Microbubble generator

Abstract

To provide a technology which can generate a larger number of fine air bubbles in a fine air bubble generation device.SOLUTION: A fine air bubble generation device comprises a flow-in part, a flow-out part, a first fine air bubble generation part and a second fine air bubble generation part. The first fine air bubble generation part comprises a reduced-diameter flow passage and an increased-diameter flow passage. The second fine air bubble generation part comprises a first swirl flow generation part and a second swirl flow generation part. The first swirl flow generation part comprises a first outer peripheral part and a plurality of first blade parts for generating a first swirl flow flowing in a first swirl direction with respect to a center axis of the second fine air bubble generation part. The second swirl flow generation part comprises a second outer peripheral part and a plurality of second blade parts for generating a second swirl flow flowing in a second swirl direction which is opposite to the first swirl direction with respect to the center axis.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The technology disclosed in this specification relates to a microbubble generator.

Background Art

[0002] Patent Document 1 discloses a microbubble generator including an inflow section into which gas-dissolved water flows, an outflow section from which the gas-dissolved water flows out, and a microbubble generation section provided between the inflow section and the outflow section. The microbubble generation section includes a reduced-diameter flow path whose flow path diameter decreases from upstream to downstream, and an enlarged-diameter flow path provided downstream of the reduced-diameter flow path and having a flow path diameter that increases from upstream to downstream.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the microbubble generator of Patent Document 1, water in which gas is dissolved (hereinafter sometimes referred to as "gas-dissolved water") flows into the reduced-diameter flow path of the microbubble generation section via the inflow section. The gas-dissolved water passes through the reduced-diameter flow path, whereby the flow velocity increases and as a result, the pressure is reduced. When the gas-dissolved water is depressurized, bubbles are generated. Next, the gas-dissolved water passes through the enlarged-diameter flow path and is gradually pressurized. When the gas-dissolved water after bubbles are generated by depressurization is pressurized, the bubbles contained in the gas-dissolved water split into microbubbles. Thus, in the microbubble generator of Patent Document 1, microbubbles are generated by the microbubble generation section. However, in the microbubble generator of Patent Document 1, a situation occurs in which the amount of microbubbles generated by the microbubble generator is insufficient.

[0005] This specification provides a technique capable of generating a large amount of microbubbles.

Means for Solving the Problems

[0006] The microbubble generator disclosed by this specification includes an inflow part into which gas-dissolved water flows, an outflow part from which the gas-dissolved water flows out, a first microbubble generation part provided between the inflow part and the outflow part, and a second microbubble generation part provided between the first microbubble generation part and the outflow part. The first microbubble generation part includes a reduced-diameter flow path whose flow path diameter decreases from upstream to downstream, and an expanded-diameter flow path provided downstream of the reduced-diameter flow path and whose flow path diameter increases from upstream to downstream. The second microbubble generation part includes a first swirling flow generation part and a second swirling flow generation part provided downstream of the first swirling flow generation part. The first swirling flow generation part includes a first outer peripheral part and a plurality of first blade parts provided inside the first outer peripheral part and generating a first swirling flow flowing in a first swirling direction with respect to the central axis of the second microbubble generation part. The second swirling flow generation part includes a second outer peripheral part and a plurality of second blade parts provided inside the second outer peripheral part and generating a second swirling flow flowing in a second swirling direction opposite to the first swirling direction with respect to the central axis.

[0007] According to the above configuration, the gas-dissolved water flowing into the fine bubble generator flows into the first fine bubble generation section. The gas-dissolved water flowing into the first fine bubble generation section passes through a constricted flow path, thereby increasing the flow velocity and as a result being depressurized. When the gas-dissolved water is depressurized, bubbles are generated. Next, the gas-dissolved water is gradually pressurized by passing through a diffuser flow path. When the gas-dissolved water after bubbles are generated by depressurization is pressurized, the bubbles contained in the gas-dissolved water split into fine bubbles. Next, the gas-dissolved water that has passed through the first fine bubble generation section flows into the first swirling flow generation section of the second fine bubble generation section. The gas-dissolved water flowing into the first swirling flow generation section becomes a swirling flow that flows in a first swirling direction with respect to the central axis of the second fine bubble generation section by a plurality of first blade parts. Next, the gas-dissolved water flowing out from the first swirling flow generation section flows into the second swirling flow generation section. The gas-dissolved water flowing into the second swirling flow generation section becomes a swirling flow that flows in a second swirling direction opposite to the first swirling direction with respect to the central axis of the second fine bubble generation section by a plurality of second blade parts. When the gas-dissolved water changes from a swirling flow flowing in the first swirling direction to a swirling flow flowing in the second swirling direction, turbulence is promoted. By promoting the turbulence, the gas-dissolved water flowing through the second blade parts is likely to collide with each other. When the gas-dissolved water collides, the fine bubbles in the gas-dissolved water split into finer bubbles and the amount of fine bubbles increases. Therefore, a large amount of fine bubbles can be generated.

[0008] In one or more embodiments, when looking at the second fine bubble generation section in the central axis direction, the end portion on the first swirling direction side of the second blade part may be located on the first swirling direction side rather than the end portion on the first swirling direction side of the first blade part, and the end portion on the second swirling direction side of the second blade part may be located on the second swirling direction side rather than the end portion on the first swirling direction side of the first blade part.

[0009] If, when looking at the second fine bubble generation section in the central axis direction, the first blade part and the second blade part completely overlap, most of the gas-dissolved water flowing from the first swirling flow generation section to the second swirling flow generation section is likely to flow into the vicinity of the end on the second swirling direction side of the second blade part. In this case, before generating a swirling flow that flows in the second swirling direction with respect to the gas-dissolved water that has flowed into the second swirling flow generation section, the gas-dissolved water is likely to flow out from the second swirling flow generation section. On the other hand, according to the above configuration, when looking at the second fine bubble generation section in the central axis direction, the end on the first swirling direction side of the first blade part is located between the end on the first swirling direction side and the end on the second swirling direction side of the second blade part. In this case, most of the gas-dissolved water flowing into the second swirling flow generation section is likely to flow into the end on the first swirling direction side of the second blade part. For this reason, in the second swirling flow generation section, most of the gas-dissolved water becomes a swirling flow that flows in the second swirling direction, and as a result, the turbulent flow is further promoted. Therefore, the gas-dissolved water flowing through the second blade part is more likely to collide with each other. As a result, a larger amount of fine bubbles can be generated.

[0010] In one or more embodiments, upstream protruding portions protruding upstream may be provided on the upstream surfaces of the first blade part and the second blade part, respectively.

[0011] According to the above configuration, the gas-dissolved water flowing in the first swirling direction through the first blade part of the first swirling flow generation section collides with the upstream protruding portion provided on the upstream surface of the first blade part, and the turbulent flow of the gas-dissolved water is promoted. Thereby, the gas-dissolved water flowing through the first blade part is more likely to collide with each other. Also, the gas-dissolved water flowing in the second swirling direction through the second blade part of the second swirling flow generation section collides with the upstream protruding portion provided on the upstream surface of the second blade part, and the turbulent flow of the gas-dissolved water is promoted. Thereby, the gas-dissolved water flowing through the second blade part is more likely to collide with each other. Therefore, a larger amount of fine bubbles can be generated.

[0012] In one or more embodiments, a downstream protruding portion protruding downstream may be provided on the downstream side surface of the first blade portion and the second blade portion, respectively.

[0013] According to the above configuration, the gas-dissolved water flowing out from the first blade portion of the first swirling flow generation portion collides with the downstream protruding portion provided on the downstream side surface of another first blade portion adjacent to the first blade portion in the first swirling direction, and the turbulent flow of the gas-dissolved water is promoted. As a result, the gas-dissolved water flowing out from the first blade portion is likely to collide with each other. Further, the gas-dissolved water flowing out from the second blade portion of the second swirling flow generation portion collides with the downstream protruding portion provided on the downstream side surface of another second blade portion adjacent to the second blade portion in the second swirling direction, and the turbulent flow of the gas-dissolved water is promoted. As a result, the gas-dissolved water flowing out from the second blade portion is likely to collide with each other. Therefore, a larger amount of fine bubbles can be generated.

[0014] In one or more embodiments, an upstream protruding portion protruding upstream is provided on the upstream side surface of the first blade portion and the second blade portion, respectively, and a downstream protruding portion protruding downstream is provided on the downstream side surface of the first blade portion and the second blade portion, respectively, and the distance between the central axis and the upstream protruding portion may be different from the distance between the central axis and the downstream protruding portion.

[0015] According to the above configuration, in the first swirling flow generation unit, the gas-dissolved water flowing out from the first blade part can be made to collide with the downstream-side protrusion provided on the downstream-side surface of another first blade part adjacent to the first blade part in the first swirling direction without colliding with the upstream-side protrusion. Also, in the second swirling flow generation unit, the gas-dissolved water flowing out from the second blade part can be made to collide with the downstream-side protrusion provided on the downstream-side surface of another second blade part adjacent to the second blade part in the second swirling direction without colliding with the upstream-side protrusion. That is, in the first swirling flow generation unit, the possibility that the gas-dissolved water collides with at least one of the upstream-side protrusion and the downstream-side protrusion can be increased, and in the second swirling flow generation unit, the possibility that the gas-dissolved water collides with at least one of the upstream-side protrusion and the downstream-side protrusion can be increased. Therefore, the turbulent flow of the gas-dissolved water can be promoted, and a larger amount of fine bubbles can be generated.

Brief Description of the Drawings

[0016]

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Mode for Carrying Out the Invention

[0017] (Example) (Configuration of the hot water supply system 2; FIG. 1) The hot water supply system 2 shown in FIG. 1 heats the water supplied from a water supply source 4 such as a waterworks, and supplies the water heated to a desired temperature to a faucet 6 installed in a kitchen or the like, or a bathtub 8 arranged in a bathroom. Further, the hot water supply system 2 can reheat the water in the bathtub 8.

[0018] The hot water supply system 2 includes a first heat source machine 10, a second heat source machine 12, and a combustion chamber 14. The first heat source machine 10 is a heat source machine used for supplying hot water to the faucet 6 and filling the bathtub 8. The second heat source machine 12 is a heat source machine used for reheating the water in the bathtub 8. The inside of the combustion chamber 14 is partitioned by a partition wall portion 16 into a first combustion chamber 18 and a second combustion chamber 20. The first heat source machine 10 is accommodated in the first combustion chamber 18, and the second heat source machine 12 is accommodated in the second combustion chamber 20.

[0019] The first heat source machine 10 includes a first burner 22 and a first heat exchanger 24. The second heat source machine 12 includes a second burner 26 and a second heat exchanger 28.

[0020] The upstream end of the first heat exchanger 24 of the first heat source machine 10 is connected to the downstream end of the water supply line 30. Water is supplied from the water supply source 4 to the upstream end of the water supply line 30. The downstream end of the first heat exchanger 24 is connected to the upstream end of the hot water supply line 32. The water supply line 30 and the hot water supply line 32 are connected by a bypass line 34. A bypass servo 36 is provided at the connection point between the water supply line 30 and the bypass line 34. The bypass servo 36 adjusts the ratio of the flow rate of water sent from the water supply line 30 to the first heat source machine 10 and the flow rate of water sent from the water supply line 30 to the bypass line 34. At the connection point between the bypass line 34 and the hot water supply line 32, the low-temperature water passing through the water supply line 30 and the bypass line 34 and the high-temperature water passing through the water supply line 30, the first heat source machine 10, and the hot water supply line 32 are mixed. A water volume sensor 38 and a water volume servo 40 are provided in the water supply line 30 upstream of the bypass servo 36. The water volume sensor 38 detects the flow rate of water flowing through the water supply line 30. The water volume servo 40 adjusts the flow rate of water flowing through the water supply line 30. A heat exchanger outlet thermistor 42 is provided in the hot water supply line 32 upstream of the connection point with the bypass line 34.

[0021] The upstream end of the hot water pouring line 50 is connected to the hot water supply line 32 downstream of the connection point of the bypass line 34. A hot water supply thermistor 44 is provided at the connection point between the hot water supply line 32 and the hot water pouring line 50. A fine bubble generator 46 is provided between the connection point of the hot water supply line 32 and the bypass line 34 and the connection point of the hot water supply line 32 and the hot water pouring line 50. The fine bubble generator 46 will be described in detail later. Hereinafter, the waterway of the hot water supply line 32 upstream of the fine bubble generator 46 may be described as the first hot water supply line 32a, and the waterway of the hot water supply line 32 downstream of the fine bubble generator 46 may be described as the second hot water supply line 32b.

[0022] The downstream end of the filling path 50 is connected to the upstream end of the reheating return path 60 and the downstream end of the first bathtub circulation path 62. The downstream end of the reheating return path 60 is connected to the upstream end of the second heat exchanger 28. The upstream end of the first bathtub circulation path 62 is connected to the bathtub 8. A filling control valve 52 and a check valve 54 are provided in the filling path 50. The filling control valve 52 opens and closes the filling path 50. The check valve 54 allows the flow of water from the upstream side to the downstream side of the filling path 50 and prohibits the flow of water from the downstream side to the upstream side of the filling path 50. A bathtub return thermistor 64 is provided at the connection point of the filling path 50, the reheating return path 60, and the first bathtub circulation path 62. A circulation pump 66 is provided in the reheating return path 60.

[0023] The downstream end of the second heat exchanger 28 of the second heat source unit 12 is connected to the upstream end of the second bathtub circulation path 68. The downstream end of the second bathtub circulation path 68 is connected to the bathtub 8. A bathtub forward thermistor 70 is provided in the second bathtub circulation path 68.

[0024] When the hot water supply system 2 supplies hot water to the faucet 6, the first burner 22 of the first heat source unit 10 burns with the filling control valve 52 closed. In this case, the water supplied from the water supply source 4 to the water supply path 30 is heated by heat exchange in the first heat exchanger 24 and then supplied from the hot water supply path 32 to the faucet 6. By adjusting the combustion amount of the first burner 22 of the first heat source unit 10 and the opening degree of the bypass servo 36, the temperature of the water flowing through the hot water supply path 32 can be adjusted to a desired temperature.

[0025] When the hot water supply system 2 performs hot water filling into the bathtub 8, the first burner 22 of the first heat source machine 10 burns with the hot water filling control valve 52 open. In this case, the water supplied from the water supply source 4 to the water supply path 30 is heated by heat exchange in the first heat exchanger 24 and then flows into the hot water filling path 50 from the hot water supply path 32. At this time, the temperature of the water is adjusted to a desired temperature by adjusting the combustion amount of the first burner 22 of the first heat source machine 10 and the opening degree of the bypass servo 36. The water that has flowed into the hot water filling path 50 flows into the bathtub 8 via the first bathtub circulation path 62 and also flows into the bathtub 8 via the supplementary heating forward path 60 and the second bathtub circulation path 68.

[0026] When the hot water supply system 2 performs supplementary heating of the bathtub 8, the circulation pump 66 is driven with the hot water filling control valve 52 closed, and the second burner 26 of the second heat source machine 12 burns. In this case, the water in the bathtub 8 flows into the first bathtub circulation path 62 and is sent to the second heat source machine 12 via the supplementary heating forward path 60. The water sent to the second heat source machine 12 is heated by heat exchange in the second heat exchanger 28 and then flows into the second bathtub circulation path 68. At this time, the temperature of the water is adjusted to a desired temperature by adjusting the combustion amount of the second burner 26 of the second heat source machine 12. The water that has flowed into the second bathtub circulation path 68 is returned to the bathtub 8.

[0027] (Configuration of the fine bubble generator 46; FIGS. 2 to 14) Next, with reference to FIGS. 2 to 14, the fine bubble generator 46 provided in the hot water supply path 32 will be described. As shown in FIG. 2, the fine bubble generator 46 includes a main body case 100, an inflow portion 102, and an outflow portion 104. The outer wall 100a of the main body case 100 has a quadrangular prism shape. As shown in FIG. 11, when the fine bubble generator 46 is viewed in the direction of the central axis A of the fine bubble generator 46, the inner wall portion 100b of the main body case 100 has a circular shape. Hereinafter, the central axis A of the fine bubble generator 46 may be simply described as the "central axis A". As shown in FIG. 3, the inflow portion 102 is fixed to the upstream end portion 100c of the main body case 100 by a screw (not shown). An inlet 102a is formed in the inflow portion 102. The inflow portion 102 is connected to the downstream end of the first hot water supply path 32a (see FIG. 1). The outflow portion 104 is fixed to the downstream end portion 100d of the main body case 100 by a screw (not shown). An outlet 104a is formed in the outflow portion 104. The outflow portion 104 is connected to the upstream end of the second hot water supply path 32b (see FIG. 1).

[0028] The main body case 100 houses a first fine bubble generation unit 110 and a second fine bubble generation unit 112. The first fine bubble generation unit 110 and the second fine bubble generation unit 112 are provided along the central axis A. The first fine bubble generation unit 110 and the second fine bubble generation unit 112 are provided from the upstream side to the downstream side in the order of the first fine bubble generation unit 110 and the second fine bubble generation unit 112. Note that the "clockwise direction" and the "counterclockwise direction" described below mean the directions when the fine bubble generator 46 is viewed from the upstream side in the direction of the central axis A.

[0029] (Configuration of the first fine bubble generation unit 110; FIGS. 3 to 6) Next, with reference to FIGS. 3 to 6, the first fine bubble generation unit 110 will be described. As shown in FIGS. 3 and 4, the first fine bubble generation unit 110 has a cylindrical shape. As shown in FIG. 3, the outer diameter of the first fine bubble generation unit 110 is the same as the inner diameter of the main body case 100. The central axis of the first fine bubble generation unit 110 coincides with the central axis A.

[0030] As shown in FIGS. 3, 5, and 6, eight Venturi portions 120a to 120h are provided in the first fine bubble generation portion 110. The Venturi portion 120a is provided at the center of the first fine bubble generation portion 110. The Venturi portion 120a is provided on the central axis A. As shown in FIG. 3, a reduced-diameter flow path 122a whose flow path diameter decreases from upstream to downstream is provided in the upstream portion of the Venturi portion 120a. The flow path diameter of the upstream end portion of the reduced-diameter flow path 122a is smaller than the flow path diameter of the inlet 102a of the inlet portion 102. A diffuser flow path 124a whose flow path diameter increases from upstream to downstream is provided on the downstream side of the Venturi portion 120a with respect to the reduced-diameter flow path 122a.

[0031] As shown in FIGS. 5 and 6, the Venturi portions 120b to 120h are provided radially outside the central axis A with respect to the Venturi portion 120a. The Venturi portions 120b to 120h are arranged at equal intervals along the circumferential direction of the central axis A. The Venturi portions 120b to 120h are provided with reduced-diameter flow paths 122b to 122h (see FIG. 5) and diffuser flow paths 124b to 124h (see FIG. 6) in the same manner as the Venturi portion 120a. The upstream-side flow path 126 in the first fine bubble generation portion 110 is defined by the reduced-diameter flow paths 122a to 122h and the diffuser flow paths 124a to 124h. Note that the number of Venturi portions 120 provided in the first fine bubble generation portion 110 is not limited to eight, and may be 1 to 7, or 9 or more. As shown in FIG. 3, the water flowing from the inlet portion 102 into the first fine bubble generation portion 110 flows into the second fine bubble generation portion 112 via the upstream-side flow path 126.

[0032] (Configuration of the second fine bubble generation portion 112; FIGS. 3, 4, 7 to 14) Next, with reference to FIGS. 3, 4, 7 to 14, the second fine bubble generation portion 112 will be described. As shown in FIGS. 3 and 4, the central axis of the second fine bubble generation portion 112 coincides with the central axis A. The second fine bubble generation portion 112 includes three cell units 130. The three cell units 130 are provided along the central axis A.

[0033] As shown in FIGS. 7 and 8, the cell unit 130 includes a first swirling flow generation unit 140 and a second swirling flow generation unit 142. As shown in FIG. 3, the first swirling flow generation unit 140 and the second swirling flow generation unit 142 are provided from the upstream side to the downstream side in the order of the first swirling flow generation unit 140 and the second swirling flow generation unit 142.

[0034] As shown in FIG. 7, the first swirling flow generation unit 140 includes a first cylindrical portion 150, five first blade portions 152a to 152e, and a first shaft portion 154. Hereinafter, the five first blade portions 152a to 152e may be collectively referred to simply as the "first blade portion 152". As shown in FIG. 3, the outer diameter of the first cylindrical portion 150 is the same as the inner diameter of the main body case 100. The first cylindrical portion 150 and the first shaft portion 154 are provided along the central axis A. For this reason, the central axis of the first cylindrical portion 150 and the central axis of the first shaft portion 154 coincide with the central axis of the second fine bubble generation unit 112. The first blade portion 152 connects the inner wall of the first cylindrical portion 150 and the outer wall of the first shaft portion 154. As shown in FIG. 7, the first blade portion 152 is inclined downstream as it goes in the counterclockwise direction. On the upstream side surface of the first blade portion 152, two first upstream side protruding portions 156a and 156b protruding upstream are provided. As shown in FIG. 9, the end portion on the clockwise direction side of the first upstream side protruding portion 156b provided on the radially inner side is provided slightly on the clockwise direction side of the virtual line connecting the end portion on the clockwise direction side of the first upstream side protruding portion 156a provided on the radially outer side and the central axis A. The first upstream side protruding portion 156a has a semi-cylindrical portion 162 and a tapered portion 164 that tapers as it goes in the counterclockwise direction. The first upstream side protruding portion 156a has a so-called tear-shaped cross-sectional shape. When the fine bubble generator 46 is viewed in the direction of the central axis A, the cross-sectional shape of the first upstream side protruding portion 156b is the same as the cross-sectional shape of the first upstream side protruding portion 156a.

[0035] As shown in FIG. 8, on the downstream side surface of the first blade portion 152, two first downstream side protruding portions 158a and 158b protruding downstream are provided. As shown in FIG. 9, the end portion on the clockwise side of the first downstream side protruding portion 158b provided on the radially inner side is on the counterclockwise side of an imaginary line connecting the end portion on the clockwise side of the first downstream side protruding portion 158a provided on the radially outer side and the central axis A. When the fine bubble generator 46 is viewed in the direction of the central axis A, the cross-sectional shapes of the first downstream side protruding portions 158a and 158b are the same as the cross-sectional shape of the first upstream side protruding portion 156a. In the radial direction, the first downstream side protruding portion 158a is provided outside the first upstream side protruding portion 156a, and the first downstream side protruding portion 158b is provided between the first upstream side protruding portion 156a and the first upstream side protruding portion 156b. That is, the distances between the first upstream side protruding portion 156a and the central axis A, the first upstream side protruding portion 156b and the central axis A, the first downstream side protruding portion 158a and the central axis A, and the first downstream side protruding portion 158b and the central axis A are different.

[0036] As shown in FIG. 7, the second swirling flow generating section 142 includes a second cylindrical section 170, five second blade sections 172a to 172e, and a second shaft section 174. Hereinafter, the five second blade sections 172a to 172e may be collectively referred to simply as the "second blade section 172". As shown in FIG. 3, the outer diameter of the second cylindrical section 170 is the same as the inner diameter of the main body case 100. The second cylindrical section 170 and the second shaft section 174 are provided along the central axis A. Therefore, the central axis of the second cylindrical section 170 and the central axis of the second shaft section 174 coincide with the central axis of the second fine bubble generating section 112. The second blade section 172 connects the inner wall of the second cylindrical section 170 and the outer wall of the second shaft section 174. As shown in FIG. 7, the second blade section 172 is inclined downstream as it goes in the clockwise direction. That is, the second blade section 172 is inclined in the direction opposite to that of the first blade section 152 of the first swirling flow generating section 140. On the upstream surface of the second blade section 172, two second upstream protruding portions 176a and 176b protruding upstream are provided. As shown in FIG. 10, the counterclockwise end of the second upstream protruding portion 176b provided on the radially inner side is provided slightly on the counterclockwise side of an imaginary line connecting the counterclockwise end of the second upstream protruding portion 176a provided on the radially outer side and the central axis A. The second upstream protruding portion 176a has a semi-cylindrical portion 182 and a tapered portion 184 that tapers as it goes in the clockwise direction. The second upstream protruding portion 176a has a so-called teardrop cross-sectional shape. When the fine bubble generator 46 is viewed along the central axis A, the cross-sectional shape of the second upstream protruding portion 176b is the same as the cross-sectional shape of the second upstream protruding portion 176a. As shown in FIG. 12, when the fine bubble generator 46 is viewed from the upstream side in the direction of the central axis A, the second inflow side end 180b on the counterclockwise side of the second blade section 172a is located on the counterclockwise side of the first outflow side end 160a on the counterclockwise side of the first blade section 152a, and the second outflow side end 180a on the clockwise side of the second blade section 172 is located on the clockwise side of the first outflow side end 160a of the first blade section 152.Also, as shown in FIG. 14, when viewed from the upstream side in the central axis A direction of the fine bubble generator 46, the first inflow side end 160b on the clockwise side of the first blade part 152a is located on the clockwise side of the second outflow side end 180a of the second blade part 172a, and the first outflow side end 160a of the first blade part 152a is located on the counterclockwise side of the second outflow side end 180a of the second blade part 172a. That is, when viewed from the upstream side in the central axis A direction of the fine bubble generator 46, the first blade parts 152a to 152f do not completely overlap with the second blade parts 172a to 172f.

[0037] As shown in FIG. 8, on the downstream side surface of the second blade part 172, two second downstream side protrusions 178a and 178b protruding downstream are provided. As shown in FIG. 10, the end on the counterclockwise side of the second downstream side protrusion 178b provided on the radially inner side is provided on the clockwise side of an imaginary line connecting the end on the counterclockwise side of the second downstream side protrusion 178a provided on the radially outer side and the central axis A. When viewed in the central axis A direction of the fine bubble generator 46, the cross-sectional shapes of the second downstream side protrusions 178a and 178b are the same as the cross-sectional shape of the second upstream side protrusion 176a. In the radial direction, the second downstream side protrusion 178a is provided outside the second upstream side protrusion 176a, and the second downstream side protrusion 178b is provided between the second upstream side protrusion 176a and the second upstream side protrusion 176b. That is, the distances between the second upstream side protrusion 176a and the central axis A, the second upstream side protrusion 176b and the central axis A, the second downstream side protrusion 178a and the central axis A, and the second downstream side protrusion 178b and the central axis A are different.

[0038] Next, with reference to FIGS. 3 and 11 to 14, the fine bubbles generated by the fine bubble generator 46 will be described. The solid arrows in FIGS. 11 to 14 indicate the direction of water flow. The fine bubble generator 46 of this embodiment generates fine bubbles by utilizing the air contained in the water supplied from a water supply source 4 such as a waterworks. The water supplied from the waterworks contains dissolved air (oxygen, carbon dioxide, nitrogen, etc.). Hereinafter, the water in which air is dissolved will be referred to as "air-dissolved water". Further, hereinafter, the description will be made assuming a situation where the calan 6 is operated by the user. As shown in FIG. 1, when the calan 6 is operated by the user, the first burner 22 of the first heat source machine 10 burns with the hot water supply control valve 52 closed. The air-dissolved water supplied from the water supply source 4 to the water supply passage 30 is heated by heat exchange in the first heat exchanger 24 and then flows into the fine bubble generator 46 via the first hot water supply passage 32a.

[0039] Before describing the fine bubbles generated by the fine bubble generator 46, the reason why the fine bubble generator 46 is provided in the first hot water supply passage 32a will be explained. The dissolved air amount indicating the amount of air that can be dissolved in water decreases as the temperature of the water increases. And the closer the amount of air dissolved in water is to the dissolved air amount, the easier it is for bubbles to be generated. Although it will be described in detail later, in the fine bubble generator 46, fine bubbles are generated by generating bubbles in the air-dissolved water and making the bubbles finer. For this reason, the more bubbles are generated in the air-dissolved water, the more the amount of fine bubbles can be increased. For such a reason, in this embodiment, the fine bubble generator 46 is provided in the first hot water supply passage 32a through which the water heated by the first heat source machine 10 flows.

[0040] As shown in FIG. 3, the air-dissolved water flowing into the fine bubble generator 46 flows into the upstream channel 126 in the first fine bubble generation section 110 via the inlet 102a of the inflow section 102. The air-dissolved water flowing into the upstream channel 126 flows into the Venturi sections 120a to 120h. For example, the air-dissolved water flowing into the Venturi section 120a flows into the reduced-diameter channel 122a. The air-dissolved water flowing into the reduced-diameter channel 122a passes through the reduced-diameter channel 122a, thereby increasing its flow velocity and as a result being depressurized. Bubbles are generated when the air-dissolved water is depressurized. The air-dissolved water that has passed through the reduced-diameter channel 122a flows into the enlarged-diameter channel 124a. The air-dissolved water flowing into the enlarged-diameter channel 124a passes through the enlarged-diameter channel 124a, thereby decreasing its flow velocity and as a result being pressurized. When the air-dissolved water containing bubbles after bubble generation by depressurization is pressurized, the bubbles contained in the air-dissolved water split into fine bubbles. The water that has passed through the enlarged-diameter channel 124a flows into the second fine bubble generation section 112. In this way, fine bubbles are generated when the air-dissolved water passes through the Venturi section 120a. The same applies to the air-dissolved water passing through the Venturi sections 120b to 120h, where fine bubbles are generated when the air-dissolved water passes through the Venturi sections 120b to 120h. The air-dissolved water that has passed through the upstream channel 126 in the first fine bubble generation section 110 flows into the second fine bubble generation section 112.

[0041] The aerated water flowing out from the first fine bubble generation unit 110 flows into the first swirling flow generation unit 140 of the cell unit 130 on the most upstream side among the three cell units 130 of the second fine bubble generation unit 112. As shown in FIG. 11, the aerated water flowing into the first swirling flow generation unit 140 becomes a swirling flow that flows in the counterclockwise direction by passing through the first blade part 152 of the first swirling flow generation unit 140. A part of the aerated water collides with the first upstream side protrusions 156a and 156b provided on the upstream side surface of the first blade part 152. By the aerated water colliding with the first upstream side protrusions 156a and 156b, the turbulent flow of the aerated water is promoted. In particular, a vortex is generated between the first upstream side protrusion 156a and the first upstream side protrusion 156b. As a result, the aerated water flowing through the first blade part 152 collides with each other, and as a result, the fine bubbles in the aerated water become finer bubbles and the amount of fine bubbles increases. Then, the aerated water flows out from the first outflow side end 160a of the first blade part 152. Since the first upstream side protrusions 156a and 156b are composed of a semi-cylindrical part 162 and a tapered part 164, compared with a configuration in which the first upstream side protrusions 156a and 156b are not provided on the first blade part 152, the turbulent flow can be promoted. Further, for example, compared with a configuration in which the first upstream side protrusions 156a and 156b have a cylindrical shape or the like, the pressure loss can be reduced. Therefore, it is possible to reduce the pressure loss while promoting the turbulent flow.

[0042] As shown in Fig. 12, a part of the air-dissolved water flowing out from the first outflow-side end portion 160a of the first blade portion 152 collides with the first downstream-side protrusions 158a and 158b provided on the downstream-side surface of another first blade portion 152 adjacent to the first blade portion 152 in the counterclockwise direction. For example, a part of the air-dissolved water flowing out from the first outflow-side end portion 160a of the first blade portion 152a collides with the first downstream-side protrusions 158a and 158b provided on the downstream-side surface of the first blade portion 152e adjacent to the first blade portion 152a in the counterclockwise direction. When the air-dissolved water collides with the first downstream-side protrusions 158a and 158b, the turbulent flow of the air-dissolved water is further promoted. As a result, the air-dissolved water flowing out from the first blade portion 152 is more likely to collide with each other. Consequently, the fine bubbles in the air-dissolved water become finer bubbles, and the amount of the fine bubbles increases. Then, the air-dissolved water flows into the second swirling flow generation portion 142. In the present embodiment, when the fine bubble generator 46 is viewed from the upstream side in the central axis A direction, the second inflow-side end portion 180b of the second blade portion 172 is located on the counterclockwise side of the first outflow-side end portion 160a of the first blade portion 152, and the second outflow-side end portion 180a of the second blade portion 172 is located on the clockwise side of the first outflow-side end portion 160a of the first blade portion 152. That is, when the fine bubble generator 46 is viewed from the upstream side in the central axis A direction, the first blade portions 152a to 152f do not completely overlap with the second blade portions 172a to 172f. Therefore, most of the air-dissolved water flowing out from the first blade portion 152a flows into the vicinity of the second inflow-side end portion 180b of the second blade portion 172a. Note that a part of the air-dissolved water flowing out from the first blade portion 152a flows into the clockwise side of the second inflow-side end portion 180b of the second blade portion 172a.

[0043] As shown in FIG. 13, the air-dissolved water that has flowed into the second swirling flow generation unit 142 becomes a swirling flow that flows in the clockwise direction by passing through the second blade part 172 of the second swirling flow generation unit 142. Since the air-dissolved water changes from a swirling flow that flows in the counterclockwise direction to a swirling flow that flows in the clockwise direction, turbulence is promoted. Then, a part of the air-dissolved water that flows in the clockwise direction collides with the second upstream protruding parts 176a and 176b provided on the upstream side surface of the second blade part 172. Also, since the air-dissolved water collides with the second upstream protruding parts 176a and 176b, the turbulence of the air-dissolved water is promoted. In particular, a vortex is generated between the second upstream protruding part 176a and the second upstream protruding part 176b. As a result, the air-dissolved water flowing through the second blade part 172 is more likely to collide with each other. Consequently, the fine bubbles in the air-dissolved water become finer bubbles, and the amount of fine bubbles increases. Then, the air-dissolved water flows out from the second outflow side end part 180a of the second blade part 172.

[0044] As shown in FIG. 14, a part of the air-dissolved water flowing out from the second outflow-side end portion 180a of the second blade portion 172 collides with the second downstream-side protrusions 178a and 178b provided on the downstream-side surface of another second blade portion 172 adjacent to the second blade portion 172 in the clockwise direction. For example, a part of the air-dissolved water flowing out from the second outflow-side end portion 180a of the second blade portion 172a collides with the second downstream-side protrusions 178a and 178b provided on the downstream-side surface of the second blade portion 172b adjacent to the second blade portion 172a in the clockwise direction. When the air-dissolved water collides with the second downstream-side protrusions 178a and 178b, the turbulent flow of the air-dissolved water is further promoted. As a result, the air-dissolved water flowing out from the second blade portion 172 is more likely to collide with each other. Consequently, the fine bubbles in the air-dissolved water become finer bubbles, and the amount of the fine bubbles increases. Then, the air-dissolved water flows into the first swirling flow generation portion 140 of the cell unit 130 on the downstream side. For example, most of the air-dissolved water flowing out from the second blade portion 172a flows into the vicinity of the first inflow-side end portion 160b of the first blade portion 152a. In addition, a part of the air-dissolved water flowing out from the second blade portion 172a flows into the counterclockwise direction side with respect to the first inflow-side end portion 160b of the first blade portion 152a.

[0045] As described above, the air-dissolved water passes through a total of three cell units 130. Thereby, the fine bubbles in the air-dissolved water are refined, and a large amount of fine bubbles are generated.

[0046] According to the above configuration, as shown in FIGS. 2 to 14, the fine bubble generator 46 includes an inflow portion 102, an outflow portion 104, a first fine bubble generation portion 110 provided between the inflow portion 102 and the outflow portion 104, and a second fine bubble generation portion 112 provided between the first fine bubble generation portion 110 and the outflow portion 104. As shown in FIGS. 5 and 6, the first fine bubble generation portion 110 includes constricted flow paths 122a to 122h and expanded flow paths 124a to 124h. As shown in FIGS. 7 and 8, the second fine bubble generation portion 112 includes a first swirling flow generation portion 140 and a second swirling flow generation portion 142. As shown in FIGS. 7 and 8, the first swirling flow generation portion 140 includes a first cylindrical portion 150 and a plurality of first blade portions 152 that generate a swirling flow that flows in a counterclockwise direction with respect to the central axis of the second fine bubble generation portion 112. The second swirling flow generation portion 142 includes a second cylindrical portion 170 and a plurality of second blade portions 172 that generate a swirling flow that flows in a clockwise direction, which is opposite to the counterclockwise direction, with respect to the central axis of the second fine bubble generation portion 112. As shown in FIG. 3, the air-dissolved water flowing into the first fine bubble generation portion 110 increases in flow velocity by passing through the constricted flow path 122 and is thus depressurized as a result. When the air-dissolved water is depressurized, bubbles are generated. Next, the air-dissolved water is gradually pressurized by passing through the expanded flow path 124. When the air-dissolved water after bubbles are generated by depressurization is pressurized, the bubbles contained in the air-dissolved water split into fine bubbles. Next, the air-dissolved water that has passed through the first fine bubble generation portion 110 flows into the first swirling flow generation portion 140 of the second fine bubble generation portion 112. The air-dissolved water that has flowed into the first swirling flow generation portion 140 becomes a swirling flow that flows in a counterclockwise direction with respect to the central axis of the second fine bubble generation portion 112 by the plurality of first blade portions 152. Next, the air-dissolved water flowing out of the first swirling flow generation portion 140 flows into the second swirling flow generation portion 142. The air-dissolved water that has flowed into the second swirling flow generation portion 142 becomes a swirling flow that flows in a clockwise direction, which is opposite to the counterclockwise direction, with respect to the central axis of the second fine bubble generation portion 112 by the plurality of second blade portions 172. When the air-dissolved water changes from a swirling flow flowing in a counterclockwise direction to a swirling flow flowing in a clockwise direction, turbulent flow is promoted.By promoting the turbulent flow, the air-dissolved waters flowing through the second blade part 172 are more likely to collide with each other. When the air-dissolved waters collide, the fine bubbles in the air-dissolved waters split into finer bubbles, and the amount of the fine bubbles increases. Therefore, finer bubbles can be generated and the amount of the fine bubbles increases. Consequently, a large amount of fine bubbles can be generated.

[0047] Also, as shown in FIG. 12, when the second fine bubble generation part 112 is viewed in the central axis direction of the second fine bubble generation part 112, the second inflow side end part 180b on the counterclockwise direction side of the second blade part 172 is located on the counterclockwise direction side rather than the first outflow side end part 160a on the counterclockwise direction side of the first blade part 152, and the second outflow side end part 180a on the clockwise direction side of the second blade part 172 is located on the clockwise direction side rather than the first outflow side end part 160a of the first blade part 152. According to the above configuration, most of the air-dissolved water flowing into the second swirling flow generation part 142 is likely to flow into the vicinity of the second inflow side end part 180b on the counterclockwise direction side of the second blade part 172. For this reason, in the second swirling flow generation part 142, most of the air-dissolved water becomes a swirling flow flowing in the clockwise direction, and as a result, the turbulent flow is further promoted. Therefore, the air-dissolved waters flowing through the second blade part 172 are more likely to collide with each other. As a result, a larger amount of fine bubbles can be generated.

[0048] Also, as shown in FIG. 7, on the upstream surfaces of the first blade portion 152 and the second blade portion 172, first upstream protruding portions 156a, 156b that protrude upstream and second upstream protruding portions 176a, 176b are provided respectively. According to the above configuration, the air-dissolved water flowing counterclockwise through the first blade portion 152 of the first swirling flow generation portion 140 collides with the first upstream protruding portions 156a, 156b, and the turbulent flow of the air-dissolved water is promoted. As a result, the air-dissolved water flowing through the first blade portion 152 is more likely to collide with each other. In addition, the air-dissolved water flowing clockwise through the second blade portion 172 of the second swirling flow generation portion 142 collides with the second upstream protruding portions 176a, 176b, and the turbulent flow of the air-dissolved water flowing in the clockwise direction is promoted. As a result, the air-dissolved water flowing through the second blade portion 172 is more likely to collide with each other. Therefore, a larger amount of fine bubbles can be generated.

[0049] Also, as shown in FIG. 8, on the downstream surfaces of the first blade portion 152 and the second blade portion 172, first downstream protruding portions 158a, 158b that protrude downstream and second downstream protruding portions 178a, 178b are provided respectively. According to the above configuration, the air-dissolved water flowing out from the first blade portion 152 of the first swirling flow generation portion 140 collides with the first downstream protruding portions 158a, 158b provided on the downstream surface of another first blade portion 152 adjacent to the first blade portion 152 in the counterclockwise direction, and the turbulent flow of the air-dissolved water is promoted. As a result, the air-dissolved water flowing out from the first blade portion 152 is more likely to collide with each other. In addition, the air-dissolved water flowing out from the second blade portion 172 of the second swirling flow generation portion 142 collides with the second downstream protruding portions 178a, 178b provided on the downstream surface of another second blade portion 172 adjacent to the second blade portion 172 in the clockwise direction, and the turbulent flow of the air-dissolved water is promoted. As a result, the air-dissolved water flowing out from the second blade portion 172 is more likely to collide with each other. Therefore, a larger amount of fine bubbles can be generated.

[0050] Also, as shown in FIGS. 7 and 8, on the upstream side surfaces of the first blade portions 152 and the second blade portions 172, first upstream side protruding portions 156a, 156b and second upstream side protruding portions 176a, 176b that protrude upstream are respectively provided. On the downstream side surfaces of the first blade portions 152 and the second blade portions 172, first downstream side protruding portions 158a, 158b and second downstream side protruding portions 178a, 178b that protrude downstream are respectively provided. As shown in FIG. 9, the distance between the central axis of the second fine bubble generation portion 112 and the first upstream side protruding portions 156a, 156b is different from the distance between the central axis and the first downstream side protruding portions 158a, 158b. According to the above configuration, in the first swirling flow generation portion 140, the air-dissolved water flowing out from the first blade portion 152 can collide with the first downstream side protruding portions 158a, 158b provided on the downstream side surface of another first blade portion 152 adjacent to the first blade portion 152 in the counterclockwise direction without colliding with the first upstream side protruding portions 156a, 156b. Further, as shown in FIG. 10, the distance between the central axis of the second fine bubble generation portion 112 and the second upstream side protruding portions 176a, 176b is different from the distance between the central axis and the second downstream side protruding portions 178a, 178b. According to the above configuration, in the second swirling flow generation portion 142, the air-dissolved water flowing out from the second blade portion 172 can collide with the second downstream side protruding portions 178a, 178b provided on the downstream side surface of another second blade portion 172 adjacent to the second blade portion 172 in the counterclockwise direction without colliding with the second upstream side protruding portions 176a, 176b. That is, in the first swirling flow generation portion 140, the possibility that the air-dissolved water collides with at least one of the first upstream side protruding portions 156a, 156b and the first downstream side protruding portions 158a, 158b can be increased, and in the second swirling flow generation portion 142, the possibility that the air-dissolved water collides with at least one of the second upstream side protruding portions 176a, 176b and the second downstream side protruding portions 178a, 178b can be increased. Therefore, the turbulent flow of the air-dissolved water can be promoted, and a larger amount of fine bubbles can be generated.

[0051] (Corresponding relationship) The air-dissolved water is an example of "gas-dissolved water". The first cylindrical portion 150 and the second cylindrical portion 170 are examples of the "first outer peripheral portion" and the "second outer peripheral portion", respectively. The counterclockwise direction and the clockwise direction are examples of the "first turning direction" and the "second turning direction", respectively. The second inflow-side end portion 180b of the second blade portion 172, the second outflow-side end portion 180a of the second blade portion 172, and the first outflow-side end portion 160a of the first blade portion 152 are examples of the "end portion of the second blade portion on the first turning direction side", the "end portion of the second blade portion on the second turning direction side", and the "end portion of the first blade portion on the first turning direction side", respectively. The first upstream-side protrusions 156a and 156b and the second upstream-side protrusions 176a and 176b are examples of the "upstream-side protrusions". The first downstream-side protrusions 158a and 158b and the second downstream-side protrusions 178a and 178b are examples of the "downstream-side protrusions".

[0052] As described above, each embodiment has been described in detail, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

[0053] (First Modified Example) The position where the fine bubble generator 46 is provided is not limited to the first hot water supply path 32a. The fine bubble generator 46 may be provided in the water supply path 30, the water pouring path 50, the afterburner forward path 60, the first bathtub circulation path 62, and the second bathtub circulation path 68.

[0054] (Second Modified Example) In the above hot water supply system 2, fine bubbles are generated by using the air contained in the water supplied from the water supply source 4 such as the waterworks. In the modified example, the hot water supply system 2 may be provided with an air-dissolved water generator that dissolves the air taken in from the outside into the water. Then, the air-dissolved water generated by the air-dissolved water generator may be supplied to the fine bubble generator 46. Further, in another modified example, an air introduction passage for introducing air from the outside may be provided at the connection portion between the reduced-diameter flow paths 122a to 122f and the enlarged-diameter flow paths 124a to 124f of the first fine bubble generation unit 110. Also, instead of air, gases such as carbon dioxide gas, hydrogen, and oxygen may be dissolved in the water.

[0055] (Third Modified Example) The first blade portion 152 may be inclined downstream as it goes in the clockwise direction, and the second blade portion 172 may be inclined downstream as it goes in the counterclockwise direction. That is, the air-dissolved water flowing through the first blade portion 152 may flow in the clockwise direction, and the air-dissolved water flowing through the second blade portion 172 may flow in the counterclockwise direction.

[0056] (Fourth Modified Example) The number of cell units 130 included in the fine bubble generator 46 may be 1 or 2, or may be 4 or more.

[0057] (Fifth Modified Example) The second fine bubble generation unit 112 may be composed of two first swirling flow generation units 140 and one second swirling flow generation unit 142. In this modified example, the two first swirling flow generation units 140 and the one second swirling flow generation unit 142 are provided from the upstream side to the downstream side in the order of the first swirling flow generation unit 140, the second swirling flow generation unit 142, and the first swirling flow generation unit 140. Generally speaking, the number of the first swirling flow generation units 140 and the number of the second swirling flow generation units 142 may be different.

[0058] (Sixth Modified Example) When viewed in the direction of the central axis A of the fine bubble generator 46, the first outflow side end portion 160a of the first blade portion 152 and the second inflow side end portion 180b of the second blade portion 172 may overlap, and the first inflow side end portion 160b of the first blade portion 152 and the second outflow side end portion 180a of the second blade portion 172 may overlap. That is, when viewed in the direction of the central axis A of the fine bubble generator 46, the first blade portion 152 and the second blade portion 172 may completely overlap.

[0059] (Sixth Modification Example) The first blade portion 152 may not include the first upstream side protruding portions 156a and 156b and the first downstream side protruding portions 158a and 158b, and the second blade portion 172 may not include the second upstream side protruding portions 176a and 176b and the second downstream side protruding portions 178a and 178b. Further, in another modification example, the first blade portion 152 may not include one of the first upstream side protruding portions 156a and 156b and the first downstream side protruding portions 158a and 158b, and the second blade portion 172 may not include one of the second upstream side protruding portions 176a and 176b and the second downstream side protruding portions 178a and 178b.

[0060] (Seventh Modification Example) The number of the first upstream side protruding portions 156a and 156b, the first downstream side protruding portions 158a and 158b, the second upstream side protruding portions 176a and 176b, and the second downstream side protruding portions 178a and 178b may be one or three or more.

[0061] (Eighth Modification Example) The distance between the central axis A and the first upstream side protruding portions 156a and 156b may be the same as the distance between the central axis A and the first downstream side protruding portions 158a and 158b. Further, the distance between the central axis A and the second upstream side protruding portions 176a and 176b may be the same as the distance between the central axis A and the second downstream side protruding portions 178a and 178b.

[0062] (Ninth Modification Example) When viewed from the upstream side in the central axis A direction of the fine bubble generator 46, the cross-sectional shapes of the first upstream side protruding portions 156a and 156b, the first downstream side protruding portions 158a and 158b, the second upstream side protruding portions 176a and 176b, and the second downstream side protruding portions 178a and 178b may be circular, fan-shaped, triangular, or the like.

[0063] (Tenth Modification Example) The "first outer peripheral portion" and the "second outer peripheral portion" are not limited to the first cylindrical portion 150 and the second cylindrical portion 170, respectively, and may be any member having a cylindrical shape extending along the central axis A.

[0064] The technical elements described in this specification or the drawings exhibit technical utility either individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Further, the technologies exemplified in this specification or the drawings can achieve multiple objectives simultaneously, and achieving any one of those objectives by itself has technical utility.

Explanation of Reference Numerals

[0065] 2: Hot water supply system 4: Water supply source 6: Faucet 8: Bathtub 10: First heat source machine 12: Second heat source machine 14: Combustion chamber 16: Partition wall portion 18: First combustion chamber 20: Second combustion chamber 22: First burner 24: First heat exchanger 26: Second burner 28: Second heat exchanger 30: Water supply line 32: Hot water supply line 32a: First hot water supply line 32b: Second hot water supply line 34: Bypass line 36: Bypass servo 38: Water volume sensor 40: Water volume servo 42: Heat exchanger outlet thermistor 44: Hot water supply thermistor 46: Microbubble generator 50: Pouring line 52: Pouring control valve 54: Check valve 60: Supplementary heating forward path 62: First bathtub circulation path 64: Bathtub return thermistor 66: Circulation pump 68: Second bathtub circulation path 70: Bathtub forward thermistor 100: Main body case 100a: Outer wall 100b: Inner wall part 100c: Upstream end 100d: Downstream end 102: Inflow part 102a: Inlet 104: Outflow part 104a: Outlet 110: First fine bubble generation part 112: Second fine bubble generation part 120a - 120h: Venturi part 122a - 122h: Converging flow path 124a - 124h: Diverging flow path 126: Upstream side flow path 130: Cell unit 140: First swirling flow generation part 142: Second swirling flow generation part 150: First cylindrical part 152a - 152f: First blade parts 154: First shaft part 156a, 156b: First upstream side protrusions 158a, 158b: First downstream side protrusions 160a: First outflow side end 160b: First inflow side end 162: Semi - cylindrical part 164: Tapered part 170: Second cylindrical part 172a - 172f: Second blade parts 174: Second shaft part 176a, 176b: Second upstream side protrusions 178a, 178b: Second downstream side protrusions 180a: Second outflow side end 180b: Second inflow side end 182: Semi - cylindrical part 184: Tapered part A: Central axis

Claims

1. A microbubble generator, comprising: an inflow section into which gas-dissolved water flows; an outflow section from which the gas-dissolved water flows out; a first microbubble generation section provided between the inflow section and the outflow section; a second microbubble generation section provided between the first microbubble generation section and the outflow section; wherein the first microbubble generation section comprises a reduced-diameter flow path whose flow path diameter decreases from upstream to downstream, and an enlarged-diameter flow path provided downstream of the reduced-diameter flow path and having a flow path diameter that increases from upstream to downstream; wherein the second microbubble generation section comprises a first swirling flow generation section, and a second swirling flow generation section provided downstream of the first swirling flow generation section; wherein the first swirling flow generation section comprises a first outer peripheral section, and a plurality of first blade parts provided inside the first outer peripheral section and generating a first swirling flow that flows in a first swirling direction with respect to the central axis of the second microbubble generation section; wherein the second swirling flow generation section comprises a second outer peripheral section, and a plurality of second blade parts provided inside the second outer peripheral section and generating a second swirling flow that flows in a second swirling direction opposite to the first swirling direction with respect to the central axis; on upstream-side surfaces of the first blade parts and the second blade parts, a plurality of upstream-side protruding parts protruding upstream are respectively provided, and the plurality of upstream-side protruding parts include a first upstream-side protruding part disposed at the outermost side in the radial direction and a second upstream-side protruding part disposed at the innermost side in the radial direction; on downstream-side surfaces of the first blade parts and the second blade parts, a plurality of downstream-side protruding parts protruding downstream are respectively provided, and the plurality of downstream-side protruding parts include a first downstream-side protruding part disposed at the outermost side in the radial direction and a second downstream-side protruding part disposed at the innermost side in the radial direction; a distance between the central axis and the first upstream-side protruding part is a first upper distance; a distance between the central axis and the second upstream-side protruding part is a second upper distance; a distance between the central axis and the first downstream-side protruding part is a first lower distance; a distance between the central axis and the second downstream-side protruding part is a second lower distance; at least one of the first upper distance and the first lower distance and at least one of the second upper distance and the second lower distance are different; a microbubble generator.

2. The fine bubble generator according to claim 1, wherein both the first upper distance and the first lower distance, and both the second upper distance and the second lower distance are different.

3. A fine bubble generator, an inflow portion into which gas-dissolved water flows in, an outflow portion from which the gas-dissolved water flows out, a first fine bubble generation portion provided between the inflow portion and the outflow portion, and a second fine bubble generation portion provided between the first fine bubble generation portion and the outflow portion. The first fine bubble generation portion includes a reduced-diameter flow path whose flow path diameter decreases from upstream to downstream, and an enlarged-diameter flow path provided downstream of the reduced-diameter flow path and having a flow path diameter that increases from upstream to downstream. The second fine bubble generation portion includes a first swirling flow generation portion, and a second swirling flow generation portion provided downstream of the first swirling flow generation portion. The first swirling flow generation portion includes a first outer peripheral portion, and a plurality of first blade portions provided inside the first outer peripheral portion and generating a first swirling flow that flows in a first swirling direction with respect to the central axis of the second fine bubble generation portion. The second swirling flow generation portion includes a second outer peripheral portion, and a plurality of second blade portions provided inside the second outer peripheral portion and generating a second swirling flow that flows in a second swirling direction opposite to the first swirling direction with respect to the central axis. On the upstream-side surfaces of the first blade portions and the second blade portions, a plurality of upstream-side protruding portions protruding upstream are respectively provided. On the downstream-side surfaces of the first blade portions and the second blade portions, a plurality of downstream-side protruding portions protruding downstream are respectively provided. When the fine bubble generator is viewed in the radial direction along the central axis direction, the downstream-side protruding portions are disposed between the plurality of upstream-side protruding portions. Fine bubble generator.

4. When the second fine bubble generation portion is viewed in the central axis direction, an end portion of the second blade portion on the first swirling direction side is located on the first swirling direction side with respect to an end portion of the first blade portion on the first swirling direction side, and an end portion of the second blade portion on the second swirling direction side is located on the second swirling direction side with respect to the end portion of the first blade portion on the first swirling direction side. The fine bubble generator according to any one of claims 1 to 3.

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