JPS6366267B2 - - 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. .

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. In particular, as the ambient temperature changes, the mechanical resonance point at which the piezoelectric element vibrates efficiently also changes, so a method has been adopted in which the oscillation frequency is changed to follow the fluctuation of the resonance point.

For example, as seen in Japanese Patent Publication No. 50-13657, ``Ceramic Body Driving Method,'' the center frequency of a phase shifter is shifted to follow the resonance frequency deviation due to changes in ambient temperature, and the phase difference between voltage and current is reduced. Alternatively, there have been methods such as changing the oscillation frequency of the oscillator using a signal from a phase difference detector so that the voltage and current to the piezoelectric element are in the same phase.

However, the conventional atomizing device having an ambient temperature compensation function has to have an oscillator for generating a piezoelectric element drive signal, a phase detector, etc., and has to have a complicated structure as a whole.

Purpose of the Invention In order to eliminate such conventional drawbacks, the present invention is a simple oscillation drive unit constructed by focusing on the fact that an atomizer has capacitance characteristics, and also has an ambient temperature compensation function. The purpose is to provide an atomization device.

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 section having a nozzle provided therein, and an electric vibrator that energizes the nozzle section to vibrate the nozzle, and a current detector that detects the current flowing through the atomizer. , an oscillation drive unit is constituted by an amplification unit that amplifies the signal of the current detector and an inductor that transmits the signal from the amplification unit to the atomizer, and the equivalent capacitance change of the atomizer with respect to temperature is It has a compensator that compensates for the change in the inductor and makes the oscillation frequency of the oscillation drive unit follow the change in the mechanical resonance point of the atomizer, and the atomizer, the oscillation drive unit, and the compensator described above are combined. It constitutes the entire atomization device.

With this configuration, the series resonant section mainly consisting of the equivalent capacitance of the inductor and the atomizer, and the amplifier section form a self-oscillation system, and the temperature characteristic compensator compensates for changes due to temperature in the series resonant section. Then, the oscillation frequency of the oscillation drive section is changed to follow the temperature shift of the mechanical resonance point that efficiently operates as an atomizer.

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 during the atomization operation, the gas discharge pipe 6 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. Reference numeral 10 denotes a lead wire for transmitting a drive signal to the piezoelectric element 9, one of which is soldered to one electrode surface of the piezoelectric element 9, and the other 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 vibrates, so that the liquid in the pressurizing chamber 1 is discharged as atomized particles 12 as a result.

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 The inside of the exhaust pipe 6 is empty, and before entering the droplet discharge sequence, for example, negative pressure may be applied through the exhaust pipe 6 to fill the pressurized chamber 1 with liquid and to draw the liquid to the middle of the exhaust pipe 6. 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 is an electrical equivalent circuit that approximates the piezoelectric element 9, with 13 equivalent parallel capacitances C _S , 14,
15 and 16 series inductance Lo,
It consists of a capacitance Co and a resistance Ro.

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. It shows the characteristics when loaded and the empty state with no liquid, that is, the characteristics when there is no load. In the no-load characteristics shown by the solid line, at electrical resonance frequency ₁ , Lo14 and Lo14 shown in Fig. 2 are shown.
Series resonance of Co15 occurs, and the peak value of the drive current appears. Also, the electrical anti-resonance frequency ₂
In this case, parallel resonance occurs between Lo14 and Cs13 shown in FIG. 2, and the drive current becomes a minimum value. _{The r} shown in the figure is approximately the intermediate frequency between ₁ and ₂ , which is called the mechanical resonance frequency. The broken line in Figure 3 is the current value under load, which is not extremely large compared to the current values ₁ and ₂ above when no load.

FIG. 4 shows changes in current value and changes in atomization amount with respect to changes in drive frequency under load. The amount of atomization reaches its maximum value when the mechanical resonance frequency is r. When actually spraying, operate at a drive frequency near this r.

FIG. 5 is a block diagram of an inductor-coupled self-oscillation system that transmits a signal from the amplifier section 18 to the atomizer (piezoelectric element 9 as a vibration source) via the inductor 17. 19 is a current detector that detects the current flowing through the atomizer. From FIG. 3 mentioned above, the drive current I increases as the drive frequency increases,
It can be seen that it exhibits capacity characteristics as an atomizer. If this equivalent capacitance is expressed as C _T and the inductor 17 is L, then the oscillation frequency o of the oscillation drive section shown in FIG. 5 is determined by o=1/ _2π√T . In this basic configuration, by appropriately adjusting the value L of the inductor 17, it is possible to drive the atomizer to oscillate at its mechanical resonance point. This configuration does not require an external oscillator.

A in FIG. 6 shows the change characteristic of the equivalent capacitance C _T (pF) with respect to the change in the ambient temperature Ta (° C.), which increases as the temperature rises. B in Figure 6 is the temperature Ta
The changes in the mechanical resonance point r of the atomizer (solid line) and the change in the oscillation frequency in the self-excited oscillation circuit system shown in FIG. Ta≒
Even if the oscillation frequency is adjusted to the mechanical resonance point (for example, ≈50 (kHz)) by adjusting the inductance L at 20°C, the difference between the temperature change in the inductance L and the equivalent capacitance C _T shown in Figure 6A is Depending on the value of the temperature change, it may not follow the temperature characteristics of the mechanical resonance point. The example of the dashed-dotted line in FIG. 6B is, for example,
This is a case where the change in C _T due to temperature is so large that the oscillation frequency becomes below the mechanical resonance point at high temperatures. At this time, the exchange rate for converting electrical energy into mechanical energy of the piezoelectric element is low, and the amount of atomization also decreases as shown in FIG.

The present invention will be described below, in which a compensator is used to track a mechanical resonance point in a self-oscillation system that treats the capacitance characteristics of an atomizer as an oscillation element.

FIG. 7 is a block diagram showing an embodiment of the present invention, and the same numbers as those in FIG. 5 are components having the same functions. A and B are capacitors 20 and 21 as compensators connected in parallel and series with the atomizer, respectively, and the change due to temperature is the sixth
By compensating for the change in C _T shown in Figure A, the resonance characteristics with the inductor match the temperature characteristics of the mechanical resonance point. The oscillation frequency at A is capacitor 2
If 0 is C ₁ , it is determined by = 1/2π√( _T + ₁ ). In order to compensate for the characteristics indicated by the dashed-dotted line in Figure 6B, ₍ C _T +
It is sufficient to select a capacitor C ₁ that reduces the rate of temperature change in C ₁ ). The oscillation frequency in FIG. 7B is determined as follows, assuming that the capacitor 21 is _C2 .

= 1/2π√( _{T 2} ) In this case as well, it is sufficient to select C ₂ in which the composite characteristic of C _T C ₂ is such that the temperature change rate of only C _T decreases. In this way, using a capacitor connected in parallel or in series as a compensator is used when the temperature change in the equivalent capacitance C _T of the atomizer itself is large and the temperature change in the coil, etc. that acts as an inductor is small and cannot be compensated for. It is an effective method.

FIG. 8 is a specific circuit diagram showing one embodiment of the present invention. The compensator has a capacitor 20 connected in parallel with the piezoelectric element 9 of the atomizer. Amplification section 1
8 is a transistor (22, 23, 24, 25),
Resistance (26, 27, 28, 29, 30, 31, 3
2), the current detector 19 is composed of a resistor 35. 36 is a DC power supply. The signal from the current detector 19 is sent to the complementary SEPP type amplification section through the capacitor 34, and the inductor 1
7 to the piezoelectric element 9 and the compensator 20.

Effects of the Invention According to the atomizer of the present invention, in addition to the compact structure of the atomizer itself, the structure of the oscillation drive section is simple, and the atomizer operates efficiently by the compensator. Mechanical resonance point tracking can be achieved.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, and FIG.
The figure is an equivalent circuit diagram of a piezoelectric element, Figure 3 is a current characteristic diagram with respect to drive frequency, Figure 4 is a characteristic diagram of current and atomization amount with respect to drive frequency, and Figure 5 is a block diagram of an inductor-coupled self-oscillation system. , FIG. 6A shows the temperature characteristics of the atomizer equivalent capacity, B shows the temperature characteristics of the mechanical resonance point and the oscillation frequency in the self-oscillation system, and FIGS. 7A and B show an example of the present invention. FIG. 8 is a specific circuit diagram of the present invention. DESCRIPTION OF SYMBOLS 1... Pressure chamber, 2... Body, 5... Supply part, 7... Nozzle part, 9... Piezoelectric element, 17...
Inductor, 18...amplifying section, 19...current detector, 20, 21...capacitor as compensator.

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; a current detector that detects the current flowing through the electric vibrator; and an amplification unit that amplifies the signal of the current detector;
an oscillation drive section including an inductor that transmits a signal from the amplification section to the atomizer; and an oscillation drive section that compensates for changes in the equivalent capacitance of the atomizer and changes in the inductor with respect to temperature. and a compensator for causing the oscillation frequency of the atomizer to follow changes in mechanical resonance of the atomizer. 2. The atomization device according to claim 1, wherein the compensator is constituted by a capacitor connected in parallel or in series with the atomization device.