EP0807924B1 - Sound or ultrasound transducer - Google Patents

Sound or ultrasound transducer Download PDF

Info

Publication number
EP0807924B1
EP0807924B1 EP97105884A EP97105884A EP0807924B1 EP 0807924 B1 EP0807924 B1 EP 0807924B1 EP 97105884 A EP97105884 A EP 97105884A EP 97105884 A EP97105884 A EP 97105884A EP 0807924 B1 EP0807924 B1 EP 0807924B1
Authority
EP
European Patent Office
Prior art keywords
sound
webs
diaphragms
ultrasonic sensor
excitation frequency
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.)
Expired - Lifetime
Application number
EP97105884A
Other languages
German (de)
French (fr)
Other versions
EP0807924A2 (en
EP0807924A3 (en
Inventor
Manfred Eckert
Karl Flögel
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 SE and Co KG
Original Assignee
Endress and Hauser SE and Co KG
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 SE and Co KG filed Critical Endress and Hauser SE and Co KG
Publication of EP0807924A2 publication Critical patent/EP0807924A2/en
Publication of EP0807924A3 publication Critical patent/EP0807924A3/en
Application granted granted Critical
Publication of EP0807924B1 publication Critical patent/EP0807924B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
    • B06B1/0607—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements
    • B06B1/0611—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements in a pile
    • B06B1/0618—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements in a pile of piezo- and non-piezoelectric elements, e.g. 'Tonpilz'
    • 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
    • G10K13/00—Cones, diaphragms, or the like, for emitting or receiving sound in general

Definitions

  • the invention relates to a sound or ultrasonic sensor for sending and / or receiving sound or ultrasound.
  • Ultrasonic sensors are e.g. as a transmitter and / or Receiver for distance measurement based on the sounder principle used, especially for measuring a level, e.g. in a container, or to measure a level, e.g. in a channel or on a conveyor belt.
  • a pulse sent by the sound or ultrasonic sensor is reflected on the surface of the product.
  • the Duration of the pulse from the sensor to the surface and back is determined and from this the fill level or the fill height certainly.
  • Such sound or ultrasonic sensors are used in many Industries, e.g. in the food industry, the Water and wastewater industry and in chemistry. Sound or ultrasonic sensors are particularly useful in chemistry of high chemical resistance required which can be used in a wide temperature range. In the food industry is also required to: such sensor preferably flush-mounted and therefore light are to be cleaned.
  • the sensors In all mentioned areas of application it is necessary that the sensors have a radiation characteristic with a small opening angle or a large main sound lobe and have low sonic lobes.
  • the sensor here comprises a conical, metallic one Radiating element and a basic body.
  • a converter element serves between the radiating element and the base body clamped piezoelectric element that too Thickness oscillations is excited.
  • the radiation characteristic of the sensor is essentially by the diameter of the front surface and the frequency certainly.
  • the sine of the opening angle behaves the emitted sound lobe like the quotient from the Wavelength of the emitted sound or ultrasound wave and the diameter of the front surface of the radiating element.
  • a large diameter must therefore be used.
  • the possible Size of the diameter is limited, however, that the Front surface above a certain diameter additionally executes bending vibrations.
  • the opening angle the sound lobe is therefore always of a minimum size.
  • a disadvantage of such a sound or ultrasonic sensor is that by using the elastomer matching layer the temperature range in which the sensor can be used, is restricted. For one, elastomers are only one lower temperature range can be used than metals, for others the speed of sound is strong in elastomers temperature dependent. Outside one by the elastomer The adaptation layer is thus a predetermined temperature range ineffective.
  • a metallic radiating element has one in comparison the matching layer higher mechanical resistance on and can be used in a wide temperature range.
  • the transducer element consists of two piezoelectric ones Elements through which the sensor causes axial vibrations is excited. With a suitable choice of This excites the membrane in resonance added.
  • the amplitude of the vibration of the membrane is at the center of the Maximum membrane and decreases towards the edge.
  • the diameter of the membrane is not arbitrary enlargeable because the membrane is given a given thickness and a given excitation frequency above a certain one Executes higher-order diameter bending waves. This can e.g. by using a stiffer membrane be avoided. Through a more rigid membrane, however the sensitivity of the sound or ultrasonic sensor greatly reduced on receipt.
  • the membrane has very high fatigue stresses exposed, it is required a very mechanical high quality material, e.g. Titanium. Such However, materials are expensive.
  • the invention consists of a sound or Ultrasonic sensor for sending and / or receiving sound or Ultrasound with a radiating element that is flat Has front surface, and with a transducer element, the Transducer element the front surface in such vibrations due to an excitation frequency that the entire Front surface almost in-phase deflections with almost equally large amplitude parallel to the surface normal of the Executes front surface, which is characterized in that concentric webs are arranged on the front surface, that between two adjacent webs concentric gap exists and that a disc, esp. made of metal, the sound or ultrasonic sensor flush with the front completes, which is firmly connected to the webs and the not connected to the webs, serving as membranes Has segments.
  • the Membranes bending vibrations, their resonance frequencies are greater than or equal to the excitation frequency.
  • the resonance frequency of the bending vibration of the middle circular membrane larger than or equal to the excitation frequency and the resonance frequencies of the remaining membranes 51 rise from the inside to the outside.
  • the resonance frequencies of the bending vibration of the membranes are identical and significantly larger than each other the excitation frequency and each membrane and each adjoining areas connected to the webs the disc 5 swing in phase.
  • the gaps have a depth that is minor is greater than a maximum deflection of the column final membranes.
  • Such Sound or ultrasonic sensor a smooth surface has and is therefore particularly easy to clean that he a metallic, chemically very stable and mechanically robust, radiation surface that he at Temperatures of up to 150 ° C can be used and that its Polar pattern is adjustable.
  • Fig. 1 is an embodiment of a Sound or ultrasonic sensor according to the invention for Sending and / or receiving sound or ultrasound shown.
  • This consists of a base body 2, one Radiating element 3 and one between the base body 2 and the radiating element 3 clamped cylindrical Transducer element 1.
  • the transducer element 1 leads Thick vibrations in the axial direction and thus stimulates the sound or ultrasonic sensor to axial vibrations.
  • the transducer element 1 consists of two annular disk-shaped piezoelectric elements 1a, 1b which are arranged one on top of the other and have an opposite polarization in the axial direction, symbolically represented by arrows. Between the two piezoelectric elements 1a, 1b, an annular disk-shaped electrode 11 common to both elements 1a, 1b is arranged. On the side facing away from the common electrode 11, each element 1a, 1b has a further counter-electrode 12a, 12b, likewise in the form of an annular disk.
  • the electrode 11 and the two counter electrodes 12a, 12b are connected to an AC voltage source, also not shown, via connecting lines, not shown.
  • the counter electrodes 12a are, 12b at the same potential U 1 and the electrode 11 on a relative to the potential U 1 180 ° phase-shifted potential U. 2
  • the transducer element 1 thus constructed has two circular ones End faces 13 and 14. Bordering on the end face 13 the base body 2. This is a cylinder with one central, axial, continuous inner bore 21.
  • the Base body 2 consists of a material of high density, for. B. made of steel and causes a reduction in emitted in the opposite direction Sound energy.
  • the radiating element 3 adjoins the end face 14. This is a truncated cone-shaped component, e.g. out Aluminum.
  • the circular surface of the truncated cone that the has a larger diameter, is from the transducer element 1 turned away and forms a flat front surface 34.
  • Das Radiating element 3 points towards the transducer element Side a central axial bore 31 with a Internal thread 311, which is a bit in axial Extends into the truncated cone.
  • a clamping device 4 is provided, through which the transducer element 1 in the axial direction, that is perpendicular to its end faces 13, 14, between the base body 2 and the radiating element 3 is clamped.
  • the embodiment is the jig 4 Clamping bolt from the side facing away from the converter element forth into the central inner bore 4 of the base body 2 is introduced, the transducer element 1 completely penetrates and into the internal thread 311 of the bore 31 of the Radiating element 3 is screwed so that Transducer element 1 is biased.
  • Concentric annular webs 32 are arranged on a front surface of the radiation element 3 facing away from the converter element. There is an annular disk-shaped gap 33 between each two adjacent webs 32.
  • This special geometry is produced, for example, by turning the annular disk-shaped gaps 32 out of an initially frustoconical radiating element 3. Since the radiating element 3 preferably consists of a metal, in particular aluminum, this is a very inexpensive and simple manufacturing process.
  • the sound or ultrasonic sensor is flush with the front closed by a preferably metallic disc 5, e.g. Made of aluminum or stainless steel, which are firmly attached to the Web 32 connected, esp. Is welded.
  • the Exposed segments of the disc 5 thus form a circular or annular disk-shaped membranes 51 on the edge due to the non-positive connection with the webs 32 are clamped.
  • the sound or ultrasonic sensor is, for example, in a, not shown in Fig. 1, cylindrical arranged at one end open housing, the between the housing and the sound or ultrasonic sensor existing cavities with an electrically non-conductive Are filled with elastomer.
  • the flat front surface 34 of the radiation element 3 is thus by the excitation frequency of the AC voltage in such a way Vibrations offset that the entire front surface 34 almost in-phase deflections with almost the same size Amplitude parallel to the surface normal on the front surface 34 executes.
  • the converter element 1 preferably driven with an excitation frequency that corresponds to the resonance frequency of the compound transducer.
  • the Length L of the compound transducer in the axial direction corresponds to an integer multiple of half Wavelength to that by weighted averaging determining fictitious wavelength that sound or Ultrasound of the excitation frequency in the composite oscillator having.
  • This vibration is mediated by the webs 32 on the Membranes 51 transferred.
  • the membranes 51 lead because they on Bending vibrations are firmly connected to the webs 32 at the edge out. Due to these bending vibrations there is one good adaptation of the ultrasonic sensor to air.
  • There is an increase in amplitude, i.e. the Vibration amplitude of the membranes 51 is larger than that the webs 32.
  • the amplitude increase is maximum if the excitation frequency with the resonance frequency of the respective membrane 51 matches.
  • the deflection of the respective membrane 51 is that of them adjacent webs 32 opposite.
  • the resonance frequency of the respective membrane 51 is decisive by their mean radius and their Stiffness determined. With equidistant spacing webs of the same width in the radial direction would be the Resonance frequency of the outer membranes 51 consequently lower than that of the inner ones. By reducing the Distance between two adjacent webs 32 in a radial Direction increases the resonance frequency between the Web 51 arranged webs.
  • the resonance frequency of all membranes 51 is preferably above the excitation frequency. This will make the appearance excluded from higher order bending waves.
  • the radiation pattern of the sound or Ultrasonic sensor is characterized by the distances between the Web 32 in the radial direction, that is, by the vote the resonance frequencies of the bending vibrations of the individual Membranes 51 on top of each other and on the drive frequency, adjustable. The following are two examples of this specified.
  • a sound or ultrasonic sensor with a suitable for distance measurement according to the sonar principle Radiation characteristics achieved by the dimensions so be set that the resonant frequency of the circular middle membrane 51 equal to or larger than that Drive frequency is and the resonance frequencies of the others annular disk-shaped membranes 51 are matched so that a membrane 51 with a smaller outer radius has a lower resonance frequency than a membrane 51 with a larger outer radius.
  • the circular middle Membrane 51 has the lowest resonance frequency.
  • the increase in amplitude and thus the radiated Sound energy thus takes along the pane 5 from the inside to the outside.
  • the amplitude distribution along one Diagonals of the disc 5 approximately corresponds to one Gaussian curve.
  • the sound energy emitted by side lobes is considerably lower than with a pure piston oscillator without webs 32 and without washer 5.
  • the radiation is almost in phase achieved all areas of the disc 5 by the Resonance frequencies of the membranes 51 all the same and clearly, e.g. 10%, are greater than the excitation frequency. Then there is almost no phase shift between the Vibration of the individual membranes 51 and to them adjacent with the respective adjacent webs 32 connected areas of the disc 5.
  • transducer element 1 does not reverberate.
  • the distance between the membranes 51 and Front surface 34 of the radiating element 3, that is the depth of the Column 33, preferably dimensioned so that it is slight is greater than the maximum deflection of column 33 final membranes 51.
  • the compression of the in the Columns 33 contained air due to the bending vibrations of the Membranes 51 cause damping through which the Ringing of the senor is significantly reduced.
  • a reduction in reverberation is also achieved by placing a damping material 6, e.g. on Foam, is introduced.
  • a damping material 6 e.g. on Foam
  • Such a foam can For example, be glued to the radiation element 3. Esp. is the formation of a ring in the columns 33 revolving waves through the damping material 6 locked out.
  • the sound or ultrasonic sensor is through the preferably metallic disc 5 completed. So that is it can be used at high temperatures up to approx. 150 ° C.
  • the Temperature range is only by the temperature range restricted, in which the converter element 1 can be used. By extending the distance between the Transducer element 1 and disc 5 are even larger Temperature ranges attainable. It should be noted here that the length L of the compound transducer in the axial direction integer multiples of half a wavelength, of those to be determined by weighted averaging fictional wavelength, the sound or ultrasound of the Has excitation frequency in the composite oscillator, equivalent.
  • the webs 32 and the disk 5 preferably made of metal occur only small temperature-related frequency deviations.
  • the sound or ultrasonic sensor is very chemical resistant and mechanically very robust. It is suitable particularly good for applications in the food industry, because the medium-touched disc 5 is flat and therefore good to is clean.
  • the invention is not for use in the described sensor is limited, but is rather at all sound or ultrasonic sensors can be used, the one Have radiating element with a flat front surface, the through the converter element 1 due to an excitation frequency is vibrated such that the entire Front surface almost in-phase deflections with almost equally large amplitude parallel to the surface normal of the Execute the front surface.
  • Fig. 2 shows a further embodiment for one such sound or ultrasonic sensor.
  • Transducer element 1 is only a single disk-shaped one piezoelectric element. With this converter element 1 is also a disk-shaped cover plate 7 same diameter firmly connected.
  • the cover plate 7 is as well as the radiation element 3 of the one in FIG. 1 illustrated embodiment to vibrations such stimulated that their entire circular transducer-facing Front surface almost in-phase deflections with almost equally large amplitude parallel to the surface normal of the Front surface.
  • the sound or ultrasonic sensor is, for example, in a, not shown in Fig. 2, cylindrical arranged at one end open housing, the between the housing and the sound or ultrasonic sensor existing cavities with an electrically non-conductive Are filled with elastomer.
  • FIG. 2 offers compared to that in Fig. 1 illustrated embodiment the advantage that it has a very low height and that a single piezoelectric element is sufficient to the sound or To stimulate ultrasonic transducers.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Mechanical Engineering (AREA)
  • Transducers For Ultrasonic Waves (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
  • Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
  • Thermotherapy And Cooling Therapy Devices (AREA)
  • Ultra Sonic Daignosis Equipment (AREA)

Description

Die Erfindung betrifft einen Schall- oder Ultraschallsensor zum Senden und/oder Empfangen von Schall- oder Ultraschall. Ultraschallsensoren werden z.B. als Sender und/oder Empfänger zur Entfernungsmessung nach dem Echolotprinzip verwendet, insb. zur Messung eines Füllstands, z.B. in einem Behälter, oder zur Messung einer Füllhöhe, z.B. in einem Gerinne oder auf einem Förderband.The invention relates to a sound or ultrasonic sensor for sending and / or receiving sound or ultrasound. Ultrasonic sensors are e.g. as a transmitter and / or Receiver for distance measurement based on the sounder principle used, especially for measuring a level, e.g. in a container, or to measure a level, e.g. in a channel or on a conveyor belt.

Ein vom Schall- oder Ultraschallsensor ausgesendeter Impuls wird an der Oberfläche des Füllgutes reflektiert. Die Laufzeit des Impulses vom Sensor zur Oberfläche und zurück wird ermittelt und daraus der Füllstand bzw. die Füllhöhe bestimmt.A pulse sent by the sound or ultrasonic sensor is reflected on the surface of the product. The Duration of the pulse from the sensor to the surface and back is determined and from this the fill level or the fill height certainly.

Derartige Schall- oder Ultraschallsensoren werden in vielen Industriezweigen, z.B. in der Lebensmittelindustrie, der Wasser- und Abwasserbranche und in der Chemie, eingesetzt. Besonders in der Chemie sind Schall- oder Ultraschallsensoren von hoher chemischer Beständigkeit erforderlich, die in einem weiten Temperaturbereich einsetzbar sind. In der Lebensmittelindustrie wird zusätzlich gefordert, das derartige Sensor vorzugsweise frontbündig und somit leicht zu reinigen sind.Such sound or ultrasonic sensors are used in many Industries, e.g. in the food industry, the Water and wastewater industry and in chemistry. Sound or ultrasonic sensors are particularly useful in chemistry of high chemical resistance required which can be used in a wide temperature range. In the food industry is also required to: such sensor preferably flush-mounted and therefore light are to be cleaned.

In allen genannten Anwendungsbereichen ist es erforderlich, daß die Sensoren eine Abstrahlcharakteristik mit einem geringen Öffnungswinkel bzw. einer großen Hauptschallkeule und geringen Nebenschallkeulen aufweisen.In all mentioned areas of application it is necessary that the sensors have a radiation characteristic with a small opening angle or a large main sound lobe and have low sonic lobes.

In der DE-OS 29 06 704 ist ein Schall- oder Ultraschallsensor zum Senden und/oder Empfangen von Schall- oder Ultraschall beschrieben mit

  • einem Abstrahlelement mit einer ebenen Frontfläche und
  • einem Sensorelement,
  • bei dem das Sensorelement die Frontfläche derart in Schwingungen versetzt, daß die gesamte Frontfläche nahezu gleichphasige Auslenkungen mit nahezu gleichgroßer Amplitude parallel zur Flächennormalen der Frontfläche ausführt.
DE-OS 29 06 704 describes a sound or ultrasonic sensor for transmitting and / or receiving sound or ultrasound
  • a radiating element with a flat front surface and
  • a sensor element,
  • in which the sensor element vibrates the front surface in such a way that the entire front surface executes almost in-phase deflections with an almost equally large amplitude parallel to the surface normal of the front surface.

Der Sensor umfaßt hier ein kegelförmiges, metallisches Abstrahlelement und einen Grundkörper. Als Wandlerelement dient ein zwischen Abstrahlelement und Grundkörper eingespanntes piezoelektrisches Element, das zu Dickenoszillationen angeregt wird.The sensor here comprises a conical, metallic one Radiating element and a basic body. As a converter element serves between the radiating element and the base body clamped piezoelectric element that too Thickness oscillations is excited.

Die Abstrahlcharakteristik des Sensor ist im wesentlichen durch den Durchmesser der Frontfläche und die Frequenz bestimmt. Dabei verhält sich der Sinus des Öffnungswinkels der abgestrahlten Schallkeule wie der Quotient aus der Wellenlänge der abgestrahlten Schall- oder Ultraschallwelle und dem Durchmesser der Frontfläche des Abstrahlelements. Um eine Schallkeule mit kleinem Öffnungswinkel zu erhalten, ist daher ein großer Durchmesser zu verwenden. Die mögliche Größe des Durchmessers ist jedoch dadurch begrenzt, daß die Frontfläche oberhalb eines bestimmten Durchmessers zusätzlich Biegeschwingungen ausführt. Der Öffnungswinkel der Schallkeule weist folglich immer eine Mindestgröße auf.The radiation characteristic of the sensor is essentially by the diameter of the front surface and the frequency certainly. The sine of the opening angle behaves the emitted sound lobe like the quotient from the Wavelength of the emitted sound or ultrasound wave and the diameter of the front surface of the radiating element. To get a sound beam with a small opening angle, a large diameter must therefore be used. The possible Size of the diameter is limited, however, that the Front surface above a certain diameter additionally executes bending vibrations. The opening angle the sound lobe is therefore always of a minimum size.

Da sich die akustische Impedanz des Mediums, in das der Schall oder Ultraschall auszusenden ist, z.B. Luft, und die des Abstrahlelements sehr stark unterscheiden, ist vor dem Abstrahlelement eine Anpaßschicht aus einem Elastomer angeordnet.Since the acoustic impedance of the medium in which the Sound or ultrasound is to be emitted, e.g. Air, and the of the radiating element is very different, is before Radiating element a matching layer made of an elastomer arranged.

Ein Nachteil eines solchen Schall- oder Ultraschallsensors ist, daß durch die Verwendung der Elastomer-Anpaßschicht der Temperaturbereich, in dem der Sensor einsetzbar ist, eingeschränkt wird. Zum einen sind Elastomere nur in einem geringeren Temperaturbereich einsetzbar als Metalle, zum anderen ist die Schallgeschwindigkeit in Elastomeren stark temperaturabhängig. Außerhalb eines durch das Elastomer vorgegebenen Temperaturbereichs ist die Anpaßschicht somit unwirksam.A disadvantage of such a sound or ultrasonic sensor is that by using the elastomer matching layer the temperature range in which the sensor can be used, is restricted. For one, elastomers are only one lower temperature range can be used than metals, for others the speed of sound is strong in elastomers temperature dependent. Outside one by the elastomer The adaptation layer is thus a predetermined temperature range ineffective.

Ferner ist in der Zeitschrift Technisches Messen, 51. Jahrgang, 1984, Heft 9 auf den Seiten 313 bis 317, insb. S. 314, veröffentlichten Fachartikel mit dem Titel: 'Meßwertverarbeitung in Ultraschall-Füllstandsmeßgeräten' ein Hochleistungs-Schallsensor beschrieben, der umfaßt:

  • zwei Metallzylinder,
  • ein zwischen den Metallzylindern eingespanntes Wandlerelement und
  • einen auf einen der Metallzylinder aufgeschraubten, als Membran ausbebildeten Deckel aus Titan.
Furthermore, in the journal Technisches Messen, 51st year, 1984, volume 9 on pages 313 to 317, esp. P. 314, published technical articles with the title: 'Messwertverarbeitung in Ultrasonic-Füllstandsmeßgeräte' describes a high-performance sound sensor which includes :
  • two metal cylinders,
  • a transducer element clamped between the metal cylinders and
  • a screwed onto one of the metal cylinders, designed as a membrane made of titanium.

Ein metallisches Abstrahlelement weist eine im Vergleich zu der Anpaßschicht höhere mechanische Beständigkeit auf und ist in einem größeren Temperaturbereich einsetzbar.A metallic radiating element has one in comparison the matching layer higher mechanical resistance on and can be used in a wide temperature range.

Das Wandlerelement besteht aus zwei piezoelektrischen Elementen, durch die der Sensor zu Axialschwingungen angeregt wird. Bei einer geeigneten Wahl der Anregungsfrequenz wird die Membran dadurch in Resonanz versetzt.The transducer element consists of two piezoelectric ones Elements through which the sensor causes axial vibrations is excited. With a suitable choice of This excites the membrane in resonance added.

Die Amplitude der Schwingung der Membran ist im Zentrum der Membran maximal und nimmt zu deren Rand hin ab. The amplitude of the vibration of the membrane is at the center of the Maximum membrane and decreases towards the edge.

Der Durchmesser der Membran ist jedoch nicht beliebig vergrößerbar, da die Membran bei einer gegebenen Dicke und einer gegebenen Anregungsfrequenz oberhalb eines bestimmten Durchmessers Biegewellen höherer Ordnung ausführt. Dies kann z.B. durch die Verwendung einer steiferen Membran vermieden werden. Durch eine steifere Membran wird jedoch die Empfindlichkeit des Schall- oder Ultraschallsensors beim Empfang stark reduziert.However, the diameter of the membrane is not arbitrary enlargeable because the membrane is given a given thickness and a given excitation frequency above a certain one Executes higher-order diameter bending waves. This can e.g. by using a stiffer membrane be avoided. Through a more rigid membrane, however the sensitivity of the sound or ultrasonic sensor greatly reduced on receipt.

Da die Membran sehr hohen Dauerwechselbeanspruchungen ausgesetzt ist, ist es erforderlich, einen mechanisch sehr hochwertigen Werkstoff, z.B. Titan, zu verwenden. Solche Materialien sind jedoch teuer.Because the membrane has very high fatigue stresses exposed, it is required a very mechanical high quality material, e.g. Titanium. Such However, materials are expensive.

Es ist eine Aufgabe der Erfindung, einen Schall- oder Ultraschallsensor anzugeben, der mechanisch robust und chemisch beständig ist und der eine einstellbare Abstrahlcharakteristik, z.B. mit einem vorzugsweise geringen Öffnungswinkel, aufweist.It is an object of the invention to provide a sound or Specify ultrasonic sensor that is mechanically robust and is chemically resistant and the one adjustable Radiation characteristics, e.g. with one preferably has a small opening angle.

Hierzu besteht die Erfindung in einem Schall- oder Ultraschallsensor zum Senden und/oder Empfangen von Schalloder Ultraschall mit einem Abstrahlelement, das eine ebene Frontfläche hat, und mit einem Wandlerelement, wobei das Wandlerelement die Frontfläche derart in Schwingungen aufgrund einer Anregungsfrequenz versetzt, daß die gesamte Frontfläche nahezu gleichphasige Auslenkungen mit nahezu gleichgroßer Amplitude parallel zur Flächennormalen der Frontfläche ausführt, der dadurch gekennzeichnet ist, daß auf der Frontfläche konzentrische Stege angeordnet sind, daß zwischen zwei benachbarten Stegen jeweils ein konzentrischer Spalt besteht und daß eine Scheibe, insb. aus Metall, den Schall- oder Ultraschallsensor frontbündig abschließt, die fest mit den Stegen verbunden ist und die nicht mit den Stegen verbundene, als Membranen dienende Segmente aufweist. For this purpose, the invention consists of a sound or Ultrasonic sensor for sending and / or receiving sound or Ultrasound with a radiating element that is flat Has front surface, and with a transducer element, the Transducer element the front surface in such vibrations due to an excitation frequency that the entire Front surface almost in-phase deflections with almost equally large amplitude parallel to the surface normal of the Executes front surface, which is characterized in that concentric webs are arranged on the front surface, that between two adjacent webs concentric gap exists and that a disc, esp. made of metal, the sound or ultrasonic sensor flush with the front completes, which is firmly connected to the webs and the not connected to the webs, serving as membranes Has segments.

Gemäß einer Ausgestaltung der Erfindung führen die Membranen Biegeschwingungen aus, deren Resonanzfrequenzen größer oder gleich der Anregungsfrequenz sind.According to one embodiment of the invention, the Membranes bending vibrations, their resonance frequencies are greater than or equal to the excitation frequency.

Gemäß einer weiteren vorteilhaften Ausgestaltung der Erfindung ist die Resonanzfrequenz der Biegeschwingung der mittleren kreisförmigen Membran größer als die oder gleich der Anregungsfrequenz und die Resonanzfrequenzen der übrigen Membranen 51 steigen von innen nach außen an.According to a further advantageous embodiment of the Invention is the resonance frequency of the bending vibration of the middle circular membrane larger than or equal to the excitation frequency and the resonance frequencies of the remaining membranes 51 rise from the inside to the outside.

Gemäß einer anderen vorteilhaften Ausgestaltung der Erfindung sind die Resonanzfrequenzen der Biegeschwingung der Membranen untereinander gleich und deutlich größer als die Anregungsfrequenz und jede Membran und die jeweils daran anschließenden mit den Stegen verbundenen Bereiche der Scheibe 5 schwingen gleichphasig.According to another advantageous embodiment of the Invention are the resonance frequencies of the bending vibration of the membranes are identical and significantly larger than each other the excitation frequency and each membrane and each adjoining areas connected to the webs the disc 5 swing in phase.

Gemäß einer weiteren vorteilhaften Ausgestaltung der Erfindung ist in die Spalte ein Dämpfungsmaterial, insb. ein Schaumstoff, eingebracht.According to a further advantageous embodiment of the Invention in the column is a damping material, esp. a foam, introduced.

Gemäß einer weiteren vorteilhaften Ausgestaltung der Erfindung weisen die Spalte eine Tiefe auf, die geringfügig größer ist als eine maximale Auslenkung der die Spalte abschließenden Membranen.According to a further advantageous embodiment of the Invention, the gaps have a depth that is minor is greater than a maximum deflection of the column final membranes.

Vorteile der Erfindung bestehen darin, daß ein solcher Schall- oder Ultraschallsensor eine glatte Oberfläche aufweist und somit besonders leicht zu reinigen ist, daß er eine metallische, also chemisch sehr beständige und mechanisch robuste, Abstrahlfläche aufweist, daß er bei Temperaturen von bis zu 150 °C einsetzbar ist und daß seine Richtcharakteristik einstellbar ist.Advantages of the invention are that such Sound or ultrasonic sensor a smooth surface has and is therefore particularly easy to clean that he a metallic, chemically very stable and mechanically robust, radiation surface that he at Temperatures of up to 150 ° C can be used and that its Polar pattern is adjustable.

Die Erfindung und weitere Vorteile werden nun anhand der Figuren der Zeichnung, in denen zwei Ausführungsbeispiele dargestellt sind, näher erläutert; gleiche Elemente sind in den Figuren mit gleichen Bezugszeichen versehen.

Fig. 1
zeigt einen Längsschnitt durch einen ersten Schall- oder Ultraschallsensor, und
Fig. 2
zeigt einen Längsschnitt durch einen zweiten Schall- oder Ultraschallsensor.
The invention and further advantages will now be explained in more detail with reference to the figures of the drawing, in which two exemplary embodiments are shown; Identical elements are provided with the same reference symbols in the figures.
Fig. 1
shows a longitudinal section through a first sound or ultrasonic sensor, and
Fig. 2
shows a longitudinal section through a second sound or ultrasonic sensor.

In Fig. 1 ist ein Ausführungsbeispiel eines erfindungsgemäßen Schall- oder Ultraschallsensors zum Senden und/oder Empfangen von Schall oder Ultraschall dargestellt. Dieser besteht aus einem Grundkörper 2, einem Abstrahlelement 3 und einem zwischen dem Grundkörper 2 und dem Abstrahlelement 3 eingespannten zylindrischen Wandlerelement 1. Das Wandlerelement 1 führt Dickenschwingungen in axialer Richtung aus und regt damit den Schall- oder Ultraschallsensor zu Axialschwingungen an.In Fig. 1 is an embodiment of a Sound or ultrasonic sensor according to the invention for Sending and / or receiving sound or ultrasound shown. This consists of a base body 2, one Radiating element 3 and one between the base body 2 and the radiating element 3 clamped cylindrical Transducer element 1. The transducer element 1 leads Thick vibrations in the axial direction and thus stimulates the sound or ultrasonic sensor to axial vibrations.

In dem in Fig. 1 dargestellten Ausführungsbeispiel besteht das Wandlerelement 1 aus zwei aufeinander angeordneten, ringscheibenförmigen piezoelektrischen Elementen 1a, 1b, die eine zueinander entgegengesetzte, durch Pfeile symbolisch dargestellte, Polarisation in axialer Richtung aufweisen. Zwischen den beiden piezoelektrischen Elementen 1a, 1b ist eine beiden Elementen 1a, 1b gemeinsame ringscheibenförmige Elektrode 11 angeordnet. Auf der der gemeinsamen Elektrode 11 abgewandten Seite weist jedes Element 1a, 1b eine weitere ebenfalls ringscheibenförmige Gegenelektrode 12a, 12b auf. Die Elektrode 11 und die beiden Gegenelektroden 12a, 12b sind über nicht dargestellte Verbindungsleitungen mit einer ebenfalls nicht dargestellten Wechselspannungsquelle verbunden. Dabei liegen die Gegenelektroden 12a, 12b auf gleichem Potential U1 und die Elektrode 11 auf einem gegenüber dem Potential U1 um 180° Phasenverschobenen Potential U2. In the exemplary embodiment shown in FIG. 1, the transducer element 1 consists of two annular disk-shaped piezoelectric elements 1a, 1b which are arranged one on top of the other and have an opposite polarization in the axial direction, symbolically represented by arrows. Between the two piezoelectric elements 1a, 1b, an annular disk-shaped electrode 11 common to both elements 1a, 1b is arranged. On the side facing away from the common electrode 11, each element 1a, 1b has a further counter-electrode 12a, 12b, likewise in the form of an annular disk. The electrode 11 and the two counter electrodes 12a, 12b are connected to an AC voltage source, also not shown, via connecting lines, not shown. Here, the counter electrodes 12a are, 12b at the same potential U 1 and the electrode 11 on a relative to the potential U 1 180 ° phase-shifted potential U. 2

Das so aufgebaute Wandlerelement 1 weist zwei kreisförmige Stirnflächen 13 und 14 auf. An die Stirnfläche 13 grenzt der Grundkörper 2 an. Dies ist ein Zylinder mit einer zentralen, axialen, durchgehenden Innenbohrung 21. Der Grundkörper 2 besteht aus einem Material hoher Dichte,z. B. aus Stahl und bewirkt eine Reduktion der in abstrahlelement-abgewandter Richtung abgestrahlten Schallenergie.The transducer element 1 thus constructed has two circular ones End faces 13 and 14. Bordering on the end face 13 the base body 2. This is a cylinder with one central, axial, continuous inner bore 21. The Base body 2 consists of a material of high density, for. B. made of steel and causes a reduction in emitted in the opposite direction Sound energy.

An die Stirnfläche 14 grenzt das Abstrahlelement 3 an. Dies ist ein kegelstumpf-förmiges Bauelement, z.B. aus Aluminium. Diejenige Kreisfläche des Kegelstumpfs, die den größeren Durchmesser aufweist, ist vom Wandlerelement 1 abgewandt und bildet eine ebene Frontfläche 34. Das Abstrahlelement 3 weist auf der wandlerelement-zugewandten Seite eine zentrale axiale Bohrung 31 mit einem Innengewinde 311 auf, die sich ein Stück weit in axialer Richtung in den Kegelstumpf hinein erstreckt.The radiating element 3 adjoins the end face 14. This is a truncated cone-shaped component, e.g. out Aluminum. The circular surface of the truncated cone that the has a larger diameter, is from the transducer element 1 turned away and forms a flat front surface 34. Das Radiating element 3 points towards the transducer element Side a central axial bore 31 with a Internal thread 311, which is a bit in axial Extends into the truncated cone.

Es ist eine Einspannvorrichtung 4 vorgesehen, durch die das Wandlerelement 1 in axialer Richtung, also senkrecht zu seinen Stirnflächen 13, 14, zwischen dem Grundkörper 2 und dem Abstrahlelement 3 eingespannt ist. In diesem Ausführungsbeispiel ist die Einspannvorrichtung 4 ein Spannbolzen, der von der wandlerelement-abgewandten Seite her in die zentrale Innenbohrung 4 des Grundkörpers 2 eingeführt ist, das Wandlerelement 1 vollständig durchdringt und in das Innengewinde 311 der Bohrung 31 des Abstrahlelements 3 eingeschraubt ist, so daß das Wandlerelement 1 vorgespannt ist.A clamping device 4 is provided, through which the transducer element 1 in the axial direction, that is perpendicular to its end faces 13, 14, between the base body 2 and the radiating element 3 is clamped. In this The embodiment is the jig 4 Clamping bolt from the side facing away from the converter element forth into the central inner bore 4 of the base body 2 is introduced, the transducer element 1 completely penetrates and into the internal thread 311 of the bore 31 of the Radiating element 3 is screwed so that Transducer element 1 is biased.

Auf einer wandlerelement-abgewandten Frontfläche des Abstrahlelements 3 sind konzentrische ringförmige Stege 32 angeordnet. Zwischen zwei benachbarten Stegen 32 besteht jeweils ein ringscheibenförmiger Spalt 33.
Hergestellt wird diese spezielle Geometrie z.B. indem die ringscheibenförmigen Spalte 32 aus einem zunächst kegelstumpfförmigen Abstrahlelement 3 herausgedreht werden. Da das Abstrahlelement 3 vorzugsweise aus einem Metall, insb. Aluminium besteht, ist dies ein sehr kostengünstiges und einfaches Herstellverfahren.Concentric annular webs 32 are arranged on a front surface of the radiation element 3 facing away from the converter element. There is an annular disk-shaped gap 33 between each two adjacent webs 32.
This special geometry is produced, for example, by turning the annular disk-shaped gaps 32 out of an initially frustoconical radiating element 3. Since the radiating element 3 preferably consists of a metal, in particular aluminum, this is a very inexpensive and simple manufacturing process.

Der Schall- oder Ultraschallsensor ist frontbündig abgeschlossen durch eine vorzugsweise metallische Scheibe 5, z.B. aus Aluminium oder Edelstahl, die fest mit den Stegen 32 verbunden, insb. verschweißt ist. Die freiliegenden Segmente der Scheibe 5 bilden somit kreis-bzw. ringscheibenförmige Membranen 51, die an deren Rand durch die kraftschlüssige Verbindung mit den Stegen 32 fest eingespannt sind.The sound or ultrasonic sensor is flush with the front closed by a preferably metallic disc 5, e.g. Made of aluminum or stainless steel, which are firmly attached to the Web 32 connected, esp. Is welded. The Exposed segments of the disc 5 thus form a circular or annular disk-shaped membranes 51 on the edge due to the non-positive connection with the webs 32 are clamped.

Der Schall- oder Ultraschallsensor ist beispielsweise in einem, in Fig. 1 nicht dargestellten, zylindrischen an einem Ende offenen Gehäuse angeordnet, wobei die zwischen dem Gehäuse und dem Schall- oder Ultraschallsensor bestehenden Hohlräume mit einem elektrisch nichtleitenden Elastomer ausgefüllt sind.The sound or ultrasonic sensor is, for example, in a, not shown in Fig. 1, cylindrical arranged at one end open housing, the between the housing and the sound or ultrasonic sensor existing cavities with an electrically non-conductive Are filled with elastomer.

Im Sendeberieb werden die piezoelektrischen Elemente 1a, 1b durch die an die Elektrode 11 und die Gegenelektroden 12a, 12b anzulegenden Wechselspannung in Dickenschwingungen versetzt. Da das Wandlerelement 1 über die Einspannvorrichtung 4 fest mit dem Grundkörper 2 und dem Abstrahlelement 3 verbunden ist, führt der aus Wandlerelement 1, Grundkörper 2 und Abstrahlelement 3 gebildete Verbundschwinger Axialschwingungen aus.The piezoelectric elements 1a, 1b through the electrodes 11 and the counter electrodes 12a, 12b AC voltage to be applied in thickness vibrations added. Since the transducer element 1 over the Jig 4 fixed to the base body 2 and Radiating element 3 is connected to the Transducer element 1, base body 2 and radiation element 3 formed composite vibrators axial vibrations.

Die ebene Frontfläche 34 des Abstrahlelements 3 wird somit durch die Anregungsfrequenz der Wechselspannung derart in Schwingungen versetzt, daß die gesamte Frontläche 34 nahezu phasengleiche Auslenkungen mit nahezu gleichgroßer Amplitude parallel zur Flächennormalen auf die Frontfläche 34 ausführt. The flat front surface 34 of the radiation element 3 is thus by the excitation frequency of the AC voltage in such a way Vibrations offset that the entire front surface 34 almost in-phase deflections with almost the same size Amplitude parallel to the surface normal on the front surface 34 executes.

Um eine möglichst große Amplitude der Schwingung der Frontfläche 34 zu erzielen wird das Wandlerelement 1 vorzugsweise mit einer Anregungsfrequenz angetrieben, die der Resonanzfrequenz des Verbundschwingers entspricht. Die Länge L des Verbundschwingers in axialer Richtung entspricht dabei einem ganzzahligen Vielfachen einer halben Wellenlänge, derjenigen durch gewichtete Mittelung zu ermittelnden fiktiven Wellenlänge, die Schall oder Ultraschall der Anregungsfrequenz in dem Verbundschwinger aufweist.In order to maximize the amplitude of the vibration of the To achieve front surface 34, the converter element 1 preferably driven with an excitation frequency that corresponds to the resonance frequency of the compound transducer. The Length L of the compound transducer in the axial direction corresponds to an integer multiple of half Wavelength to that by weighted averaging determining fictitious wavelength that sound or Ultrasound of the excitation frequency in the composite oscillator having.

Vermittelt durch die Stege 32 wird diese Schwingung auf die Membranen 51 übertragen. Die Membranen 51 führen, da sie am Rand fest mit den Stegen 32 verbunden sind Biegeschwingungen aus. Durch diese Biegeschwingungen liegt eine gute Anpassung des Ultraschallsensors an Luft vor. Es tritt eine Amplitudenüberhöhung auf, d.h. die Schwingungsamplitude der Membranen 51 ist größer als die der Stege 32. Die Amplitudenüberhöhung ist maximal, wenn die Anregungsfrequenz mit der Resonanzfrequenz der jeweiligen Membran 51 übereinstimmt. Dann ist die Biegeschwingung der jeweiligen Membran 51 gegenüber der Anregungsfrequenz um 180° phasenverschoben. Die Auslenkung der jeweiligen Membran 51 ist derjenigen der an sie angrenzenden Stege 32 entgegengesetzt.This vibration is mediated by the webs 32 on the Membranes 51 transferred. The membranes 51 lead because they on Bending vibrations are firmly connected to the webs 32 at the edge out. Due to these bending vibrations there is one good adaptation of the ultrasonic sensor to air. There is an increase in amplitude, i.e. the Vibration amplitude of the membranes 51 is larger than that the webs 32. The amplitude increase is maximum if the excitation frequency with the resonance frequency of the respective membrane 51 matches. Then it is Bending vibration of the respective membrane 51 relative to the Excitation frequency out of phase by 180 °. The deflection of the respective membrane 51 is that of them adjacent webs 32 opposite.

In diesem Fall strahlen die jeweilige Membran 51 und die fest mit den an sie angrenzenden Stegen 32 verbundenen beiden Flächen der Scheibe 5 gegenphasige Schallwellen aus.In this case, the respective membrane 51 and firmly connected to the webs 32 adjacent to them both surfaces of the disc 5 out of phase sound waves.

Es tritt destruktive Interferenz auf. Um die dadurch bedingte Verluste gering zu halten, ist es erforderlich, daß die Summe der Flächen der Membranen 51 groß gegenüber der Summe der Flächen der Scheibe 5, die fest mit den Stegen 32 verbunden sind, ist. Destructive interference occurs. To that to keep contingent losses low, it is necessary that the sum of the areas of the membranes 51 is large compared the sum of the areas of the disc 5, which are fixed with the Web 32 are connected.

Je weiter die Resonanzfrequenz der jeweiligen Membran 51 oberhalb der Anregungsfrequenz liegt, desto geringer ist die beschriebene Phasenverschiebung. Gleichzeitig reduziert sich jedoch die Amplitudenüberhöhung und somit auch die von der jeweiligen Membran 51 abgestrahlte Schallleistung.The further the resonance frequency of the respective membrane 51 is above the excitation frequency, the lower the phase shift described. Reduced at the same time however, the amplitude increase and thus also that of the respective diaphragm 51 radiated sound power.

Die Resonanzfrequenz der jeweiligen Membran 51 ist maßgeblich durch deren mittleren Radius und deren Steifigkeit bestimmt. Bei äquidistanter Beabstandung gleichbreiter Stege 32 in radialer Richtung wäre die Resonanzfrequenz der äußeren Membranen 51 folglich niedriger, als die der inneren. Durch Verringerung des Abstandes zwischen zwei benachbarten Stegen 32 in radialer Richtung erhöht sich die Resonanzfrequenz der zwischen den Stegen angeordneten Membran 51.The resonance frequency of the respective membrane 51 is decisive by their mean radius and their Stiffness determined. With equidistant spacing webs of the same width in the radial direction would be the Resonance frequency of the outer membranes 51 consequently lower than that of the inner ones. By reducing the Distance between two adjacent webs 32 in a radial Direction increases the resonance frequency between the Web 51 arranged webs.

Vorzugsweise liegt die Resonanzfrequenz aller Membranen 51 oberhalb der Anregungsfrequenz. Dadurch wird das Auftreten von Biegewellen höherer Ordnung ausgeschlossen.The resonance frequency of all membranes 51 is preferably above the excitation frequency. This will make the appearance excluded from higher order bending waves.

Die Abstrahlcharakteristik des Schall- oder Ultraschallsensors ist durch die Abstände zwischen den Stegen 32 in radialer Richtung, also durch die Abstimmung der Resonanzfrequenzen der Biegeschwingungen der einzelnen Membranen 51 aufeinander und auf die Antriebsfrequenz, einstellbar. Im folgenden sind zwei Beispiele hierfür angegeben.The radiation pattern of the sound or Ultrasonic sensor is characterized by the distances between the Web 32 in the radial direction, that is, by the vote the resonance frequencies of the bending vibrations of the individual Membranes 51 on top of each other and on the drive frequency, adjustable. The following are two examples of this specified.

Zum einen wird ein Schall- oder Ultraschallsensor mit einer für die Abstandsmessung nach dem Echolotprinzip geeigneten Abstrahlcharakteristik erzielt, indem die Abmessungen so gesetzt werden, daß die Resonanzfrequenz der kreisförmigen mittleren Membran 51 gleich oder größer als die Antriebsfrequenz ist und die Resonanzfrequenzen der anderen ringscheibenförmigen Membranen 51 so abgestimmt sind, daß eine Membran 51 mit einem kleineren Außenradius eine geringere Resonanzfrequenz aufweist, als eine Membran 51 mit einem größeren Außenradius. Die kreisförmige mittlere Membran 51 hat die niedrigste Resonanzfrequenz.On the one hand, a sound or ultrasonic sensor with a suitable for distance measurement according to the sonar principle Radiation characteristics achieved by the dimensions so be set that the resonant frequency of the circular middle membrane 51 equal to or larger than that Drive frequency is and the resonance frequencies of the others annular disk-shaped membranes 51 are matched so that a membrane 51 with a smaller outer radius has a lower resonance frequency than a membrane 51 with a larger outer radius. The circular middle Membrane 51 has the lowest resonance frequency.

Die Amplitudenüberhöhung und damit die abgestrahlte Schallenergie nimmt somit entlang der Scheibe 5 von innen nach außen ab. Die Amplitudenverteilung entlang einer Diagonalen der Scheibe 5 entspricht näherungsweise einer Gaußkurve. Die durch Nebenkeulen abgestrahlte Schallenergie ist erheblich geringer als bei einem reinen Kolbenschwinger ohne Stege 32 und ohne Scheibe 5.The increase in amplitude and thus the radiated Sound energy thus takes along the pane 5 from the inside to the outside. The amplitude distribution along one Diagonals of the disc 5 approximately corresponds to one Gaussian curve. The sound energy emitted by side lobes is considerably lower than with a pure piston oscillator without webs 32 and without washer 5.

Zum anderen wird eine nahezu gleichphasige Abstrahlung aller Bereiche der Scheibe 5 erzielt, indem die Resonanzfrequenzen der Membranen 51 alle gleich und deutlich, z.B. 10 %, größer als die Anregungsfrequenz sind. Es tritt dann nahezu keine Phasenverschiebung zwischen der Schwingung der einzelnen Membranen 51 und den an sie angrenzenden mit den jeweils benachbarten Stegen 32 verbundenen Bereichen der Scheibe 5 auf.On the other hand, the radiation is almost in phase achieved all areas of the disc 5 by the Resonance frequencies of the membranes 51 all the same and clearly, e.g. 10%, are greater than the excitation frequency. Then there is almost no phase shift between the Vibration of the individual membranes 51 and to them adjacent with the respective adjacent webs 32 connected areas of the disc 5.

Wird der Schall- oder Ultraschallsensor dazu verwendet, Schall- oder Ultraschall-Impulse einer bestimmten Dauer auszusenden, so ist darauf zu achten, daß der Schall- oder Ultraschallsensor nach dem Ende der Anregung durch das Wandlerelement 1 möglichst nicht nachschwingt.If the sound or ultrasonic sensor is used to Sound or ultrasound pulses of a certain duration to send out, so make sure that the sound or Ultrasonic sensor after the end of the excitation by the If possible, transducer element 1 does not reverberate.

Hierzu ist der Abstand zwischen den Membranen 51 und der Frontfläche 34 des Abstrahlelements 3, also die Tiefe der Spalte 33, vorzugsweise so bemessen, daß er geringfügig größer ist als die maximale Auslenkung der die Spalte 33 abschließenden Membranen 51. Die Kompression der in den Spalten 33 enthaltenen Luft durch die Biegeschwingungen der Membranen 51 bewirkt eine Dämpfung, durch die das Nachschwingen des Senors erheblich reduziert ist.For this purpose, the distance between the membranes 51 and Front surface 34 of the radiating element 3, that is the depth of the Column 33, preferably dimensioned so that it is slight is greater than the maximum deflection of column 33 final membranes 51. The compression of the in the Columns 33 contained air due to the bending vibrations of the Membranes 51 cause damping through which the Ringing of the senor is significantly reduced.

Eine Reduktion des Nachschwingens wird gleichfalls erzielt, indem in die Spalte 33 ein Dämpfungsmaterial 6, z.B. ein Schaumstoff, eingebracht ist. Ein solcher Schaumstoff kann beispielsweise auf dem Abstrahlelement 3 aufgeklebt sein. Insb. ist die Ausbildung von ringförmig in den Spalten 33 umlaufenden Wellen durch das Dämpfungsmaterial 6 ausgeschlossen.A reduction in reverberation is also achieved by placing a damping material 6, e.g. on Foam, is introduced. Such a foam can For example, be glued to the radiation element 3. Esp. is the formation of a ring in the columns 33 revolving waves through the damping material 6 locked out.

Der durch die Stege 32 und die Scheibe 5 gebildete Vorbau des Verbundschwingers bewirkt durch die Biegeschwingung eine Anpassung der akustischen Impedanz des Schall- oder Ultraschallsensors an die akustische Impedanz des Mediums, in den die Schallenergie auszusenden ist. Insbesondere ist es nicht erforderlich, eine zusätzliche Schicht aus einem Material, dessen akustische Impedanz zwischen der des Materials der Scheibe 5 und der des Mediums in das die Schallenenergie auszusenden ist, z.B. aus einem Elastomer vorzusehen.The stem formed by the webs 32 and the disc 5 of the compound transducer caused by the bending vibration an adjustment of the acoustic impedance of the sound or Ultrasonic sensor to the acoustic impedance of the medium, into which the sound energy is to be emitted. In particular is it does not require an additional layer of one Material whose acoustic impedance is between that of the Material of the disc 5 and that of the medium in which Sound energy is to be emitted, e.g. made of an elastomer provided.

Eine auf die Scheibe 5 auftreffende Schall- oder Ultraschallwelle versetzt die Scheibe 5, besonders die Membranen 51 in Biegeschwingungen, die durch das Abstrahlelement auf das Wandlerelement 1 übertragen werden. Dadurch werden die piezoelektrischen Elemente 1a und 1b in Schwingungen versetzt. Es entsteht eine piezoelektrische Spannung die über die Elektroden 11, 12a und 12b einer weiteren Verarbeitung zugänglich ist.A sound or impinging on the disc 5 Ultrasonic wave displaces disc 5, especially that Membranes 51 in bending vibrations caused by the Radiating element can be transferred to the transducer element 1. Thereby, the piezoelectric elements 1a and 1b in Vibrated. A piezoelectric is created Voltage across the electrodes 11, 12a and 12b one further processing is accessible.

Der Schall- oder Ultraschallsensor ist durch die vorzugsweise metallische Scheibe 5 abgeschlossen. Damit ist er bei hohen Temperaturen bis ca. 150 °C einsetzbar. Der Temperaturbereich ist lediglich durch den Temperaturbereich eingeschränkt, in dem das Wandlerelement 1 einsetzbar ist. Durch eine Verlängerung des Abstandes zwischen dem Wandlerelement 1 und der Scheibe 5 sind noch größere Temperaturbereiche erreichbar. Hierbei ist zu beachten, daß die Länge L des Verbundschwingers in axialer Richtung einem ganzzahligen Vielfachen einer halben Wellenlänge, derjenigen durch gewichtete Mittelung zu ermittelnden fiktiven Wellenlänge, die Schall oder Ultraschall der Anregungsfrequenz in dem Verbundschwinger aufweist, entspricht.The sound or ultrasonic sensor is through the preferably metallic disc 5 completed. So that is it can be used at high temperatures up to approx. 150 ° C. The Temperature range is only by the temperature range restricted, in which the converter element 1 can be used. By extending the distance between the Transducer element 1 and disc 5 are even larger Temperature ranges attainable. It should be noted here that the length L of the compound transducer in the axial direction integer multiples of half a wavelength, of those to be determined by weighted averaging fictional wavelength, the sound or ultrasound of the Has excitation frequency in the composite oscillator, equivalent.

Da das Abstrahlelement, die Stege 32 und die Scheibe 5 vorzugsweise aus Metall bestehen treten nur geringe temperaturbedingte Frequenzabweichungen auf.Since the radiating element, the webs 32 and the disk 5 preferably made of metal occur only small temperature-related frequency deviations.

Der Schall- oder Ultraschallsensor ist chemisch sehr beständig und mechanisch sehr robust. Er eignet sich besonders gut für Anwendungen in der Lebensmittelindustrie, da die medium-berührte Scheibe 5 eben und somit gut zu reinigen ist.The sound or ultrasonic sensor is very chemical resistant and mechanically very robust. It is suitable particularly good for applications in the food industry, because the medium-touched disc 5 is flat and therefore good to is clean.

Die Erfindung ist nicht auf den Einsatz bei dem beschriebenen Sensor beschränkt, sonder ist vielmehr bei allen Schall- oder Ultraschallsensoren einsetzbar, die ein Abstrahlelement mit einer ebenen Frontfläche aufweisen, die durch das Wandlerelement 1 aufgrund einer Anregungsfrequenz derart in Schwingungen versetzt wird, daß die gesamte Frontfläche nahezu gleichphasige Auslenkungen mit nahezu gleichgroßer Amplitude parallel zur Flächennormalen der Frontfläche ausführen.The invention is not for use in the described sensor is limited, but is rather at all sound or ultrasonic sensors can be used, the one Have radiating element with a flat front surface, the through the converter element 1 due to an excitation frequency is vibrated such that the entire Front surface almost in-phase deflections with almost equally large amplitude parallel to the surface normal of the Execute the front surface.

Fig. 2 zeigt ein weiteres Ausführungsbeispiel für eines derartigen Schall- oder Ultraschallsensor.Fig. 2 shows a further embodiment for one such sound or ultrasonic sensor.

Bei dem in Fig. 2 im Längschnitt lediglich schematisch dargestellten Schall- oder Ultraschallsensor weist das Wandlerelement 1 lediglich ein einziges scheibenförmiges piezoelektrisches Element auf. Mit diesem Wandlerelement 1 ist eine ebenfalls scheibenförmige Deckplatte 7 mit gleichem Durchmesser fest verbunden. Die Deckplatte 7 wird ebenso wie das Abstrahlelement 3 des in Fig. 1 dargestellten Ausführungsbeispiels zu Schwingungen derart angeregt, daß deren gesamte kreisförmige wandler-abgewandte Frontfläche nahezu gleichphasige Auslenkungen mit nahezu gleichgroßer Amplitude parallel zur Flächennormalen der Frontfläche ausführt.In the longitudinal section in Fig. 2 only schematically shown sound or ultrasonic sensor has that Transducer element 1 is only a single disk-shaped one piezoelectric element. With this converter element 1 is also a disk-shaped cover plate 7 same diameter firmly connected. The cover plate 7 is as well as the radiation element 3 of the one in FIG. 1 illustrated embodiment to vibrations such stimulated that their entire circular transducer-facing Front surface almost in-phase deflections with almost equally large amplitude parallel to the surface normal of the Front surface.

Auf der Deckplatte 7 sind analog zu dem Ausführungsbeispiel von Fig. 1 konzentrische Stege 32 angeordnet, auf denen wiederum die Scheibe 5 befestigt ist.On the cover plate 7 are analogous to the embodiment 1 concentric webs 32 are arranged on which again the disc 5 is attached.

Der Schall- oder Ultraschallsensor ist beispielsweise in einem, in Fig. 2 nicht dargestellten, zylindrischen an einem Ende offenen Gehäuse angeordnet, wobei die zwischen dem Gehäuse und dem Schall- oder Ultraschallsensor bestehenden Hohlräume mit einem elektrisch nichtleitenden Elastomer ausgefüllt sind.The sound or ultrasonic sensor is, for example, in a, not shown in Fig. 2, cylindrical arranged at one end open housing, the between the housing and the sound or ultrasonic sensor existing cavities with an electrically non-conductive Are filled with elastomer.

Das Ausführungsbeispiel von Fig. 2 bietet gegenüber dem in Fig. 1 dargestellten Ausführungsbeispiel den Vorteil, daß es eine sehr geringe Bauhöhe aufweist und daß ein einziges piezoelektrisches Element ausreicht, um den Schall- oder Ultraschallwandler anzuregen.The embodiment of FIG. 2 offers compared to that in Fig. 1 illustrated embodiment the advantage that it has a very low height and that a single piezoelectric element is sufficient to the sound or To stimulate ultrasonic transducers.

Claims (6)

  1. A sonic or ultrasonic sensor for transmitting and/or receiving sound or ultrasound
    with a radiation element (3) which has a level front face (34), and
    with a transformer element (1),
    the transformer element (1) setting the front face (34) into vibrations on account of an excitation frequency in such a way that the entire front face (34) performs almost in-phase displacements with an amplitude of almost equal magnitude parallel to the line at a right angle to the front face (34),
    characterized in that
    concentric webs (32) are arranged on the front face (34),
    a concentric gap (33) is present between two adjacent webs (32) in each case, and
    a disc (5), in particular of metal, terminates the sonic or ultrasonic sensor in alignment with the front, and is connected to the webs (32) in a fixed manner and is provided therebetween with segments which are not connected to the webs (32) and which act as diaphragms (51).
  2. A device according to Claim 1, characterized in that the diaphragms (51) perform bending vibrations, the resonance frequencies of which are larger than or equal to the excitation frequency.
  3. A device according to Claim 2, characterized in that the resonance frequency of the bending vibration of the middle diaphragm (51) is larger than or equal to the excitation frequency, and the resonance frequencies of the remaining diaphragms (51) increase outwards from the inside.
  4. A device according to Claim 1, characterized in that the resonance frequencies of the bending vibrations of the diaphragms (51) are equal amongst themselves and are significantly greater than the excitation frequency, and each diaphragm (51) and the regions of the disc 5 respectively adjoining each diaphragm (51) and connected to the webs (32) vibrate in phase.
  5. A device according to Claim 1, characterized in that a damping material (6), in particular a foamed material, is introduced into the gaps (33).
  6. A device according to Claim 1, characterized in that the gaps (33) have a depth which is slightly larger than a maximum displacement of the diaphragms (51) terminating the gaps (33).
EP97105884A 1996-05-18 1997-04-10 Sound or ultrasound transducer Expired - Lifetime EP0807924B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19620133A DE19620133C2 (en) 1996-05-18 1996-05-18 Sound or ultrasonic sensor
DE19620133 1996-05-18

Publications (3)

Publication Number Publication Date
EP0807924A2 EP0807924A2 (en) 1997-11-19
EP0807924A3 EP0807924A3 (en) 1999-06-02
EP0807924B1 true EP0807924B1 (en) 2002-12-11

Family

ID=7794713

Family Applications (1)

Application Number Title Priority Date Filing Date
EP97105884A Expired - Lifetime EP0807924B1 (en) 1996-05-18 1997-04-10 Sound or ultrasound transducer

Country Status (5)

Country Link
US (1) US5726952A (en)
EP (1) EP0807924B1 (en)
CA (1) CA2203583C (en)
DE (2) DE19620133C2 (en)
HU (1) HU216670B (en)

Families Citing this family (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19758243A1 (en) * 1997-12-30 1999-07-15 Endress Hauser Gmbh Co Sound converter system
DE10156259A1 (en) * 2001-11-09 2003-05-22 Valeo Schalter & Sensoren Gmbh Ultrasonic sensor and method for manufacturing an ultrasonic sensor
US7117738B2 (en) * 2003-10-02 2006-10-10 Denso Corporation Liquid level detecting apparatus
AT413890B (en) * 2004-02-27 2006-07-15 Univ Wien Tech METHOD AND SENSOR DEVICE FOR OBTAINING INFORMATION ON THE POSITION OF AN OBJECT WITH AN ULTRASOUND SENSOR
DE102004020895B4 (en) * 2004-04-28 2012-05-24 Endress + Hauser Gmbh + Co. Kg Device for determining and / or monitoring the level of a medium
DE102005056895A1 (en) * 2005-11-28 2007-05-31 Endress + Hauser Gmbh + Co. Kg Device for determining and monitoring the fill level of a product in a container according to the transit time measurement method
WO2007088772A1 (en) 2006-01-31 2007-08-09 Matsushita Electric Industrial Co., Ltd. Ultrasonic probe
DE102006058926B4 (en) * 2006-12-12 2020-09-24 Endress+Hauser SE+Co. KG Device for determining and / or monitoring a process variable
FR2931016B1 (en) * 2008-05-07 2010-08-13 Ixsea ACOUSTIC ANTENNA WITH INTEGRATED PRINTED CIRCUITS
KR101593994B1 (en) * 2009-09-04 2016-02-16 삼성전자주식회사 High power ultrasonic transducer
US8797830B2 (en) * 2011-02-02 2014-08-05 General Monitors, Inc. Explosion-proof acoustic source for hazardous locations
DE102012201884A1 (en) 2012-02-09 2013-08-14 Robert Bosch Gmbh transducer
TWI487886B (en) * 2014-03-26 2015-06-11 Univ Nat Kaohsiung Applied Sci Integrated Sensing Device with Ultrasonic Transducer and Microphone and Its Method
US9506833B2 (en) 2014-03-26 2016-11-29 General Monitors, Inc. Ultrasonic gas leak detectors and testing methods
GB201408833D0 (en) * 2014-05-19 2014-07-02 Skoogmusic Ltd Control apparatus
DE102015113561A1 (en) 2015-08-17 2017-02-23 Endress + Hauser Flowtec Ag Ultrasonic transducers for use in ultrasonic flowmeters for measuring the flow rate or volume flow of media in a pipeline, and a method of making such an ultrasonic transducer
US10632499B2 (en) * 2016-12-09 2020-04-28 Sensus USA, Inc. Thickness mode transducers and related devices and methods
DE102018200324A1 (en) * 2018-01-11 2019-07-11 Robert Bosch Gmbh Ultrasonic sensor and fluid tank with ultrasonic sensor

Family Cites Families (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2943297A (en) * 1950-04-27 1960-06-28 Raymond L Steinberger Multiple element electroacoustic transducer
US3370186A (en) * 1965-02-05 1968-02-20 Blackstone Corp Ultrasonic transducers
US3457543A (en) * 1968-02-26 1969-07-22 Honeywell Inc Transducer for producing two coaxial beam patterns of different frequencies
US3739327A (en) * 1970-12-16 1973-06-12 Dynamics Corp Massa Div Electroacoustic transducers of the mass loaded vibratile piston type
US3949349A (en) * 1972-04-13 1976-04-06 Fred M. Dellorfano, Jr. Dual electroacoustic transducers
JPS52131676A (en) * 1976-04-27 1977-11-04 Tokyo Shibaura Electric Co Probe for ultrasonic diagnostic device
US4183007A (en) * 1978-02-22 1980-01-08 Fischer & Porter Company Ultrasonic transceiver
US4246449A (en) * 1979-04-24 1981-01-20 Polaroid Corporation Electrostatic transducer having optimum sensitivity and damping
CA1136257A (en) * 1980-04-21 1982-11-23 Stanley Panton Broadly tuned directional transducer
US4333028A (en) * 1980-04-21 1982-06-01 Milltronics Ltd. Damped acoustic transducers with piezoelectric drivers
US4633119A (en) * 1984-07-02 1986-12-30 Gould Inc. Broadband multi-resonant longitudinal vibrator transducer
DE3721209C2 (en) * 1987-06-26 1997-04-30 Grieshaber Vega Kg Sound / ultrasonic measuring device
US5515342A (en) * 1988-12-22 1996-05-07 Martin Marietta Corporation Dual frequency sonar transducer assembly
US5218575A (en) * 1992-09-04 1993-06-08 Milltronics Ltd. Acoustic transducer
US5452267A (en) * 1994-01-27 1995-09-19 Magnetrol International, Inc. Midrange ultrasonic transducer

Also Published As

Publication number Publication date
CA2203583A1 (en) 1997-11-18
DE19620133C2 (en) 2001-09-13
HUP9700904A3 (en) 1998-12-28
EP0807924A2 (en) 1997-11-19
HUP9700904A2 (en) 1998-04-28
CA2203583C (en) 2000-02-08
DE59708924D1 (en) 2003-01-23
EP0807924A3 (en) 1999-06-02
HU216670B (en) 1999-08-30
US5726952A (en) 1998-03-10
HU9700904D0 (en) 1997-07-28
DE19620133A1 (en) 1997-11-27

Similar Documents

Publication Publication Date Title
EP0807924B1 (en) Sound or ultrasound transducer
DE102007046031B4 (en) ultrasonic sensor
EP0507892B1 (en) Ultrasonic transducer
EP0449023B1 (en) Device for determining and/or monitoring a predetermined filling level in a container
EP0840655B1 (en) Ultrasound transducer
DE3602351C1 (en) Sound converter system
DE4006718A1 (en) PIEZOELECTRIC CONVERTER
DE3815359A1 (en) TRANSMITTER / RECEIVER OF A ULTRASONIC DISTANCE MEASURING DEVICE
DE4008768A1 (en) PIEZOELECTRIC CONVERTER
EP0903563A1 (en) Device for the detection and/or monitoring of a predetermined level in a container
EP1308750A2 (en) Method and device for measuring distance and pressure inside an air spring
EP1111585A2 (en) Method for generation of Lamb-waves in a plate, in particular a container-wall, and apparatus for applying the method and for reception of the generated Lamb-waves
DE2537788A1 (en) Piezoelectric ultrasonic transducer - with wider bandwidth, and greater sensitivity when used as microphone
EP0615471B1 (en) Sonic or ultrasonic transducer
EP0927987B1 (en) Sound transducer system
DE4323134C1 (en) Ultrasonic oscillator - has oversize matching body resting on support ring for acoustic dampening
WO1999010874A1 (en) Acoustic transducer
EP1493302B1 (en) Sound or ultrasound sensor
DE202007007135U1 (en) Ultrasonic transducer for sending and receiving ultrasonic signal in e.g. air, has piezoelectric transducer unit e.g. piezoceramic, radially coupled to pot base in form-fit and force-fit manner, and housing made of aluminum oxide
EP1206698A2 (en) Ultrasound sensor system
DE19623071C2 (en) Ultrasonic transducer
WO2002061413A2 (en) Ultrasonic sensor for controlling the process during resistance spot welding
EP3822661A1 (en) Object detection sensor
DE19750179A1 (en) Sonic transducer e.g. for air
DE3401979A1 (en) Ultrasonic transducer

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): DE GB

17P Request for examination filed

Effective date: 19980328

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Kind code of ref document: A3

Designated state(s): DE GB

RIC1 Information provided on ipc code assigned before grant

Free format text: 6G 10K 13/00 A, 6B 06B 1/06 B

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: ENDRESS + HAUSER GMBH + CO.KG.

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

17Q First examination report despatched

Effective date: 20020516

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE GB

REG Reference to a national code

Ref country code: GB

Ref legal event code: FG4D

Free format text: NOT ENGLISH

GBT Gb: translation of ep patent filed (gb section 77(6)(a)/1977)

Effective date: 20021218

REF Corresponds to:

Ref document number: 59708924

Country of ref document: DE

Date of ref document: 20030123

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed

Effective date: 20030912

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20110421

Year of fee payment: 15

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20110421

Year of fee payment: 15

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20120410

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20120410

REG Reference to a national code

Ref country code: DE

Ref legal event code: R119

Ref document number: 59708924

Country of ref document: DE

Effective date: 20121101

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20121101