JPS59136159A - Atomizer - Google Patents

Abstract

PURPOSE:To obtain a substantial rate of atomization at low electric power consumption with compact constitution by connecting an oscillation driving part which supplies a constant current driving signal to an electrical oscillator in the stage of spraying liquid in a pressurizing chamber from a nozzle by said oscillator. CONSTITUTION:A negative pressure is applied through a discharging pipe 6, and liquid is filled from a supply part 5 into a pressurizing chamber 1 so as to be filled up to the midway of the pipe 6. A driving signal is transmitted via a lead wire 10 to a piezoelectric element 9 which excites mechanical oscillation to energize a nozzle part 7, thereby discharging the liquid in the chamber 1 in the form of atomized particles 12 from the nozzle part. An oscillation driving part 17 is connected to the element 9 and the signal from an oscillation part 18 is amplified in an amplifier part 19. The driving signal value to the element 9 is set at a prescribed value with a constant current part 20. The atomizer is thus efficiently driven.

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 bath liquid, recording liquid, etc. using an electric vibrator. Regarding.

Conventional Structures and Their Problems Various types of liquid atomization devices have been proposed in the past, and many of them use electrical 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 sprays an array of ultrasonic atomized particles that has been put into practical use in inkjet recording devices in recent years, with a piezoelectric vibrator installed at one end of the liquid chamber. , with an orifice provided at the other end, the pressure change in the liquid chamber caused by the vibration of the piezoelectric vibrator is transmitted to the orifice via the liquid, and as a result, atomized particles can be injected from the orifice at a considerable scattering speed. There is an atomizer.

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 for supplying the liquid to the atomization surface is complicated. there were. In addition, in order to obtain an atomization amount of 20cc/min,
In addition to requiring a considerably large power consumption of 6 to 1 watts, its atomization ability was not sufficient.

In addition, the atomizing device (2) has the advantage of being simple in structure and stable in operation, as is clear from the fact that it is used in inkjet, but the pressure inside the liquid chamber due to the vibration of the vibrator is Since the structure transmits the change to the orifice through the liquid, when using a typical liquid containing a large amount of dissolved air, cavitation bubbles are generated in the liquid chamber, and these bubbles prevent stable atomization. It had the disadvantage of not being able to maintain its operation. Therefore, in order to atomize ordinary liquids, dissolved air must be degassed, which is extremely lacking in versatility.

OBJECTS OF THE INVENTION The present invention eliminates these conventional drawbacks, and provides a compact configuration and a sufficient amount of atomization with low power consumption. In addition, it is an object of the present invention to provide an atomizing device that does not cause the device to be destroyed even when there is no load, in which no liquid as a load is supplied.

Structure of the Invention In order to achieve this object, the present invention includes a body provided with a pressurized chamber filled with liquid, a supply section for supplying liquid to the pressurized chamber, and a supply section facing the pressurized 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 the drive signal to the atomizer is made into a constant current oscillation. The drive unit and the atomizer constitute an atomizing device. Further, it includes a current detection section that detects the current flowing through the atomizer, an amplification section that amplifies the signal of the current detection section, and an oscillation drive section that transmits the output of the amplification section to the atomization device via an inductor. are doing. Further, in order to prevent damage to the atomizer, the atomizer includes a current limiting section that limits the current to the atomizer and the oscillation drive section to a predetermined value or less.

With this configuration, a constant current is passed through the electric vibrator, and no current greater than the constant current flows. However, the electric resonator that forms a series resonant circuit with an inductor has
A voltage that is a predetermined times the voltage supplied to the amplifier section is applied to excite mechanical vibrations. Furthermore, during the actual atomization operation, only the ejected amount of liquid is sucked up, so there is no need for a pump or the like to supply liquid to the pressurizing chamber, resulting in a compact system as a whole.

DESCRIPTION OF EMBODIMENTS Referring to FIG. 1, an atomizer which is an embodiment of the present invention will be described. 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 via the supply vibro, and during the atomization operation, the vibro for gas discharge is filled halfway. 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.

10 is a single line for transmitting a drive signal to the piezoelectric element 9;
One side is soldered and bonded to one electrode surface of the piezoelectric element 9, and the other side is connected to the body 2 with a helix 11. When the piezoelectric element 9 is excited to mechanically vibrate by the drive signal, the nozzle portion 7 is also energized and vibrates, so that the liquid in the pressurizing chamber 1 is discharged as atomized particles 12 as a result.

By the way, the liquid supplied to the pressurizing chamber 1 may be filled halfway with the vibro for gas discharge in the atomizer installation configuration, but as an alternative, in the atomizer installation configuration, the liquid supplied to the pressurizing chamber 1 and The exhaust vibro is empty, and before entering the droplet ejection sequence, for example, negative pressure may be applied through the exhaust vibro to fill the pressurizing chamber 1 with liquid and draw the exhaust vibro halfway up.

According to the latter method, impurities in the liquid solidify in the nozzle hole and the problem that droplets cannot be ejected does not occur.

FIG. 2 shows an electrical equivalent circuit that approximates the piezoelectric element 9, and is composed of 13 equivalent parallel capacitances C8, a series inductance L0 of 14° and 15.16°, a capacitance C0, and a resistance R0. ing.

FIG. 3 shows the current change when a driving signal (for example, a sine wave) is applied to the piezoelectric element 9 of the atomizer by changing the frequency, and shows the current change when the pressurizing chamber 1 is filled with liquid. The characteristics under load are determined in an empty state with no liquid, that is,
It shows the characteristics at no load. In the no-load characteristics shown by the solid line, series resonance between L014 and C016 shown in FIG. 2 occurs at the electrical resonance frequency f1, and the peak value of the drive current appears. Also, the electrical anti-resonance frequency f2
In this case, parallel resonance occurs between L014 and C813 shown in FIG. 2, and the drive current becomes a minimum value. f shown in the figure
r is approximately an intermediate frequency between fl and f2 and is called a mechanical resonance frequency. The broken line in FIG. 3 is the one under load, and the difference between the current values f and +f2 mentioned above is not extremely large compared to when there is no load.

FIG. 4 shows changes in current value and changes in atomization amount with respect to changes in drive frequency under load. mechanical resonance frequency fr
The atomization amount is at its maximum value when . When actually spraying, it is operated at a driving frequency near this fr.

FIG. 6 is a block diagram showing the configuration of the oscillation drive section 17 including the constant current section of the present invention.
The drive signal value to the piezoelectric element 9 is set to a predetermined value via the constant current section 20. In this configuration, only the signal to the piezoelectric element 9 is a constant current. In the explanation of FIGS. 3 and 4, it was stated that the atomization is performed at a frequency around fr. It's a moat, the difference between f and f2 is small, fr
Even if the drive is in the vicinity, it may approach fl. At this time, when there is no load, the impedance of the piezoelectric element 9 rapidly decreases, and an excessive current flows as shown in FIG. 3. If a constant current signal is used as in the present invention, a current exceeding a predetermined value will often be supplied to the piezoelectric element even when there is no load, and this will cause damage to each joint shown in the structure of Figure 1. Never.

FIG. 6 is a block diagram showing another embodiment of the invention. The first oscillation drive section includes a current detection section 21 that detects the current flowing through the piezoelectric element 9, an amplification section 22 that amplifies the signal of the current detection section 21, and an equivalent capacitance C6 of the piezoelectric element 9, which causes series resonance. An inductor 23 forming the circuit is included. Further, the current limiter 24 limits the current to the oscillation driver 17 so that it does not exceed a predetermined value. A specific example of this configuration will be explained with reference to FIG. 7, and the driving section of the piezoelectric element 9 constitutes a self-oscillation system mainly based on the resonance signal of the series resonance circuit. Furthermore, since the current limiting section 24 is provided,
As described above, an excessive current does not flow to the piezoelectric element 9, which has a low impedance in an unloaded state.

FIG. 7 shows a specific embodiment of the present invention. The same numbers as before indicate components having the same functions.

26 is a resistor constituting the current detection section, and this detection signal is transmitted via the capacitor 26 to the complementary 3EPP
It is sent to the type amplifier circuit, and through the inductor 23 by the operation of the switching transistors 27 and 28 in this output stage,
It is transmitted to the piezoelectric element 9. The amplifier circuit includes a resistor (
29, 30, 31° 32.33, 34.35), transistor (27° 28.36.37), and capacitor 3
It consists of 8. This closed loop forms a self-oscillation system with an oscillation period determined by the inductor 23 and the piezoelectric element 90 equivalent capacitance CB. Furthermore, since the output stage is a switching operation, the thermal loss of the transistor itself is small.
The amplifier section is also designed to reduce power consumption. Also, 2
The constant current section of 4 is a resistor (39°40), ) run raster 4
1. It is composed of a constant voltage diode 42, and supplies a predetermined current to the atomizer oscillation drive section including the amplification section 22. 43
is a commercial power supply, 44 is a transformer, 46 is a rectifying diode bridge, and 46 is a smoothing capacitor.

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

(1) In addition to the atomizer itself having a compact configuration, the power consumption of the drive device is reduced, and the atomizer can be driven efficiently.

(2) The current limiter regulates the current flowing to the electric vibrator, so even if the electric vibrator is in a no-load state and the impedance of the electric vibrator is extremely reduced, the electric power will be maintained. The structure of the atomizer will not be damaged due to overfilling.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing an embodiment of the present invention, Fig. 2 is an electrical equivalent circuit diagram of a piezoelectric element, Fig. 3 is a current characteristic diagram with respect to drive frequency, and Fig. 4 is a graph showing current and atomization with respect to drive frequency. 6 is a block diagram of an atomizing device according to an embodiment of the present invention, FIG. 6 is a block diagram of an atomizing device according to another embodiment of the present invention, and FIG. 7 is a block diagram of an atomizing device according to another embodiment of the present invention. FIG. 2 is a circuit diagram showing an example. 1... Pressure chamber, 2... Body, 6...
...Supply section, 7...Nozzle section, 9...
. . . Piezoelectric element, 17 . . . Oscillation drive unit, 21.
...Current detection section, 22...Amplification section, 23
...Inductor, 24...Current limiting section. Name of agent: Patent attorney Toshio Nakao and 1 other WJ
Figure 1 / θ Figure 2-4 t, s /1 \ \ / Figure 3 / Figure 4 Figure 5 Figure 6

Claims (3)

[Claims] (1) A body including a pressurizing chamber filled with liquid, a supply section for supplying liquid to the pressurizing chamber, a nozzle section having a nozzle facing the pressurizing chamber, and the nozzle. an oscillation drive unit that supplies a constant current drive signal to the atomizer; (2) An oscillation drive unit comprising a current detection unit that detects the current flowing through the atomizer, an amplification unit that amplifies the signal of the current detection unit, and an inductor that couples the output of the amplification unit and the atomizer. An atomizing device according to claim 1, comprising: (3) The atomizing device according to claim 2, further comprising: the oscillation drive section and a current limiting section that limits the current flowing to the atomizer to a predetermined value or less.