JP2008307509A - Apparatus for generating microbubble - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for generating microbubbles, which allow an improvement in white turbidity by drastically increasing the amount of microbubbles to be generated, by a simple constitution. <P>SOLUTION: The apparatus for generating microbubbles is characterized in that an air-dissolved aqueous fluid with air dissolved under pressure, in the water, is discharged from a discharge nozzle 30 by releasing the pressure of the air-dissolved aqueous fluid by a decompression means 12 while generating microbubbles. The discharge nozzle 30 is provided with a downstream venturi tube 12b as the decompression means. The downstream venturi tube 12b has a tapered part being a diameter-expanded part whose diameter is made larger gradually as it goes to the downstream side. The expanded angle of the tapered part is formed to have 4-6°. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fine bubble generating apparatus that is most suitable for a watering facility.

Conventionally, fine air bubbles were released from a discharge nozzle into a bathtub (an example of a watering facility) by releasing the pressure of a gas-water dissolved fluid in which air was pressurized and dissolved in water using decompression means, and generating fine bubbles. There exists a generator (refer patent document 1).
JP-A-11-33071

  When the fine bubble generator as described above is applied to a bathtub that is a watering facility, it is necessary to install the fine bubble generator in a narrow space such as a gap between the bathtub and the apron. There is a desire to greatly increase the amount of microbubbles generated with a simple configuration without using a route.

  The present invention has been made to meet the above-mentioned demand, and an object of the present invention is to provide a microbubble generator capable of improving the cloudiness by greatly increasing the amount of microbubbles generated with a simple configuration. It is what.

  In order to solve the above-mentioned problems, the present invention is a microbubble generator that discharges from a discharge nozzle while releasing a pressure of a gas-water-dissolved fluid in which air is pressurized and dissolved in water by a decompression means to generate microbubbles. The discharge nozzle is provided with a venturi pipe that constitutes a decompression means, and on the downstream side of the venturi pipe, there is provided an enlarged diameter portion that gradually increases in diameter toward the downstream side. The fine bubble generator is characterized in that the spread angle is more than 0 ° and less than 10 °.

  As described in claim 2, the divergence angle is preferably 4 ° or more and 6 ° or less.

  According to the first aspect of the present invention, since the divergence angle of the expanded portion of the venturi tube is formed so as to be more than 0 ° and not more than 10 °, the expanded portion of the venturi tube is combined with the gas-water dissolving fluid. When the bubbles flow, the bubbles can be generated by breaking the pressure by releasing the pressure, and a part of the gas-water dissolving fluid can be prevented from causing a vortex in the vicinity of the inner peripheral wall of the enlarged diameter portion. Thereby, for example, it is possible to prevent the vortex generated in the vicinity of the inner peripheral wall of the enlarged diameter portion from gathering and coalescing at the center of the vortex of the generated split bubbles. . Therefore, the generated splitting bubbles can be taken out of the venturi as they are without being united.

  According to the second aspect of the present invention, since the divergence angle is set to 4 ° to 6 °, the generation of the vortex flow of the air-water dissolving fluid in the vicinity of the inner peripheral wall of the expanded diameter portion can be prevented more reliably. It is possible to more surely prevent coalescence of split bubbles.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a basic configuration diagram of a microbubble generator according to an embodiment of the present invention. In this embodiment, the microbubble generator is used for a bathtub 1 and is configured to generate microbubbles in bath water in the bathtub 1. The suction port 2 and the discharge port 3 are provided on the inner surface of the bathtub 1, and the air suction port 4 is provided on the flange portion of the bathtub 1.

  The suction port 2 is connected to the suction side of the electric pump 6 through the connection pipe 5, and the discharge side of the electric pump 6 is connected to the injection port 9 on the suction side of the air dissolving device 8 through the inflow pipe 7. . The outlet 10 on the discharge side of the air dissolving device 8 is connected to one end of a venturi pipe 12 serving as a pressure release portion via an outflow pipe 11, and the other end of the venturi pipe 12 is connected to the side surface of the bathtub 1 via a connection pipe 13. Is connected to the discharge port 3 installed in the. The air suction port 4 is connected to a connection pipe 5 near the inlet side of the electric pump 6 via a connection pipe 14, and a check valve 15 is provided in the connection pipe 14.

  As shown in detail in FIG. 2 and FIG. 3, the air dissolving device 8 includes a side wall portion 21 having a straight cylindrical shape with a circular cross section, and end wall portions 22 that close both ends of the side wall portion 21. The center axis A (see the one-dot chain line in FIG. 2) of the side wall portion 21 which is configured by the tank-like cylindrical body 23 and has a substantially cylindrical shape is 10 in the horizontal direction (see the arrow in FIG. 2). It arrange | positions with the attitude | position which inclines with the inclination-angle (theta) of -45 degree | times.

  The cylindrical body 23 in the inclined posture has an upper end serving as an upstream A end, and a lower end serving as a downstream B end. An injection port 9 for injecting into the cylindrical body 23 is formed, and an outflow port 10 through which water flows out from the cylindrical body 23 is formed on the downstream side B.

  In the cylindrical body 23, air such as air serving as a solute and water such as water serving as a solvent are stored, and air is disposed in the vicinity of the substantially center of the substantially cylindrical side wall portion 21 in the vertical direction. The interface 24 with water is located, and the portion on the upstream side A above the interface 24 becomes an air storage portion 25 in which air is stored, and the portion on the downstream side B from the interface 24 is water in which water is stored. It becomes the storage part 26.

  The injection port 9 is located on the inner wall surface of the air reservoir 25 (the inner wall surface 21 on the upstream side A or the inner wall surface of the end wall portion 22 from the interface 24), at a position near the interface 24, or slightly below the interface 24. The water outlet 26 is formed on the inner wall surface (inner wall surface of the side wall 21 on the downstream side B from the interface 24), and the outlet 10 is connected to the inner wall surface near the end of the water reservoir 26 (on the downstream side B from the interface 24. The inner wall surface of the side wall portion 21 or the end wall portion 22 is formed.

  An air vent 27 provided with a valve (not shown) is formed in the side wall 21 of the cylindrical body 23, and the air and water reservoir 26 is stored in the air reservoir 25 at the position of the air vent 27. It becomes the level of the interface 24 of the water stored.

  Next, the operation of the air dissolving device 8 will be described. When the same water and air stored in the cylindrical body 23 are injected from the injection port 9, they collide with the inner wall surface on the upper side of the side wall portion 21 facing the injection port 9 and bounce off the inner wall surface. The water collides with the water stored in the water storage section 26 at the interface 24 and is agitated. Further, the water stored in the water storage unit 26 is not only stirred by the air / water mixed fluid colliding with the interface 24 but also by the air / water mixed fluid injected into the cylindrical body 23 from the injection port 9. Stir.

  As described above, the air stored in the cylindrical body 23 and the like by the agitation due to the collision with the inner wall surface of the side wall portion 21 of the air-water mixed fluid or the collision at the interface 24, the agitation of water when jetted, and the like Water, air in the air-water mixed fluid, and water are mixed, and dissolution of air into water is promoted. That is, due to shearing by mixing and stirring, bubbles (air) mixed with water are subdivided and the total surface area in contact with water increases, and the dissolved concentration of air near the interface between water and air increases. Since it is reduced by homogenization by mixing and stirring and the dissolution rate of air in water increases, dissolution of air in water is promoted.

  The water in which the dissolution of the air has progressed is stored in the water storage section 26 of the cylindrical body 23, but many undissolved bubbles are mixed in the stored water, and these bubbles become denser as they go upward. There are few bubbles near the lower end of the water reservoir 26, and there are almost no large bubbles. Then, dissolution of the air proceeds and water at the lower end of the water storage part 26 where there are almost no large bubbles flows out of the cylindrical body 23 from the outlet 10.

  FIG. 4 is a basic configuration diagram of the venturi tube 12. The venturi pipe 12 of the outflow pipe 11 has a two-stage configuration including one upstream venturi pipe 12a in the center and a plurality (five in the example of FIG. 4) downstream venturi pipes 12b.

  5 and 6 are microbubble generators embodying the basic configuration shown in FIGS. 1 to 4. The same configuration as the basic configuration is given the same number, and the detailed description is omitted.

  A discharge nozzle 30 is attached to the side wall 1 a of the bathtub 1, and the above-described suction port 2, discharge port 3, venturi pipe 12 (12 a, 12 b) and the like are incorporated into the discharge nozzle 30 as a unit.

  The discharge nozzle 30 is provided with an L-shaped nozzle case 31 in a side view, and an L-shaped flow path 31a following the outer shape is formed inside the nozzle case 31. The outflow pipe 11 is connected to the inlet side (vertical portion) via an O-ring 32.

  In this embodiment, the flow channel 31a includes a bubble generation (foaming) flow channel region 131, a bubble splitting flow channel region 133 disposed on the downstream side of the bubble generation flow channel region 131, and the bubble splitting. And a vaporization channel region part 132 disposed on the downstream side of the channel region part 133.

  The bubble generation flow channel region 131 is a flow channel for generating bubbles from the gas-water dissolved fluid. The bubble generation flow path region 131 of this embodiment is provided with an upstream venturi pipe 12a as a decompression means, and from an upstream end of the upstream venturi pipe 12a to a downstream venturi pipe 12b described later. Formed in the region.

  The upstream side venturi pipe 12a is fitted in the upper part of the nozzle case 31, and is provided vertically in FIG. 6 on the inlet side of the bubble generation flow path region 131.

  The bubble generation flow channel region 131 is provided with a current generation means. The current generation means is for causing a vortex or a swirl flow in part or all of the gas-water dissolving fluid flowing through the upstream side venturi tube 12a. The current transformation generating means of this embodiment is constituted by an edge 12c for generating vortex flow provided in the upstream side venturi tube 12a, and causes vortex flow in a part of the gas-water dissolved fluid flowing in the upstream side venturi tube 12a. It has become.

  As shown in FIG. 7, the eddy current generating edge 12c is provided on the inner peripheral wall of the upstream venturi tube 12a so as to protrude radially inward (inner peripheral side) along the entire circumference. Yes.

  Further, the upstream front surface 12d of the eddy current generating edge 12c is inclined downstream at a predetermined angle with respect to a plane orthogonal to the axial direction of the upstream venturi tube 12a from the base end 12f to the protruding tip 12g. It is configured as follows. Further, the downstream rear surface 12e is configured to incline upstream from the base end 12h to the protruding tip 12g with a predetermined angle with respect to a plane perpendicular to the axial direction of the upstream venturi tube 12a.

  Returning to FIG. 6, the bubble splitting channel region part 133 is a channel that splits the bubbles generated in the bubble generating channel region part 131 to generate split bubbles. The bubble splitting channel region portion 133 of this embodiment is provided with a downstream venturi tube 12b as decompression means, and the entire channel formed inside the downstream venturi tube 12b, that is, the channel It is formed in a region extending from the upstream end to the downstream end.

  In this embodiment, the downstream side venturi pipe 12b is composed of a plurality of pipes formed in the nozzle body 29. Then, when the nozzle body 29 is fitted in the middle of the nozzle case 31 via the O-ring 33, the downstream venturi pipe 12b is disposed laterally in FIG. 6 on the downstream side of the upstream venturi pipe 12a. ing.

  Specifically, as shown in FIGS. 6 and 11, the nozzle body 29 includes a cylindrical fitting portion 29 a for fitting into the outlet side (laterally facing portion) portion of the nozzle case 31 via an O-ring 33, and A cylindrical projecting portion 29b projecting downstream (discharging direction) from the fitting portion 29a and a plate-like closing portion 29c are formed between the cylindrical protruding portion 29b and the fitting portion 29a. Two inner and outer concentric circles are set, and a plurality of (six in this example) downstream venturi tubes 12b are formed along the inner small-diameter circle at equal angular intervals on the circumference. A plurality of (10 in this example) downstream venturi pipes 12b are formed at equal angular intervals on the circumference (a total of 16 downstream venturi pipes 12b in this example). The plurality of venturi tubes 12b can be referred to as a venturi tube group.

  Further, as shown in FIG. 9, each of these downstream venturi pipes 12b has an upstream inlet portion formed in an outward trumpet shape, and a shortest and smallest straight portion 121 formed immediately downstream thereof. On the downstream side, a taper portion 122 is formed as a long expanded portion whose diameter is increased from the upstream side toward the downstream side.

  Further, the taper portion 122 has a spread angle θ (twice the taper angle formed by the inner peripheral wall 122a of the taper portion 122 and the axis of the downstream venturi tube 12b) exceeding 0 ° and not more than 10 °. (The taper angle is more than 0 ° and not more than 5 °).

  When the divergence angle θ is 0 °, the bubbles flowing from the straight portion 121 cannot be split by releasing the pressure. In addition, when the spread angle θ is 10 ° or more, a part of the gas-water dissolving fluid tends to cause vortex near the inner wall surface of the tapered portion 122.

  Specifically, for example, as shown in FIG. 10 (a), in the venturi tube 130 having a divergence angle θ of 10 ° or more (in FIG. 10 (a), an example in which the divergence angle θ is approximately 14 °) is shown. A part of the gas-water dissolving fluid generates a vortex 132 near the inner wall surface 130a on the downstream side of the tapered portion 130a, and the force generated by the generation of the vortex flows, as shown in FIG. This is because the split bubbles 100b having a small specific gravity gather at the center of the vortex flow 132, and a plurality of them merge to generate a coalesced bubble 101.

  More preferably, the spread angle θ is not less than 4 ° and not more than 6 ° (in the above taper angle, not less than 2 ° and not more than 3 °). Thereby, it is easy to generate the split bubbles, and further, the generation of the vortex flow of the air-water dissolved fluid in the vicinity of the inner wall surface 122a on the downstream side of the tapered portion 122 can be prevented, and the coalescence of the split bubbles can be prevented.

  Further, in this embodiment, as shown in FIG. 9, the upstream side surface 110 a in the burr 110 that is generated to protrude toward the inner peripheral side is formed downstream of the inner side of the downstream venturi tube 12 b by the burr shaping processing unit. The other side surface 110b on the downstream side of the burr 110 is shaped into an inclined surface inclined to the upstream side. The details are as follows.

  If there is a protrusion such as a burr on the inner peripheral side of the downstream venturi pipe 12b, it is preferable that there is no resistance when the air-water dissolved fluid flows, but at the time of molding, as shown in FIG. The burr 110 is easily formed.

  Therefore, in this embodiment, a shaping part that presses and shapes one side 110a on the upstream side of the burr 110 to an inclined surface that is inclined to the downstream side, and another downstream side of the burr 110 in the molding die as the burr shaping unit. The side surface 110b is provided with a shaping portion that presses and shapes the inclined surface inclined to the upstream side. When forming the downstream side venturi tube 12b, as shown in FIG. 9, the inner circumference straight of the downstream side venturi tube 12b is provided. In the portion 121, the upstream side surface 110a of the burr 110 protruding and generated on the inner peripheral side is inclined to the downstream side, and the downstream side surface 110b of the burr 110 is inclined to the upstream side. Formatting process.

  In this way, the frictional resistance when the gas-water dissolved fluid flows is reduced. Further, a vortex is caused by the burr 110. Note that the burr shaping processing means is not limited to one constituted by a molding die, and may be performed by cutting or the like, for example.

  Further, in this embodiment, when the protrusion height from the inner peripheral wall of the downstream venturi tube 12b in the burr 110 is h, the maximum thickness t from the upstream end 110c to the downstream end 110d in the burr 110 is set. H / t is preferably in the range of 0.12 to 0.13 in that the frictional resistance can be further reduced, and more preferably about 0.125.

  Next, the vaporization channel region 132 will be described. The vaporization flow channel region 132 is a flow channel for growing the split bubbles (increasing the diameter) to form fine bubbles having an outer diameter necessary and sufficient for white turbidity.

  The vaporization channel region portion 132 of this embodiment is formed on the downstream side of the downstream venturi tube 12b in the nozzle body 29 (left side portion in FIG. 6). Further, the vaporization flow path region portion 132 promotes vaporization of dissolved air dissolved in the gas-water dissolution fluid by the vaporization promoting means, and the split bubbles flow through the vaporization flow passage region portion 132 together with the gas-water dissolution fluid. In the meantime, fine bubbles having an outer diameter necessary and sufficient for whitening can be formed.

  In this embodiment, the vaporization promoting means is a channel narrowing member in which the channel cross-sectional area at the downstream end of the vaporization channel region 132 is made smaller than the upstream channel cross-sectional area to narrow the channel. Compared to the case where the flow path narrowing member 38 is not provided, this flow path narrowing member 38 slows down the flow rate of the gas-water dissolving fluid flowing through the vaporization flow path region 132, and The time during which the water-dissolving fluid flows through the vaporization channel region 132 is lengthened.

  Specifically, a cylindrical holder 37 that extends downstream (in the discharge direction) is disposed at the discharge side end of the nozzle body 29, and the male screw 29 d at the front end of the protrusion 29 b of the nozzle body 29 is connected to the female screw of the holder 37. 37a is attached by screwing, and a flow path narrowing member 38 is provided on the inner peripheral side of the holder 37.

  As shown in FIGS. 6 and 12, the channel narrowing member 38 of this embodiment includes a closing portion 38a disposed so as to be substantially orthogonal to the axis of the holder 37, and four openings formed in the closing portion 38a. And an opening 38b. The flow path narrowing member 38 configured in this manner allows the flow path cross-sectional area of the downstream end portion of the vaporization flow path region portion 132 formed inside the nozzle body 29 to be the entire flow path narrowing member 38. This corresponds to the cross-sectional area of the opening 38 b, and the downstream end of the vaporization channel region 132 is narrower than other portions of the vaporization channel region 132.

  The channel cross-sectional area of the discharge side end in the vaporization channel region 132 is not particularly limited and can be changed as appropriate. It is preferable to be in the range of about 60 to about 90% with respect to the area, more preferably about 75%.

  Continuing the description of the discharge nozzle 30, a packing 40 having a U-shaped cross section is fitted into the mounting hole 1 b of the side wall 1 a of the bathtub 1, and the outlet side (sideways portion) of the nozzle case 31 from the outside of the bathtub 1. The flange portion 31b is applied to the packing 40, and the male screw 41a at the rear end portion of the cylindrical fixing flange 41 is screwed into the female screw 31c of the flange portion 31b of the nozzle case 31 from the inside of the bathtub 1 to thereby fix the fixing flange 41. The flange portion 41 b at the front end portion is in watertight contact with the packing 40, and the flange portion 31 b of the nozzle case 31 is in watertight contact with the packing 40. As a result, the nozzle case 31 is fixedly attached to the side wall 1 a of the bathtub 1 with the fixing flange 41.

  The nozzle cover 42 is attached to the flange portion 41 b of the fixed flange 41 by screwing the female screw 42 a at the rear end portion of the cylindrical nozzle cover 42 into the male screw 41 c of the flange portion 41 b of the fixed flange 41 from the inside of the bathtub 1. become. The nozzle cover 42 has the discharge port 3 formed therein.

  As shown in FIGS. 13 (a) and 13 (b), the fixing flange 41 is formed with a plate-like closing portion 41d that closes the outer peripheral surface of the holder 37. Concentric circles are set, a large number of through holes 41e are formed at equal circumferential intervals along the inner small-diameter circle, and half pitches are formed along the outer large-diameter circle with the inner small-diameter through-holes 41e. In a shifted state, a large number of through holes 41e are formed at equal angular intervals on the circumference. Water-tightness can be improved by interposing a packing (not shown) between the inner peripheral surface of the closing portion 41 d and the outer peripheral surface of the holder 37.

  On the outer peripheral surface of the nozzle cover 42, as shown in FIG. 6, a plurality of the suction ports 2 are formed at equal angular intervals on the circumference.

  In the case of the discharge nozzle 30 configured as described above, as shown in FIG. 6, hot water as an air-water dissolving fluid in which air is dissolved is upstream of the nozzle case 31 from the outflow pipe 11 as indicated by an arrow a. Enter the venturi tube 12a. When passing through the upstream venturi tube 12a, the hot water is depressurized by the upstream venturi tube 12a, and bubbles 100a are generated from the hot water. Further, as shown in FIG. 8, a part of the hot water generates a vortex by the edge 12c for generating the vortex, and bubbles 100a are generated from the hot water by the low-pressure portion formed by the generation of the vortex.

  Accordingly, bubbles can be generated by both the pressure reduction by the upstream side venturi tube 12a and the edge 12c for generating the eddy current, and the upstream side venturi tube can be generated as compared with the case where the bubbles are generated only by the pressure reduction of the upstream side venturi tube 12a. A larger amount of bubbles can be generated in the bubble generation flow channel region 131 formed in the region from the upstream end of the tube 12a to the downstream venturi tube 12b.

  Thereafter, the hot water containing the generated bubbles 100a enters the downstream venturi tube 12b as shown in FIGS. 6 and 9, and the bubbles 100a are further broken by the pressure release at the tapered portion 122 of the downstream venturi tube 12b. Thus, a split bubble 100b is generated.

  At that time, even when the burr 110 is generated on the inner circumference of the downstream venturi pipe 12b, the burr shaping means makes the upstream side surface 110a of the burr 110 inclined to the downstream side. Since the downstream side surface 110b on the downstream side of the burr 110 is shaped into an inclined surface inclined upstream, the hot water can flow smoothly without receiving a large frictional resistance.

  Moreover, since the spread angle θ of the tapered portion 122 is formed to be greater than 0 ° and equal to or less than 10 °, the generation of vortex flow of hot water near the inner wall surface 122a on the downstream side of the tapered portion 122 is prevented. Thus, coalescence of the split bubbles 100b can be prevented. Therefore, the fissured bubble 100b leaves the downstream venturi tube 12b as it is.

  Next, the hot water including the split bubbles 100 b exiting the downstream venturi tube 12 b enters the vaporization flow path region 132. Since the downstream end of the vaporization channel region 132 is narrower than its upstream side, the hot water that has entered the vaporization channel region 132 together with the split bubbles 100b promotes the vaporization of air from the hot water. Slowly washed away. As a result, the split bubbles 100b grow (become large) and can be formed into fine bubbles 100c having an outer diameter necessary and sufficient for white turbidity.

  Therefore, the hot and cold water containing the fine bubbles 100c is sufficiently clouded. And the hot water containing the fine bubble 100c is discharged to the bathtub 1 from the discharge outlet 3 in this state.

  Also, the bath water in the bathtub 1 is sucked into the nozzle cover 42 from the suction port 2 of the nozzle cover 42 as shown by an arrow b shown in FIG. As shown in FIG. 5, the electric pump 6 is sucked from the connection pipe 5 connected to the outer side of the nozzle case 31.

  In the above embodiment, the water supply equipment is for a bathtub that injects fine bubbles for white turbidity, but the present invention can also be applied to a flush toilet that injects fine bubbles for bowl cleaning. Of course.

It is a basic lineblock diagram of the fine bubble generating device concerning the embodiment of the present invention. It is a perspective view of the air dissolving apparatus of FIG. 1. It is the air dissolving apparatus of FIG. 1, (a) is sectional drawing, (b) is the II sectional view taken on the line of (a). It is sectional drawing of the venturi pipe | tube of FIG. It is the perspective view which actualized the bath fine bubble generator provided with the air dissolving device concerning the embodiment of the present invention. It is sectional drawing of the discharge nozzle which has a venturi pipe. It is a top view of an upstream side venturi pipe. It is explanatory drawing when a vortex | eddy_current is produced | generated by the edge for eddy current production | generation. It is a principal part expanded sectional view of a downstream venturi pipe. It is the venturi pipe as a comparative example, (a) is the principal part expanded sectional view, (b) is explanatory drawing when a venturi pipe | tube produces | generates a vortex | eddy_current and a split bubble is united by the vortex | eddy_current. It is the perspective view which assembled the nozzle main body and the holder. It is a front view of a holder. It is a fixed flange, (a) is a front view, (b) is a sectional view.

Explanation of symbols

1 Bathtub 2 Suction port 3 Discharge port 8 Air dissolving device 12a Upstream venturi pipe (pressure reduction means)
12b Venturi pipe on the downstream side (pressure reduction means)
12c Edge for eddy current generation (current generation means)
30 Discharge nozzle 37 Holder 38 Channel narrowing member (vaporization promoting means)

Claims (2)

A micro-bubble generating device that discharges air and water-dissolved fluid, in which air is pressurized and dissolved in water, with a decompression unit and discharges from a discharge nozzle while generating micro-bubbles,
The discharge nozzle is provided with a venturi pipe that constitutes a decompression means, and on the downstream side of the venturi pipe, a diameter-expanded portion that gradually increases toward the downstream side is provided,
The expanded diameter portion is formed so that a spread angle thereof exceeds 0 ° and is equal to or less than 10 °.   2. The microbubble generator according to claim 1, wherein the divergence angle is 4 [deg.] Or more and 6 [deg.] Or less.

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