WO2020189272A1

WO2020189272A1 - Bubble generation device

Info

Publication number: WO2020189272A1
Application number: PCT/JP2020/009072
Authority: WO
Inventors: 藤本　克己; 良浩小木
Original assignee: 株式会社村田製作所
Priority date: 2019-03-20
Filing date: 2020-03-04
Publication date: 2020-09-24
Also published as: JPWO2020189272A1; JP7180749B2; CN113396011A; CN113396011B

Abstract

Disclosed is a bubble generation device (1) that generates fine bubbles in a liquid by vibration. The bubble generation device (1) comprises: a vibration plate (2) in which a plurality of pores (openings) are formed, one face of which contacts water (liquid) in a water tank (10), and the other face of which contacts air; and a piezoelectric element (4) that vibrates the vibration plate (2). The vibration direction in which the vibration plate (2) vibrates includes at least a direction that differs from the direction in which the air flows through the plurality of pores (openings).

Description

Bubble generator

This disclosure relates to a bubble generator.

In recent years, water purification, wastewater treatment, fish farming, etc. have been carried out using fine bubbles, and fine bubbles are used in various fields. Therefore, a bubble generator for generating fine bubbles has been developed (Patent Document 1).

In the bubble generator described in Patent Document 1, fine bubbles are generated by using a piezoelectric element. In this bubble generator, the vertical vibration in the central portion of the diaphragm that flexes and vibrates is used to tear off the bubbles generated in the pores formed in the diaphragm and make them finer. Therefore, in this bubble generator, the direction of air flowing through the pores formed in the diaphragm is parallel to the vibration direction of the diaphragm.

Japanese Patent No. 6108526

The air flowing through the pores becomes bubbles at the interface between the diaphragm and the liquid and rises in the liquid. When the direction of the air flowing through the pores and the vibration direction of the diaphragm are parallel, the bubbles generated on the surface of the diaphragm rise at once along with the flow of the direct jet pushed out from the pores, and the water surface of the water tank. Will be released into the atmosphere. Therefore, the bubble generator described in Patent Document 1 has a problem that the generated bubbles cannot be suspended in the liquid for a long time and the amount of fine bubbles remaining in the liquid is reduced.

Therefore, an object of the present disclosure is to provide a bubble generator capable of increasing the amount of fine bubbles remaining in the liquid.

The bubble generator according to one embodiment of the present disclosure is a bubble generator that generates fine bubbles in a liquid by vibration, in which a plurality of openings are formed, one surface is in contact with the liquid in the liquid tank, and the other. A diaphragm whose surface is in contact with a gas and a piezoelectric element that vibrates the diaphragm are provided, and the vibration direction for vibrating the diaphragm includes at least a direction different from the direction of the gas flowing through the plurality of openings.

According to the present disclosure, since the vibration direction for vibrating the diaphragm includes at least a direction different from the direction of the gas flowing through the plurality of openings, the amount of fine bubbles remaining in the liquid can be increased.

It is the schematic of the water quality purification apparatus which uses the bubble generator which concerns on this Embodiment 1. It is a schematic diagram of the vibrating body of the bubble generator which concerns on Embodiment 1. FIG. 5 is a partial cross-sectional view of a vibrating body of the bubble generator according to the first embodiment. It is a figure which shows the vibration state of the vibrating body of the bubble generator which concerns on this Embodiment 1. It is a top view of the diaphragm which concerns on this Embodiment 1. It is sectional drawing of the opening formed in the diaphragm which concerns on Embodiment 1. It is the schematic of the water quality purification apparatus which uses the bubble generator which concerns on this Embodiment 2. It is a perspective view of the vibrating body of the bubble generator which concerns on Embodiment 2. It is a figure which shows the vibration state of the vibrating body of the bubble generator which concerns on Embodiment 2. It is the schematic of the water quality purification apparatus which uses the bubble generator which concerns on this Embodiment 3. It is the schematic of the vibrating body of the bubble generator which concerns on embodiment 3. It is a figure which shows the vibration state of the vibrating body of the bubble generator which concerns on this Embodiment 3. It is the schematic of the water quality purification apparatus which uses the bubble generator which concerns on this Embodiment 4. It is an exploded perspective view of the vibrating body and the like of the bubble generator which concerns on Embodiment 4. It is a figure which shows the vibration state of the diaphragm of the bubble generator which concerns on this Embodiment 4.

(Embodiment 1)
Hereinafter, the bubble generator according to the first embodiment will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals and the description thereof will not be repeated.

First, FIG. 1 is a schematic view of a water purification device 100 in which the bubble generator 1 according to the first embodiment is used. The bubble generator 1 shown in FIG. 1 is provided, for example, at the bottom of a water tank (liquid tank) 10 and is used in a water purification device 100 that generates fine bubbles in the water of the water tank 10. The use of the bubble generator 1 is not limited to the water purification device 100, and can be applied to various uses such as a wastewater treatment device and a fish farming aquarium.

The bubble generator 1 includes a diaphragm 2, a vibrating body 3, a piezoelectric element 4, a holding portion 5, and a supporting portion 6. The bubble generator 1 is provided with a vibrating body 3 held by the holding portion 5 in a hole formed in a part of the bottom of the water tank 10. The boundary portion between the vibrating body 3 and the holding portion 5 is sealed, and the internal space of the holding portion 5 and the water in the water tank 10 are completely separated. Since the piezoelectric element 4 is provided on the side surface of the vibrating body 3 in the internal space of the holding portion 5, it is possible to prevent the electrical wiring and the like of the piezoelectric element 4 from being immersed in the liquid.

The vibrating body 3 is provided with an introduction hole 3d for passing air, and one end of the introduction hole 3d is provided on the internal space side of the holding portion 5. The holding portion 5 is provided on the supporting portion 6. The support portion 6 is provided with an introduction hole 6a, and air is sent from the introduction hole 6a into the internal space of the holding portion 5. The air sent from the introduction hole 6a into the internal space of the holding portion 5 passes through the introduction hole 3d of the vibrating body 3 and reaches the diaphragm 2 provided at the first end portion 3a and the second end portion 3b.

In the bubble generator 1, a plurality of air sent through the introduction hole 3d are formed in the diaphragm 2 by vibrating the diaphragm 2 and the diaphragm 3 with the piezoelectric element 4 provided on the side surface of the diaphragm 3. It is generated as fine bubbles from the pores (openings). In the bubble generator 1, a plurality of diaphragms 2 formed on the diaphragm 2 through the introduction holes 3d by applying back pressure (for example, about 0.08 atm to 0.12 atm (8 to 12 kPa)) in the direction shown in FIG. It supplies air to the pores.

The diaphragm 2 is made of a glass plate. When the diaphragm 2 is formed of a glass plate, for example, it may be formed of a glass plate that transmits ultraviolet light having a wavelength of 200 nm to 380 nm and deep ultraviolet light. By forming a glass plate that transmits ultraviolet light and deep ultraviolet light, a light source that emits ultraviolet light to the water in the water tank 10 from the other surface side of the vibrating plate 2 is provided, and sterilization by ozone generation and ultraviolet light irradiation are performed. It can also be used for sterilization. As the glass plate, quartz glass or pseudo-quartz synthetic glass whose composition is controlled and the transmittance of deep ultraviolet rays is improved is used. The diaphragm 2 may be formed of a metal plate, or may be formed of a material other than glass (for example, metal, resin, etc.).

The diaphragm 2 is formed with a plurality of pores, one surface of which is in contact with the water (liquid) of the water tank 10, and the other surface of which is in contact with the first end 3a or the second end 3b of the vibrating body 3. ing. In the bubble generator 1, air that has passed through the introduction hole 3d provided in the vibrating body 3 is sent from the first end portion 3a and the second end portion 3b to the water in the water tank 10 through the pores of the diaphragm 2. Generates fine bubbles.

In the bubble generator 1, the piezoelectric element 4 vibrates the diaphragm 2 and the vibrating body 3. FIG. 2 is a schematic view of the vibrating body 3 of the bubble generator 1 according to the first embodiment. 2 (a) is a perspective view of the vibrating body 3, FIG. 2 (b) is a side view of the vibrating body 3, and FIG. 2 (c) is a plan view of the vibrating body 3. FIG. 3 is a partial cross-sectional view of the vibrating body 3 of the bubble generator 1 according to the first embodiment.

The vibrating body 3 has a first end portion 3a and a second end portion 3b opposite to the first end portion 3a. The vibrating body 3 has a disk-shaped first end portion 3a, a second end portion 3b, and a pillar-shaped portion 3c connected to each other. The second end portion 3b is located on the side opposite to the first end portion 3a in the long side direction of the pillar-shaped portion 3c.

The first end portion 3a and the second end portion 3b are connected to the diaphragm 2, respectively. That is, the pores of the diaphragm 2 are connected to the introduction hole 3d on the first end 3a side and the introduction hole 3d on the second end 3b side. The second end portion 3b and the introduction hole 3d are also provided in the pillar-shaped portion 3c of the vibrating body 3.

The vibrating body 3 is made of an aluminum alloy in this embodiment. However, instead of the aluminum alloy, another metal material such as stainless steel may be used. Preferably, a highly rigid metal such as an aluminum alloy or stainless steel is desirable.

The vibrating body 3 has a shape in which the central portion is cut into a pillar shape, leaving the first end portion 3a and the second end portion 3b of the cylinder. Therefore, in the vibrating body 3, the first end portion 3a, the second end portion 3b, and the pillar-shaped portion 3c are integrally formed of the same material. In the vibrating body 3, the pillar-shaped portion 3c is joined to the first end portion 3a and the second end portion 3b as separate members, and the pillar-shaped portion 3c, the first end portion 3a, and the first end portion 3a are joined. The end portion 3b of 2 may be made of a separate member.

The piezoelectric element 4 is fixed to the pillar-shaped portion 3c of the vibrating body 3. The piezoelectric element 4 has a piezoelectric body and electrodes provided on both sides of the piezoelectric body. The piezoelectric body is polarized in the thickness direction, that is, in the direction parallel to the planes of the first end 3a and the second end 3b of the vibrating body 3. The piezoelectric body is made of a piezoelectric material such as piezoelectric ceramics.

By driving the piezoelectric element 4 in the bending vibration mode in a structure in which the piezoelectric element 4 is joined to the column-shaped portion 3c of the vibrating body 3, a vibrating body that flexes and vibrates the diaphragm 2 and the vibrating body 3 is configured. There is. The piezoelectric element 4 has, for example, a width of 8 mm, a length of 16 mm, and a thickness of 1 mm. Further, the piezoelectric element 4 is driven, for example, under operating conditions of a rectangular waveform having a voltage of 50 Vpp to 70 Vpp and a duty ratio of 50%.

In the bubble generator 1, the driving of the piezoelectric element 4 in the bending vibration mode vibrates the diaphragm 2 and the vibrating body 3 to generate fine bubbles. A controller signal (not shown) is supplied to the electrodes of the piezoelectric element 4, and the piezoelectric element 4 is driven based on the signal.

It has been explained that one piezoelectric element 4 is provided on one surface of the pillar-shaped portion 3c, but the present invention is not limited to this. For example, a plurality of piezoelectric elements 4 may be provided on one surface of the pillar-shaped portion 3c.

Next, the vibration of the diaphragm 2 and the vibrating body 3 in the bubble generator 1 will be described in detail. FIG. 4 is a diagram showing a vibration state of the vibrating body of the bubble generator according to the first embodiment. FIG. 4 shows the displacement as a result of simulating the vibration of the vibrating body 3 of the bubble generator 1.

In the vibrating body 3 shown in FIG. 4, the piezoelectric element 4 is provided in the pillar-shaped portion 3c. By applying an AC electric field between the electrodes of the piezoelectric element 4, the piezoelectric element 4 is driven in the bending vibration mode to cause the vibrating body 3 to bend and vibrate. Due to the displacement of the bending vibration, the diaphragms 2 provided at the first end 3a and the second end 3b of the vibrating body 3 are displaced in the left-right direction (vibration direction) in the drawing. On the other hand, the direction of the gas flowing through the plurality of pores formed in the diaphragm 2 is the vertical direction in the drawing, which is different from the vibration direction of the diaphragm 2 which vibrates by driving the piezoelectric element 4.

In the bubble generator 1, as shown in FIG. 4, the vibration direction for vibrating the diaphragm 2 includes a vibration component that is perpendicular to the direction of the gas flowing through the plurality of pores. Therefore, in the bubble generator 1, the bubbles generated on the surface of the diaphragm 2 are not easily affected by the flow of the direct jet extruded from the pores, and the bubbles rise at once and enter the atmosphere on the water surface of the water tank 10. It can be prevented from being dissipated. Further, in the bubble generator 1, the generated bubbles can be suspended in the water of the water tank 10 for a long time, and the amount of fine bubbles remaining in the water can be increased.

In particular, if the vibration direction for vibrating the diaphragm 2 is perpendicular to the direction of the gas flowing through the plurality of pores, the bubbles are less affected by the flow of the direct jet extruded from the pores. be able to. As shown in FIG. 4, the bubble generator 1 is not limited to the case where the vibration direction for vibrating the diaphragm 2 is the direction perpendicular to the direction of the gas flowing through the plurality of pores, and the vibration of the diaphragm 2 As long as it contains at least a vibration component that is perpendicular to the direction of the gas flowing through the plurality of pores, it is sufficient that the bubbles are not easily affected by the flow of the direct jet flow pushed out from the pores. ..

A plurality of pores are formed in the diaphragm 2. FIG. 5 is a plan view of the diaphragm according to the present embodiment. In the diaphragm 2 shown in FIG. 5, a plurality of pores 2b are formed in a region of 5 mm × 5 mm provided in the central portion of a glass plate 2a having a diameter of 14 mm. For example, when the pore diameter of the pores 2b is 10 μm and the distance between the pores 2b is 0.25 mm, the diaphragm 2 can form 441 pores 2b in a region of 5 mm × 5 mm. In addition, in FIG. 5, in order to make it easy to imagine that a plurality of pores 2b are formed in the glass plate 2a, the pore diameter of the pores 2b and the spacing between the pores 2b are different from the actual scale.

The pores 2b provided in the diaphragm 2 have a pore diameter of 1 μm to 20 μm on the surface in contact with the liquid. The air introduced from the pores 2b generates fine bubbles having a diameter about 10 times that of the water in the water tank 10. Since a plurality of pores 2b are formed at intervals of 10 times or more the pore diameter, it is possible to prevent fine bubbles generated from one pore 2b from connecting with fine bubbles generated from adjacent pores 2b. The performance to generate independent fine bubbles is improved.

As a method for forming a plurality of pores 2b in the glass plate 2a, for example, there is a method in which a laser and liquid phase etting are combined. Specifically, in this method, by irradiating the glass plate 2a with a laser, the glass plate 2a is subjected to composition modification by laser energy, and the portion is eroded by a liquid fluoride-based etiquette or the like to cause a plurality of pieces. It forms pores 2b.

FIG. 6 is a cross-sectional view of the pores (openings) 2b formed in the diaphragm according to the present embodiment. As shown in FIG. 6, the shape of the pores 2b formed in the glass plate 2a is a tapered shape in which the pore diameter of the upper surface is larger than the pore diameter of the lower surface in the drawing. By arranging the diaphragm 2 with the surface having a small pore diameter in contact with water in the water tank 10 and the surface having a large pore diameter in contact with gas, the diameter of fine bubbles generated in the pores 2b can be made smaller. Can be done. Of course, the diaphragm 2 may be arranged with the surface having a large pore diameter in contact with water in the water tank 10 and the surface having a small pore diameter in contact with gas.

When the glass plate 2a is used for the diaphragm 2, there is an advantage that liquid contamination due to elution of metal ions into the liquid can be prevented as compared with the case where the metal plate is used. Further, when pores are formed in the metal plate, it is necessary to perform plating to prevent corrosion of the metal. Precious metals must be used to prevent the elution of metal ions into the liquid. Therefore, if the metal plate having pores formed is plated with a noble metal, the cost of the diaphragm becomes high.

As described above, the bubble generator 1 according to the first embodiment is a bubble generator 1 that generates fine bubbles in a liquid by vibration. In the bubble generator 1, a plurality of pores 2b (openings) are formed, one surface is in contact with the water (liquid) of the water tank 10, and the other surface is in contact with the gas, vibrating the diaphragm 2 and the diaphragm 2. It is provided with a piezoelectric element 4 for causing vibration. The vibration direction for vibrating the diaphragm 2 includes at least a direction different from the direction of the gas flowing through the plurality of pores 2b.

As a result, the bubble generator 1 includes at least a direction different from the direction of the gas flowing through the plurality of pores 2b in the vibration direction for vibrating the diaphragm, so that the flow of the direct jet extruded from the pores 2b The bubbles are not easily affected, and the amount of fine bubbles remaining in the liquid can be increased.

The vibration direction of the diaphragm 2 that drives the piezoelectric element 4 in the bending vibration mode and vibrates by driving the piezoelectric element 4 includes at least a direction different from the direction of the gas flowing through the plurality of pores 2b. As a result, the bubble generator 1 can drive the piezoelectric element 4 in the bending vibration mode to increase the amount of fine bubbles remaining in the liquid.

The vibration direction for vibrating the diaphragm 2 may include at least a vibration component in the direction perpendicular to the direction of the gas flowing through the plurality of pores 2b. As a result, the bubbles can be made less affected by the flow of the direct jet extruded from the pores, and the amount of fine bubbles remaining in the liquid can be further increased.

Further, the diaphragm 2 may be formed of a glass plate. As a result, the bubble generator 1 can prevent liquid contamination due to elution of metal ions into the water (liquid) of the water tank 10.

Further, the diaphragm 2 may form a plurality of pores 2b having a pore diameter of 1 μm to 20 μm on the surface in contact with the liquid at intervals of 10 times or more the pore diameter. As a result, the bubble generator 1 can prevent the fine bubbles 200 generated from one pore 2b from being connected to the fine bubbles 200 generated from the adjacent pores 2b, and generate independent fine bubbles 200. be able to.

Further, the shape of the pores 2b may be a tapered shape in which the pore diameter of the other surface in contact with the gas is larger than the pore diameter of one surface in contact with the water (liquid) of the water tank 10. As a result, the bubble generator 1 can make the diameter of the fine bubbles 200 generated in the pores 2b smaller.

(Embodiment 2)
In the first embodiment, the vibrating body 3 is provided by the holding portion 5 provided in the water of the water tank 10 so that the vibrating direction for vibrating the diaphragm 2 includes at least a direction different from the direction of the gas flowing through the plurality of pores 2b. The configuration for holding the above was described. In the second embodiment, a configuration will be described in which the vibration direction for vibrating the diaphragm includes at least a direction different from the direction of the gas flowing through the plurality of pores without providing the holding portion.

FIG. 7 is a schematic view of the water purification device 110 in which the bubble generator 1a according to the second embodiment is used. The water purification device 110 according to the second embodiment has the same configuration as the water purification device 100 according to the first embodiment shown in FIG. 1, and the same reference numerals are given to the configurations, and detailed description thereof will not be repeated.

The bubble generator 1a shown in FIG. 7 is provided, for example, at the bottom of the water tank (liquid tank) 10 and is used in the water purification device 110 that generates fine bubbles in the water of the water tank 10. The use of the bubble generator 1a is not limited to the water purification device 110, and can be applied to various uses such as a wastewater treatment device and a fish farming aquarium.

The bubble generator 1a includes a diaphragm 2, a vibrating body 30, and a piezoelectric element 4. The vibrating body 30 has an H-shaped (tuning fork) shape, is held in a hole made in a part of the bottom of the water tank 10, and a part of the vibrating body 30 is arranged on the water side (liquid side) of the water tank 10. Has been done. The boundary portion between the vibrating body 30 and the bottom of the water tank 10 is sealed, and the portion of the vibrating body 30 on the outside (gas side) of the water tank 10 and the water in the water tank 10 are completely separated. Since the piezoelectric element 4 is provided in the portion of the vibrating body 30 outside the water tank 10, it is possible to prevent the electrical wiring and the like of the piezoelectric element 4 from being immersed in the liquid.

The vibrating body 30 is provided with an introduction hole 30d for passing air, one end of the introduction hole 30d is provided on the water side of the water tank 10, and the other end of the introduction hole 30d is provided on the outside of the water tank 10. .. The air sent from the other end of the introduction hole 30d passes through the introduction hole 30d and reaches the diaphragm 2 provided at one end of the vibrating body 30 (the water side of the water tank 10).

In the bubble generator 1a, the diaphragm 2 and the diaphragm 30 are vibrated by the piezoelectric element 4 provided on the side surface of the diaphragm 30 outside the water tank 10, so that the air sent through the introduction hole 30d is sent to the diaphragm. It is generated as fine bubbles from a plurality of pores (openings) formed in 2. In the bubble generator 1a, a plurality of diaphragms 2 formed on the diaphragm 2 through the introduction holes 30d by applying back pressure (for example, about 0.08 atm to 0.12 atm (8 to 12 kPa)) in the direction shown in FIG. Air is supplied to the pores.

In the bubble generator 1a, the piezoelectric element 4 vibrates the diaphragm 2 and the vibrating body 30. FIG. 8 is a perspective view of the vibrating body 30 of the bubble generator 1a according to the second embodiment.

The vibrating body 30 has a pillar-shaped portion 30a and a pillar-shaped portion 30b arranged in parallel with the pillar-shaped portion 30a. The vibrating body 30 has an H-shape in which the central portion of the pillar-shaped portion 30a and the pillar-shaped portion 30b is connected by the connecting portion 30c. A diaphragm 2 is provided at one end (water side of the water tank 10) of the pillar-shaped portion 30a and the pillar-shaped portion 30b, respectively. Since the shape of one end of the pillar-shaped portion 30a and the pillar-shaped portion 30b is rectangular, the outer shape of the diaphragm 2 is also rectangular, but as shown in FIG. 5, a plurality of pores 2b are formed in the glass plate 2a. Is formed.

In the present embodiment, the vibrating body 30 is made of an aluminum alloy. However, instead of the aluminum alloy, another metal material such as stainless steel may be used. Preferably, a highly rigid metal such as an aluminum alloy or stainless steel is desirable.

The vibrating body 30 has an H-shaped (tuning fork) shape in which the central portion of the pillar-shaped portion 30a and the pillar-shaped portion 30b is connected by the connecting portion 30c. Therefore, in the vibrating body 30, the pillar-shaped portion 30a, the pillar-shaped portion 30b, and the connecting portion 30c are integrally made of the same material. In the vibrating body 30, the pillar-shaped portion 30a and the pillar-shaped portion 30b as separate members are joined to the connecting portion 30c, and the connecting portion 30c and the pillar-shaped portion 30a and the pillar-shaped portion 30b are separated. It may be composed of members.

Next, the vibration of the diaphragm 2 and the vibrating body 30 in the bubble generator 1a will be described in detail. FIG. 9 is a diagram showing a vibration state of the vibrating body 30 of the bubble generator 1a according to the second embodiment. FIG. 9 shows the displacement as a result of simulating the vibration of the vibrating body 30 of the bubble generator 1a.

In the vibrating body 30 shown in FIG. 9, the piezoelectric element 4 is provided in the pillar-shaped portion 30a and the pillar-shaped portion 30b. By applying an AC electric field between the electrodes of the piezoelectric element 4, the piezoelectric element 4 is driven in the bending vibration mode to cause the vibrating body 30 to bend and vibrate. Due to the displacement of the bending vibration, the diaphragms 2 provided at the first end 3a and the second end 3b of the vibrating body 30 are displaced in the arrow direction (vibration direction) in the drawing. On the other hand, the direction of the gas flowing through the plurality of pores 2b formed in the diaphragm 2 is the vertical direction in the drawing, which is different from the vibration direction of the diaphragm 2 that vibrates by driving the piezoelectric element 4.

In the bubble generator 1a, as shown in FIG. 9, the vibration direction for vibrating the diaphragm 2 is perpendicular to the direction of the gas flowing through the plurality of pores 2b. Therefore, in the bubble generator 1a, the bubbles generated on the surface of the diaphragm 2 are not easily affected by the flow of the direct jet extruded from the pores 2b, and the bubbles rise at once on the water surface of the water tank 10. It can be prevented from being released into the atmosphere. Further, in the bubble generator 1a, the generated bubbles can be suspended in the water of the water tank 10 for a long time, and the amount of fine bubbles remaining in the water can be increased.

In particular, if the vibration direction for vibrating the diaphragm 2 is perpendicular to the direction of the gas flowing through the plurality of pores 2b, the bubbles are more affected by the flow of the direct jet extruded from the pores 2b. It can be difficult. The bubble generator 1a is not limited to the case where the vibration direction for vibrating the diaphragm 2 is perpendicular to the direction of the gas flowing through the plurality of pores 2b as shown in FIG. If the vibration direction and the direction of the gas flowing through the plurality of pores 2b are different and include at least a vibration component that is in the vertical direction, the bubbles are affected by the flow of the direct jet flow pushed out from the pores 2b. I hope it can be difficult.

As described above, in the bubble generator 1a according to the second embodiment, the piezoelectric element 4 is driven in the bending vibration mode, and a plurality of pores are formed in the vibration direction of the diaphragm 2 which is vibrated by the drive of the piezoelectric element 4. It includes at least a direction different from the direction of the gas flowing through 2b. As a result, in the bubble generator 1a, the direction of the gas flowing through the plurality of pores 2b and the vibration direction for vibrating the diaphragm 2 are different, and the bubbles affect the flow of the direct jet extruded from the pores 2b. It can be made difficult to receive.

(Embodiment 3)
In the first embodiment, the configuration in which the piezoelectric element 4 is driven in the bending vibration mode to cause the vibrating body 3 to bend and vibrate has been described. In the third embodiment, a configuration in which the piezoelectric element is driven in a mode other than the bending vibration mode to vibrate the vibrating body will be described.

FIG. 10 is a schematic view of a water purification device 120 in which the bubble generator 1b according to the third embodiment is used. The water purification device 120 according to the third embodiment has the same configuration as the water purification device 100 according to the first embodiment shown in FIG. 1, and the same reference numerals are given to the configurations, and detailed description thereof will not be repeated.

The bubble generator 1b includes a diaphragm 21, a vibrating body 31, a piezoelectric element 41, a holding portion 51, and a supporting portion 6. The bubble generator 1b is provided with a diaphragm 21 held by the holding portion 51 in a hole formed in a part of the bottom of the water tank 10. The boundary portion between the diaphragm 21 and the holding portion 51 is sealed, and the internal space of the holding portion 51 and the water in the water tank 10 are completely separated. Since the piezoelectric element 41 is provided on the lower surface of the diaphragm 21 in the internal space of the holding portion 51, it is possible to prevent the electrical wiring and the like of the piezoelectric element 41 from being immersed in the liquid.

A vibrating body 31 is provided on the lower surface of the diaphragm 21 with the piezoelectric element 41 interposed therebetween. The vibrating body 31 is provided with an introduction hole 31d for passing air, and one end of the introduction hole 31d is provided on the outside (gas side) of the water tank 10. The holding portion 51 is provided on the supporting portion 6. The support portion 6 is provided with an introduction hole 6a, and air is sent from the introduction hole 6a to the introduction hole 31d. The air sent from the introduction hole 6a reaches the diaphragm 21 through the introduction hole 31d of the vibrating body 31.

In the bubble generator 1b, the diaphragm 21 and the diaphragm 31 are vibrated by the piezoelectric element 41 provided at the outer peripheral end of the diaphragm 31, so that the air sent through the introduction hole 31d is formed in the diaphragm 21. It is generated as fine bubbles from the pores (openings) of. In the bubble generator 1b, a plurality of diaphragms 21 formed on the diaphragm 21 through the introduction holes 31d by applying back pressure (for example, about 0.08 atm to 0.12 atm (8 to 12 kPa)) in the direction shown in FIG. Air is supplied to the pores.

The diaphragm 21 has a plurality of pores formed in the vicinity of the position where the piezoelectric element 41 is arranged, and one surface is in contact with the water (liquid) of the water tank 10 and the other surface is in contact with the piezoelectric element 41. In the bubble generator 1b, fine bubbles are generated by sending air that has passed through the introduction hole 31d provided in the vibrating body 31 into the water in the water tank 10 through the pores of the diaphragm 21.

In the bubble generator 1b, the piezoelectric element 41 vibrates the diaphragm 21 and the vibrating body 31. FIG. 11 is a schematic view of the vibrating body 31 of the bubble generator 1b according to the third embodiment. 11 (a) is a partial cross-sectional view of the vibrating body 31, and FIG. 11 (b) is a side view of the vibrating body 31.

The vibrating body 31 is a donut-shaped plate provided in the introduction hole 31d at the center, and is connected to a ring-shaped piezoelectric element 41 at the outer peripheral end. Further, the piezoelectric element 41 is connected to the diaphragm 21 on the opposite surface connected to the vibrating body 31.

In the present embodiment, the vibrating body 31 is made of an aluminum alloy. However, instead of the aluminum alloy, another metal material such as stainless steel may be used. Preferably, a highly rigid metal such as an aluminum alloy or stainless steel is desirable.

The piezoelectric element 41 has a piezoelectric body and electrodes provided on both sides of the piezoelectric body. The piezoelectric body is polarized in the thickness direction, that is, in the direction in which the vibrating body 31 and the diaphragm 21 are overlapped with each other. The piezoelectric body is made of a piezoelectric material such as piezoelectric ceramics.

The piezoelectric element 41 is connected to the outer peripheral end of the vibrating body 31, and the piezoelectric element 41 is expanded and driven in the vibration mode to form a vibrating body that expands and vibrates the diaphragm 21 and the vibrating body 31. The piezoelectric element 41 can be driven in a spreading vibration mode that spreads in the plane direction of a thin square plate or disk by utilizing the mechanical resonance of the piezoelectric ceramics and its resonance frequency (for example, 100 kHz to several MHz).

In the bubble generator 1b, the driving of the piezoelectric element 41 in the spreading vibration mode vibrates the diaphragm 21 and the vibrating body 31 to generate fine bubbles. A controller signal (not shown) is supplied to the electrodes of the piezoelectric element 41, and the piezoelectric element 41 is driven based on the signal.

Although it has been explained that the piezoelectric element 41 is provided with one ring-shaped piezoelectric element on one surface of the vibrating body 31, the present invention is not limited to this. The piezoelectric element 41 may have, for example, a configuration in which a plurality of piezoelectric elements are arranged in a ring shape on one surface of the vibrating body 31.

Next, the vibration of the diaphragm 21 and the vibrating body 31 of the bubble generator 1b will be described in detail. FIG. 12 is a diagram showing a vibration state of the vibrating body 31 of the bubble generator 1b according to the third embodiment. FIG. 12 shows the displacement direction as a result of simulating the vibration of the vibrating body 31 of the bubble generator 1b.

In the vibrating body 31 shown in FIG. 12, a piezoelectric element 41 is provided at the outer peripheral end of the vibrating body 31. In the diaphragm 21, unlike the diaphragm 2 shown in FIG. 5, a plurality of pores 21b are formed not in the central portion but in the vicinity of the position where the piezoelectric element 41 is arranged. By arranging a plurality of pores 21b between the outer peripheral end portion and the central portion (the range from the peripheral portion to the central portion of the diaphragm 21) instead of the central portion of the diaphragm 21, the spread vibration by the piezoelectric element 41 can be generated. It can be placed in a large position. The plurality of pores 21b formed in the diaphragm 21 also have pores 2b as shown in FIG.

By applying an AC electric field between the electrodes of the piezoelectric element 41, the piezoelectric element 41 is expanded and driven in the vibration mode to expand and vibrate the diaphragm 21. Due to the displacement of the spreading vibration, the diaphragm 21 is displaced in the direction of the arrow (vibration direction) in the figure from the center to the outer circumference. On the other hand, the direction of the gas flowing through the plurality of pores 21b formed in the diaphragm 21 is the vertical direction (direction perpendicular to the surface of the diaphragm 21) in the figure, and the diaphragm 21 vibrates by driving the piezoelectric element 41. It is different from the vibration direction.

In the bubble generator 1b, as shown in FIG. 12, the vibration direction for vibrating the diaphragm 21 is perpendicular to the direction of the gas flowing through the plurality of pores 21b. Therefore, in the bubble generator 1b, the bubbles generated on the surface of the diaphragm 21 are not easily affected by the flow of the direct jet extruded from the pores 21b, and the bubbles rise at once on the water surface of the water tank 10. It can be prevented from being released into the atmosphere. Further, in the bubble generator 1b, the generated bubbles can be suspended in the water of the water tank 10 for a long time, and the amount of fine bubbles remaining in the water can be increased.

In particular, if the vibration direction for vibrating the diaphragm 21 is perpendicular to the direction of the gas flowing through the plurality of pores 21b, the bubbles are more affected by the flow of the direct jet extruded from the pores 21b. It can be difficult. The bubble generator 1b is not limited to the case where the vibration direction for vibrating the diaphragm 21 is perpendicular to the direction of the gas flowing through the plurality of pores 21b as shown in FIG. If the vibration direction and the direction of the gas flowing through the plurality of pores 21b are different from each other and include at least a vibration component that is in the vertical direction, the bubbles are less likely to be affected by the flow of the direct jet flow pushed out from the pores. I hope I can. When the piezoelectric element 41 is driven in the expanded vibration mode and the vibration plate 21 is subjected to bending vibration in the higher-order mode, the vibration component in the vibration direction that vibrates the vibration plate 21 includes the expansion vibration component in the vertical direction. , May contain bending vibration components in the parallel direction. However, if the bending vibration component in the parallel direction is small with respect to the spreading vibration component in the vertical direction, the influence of the bubbles on the flow of the direct jet is small.

As described above, in the bubble generator 1b according to the third embodiment, the piezoelectric element 41 is expanded and driven in the vibration mode, and a plurality of pores 21b are provided in the range from the peripheral portion to the central portion of the diaphragm 21. The peripheral portion of the diaphragm 21 is vibrated by driving the piezoelectric element 41. As a result, the bubble generator 1b drives the piezoelectric element 41 in the expanding vibration mode, causes the direction of the gas flowing through the plurality of pores 21b to be different from the vibration direction for vibrating the diaphragm 21, and is extruded from the pores 21b. It is possible to make the bubbles less susceptible to the flow of the direct jet.

(Embodiment 4)
In the first embodiment, the configuration in which the piezoelectric element 4 is driven in the bending vibration mode to cause the vibrating body 3 to bend and vibrate has been described. In the fourth embodiment, a configuration in which the vibrating body is vibrated other than bending vibration will be described.

FIG. 13 is a schematic view of the water purification device 130 in which the bubble generator 1c according to the fourth embodiment is used. The water purification device 130 according to the fourth embodiment has the same configuration as the water purification device 100 according to the first embodiment shown in FIG. 1, and the same reference numerals are given to the configurations, and detailed description thereof will not be repeated.

The bubble generator 1c includes a diaphragm 22, a vibrating body 32, a piezoelectric element 42, holding

portions

52a and 52b, and a supporting portion 62. The bubble generator 1c is provided with a vibrating body 32 held by the holding portion 52a in a hole formed in a part of the bottom of the water tank 10. The boundary portion between the vibrating body 32 and the holding portion 52a is sealed, and the space below the holding portion 52a and the water in the water tank 10 are completely separated. Since the piezoelectric element 42 is provided in the space below the holding portion 52a, it is possible to prevent the electrical wiring and the like of the piezoelectric element 42 from being immersed in the liquid.

A diaphragm 22 is provided on the upper surface of the holding portion 52a with the vibrating body 32 interposed therebetween. The vibrating body 32 is a tubular body that allows air to pass through. The holding portion 52b is provided on the supporting portion 62 and is connected to the holding portion 52a with the piezoelectric element 42 interposed therebetween. The holding portion 52a and the holding portion 52b have an opening in the central portion. Air can be passed through the support portion 62 through a tubular body, and air is sent to the diaphragm 22 by connecting with the vibrating body 32 via the holding portion 52a and the holding portion 52b.

In the bubble generator 1c, the diaphragm 22 and the vibrating body 32 are vibrated by the piezoelectric element 42 provided at the outer peripheral end of the vibrating body 32, so that the air sent through the support portion 62 and the vibrating body 32 is sent to the diaphragm 22. It is generated as fine bubbles from a plurality of pores (openings) formed in. In the bubble generator 1c, by applying back pressure (for example, about 0.08 atm to 0.12 atm (8 to 12 kPa)) in the direction shown in FIG. 13, the vibrating plate 22 is subjected to the support portion 62 and the vibrating body 32. Air is supplied to a plurality of formed pores.

In the diaphragm 22, a plurality of pores are formed not between the central portion of the diaphragm 22 but between the outer peripheral end portion and the central portion, one surface is in contact with the water (liquid) of the water tank 10, and the other surface vibrates. It is in contact with the body 32.

FIG. 14 is an exploded perspective view of a vibrating body or the like of the bubble generator 1c according to the fourth embodiment. The vibrating body 32 is a tubular body and has a shape in which brims are provided at both ends. The vibrating body 32 is connected to the piezoelectric element 42 via the holding portion 52a. In the piezoelectric element 42, a plurality of piezoelectric elements are arranged along the opening of the holding portion 52a. The piezoelectric element 42 is connected to the support portion 62 via the holding portion 52b.

The vibrating body 32 is made of an aluminum alloy in this embodiment. However, instead of the aluminum alloy, another metal material such as stainless steel may be used. Preferably, a highly rigid metal such as an aluminum alloy or stainless steel is desirable.

The piezoelectric element 42 has a piezoelectric body and electrodes provided on both sides of the piezoelectric body. The piezoelectric body does not use polarization in the thickness direction, and is polarized parallel to the length direction of the piezoelectric body as shown by the arrow direction shown in FIG. The piezoelectric body is made of a piezoelectric material such as piezoelectric ceramics.

In the piezoelectric element 42, a plurality of piezoelectric elements are arranged at positions corresponding to the peripheral portions of the diaphragm 22, and each piezoelectric element is vibrated in the length direction so as to vibrate in the plane of the diaphragm 22. ..

In the bubble generator 1c, the diaphragm 22 is vibrated in a plane by being driven by the piezoelectric element 42 to generate fine bubbles. A controller signal (not shown) is supplied to the electrodes of the piezoelectric element 42, and the piezoelectric element 42 is driven based on the signal.

Next, the vibration of the diaphragm 22 of the bubble generator 1c will be described in detail. FIG. 15 is a diagram showing a vibration state of the diaphragm 22 of the bubble generator 1c according to the fourth embodiment. FIG. 15 shows the displacement direction as a result of simulating the vibration of the diaphragm 22 of the bubble generator 1c.

In the vibrating body 32 shown in FIG. 15, the piezoelectric element 42 is provided at a position corresponding to the outer peripheral end portion of the vibrating body 32. In the diaphragm 22, unlike the diaphragm 2 shown in FIG. 5, a plurality of pores 22b are formed not in the central portion but in the vicinity of the position where the piezoelectric element 42 is arranged. By arranging a plurality of pores 22b between the outer peripheral end portion and the central portion (the range from the peripheral portion to the central portion of the diaphragm 22) instead of the central portion of the diaphragm 22, the torsional vibration caused by the piezoelectric element 42 is generated. It can be placed in a large position. The plurality of pores 22b formed in the diaphragm 22 also have pores 2b as shown in FIG.

By applying an AC electric field between the electrodes of the piezoelectric element 42, the diaphragm 22 is twisted and vibrated by driving the piezoelectric element 42. Due to the displacement of the torsional vibration, the displacement in the arrow direction (vibration direction) in the figure is larger in the outer peripheral portion than in the central portion of the diaphragm 22. On the other hand, the direction of the gas flowing through the plurality of pores 22b formed in the diaphragm 22 is the vertical direction in the figure (direction perpendicular to the surface of the diaphragm 22), and the diaphragm 22 vibrates by driving the piezoelectric element 42. It is different from the vibration direction.

In the bubble generator 1c, as shown in FIG. 15, the vibration direction for vibrating the diaphragm 22 is perpendicular to the direction of the gas flowing through the plurality of pores 22b. Therefore, in the bubble generator 1c, the bubbles generated on the surface of the diaphragm 22 are not easily affected by the flow of the direct jet extruded from the pores 22b, and the bubbles rise at once on the water surface of the water tank 10. It can be prevented from being released into the atmosphere. Further, in the bubble generator 1c, the generated bubbles can be suspended in the water of the water tank 10 for a long time, and the amount of fine bubbles remaining in the water can be increased.

In particular, if the vibration direction for vibrating the diaphragm 22 is perpendicular to the direction of the gas flowing through the plurality of pores 22b, the bubbles are more affected by the flow of the direct jet extruded from the pores 22b. It can be difficult. The bubble generator 1c is not limited to the case where the vibration direction for vibrating the diaphragm 22 is perpendicular to the direction of the gas flowing through the plurality of pores 22b as shown in FIG. If the vibration direction and the direction of the gas flowing through the plurality of pores 22b are different and include at least a vibration component that is in the vertical direction, the bubbles are less likely to be affected by the flow of the direct jet flow pushed out from the pores. I hope I can.

As described above, in the bubble generator 1c according to the fourth embodiment, a plurality of piezoelectric elements 42 are arranged at positions corresponding to the peripheral portions of the diaphragm 22, and the range from the peripheral portion to the central portion of the diaphragm 22 is provided. Is provided with a plurality of pores 22b. The bubble generator 1c vibrates the diaphragm 22 by driving the plurality of piezoelectric elements 42 so as to twist in the plane of the diaphragm 22 forming the plurality of pores 22b. As a result, the bubble generator 1c vibrates the diaphragm 22 by torsional vibration to make the direction of the gas flowing through the plurality of pores 22b different from the vibration direction that vibrates the diaphragm 22 and pushes the diaphragm 22 out of the pores 22b. Bubbles can be made less susceptible to the flow of the direct jet.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

1,1a to 1c bubble generator, 2,21,22 diaphragm, 2a glass plate, 2b, 21b, 22b pores, 3,30,31,32 vibrating body, 4,41,42 piezoelectric element, 10 water tank, 100, 110, 120, 130 Water purification device.

Claims

A bubble generator that generates fine bubbles in a liquid by vibration.
A diaphragm in which multiple openings are formed, one surface in contact with the liquid in the liquid tank and the other surface in contact with the gas.
A piezoelectric element that vibrates the diaphragm is provided.
A bubble generator that includes at least a direction different from the direction of the gas flowing through the plurality of openings in the vibration direction for vibrating the diaphragm.
The piezoelectric element is driven in the bending vibration mode,
The bubble generator according to claim 1, wherein the vibration direction of the diaphragm that vibrates by driving the piezoelectric element includes at least a direction different from the direction of the gas flowing through the plurality of openings.
The piezoelectric element is expanded and driven in the vibration mode,
The bubble generator according to claim 1, wherein the plurality of openings are provided in a range from the peripheral portion to the central portion of the diaphragm, and the peripheral portion of the diaphragm is vibrated by driving the piezoelectric element.
A plurality of the piezoelectric elements are arranged at positions corresponding to the peripheral portions of the diaphragm.
The plurality of openings are provided in a range from the peripheral portion to the central portion of the diaphragm, and the diaphragm is twisted in the plane of the diaphragm forming the plurality of openings. The bubble generator according to claim 1, which vibrates by driving.
The bubble generation according to any one of claims 1 to 4, wherein the vibration direction for vibrating the diaphragm includes at least a vibration component in a direction perpendicular to the direction of the gas flowing through the plurality of openings. apparatus.
The bubble generator according to any one of claims 1 to 5, wherein the diaphragm is made of a glass plate.
The bubble generator according to any one of claims 1 to 6, wherein the diaphragm has a plurality of openings having a hole diameter of 1 μm to 20 μm formed at intervals of 10 times or more the hole diameter.
Any one of claims 1 to 7, wherein the shape of the opening is a tapered shape in which the pore diameter of the other surface in contact with the gas is larger than the pore diameter of the one surface in contact with the liquid in the liquid tank. The bubble generator according to the section.