Bubble generating device and bubble generating system

Abstract

The present invention relates to a bubble generating device and a bubble generating system. The present invention provides a bubble generating device (1) provided with a vibration plate (2), a first cylindrical body (31), a spring portion (32), a second cylindrical body (33), and a piezoelectric element (4). The vibration plate (2) is formed with a plurality of opening portions, and is disposed so that one surface is in contact with a liquid in a liquid tank (10), and the other surface is in contact with a gas at a position. The first cylindrical body (31) supports the vibration plate (2) with one end portion. The spring portion (32) is plate-shaped, and supports the other end portion of the first cylindrical body (31). The second cylindrical body (33) supports the spring portion (32) with one end portion at a position located outward of the position at which the first cylindrical body (31) is supported. The piezoelectric element (4) vibrates the spring portion (32). The piezoelectric element (4) is disposed in the surface of the spring portion (32) on the side supported by the second cylindrical body (33) inward of the position supported by the second cylindrical body (33).

Description

Technical Field

[0001] This disclosure relates to bubble generating apparatus and bubble generating system. Background Technology

[0002] In recent years, microbubbles have been used in various fields such as water purification, wastewater treatment, and fish farming. Therefore, a bubble generating device for producing microbubbles has been developed (Japanese Patent Application Publication No. 2016-209825: Patent Document 1).

[0003] In the bubble generating apparatus described in Patent Document 1, a piezoelectric element is used to generate fine bubbles. In this bubble generating apparatus, the central part of a vibrating plate is vibrated up and down by bending vibration, and the bubbles generated at the fine holes formed in the vibrating plate are torn apart by the vibration to achieve miniaturization.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2016-209825

[0005] In the bubble generating device described in Patent Document 1, depending on the type of liquid placed in the liquid tank, due to the high specific gravity, high surface tension, and high viscosity of the liquid, it is sometimes impossible to tear the bubbles generated at the fine holes by the vibration of the vibrating plate and generate fine bubbles.

[0006] To generate fine bubbles using a bubble generating device, piezoelectric elements are needed to make the vibrating plate vibrate more strongly. However, when using piezoelectric elements to make the vibrating plate vibrate more strongly, there is a problem that the vibration of the vibrating plate leaks into the liquid tank, causing the liquid tank itself to vibrate. Summary of the Invention

[0007] Therefore, the purpose of this disclosure is to provide a bubble generating apparatus and a bubble generating system, wherein the bubble generating apparatus effectively generates fine bubbles regardless of the type of liquid placed in the liquid tank.

[0008] One aspect of this disclosure relates to a bubble generating device that is installed in a liquid tank to generate fine bubbles in the liquid. The device comprises: a vibrating plate having multiple openings and positioned such that one side contacts the liquid in the liquid tank and the other side contacts the gas; a first cylindrical body supporting the vibrating plate at one end; a plate-shaped spring supporting the other end of the first cylindrical body; a second cylindrical body supporting the spring at one end at a position further outward than the position supporting the first cylindrical body; and a piezoelectric element that vibrates the spring, the piezoelectric element being disposed on the side of the spring supported by the second cylindrical body further inward than the position supported by the second cylindrical body.

[0009] Another aspect of this disclosure relates to a bubble generating system comprising the aforementioned bubble generating device and liquid tank.

[0010] According to this disclosure, by placing the piezoelectric element on the inner side of the spring portion supported by the second cylindrical body, rather than at the position supported by the second cylindrical body, it is possible to effectively generate fine bubbles, regardless of the type of liquid placed in the liquid tank. Furthermore, by making the outer diameter of the first cylindrical body smaller than the outer diameter of the vibrating plate, the size of the piezoelectric element can be reduced, thereby lowering costs. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of a bubble generating system using the bubble generating apparatus according to this embodiment.

[0012] Figure 2 This is a perspective view of the bubble generating apparatus according to this embodiment.

[0013] Figure 3 This is a cross-sectional view of the bubble generating apparatus according to this embodiment.

[0014] Figure 4 This is a diagram used to illustrate the vibration of the vibrating plate of the bubble generating apparatus according to this embodiment.

[0015] Figure 5 This is a graph showing the relationship between the frequency and impedance of the drive signal applied to the piezoelectric element of the bubble generating device according to this embodiment.

[0016] Figure 6 This is a graph showing the change in resonant frequency when the vibrating plate of the bubble generating apparatus according to this embodiment is driven in a gas and when the vibrating plate is driven in a liquid.

[0017] Figure 7 This is a graph showing the displacement of the vibrating plate when the vibrating plate of the bubble generating apparatus according to this embodiment is driven in a gas and when the vibrating plate is driven in a liquid.

[0018] Figure 8 This is a perspective view of the bubble generating device involved in Modified Example 1.

[0019] Figure 9 This is a cross-sectional view of the bubble generating apparatus involved in Variation Example 2.

[0020] Figure 10 It is a three-dimensional diagram of another structure.

[0021] Figure 11 This is a three-dimensional diagram of yet another structure. Detailed Implementation

[0022] (Implementation Method)

[0023] Hereinafter, the bubble generating apparatus and bubble generating system according to this embodiment will be described in detail with reference to the accompanying drawings. Furthermore, the same or equivalent parts in the drawings will be labeled with the same reference numerals, and their descriptions will not be repeated.

[0024] first, Figure 1 This is a schematic diagram of a bubble generating system 100 using the bubble generating apparatus 1 according to this embodiment. Figure 1 The bubble generating device 1 shown is installed at the bottom of a liquid tank 10 containing liquids such as water, gasoline, or light oil, and is used to generate fine bubbles 200 in the liquid in the liquid tank 10. Furthermore, the bubble generating system 100 can be applied to various systems such as water purification devices, drainage treatment devices, fish farming tanks, and fuel injection devices.

[0025] Furthermore, the liquid introduced into the liquid tank 10 varies depending on the system being applied; for example, it is water in a water purification device, but liquid fuel in a fuel injection device. Additionally, the liquid tank 10 only needs to be able to temporarily store liquid, and also includes a tank in which the liquid continuously flows within the pipe through which it is introduced.

[0026] The bubble generating device 1 includes a vibrating plate 2, a cylindrical body 3, and a piezoelectric element 4. The bubble generating device 1 is provided in a hole opened in a part of the bottom of the liquid tank 10, and the vibrating plate 2 protruding from the hole toward the liquid side is vibrated by the piezoelectric element 4, thereby generating fine bubbles 200 from a plurality of fine holes (openings) formed in the vibrating plate 2.

[0027] The vibrating plate 2 is formed, for example, from a resin plate, a metal plate, a Si or SOI (Silicon on Insulator) substrate, a porous ceramic plate, or a glass plate. When the vibrating plate 2 is formed from a glass plate, it can, for example, be a glass plate through which ultraviolet light and deep ultraviolet light with wavelengths of 200 nm to 380 nm are transmitted. By forming it from a glass plate through which ultraviolet and deep ultraviolet light are transmitted, a light source emitting ultraviolet light from the other side of the vibrating plate 2 relative to the liquid in the liquid tank 10 can be provided, enabling both ozone-based sterilization and ultraviolet light-based sterilization to be performed.

[0028] The vibrating plate 2 has multiple fine holes, with one side in contact with the liquid (e.g., water) in the liquid tank 10 and the other side in contact with the gas (e.g., air). That is, in the bubble generating device 1, the vibrating plate 2 separates the liquid from the air, applying back pressure to the other side. Figure 1(As indicated by the arrow), the gas is thus fed into the liquid in the liquid tank 10 through multiple fine holes. The bubble generating device 1 tears the gas fed into the liquid through the multiple fine holes by the vibration of the vibrating plate 2, thereby generating fine bubbles 200.

[0029] To explain in more detail, when gas attempts to exit through multiple fine pores, the surface tension of the liquid hinders its intrusion into the liquid side. On the other hand, the buoyancy of the gas breaks this surface tension. The diameter of the bubble 200 is determined by this balance, but the vibration of the vibrating plate 2 creates an effect of peeling away from the walls of the fine pores, resulting in a state similar to reduced surface tension. As a result, in the initial stage of gas exiting through multiple fine pores, the vibration of the vibrating plate 2 tears the gas apart, enabling the generation of micro-bubbles 200 with a diameter of approximately 1 / 10 compared to the case where the vibration of the vibrating plate 2 is not applied.

[0030] Although not shown in the figure, for example, multiple micropores are formed in a 5mm × 5mm area at the center of the vibrating plate 2 with a diameter of 14mm. When the diameter of the micropores is set to 1μm and the spacing between the micropores is set to 0.25mm, 441 micropores can be formed in the 5mm × 5mm area.

[0031] In the bubble generating device 1, the vibrating plate 2 is vibrated via the piezoelectric element 4 through the cylindrical body 3. Figure 2 This is a perspective view of the bubble generating device 1 according to this embodiment. Figure 3 This is a cross-sectional view of the bubble generating apparatus according to this embodiment. Figure 3 As shown, Figure 1 The shown cylindrical body 3 includes a first cylindrical body 31, a spring portion 32, a second cylindrical body 33, and a counterweight portion 34. Furthermore, Figure 3 The bubble generating device 1 is a cross-sectional view cut off in the center along the through direction of the second cylindrical body 33 (vertical direction in the figure).

[0032] The end of the vibrating plate 2 is held by the end of a cylindrical first cylindrical body 31. The vibrating plate 2 is supported by the first cylindrical body 31 at a position where the direction of the plurality of fine holes formed in the vibrating plate 2 is parallel to the vibration direction of the first cylindrical body 31. The outer diameter of the first cylindrical body 31 is smaller than the diameter of the vibrating plate 2; for example, the diameter of the vibrating plate 2 is 14 mm, while the outer diameter of the first cylindrical body 31 is 8 mm. The end of the first cylindrical body 31 opposite to the vibrating plate 2 is supported by a spring portion 32. The spring portion 32 is a plate-shaped component capable of elastic deformation, supporting the bottom surface of the cylindrical first cylindrical body 31 and extending outward from the supported position. The spring portion 32 is hollow and circular, and the first cylindrical body 31 is formed on this hollow circular shape.

[0033] The spring portion 32 is supported by a second cylindrical body 33 at a position located outside the support of the first cylindrical body 31. The second cylindrical body 33 is cylindrical in shape. The second cylindrical body 33 supports the spring portion 32 at one end. At the other end of the second cylindrical body 33, a cylindrical counterweight portion 34 is provided on the outer side. Furthermore, the shape, position, and mass of the counterweight portion 34 satisfy the condition that it can be driven to make the outer end of the spring portion 32 or the outer surface of the second cylindrical body 33 a vibrating node. The shape, position, and mass of the counterweight portion 34 are simulated in other structures of the bubble generating device 1 to determine whether this condition is satisfied. Of course, the bubble generating device 1 may not have a counterweight portion 34 as long as it can be driven to make the outer end of the spring portion 32 or the outer surface of the second cylindrical body 33 a vibrating node.

[0034] A hollow circular piezoelectric element 4 is provided on the lower surface of the spring portion 32, matching the shape of the spring portion 32. The piezoelectric element 4 vibrates in the penetrating direction (vertical direction in the figure) of the first cylindrical body 31. The vibration of the piezoelectric element 4 in the penetrating direction of the first cylindrical body 31 causes the spring portion 32 to vibrate in the penetrating direction of the first cylindrical body 31, causing the first cylindrical body 31 to be displaced approximately uniformly in the vertical direction. Furthermore, the piezoelectric element 4 may not be hollow and circular, but may be circular covering the entire inner diameter of the second cylindrical body 33. In addition, the shape, position, and mass of the counterweight portion 34 are more preferably satisfied by the following condition: when the piezoelectric element 4 is driven, it is possible to drive the vibrating plate 2 to vibrate vertically in parallel. The shape, position, and mass of the counterweight portion 34 are determined to satisfy this condition by simulating other structures of the bubble generating device 1. Of course, the bubble generating device 1 may not have a counterweight portion 34 as long as it is able to drive the vibrating plate 2 to vibrate vertically in parallel. When the outer diameter of the first cylindrical body 31 is the same as the diameter of the vibrating plate 2, the outer diameter of the second cylindrical body 33 becomes larger, and therefore the diameter of the piezoelectric element 4 must also become larger, which is the main factor increasing the cost. Therefore, it is preferable that the outer diameter of the first cylindrical body 31 is smaller than the diameter of the vibrating plate 2. Specifically, it is sufficient to form a space within the first cylindrical body 31 that is adequate to ensure the amount of air intake required for bubble generation. The smaller the outer diameter of the first cylindrical body 31, the smaller the diameter of the piezoelectric element 4 can be, thus reducing the cost.

[0035] The first cylindrical body 31, the spring portion 32, the second cylindrical body 33, and the counterweight portion 34 are integrally formed. The first cylindrical body 31, the spring portion 32, the second cylindrical body 33, and the counterweight portion 34 are made of, for example, a metal such as stainless steel or a synthetic resin. Preferably, a metal with high rigidity, such as stainless steel, is preferred. Alternatively, the first cylindrical body 31, the spring portion 32, the second cylindrical body 33, and the counterweight portion 34 may be formed as separate parts. The method of joining the vibrating plate 2 to the first cylindrical body 31 is not particularly limited. The vibrating plate 2 and the first cylindrical body 31 can be joined by adhesives, welding, fitting, pressing, etc.

[0036] like Figure 1 As shown, the bubble generating device 1 is connected to a hole in a portion of the bottom of the liquid tank 10 at the outer end of the spring portion 32 or the outer side of the second cylindrical body 33. As will be described later, even when the vibrating plate 2 is vibrated by the piezoelectric element 4, the outer end of the spring portion 32 or the outer side of the second cylindrical body 33 hardly vibrates. Therefore, it is possible to vibrate the vibrating plate 2 substantially without transmitting the vibration of the piezoelectric element 4 to the liquid tank 10.

[0037] The piezoelectric element 4 vibrates, for example, by polarization in the thickness direction. The piezoelectric element 4 is made of lead zirconate titanate-based piezoelectric ceramic. However, other piezoelectric ceramics such as (K,Na)NbO3 can also be used. Additionally, piezoelectric single crystals such as LiTaO3 can also be used.

[0038] In the bubble generating apparatus 1, a structure is adopted in which the vibrating plate 2 in contact with the liquid is, for example, a glass plate, and the vibrating plate 2 is vibrated by a piezoelectric element 4 via a cylindrical body 3. This allows the space for introducing gas to be completely separated from the liquid. By completely separating the space for introducing gas from the liquid, it is possible to prevent the electrical wiring of the piezoelectric element 4 from being immersed in the liquid. In addition, in the bubble generating apparatus 1, even if a light source emitting ultraviolet light relative to the liquid in the liquid tank 10 is provided, the light source can be placed in the space for introducing gas, thus preventing the electrical wiring of the light source from being immersed in the liquid.

[0039] Next, the vibration of the vibrating plate 2 in the bubble generating device 1 will be described in detail. Figure 4 This is a diagram used to illustrate the vibration of the vibrating plate 2 of the bubble generating apparatus 1 according to this embodiment. Figure 4 A cross-sectional view of the bubble generating device 1 and the displacement results of a vibration simulation of the vibrating plate 2 are shown. Figure 4 In the diagram, the reference position of the bubble generating device 1 before vibration begins is represented by a dashed line, and the position of the bubble generating device 1 after displacement is represented by a solid line.

[0040] When based on data from controller 20 (reference) Figure 1When the drive signal causes the piezoelectric element 4 to vibrate in the penetrating direction of the first cylindrical body 31, for example, as Figure 4 As shown, the spring portion 32 displaces downward. Because the spring portion 32 supporting the first cylindrical body 31 sinks downward, the entire first cylindrical body 31 displaces downward, resulting in the entire vibrating plate 2, which is held in the first cylindrical body 31, displacing downward. At this time, a node (the portion that does not displace due to the vibration of the piezoelectric element 4) is formed at the outer end of the spring portion 32 or on the outer surface of the second cylindrical body 33. Therefore, by engaging the liquid tank 10 at the outer end of the spring portion 32 or on the outer surface of the second cylindrical body 33, the vibrating plate 2 can vibrate without substantially transmitting the vibration of the piezoelectric element 4 to the liquid tank 10.

[0041] Although not shown, by continuously vibrating the piezoelectric element 4, the spring portion 32 moves upward after it moves downward. Since the position of the spring portion 32 supporting the first cylindrical body 31 bulges upward, the entire first cylindrical body 31 moves upward, and as a result, the entire vibrating plate 2 held in the first cylindrical body 31 moves upward.

[0042] In the bubble generating apparatus 1 according to this embodiment, as described above, by vibrating the piezoelectric element 4, the vibrating plate 2 is displaced approximately uniformly in the vertical direction, while the vibrating plate 2 itself remains almost undeformed. Therefore, in the bubble generating apparatus 1, by utilizing the vertical resonance of the spring portion 32 to drive the vibrating plate 2 in a planar manner, the same shear stress is achieved at any position of the vibrating plate 2. This shear stress is used to tear the gas introduced through the multiple fine holes of the vibrating plate 2, thereby generating uniform bubbles. Furthermore, in this embodiment, the approximately uniform vertical vibration of the vibrating plate 2 is referred to as spring vibration (piston vibration), and such a vibration mode is called the spring vibration mode.

[0043] When the bubble generating device 1 vibrates the vibrating plate 2 through the spring vibration mode, the frequency of the driving signal applied to the piezoelectric element 4 is set as the resonant frequency. Figure 5 This is a graph showing the relationship between the frequency and impedance of the drive signal applied to the piezoelectric element 4 of the bubble generating device 1 according to this embodiment.

[0044] from Figure 5 It can be seen that the impedance of the piezoelectric element 4 changes significantly at a frequency A of approximately 32 kHz. The controller 20 drives the vibrating plate 2 at frequency A, thereby enabling the vibrating plate 2 to vibrate through a spring vibration mode. This frequency A is the resonant frequency of the spring vibration mode.

[0045] The resonant frequency of the spring vibration mode changes when the vibrating plate 2 is driven in a gas and when the vibrating plate 2 is driven in a liquid. Figure 6This is a graph showing the change in resonant frequency when the vibrating plate 2 of the bubble generating apparatus 1 according to this embodiment is driven in a gas and when the vibrating plate 2 is driven in a liquid.

[0046] from Figure 6 It can be seen that when the vibrating plate 2 is driven in a gas, the resonant frequency is approximately 32 kHz, and the vibration velocity of the vibrating plate 2 is at its maximum. On the other hand, when the vibrating plate 2 is driven in a liquid, the resonant frequency is approximately 30 kHz, and the vibration velocity of the vibrating plate 2 is at its maximum. It can be seen that compared with the case where the vibrating plate 2 is driven in a gas, the vibration velocity is reduced when the vibrating plate 2 is driven in a liquid, but even in a liquid, the vibrating plate 2 vibrates sufficiently. Therefore, it can be seen that for the bubble generating device 1, even when the vibrating plate 2 is in a liquid, sufficient shear stress is generated to tear apart the gas introduced through the multiple fine holes of the vibrating plate 2 and generate bubbles.

[0047] In addition, the displacement of the vibrating plate 2 was compared when the vibrating plate 2 was driven in a gas and when the vibrating plate 2 was driven in a liquid. Figure 7 This is a graph showing the displacement of the vibrating plate 2 when the vibrating plate 2 of the bubble generating apparatus 1 according to this embodiment is driven in a gas and when the vibrating plate 2 is driven in a liquid. Figure 7 (a) is a graph showing the displacement of the vibrating plate 2 when it is driven in a gas. Figure 7 (b) is a graph showing the displacement of the vibrating plate 2 when it is driven in a liquid. Furthermore, in Figure 7 (a) and Figure 7 In (b), Figure 4 The vertical direction is defined as the Z-direction, the horizontal direction as the X-direction, and the direction perpendicular to both the X and Z directions as the Y-direction. Additionally, in Figure 7 (a) and Figure 7 In (b), the solid line represents the displacement of the vibrating plate 2 in the X direction, the dashed line represents the displacement of the vibrating plate 2 in the Y direction, and the arrow in the figure represents the state of the vibrating plate 2 being displaced in the upward direction.

[0048] from Figure 7 As shown in (a), when the vibrating plate 2 is driven in the gas with a voltage of 2Vp-p, the displacement within the XY plane of the vibrating plate 2 is uniformly approximately 3.3 nm when observed at the peak value. On the other hand, from... Figure 7As shown in (b), when the vibrating plate 2 is driven in a liquid, the displacement at the end of the vibrating plate 2 is reduced compared to when it is driven in a gas. However, at the center of the vibrating plate 2, the displacement is uniformly about 2.0 nm in the XY plane. Normally, when the vibrating plate is placed in a liquid, the vibration is braked to about 1 / 10. However, it can be seen that for the bubble generating device 1, even when the vibrating plate 2 is in a liquid, the vibration of the vibrating plate 2 tears the gas introduced through the multiple fine holes of the vibrating plate 2, thus generating sufficient bubbles.

[0049] As described above, the bubble generating device 1 of this embodiment is installed in a liquid tank 10 to generate fine bubbles in the liquid in the liquid tank 10. The bubble generating device 1 includes a vibrating plate 2, a first cylindrical body 31, a spring portion 32, a second cylindrical body 33, and a piezoelectric element 4. The vibrating plate 2 has multiple openings and is positioned such that one side contacts the liquid in the liquid tank 10, and the other side contacts the gas. The first cylindrical body 31 supports the vibrating plate 2 at one end. The spring portion 32 is plate-shaped and supports the other end of the first cylindrical body 31. The second cylindrical body 33 supports the spring portion 32 at one end at a position located further outward than the position supporting the first cylindrical body 31. The piezoelectric element 4 causes the spring portion 32 to vibrate. The piezoelectric element 4 is disposed on the side of the spring portion 32 supported by the second cylindrical body 33, further inward than the position supported by the second cylindrical body 33.

[0050] Therefore, the bubble generating device 1 has the piezoelectric element 4 placed on the side supported by the second cylindrical body 33 and on the surface of the spring portion 32, which is further inward than the position supported by the second cylindrical body 33. Thus, it can effectively generate fine bubbles, regardless of the type of liquid placed in the liquid tank 10.

[0051] The piezoelectric element 4 is preferably disposed on the surface of the spring portion 32 on the side supported by the second cylindrical body 33, covering the entire inner diameter of the second cylindrical body 33. This allows for more efficient generation of fine bubbles.

[0052] The bubble generating device 1 preferably contacts the liquid tank 10 at the outer end of the spring portion 32 or the outer surface of the second cylindrical body 33, and also includes a controller 20 (control unit) capable of controlling the drive of the piezoelectric element 4. When liquid is placed in the liquid tank 10, the resonant frequency of the piezoelectric element 4 changes compared to when it is in a gas environment. The controller 20 preferably searches while sweeping the drive frequency and controls the drive of the piezoelectric element 4 so that the outer end of the spring portion 32 or the outer surface of the second cylindrical body 33 becomes the vibration node. This allows the vibrating plate 2 to vibrate without transmitting the drive of the piezoelectric element 4 to the liquid tank 10.

[0053] The bubble generating device 1 preferably further includes a counterweight 34 disposed at the other end of the second cylindrical body 33. The counterweight 34 preferably has a shape, position, and mass that allows for driving the outer end of the spring portion 32 or the outer surface of the second cylindrical body 33 to become a vibrating node when the piezoelectric element 4 is driven. This makes it easier to achieve the driving of the outer end of the spring portion 32 or the outer surface of the second cylindrical body 33 as a vibrating node.

[0054] The counterweight 34 preferably has a shape, position, and mass that satisfy the condition that when the piezoelectric element 4 is driven, it can drive the vibrating plate 2 to vibrate up and down in parallel. This makes it easier to achieve the drive that makes the vibrating plate 2 vibrate up and down in parallel.

[0055] The vibrating plate 2 is preferably supported by the first cylindrical body 31 at a position where the direction of the plurality of fine holes formed in the vibrating plate 2 is parallel to the vibration direction of the first cylindrical body 31. This allows the vibration direction of the vibrating plate 2 to be aligned with the direction in which buoyancy is generated in the gas.

[0056] (Variation Example 1)

[0057] In the bubble generating apparatus 1 described in the above embodiment, the shape of the counterweight 34 is described as cylindrical along the shape of the second cylindrical body 33, but it is not limited to this. For example, the shape of the counterweight can also be rectangular when viewed from the side of the vibrating plate 2 that is in contact with the liquid. Figure 8 This is a perspective view of the bubble generating apparatus 1a involved in Modified Example 1. Furthermore, regarding... Figure 8 The bubble generating device 1a shown in the figure has the same properties as the bubble generating device 1a shown in the figure. Figure 2 The bubble generating device 1 shown has the same structure and is labeled with the same reference numerals, so detailed descriptions will not be repeated.

[0058] At the other end of the second cylindrical body 33, a prism-shaped counterweight 34a is provided on the outer side. Furthermore, the shape, position, and mass of the counterweight 34a satisfy the following conditions: it is capable of driving the outer end of the spring part 32 or the outer surface of the second cylindrical body 33 to become a vibrating node, and it is capable of driving the vibrating plate 2 to vibrate up and down in parallel. The shape, position, and mass of the counterweight 34a were determined to satisfy these conditions by simulating other structures of the bubble generating device 1a.

[0059] (Variation Example 2)

[0060] Furthermore, in the bubble generating apparatus 1 according to the above embodiment, it is described that the vibrating plate 2 is supported by the first cylindrical body 31 at a position where the penetrating direction of the plurality of fine holes formed in the vibrating plate 2 is parallel to the vibration direction of the first cylindrical body 31, but this is not a limitation. For example, the vibrating plate may also have a structure in which the penetrating direction of the plurality of openings is perpendicular to the vibration direction of the first cylindrical body. Figure 9 This is a cross-sectional view of the bubble generating apparatus 1b involved in Modified Example 2. Furthermore, regarding... Figure 9 The bubble generating device 1b shown is related to... Figure 3 The bubble generating device 1 shown has the same structure and is labeled with the same reference numerals, so detailed descriptions will not be repeated.

[0061] The vibrating plate 2a held at the end of the first cylindrical body 31 does not have multiple fine holes (openings), but a structure 2A with multiple fine holes is provided in a direction perpendicular to the vibrating plate 2a. The structure 2A is a hollow prism, and the plate 2b is provided on two opposite faces of the prism. The hollow part of the structure 2A and the first cylindrical body 31 are connected by a hollow column 2c, and gas is introduced from the first cylindrical body 31 into the hollow part of the structure 2A.

[0062] Gas introduced into the hollow portion of structure 2A is discharged to the liquid side through multiple fine holes provided in plate 2b. The gas discharged to the liquid side through these fine holes is torn into fine bubbles 200 by plate 2b, which vibrates in a direction perpendicular to vibrating plate 2a. When piezoelectric element 4 is driven, vibrating plate 2a vertically in parallel, the penetrating direction of the multiple fine holes in plate 2b vibrates vertically relative to vibrating plate 2a. Therefore, a shear stress greater than the shear stress generated when vibrating plate 2b vertically is applied to the gas discharged to the liquid side through the multiple fine holes by plate 2b vibrating in a direction perpendicular to vibrating plate 2a can be applied. Furthermore, since the bubbles 200 are discharged to the liquid side in a direction perpendicular to vibrating plate 2a, they are not subjected to sound pressure caused by ultrasonic waves generated by the vibration of vibrating plate 2a, and are not forced to rise due to this sound pressure.

[0063] Furthermore, since a plate 2b with multiple micro-holes is disposed on the structure 2A, the piezoelectric element 4 is driven to vibrate the structure 2A up and down via the vibrating plate 2a. Therefore, the drive of the piezoelectric element 4 is not directly applied to the plate 2b, making the plate 2b less prone to bending vibration. Because the plate 2b is less prone to bending vibration, even if a thinner vibrating plate is used, damage caused by bending deformation can be prevented. Since the aspect ratio limit for micro-hole processing is constant, it is easier to form micro-holes with a thinner plate. That is, even if multiple finer micro-holes are provided on the plate 2b, it is less likely to be damaged. For example, micro-holes with a lower limit of 2μm or less can be processed down to 0.5μm on the SOI substrate of the plate 2b.

[0064] Furthermore, the construction of structure 2A is not limited to Figure 9 The structure shown. In Figure 9 In the structure 2A shown, plates 2b are provided on two opposing faces of the prism, but plates 2b can also be provided on all four faces of the cube. Figure 10 This is a perspective view of another structure 2B. Structure 2B is a hollow cube with plates 2b on its four sides. The hollow portion of structure 2B is connected to the first cylindrical body 31 via hollow pillars 2c, and gas is introduced from the first cylindrical body 31 into the hollow portion of structure 2B. Bubbles 200 can be generated from the four sides of the cube in structure 2B.

[0065] In addition, the shape of the structure is not limited to a hollow prism; it can also be a hollow cylinder. Figure 11 This is a perspective view of another structure 2C. In structure 2C, which is a hollow cylinder, a cylindrical body 2d with multiple fine holes is disposed on the side of the cylinder. The hollow portion of structure 2C and the first cylindrical body 31 are connected by a hollow column 2c, and gas is introduced from the first cylindrical body 31 into the hollow portion of structure 2C. In structure 2C, bubbles 200 can be generated from the entire circumference of the cylinder.

[0066] The vibrating plate 2a is preferably a structure 2A to 2C with multiple fine holes whose through-direction is perpendicular to the vibration direction of the first cylindrical body 31. This protects the bubble 200 from the influence of ultrasound, increases the shear stress of the plate 2b or the cylinder 2d, and makes the plate 2b itself less prone to damage. Furthermore, the structure is preferably cylindrical. This allows the bubble 200 to be generated from the entire circumference of the structure 2C.

[0067] like Figure 2 As shown, the second cylindrical body 33 may also be provided with a flange portion 33a, which is connected to the liquid tank 10. Therefore, in the bubble generating system 100 equipped with the bubble generating device 1 and the liquid tank 10, the airtightness between the bubble generating device 1 and the liquid tank 10 is improved. Furthermore, since the bubble generating device 1 is connected to the liquid tank 10 on the side of the second cylindrical body 33, only the vibrating plate 2 can vibrate, without transmitting the vibration of the piezoelectric element 4 to the liquid tank 10.

[0068] All points in the embodiments disclosed herein are merely illustrative and should not be considered as limitations on the invention. The scope of the invention is defined by the claims rather than by the foregoing description, and includes all modifications within the meaning and scope equivalent to the claims.

[0069] Explanation of reference numerals in the attached figures

[0070] 1, 1a, 1b...bubble generating device; 2, 2a...vibrating plate; 2A, 2B, 2C...structure; 2b...plate; 2c...column; 2d...cylinder; 3...cylindrical body; 4...piezoelectric element; 10...liquid tank; 20...controller; 31...first cylindrical body; 32...spring part; 33...second cylindrical body; 33a...flange part; 34, 34a...counterweight part; 100...bubble generating system; 200...bubble.

Claims

1. A bubble generating apparatus that is installed in a liquid tank to generate fine bubbles in a liquid in the liquid tank, wherein Possessing: a vibrating plate formed with a plurality of opening portions and disposed at a position where one face is in contact with a liquid of the liquid tank and the other face is in contact with a gas; a first cylindrical body supporting the vibrating plate with one end portion; a plate-shaped spring portion supporting the other end portion of the first cylindrical body; a second cylindrical body supporting the spring portion with one end portion at a position located outward of the position supporting the first cylindrical body; and a piezoelectric element vibrating the spring portion, the piezoelectric element is disposed in a face of the side of the spring portion supported by the second cylindrical body inward of the position supported by the second cylindrical body.

2. The bubble generating apparatus according to claim 1, wherein the piezoelectric element is disposed in the entire face of the inner diameter of the second cylindrical body in the face of the side of the spring portion supported by the second cylindrical body.

3. The bubble generating apparatus according to claim 1 or 2, wherein an end portion of the outer side of the spring portion or an outer side face of the second cylindrical body is in contact with the liquid tank, the bubble generating apparatus further possesses a control portion capable of controlling the driving of the piezoelectric element, the control portion controls the driving of the piezoelectric element so that the end portion of the outer side of the spring portion or the outer side face of the second cylindrical body becomes a node of vibration.

4. The bubble generating apparatus according to claim 3, wherein a counterweight portion is further possessed, the counterweight portion being disposed at the other end portion of the second cylindrical body, the counterweight portion has a shape, position, and mass satisfying the condition that, in the case of driving the piezoelectric element, driving can be performed so that the end portion of the outer side of the spring portion or the outer side face of the second cylindrical body becomes a node of vibration.

5. The bubble generating apparatus according to claim 4, wherein the counterweight portion has a shape, position, and mass satisfying the condition that, in the case of driving the piezoelectric element, driving can be performed so that the vibrating plate is vibrated up and down in parallel.

6. The bubble generating apparatus according to claim 4 or 5, wherein the shape of the counterweight portion, viewed from the face of the vibrating plate in contact with the liquid, is a rectangular shape.

7. The bubble generating apparatus according to claim 1 or 2, wherein the vibrating plate is supported by the first cylindrical body at a position where the through direction of the plurality of opening portions formed in the vibrating plate is parallel with respect to the vibration direction of the first cylindrical body.

8. The bubble generating apparatus according to claim 1 or 2, wherein the vibrating plate has a configuration body in which the through direction of the plurality of opening portions is perpendicular with respect to the vibration direction of the first cylindrical body.

9. The bubble generating apparatus according to claim 8, wherein the configuration body is a cylindrical body. Possessing:

10. A bubble generating system wherein, the bubble generating apparatus according to any one of claims 1 to 9; and the liquid tank.

11. The bubble generating system according to claim 10, wherein the bubble generating apparatus is combined with the liquid tank at the side face of the second cylindrical body. ​

Images