authority
EP
European Patent Office
Prior art keywords
ultrasonic
ultrasonic transducer
transducer
piezo elements
piezo
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP03752748A
Other languages
German (de)
French (fr)
Inventor
Andreas Berger
Thomas Fröhlich
Achim Wiest
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Endress and Hauser Flowtec AG
Original Assignee
Endress and Hauser Flowtec AG
Flowtec AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Endress and Hauser Flowtec AG, Flowtec AG filed Critical Endress and Hauser Flowtec AG
Publication of EP1504242A1 publication Critical patent/EP1504242A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • G01F1/66—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 measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
    • G01F1/662—Constructional details
    • 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
    • G01F1/66—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 measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
    • G01F1/667—Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters
    • 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
    • G01F1/66—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 measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
    • G01F1/667—Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters
    • G01F1/668—Compensating or correcting for variations in velocity of sound
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
    • G01S15/02—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems using reflection of acoustic waves
    • G01S15/50—Systems of measurement, based on relative movement of the target
    • G01S15/58—Velocity or trajectory determination systems; Sense-of-movement determination systems

Definitions

  • Ultrasonic flowmeters are widely used in process and automation technology. They allow the volume flow in a pipeline to be determined in a simple manner without contact.
  • the known ultrasonic flow meters work either on the double or on the transit time difference principle.
  • the different transit times of ultrasonic pulses are evaluated relative to the direction of flow of the liquid.
  • ultrasonic pulses are sent by means of transducers both in and against the flow direction. From the transit time difference, the flow velocity and thus the volume flow can be determined if the diameter of the pipe section is known.
  • ultrasonic waves are injected into the liquid at a certain frequency and the ultrasonic waves reflected by the liquid are evaluated.
  • the flow velocity of the liquid can also be determined from the frequency shift between the injected and reflected waves.
  • the ultrasonic waves are generated or received using so-called ultrasonic transducers.
  • ultrasonic transducers are firmly attached to the pipe wall of the relevant pipe section.
  • clamp-on ultrasound measuring systems are also available. In these systems, the ultrasonic transducers are only pressed against the pipe wall with a tension lock.
  • Such systems are known for example from EP-B 686 255, US-A 44 84 478 or US-A 45 98 593.
  • Another ultrasonic flow meter that works on the time difference principle is known from US-A 50 52 230. The transit time is determined here by means of bursts, which are short ultrasonic pulses.
  • the ultrasonic transducers usually consist of a piezo element and a coupling wedge made of plastic.
  • the ultrasonic waves are generated in the piezo element and guided to the pipe wall via the coupling wedge and from there coupled into the liquid. Since the speeds of sound in liquids and plastics are different, the ultrasonic waves are broken at the transition between the different media.
  • the angle of refraction is determined according to Snell 's law. The angle of refraction is therefore dependent on the ratio of the propagation speeds in the two different media.
  • a second ultrasonic sensor was previously required to determine the transmission sound velocity in the medium and in the pipe wall. Since the pipe wall thickness also has an influence on the signal path, it is necessary to determine the pipe wall thickness in certain applications. This is only possible with another third ultrasonic sensor.
  • the object of the present invention is to provide an ultrasonic transducer for an ultrasonic flow meter which does not have the disadvantages mentioned above, which in particular enables simple adaptation to different media and which is simple and inexpensive to produce.
  • the essential idea of the invention is to provide several piezo elements in an ultrasonic transducer for an ultrasonic flow meter, which can be controlled separately from a control logic. By activating the individual piezo elements at different times, wave fronts can be generated in any direction.
  • Advantageous further developments of the invention are specified in the subclaims.
  • FIG. 1 Schematic representation of an ultrasonic flow meter
  • Fig. 1 shows a highly simplified representation of an ultrasonic flow meter with two ultrasonic transducers 2, 3, which are arranged on the outer wall of a pipeline 1 offset axially offset (clamp-on unit).
  • the liquid F in the pipeline 1 flows in the direction of the arrow.
  • This pair of converters 2, 3 can be operated in two different ways. Either the ultrasound transducer 2 acts as a transmitter transducer and the ultrasound transducer as 3 as a receiver transducer or the ultrasound transducer 2 as a receiver transducer and the ultrasound transducer 3 as a transmitter transducer, as a result of which measurements are taken alternately in the direction of flow and against the direction of flow.
  • Each of the ultrasonic transducers 2 and 3 consists of a piezo element P2 and P3 and a coupling element 21 and 31, respectively, which either couple the ultrasonic signals at an angle ⁇ different from 90 ° into the wall of the pipeline.
  • the angle ⁇ is chosen so that the signal reflected on the opposite wall of the pipeline 1 strikes the other ultrasonic transducer.
  • the piezo elements P2, P3 either convert electrical impulses into mechanical vibrations, the actual ultrasonic signals, or conversely mechanical vibrations into electrical impulses.
  • Both ultrasonic transducers 2, 3 are each connected to a measuring circuit 100 via connecting lines 23 and 33.
  • the electrical pulses are conducted via these connecting lines 23, 33. 2 shows the ultrasound transducer 2 in more detail.
  • the ultrasonic transducer 2 consists of a housing 50 which has an adaptation and insulation layer 60 on its underside.
  • the adaptation and insulation layer 60 lies against the outer wall of the pipeline 1 when used.
  • a plurality of piezo elements 40.1, 40.2 ... 40.n are provided in the housing interior on the adaptation and insulation layer 60.
  • the piezo elements are connected to a driver and preamplifier electronics 20 via corresponding feed lines 30.1, 30.2, 30. n.
  • the driver and preamplifier electronics 20 are connected to the measuring circuit 100 via a connecting line 22.
  • FIG. 2 also shows how ultrasonic waves are generated at a certain angle ⁇ by correspondingly staggered activation of the individual piezo elements 40.1 to 40. n.
  • the wavefront is labeled 80 and is perpendicular to the direction of propagation.
  • the optimal direction of propagation can be found by varying the time delay in the control of the adjacent piezo elements (40. i, 40.i + 1) and at the same time checking the received intensity at the transmitter converter.
  • the setting for the receiver converter can be made accordingly.
  • the first half of the piezo elements 40.1 to 40. n / 2 is driven.
  • the second half of the remaining piezo elements 40.n / 2 + 1 to 40. n serve as receiver transducers and detect the echoes of the ultrasonic waves, which either reflect at the tube wall medium interface or at the opposite tube wall become.
  • the speed of sound in the medium or in the pipe wall can be determined from the time delay and the intensity of the echoes.
  • the angle of refraction ⁇ which indeed indicates the direction of the emitted ultrasound waves, can be calculated and a rough adjustment of the two ultrasound transducers 2, 3 can thereby be carried out.
  • only one piezo element is provided in the converter, which is pivotally mounted. Due to the pivotable mounting, the direction in which the ultrasonic wave is emitted can also be set as desired.
  • the ultrasonic transducer consists of a housing 210 which is filled with a coupling liquid 250 (oil).
  • a shaft 203 is pivotally mounted in the interior of the housing 210 and is connected to an inner housing 204.
  • An ultrasound transducer 201 is arranged in the interior of the housing 204 and is connected to the shaft 203 by means of an adhesive and adaptation layer 202.
  • 3b shows a cross section of the ultrasound transducer according to FIG. 3a.
  • the ultrasonic transducer 201 is connected to control electronics (not shown) via an electrical feed 231.
  • the shaft 203 can be rotated by means of a stepper motor 220 via a gear connection 221 and 222.
  • the stepper motor 220 is driven via an electrical feed line 232.
  • the shaft 203 is sealed off from the housing 210 via a shaft seal 211.
  • the housing 210 lies on a tube wall 240, in which the measuring medium flows.
  • the radiation direction of the ultrasound waves or the reception direction can be varied over wide ranges.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Fluid Mechanics (AREA)
  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Acoustics & Sound (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Measuring Volume Flow (AREA)

Abstract

The invention relates to an ultrasonic transducer for an ultrasonic flow-rate meter, wherein several piezo elements (40.1 - 40.n) can be controlled in a time-delayed manner by means of a control logic (20), whereupon the direction of propagation of the radiated ultrasonic waves can be varied within a wide range.

Description

Ultraschallwandler für ein Ultraschall-Durchflussmessgerät Ultrasonic transducer for an ultrasonic flow meter
Ultraschall-Durchflußmeßgeräte werden vielfach in der Prozeß- und Automatisierungstechnik eingesetzt. Sie erlauben in einfacher Weise, den Volumendurchfluß in einer Rohrleitung berührungslos zu bestimmen.Ultrasonic flowmeters are widely used in process and automation technology. They allow the volume flow in a pipeline to be determined in a simple manner without contact.
Die bekannten Ultraschall-Durchflußmeßgeräte arbeiten entweder nach dem Doppier- oder nach dem Laufzeitdifferenz-Prinzip.The known ultrasonic flow meters work either on the double or on the transit time difference principle.
Beim Laufzeitdifferenz-Prinzip werden die unterschiedlichen Laufzeiten von Ultraschallimpulsen relativ zur Strömungsrichtung der Flüssigkeit ausgewertet.With the transit time difference principle, the different transit times of ultrasonic pulses are evaluated relative to the direction of flow of the liquid.
Hierzu werden Ultraschallimpulse mittels Wandler sowohl in wie auch entgegen der Strömungsrichtung gesendet. Aus der Laufzeitdifferenz läßt sich die Strömungsgeschwindigkeit und damit bei bekanntem Durchmesser des Rohrleitungsabschnitts der Volumendurchfluß bestimmen.For this purpose, ultrasonic pulses are sent by means of transducers both in and against the flow direction. From the transit time difference, the flow velocity and thus the volume flow can be determined if the diameter of the pipe section is known.
Beim Doppler-Prinzip werden Ultraschallwellen mit einer bestimmten Frequenz in die Flüssigkeit eingekoppelt und die von der Flüssigkeit reflektierten Ultraschallwellen ausgewertet. Aus der Frequenzverschiebung zwischen den eingekoppelten und reflektierten Wellen läßt sich ebenfalls die Fließgeschwindigkeit der Flüssigkeit bestimmen.In the Doppler principle, ultrasonic waves are injected into the liquid at a certain frequency and the ultrasonic waves reflected by the liquid are evaluated. The flow velocity of the liquid can also be determined from the frequency shift between the injected and reflected waves.
Reflexionen in der Flüssigkeit treten jedoch nur auf, wenn Luftbläschen oder Verunreinigungen in dieser vorhanden sind, so daß dieses Prinzip hauptsächlich bei verunreinigten Flüssigkeiten Verwendung findet.However, reflections in the liquid only occur if air bubbles or impurities are present in it, so that this principle is mainly used for contaminated liquids.
Die Ultraschallwellen werden mit Hilfe sogenannter Ultraschallwandler erzeugt bzw. empfangen. Hierfür sind Ultraschallwandler an der Rohrwandung des betreffenden Rohrleitungsabschnitts fest angebracht. Seit neuerem sind auch Clamp-on-Ultraschall-Meßsysteme erhältlich. Bei diesen Systemen werden die Ultraschallwandler nur noch mit einem Spannverschluß an die Rohrwandung gepreßt. Derartige Systeme sind z.B. aus der EP-B 686 255, US-A 44 84 478 oder US-A 45 98 593 bekannt. Ein weiteres Ultraschall-Durchflußmeßgerät, das nach dem Laufzeitdifferenz- Prinzip arbeitet, ist aus der US-A 50 52 230 bekannt. Die Laufzeit wird hier mittels Bursts, das sind kurze Ultraschallimpulse, ermittelt.The ultrasonic waves are generated or received using so-called ultrasonic transducers. For this purpose, ultrasonic transducers are firmly attached to the pipe wall of the relevant pipe section. Recently, clamp-on ultrasound measuring systems are also available. In these systems, the ultrasonic transducers are only pressed against the pipe wall with a tension lock. Such systems are known for example from EP-B 686 255, US-A 44 84 478 or US-A 45 98 593. Another ultrasonic flow meter that works on the time difference principle is known from US-A 50 52 230. The transit time is determined here by means of bursts, which are short ultrasonic pulses.
Die Ultraschallwandler bestehen normalerweise aus einem Piezoelement und einem Koppelkeil aus Kunststoff. Im Piezoelement werden die Ultraschallwellen erzeugt und über den Koppelkeil zur Rohrwandung geführt und von dort in die Flüssigkeit eingekoppelt. Da die Schallgeschwindigkeiten in Flüssigkeiten und Kunststoffen unterschiedlich sind, werden die Ultraschallwellen beim Übergang zwischen den verschiedenen Medien gebrochen. Der Brechungswinkel bestimmt sich nach dem Snell'schen Gesetz. Der Brechungswinkel ist somit abhängig von dem Verhältnis der Ausbreitungsgeschwindigkeiten in den beiden unterschiedlichen Medien.The ultrasonic transducers usually consist of a piezo element and a coupling wedge made of plastic. The ultrasonic waves are generated in the piezo element and guided to the pipe wall via the coupling wedge and from there coupled into the liquid. Since the speeds of sound in liquids and plastics are different, the ultrasonic waves are broken at the transition between the different media. The angle of refraction is determined according to Snell 's law. The angle of refraction is therefore dependent on the ratio of the propagation speeds in the two different media.
Ändert sich das Messmedium, so ändert sich auch der Brechungswinkel und damit der Schallweg zwischen Sendewandler und Empfängerwandler. Für eine optimale Messung ist die Einhaltung eines vorgegebenen Signalweges notwendig. Es ist deshalb den Empfängerwandler entsprechend nachzujustieren. Zur Bestimmung der Sende-Schallgeschwindigkeit im Medium und in der Rohrwandung wurde bisher ein zweiter Ultraschallsensor benötigt. Da die Rohrwandstärke ebenfalls einen Einfluß auf den Signalweg hat, ist es bei bestimmten Anwendungen notwendig, die Rohrwandstärke zu bestimmen. Dies ist nur mit einem weiteren dritten Ultraschallsensor möglich.If the measuring medium changes, so does the angle of refraction and thus the sound path between the transmitter transducer and the receiver transducer. Compliance with a specified signal path is necessary for optimal measurement. It is therefore necessary to readjust the receiver converter accordingly. A second ultrasonic sensor was previously required to determine the transmission sound velocity in the medium and in the pipe wall. Since the pipe wall thickness also has an influence on the signal path, it is necessary to determine the pipe wall thickness in certain applications. This is only possible with another third ultrasonic sensor.
Aufgabe der vorliegenden Erfindung ist es, einen Ultraschallwandler für ein Ultraschalldurchflußmeßgerat anzugeben, der die oben genannten Nachteile nicht aufweist, der insbesondere eine einfache Anpassung an unterschiedlichen Medien ermöglicht und der einfach und kostengünstig herstellbar ist.The object of the present invention is to provide an ultrasonic transducer for an ultrasonic flow meter which does not have the disadvantages mentioned above, which in particular enables simple adaptation to different media and which is simple and inexpensive to produce.
Gelöst wird diese Aufgabe durch die im Anspruch 1 angegebenen Merkmale.This object is achieved by the features specified in claim 1.
Wesentliche Idee der Erfindung ist es, mehrere Piezoelemente bei einem Ultraschallwandler für einen Ultraschall-Durchflußmesser vorzusehen, die separat von einer Steuerlogik ansteuerbar sind. Durch zeitversetztes Ansteuern der einzelnen Piezoelemente können Wellenfronten in beliebigen Richtungen erzeugt werden. Vorteilhafte Weiterentwicklungen der Erfindung sind in den Unteransprüchen angegeben.The essential idea of the invention is to provide several piezo elements in an ultrasonic transducer for an ultrasonic flow meter, which can be controlled separately from a control logic. By activating the individual piezo elements at different times, wave fronts can be generated in any direction. Advantageous further developments of the invention are specified in the subclaims.
Nachfolgend ist die Erfindung anhand eines in der Zeichnung dargestellten Ausführungsbeispiels näher erläutert.The invention is explained in more detail below on the basis of an exemplary embodiment shown in the drawing.
Fig. 1 Schematische Darstellung eines UltraschalldurchflußmeßgerätesFig. 1 Schematic representation of an ultrasonic flow meter
Fig. 2 Erfindungsgemäße UltraschallwandlerFig. 2 Ultrasonic transducer according to the invention
Fig. 1 zeigt in stark vereinfachter Darstellung ein Ultraschall-Durchflußmessgerät mit zwei Ultraschallwandlern 2, 3, die auf der Außenwandung einer Rohrleitung 1 achsparallel versetzt lösbar (Clamp-on-Einheit) angeordnet sind. Die Flüssigkeit F in der Rohrleitung 1 fließt in Pfeilrichtung.Fig. 1 shows a highly simplified representation of an ultrasonic flow meter with two ultrasonic transducers 2, 3, which are arranged on the outer wall of a pipeline 1 offset axially offset (clamp-on unit). The liquid F in the pipeline 1 flows in the direction of the arrow.
Dieses Wandlerpaar 2, 3 kann auf zwei unterschiedliche Weisen betrieben werden. Entweder wirkt der Ultraschallwandler 2 als Sendewandler und der Ultraschallwandler als 3 als Empfängerwandler oder der Ultraschallwandler 2 als Empfängerwandler und der Ultraschallwandler 3 als Sendewandler, wodurch abwechselnd in Strömungsrichtung bzw. entgegen der Strömungsrichtung gemessen wird.This pair of converters 2, 3 can be operated in two different ways. Either the ultrasound transducer 2 acts as a transmitter transducer and the ultrasound transducer as 3 as a receiver transducer or the ultrasound transducer 2 as a receiver transducer and the ultrasound transducer 3 as a transmitter transducer, as a result of which measurements are taken alternately in the direction of flow and against the direction of flow.
Jeder der Ultraschallwandler 2 bzw. 3 besteht aus jeweils einem Piezoelement P2 bzw. P3 und jeweils einem Koppelelement 21 bzw. 31 , das die Ultraschallsignale unter einem von 90° verschiedenen Winkel α entweder in die Wandung der Rohrleitung ein- bzw. auskoppelt werden. Der Winkel α ist so gewählt, daß das an der gegenüberliegenden Wandung der Rohrleitung 1 reflektierte Signal auf den jeweils anderen Ultraschallwandler trifft.Each of the ultrasonic transducers 2 and 3 consists of a piezo element P2 and P3 and a coupling element 21 and 31, respectively, which either couple the ultrasonic signals at an angle α different from 90 ° into the wall of the pipeline. The angle α is chosen so that the signal reflected on the opposite wall of the pipeline 1 strikes the other ultrasonic transducer.
Die Piezoelemente P2, P3 wandeln entweder elektrische Impulse in mechanische Schwingungen, die eigentlichen Ultraschallsignale, oder umgekehrt mechanische Schwingungen in elektrische Impulse um.The piezo elements P2, P3 either convert electrical impulses into mechanical vibrations, the actual ultrasonic signals, or conversely mechanical vibrations into electrical impulses.
Beide Ultraschallwandler 2,3 sind jeweils über Anschlußleitungen 23 bzw. 33 mit einer Meßschaltung 100 verbunden. Über diese Anschlußleitungen 23, 33 werden die elektrischen Impulse geführt. In Fig. 2 ist der Ultraschallwandler 2 näher dargestellt. Der Ultraschallwandler 2 besteht aus einem Gehäuse 50, das an seiner Unterseite eine Anpassungs- und Isolationsschicht 60 aufweist. Die Anpassungs- und Isolationsschicht 60 liegt beim Einsatz an der Aussenwandung der Rohrleitung 1 an. Im Gehäuseinnern sind auf Anpassungs- und Isolationsschicht 60 mehrere Piezoelemente 40.1 , 40.2....40.n vorgesehen. Die Piezoelemente sind über entsprechende Zuleitungen 30.1 , 30.2, 30. n mit einer Treiber- und Vorverstärkerelektronik 20 verbunden. Die Treiber- und Vorverstärkerelektronik 20 ist über eine Verbindungsleitung 22 mit der Meßschaltung 100 verbunden.Both ultrasonic transducers 2, 3 are each connected to a measuring circuit 100 via connecting lines 23 and 33. The electrical pulses are conducted via these connecting lines 23, 33. 2 shows the ultrasound transducer 2 in more detail. The ultrasonic transducer 2 consists of a housing 50 which has an adaptation and insulation layer 60 on its underside. The adaptation and insulation layer 60 lies against the outer wall of the pipeline 1 when used. A plurality of piezo elements 40.1, 40.2 ... 40.n are provided in the housing interior on the adaptation and insulation layer 60. The piezo elements are connected to a driver and preamplifier electronics 20 via corresponding feed lines 30.1, 30.2, 30. n. The driver and preamplifier electronics 20 are connected to the measuring circuit 100 via a connecting line 22.
In Fig. 2 ist ebenfalls dargestellt, wie Ultraschallwellen unter einem bestimmten Winkel α durch entsprechendes zeitversetztes Ansteuern der einzelnen Piezoelemente 40.1 bis 40. n erzeugt werden. Die Wellenfront ist mit 80 bezeichnet und steht senkrecht auf die Ausbreitungsrichtung.FIG. 2 also shows how ultrasonic waves are generated at a certain angle α by correspondingly staggered activation of the individual piezo elements 40.1 to 40. n. The wavefront is labeled 80 and is perpendicular to the direction of propagation.
Nachfolgend ist das erfindungsgemäße Verfahren näher erläutert. Durch zeitversetztes Ansteuern der einzelnen Piezoelemente 40.1 bis 40. n kann eine Ultraschallwelle in beliebiger Richtung α erzeugt werden. Dadurch kann die Ausbreitungsrichtung der Ultraschallwellen immer so gewählt werden, daß die abgestrahlte Ultraschallwelle den Empfängerwandler optimal trifft. Dadurch entfällt ein Nachjustieren der beiden Wandler, bei sich ändernden Prozeßbedingungen, insbesondere wenn das Meßmedium gewechselt wird.The method according to the invention is explained in more detail below. By actuating the individual piezo elements 40.1 to 40. n with a time delay, an ultrasound wave can be generated in any direction α. As a result, the direction of propagation of the ultrasonic waves can always be selected so that the emitted ultrasonic wave optimally hits the receiver transducer. This eliminates the need to readjust the two transducers in the event of changing process conditions, especially when the measuring medium is changed.
Die optimale Ausbreitungsrichtung kann dadurch gefunden werden, daß der Zeitverzug bei der Ansteuerung der benachbarten Piezoelemente (40. i, 40.i+1) variiert wird und gleichzeitig die empfangene Intensität beim Senderwandler kontrolliert wird. Entsprechend kann die Einstellung beim Empfängerwandler vorgenommen werden.The optimal direction of propagation can be found by varying the time delay in the control of the adjacent piezo elements (40. i, 40.i + 1) and at the same time checking the received intensity at the transmitter converter. The setting for the receiver converter can be made accordingly.
Neben der optimalen Wahl der Ausbreitungsrichtung ist auch eine Messung der Schallgeschwindigkeit im Medium sowie in der Rohrwandung möglich.In addition to the optimal choice of the direction of propagation, it is also possible to measure the speed of sound in the medium and in the pipe wall.
Zur Bestimmung der Schallgeschwindigkeit im Medium wird nur die erste Hälfte der Piezoelemente 40.1 bis 40. n/2 angesteuert. Die zweite Hälfte der übrigen Piezoelemente 40.n/2+1 bis 40. n dienen als Empfängerwandler und detektieren die Echos der Ultraschallwellen, die entweder an der Grenzfläche Rohrwandungmedium bzw. an der gegenüberliegenden Rohrwandung reflektiert werden. Aus dem Zeitverzug und der Intensität der Echos läßt sich die Schallgeschwindigkeit im Medium bzw. in der Rohrwandung bestimmen.To determine the speed of sound in the medium, only the first half of the piezo elements 40.1 to 40. n / 2 is driven. The second half of the remaining piezo elements 40.n / 2 + 1 to 40. n serve as receiver transducers and detect the echoes of the ultrasonic waves, which either reflect at the tube wall medium interface or at the opposite tube wall become. The speed of sound in the medium or in the pipe wall can be determined from the time delay and the intensity of the echoes.
Aufgrund der Kenntnis über diese beiden Schallgeschwindigkeiten (Medium, Rohrwandung) läßt sich der Brechungswinkel α, der ja die Richtung der abgestrahlten Ultraschallwellen angibt, berechnen und dadurch eine vorab Grobjustierung der beiden Ultraschallwandler 2, 3 vornehmen.On the basis of the knowledge of these two sound velocities (medium, tube wall), the angle of refraction α, which indeed indicates the direction of the emitted ultrasound waves, can be calculated and a rough adjustment of the two ultrasound transducers 2, 3 can thereby be carried out.
In einer vereinfachten Ausgestaltung der Erfindung ist nur ein Piezoelement im Wandler vorgesehen, das schwenkbar gelagert ist. Durch die schwenkbare Lagerung kann die Richtung, in der die Ultraschallwelle abgestrahlt wird ebenfalls quasi beliebig eingestellt werden.In a simplified embodiment of the invention, only one piezo element is provided in the converter, which is pivotally mounted. Due to the pivotable mounting, the direction in which the ultrasonic wave is emitted can also be set as desired.
Der Ultraschallwandler besteht aus einem Gehäuse 210, das mit einer Koppelflüssigkeit 250 (Öl) gefüllt ist. Im inneren des Gehäuses 210 ist eine Welle 203 schwenkbar gelagert, die mit einem inneren Gehäuse 204 verbunden ist. Im Inneren des Gehäuses 204 ist ein Ultraschallwandler 201 angeordnet, der mit der Welle 203 mittels einer Klebe- und Anpassungsschicht 202 verbunden ist. Fig. 3b zeigt einen Querschnitt des Ultraschallwandlers gemäß Fig. 3a. Über eine elektrische Zuführung 231 ist der Ultraschallwandler 201 mit einer nicht dargestellten Steuerelektronik verbunden. Die Welle 203 kann mit Hilfe eines Schrittmotors 220 über eine Zahnradverbindung 221 und 222 gedreht werden. Der Schrittmotor 220 wird über eine elektrische Zuführungsleitung 232 angetrieben. Die Welle 203 ist über eine Wellendichtung 211 gegenüber dem Gehäuse 210 abgedichtet.The ultrasonic transducer consists of a housing 210 which is filled with a coupling liquid 250 (oil). A shaft 203 is pivotally mounted in the interior of the housing 210 and is connected to an inner housing 204. An ultrasound transducer 201 is arranged in the interior of the housing 204 and is connected to the shaft 203 by means of an adhesive and adaptation layer 202. 3b shows a cross section of the ultrasound transducer according to FIG. 3a. The ultrasonic transducer 201 is connected to control electronics (not shown) via an electrical feed 231. The shaft 203 can be rotated by means of a stepper motor 220 via a gear connection 221 and 222. The stepper motor 220 is driven via an electrical feed line 232. The shaft 203 is sealed off from the housing 210 via a shaft seal 211.
Das Gehäuse 210 liegt an einer Rohrwandung 240, in der das Messmedium strömt.The housing 210 lies on a tube wall 240, in which the measuring medium flows.
Durch Drehen der Welle 203 kann die Abstrahlrichtung der Ultraschallwellen bzw. die Empfangsrichtung über weite Bereiche variiert werden. By rotating the shaft 203, the radiation direction of the ultrasound waves or the reception direction can be varied over wide ranges.

Claims

Patentansprüche claims
1. Ultraschallwandler für ein Ultraschalldurchflußmeßgerat, bestehend aus einem Gehäuse 50, das an seiner Unterseite eine Anpassungs- und Isolationsschicht 60 aufweist auf der mehrere Piezoelemente 40.1 bis 40. n vorgesehen sind, die mit einer Steuerlogik 20 verbunden sind, die die einzelnen Piezoelemente 40.1 bis 40. n zeitversetzt ansteuert.1. Ultrasonic transducer for an ultrasonic flow meter, consisting of a housing 50, which has on its underside an adaptation and insulation layer 60 on which a plurality of piezo elements 40.1 to 40. n are provided, which are connected to a control logic 20 which controls the individual piezo elements 40.1 to 40. n controlled with a time delay.
2. Ultraschallwandler nach Anspruch 1 , dadurch gekennzeichnet, daß der Ultraschallwandler als Ciamp-on-Einheit ausgebildet ist.2. Ultrasonic transducer according to claim 1, characterized in that the ultrasonic transducer is designed as a ciamp-on unit.
3. Verfahren zur Bestimmung der optimalen Ausbreitungsrichtung bei einem Ultraschallwandler gemäß der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß der Zeitverzug bei der Ansteuerung benachbarter Piezoelemente 40. i, 40.i+1 variiert wird und die empfangene Intensität beim Empfängerwandler maximiert wird.3. A method for determining the optimal direction of propagation in an ultrasonic transducer according to the preceding claims, characterized in that the time delay in the control of adjacent piezo elements 40. i, 40.i + 1 is varied and the received intensity is maximized in the receiver transducer.
4. Verfahren zur Bestimmung der Schallgeschwindigkeit in einem Medium mit einem Ultraschallwandler nach einem der Ansprüche 1-2, dadurch gekennzeichnet, daß jedes zweite Piezoelement als Sender dient und die übrigen Piezoelemente als Empfänger dienen.4. A method for determining the speed of sound in a medium with an ultrasonic transducer according to one of claims 1-2, characterized in that every second piezo element serves as a transmitter and the other piezo elements serve as a receiver.
5. Ultraschallwandler für ein Ultraschalldurchflußmeßgerat bestehend aus einem Gehäuse, in dem ein Piezoelement angeordnet ist, dadurch gekennzeichnet, daß das Piezoelement schwenkbar gelagert ist. 5. Ultrasonic transducer for an ultrasonic flow meter consisting of a housing in which a piezo element is arranged, characterized in that the piezo element is pivotally mounted.
EP03752748A 2002-05-15 2003-05-15 Ultrasonic transducer for an ultrasonic flow-rate meter Withdrawn EP1504242A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10221771A DE10221771A1 (en) 2002-05-15 2002-05-15 Ultrasonic transducer system is used to measure the flow rate of a fluid within a channel or duct based upon the propagation of the wave signal
DE10221771 2002-05-15
PCT/EP2003/005129 WO2003098166A1 (en) 2002-05-15 2003-05-15 Ultrasonic transducer for an ultrasonic flow-rate meter

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EP1504242A1 true EP1504242A1 (en) 2005-02-09

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AU (1) AU2003247281A1 (en)
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WO (1) WO2003098166A1 (en)

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