EP1173842A1 - Ultrasound sensor having a pot-shaped oscillating element - Google Patents

Ultrasound sensor having a pot-shaped oscillating element

Info

Publication number
EP1173842A1
EP1173842A1 EP01903687A EP01903687A EP1173842A1 EP 1173842 A1 EP1173842 A1 EP 1173842A1 EP 01903687 A EP01903687 A EP 01903687A EP 01903687 A EP01903687 A EP 01903687A EP 1173842 A1 EP1173842 A1 EP 1173842A1
Authority
EP
European Patent Office
Prior art keywords
uitraschaiisensor
piezoelectric transducers
membrane
shaped
sensor
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
EP01903687A
Other languages
German (de)
French (fr)
Inventor
Dieter Falzewski
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.)
Volkswagen AG
Original Assignee
Volkswagen 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 Volkswagen AG filed Critical Volkswagen AG
Publication of EP1173842A1 publication Critical patent/EP1173842A1/en
Ceased legal-status Critical Current

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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
    • G10K9/00—Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers
    • G10K9/12—Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers electrically operated
    • G10K9/122—Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers electrically operated using piezoelectric driving means
    • 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
    • G10K9/00—Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers
    • G10K9/12—Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers electrically operated
    • G10K9/122—Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers electrically operated using piezoelectric driving means
    • G10K9/125—Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers electrically operated using piezoelectric driving means with a plurality of active elements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
    • G01S15/88—Sonar systems specially adapted for specific applications
    • G01S15/93—Sonar systems specially adapted for specific applications for anti-collision purposes
    • G01S15/931—Sonar systems specially adapted for specific applications for anti-collision purposes of land vehicles

Definitions

  • the invention relates to an ultrasonic sensor, in particular for parking aids in motor vehicles, with a cup-shaped oscillating element, the bottom of which serves as a membrane.
  • Such a sensor which functions according to the ultrasound echo principle, is known, for example, from DE 39 39 387 A1.
  • the inside of the membrane of this ultrasonic sensor carries a piezo disk, the membrane and the piezo disk each being designed in the form of a circular disk.
  • the piezo disk is excited to oscillate by an applied electrical voltage, so that ultrasound waves emitted via the outside of the membrane are generated.
  • At least some of these ultrasonic waves are received by the membrane as reflection signals in the subsequent microphone phase of the sensor after reflection from an obstacle, for example another parked vehicle, and are thereby transmitted in the form of vibrations to the piezo disk, due to the piezo effect on the An electrical voltage proportional to the vibrations is generated on the side of the piezo disk, which can be used as a parking aid signal after electronic processing.
  • the ultrasonic sensor known from DE 39 39 387 A1 has a diaphragm which partially covers the outside of the membrane and is designed in the form of a circular section, the chord of which runs parallel to a plane of symmetry of the sensor.
  • the solution according to the invention has the particular advantage that with an increasing number of piezoelectric transducers and thus an increasing asymmetry ratio, for example between the horizontal and vertical central plane of the radiation lobe, the sound power and thus the sensory effect increases
  • Another advantage of the invention is that by using several small piezo disks arranged next to one another, higher ultrasonic frequencies can be achieved than when using only a single large piezo disk. With several small piezo disks, finer and more precise and thus more powerful radiation lobes can also be modeled
  • An advantageous embodiment of the ultrasonic sensor according to the invention consists in that it is additionally provided with mechanical means for achieving an asymmetrical sound directional diagram. Because of the increased vibration energy available when several piezoelectric transducers are used, a more detailed design of the sound directional diagram is possible, for example in such a way that not only a purely elliptical directional diagram in the XY section is possible, but also, for example, a trapezoidal directional diagram.
  • a directional diagram can be achieved with such a Uitraschai sensor, in which a lower sound power is emitted in the direction of the roadway level, so that accordingly less ground echoes are received, and in which a higher sound power is emitted vertically upwards, so that a correspondingly longer sensor range results or objects which are more difficult to detect, in particular Objects with low reflectivity can be detected Further preferred and advantageous embodiments of the invention are specified in the subclaims.
  • FIG. 1 is a plan view of a vibrating element of an ultrasonic sensor according to the invention in a sectional view
  • FIG. 2 is a side view of the vibrating element according to FIG. 1 in a sectional view
  • FIG. 3 shows a typical sound directional diagram of an ultrasonic sensor according to the invention in horizontal section
  • FIG. 5 is a plan view of a vibration element of a conventional ultrasonic sensor in a sectional view
  • FIG. 6 is a side view of the vibrating element according to FIG. 5 in a sectional view
  • FIG. 8 shows the sound directional diagram according to FIG. 7 in vertical section transverse to the longitudinal axis of the ultrasonic sensor.
  • FIGS. 5 and 6 show a vibrating element 1 of a conventional ultrasonic sensor for parking aids in motor vehicles.
  • the vibrating element 1 is cup-shaped and carries a circular piezo disk 3 on the inside of the bottom surface serving as membrane 2.
  • the piezo disk 3 is excited to vibrate for a certain time phase by an applied electrical voltage, so that 2 ultrasonic waves are emitted via the outside of the membrane , After reflection from an obstacle in the subsequent microphone phase of the sensor, these ultrasonic waves are received by the membrane 2 as echo signals and transmitted in the form of vibrations to the piezo disk 3.
  • the distance of the obstacle from the Uitraschaiis sensor being able to be calculated from the time difference between the transmission of the ultrasonic waves and the reception of the echo signals.
  • a Uitraschaiisensor with the construction shown in FIGS. 5 and 6 has an essentially club-shaped sound directional diagram, which has a largely rotationally symmetrical shape in vertical section (Z-section) transverse to the longitudinal axis of the ultrasonic sensor (see FIGS. 7 and 8).
  • a sound directional diagram has the disadvantage that undesirable echo effects, in particular ground echoes, occur with larger lobe shapes. If the lobe-shaped expansion of the sound directional diagram is reduced by a corresponding reduction in the sound power, the detection range of the ultrasonic sensor is also reduced in the horizontal direction, which results in unacceptable detection gaps.
  • the vibrating element 4 of an ultrasonic sensor according to the invention is likewise pot-shaped.
  • the oscillating element 4 has a circumferential cylindrical side wall and a bottom surface serving as a membrane 5.
  • two piezoelectric bending transducers 6, 7 are fastened to the inside of this membrane 5.
  • the transducers 6, 7, which are arranged next to one another in the form of a circular disk, are excited to vibrate in parallel and in the same direction of vibration during the transmission operation of the ultrasound sensor and, in the subsequent microphone phase, reproduce the received echo signals in parallel as an electrical output voltage.
  • the bending transducers 6, 7 are controlled by means of a small electrical transformer (not shown). It can be seen that the two disk-shaped piezoelectric transducers 6, 7 are arranged at a slight distance from one another and from the peripheral side wall of the pot-shaped vibrating element 4.
  • the oscillating element 4 is provided on the inside with two arcuate diaphragms 8, 9 which are arranged at a distance from the membrane 5.
  • the diaphragms 8, 9 are arranged so that they do not cover the piezoelectric transducers 6, 7.
  • the cup-shaped oscillating element can also have one or more recesses and / or ribs, which are preferably arranged on the inside and / or outside of the membrane.
  • FIGS. 3 and 4 show a typical sound directional diagram of an ultrasonic sensor with a vibrating element according to FIGS. 1 and 2, with FIG. 3 a horizontal section (Z section) and FIG. 4 a vertical section (Y section) transverse to Longitudinal axis of the pot-shaped vibrating element.
  • the large asymmetrical effect of the ultrasonic sensor according to the invention can be seen in particular from FIG. 4.
  • the invention is not restricted to the exemplary embodiment described above. Rather, a number of variants are conceivable.
  • three or more piezoelectric transducers can also be attached to the membrane 5.
  • oval, rectangular or asymmetrical piezoelectric transducers can also be used instead of circular ones.
  • the piezoelectric transducers 6, 7 of the ultrasound sensor according to the invention can not only vibrate in parallel and in the same direction of vibration in the transmission mode.
  • the piezoelectric transducers 6, 7 can also be controlled separately and in particular out of phase. Such control enables the generation of specially designed sound directional diagrams and can therefore bring significant advantages in certain situations.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
  • Transducers For Ultrasonic Waves (AREA)

Abstract

The invention relates to an ultrasound sensor, especially for parking aids in motor vehicles, comprising a pot-shaped oscillating element (4). The bottom of said element serves as a membrane. According to the invention, at least two disc-shaped piezoelectric transducers (6, 7) are fixed next to one another in the membrane (5). The inventive ultrasound sensor is characterised by a sound directional diagram being provided with particularly high asymmetry.

Description

ULTRASCHALLSENSOR MIT EINEM TOPFFÖRMIGEN SCHWINGELEMENT . ULTRASONIC SENSOR WITH A POT-SHAPED VIBRATION ELEMENT.
Die Erfindung betrifft einen Ultraschallsensor, insbesondere für Einparkhilfen in Kraftfahrzeugen, mit einem topfförmigen Schwingelement, dessen Boden als Membran dient.The invention relates to an ultrasonic sensor, in particular for parking aids in motor vehicles, with a cup-shaped oscillating element, the bottom of which serves as a membrane.
Ein derartiger, nach dem Ultraschall-Echoprinzip funktionierender Sensor ist beispielsweise aus der DE 39 39 387 A1 bekannt. Die Membran dieses Ultraschallsensors trägt innenseitig eine Piezoscheibe, wobei Membran und Piezoscheibe jeweils kreisscheibenförmig ausgebildet sind. Die Piezoscheibe wird in der Sendephase des Sensors durch eine angelegte elektrische Spannung zum Schwingen angeregt, so daß über die Außenseite der Membran abgestrahlte Ultraschallwellen erzeugt werden. Von diesen Ultraschallwellen wird zumindest ein Teil nach Reflexion an einem Hindernis, beispielsweise einem anderen parkenden Fahrzeug, als Echosignale in der anschließenden Mikrofonphase des Sensors von der Membran empfangen und dabei in Form von Schwingungen auf die Piezoscheibe übertragen, wobei aufgrund des Piezo-Effektes an den Scheibenseiten der Piezoscheibe eine den Schwingungen proportionale elektrische Spannung entsteht, die nach elektronischer Aufbereitung als Einparkhilfe-Signal verwertbar ist.Such a sensor, which functions according to the ultrasound echo principle, is known, for example, from DE 39 39 387 A1. The inside of the membrane of this ultrasonic sensor carries a piezo disk, the membrane and the piezo disk each being designed in the form of a circular disk. In the transmission phase of the sensor, the piezo disk is excited to oscillate by an applied electrical voltage, so that ultrasound waves emitted via the outside of the membrane are generated. At least some of these ultrasonic waves are received by the membrane as reflection signals in the subsequent microphone phase of the sensor after reflection from an obstacle, for example another parked vehicle, and are thereby transmitted in the form of vibrations to the piezo disk, due to the piezo effect on the An electrical voltage proportional to the vibrations is generated on the side of the piezo disk, which can be used as a parking aid signal after electronic processing.
Es wurden bereits verschiedene Konstruktionen für Ultraschallsensoren der hier interessierenden Art vorgeschlagen, die darauf abzielen, den Detektionsbereich des Sensors zu beeinflussen, um unerwünschte Echowirkungen, insbesondere den Empfang von Bodenechos zu vermeiden. Der aus der DE 39 39 387 A1 bekannte Ultraschallsensor weist hierzu eine die Außenseite der Membran teilweise abdeckende Blende auf, die in Form eines Kreisabschnittes ausgebildet ist, dessen Sehne parallel zu einer Symmetrieebene des Sensors verläuft.Various designs for ultrasonic sensors of the type of interest here have already been proposed, which aim to influence the detection range of the sensor in order to avoid undesired echo effects, in particular the reception of ground echoes. For this purpose, the ultrasonic sensor known from DE 39 39 387 A1 has a diaphragm which partially covers the outside of the membrane and is designed in the form of a circular section, the chord of which runs parallel to a plane of symmetry of the sensor.
Aus der DE 37 32 410 A1 ist ein gattungsgemäßer Uitraschaiisensor bekannt, dessen Membran in wenigstens einer ihrer Oberflächen zueinander parallel verlaufende Rillen aufweist. Diese Rillen bewirken, daß die bei herkömmlichen, solche Rillen nicht aufweisenden Ultraschallsensoren weitgehend symmetrischen Schwingungen der Piezoscheibe bzw. Membran so verzerrt werden, daß sich bezogen auf die Flächennormale der Membran ein asymmetrisches räumliches Schall-Richtdiagramm ergibt. Die Herstellung dieser Rillen ist relativ aufwendig, wobei das realisierbare Asymmetrieverhältnis dabei ohnehin begrenzt ist. Hinzu kommt eine Verschlechterung des akustischen und somit sensorischen Wirkungsgrades. Zum Stand der Technik bezüglich der Beeinflussung des Detektionsbereichs gattungsgemaßer Ultraschallsensoren wird ferner auf die deutschenFrom DE 37 32 410 A1 a generic Uitraschaiis sensor is known, the membrane of which has grooves running parallel to each other in at least one of its surfaces. These grooves have the effect that the largely symmetrical vibrations of the piezo disk or membrane in conventional ultrasound sensors not having such grooves are distorted in such a way that an asymmetrical spatial sound directional diagram results with respect to the surface normal of the membrane. The production of these grooves is relatively complex, the asymmetry ratio that can be achieved being limited anyway. In addition, there is a deterioration in the acoustic and thus sensory efficiency. The state of the art with regard to influencing the detection range of generic ultrasonic sensors is further referred to the German ones
Offenlegungsschπften DE 44 13 894 AI , DE 34 41 684 AI und DE 31 37 745 A1 verwiesenDisclosures DE 44 13 894 AI, DE 34 41 684 AI and DE 31 37 745 A1 referenced
Aufgabe der vorliegenden Erfindung ist es, einen Uitraschaiisensor zu schaffen, der bei hohem Wirkungsgrad ein Schall-Richtdiagramm mit großer Asymmetrie aufweist sowie relativ einfach und auch in Großserie zuverlässig reproduzierbar herzustellen istIt is an object of the present invention to provide a Uitraschaiisensor which, with high efficiency, has a sound directional diagram with great asymmetry and is relatively simple to manufacture and can also be reliably reproduced in large series
Diese Aufgabe wird bei einem Uitraschaiisensor der eingangs genannten Art erfindungsgemaß dadurch gelost, daß an der Membran mindestens zwei scheibenförmige piezoelektrische Wandler nebeneinander befestigt sindThis object is achieved according to the invention in a Uitraschai sensor of the type mentioned at the outset in that at least two disk-shaped piezoelectric transducers are fastened next to one another on the membrane
Die erfindungsgemaße Losung hat insbesondere den Vorteil, daß mit steigender Anzahl der piezoelektrischen Wandler und somit steigendem Asymmetneverhaltnis, z B zwischen horizontaler und vertikaler Mittelebene der Strahlungskeule, die Schalleistung und somit die sensorische Wirkung ansteigtThe solution according to the invention has the particular advantage that with an increasing number of piezoelectric transducers and thus an increasing asymmetry ratio, for example between the horizontal and vertical central plane of the radiation lobe, the sound power and thus the sensory effect increases
Ein weiterer Vorteil der Erfindung besteht darin, daß durch die Verwendung von mehreren kleinen, nebeneinander angeordneten Piezoscheiben höhere Ultraschalifrequenzen realisiert werden können als bei der Verwendung lediglich einer einzigen großen Piezoscheibe Mit mehreren kleinen Piezoscheiben können zudem feinere und genauere und somit leistungsfähigere Strahlungskeulen modelliert werdenAnother advantage of the invention is that by using several small piezo disks arranged next to one another, higher ultrasonic frequencies can be achieved than when using only a single large piezo disk. With several small piezo disks, finer and more precise and thus more powerful radiation lobes can also be modeled
Eine vorteilhafte Ausgestaltung des erfindungsgemaßen Ultraschallsensors besteht dann, daß dieser zusätzlich mit mechanischen Mitteln zur Erzielung eines asymmetrischen Schall-Richtdiagramms versehen ist Aufgrund der beim Einsatz von mehreren piezoelektrischen Wandlern erhöht zur Verfugung stehenden Schwingungsenergie ist somit eine detailliertere Ausbildung des Schall-Richtdiagramms möglich, zum Beispiel in der Art, daß nicht nur ein rein elliptisches Richtdiagramm im X-Y-Schnitt möglich ist, sondern auch beispielsweise ein trapezförmiges Richtdiagramm Insbesondere kann mit einem derartigen Uitraschaiisensor ein Richtdiagramm erzielt werden, bei welchem in Richtung der Fahrbahnebene eine geringere Schalleistung abgestrahlt wird, so daß entsprechend weniger Bodenechos empfangen werden, und bei dem vertikal nach oben eine höhere Schalleistung abgestrahlt wird, so daß sich eine entsprechend höhere Sensorreichweite ergibt bzw auch schwieriger detektierbare Objekte, insbesondere Objekte mit geringem Reflexionsvermogen erfaßt werden können Weitere bevorzugte und vorteilhafte Ausgestaltungen der Erfindung sind in den Unteransprüchen angegeben.An advantageous embodiment of the ultrasonic sensor according to the invention then consists in that it is additionally provided with mechanical means for achieving an asymmetrical sound directional diagram. Because of the increased vibration energy available when several piezoelectric transducers are used, a more detailed design of the sound directional diagram is possible, for example in such a way that not only a purely elliptical directional diagram in the XY section is possible, but also, for example, a trapezoidal directional diagram. In particular, a directional diagram can be achieved with such a Uitraschai sensor, in which a lower sound power is emitted in the direction of the roadway level, so that accordingly less ground echoes are received, and in which a higher sound power is emitted vertically upwards, so that a correspondingly longer sensor range results or objects which are more difficult to detect, in particular Objects with low reflectivity can be detected Further preferred and advantageous embodiments of the invention are specified in the subclaims.
Nachfolgend wird die Erfindung anhand einer ein Ausführungsbeispiel darstellenden Zeichnung näher erläutert. Im einzelnen zeigen in schematischer Darstellung:The invention is explained in more detail below on the basis of a drawing illustrating an exemplary embodiment. In a schematic representation:
Fig. 1 eine Draufsicht auf ein Schwingelement eines erfindungsgemäßen Ultraschallsensors in Schnittdarstellung,1 is a plan view of a vibrating element of an ultrasonic sensor according to the invention in a sectional view,
Fig. 2 eine Seitenansicht auf das Schwingelement gemäß Fig. 1 in Schnittdarstellung,2 is a side view of the vibrating element according to FIG. 1 in a sectional view,
Fig. 3 ein typisches Schall-Richtdiagramm eines erfindungsgemäßen Ultraschallsensors im Horizontalschnitt,3 shows a typical sound directional diagram of an ultrasonic sensor according to the invention in horizontal section,
Fig. 4 das Schall-Richtdiagramm gemäß Fig. 3 im Vertikalschnitt quer zur Längsachse des Ultraschallsensors,4 the sound directional diagram according to FIG. 3 in vertical section transverse to the longitudinal axis of the ultrasonic sensor,
Fig. 5 eine Draufsicht auf ein Schwingelement eines herkömmlichen Ultraschallsensors in Schnittdarstellung,5 is a plan view of a vibration element of a conventional ultrasonic sensor in a sectional view,
Fig. 6 eine Seitenansicht auf das Schwingelement gemäß Fig. 5 in Schnittdarstellung,6 is a side view of the vibrating element according to FIG. 5 in a sectional view,
Fig. 7 ein typisches Schall-Richtdiagramm eines herkömmlichen Ultraschallsensors im Horizontalschnitt, und7 shows a typical sound directional diagram of a conventional ultrasonic sensor in horizontal section, and
Fig. 8 das Schall-Richtdiagramm gemäß Fig. 7 im Vertikalschnitt quer zur Längsachse des Ultraschallsensors.8 shows the sound directional diagram according to FIG. 7 in vertical section transverse to the longitudinal axis of the ultrasonic sensor.
In den Figuren 5 und 6 ist ein Schwingelement 1 eines herkömmlichen Ultraschallsensors für Einparkhilfen in Kraftfahrzeugen dargestellt. Das Schwingelement 1 ist topfförmig ausgebildet und trägt auf der Innenseite der als Membran 2 dienenden Bodenfläche eine kreisförmige Piezoscheibe 3. Die Piezoscheibe 3 wird für eine bestimmte Zeitphase durch eine angelegte elektrische Spannung zum Schwingen angeregt, so daß über die Außenseite der Membran 2 Ultraschallwellen ausgesandt werden. Diese Ultraschallwellen werden nach Reflexion an einem Hindernis in der anschließenden Mikrofonphase des Sensors von der Membran 2 als Echosignale empfangen und in Form von Schwingungen auf die Piezoscheibe 3 übertragen. An den Scheibenseiten der Piezoscheibe 3 entsteht dabei aufgrund des Piezo-Effektes eine den Schwingungen proportionale elektrische Spannung, wobei aus der Zeitdifferenz zwischen dem Aussenden der Ultraschallwellen und dem Empfang der Echosignale der Abstand des Hindernisses von dem Uitraschaiisensor errechnet werden kann.FIGS. 5 and 6 show a vibrating element 1 of a conventional ultrasonic sensor for parking aids in motor vehicles. The vibrating element 1 is cup-shaped and carries a circular piezo disk 3 on the inside of the bottom surface serving as membrane 2. The piezo disk 3 is excited to vibrate for a certain time phase by an applied electrical voltage, so that 2 ultrasonic waves are emitted via the outside of the membrane , After reflection from an obstacle in the subsequent microphone phase of the sensor, these ultrasonic waves are received by the membrane 2 as echo signals and transmitted in the form of vibrations to the piezo disk 3. To the Disc sides of the piezo disc 3 create an electrical voltage proportional to the vibrations due to the piezo effect, the distance of the obstacle from the Uitraschaiis sensor being able to be calculated from the time difference between the transmission of the ultrasonic waves and the reception of the echo signals.
Ein Uitraschaiisensor mit dem in den Figuren 5 und 6 gezeigten Aufbau besitzt ein im wesentlichen keulenförmiges Schall-Richtdiagramm, das im Vertikalschnitt (Z-Schnitt) quer zur Längsachse des Ultraschallsensors eine weitestgehend rotationssymmetrische Form aufweist (vgl. Figuren 7 und 8). Ein derartiges Schall-Richtdiagramm hat jedoch den Nachteil, daß bei größeren Keulenformen unerwünschte Echowirkungen, insbesondere Bodenechos entstehen. Wird die keulenförmige Ausdehnung des Schall- Richtdiagramm durch entsprechende Verringerung der Schalleistung verkleinert, verkleinert sich auch der Detektionsbereich des Ultraschallsensors in horizontaler Richtung, was inakzeptable Detektionslücken zur Folge hat.A Uitraschaiisensor with the construction shown in FIGS. 5 and 6 has an essentially club-shaped sound directional diagram, which has a largely rotationally symmetrical shape in vertical section (Z-section) transverse to the longitudinal axis of the ultrasonic sensor (see FIGS. 7 and 8). However, such a sound directional diagram has the disadvantage that undesirable echo effects, in particular ground echoes, occur with larger lobe shapes. If the lobe-shaped expansion of the sound directional diagram is reduced by a corresponding reduction in the sound power, the detection range of the ultrasonic sensor is also reduced in the horizontal direction, which results in unacceptable detection gaps.
Das in den Figuren 1 und 2 schematisch dargestellte Schwingelement 4 eines erfindungsgemäßen Ultraschallsensors ist ebenfalls topfförmig ausgebildet. Das Schwingelement 4 weist eine umlaufende zylindrische Seitenwand und eine als Membran 5 dienende Bodenfläche auf. An der Innenseite dieser Membran 5 sind im Gegensatz zu der Membran 2 des in den Figuren 5 und 6 gezeigten Schwingelements 1 zwei piezoelektrische Biegewandler 6, 7 befestigt. Die nebeneinander angeordneten kreisscheibenförmig ausgebildeten Wandler 6, 7 werden während des Sendebetriebs des Ultraschalisensors parallel und in derselben Schwingrichtung zum Schwingen angeregt und geben in der anschließenden Mikrofonphase die empfangenen Echosignale parallel als elektrische Ausgangsspannung wieder. Die Ansteuerung der Biegewandler 6, 7 erfolgt mittels eines kleinen elektrischen Transformators (nicht gezeigt). Es ist zu erkennen, daß die beiden scheibenförmigen piezoelektrischen Wandler 6, 7 mit geringfügigem Abstand zueinander sowie zur umlaufenden Seitenwand des topfförmigen Schwingelements 4 angeordnet sind.The vibrating element 4 of an ultrasonic sensor according to the invention, which is shown schematically in FIGS. 1 and 2, is likewise pot-shaped. The oscillating element 4 has a circumferential cylindrical side wall and a bottom surface serving as a membrane 5. In contrast to the membrane 2 of the oscillating element 1 shown in FIGS. 5 and 6, two piezoelectric bending transducers 6, 7 are fastened to the inside of this membrane 5. The transducers 6, 7, which are arranged next to one another in the form of a circular disk, are excited to vibrate in parallel and in the same direction of vibration during the transmission operation of the ultrasound sensor and, in the subsequent microphone phase, reproduce the received echo signals in parallel as an electrical output voltage. The bending transducers 6, 7 are controlled by means of a small electrical transformer (not shown). It can be seen that the two disk-shaped piezoelectric transducers 6, 7 are arranged at a slight distance from one another and from the peripheral side wall of the pot-shaped vibrating element 4.
Zur Verstärkung der Asymmetrie des Sensorrichtdiagramms ist das Schwingeiement 4 innenseitig mit zwei bogenförmig ausgebildeten Blenden 8, 9 versehen, die beabstandet zu der Membran 5 angeordnet sind. Die Blenden 8, 9 sind dabei so angeordnet, daß sie die piezoelektrischen Wandler 6, 7 nicht überdecken. Alternativ zu den Blenden oder zusätzlich dazu kann das topfförmige Schwingelement auch eine oder mehrere Ausnehmungen und/oder Rippen aufweisen, die vorzugsweise auf der Innenseite und/oder der Außenseite der Membran angeordnet sind.In order to reinforce the asymmetry of the sensor directional diagram, the oscillating element 4 is provided on the inside with two arcuate diaphragms 8, 9 which are arranged at a distance from the membrane 5. The diaphragms 8, 9 are arranged so that they do not cover the piezoelectric transducers 6, 7. As an alternative to or in addition to the screens, the cup-shaped oscillating element can also have one or more recesses and / or ribs, which are preferably arranged on the inside and / or outside of the membrane.
In den Figuren 3 und 4 ist ein typisches Schall-Richtdiagramm eines Ultraschallsensors mit einem Schwingelement gemäß den Figuren 1 und 2 dargestellt, wobei die Fig. 3 einen Horizontalschnitt (Z-Schnitt) und Fig. 4 einen Vertikalschnitt (Y-Schnitt) quer zur Längsachse des topfförmigen Schwingelements darstellt. Insbesondere anhand der Fig. 4 läßt sich die große asymmetrische Wirkung des erfindungsgemäßen Ultraschallsensors erkennen.FIGS. 3 and 4 show a typical sound directional diagram of an ultrasonic sensor with a vibrating element according to FIGS. 1 and 2, with FIG. 3 a horizontal section (Z section) and FIG. 4 a vertical section (Y section) transverse to Longitudinal axis of the pot-shaped vibrating element. The large asymmetrical effect of the ultrasonic sensor according to the invention can be seen in particular from FIG. 4.
Die Erfindung ist nicht auf das vorstehend beschriebene Ausführungsbeispiel beschränkt. Vielmehr ist eine Anzahl von Varianten denkbar. So können beispielsweise auch drei oder noch mehr piezoelektrische Wandler auf der Membran 5 befestigt sein. Des weiteren können anstelle von kreisrunden auch ovale, rechteckige oder unsymmetrische piezoelektrische Wandler zum Einsatz kommen.The invention is not restricted to the exemplary embodiment described above. Rather, a number of variants are conceivable. For example, three or more piezoelectric transducers can also be attached to the membrane 5. Furthermore, oval, rectangular or asymmetrical piezoelectric transducers can also be used instead of circular ones.
Ferner können die piezoelektrischen Wandler 6, 7 des erfindungsgemäßen Ultraschalisensors im Sendebetrieb nicht nur parallel und in der selben Schwingungsrichtung schwingen. Nach einer vorteilhaften Ausgestaltung können die piezoelektrischen Wandler 6, 7 auch separat und insbesondere phasenverschoben angesteuert werden. Eine solche Ansteuerung ermöglicht die Erzeugung besonders ausgebildeter Schall- Richtdiagramme und kann daher in gewissen Situationen signifikante Vorteile bringen. Furthermore, the piezoelectric transducers 6, 7 of the ultrasound sensor according to the invention can not only vibrate in parallel and in the same direction of vibration in the transmission mode. According to an advantageous embodiment, the piezoelectric transducers 6, 7 can also be controlled separately and in particular out of phase. Such control enables the generation of specially designed sound directional diagrams and can therefore bring significant advantages in certain situations.

Claims

PAT E N TA N S P R U C H E PAT EN TA NSPRUCHE
1. Uitraschaiisensor, insbesondere für Einparkhilfen in Kraftfahrzeugen, mit einem topfförmigen Schwingelement (4), dessen Boden als Membran (5) dient, dadurch gekennzeichnet, daß an der Membran (5) mindestens zwei scheibenförmige piezoelektrische Wandler (6, 7) nebeneinander befestigt sind.1. Uitraschaiisensor, in particular for parking aids in motor vehicles, with a cup-shaped oscillating element (4), the bottom of which serves as a membrane (5), characterized in that at least two disk-shaped piezoelectric transducers (6, 7) are fastened next to one another on the membrane (5) ,
2. Uitraschaiisensor nach Anspruch 1 , dadurch gekennzeichnet, daß die piezoelektrischen Wandler (6, 7) während des Sendebetriebs des Sensors parallel und in der selben Schwingrichtung schwingen.2. Uitraschaiisensor according to claim 1, characterized in that the piezoelectric transducers (6, 7) vibrate in parallel and in the same direction of vibration during the transmission operation of the sensor.
3. Uitraschaiisensor nach Anspruch 1 , dadurch gekennzeichnet, daß den piezoelektrischen Wandlern (6, 7) eine Einrichtung zugeordnet ist, durch die die Wandler (6, 7) separat angesteuert werden.3. Uitraschaiisensor according to claim 1, characterized in that the piezoelectric transducers (6, 7) is assigned a device through which the transducers (6, 7) are controlled separately.
4. Uitraschaiisensor nach Anspruch 1 oder 3, dadurch gekennzeichnet, daß den piezoelektrischen Wandlern (6, 7) eine Einrichtung zugeordnet ist, durch die die Wandler (6, 7) phasenverschoben angesteuert werden.4. Uitraschaiisensor according to claim 1 or 3, characterized in that the piezoelectric transducers (6, 7) is assigned a device through which the transducers (6, 7) are driven out of phase.
5. Uitraschaiisensor nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß die piezoelektrischen Wandler (6, 7) kreisscheibenförmig ausgebildet sind.5. Uitraschaiisensor according to one of claims 1 to 4, characterized in that the piezoelectric transducers (6, 7) are circular disk-shaped.
6. Uitraschaiisensor nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß die piezoelektrischen Wandler oval ausgebildet sind.6. Uitraschaiisensor according to one of claims 1 to 5, characterized in that the piezoelectric transducers are oval.
7. Uitraschaiisensor nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, daß die piezoelektrischen Wandler rechteckig ausgebildet sind.7. Uitraschaiisensor according to one of claims 1 to 6, characterized in that the piezoelectric transducers are rectangular.
8. Uitraschaiisensor nach einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, daß die piezoelektrischen Wandler eine unsymmetrische Form aufweisen.8. Uitraschaiisensor according to one of claims 1 to 7, characterized in that the piezoelectric transducers have an asymmetrical shape.
9. Uitraschaiisensor nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, daß das topfförmige Schwingelement (4) eine oder mehrere Ausnehmungen, Rippen und/oder Blenden (8, 9) aufweist. 9. Uitraschaiisensor according to any one of claims 1 to 8, characterized in that the cup-shaped oscillating element (4) has one or more recesses, ribs and / or screens (8, 9).
EP01903687A 2000-02-26 2001-02-01 Ultrasound sensor having a pot-shaped oscillating element Ceased EP1173842A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10009129A DE10009129A1 (en) 2000-02-26 2000-02-26 Ultrasonic sensor has pot-shaped vibration element whose floor acts as membrane with at least two disc-shaped piezoelectric transducers attached to membrane and adjacent to each other
DE10009129 2000-02-26
PCT/EP2001/001075 WO2001063595A1 (en) 2000-02-26 2001-02-01 Ultrasound sensor having a pot-shaped oscillating element

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