WO2002071002A1 - Transducer for an ultrasonic flowmeter - Google Patents

Transducer for an ultrasonic flowmeter Download PDF

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Publication number
WO2002071002A1
WO2002071002A1 PCT/EP2002/002020 EP0202020W WO02071002A1 WO 2002071002 A1 WO2002071002 A1 WO 2002071002A1 EP 0202020 W EP0202020 W EP 0202020W WO 02071002 A1 WO02071002 A1 WO 02071002A1
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WO
WIPO (PCT)
Prior art keywords
transducer
medium
transducer element
protective layer
converter
Prior art date
Application number
PCT/EP2002/002020
Other languages
German (de)
French (fr)
Inventor
Thomas Hahn-Jose
Original Assignee
Spanner-Pollux Gmbh
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 Spanner-Pollux Gmbh filed Critical Spanner-Pollux Gmbh
Publication of WO2002071002A1 publication Critical patent/WO2002071002A1/en

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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

Definitions

  • the invention relates to a transducer for ultrasonic flow meters according to the preamble of claim 1.
  • Ultrasonic transducers are used in ultrasonic flow meters to measure the flow velocity or the flow rate of the medium.
  • Such a converter is known for example from EP-Bl 0 606 536. Its piezo elements are arranged in housings which are sealed off by membranes against the measuring section through which the medium flows. This serves the purpose of protecting the piezo elements against the harmful, e.g. protect corrosive influences of the medium.
  • a converter of the type mentioned in the preamble of claim 1 is known from DE-Al 197 25 717.
  • Such membranes which are usually thin steel foils, are dispensed with here.
  • the electrode of the piezo element facing the medium is projecting on all sides and held under an O-ring.
  • the electrode is glued to the piezo element.
  • the electrode In order to prevent harmful effects of the medium on this electrode, the electrode itself must be made of a corrosion-resistant material. It is certainly a disadvantage that the electrode has no direct contact with the surface of the piezo element, because the adhesive layer in between means that the efficiency when transmitting and receiving ultrasonic waves is not optimal because of the damping caused by the adhesive layer.
  • Such adhesive layers can also age, so that the vibration behavior can change adversely over time.
  • the invention has for its object to provide a transducer for ultrasonic flow meters, which withstands the corrosive influence of the medium in the absence of a membrane or a special housing against the medium to protect the piezo element from the medium.
  • Fig. 1 is a scale diagram of the construction of a transducer element in a sectional view
  • Fig. 2 shows a schematic section of a transducer element installed in a transducer housing. Ways of carrying out the invention and industrial applicability:
  • 1 means a transducer element, the core of which consists of a ceramic disk 2.
  • two electrodes are applied to this ceramic disk 2, a front electrode 3 and a back electrode 4.
  • the front electrode 3 faces the medium.
  • the front electrode 3 extends from the front over the outer surface to the rear and forms a ring there. This arrangement has the advantage that the two electrodes 3, 4 can be contacted on the rear side.
  • a protective layer 5 is applied to the front electrode 3 on the side facing the medium.
  • this protective layer 5 is a corrosion-resistant hard material layer. Due to the corrosion resistance of this protective layer 5, the transducer element 1 can be directly exposed to the medium on this side. A membrane for protecting the transducer element 1 from the medium can therefore be dispensed with.
  • the hardness of the protective layer 5 also ensures that the transducer element 1 is also reliably protected from abrasive particles, which may well be carried in the medium.
  • Such ultrasonic flow meters are used, for example, to measure the consumption of water. Within supply lines for water supply, it happens again and again that sand, for example, penetrates the supply lines due to construction and repair work. Particles carried by the flowing medium can be particularly abrasive if the flow rate is high.
  • the protective layer 5 also offers reliable protection against this.
  • the protective layer 5 advantageously consists of titanium nitride. Titanium nitride is very hard and offers excellent protection of the converter element 1 against abrasive particles. Titanium nitride can be applied using various methods. When applying the protective layer 5, care must be taken that the temperature during the process does not exceed the Curie temperature of the ceramic disk 2. So it is advantageous to use the so-called sputtering process to use, in which titanium forms the cathode, while ionizing a mixture of argon and nitrogen.
  • the process of applying the titanium nitride layer is advantageously controlled in such a way that the protective layer 5 has a so-called closed structure.
  • This structure has a significantly better corrosion resistance than the fractal structure of such layers, which is otherwise often used.
  • the heating to 500 to 1000 ° C. which is otherwise customary for producing the closed structure cannot, however, be used because of the properties of the ceramic disk 2, since the ceramic disk 2 would be damaged in the process.
  • a voltage is applied between the plate with the objects to be coated and the outer wall of the recipient. Because of the increased mobility of the atoms or molecules, there is no columnar growth of the layer, but a smooth layer is formed.
  • the thickness of the protective layer 5 is advantageously 1 to 5 ⁇ m.
  • the minimum thickness of 1 ⁇ m is sufficient to ensure both corrosion protection and protection against abrasion.
  • the converter housing 10 has an interior 11 which is intended for receiving the converter element 1 together with the associated connection connections.
  • the connection connections are routed to the outside in a known manner, a web 13 surrounding the cable duct 12 serving to connect the converter housing 10 to other parts of the measuring section.
  • the transducer element 1 is surrounded on its outer surface and on the outer parts of its front and back by a molded seal 14. This molded seal 14 advantageously consists of a rubber-elastic material.
  • the interior 11 of the converter housing 10 advantageously has an annular step 15, on which the converter element 1 is supported via the molded seal 14.
  • the transducer element 1 is held by a retaining ring 16, the molded seal 14 also being interposed here.
  • the retaining ring 16 can be screwed to the converter housing 10, which enables particularly simple assembly. Instead of the screw connection, other types of connection are also possible.
  • the retaining ring 16 can be pressed onto the converter housing 10 by a press fit. Due to the molded seal 14 in connection with the design of the interior 11 of the converter housing 10 and with the retaining ring 16, no further individual parts are required to fix the converter element 1 in the converter housing 10. This offers advantages in terms of manufacturing and assembly costs. Further embodiments lie within the framework of the technical skills of a designer.
  • the solution according to the invention has the advantage that the electro-acoustic efficiency is improved compared to the known prior art because a membrane protecting the transducer element 1 from the medium or a housing hermetically sealing the transducer element 1 is not required. This also applies to the adhesive layers present in some of these solutions, which can be dispensed with by the invention. The ultrasonic wave damping effect of the adhesive layer and or housing is therefore eliminated.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Volume Flow (AREA)

Abstract

The invention relates to a transducer for an ultrasonic flowmeter. The inventive transducer element (1), which is located in a transducer housing, has a protective layer (5) consisting of a hard material on the front electrode (3) that faces the medium. The hard material is preferably titanium nitride, which has an advantageous closed structure. The thickness of the protective layer (5) is preferably between 1 and 5 νm. The protective layer (5) is resistant to corrosion and abrasion. The invention obviates the need for a membrane that protects the transducer element (1) between the latter (1) and the medium. This permits lower production and assembly costs, whilst increasing the electroacoustic efficiency.

Description

Beschreibung:Description:
Wandler für Ultraschall-DurchflussmesserUltrasonic flow meter transducer
Technisches Gebiet:Technical field:
Die Erfindung bezieht sich auf einen Wandler für Ultraschall-Durchflussmesser gemäß dem Oberbegriff des Anspruchs 1.The invention relates to a transducer for ultrasonic flow meters according to the preamble of claim 1.
Stand der Technik:State of the art:
Ultraschall-Wandler werden in Ultraschall-Durchflussmessern zum Erfassen der Strömungsgeschwindigkeit bzw. der Durchflussmenge des Mediums verwendet.Ultrasonic transducers are used in ultrasonic flow meters to measure the flow velocity or the flow rate of the medium.
Ein solcher Wandler ist beispielsweise aus der EP-Bl 0 606 536 bekannt. Dessen Piezoelemente sind in Gehäusen angeordnet, die gegen die vom Medium durchflossene Messstrecke durch Membranen abgeschlossen sind. Dies dient dem Zweck, die Piezoelemente gegen die schädlichen, z.B. korrosiven Einflüsse des Mediums zu schützen.Such a converter is known for example from EP-Bl 0 606 536. Its piezo elements are arranged in housings which are sealed off by membranes against the measuring section through which the medium flows. This serves the purpose of protecting the piezo elements against the harmful, e.g. protect corrosive influences of the medium.
Ein Wandler der im Oberbegriff des Anspruchs 1 genannten Art ist aus DE-Al 197 25 717 bekannt. Hier wird auf solche Membranen, die in der Regel dünne Stahlfolien sind, verzichtet. Hier ist die dem Medium zugekehrte Elektrode des Piezoelements allseits überstehend ausgebildet und unter einem O-Ring gehalten. Die Elektrode ist auf dem Piezoelement aufgeklebt. Um schädliche Wirkungen des Mediums auf diese Elektrode zu verhindern, muss also die Elektrode selbst aus einem korrosionsbeständigen Werkstoff bestehen. Nachteilig ist sicherlich, dass die Elektrode keinen unmittelbaren Kontakt zur Oberfläche des Piezoelements hat, denn durch die dazwischen liegende Klebstoffschicht ist der Wirkungsgrad beim Senden und Empfangen von Ultraschallwellen wegen der durch die Klebstoffschicht verursachten Dämpfung nicht optimal. Solche Klebstoffschichten können zudem altern, so dass sich das Schwingungsverhalten im Laufe der Zeit nachteilig verändern kann. Dies insbesondere dann, wenn der Ultraschall-Durchflussmesser Teil eines Wärmemengenzählers ist, bei dem das Medium erhöhte Temperatur von durchaus etwa 80 °C haben kann. Nachteilig ist weiter der Aufwand, der dadurch entsteht, dass die Elektrode auf das Piezoelement aufgeklebt werden muss. Aus US-A 4,945,276 ist ein Wandler bekannt, der für die Messung der Geschwindigkeit eines Mediums, nämlich von Gasen und Flüssigkeiten, vorgesehen ist. Der Wandler ist so gestaltet, dass er auch für die Anwendung in bestimmten Gefahrenklassen geeignet ist. Der Wandler befindet sich deshalb in einem becherförmigen Gehäuse, das aus Titan, Stahl, Aluminium oder einen Kohlefaser- Werkstoff besteht.A converter of the type mentioned in the preamble of claim 1 is known from DE-Al 197 25 717. Such membranes, which are usually thin steel foils, are dispensed with here. Here, the electrode of the piezo element facing the medium is projecting on all sides and held under an O-ring. The electrode is glued to the piezo element. In order to prevent harmful effects of the medium on this electrode, the electrode itself must be made of a corrosion-resistant material. It is certainly a disadvantage that the electrode has no direct contact with the surface of the piezo element, because the adhesive layer in between means that the efficiency when transmitting and receiving ultrasonic waves is not optimal because of the damping caused by the adhesive layer. Such adhesive layers can also age, so that the vibration behavior can change adversely over time. This is particularly the case when the ultrasonic flow meter is part of a heat meter in which the medium can have an elevated temperature of around 80 ° C. Another disadvantage is the effort that arises from the fact that the electrode must be glued to the piezo element. From US-A 4,945,276 a converter is known which is provided for measuring the speed of a medium, namely gases and liquids. The converter is designed so that it is also suitable for use in certain hazard classes. The converter is therefore in a cup-shaped housing made of titanium, steel, aluminum or a carbon fiber material.
Aus US-A 5,440,937 ist ein Wandler bekannt, der zur Messung der Geschwindigkeit eines Mediums bei großen Rohrdurchmessern geeignet ist. Dabei soll er Temperaturen von 17 °C widerstehen und auf die giftige Gase und dergleichen geeignet sein. Deshalb sind hier ebenfalls besondere Gehäusewerkstoffe vorgesehen, so etwa Titan, Sandvik 253MA, Hastelloy™ C276, Carpenter™ 20, Werkstoffe der Inconel™ 600-Gruppe oder andere korrosionsbeständige Werkstoffe.From US-A 5,440,937 a converter is known which is suitable for measuring the speed of a medium with large pipe diameters. It should withstand temperatures of 17 ° C and be suitable for toxic gases and the like. This is why special housing materials are also provided here, such as titanium, Sandvik 253MA, Hastelloy ™ C276, Carpenter ™ 20, materials from the Inconel ™ 600 group or other corrosion-resistant materials.
Darstellung der Erfindung:Presentation of the invention:
Der Erfindung liegt die Aufgabe zugrunde, einen Wandler für Ultraschall- Durchflussmesser zu schaffen, der bei Verzicht auf eine Membran oder eines besonderen, gegen das Medium abschließenden Gehäuses zum Schutz des Piezoelements vor dem Medium dem korrosiven Einfluss des Mediums widersteht.The invention has for its object to provide a transducer for ultrasonic flow meters, which withstands the corrosive influence of the medium in the absence of a membrane or a special housing against the medium to protect the piezo element from the medium.
Die genannte Aufgabe wird erfindungsgemäß durch die Merkmale des Anspruchs 1 gelöst. Vorteilhafte Weiterbildungen ergeben sich aus den abhängigen Ansprüchen.According to the invention, the stated object is achieved by the features of claim 1. Advantageous further developments result from the dependent claims.
Kurze Beschreibung der Zeichnung:Brief description of the drawing:
Nachfolgend wird ein Ausführungsbeispiel der Erfindung anhand der Zeichnung näher erläutert. Es zeigen:An exemplary embodiment of the invention is explained in more detail below with reference to the drawing. Show it:
Fig. 1 ein unmaßstäbliches Schema des Aufbaus eines Wandlerelements in einer Schnittdarstellung undFig. 1 is a scale diagram of the construction of a transducer element in a sectional view and
Fig. 2 einen schematischen Schnitt eines in ein Wandlergehäuse eingebauten Wandlerelements. Wege zur Ausführbarkeit der Erfindung und gewerbliche Anwendbarkeit:Fig. 2 shows a schematic section of a transducer element installed in a transducer housing. Ways of carrying out the invention and industrial applicability:
In der Fig. 1 bedeutet 1 ein Wandlerelement, dessen Kern aus einer Keramikscheibe 2 besteht. Auf diese Keramikscheibe 2 sind in bekannter Weise zwei Elektroden aufgebracht, eine Frontelektrode 3 und eine Rückenelektrode 4. Die Frontelektrode 3 ist dem Medium zugewandt. In ebenfalls bekannter Weise dehnt sich die Frontelektrode 3 von der Frontseite über die Mantelfläche bis zur Rückseite aus und bildet dort einen Ring. Diese Anordnung hat den Vorteil, dass die Kontaktierung der beiden Elektroden 3, 4 auf der Rückseite erfolgen kann.In FIG. 1, 1 means a transducer element, the core of which consists of a ceramic disk 2. In a known manner, two electrodes are applied to this ceramic disk 2, a front electrode 3 and a back electrode 4. The front electrode 3 faces the medium. In a likewise known manner, the front electrode 3 extends from the front over the outer surface to the rear and forms a ring there. This arrangement has the advantage that the two electrodes 3, 4 can be contacted on the rear side.
Erfindungsgemäß ist auf der dem Medium zugewandten Seite auf der Frontelektrode 3 eine Schutzschicht 5 aufgebracht. Diese Schutzschicht 5 ist erfindungsgemäß eine korrosionsbeständige Hartstoffschicht. Durch die Korrosionsbeständigkeit dieser Schutzschicht 5 kann das Wandlerelement 1 auf dieser Seite unmittelbar dem Medium ausgesetzt sein. Auf eine Membran zum Schutz des Wandlerelements 1 vor dem Medium kann also verzichtet werden. Durch die Härte der Schutzschicht 5 wird darüber hinaus erreicht, dass das Wandlerelement 1 auch vor abrasiv wirkenden Partikeln, die durchaus im Medium mitgeführt sein können, sicher geschützt ist. Solche Ultraschall-Durchflussmesser werden beispielsweise zur Messung des Verbrauchs von Wasser benützt. Innerhalb von Versorgungsleitungen für die Wasserversorgung kommt es immer wieder vor, dass durch Bau- und Reparaturarbeiten beispielsweise Sand in die Versorgungsleitungen eindringt. Vom strömendem Medium mitgeführte Partikel können insbesondere dann stark abrasiv wirken, wenn die Strömungsgeschwindigkeit hoch ist. Die Schutzschicht 5 bietet auch davor einen zuverlässigen Schutz.According to the invention, a protective layer 5 is applied to the front electrode 3 on the side facing the medium. According to the invention, this protective layer 5 is a corrosion-resistant hard material layer. Due to the corrosion resistance of this protective layer 5, the transducer element 1 can be directly exposed to the medium on this side. A membrane for protecting the transducer element 1 from the medium can therefore be dispensed with. The hardness of the protective layer 5 also ensures that the transducer element 1 is also reliably protected from abrasive particles, which may well be carried in the medium. Such ultrasonic flow meters are used, for example, to measure the consumption of water. Within supply lines for water supply, it happens again and again that sand, for example, penetrates the supply lines due to construction and repair work. Particles carried by the flowing medium can be particularly abrasive if the flow rate is high. The protective layer 5 also offers reliable protection against this.
Vorteilhaft besteht die Schutzschicht 5 aus Titannitrid. Titannitrid ist sehr hart und bietet ausgezeichneten Schutz des Wandlerelements 1 gegen abrasiv wirkende Partikel. Titannitrid lässt sich nach verschiedenen Verfahren aufbringen. Beim Aufbringen der Schutzschicht 5 muss darauf geachtet werden, dass die Temperatur während der Prozesses die Curietemperatur der Keramikscheibe 2 nicht überschreitet. So ist es vorteilhaft, das sogenannte Sputterverfahren anzuwenden, bei dem Titan die Kathode bildet, und dabei eine Mischung von Argon und Stickstoff zu ionisieren.The protective layer 5 advantageously consists of titanium nitride. Titanium nitride is very hard and offers excellent protection of the converter element 1 against abrasive particles. Titanium nitride can be applied using various methods. When applying the protective layer 5, care must be taken that the temperature during the process does not exceed the Curie temperature of the ceramic disk 2. So it is advantageous to use the so-called sputtering process to use, in which titanium forms the cathode, while ionizing a mixture of argon and nitrogen.
Vorteilhaft wird dabei der Prozess des Aufbringens der Titannitrid-Schicht so gesteuert, dass die Schutzschicht 5 eine sogenannte geschlossene Struktur aufweist. Diese Struktur hat einen deutlich besseren Korrosionswiderstand als die sonst vielfach zur Anwendung kommende fraktale Struktur solcher Schichten. Das zur Erzeugung der geschlossenen Struktur sonst übliche Heizen auf 500 bis 1000 °C kann wegen der Eigenschaften der Keramikscheibe 2 aber nicht angewendet werden, weil dabei die Keramikscheibe 2 geschädigt würde. Um ohne Heizen eine geschlossene Struktur der Titannitrid-Schicht zu erreichen, wird zwischen dem Teller mit den zu beschichtenden Objekten und der Außenwand des Rezipienten eine Spannung angelegt. Wegen der dadurch erhöhten Beweglichkeit der Atome bzw. Moleküle erfolgt kein kolumnares Wachstum der Schicht, sondern es entsteht eine glatte Schicht.The process of applying the titanium nitride layer is advantageously controlled in such a way that the protective layer 5 has a so-called closed structure. This structure has a significantly better corrosion resistance than the fractal structure of such layers, which is otherwise often used. The heating to 500 to 1000 ° C. which is otherwise customary for producing the closed structure cannot, however, be used because of the properties of the ceramic disk 2, since the ceramic disk 2 would be damaged in the process. In order to achieve a closed structure of the titanium nitride layer without heating, a voltage is applied between the plate with the objects to be coated and the outer wall of the recipient. Because of the increased mobility of the atoms or molecules, there is no columnar growth of the layer, but a smooth layer is formed.
Die Dicke der Schutzschicht 5 beträgt vorteilhaft 1 bis 5 μm. Die minimale Dicke von 1 μm reicht aus, um sowohl den Korrosionsschutz als auch den Schutz gegen Abrasion zu gewährleisten.The thickness of the protective layer 5 is advantageously 1 to 5 μm. The minimum thickness of 1 μm is sufficient to ensure both corrosion protection and protection against abrasion.
In der Fig. 2 ist ein Beispiel für ein in ein Wandlergehäuse 10 eingebautes Wandlerelement 1 gezeigt. Das Wandlergehäuse 10 weist einen Innenraum 11 auf, der zur Aufnahme des Wandlerelements 1 samt der zugehörigen Anschlussverbindungen bestimmt ist. In einem Kabelkanal 12 werden die Anschlussverbindungen in bekannter Weise nach außen geführt, wobei ein den Kabelkanal 12 umgebender Steg 13 der Verbindung des Wandlergehäuses 10 mit anderen Teilen der Messstrecke dient. Das Wandlerelement 1 ist an seiner Mantelfläche und an den äußeren Partien seiner Frontseite und Rückseite von einer Formdichtung 14 umgeben. Diese Formdichtung 14 besteht vorteilhaft aus einem gummielastischen Werkstoff.2 shows an example of a transducer element 1 installed in a transducer housing 10. The converter housing 10 has an interior 11 which is intended for receiving the converter element 1 together with the associated connection connections. In a cable duct 12, the connection connections are routed to the outside in a known manner, a web 13 surrounding the cable duct 12 serving to connect the converter housing 10 to other parts of the measuring section. The transducer element 1 is surrounded on its outer surface and on the outer parts of its front and back by a molded seal 14. This molded seal 14 advantageously consists of a rubber-elastic material.
Der Innenraum 11 des Wandlergehäuses 10 besitzt vorteilhaft eine ringförmige Stufe 15, an der sich das Wandlerelement 1 über die Formdichtung 14 abstützt. Auf der anderen Seite wird das Wandlerelement 1 gehalten von einem Haltering 16, wobei auch hier die Formdichtung 14 zwischengeschaltet ist. Dabei kann der Haltering 16 mit dem Wandlergehäuse 10 verschraubbar sein, was eine besonders einfache Montage ermöglicht. Statt der Verschraubung kommen aber auch andere Verbindungsarten in Betracht. Beispielsweise kann der Haltering 16 auf das Wandlergehäuse 10 durch einen Presssitz aufpressbar sein. Durch die Formdichtung 14 in Verbindung mit der Gestaltung des Innenraums 11 des Wandlergehäuses 10 und mit dem Haltering 16 bedarf es keiner weiteren Einzelteile, um das Wandlerelement 1 im Wandlergehäuse 10 zu fixieren. Das bietet Vorteile hinsichtlich Herstellungs- und Montagekosten. Weitere Ausführungsformen liegen im Rahmen des handwerklichen Könnens eines Konstrukteurs.The interior 11 of the converter housing 10 advantageously has an annular step 15, on which the converter element 1 is supported via the molded seal 14. On the other hand, the transducer element 1 is held by a retaining ring 16, the molded seal 14 also being interposed here. there The retaining ring 16 can be screwed to the converter housing 10, which enables particularly simple assembly. Instead of the screw connection, other types of connection are also possible. For example, the retaining ring 16 can be pressed onto the converter housing 10 by a press fit. Due to the molded seal 14 in connection with the design of the interior 11 of the converter housing 10 and with the retaining ring 16, no further individual parts are required to fix the converter element 1 in the converter housing 10. This offers advantages in terms of manufacturing and assembly costs. Further embodiments lie within the framework of the technical skills of a designer.
Die erfindungsgemäße Lösung hat den Vorteil, dass der elektro-akustische Wirkungsgrad gegenüber dem bekannten Stand der Technik verbessert ist, weil eine das Wandlerelement 1 vor dem Medium schützende Membran oder ein das Wandlerelement 1 hermetisch abschließendes Gehäuse nicht erforderlich ist. Das gilt auch hinsichtlich der bei manchen dieser Lösungen vorhandenen Klebstoffschichten, auf die durch die Erfindung verzichtet werden kann. Die Ultraschallwellen dämpfende Wirkung von Klebstoffschicht und oder Gehäuse entfällt also. The solution according to the invention has the advantage that the electro-acoustic efficiency is improved compared to the known prior art because a membrane protecting the transducer element 1 from the medium or a housing hermetically sealing the transducer element 1 is not required. This also applies to the adhesive layers present in some of these solutions, which can be dispensed with by the invention. The ultrasonic wave damping effect of the adhesive layer and or housing is therefore eliminated.

Claims

Patentansprüche claims
1. Wandler für einen Ultraschall-Durchflussmesser, enthaltend ein in einem Wandlergehäuse (10) angeordnetes Wandlerelement (1) mit einer dem Medium zugewandten Frontelektrode (3) und einer Rückelektrode (4), die auf einer Keramikscheibe (2) aufgebracht sind, mit Mitteln, um das Wandlerelement (1) vor dem Angriff durch das Medium zu schützen, dadurch gekennzeichnet, dass auf der dem Medium zugewandten Frontelektrode (3) des Wandlerelements (1) eine Schutzschicht (5) aufgebracht ist, die aus einem Hartstoff besteht.1. Transducer for an ultrasonic flow meter, comprising a transducer element (1) arranged in a transducer housing (10) with a front electrode (3) facing the medium and a back electrode (4) which are applied to a ceramic disc (2) with means In order to protect the transducer element (1) from attack by the medium, characterized in that a protective layer (5) made of a hard material is applied to the front electrode (3) of the transducer element (1) facing the medium.
2. Wandler nach Anspruch 1, dadurch gekennzeichnet, dass der Hartstoff Titannitrid ist.2. Converter according to claim 1, characterized in that the hard material is titanium nitride.
3. Wandler nach Anspruch 2, dadurch gekennzeichnet, dass das Titannitrid eine sogenannte geschlossene Struktur aufweist.3. Converter according to claim 2, characterized in that the titanium nitride has a so-called closed structure.
4. Wandler nach Anspruch 3, dadurch gekennzeichnet, dass die Dicke der Schutzschicht (5) 1 bis 5 μm beträgt.4. Converter according to claim 3, characterized in that the thickness of the protective layer (5) is 1 to 5 microns.
5. Wandler nach Anspruch 4, dadurch gekennzeichnet, dass das Wandlerelement (1) an seiner Mantelfläche und an den äußeren Partien seiner Frontseite und Rückseite von einer Formdichtung (14) umgeben ist, wobei sich das Wandlerelement (1) über diese Formdichtung (14) einerseits an einer ringförmigen Stufe (15) im Innenraum des Wandlergehäuses (10) und andererseits an einem mit dem Wandlergehäuse (10) verbindbaren Haltering (16) abstützt. 5. Transducer according to claim 4, characterized in that the transducer element (1) on its outer surface and on the outer parts of its front and back is surrounded by a molded seal (14), the transducer element (1) via this molded seal (14) on the one hand on an annular step (15) in the interior of the converter housing (10) and on the other hand on a retaining ring (16) which can be connected to the converter housing (10).
PCT/EP2002/002020 2001-03-02 2002-02-26 Transducer for an ultrasonic flowmeter WO2002071002A1 (en)

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CH20010393/01 2001-03-02
CH3932001 2001-03-02

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Cited By (4)

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Publication number Priority date Publication date Assignee Title
US6652992B1 (en) * 2002-12-20 2003-11-25 Sulphco, Inc. Corrosion resistant ultrasonic horn
US7551520B2 (en) 2003-08-11 2009-06-23 Valeo Schalter Und Sensoren Gmbh Sensor for a short-range detection system and/or parking system of a motor vehicle and method for the production thereof
EP2602596A1 (en) * 2011-12-09 2013-06-12 Kamstrup A/S Ultrasonic flow meter on a PCB
WO2019214952A1 (en) * 2018-05-09 2019-11-14 Diehl Metering Gmbh Measuring device for determining a fluid variable

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US6652992B1 (en) * 2002-12-20 2003-11-25 Sulphco, Inc. Corrosion resistant ultrasonic horn
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US7551520B2 (en) 2003-08-11 2009-06-23 Valeo Schalter Und Sensoren Gmbh Sensor for a short-range detection system and/or parking system of a motor vehicle and method for the production thereof
EP2602596A1 (en) * 2011-12-09 2013-06-12 Kamstrup A/S Ultrasonic flow meter on a PCB
WO2019214952A1 (en) * 2018-05-09 2019-11-14 Diehl Metering Gmbh Measuring device for determining a fluid variable

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