JP3304401B2 - Ultrasonic atomizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic atomizer for atomizing a liquid by elastic vibration generated by an ultrasonic exciter.

[0002]

2. Description of the Related Art Conventional ultrasonic atomizers include an ultrasonic atomizer using a bolted Langevin type vibrator and a nebulizer. The atomization device using the 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 fog, but has the disadvantage that the structure is complicated and the device is large-scale. Have. On the other hand, nebulizers use ultrasonic waves in the MHz range, and have the advantage of fine particles and excellent uniformity, but have the disadvantage of poor atomization efficiency and the difficulty of generating large amounts of fog with low power. Have.
That is, the conventional ultrasonic atomizer has a problem in atomization efficiency, mass atomization, fineness of particles, or driving power supply cost.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide atomization efficiency, large-volume atomization, fine and uniform particle size, small and lightweight device, simple structure, and low driving power cost. SUMMARY OF THE INVENTION An object of the present invention is to provide an ultrasonic atomizing device that can be satisfied from any aspect of the invention.

[0004]

According to a first aspect of the present invention, there is provided an ultrasonic atomizing apparatus comprising: an ultrasonic exciter having a vibrator fixed to a piezoelectric vibrator; and a liquid supply means. In an ultrasonic atomizing device that atomizes the liquid supplied from the supply unit to the vibrating body by elastic vibration generated by the ultrasonic exciter,
The piezoelectric vibrator includes a piezoelectric ceramic and film-shaped electrodes A formed on both end surfaces perpendicular to the thickness direction of the piezoelectric ceramic.
And B, the entire shape of the piezoelectric vibrator including the piezoelectric ceramic and the electrodes A and B is a plate shape having first and second plate surfaces substantially parallel to each other, and the vibrating body has a thickness of A fixed plate-shaped body, fixedly and integrally fixed to the first or second plate surface of the piezoelectric vibrator, and a fixed portion fixed to an end of the piezoelectric vibrator; A vibrating portion extending in the direction of the first or second plate surface of the piezoelectric vibrator, wherein the vibrating portion has a curved structure having a curved portion in which a plate-like body is bent in at least a partial region. The curved portion has a large number of holes, and receives the liquid from the liquid supply means on one side surface of the curved portion, and secures the piezoelectric vibrator to the piezoelectric vibrator when the piezoelectric vibrator vibrates. Vibrates in such a manner that the portion has a fixed end, and the liquid supply means And supplying the liquid to the curved portion in a space open to the atmosphere.

An ultrasonic atomizer according to a second aspect is characterized in that the curved surface forming the surface of the curved portion is a trough-shaped cylindrical surface.

According to a third aspect of the present invention, in the ultrasonic atomizing apparatus, the liquid supply means includes a liquid retaining material that absorbs the liquid, the liquid retaining material has a lower acoustic impedance than the piezoelectric vibrator, and a sponge. Other substances with high liquid absorption capacity,
The liquid is supplied to the curved portion by partially contacting the concave side of the curved portion.

According to a fourth aspect of the present invention, in the ultrasonic atomizing device, one opening area and another opening area of the vibrating portion in the hole are different from each other. Claim 5
The ultrasonic atomizer described in (1) is characterized in that a resonance frequency of the piezoelectric vibrator is substantially equal to a resonance frequency of a complex of the piezoelectric vibrator and the vibrator.

[0008]

When the ultrasonic atomizer of the present invention is used, an AC signal having a frequency substantially equal to the resonance frequency of the composite of the piezoelectric vibrator and the vibrating body is applied to the piezoelectric vibrator, and the piezoelectric vibrator is subjected to the piezoelectric vibration. The child is excited. Excitation of the piezoelectric vibrator causes the vibrating body to vibrate. The liquid supplied to the vibrator is atomized through a hole provided in the vibrator.
Atomization through holes promotes fineness and uniformity of particles, and can increase atomization efficiency. In addition, since the atomization efficiency is high, a large amount of atomization can be realized with low power consumption and the size of the apparatus can be easily reduced. Since self-excited driving is possible and driving with batteries is easy, driving with low power consumption is possible in a form that can respond to environmental changes. Further, since at least a part of the vibrating part has a curved structure, it is possible to diverge the fog existing area.

The piezoelectric vibrator comprises a piezoelectric ceramic and electrodes A and B formed on both end surfaces perpendicular to the thickness direction of the piezoelectric ceramic. An AC voltage is applied to the piezoelectric vibrator via the electrodes A and B, and the piezoelectric vibrator is excited. The adoption of the piezoelectric vibrator having such a simple structure makes it possible to reduce the size of the ultrasonic atomizing device, and furthermore, this device can atomize the liquid with high efficiency.

The vibrating body is the electrode A of the piezoelectric vibrator.
Alternatively, since the vibrating portion vibrates in a form having the fixed portion as a fixed end by being integrally and continuously fixed on at least one end surface having B, the liquid supplied to the vibrating portion is It is atomized by the elastic vibration and is emitted as mist upward of the vibrating part.

The means for supplying the liquid to the vibrating section includes:
A liquid retaining material for absorbing the liquid and supplying the liquid to the vibrating section; Since the liquid retaining material is in contact with the concave portion of the curved structure in the vibrating portion, the liquid supplied to the concave portion is atomized toward the convex portion of the curved structure through a hole provided in the vibrating portion. Is done. Atomization through the holes promotes fineness and uniformity of the particles and can not only increase the atomization efficiency but also diverge the direction of the atomized fog.

Since one opening area of the vibrating portion in the hole is larger than the other opening area, by setting one opening as the inlet side and the other as the outlet side, the liquid passage area of the hole is reduced to the inlet side. And decrease toward the exit side.
Thus, as the liquid passes through the hole, the liquid is squeezed by the hole. As a result, the synergistic effect of the throttling action and the vibration of the vibrating section promotes the atomization action of the liquid, increasing the amount of mist generated and making the particle diameter uniform.

When a voltage at which the resonance frequency of the piezoelectric vibrator becomes substantially equal to the resonance frequency of the composite of the piezoelectric vibrator and the vibrating body is applied to the piezoelectric vibrator, the vibrating body is efficiently operated. And the atomization efficiency is promoted, and the amount of fog generated further increases.

[0014]

FIG. 1 is a perspective view showing an embodiment of an ultrasonic atomizer according to the present invention. In this embodiment, the piezoelectric vibrator 1 and the vibrating body 2
And a liquid retaining material 3. A terminal made of copper foil is fixed to the piezoelectric vibrator 1 with a conductive adhesive. A vibrating body 2 is provided on the piezoelectric vibrator 1. In FIG. 1, a power supply circuit for supplying an AC voltage to the piezoelectric vibrator 1 and terminals are omitted. The vicinity of the center of the vibrating body 2 is curved.
The liquid retaining material 3 is in contact with the curved concave portion of the vibrating body 2 and supplies the liquid from the liquid retaining material 3 to the concave portion in use.

FIG. 2 is a side view showing an embodiment of a composite including the piezoelectric vibrator 1 and the vibrating body 2, and FIG. 3 is a plan view of the composite of FIG. The piezoelectric vibrator 1 is a rectangular plate-shaped piezoelectric ceramic 11.
The piezoelectric ceramic 11 is made of TDK72A (product name), its length is 10 mm, its width is 9 mm, and its thickness is 1 m
m. The TDK72A material has a large electromechanical coupling coefficient, and is therefore used in the examples here. Piezoelectric ceramic 11
The direction of the polarization axis coincides with the thickness direction, and electrodes D, F and G are formed on both end faces perpendicular to the thickness direction. The electrodes D and F are provided on the same surface and are insulated from each other. The electrode D covers a portion 4.5 mm from the longitudinal end of the piezoelectric ceramic 11, and the electrode F is
It covers the remaining part which is separated by mm. The electrode D has a terminal P
Are attached, a terminal Q is attached to the electrode F, and a terminal R is attached to the electrode G. A tongue-shaped vibrating body 2 having a curved central portion is attached to one end face of the piezoelectric vibrator 1. The vibrating plate 2 is made of nickel, and is integrally fixed to the piezoelectric vibrator 1 at an elongated plate-shaped fixing portion 12, and the vibrating body 2 protruding from the piezoelectric vibrator 1 forms the vibrating portion 13. ing. The fixing portion 12 is bonded to the piezoelectric vibrator 1 via an electrode F with an adhesive. The vibrator 2 has a length of 10.5 mm, a width of 9 mm, and a thickness of 0.1 mm.
05 mm. The fixing part 12 is 1.5 mm long and 9 m wide.
m, thickness 0.05 mm. The vibrating portion 13 protrudes outward from an edge along the width direction of the piezoelectric vibrator 1.
The vibrating part 13 has a length of 9 mm, a width of 9 mm, and a thickness of 0.05 mm
It is.

FIG. 4 is a view showing a cross section of the vibrating section 13 which appears when the vibration section 13 is cut along a plane perpendicular to the plate surface. The vibrating section 13 is provided with a large number of fine holes 20 penetrating in the thickness direction. FIG. 4 shows the vertical cross-sectional shape and dimensions of the hole 20. The shape of the hole 20 is mortar-shaped, and one having an opening area larger than the other opening area is used in this embodiment, and one opening is an inlet side and the other is an outlet side. The diameter on the inlet side is 0.1 mm and the diameter on the outlet side is 0.01 mm, and the holes 20 are arranged at an equal pitch.

FIG. 5 is a partially enlarged plan view of the vibrating section 13. FIG. FIG. 5 shows the shape, arrangement and dimensions of the holes 20.

When the ultrasonic atomizer shown in FIG. 1 is driven, when an AC signal having a frequency substantially equal to the resonance frequency of the complex of the piezoelectric vibrator 1 and the vibrating body 2 is applied to the piezoelectric vibrator 1, the piezoelectric vibrator 1 is driven. Is excited. At this time, the frequency of the AC signal substantially matches one of the resonance frequencies of the piezoelectric vibrator 1 alone. Since a structure is adopted in which the vibrating body 2 is integrally connected to and fixed to at least one end face of the piezoelectric vibrator 1, the vibrating body 2 is excited with the piezoelectric vibrator 1.
Is vibrated in such a manner that the fixing portion 12 is used as a fixed end, and the elastic vibration of the vibrating portion 13 effectively functions for atomizing the liquid. The liquid retaining material 3 having a large liquid absorbing capacity and a low acoustic impedance as compared with the piezoelectric vibrator 1 is used in this embodiment. This is to prevent the ultrasonic wave from the piezoelectric vibrator 1 from propagating into the liquid via the liquid retaining material 3 and being lost, and to vibrate the vibrating body 2 efficiently. The liquid absorbed by the liquid retaining material 3 reaches the vibrating body 2 in a portion in contact with the liquid retaining material 3 and is guided to each hole 20 by capillary action. When the liquid passes through each hole 20, the liquid passage area of each hole 20 decreases from the inlet side to the outlet side.
The particles are subjected to a squeezing action by 0 and become fine and uniform particles and flow out to the exit side of the hole 20. As a result, the liquid flowing out of the hole 20 due to the throttle action and the elastic vibration of the vibrating section 13 is efficiently atomized. In addition, since the center part of the vibrating part 13 is curved, it is possible to disperse the mist ejection directions.

FIG. 6 is a diagram showing the frequency characteristics of the amplitude and phase of the admittance between the electrodes D and G in the composite of the piezoelectric vibrator 1 and the vibrator 2. In FIG. 6, the dotted line indicates the characteristics of the piezoelectric vibrator 1 alone, and the solid line indicates the characteristics of the composite of the piezoelectric vibrator 1 and the vibrator 2. Assuming that the main resonance points of the piezoelectric vibrator 1 alone are f1, f2 and f3, two new resonance points fa and fb are newly generated between f2 and f3 in the composite. fo indicates the frequency at which the amount of atomization is maximized. fo is 231 kHz, which substantially coincides with the resonance point fb of the composite,
Fb shifts toward the high frequency side as the length of the fb decreases. When fb is near f3 and the amplitude of the phase change is maximum, the maximum atomization effect is obtained. In this way, by adopting a structure in which the resonance frequency of the composite of the piezoelectric vibrator and the vibrating body is substantially equal to the resonance frequency of the piezoelectric vibrator alone, the coupling of the composite of the piezoelectric vibrator and the vibrating body is achieved. Since the vibration is increased, the amount of fog generated further increases.

FIG. 7 shows the relationship between the length of the vibrating portion 13 and the height of the mist when the length of the vibrating portion 13 is changed in the composite of the piezoelectric vibrator 1 and the vibrating body 2. It is a characteristic diagram. However, the height at this time represents the height from the highest point of the curved portion of the vibrating portion 13. When the length of the vibration part 13 was 9 mm, the height of the mist reached the maximum value of 55 cm.

FIG. 8 is a characteristic diagram showing the relationship between the length of the vibrating section 13 and the amount of atomization when the length of the vibrating section 13 is changed in a composite of the piezoelectric vibrator 1 and the vibrating body 2. It is. The atomization amount is 578cc when the length of the vibrating part is 9mm
/ H was reached.

FIG. 9 is a characteristic diagram showing the relationship between the length of the vibrating section 13 and the power consumption when the length of the vibrating section 13 is changed in the composite of the piezoelectric vibrator 1 and the vibrating body 2. is there. When the length of the vibrating part is 9 mm, the power consumption is almost 1
W.

[0023]

According to the ultrasonic atomizing apparatus of the present invention, the liquid is atomized while passing through the hole provided in the vibrating section.
The fineness and uniformity of the fog particles can be promoted. Further, since at least a part of the vibrating portion has a curved structure, it is possible to diverge the fog existing area. Since the atomization efficiency is high, a large amount of atomization can be realized with low power consumption and the size of the apparatus can be easily reduced. Since self-excited driving is possible and driving with batteries is easy, driving with low power consumption is possible in a form that can respond to environmental changes.

By adopting a simple structure comprising a piezoelectric ceramic as a piezoelectric vibrator and electrodes formed on both end surfaces perpendicular to the thickness direction of the piezoelectric ceramic, the apparatus can be reduced in size and with high efficiency. The liquid can be atomized and can be driven with low power consumption.

By adopting a structure in which the vibrating body is integrally connected to and fixed to at least one end face of the piezoelectric vibrator, the vibrating portion vibrates with the fixed portion as a fixed end. The supplied liquid is atomized by its elastic vibration and is scattered upward as mist above the vibrating part.

As the applied voltage increases, the amount of atomization also increases. Therefore, if the voltage is changed according to the purpose, the amount of atomization can be freely changed.

As means for supplying liquid to the vibrating section, a liquid retaining material for sucking up liquid and supplying the liquid to the vibrating section is provided. As the liquid retaining material, a sponge or other liquid absorbing ability is large and the acoustic impedance is higher than that of the piezoelectric vibrator. By using a low substance, not only can the liquid be supplied efficiently without waste, but also the propagation of the ultrasonic wave from the piezoelectric vibrator into the liquid is blocked, and the liquid retaining material for the excitation of the piezoelectric vibrator is used. Is also suppressed, and the excitation of the piezoelectric vibrator can vibrate the diaphragm efficiently. Therefore, it is possible to increase the atomization efficiency of liquid and to atomize a large amount of liquid with low power consumption.
In addition, the size of the apparatus can be easily reduced.

By adopting a structure in which the liquid retaining material is brought into contact with the concave portion of the curved structure in the vibrating portion, the liquid supplied to the concave portion passes through the hole provided in the vibrating portion and passes through the convex portion of the curved structure. Atomized toward. Atomization through the holes promotes fineness and uniformity of the particles and can not only increase the atomization efficiency but also diverge the direction of the atomized fog.

Since the opening area of one of the holes provided in the vibrating portion is larger than the other, the structure in which one opening is on the inlet side and the other opening is on the outlet side is used to pass the liquid. As the area decreases from the inlet side to the outlet side of the hole, the liquid is throttled by the hole as it passes through the hole. As a result, the synergistic effect of the throttling action and the vibration of the vibrating section promotes the atomization action of the liquid, thereby increasing the amount of fog generated and making the particle diameter uniform.

By employing a structure in which the resonance frequency of the composite body of the piezoelectric vibrator and the vibrating body is substantially equal to the resonance frequency of the piezoelectric vibrator alone, the combined vibration of the composite body of the piezoelectric vibrator and the vibrating body is achieved. And the amount of fog generated further increases.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of an ultrasonic atomizer according to the present invention.

FIG. 2 is a side view showing one embodiment of a composite including a piezoelectric vibrator 1 and a vibrating body 2;

FIG. 3 is a plan view of the composite of FIG. 2;

FIG. 4 is a diagram showing a cross section of a vibrating section 13 appearing when cut along a plane perpendicular to the plate surface.

FIG. 5 is a partially enlarged plan view of a vibration unit 13.

FIG. 6 is a diagram showing frequency characteristics of amplitude and phase of admittance in a composite including a piezoelectric vibrator 1 and a vibrating body 2;

FIG. 7 is a characteristic diagram showing the relationship between the length of the vibrating part and the height of the fog ejection when the length of the vibrating part is changed in a composite including the piezoelectric vibrator 1 and the vibrating body 2.

FIG. 8 is a characteristic diagram showing a relationship between the length of the vibrating portion and the amount of atomization when the length of the vibrating portion is changed in a composite including the piezoelectric vibrator 1 and the vibrating body 2.

FIG. 9 is a characteristic diagram showing a relationship between the length of the vibrating portion and the power consumption when the length of the vibrating portion is changed in a composite including the piezoelectric vibrator 1 and the vibrating body 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric vibrator 2 Vibration body 3 Liquid retention material 11 Piezoelectric ceramic 12 Fixed part 13 Vibration part 20 Hole

Claims (5)

(57) [Claims] An ultrasonic exciter comprising a vibrator fixed to a piezoelectric vibrator and liquid supply means, wherein the liquid supplied from the liquid supply means to the vibrator is supplied by the ultrasonic exciter. In an ultrasonic atomizing device that atomizes by generated elastic vibration, the piezoelectric vibrator includes a piezoelectric ceramic and film-like electrodes A formed on both end surfaces perpendicular to a thickness direction of the piezoelectric ceramic.
And B, wherein the piezoelectric vibrator and the entire piezoelectric vibrator comprising the electrodes A and B have first and second substantially parallel shapes.
The vibrating body is a plate-like body having a constant thickness, and is integrally fixed to the first or second plate surface of the piezoelectric vibrator, and The piezoelectric vibrator comprises: a fixed portion fixed to an end of the piezoelectric vibrator; and a vibrating portion extending in a direction of the first or second plate surface of the piezoelectric vibrator; Is a curved structure having a curved portion in at least a partial area, the curved portion is provided with a number of holes, and receives the liquid from the liquid supply means on one side of the curved portion, When the piezoelectric vibrator vibrates, the piezoelectric vibrator vibrates with the fixed part as a fixed end, and the liquid supply unit supplies the liquid to the curved part in a space open to the atmosphere. Ultrasonic atomizer characterized by the above-mentioned. 2. The ultrasonic atomizer according to claim 1, wherein the curved surface forming the surface of the curved portion is a gutter-shaped cylindrical surface. 3. The liquid supply means includes a liquid retaining material that absorbs the liquid, wherein the liquid retaining material is a sponge or another substance having a large liquid absorbing capacity, having a lower acoustic impedance than the piezoelectric vibrator, The ultrasonic atomizer according to claim 1 or 2, wherein the liquid is supplied to the curved portion by partially contacting a concave portion side of the curved portion. 4. An ultrasonic atomizer according to claim 1, wherein one opening area of said vibrating portion and said other opening area of said vibrating portion in said hole are different from each other. 5. The ultra-compound according to claim 1, wherein a resonance frequency of the piezoelectric vibrator is substantially equal to a resonance frequency of a composite of the piezoelectric vibrator and the vibrating body. Sonic atomizer.