Microbubble generator

Abstract

To provide a fine bubble generation device where an intake position of a gas can be fixed when generating fine bubbles.SOLUTION: A fine bubble generation device comprises: a circular disk 10 where a central groove 11 at a central part and a plurality of radial grooves 12 from the central groove 11 to a peripheral edge are grooved on an undersurface 10u and immersed into a liquid phase Pb; a drive unit 25 rotating the circular disk 10 around a central axis; and a suction pipe 30 having one end 32 facing the central groove 11 on the undersurface 10u of the circular disk 10 and the other end 31 communicated with the gas phase Pa, wherein a liquid Q and a gas G are suctioned from the central groove 11 to each radial groove 12 by the rotation of the circular disk 10 by the drive unit 25, and bubbles S pulverized by each radial groove 12 are discharged from the peripheral edge of the circular disk 10.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a microbubble generating device, and more particularly to a device that generates microbubbles by rotating a disk in a liquid phase. [Background technology]

[0002] Microbubbles are tiny bubbles with a main particle size of 100 μm or less (e.g., several tens of μm to several μm), also known as fine bubbles, microbubbles, nanobubbles, etc. For example, water quality can be improved by supplying microbubbles containing trapped air into water and dissolving them. It has also been reported that water containing microbubbles has an activating effect on microorganisms, plants, and animals, and for example, the microbubbles can be used to increase the yield of agricultural crops. Furthermore, microbubbles containing various gases (oxygen, ozone, nitrogen, etc.) are also used in the fields of medicine and food, and it has been reported that microbubbles containing ozone gas, for example, have a strong bactericidal effect (see Non-Patent Document 1).

[0003] One example of a method for generating microbubbles is an ejector type in which a liquid is passed through a small diameter pipe at high speed, and the negative pressure generated by the liquid flow is used to draw in gas into the liquid, and the cavitation generated downstream breaks up the gas, creating microbubbles (see Patent Documents 1 to 3 and Non-Patent Document 2).However, the conventional ejector type method for generating microbubbles requires the gas to be pressurized using a pump or the like, and requires a relatively large amount of energy to generate the microbubbles, making it difficult to apply it to the ocean or fish farms where there is no power source.

[0004] In response to this, a disk-type micro-bubble generator 50 has been proposed that can generate micro-bubbles with relatively little energy, as shown in Fig. 4 (see Patent Document 4). The illustrated example of the micro-bubble generator 50 includes a disk 51 having a plurality of hollow ducts (hollow pipes) 60 attached radially on one side and an airtight chamber 55 on the other side, a hollow rotating shaft pipe 70 inserted into the center of the disk 51 and having one end connected to the airtight chamber 55, and a drive unit 80 that rotates the disk 51 around the pipe 70 (see Fig. 4(A)).

[0005] The disk 51 in the illustrated example is composed of a circular substrate 52 (see FIG. 4(C)) of a predetermined diameter R0, a doughnut-shaped substrate 61 (see FIG. 4(D)) with a central hole 62 of the same diameter aligned and facing one side (the lower side in the illustrated example) of the circular substrate 52, a plurality of hollow ducts 60 (see FIG. 4(D)) of length L2 radially arranged at a required angular interval θ in the facing gap between the circular substrate 52 and the doughnut-shaped substrate 61, and an airtight chamber 55 (see FIG. 4(A)) airtightly covering the opposite side (the upper side in the illustrated example) of the circular substrate 52. As shown in FIG. 4(D), a central gap 63 of a predetermined diameter (=R0-L2) connected to the central hole 62 of the doughnut-shaped substrate 61 is formed in the central portion of the disk 51 surrounded by the plurality of hollow ducts 20. As shown in FIG. 4(C), a plurality of minute through holes 56 leading to the hollow portions of the respective hollow pipes 60 are drilled in the circular substrate 52 at a required angular interval θ.

[0006] As shown in FIG. 4(E), which is a cross-sectional view of FIG. 4(A), the airtight chamber 55 of the disk 51 can be formed, for example, by aligning a circular substrate 53 (see FIG. 4(B)) of the same diameter with the opposite side (upper side) of the circular substrate 52 and sealing the peripheral portion of the opposing gap between the pair of circular substrates 52, 53 with a sealant 54. As shown in FIG. 4(A), an intake hole 71 and an exhaust hole 73 are provided at one end and the other end of a hollow rotating shaft pipe 70, respectively, and one end of the pipe is inserted and fixed in the center of the disk 51 to communicate the exhaust hole 73 with the airtight chamber 55, and the other end is exposed above the liquid surface to communicate the intake hole 71 with the gas phase Pa. The drive shaft 81 of the drive unit 80 is connected to the other end of the pipe 70 exposed above the liquid surface. The reference numeral 82 in the figure indicates a coupling that connects the other end of the pipe 70 with the drive shaft 81 of the drive unit 80.

[0007] As shown in FIG. 4(A), when the disk 51 is immersed in the liquid phase and rotated around the pipe 70 at a required rotation speed ω by the driving device 80 protruding above the liquid surface, the liquid Q flows from the central gap 63 of the disk 51 into each hollow duct 60 due to the centrifugal force F generated during rotation, as shown in FIG. 4(E), and a liquid flow at a required speed flowing from the center of the disk 51 to the outer periphery is formed in the hollow portion of each hollow duct 60. In addition, the liquid flow sucks gas G from the airtight chamber 53 of the disk 51 through the minute through holes 56 into each hollow duct 60 and mixes with the liquid Q. Although the pressure of the airtight chamber 55 decreases due to the sucking of gas G, gas G is replenished from the gas phase Pa to the airtight chamber 55 through the pipe 70. An intake amount adjustment plug 72 is provided in the intake hole 71 of the pipe 70, and the flow rate of the gas G to be taken in can be adjusted.

[0008] As shown in Figures 5(A) and (B), each hollow pipe 60 of the disk 51 functions in the same way as a conventional ejector. That is, negative pressure is generated by the liquid flow passing through the relatively narrow hollow pipe 60 from the relatively wide central gap 63 of the disk 51, and the gas G is sucked from the airtight chamber 55 into each hollow pipe 60 by the negative pressure and mixed with the liquid Q. The mixed gas G is crushed by cavitation in the process of being sent to the pipe outlet 60a together with the liquid Q, and is released into the liquid phase Pb from the outer periphery of the disk into the liquid phase Pb. In this way, the fine bubble generator 50 of Figure 4 can efficiently generate fine bubbles S only by the driving energy of the rotation of the relatively small disk 51, and does not need to use a device such as a pump to pressurize the liquid Q, so it can be easily applied on the ocean or in a fish farm without a power source. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2005-334869 A [Patent Document 2] JP 2006-167612 A [Patent Document 3] JP 2019-147086 A [Patent Document 4] JP 2019-034292 A [Non-patent literature]

[0010] [Non-Patent Document 1] Shozo Himuro, "Finance of Fine Bubbles and Their Applications," Science Materials No. 80, Jikkyo Publishing, September 26, 2016, Internet<http: / / www.jikkyo.co.jp / download / detail / 45 / 9992657592> [Non-Patent Document 2] Fine Bubble Society of Japan, edited by Koichi Terasaka et al., "Introduction to Fine Bubbles, Chapter 6: Fine Bubble Generation Technology," Nikkan Kogyo Shimbun, published November 28, 2016, pp. 167-192 DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0011] The conventional fine bubble generator 50 shown in Fig. 4 can adjust the particle size and amount (concentration) of the fine bubbles S generated by adjusting the amount of gas G taken in from the intake hole 71 of the hollow rotating shaft pipe 70 (intake amount adjustment plug 72), etc. However, the hollow rotating shaft pipe 70 functions not only as a flow path for taking in the gas G into the airtight chamber 55 but also as the rotation axis of the disk 51, and the position of the intake hole 71 varies according to the rotation of the disk 51, so it is difficult to operate the intake amount adjustment plug 72 of the intake hole 71 unless the rotation of the disk 51 is stopped, and there is a problem that the amount of gas G taken in cannot be finely adjusted steplessly while generating the fine bubbles S.

[0012] Furthermore, in the conventional micro-bubble generator 50, the position of the intake hole 71 that takes in the gas G when generating micro-bubbles varies according to the rotation of the disk 51, so although it is possible to open the intake hole 71 to the atmosphere, it is difficult to connect supply ports for various gases (oxygen, ozone, nitrogen, etc.) to the intake hole 71, and there is a problem in that micro-bubbles containing such gases cannot be generated. As described above, the use of micro-bubbles containing various gases is progressing, and there is a demand for the development of technology that can easily generate such micro-bubbles with relatively little energy.

[0013] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a micro-bubble generating device capable of fixing the gas intake position when generating micro-bubbles. [Means for solving the problem]

[0014] Figure 1 and Figure 2 Referring to the embodiment, the microbubble generating device according to the present invention is a circular disk 10 (see FIG. 1(D)) having a central groove 11 at the center and a plurality of radial grooves 12 extending from the central groove 11 to the periphery on the lower surface 10u, which is immersed in liquid Pb. A donut-shaped cover plate 14 (see FIGS. 2(B) and (E)) that covers the lower surface 10u of the circular disk 10 except for the central groove 11.The device includes a drive unit 25 (see FIG. 1(A)) for rotating the circular disk 10 around its central axis, and an intake pipe 30 (see FIG. 1(A)) having one end 32 facing the central groove 11 on the lower surface 10u of the circular disk 10 and the other end 31 communicating with the gas phase Pa. The rotation of the circular disk 10 by the drive unit 25 causes the central groove 11 to flow. A negative pressure is generated in the intake pipe 30, and the gas G sucked in from one end 32 of the intake pipe 30 is mixed with the liquid Q by the negative pressure and flows into each radial groove 12 covered with the doughnut-shaped cover plate 14. The bubbles S are crushed in each radial groove 12 and released from the periphery of the circular disk 10 (see FIG. 1(E)).

[0015] In a preferred embodiment, as shown in FIG. 2(D), each of the plurality of radial grooves 12 on the circular disk 10 is a curved radial groove 12a whose middle portion is curved in the direction of rotation of the circular disk 10.

[0016] In a more preferable embodiment, as shown in Figures 1(A) and 2(A), an intake amount adjustment valve 34 is provided at the other end 31 of the intake pipe 30. Preferably, a shaft 20 is provided that extends to the gas phase Pa along the central axis of the upper surface 10t of the circular disk 10, and a drive unit 25 is attached to the other end of the shaft 20. More preferably, as shown in Figures 2(A) and 2(F), a protective cover 40 is provided that covers the circular disk 10 and the shaft 20 and has a bottom hole 43 facing the central groove 11 of the bottom surface 10u of the circular disk and a discharge port 41 for discharging the discharge flow from the outer periphery of the circular disk, and is isolated from the rotation of the drive unit 25, and the intake pipe 30 is arranged along the outer surface of the protective cover 40. Effect of the Invention

[0017] The microbubble generating device according to the present invention comprises a circular disk 10 having a central groove 11 at the center and a plurality of radial grooves 12 extending from the central groove 11 to the periphery on the lower surface 10u. , and the part of the lower surface 10u other than the central groove 11 is covered with a doughnut-shaped cover plate 14. One end 32 of the intake pipe 30, which is immersed in liquid phase Pb and has the other end 31 connected to gas phase Pa, is placed in the central groove 11 of the lower surface 10u of the circular disk 10. At the same time, the driving device 25 rotates the circular disk 10 around the central axis to generate negative pressure in the central groove 11 of the lower surface 10u. By doing so, The negative pressure causes the gas G sucked in from one end 32 of the intake pipe 30 to mix with the liquid Q and flow into each radial groove 12 covered with the doughnut-shaped cover plate 14. Since the air bubbles S crushed in each radial groove 12 are released from the periphery of the circular disk 10, the following effects are achieved.

[0018] (i) Since the drive device 25 that rotates the circular disk 10 and the intake pipe 30 that takes in gas G from the gas phase P are separated, one end 32 of the intake pipe 30 that takes in gas G can be fixed even when the circular disk 10 is rotated by the drive device 25. (b) Therefore, even when the drive unit 25 is operating, the amount of gas G taken in can be finely adjusted by the intake volume adjustment valve 34 attached to one end 32 of the intake pipe 30, and the particle size and quantity (concentration) of the fine bubbles S can be adjusted by continuously switching the amount of gas G taken in while observing the generation status of the fine bubbles S.

[0019] (c) In addition, it has become easy to connect supply ports for various gases (oxygen, ozone, nitrogen, etc.) to one end 32 of the intake pipe 30, and fine bubbles S containing such gases can be generated by rotation of the circular disc 10, and the particle size and amount (concentration) of the fine bubbles S containing such gases can also be adjusted by the intake volume adjustment valve 34. (ii) Furthermore, the liquid Q and gas G are mixed in the central groove 11 of the circular disk 10 and then sucked into each radial groove 12, and the bubbles S are crushed by cavitation in the flow path extending over the entire length of each radial groove 12. Therefore, the entire length of each radial groove 12 can be utilized for the micronization of the bubbles, and it is expected that the particle size of the fine bubbles S released from the periphery of the disk 10 can be made finer and more uniform. [Brief description of the drawings]

[0020] Hereinafter, modes and embodiments for carrying out the present invention will be described with reference to the accompanying drawings. [Figure 1] FIG. 1 is an explanatory diagram of one embodiment of a microbubble generating device according to the present invention. [Diagram 2] FIG. 11 is an explanatory diagram of another embodiment of the micro-bubble generating device according to the present invention. [Diagram 3] 1 is an explanatory diagram of the principle of fine bubble generation in the fine bubble generating device according to the present invention. FIG. [Figure 4] FIG. 1 is an explanatory diagram of an example of a conventional microbubble generating device. [Diagram 5]FIG. 1 is an explanatory diagram of the principle of fine bubble generation in a conventional fine bubble generating device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] 1(A) shows an embodiment of the fine bubble generator 1 of the present invention applied to target water areas such as aquaculture ponds, hydroponic cultivation fields, etc. The generator 1 in the illustrated example includes a circular disk 10 having grooves 11, 12 on its lower surface 10u, a drive unit 25 that rotates the circular disk 10 around its central axis, and an intake pipe 30 having one end 32 facing the lower surface 10u of the circular disk 10 and the other end 31 that communicates with the gas phase Pa.

[0022] 1(A), a circular disk 10 is immersed almost horizontally in the liquid phase Pb of the target water area, and the circular disk 10 is rotated around a vertical central axis at a required rotational speed ω by a drive unit 25, whereby gas G sucked in from the gas phase Pa via an intake pipe 30 is crushed to generate fine bubbles S. The present invention will be described below with reference to the illustrated example, but the application of the present invention is not limited to aquaculture ponds, hydroponic cultivation fields, etc., and can be widely applied to the supply of fine bubbles S containing various gases G to a liquid Q.

[0023] FIG. 1(B) shows an enlarged cross-sectional view of a portion of the microbubble generator 1 in FIG. 1(A) including the circular disk 10 surrounded by the two-dot chain line B, and FIG. 1(C) and (D) show the upper surface 10t and the lower surface 10u of the circular disk 10 with a diameter R0. As shown in FIG. 1(D), the lower surface 10u of the circular disk 10 has a circular central groove 11 with a diameter R1 drilled in its center, and multiple radial grooves 12 from the central groove 11 to the periphery drilled at a required angular interval θ. In the illustrated example, the multiple radial grooves 12 have the same angular interval θ, but the angular interval θ of each radial groove 12 may be different. Since the circular disk 10 is immersed in the liquid phase Pb of the target water area, it is desirable for the circular disk 10 to be made of a material (e.g., metal or synthetic resin) that is not easily corroded even when immersed in liquid phase Pb for a long period of time.

[0024] The micro-bubble generator 1 in the illustrated example has a shaft 20 having one end fixed to the center of the upper surface 10t of the circular disk 10 and extending along the central axis, and a drive device (e.g., a motor) 25 is attached to the other end of the shaft 20. As shown in Fig. 1(B), for example, one end of the shaft 20 is passed through to the lower surface 10u of the circular disk 10, and the circular disk 10 is fixed to the shaft 20 by a retaining ring 21 provided on the lower surface 10u.

[0025] By including the shaft 20 as shown in the illustrated example in the fine bubble generator 1, when the circular disk 10 is immersed in liquid-phase Pb, the other end of the shaft 20 is exposed above the liquid surface, and the contact between the drive unit 25 attached to the other end of the shaft 20 and the liquid-phase Pb is avoided, thereby preventing the temperature rise of the liquid-phase Pb. However, the shaft 20 is not essential to the present invention, and when the temperature rise of the liquid-phase Pb is not an issue, the shaft 20 may be omitted and the drive unit 25 may be attached integrally to the circular disk 10 immersed in the liquid-phase Pb. The drive unit 25 may include a rotation speed adjustment means 26, and the particle size and amount of the fine bubbles S generated may be adjusted by the rotation speed ω of the circular disk 10. When used at sea or other places where it is difficult to connect to a power system, the drive unit 25 may include a storage battery, a solar power generator, etc.

[0026] The micro-bubble generator 1 in the illustrated example has a locking plate 22 supported by the gas phase Pa, and a drive unit 25 is installed on the locking plate 22. A shaft 20 is rotatably inserted through the locking plate 22, and the circular disk 10 is rotated around its central axis via the shaft 20 by the drive unit 25 on the locking plate 22, but the locking plate 22 can be left stationary. The locking plate 22 can be locked to a suitable member on the liquid surface, but if no suitable member exists, the locking plate 22 may be a floating plate that floats on the liquid surface. However, the locking plate 22 is not essential to the present invention and can be omitted.

[0027] The intake pipe 30 in the illustrated example has one end 32 submerged in liquid-phase Pb and facing the lower surface 10u of the circular disk 10, and the other end 31 supported by a locking plate 22 and connected to the gas phase Pa. The intake pipe 30 is also desirably made of a material (e.g., metal or synthetic resin) that is not easily corroded in liquid-phase Pb, and may be, for example, a tube made of relatively hard polyolefin resin. Since the inside of the intake pipe 30 becomes negative pressure when gas G is sucked in, if an excessively soft tube is used, the intake pipe 30 may be crushed in the inner diameter direction and become clogged when negative pressure is applied, so it is desirably made of a material that does not cause blockage even when negative pressure is applied. An intake amount adjustment valve 34 can be provided at the other end 31 of the intake pipe 30, and the particle size and amount of generation of the fine bubbles S can be adjusted by the intake amount of the intake pipe 30.

[0028] 1(E) shows the principle of generating micro-bubbles using the micro-bubble generator 1. When the circular disk 10 is horizontally immersed in the liquid phase Pb of the target water area and rotated around the central axis by the drive unit 25, the centrifugal force F of the rotation causes liquid Q to flow from the central groove 11 of the circular disk 10 into each radial groove 12, forming a liquid flow in each radial groove 12 that flows from the center to the periphery. This liquid flow generates negative pressure in the central groove 11 of the circular disk 10, and the liquid Q is replenished from the liquid phase Pb to the central groove 11 due to this negative pressure, and gas G is sucked in from one end 32 of the intake pipe 30 and mixed with the liquid Q.

[0029] 1(E), the liquid Q and gas G mixed in the central groove 11 of the circular disk 10 are crushed to a certain extent by cavitation in the central groove 11, and then flow from the central groove 11 into each radial groove 12 on the liquid flow formed by centrifugal force F. The liquid Q and gas G that flowed into each radial groove 12 are further crushed into small pieces by further cavitation in the flow path over the entire length of each radial groove 12, and are released as fine bubbles S from the periphery of the disk 10. In other words, the fine bubble generator 1 in FIG. 1 can efficiently generate fine bubbles S using only the rotational drive energy of a relatively small disk, similar to the conventional fine bubble generator 50 described above with reference to FIGS. 4 and 5.

[0030] On the other hand, in the conventional fine-bubble generator 50, the hollow rotating shaft pipe 70 was used not only as a flow path for taking in gas G into the disk 51 but also as the rotating shaft of the disk 51, so the position of the intake hole 71 of the pipe 70 fluctuated according to the rotation of the disk 51. In contrast, the fine-bubble generator 1 in Fig. 1 separates the drive unit 25 that rotates the circular disk 10 from the intake pipe 30 that takes in gas G from the gas phase P, so that the intake hole (one end of the intake pipe) 31 that takes in gas G can remain fixed even when the circular disk 10 is rotated by the drive unit 25, and an intake amount adjustment valve 34 is attached to the intake hole, so that the intake amount of gas G can be changed steplessly by the intake amount adjustment valve 34 while observing the generation state of fine bubbles S from the periphery of the disk 10.

[0031] In addition, the conventional fine-bubble generator 50 forms liquid flows that flow from the center to the periphery in each of the hollow pipes 60 arranged radially around the central gap 63 when the disk 51 rotates, but since the gas G is supplied to each of the hollow pipes 60 through the micro-through holes 56, rather than to the central gap 63, the flow path in which the gas G is crushed by cavitation is only a relatively short portion downstream of the micro-through holes 56 (see Fig. 5), and it has been experienced that the fine bubbles S released from the disk periphery contain bubbles with a relatively large diameter. In contrast, the fine-bubble generator 1 in Fig. 1 supplies the gas G to the central groove 11 of the circular disk 10 to mix with the liquid Q, and the gas G is crushed by cavitation in a relatively long flow path over the entire length of each radial groove 12, so that the particle size of the released fine bubbles S can be made finer and the particle size of the fine bubbles S can be made uniform.

[0032] In the illustrated example, the circular disk 10 in the liquid phase Pb is disposed nearly horizontally, but the arrangement of the circular disk 10 does not necessarily have to be horizontal. As described above, if a liquid flow can be formed from the central groove 11 toward each radial groove 12 when the circular disk 10 rotates, fine bubbles S can be generated, so the circular disk 10 can be tilted as necessary, or disposed nearly vertically.

[0033] Preferably, the radial grooves 12 on the lower surface 10u of the circular disk 10 are curved radial grooves 12a with the middle portion curved in the direction of rotation of the circular disk 10 as shown in Fig. 2(D) instead of the straight ones as shown in Fig. 1(D). Fig. 2(A) shows another embodiment of the fine-bubble generator 1 of the present invention. The fine-bubble generator 1 of Fig. 2 also includes a circular disk 10 with grooves 11, 12 drilled on the lower surface 10u, a drive unit 25 that rotates the circular disk 10 around the central axis, and an intake pipe 30 having one end 32 facing the lower surface 10u of the circular disk 10 and the other end 31 that communicates with the gas phase Pa.

[0034] Fig. 2(B) shows an enlarged cross-sectional view of a portion including the circular disk 10 of the micro-bubble generator 1 in Fig. 2(A), and Fig. 2(C) and (D) show the upper surface 10t and the lower surface 10u of the circular disk 10. The lower surface 10u of the circular disk 10 shown in Fig. 2(D) has a circular central groove 11 with a diameter R1 drilled in its center, and multiple curved radial grooves 12a drilled at a required angular interval θ from the central groove 11 to the periphery. In the illustrated example of Fig. 2, the multiple curved radial grooves 12a are also at equal angular intervals θ, but the angular intervals θ of each curved radial groove 12a may be different.

[0035] The curved radial grooves 12a have an intermediate portion curved in the direction of rotation of the circular disk 10, and can lengthen the flow path from the central groove 11 to the periphery compared to the straight radial grooves 12 in Fig. 1(D). It is expected that the gas G will be crushed by cavitation throughout the entire long flow path, thereby making the particle size of the fine bubbles S released from the periphery of the disk even finer and more uniform. The curved radial grooves 12a in the illustrated example are drilled to draw a circular arc, but the shape of the curved radial grooves 12a is not limited to the illustrated example. For example, the curved radial grooves 12a may be formed by drilling the intermediate portion of the straight radial grooves 12 as shown in Fig. 1(D) by bending it at a required angle once or more times in the opposite direction to the rotation direction.

[0036] Moreover, while the linear radial grooves 12 in FIG. 1(D) disperse the fine bubbles S emitted from the periphery of the circular disk 10 over a wide 360-degree radial range, the curved radial grooves 12a as in FIG. 2(D) can emit the fine bubbles S in a direction along the periphery of the circular disk 10, and can prevent the emitted fine bubbles S from dispersing (see also FIG. 3(B)). For example, when installing the fine bubble generator 1 in an aquarium, it may be necessary to concentrate the emission of the fine bubbles S in a direction where there is no wall of the aquarium. By emitting the fine bubbles S in a direction along the periphery of the circular disk 10, the fine bubbles S can be easily guided in a specific direction using, for example, a protective cover 40 (see FIG. 2(F)) described later, and it becomes easy to focus the emission of the fine bubbles S in the required direction.

[0037] More preferably, as shown in FIG. 2(B), a doughnut-shaped cover plate 14 is provided to cover the portion of the lower surface 10u of the circular disk 10 other than the central groove 11. FIG. 2(E) shows a front view of the doughnut-shaped cover plate 14 as seen from below. By covering each curved radial groove 12a of the lower surface 10u with the doughnut-shaped cover plate 14, each curved radial groove 12a extending from the central groove 11 can be made into a cylindrical (culvert-like) pipe surrounded by the cover plate 14, and all the generated fine bubbles S can be released from the periphery of the circular disk 10 while avoiding wasteful leakage of the fine bubbles S into the liquid phase Pb from the middle of the flow path of each curved radial groove 12a. The reference numeral 15 in the figure indicates a screw for joining the circular disk 10 and the doughnut-shaped cover plate 14 by aligning the centers of them, but the circular disk 10 and the doughnut-shaped cover plate 14 may be joined by an adhesive or the like. In addition, in the micro-bubble generating device 1 of FIG. 1 as well, it is effective to provide a donut-shaped cover plate 14 that covers the portion of the lower surface 10u of the circular disk 10 other than the central groove 11.

[0038] 2 also has a locking plate 22 supported by the gas phase Pa, a mounting base 27 for the drive unit 25 is provided on the locking plate 22, and the drive unit 25 is mounted on the mounting base 27. One end 32 of the intake pipe 30 is submerged in the liquid phase Pb and faces the lower surface 10u of the circular disk 10, and the other end 31 of the intake pipe 30 is supported by the locking plate 22 and is attached to the mounting base 27 for the drive unit 25. By connecting the intake pipe 30 and the mounting base 25 for the drive unit 25 in this way, the entire fine bubble generator 1 including both can be made into a compact shape.

[0039] Fig. 3 shows the principle of generating fine bubbles using the fine bubble generator 1 of Fig. 2. As shown in Fig. 3(A), when a circular disk 10 is horizontally immersed in the liquid phase Pb of the target water area and the circular disk 10 is rotated around the central axis by a driving device 25, the centrifugal force F of the rotation causes liquid Q to flow from the central groove 11 of the circular disk 10 into each curved radial groove 12a covered with a donut-shaped cover plate 14, and a liquid flow that flows from the center to the outer periphery is formed in each curved radial groove 12a. This liquid flow generates negative pressure in the central groove 11 of the circular disk 10, and the liquid Q is replenished from the liquid phase Pb to the central groove 11 by this negative pressure, and gas G is sucked in from one end 32 of the intake pipe 30 and mixed with the liquid Q.

[0040] 3(B), the liquid Q and gas G mixed in the central groove 11 of the circular disk 10 are crushed to a certain extent by cavitation in the central groove 11, and then carried by the liquid flow formed by centrifugal force F from the central groove 11 into each curved radial groove 12a covered with a doughnut-shaped cover plate 14. The liquid Q and gas G that have flowed into each curved radial groove 12a are further crushed into fine bubbles S by further cavitation in the flow path over the entire length of each radial groove 12, generating fine bubbles S, and all of the generated fine bubbles S are released as fine bubbles S from the periphery of the disk 10.

[0041] 3(B), the curved radial grooves 12a emit the fine bubbles S in a direction along the periphery of the circular disk 10, so that the emitted fine bubbles S can flow along the periphery of the circular disk 10. Therefore, by providing a protective cover 40 that covers the outside of the circular disk 10, the fine bubbles S can be guided and emitted in a specific direction from an outlet 41 provided in a part of the protective cover 40, and the fine bubbles S can be emitted in a focused direction while preventing the fine bubbles S from dissipating.

[0042] In this way, the object of the present invention can be achieved by providing a "micro-bubble generating device capable of fixing the gas intake position when generating micro-bubbles."

[0043] In the embodiment of Figures 1 and 2, one end 32 of the intake pipe 30 is connected to the gas phase Pa via the intake volume adjustment valve 34, but one end 32 of the intake pipe 30 can be connected to a supply port of various gases (oxygen, ozone, nitrogen, etc.), and based on the principle of generation of fine bubbles S as shown in Figure 3, fine bubbles S containing such gases can be generated and supplied by rotation of the circular disc 10. EXAMPLES

[0044] 2(F) shows an embodiment of a protective cover 40 that covers the circular disk 10 and the shaft 20. The protective cover 40 in the illustrated example has a shape that combines a cylindrical protective cover that covers the outside of the shaft 20 with a disk-shaped protective cover that covers the outside of the circular disk 10, and has a bottom hole 43 in a portion facing the central groove 11 of the bottom surface 10u of the circular disk 10, and a discharge port 41 that guides and discharges the discharge flow from the outer periphery of the circular disk 10 in a specific direction.

[0045] 2(A), the upper end of the protective cover 40 in the illustrated example can be supported by the locking plate 22 and is isolated from the rotation of the drive device 25. In other words, even when the circular disk 10 is rotated around the central axis by the drive device 25 via the shaft 20, the locking plate 22 and the protective cover 40 can be left stationary.

[0046] Furthermore, the protective cover 40 in the illustrated example has a pair of insertion openings 42a, 42b through which the intake pipe 30 is inserted, and one end 32 of the intake pipe 30 supported on the locking plate 22 is inserted through the insertion openings 42a, 42b of the protective cover 40 and faces the underside 10u of the circular disk 10. By arranging the intake pipe 30 by inserting it through the protective cover 40 in this manner, it becomes easier to arrange the intake pipe 30 along the outer surface of the protective cover 40 and to position the one end 32 of the intake pipe 30 in an appropriate position facing the underside 10u of the circular disk 10, and the entire fine bubble generator 1 including both the protective cover 40 and the intake pipe 30 can be made into a compact shape. [Explanation of symbols]

[0047] 1. Microbubble generator 10...Circular disk 10t...(Circular disk) top surface 10u...(Circular disc) bottom surface 11...Central groove 12...Radial groove 12a...Curved radial groove 14...Donut-shaped cover plate 15...Screw 20...Shaft 21...Retaining ring (cap nut) 22...Lock plate (or floating plate) 25... Drive device 26... Drive speed adjustment means 27…Installation stand 30... Intake pipe 31... Intake hole (at the other end of the intake pipe) 32... Exhaust hole (at one end of the intake pipe) 34... Intake amount adjustment valve 40: Protective cover 41: Air bubble outlet 42a, 42b... Tube insertion port 50...Microbubble generator 51... disk 52... substrate 53... Substrate 54... Periphery seal material 55...Airtight chamber 56...Minute through hole 60...Hollow pipeline (hollow pipe) 60a...Pipe outlet 61... Donut plate 62... (Doughnut plate) central hole 63…Central void 70... Hollow rotating shaft pipe 71... Intake hole 72... Intake volume adjustment valve 73... Exhaust hole 76, 77...Ring-shaped retainer (retaining boss) 80... Drive device 81... Drive shaft 82... Coupling 83... Rotational speed adjusting means Pa: Gas phase Pb: Liquid phase S: Fine bubbles L: Length of hollow pipe G…Gas Q…Liquid R0…Disc diameter R1…Central groove diameter (diameter of central hole 62) θ…Mutual angular spacing ω…Rotation speed

Claims

1. A fine bubble generator comprising: a circular disk having a central groove in the center and a plurality of radial grooves extending from the central groove to the periphery on its underside and immersed in a liquid phase; a donut-shaped cover plate covering the entire underside of the circular disk except for the central groove; a drive unit for rotating the circular disk around its central axis; and an intake pipe having one end facing the central groove on the underside of the circular disk and the other end communicating with the gas phase, wherein negative pressure is generated in the central groove by the rotation of the circular disk by the drive unit, and gas sucked in from one end of the intake pipe is mixed with liquid by the negative pressure and flows into each of the radial grooves covered by the donut-shaped cover plate, and the bubbles crushed in each radial groove are released from the periphery of the circular disk.

2. 2. The microbubble generating device according to claim 1, wherein each of the plurality of radial grooves of the circular disk is a curved radial groove whose intermediate portion is curved in the direction of rotation of the circular disk.

3. 3. The fine bubble generating device according to claim 1, further comprising an intake amount adjusting valve provided at the other end of said intake pipe.

4. 4. The fine bubble generating device according to claim 1, further comprising a shaft extending along the central axis of the upper surface of the circular disk to the gas phase, and the driving device attached to the other end of the shaft.

5. 5. A micro-bubble generating device according to claim 4, further comprising a protective cover which covers the circular disk and shaft, has a bottom hole facing a central groove on the bottom surface of the circular disk, and has an outlet port for discharging the discharge flow from the outer periphery of the circular disk, and is isolated from the rotation of the drive unit, and an intake pipe is arranged along the outer surface of the protective cover.

6. 6. The fine bubble generating device according to claim 1, further comprising a gas generating device for generating oxygen, ozone, nitrogen or other gas, connected to the other end of said intake pipe.

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