WO1991005331A1 - Electroacoustic unit for generating high sonic and ultrasonic intensities in gases and interphases - Google Patents

Electroacoustic unit for generating high sonic and ultrasonic intensities in gases and interphases Download PDF

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Publication number
WO1991005331A1
WO1991005331A1 PCT/ES1990/000033 ES9000033W WO9105331A1 WO 1991005331 A1 WO1991005331 A1 WO 1991005331A1 ES 9000033 W ES9000033 W ES 9000033W WO 9105331 A1 WO9105331 A1 WO 9105331A1
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WIPO (PCT)
Prior art keywords
equipment according
previous
electroacoustic equipment
load
electroacoustic
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PCT/ES1990/000033
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Spanish (es)
French (fr)
Inventor
Juan Antonio Gallego Juarez
Germán RODRIGUEZ CORRAL
José Luis SAN EMETERIO PRIETO
Fausto Montoya Vitini
Original Assignee
Consejo Superior Investigaciones Cientificas
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Application filed by Consejo Superior Investigaciones Cientificas filed Critical Consejo Superior Investigaciones Cientificas
Priority to DE69011085T priority Critical patent/DE69011085T2/en
Priority to EP19900915472 priority patent/EP0450030B1/en
Publication of WO1991005331A1 publication Critical patent/WO1991005331A1/en
Priority to US08/006,040 priority patent/US5299175A/en

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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
    • B06B3/00—Methods or apparatus specially adapted for transmitting mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B3/04—Methods or apparatus specially adapted for transmitting mechanical vibrations of infrasonic, sonic, or ultrasonic frequency involving focusing or reflecting
    • 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
    • B06B1/0207—Driving circuits
    • B06B1/0223—Driving circuits for generating signals continuous in time
    • B06B1/0238—Driving circuits for generating signals continuous in time of a single frequency, e.g. a sine-wave
    • B06B1/0246—Driving circuits for generating signals continuous in time of a single frequency, e.g. a sine-wave with a feedback signal
    • B06B1/0253—Driving circuits for generating signals continuous in time of a single frequency, e.g. a sine-wave with a feedback signal taken directly from the generator circuit
    • 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 object of this patent is an electroacoustic equipment for the efficient generation of high acoustic intensities in gaseous media and at interfaces (gas-solid, gas-liquid).
  • Aerodynamic systems such as whistles and sirens, in which energy is supplied by a gas stream.
  • the acoustic powers achieved with these systems can be high, however the yields that are obtained are generally low, the acoustic signals emitted are complex and present difficulties in reaching ultrasonic frequencies. Aerodynamic systems also have the disadvantage that, together with acoustic radiation, a large amount of gas from the emitter is propagated.
  • ac ⁇ high intensity acoustic wave generators are electromagnetic, magnetostrictive or piezoelectric, working with solid emitters vibrating longitudinally with which, they present notable limitations in geography (to avoid transverse modes), as well as to achieve high yields and high displacements .
  • the most recent attempts try to use flat radiators vibrating flexurally. This allows to increase the radiant surface, increasing the radiation intensity (which is proportional to the surface of the radiator), and achieving high displacements.
  • the great problem of these systems comes from the phase cancellation that occurs due to the zones that vibrate in contraphase on both sides of a nodal line.
  • the present invention relates to equipment Electroacoustic consisting of a transduction system and its electronic power device.
  • the radiating element is of the flexional type but has a discontinuous profile structure.
  • it is possible to modify the amplitude of the vibration and the phase of the radiation so that all the vibrant zones contribute directly to the construction of the acoustic field with a configuration that can be previously established.
  • two different configurations of the acoustic field can be obtained, in correspondence with the different profile of each of its faces.
  • prototypes for frequencies of approximately 20 KHz have been developed with which, with a single transducer, a directional field of a beam width (at 3 dB) less than 3 degrees is achieved by one of the faces of the radiating element, and a field strongly focused on an axial cylindrical volume about 10 cm long and less than 2 c wide on the other side.
  • Figure 1 presents the directivity diagram of the transducer radiating from its directional face
  • Figure 2 shows the axial and transverse distribution (in focus) of the acoustic field emitted by the focusing face.
  • P represents the amplitude of the acoustic pressure in relative units and D the distance in centimeters.
  • the transduction system ( Figure 3) is essentially constituted by a transduction element (1), which can be piezoelectric or magnetostrictive, a mechanical vibration amplifier (2), which can be exponentially, stepped, conical or catenoidal, and a plate-shaped radiator with a discontinuous profile on both sides (3).
  • the longitudinal vibration generated by the transduction element and amplified by the mechanical amplifier serves to excite the radiating element in one of its flexural modes.
  • the radiating element can have any geometric shape and vibrate in any of its vibration modes.
  • the discontinuous profile is obtained by displacing, in the direction perpendicular to the middle plane of the element, the internodal areas that are considered necessary.
  • the obtaining of directional fields is achieved by alternately displacing the internodal crowns in half a wavelength of the radiation in the middle, in order to phase the entire beam.
  • the focused fields are obtained by displacing the internal crowns so that the distance from the center of said zones to the focal point is such that the radiation arrives in phase at said point located in the near field of the radiator. It is evident that by varying the length of displacement of the internal crowns suitably, virtually any desired distribution of the acoustic field can be achieved.
  • radiators with double discontinuous profile apart from the utility of having two configurations of the acoustic field, favors in lines
  • mass distribution results from mass distribution.
  • This translates into a greater power capacity of transducer systems that, in the structure presented here, is given by the maximum amplitude of vibration that can develop the radius without breaking.
  • the radiators presented here must be constructed of metals or metal alloys that, with those of titanium, have good vibratory characteristics with high mechanical resistance.
  • the three basic parts that constitute it have to be well tuned to the working frequency.
  • the system is highly resonant and, given that due to the conditions of the medium or heating, the frequency may vary over time, an electronic excitation device with very specific requirements is required.
  • the generator system in addition to producing at each moment a signal whose frequency is within a very narrow band (corresponding to the resonance range of the emitter used), is able to automatically correct the value of said frequency by adapting it to the slippage produced in the emitter resonance band, as the reactive mechanical load associated with it varies for different conditions of the radiated medium and the emitting device itself.
  • Ultrasonic transducer by means of a tuned bridge circuit, a phase shifter, a limiter, and a bandpass filter. These types of systems have a fairly critical behavior, especially in the initial moments of the emission, also specifying the use of components
  • the generator object of the present patent introduces a new procedure for monitoring the frequency of
  • the procedure is based on the fact that a piezoelectric sonic or ultrasonic emitter has a
  • Sonic and ultrasonic transducers also show considerable resistance variations depending on the temperature of the ceramic, which changes widely during operation due to heating.
  • the system described also incorporates a circuit for measuring the power delivered by the transducer to its load and stabilization.
  • the generator system consists of the following fundamental steps: a) An impedance transformer that reduces the impedance of the transducer to 50 ⁇ . b) A compensation reactance of the parasitic capacity of the transducer. c) A power amplifier suitable for requiring 50 ⁇ loads. d) A channel for taking a sample of the current signal in the load. e) A channel for taking a sample of the output voltage of the power amplifier. f) A PLL (Phase Looked Loop) circuit for generating the power amplifier exciter signal, with a frequency equal to the transducer resonance frequency. g) A circuit measuring the power delivered to the load, h) A circuit controlling the power delivered to the load.
  • each of these stages is described individually as well as their interrelation: a)
  • the IT transformer is much wider in band than the resonance frequency range in which the transducer moves, introducing a negligible offset.
  • the transformation ratio is such that the impedance of the primary is 50 ⁇ , when loaded with the cold transducer.
  • the 50 ⁇ impedance has been chosen to be able to adapt to the impedance of ordinary 50 ⁇ transmission lines, which will link the transformer and the amplifier.
  • the main ones are far from each other, and therefore they need to be joined by an adapted transmission line.
  • the compensation reactance Ll resonates at the working frequency of the transducer with the parasitic electrical capacity of the transducer, compensating for the damaging offset that it could introduce.
  • the power amplifier is capable of delivering appropriate power to each application. Its design is common must be adapted to require 50 ⁇ loads. The offset entered between the input and output signals must be null.
  • the channel for taking a sample of the current d signal in the load is formed by the resistance Rl qu that is in series with the amplifier load and that e of a value well below 50 ⁇ , so that no appreciably modifying the load impedance and the voltage that appears in its bums is proportional to the current d in the load. The signal obtained serves both for frequency control and for power control.
  • the channel for taking a sample of the output voltage of the power amplifier is formed by a voltage divider that takes a small fraction of it, built with resistors R2 and R3. The signal obtained is used for power control.
  • the PLL (Phase Looked Loop) circuit is of the cobus type. It is composed of a VCO (Voltage controlled oscillator), a four quadrant multiplier acting as a MI phase comparator and a low pass filter, formed by the resistor R6 and the capacitor C3.
  • the VCO has two outputs, one square waveform to attack the phase comparator and another sine waveform to attack the amplifier, both outputs are set in ⁇ / 2 radians.
  • the other phase comparator input is the output current sample signal.
  • the phase comparator is a four quadrant multiplier, so that the PLL is deceived in the frequency at which the phase difference between the two inputs is ⁇ / 2, as the phase difference between the two outputs of the VCO is also ⁇ / 2 it turns out that the phase at which the voltage and current at the output of the power amplifier is 0 will be maintained.
  • the central working frequency of the VCO is regulated by the resistor R4 and the capacitor Cl.
  • the measuring circuit of the power delivered to the load is formed by a multiplier of four quadrants M2 whose inputs are the voltage and current samples taken at the output of the power amplifier, the product signal is filtered low through resistance R5 and the capacitor C2 so that the output of the filter is proportional to the effective power in the load, h)
  • the control circuit of the power input to the load is formed by a COM ⁇ comparator and a mul four-quadrant M3 typifier, operating as a voltage-controlled attenuator.
  • the comparator finds the difference in magnitude between the effective power in the load and a reference signal REF, the difference between them serves to control -Il ⁇
  • Fig 4.- General block diagram of the electronic generator. It includes the stages of transformation, power amplification, generation, automatic frequency control and power control.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Transducers For Ultrasonic Waves (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
  • Apparatuses For Generation Of Mechanical Vibrations (AREA)

Abstract

New electroacoustic unit for the efficient generation of high sonic and ultrasonic intensities in gas media and in interphases (gas-solid, gas-liquid). Said unit is comprised of an electromechanical transducer system of which the radiating element is a plate (3) having a discontinuous profile and an electronic device for the controlled generation of the electric power signal. The unit is capable of generating acoustic fields of very high intensity with a predetermined configuration. Particularly it is capable of generating with a same transducer system two distinct configurations of the acoustic field. Prototypes for generating directional and focused fields have been developed.

Description

MEMORIA DESCRIPTIVA EQUIPO ELECTROACUS ICO PARA LA GENERACIÓN DE ALTAS INTENSI DADES SÓNICAS Y ULTRASÓNICAS EN GASES E INTERFASES DESCRIPTIVE MEMORY ELECTROACUS ICO EQUIPMENT FOR THE GENERATION OF HIGH INTENSIUM SOUND AND ULTRASONIC DADES IN GASES AND INTERFASES
El objeto de esta patente es un equipo electroacústic para la generación eficiente de altas intensidades acústica en medios gaseosos y en interfases (gas-sólido, gas-liquido) .The object of this patent is an electroacoustic equipment for the efficient generation of high acoustic intensities in gaseous media and at interfaces (gas-solid, gas-liquid).
La generación de ondas sónicas ultrasónicas de alt intensidad en medios gaseosos presenta notables dificultade que van ligadas fundamentalmente a la baja impedancia acústic del medio (producto de la densidad por la velocidad d propagación) y a la elevada absorción del mismo. Por tanto, para conseguir una transmisión eficiente de la energi acústica es preciso un buen acoplamiento entre el sistem emisor y el gas. Además, para alcanzar altas intensidades s requieren elevadas amplitudes de vibración y que el ha acústico sea muy direccional o focalizado.The generation of high intensity ultrasonic sonic waves in gaseous media presents notable difficulties that are fundamentally linked to the low acoustic impedance of the medium (product of the density due to the speed of propagation) and the high absorption thereof. Therefore, to achieve an efficient transmission of acoustic energy, a good coupling between the emitting system and the gas is necessary. In addition, to achieve high intensities s require high amplitudes of vibration and that the acoustic ha is very directional or focused.
Existen diferentes tipos de generadores sónicos y ultrasónicos para uso en gases. La mayoría de ellos son sistemas aerodinámicos, tales como los silbatos y las sirenas, en los que la energia es suministrada por un chorro de gas. Las potencias acústicas alcanzadas con estos sistemas pueden ser elevadas, sin embargo los rendimientos que se obtienen son generalmente bajos, las señales acústicas emitidas son complejas y presentan dificultades para alcanzar frecuencias ultrasónicas. Los sistemas aerodinámicos tienen además la desventaja de que, junto a la radiación acústica, se propaga una gran cantidad de gas procedente del emisor. Otroε generadores de ondas acústicas de alta intensidad son de tipo electromagnético, magnetostrictivo o piezoeléctrico, trabajando con emisores sólidos vibrando longitudinalmente con lo que, presentan notables limitaciones en la geo etria (para evitar modos transversales) , asi como para alcanzar altos rendimientos y elevados desplazamientos. Los más recientes intentos tratan de usar radiadores planos vibrando flexionalmente. Esto permite incrementar la superficie radiante, aumentando la i pedancia de radiación (que es proporcional a la superficie del radiador) , y conseguir desplazamientos elevados. Sin embargo, el gran problema de estos sistemas proviene de la cancelación de fase que se produce por efecto de las zonas que vibran en contrafase a ambos lados de una linea nodal. Existen algunos intentos para evitar este efecto cubriendo con materiales absorbentes aquellas zonas internodales que vibran con la misma fase y dejando libres las zonas alternas que vibran en oposición de fase a las anteriores. Otras estructuras más efectivas tratan de aprovechar todas las zonas vibrantes cubriendo las zonas internodales con materiales que sirvan de adaptadores de impedancia al medio y con un espesor tal que permita corregir en la radiación el desfase que se produce en la vibración. Estos sistemas, aun siendo más efectivos que los citados anteriormente, presentan notables problemas prácticos procedentes de las uniones entre la placa plana y los materiales adicionales que se colocan en las zonas internodales.There are different types of sonic and ultrasonic generators for use in gases. Most of them are aerodynamic systems, such as whistles and sirens, in which energy is supplied by a gas stream. The acoustic powers achieved with these systems can be high, however the yields that are obtained are generally low, the acoustic signals emitted are complex and present difficulties in reaching ultrasonic frequencies. Aerodynamic systems also have the disadvantage that, together with acoustic radiation, a large amount of gas from the emitter is propagated. Other acú high intensity acoustic wave generators are electromagnetic, magnetostrictive or piezoelectric, working with solid emitters vibrating longitudinally with which, they present notable limitations in geography (to avoid transverse modes), as well as to achieve high yields and high displacements . The most recent attempts try to use flat radiators vibrating flexurally. This allows to increase the radiant surface, increasing the radiation intensity (which is proportional to the surface of the radiator), and achieving high displacements. However, the great problem of these systems comes from the phase cancellation that occurs due to the zones that vibrate in contraphase on both sides of a nodal line. There are some attempts to avoid this effect by covering absorbent materials with those internodal zones that vibrate with the same phase and leaving free the alternate zones that vibrate in opposition to the previous phases. Other more effective structures try to take advantage of all the vibrating areas by covering the internals with materials that serve as impedance adapters to the environment and with a thickness that allows to correct in the radiation the gap that occurs in the vibration. These systems, while being more effective than those mentioned above, present notable practical problems arising from the joints between the flat plate and the additional materials that are placed in the internals.
La presente invención se refiere a un equipo electroacústico que consta de un sistema de transducción y u dispositivo electrónico de alimentación. En el sistema d transducción, que puede ser piezoeléctrico o magnetostrictivo, el elemento radiante es de tipo flexional pero posee una estructura de perfil discontinuo. Con este diseño especial, se consigue modificar la amplitud de la vibración y la fase de la radiación de modo que todas las zonas vibrantes contribuyan directamente a la construcción del campo acústico con una configuración que puede ser previamente establecida. Además con un mismo elemento radiante se puede obtener dos diversas configuraciones del campo acústico, en correspondencia con el distinto perfil de cada una de las caras del mismo. En particular se han desarrollado prototipos para frecuencias de aproximadamente 20 KHz con lo que se consigue, con un único transductor, un campo direccional de una anchura del haz (a 3 dB) menor de 3 grados por una de las caras del elemento radiante, y un campo fuertemente focalizado en un volumen cilindrico axial de unos 10 cm de longitud y menos de 2 c de anchura por la otra cara. La Figura 1 presenta el diagrama de directividad del transductor radiando por su cara direccional, mientras que la Figura 2 presenta la distribución axial y transversal (en el foco) del campo acústico emitido por la cara focalizante. P representa la amplitud de la presión acústica en unidades relativas y D la distancia en centímetros.The present invention relates to equipment Electroacoustic consisting of a transduction system and its electronic power device. In the transduction system, which can be piezoelectric or magnetostrictive, the radiating element is of the flexional type but has a discontinuous profile structure. With this special design, it is possible to modify the amplitude of the vibration and the phase of the radiation so that all the vibrant zones contribute directly to the construction of the acoustic field with a configuration that can be previously established. In addition with the same radiant element, two different configurations of the acoustic field can be obtained, in correspondence with the different profile of each of its faces. In particular, prototypes for frequencies of approximately 20 KHz have been developed with which, with a single transducer, a directional field of a beam width (at 3 dB) less than 3 degrees is achieved by one of the faces of the radiating element, and a field strongly focused on an axial cylindrical volume about 10 cm long and less than 2 c wide on the other side. Figure 1 presents the directivity diagram of the transducer radiating from its directional face, while Figure 2 shows the axial and transverse distribution (in focus) of the acoustic field emitted by the focusing face. P represents the amplitude of the acoustic pressure in relative units and D the distance in centimeters.
El sistema de transducción (Figura 3) está constituido esencialmente por un elemento de transducción (1) , que puede ser piezoeléctrico o magnetostrictivo, un amplificador mecáni¬ co de la vibración (2) , que puede ser de forma exponencial, escalonada, cónica o catenoidal, y un radiador en forma de placa de perfil discontinuo en sus dos caras (3) . La vibración longitudinal generada por el elemento de transducción y ampli¬ ficado por el amplificador mecánico, sirve para excitar al elemento radiante en uno de sus modos flexionales. Aunque en general resulta útil emplear formas circulares y modos de vibración axisimétricos, el elemento radiante puede tener cualquier forma geométrica y vibrar en cualquiera de sus modos de vibración. El perfil discontinuo se obtiene desplazando, en la dirección perpendicular al plano medio del elemento, las zonas internodales que se consideren necesarias. En el caso de elementos circulares vibrando en modos axisimétricos, la obtención de campos direccionales se consigue desplazando alternativamente las coronas internodales en media longitud de onda de la radiación en el medio, con el fin de poner en fase todo el haz. Asimismo los campos focalizados se obtienen desplazando las coronas internodales de modo que la distancia desde el centro de dichas zonas al punto focal sea tal que la radiación llegue en fase a dicho punto situado en el campo próximo del radiador. Es evidente que variando la longitud del desplazamiento de las coronas internodales adecuadamente se puede conseguir prácticamente cualquier distribución del campo acústico que se desee.The transduction system (Figure 3) is essentially constituted by a transduction element (1), which can be piezoelectric or magnetostrictive, a mechanical vibration amplifier (2), which can be exponentially, stepped, conical or catenoidal, and a plate-shaped radiator with a discontinuous profile on both sides (3). The longitudinal vibration generated by the transduction element and amplified by the mechanical amplifier serves to excite the radiating element in one of its flexural modes. Although it is generally useful to use circular shapes and axisymmetric vibration modes, the radiating element can have any geometric shape and vibrate in any of its vibration modes. The discontinuous profile is obtained by displacing, in the direction perpendicular to the middle plane of the element, the internodal areas that are considered necessary. In the case of circular elements vibrating in axisimetric modes, the obtaining of directional fields is achieved by alternately displacing the internodal crowns in half a wavelength of the radiation in the middle, in order to phase the entire beam. Likewise, the focused fields are obtained by displacing the internal crowns so that the distance from the center of said zones to the focal point is such that the radiation arrives in phase at said point located in the near field of the radiator. It is evident that by varying the length of displacement of the internal crowns suitably, virtually any desired distribution of the acoustic field can be achieved.
La construcción de radiadores con doble perfil discontinuo, aparte de la utilidad que representa disponer de dos configuraciones del campo acústico, favorece en lineas generales una distribución más homogénea de las amplitudes d vibración, en comparación con un radiador plano, com consecuencia de la distribución de masas. Esto se traduce e una mayor capacidad de potencia de los sistemas transductore que, en la estructura que aqui se presenta, viene dada por l máxima amplitud de vibración que puede desarrolar el radiado sin romperse. A este fin los radiadores que aqui se presenta deben construirse en metales o aleaciones metálicas que, com las de titanio, presenten buenas caracteristicas vibratorias alta resistencia mecánica.The construction of radiators with double discontinuous profile, apart from the utility of having two configurations of the acoustic field, favors in lines In general, a more homogeneous distribution of the amplitudes of vibration, compared to a flat radiator, results from mass distribution. This translates into a greater power capacity of transducer systems that, in the structure presented here, is given by the maximum amplitude of vibration that can develop the radius without breaking. To this end, the radiators presented here must be constructed of metals or metal alloys that, with those of titanium, have good vibratory characteristics with high mechanical resistance.
Para conseguir un máximo rendimiento en el sistema de transducción, las tres partes básicas que lo constituyen tienen que ser bien sintonizadas a la frecuencia de trabajo. Como consecuencia el sistema resulta altamente resonante y, dado que por las condiciones del medio o por calentamientos la frecuencia puede variar con el tiempo, se precisa un dispositivo electrónico de excitación con requisitos muy específicos.To achieve maximum performance in the transduction system, the three basic parts that constitute it have to be well tuned to the working frequency. As a consequence, the system is highly resonant and, given that due to the conditions of the medium or heating, the frequency may vary over time, an electronic excitation device with very specific requirements is required.
Por tanto, el sistema generador, además de producir en cada instante una señal cuya frecuencia se sitúa dentro de una banda muy estrecha (correspondiente al margen de resonancia del emisor utilizado) , es capaz de corregir automáticamente el valor de dicha frecuencia adaptándolo al deslizamiento producido en la banda de resonancia del emisor, a medida que varia la carga mecánica reactiva asociada a éste para distintas condiciones del medio radiado y del propio dispositivo emisor.
Figure imgf000008_0001
Therefore, the generator system, in addition to producing at each moment a signal whose frequency is within a very narrow band (corresponding to the resonance range of the emitter used), is able to automatically correct the value of said frequency by adapting it to the slippage produced in the emitter resonance band, as the reactive mechanical load associated with it varies for different conditions of the radiated medium and the emitting device itself.
Figure imgf000008_0001
-6--6-
Los sistemas utilizados actualmente para la exicitación de este tipo de transductores están basados en montajes osciladores de tipo analógico, constituidos por un amplificador de potencia realimentado a partir del propioThe systems currently used for the excitation of this type of transducers are based on oscillator assemblies of analog type, constituted by a power amplifier fed back from the own
5 transductor ultrasónico mediante un circuito puente sintonizado, un defasador, un limitador, y un filtro de paso de banda. Este tipo de sistemas presentan un comportamiento bastante critico, sobre todo en los instantes iniciales de la emisión, precisando además la utilización de componentes5 Ultrasonic transducer by means of a tuned bridge circuit, a phase shifter, a limiter, and a bandpass filter. These types of systems have a fairly critical behavior, especially in the initial moments of the emission, also specifying the use of components
10 de una precisión muy elevada, asi como la inclusión de varios puntos de ajuste, que han de ser ajustados individualmente para cada emisor ultrasónico diferente que se conecte.10 of very high precision, as well as the inclusion of several setpoints, which have to be adjusted individually for each different ultrasonic emitter that is connected.
El generador objeto de la presente patente introduce un nuevo procedimiento para el seguimiento de la frecuencia deThe generator object of the present patent introduces a new procedure for monitoring the frequency of
15 resonancia del emisor, que no precisa la introducción del transductor en el laza de realimentación el circuito oscilador.15 emitter resonance, which does not require the introduction of the transducer in the feedback loop of the oscillator circuit.
El procedimiento está basado en el hecho de que un emisor sónico o ultrasónico de tipo piezoeléctrico presenta unaThe procedure is based on the fact that a piezoelectric sonic or ultrasonic emitter has a
20 impedancia eléctrica puramente resistiva cuando vibra en el punto central de su banda de resonancia (bajo el supuesto de que se haya realizado la compensación de la componente reactiva asociada a la propia capacidad interelectródica del transductor) . Cuando el punto de funcionamiento se aleja20 purely resistive electrical impedance when it vibrates at the central point of its resonance band (under the assumption that the reactive component compensation associated with the transducer's own inter-electrode capacity has been performed). When the operating point moves away
25 (aunque cuando sea levemente) de la resonancia, aparece rápidamente una componente reactiva considerable. Como consecuencia de ello, únicamente a la frecuencia de resonancia presentarán un desfase nulo las señales de tensión e intensidad en el transductor25 (although slightly) of the resonance, a considerable reactive component appears rapidly. As a consequence, only at the resonant frequency will the voltage signals e transducer intensity
Por tanto, bastará que el generador acomode la frecuencia de la señal al punto en que dicho desfase se anula para que se produzca la resonancia.Therefore, it will be sufficient for the generator to accommodate the frequency of the signal to the point where said offset is canceled so that resonance occurs.
Este método presenta una serie de ventajas sobre los comentados anteriormente: a) No es preciso introducir el transductor en la cadena de realimentación del sistema, lo cual redunda en una mayor estabilidad de la amplitud de la señal excitadora. b) La realización del dispositivo electrónico no necesita la utilización de componentes de alta precisión. c) Finalmente, el funcionamiento del sistema en el punto de resonancia resulta ser muy estable, adaptándose fielmente a los deslizamientos de banda provocados por variaciones de las características del medio en el que radia el emisor.This method has a series of advantages over those mentioned above: a) It is not necessary to introduce the transducer into the system feedback chain, which results in greater stability of the amplitude of the exciter signal. b) The realization of the electronic device does not require the use of high precision components. c) Finally, the operation of the system at the resonance point turns out to be very stable, adapting faithfully to the band landslides caused by variations in the characteristics of the medium in which the emitter radiates.
Los transductores sónicos y ultrasónicos también presentan considerables variaciones de resistencia en función de la temperatura de la cerámica, la cual cambia ampliamente durante el funcionamiento debido al calentamiento. El sistema descrito también incorpora un circuito de medida de la potencia entregada por el transductor a la carga y estabilización de ésta.Sonic and ultrasonic transducers also show considerable resistance variations depending on the temperature of the ceramic, which changes widely during operation due to heating. The system described also incorporates a circuit for measuring the power delivered by the transducer to its load and stabilization.
Tal como se expone en el diagrama de bloques de la Fig. 4, el sistema generador consta de las etapas fundamentales siguientes: a) Un transformador de impedancias que reduce la impedancia del transductor a 50 Ω. b) Una reactancia de compensación de la capacidad parásita del transductor. c) Un amplificador de potencia adecuado para exicitar cargas de 50 Ω. d) Un canal para la toma de una muestra de la señal de corriente en la carga. e) Un canal para la toma de una muestra de la tensión de salida del amplificador de potencia. f) Un circuito PLL (Phase Looked Loop) para la generación de la señal excitadora del amplificador de potencia, con una frecuencia igual a la frecuencia de resonancia del transductor. g) Un circuito medidor de la potencia entregada a la carga, h) Un circuito controlador de la potencia entregada a la carga.As shown in the block diagram of Fig. 4, the generator system consists of the following fundamental steps: a) An impedance transformer that reduces the impedance of the transducer to 50 Ω. b) A compensation reactance of the parasitic capacity of the transducer. c) A power amplifier suitable for requiring 50 Ω loads. d) A channel for taking a sample of the current signal in the load. e) A channel for taking a sample of the output voltage of the power amplifier. f) A PLL (Phase Looked Loop) circuit for generating the power amplifier exciter signal, with a frequency equal to the transducer resonance frequency. g) A circuit measuring the power delivered to the load, h) A circuit controlling the power delivered to the load.
A continuación se describe individualmente el funcionamiento de cada una de estas etapas asi como su interrelación: a) El transformador TI es de banda mucho más ancha que el margen de frecuencia de resonancia en que se mueve el transductor, introduciendo un defasaje despreciable. La rela¬ ción de transformación es tal que la impedancia que presenta el primario es de 50 Ω, cuando está cargado con el transductor frió. Se ha elegido la impedancia de 50 Ω para poder adaptarse a la impedancia de lineas de transmisión ordinarias de 50 Ω, que unirán el transformador y el amplificador. Dependiendo de la aplicación puede ser necesario que transductor y equipo principal estén muy alejados entre si, y por tanto se requier unirlos por una linea de transmisión adaptada. b) La reactancia de compensación Ll resuena a la frecuenci de trabajo del transductor con la capacidad eléctrica parásit del transductor, compensando el defasaje perjudicial que ést podria introducir. c) El amplificador de potencia es capaz de entregar un potencia apropiada a cada aplicación. Su diseño es común debe estar adaptado para exicitar cargas de 50 Ω. El defasaj introducido entre las señales de entrada y salida ha de se nulo. d) El canal para la toma de una muestra de la señal d corriente en la carga, está formado por la resistencia Rl qu se encuentra en serie con la carga del amplificador y que e de valor muy inferior a 50 Ω, de manera que no modific apreciablemente la impedancia de carga y la tensión qu aparece en sus bomas es proporcional a la intensidad d corriente en la carga. La señal obtenida sirve tanto para el control de frecuencia como para el control de potencia. e) El canal para la toma de una muestra de la tensión de salida del amplificador de potencia está formado por una divisor de tensión que toma una pequeña fracción de ésta, construido con las resistencia R2 y R3. La señal obtenida sirve para el control de potencia. f) El circuito PLL (Phase Looked Loop) es de tipo cóBfün. Está integrado por un VCO (Voltaje controlled oscillator) , un multiplicador de cuatro cuadrantes actuando como comparador de fase MI y un filtro paso bajo, formado por la resistencia R6 y el condensador C3. El VCO tiene dos salidas, una de forma de onda cuadrada para atacar al comparador de fase y otra de forma de onda sinusoidal para atacar al amplificador, ambas salidas están def sadas en π/2 radianes. La otra entrada de comparador de fase es la señal de muestra de corriente de salida. El comparador de fase es un multiplicador de cuatro cuadrantes, de forma que el PLL se engacha en la frecuencia a la que la diferencia de fase entre las dos entradas sea π/2 , como la diferencia de fase entre las dos salidas del VCO es también π/2 resulta que se mantendrá a la frecuencia a la que la fase en que la tensión y la corriente a la salida del amplificador de potencia es 0. La frecuencia central de trabajo del VCO se regula mediante la resistencia R4 y el condensador Cl. g) El circuito medidor de la potencia entregada a la carga está formado por un multiplicador de cuatro cuadrantes M2 cuyas entradas son las muestras de tensión y corriente tomadas a la salida del amplificador de potencia, la señal producto está filtrada paso bajo mediante la resistencia R5 y el condensador C2 de forma que la salida del filtro es proporcional a la potencia efectiva en la carga, h) El circuito controlador de la potencia entragada a la carga está formado por un comparador COMÍ y un multiplicador de cuatro cuadrantes M3, funcionando como atenuador controlado por tensión. El comparador halla la diferencia de magnitud entre la potencia efectiva en la carga y una señal de referencia REF, la diferencia entre ellas sirve para controlar -Il¬The operation of each of these stages is described individually as well as their interrelation: a) The IT transformer is much wider in band than the resonance frequency range in which the transducer moves, introducing a negligible offset. The transformation ratio is such that the impedance of the primary is 50 Ω, when loaded with the cold transducer. The 50 Ω impedance has been chosen to be able to adapt to the impedance of ordinary 50 Ω transmission lines, which will link the transformer and the amplifier. Depending on the application it may be necessary for transducer and equipment The main ones are far from each other, and therefore they need to be joined by an adapted transmission line. b) The compensation reactance Ll resonates at the working frequency of the transducer with the parasitic electrical capacity of the transducer, compensating for the damaging offset that it could introduce. c) The power amplifier is capable of delivering appropriate power to each application. Its design is common must be adapted to require 50 Ω loads. The offset entered between the input and output signals must be null. d) The channel for taking a sample of the current d signal in the load, is formed by the resistance Rl qu that is in series with the amplifier load and that e of a value well below 50 Ω, so that no appreciably modifying the load impedance and the voltage that appears in its bums is proportional to the current d in the load. The signal obtained serves both for frequency control and for power control. e) The channel for taking a sample of the output voltage of the power amplifier is formed by a voltage divider that takes a small fraction of it, built with resistors R2 and R3. The signal obtained is used for power control. f) The PLL (Phase Looked Loop) circuit is of the cobus type. It is composed of a VCO (Voltage controlled oscillator), a four quadrant multiplier acting as a MI phase comparator and a low pass filter, formed by the resistor R6 and the capacitor C3. The VCO has two outputs, one square waveform to attack the phase comparator and another sine waveform to attack the amplifier, both outputs are set in π / 2 radians. The other phase comparator input is the output current sample signal. The phase comparator is a four quadrant multiplier, so that the PLL is deceived in the frequency at which the phase difference between the two inputs is π / 2, as the phase difference between the two outputs of the VCO is also π / 2 it turns out that the phase at which the voltage and current at the output of the power amplifier is 0 will be maintained. The central working frequency of the VCO is regulated by the resistor R4 and the capacitor Cl. g) The measuring circuit of the power delivered to the load is formed by a multiplier of four quadrants M2 whose inputs are the voltage and current samples taken at the output of the power amplifier, the product signal is filtered low through resistance R5 and the capacitor C2 so that the output of the filter is proportional to the effective power in the load, h) The control circuit of the power input to the load is formed by a COMÍ comparator and a mul four-quadrant M3 typifier, operating as a voltage-controlled attenuator. The comparator finds the difference in magnitude between the effective power in the load and a reference signal REF, the difference between them serves to control -Il¬
la atenuación introducida por el multiplicador M2. Claves de la Gráficathe attenuation introduced by the multiplier M2. Keys of the Graph
Fig 4.- Diagrama general de bloques del generador electrónico. Incluye las etapas de trasformación, amplificación de potencia, generación, control automático de frecuencia y control de potencia. Fig 4.- General block diagram of the electronic generator. It includes the stages of transformation, power amplification, generation, automatic frequency control and power control.

Claims

REIVINDICACIONES
1) EQUIPO ELECTROACUSTICO PARA LA GENERACIÓN DE ALTAS INTENSIDADES SÓNICAS Y ULTRASÓNICAS EN GASES E INTERFASES constituido por un sistema electromecánico de transducción y un dispositivo electrónico para la generación controlada de la señal eléctrica de potencia en el que el equipo electroacústico está caracterizado porque: a) el sistema de transducción está formado por un elemento de transducción, un amplificador mecánico de la vibración y un radiador en forma de placa con perfil discontinuo en sus dos caras. Las tres partes que constituyen el sistema de transducción están sintonizadas para resonar a la frecuencia de trabajo; b) el generador electrónico está formado por un amplificador de potencia, un circuito PLL (Phase looked loop) , un circuito medidor de potencia y un circuito controlador de potencia.1) ELECTRO-ACOUSTIC EQUIPMENT FOR THE GENERATION OF HIGH-SOUND AND ULTRASONIC INTENSITIES IN GASES AND INTERFASES constituted by an electromechanical transduction system and an electronic device for the controlled generation of the electrical power signal in which the electroacoustic equipment is characterized by: a) The transduction system consists of a transduction element, a mechanical vibration amplifier and a plate-shaped radiator with a discontinuous profile on both sides. The three parts that constitute the transduction system are tuned to resonate at the working frequency; b) the electronic generator consists of a power amplifier, a PLL (Phase looked loop) circuit, a power meter circuit and a power controller circuit.
2) Un equipo electroacústico según reivindicación 1 y caracterizado porque el elemento de transducción, puede ser piezoeléctrico o magnetostrictivo, y origina una vibración longitudinal.2) An electroacoustic equipment according to claim 1 and characterized in that the transduction element can be piezoelectric or magnetostrictive, and causes a longitudinal vibration.
3) Un equipo electroacústico según reivindicaciones anteriores caracterizado porque el amplificador mecánico, puede ser de forma exponencial, escalonada, cónica, catenoi- dal u otras similares, y amplifica la vibración generada por el elemento de transducción, excitando el rediador en uno de sus modos flexionales de vibración.3) An electroacoustic equipment according to previous claims characterized in that the mechanical amplifier, can be exponentially, stepped, conical, catenoidal or similar, and amplifies the vibration generated by the transduction element, exciting the router in one of its modes vibrational flexion
4) Un equipo electroacústico según reivindicaciones anteriores y caracterizado porque el elemento radiante está constituido por una placa que puede ser de cualquier forma geométrica (circular, rectangular, cuadrada, etc.) y cuyas dos caras tienen un perfil discontinuo, que se se obtiene desplazando, en la dirección perpendicular al plano medio de la placa, algunas zonas internodales.4) An electroacoustic equipment according to previous claims and characterized in that the radiating element is constituted by a plate that can be of any geometric shape (circular, rectangular, square, etc.) and whose two faces have a discontinuous profile, which is obtained by moving, in the direction perpendicular to the middle plane of the plate, some internals .
5) Un equipo electroacústico según reivindicaciones anteriores y caracterizado porque el número y posición de las zonas internodales que se desplazan asi como la altura o profundidad de los desplazamientos depende de la configúra¬ ción del campo acústico que se desee obtener.5) An electroacoustic equipment according to previous claims and characterized in that the number and position of the internal areas that move as well as the height or depth of the displacements depends on the configuration of the acoustic field that one wishes to obtain.
6) Un equipo electroacústico según reivindicaciones anteriores y caracterizado porque con un mismo radiador se pueden generar dos campos acústico con distinta configuración, en correspondencia de los dos distintos per- files de cada una de las caras.6) An electroacoustic equipment according to previous claims and characterized in that with the same radiator two acoustic fields with different configuration can be generated, corresponding to the two different profiles of each of the faces.
7) Un equipo electroacústico según reivindicaciones anteriores y caracterizado porque la obtención de campos direccionales se consigue, en el caso de radiadores cir¬ culares vibrando en uno de sus modos axisimétricos, desplazando alternativamente las coronas internodales en media longitud de onda de la radiación en el medio.7) An electroacoustic equipment according to previous claims and characterized in that the obtaining of directional fields is achieved, in the case of circular radiators vibrating in one of its axisymmetric modes, alternatively displacing the internal crowns in half a wavelength of the radiation in the medium.
8) Un equipo electroacústico según reinvidaciones ante¬ riores y caracterizado porque la obtención de campos focali¬ zados se consigue, en el caso de radiadores circulares vibrando en uno de sus modos axisimétricos, desplazando las coronas internodales de modo que la distancia desde el centro de dichas zonas al punto focal sea tal que la radiación llegue en fase a dicho punto situado en el campo próximo del radiador.8) An electroacoustic equipment according to previous reinvi- tions and characterized in that the obtaining of focused fields is achieved, in the case of circular radiators vibrating in one of its axisymmetric modes, displacing the internal crowns so that the distance from the center of said zones at the focal point is such that the radiation arrives in phase at said point located in the near field of the radiator.
9) Un equipo electroacústico según reivindicaciones anteriores y caracterizado porque el dispositivo generador electrónico produce en cada instante una señal cuya frecuen¬ cia se sitúa dentro de la banda de resonancia del sistema de transducción, y corrige automáticamente el valor de dicha frecuencia para adaptarlo al deslizamiento que pueda producirse en la banda de resonancia del emisor.9) An electroacoustic equipment according to previous claims and characterized in that the electronic generating device produces at each moment a signal whose frequency is located within the resonance band of the transduction system, and automatically corrects the value of said frequency to adapt it to the slip that may occur in the emitter's resonance band.
10) Un equipo electroacüstico según reivindicaciones anteriores y caracterizado porque el generador electrónico dispone de un amplificador de potencia en el que el deεfasaje introducido entre las señales de entrada y salida es nulo.10) An electroacoustic equipment according to previous claims and characterized in that the electronic generator has a power amplifier in which the gap introduced between the input and output signals is zero.
11) Un equipo electroacústico según reivindicaciones anteriores y caracterizado porque en el generador electrónico el canal para la toma de muestra de la señal de corriente en la carga, está formado por una resistencia, en serie con la carga del amplificador, de valor tal que no modifica aprecia- blemente la impedancia de carga siendo la tensión en sus bornas proporcional a la intensidad de corriente en la carga.11) An electroacoustic equipment according to previous claims and characterized in that in the electronic generator the channel for the sampling of the current signal in the load, is formed by a resistor, in series with the amplifier load, of value such that no appreciably modifies the load impedance with the voltage at its terminals proportional to the current in the load.
12) Un equipo electroacústico según reivindicaciones anteriores y caracterizado porque en el generador electrónico se toma una muestra de la tensión de salida del amplificador de potencia mediante divisor de tensión para controlar la potencia.12) An electroacoustic equipment according to previous claims and characterized in that in the electronic generator a sample of the output voltage of the power amplifier is taken by means of a voltage divider to control the power.
13) Un equipo electroacústico según reivindicaciones anteriores y caracterizado porque el generador electrónico incluye un circuito PLL (Phase looked loop) integrado por un oscilador controlado por voltaje, un multiplicador de cuatr cuadrantes actuando como comparador de fase y un filtro pas bajo.13) An electroacoustic equipment according to previous claims and characterized in that the electronic generator includes a PLL (Phase looked loop) circuit composed of a voltage controlled oscillator, a quad quadrant multiplier acting as a phase comparator and a low pass filter.
14) Un equipo electroacústico según reivindicacione anteriores y caracterizado porque el oscilador controlado po voltaje del generador electrónico tiene dos salidas, una d forma de onda cuadrada, que ataca el comparador de fase, otra sinusoidal que ataca al amplificador, ambas desfasadas e π/2 radianes, siendo la otra entrada del comparador de fase 0 la señal de muestra de corriente de salida.14) An electroacoustic equipment according to previous claims and characterized in that the oscillator controlled by the voltage of the electronic generator has two outputs, a d-shaped square wave, which attacks the phase comparator, another sinusoidal that attacks the amplifier, both offset and π / 2 radians, the other input of the phase 0 comparator being the output current sample signal.
15) Un equipo electroacústico según reivindicaciones anteriores y caracterizado porque en el generador electrónico el circuito medidor de la potencia entregada a la carga está formado por un multiplicador de cuatro cuadrantes cuyas en- 5 tradas son las muestras de tensión y corriente tomadas a la salida del amplificador de potencia, siendo la señal producto filtrada para bajo paso bajo para obtener una señal propor¬ cional a la potencia efectiva en la carga.15) An electroacoustic equipment according to previous claims and characterized in that in the electronic generator the power measuring circuit delivered to the load is formed by a four quadrant multiplier whose inputs are the voltage and current samples taken at the exit of the power amplifier, the product signal being filtered for low low pass to obtain a signal proportional to the effective load power.
16) Un equipo electroacústico según reivindicaciones o anteriores y caracterizado porque en el generador electrónico, el circuito controlador de la patencia entregada a la carga está formado por un comparador y un multiplicador de cuatro cuadrantes, funcionando como atenuador controlado por tensión. 16) An electroacoustic equipment according to claims or earlier and characterized in that in the electronic generator, the patent control circuit delivered to the load is formed by a comparator and a quadrant multiplier, functioning as a voltage controlled attenuator.
PCT/ES1990/000033 1989-10-06 1990-10-03 Electroacoustic unit for generating high sonic and ultrasonic intensities in gases and interphases WO1991005331A1 (en)

Priority Applications (3)

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DE69011085T DE69011085T2 (en) 1989-10-06 1990-10-03 ELECTROACOUSTIC UNIT FOR EXCITING HIGH-INTENSITY SOUND AND ULTRASOUND IN GASES AND INTERMEDIATE PHASES.
EP19900915472 EP0450030B1 (en) 1989-10-06 1990-10-03 Electroacoustic unit for generating high sonic and ultrasonic intensities in gases and interphases
US08/006,040 US5299175A (en) 1989-10-06 1993-01-19 Electroacoustic unit for generating high sonic and ultra-sonic intensities in gases and interphases

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ES8903371 1989-10-06
ES8903371A ES2017285A6 (en) 1989-10-06 1989-10-06 Electroacoustic unit for generating high sonic and ultrasonic intensities in gases and interphases

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EP0543685A1 (en) * 1991-10-07 1993-05-26 Sollac Method and apparatus for etching edges of a hot rolled plate
DE4418830A1 (en) * 1994-05-30 1995-12-07 Sonident Anstalt Method of generating spherical waves in ultrasonic range
US5828627A (en) * 1994-05-30 1998-10-27 Sonident Anstalt Liechtensteinischen Rechts Method of and apparatus for producing spherical waves in the ultrasonic range

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JP2009502466A (en) * 2005-07-27 2009-01-29 コンセホ・スペリオール・デ・インベスティガシオネス・シエンティフィカス Macro-sonic generator for industrial defoaming of air-based liquids
RU2744826C1 (en) * 2020-03-24 2021-03-16 федеральное государственное бюджетное образовательное учреждение высшего образования "Алтайский государственный технический университет им. И.И. Ползунова" (АлтГТУ) Piezoelectric oscillating system for ultrasonic action on gaseous media

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EP0543685A1 (en) * 1991-10-07 1993-05-26 Sollac Method and apparatus for etching edges of a hot rolled plate
DE4418830A1 (en) * 1994-05-30 1995-12-07 Sonident Anstalt Method of generating spherical waves in ultrasonic range
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DE69011085T2 (en) 1995-03-23
ES2017285A6 (en) 1991-01-16
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ATE109297T1 (en) 1994-08-15
CA2042575C (en) 1995-08-08

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