JPS6051010B2 - Ultrasonic humidifier oscillation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an oscillation device for an ultrasonic humidifier equipped with an electrostrictive vibrator for atomization. A configuration that is set to substantially match a resonance frequency due to higher-order vibration of a longitudinal vibration mode specific to the electrostrictive vibrator, which exists within the range of a resonant frequency of a thickness vibration mode specific to the vibrator and an anti-resonance frequency. By doing so, it is an object of the present invention to provide an oscillation device for an ultrasonic humidifier that can improve atomization efficiency using an electrostrictive vibrator.

An ultrasonic humidifier has an electrostrictive vibrator installed at the bottom of a water tank, and this electrostrictive vibrator is supplied with oscillation output from a high-frequency oscillation circuit to drive the electrostrictive vibrator and generate ultrasonic waves. The water in the aquarium is irradiated with sound waves to form a water column in the area irradiated with the ultrasonic waves to atomize the water, and this atomized water is blown out of the aquarium along with the wind from the blower to humidify the room. It is configured.

Therefore, the inventor of the present application conducted calculations, experiments, and considerations as described below regarding the oscillation device of such an ultrasonic humidifier using a disk-shaped electrostrictive vibrator as an example. For example, a disc-shaped electrostrictive vibrator with a thickness of 1 and a diameter of d has two vibration modes: a thickness vibration mode and a radial longitudinal vibration mode, which is a longitudinal vibration mode. Since there are concentric nodes on the strained vibrator that do not vibrate according to the vibration order of the radial longitudinal vibration mode, the radial longitudinal vibration mode becomes a so-called node vibration mode. The resonant frequency Fr of the thickness vibration mode of such an electrostrictive vibrator
) When finding solutions to the eigenvalues such as the anti-resonant frequency Fa and the resonant frequency Fn due to the n-th vibration of the node vibration mode,
As the boundary conditions, a peripheral end surface free condition and a side surface free condition can be given. The solution that satisfies the peripheral end surface free condition is the ratio (1/d) between the thickness 1 and the diameter d of the electrostrictive vibrator.
When (1/d) is relatively small, the solution approximates the measured value well, and a solution that satisfies the side surface free condition closely approximates the measured value when (1/d) is relatively large. Also, regarding the solution of the eigenvalue of the nodal vibration mode, as the vibration order ``n'' increases, the solution that satisfies the lateral free condition will more closely approximate the measured value.Taking these things into consideration, , 1=1.21wgnNd=
20TWL or (1/d) = 0.0 longitudinal elastic modulus E = 1
0.25×10″ONIm) Poisson’s ratio V■0.33
For the electrostrictive vibrator, given the circumferential end face free condition, the resonance frequency Fr of the thickness vibration mode and the resonance frequency F, where the vibration order n of the nodal vibration mode is 1st to 5th order.
By calculating the lateral free condition, the resonance frequency F3 to Fl where the vibration order n of the nodal vibration mode is 3rd to 16th order is calculated.
6 was calculated. These calculated values and experimentally measured values are shown in FIG. 1 as a resonance frequency characteristic curve. 1st
In the figure, the horizontal axis represents the vibration order n of the nodal circular vibration mode, and the vertical axis represents the resonance frequency Fn. ．． The values are expressed in terms of Fr, with actual measured values indicated by O and calculated values indicated by X. From this Figure 1, the resonant frequency Fr of the thickness vibration mode (actual value = 1738 KHz)
, calculated value = 1766 KHZ), the 14th and 1st resonance frequencies of the nodal circular vibration mode Fl4 (actual value = 17
It can be seen that 17 K pressure, calculated value = 1724 KHZ) and Fl5 (actual value = 1806 KHZ, calculated value = 1806 KHZ) are present. This will become clear in FIG. 2, which will be described later. Figure 2 shows the frequency-impedance characteristic curve of an electrostrictive resonator, where the horizontal axis represents the excitation frequency f of the electrostrictive resonator and the vertical axis represents its impedance Z.
In the figure, among point A where the impedance Z is rapidly attenuated and points B and C where spurious waves due to higher-order vibrations appear, B and C correspond to the above-mentioned nodal circular vibration mode. They correspond to the 14th and 1st European resonant frequencies Fl4 and Fl3, respectively, and A corresponds to the resonant frequency Fr of the thickness vibration mode, and in the figure, the peak point D of the impedance Z corresponds to the resonant frequency of the thickness vibration mode. It corresponds to the resonance frequency Fa. Conventionally, in ultrasonic humidifiers, the frequency of the oscillation output supplied from the high frequency oscillation circuit to the electrostrictive vibrator, that is, the excitation frequency f of the electrostrictive vibrator, is set to a value at which the impedance Z is minimum. That is, it is common knowledge to set it near the resonance frequency Fr of the thickness vibration mode. Figure 3 shows an electrostrictive vibrator. It shows the results of an experiment conducted for the purpose of investigating the relationship between the excitation frequency f and the amount of atomized water generated by excitation driving of the electrostrictive vibrator when the excitation frequency f was changed, The horizontal axis represents the resonance frequency f of the electrostrictive vibrator, and the vertical axis represents the relative value of the atomized water amount M! where the input P of the electrostrictive vibrator is used as a parameter. As is clear from FIG. 3, the amount of atomized water M is maximum when the excitation frequency f of the electrostrictive vibrator is the resonance frequency Fr of the thickness vibration mode.
This is not when the frequency is near the resonant frequency Fl5 of the first vibration of the nodal vibration mode. this is,
When the electrostrictive vibrator is excited at the resonant frequency Fr in the thickness vibration mode, the electrostrictive effect of the electrostrictive vibrator is almost only in the thickness vibration mode; When excited at the resonance frequency Fn of the n-th vibration of the nodal vibration mode that exists between the resonance frequency Fr of the vibration mode and the anti-resonance frequency Fa, the electrostrictive effect due to the thickness vibration mode and the nodal vibration mode are generated. This is thought to be because the electrostrictive effects react with each other to produce a synergistic effect, and as a result, the efficiency of the atomization action of the electrostrictive vibrator is improved.
Therefore, if the above-mentioned facts are taken together, the excitation frequency f of the electrostrictive vibrator exists between the resonant frequency Fr and the anti-resonant frequency Fa of the thickness vibration mode unique to the electrostrictive vibrator. n-th longitudinal vibration mode specific to the electrostrictive vibrator
It was concluded that the atomization efficiency of the electrostrictive vibrator can be improved by setting it to approximately match the resonance frequency Fn due to the next vibration. It will be done. An embodiment of the present invention based on the above conclusion will be described below with reference to FIGS. 4 and 5.

First, to describe the schematic configuration according to FIG. 4, reference numeral 1 is a water tank with an open top surface disposed inside an outer box (not shown). A cover plate 2 is attached, and a spout 3 is formed at the upper left side, and an air outlet 4 is formed at the right side. 5 has an opening 5 in the center
A support body has a flange 5b on the outer periphery of the lower part, which is fitted into a mounting opening 6 formed at the bottom of the water tank 1 to correspond to the spout 3, and the flange 5b is attached to the backing. It is attached to the bottom of the water tank 1 via 7 with screws or the like.

Then, an electrostrictive transducer 8, for example, in the form of a disk, is arranged at the bottom of the support 5 with a sealing member 9 in between so as to close the opening 5a, and the ultrasonic transducer 8 is connected to the support. 5
It is held by a holder 10 attached to the bottom of the body by screws or the like. At this time, the thickness l and diameter d of the electrostrictive vibrator 8
, between the resonance frequency Fr of the thickness vibration mode and the anti-resonance frequency Fa specific to the electrostrictive vibrator 8, there is a resonance of, for example, the first song vibration of the resonance frequency Fn due to the n-th vibration of the nodal circular vibration mode. Settings are made so that spurious at frequency Fl5 appears. Reference numeral 11 denotes a blower, which includes a blower blade 12 facing the blower opening 4 and a drive motor 13 for rotationally driving the blower blade 12.

Now, the configuration of the electric circuit will be described according to FIG. 1
Reference numeral 4 denotes a DC power supply constituted by a full-wave rectification circuit using a rectifier diode 15. One terminal of a plug 17 is connected to one AC input terminal 14a via a power switch 16, and the other AC input Plug 17 into terminal 14b
At the same time, the two human power terminals of the drive motor 13 described above are connected between the two AC input terminals 14a and 14b of the DC power supply 14. Then, a smoothing capacitor 18 is connected between both DC output terminals of the DC power supply 14, and one DC bus bar 20 is connected to one DC output terminal via a choke coil 19 for high frequency cutoff, and the other DC output The other DC bus 21 is connected to the terminal. 22 is an oscillation transistor whose collector is connected to one DC bus 20;
The emitter is connected to the DC bus 21 through a parallel circuit of a resistor 23 and a capacitor 24.

The oscillation transistor 22 includes an oscillation capacitor 25,
26 and the equivalent inductance of the electrostrictive vibrator 8 for atomization constitute a self-excited Colpitts-type high frequency oscillation circuit 27. For this purpose, one oscillation capacitor 25 is connected to the DC bus 20, 21, and the other oscillation capacitor 26 is connected between the base of the oscillation transistor 22 and the DC bus 21. 28 is an output transformer that couples the oscillation transistor 22 and the electrostrictive resonator 8; one end of its primary winding 29 is connected to the DC bus 20, and the other end is connected to the oscillation transistor 22 via a coupling capacitor 30. The electrostrictive vibrator 8 is connected to the base, and the electrostrictive vibrator 8 is further connected to the secondary winding 31 of the output transformer 28.

32 and 33 are a bias resistor and a variable resistor, respectively;
These internal resistors 32 are connected between the DC bus 20 and the base of the oscillation transistor 22, and a variable resistor 33 for setting the amount of humidification is connected between the base of the oscillation transistor 22 and the DC bus 21.

In this case, the resonant frequency of the oscillation transistor 22, in other words, the excitation frequency f of the electrostrictive resonator 8, is determined by the self-inductance of the primary and secondary sides of the output transformer 28,
It is determined by the self-inductance of the electrostrictive vibrator 8 and the capacitance of the oscillation capacitors 25 and 26. Therefore, by appropriately selecting the constants of each of these elements,
The resonant frequency of the oscillation transistor 22 is determined by the longitudinal vibration mode inherent to the electrostrictive vibrator 8, which exists between the resonant frequency Fr of the thickness vibration mode inherent to the electrostrictive vibrator 8 and the anti-resonance frequency Fa. It is set to substantially match the resonance frequency Fl5 of the first vibration vibration in the barrel nodal vibration mode. At this time, the error in the oscillation frequency of the oscillation transistor 22 is allowed up to approximately 20 KHz above and below, according to the experimental results of the inventor of the present application. Next, the operation of this embodiment having the above configuration will be explained.
Now, when the water 34 is supplied to the specified water level in the aquarium 1, the plug 17 is inserted into a single-phase AC power outlet (not shown), and the power switch 16 is then closed, the drive motor 13 is energized. At the same time, a single-phase AC power is applied between the AC input terminals 14a and 14b of the DC power supply 14, and a DC output smoothed by the smoothing capacitor 18 is obtained between the DC output terminals of the DC power supply 14. The DC output is sent to the choke coil 19 and the DC bus 20.
and 21 to the high frequency oscillation circuit 27. Then, the oscillation transistor 22 is applied with a bias voltage via the resistor 32 and the variable resistor 33, and starts oscillating.
The high frequency oscillation circuit 27 starts oscillation operation to excite and drive the electrostrictive vibrator 8. The excitation frequency f of the electrostrictive vibrator 8 at this time substantially coincides with the resonant frequency Fl5 of the first oscillation in the nodal vibration mode of the electrostrictive vibrator 8, as described above. When the electrostrictive vibrator 8 is excited and driven, it generates ultrasonic waves, and the ultrasonic waves are transmitted to the water tank 1 through the opening 5a of the support 5.
The water 34 inside is irradiated. As a result, the portion of the water 34 that has been irradiated with the ultrasonic wave swells up into a water column 35 as shown in FIG. 4, and at the same time generates a minute water mist around this water column 35. On the other hand, the blower blade 12 is connected to the drive motor 1
3, the air is sucked in from outside the outer box and blown into the aquarium 1 from the air outlet 4 as shown by the arrow 36. At the same time, the air is ejected from the ejection port 3 to the outside, thereby humidifying the room. As described above, in this embodiment, the thickness I and the diameter d of the electrostrictive vibrator 8 are set as a node between the resonant frequency Fr and the anti-resonant frequency Fa of the thickness vibration and dynamic mode specific to the electrostrictive vibrator 8. The oscillation frequency of the oscillation transistor 22 of the high frequency oscillation circuit 27, in other words, the excitation frequency number f of the electrostrictive vibrator 8 is set so that a spurious of the resonance frequency Fl5 due to the first vibration in the circular vibration mode appears. The high frequency oscillation circuit 27 is set to substantially match the resonant frequency Fl5.
The oscillation output is supplied to the electrostrictive vibrator 8.

Therefore, as is clear from the above-mentioned conclusions of the experiments conducted by the inventor of the present application, the work efficiency of the electrostrictive vibrator 8 is due to the synergistic effect of the electrostrictive effect of the thickness vibration mode and the electrostrictive effect of the nodal vibration mode. Since the atomization efficiency increases due to the effect, the atomization efficiency by the electrostrictive vibrator 8 can be improved. Furthermore, according to this embodiment, the electrostrictive vibrator 8 is used in a region where its impedance Z increases as its excitation frequency f increases (see FIG. 2), that is, in an inductive load region. Therefore, when designing the high-frequency oscillation circuit 27, the electrostrictive vibrator 8 can be treated as an inductive load, and the design is relatively easy. It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, but can of course be implemented with appropriate modifications within the scope of the gist.

As described above, the present invention can provide an oscillation device for an ultrasonic humidifier that can improve atomization efficiency using an electrostrictive vibrator.

[Brief explanation of the drawing]

1 to 3 show calculation and experimental results according to the present invention, FIG. 1 is a resonance frequency characteristic curve diagram, and FIG.
The impedance characteristic curve diagram, FIG. 3, is a frequency-atomized water characteristic curve diagram. FIGS. 4 and 5 are a schematic vertical sectional view and an electric circuit diagram, respectively, showing one embodiment of the present invention. In the figure, 1 is a water tank, 8 is an electrostrictive vibrator, 22 is an oscillation transistor, 25 and 2
6 is an oscillation capacitor, 27 is a high frequency oscillation circuit, 28 is an output transformer, and 30 is a coupling capacitor.

Claims (1)

[Claims] 1. In an ultrasonic humidifier equipped with an electrostrictive vibrator for atomization and a high-frequency oscillation circuit for exciting and driving this electrostrictive vibrator, the excitation frequency of the electrostrictive vibrator is set to a frequency unique to the electrostrictive vibrator. The electrostrictive vibrator is characterized by being set to substantially match the resonant frequency due to the higher-order vibration of the longitudinal longitudinal vibration mode inherent in the electrostrictive vibrator, which exists between the resonant frequency of the thickness vibration mode and the anti-resonance frequency of the electrostrictive vibrator. Ultrasonic humidifier oscillation device.