Microbubble generating device

Abstract

A microbubble generating device has an inflow portion, an outflow portion, a first microbubble generating portion, and a second microbubble generating portion. The first microbubble generating portion is provided between the inflow portion and the outflow portion and has a first flow path. The second microbubble generating portion is provided between the first microbubble generating portion and the outflow portion and has a second flow path. The first flow path has a reduced-diameter flow path and an enlarged-diameter flow path. The second flow path has a guide flow path and a collision flow path. A first bearing portion is provided in the collision flow path, and a first impeller is rotatably mounted to the first bearing portion. The first impeller has a circular plate portion, a first rotating shaft portion, and a first blade portion. The circular plate portion is provided at a position where water colliding through the guide flow path collides and is provided orthogonal to a flow path axis of the second flow path. The first rotating shaft portion is provided on a surface on a downstream side of the circular plate portion and is rotatably mounted to the first bearing portion. The first blade portion is provided on a surface on an upstream side of the circular plate portion. Accordingly, microbubbles can be generated in a large amount.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a fine bubble generating apparatus. Background Technology

[0002] Patent Document 1 discloses a microbubble generating device comprising: an inlet section for receiving gas-dissolved water; an outlet section for receiving gas-dissolved water; and a microbubble generating section disposed between the inlet section and the outlet section. The microbubble generating section comprises: a narrowing flow path whose diameter decreases from upstream to downstream; and an expanding flow path disposed downstream of the narrowing flow path, whose diameter increases from upstream to downstream.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Publication No. 2018-8193 Summary of the Invention

[0006] In the microbubble generating apparatus of Patent Document 1, water containing dissolved gas (hereinafter sometimes referred to as "gas-dissolved water") flows into the narrowed flow path of the microbubble generating section via the inlet section. The gas-dissolved water experiences an increased flow velocity through the narrowed flow path, resulting in depressurization. Bubbles are generated by this depressurization. Then, the gas-dissolved water is gradually pressurized through the expanding flow path. When the gas-dissolved water, after bubble generation through depressurization, is pressurized, the bubbles contained within it break apart into microbubbles. Thus, in the microbubble generating apparatus of Patent Document 1, microbubbles are generated by the microbubble generating section. However, in the microbubble generating apparatus of Patent Document 1, the amount of microbubbles generated by the microbubble generating apparatus is insufficient.

[0007] This specification provides a technique for generating a large number of microbubbles.

[0008] The microbubble generating device disclosed in this specification has an inlet section, an outlet section, a first microbubble generating section, and a second microbubble generating section. The inlet section receives gas-dissolved water; the outlet section receives gas-dissolved water; the first microbubble generating section is disposed between the inlet section and the outlet section and has a first flow path; the second microbubble generating section is disposed between the first microbubble generating section and the outlet section and has a second flow path. The first flow path has a narrowing flow path and an expanding flow path, wherein the diameter of the narrowing flow path decreases as it moves downstream; the expanding flow path is located downstream of the narrowing flow path and its diameter increases as it moves downstream; the second flow path has a guiding flow path and a collision flow path. The guiding flow path guides the dissolved gas water flowing into the second flow path towards the center of the flow path axis of the second flow path; the collision flow path is located downstream of the guiding flow path and is defined by the collision flow path wall. A first bearing section and a first impeller are provided on the collision flow path. The first impeller is rotatably mounted on the first bearing section. The first impeller has a circular plate section, a first rotating shaft section, and a first blade section. The circular plate section is located at the point of water collision through the guiding flow path and is configured to be orthogonal to the flow path axis of the second flow path. The first rotating shaft section is located on the downstream surface of the circular plate section and is rotatably mounted on the first bearing section. The first blade section is located on the upstream surface of the circular plate section.

[0009] According to the above structure, dissolved gas water flows into the narrowed flow path of the first microbubble generating section via the inlet section. As the dissolved gas water passes through the narrowed flow path, its flow velocity increases, resulting in depressurization. Bubbles are generated when the dissolved gas water is depressurized. Then, the dissolved gas water is gradually pressurized through the expanding flow path. When the dissolved gas water, after bubble generation due to depressurization, is pressurized, the bubbles contained in the dissolved gas water break apart into microbubbles. The dissolved gas water flowing through the first microbubble generating section flows into the second microbubble generating section. The dissolved gas water flowing into the second microbubble generating section flows into the collision flow path via the guide flow path, colliding with the circular plate portion of the first impeller provided in the collision flow path. The guide flow path guides the dissolved gas water flowing into the second microbubble generating section towards the center direction of the flow path axis of the second flow path, i.e., towards the center of the circular plate portion; therefore, most of the dissolved gas water collides near the center of the circular plate portion. Since a first blade portion is provided on the upstream surface of the circular plate portion, the dissolved gas water colliding with the circular plate portion flows along the first blade portion, and the circular plate portion rotates relative to the first bearing portion. As the circular plate rotates relative to the first bearing section, the dissolved water flowing along the first blade section is thrown radially outward from the circular plate, colliding with the walls of the collision flow path that divides the collision flow path. Through the collision of the dissolved water with the collision flow path walls, the microbubbles generated by the first microbubble generating section break down into even smaller bubbles, and the number of microbubbles increases. Therefore, a large number of microbubbles can be generated.

[0010] In one or more embodiments, the microbubble generating device may further include a third microbubble generating section, which is disposed between the first microbubble generating section and the outflow section and has a third flow path. Alternatively, a second bearing section and a second impeller may be provided on the third flow path. The second impeller has a second rotating shaft section and a second blade section, wherein the second rotating shaft section is rotatably mounted to the second bearing section and extends along the flow path axis of the third flow path; the second blade section is connected to the second rotating shaft section and extends radially outward from the second rotating shaft section.

[0011] According to the above structure, dissolved gas water flows into the third flow path of the third microbubble generating section through the first microbubble generating section. The dissolved gas water collides with the second blade of the second impeller disposed in the third flow path, thereby causing the second impeller to rotate relative to the second bearing. Then, the microbubbles in the dissolved gas water passing through the second impeller are sheared by the rotating second blade as the dissolved gas water passes through the second impeller. As a result, the microbubbles in the dissolved gas water become even smaller bubbles, and the number of microbubbles increases.

[0012] In one or more embodiments, the third microbubble generating section may also have a rib, which is located downstream of the second blade section and connects the second bearing section and the wall section that defines (divides) the third flow path.

[0013] According to the above structure, when the gas-dissolved water passing through the second impeller passes through the ribs, the ribs shear the tiny bubbles within the gas-dissolved water. Consequently, the tiny bubbles within the gas-dissolved water become even smaller bubbles, and the number of tiny bubbles increases.

[0014] In one or more embodiments, the second microbubble generating unit may also be disposed between the third microbubble generating unit and the outflow unit.

[0015] In the second microbubble generation section, the dissolved gas collides with the circular plate and the flow path wall, causing a significant change in the flow direction of the dissolved gas. On the other hand, in the third microbubble generation section, the flow direction of the dissolved gas does not change significantly. Therefore, the pressure drop in the second flow path of the second microbubble generation section is greater than the pressure drop in the third flow path of the third microbubble generation section, making it easier for the flow of dissolved gas to stagnate. By allowing the dissolved gas before its flow stagnates to flow into the third microbubble generation section, a large number of microbubbles can be generated. According to the above structure, compared to a structure where the third microbubble generation section is located between the second microbubble generation section and the outflow section, the pressure drop before flowing into the third microbubble generation section can be reduced, allowing the dissolved gas before its flow stagnates to flow into the second microbubble generation section. Therefore, in the third microbubble generation section, the dissolved gas is more easily sheared, resulting in the generation of more microbubbles.

[0016] In one or more embodiments, an axial extension may also be provided in the collision flow path. The axial extension is provided radially between the collision flow path wall and the first impeller in the first rotating shaft portion and extends axially along the first rotating shaft portion.

[0017] By increasing the number of collisions between the gas and dissolved water, the microbubbles become smaller and the number of microbubbles increases. According to the above structure, a portion of the gas-dissolved water ejected radially outward from the circular plate collides with the wall of the collision flow path after the axial extension portion. Therefore, compared to a structure without an axial extension portion in the collision flow path, the number of collisions between the gas and dissolved water can be increased. Consequently, the microbubbles within the gas-dissolved water become even smaller, and the number of microbubbles increases.

[0018] In one or more embodiments, the first end of the first blade portion on the radially inner side of the first rotating shaft portion may be located on the side of the first rotation direction relative to the first rotating shaft portion, which is closer to the second end of the outer side than the second end of the outer side. The third end of the axial extension portion on the radially inner side may be located on the side of the second rotation direction opposite to the fourth end of the outer side than the first rotation direction side.

[0019] According to the above structure, the dissolved gas water colliding with the circular plate passes through the first blade portion, thereby causing the circular plate portion to rotate in the first rotational direction relative to the first bearing portion. Then, the dissolved gas water ejected radially outward from the first impeller flows in the opposite direction to the first rotational direction, i.e., the second rotational direction, while being ejected radially outward. Since the third end of the axial extension is located closer to the second rotational direction side than the fourth end, the dissolved gas water ejected radially outward easily collides with the axial extension. Then, the dissolved gas water colliding with the axial extension flows radially outward, i.e., towards the collision flow path wall. Therefore, the dissolved gas water colliding with the axial extension can collide with the collision flow path wall. Thus, the number of collisions of the dissolved gas water can be increased, the tiny bubbles in the dissolved gas water become even smaller bubbles, and the number of tiny bubbles increases. Attached Figure Description

[0020] Figure 1 This is a diagram schematically illustrating the structure of the hot water supply system 2 involved in the embodiment.

[0021] Figure 2 This is a perspective view of the microbubble generating device 46 involved in the embodiment.

[0022] Figure 3 This is a cross-sectional view of the microbubble generating device 46 involved in the embodiment.

[0023] Figure 4 This is a perspective view showing the microbubble generator 46 according to the embodiment with its main body housing 100 removed.

[0024] Figure 5 yes Figure 4 The exploded diagram.

[0025] Figure 6 This is a diagram showing the upstream microbubble generation unit 110 of the embodiment as viewed from the upstream side.

[0026] Figure 7 This is a diagram showing the upstream microbubble generation unit 110 of the embodiment as viewed from the downstream side.

[0027] Figure 8 This is an exploded view of the intermediate microbubble generation section 112 involved in the embodiment, viewed from the upstream side.

[0028] Figure 9 This is an exploded view of the intermediate microbubble generation section 112 involved in the embodiment, viewed from the downstream side.

[0029] Figure 10 This is an exploded view of the downstream microbubble generation section 114 involved in the embodiment, viewed from the upstream side.

[0030] Figure 11 This is an exploded view of the downstream microbubble generation unit 114 involved in the embodiment, viewed from the downstream side.

[0031] Figure 12 yes Figure 3 Sectional view XII-XII.

[0032] Figure 13 yes Figure 3 Sectional view XIII-XIII.

[0033] Figure 14 yes Figure 3 Sectional view of XIV-XIV.

[0034] Explanation of reference numerals in the attached figures

[0035] 2: Hot water supply system; 4: Water source; 6: Faucet; 8: Bathtub; 10: First heat source unit; 12: Second heat source unit; 14: Combustion chamber; 16: Partition wall; 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 path; 32: Hot water supply path; 32a: First hot water supply path; 32b: Second hot water supply path; 34: Bypass path; 36: Bypass servo mechanism; 38: Water volume sensor; 40: Water volume servo mechanism; 42: Heat exchanger outlet thermistor; 44: Hot water supply thermistor; 46: Microbubble generator; 50: Hot water injection path; 52: Hot water injection control valve; 54: Check valve; 60: Reheating path; 62: First bathtub circulation path; 64: Return bathtub thermistor; 66: Circulation pump; 68: Second bathtub circulation path; 70: To bathtub thermistor; 100: Main body shell; 100a: Outer wall; 100b: Inner wall; 100c: Upstream end; 100d: Downstream end; 102: Inflow section; 102a: Inlet; 104: Outflow section; 104a: Outlet; 110: Upstream microbubble generator; 112: Intermediate microbubble generator; 114: Downstream microbubble generator Section; 120a-120h: Venturi tube section; 122a-122h: narrowing flow path; 124a-124h: widening flow path; 126: upstream side flow path; 130: intermediate fixed section; 132: intermediate rotating section; 140: first intermediate cylindrical section; 142: intermediate bearing section; 144: intermediate rib section; 146: intermediate flow path; 150: second intermediate cylindrical section; 152: intermediate rotating shaft section; 154: intermediate blade section; 160: first downstream side fixed section; 162: downstream side rotating section; 164: second downstream side fixed section; 170: first downstream side cylindrical section; 170a: recessed section; 172: downstream side bearing section; 174 180: Downstream side rib; 180: Circular plate portion; 180a: Downstream side surface; 180b: Upstream side surface; 182: Downstream side rotating shaft portion; 184: Downstream side blade portion; 184a: Inner end portion; 184b: Outer end portion; 184c: Extension portion; 186: Flange portion; 190: Guide portion; 192: Axial extension portion; 200: Guide flow path; 210: First axial extension portion; 210a: Sidewall portion; 210b: Protrusion portion; 212: Second axial extension portion; 212a: Sidewall portion; 212b: Inner end portion; 212c: Outer end portion; 220: Collision flow path; 222: Downstream side flow path; A: Central axis. Detailed Implementation

[0036] (Example)

[0037] (Structure of hot water supply system 2;) Figure 1 )

[0038] Figure 1 The hot water supply system 2 shown can heat water supplied from a water source 4, such as a water supply system, and supply the heated water to a desired temperature to faucets 6 installed in the kitchen, etc., and bathtubs 8 installed in the bathroom. In addition, the hot water supply system 2 can reheat the water in the bathtub 8.

[0039] The hot water supply system 2 includes a first heat source unit 10, a second heat source unit 12, and a combustion chamber 14. The first heat source unit 10 is used to supply hot water to the faucet 6 or to inject hot water into the bathtub 8. The second heat source unit 12 is used to reheat the bathtub 8. The interior of the combustion chamber 14 is divided into a first combustion chamber 18 and a second combustion chamber 20 by a partition wall 16. The first heat source unit 10 is housed in the first combustion chamber 18, and the second heat source unit 12 is housed in the second combustion chamber 20.

[0040] The first heat source unit 10 has a first burner 22 and a first heat exchanger 24. The second heat source unit 12 has a second burner 26 and a second heat exchanger 28.

[0041] The upstream end of the first heat exchanger 24 of the first heat source unit 10 is connected to the downstream end of the water supply path 30. Water is supplied from the water supply source 4 to the upstream end of the water supply path 30. The downstream end of the first heat exchanger 24 is connected to the upstream end of the hot water supply path 32. The water supply path 30 and the hot water supply path 32 are connected by a bypass path 34. A bypass servo mechanism 36 is provided at the connection between the water supply path 30 and the bypass path 34. The bypass servo mechanism 36 adjusts the ratio of the flow rate of water supplied from the water supply path 30 to the first heat source unit 10 and the flow rate of water supplied from the water supply path 30 to the bypass path 34. At the connection between the bypass path 34 and the hot water supply path 32, low-temperature water from the water supply path 30 and the bypass path 34 mixes with high-temperature water from the water supply path 30, the first heat source unit 10, and the hot water supply path 32. A water flow sensor 38 and a water flow servo mechanism 40 are provided on the water supply path 30, which is upstream of the bypass servo mechanism 36. Water flow sensor 38 detects the flow rate of water flowing through water supply path 30. Water flow servo mechanism 40 adjusts the flow rate of water flowing through water supply path 30. A heat exchanger outlet thermistor 42 is installed on the hot water supply path 32 upstream of the connection point with bypass path 34.

[0042] The upstream end of the hot water injection path 50 is connected to the hot water supply path 32, which is downstream of the connection point of the bypass path 34. A hot water supply thermistor 44 is provided at the connection point between the hot water supply path 32 and the hot water injection path 50. A microbubble generator 46 is provided between the connection point of the hot water supply path 32 and the bypass path 34 and the connection point of the hot water supply path 32 and the hot water injection path 50. The microbubble generator 46 will be described in detail later. In addition, the water passage in the hot water supply path 32 located upstream of the microbubble generator 46 is sometimes referred to as the first hot water supply path 32a, and the water passage in the hot water supply path 32 located downstream of the microbubble generator 46 is sometimes referred to as the second hot water supply path 32b.

[0043] The downstream end of the hot water injection path 50 is connected to the upstream end of the reheating path 60 and the downstream end of the first bathtub circulation path 62. The downstream end of the reheating 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 hot water injection control valve 52 and a check valve 54 are provided on the hot water injection path 50. The hot water injection control valve 52 opens and closes the hot water injection path 50. The check valve 54 allows water to flow from the upstream side to the downstream side of the hot water injection path 50 and prohibits water from flowing from the downstream side to the upstream side of the hot water injection path 50. A return bathtub thermistor 64 is provided at the connection point of the hot water injection path 50, the reheating path 60, and the first bathtub circulation path 62. A circulation pump 66 is provided on the reheating path 60.

[0044] 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 thermistor 70 leading to the bathtub is installed on the second bathtub circulation path 68.

[0045] 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 ignites with the hot water injection 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 to the faucet 6 from the hot water supply path 32. By adjusting the combustion rate of the first burner 22 of the first heat source unit 10 and the opening degree of the bypass servo mechanism 36, the temperature of the water flowing through the hot water supply path 32 can be adjusted to the desired temperature.

[0046] When the hot water supply system 2 injects hot water into the bathtub 8, the first burner 22 of the first heat source unit 10 ignites with the hot water injection 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 from the hot water supply path 32 into the hot water injection path 50. By adjusting the combustion rate of the first burner 22 of the first heat source unit 10 and adjusting the opening of the bypass servo mechanism 36, water adjusted to the desired temperature flows into the hot water injection path 50. The water flowing into the hot water injection path 50 flows into the bathtub 8 via the first bathtub circulation path 62, and then into the bathtub 8 via the reheating path 60 and the second bathtub circulation path 68.

[0047] When the hot water supply system 2 reheats the bathtub 8, with the hot water injection control valve 52 closed, the circulation pump 66 is driven, and the second burner 26 of the second heat source unit 12 ignites. In this case, water from the bathtub 8 flows into the first bathtub circulation path 62 and is delivered to the second heat source unit 12 via the reheating path 60. The water delivered to the second heat source unit 12 is heated by heat exchange in the second heat exchanger 28 and then flows into the second bathtub circulation path 68. By adjusting the combustion rate of the second burner 26 of the second heat source unit 12, water adjusted to the desired temperature flows into the second bathtub circulation path 68. The water flowing into the second bathtub circulation path 68 returns to the bathtub 8.

[0048] (Structure of the microbubble generator 46;) Figures 2 to 14 )

[0049] Next, refer to Figures 2 to 14 The microbubble generator 46, installed in the hot water supply path 32, will be described below. Furthermore, the terms "clockwise" and "counterclockwise" as used below refer to the direction when viewing the microbubble generator 46 from the upstream side along its central axis A. Hereinafter, the central axis A of the microbubble generator 46 may be simply referred to as "central axis A". Figure 2 As shown, the microbubble generator 46 has a main body shell 100, an inlet portion 102, and an outlet portion 104. The outer wall portion 100a of the main body shell 100 has a quadrangular prism shape. The central axis of the main body shell 100 coincides with the central axis A. Figure 12 As shown, when the microbubble generator 46 is viewed from the direction of the central axis A, the inner wall portion 100b of the main body shell 100 is circular. Figure 3 The inlet portion 102 is fixed to the upstream end 100c of the main housing 100 by screws (not shown). An inlet 102a is formed in the inlet portion 102. The inlet portion 102 is connected to the first hot water supply path 32a (see reference). Figure 1The downstream end of the main body housing 100. The outlet 104 is fixed to the downstream end 100d of the main body housing 100 by screws (not shown). An outlet 104a is formed in the outlet 104. The outlet 104 is connected to the second hot water supply path 32b (see reference). Figure 1 The upstream end of ).

[0050] An upstream microbubble generating unit 110, an intermediate microbubble generating unit 112, and a downstream microbubble generating unit 114 are housed within the main body casing 100. The upstream microbubble generating unit 110, the intermediate microbubble generating unit 112, and the downstream microbubble generating unit 114 are arranged along the central axis A. The upstream microbubble generating unit 110, the intermediate microbubble generating unit 112, and the downstream microbubble generating unit 114 are arranged from the upstream side to the downstream side in the order of upstream microbubble generating unit 110, intermediate microbubble generating unit 112, and downstream microbubble generating unit 114.

[0051] (Structure of the upstream microbubble generation section 110;) Figures 3-7 )

[0052] Next, refer to Figures 3-7 The upstream microbubble generation unit 110 will be described. For example... Figure 3 , Figure 4 As shown, the upstream microbubble generating section 110 has a cylindrical shape. Figure 3 As shown, the outer diameter of the upstream microbubble generating section 110 is the same as the inner diameter of the main body shell 100. The central axis of the upstream microbubble generating section 110 is aligned with the central axis A.

[0053] like Figure 3 , Figure 6 , Figure 7 As shown, eight Venturi tube sections 120a to 120h are provided in the upstream microbubble generating section 110. The Venturi tube section 120a is located at the center of the upstream microbubble generating section 110. The Venturi tube section 120a is positioned on the central axis A. Figure 3 As shown, a narrowing flow path 122a is provided at the upstream end of the venturi section 120a, with its flow path diameter decreasing as it moves downstream. The flow path diameter at the upstream end of the narrowing flow path 122a is smaller than the flow path diameter of the inlet 102a of the inlet section 102. An expanding flow path 124a is provided downstream of the narrowing flow path 122a of the venturi section 120a, with its flow path diameter increasing as it moves downstream.

[0054] like Figure 6 , Figure 7As shown, the Venturi tube sections 120b to 120h are arranged radially outside the central axis A relative to the Venturi tube section 120a. The Venturi tube sections 120b to 120h are arranged at equal intervals along the circumferential direction of the central axis A. In the Venturi tube sections 120b to 120h, similar to the Venturi tube section 120a, narrower flow paths 122b to 122h are also provided (see reference). Figure 6 ) and extended flow paths 124b~124h (refer to Figure 7 The upstream flow path 126 within the upstream microbubble generation section 110 is defined by narrowing flow paths 122a-122h and widening flow paths 124a-124h. Furthermore, the number of Venturi tube sections 120 provided in the upstream microbubble generation section 110 is not limited to eight; it can be one to seven, or even nine or more. Figure 3 As shown, water flowing from the inlet 102 into the upstream microbubble generating section 110 flows into the intermediate microbubble generating section 112 via the upstream flow path 126.

[0055] (Structure of the intermediate microbubble generation section 112;) Figures 3-5 , Figure 8 , Figure 9 )

[0056] Next, refer to Figures 3-5 , Figure 8 , Figure 9 The intermediate microbubble generation section 112 will be described below. For example... Figure 8 , Figure 9 As shown, the intermediate microbubble generating section 112 has an intermediate fixing section 130 and an intermediate rotating section 132.

[0057] The intermediate fixing part 130 has a first intermediate cylindrical part 140, an intermediate bearing part 142, and five intermediate ribs 144. The first intermediate cylindrical part 140, the intermediate bearing part 142, and the five intermediate ribs 144 are integrally formed. Figure 3 As shown, the outer diameter of the first intermediate cylindrical portion 140 is the same as the inner diameter of the main body shell 100. The central axis of the first intermediate cylindrical portion 140 and the intermediate bearing portion 142 is aligned with the central axis A. The upstream end of the first intermediate cylindrical portion 140 is connected to the downstream end of the upstream microbubble generating portion 110. The intermediate bearing portion 142 is provided downstream of the intermediate fixing portion 130. Figure 8 , Figure 9 As shown, the intermediate rib 144 connects the inner wall of the first intermediate cylindrical portion 140 and the outer wall of the intermediate bearing portion 142. The intermediate rib 144 extends perpendicular to the central axis A. Five intermediate ribs 144 are arranged at equal intervals along the circumferential direction of the central axis A. Figure 3As shown, an intermediate flow path 146 within the intermediate microbubble generating section 112 is defined by an intermediate fixing portion 130 (more specifically, a first intermediate cylindrical portion 140). The flow path axis of the intermediate flow path 146 is aligned with the central axis A.

[0058] like Figure 8 , Figure 9 As shown, the intermediate rotating part 132 has a second intermediate cylindrical part 150, an intermediate rotating shaft part 152, and five intermediate blade parts 154. The second intermediate cylindrical part 150, the intermediate rotating shaft part 152, and the intermediate blade parts 154 are formed as a single unit. Figure 3 As shown, the outer diameter of the second intermediate cylindrical portion 150 is slightly smaller than the inner diameter of the first intermediate cylindrical portion 140 of the intermediate fixed portion 130. The central axes of the second intermediate cylindrical portion 150 and the intermediate rotating shaft portion 152 are aligned with the central axis A. That is, the second intermediate cylindrical portion 150 and the intermediate rotating shaft portion 152 extend along the flow path axis of the intermediate flow path 146. The downstream end of the intermediate rotating shaft portion 152 is mounted to the intermediate bearing portion 142 of the intermediate fixed portion 130 in a manner that allows it to rotate around the central axis A. Figure 8 , Figure 9 As shown, the intermediate blade portion 154 is connected to the inner wall portion of the second intermediate cylindrical portion 150, extends radially outward from the inner wall portion of the second intermediate cylindrical portion 150, and is connected to the outer wall portion of the intermediate rotating shaft portion 152. Figure 8 As shown, when the intermediate rotating part 132 is viewed from the upstream side along the central axis A, the intermediate blade part 154 tilts downstream as it moves towards a clockwise direction. Figure 3 As shown, water flowing from the upstream microbubble generating section 110 into the intermediate microbubble generating section 112 flows into the downstream microbubble generating section 114 via the intermediate flow path 146.

[0059] (Structure of downstream microbubble generation section 114;) Figures 3-5 , Figure 10 , Figure 11 )

[0060] Next, refer to Figures 3-5 , Figure 10 , Figure 11 The downstream microbubble generation section 114 will be described. For example... Figure 10 , Figure 11 As shown, the downstream microbubble generating section 114 has a first downstream fixing section 160, a downstream rotating section 162 and a second downstream fixing section 164.

[0061] The first downstream fixing part 160 has a first downstream cylindrical part 170, a downstream bearing part 172, and four downstream ribs 174. The first downstream cylindrical part 170, the downstream bearing part 172, and the four downstream ribs 174 are formed as one unit. Figure 3 As shown, the outer diameter of the first downstream cylindrical portion 170 is the same as the inner diameter of the main body housing 100. The central axes of the first downstream cylindrical portion 170 and the downstream bearing portion 172 are aligned with the central axis A. The downstream end of the first downstream cylindrical portion 170 contacts the upstream end of the outlet portion 104. Figure 10 As shown, two recesses 170a are provided at the upstream end of the first downstream cylindrical portion 170. A downstream rib 174 connects the inner wall of the first downstream cylindrical portion 170 and the outer wall of the downstream bearing portion 172. The downstream rib 174 extends perpendicularly to the central axis A. Four downstream ribs 174 are arranged at equal intervals along the circumferential direction of the central axis A.

[0062] like Figure 10 , Figure 11 As shown, the downstream rotating part 162 has a circular plate part 180, a downstream rotating shaft part 182, a downstream blade part 184, and a flange part 186. Figure 3 As shown, the circular plate portion 180 is arranged orthogonally to the flow path axis of the downstream flow path 222, which will be described later. Furthermore, the flow path axis of the downstream flow path 222 coincides with the central axis A of the microbubble generator 46. Additionally, the central axis of the circular plate portion 180 coincides with the central axis A of the microbubble generator 46, i.e., the flow path axis of the downstream flow path 222. Figure 11 As shown, the downstream rotating shaft portion 182 extends downstream from the downstream surface 180a of the circular plate portion 180. Figure 3 As shown, the downstream end of the downstream rotating shaft portion 182 is mounted on the downstream bearing portion 172 of the first downstream fixing portion 160 in a manner that allows it to rotate about the central axis A. The outer diameter of the circular plate portion 180 is smaller than the inner diameter of the first downstream cylindrical portion 170. The center portion of the upstream surface 180b of the circular plate portion 180 protrudes upstream. Figure 10 As shown, the downstream blade portion 184 is disposed on the upstream surface 180b of the circular plate portion 180. For example... Figure 14 As shown, when viewing the downstream blade portion 184 from the upstream side along the central axis A, the downstream blade portion 184 is bent such that the inner end 184a, radially inward of the central axis A, is located counterclockwise from the outer end 184b, radially outward of the central axis A. The central portion of the downstream blade portion 184 is located counterclockwise from the virtual line connecting the inner end 184a and the outer end 184b. The outer end 184b of the downstream blade portion 184 extends outward from the circular plate portion 180. Figure 10As shown, the downstream blade portion 184 also has an extension portion 184c extending from the inner end portion 184a towards the upstream side. A flange portion 186 is provided at a position radially outward from the extension portion 184c. The flange portion 186 is provided on the surface upstream of the outer end portion 184b.

[0063] like Figure 10 As shown, the second downstream fixing portion 164 has a guide portion 190 and an axially extending portion 192. The guide portion 190 has a cylindrical shape. Figure 3 As shown, the outer diameter of the guide portion 190 is the same as the inner diameter of the main body shell 100. The central axis of the guide portion 190 is aligned with the central axis A. A guide flow path 200 is provided in the guide portion 190, the flow path diameter of which decreases from upstream to downstream. The flow path diameter on the upstream side of the guide flow path 200 is the same as the flow path diameter at the downstream end of the first intermediate cylindrical portion 140 of the intermediate microbubble generating portion 112. The flow path diameter on the downstream side of the guide flow path 200 is smaller than the outer diameter of the circular plate portion 180.

[0064] like Figure 11 As shown, the axial extension 192 has four first axial extensions 210 and twelve second axial extensions 212. The first axial extensions 210 and the second axial extensions 212 extend downstream from the downstream end of the guide 190. Figure 14 As shown, the first axial extension 210 and the second axial extension 212 are arranged at equal intervals along the circumferential direction of the central axis A. The diameter of the circle formed by connecting the outer wall of the first axial extension 210 and the outer wall of the second axial extension 212 is the same as the inner diameter of the main body shell 100. Three second axial extensions 212 are provided between adjacent first axial extensions 210 in the circumferential direction of the central axis A. When viewing the microbubble generator 46 from the direction of the central axis A, the side wall 210a of the first axial extension 210 is parallel to the virtual line connecting the center of the central axis A and the first axial extension 210 in the circumferential direction. The side wall 212a of the second axial extension 212 is inclined such that the inner end 212b of the radially inner side of the central axis A is located clockwise from the outer end 212c of the radially outer side.

[0065] like Figure 11 As shown, in the four first axial extensions 210, a recess 170a is provided in the first downstream cylindrical portion 170 that is connected to the first downstream fixing portion 160 (see reference). Figure 10 The downstream ends of the two first axial extensions 210 at the corresponding positions are provided with protrusions 210b that protrude downstream. For example... Figure 3As shown, the collision flow path 220 is defined by the inner wall portion 100b of the main body shell 100, which is located radially outside the axial extension portion 192. The downstream flow path 222 within the downstream microbubble generation portion 114 is defined by the guide flow path 200 and the collision flow path 220. Hereinafter, the portion of the inner wall portion 100b of the main body shell 100 that defines the collision flow path 220 will sometimes be referred to as the "collision flow path wall portion".

[0066] Next, refer to Figure 3 , Figures 12-14 The microbubbles generated by the microbubble generator 46 will be explained. Furthermore, Figure 13 solid arrows Figure 14 solid arrow and Figure 14 The dashed arrows indicate the direction of water flow. In this embodiment, the microbubble generator 46 generates microbubbles using air contained in water supplied from a water source 4, such as a water supply system. Air (oxygen, carbon dioxide, nitrogen, etc.) is dissolved in the water supplied from the water supply system. Hereinafter, water containing dissolved air will be referred to as "air-dissolved water." Furthermore, the following description assumes a user operating the faucet 6. Figure 1 As shown, when the user operates the faucet 6, the first burner 22 of the first heat source unit 10 ignites when the hot water injection control valve 52 is closed. The dissolved air 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 microbubble generator 46 via the first hot water supply path 32a.

[0067] Before explaining the microbubbles generated by the microbubble generator 46, the reason for placing the microbubble generator 46 in the first hot water supply path 32a will be explained. The higher the water temperature, the smaller the amount of dissolved air that can dissolve in the water. Furthermore, the closer the amount of dissolved air in the water is to the amount of dissolved air, the easier it is to generate bubbles. In the microbubble generator 46, microbubbles are generated by dissolving air in water to produce bubbles and miniaturizing these bubbles; this will be explained in detail later. Therefore, the more bubbles generated by dissolving air in water, the greater the amount of microbubbles. For this reason, in this embodiment, the microbubble generator 46 is provided on the first hot water supply path 32a through which water heated by the first heat source 10 flows.

[0068] like Figure 3As shown, dissolved air flowing into the microbubble generator 46 enters the upstream flow path 126 within the upstream microbubble generating section 110 via the inlet 102a of the inlet section 102. The dissolved air flowing into the upstream flow path 126 then flows into the venturi sections 120a to 120h. For example, dissolved air flowing into the venturi section 120a flows into the narrowing flow path 122a. The dissolved air flowing into the narrowing flow path 122a experiences an increased flow velocity, resulting in depressurization of the dissolved air. Bubbles are generated by depressurizing the dissolved air. The dissolved air flowing through the narrowing flow path 122a flows into the widening flow path 124a. The dissolved air flowing into the widening flow path 124a experiences a decreased flow velocity, resulting in pressurization of the dissolved air. When the dissolved air, after being depressurized to generate bubbles, is pressurized, the bubbles contained in the dissolved air break apart into microbubbles. Water flows into the intermediate flow path 146 of the intermediate microbubble generating section 112 through the expanded flow path 124a. Thus, microbubbles are generated by allowing air-dissolved water to pass through the venturi section 120a. Air-dissolved water passing through the venturi sections 120b to 120h also generates microbubbles. Air-dissolved water flowing through the upstream flow path 126 within the upstream microbubble generating section 110 flows into the intermediate flow path 146 of the intermediate microbubble generating section 112.

[0069] Air-dissolved water flowing into the intermediate flow path 146 of the intermediate microbubble generation section 112 collides with the intermediate blade section 154 of the intermediate rotating section 132. For example... Figure 12 As shown, dissolved water in the air collides with the intermediate blade portion 154, causing the intermediate blade portion 154 to rotate counterclockwise. Then, as the dissolved water passes through the intermediate blade portion 154 rotating counterclockwise, the tiny bubbles within the dissolved water are sheared, resulting in the tiny bubbles becoming even smaller bubbles, and the number of tiny bubbles increases. Meanwhile, the water passing through the intermediate blade portion 154 flows downstream while swirling clockwise.

[0070] Next, the dissolved water in the air through the middle blade section 154 reaches the middle rib section 144 while rotating clockwise. Then, as... Figure 13 As described above, when the air-dissolved water passes through the intermediate rib 144, the intermediate rib 144 shears the tiny air bubbles within the air-dissolved water, resulting in the tiny air bubbles becoming even smaller bubbles, and the number of tiny bubbles increasing. Figure 3 As shown, dissolved air water flows into the downstream flow path 222 of the downstream microbubble generating unit 114 through the intermediate flow path 146 of the intermediate microbubble generating unit 112.

[0071] Air-dissolved water flowing into the downstream flow path 222 of the downstream microbubble generation section 114 flows into the guide flow path 200. As described above, the flow path axis of the guide flow path 200 is aligned with the central axis of the circular plate section 180. Therefore, the air-dissolved water flowing through the guide flow path 200, whose diameter decreases from upstream to downstream, is guided in the central direction (i.e., the central direction of the circular plate section 180) of the upstream and downstream flow paths 222 of the circular plate section 180 of the downstream rotating section 162. Therefore, most of the air-dissolved water flowing through the guide flow path 200 collides near the center of the circular plate section 180. After colliding with the circular plate section 180, the air-dissolved water flows along the upstream surface 180b and the downstream blade section 184 of the circular plate section 180. The flow of air-dissolved water along the upstream surface 180b and the downstream blade section 184 of the circular plate section 180 causes the downstream rotating section 162 to rotate counterclockwise. Then, as Figure 14 As shown, dissolved air flows clockwise while being ejected radially outward from the downstream rotating section 162. The dissolved air ejected radially outward from the downstream rotating section 162 collides with the collision flow path wall (i.e., the inner wall 100b), the first axial extension 210, and the second axial extension 212. Through these collisions, the tiny bubbles within the dissolved air break down, resulting in even smaller bubbles and a greater number of them. Additionally, a portion of the dissolved air collides with the side wall 212a of the second axial extension 212 and then with the collision flow path wall. Furthermore, a portion of the dissolved air sequentially collides with the side wall 212a of the second axial extension 212, then with the collision flow path wall, and finally with the dissolved air ejected from the circular plate section 180. The dissolved air water collides with the collision flow path wall, the first axial extension 210 and the second axial extension 212, thereby turning the tiny bubbles in the dissolved air water into even smaller bubbles and increasing the number of tiny bubbles.

[0072] Based on the above structure, such as Figures 2-5 As shown, the microbubble generating device 46 includes: an inflow section 102; an outflow section 104; an upstream microbubble generating section 110 disposed between the inflow section 102 and the outflow section 104, and having an upstream flow path 126; and a downstream microbubble generating section 114 disposed between the upstream microbubble generating section 110 and the outflow section 104, and having a downstream flow path 222. Figure 3 , Figure 6 , Figure 7 As shown, the upstream flow path 126 has: narrowing flow paths 122a to 122f; and widening flow paths 124a to 124f, which are located downstream of the narrowing flow paths 122a to 122f. Figure 3 , Figure 10, Figure 11 As shown, the downstream flow path 222 includes: a guiding flow path 200, which guides the dissolved air water flowing into the downstream flow path 222 towards the center of the flow path axis of the downstream flow path 222; and a collision flow path 220, which is defined by the collision flow path wall. A downstream bearing portion 172 and a downstream rotating portion 162 rotatably mounted on the collision flow path 220 are provided. The downstream rotating portion 162 includes: a circular plate portion 180, which is disposed at the point of water collision through the guiding flow path 200 and is orthogonal to the flow path axis of the downstream flow path 222; a downstream rotating shaft portion 182, which is disposed on the downstream surface of the circular plate portion 180 and rotatably mounted on the downstream bearing portion 172; and a downstream blade portion 184, which is disposed on the upstream surface of the circular plate portion 180. Figure 3 As shown, dissolved air water flows through inlet 102 into the narrowed flow paths 122a-122f of the upstream microbubble generation section 110. As the dissolved air water passes through the narrowed flow paths 122a-122f, its flow velocity increases, resulting in depressurization. Bubbles are generated when the dissolved air water is depressurized. Then, the dissolved air water is gradually pressurized through the widened flow paths 124a-124f. When the dissolved air water, after being depressurized and generating bubbles, is pressurized, the bubbles contained in the dissolved air water break down into microbubbles. The dissolved air water flowing through the upstream microbubble generation section 110 flows into the downstream microbubble generation section 114. Figure 14 As shown, air-dissolved water flowing into the downstream microbubble generating section 114 passes through the guide flow path 200 and collides with the circular plate portion 180 disposed on the downstream rotating section 162 of the collision flow path 220. The air-dissolved water flowing into the downstream microbubble generating section 114 through the guide flow path 200 is guided towards the center direction of the flow path axis of the downstream flow path 222, i.e., the center direction of the circular plate portion 180. Therefore, most of the air-dissolved water collides near the center of the circular plate portion 180. Since a downstream blade portion 184 is provided on the upstream surface 180a of the circular plate portion 180, the water colliding with the circular plate portion 180 flows along the downstream blade portion 184, and the circular plate portion 180 rotates relative to the downstream bearing portion 172. Due to the rotation of the circular plate portion 180 relative to the downstream bearing portion 172, the water flowing along the downstream blade portion 184 is thrown radially outward from the circular plate portion 180, colliding with the collision flow path wall used to delineate the collision flow path 220. By colliding with the walls of the collision flow path, dissolved water in air causes microbubbles generated by the upstream microbubble generating unit 110 to break down into even smaller bubbles, and the number of microbubbles increases. Therefore, a large number of microbubbles can be generated.

[0073] In addition, such as Figures 2-5As shown, the microbubble generating device 46 also includes an intermediate microbubble generating section 112, which is disposed between the upstream microbubble generating section 110 and the outflow section 104 and has an intermediate flow path 146. Figure 3 , Figure 8 , Figure 9 As shown, an intermediate bearing portion 142 and an intermediate rotating portion 132 are provided on the intermediate flow path 146. The intermediate rotating portion 132 has: an intermediate rotating shaft portion 152, which is rotatably mounted on the intermediate bearing portion 142 and extends along the flow path axis of the intermediate flow path 146; and an intermediate blade portion 154, which is connected to the intermediate rotating shaft portion 152 and extends radially outward from the intermediate rotating shaft portion 152. According to the above structure, air-dissolved water from the upstream microbubble generating portion 110 flows into the intermediate flow path 146 of the intermediate microbubble generating portion 112. Figure 12 As shown, dissolved air water collides with the intermediate blade portion 154 of the intermediate rotating portion 132 disposed in the intermediate flow path 146, thereby causing the intermediate blade portion 154 to rotate relative to the intermediate bearing portion 142. Then, the tiny air bubbles in the dissolved air water passing through the intermediate blade portion 154 are sheared by the rotating intermediate blade portion 154 as the dissolved air water passes through the intermediate rotating portion 132. Consequently, the tiny air bubbles in the dissolved air water become even smaller bubbles, and the number of tiny bubbles increases.

[0074] In addition, such as Figure 8 , Figure 9 As shown, the intermediate microbubble generating section 112 also has an intermediate rib 144, which is located downstream of the intermediate blade section 154 and connects the intermediate bearing section 142 and the first intermediate cylindrical section 140 that divides (defines) the intermediate flow path 146. According to the above structure, as... Figure 13 As shown, when the air-dissolved water passing through the intermediate rotating section 132 passes through the intermediate rib 144, the intermediate rib 144 shears the tiny air bubbles within the air-dissolved water. Accordingly, the tiny air bubbles within the air-dissolved water become even smaller bubbles, and the number of tiny bubbles increases.

[0075] In addition, such as Figure 3 As shown, the downstream microbubble generating section 114 is disposed between the intermediate microbubble generating section 112 and the outflow section 104. Figure 14 As shown, in the downstream microbubble generation section 114, dissolved air water collides with the circular plate section 180 and the flow path wall section, thereby causing a significant change in the flow direction of the dissolved air water. On the other hand, as... Figure 12 , Figure 13As shown, the flow direction of the air-dissolved water does not change significantly in the intermediate microbubble generating section 112. Therefore, the pressure drop in the downstream flow path 222 of the downstream microbubble generating section 114 is greater than the pressure drop in the intermediate flow path 146 of the intermediate microbubble generating section 112, making it easy for the flow of air-dissolved water to stagnate. By allowing the air-dissolved water before its flow stagnates to flow into the intermediate microbubble generating section 112, a large number of microbubbles can be generated. According to the above structure, compared to a structure where the intermediate microbubble generating section 112 is located between the downstream microbubble generating section 114 and the outflow section 104, the pressure drop before flowing into the intermediate microbubble generating section 112 can be reduced, allowing the air-dissolved water before its flow stagnates to flow into the intermediate microbubble generating section 112. Therefore, in the intermediate microbubble generating section 112, the air-dissolved water is more easily sheared, resulting in the generation of more microbubbles.

[0076] In addition, such as Figure 3 , Figure 10 , Figure 11 As shown, an axial extension 192 is also provided on the collision flow path 220. The axial extension 192 is disposed radially between the collision flow path wall and the downstream rotating part 162, and extends axially along the downstream rotating shaft 182. According to the above structure, as... Figure 14 As shown, a portion of the air-dissolved water ejected radially outward from the circular plate portion 180 collides with the axial extension portion 192 and then with the wall of the collision flow path. Therefore, compared to a structure where the axial extension portion 192 is not provided on the collision flow path 220, the number of collisions of the air-dissolved water can be increased. Consequently, the tiny bubbles in the air-dissolved water become even smaller bubbles, and the number of tiny bubbles increases.

[0077] In addition, such as Figure 14As shown, the inner end 184a of the downstream blade portion 184 is located counterclockwise from the outer end 184b, and the inner end 212b of the second axial extension 212 is located clockwise from the outer end 212c. According to this structure, the air-dissolved water that collides with the circular plate portion 180 passes through the downstream blade portion 184, thereby causing the circular plate portion 180 to rotate counterclockwise relative to the downstream bearing portion 172. Then, the air-dissolved water, which is thrown radially outward from the downstream rotating portion 162, flows clockwise while being thrown radially outward. As described above, the inner end 212b of the second axial extension 212 is located clockwise from the outer end 212c. Assuming that the inner end 212b of the second axial extension 212 is located counterclockwise than the outer end 212c, the dissolved air water that flows clockwise and is thrown radially outward tends to flow along the sidewall 212a of the second axial extension 212. Therefore, the dissolved air water is less likely to collide with the second axial extension 212 (specifically, the sidewall 212a). On the other hand, in this embodiment, since the inner end 212b of the second axial extension 212 is located clockwise than the outer end 212c, the dissolved air water that flows clockwise and is thrown radially outward tends to collide with the second axial extension 212 (specifically, the sidewall 212a). Furthermore, the dissolved air water that collides with the second axial extension 212 (specifically, the sidewall 212a) flows radially outward, i.e., towards the collision flow path wall. Therefore, the air-dissolved water that collides with the second axial extension 212 (specifically, the sidewall 212a) can collide with the collision flow path wall. As a result, the number of collisions of the air-dissolved water can be increased, the tiny bubbles in the air-dissolved water become even smaller bubbles, and the number of tiny bubbles becomes greater.

[0078] (Correspondence)

[0079] Air-dissolved water is an example of "gas-dissolved water". The upstream microbubble generating section 110 is an example of "first microbubble generating section". The upstream flow path 126 is an example of "first flow path". The downstream microbubble generating section 114 is an example of "second microbubble generating section". The downstream flow path 222 is an example of "second flow path". A portion of the inner wall 100b of the main body shell 100 dividing the collision flow path 220 is an example of "collision flow path wall". The downstream bearing section 172 is an example of "first bearing section". The downstream rotating section 162 is an example of "first impeller". The downstream rotating shaft section 182 is an example of "first rotating shaft section". The downstream blade section 184 is an example of "first blade section". The intermediate microbubble generating section 112 is an example of "third microbubble generating section". The intermediate flow path 146 is an example of "third flow path". The intermediate bearing section 142 is an example of a "second bearing section". The intermediate rotating section 132 is an example of a "second impeller". The intermediate rotating shaft section 152 is an example of a "second rotating shaft section". The intermediate blade section 154 is an example of a "second blade section". The first intermediate cylindrical section 140 is an example of a "cylindrical section". The intermediate rib section 144 is an example of a "rib section". The axial extension section 192, the first axial extension section 210, and the second axial extension section 212 are examples of "axial extension sections". The inner end 184a and the outer end 184b of the downstream blade section 184 are examples of "first end" and "second end", respectively. The inner end 212b and the outer end 212c of the second axial extension section 212 are examples of "third end" and "fourth end", respectively. Figure 14 The counterclockwise and clockwise directions are examples of "first rotation direction" and "second rotation direction," respectively.

[0080] The embodiments have been described in detail above, but these embodiments are merely examples and do not limit the scope of the technical solution. The technology described in the technical solution includes technologies obtained by various modifications and alterations to the specific examples illustrated above.

[0081] (First Modification) The location of the microbubble generator 46 is not limited to the first hot water supply path 32a. The microbubble generator 46 may also be installed in the water supply path 30, the hot water injection path 50, the reheating path 60, the first bathtub circulation path 62, or the second bathtub circulation path 68.

[0082] (Second Modification) In the hot water supply system 2 described above, microbubbles are generated using air contained in water supplied from a water source 4, such as a water supply system. In a modification, the hot water supply system 2 may also include an air-dissolved water generating device, which dissolves air obtained from the outside into the water. Furthermore, air-dissolved water generated by the air-dissolved water generating device may be supplied to the microbubble generating device 46. In another modification, an air introduction passage for introducing air from the outside may be provided at the connection between the narrowing flow paths 122a-122f and the widening flow paths 124a-124f of the upstream microbubble generating section 110. Alternatively, gases such as carbon dioxide, hydrogen, and oxygen may be dissolved in the water instead of air.

[0083] (3rd variation) The microbubble generating device 46 may also not have an intermediate microbubble generating section 112.

[0084] (4th Modification) The intermediate microbubble generating section 112 may also lack the first intermediate cylindrical section 140 with the intermediate fixing section 130. In this modification, the intermediate rib 144 connects the inner wall section 100b of the main body shell 100 and the outer wall section of the intermediate bearing section 142. In this modification, the intermediate flow path 146 is divided by a portion of the inner wall section 100b of the main body shell 100 (an example of "the wall section dividing the third flow path").

[0085] (5th variation)

[0086] The number of upstream microbubble generating unit 110, intermediate microbubble generating unit 112 and downstream microbubble generating unit 114 is not limited to one. The microbubble generating device 46 may have two or more upstream microbubble generating units 110, two or more intermediate microbubble generating units 112, and two or more downstream microbubble generating units 114.

[0087] (6th variation) The upstream microbubble generating unit 110, the intermediate microbubble generating unit 112 and the downstream microbubble generating unit 114 may also be arranged from the upstream side to the downstream side in the order of upstream microbubble generating unit 110, downstream microbubble generating unit 114 and intermediate microbubble generating unit 112.

[0088] (7th variation) The intermediate microbubble generating part 112 may also not have the intermediate rib 144.

[0089] (8th variation) The downstream microbubble generating section 114 may also not have the axial extension section 192.

[0090] (9th variation) The axial extension 192 may be composed of only the first axial extension 210 or only the second axial extension 212.

[0091] The technical elements described in this specification or drawings, individually or in various combinations, exert their technical usefulness and are not limited to the combinations described in the technical solution at the time of the application. Furthermore, the technology illustrated in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives is itself technically useful.

Claims

1. A microbubble generating device, characterized in that, It has an inflow section, an outflow section, a first microbubble generating section, and a second microbubble generating section, wherein, The inlet section is for gas-dissolving water to flow in; The outlet section is for the gas-dissolved water to flow out; The first microbubble generating section is disposed between the inflow section and the outflow section and has a first flow path; The second microbubble generating section is disposed between the first microbubble generating section and the outflow section and has a second flow path. The first flow path has a narrowing flow path and an expanding flow path, wherein, The diameter of the narrowing flow path decreases as it moves from upstream to downstream; The expanding flow path is positioned downstream of the contracting flow path, and its diameter increases from upstream to downstream. The second flow path has a guiding flow path and a collision flow path, wherein, The guiding flow path guides the gas-dissolved water flowing into the second flow path towards the center of the flow path axis of the second flow path; The collision flow path is located downstream of the guide flow path and is defined by the wall of the collision flow path. A first bearing section and a first impeller are provided in the collision flow path, and the first impeller is rotatably mounted on the first bearing section. The first impeller has a circular plate portion, a first rotating shaft portion, and a first blade portion, wherein, The circular plate portion is positioned at the point where the dissolved water collides with the gas passing through the guide flow path and is configured to be orthogonal to the flow path axis of the second flow path; The first rotating shaft is disposed on the downstream surface of the circular plate and is rotatably mounted to the first bearing portion; The first blade portion is disposed on the upstream surface of the circular plate portion. The dissolved gas water that collided with the circular plate flowed along the first blade portion. The circular plate portion rotated relative to the first bearing portion. Due to the rotation of the circular plate portion, the dissolved gas water flowing along the first blade portion was thrown out radially outward from the circular plate portion and collided with the collision flow path wall portion.

2. The microbubble generator according to claim 1, characterized in that, The microbubble generating device further includes a third microbubble generating section, which is disposed between the first microbubble generating section and the outflow section and has a third flow path. A second bearing portion and a second impeller are provided in the third flow path. The second impeller has a second rotating shaft portion and a second blade portion. The second rotating shaft portion is rotatably mounted on the second bearing portion and extends along the flow path axis of the third flow path. The second blade portion is connected to the second rotating shaft portion and extends radially outward from the second rotating shaft portion.

3. The microbubble generator according to claim 2, characterized in that, The third microbubble generating section also has a rib, which is located downstream of the second blade section and connects the second bearing section and the wall section defining the third flow path.

4. The microbubble generator according to claim 2, characterized in that, The second microbubble generating section is disposed between the third microbubble generating section and the outflow section.

5. The microbubble generating apparatus according to any one of claims 1 to 4, characterized in that, An axial extension is also provided in the collision flow path. The axial extension is disposed radially between the collision flow path wall and the first impeller in the first rotating shaft and extends axially along the first rotating shaft.

6. The microbubble generator according to claim 5, characterized in that, The first end of the first blade portion, located radially inside the first rotating shaft portion, is positioned closer to the first rotation direction side of the first rotating shaft portion than the second end of the first blade portion. The third end of the axial extension is located on the inner side in the radial direction, in the opposite direction to the fourth end on the outer side, i.e., on the second rotation direction side.

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