JPS5913263B2 - Ultrasonic liquid atomizer - Google Patents

Description

Detailed Description of the Invention The present invention provides an ultrasonic liquid atomization device using an electrostrictive ultrasonic transducer with a frequency of several hundred KHz to several MH2. It is an object of the present invention to provide a device that can always maintain a constant state regardless of factors such as variations in strain oscillators.

In recent years, an ultrasonic liquid fuel combustion device has been provided that uses an electrostrictive ultrasonic vibrator with a frequency of several hundred KHz to several MH2 to atomize and burn liquid fuel, but this electrostrictive ultrasonic vibrator For example, when using kerosene to atomize a liquid, the amount of atomization varies greatly by about ±25% when the power supply voltage fluctuates by ±10%, and the viscosity of the liquid changes due to temperature changes. The disadvantage was that the amount of atomization fluctuated significantly. Other factors that may cause variations in the amount of atomization include electrostrictive vibrators and ultrasonic oscillators, but it is almost impossible to resolve all of these factors and stabilize the amount of atomization. . An example of a Colpitts type oscillation circuit of a conventional ultrasonic liquid atomizer is shown in FIG.

1 is a commercial AC power supply, which is connected to a double-wave rectifier diode bridge 2, and the + side of the output of this diode bridge 2 is connected to the anode of the diode 4, one end of the coil 7, and one end of the capacitor 8, and the other end is connected to the capacitor 3. , 13, one end of the resistor 6, and the emitter of the NPN transistor 15.

0 The cathode of the diode 4 is connected to the other end of the capacitor 3 and one end of the resistor 5; the other end of this resistor 5 is connected to the other end of the resistor 6 and one end of the resistor 9; The other end is connected to one end of the coil 12 and one end of the coil 14, respectively.

'5 The other end of the coil 12 is connected to one end of the capacitor 11, and the other end of the capacitor 11 is connected to the ultrasonic transducer 1.
One end of 0 is connected. The other end of the ultrasonic transducer 10 is connected to the coil 7, the other end of the capacitor 8, and the collector of an NPN transistor 15, and the base of the NPN transistor 15 is connected to the coil 14. In the conventional circuit configured as described above, the diode 4
, resistors 5, 6, 9 and capacitor 3 constitute a bias circuit 3525 for transistor 15, and coil T
, 12, 14, capacitors 8, 11, 13, transistor 15, and ultrasonic transducer 10 constitute an oscillation circuit 36.

When an AC voltage is applied from the commercial power source 1, a DC output double-wave rectified by the double-wave rectifier diode bridge 2 is applied to the 30 bias circuit 35 and the oscillation circuit 36, and the ultrasonic transducer 10 is driven. The amount of atomization is approximately proportional to the input power of the ultrasonic vibrator 10, and the internal impedance of the ultrasonic vibrator 10 in the liquid hardly changes if the phase difference between the drive voltage and the drive current is constant. However, there was a drawback that the amount of atomization varied approximately at the square of the fluctuation rate of the power supply voltage. In addition, even if the viscosity changes due to temperature changes and the driving power required to atomize a certain amount changes accordingly, only approximately the same driving power is always applied. Therefore, a phenomenon occurred in which the amount of atomization decreased.

Furthermore, the amount of atomization varies considerably depending on the phase difference between the current and voltage applied to the ultrasonic transducer 10 by the oscillator, and it is very difficult to always adjust the phase difference to the same level during mass production. It was hot.

Furthermore, when the liquid to be atomized runs out, the device is driven without load, which has the disadvantage of destroying the transistor of the oscillation circuit or the ultrasonic transducer. The ultrasonic liquid atomization device of the present invention eliminates the above-mentioned drawbacks of the conventional technology by eliminating factors related to the amount of atomization caused by factors related to the ultrasonic vibrator and the oscillation circuit. A detailed explanation will be given of a structure in which a liquid is supplied by an external oil supply device, the drive output of the ultrasonic transducer is controlled, and only the supplied amount is completely atomized.

In Fig. 1, A indicates an ultrasonic transducer drive output control circuit using a liquid level gauge, and B indicates an ultrasonic transducer drive output circuit. In the ultrasonic transducer drive output control circuit A, 16 is a resistor and one end is a diode. It is connected to the + side of the bridge 2 and the anode of the diode 18, and the other end is connected to one end of each of the resistors 17 and 19.

The other end of this resistor 19 is connected to the base of an NPN transistor 23, the emitter of this NPN transistor 23 is connected to the anode of a diode 24, the collector is connected to one end of the resistor 22, and the cathode of the diode 24 is connected to one end of the resistors 25 and 26. One end of each is connected to the collector of the NPN transistor 30. This NPN transistor 3
The emitter of the diode 29 is connected to the anode of the diode 29, the base is connected to one end of the liquid level sensor 32 and one end of the resistor 31, and the cathode of the diode 29 is connected to the anode of the resistor 27 and the constant voltage diode 28, respectively. Also, the resistor 22
The other end is connected to one end of the resistor 21 and the base of a PNP transistor 33, and the collector of the PNP transistor 33 is connected to one end of a capacitor 34 and one end of each of the resistor 5, coil 7, and capacitor 8 of the ultrasonic transducer drive circuit B. The emitter of the PNP transistor 33 is connected to the diode 18.
the cathode and one end of the capacitor 20 and the resistor 2172
5, 27, and 31, respectively. Further, the resistors 17 and 26, the capacitors 20 and 34, the other ends of the liquid level sensor 32, and the anode of the constant voltage diode 28 are connected to one side of the diode bridge 2, the resistor 6 of the ultrasonic transducer drive circuit B, and the capacitor 13. each end of and NPN
The emitters of the transistors 15 are connected to each other. Figure 2 shows the relationship between the liquid level and the resistance value of the liquid level sensor 32 when a thermistor is used.While the thermistor is immersed in the liquid, it self-generates heat due to heat dissipation to the liquid. It is difficult to use and has a high resistance value, and when the thermistor is exposed to the air due to a lack of liquid, it rapidly generates heat, the temperature rises, and the resistance value decreases. FIG. 3 shows the configuration of the ultrasonic liquid atomization device in this embodiment, where 37 is a constant flow rate supply device for liquid, 38 is an atomization tank, and 39 is a liquid atomization device.
is the liquid to be atomized.

Next, its operation will be explained.

First, in the circuit shown in FIG. 1, the transistor 30, the resistors 27 and 31, the diode 29, the constant voltage diode 28, and the liquid level sensor 32 constitute a first voltage comparator circuit C, and the voltage across the liquid level sensor 32 and the voltage diode 28
The voltage across the resistor 26 is controlled. In addition, the transistor 23 and the resistors 16, 17, 19,
25, 26 and diodes 18, 24 constitute a second voltage comparator circuit D, in which the voltage across the resistor 26 controlled by the first voltage comparator circuit C and the resistor 1 are obtained by full-wave rectification of the commercial power supply 1.
The transistor 33 is controlled by comparing the pulsating voltage across the terminal 7. Since the voltage across the resistor 17 is pulsating, the transistor 23 is turned on at twice the frequency of the commercial power supply.
The resistor 26 is turned off, and the ratio between the on time and the off time is changed by changing the voltage across the resistor 26. Therefore, since the transistor 33 is also driven on and off, a voltage is generated across the capacitor 34 that is approximately proportional to the ratio of the on time to the off time. In the device shown in FIG. 3, when liquid is supplied into the atomization tank 38 by the constant flow supply device 37, when the liquid level is low, the resistance value of the liquid level sensor 32 is low, so the voltage across both ends is low, and the No base current flows through the transistor 30 in FIG. 1, increasing the voltage across the resistor 26. Then, the transistor 23 turns on when the voltage across the resistor 17 is high, and the time in the on state becomes shorter. Therefore, the time during which the transistor 33 is in a conductive state becomes shorter, so that the voltage across the capacitor 34 decreases, lowering the driving voltage of the ultrasonic transducer 10 and reducing the amount of atomization. Here, since the transistor 30 is in a damp state when there is no liquid at all, by adjusting the settings of the second voltage comparator circuit composed of the transistor 23, the transistor 33 is brought into a damp state and ultrasonic vibrations are generated. It is also possible to completely stop driving the child 10. When the liquid level rises and attempts to rise above the reference setting level of the liquid level sensor 32, the liquid level sensor 32
resistance rises rapidly, causing the voltage across both ends to rise rapidly. Then, a base current flows through the transistor 30, lowering the voltage across the resistor 26, and the transistor 23 is turned on when the voltage across the resistor 17 is low, thereby increasing the voltage across the capacitor 34. Therefore, the amount of atomization of the ultrasonic vibrator 10 is increased, and the voltage across the liquid level sensor 32 becomes equal to the reference voltage of the constant voltage diode 28, the forward voltage of the diode 29, and the base-emitter forward voltage of the transistor 30. It becomes stable at a liquid level that is equal to the voltage value plus . As described above, atomization is performed using the liquid level sensor 28 using the circuit shown in Figure 1 so that the liquid level is always constant. If the reference level is set to 28, the amount of liquid in the atomization tank 38 will always be kept constant, so exactly the same amount of flow as the flow rate supplied by the external constant flow supply device 37 will be atomized. Become. Therefore, a constant amount of stable atomization can always be obtained without being affected by fluctuation factors such as fluctuations in the ultrasonic vibrator 10, the oscillation circuit, and power supply voltage. FIG. 4 shows another modification of the circuit of the ultrasonic liquid atomizer.

The base of a PNP transistor 40 is connected to the other end of the resistor 19 of the second voltage comparison circuit.
The cathode of the diode 41 is connected to the emitter of 0, and the resistor 42 is connected to the collector.The anode of the diode 41 is connected to one end of each of the resistors 25 and 26, and the other end of the resistor 42 is connected to one end of the resistor 43 and the base of the NPN transistor 44. is connected to. The collector of the NPN transistor 44 is connected to one end of each of the resistors 5, 6, and 9, and the emitter is connected to the other end of the resistor 43 and one side of the diode bridge 2, respectively. Since the other circuit configurations are exactly the same as those shown in FIG. 1, their explanation will be omitted. The operation of the circuit shown in FIG. 4 will be explained.

The transistor 23 in FIG. 1 is an NPN type transistor, whereas the transistor 23 in FIG. As the liquid level begins to fall, the on-state time becomes longer.
As the liquid level rises, the off-state time becomes shorter. The transistor 44 controls the bias circuit of the transistor 15 of the ultrasonic transducer drive circuit B, is connected to drive the ultrasonic transducer intermittently, and is configured to be controlled by the output of the transistor 40. Therefore, as the liquid level rises, the time during which conduction occurs between the collector and emitter becomes shorter, the time during which the ultrasonic vibrator stops driving becomes shorter, and the average drive output increases, keeping the liquid level constant.
When the liquid level begins to fall, the operation is the opposite to that described above to keep the liquid level constant. The difference between the circuit example in FIG. 1 and the circuit example in FIG. 4 is that in the circuit example in FIG. In the circuit shown in FIG. 4, the ultrasonic transducer is driven intermittently to control the average drive output.

In the above embodiments, a thermistor is used as the liquid level sensor, but any other liquid level sensor may be used as long as it can perform the same operation.

In addition, any other circuit may be used as the voltage comparison circuit and the ultrasonic transducer 1 drive circuit as long as it performs the same operation, and although the rectifier circuit is shown for full-wave rectification, it may be half-wave rectification or other type, even if it is for pulsating voltage. Therefore, in this embodiment, a liquid level sensor 32 connected in series with a resistor 31 is installed in the liquid atomizing tank 38, and the voltage across the liquid level sensor 32 is compared with a reference voltage. Either an output control circuit A having a voltage comparison circuit C of 1 is connected to the ultrasonic transducer 1 drive circuit B to control the drive output of the drive circuit B, or a pulsating voltage obtained by rectifying a commercial power source is compared with the first voltage. Is the output control circuit A, which also has a second voltage comparison circuit D that compares the output voltage of the circuit C, connected to the ultrasonic transducer drive circuit B to control the voltage supplied to the drive circuit B or the average drive output? are doing.

Therefore, since the liquid level in the liquid atomization tank 38 is kept constant, fluctuations in the power supply voltage, temperature changes, and variations in the ultrasonic transducer,
A constant amount of atomization can always be performed without being affected by variations in the oscillation circuit.

In addition, when used in a liquid fuel combustion device, the liquid fuel is supplied at the same time as the power is turned on to the ultrasonic vibrator drive control circuit, and then the combustion fan is operated to atomize a large amount at the time of startup to improve ignitability. Furthermore, since atomization is not performed unless liquid fuel is sent, it is possible to prevent destruction of the drive circuit ultrasonic vibrator that would occur when the ultrasonic vibrator is driven under no load.

As described above, the present invention connects a resistor in series to a liquid level sensor attached to a liquid atomization tank, and connects a voltage comparison circuit that compares the voltage across the liquid level sensor with a reference voltage to an ultrasonic vibrator drive circuit. This is of great industrial value as it allows a constant amount of atomization to be achieved by connecting.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of an ultrasonic liquid atomization device according to an embodiment of the present invention, Fig. 2 is a relationship diagram between the liquid level and resistance value of the liquid level sensor in the same device, and Fig. 3 is a diagram of the relationship between the liquid level and the resistance value of the liquid level sensor in the same device. FIG. 4 is a modification of the circuit diagram of the same device, and FIG. 5 is a circuit diagram of the conventional device. B... Ultrasonic transducer drive circuit, C...
Voltage comparison circuit, 10... Ultrasonic vibrator, 32.
...Liquid level sensor.

Claims (1)

[Claims] 1. A resistor is connected in series to a liquid level sensor attached to a liquid atomization tank, and a voltage comparison circuit for comparing the voltage across the liquid level sensor and a reference voltage is connected to an ultrasonic vibrator drive circuit. Ultrasonic liquid atomizer.