EP0123277B1 - Method of driving an ultrasonic oscillator for an atomizing fluid - Google Patents

Method of driving an ultrasonic oscillator for an atomizing fluid Download PDF

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Publication number
EP0123277B1
EP0123277B1 EP84104426A EP84104426A EP0123277B1 EP 0123277 B1 EP0123277 B1 EP 0123277B1 EP 84104426 A EP84104426 A EP 84104426A EP 84104426 A EP84104426 A EP 84104426A EP 0123277 B1 EP0123277 B1 EP 0123277B1
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EP
European Patent Office
Prior art keywords
oscillator
time interval
supplied
power
frequency
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Expired
Application number
EP84104426A
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German (de)
French (fr)
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EP0123277A2 (en
EP0123277A3 (en
Inventor
Valentin Dipl.-Phys. Mágori
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Siemens AG
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Siemens AG
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Priority to AT84104426T priority Critical patent/ATE41887T1/en
Publication of EP0123277A2 publication Critical patent/EP0123277A2/en
Publication of EP0123277A3 publication Critical patent/EP0123277A3/en
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Publication of EP0123277B1 publication Critical patent/EP0123277B1/en
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B17/00—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups
    • B05B17/04—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods
    • B05B17/06—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods using ultrasonic or other kinds of vibrations
    • B05B17/0607—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods using ultrasonic or other kinds of vibrations generated by electrical means, e.g. piezoelectric transducers
    • B05B17/0623—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods using ultrasonic or other kinds of vibrations generated by electrical means, e.g. piezoelectric transducers coupled with a vibrating horn
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B17/00—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups
    • B05B17/04—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods
    • B05B17/06—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods using ultrasonic or other kinds of vibrations
    • B05B17/0607—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods using ultrasonic or other kinds of vibrations generated by electrical means, e.g. piezoelectric transducers
    • B05B17/0623—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods using ultrasonic or other kinds of vibrations generated by electrical means, e.g. piezoelectric transducers coupled with a vibrating horn
    • B05B17/063—Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups operating with special methods using ultrasonic or other kinds of vibrations generated by electrical means, e.g. piezoelectric transducers coupled with a vibrating horn having an internal channel for supplying the liquid or other fluent material
    • 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
    • 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
    • B06B2201/00—Indexing scheme associated with B06B1/0207 for details covered by B06B1/0207 but not provided for in any of its subgroups
    • B06B2201/50—Application to a particular transducer type
    • B06B2201/55—Piezoelectric transducer
    • 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
    • B06B2201/00—Indexing scheme associated with B06B1/0207 for details covered by B06B1/0207 but not provided for in any of its subgroups
    • B06B2201/70—Specific application
    • B06B2201/76—Medical, dental
    • 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
    • B06B2201/00—Indexing scheme associated with B06B1/0207 for details covered by B06B1/0207 but not provided for in any of its subgroups
    • B06B2201/70—Specific application
    • B06B2201/77—Atomizers

Definitions

  • the present invention relates to a method according to the preamble of patent claim 1.
  • microinhaler An inhalation device from Siemens with the designation “microinhaler” is commercially available, in which there is a liquid atomizer according to the above-mentioned patent specification. This device also contains an electrical excitation circuit that supplies the AC supply voltage.
  • liquid atomizer of the type mentioned above are e.g. B. the fuel oil atomization for fuel oil burners.
  • an electronic excitation circuit which can operate the oscillator even under unfavorable operating (start-up) conditions in such a way that liquid atomization actually occurs.
  • an unfavorable operating condition is e.g. B. that a drop of liquid adheres to the worktop of the atomizer, which hinders the vibration of this worktop and thus the vibration of the whole ultrasonic vibrator.
  • a high excess of electrically fed continuous power has been provided as a remedy that such excessive damping of the transducer can also be overcome.
  • this has the disadvantage that the oscillator is then destroyed, in particular if the liquid supply fails, because the result is thermal overloading of the oscillator.
  • the invention is based on the consideration that a completely new operating method for such a liquid atomizer must be found in order to solve the problems at hand.
  • the concept of this new method is to feed the oscillator repetitively, in particular periodically, at a relatively low frequency (20 to 100 Hz) instead of continuously, as before, at a relatively high frequency alternating voltage.
  • a high electrical (peak) power is supplied during a first time interval ⁇ t 1 that the vibrator even with strong damping by e.g. B. attached drops swings safely.
  • ⁇ t 2 significantly lower electrical power or no power at all is supplied.
  • the clock ratio of ⁇ t 1 to ⁇ t 2 , the absolute time periods of the time intervals and the values of the electrical power values supplied in the time intervals are dimensioned in such a way that the thermal load on the oscillator resulting from the integrally resulting mean electrical power supply does not become impermissibly high and yet the corresponding amount of liquid is atomized.
  • a particularly advantageous development of the invention is to provide a repetition for the time intervals .DELTA.t 1 and .DELTA.t2, in which groups, each consisting of a plurality of successive cycles corresponding to the time intervals .DELTA.t 1 ', periodically follow one another.
  • the frequency of the succession of the groups is equal to the clock frequency already mentioned with z. B. 20 to 100 Hz selected. With a clock frequency of such a frequency value it can be achieved that a liquid drop adhering to the vibrating worktop - depending on the consistency and adhesive force of the material of this droplet - is caused to oscillate on the surface of this worktop.
  • such a drop of liquid preferably contracts in the center of this worktop.
  • the vibration amplitude or the rest of the worktop decays, it is distributed uniformly up to the edge of the worktop over its entire surface or, if the surface of the worktop is not horizontal, more or less hangs on the edge region of the worktop.
  • This response time constant is z. B. 1 ms for an oscillator with 100 kHz oscillation frequency.
  • the oscillation amplitude of the oscillator does not reach the level of the final amplitude of the oscillation, but the rise stops at a predeterminable value of an upper threshold S.
  • this oscillation then decays to a lower, predefinable threshold value.
  • a sawtooth-like time course of the oscillation amplitude of the oscillator can thus be achieved.
  • the frequency of this electrical signal to be picked up is equal to the natural resonance frequency of the vibrator and can be used for optimal control of the frequency of the excitation AC voltage for the supply in the first time interval ⁇ t 1 .
  • the occurrence of such an electrical signal in the second time interval At 2 is also a control for the oscillation and the atomization function in the first time interval ⁇ t 1 .
  • the level and the time profile - in particular the time constant - of the electrical signal in the time interval ⁇ t 2 is also a measure of the vibration amplitude achieved in the time interval ⁇ t 1 .
  • a lower level of this electrical signal recorded in the time interval ⁇ t 2 indicates stronger damping of the ultrasonic vibrator and thus a relatively large supply of liquid.
  • the supplied electrical feed power can be increased in the time interval ⁇ t, or the amount of liquid supplied per unit of time can be reduced until the electrical signal taken off in the time interval ⁇ t 2 indicates that the liquid atomizer has again achieved the optimum vibration behavior.
  • Fig. 1 denotes the entire ultrasonic vibrator. It is z. B. an ultrasonic transducer according to German patent 20 32 433. This transducer comprises a piezoceramic disk 2 as a piezoelectric converter, to which the electrical excitation voltage is to be applied. With 3 the worktop is designated, on the surface 4 of which the liquid atomization 5 takes place. 6 designates a supply line and 7 designates a pump installed in this supply line for the liquid to be atomized to be supplied to the surface 4.
  • the actual excitation electronics are designated by 11 and reference is made to an additional electronic circuit provided according to a further development, which serves to monitor the operational vibration behavior of the ultrasonic vibrator 1.
  • the electrical power output by the circuit 11 is fed to the converter 2 via the line 13.
  • the circuit 11 is at the terminals 14 z. B. fed with 220 volts AC or 12 volts DC.
  • 15 denotes a connecting line to the circuit 12, namely via which an electrical signal returned by the converter 2 can be fed to this circuit 12 during the meal break in the time interval ⁇ t 2 .
  • the converter 2 has an additional (feedback) electrode which is connected to the circuit 12 via the line 15.
  • the line 16 between the circuits 11 and 12 serve to supply evaluation signals from the circuit 12 to the circuit 11 in order to control them.
  • This control can relate in particular to the frequency f of the excitation AC voltage (for example in the range of 100 kHz), to the upper threshold S, the oscillation amplitude of the oscillator 1 and / or to the lower oscillation amplitude S 2 of the same.
  • the lines 17 indicate control signal outputs of the circuit 12, e.g. B. to a light emitting diode 18, which can serve as an operating signal lamp, and to the pump 7, the control of which from the circuit 12 can always ensure an adapted amount of liquid supply to the surface 4 of the vibrator 1.
  • the diagram in FIG. 2 shows the electrical power N supplied to the converter 2 and thus to the oscillator 1 via the line 13, plotted over time.
  • the clocks 21 with the first time intervals ⁇ t 1 are the actual feed intervals. In these intervals, the vibrator 1 receives such a large electrical power that it itself and thus also the worktop 3 is reliably set in the required ultrasonic vibration, regardless of whether on the surface 4 of the plate 3 a more or less there is a large amount of liquid or a drop adhering to it.
  • electrical power is supplied in accordance with the clocks 22.
  • the power of the clocks 22 can be so high that continuous oscillation continuously causes further atomization 5.
  • the electrical power of the clocks 22 can, however, have the value zero, ie the oscillator 1 is allowed to swing out in the second time intervals ⁇ t 2 .
  • the clock ratio At,: ( ⁇ t 1 + ⁇ t 2 ) is z. B. 4 ms: 20 ms, the latter value advantageously being derived from the mains frequency. It is important for the clock ratio that, together with the power ratio N, to N 2, the permissible mean electrical power to be supplied is not exceeded, but nevertheless safe start-up is always ensured with the power N level.
  • Fig. 3 shows the diagram of the electrical power N, again plotted against the time t, but with groups of - in this example three clocks 37.
  • Each of these clocks 31 has the length of a time interval ⁇ t 1 'of z. B. 1 ms duration.
  • the repetition of these clocks 31 within a group is preferably periodic with the frequency F.
  • the groups 32 consist of the respective number of individual clock cycles 31 and preferably also have periodic repetition with the frequency F 2 .
  • this frequency F 2 is chosen between 10 and 100 Hz, preferably 50 Hz (60 Hz).
  • the sum of the time intervals ⁇ t 1 ′ of an individual group 32 in relation to the period of the repetition frequency F 2 is important for the measure of the mean electrical power already mentioned above.
  • FIG. 4 shows an amplitude curve of the oscillation of the vibrator 1 or the worktop 3 when the excitation power is supplied according to FIG. 3. Since between the last time interval ⁇ t 1 'of one group 32 and the first time interval ⁇ t.' the group 32 is no electric power supply is provided according to Fig. 3, is performed in this time interval At 2 asymptotic decay until the next Wiederanschwingen.
  • the time intervals of the ⁇ t 1 or the time interval in which the time intervals ⁇ t 1 '(FIG. 3) are present, and the time interval ⁇ t 2 then result from the respective operating vibration behavior of the vibrator 1 and are here variable in terms of their length in time over the duration .
  • the time intervals .DELTA.t 1 and .DELTA.t2 are controlled with the aid of the circuit 12, in which a return signal of the vibrator 1 supplied via the line 15 is evaluated.
  • FIG. 6 shows a complete circuit diagram for a circuit 11 for generating the electrical power that feeds the oscillator 1.
  • the repetition frequency is supplied by the generator 61 in this circuit.
  • the circuit part 63 is a driver stage and the transistor 64 is the final stage.
  • the circuit part 65 with the zener diode serves to correct a fluctuation in the supply voltage 66.
  • the further details of the circuit are readily apparent to the person skilled in the art from the circuit diagram.
  • FIG. 7 shows a circuit example for a circuit 12.
  • the circuit part provided for a signal delay and the signal comparator 72 are designated with 71. 'Also this diagram needs no further explanation to the skilled artisan.
  • a pre-pulse is shown at 35, which is supplied to the oscillator 1 before the actual atomizing operation is started.
  • This is preferably a burst pulse (oscillation packet) with advantageously one to twenty oscillations with a frequency that is at least approximately equal to the resonance frequency of the oscillator 1.
  • the pre-pulse triggers an oscillation of the oscillator 1 and its decay oscillation 45 (in FIG. 4), as already described above, is used for the initial control of the frequency f of the alternating excitation voltage to be supplied via the line 13.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Special Spraying Apparatus (AREA)
  • Apparatuses For Generation Of Mechanical Vibrations (AREA)

Abstract

1. Method of driving an ultrasonic oscillator (1) for atomisation of liquid, the oscillator (1) being supplied by excitation electronics (11) having an electrical alternating voltage, the frequency (F2 ) of which can be tuned to the optiomum oscillatory power of the oscillator (1), characterized in that the electrical power (N) supplied is timed to occur in repeated cycles, the power (N1 ) supplied for a first time interval (DELTA t1 ) being rated so high that the starting threshold (E) for actually occuring atomisation of liquid (5) is sufficiently hyghly exceeded even when the condition of operational oscillation build-up is unfavourable, the power (N2 ) supplied for a second time interval (DELTA t2 ) being rated lower by comparison with the time interval (DELTA t1 ), and mean of the power see diagramm : EP0123277,P7,F1 supplied, as averaged over the two time intervals (DELTA t1 , DELTA t2 ) taken together, being matched to the quantitity of liquid (7) which is fed per unit time and is to be atomised.

Description

Die vorliegende Erfindung bezieht sich auf ein Verfahren nach dem Oberbegriff des Patentanspruchs 1.The present invention relates to a method according to the preamble of patent claim 1.

Aus der deutschen Patentschrift 20 32 433 ist ein Ultraschall-Flüssigkeitszerstäuber bekannt, der mit elektrischer Wechselspannung mit einer Frequenz von z. B. 100 kHz gespeist wird. Zum Zwecke der Umwandlung elektrischer in mechanische Energie hat der Schwinger des Zerstäubers einen Anteil aus piezoelektrischer Keramik.From the German patent specification 20 32 433 an ultrasonic liquid atomizer is known, which with electrical alternating voltage with a frequency of z. B. 100 kHz is fed. For the purpose of converting electrical into mechanical energy, the vibrator of the atomizer has a part made of piezoelectric ceramic.

Im Handel ist ein Inhalationsgerät der Fa. Siemens mit der Bezeichnung « Mikroinhalator », in dem sich ein Flüssigkeitszerstäuber nach der obengenannten Patentschrift befindet. In diesem Gerät ist auch eine elektrische Anregungsschaltung enthalten, die die Speise-Wechselspannung liefert.An inhalation device from Siemens with the designation “microinhaler” is commercially available, in which there is a liquid atomizer according to the above-mentioned patent specification. This device also contains an electrical excitation circuit that supplies the AC supply voltage.

Weitere Anwendungen eines Flüssigkeitszerstäubers der obengenannten Art ist z. B. die Heizöl-Zerstäubung für Heizölbrenner.Further applications of a liquid atomizer of the type mentioned above are e.g. B. the fuel oil atomization for fuel oil burners.

In allen Anwendungsfällen eines wie obengenannten Flüssigkeitszerstäubers mit einem Ultraschall-Schwinger war darauf zu achten, daß die der schwingenden Arbeitsplatte zuzuführende und insbesondere die an dieser Platte anhaftende Flüssigkeitsmenge niemals groß war, weil sonst das einwandfreie Schwingen des Schwingers und insbesondere dieser Arbeitsplatte behindert würde.In all applications of a liquid atomizer as mentioned above with an ultrasound transducer, care had to be taken that the amount of liquid to be supplied to the vibrating work surface and in particular the amount of liquid adhering to this work surface was never large, since otherwise the perfect swinging of the vibrator and in particular this work surface would be impeded.

Es ist eine Aufgabe der vorliegenden Erfindung, Maßnahmen anzugeben, mit denen das Problem der Behinderung der Schwingung des Flüssigkeitszerstäubers bei übermäßiger Flüssigkeitsmenge behoben wird.It is an object of the present invention to provide measures with which the problem of obstructing the oscillation of the liquid atomizer in the event of an excessive amount of liquid is eliminated.

Diese Aufgabe wird mit einem Verfahren nach dem Oberbegriff des Patentanspruchs 1 erfindungsgemäß mit Hilfe der Merkmale des Kennzeichens des Patentanspruchs 1 gelöst. Weitere Ausgestaltungen und Weiterbildungen gehen aus den Unteransprüchen hervor.This object is achieved according to the invention with the aid of the features of the characterizing part of patent claim 1 using a method according to the preamble of patent claim 1. Further refinements and developments emerge from the subclaims.

Zum Betrieb des Ultraschall-Wandlers eines wie oben erörterten Flüssigkeitszerstäubers wird eine elektronische Anregungsschaltung benötigt, die den Schwinger auch unter ungünstigen Betriebs (Anschwing-)bedingungen derart in Betrieb zu setzen vermag, daß tatsächlich Flüssigkeitszerstäubung auftritt. Eine solche ungünstige Betriebsbedingung ist z. B., daß an der Arbeitsplatte des Zerstäubers ein Flüssigkeitstropfen haftet, der die Schwingung dieser Arbeitsplatte und damit die Schwingung des ganzen Ultraschall-Schwingers behindert. Bisher wurde als Abhilfe dagegen ein so hoher Leistungsüberschuß an elektrisch eingespeister Dauerleistung vorgesehen, daß auch solche übermäßige Bedämpfung des Schwingers bewältigt wird. Dies hat aber den Nachteil, daß insbesondere bei einem Ausfall der Flüssigkeitszufuhr der Schwinger dann zerstört wird, weil im Ergebnis thermische Überlastung desselben auftritt.To operate the ultrasonic transducer of a liquid atomizer as discussed above, an electronic excitation circuit is required which can operate the oscillator even under unfavorable operating (start-up) conditions in such a way that liquid atomization actually occurs. Such an unfavorable operating condition is e.g. B. that a drop of liquid adheres to the worktop of the atomizer, which hinders the vibration of this worktop and thus the vibration of the whole ultrasonic vibrator. So far, however, a high excess of electrically fed continuous power has been provided as a remedy that such excessive damping of the transducer can also be overcome. However, this has the disadvantage that the oscillator is then destroyed, in particular if the liquid supply fails, because the result is thermal overloading of the oscillator.

Die Erfindung geht von der Überlegung aus, daß ein völlig neues Betriebsverfahren für einen solchen Flüssigkeitszerstäuber gefunden werden muß, um die anstehenden Probleme zu lösen. Das Konzept dieses neuen Verfahrens ist, den mit einer relativ hochfrequenten Wechselspannung zu speisenden Schwinger statt wie bisher kontinuierlich jetzt mit relativ niedriger Frequenz (20 bis 100 Hz) repetierlich, insbesondere periodisch, getaktet zu speisen. Zum sicheren Anschwingen des Schwingers und damit zum sicheren Anlaufen des Zerstäubungsvorgangs wird während eines ersten Zeitintervalls Δt1 eine so hohe elektrische (Spitzen-)Leistung zugeführt, daß der Schwinger selbst bei starker Bedämpfung durch z. B. anhängende Tropfen sicher anschwingt. Während eines nachfolgenden zweiten Zeitintervalls Δt2 wird wesentlich niedrigere elektrische Leistung bzw. gar keine Leistung mehr zugeführt. Das Taktverhältnis von Δt1 zu Δt2, die absoluten Zeitdauern der Zeitintervalle und die Werte der in den Zeitintervallen zugeführten elektrischen Leistungswerte sind aufeinander so abgestimmt bemessen, daß die sich aus der integral ergebenden mittleren zugeführten elektrischen Leistung resultierende thermische Belastung des Schwingers nicht unzulässig hoch wird und dennoch entsprechende Flüssigkeitsmenge zerstäubt wird.The invention is based on the consideration that a completely new operating method for such a liquid atomizer must be found in order to solve the problems at hand. The concept of this new method is to feed the oscillator repetitively, in particular periodically, at a relatively low frequency (20 to 100 Hz) instead of continuously, as before, at a relatively high frequency alternating voltage. For a safe swinging of the vibrator and thus for a safe start of the atomization process, such a high electrical (peak) power is supplied during a first time interval Δt 1 that the vibrator even with strong damping by e.g. B. attached drops swings safely. During a subsequent second time interval Δt 2 , significantly lower electrical power or no power at all is supplied. The clock ratio of Δt 1 to Δt 2 , the absolute time periods of the time intervals and the values of the electrical power values supplied in the time intervals are dimensioned in such a way that the thermal load on the oscillator resulting from the integrally resulting mean electrical power supply does not become impermissibly high and yet the corresponding amount of liquid is atomized.

Eine besonders vorteilhafte Weiterbildung der Erfindung ist, für die Zeitintervalle Δt1 und Δt2 eine derartige Repetition vorzusehen, bei der Gruppen, jeweils bestehend aus mehreren aufeinanderfolgenden, den Zeitintervallen Δt1' entsprechenden Takten, periodisch aufeinanderfolgen. Vorzugsweise wird die Frequenz der Aufeinanderfolge der Gruppen gleich der schon obengenannten Taktfrequenz mit z. B. 20 bis 100 Hz gewählt. Mit einer Taktfrequenz eines solchen Frequenzwertes läßt sich erreichen, daß ein an der schwingenden Arbeitsplatte anhaftender Flüssigkeitstropfen - je nach Konsistenz und Adhäsionskraft des Materials dieses Tropfens - in eine Schwingbewegung auf der Oberfläche dieser Arbeitsplatte gebracht wird. Während der Phase des Schwingens der Arbeitsplatte zieht sich ein solcher Flüssigkeitstropfen vorzugsweise im Zentrum dieser Platte zusammen. Bei Abklingen der Schwingamplitude bzw. Ruhe der Arbeitsplatte verteilt er sich dagegen gleichförmig bis zu dem Rand der Platte über deren ganzer Oberfläche oder hängt bei nichthorizontaler Lage der Oberfläche der Platte mehr oder weniger am Randbereich der Platte.A particularly advantageous development of the invention is to provide a repetition for the time intervals .DELTA.t 1 and .DELTA.t2, in which groups, each consisting of a plurality of successive cycles corresponding to the time intervals .DELTA.t 1 ', periodically follow one another. Preferably, the frequency of the succession of the groups is equal to the clock frequency already mentioned with z. B. 20 to 100 Hz selected. With a clock frequency of such a frequency value it can be achieved that a liquid drop adhering to the vibrating worktop - depending on the consistency and adhesive force of the material of this droplet - is caused to oscillate on the surface of this worktop. During the phase of the swinging of the worktop, such a drop of liquid preferably contracts in the center of this worktop. On the other hand, when the vibration amplitude or the rest of the worktop decays, it is distributed uniformly up to the edge of the worktop over its entire surface or, if the surface of the worktop is not horizontal, more or less hangs on the edge region of the worktop.

Anstelle eines - bezogen auf die Periodendauer einer 10 bis 100 Hz-Schwingung - längeren Zeitintervalls Δt1 ist es vorteilhaft, die bereits obenerwähnten Impulsgruppen vorzusehen, nämlich mehrere Impulse mit jeweils kürzeren Zeitintervallen Δt1' aufeinanderfolgen zu lassen und die Länge des einzelnen Zeitintervalls Δt.' so kurz zu wählen, daß ät, = 25 bis 200 % der Betriebs-Anschwingzeitkonstanten τ des Schwingers ist. Diese Bemessung hat den überraschenden Vorteil, daß in einem derart kurz bemessenen Zeitintervall Δt1' die Anschwing-Steilheit des SchwingersInstead of a longer time interval Δt 1 - based on the period of a 10 to 100 Hz oscillation - it is advantageous to provide the pulse groups already mentioned, namely to have several pulses with shorter time intervals Δt 1 'in succession and the length of the individual time interval Δt. ' to be chosen so short that ät = 25 to 200% of the operating start-up time constant τ of the oscillator. This dimensioning has the surprising advantage that in such a short time interval Δt 1 'the starting steepness of the vibrator

als lastunabhängig erscheint. Diese Anschwingzeitkonstante beträgt z. B. 1 ms für einen Schwinger mit 100 kHz Schwingfrequenz.appears to be load independent. This response time constant is z. B. 1 ms for an oscillator with 100 kHz oscillation frequency.

Besonders wenig aufwendig ist es, die Repetitionsfrequenz bzw. die Periodenfrequenz für das Aufeinanderfolgen der Gruppen von Anregungstakten der Netzfrequenz zu entnehmen. Hierfür genügt es, ungesiebt gleichgerichtete Wechselspannung des Netzes zur Speisung der Anregungsschaltung zu verwenden.It is particularly inexpensive to take the repetition frequency or the period frequency for the succession of the groups of excitation cycles from the network frequency. For this, it is sufficient to use non-screened rectified AC voltage of the network to supply the excitation circuit.

Bei Schwingungsanregung des Schwingers mit kurzen Zeitintervallen Δt1' in der Größe von 25 bis 200 % der Anschwingzeitkonstanten erreicht die Schwingungsamplitude des Schwingers nicht die Höhe der Endamplitude der Schwingung, sondern der Anstieg bricht bei einem vorgebbaren Wert einer oberen Schwelle S, ab. Im nachfolgenden zweiten Zeitintervall Als, in dem Speisung mit geringerer oder keiner elektrischen Leistung erfolgt, klingt diese Schwingung dann auf einen unteren vorgebbaren Schwellenwert ab. Es läßt sich damit ein sägezahnartiger zeitlicher Verlauf der Schwingungsamplitude des Schwingers erreichen. Damit wird einerseits stets zuverlässig Schwingungsanregung und Flüssigkeitszerstäubung, und zwar auch unter ungünstigsten Anschwingbedingungen, erreicht, und andererseits kann, die mittlere thermische Belastung des Schwingers selbst für den Fall des Trockengehens desselben auf einem genügend niedrigen Maß gehalten werden.When the oscillator is excited to vibrate with short time intervals Δt 1 'in the size of 25 to 200% of the oscillation time constant, the oscillation amplitude of the oscillator does not reach the level of the final amplitude of the oscillation, but the rise stops at a predeterminable value of an upper threshold S. In the subsequent second time interval, in which there is supply with less or no electrical power, this oscillation then decays to a lower, predefinable threshold value. A sawtooth-like time course of the oscillation amplitude of the oscillator can thus be achieved. On the one hand, vibration excitation and liquid atomization are always reliably achieved, even under the most unfavorable starting conditions, and on the other hand, the mean thermal load on the vibrator can be kept to a sufficiently low level even if it dries up.

Mit dem erfindungsgemäßen Verfahren getakteter Zuführung der elektrischen Anregungsleistung für das Schwingen des Ultraschall-Schwingers kann eine besonders vorteilhafte Weiterbildung der Erfindung realisiert werden, nämlich Steuerungs- und/oder Kontrollmaßnahmen durchzuführen. Wenn man im zweiten Zeitintervall Δt2 dem Schwinger keine elektrische Leistung zuführt, erfolgt das Abklingen der Schwingung desselben entsprechend den eigenen charakteristischen Eigenschaften des Schwingers. Da der UltraschallSchwinger im Regelfall mit Hilfe eines piezoelektrischen Wandlers angeregt wird, dem die elektrische Leistung zugeführt wird, kann in der Phase des Abkling-Ausschwingens dieses Ultraschall-Schwingers von diesem Wandler umgekehrt ein elektrisches Signal abgenommen werden. Die Frequenz dieses abzunehmenden elektrischen Signals ist gleich der Eigenresonanzfrequenz des Schwingers und kann zur optimalen Steuerung der Frequenz der Anregungs-Wechselspannung für die Speisung im ersten Zeitintervall Δt1 genutzt werden. Das Auftreten eines solchen elektrischen Signals im zweiten Zeitintervall At2 ist auch eine Kontrolle für das Schwingen und die Zerstäubungsfunktion im ersten Zeitintervall Δt1. Die Höhe und der zeitliche Verlauf - insbesondere die Zeitkonstante - des elektrischen Signals im Zeitintervall Δt2 ist auch ein Maß für die erreichte Schwingamplitude im Zeitintervall Δt1. Eine geringere Höhe dieses im Zeitintervall Δt2 aufgenommenen elektrischen Signals weist auf stärkere Bedämpfung des Ultraschall-Schwingers und damit auf relativ große Flüssigkeitszufuhr hin. Soweit zulässig, kann die zugeführte elektrische Speiseleistung im Zeitintervall Δt, vergrößert werden oder die Menge der pro Zeiteinheit zugeführten Flüssigkeit soweit verringert werden, bis das im Zeitintervall Δt2 abgenommene elektrische Signal auf wieder erreichtes optimales Schwingverhalten des Flüssigkeitszerstäubers hinweist.With the method according to the invention of clocked supply of the electrical excitation power for the oscillation of the ultrasonic oscillator, a particularly advantageous development of the invention can be realized, namely to carry out control and / or control measures. If no electrical power is supplied to the oscillator in the second time interval Δt 2, the oscillation of the oscillator decays in accordance with the oscillator's own characteristic properties. Since the ultrasonic vibrator is usually excited with the aid of a piezoelectric transducer, to which the electrical power is supplied, an electrical signal can be taken from this transducer in the phase when the ultrasonic vibrator decays. The frequency of this electrical signal to be picked up is equal to the natural resonance frequency of the vibrator and can be used for optimal control of the frequency of the excitation AC voltage for the supply in the first time interval Δt 1 . The occurrence of such an electrical signal in the second time interval At 2 is also a control for the oscillation and the atomization function in the first time interval Δt 1 . The level and the time profile - in particular the time constant - of the electrical signal in the time interval Δt 2 is also a measure of the vibration amplitude achieved in the time interval Δt 1 . A lower level of this electrical signal recorded in the time interval Δt 2 indicates stronger damping of the ultrasonic vibrator and thus a relatively large supply of liquid. As far as permissible, the supplied electrical feed power can be increased in the time interval Δt, or the amount of liquid supplied per unit of time can be reduced until the electrical signal taken off in the time interval Δt 2 indicates that the liquid atomizer has again achieved the optimum vibration behavior.

Weitere Erläuterungen der Erfindung gehen auf der anhand der Figuren'gegebenen Beschreibung hervor. Es zeigen :

  • Fig. 1 eine Prinzipanordnung eines Flüssigkeitszerstäubers mit elektronischer Anregungsschaltung.
  • Fig. 2 Ein Diagramm des zeitlichen Taktverlaufs eingespeister elektrischer Leistung.
  • Fig. 3 Ein Diagramm eines zeitlichen Taktverlaufs eingespeister elektrischer Leistung, wobei Gruppen von Speisetakten periodisch aufeinanderfolgen.
  • Fig. 4 Ein Diagramm des zeitlichen Verlaufs der Schwingungsamplitude des Ultraschall-Schwingers.
  • Fig. 5 ein Diagramm des zeitlichen Verlaufs der Amplitude des Ultraschall-Schwingers, wobei die Taktfolge nach den jeweils erreichten Schwingungsamplituden gesteuert wird.
  • Fig. 6 Ein Schaltungsbeispiel zur Durchführung des erfindungsgemäßen Verfahrens.
  • Fig. 7 Ein Schaltbild für eine gemäß der Weiterbildung der Erfindung vorgesehene Überwachung des Betriebsverhaltens des Ultraschall-Schwingers.
Further explanations of the invention can be found in the description given with reference to the figures. Show it :
  • Fig. 1 shows a basic arrangement of a liquid atomizer with an electronic excitation circuit.
  • Fig. 2 is a diagram of the timing of electrical power fed in.
  • Fig. 3 is a diagram of a time cycle of electrical power fed in, wherein groups of feed cycles periodically follow each other.
  • Fig. 4 is a diagram of the time course of the vibration amplitude of the ultrasonic vibrator.
  • 5 shows a diagram of the time course of the amplitude of the ultrasonic vibrator, the clock sequence being controlled according to the vibration amplitudes achieved in each case.
  • Fig. 6 A circuit example for performing the method according to the invention.
  • 7 shows a circuit diagram for monitoring the operating behavior of the ultrasonic vibrator provided in accordance with the development of the invention.

In Fig.1 ist mit 1 der gesamte UltraschallSchwinger bezeichnet. Es ist dies z. B. ein Ultraschall-Schwinger nach der deutschen Patentschrift 20 32 433. Dieser Schwinger umfaßt eine piezokeramische Scheibe 2 als piezoelektrischer Wendler, an die die elektrische Anregungsspannung anzulegen ist. Mit 3 ist die Arbeitsplatte bezeichnet, auf deren Oberfläche 4 die Flüssigkeitszerstäubung 5 erfolgt. Mit 6 ist eine Zuführungsleitung und mit 7 eine in dieser Zuführungsleitung installierte Pumpe für die der Oberfläche 4 zuzuführende, zu zerstäubende Flüssigkeit bezeichnet.In Fig. 1, 1 denotes the entire ultrasonic vibrator. It is z. B. an ultrasonic transducer according to German patent 20 32 433. This transducer comprises a piezoceramic disk 2 as a piezoelectric converter, to which the electrical excitation voltage is to be applied. With 3 the worktop is designated, on the surface 4 of which the liquid atomization 5 takes place. 6 designates a supply line and 7 designates a pump installed in this supply line for the liquid to be atomized to be supplied to the surface 4.

Mit 11 ist die eigentliche Anregungselektronik bezeichnet und mit 12 ist auf eine gemäß einer Weiterbildung vorgesehene zusätzliche Elektronikschaltung hingewiesen, die der Überwachung des betriebsmäßigen Schwingverhaltens des Ultraschall-Schwingers 1 dient.The actual excitation electronics are designated by 11 and reference is made to an additional electronic circuit provided according to a further development, which serves to monitor the operational vibration behavior of the ultrasonic vibrator 1.

Über die Leitung 13 wird die von der Schaltung 11 abgegebene elektrische Leistung dem Wandler 2 zugeführt. Die Schaltung 11 wird an den Anschlüssen 14 z. B. mit 220 Volt Wechselspannung oder auch mit 12 Volt Gleichspannung gespeist. Mit 15 ist eine Verbindungsleitung zur Schaltung 12 bezeichnet, nämlich über die während der Speisepause im Zeitintervall Δt2 ein vom Wandler 2 zurückgeliefertes elektrisches Signal dieser Schaltung 12 zugeführt werden kann. Alternativ kann auch vorgesehen sein, daß der Wandler 2 eine zusätzliche (Rückkopplungs-)Elektrode hat, die über die Leitung 15 mit der Schaltung 12 verbunden ist. Die Leitung 16 zwischen den Schaltungen 11 und 12 dient dazu, von der Schaltung 12 Auswertesignale an die Schaltung 11 zu liefern, um diese zu steuern. Diese Steuerung kann sich insbesondere auf die Frequenz f der Anregungs-Wechselspannung (z. B. im Bereich von 100 kHz), auf die obere Schwelle S, der Schwingungsamplitude des Schwingers 1 und/oder auf die untere Schwingungsamplitude S2 desselben beziehen.The electrical power output by the circuit 11 is fed to the converter 2 via the line 13. The circuit 11 is at the terminals 14 z. B. fed with 220 volts AC or 12 volts DC. 15 denotes a connecting line to the circuit 12, namely via which an electrical signal returned by the converter 2 can be fed to this circuit 12 during the meal break in the time interval Δt 2 . Alternatively, it can also be provided that the converter 2 has an additional (feedback) electrode which is connected to the circuit 12 via the line 15. The line 16 between the circuits 11 and 12 serve to supply evaluation signals from the circuit 12 to the circuit 11 in order to control them. This control can relate in particular to the frequency f of the excitation AC voltage (for example in the range of 100 kHz), to the upper threshold S, the oscillation amplitude of the oscillator 1 and / or to the lower oscillation amplitude S 2 of the same.

Mit den Leitungen 17 ist auf Steuersignalausgänge der Schaltung 12 hingewiesen, z. B. zu einer Leuchtdiode 18, die als Betriebssignallampe dienen kann, und zur Pumpe 7, deren Steuerung aus der Schaltung 12 stets angepaßte Menge der Flüssigkeitszufuhr zur Oberfläche 4 des Schwingers 1 gewährleisten kann.The lines 17 indicate control signal outputs of the circuit 12, e.g. B. to a light emitting diode 18, which can serve as an operating signal lamp, and to the pump 7, the control of which from the circuit 12 can always ensure an adapted amount of liquid supply to the surface 4 of the vibrator 1.

Das Diagramm der Fig. 2 zeigt die über die Leitung 13 dem Wandler 2 und damit dem Schwinger 1 zugeführte elektrische Leistung N, aufgetragen über der Zeit. Die Takte 21 mit den ersten Zeitintervallen Δt1 sind die eigentlichen Speiseintervalle. In diesen Intervallen erhält der Schwinger 1 eine so große elektrische Leistung zugeführt, daß er selbst und damit auch die Arbeitsplatte 3 zuverlässig in die geforderte Ultraschall-Schwingung versetzt wird, und zwar unabhängig davon, ob auf der Oberfläche 4 der Platte 3 eine mehr oder weniger große Flüssigkeitsbelegung oder ein daran anhaftender Tropfen vorliegt. In den Zeitintervallen Δt2 wird elektrische Leistung entsprechend den Takten 22 zugeführt. Die Leistung der Takte 22 kann so hoch bemessen sein, daß kontinuierliches Weiterschwingen kontinuierlich weitere Zerstäubung 5 bewirkt. Die elektrische Leistung der Takte 22 kann aber den Wert Null haben, d. h. man läßt in den zweiten Zeitintervallen Δt2 den Schwinger 1 ausschwingen. Das Taktverhältnis At, : (Δt1 + Δt2) beträgt z. B. 4 ms :20 ms, wobei letzterer Wert vorteilhafterweise aus der Netzfrequenz abgeleitet ist. Wichtig für das Taktverhältnis ist, daß zusammen mit dem Leistungsverhältnis N, zu N2 die zulässigerweise zuzuführende mittlere elektrische Leistung nicht überschritten wird, aber dennoch mit der Höhe der Leistung N, stets sicheres Anschwingen gewährleistet ist.The diagram in FIG. 2 shows the electrical power N supplied to the converter 2 and thus to the oscillator 1 via the line 13, plotted over time. The clocks 21 with the first time intervals Δt 1 are the actual feed intervals. In these intervals, the vibrator 1 receives such a large electrical power that it itself and thus also the worktop 3 is reliably set in the required ultrasonic vibration, regardless of whether on the surface 4 of the plate 3 a more or less there is a large amount of liquid or a drop adhering to it. In the time intervals Δt 2 , electrical power is supplied in accordance with the clocks 22. The power of the clocks 22 can be so high that continuous oscillation continuously causes further atomization 5. The electrical power of the clocks 22 can, however, have the value zero, ie the oscillator 1 is allowed to swing out in the second time intervals Δt 2 . The clock ratio At,: (Δt 1 + Δt 2 ) is z. B. 4 ms: 20 ms, the latter value advantageously being derived from the mains frequency. It is important for the clock ratio that, together with the power ratio N, to N 2, the permissible mean electrical power to be supplied is not exceeded, but nevertheless safe start-up is always ensured with the power N level.

Fig. 3 zeigt das Diagramm der elektrischen Leistung N, wiederum aufgetragen über der Zeit t, jedoch mit Gruppen von - bei diesem Beispiel jeweils drei -Takten 37. Ein jeder dieser Takte 31 hat die Länge eines Zeitintervalls Δt1' von z. B. 1 ms Dauer. Die Repetition dieser Takte 31 innerhalb einer Gruppe ist vorzugsweise periodisch mit der Frequenz F,. Die Gruppen 32 bestehen aus der jeweiligen Anzahl der Einzeltakte 31, haben vorzugsweise ebenfalls periodische Repetition mit der Frequenz F2. Insbesondere wird diese Frequenz F2 zwischen 10 und 100 Hz, vorzugsweise 50 Hz (60 Hz), gewählt. Für das Maß der bereits obenerwähnten zugeführten mittleren elektrischen Leistung kommt es auf die Summe der Zeitintervalle Δt1' einer einzelner Gruppe 32 im Verhältnis zur Periodendauer der Repetitionsfrequenz F2 an.Fig. 3 shows the diagram of the electrical power N, again plotted against the time t, but with groups of - in this example three clocks 37. Each of these clocks 31 has the length of a time interval Δt 1 'of z. B. 1 ms duration. The repetition of these clocks 31 within a group is preferably periodic with the frequency F. The groups 32 consist of the respective number of individual clock cycles 31 and preferably also have periodic repetition with the frequency F 2 . In particular, this frequency F 2 is chosen between 10 and 100 Hz, preferably 50 Hz (60 Hz). The sum of the time intervals Δt 1 ′ of an individual group 32 in relation to the period of the repetition frequency F 2 is important for the measure of the mean electrical power already mentioned above.

Das Diagramm der Fig. 4 zeigt ein sich bei Speisung mit Anregungsleistung nach Fig. 3 ergebender Amplitudenverlauf der Schwingung des Schwingers 1 bzw. der Arbeitsplatte 3. Da zwischen dem letzten Zeitintervall Δt1' der einen Gruppe 32 und dem ersten Zeitintervall Δt.' der folgenden Gruppe 32 nach Fig. 3 keine elektrische Leistungszufuhr vorgesehen ist, erfolgt in diesem Zeitintervall Δt2 ein asymptotisches Abklingen bis zum erneuten Wiederanschwingen.The diagram of FIG. 4 shows an amplitude curve of the oscillation of the vibrator 1 or the worktop 3 when the excitation power is supplied according to FIG. 3. Since between the last time interval Δt 1 'of one group 32 and the first time interval Δt.' the group 32 is no electric power supply is provided according to Fig. 3, is performed in this time interval At 2 asymptotic decay until the next Wiederanschwingen.

Es ist bereits oben darauf hingewiesen worden, daß es von Vorteil sein kann, die Schwingungsamplitude A zwischen einer oberen Schwelle S. und einer unteren Schwelle S2 zu halten, wie dies Fig.5 zeigt. Die Zeitintervalle des Δt1 bzw. das Zeitintervall, in dem Zeitintervalle Δt1' (Fig. 3) vorliegen, und das Zeitintervall Δt2 ergeben sich dann aus dem jeweiligen Betriebsschwingungsverhalten des Schwingers 1 und sind hier in ihrer zeitlichen Länge über die Dauer betrachtet variabel. Wie ebenfalls bereits oben erwähnt, erfolgt die Steuerung der Zeitintervalle Δt1 und Δt2 mit Hilfe der Schaltung 12, in der ein über die Leitung 15 geliefertes Rücksignal des Schwingers 1 ausgewertet wird.It has already been pointed out above that it can be advantageous to keep the oscillation amplitude A between an upper threshold S. and a lower threshold S 2 , as shown in FIG. The time intervals of the Δt 1 or the time interval in which the time intervals Δt 1 '(FIG. 3) are present, and the time interval Δt 2 then result from the respective operating vibration behavior of the vibrator 1 and are here variable in terms of their length in time over the duration . As also mentioned above, the time intervals .DELTA.t 1 and .DELTA.t2 are controlled with the aid of the circuit 12, in which a return signal of the vibrator 1 supplied via the line 15 is evaluated.

Fig. 6 zeigt ein vollständiges Schaltbild für eine Schaltung 11 zur Erzeugung der den Schwinger 1 speisenden elektrischen Leistung. Die Repetitionsfrequenz wird in dieser Schaltung von dem Generator 61 geliefert. Mit dem Generator 62 wird die Frequenz f der über die Leitung 13 zuzuführenden Wechselspannung, z. B. 100 kHz, gesteuert. Der Schaltungsteil 63 ist eine Treiberstufe und der Transistor 64 ist die Endstufe. Das Schaltungsteil 65 mit der Zenerdiode dient der Korrektur einer Schwankung der Versorgungsspannung 66. Die weiteren Einzelheiten der Schaltung gehen für den Fachmann ohne weiteres erkennbar aus dem Schaltbild hervor.FIG. 6 shows a complete circuit diagram for a circuit 11 for generating the electrical power that feeds the oscillator 1. The repetition frequency is supplied by the generator 61 in this circuit. With the generator 62, the frequency f of the AC voltage to be supplied via line 13, e.g. B. 100 kHz controlled. The circuit part 63 is a driver stage and the transistor 64 is the final stage. The circuit part 65 with the zener diode serves to correct a fluctuation in the supply voltage 66. The further details of the circuit are readily apparent to the person skilled in the art from the circuit diagram.

Fig. 7 zeigt ein Schaltungsbeispiel für eine Schaltung 12. Es sind mit 71 das für eine Signalverzögerung vorgesehene Schaltungsteil und mit 72 der Signalkomparator bezeichnet.' Auch dieses Schaltbild bedarf für den Fachmann keiner weiteren Erläuterung.FIG. 7 shows a circuit example for a circuit 12. The circuit part provided for a signal delay and the signal comparator 72 are designated with 71. 'Also this diagram needs no further explanation to the skilled artisan.

In Fig. 3 ist mit 35 ein Vorimpuls gezeigt, der zeitlich vor Ingangsetzen des eigentlichen Zerstäuberbetriebs dem Schwinger 1 zugeführt wird. Es ist dies vorzugsweise ein Burstimpuls (Schwingungspaket) mit vorteilhafterweise eins bis zwanzig Schwingungen mit einer Frequenz, die wenigstens angenähert gleich der Resonanzfrequenz des Schwingers 1 ist.In Fig. 3, a pre-pulse is shown at 35, which is supplied to the oscillator 1 before the actual atomizing operation is started. This is preferably a burst pulse (oscillation packet) with advantageously one to twenty oscillations with a frequency that is at least approximately equal to the resonance frequency of the oscillator 1.

Der Vorimpuls stößt eine Schwingung des Schwingers 1 an und dessen Abklingschwingung 45 (in Fig. 4) wird, wie oben schon beschrieben, zur Anfangssteuerung der Frequenz f der über die Leitung 13 zuzuführenden AnregungsWechselspannung genutzt.The pre-pulse triggers an oscillation of the oscillator 1 and its decay oscillation 45 (in FIG. 4), as already described above, is used for the initial control of the frequency f of the alternating excitation voltage to be supplied via the line 13.

Claims (19)

1. Method of driving an ultrasonic oscillator (1) for atomisation of liquid, the oscillator (1) being supplied by excitation electronics (11) having an electrical alternating voltage, the frequency (F2) of which can be tuned to the optimum oscillatory power of the oscillator (1), characterised in that the electrical power (N) supplied is timed to occur in repeated cycles, the power (N1) supplied for a first time interval (Δt1) being rated so high that the starting threshold (E) for actually occurring atomisation of liquid (5) is sufficiently highly exceeded even when the condition of operational oscillation build-up is unfavourable, the power (N2) supplied for a second time interval (Δt2) being rated lower by comparison with the time interval (Δt1), and the mean of the power (N,+ N2) supplied, as averaged over the two time intervals (Δt1, Δt2) taken together, being matched to the quantitity of liquid (7) which is fed per unit time and is to be atomised.
2. Method according to Claim 1, characterised in that during a second time interval (Δt2) no electric power (N2 = 0) is supplied, the mechanical power stored in the oscillator (1) being used for further atomisation of liquid (5) in this second time interval (Δt2).
3. Method according to Claim 1 or 2, characterised in that the length of a first time interval (Δt1) amounts to 25 to 200 % of the operational oscillation build-up time constant τ of the oscillator.
4. Method according to Claim 1, 2 or 3, characterised in that the repetition of the time intervals (Δt1, Δt2) takes place with a frequency (F2 of 10 to 100 Hz.
5. Method according to Claim 4, characterised in that the repetition (F2) is carried out with the mains frequency (50 or 60 Hz), unfiltered, rectified alternating voltage of the mains for the supply (14) of the excitation circuit (11) being employed for this purpose.
6. Method according to one of Claims 1 to 5, characterised in that a second repetition frequency (F2) having values from 10 to 100 Hz is employed for a group (32) consisting of several cycles (31) of sequential first time intervals (Δt1') having a first repetition frequency (FI).
7. Method according to Claim 6, characterised in that the first repetition frequency (F,) is chosen to be approximately equal to 0.2 to 2 times the reciprocal of the oscillation build-up time constant τ of the oscillator (1).
8. Method according to Claim 6 or 7, characterised in that the number of the cycles (31) of a particular group (32) is equal to 2 to 10 or 24.
9. Method according to one of Claims 1 to 8, characterised in that an upper threshold (S,) and a lower threshold (S2) are stipulated for the amplitudes of oscillation (A) of the oscillator (1), the upper threshold (S1) being rated higher than the minimum amplitude (E) of the oscillator (1) required for atomisation, and the change from the particular-first time interval (Δt1, Δt,'), to the subsequent second time interval (Δt2) taking place when the upper threshold (S1) is reached, and the change from the second time interval (Δt2) to the subsequent firsttime interval (Δt1, Δt1') taking place when the lower threshold (S2) is reached.
10. Method according to one of Claims 2 to 9, characterised in that an evaluation is undertaken of the temporary damping of the amplitude of oscillation (A) of the oscillator (1) taking place in the second time interval (Δt2), an electrical signal (15) being received, which is delivered from the oscillator and corresponds to this damping.
11. Method according to Claim 10, characterised in that the evaluation of the electrical signal (15) of the damping of the oscillator (1) during the second time interval (Δt2) is used to monitor (18) the correct operation of the oscillator.
12. Method according to Claim 10 or 11, characterised in that the electrical signal (15) of the damping of the oscillator during the second time interval (Δt2) is used to control the interruption and/or (re-)starting of a liquid feed (7).
13. Method according to Claim 10, 11 or 12, characterised in that the electrical signal (15) of the damping of the oscillator during the second time interval (At2) is used for tuned control of the liquid feed (7) and of the mean electrical power (N 1 + N 2 ) supplied.
14. Method according to one of Claims 10 to 13, characterised in that the electrical signal (15) of the damping of the oscillator (1) during the second time interval (Δt2) is used during the first time interval (Δt1) to monitor and control the supply of electrical power (N1) rated sufficiently highly for the operational overshooting of the starting threshold (E).
15. Method according to one of Claims 10 to 14, characterised in that the frequency of the electrical signal (15) of the damping of the oscillator (1) during the second time interval (Δt2) is used to control the frequency (f) of the excitation alternating voltage for the supply of the oscillator (1).
16. Method according to Claim 10, characterised in that the frequency of the electrical signal (15) of the damping of the oscillator (1), which is to be obtained after the oscillator (1) has beem supplied with an exciting prepulse (35), is used to determine the frequency (f) of the electrical alternating voltage (13) which excites the oscillator (1).
17. Method according to Claim 16, characterised in that the prepulse (35) is a burst sigmal (sine beat) having only a few oscillations.
18. Method according to one of Claims 1 to 17, characterised in that the mean electrical power (N, + N2) is held constant independently of fluctuations in the supply voltage (66) by means of a controlled change in the length of the first and/or the second time intervals (Δt1, Δt2).
EP84104426A 1983-04-22 1984-04-18 Method of driving an ultrasonic oscillator for an atomizing fluid Expired EP0123277B1 (en)

Priority Applications (1)

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AT84104426T ATE41887T1 (en) 1983-04-22 1984-04-18 PROCEDURE FOR OPERATING AN ULTRASONIC VIBRATOR FOR LIQUID ATOOMIZATION.

Applications Claiming Priority (2)

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DE19833314609 DE3314609A1 (en) 1983-04-22 1983-04-22 METHOD FOR OPERATING AN ULTRASONIC VIBRATOR FOR LIQUID SPRAYING
DE3314609 1983-04-22

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EP0123277A2 EP0123277A2 (en) 1984-10-31
EP0123277A3 EP0123277A3 (en) 1986-07-02
EP0123277B1 true EP0123277B1 (en) 1989-04-05

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US7211927B2 (en) 1996-09-24 2007-05-01 William Puskas Multi-generator system for an ultrasonic processing tank
JP4666769B2 (en) * 1999-03-05 2011-04-06 エス．シー． ジョンソン アンド サン、インコーポレイテッド Control system for atomizing liquid using piezoelectric vibrator
FR2903331B1 (en) 2006-07-07 2008-10-10 Oreal GENERATOR FOR EXCITING A PIEZOELECTRIC TRANSDUCER
IT1393824B1 (en) 2009-04-20 2012-05-11 Zobele Holding Spa LIQUID ATOMIZER WITH PIEZOELECTRIC VIBRATION DEVICE WITH IMPROVED ELECTRONIC CONTROL CIRCUIT AND RELATED DRIVING METHOD.
CN105764616A (en) 2013-09-09 2016-07-13 奥姆纽斯特有限责任公司 Atomizing spray apparatus
CN114130547B (en) * 2021-11-18 2023-06-16 安徽理工大学 Medicament vaporization assembly and jet flow flotation column type device using same

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EP0123277A2 (en) 1984-10-31
ATE41887T1 (en) 1989-04-15
DE3314609A1 (en) 1984-10-25
DE3477550D1 (en) 1989-05-11
EP0123277A3 (en) 1986-07-02

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