JP2008207052A - Ultrasonic atomizing device and equipment provided with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic atomizing device which is capable of preventing the damage of a piezoelectric element due to heat by using a piezoelectric element having low-frequency band and has improved atomization efficiency by intensively radiating the atomized liquid and equipment provided with the same. <P>SOLUTION: The ultrasonic atomizing device 10 is provided with a PZT vibrator 13 generating ultrasonic wave having 20-80 kHz frequency band, a resonator 14 resonating with the vibration of the PZT vibrator 13 to generate resonance wave and a plurality of projecting parts 15 attached to the resonator 14 on the side opposite to the PZT vibrator 13 side to propagate the resonance wave from the resonator 14 through the inside. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultrasonic atomizing device that can atomize a liquid using ultrasonic waves, and equipment equipped with the ultrasonic atomizing device, and in particular, an ultrasonic atomizing device that uses a piezoelectric element having a low frequency band, and It relates to the equipment provided.

  Conventionally, there is an ultrasonic atomization device that atomizes a liquid by an ultrasonic atomization technique. Such an ultrasonic atomizer applies a pulse voltage to a PZT (lead zirconate titanate) vibrator, which is a piezoelectric element, and oscillates the PZT vibrator to generate ultrasonic waves to atomize the liquid. ing. Such an ultrasonic atomizer is used for medical applications such as nebulization of medicines and disinfectants (for example, nebulizers (inhalers)), and for air conditioning applications such as humidifying indoor air. There are many uses.

  As such, “in an ultrasonic atomizing device that atomizes a liquid by elastic vibration generated by an ultrasonic exciter in which a tongue-shaped diaphragm is fixed to a piezoelectric vibrator, the liquid is contained. An ultrasonic atomizing device that includes a liquid storage chamber and means for guiding the liquid from the liquid storage chamber and dropping the liquid onto the vibration plate, and the vibration plate has a plurality of holes. '' It has been proposed (see, for example, Patent Document 1). In addition, “an ultrasonic vibrator made of a piezoelectric material, a liquid container for containing a liquid, and a water absorption band in which one end is inserted into the liquid container and the other end is in contact with the entire vibration end face of the ultrasonic vibrator”. An ultrasonic atomizer has been proposed (see, for example, Patent Document 2).

Japanese Patent No. 2644621 (2nd, 3rd page, 1st and 2nd figures) JP 2003-181347 A (3rd page, FIG. 1)

  The ultrasonic atomizing device described in Patent Document 1 is such that a liquid is directly dropped onto a diaphragm provided with a large number of holes for determining the atomized particle diameter to atomize the liquid. . However, this ultrasonic atomizing apparatus has a problem that, as time passes, a large number of holes provided in the diaphragm are clogged with dust, dust, and chalk in the liquid, and the holes are blocked. This problem leads to an inability to stably supply the atomized liquid. In addition, since the liquid is atomized at a high frequency of 100 kHz or more, there is a problem that strong amplitude is generated and the diaphragm is damaged by heat. Therefore, in order to prevent the diaphragm from being damaged by heat, the diaphragm must always be wetted with liquid.

  The ultrasonic atomizer described in Patent Document 2 sucks up a liquid in a water absorption zone and supplies the liquid directly to an ultrasonic vibrator to atomize the liquid. However, this ultrasonic atomizer has a problem that it becomes impossible to absorb the liquid while the water absorption zone is in use due to various germs and chalk contained in the liquid. Moreover, like the ultrasonic atomizer described in Patent Document 1, when the liquid is atomized at a high frequency of 100 kHz or more, there is a problem that the diaphragm is damaged by heat. Further, although a fan can be provided to obtain a spray distance, there is a problem that the atomized liquid diffuses over a wide range.

  The present invention has been made to solve the above-described problems. By using a piezoelectric element having a low frequency band, the piezoelectric element is prevented from being damaged by heat, and the atomized liquid is radiated intensively. The ultrasonic atomizer which improved the atomization efficiency by this, and the equipment provided with the same are provided.

  An ultrasonic atomization apparatus according to the present invention is an ultrasonic atomization apparatus that atomizes a liquid by ultrasonic waves, and is configured by a piezoelectric element, and a vibrator that generates ultrasonic waves in a frequency band of 20 kHz to 80 kHz; A resonator that is attached to the vibrator and generates a resonance wave by resonating with the vibration of the vibrator, and is attached to the opposite side of the resonator to the vibrator side, and the resonance wave from the resonator is And a plurality of protrusions that propagate.

  Moreover, the equipment according to the present invention includes the above-described ultrasonic atomizer.

  An ultrasonic atomization apparatus according to the present invention includes a vibrator that generates ultrasonic waves in a frequency band of 20 kHz to 80 kHz, a resonator that generates resonance waves by resonating with vibrations of the vibrator, and the resonator. Since the plurality of protrusions through which the resonance wave propagates are provided, the atomized liquid can be concentratedly emitted from the tip surface of the protrusion. In addition, since a vibrator that generates an easily available frequency band can be used, it is possible to prevent the vibrator from being damaged by heat generated by the vibration of the vibrator.

  Moreover, since the installation apparatus which concerns on this invention is equipped with said ultrasonic atomizer, it has all the effects of an ultrasonic atomizer.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing a schematic configuration of an ultrasonic atomizer 10 according to an embodiment of the present invention. Based on FIG. 1, the structure of the ultrasonic atomizer 10 is demonstrated. This ultrasonic atomizer 10 atomizes liquids such as water and chemicals by generating ultrasonic waves. FIG. 1A shows a longitudinal sectional view of the ultrasonic atomizing device 10, and FIG. 1B shows a plan view of the ultrasonic atomizing device 10. In addition, in the following drawings including FIG. 1, the relationship of the size of each component may be different from the actual one.

  As shown in FIG. 1A, the ultrasonic atomizer 10 is configured by laminating a support portion 11, a pedestal 12, a PZT vibrator 13, a resonator 14, and a protrusion 15 in order. Yes. The ultrasonic atomizing device 10 is characterized in that a liquid atomized by ultrasonic waves (hereinafter referred to as an atomized liquid) is radiated in a concentrated manner from the tip surface of the protrusion 15. That is, the ultrasonic atomizing device 10 can arbitrarily determine the size of the atomized particle diameter of the atomized liquid by providing the protrusion 15 so as to improve the atomization efficiency. It has become.

  The support part 11 is for attaching the ultrasonic atomizer 10 to the housing | casing etc. of the installation apparatus with which the ultrasonic atomizer 10 is installed. As shown in FIG. 1B, the support portion 11 has a circular planar shape. In addition, the support part 11 is not limited to circular shape, What is necessary is just the shape according to the equipment with which the ultrasonic atomizer 10 is attached. The pedestal 12 is attached to one side (the upper side in the drawing) of the support portion 11 and is for fixing the PZT vibrator 13. The pedestal 12 also has a circular planar shape like the support portion 11, but the planar shape is not limited to a circular shape.

  The PZT vibrator 13 is a piezoelectric element made of lead zirconate titanate, and oscillates when a pulse voltage is applied via the positive electrode terminal portion 17 and the negative electrode terminal portion 18. That is, the PZT vibrator 13 has a circular planar shape, and is applied with a pulse voltage to generate a sound wave (ultrasonic wave) in a predetermined frequency band (general frequency band: 20 kHz to 80 kHz). It has the function as an ultrasonic transducer that generates Here, a case where one PZT transducer 13 is provided in the ultrasonic atomizer 10 is shown as an example, but a plurality of PZT transducers 13 are overlapped and provided in the ultrasonic atomizer 10 as a bimorph structure. You may do it. If the PZT vibrator 13 has a bimorph structure, the oscillation of the PZT vibrator 13 can be made stronger.

  FIG. 1 shows an example in which the positive electrode terminal portion 17 and the negative electrode terminal portion 18 penetrate the support portion 11 and the pedestal 12 and are connected to the PZT vibrator 13. However, the present invention is not limited to this, and may be connected to the PZT vibrator 13 without penetrating the support portion 11 and the base 12. Further, the PZT vibrator 13 also has a circular planar shape like the support portion 11 and the pedestal 12, but the planar shape is not limited to a circular shape, and may be a polygonal shape.

  The resonator 14 is attached to the PZT vibrator 13 and resonates due to the oscillation of the PZT vibrator 13. That is, the resonator 14 causes a resonance phenomenon in the primary vibration mode (broken line A shown in FIG. 1A) of the ultrasonic frequency generated by the oscillation of the PZT vibrator 13. The resonator 14 has a circular planar shape, is attached to the PZT vibrator 13, has an internal space, and a side surface that accommodates the PZT vibrator 13 and the pedestal 12 in the internal space. Is attached to the support portion 11. That is, the resonator 14 covers the surface of the PZT vibrator 13 (the surface on the side opposite to the pedestal 12 side) to protect the PZT vibrator 13 without directly contacting the liquid. It has a function to amplify oscillation.

In addition, the resonator 14 should just be comprised with the metal, and does not specifically limit a material. That is, the material of the resonator 14 may be determined according to the application of the ultrasonic atomizer 10, particularly the liquid to be atomized. If the ultrasonic atomizer 10 is used for sterilization by using a chemical (for example, H ₂ O ₂ (hydrogen peroxide solution)) as the liquid, the resonator 14 can be prevented from being corroded by the chemical. Such a metal material (for example, an alloy of nickel (Ni) and copper (Cu)) may be used. Then, the progress of corrosion due to the chemical can be prevented.

  As shown in FIG. 1A, the protrusion 15 is formed in a truncated cone shape, and a plurality of protrusions 15 are provided on the upper surface of the resonator 14 (the surface opposite to the side on which the PZT vibrator 13 is attached). It has been. Further, the protrusion 15 can be arbitrarily changed in the diameter of the tip surface (hereinafter simply referred to as the tip diameter) by about 5 to 10 μm (micrometer). Since the liquid can be atomized with an atomization particle size similar to the tip diameter of the projection 15, the tip diameter of the projection 15 may be determined according to the desired atomization particle size. The height h of the protrusion 15 will be described in detail with reference to FIG.

  The protrusion 15 is provided so that there is no gap (that is, a smooth surface) on the upper surface of the resonator 14. This is because if there is a gap on the upper surface of the resonator 14, the liquid will be atomized, and the atomized liquid cannot be concentratedly emitted from the protrusion 15. Further, if the area of the gap that exists in the resonator 14 is smaller than the area of the tip surface of the protrusion 15, the atomized liquid can be prevented from radiating from the gap. Furthermore, even if the gap existing on the upper surface of the resonator 14 is roughened, the atomized liquid can be prevented from radiating from the gap.

  The protrusion 15 and the resonator 14 may be formed as separate bodies, and the protrusion 15 may be attached to the resonator 14, or the protrusion 15 and the resonator 14 may be formed integrally. Moreover, the protrusion part 15 should just be metal, and does not specifically limit a material. For example, when the protrusion 15 is configured separately from the resonator 14, the protrusion 15 may be formed of the same material as the resonator 14 or may be formed of a different material. Furthermore, the number of the protrusions 15 is not particularly limited, and it is preferable that the number of protrusions 15 is such that there are not many gaps on the upper surface of the resonator 14.

  Here, although the case where the projection part 15 is comprised by the truncated cone shape is shown as an example, it is not limited to this. If the shape of the bottom surface of the protrusion 15 is circular as in the shape of a truncated cone, a gap is likely to exist on the upper surface of the resonator 14. Therefore, by forming the protrusion 15 in the shape of a truncated pyramid (a triangular frustum, a quadrangular frustum, a hexagonal frustum, etc.), it is possible to prevent a gap from being present on the upper surface of the resonator 14 as much as possible. Further, it is possible to prevent the atomized liquid from radiating from the gap by placing silicon rubber or the like in the gap existing on the upper surface of the resonator 14.

  FIG. 2 is an enlarged longitudinal sectional view showing the sectional structure of the protrusion 15 in an enlarged manner. The details of the protrusion 15 will be described with reference to FIG. First, radiation of the atomized liquid will be briefly described. As described above, the resonator 14 causes a resonance phenomenon by the primary vibration mode of the ultrasonic wave generated from the PZT vibrator 13. Due to the resonance phenomenon of the resonator 14, a resonance wave having a resonance frequency of the primary resonance mode is generated from the resonator 14. By this resonance wave, the liquid is atomized and emitted. The atomized liquid generated based on such a principle has a large atomized particle size and cannot be concentrated. That is, the atomization efficiency is extremely low.

  Therefore, in this ultrasonic atomizing device 10, the projecting portion 15 is provided on the resonator 14 so that the atomized particle diameter of the atomized liquid can be made extremely small and concentrated radiation of the atomized liquid can be performed. It is. In this ultrasonic atomizing device 10, by providing the projecting portion 15 on the resonator 14, the resonance wave generated by the resonator 14 propagates to the projecting portion 15, and the resonance wave propagates in a fixed manner inside the projecting portion 15. As a result, resonance waves (ultrasound) are generated from the tip surfaces of all the plurality of protrusions 15 provided on the upper surface of the resonator 14 (broken line B shown in FIG. 2).

  That is, in the ultrasonic atomizing device 10, in the process in which the resonance wave generated by the resonator 14 is fixedly propagated inside the protrusion 15, multiple times of “antinodes” and “nodes” are generated by the primary resonance mode of this resonance wave. The height h of the protrusion 15 is set so that resonance appears strongest on the tip surface of the protrusion 15, so that the atomized liquid can be concentrated and radiated, and the tip diameter of the protrusion 15 is a desired size. Therefore, the atomized particle diameter of the atomized liquid can be made extremely small. Therefore, the ultrasonic atomizer 10 can be made high in atomization efficiency.

  The height h of the protrusion 15 for making the resonance wave strongest on the tip surface of the protrusion 15 can be calculated as follows. The height h of the protrusion 15 is determined as one wavelength or a quarter wavelength calculated by the following relational expression. That is, C = fλ (C is the speed of sound (the speed of sound during solid propagation in the case of metal is about 5000 m / s), f is the frequency, and λ is the wavelength). The length h is determined. When 40 kHz ultrasonic waves are generated from the PZT vibrator 13, the relational expression is 5000 = 40000 × λ, and the height h (for one wavelength) of the protrusion 15 is λ = 0.125 m.

  Actually, even if the height h of the protrusion 15 is set to ¼ wavelength, since the resonance wave is fixedly propagated in the protrusion 15, 0.125 m ÷ 4 = about 0.03 m (that is, 3 cm). That is, the height h of the protrusion 15 can be determined depending on the size of the equipment in which the ultrasonic atomizer 10 is installed and the application (particularly, the method of using the atomized liquid). Further, as described above, the tip diameter of the protrusion 15 can be determined to be about 5 to 10 μm in order to form the atomized particle diameter of the atomized liquid in a desired size. Therefore, an atomized liquid having an arbitrary atomized particle diameter can be radiated intensively from the protrusion 15 and the atomization efficiency can be improved.

  Further, the ultrasonic atomizing device 10 according to this embodiment may generate a frequency band of about 20 kHz to 80 kHz that is easily available to the PZT vibrator 13 constituting the piezoelectric element. By using it, there is an advantage that the amplitude is increased and the sound pressure level of the generated ultrasonic wave is high. Further, since the generation frequency of the PZT vibrator 13 is relatively low, 20 to 80 kHz, there is no problem such as heat treatment of the PZT vibrator 13 generated in a frequency band higher than this band. There is no need to keep it wet with liquid. Therefore, even when the case where the liquid cannot be supplied occurs, damage to the PZT vibrator 13 due to heat can be prevented.

  FIG. 3 is a plan view showing a state in which the ultrasonic atomizer 10 provided with the protrusions 15a is viewed from above. Based on FIG. 3, the structure of the protrusion part 15a of the shape different from the protrusion part 15 is demonstrated. Although the protrusion 15 described above is configured as a truncated cone, the protrusion 15a illustrated in FIG. 3 is configured as a truncated pyramid (hexagonal truncated cone). In other words, if the shape of the bottom surface is polygonal like the protrusion 15a, the gap existing on the upper surface of the resonator 14 can be made uniform, so it is easy to eliminate or reduce this gap. It can be realized.

  FIG. 4 is an explanatory diagram for explaining an installation example of the ultrasonic atomizer 10. Based on FIG. 4, the installation example of the ultrasonic atomizer 10 is demonstrated. In FIG. 4, the case where the ultrasonic atomizer 10 is installed in the atomizing duct 20 is shown as an example. As shown in FIG. 4, when the ultrasonic atomizer 10 radiates liquid, the atomizing liquid (hereinafter simply referred to as source water 22) is supplied from the source water tank 21 into the atomization duct 20. Supplied. Then, when the source water 22 reaches the tip surface of the projection 15 inside the atomizing duct 20, the atomization of the source water 22 is started.

  That is, a pulse voltage is applied to the PZT vibrator 13 via the positive electrode terminal portion 17 and the negative electrode terminal portion 18 connected to the PZT vibrator 13, and the PZT vibrator 13 oscillates. Resonator 14 covering 13 resonates. The resonance wave generated in the resonator 14 propagates to the protrusion 15, and the resonance wave is fixedly propagated in the protrusion 15, whereby all the plurality of protrusions provided on the upper surface of the resonator 14. A resonance wave is generated on the surface of the tip 15. At this time, the source water 22 that fills the tip surface of the protrusion 15 is atomized.

  Further, the entire resonator 14 resonates due to the oscillation of the PZT vibrator 13. That is, the resonator 14 is vibrated, and the resonance wave is radiated from the entire resonator 14 into the atomizing duct 20. The atomizing duct 20 functions as an ultrasonic waveguide, and a resonance wave (ultrasonic vibration wave) generated from the entire resonator 14 is propagated in the atomizing duct 20. Become. Therefore, by installing the ultrasonic atomizing device 10 in the atomizing duct 20, there is no propagation of air from the outside of the atomizing duct 20, and attenuation of resonance waves can be reduced.

  That is, the resonance wave generated from the entire resonator 14 propagates through the atomizing duct 20 while repeating the density. By installing the ultrasonic atomizer 10 in the atomizing duct 20 in this way, attenuation of the resonance wave generated from the entire resonator 14 can be reduced, and the length of the atomizing duct 20 is increased. Even so, the ultrasonic vibration wave can be propagated over a long distance. Therefore, the ultrasonic atomizing device 10 can be installed in the atomizing duct 20 in accordance with the application of the equipment in which the ultrasonic atomizing device 10 is installed.

  As equipment that can install the ultrasonic atomizer 10 according to this embodiment, for example, an indoor unit of an air conditioner such as an air conditioner or a freezer, a nebulizer (inhaler), a deodorizer, a sprayer, a humidifier, There are refrigerators. That is, the ultrasonic atomizer 10 can be installed in any equipment that needs to atomize and emit liquid. Moreover, when the ultrasonic atomizer 10 is provided in an indoor unit, it can be used for the sterilization use in an indoor unit, and when the ultrasonic atomizer 10 is provided in a refrigerator, the food in a warehouse is dried. It can also be used to prevent it.

  In the embodiment, the PZT vibrator 13 is described as an example of the piezoelectric element, but the present invention is not limited to this. For example, a piezoelectric element such as a ceramic piezoelectric element or a polymer piezoelectric element may be used. The atomization duct 20 described with reference to FIG. 4 may be installed according to the equipment that installs the ultrasonic atomizer 10. Further, the atomizing duct 20 may be configured in a cylindrical shape, may be configured in a prismatic shape, and the inside may be hollowed out in a cylindrical shape. In this case, the support portion 11 may also have a shape corresponding to the shape of the atomizing duct 20.

It is a schematic block diagram which shows schematic structure of the ultrasonic atomizer which concerns on embodiment. It is an expanded vertical sectional view which expands and shows the cross-sectional structure of a projection part. It is a top view which shows the state which looked at the ultrasonic atomizer which provided the projection part from the top. It is explanatory drawing for demonstrating the installation example of an ultrasonic atomizer.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Ultrasonic atomization apparatus, 11 Support part, 12 base, 13 PZT vibrator, 14 Resonator, 15 Protrusion part, 15a Protrusion part, 17 Positive electrode terminal part, 18 Negative electrode terminal part, 20 Atomization duct, 21 Source water tank, 22 Source water.

Claims (6)

An ultrasonic atomizer that atomizes a liquid by ultrasonic waves,
A vibrator configured of a piezoelectric element and generating ultrasonic waves in a frequency band of 20 kHz to 80 kHz;
A resonator attached to the vibrator and generating a resonance wave by resonating with the vibration of the vibrator;
An ultrasonic atomizing device, comprising: a plurality of protrusions attached to an opposite side of the resonator to the vibrator side and through which a resonance wave from the resonator propagates. The ultrasonic atomizer according to claim 1, wherein the protrusion is configured as a truncated cone shape or a truncated pyramid shape. The height of the protrusion is
The ultrasonic atomizer according to claim 1 or 2, wherein the ultrasonic atomizer is set as one wavelength or a quarter wavelength calculated based on a sound speed and a frequency of a sound wave generated from the vibrator. The ultrasonic atomizing device according to any one of claims 1 to 3, wherein a diameter of a tip surface of the protrusion is set in a range of 5 µm to 10 µm. The ultrasonic atomizer according to any one of claims 1 to 4, wherein the resonator and the protrusion are made of the same metal material. The equipment provided with the ultrasonic atomizer in any one of the said Claims 1-5.

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