JPH04207800A - Ultrasonic atomizer - Google Patents

Abstract

PURPOSE:To enhance atomization efficiency by constituting a piezoelectric vibrator of piezoelectric magnetism and electrodes respectively fixed to both end faces, providing a diaphragm at least at one point in the position covering the aperture of a through-hole or in the through-hole and boring many holes on the diaphragm, thereby forming the diaphragm. CONSTITUTION:The disk-shaped diaphragm 2 is mounted in the position covering the aperture of the through-hole at the bottom end face of the piezoelectric vibrator 1. The diaphragm 2 is made of nickel and is integrally and continuously foxed to the piezoelectric vibrator 1 by an annular fixing part 21. The liquid housed in a liquid housing tank 4 is introduced into the respective holes 40 by capillarity. Since the aperture areas on one side of the holes 40 are larger than the aperture areas on another side, the liquid receives a throttling effect by the holes 40 and flows out to the upper part of the vibrating part 20. Consequently, the liquid flowing out of the holes 40 is atomized by the throttling effect, the coupling vibrations of the vibrating part 20 and the effect of shielding the liquid from the piezoelectric vibrator 1 by a supporting plate 3. The atomization efficiency thereof is thus enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an ultrasonic atomizer that atomizes liquid by using elastic vibrations generated by an ultrasonic exciter.

(Prior Art) Examples of conventional ultrasonic atomizers include ultrasonic atomizers and nebulizers that utilize a bolted Langevin type vibrator. The atomization device using a bolted Langevin type vibrator uses ultrasonic waves with a frequency of several tens of kHz, and has the advantage of generating a large amount of mist.
It also has the disadvantages of being complex in structure and dependent on equipment.

On the other hand, nebulizers utilize ultrasonic waves in the MHz range, and although they have the advantage of fine particles and excellent uniformity, they have the disadvantages of poor atomization efficiency and difficulty in generating a large amount of mist.

(Problems to be Solved by the Invention) Conventional ultrasonic atomizers have problems with either atomization efficiency, large amount of atomization, fineness and uniformity of particles, or cost of driving power source.

The objects of the present invention are atomization efficiency, large amount atomization, fineness of particles,
It is an object of the present invention to provide an ultrasonic atomizer that is satisfactory in terms of uniformity and drive power cost.

(Means for Solving the Problems) The ultrasonic atomization device according to claim 1 is an ultrasonic atomization device that atomizes liquid by using elastic vibrations generated by an ultrasonic exciter including a piezoelectric vibrator and a vibration plate fixed to the ultrasonic atomization device. The sonic atomizer includes means for supplying the liquid to the diaphragm, and the piezoelectric vibrator has end faces on both sides perpendicular to the polarization axis, and has a hole extending parallel to the polarization axis. The diaphragm is composed of a columnar piezoelectric ceramic and electrodes fixed to each of the end faces, and the diaphragm is arranged at least at one location covering the opening of the through-hole or inside the through-hole substantially parallel to the end face. 3. The ultrasonic atomizer according to claim 2, wherein the diaphragm is provided with a large number of holes, and the ultrasonic exciter has a lower acoustic impedance than the piezoelectric vibrator. affixed to a support plate made of low styrofoam or other material that holds the ultrasonic exciter in position relative to a fixed object or suspends the ultrasonic exciter in the liquid by buoyancy; The ultrasonic atomizer according to claim 3, characterized in that the opening area of one side of the diaphragm in the hole and the opening area of the other side of the diaphragm are different from each other. The oscillation device includes a fixed part in which the diaphragm is fixed to the piezoelectric vibrator and a vibrating part surrounded by the fixed part, and one of the resonant frequencies of the piezoelectric vibrator is the same as that of the piezoelectric vibrator. 6. The ultrasonic atomizer according to claim 5, wherein the ultrasonic atomizer has a resonance frequency substantially equal to one of the resonant frequencies of the complex with the diaphragm, wherein the liquid supply means includes a liquid storage chamber and a resonant frequency from the liquid storage chamber. The ultrasonic atomizer according to claim 6, further comprising a tube for supplying liquid to the vibration plate, wherein the liquid supply means leads out the liquid from the liquid storage chamber and the liquid storage chamber. 8. The ultrasonic atomizer according to claim 7, further comprising means for causing the droplet to drop onto a diaphragm, wherein the piezoelectric vibrator has a rectangular or annular shape, and the piezoelectric vibrator has a polarization axis in the direction of the polarization axis of the piezoelectric vibrator. Use of the ultrasonic atomizer according to claim 1, characterized in that the ratio of the dimension to the dimension of a straight line connecting the outer edge and the inner edge of the end face and perpendicular to both edges is approximately equal to 1. At this time, an alternating current signal having a frequency approximately equal to the resonant frequency of the composite of the piezoelectric vibrator and the diaphragm is applied to the piezoelectric vibrator, and the piezoelectric vibrator is excited.

The excitation of the piezoelectric vibrator causes the vibration plate to vibrate, and the liquid supplied to the vibration plate is atomized by the effect of a large number of holes provided in the vibration plate. The piezoelectric vibrator is made up of a columnar piezoelectric ceramic having end faces on both sides perpendicular to the polarization axis, a hole extending parallel to the polarization axis, and electrodes fixed to each of the end faces. A voltage is applied to the piezoelectric vibrator via the electrode. Since the diaphragm is provided at least at one location covering the opening of the through hole or inside the through hole substantially parallel to the end surface, the vibration energy of the piezoelectric vibrator is efficiently transferred to the diaphragm. Since the diaphragm is vibrated, the atomization efficiency can be increased. Therefore, in the device of the present invention, by employing a piezoelectric vibrator with a simple structure and providing a diaphragm at a predetermined position with respect to the through hole of the piezoelectric vibrator, the device can be made compact, and moreover, the liquid Furthermore, the large number of holes provided in the diaphragm promotes fineness and uniformity of the mist particles. Further, by using a plurality of diaphragms, the fineness of the mist particles can be improved.

In the ultrasonic atomization device according to the second aspect, the ultrasonic exciter is fixed to a support plate made of foamed polystyrene or other material whose acoustic impedance is lower than that of the piezoelectric vibrator. The support plate holds the ultrasonic exciter in place relative to a fixed object or suspends the ultrasonic exciter in the liquid by buoyancy. At this time, the support plate or
By being made of foamed polystyrene or other material that has a lower acoustic impedance than the piezoelectric vibrator, the support plate suppresses the vibration energy of the piezoelectric vibrator from leaking into the fixed object or the liquid, and prevents the piezoelectric vibrator from leaking into the fixed object or the liquid. The excitation is efficiently transmitted to the diaphragm. Therefore, efficient atomization can be achieved.

In the ultrasonic atomization device according to claim 3, the atomization effect of the liquid is further promoted by the opening area of one side of the diaphragm being different from the area of the other opening of the diaphragm in the hole. and the particle diameter becomes uniform.

The ultrasonic atomization device according to claim 4 includes a fixed part in which the diaphragm is fixed to the piezoelectric vibrator, and a vibrating part surrounded by the fixed part, and the vibrating part is connected to the piezoelectric vibrator. The liquid supplied to the vibrating section is atomized by the combined vibration and is dispersed upward perpendicularly to the diaphragm as a mist. The vibration of the vibrating section increases the atomization efficiency of the liquid and increases the amount of mist generated.

Further, a voltage is applied to the piezoelectric vibrator when one of the resonant frequencies of the piezoelectric vibrator becomes approximately equal to one of the resonant frequencies of a composite body of the piezoelectric vibrator and the diaphragm. This promotes atomization efficiency and further increases the amount of fog generated.

In the ultrasonic atomization device according to claim 5, the liquid supply means includes a liquid storage chamber and a tube for supplying the liquid from the liquid storage chamber to the diaphragm, so that the liquid supply is not wasted. Not only can this be done more efficiently, but also it is possible to control the amount of liquid supplied to the diaphragm, so it is possible to realize the supply that provides the highest atomization efficiency.

In the ultrasonic atomization device according to claim 6, the liquid supply means includes a liquid storage chamber and a means for drawing the liquid from the liquid storage chamber and dropping it onto the vibration plate, so that the liquid supply means touches the vibration plate. By controlling the amount of liquid, it is possible to always supply the amount of liquid that provides the highest atomization efficiency. Further, the liquid can be supplied efficiently without waste.

In the ultrasonic atomization device according to claim 7, the piezoelectric vibrator has a rectangular or annular shape, and the dimension in the direction of the polarization axis of the piezoelectric vibrator and the outer edge and inner edge of the end face are connected to both edges. By adopting a structure in which the ratio of the vertical linear dimension is approximately equal to 1, the coupled vibration of the composite of the piezoelectric vibrator and the diaphragm is enhanced, and the atomization efficiency is further increased.

(Example) Next, the present invention will be described in more detail with reference to Examples. 1st
The figure is a sectional view showing an embodiment of the ultrasonic atomization device of the present invention. In this embodiment, a terminal P made of copper foil is connected via an adhesive.
It consists of a piezoelectric vibrator 1, a vibration plate 2, a support plate 3, and a liquid storage tank 4. However, FIG. 1 also shows a power supply circuit for supplying AC voltage to the piezoelectric vibrator 1, and the liquid storage tank 4 is filled with an appropriate amount of liquid during use.

An ultrasonic exciter consisting of a piezoelectric vibrator 1 and a diaphragm 2 is fixed to a support plate 3 and floated in a liquid by buoyancy during use. At this time, the support plate 3 isolates the piezoelectric vibrator from the liquid and prevents the energy of the ultrasonic vibration from being released into the liquid, so that the energy is efficiently transmitted to the signal plate 2.

FIG. 2 is a plan view of the ultrasonic exciter attached to the support plate 3 in the embodiment of FIG. 1, viewed from below;
FIG. 3 is a perspective view of the ultrasonic atomization device of FIG. 1. The piezoelectric vibrator 1 consists of a cylindrical piezoelectric ceramic 30 having six end faces on both sides perpendicular to the polarization axis and a hole penetrated flatly through the polarization axis, and the material of the piezoelectric device 30 is TDK72.
Material A (product name) has a diameter of 24 mm and a thickness of 6 mm, and the through hole is also cylindrical, and its diameter is 12 tnm.

TDK72A material is used in this second example because it has a large electromechanical coupling coefficient. An AU electrode 31 and an Au electrode 32 are formed on both end faces, respectively.

A terminal P is attached to the Au electrode 31, and the Au% electrode 32
A terminal Q is attached to the terminal.

A disc-shaped diaphragm 2 is attached to the lower end surface of the piezoelectric vibrator 1 at a position covering the opening of the through hole. Vibration plate 2
is made of nickel and is integrally fixed to the piezoelectric vibrator 1 through a ring-shaped fixing section 21, and the diaphragm 2 surrounded by the fixing section 21 forms the vibrating section 20. Fixed part 21
is fixed to the piezoelectric vibrator 1 via an Au electrode 32.

The diameter of the diaphragm 2 is 14 mm and the thickness is 0.05 mm.

The diameter of the vibrating part 20 matches the diameter of the through hole 1
2 mm, and the thickness is 0.05 mm. Vibrating part 20
is provided with a plurality of fine holes 40 that penetrate in its thickness direction. FIG. 4 is a diagram showing a cross section of the vibrating portion 20 that appears when cut along a plane perpendicular to the plate surface, and the vertical cross-sectional shape of the hole 40 is also shown in the diagram. The hole 40 has a forest-like shape, and is used in this embodiment because the opening area on the - side is larger than the other opening area, and one opening is the inlet side and the other is the outlet side. It is said that The diameter size on the population side is O,'1 ma+, the diameter size on the outlet side is 0.02 mm, and the holes 40 are arranged at equal pitches. FIG. 5 is a partially enlarged plan view of the vibrating section 20 when viewed from the exit side.

When the ultrasonic atomizer shown in FIG. Apply. The piezoelectric vibrator] is excited, and the vibrating part 20 surrounded by the fixed part 21 unitarily vibrates with the piezoelectric vibrator 1. This coupled vibration of the vibrating section 20 effectively functions to atomize the liquid.

With the combined vibration of the vibrating section 20, the liquid contained in the liquid storage tank 4 is guided to each person 40 by capillary phenomenon.

Since the opening area of one of the holes 40 is larger than the opening area of the other, if one opening is set as the inlet side and the other opening is set as the outlet side, when the liquid passes through each person 40, each person Since the passage area of the liquid 40 decreases from the inlet side to the outlet side, the liquid is subjected to a throttling action by the hole 40 and flows out to the upper part of the vibrating part 20. As a result, the aperture effect, the combined vibration of the vibrating part 20 and the support plate 3
Due to the liquid barrier effect on the piezoelectric vibrator 1,
The liquid flowing out from the holes 40 is atomized, and the atomization rate becomes high.

FIG. 6 is a characteristic diagram showing in a table the relationship between applied voltage, frequency, and power consumption and current for a composite body of three types of piezoelectric vibrators and diaphragms. ■Type and ■
The mold has a diaphragm fixed to the bottom end of the piezoelectric vibrator. The ■type has the same dimensions as the ■type, and the diaphragm is fixed to the top surface of the piezoelectric vibrator. Type (2) is a composite body of a piezoelectric vibrator 1 and a diaphragm 2 shown in the embodiment shown in FIG. The applied voltage is 10.
When the voltage is 7V, the amount of atomization reaches its maximum at a frequency of 290.6kHz, and the power consumption at that time is 320ml+ and the current is 30mA. Further, the power consumption of the entire device including the power supply is 6420 mA, and the current is 60 mA. In addition, ■
When the structure was the same as the mold, but a diaphragm was also provided on the top, the characteristics of the mold were retained, but the atomization rate decreased, but it was confirmed that it was effective in generating extremely fine mist. .

(Effects of the Invention) As explained in detail above, according to the ultrasonic atomization device of the present invention, since the liquid is atomized while passing through the holes provided in the vibrating part, the fineness of the mist particles can be reduced. , which can encourage uniformity. Furthermore, by fixing the support plate to the piezoelectric vibrator, this device can be floated in the liquid by buoyancy, and it can be constantly vibrated without being affected by the increase or decrease in the amount of liquid contained in the liquid storage tank. Since an appropriate amount of liquid is supplied to each part, efficient atomization can be achieved, and therefore a large amount of atomization can be achieved with low power consumption, and the device can also be easily miniaturized.

As a piezoelectric vibrator, we adopted a structure consisting of a columnar u:electromagnetic device with a through hole and an electrode, and also adopted a structure in which the vibration frequency was set inside the through hole or at a position covering its opening. The excitation of the vibrator efficiently vibrates the diaphragm,
Therefore, the atomization efficiency can be increased and the device can be made smaller. Furthermore, if a plurality of diaphragms are used, the fineness of the fog particles can be improved.

By using a material with lower acoustic impedance than the piezoelectric vibrator, such as styrene foam, as the support plate, not only the transmission of the excitation of the piezoelectric vibrator into the liquid is blocked, but also the vibration of the piezoelectric vibrator is Since propagation of the excitation to the support plate itself is suppressed, the excitation of the piezoelectric vibrator can efficiently vibrate the support plate. Therefore, the atomization efficiency can be increased.

By adopting a structure in which the diaphragm is integrally fixed to the inside of the through hole of the piezoelectric vibrator or at a position covering the opening thereof, the vibrating part is integrated with the piezoelectric vibrator and performs coupled vibration. The liquid that comes into contact with the vibrating part that is in a state of coupled vibration is atomized in the vertical direction. In addition, since the opening area of one of the multiple holes provided in the diaphragm is larger than the other opening area, by adopting a structure in which one opening is the inlet side and the other opening is the outlet side, liquid Since the passage area of the hole decreases from the inlet side to the outlet side of the hole, when the liquid passes through the hole, the liquid is subjected to a squeezing action by the hole. As a result, the synergistic effect of the squeezing action and the vibration of the vibrating section promotes the atomization of the liquid, increasing the amount of mist generated and making the diameter of the particles uniform.

The atomization efficiency can be improved by adopting a structure in which one of the resonant frequencies of the ultrasonic exciter as a composite of a piezoelectric vibrator and a diaphragm is approximately equal to one of the resonant frequencies of the piezoelectric vibrator. This will further increase the amount of fog generated.

As the applied voltage increases, the amount of atomization also increases, so by changing the voltage depending on the purpose, the amount of atomization can be changed freely.

By providing a liquid supply means or a liquid storage chamber and a liquid supply tube, the liquid can be supplied efficiently without waste, and therefore the atomization efficiency can be increased.

By adopting a structure in which the liquid is dropped onto the liquid supply means or the vibrating section, the supplied liquid can be efficiently atomized.

The piezoelectric vibrator has a rectangular or annular shape, and has a structure in which the ratio of the dimension in the direction of the polarization axis of the piezoelectric vibrator to the dimension of a straight line connecting the outer edge and inner edge of the end face and perpendicular to both edges is approximately equal to 1. By employing this, the combined vibration of the composite body of the piezoelectric vibrator and the diaphragm is enhanced, so that the atomization efficiency can be further increased.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of the ultrasonic atomization device of the present invention, and FIG. 2 is a plane view of the ultrasonic exciter attached to the support plate in the embodiment of FIG. 1, when viewed from below. 3 is a perspective view of the ultrasonic atomization device of the embodiment shown in FIG. 1, and FIG. 4 is a vibrating section 20 that appears when cut along a plane perpendicular to the plate surface.
5 is a partially enlarged plan view of the vibrating section 20 when viewed from the exit side, and FIG. 6 is a diagram showing the applied voltage, frequency, and It is a characteristic diagram showing the relationship between power consumption and current at that time in a table. DESCRIPTION OF SYMBOLS 1... Piezoelectric vibrator, 2... Vibration plate, 3... Support plate, 4... Liquid storage tank, 20... Vibrating part, 21...
Fixed part, 30... Piezoelectric device, 31.32... Electrode,
40...hole. Agent Patent Attorney Shinsuke Honjo"・□':,jllll)・,,゛!" Figure 1

Claims (7)

[Claims] (1) An ultrasonic atomization device that atomizes liquid by elastic vibrations generated by an ultrasonic exciter including a diaphragm fixed to a piezoelectric vibrator, comprising means for supplying the liquid to the diaphragm. The piezoelectric vibrator is made up of a columnar piezoelectric ceramic having end faces on both sides perpendicular to the polarization axis, and a columnar piezoelectric ceramic having a hole extending parallel to the polarization axis, and electrodes fixed to each of the end faces. , the diaphragm is provided at least at one location substantially parallel to the end surface at a position covering the opening of the through hole or inside the through hole, and the diaphragm is provided with a large number of holes. Ultrasonic atomization device. (2) The ultrasonic exciter is fixed to a support plate made of foamed polystyrene or other material that has a lower acoustic impedance than the piezoelectric vibrator, and the support plate holds the ultrasonic exciter in a predetermined position relative to a fixed object. The ultrasonic atomization device according to claim 1, wherein the ultrasonic exciter is held or floated in the liquid by buoyancy. (3) Claim 1 characterized in that the opening area of one side of the diaphragm in the hole and the opening area of the other side of the diaphragm are different.
or the ultrasonic atomization device according to 2. (4) The diaphragm consists of a fixed part fixed to the piezoelectric vibrator and a vibrating part surrounded by the fixed part, and one of the resonance frequencies of the piezoelectric vibrator is different from that of the piezoelectric vibrator. 4. The ultrasonic atomization device according to claim 1, wherein the ultrasonic atomization device is approximately equal to one of the resonant frequencies of the complex with the diaphragm. (5) The ultrasonic atomizer according to any one of claims 1 to 4, wherein the liquid supply means includes a liquid storage chamber and a tube for supplying liquid from the liquid storage chamber to the diaphragm. . (6) The ultrasonic atomization according to any one of claims 1 to 5, wherein the liquid supply means includes a liquid storage chamber and a means for drawing out the liquid from the liquid storage chamber and dropping it onto the diaphragm. Device. (7) The piezoelectric vibrator has a rectangular or annular shape, and the ratio of the dimension in the direction of the polarization axis of the piezoelectric vibrator to the dimension of a straight line connecting the outer edge and the inner edge of the end face and perpendicular to both edges is approximately 7. Ultrasonic atomization device according to claims 1 to 6, characterized in that: 1 is equal to 1.