JP3010297B2 - Ultrasonic atomizer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ultrasonic atomizing device that emits ultrasonic waves into a liquid and generates a mist from a liquid surface, and particularly relates to a medical inhaler,
The present invention relates to an ultrasonic atomizing device suitable for home ultrasonic humidifiers and the like.

(Prior Art) Conventionally, as an ultrasonic atomizing device, there is provided an atomizing chamber containing a liquid, and ultrasonic generating means for emitting ultrasonic waves to the liquid in the atomizing chamber, and the ultrasonic generating means Some have a disk-shaped piezoelectric ceramic vibrator whose one surface is immersed in the liquid.

When a conventional ultrasonic atomizer is driven, a driving signal is applied to the piezoelectric ceramic vibrator. The piezoelectric ceramic vibrator is excited, and ultrasonic waves are emitted from one surface thereof. The ultrasonic waves propagate in the liquid, and fog is generated from the liquid surface of the liquid.

(Problems to be Solved by the Invention) However, since the mist generated from the liquid surface diffuses in the horizontal direction while moving upward from the liquid surface, the mist cannot be guided in a predetermined direction. It is necessary to separately form a flow of the medium for guiding in a predetermined direction.

An object of the present invention is to provide an ultrasonic atomizing device capable of forming a directional mist flow.

(Means for Solving the Problems) The present invention is an ultrasonic atomizing apparatus including an atomizing chamber containing a liquid, and ultrasonic generating means for emitting ultrasonic waves to the liquid in the atomizing chamber. The ultrasonic wave generating means may include a vibrator including a plate-shaped piezoelectric ceramic having electrodes formed on both surfaces perpendicular to the polarization axis, and a fixing device fixed to one end of one surface of the piezoelectric ceramic. A diaphragm including a vibrating portion integrally connected to the portion and the fixed portion and protruding substantially parallel to one surface of the piezoelectric ceramic toward the outside of the piezoelectric ceramic, wherein the ultrasonic wave generating means includes: The vibrating plate is disposed so that the plate surface is substantially perpendicular to the liquid surface of the liquid, the tip of the vibrating part is immersed in the liquid, and an AC signal having a frequency equal to the resonance frequency of the vibrator is generated. The vibrator is excited by being applied to the vibrator through the electrode. By vibrating the vibrating plate with the fixed portion as a fixed end by excitation of the vibrator, the liquid in the vicinity of the distal end of the vibrating portion is atomized.

It is preferable that a characteristic frequency of the vibrating plate is equal to a resonance frequency of the vibrator, and a length dimension of the vibrating part along a projecting direction is a quarter wavelength of vibration generated in the vibrating part.

(Operation) When the ultrasonic atomizing device of the present invention is used, an AC signal having a frequency equal to the resonance frequency of the vibrator is applied to the vibrator via its electrode, and the vibrator is excited. Since the fixed portion of the vibration plate is fixed to one surface of the piezoelectric ceramic, the vibrating portion bends and vibrates in the form of a cantilever having the fixed portion as a fixed end. Ultrasonic waves are radiated in the direction perpendicular to the respective surfaces. Since at least one portion of the vibrating portion is immersed in the liquid, ultrasonic waves are radiated into the liquid from each surface of the vibrating portion located in the liquid. A droplet is generated, and the droplet is moved substantially in the ultrasonic radiation direction. As a result, a directional mist flow is formed.

Since the natural frequency of the vibrating portion of the vibrating plate is substantially equal to the resonance frequency of the vibrator, the vibrating portion of the vibrating plate vibrates at a frequency substantially equal to the natural frequency,
The frequency of the ultrasonic wave radiated from the vibrating portion of the diaphragm is substantially equal to the natural frequency of the vibrating portion. Further, since the length dimension along the projecting direction of the vibrating part is about one quarter wavelength of the vibration wave generated in the vibrating plate, the vibration part of the vibrating part has one antinode. Ultrasonic waves having high intensity radiated from the vibrating portion are concentrated on a portion corresponding to the antinode of the vibration of the vibrating portion, and the generation amount of the mist-like droplet is further increased.

(Embodiment) FIG. 1 is a longitudinal sectional view showing an embodiment of the ultrasonic atomizer of the present invention, and FIG. 2 shows an ultrasonic generator used in the ultrasonic atomizer of FIG. FIG. 3 is a side view of the ultrasonic wave generating means of FIG.

As shown in FIG. 1, the ultrasonic atomizing device 10 includes an atomizing chamber 12.
Is provided. The atomization chamber 12 has a rectangular plate-shaped bottom plate 14, each of which is integrally connected to an edge of the corresponding bottom plate 14, and four side plates 16 rising vertically from the bottom plate 14, and connected to an upper end edge of each side plate 16. And a lid plate 18 which cooperates with the bottom plate 14 and each side plate 16 to define an internal space.

One of the four side plates 16 is provided with a nozzle 20 extending in the thickness direction. Nozzle 20 is the one side plate
It is arranged near the lower end of 16. The cross-sectional shape of the nozzle 20 is quadrangular.

The side plate 16 facing the nozzle 20 is provided with a pair of gate-shaped brackets 22 that rise vertically from the inner surface thereof. Each of the brackets 22 is opposite and parallel to each other.

The cover plate 18 is provided with a nozzle 24 extending in the thickness direction. The nozzle 24 is located near the side plate 16 having the bracket 22 of the cover plate 18, and has a circular cross-sectional shape.

The liquid is stored in the atomization chamber 12. The liquid level is at a position below the nozzle 20.

The ultrasonic generating means 26 is housed in the atomizing chamber 12. The ultrasonic wave generating means 26 has a vibrator 28 as shown in FIG. 2 and FIG. The vibrator 28 includes a piezoelectric ceramic 30. According to the illustrated example, the piezoelectric ceramic 30 is made of a plate having a rectangular planar shape, and has a length of 30 mm and a width of 25 m.
m, thickness dimension is 5mm. Both surfaces of the piezoelectric ceramic 30 are perpendicular to the thickness direction, and the direction of the polarization axis coincides with the thickness direction. The material of the piezoelectric ceramic 30 is TDK91A (product name). Although a plate-shaped piezoelectric ceramic is used in the present embodiment, a columnar piezoelectric ceramic can be used instead.

An electrode 32 is formed on one surface of the piezoelectric ceramic 30, and an electrode 34 is formed on the other surface. The electrode 32 covers one surface of the piezoelectric ceramic 30, and the electrode 34 similarly covers the other surface of the piezoelectric ceramic 30. The material of each of the electrodes 32 and 34 is baked silver.
A terminal P made of copper foil is attached to the electrode 32, and a terminal Q made of copper foil is attached to the electrode 34. The terminals P and Q are located at one edge of the piezoelectric ceramic 30 along the width direction.

The vibrator 28 is mounted on each of the brackets 22 such that one surface of the piezoelectric ceramic 30 is parallel to the side plate 16 with the nozzle 20 and the longitudinal direction of the piezoelectric ceramic 30 coincides with a direction orthogonal to the liquid surface.
It is supported by. The terminals P and Q of the vibrator 28 are located on the side of the cover plate 18. The other surface of the piezoelectric ceramic 30 is fixed to each of the brackets 22. The resonance frequency of the vibrator 28 is about 57 KHz.

A vibration plate 36 is attached to one surface of the piezoelectric ceramic 30. According to the illustrated example, the vibration plate 36 is formed of a rectangular plate made of phosphor bronze, and is integrally formed with an elongated plate-shaped fixing portion 38 and one edge portion along the longitudinal direction of the fixing portion 38. And a rectangular plate-shaped vibrating portion 40 that cooperates with the fixing portion 38 to define a rectangular plate. The fixing portion 38 is bonded to the electrode 32 with an adhesive 42 such that the longitudinal direction thereof is in the width direction of the piezoelectric ceramic 30 and faces one surface thereof. The adhesive 42 is an epoxy resin-based adhesive. The length of the fixing part 38 is 25
mm, the width is 5 mm, and the thickness is 0.1 mm. The vibrating portion 40 projects outward in a direction perpendicular to the other edge along the width direction of the piezoelectric ceramic 30. The vibrating section 40 faces the nozzle 20, and its tip is immersed in liquid.
The length of the vibrating part 40 is 25 mm, the width l is 17 mm, and the thickness is 0.1 mm. The natural frequency of the vibrating section 40 is equal to the resonance frequency of the vibrator 28.

When the ultrasonic atomizer 10 is driven, an AC signal having a frequency equal to the resonance frequency of the vibrator 28 is applied to the vibrator 28 via the terminals P and Q. The vibrator 28 is excited, and the diaphragm 36 is driven in the form of a cantilever having the fixed portion 38 as a fixed end. The vibration generated in the vibration part 40 of the vibration plate 36 is bending vibration having a wavelength λ, and the vibration frequency of the vibration part 40 is
Equal to the natural frequency of Ultrasonic waves are radiated from the surface of the vibrating section 40 in the direction orthogonal to the respective planes by the vibration of the vibrating section 40. Since the tip of the vibrating part 40 is immersed in the liquid, the ultrasonic waves are radiated into the liquid, so that a mist-like droplet is generated from the liquid surface near the vibrating part 40. Since the dimension l of the vibrating section 40 and the wavelength λ of the resulting vibration satisfy the following expression (1), the tip of the vibrating section 40 corresponds to the vibration film, and therefore, radiates from the tip of the vibrating section 40. The intensity of the ultrasonic wave is increased.

l = 1 / 4λ (1) Also, since only one vibration film is generated in the vibrating part 40, ultrasonic waves having a large intensity concentrate on the tip of the vibrating part 40. As a result, the amount of mist droplets generated from the liquid surface increases.

The ultrasonic waves radiated toward the nozzle 20 into the gas in the atomization chamber 12 move the mist-like droplets in the radiation direction, thereby forming a directional mist flow. The droplet flows out through the nozzle 20 to the outside. Ultrasonic waves radiated into the liquid are reflected and absorbed by the side plate 16 facing the surface of the vibrating section 40, so that a large repeated stress acts on a boundary portion between the bottom plate 14 and the side plate 16 where stress is concentrated. Therefore, no crack or the like in the atomization chamber 12 due to the repeated stress is generated, and there is no possibility that the liquid in the atomization chamber 12 leaks to the outside.

With the generation of the mist-like droplets, the liquid level of the liquid in the atomization chamber 12 decreases. As the liquid level of the liquid decreases, the relative positional relationship between the vibrating section 40 and the liquid surface of the liquid changes, so that the amount of the atomized droplets changes. In order to maintain the generation amount of the mist droplets at a constant value, it is preferable that the liquid is supplied from the nozzle 24 and the relative positional relationship between the vibrating section 40 and the liquid surface of the liquid is maintained constant.

As described above, the ultrasonic atomizer 10 can be used as a mist generating means such as a medical inhaler or a home ultrasonic humidifier.

(Effects of the Invention) According to the present invention, ultrasonic waves are radiated from the respective surfaces of the vibrating portion of the diaphragm in directions orthogonal to each other.
The mist droplets generated by the ultrasonic waves radiated into the liquid are moved in the ultrasonic radiation direction by the ultrasonic waves radiated into the gas, so that a mist flow having directivity is formed. can do.

Since the natural frequency of the vibrating portion of the vibrating plate is substantially equal to the resonance frequency of the vibrator, the vibrating portion of the vibrating plate vibrates at a frequency substantially equal to the natural frequency,
The frequency of the ultrasonic wave radiated from the vibrating part of the diaphragm is substantially equal to the natural frequency of the vibrating part, and the ultrasonic wave can be efficiently radiated. Further, since the length dimension along the projecting direction of the vibrating part is about one quarter wavelength of the vibration wave generated in the vibrating plate, the vibration part of the vibrating part has one antinode. Ultrasonic waves of high intensity radiated from are concentrated on the part corresponding to the antinode of the vibration of the vibrating part,
The amount of mist droplets generated further increases.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the ultrasonic atomizer of the present invention, FIG. 2 is a front view showing an ultrasonic generator used in the ultrasonic atomizer of FIG. FIG. 3 is a side view showing the ultrasonic wave generating means of FIG. 10 ... ultrasonic atomizing device, 12 ... atomizing chamber, 26 ... ultrasonic generating means, 28 ... vibrator, 30 ... piezoelectric ceramic, 32, 34 ... electrode, 36 ... diaphragm, 38 …… Fixed part, 40 …… Vibration part.

Claims (2)

(57) [Claims] 1. An ultrasonic atomizing apparatus comprising: an atomizing chamber containing a liquid; and ultrasonic generating means for emitting ultrasonic waves to the liquid in the atomizing chamber, wherein the ultrasonic generating means comprises: A vibrator including a plate-shaped piezoelectric ceramic having electrodes formed on both surfaces perpendicular to the polarization axis, a fixed part fixed to one end of one surface of the piezoelectric ceramic, and an integral part of the fixed part. And a vibrating plate including a vibrating portion that projects outwardly of the piezoelectric ceramic substantially parallel to one surface of the piezoelectric ceramic, wherein the ultrasonic generating means has a plate surface of the vibration plate. The tip of the vibrating part is immersed in the liquid, and an AC signal having a frequency equal to the resonance frequency of the vibrator is applied to the vibrator through the electrode. The vibrator is excited by being applied to the An ultrasonic atomizer in which the liquid in the vicinity of the distal end of the vibrating portion is atomized by vibrating the diaphragm with the fixed portion as a fixed end. 2. A characteristic frequency of the vibrating plate is equal to a resonance frequency of the vibrator, and a length dimension of the vibrating part along a projecting direction is a quarter wavelength of vibration generated in the vibrating part. The ultrasonic atomizer according to claim 1.