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WO2008152058A1 - Capteur à ultrasons - Google Patents

Capteur à ultrasons Download PDF

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Publication number
WO2008152058A1
WO2008152058A1 PCT/EP2008/057293 EP2008057293W WO2008152058A1 WO 2008152058 A1 WO2008152058 A1 WO 2008152058A1 EP 2008057293 W EP2008057293 W EP 2008057293W WO 2008152058 A1 WO2008152058 A1 WO 2008152058A1
Authority
WO
WIPO (PCT)
Prior art keywords
layer
matching layer
coating method
layers
impedance
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.)
Ceased
Application number
PCT/EP2008/057293
Other languages
German (de)
English (en)
Inventor
Andreas Berger
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 WO2008152058A1 publication Critical patent/WO2008152058A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/02—Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators
    • 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
    • G01F1/666—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 by detecting noise and sounds generated by the flowing fluid
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/03—Assembling devices that include piezoelectric or electrostrictive parts

Definitions

  • the invention relates to an ultrasonic sensor with an im
  • Sound beam of the ultrasonic sensor arranged matching layer which is arranged between two layers of different materials or can be arranged, wherein it is a piezoelectric element in the first layer to which electrodes are mounted such that it emits ultrasonic measurement signals along the sound beam and receives.
  • Corresponding ultrasonic sensors are used in clamp-on or inline ultrasonic flowmeters, as offered by the applicant under the name PROSONIC FLOW in different configurations. Furthermore, ultrasonic sensors are used in the distance measurement.
  • Corresponding ultrasonic level gauges are offered and distributed by the ENDRESS + HAUSER group of companies.
  • the ultrasonic sensor according to the invention is preferably used in process automation, but also for example in medical technology.
  • Achieving ultrasonic waves through two adjacent materials with a relatively large impedance difference is advantageous for introducing an intermediate layer of material with an impedance between the two impedances Z1 and Z2. Maximized transmission can be achieved when the impedance of the spacer meets the following relationship.
  • a piezoceramic which is usually used in ultrasonic sensors as a transmitting and receiving element for the ultrasonic waves, an acoustic impedance, which is approximately in the range of about 30 MRayl. If ultrasonic sensors are used for measuring the flow of a medium in a pipeline, then a relatively high reflection component is to be expected, since water has an acoustic impedance of about 1.5 MRayl.
  • plastics such as those used for pipelines are also located in the same area. The acoustic impedance of plastics lies in the range between 1.5 ... 4 MRayl. For example, PVC has an acoustic impedance of 3 MRayl.
  • this impedance Z3 does not occur in conventional materials, materials are often used that have an impedance that are close to this optimum impedance.
  • glass with an impedance Z - 13 ... 15 MRayl or aluminum with an impedance Z ⁇ 17MRayl is used as the material for this so-called matching layer.
  • a further optimization of the signal strength is about the thickness of the Adjustment layer to achieve, since at a thickness which corresponds to the quarter of wavelength I, in addition, a very good transmission of the sound waves due to interference effects occurs.
  • a quarter-wave layer usually referred to by a quarter-wave layer.
  • the invention has for its object to propose an ultrasonic sensor with optimized transmission behavior.
  • the object is achieved in that the matching layer is applied to the piezoelectric element via a screen printing method, a powder coating method, a sputtering method, a CVD coating method, a PVD coating method, a spin coating method, or a galvanic coating method.
  • the advantage of the invention can best be explained by means of an example: If it is designed as a matching layer as a quarter-wave layer and consists of aluminum, it has in the MHz range in which the usual frequencies of the ultrasonic measurement signals are settled, a thickness which is less than 0.5 mm. At approx. 6 MHz, thicknesses of approx. 0.26 mm can be expected. Considering the strength of an adhesive bond provided in the prior art solutions between the piezoelectric element and the matching layer of aluminum, it can reach a thickness of 0.26 mm. The adhesive layer is very similar to plastic in terms of its transmission behavior. Consequently, at the interface: piezoelectric element - adhesive takes place an undesirable reflection.
  • the coating method according to the invention for example the screen printing method, it is possible to glasses, metals, ceramics, etc. thin layer in the range of a few hundredths of a millimeter to apply.
  • an aluminum layer with a thickness of eg 0.03 ... 0.06 mm can be applied directly to a glass layer or to a piezoelectric layer.
  • An advantage of the ultrasonic sensor according to the invention is the fact that it can be dispensed with the disturbing adhesive layer between the piezoelectric element and matching layer.
  • the relatively high temperature of about 600 ° C which is needed for curing of the pastes and which is above the Curie temperature about 350 °, does not cause the piezoelectric elements lose their piezoelectric properties, allowed with the matching layer directly coated piezoelectric elements are polarized only after printing.
  • the adjustment layer consists of several layers, which successively on the piezoelectric layer or on the previously by the screen printing method, the powder coating method, the sputtering method, the CVD coating method, the PVD coating method, the spin coating method or via the electroplating process applied layer of the matching layer are applied.
  • the matching layer if in the matching layer, a structure is introduced, which focuses the ultrasonic measurement signals.
  • the Matching layer introduced structure the shape of a concave lens or a Fresnel lens.
  • an advantageous embodiment of the device according to the invention provides that a potting or an adhesive is provided between the matching layer and the second layer.
  • the second layer is the wall of a pipeline through which a fluid medium flows.
  • the matching layer is preferably made of glass, ceramic, plastic, of a semiconductor material or of a metal. Furthermore, it is particularly advantageous if the matching layer has a thickness which corresponds essentially to a quarter wavelength or an odd integral multiple of the quarter wavelength of the ultrasonic measuring signals.
  • the advantage of this embodiment is to be seen in an optimization of the signal strength, since at a thickness which shows the aforementioned dimensions, a very good transmission due to interference effects arises. It should be noted, however, that this permeability is frequency-dependent.
  • Matching layer provides that the piezoelectric element has a first acoustic impedance, that the second layer has a second acoustic impedance and that the at least one matching layer has a third impedance, which - averaged at the operating frequency of the ultrasonic sensor - between the acoustic impedance of the piezoelectric element and the acoustic impedance of the second layer.
  • the coating method according to the invention it is possible via the coating method according to the invention to give the matching layer a desired structure.
  • the structure is created by stepwise covering or releasing corresponding areas when individual layers are applied in successive successive coating processes.
  • the structure by an erosive process, such as etching, laser or milling, in an adjustment layer is incorporated.
  • an advantageous embodiment of the ultrasonic sensor according to the invention provides that at least one adaptation layer consists of a mixture of different components. Furthermore, it is proposed that the materials of the different layers of the matching layer are chosen so that the impedances of the individual layers gradually approach the impedance of the second layer. This achieves a 'flowing' transition in the area of the sound beam. Also, alternate construction of high and low impedance layers is possible. In this case, the respective thickness of the layers is advantageously smaller than the smallest wavelength or smaller than VA of the wavelength.
  • the adaptation layer composed of a plurality of layers consists of different materials in selected regions, each layer, however, being constructed such that it forms a closed surface in each case.
  • FIG. 2 shows a schematic representation of an ultrasonic sensor mounted on a pipeline in a second embodiment
  • FIG. 3 shows a schematic representation of an ultrasonic sensor mounted on a pipeline in FIG a third embodiment.
  • Fig. 1 shows a schematic representation of a first embodiment of an ultrasonic sensor 1 according to the invention, which is mounted on the wall 6 of a pipeline.
  • the ultrasonic sensor 1 has - with regard to the impedances of the individual layers 3a, 3b - a matched piezoelectric element 2.
  • the immediately - ie without adhesive - applied to the piezoelectric element matching layer 3 is applied in two layers 3a, 3b.
  • the layers 3a, 3b also consist of the same material, if larger layer thicknesses are to be realized.
  • Screen printing process can be any thickness of the matching layer 3 realize. Furthermore, it is possible to bring a too thick matching layer 3 subsequently by a removal process to the desired thickness. As a result of the fact that the adaptation layer 3 or the individual layers 3a, 3b of the matching layer 3 are applied directly to the piezoelectric element 2, the interfering adhesive layer can be dispensed with an impedance which deviates greatly from the adjacent materials and significantly influences the sound beam.
  • the piezoelectric element 2 has an acoustic wave
  • Impedance of about 30 MRayl it may be in the first layer 3a of the matching layer 3 to an aluminum layer with an acoustic impedance of 17 MRayl and the second layer 3b to a glass layer with an acoustic impedance of 11 ... 17 MRayl , As already stated above, it is advantageous if both layers 3a, 3b each have a layer thickness d fl , d h which corresponds to a quarter wavelength or an odd integer multiple of a quarter wavelength.
  • the adhesive or the coupling layer 5 has an acoustic impedance of about 1.5 ... 4 MRayl.
  • the second layer or the wall 6 of the pipeline which also has an acoustic impedance of about 1.5 MRayl if it is made of plastic.
  • the impedance can be varied almost continuously from layer to layer over different materials with low impedance differences. This means a very good adaptation and thus little loss.
  • the ultrasonic sensor 1 according to the invention can be manufactured simply and inexpensively. Furthermore, the producibility is improved.
  • the adaptation layer 3 is composed here of four layers 3a, 3b, 3c, 3d; however, it can also be more layers.
  • a step-shaped structure 8 arranged radially and / or symmetrically about the central axis of the piezoelectric element 2 is introduced, which has the shape of a concave lens.
  • the staircase-shaped structure 8 has arisen by e.g. in the case of the screen printing method as a coating method, for each layer 3a, 3b, 3c, 3d a screen with correspondingly shaped and different masks is used.
  • the individual layers 3a, 3b, 3c, 3d can - as already stated - be made of the same material, e.g. made of aluminum with a speed of sound of 6,300 m / sec, or made of different materials.
  • a correspondingly thick matching layer 3 which in turn may consist of several layers 3a, 3b, 3c, 3d, subsequently introduce the structure 8 by a removal process. Suitable methods are all known methods of a mechanical or chemical nature.
  • the ultrasonic measurement signals are focused in the case shown in the region of the wall 6 of the pipeline.
  • the focus can be set by appropriate design of the structure 8 at any point in the sound beam.
  • a potting or an adhesive is provided which has, for example, a speed of sound of 2,500 m / sec. By choosing the materials, the focusing effect can also be shaped.
  • Embodiment of an ultrasonic sensor 1 mounted on a pipe differs from the embodiment shown in Fig. 2 only by the introduced into the matching layer 3 structure 9:
  • the structure 9 has the shape of a Fresnel lens. With this configuration can be at small thickness of the structured layer to achieve the desired focusing effect.
  • LIST OF REFERENCE NUMBERS Ultrasonic sensor piezoelectric element Adaptation layer a first layer b second layer c third layer d fourth layer e fifth layer a electrode b electrode potting / adhesive / coupling mat / grease wall of the pipeline / second layer acoustic beam structure structure

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
  • Transducers For Ultrasonic Waves (AREA)

Abstract

L'invention concerne un capteur à ultrasons (1) avec une couche d'adaptation (3) disposée dans le faisceau de son (7) du capteur à ultrasons (1), et disposée entre deux couches (2, 6) de matériaux différents. La première couche est un élément piézoélectrique (2) sur lequel sont posées des électrodes (4a, 4b) de telle sorte qu'il émet des signaux de mesure à ultrasons le long du faisceau de son (7). Pour optimiser la transmission des signaux de mesure à ultrasons, la couche d'adaptation (3) est posée par un procédé de sérigraphie, un procédé de revêtement par poudre, un procédé de pulvérisation, un procédé de revêtement par CVD, un procédé de revêtement par PVD ou par un procédé de revêtement galvanique.
PCT/EP2008/057293 2007-06-11 2008-06-11 Capteur à ultrasons Ceased WO2008152058A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102007027277A DE102007027277A1 (de) 2007-06-11 2007-06-11 Ultraschallsensor
DE102007027277.6 2007-06-11

Publications (1)

Publication Number Publication Date
WO2008152058A1 true WO2008152058A1 (fr) 2008-12-18

Family

ID=39764826

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2008/057293 Ceased WO2008152058A1 (fr) 2007-06-11 2008-06-11 Capteur à ultrasons

Country Status (2)

Country Link
DE (1) DE102007027277A1 (fr)
WO (1) WO2008152058A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20230134074A1 (en) * 2021-10-28 2023-05-04 Baker Hughes, A Ge Company, Llc Ultrasonic transducer for flow measurement

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102016115199B4 (de) 2016-08-16 2023-08-31 Endress+Hauser Flowtec Ag Ultraschallsensor zur Bestimmung oder Überwachung einer Prozessgröße eines Mediums in der Automatisierungstechnik

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4523122A (en) * 1983-03-17 1985-06-11 Matsushita Electric Industrial Co., Ltd. Piezoelectric ultrasonic transducers having acoustic impedance-matching layers
US4841977A (en) * 1987-05-26 1989-06-27 Inter Therapy, Inc. Ultra-thin acoustic transducer and balloon catheter using same in imaging array subassembly
EP1011028A2 (fr) * 1998-12-15 2000-06-21 Xerox Corporation Procédé pour fabriquer des structures à multiples niveaux en utilisant des couches d'arrêt de gravure enfouies
US6371915B1 (en) * 1999-11-02 2002-04-16 Scimed Life Systems, Inc. One-twelfth wavelength impedence matching transformer
EP1615203A1 (fr) * 2004-07-07 2006-01-11 Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno Ensemble de transducteurs à ultrasons

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3309236A1 (de) * 1983-03-15 1984-09-20 Siemens AG, 1000 Berlin und 8000 München Ultraschallwandler
JP2001149371A (ja) * 1999-11-25 2001-06-05 Aloka Co Ltd 超音波探触子
JP3445262B2 (ja) * 2001-11-22 2003-09-08 松下電器産業株式会社 圧電体の製造方法、圧電体、超音波探触子、超音波診断装置および非破壊検査装置
US7285897B2 (en) * 2003-12-31 2007-10-23 General Electric Company Curved micromachined ultrasonic transducer arrays and related methods of manufacture

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4523122A (en) * 1983-03-17 1985-06-11 Matsushita Electric Industrial Co., Ltd. Piezoelectric ultrasonic transducers having acoustic impedance-matching layers
US4841977A (en) * 1987-05-26 1989-06-27 Inter Therapy, Inc. Ultra-thin acoustic transducer and balloon catheter using same in imaging array subassembly
EP1011028A2 (fr) * 1998-12-15 2000-06-21 Xerox Corporation Procédé pour fabriquer des structures à multiples niveaux en utilisant des couches d'arrêt de gravure enfouies
US6371915B1 (en) * 1999-11-02 2002-04-16 Scimed Life Systems, Inc. One-twelfth wavelength impedence matching transformer
EP1615203A1 (fr) * 2004-07-07 2006-01-11 Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno Ensemble de transducteurs à ultrasons

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20230134074A1 (en) * 2021-10-28 2023-05-04 Baker Hughes, A Ge Company, Llc Ultrasonic transducer for flow measurement
US11806749B2 (en) * 2021-10-28 2023-11-07 Baker Hughes, A Ge Company, Llc Ultrasonic transducer for flow measurement

Also Published As

Publication number Publication date
DE102007027277A1 (de) 2008-12-18

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