JPS6258788B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a liquid atomization device that atomizes liquid fuel such as kerosene or light oil, water, medicinal solution, recording liquid, etc. using an electric vibrator. .

Configurations of Conventional Examples and Their Problems Various types of liquid atomization devices have been proposed in the past, and many of them use electric vibrators such as piezoelectric elements.

For example, (1) a piezoelectric element is bolted or glued to a horn-shaped vibrator, the mechanical vibration amplitude of the piezoelectric element is amplified by the horn-shaped vibrator, and a liquid is supplied and dripped onto the amplitude amplifying surface at the tip of the horn. (2) A device that injects an array of ultrasonic atomized particles, which has been put into practical use in inkjet recording devices in recent years, and has a piezoelectric vibrator installed at one end of the liquid chamber. , with an orifice installed at the other end, the pressure increase in the liquid chamber due to the vibration of the piezoelectric vibrator is transmitted to the orifice via the liquid, and as a result, atomized particles can be sprayed from the orifice at a considerable scattering speed. There are atomization devices that can do this.

However, the conventional ultrasonic atomization device described above had various drawbacks.

The atomization device (1) requires high machining precision for the horn-shaped vibrator and a pump to supply the liquid, so it is expensive, and the method of supplying the liquid to the atomization surface is complicated. It was hot. Further, in order to obtain an atomization amount of 20 c.c./min, a considerably large power consumption of 5 to 10 watts is required, and the atomization ability is not sufficient.

The atomizing device (2) had the advantage of being simple in structure and stable in operation, as is clear from the fact that it is used in inkjet. Since the configuration transmits the information to the orifice via the liquid, when a typical liquid containing a large amount of dissolved air is used, cavitation bubbles will occur in the liquid chamber, and these bubbles will prevent stable atomization operation. It had the disadvantage of being unsustainable. Therefore, in order to atomize ordinary liquids, dissolved air must be degassed, which is extremely lacking in versatility.

OBJECT OF THE INVENTION The present invention aims to eliminate such conventional drawbacks, and provides an atomization device that has a compact configuration, obtains a sufficient amount of atomization with low power consumption, and maintains stable atomization operation. For the purpose of providing.

Structure of the Invention In order to achieve this object, the present invention includes a body including a pressurizing chamber filled with liquid, a supply section for supplying liquid to the pressurizing chamber, and a supply section facing the pressurizing chamber. An atomizer is composed of the provided nozzle part and an electric vibrator that energizes the nozzle part to vibrate the nozzle, and automatically tracks a predetermined mechanical resonance frequency of the electric vibrator to generate electricity. an oscillation drive section that transmits vibrational energy; a temperature detection means for the liquid or the surroundings; and a duty control section that controls the ratio between the vibration time and the stop time of the electric vibrator based on the signal from the temperature detection means. It constitutes a conversion device.

With this basic configuration, it maintains stable atomization operation as an atomizer, and performs oscillation operation at a predetermined mechanical resonance frequency with good electro-mechanical conversion efficiency.
Moreover, a predetermined amount of atomization is always ensured by controlling the ratio of the oscillation time and the stop time of the electric vibrator in response to temperature changes in the liquid or the surroundings.

DESCRIPTION OF EMBODIMENTS An atomizer which is an embodiment of the present invention will be described with reference to FIG. A body 2 including a pressurized chamber 1 filled with liquid is fixed to a mounting plate 4 with screws 3. The liquid enters the pressurizing chamber 1 through the supply pipe 5, and the gas discharge pipe 6 is filled halfway during actual atomization. Reference numeral 7 denotes a nozzle portion facing one side of the pressurizing chamber 1, and its outer periphery is joined to the body 2. A spherical protrusion 8 having a fine nozzle for ejecting droplets is formed at the center of the nozzle portion 7 . Furthermore, an annular electric vibrator, here a piezoelectric element 9, is attached to the nozzle portion 7. This piezoelectric element 9 is a piezoelectric ceramic polarized in the thickness direction, and has electrodes on the surface to be joined to the nozzle portion 7 and on the opposite surface. Reference numeral 10 denotes a lead wire for transmitting a drive signal to the piezoelectric element 9. One side is soldered to one side of the piezoelectric element 9, and the other side is connected to the body 2 with a screw 11. When the mechanical vibration of the piezoelectric element 9 is excited by the drive signal, the nozzle part 7 is also urged and vibrated, and as a result, the liquid in the pressurizing chamber 1 is discharged as atomized particles 12.

Incidentally, the liquid supplied to the pressurizing chamber 1 may be filled halfway into the gas discharge pipe 6 in the atomizer installation configuration, but as an alternative, the liquid supplied to the pressurizing chamber 1 may be and the exhaust pipe 6 is empty, for example, the exhaust pipe 6 is empty before entering the droplet ejection sequence.
Negative pressure may be applied through the pressure chamber 1 to fill the pressurized chamber 1 with liquid, and at the same time, the exhaust pipe 6 may be pulled up halfway.
According to the latter method, impurities in the liquid solidify in the nozzle, and the problem that droplets cannot be ejected does not occur.

Next, the configuration of the atomizing device will be explained in block form with reference to FIG. Reference numeral 13 denotes an oscillation drive unit that automatically tracks a predetermined mechanical resonance frequency of the electric vibrator 9, transmits electric vibration energy at the frequency to the electric vibrator 9, and drives the atomizer. Continue the atomization operation. Further, 14 is a temperature detection means for detecting the temperature of the liquid to be discharged or the surroundings, and a signal from this temperature detection means is inputted, and a duty control section 15 is used to control the vibration time and stop time of the electric vibrator 9. The atomization ratio is controlled and the atomization ability is compensated for the temperature.

Each characteristic to explain the above atomization operation is explained in the third section.
As shown in the figure. a is the voltage V ₀ across the electric vibrator 9
is i-, which represents the relationship between the drive frequency at a predetermined _V2 and the current flowing through the electric vibrator 9.
In the characteristic diagram, the frequency of the applied driving voltage is =
There is a maximum point at ₁ and a minimum point at ₃ . =
₃ is approximately the intermediate frequency between ₁ and ₂ . b
shows the relationship between the driving frequency and the atomization amount when V ₀ =V ₂ , where = ₂ is the atomization amount peak. The mechanical resonance point is = ₂ , which is the frequency at which the electrical-mechanical energy conversion efficiency is the best. Also, <
The range of ₀₁ and > ₀₃ is a range in which the amplitude operation of the nozzle section described above is unstable, and the spray characteristics are also unstable. c.
is the atomization amount characteristic when the applied voltage level is changed with the driving frequency fixed at the mechanical resonance point = ₂ . Both the regions of V ₀ < V ₁ and V ₀ < V ₃ are
Even if the drive frequency is stable, the atomization operation becomes unstable.On the low voltage side, there is an unstable operation range caused by the minute assembly variations of the atomizer, and on the high voltage side, the atomization operation becomes unstable. An extremely large amount of dissolved air is generated due to vibration, causing unstable operation of the ejected droplets.

In this way, in order to vibrate efficiently and stably as an atomizer, oscillation at the mechanical resonance point (=
₂ ), and the applied voltage is also V ₁ V ₀ V ₃
must be maintained at a predetermined value. Furthermore, the mechanical resonance point varies depending on the ambient temperature and tends to decrease as the temperature increases. The level of the amount of atomization also fluctuates as the ambient temperature changes. Therefore, the above-mentioned 13 oscillation drive section automatically tracks the resonance frequency to continue oscillation at the mechanical resonance point (= ₂ ), thereby achieving stable atomization operation. Furthermore, the temperature detection means 14 and 15 and the duty control section operate to maintain the atomization amount, which changes depending on the temperature, at a predetermined value, and adjust the atomization amount by varying the ratio of the vibration time and the stop time. In addition to compensation, the amount of atomization is controlled.

Next, before explaining the more detailed configuration of the oscillation drive section of the present invention, in FIG. Shows the phase relationship with current. a
is similar to FIG. 3a. b shows the phase difference between the current and the voltage, showing how the current phase advances and how the phase difference becomes minimum at the mechanical resonance point = ₂ .

FIG. 5 shows a specific example of the configuration of the oscillation drive section, and the same numbers as those in the previous figures indicate components having similar functions. 16 is a current detector that detects the current flowing through the electric vibrator 9, and a phase comparator 17 receives the current signal from the current detector 16 and the voltage signal applied to the vibrator 9. ,
Signals depending on their phase difference are output to 18 oscillators. The oscillator 18 receives the signal from the phase comparator, controls the oscillation frequency so that the phase difference is minimized, and transmits the signal to the electric vibrator 9 via the drive section 19. Reference numeral 20 denotes a switch means operated by the output signal of the duty control section 15. The closed state of this switch is the vibration time of the electric vibrator 9, and the closed state is the stop time.

FIG. 5 shows a configuration block that realizes the content explained in FIG.

Further, with reference to FIG. 6, a specific example of the configuration of another oscillation drive section will be explained. Those with the same numbers as above are components having similar functions. Current detector 16
The signal is amplified by an amplifying section 21 and transmitted to the electric vibrator 9 via an inductor 22.
This system has a self-oscillation configuration in which 22 maintains oscillation at a period mainly determined by a predetermined inductance determined by the inductor and the equivalent parallel capacitance of the electric resonator 9. There is. By setting the inductor to a predetermined value and adjusting the oscillation frequency of the system to approximately a predetermined resonance point of the electric vibrator 9, stable atomization operation can be maintained. With respect to temperature changes, the equivalent parallel capacitance change almost follows the resonance point fluctuation. In addition, in a self-oscillation system at a mechanical resonance point, a pull-in phenomenon that causes a jump in frequency and power may occur, and in this case, a loose coupling state is formed to ensure stable operation of the self-oscillation system. can be retained.

FIG. 7 shows a specific block configuration a of the duty control section and its waveform b. In a,
The signal from the triangular wave generator 23 and the signal from the level setter 24 are compared by a comparator 25, and the result is expressed as a predetermined High/Low signal, which controls the opening/closing state of the switch means 20. . As the switch means, analog switches, transistors, etc. are often used as opening/closing means in electric circuits.

b shows potential changes at each part in FIG. 7a, and a High output signal is generated in the periods from t ₁ to t ₂ and from t ₃ to t ₄ .

By the way, in the embodiment shown in FIG. 5, the voltage applied to the vibrator 9 and the current supplied to the vibrator 9 are directly input to the phase comparator, but if the applied voltage is a rectangular wave, the electric vibrator 9 Due to its capacitive nature, its current waveform exhibits the characteristics of a capacitive load. Therefore, if the fundamental frequencies of the voltage and current are inputted to the phase comparator via a filter section that takes out the respective fundamental frequencies, it is also possible to detect the phase difference. This is the fifth
The same applies to the oscillation drive section having the configuration shown in the figure.

Effects of the Invention According to the atomization device of the present invention, the following effects can be obtained.

(1) Even if the mechanical resonance point shifts due to environmental changes such as temperature or changes over time in the atomizer configuration,
Since the oscillation frequency at the resonance point is always automatically tracked, an electronic atomization device with high efficiency and stable atomization operation can be realized.

(2) Since the duty control section compensates for variations in the amount of atomization due to temperature changes, etc., a predetermined amount of atomization can always be obtained.

(3) The atomization device as a whole has a compact configuration, and further lower power consumption can be achieved by inductor coupling.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing the configuration of essential parts of an embodiment of the present invention, Fig. 2 is a block diagram showing the structure of an atomization device of an embodiment of the invention, and Fig. 3a is a drive frequency and current. , b is a characteristic diagram showing the relationship between driving frequency and atomization amount, c is a characteristic diagram showing the relationship between driving voltage and atomization amount, FIG. 4 a and b are characteristic diagrams, and FIG. 5 is a block diagram showing an embodiment of the present invention. FIG. 6 is a block diagram showing another embodiment of the present invention, FIG. 7a is a diagram showing a specific configuration of the duty control section, and FIG. 7B is a voltage waveform diagram of each part of the duty control section. DESCRIPTION OF SYMBOLS 1... Pressurization chamber, 2... Body, 5... Supply part, 7... Nozzle part, 9... Electric vibrator, 13
...Oscillation drive unit, 14...Temperature detection means, 15...
...Duty control unit, 16...Current detector, 1
7... Phase comparator, 18... Oscillator, 19... Drive section, 21... Amplification section, 22... Inductor.

Claims (1)

[Claims] 1. A body equipped with a pressurized chamber filled with liquid;
a supply unit for supplying liquid to the pressurizing chamber; a nozzle unit having a nozzle facing the pressurizing chamber; and an electric vibrator that biases the nozzle unit and vibrates the nozzle. an oscillation drive section that automatically tracks a substantially resonant frequency of the electric vibrator and transmits electric vibration energy; a liquid or ambient temperature sensing means; and a signal from the temperature sensing means that causes the electric vibrator to vibrate. An atomizing device that includes a duty control section that controls the ratio between time and stop time. 2. A current detector that detects the current flowing through the electric vibrator, and a phase difference between the fundamental frequencies of the drive voltage applied to the electric vibrator and the drive current detected by the current detector. A patent that includes the oscillation drive unit, which includes a phase comparator that generates an output signal, an oscillator that varies the oscillation frequency depending on the output signal of the phase comparator, and a drive unit that transmits the signal of the oscillator. The atomization device according to claim 1. 3 Consisting of a current detector that detects the current flowing through the electric vibrator, an amplification section that amplifies the signal of the current detector, and a predetermined inductor that transmits the signal from the amplification section to the electric vibrator. The atomization device according to claim 1, having the oscillation drive section.