JPS6023017Y2 - Ultrasonic liquid atomizer - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an ultrasonic liquid atomization device that atomizes liquid using an ultrasonic vibrator.

FIG. 1 shows an excitation circuit for an ultrasonic liquid atomizer that has been commonly used in the past.

In the figure, 1 is a commercial power source including a power transformer, 2 is a diode bridge, 3 is an ultrasonic transducer, 4 is an oscillation transistor, and part A is an ultrasonic transducer excitation circuit.

Since this ultrasonic transducer excitation circuit A is a Colpitts oscillation circuit that has been used conventionally, a detailed explanation of the oscillation mechanism will be omitted.

This ultrasonic vibrator excitation circuit A oscillates at the natural frequency of the ultrasonic vibrator 3, has good frequency stability, and does not require an amplifier circuit, etc., and is a power oscillation circuit, so the utilization rate of the power source is low. In good condition.

The amount of atomization in the circuit configured in this manner can be adjusted by adjusting the base bias of the excitation transistor A.

However, this adjustment is a fixed adjustment under certain conditions, and is powerless against frequent fluctuations in the voltage of the commercial power supply and the temperature of the atomized liquid, and the amount of atomization fluctuates as shown in FIG.

These fluctuations amount to ±20 to 30% compared to the amount of atomization based on the steady state value of 100V +20°C.

In this way, the amount of atomization in conventional ultrasonic liquid atomizers varies widely depending on the ice temperature, power supply voltage, etc., so this is a problem for ultrasonic humidifiers, etc., which simply need to ensure a certain amount of atomization. However, in combustors that atomize and burn kerosene, there are problems such as the inability to obtain a constant combustion amount.

This idea was made in consideration of these points,
A constant amount of atomization can be obtained without being affected by fluctuations in liquid temperature or power supply voltage.

An ultrasonic liquid atomization device is provided. FIG. 3 is a block diagram showing an embodiment of this invention, in which a shows an oscillation circuit similar to that shown in FIG. C is a voltage fluctuation detection section that detects commercial power supply voltage fluctuations, and d is a liquid temperature detection section that detects the temperature of the atomized liquid. The oscillation time of the oscillation circuit that excites the vibrator 3 is controlled by the switching circuit as TM, TL, and TH as shown in FIG.

By controlling the oscillation period in this manner, fluctuations in the amount of atomization are prevented.

Details of this control will be explained using a specific circuit diagram shown in FIG.

In Fig. 5, 5 is a thermistor that detects the temperature of the atomized liquid, 6 is a parallel resistor 7 is a smoothing capacitor, 8 and 9 are voltage dividing resistors, and the voltages shown in block diagrams c and d of Fig. 3 are shown. They are a fluctuation detection section and a liquid temperature detection section.

10 is a collector resistor of the transistor 13, 12 is a collector resistor of the transistor 16, 11 and 22 are base resistors of each transistor, and 14.15 is a charging capacitor, which makes an astable multivibrator 30.
The collector output of this transistor 13 is connected to a resistor 20.
is connected to the transistor 21 by.

This portion constitutes the switching circuit B already shown in FIG.

Resistor 17, Zener diode 19 Smoothing capacitor 1
8 constitutes the power source of the astable multivibrator 30.

A is an ultrasonic transducer excitation circuit.

Next, the operation will be explained.

The ultrasonic vibrator excitation circuit A is a normal Colpitts oscillation circuit, and is driven by a voltage obtained by double-wave rectification of the oscillation circuit AC voltage by a diode bridge 2 and smoothed by a smoothing capacitor 7.

At the same time, stabilized power is supplied to the astable multivibrator 30 by the resistor 17, the Zener diode 19, and the capacitor 18, and the oscillation operation starts as shown by V16 in FIG.

Due to the oscillation operation of the astable multivibrator 30, the transistor 13 performs 0N10FF, and when the collector voltage of the transistor 13 becomes 1H, the switching transistor 21 is turned on via the resistor 20.

When the transistor 21 turns on, the ultrasonic transducer excitation circuit A
The base B of the oscillation transistor 4 is short-circuited, the base bias of the transistor 4 disappears, the oscillation conditions are not satisfied, and the oscillation of the ultrasonic vibrator excitation circuit A is stopped.

After a certain period of time, the astable multivibrator 30 is reversed, the transistor 13 is turned on, the switching transistor 21 is turned off, and the base B of the oscillation transistor 4 becomes a normal bias, and the oscillation condition is established again, and the oscillator 3
vibrates and resumes liquid atomization.

That is, the base B of the oscillation transistor 4 of the ultrasonic vibrator excitation circuit A is set to 0 by the output of the astable multivibrator 30.
By repeating N10FF, the oscillation of the ultrasonic vibrator excitation circuit A is repeatedly stopped, and if this oscillation period is long, the amount of atomization increases.
If the time is short, the amount of atomization will decrease.

Next, the correction operation for each variation factor will be explained.

First, we will discuss stabilizing the atomization amount in response to power supply voltage fluctuations.

When the commercial power supply voltage increases, the smoothing capacitor 7 of the power supply
As the voltage increases, the voltage shared by resistor 9 ■9
becomes higher, the charging voltage of the time constant circuit of the resistor 22 and the capacitor 14 becomes higher, the capacitor 14 is charged faster, the timing at which the transistor 16 is turned on, that is, the transistor 13 is turned off earlier, and therefore the period during which the switching transistor 21 is turned on becomes longer. Therefore, the non-bias period of the oscillation transistor 4 of the ultrasonic vibrator excitation circuit A is shortened to prevent an increase in the amount of atomization due to an increase in the power supply voltage.

Conversely, when the power supply voltage decreases, the voltage across the resistor 9 decreases, resulting in a reverse operation to that described above, which lengthens the oscillation period of the ultrasonic vibrator excitation circuit A, thereby preventing a decrease in the amount of atomization due to the voltage drop.

Therefore, the amount of atomization is prevented from increasing or decreasing due to fluctuations in the power supply voltage, and a constant volume can be achieved.

Next, the operation for preventing fluctuations due to temperature changes in the atomized liquid will be described.

When the temperature of the liquid increases, the resistance of the sursistor 5 in the liquid decreases, the partial pressure ratio of each of the resistors 8, 6, and 9 changes, and the voltage of the resistor 9 increases.

For this purpose, the same correction operation as the increase in power supply voltage accelerates r'ONJ of the switching transistor 21, shortens the oscillation period of the ultrasonic vibrator excitation circuit A, and prevents an increase in the amount of atomization due to a rise in the temperature of the atomized liquid. Conversely, when the temperature decreases, the resistance of the thermistor 5 increases, and the voltage across the resistor 9 decreases and the charging circuit 2
2.14 charging is slowed down and the oscillation period of the excitation circuit A is lengthened by the same correction operation as when the voltage drops, thereby preventing a decrease in the amount of atomization due to a drop in the atomized liquid temperature.

FIG. 7 shows the voltage across the resistor 19 and the oscillation rate (%) of the ultrasonic vibrator excitation circuit A due to this correction operation, and FIG. 8 shows the relationship between each variation factor and the oscillation rate.

In this way, 0N10FF of astable multivibrator 30
By changing the period rate (time rate) according to fluctuation factors such as voltage and liquid temperature, and by changing the oscillation period and rest period of the ultrasonic vibrator excitation circuit A to keep the atomization amount constant, the combustor It is also possible to apply this method to applications that require a uniform amount of atomization.

Although the method described above has been described in which the base B of the oscillation transistor 4 is short-circuited by the astable multivibrator 30, the same effect can be expected by directly switching the base bias of the oscillation transistor 4 as shown in FIG.

As described above, according to this invention, a constant amount of atomization can be obtained even if the temperature of the liquid to be atomized or the power supply voltage fluctuates, and there are advantages such as improved efficiency compared to the conventional method.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing a conventional excitation circuit for an ultrasonic liquid atomizer, Figure 2 is a characteristic curve diagram showing the characteristics of the circuit shown in Figure 1, and Figure 3 is an example of an embodiment of this invention. 4 is a diagram showing the operation of FIG. 3, FIG. 5 is a circuit diagram showing an example of the specific circuit of FIG. 3, and FIG. 6 is a waveform showing signal waveforms of each part of FIG. 5. Figure 7 shows the resistance 9 in Figure 5.
FIG. 8 is a diagram showing the relationship between fluctuation factors and oscillation rate, and FIG. 9 is a circuit diagram showing the main part of another embodiment of this invention. In the figure, 1 is a commercial power supply, 2 is a diode bridge,
3 is an ultrasonic transducer; 6, 8, 9. 20 are resistors, 7 is a capacitor, 21 is a switching transistor, 30 is an astable multivibrator, and A is an ultrasonic transducer excitation circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (5)

[Scope of utility model registration request] (1) In an ultrasonic liquid atomizer having an ultrasonic vibrator excitation circuit that oscillates at the natural frequency of the ultrasonic vibrator, the ultrasonic vibrator excitation circuit includes a temperature detection means for detecting the temperature of the atomized liquid; A voltage detection means for detecting an input voltage, and a switching means operated according to the output signals of both of these means, and the switching means controls the time ratio of oscillation and non-oscillation of the ultrasonic transducer excitation circuit. An ultrasonic liquid atomization device characterized by: (2) Utility model registration claim 1, characterized in that the base bias of the main oscillation transistor of the ultrasonic transducer excitation circuit is controlled by the switching means, and the time ratio of oscillation and non-oscillation is controlled. The ultrasonic liquid atomization device described in . (3) The ultrasonic liquid atomization device according to claim 1 or 2, characterized in that an astable multivibrator is used as the switching means. (4) The switching means is turned on by the astable multivibrator and the output signal of this astable multivibrator.
The ultrasonic liquid atomization device according to any one of claims 1 to 3, characterized in that the ultrasonic liquid atomization device is constituted by a switching transistor that operates in the OFF state. (5) Ultrasonic liquid atomization according to claim 4 of the utility model registration claim, characterized in that the output voltages of the temperature detection means and the voltage detection means are used as the charging voltage source of the time constant circuit of the astable multivibrator. Device.