JPS6366266B2 - - 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.

Purpose of the Invention The present invention aims to eliminate such conventional drawbacks, and has a compact configuration, obtains sufficient atomization amount with low power consumption, and provides stable atomization operation even under environmental changes. The purpose is to provide an atomization device that maintains

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 constituted by a nozzle part having a nozzle provided therein, and an electric vibrator that energizes the nozzle part to vibrate the nozzle, and transmits an oscillation signal to the electric vibrator via an inductor. The atomizing device is composed of an oscillation driving section and a resistor section connected in parallel to the electric vibrator.

With this configuration, the electric vibrator forms an electric tank circuit with the inductor, which boosts the voltage supplied to the amplification section to generate vibrations, reducing power consumption. Depending on the component, the Q of the tank circuit is lowered to a predetermined value.
Furthermore, during actual atomization operation, the pressurized chamber acts as a self-sufficient liquid pump due to the vibration of the nozzle plate, making the entire atomizer system compact.

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 hole for ejecting droplets is formed in 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 and on the opposite surface. Reference numeral 10 denotes a lead wire for transmitting a drive signal to the piezoelectric element 9, one of which is soldered to one side of the piezoelectric element 9, and the other 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, there is no problem that impurities in the liquid solidify in the nozzle hole and droplets cannot be ejected.

Next, FIG. 2 shows details of the configuration of the atomizing section. a is a top view, b is a cross-sectional view taken along line C-C' of a, and 13 represents a single-sided electrode of piezoelectric element 9; As will be explained later, when driving in the ultrasonic range close to the audible frequency band, the diameter is about 10 mm and the thickness is about 1 mm.
A nozzle portion 7 having a thickness of about 10 μm is bonded to a piezoelectric element 9 having a thickness of 1 mm, and the distance between the edges of one electrode 13 and the nozzle portion 7, which is the other electrode, is only about 1 mm.

FIG. 3 is a diagram showing the operating characteristics of a self-excited oscillation circuit system having a tank circuit configuration with an inductor.
Reference numeral 14 denotes an amplification section that amplifies a signal from a current detector 15 that detects the current flowing through the electric vibrator 9, and transmits a drive signal to the piezoelectric element 9 via an inductor L16.

FIG. 4 is an electrical equivalent circuit that approximates the piezoelectric element 9, with 17 equivalent parallel capacitances Cs,
18, 19, and 20, each consisting of a series inductance Lo, a capacitance Co, and a resistance Ro.
The inductor L shown in FIG. 3 has a series resonance configuration mainly consisting of the equivalent parallel capacitance Cs. This L and Cs
forms a tank circuit, and the driving voltage transmitted from the amplifier is boosted across the electric vibrator, and
It becomes a sine waveform.

However, as described above, in the case of a configuration in which the edge surface distance between the electrodes of the piezoelectric element 9 cannot be made large, an electrical bypass path is formed due to adhesion of moisture between the electrodes, and the tank circuit described above is The boost values are different. Therefore, as shown in Fig. 5, a spray state is obtained with a circuit configuration in which a resistor 21 is connected in parallel to both ends of the piezoelectric element 9 to lower the Q of the tank circuit, so that the leakage between the electrodes does not become a problem as described above. The electronic atomization device of the present invention does this.

FIG. 6 shows the change in the voltage across the atomizer when the size of the resistor 21 is changed. The smaller the resistance value inserted in parallel, the lower the boost value becomes. The voltage level indicated by the one-dot chain line is the value of the amplifier power supply voltage applied from the amplifier 14 to the inductor L16. As mentioned above, even when leakage impedances are connected in parallel, if a parallel resistance value is selected and connected so that the voltage across the atomizer does not change significantly, stable operation is possible even against environmental changes.

In addition, Fig. 7 shows the change characteristics of the current and the amount of atomization when a driving voltage of a predetermined frequency is applied to the piezoelectric element 9 alone, and fr and fm indicate the electrical resonance point and mechanical resonance point, respectively. represents. When determining the oscillation frequency by adjusting the inductor in the automatic oscillation system described above, it is adjusted to the actual spraying frequency near this fr.

FIG. 8 shows a specific embodiment of the present invention. The same numbers as in the previous figure indicate components having the same function. 22 is a resistor that constitutes a current detector, and this detection signal is sent to a complementary SEPP type amplifier circuit via a capacitor 23, and is transmitted via an inductor 16 by the operation of switching transistors 34 and 35 in the output stage. It is transmitted to the piezoelectric element 9. The amplifier circuit includes resistors 24, 25, 2
6, 27, 29, 31, 32 and transistor 2
8, 33, 34, 35, and a capacitor 30. In this closed loop, L and the above
It is responsible for a self-excited oscillation circuit with an oscillation period determined by Cs. Note that since the output stage performs a switching operation, the loss of the transistor itself is small, and the power consumption of the amplifier section is also reduced.

FIG. 9 shows another configuration example of the present invention, in which an oscillator 36 and an amplification section 37 form an oscillation drive section 38, which is driven via an inductor 16 to an electric vibrator 9 connected to a parallel resistor 21. A signal is transmitted.

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

(1) The atomizer itself has a compact configuration, and
The power consumption of the drive device can be reduced, and the atomization device can achieve lower power consumption, that is, higher efficiency.

(2) By connecting the resistor section in parallel with the electric vibrator, the atomization characteristics will not deteriorate due to environmental changes such as dew condensation, even if the electrodes are not sufficiently spaced apart.

(3) If the present invention is used in addition to preventing leakage by surface coating between electrodes, driving reliability will be further improved under various environmental conditions.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the configuration of an embodiment of the present invention, Fig. 2a is a front view of the vibrator side, Fig. 2b is a sectional view of the electrode section, and Fig. 3 is a block diagram explaining the operation of the self-excited oscillation circuit. 4 is an electrical equivalent circuit diagram of an electric vibrator, FIG. 5 is a block diagram of an atomizing device according to an embodiment of the present invention, and FIG. 6 is a diagram showing parallel resistance values and voltages across the atomizer. A relationship diagram, FIG. 7 is a characteristic diagram of current and atomization amount with respect to drive frequency, FIG. 8 is a circuit diagram showing one embodiment of the present invention, and FIG. 9 is a diagram showing another embodiment of the present invention. . DESCRIPTION OF SYMBOLS 1... Pressure chamber, 2... Body, 5... Supply part, 7... Nozzle part, 9... Piezoelectric element (electrical vibrator), 15... Current detector, 16... Inductor, 21... ...resistance section, 38... oscillation drive section.

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 atomizer consisting of an inductor, an oscillation drive section that transmits an oscillation signal to the electric vibrator via the inductor, and a resistor section connected in parallel to the electric vibrator. conversion device. 2. The atomization device according to claim 1, which has the oscillation drive section that includes a current detector that detects a current flowing through an electric vibrator, and an amplification section that amplifies the signal of the current detector. .