Microbubble generator

Abstract

To provide a technique which can reduce an amount of undissolved gas contained in a liquid introduced to a discharge port.SOLUTION: A fine bubble generating device includes: a tank having a supply port and a discharge port; a mixed case; a supply path; an introduction path; a discharge path; a liquid tank; and a fine bubble generating nozzle. The tank has an inside surface having substantially a cylindrical shape around a first shaft in a vertical direction. The mixed case includes a bottom plate part, a side wall part, an agitation part, an outflow part, and a plate-like member. The side wall part has an outside surface having substantially a cylindrical shape around a second shaft substantially the same as the first shaft. The plate-like member projects to a radial outside of the second shaft from the outside surface of the side wall part, and is provided in a circumferential direction of the second shaft. The liquid supplied to the supply port is introduced into the mixed case, is made to outflow to the outside of the mixed case from the outflow part, and is introduced to the discharge port. The plate-like member is below the outflow part, and is arranged above the discharge port. A distance between the plate-like member and the outflow part in the vertical direction is smaller than a distance between the plate-like member and the discharge port.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present specification relates to a microbubble generating device. [Background technology]

[0002] Patent Document 1 discloses a micro-bubble generator comprising: a tank with a supply port and a discharge port; a target member contained in the tank; a supply channel for supplying the liquid to the supply port; a discharge channel for discharging the liquid stored in the tank through the discharge port into a liquid tank; and a micro-bubble generating nozzle provided in the discharge channel for generating micro-bubbles by decompressing the liquid in which the gas is pressurized and dissolved. The tank has a substantially cylindrical inner surface centered on a first axis along the vertical direction. The target member includes a substantially disc-shaped bottom plate extending horizontally; a sidewall portion extending upward from the periphery of the bottom plate and having a substantially cylindrical outer surface centered on a second axis substantially identical to the first axis; and an outlet portion provided in the bottom plate. After impacting the target member, the liquid supplied to the supply port partially flows out from the outlet portion, and the remaining portion falls outside the target member and is guided to the outlet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-111504 Summary of the Invention [Problem to be solved by the invention]

[0004] In the micro-bubble generator of Patent Document 1, the gas is mixed into the liquid by stirring the liquid and the gas. At this time, a portion of the gas mixed into the liquid remains in the liquid without dissolving in the liquid. Here, if the gas that is not dissolved in the liquid (hereinafter, sometimes referred to as "undissolved gas") is introduced to the outlet together with the liquid, the turbidity of the micro-bubbles generated in the liquid tank may decrease. For this reason, in the micro-bubble generator, it is sometimes desirable to reduce the amount of undissolved gas contained in the liquid introduced to the outlet. This specification provides a technology that can reduce the amount of undissolved gas contained in the liquid introduced to the outlet. [Means for solving the problem]

[0005] The micro-bubble generator disclosed in this specification includes a tank having a supply port and a discharge port, a mixing case housed in the tank and dissolving gas in the tank under pressure in a liquid, a supply path for supplying the liquid to the supply port, an introduction path for introducing the liquid supplied to the supply port into the mixing case, a discharge path for discharging the liquid stored in the tank from the discharge port to a liquid tank, and a micro-bubble generating nozzle provided in the discharge path for generating micro-bubbles by decompressing the liquid in which the gas has been pressurized and dissolved. The tank has a substantially cylindrical inner surface centered on a first axis along the vertical direction. The mixing case includes a bottom plate having a substantially circular plate shape extending horizontally, a sidewall extending upward from the periphery of the bottom plate and having a substantially cylindrical outer surface centered on a second axis substantially identical to the first axis, an agitator for agitating the liquid and the gas introduced into the mixing case, an outlet formed by cutting out the upper end of the sidewall, and a plate-like member provided in a portion of the sidewall along the circumferential direction of the second axis and protruding from the outer surface of the sidewall toward the radially outward direction of the second axis. The liquid supplied to the supply port is introduced into the mixing case, flows out of the mixing case from the outlet port, and is guided to the outlet port. The plate-like member is positioned below the outlet port and above the outlet port.

[0006] According to the above configuration, the liquid flowing out from the outflow portion of the mixing case flows downward along the outer surface of the mixing case and collides with the plate-shaped member. The liquid that collides with the plate-shaped member changes direction so that it flows in a substantially horizontal direction along the plate-shaped member. The change in direction of the liquid by the plate-shaped member decelerates the liquid. As the liquid decelerates, undissolved gas contained in the liquid is separated from the liquid. This makes it possible to reduce the amount of undissolved gas contained in the liquid that is guided to the outlet.

[0007] In one or more embodiments, when the mixing case is viewed from above along the second axis, the distance in the circumferential direction of the second axis from the centroid of the plate-shaped member to the centroid of the outlet may be smaller than the distance in the circumferential direction of the second axis from the centroid of the plate-shaped member to the centroid of the outlet.

[0008] When the mixing case is viewed from above along the second axis, if the distance in the circumferential direction of the second axis from the centroid of the plate-shaped member to the centroid of the outflow portion is greater than the distance in the circumferential direction of the second axis from the centroid of the plate-shaped member to the centroid of the discharge port, the liquid flowing out of the outflow portion of the mixing case may be guided to the discharge port without colliding with the plate-shaped member. According to the above configuration, the liquid flowing out of the outflow portion of the mixing case can be more reliably made to collide with the plate-shaped member. This makes it possible to more reliably reduce the amount of undissolved gas contained in the liquid guided to the discharge port.

[0009] In one or more embodiments, when the mixing case is viewed from above along the second axis, the portion of the side wall where the plate-like member is provided may overlap at least a portion of the portion of the side wall where the outflow portion is provided.

[0010] Typically, most of the liquid flowing out of the outflow port of the mixing case flows directly below the outflow port due to gravity. With the above configuration, at least a portion of the liquid flowing directly below the outflow port can be caused to collide with the plate-shaped member. This makes it possible to efficiently reduce the amount of undissolved gas contained in the liquid guided to the discharge port.

[0011] In one or more embodiments, when the mixing case is viewed from above along the second axis, the portion of the side wall where the plate-like member is provided may overlap the entire portion of the side wall where the outflow portion is provided.

[0012] According to the above configuration, all of the liquid flowing directly below the outflow portion can be caused to collide with the plate-shaped member, thereby more efficiently reducing the amount of undissolved gas contained in the liquid guided to the outlet.

[0013] In one or more embodiments, when the tank is viewed from above along the second axis, the outlet may be positioned so as not to overlap with the second axis.

[0014] The outflow portion of the mixing case is located at a position that does not overlap with the second axis. Therefore, when the discharge port is located at a position that does not overlap with the second axis, the liquid from which undissolved gas has been separated by the plate-like member is more likely to be guided to the discharge port. According to the above configuration, the liquid from which undissolved gas has been separated by the plate-like member is more likely to be guided to the discharge port. Therefore, the amount of undissolved gas contained in the liquid guided to the discharge port can be efficiently reduced.

[0015] In one or more embodiments, the tank may further include a circulation opening provided separately from the discharge port. The micro-bubble generator may further include a circulation path that sends the liquid stored in the tank from the circulation opening to the supply port. The circulation path may include a pressure reduction section that reduces the pressure of the liquid and passes it through, and a gas inlet that introduces the gas by using the negative pressure of the liquid in the pressure reduction section. The plate-like member may be located above the circulation opening.

[0016] A micro-bubble generator may be configured to introduce gas into a tank by providing a circulation path for circulating the liquid in the tank and using the negative pressure of the liquid in a pressure-reducing section of the circulation path to introduce the gas into the tank. In this case, if undissolved gas is introduced into the circulation opening together with the liquid, the negative pressure of the liquid in the pressure-reducing section may decrease, potentially reducing the amount of gas introduced. For this reason, in a micro-bubble generator, it may be desirable to reduce the amount of undissolved gas contained in the liquid introduced into the circulation opening. With this configuration, the undissolved gas contained in the liquid flowing out from the outlet of the mixing case is decelerated by the plate-shaped member. When the liquid is decelerated, the undissolved gas contained in the liquid is separated from the liquid. This allows the amount of undissolved gas contained in the liquid introduced into the circulation opening to be reduced.

[0017] In one or more embodiments, when the tank is viewed from above along the second axis, the circulation opening may be positioned so as not to overlap with the second axis.

[0018] When the circulation opening is positioned so as not to overlap with the second axis, the liquid from which the undissolved gas has been separated by the plate-like member is more likely to be guided to the circulation opening. According to the above configuration, the liquid from which the undissolved gas has been separated by the plate-like member is more likely to be guided to the circulation opening. Therefore, the amount of undissolved gas contained in the liquid guided to the circulation opening can be efficiently reduced.

[0019] In one or more embodiments, when the tank and the mixing case are viewed from above along the second axis, a portion of the circulation opening may be located between the inner surface of the tank and the outer surface of the side wall portion.

[0020] The plate-shaped member is provided between the inner surface of the tank and the outer surface of the side wall portion. With this configuration, the liquid from which undissolved gas has been separated by the plate-shaped member is more easily guided to the circulation opening. This makes it possible to more efficiently reduce the amount of undissolved gas contained in the liquid guided to the circulation opening.

[0021] In one or more embodiments, the plate-like member may be seamlessly and integrally formed with the sidewall portion.

[0022] In the manufacturing process of a micro-bubble generator, it is sometimes desirable to reduce the number of parts that make up the mixing case. With the above configuration, the number of parts that make up the mixing case can be reduced compared to when a plate-shaped member is separately attached to the side wall portion.

[0023] In one or more embodiments, the liquid may be water, and the liquid reservoir may be a bathtub used by a user for bathing.

[0024] According to the above configuration, in a micro-bubble generator that generates micro-bubbles in the water in a bathtub used by a user for bathing, the amount of undissolved gas contained in the liquid led to the outlet can be reduced. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a diagram schematically illustrating the configuration of a water heating device 2 of a first embodiment. [Figure 2] 2 is an exploded view of a tank 52 included in the hot water device 2 of the first embodiment. FIG. [Figure 3] 10 is a view of the tank lower portion 522 of the first or second embodiment as viewed from above along the axis A. FIG. [Figure 4] 10 is a view of the tank lower portion 522 and the case main body 40 of the first or second embodiment as viewed from above along the axis A. FIG. [Figure 5] 3 is a diagram schematically illustrating an example of the flow of water in a tank 52 according to the first embodiment. FIG. [Figure 6] 10 is a rear view of the electrode unit 54 and the mixing case 4 of the first or third embodiment. FIG. [Figure 7] 10 is a view of the electrode unit 54 and the case lid 44 of the first or third embodiment as viewed from below. FIG. [Figure 8] 10 is a diagram schematically illustrating an example of the flow of water flowing out from a first outlet 404a in Examples 1 to 3. FIG. [Figure 9]10 is a diagram showing a schematic example of the flow of water in the bathtub adapter 132 of Examples 1 to 3. FIG. [Figure 10] 10 is a diagram showing another example of the water flow in the bathtub adapter 132 of Examples 1 to 3. FIG. [Figure 11] 3 is a diagram schematically illustrating an example of the flow of water in the water heating device 2 of the first embodiment. FIG. [Figure 12] 5 is a diagram schematically showing another example of the flow of water in the water heating device 2 of the first embodiment. FIG. [Figure 13] 10 is a flowchart of a process executed by a control device 150 during a fine bubble generating operation of the hot water device 2 of the first embodiment. [Figure 14] 10 is a diagram schematically showing still another example of the flow of water in the water heating device 2 of the first embodiment. FIG. [Figure 15] FIG. 10 is a diagram schematically illustrating the configuration of a water heating device 2A of a second embodiment. [Figure 16] FIG. 10 is an exploded view of a tank 72 included in a water heating device 2A of a second embodiment. [Figure 17] 10 is a rear view of the electrode unit 754 and the mixing case 4 of the second embodiment. FIG. [Figure 18] 10 is a view of an electrode unit 754 and a case lid 44 of the second embodiment as viewed from below. FIG. [Figure 19] 10 is a flowchart of a process executed by a control device 150 during a fine bubble generating operation of a water heating device 2A of a second embodiment. [Figure 20] FIG. 10 is a diagram schematically illustrating the configuration of a water heating device 2B according to a third embodiment. [Figure 21] 10 is a flowchart of a process executed by a control device 150 during a fine bubble generating operation of a water heating device 2B of a third embodiment. [Figure 22] 10 is a diagram schematically illustrating an example of the flow of water in a water heating device 2B of a third embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0026] (Example) 1, the water heater 2 of this embodiment includes a heat source unit 10, an air pressurization dissolution unit 50, a bathtub adapter 132, and a control device 150. The water heater 2 heats water supplied from a water supply source 200 such as a tap, and supplies the water heated to a desired temperature to a faucet 250 installed in a kitchen or the like, or to a bathtub 130 installed in a bathroom. The water heater 2 can also generate fine bubbles in the water in the bathtub 130 that a user uses for bathing.

[0027] (Configuration of heat source unit 10) The heat source unit 10 includes a first heat source unit 12, a second heat source unit 14, a water supply line 16, a hot water outlet line 18, a bypass line 20, a bypass servo 22, a hot water inlet line 24, a hot water filling valve 26, a water volume sensor 28, a forward circulation line 30, a return circulation line 32, a bathtub circulation pump 34, and a water flow switch 36.

[0028] The upstream end of water supply passage 16 is connected to water supply source 200, and the downstream end of water supply passage 16 is connected to first heat source unit 12. Furthermore, the upstream end of hot water outlet passage 18 is connected to first heat source unit 12, and the downstream end of hot water outlet passage 18 is connected to faucet 250. First heat source unit 12 is a combustion heat source unit that heats water by, for example, burning gas. First heat source unit 12 heats the water flowing in from water supply passage 16 and sends the heated water to hot water outlet passage 18.

[0029] The upstream end of the bypass passage 20 is connected to the water supply passage 16, and the downstream end of the bypass passage 20 is connected to the hot water outlet passage 18. A bypass servo 22 is provided where the bypass passage 20 connects to the water supply passage 16. The bypass servo 22 adjusts the opening of a built-in valve to adjust the ratio of the flow rate of water flowing from the water supply passage 16 via the first heat source unit 12 to the hot water outlet passage 18 and the flow rate of water flowing from the water supply passage 16 via the bypass passage 20 to the hot water outlet passage 18. By adjusting the opening of the bypass servo 22, high-temperature water flowing from the first heat source unit 12 and low-temperature water flowing from the bypass passage 20 are mixed in a desired ratio in the hot water outlet passage 18 downstream of the connection point with the bypass passage 20, thereby supplying water adjusted to a desired temperature. A hot water outlet temperature thermistor 18a is provided in the hot water outlet passage 18 downstream of the connection point with the bypass passage 20 to detect the temperature of the water in the hot water outlet passage 18.

[0030] The upstream end of the molten metal pouring path 24 is connected to the molten metal outlet path 18 downstream of the point where the bypass path 20 is connected, and the downstream end of the molten metal pouring path 24 is connected to the return circulation path 32. A molten metal filling valve 26 is provided in the molten metal pouring path 24 and opens and closes the molten metal pouring path 24. The molten metal filling valve 26 is normally kept closed. A water volume sensor 28 is provided in the molten metal pouring path 24 and detects the amount of water flowing through the molten metal pouring path 24.

[0031] The upstream end of the return circulation path 32 is connected to a heat source return path 60 (details will be described later) of the air pressurized dissolving unit 50, and the downstream end of the return circulation path 32 is connected to the second heat source device 14. The upstream end of the outgoing circulation path 30 is connected to the second heat source device 14, and the downstream end of the outgoing circulation path 30 is connected to a heat source outgoing path 68 (details will be described later) of the air pressurized dissolving unit 50. The second heat source device 14 is a combustion heat source device that heats water by, for example, burning gas. The second heat source device 14 heats the water flowing in from the return circulation path 32 and sends the heated water to the outgoing circulation path 30. A return circulation path thermistor 32a that detects the temperature of the water in the return circulation path 32 is provided near the upstream end of the return circulation path 32. A forward circulation path thermistor 30a that detects the temperature of the water in the outgoing circulation path 30 is provided near the downstream end of the outgoing circulation path 30.

[0032] The bathtub circulation pump 34 is provided on the circulation return path 32 downstream of the connection point of the hot water supply path 24, and sends water from the circulation return path 32 toward the second heat source unit 14. The water flow switch 36 is provided on the circulation return path 32 between the bathtub circulation pump 34 and the second heat source unit 14, and detects whether water is flowing through the circulation return path 32.

[0033] (Configuration of the air pressure dissolving unit 50) The air pressurization dissolution unit 50 includes a tank 52, a heat source return path 60, a heat source outward path 68, a tank return path 74, a tank outward path 64, a connecting passage 66, a first three-way valve 80, a second three-way valve 82, a check valve 84, a tank water supply valve 86, a first pressurization pump 88, a second pressurization pump 90, a tank circulation path 92, a tank circulation pump 94, and a gas introduction mechanism 96.

[0034] (Tank 52 Configuration) The tank 52 can store water therein and is also used to generate air-dissolved water by dissolving air in water under pressure.

[0035] As shown in FIG. 2, the tank 52 includes an upper tank portion 520 and a lower tank portion 522. The upper tank portion 520 includes an electrode installation portion 540, a first water supply port 74a, and a second water supply port 74b. The lower tank portion 522 includes a case installation portion 550, a drain port 64a, and a circulation opening 92a (see FIG. 3). The upper tank portion 520 and the lower tank portion 522 are fixed to each other with screws (not shown). The upper tank portion 520 and the lower tank portion 522 have substantially cylindrical inner surfaces centered on an axis A extending in the vertical direction. A mixing case 4 is accommodated inside the tank 52. The mixing case 4 includes a case body 40, a stirring portion 42, a case lid 44, and an introduction pipe 46. An electrode unit 54 is installed in the electrode installation portion 540.

[0036] 3, the drain outlet 64a and the circulation opening 92a are provided on the underside of the tank lower part 522 and open downward. Therefore, the water stored in the tank 52 is configured to be guided to the drain outlet 64a and the circulation opening 92a along the inner surface of the tank 52. In this embodiment, when the tank lower part 522 is viewed from above along the axis A, the drain outlet 64a and the circulation opening 92a are positioned so as not to overlap with the axis A.

[0037] As shown in Figure 4, when the tank lower part 522 and the case body 40 are viewed from above along the axis A, the drain outlet 64a (see Figure 3) is located at a position hidden by the case body 40. Furthermore, when the tank lower part 522 and the case body 40 are viewed from above along the axis A, a portion of the circulation opening 92a is located between the inner surface of the tank lower part 522 and the outer surface of a first side wall part 402, which will be described later.

[0038] (Configuration of case body 40) 2, the case body 40 includes a first bottom plate portion 400 having a substantially circular plate shape extending horizontally, a first side wall portion 402 extending upward from the peripheral edge of the first bottom plate portion 400, a plurality of outlet portions 404 formed by cutting out the upper end portion of the first side wall portion 402, and a plate-like member 406 and a plurality of mounting members 408 provided on the first side wall portion 402. In this embodiment, the first bottom plate portion 400, the first side wall portion 402, the plate-like member 406, and the plurality of mounting members 408 are formed integrally and seamlessly. The first side wall portion 402 is formed in a substantially cylindrical shape centered on the axis A.

[0039] 4, the plate-like member 406 and the plurality of mounting members 408 abut from above against the case installation portion 550 of the tank lower portion 522. Therefore, the case main body 40 is supported on the tank lower portion 522 via the plate-like member 406 and the plurality of mounting members 408.

[0040] In this embodiment, there are provided four outlet portions 404. Therefore, in this embodiment, the outlet portions 404 may be classified into a first outlet portion 404a, a second outlet portion 404b, a third outlet portion 404c, and a fourth outlet portion 404d.

[0041] The plurality of mounting members 408 are provided at predetermined angular intervals along the circumferential direction of the axis A. In this embodiment, three mounting members 408 are provided. For this reason, in this embodiment, the plurality of mounting members 408 may be classified into a first mounting member 408a, a second mounting member 408b, and a third mounting member 408c. The first mounting member 408a, the second mounting member 408b, and the third mounting member 408c are provided at 90° intervals along the circumferential direction of the axis A.

[0042] The plate-shaped member 406 is a flat plate having a substantially sector-shaped shape centered on the axis A. The plate-shaped member 406 is provided along the horizontal direction. The plate-shaped member 406 is provided along the circumferential direction of the axis A within a predetermined angular range (for example, an angular range of 70°) of the entire circumference of the first side wall portion 402. The plate-shaped member 406 protrudes from the outer surface of the first side wall portion 402 toward the outside in the radial direction of the axis A. Furthermore, when the case body 40 is viewed from above along the axis A, the portion of the first side wall portion 402 where the plate-shaped member 406 is provided overlaps the entire portion of the first side wall portion 402 where the first outlet portion 404a is provided. Furthermore, when the case body 40 is viewed from above along the axis A, the distance in the circumferential direction of the axis A from the centroid of the plate-shaped member 406 to the centroid of the first outflow section 404a is smaller than the distance in the circumferential direction of the axis A from the centroid of the plate-shaped member 406 to the centroid of the drain outlet 64a, and is also smaller than the distance in the circumferential direction of the axis A from the centroid of the plate-shaped member 406 to the centroid of the circulation opening 92a.

[0043] 5, the plate-shaped member 406 is disposed below the first outlet 404a and above the drain outlet 64a and the circulation opening 92a. The vertical distance from the plate-shaped member 406 to the first outlet 404a is shorter than the vertical distance from the plate-shaped member 406 to the drain outlet 64a and is also shorter than the vertical distance from the plate-shaped member 406 to the circulation opening 92a.

[0044] (Configuration of the stirring unit 42) 2, the stirring unit 42 includes a second bottom plate 420 having a substantially circular plate shape extending horizontally, a second side wall 422 extending upward from the peripheral edge of the second bottom plate 420, an insertion tube 424 and a fitting member 426 provided along the tangential direction of the second side wall 422, and a flange 428 protruding radially outward from the upper portion of the second side wall 422. In this embodiment, the second bottom plate 420, the second side wall 422, the insertion tube 424, the fitting member 426, and the flange 428 are formed integrally and seamlessly. The second side wall 422 is formed in a substantially cylindrical shape centered on the axis A.

[0045] 5, the flange portion 428 abuts against the upper end portion of the first side wall portion 402 of the case body 40 from above. Therefore, the stirring portion 42 is supported by the case body 40 via the flange portion 428. When the stirring portion 42 is supported by the case body 40, the insertion tube 424 fits into a portion of the fourth outlet portion 404d of the case body 40, and the fitting member 426 fits into a portion of the first outlet portion 404a.

[0046] The stirring unit 42 further includes a jetting port 425 formed in the second bottom plate portion 420. The second bottom plate portion 420 is disposed at a position spaced apart from the first bottom plate portion 400 of the case body 40 in the up-down direction. The outer diameter of the second side wall portion 422 is smaller than the inner diameter of the first side wall portion 402 of the case body 40. As a result, a gap is provided between the stirring unit 42 and the case body 40, which connects the jetting port 425 and the plurality of outlet portions 404.

[0047] (Configuration of case lid 44) As shown in FIG. 2, the case lid 44 includes an upper plate portion 440 having a generally circular plate shape extending horizontally, an expanded diameter portion 442 connected to the peripheral edge of the upper plate portion 440 and extending radially outward relative to the axis A as it extends downward, a side plate portion 444 extending downward from the lower end of the expanded diameter portion 442, and an electrode cover 446 provided on the side plate portion 444 and extending vertically. In this embodiment, the upper plate portion 440, the expanded diameter portion 442, the side plate portion 444, and the electrode cover 446 are seamlessly and integrally formed. The electrode cover 446 is formed in a shape that follows the inner surfaces of the tank upper portion 520 and the tank lower portion 522. The upper plate portion 440 is also provided with a communicating air hole (not shown).

[0048] 5, the case lid 44 is provided to cover the upper parts of the case body 40 and the agitator 42. A sealing member (not shown) seals the space between the case lid 44 and the agitator 42. Therefore, the case lid 44 prevents water introduced into the agitator 42 from passing between the case lid 44 and the agitator 42 and flowing out of the mixing case 4. In addition, the case lid 44 prevents water from splashing above the tank 52 when it flows out from the multiple outlets 404 of the case body 40.

[0049] (Configuration of the introduction pipe 46) The inlet pipe 46 is attached to the agitator 42 by being inserted into the insertion pipe 424 of the agitator 42. The inlet pipe 46 is provided to communicate the first water inlet 74a and the second water inlet 74b of the tank upper part 520 with the interior of the agitator 42. Therefore, the inlet pipe 46 can introduce water supplied to the first water inlet 74a and the second water inlet 74b of the tank upper part 520 into the interior of the agitator 42.

[0050] (Configuration of electrode unit 54) As shown in FIG. 2, the electrode unit 54 includes a high water level electrode 54a, a low water level electrode 54b, and a ground electrode 54c. The high water level electrode 54a, the low water level electrode 54b, and the ground electrode 54c extend vertically inside the tank 52 but outside the mixing case 4. When the high water level electrode 54a and the low water level electrode 54b come into contact with the water surface of the water stored in the tank 52, a current flows between the high water level electrode 54a and the low water level electrode 54b and outputs an ON signal to the control device 150. That is, each of the high water level electrode 54a and the low water level electrode 54b is configured to detect whether the water level in the tank 52 is equal to or higher than a predetermined water level. Hereinafter, the water level in the tank 52 detected by the low water level electrode 54b may be referred to as the "first water level." The water level in the tank 52 detected by the high water level electrode 54a may be referred to as the "second water level." The lower end of the high water level electrode 54a is higher than the lower end of the low water level electrode 54b. Therefore, the second water level is higher than the first water level.

[0051] 6, the high water level electrode 54a is covered by an electrode cover 446. On the other hand, the low water level electrode 54b and the earth electrode 54c are not covered by the electrode cover 446. The lower end of the electrode cover 446 is located lower than the lower ends of the high water level electrode 54a, the low water level electrode 54b, and the earth electrode 54c. The lower end of the electrode cover 446 is also located lower than the lower end of the mixing case 4.

[0052] As shown in FIG. 7, when the electrode cover 446 is viewed from below, the electrode cover 446 covers the entire periphery of the high water level electrode 54a.

[0053] (Water flow in tank 52) As shown in FIG. 5, water supplied from the first water inlet 74a and the second water inlet 74b is introduced into the agitator 42 via the inlet pipe 46. The water introduced into the agitator 42 flows downward while swirling in a spiral pattern within the agitator 42. When the water swirls within the agitator 42, a large negative pressure is generated near the center of the agitator 42. As a result, air accumulated at the top of the tank 52 is drawn into the agitator 42 through the air communication hole (not shown) in the case lid 44. The air drawn into the agitator 42 is entrained in the water swirling within the agitator 42. This causes the air to dissolve in the water, producing aerated water. The aerated water produced within the agitator 42 is ejected from the ejection port 425 toward the first bottom plate 400 of the case body 40. The aerated water ejected from the ejection port 425 collides with the first bottom plate portion 400, changes direction, flows upward through the gap formed between the second side wall portion 422 and the first side wall portion 402, and flows out of the mixing case 4 from the multiple outlets 404 of the case main body 40. The aerated water ejected from the multiple outlets 404 flows downward through the gap formed between the inner surface of the tank 52 and the first side wall portion 402, and is stored in the tank 52. Note that the solid arrows in FIG. 5 indicate the flow of water.

[0054] As shown in FIG. 8 , among the aerated water flowing out from the multiple outlets 404, the aerated water flowing out from the first outlet 404a collides with the plate-shaped member 406 as it flows downward through the gap formed between the inner surface of the tank 52 and the first sidewall 402. The aerated water that collides with the plate-shaped member 406 changes direction to flow horizontally along the plate-shaped member 406. When the plate-shaped member 406 changes direction, the aerated water slows down. Therefore, if undissolved air is mixed in the aerated water, the undissolved air is separated from the aerated water due to the deceleration of the aerated water. The air separated from the aerated water then returns to the upper part of the tank 52. As described above, the water heater 2 of this embodiment can reduce the amount of undissolved air contained in the aerated water that is guided to the drain outlet 64a (see FIG. 3 ) and the circulation opening 92a (see FIG. 3 ). Note that the solid arrows in FIG. 8 indicate the water flow.

[0055] (Configuration of each water channel in the air pressure dissolution unit 50) As shown in FIG. 1, one end of the heat source return line 60 is connected to a communication passage 66, and the other end of the heat source return line 60 is connected to the circulation return line 32 of the heat source unit 10. The communication passage 66 connects a first three-way valve 80 and a second three-way valve 82. The first three-way valve 80 is connected to the communication passage 66, the first bathtub water passage 62, and the tank outbound line 64. The first three-way valve 80 can be switched between a first communication state (see FIG. 14) in which the tank outbound line 64 and the first bathtub water passage 62 are connected, a second communication state (see FIG. 1) in which the tank outbound line 64 and the communication passage 66 are connected, and a third communication state (see FIGS. 11 and 12) in which the first bathtub water passage 62, the tank outbound line 64, and the communication passage 66 are connected. The upstream end of the tank outflow path 64 is connected to the tank 52 via a drain port 64a, and the downstream end of the tank outflow path 64 is connected to a first three-way valve 80. A check valve 84 is provided in the tank outflow path 64 to allow water to flow from the tank 52 toward the first three-way valve 80 and to prohibit water from flowing from the first three-way valve 80 toward the tank 52. One end of the first bathtub water passage 62 is connected to the first three-way valve 80, and the other end of the first bathtub water passage 62 is connected to a bathtub adapter 132.

[0056] One end of the heat source outbound path 68 is connected to the circulation outbound path 30 of the heat source unit 10, and the other end of the heat source outbound path 68 is connected to a second three-way valve 82. The second three-way valve 82 is connected to a communication passage 66, the heat source outbound path 68, and a second bathtub water passage 70. The second three-way valve 82 can switch between a fourth communication state (see FIG. 14) in which the second bathtub water passage 70 and the communication passage 66 are connected, and a fifth communication state (see FIGS. 1, 11, and 12) in which the heat source outbound path 68 and the second bathtub water passage 70 are connected. One end of the second bathtub water passage 70 is connected to the second three-way valve 82, and the other end of the second bathtub water passage 70 is connected to a bathtub adapter 132.

[0057] The upstream end of the tank return line 74 is connected to the heat source outbound line 68, and the downstream end of the tank return line 74 is connected to the tank 52 via a first water supply port 74a. A tank water supply valve 86 is provided in the tank return line 74 and opens and closes the tank return line 74. The tank water supply valve 86 is normally closed. A first pressurizing pump 88 and a second pressurizing pump 90 are provided in the tank return line 74 between the tank water supply valve 86 and the tank 52. The first pressurizing pump 88 and the second pressurizing pump 90 pressurize the water in the tank return line 74 and send it out toward the tank 52. In the tank return line 74, the first pressurizing pump 88 is provided upstream of the second pressurizing pump 90.

[0058] The upstream end of the tank circulation path 92 is connected to the tank 52 via a circulation opening 92a, and the downstream end of the tank circulation path 92 is connected to the tank 52 via a second water supply port 74b. A tank circulation pump 94 is provided on the tank circulation path 92. The tank circulation pump 94 draws water from within the tank 52 into the tank circulation path 92 via the circulation opening 92a, and discharges water from the tank circulation path 92 into the tank 52 via the second water supply port 74b.

[0059] (Configuration of gas introduction mechanism 96) The gas introduction mechanism 96 is provided in the tank circulation path 92 upstream of the tank circulation pump 94. The gas introduction mechanism 96 includes a water inlet pipe 98, a water outlet pipe 100, a Venturi tube 102, a gas introduction path 104, and a gas introduction valve 106. Water flows into the water inlet pipe 98 from the upstream side of the tank circulation path 92. The water outlet pipe 100 discharges water to the downstream side of the tank circulation path 92. The Venturi tube 102 connects the water inlet pipe 98 and the water outlet pipe 100. The diameter of the Venturi tube 102 is smaller than the diameters of the water inlet pipe 98 and the water outlet pipe 100. The water flowing through the gas introduction mechanism 96 is decompressed to a pressure lower than atmospheric pressure when it flows from the water inlet pipe 98 to the Venturi tube 102, and is then pressurized back to its original pressure when it flows from the Venturi tube 102 to the water outlet pipe 100. An upstream end of the gas introduction path 104 (hereinafter also referred to as a gas introduction port 104a) is open to the atmosphere, and a downstream end is connected to the Venturi tube 102. A gas introduction valve 106 is provided in the gas introduction path 104 and opens and closes the gas introduction path 104. When water flows through the gas introduction mechanism 96, if the gas introduction valve 106 is open, air is drawn into the gas introduction path 104 from the gas introduction port 104a, and the air is mixed with the water flowing through the Venturi tube 102. The air introduced through the gas introduction path 104 flows into the tank 52 together with the water flowing through the tank circulation path 92. The gas introduction valve 106 is normally kept in a closed state.

[0060] (Configuration of bathtub adapter 132) Next, the bathtub adapter 132 provided on the wall 130a of the bathtub 130 will be described with reference to Figures 9 and 10. Figure 9 shows the flow of water in the bathtub adapter 132 when water flows from the first bathtub water channel 62 toward the bathtub 130 and from the bathtub 130 toward the second bathtub water channel 70 (for example, the state shown in Figure 14). Figure 10 shows the flow of water in the bathtub adapter 132 when water flows from the bathtub 130 toward the first bathtub water channel 62 and from the second bathtub water channel 70 toward the bathtub 130 (for example, the state shown in Figure 12).

[0061] The bathtub adapter 132 has a first water passage 136 and a second water passage 138. The first water passage 136 is connected to the first bathtub water passage 62, and the second water passage 138 is connected to the second bathtub water passage 70. The first water passage 136 branches into a first discharge passage 136a and a first suction passage 136b. The first discharge passage 136a is connected to a first discharge port 134a provided on the front surface 132a of the bathtub adapter 132. Water discharged from the first discharge port 134a into the bathtub 130 is discharged in front of the wall 130a of the bathtub 130, i.e., in a direction perpendicular to the wall 130a of the bathtub 130. The first discharge passage 136a is provided with a check valve 140a that prevents water from flowing from the bathtub 130 toward the first bathtub water passage 62, and a fine-bubble generating nozzle 142 that is located upstream of the check valve 140a (toward the first bathtub water passage 62). The fine-bubble generating nozzle 142 reduces the pressure of the water passing through the fine-bubble generating nozzle 142. The first suction passage 136b is connected to a first suction port 134b that is provided on the front surface 132a of the bathtub adapter 132. The first suction passage 136b is provided with a check valve 140b that prevents water from flowing from the first bathtub water passage 62 toward the bathtub 130.

[0062] The second water passage 138 branches into a second discharge passage 138a and a second suction passage 138b. The second suction passage 138b is connected to a second suction port 134c provided on the front surface 132a of the bathtub adapter 132. The second suction passage 138b is provided with a check valve 140c that prevents water from flowing from the second bathtub water passage 70 toward the bathtub 130. The second discharge passage 138a is connected to a second discharge port 134d provided on the underside 132b of the bathtub adapter 132. Water discharged from the second discharge port 134d is discharged downward, i.e., in a direction parallel to the wall 130a of the bathtub 130. The second discharge passage 138a is provided with a check valve 140d that prevents water from flowing from the bathtub 130 toward the second bathtub water passage 70.

[0063] (Configuration of control device 150) The control device 150 shown in Fig. 1 controls the operation of each component of the heat source unit 10 and the air pressurization dissolution unit 50. The control device 150 is configured to be able to communicate with a remote control 154 that can be operated by the user. The control device 150 is equipped with a memory 152, and is capable of storing various settings input by the user, such as the set temperature and set water volume for the water filling operation, and the set temperature for the reheating operation. The user can use the remote control 154 to instruct the start and end of the water filling operation, reheating operation, and fine bubble generation operation, which will be described later.

[0064] (Bath filling operation) The water filling operation starts when the user issues a command to start the water filling operation via the remote control 154. Alternatively, the user may set the start time of the water filling operation via the remote control 154, and the water filling operation may start when the control device 150 determines that the start time has arrived. When starting the water filling operation, the control device 150 sets the first three-way valve 80 and the second three-way valve 82 to the third and fifth communication states, respectively (see Figures 11 and 12). When the water filling operation starts, the control device 150 opens the water filling valve 26 and starts heating using the first heat source unit 12. As a result, as shown in Figure 11, water adjusted to the set temperature flows from the hot water outlet path 18 through the hot water inlet path 24 into the circulation return path 32. The water that flows into the circulation return path 32 branches into a flow heading upstream (i.e., the heat source return path 60) and a flow heading downstream (i.e., the second heat source unit 14). Water flowing from the circulation return path 32 to the heat source return path 60 flows into the bathtub 130 via the connecting passage 66, the first three-way valve 80, the first bathtub water passage 62, and the bathtub adapter 132. Water flowing from the circulation return path 32 to the second heat source unit 14 flows into the bathtub 130 via the circulation outward path 30, the heat source outward path 68, the second three-way valve 82, the second bathtub water passage 70, and the bathtub adapter 132. The control device 150 waits until the accumulated water volume detected by the water volume sensor 28 reaches the set water volume for the bath filling operation. Note that the accumulated water volume here refers to the accumulated water volume detected by the water volume sensor 28 since the bath filling operation began. When the accumulated water volume reaches the set water volume, the control device 150 closes the bath filling valve 26 and stops heating the water by the first heat source unit 12. Thereafter, the control device 150 notifies the user via the remote control 154 that the water filling operation has been completed, and ends the water filling operation.

[0065] (Reheating operation) The reheating operation starts when the user issues a command to start the reheating operation via the remote control 154. Alternatively, the reheating operation may start when the control device 150 determines that the temperature detected by the circulation return thermistor 32a is lower than the set temperature after the first heat source unit 12 has finished heating water during the bath filling operation. When starting the reheating operation, the control device 150 sets the first three-way valve 80 to the third communication state and the second three-way valve 82 to the fifth communication state (see FIGS. 11 and 12). From this state, the control device 150 drives the bathtub circulation pump 34 and starts heating water with the second heat source unit 14. As a result, as shown in FIG. 12, water in the bathtub 130 is sent to the second heat source unit 14 via the bathtub adapter 132, the first bathtub water passage 62, the first three-way valve 80, the communication passage 66, the heat source return path 60, and the circulation return path 32. The water heated by the second heat source unit 14 is returned to the bathtub 130 via the circulation outward path 30, the heat source outward path 68, the second three-way valve 82, the second bathtub water passage 70, and the bathtub adapter 132. When the temperature detected by the circulation return thermistor 32a reaches or exceeds the set temperature, the control device 150 stops the bathtub circulation pump 34 and terminates the heating of water by the second heat source unit 14. The control device 150 then notifies the user via the remote control 154 that the reheating operation has been completed, and terminates the reheating operation.

[0066] (Fine bubble generation operation) The micro-bubble generating operation is started when the user issues a command to start the micro-bubble generating operation via the remote control 154. In addition, in the hot water heating device 2 of this embodiment, the micro-bubble generating operation also starts automatically after the above-mentioned water filling operation is completed. In other words, the micro-bubble generating operation is executed in conjunction with the execution of the water filling operation. When starting the micro-bubble generating operation, the control device 150 sets the first three-way valve 80 and the second three-way valve 82 to the third communication state and the fifth communication state, respectively (see Figures 11 and 12). In addition, the control device 150 sets the tank water supply valve 86 to an open state. From this state, the control device 150 executes the processing shown in Figure 13.

[0067] In S2, the control device 150 drives the tank circulation pump 94. This causes water to circulate between the tank 52 and the tank circulation path 92.

[0068] In S4, the control device 150 starts the first air introduction operation. Specifically, the control device 150 opens the gas introduction valve 106. During the first air introduction operation, air is introduced into the water flowing through the gas introduction mechanism 96 of the tank circulation path 92.

[0069] In S6, the control device 150 starts the pressurized water supply operation. Specifically, as shown in FIG. 14, the control device 150 sets the first three-way valve 80 to the first communication state and the second three-way valve 82 to the fourth communication state, and then drives the bathtub circulation pump 34, the first pressurized pump 88, and the second pressurized pump 90. During the pressurized water supply operation, water from the bathtub 130 is supplied to the tank 52 via the bathtub adapter 132, the second bathtub water passage 70, the second three-way valve 82, the communication passage 66, the heat source return path 60, the circulation return path 32, the second heat source unit 14, the circulation outward path 30, the heat source outward path 68, and the tank return path 74. At this time, water pressurized by the first pressurized pump 88 and the second pressurized pump 90 is supplied to the tank 52 from the tank return path 74. This causes air to be pressurized and dissolved in the water inside the tank 52. The water with the air dissolved under pressure is then supplied to the bathtub 130 from the tank 52 via the tank outbound line 64, the first three-way valve 80, the first bathtub water line 62, and the bathtub adapter 132. At this time, the water with the air dissolved under pressure is decompressed to below atmospheric pressure as it passes through the fine bubble generating nozzle 142 of the first discharge line 136a of the bathtub adapter 132, and the pressure is increased to atmospheric pressure when it is sprayed into the bathtub 130, generating fine bubbles in the water in the bathtub 130.

[0070] In S8, the control device 150 determines whether the water level in the tank 52 is below the first water level based on the detection signal from the low water level electrode 54b. In this embodiment, the amount of air introduced into the gas introduction mechanism 96 when the gas introduction valve 106 is open is greater than the amount of air in the fine bubbles generated in the water in the bathtub 130. Therefore, when the gas introduction valve 106 is open, the amount of air in the tank 52 increases, and the water level in the tank 52 drops. If the water level in the tank 52 is equal to or higher than the first water level (NO), the process proceeds to S12. If the water level in the tank 52 is below the first water level (YES), the process proceeds to S10.

[0071] In S10, if the first air introduction operation is being performed, the control device 150 stops the first air introduction operation. Specifically, the control device 150 closes the gas introduction valve 106. This stops the introduction of air into the water flowing through the gas introduction mechanism 96 of the tank circulation path 92. With the gas introduction valve 106 closed, no air is supplied to the tank 52, so the amount of air in the tank 52 decreases and the water level in the tank 52 rises. Note that in this embodiment, the tank circulation pump 94 continues to be driven even while the gas introduction valve 106 is closed. This promotes the flow of water in the tank 52 and promotes the pressurized dissolution of air into the water in the tank 52.

[0072] In S12, the control device 150 determines whether the water level in the tank 52 is equal to or higher than the second water level based on the detection signal from the high water level electrode 54a. If the water level in the tank 52 is lower than the second water level (NO), the process proceeds to S16. If the water level in the tank 52 is equal to or higher than the second water level (YES), the process proceeds to S14.

[0073] In S14, if the first air introduction operation has been stopped, the control device 150 starts the first air introduction operation, thereby restarting the introduction of air into the water flowing through the gas introduction mechanism 96 of the tank circulation path 92.

[0074] In S16, the control device 150 determines whether the operating time of the fine bubble generating operation has reached the set time. Here, the operating time of the fine bubble generating operation is the time elapsed since the start of the fine bubble generating operation. In the hot water heating device 2 of this embodiment, if the fine bubble generating operation is performed independently without being linked to the execution of the hot water filling operation, the set time is set to, for example, 10 minutes. In contrast, if the fine bubble generating operation is performed in conjunction with the execution of the hot water filling operation, the set time is set to, for example, 30 minutes. If the operating time has not reached the set time (if NO), the process returns to S8. If the operating time has reached the set time (if YES), the process proceeds to S18.

[0075] In S18, the control device 150 stops the pressurized water supply operation. Specifically, the control device 150 stops the bathtub circulation pump 34, the first pressurizing pump 88, and the second pressurizing pump 90.

[0076] In S20, if the first air introduction operation is being performed, the control device 150 stops the first air introduction operation.

[0077] In S22, the control device 150 stops the tank circulation pump 94. This stops the circulation of water between the tank 52 and the tank circulation path 92. After S22, the processing of FIG. 13 ends.

[0078] Thus, in the hot water apparatus 2 of this embodiment, the control device 150 is configured to control the operation of the gas introduction mechanism 96 during the fine-bubble generating operation using the high water level electrode 54a and the low water level electrode 54b so that the water level in the tank 52 changes between the first water level and the second water level. Furthermore, when the first gas introduction operation is performed during the pressurized water supply operation during the fine-bubble generating operation, the control device 150 is configured to perform the first gas introduction operation without interrupting the pressurized water supply operation.

[0079] Example 2 As shown in Fig. 15, the water heating apparatus 2A of this embodiment has substantially the same configuration as the water heating apparatus 2 of Example 1. In the water heating apparatus 2A, the air pressurization dissolution unit 50 has a tank 72 instead of the tank 52. Furthermore, in the water heating apparatus 2A, when performing the fine bubble generation operation, the control device 150 executes the process shown in Fig. 19 instead of executing the process shown in Fig. 13. Below, differences between the tank 72 and the tank 52 and differences between the process shown in Fig. 19 and the process shown in Fig. 13 will be described.

[0080] (Differences between Tank 72 and Tank 52) 16, tank 72 has tank upper part 720 instead of tank upper part 520. Tank upper part 720 has electrode installation part 740 instead of electrode installation part 540. Electrode unit 754 is installed in electrode installation part 740 instead of electrode unit 54.

[0081] The electrode unit 754 includes a single water level electrode 754a and a ground electrode 754b. The single water level electrode 754a and the ground electrode 754b extend vertically inside the tank 72 but outside the mixing case 4. When the single water level electrode 754a comes into contact with the surface of the water stored in the tank 72, a current flows between the single water level electrode 754a and the ground electrode 754b, and an ON signal is output to the control device 150. In other words, the single water level electrode 754a is configured to detect whether the water level in the tank 72 is equal to or higher than a predetermined water level. Hereinafter, the water level in the tank 72 detected by the single water level electrode 754a may be referred to as the "third water level." The lower end of the single water level electrode 754a is located higher than the lower end of the mixing case 4. Therefore, the third water level is located higher than the lower end of the mixing case 4.

[0082] 17, the single water level electrode 754a is covered by the electrode cover 446. On the other hand, the earth electrode 754b is not covered by the electrode cover 446. The lower end of the electrode cover 446 is located lower than the lower end of the single water level electrode 754a and the lower end of the earth electrode 754b. The lower end of the electrode cover 446 is also located lower than the lower end of the mixing case 4.

[0083] As shown in FIG. 18, when the electrode cover 446 is viewed from below, the electrode cover 446 covers the entire periphery of the single water level electrode 754a.

[0084] (Differences between the process shown in FIG. 19 and the process shown in FIG. 13) In the process shown in Figure 19, after S6, the process proceeds to S32. In S32, the control device 150 determines whether the water level in the tank 72 is below the third water level based on whether or not an ON signal is output from the single water level electrode 754a. If the water level in the tank 72 is equal to or higher than the third water level (NO), the process repeats S32. If the water level in the tank 72 is below the third water level (YES), the process proceeds to S10. Then, after S10, the process proceeds to S34.

[0085] In S34, the control device 150 starts timing the time for the water level to rise using a built-in timer (not shown). After S34, the process proceeds to S36.

[0086] In S36, the control device 150 determines whether the water level rise time, which began to be measured in S34, exceeds a first predetermined time (e.g., 90 seconds). If the water level rise time is equal to or less than the first predetermined time (NO), the process repeats S36. If the water level rise time exceeds the first predetermined time (YES), the process proceeds to S38.

[0087] In S38, the control device 150 ends the measurement of the water level rise time using a built-in timer (not shown). After S38, the process proceeds to S14.

[0088] Thus, in the water heating apparatus 2A, the control device 150 is configured to control the operation of the gas introduction mechanism 96 using the single water level electrode 754a during the fine bubble generation operation so that the water level in the tank 72 is maintained at or above the third water level. Furthermore, when the first gas introduction operation is performed during the pressurized water supply operation during the fine bubble generation operation, the control device 150 is configured to perform the first gas introduction operation without interrupting the pressurized water supply operation.

[0089] Example 3 As shown in FIG. 20 , the water heating apparatus 2B of this embodiment has substantially the same configuration as the water heating apparatus 2 of Example 1. In the water heating apparatus 2B, the air pressure dissolution unit 50 has a tank 352 instead of the tank 52. The tank 352 does not have the circulation opening 92a of the tank 52. The tank 352 has a third water supply port 374 instead of the first water supply port 74a and the second water supply port 74b of the tank 52. The third water supply port 374 is connected to the downstream end of the tank return line 74. Furthermore, in the water heating apparatus 2B, the air pressure dissolution unit 50 has a gas introduction path 300 and an air pump 302 instead of the tank circulation path 92, the tank circulation pump 94, and the gas introduction mechanism 96. The upstream end of the gas introduction path 300 (hereinafter also referred to as the gas introduction port 300a) is open to the atmosphere, and the downstream end is connected to the tank 52. The air pump 302 is provided in the gas introduction path 300. When the air pump 302 is driven, air is introduced into the tank 52 through the gas introduction path 300.

[0090] Furthermore, in the water heating device 2B, when the fine bubble generating operation is performed, the control device 150 executes the process shown in FIG. 21 instead of executing the process shown in FIG.

[0091] 21, in S52, the control device 150 starts the second air introduction operation. Specifically, the control device 150 sets the first three-way valve 80 and the second three-way valve 82 to the second communication state and the fifth communication state (see FIG. 20), respectively, and then drives the air pump 302. During the second air introduction operation, air is introduced into the tank 352 through the gas introduction path 300.

[0092] In S54, the control device 150 determines whether the water level in the tank 352 is below the first water level based on the detection signal from the low water level electrode 54b. When the second air introduction operation is performed while the pressurized water supply operation described below is stopped, the amount of air in the tank 352 increases, causing the water level in the tank 352 to drop. If the water level in the tank 352 is equal to or higher than the first water level (NO), the process proceeds to S60. If the water level in the tank 352 is below the first water level (YES), the process proceeds to S56.

[0093] In S56, if the second air introduction operation is being performed, the control device 150 stops the second air introduction operation. Specifically, the control device 150 stops the air pump 302. This stops the introduction of air into the tank 352.

[0094] In S58, if the pressurized water supply operation is stopped, the control device 150 starts the pressurized water supply operation. Specifically, as shown in Fig. 22, the control device 150 sets the first three-way valve 80 and the second three-way valve 82 to the first communication state and the fourth communication state, respectively, and then drives the bathtub circulation pump 34, the first pressurized pump 88, and the second pressurized pump 90. This promotes the pressurized dissolution of air into the water in the tank 352 and starts the supply of air-dissolved water from the tank 352 to the bathtub 130. Note that with the second air introduction operation stopped, no air is supplied to the tank 352, so the amount of air in the tank 352 decreases and the water level in the tank 352 rises.

[0095] In S60, the control device 150 determines whether the water level in the tank 352 is equal to or higher than the second water level based on the detection signal from the high water level electrode 54a. If the water level in the tank 352 is lower than the second water level (NO), the process proceeds to S66. If the water level in the tank 352 is equal to or higher than the second water level (YES), the process proceeds to S62.

[0096] In S62, if the second air introduction operation has been stopped, the control device 150 starts the second air introduction operation, thereby restarting the introduction of air into the tank 352.

[0097] In S64, if the pressurized water supply operation is being performed, the control device 150 stops the pressurized water supply operation. This stops the supply of air-dissolved water from the tank 352 to the bathtub 130. Furthermore, because the second air introduction operation is performed with the pressurized water supply operation stopped, the water level in the tank 352 drops.

[0098] In S66, the control device 150 determines whether the operation time of the fine bubble generating operation has reached the set time. If the operation time has not reached the set time (NO), the process returns to S54. If the operation time has reached the set time (YES), the process proceeds to S68.

[0099] In S68, if the pressurized water supply operation is being performed, the control device 150 stops the pressurized water supply operation.

[0100] In S70, if the second air introduction operation is being performed, the control device 150 stops the second air introduction operation. After S70, the processing in FIG.

[0101] Thus, in the water heating apparatus 2B, the control device 150 is configured to use the high water level electrode 54a and the low water level electrode 54b to control the operation of the air pump 302 during the fine bubble generation operation so that the water level in the tank 352 fluctuates between the first water level and the second water level. Furthermore, when the second air introduction operation is performed during the pressurized water supply operation during the fine bubble generation operation, the control device 150 is configured to interrupt the pressurized water supply operation when the second air introduction operation starts, and to resume the interrupted pressurized water supply operation when the second air introduction operation is stopped.

[0102] In the water heating apparatus 2B, the tank 352 may be equipped with the electrode unit 754 of the second embodiment instead of the electrode unit 54. In this case, the control device 150 may be configured to control the operation of the air pump 302 using a single water level electrode 754a during the fine-bubble generating operation so that the water level in the tank 352 is maintained at or above the third water level. In this case, when the second air introduction operation is performed during the pressurized water supply operation during the fine-bubble generating operation, the control device 150 may be configured to interrupt the pressurized water supply operation when the second air introduction operation is started and to resume the interrupted pressurized water supply operation when the second air introduction operation is stopped.

[0103] (Variation) In the above-described water heating apparatus 2 (or water heating apparatus 2A, water heating apparatus 2B), air is introduced into tank 52 (or tank 72, tank 352), but instead of air, a gas such as carbon dioxide, hydrogen, or oxygen may be introduced into tank 52 (or tank 72, tank 352). In this case, a gas-filled tank (not shown) filled with gas may be connected to gas inlet 104a of gas introduction path 104 (or gas inlet 300a of gas introduction path 300).

[0104] In the above-described hot water apparatus 2 (or hot water apparatus 2A, hot water apparatus 2B), the heat source unit 10 is connected to the faucet 250, and the pressurized air dissolving unit 50 is connected to the bathtub 130. In other embodiments, the heat source unit 10 may be connected to another place where heat is used, or the pressurized air dissolving unit 50 may be connected to another liquid tank.

[0105] In the above-described water heating apparatus 2 (or water heating apparatus 2A), the drain outlet 64a and the circulation opening 92a are provided on the lower surface of the tank lower portion 522 and open downward. In another embodiment, the drain outlet 64a and the circulation opening 92a do not have to be provided on the lower surface of the tank lower portion 522, and do not have to open downward. For example, at least one of the drain outlet 64a and the circulation opening 92a may be provided on a side surface of the tank lower portion 522 and may open horizontally.

[0106] In the above-described water heating device 2 (or water heating device 2A, water heating device 2B), the plate-shaped member 406 is seamlessly and integrally formed with the first side wall portion 402. In another embodiment, the plate-shaped member 406 may be provided separately from the first side wall portion 402.

[0107] In the above-described water heating device 2 (or water heating device 2A, water heating device 2B), the plate-shaped member 406 is provided along the horizontal direction. In another embodiment, the plate-shaped member 406 does not have to be provided along the horizontal direction. For example, the plate-shaped member 406 may be provided along a plane that is inclined with respect to the horizontal direction.

[0108] In the above-described water heating device 2 (or water heating device 2A, water heating device 2B), the plate-like member 406 is a flat plate having a generally fan-shaped configuration centered on axis A. In another embodiment, the plate-like member 406 does not have to have a generally fan-shaped configuration centered on axis A, and does not have to be a flat plate. For example, the plate-like member 406 may be a flat plate having a generally circular configuration centered on axis A, or a plate having a generally fan-shaped configuration centered on axis A and curving upward toward the circumferential end of axis A.

[0109] In the above-described water heating apparatus 2 (or water heating apparatus 2A, water heating apparatus 2B), the plate-shaped member 406 abuts against the case mounting portion 550 of the tank lower portion 522 from above. In other words, the plate-shaped member 406 protrudes radially outward in the direction of the axis A beyond the inner surface of the tank lower portion 522. In another embodiment, the plate-shaped member 406 does not have to protrude radially outward in the direction of the axis A beyond the inner surface of the tank lower portion 522.

[0110] In the water heating apparatus 2 (or the water heating apparatus 2A or 2B), the electrode cover 446 is seamlessly and integrally formed with the upper plate portion 440, the enlarged diameter portion 442, and the side plate portion 444. In another embodiment, the electrode cover 446 may be provided separately from the upper plate portion 440, the enlarged diameter portion 442, and the side plate portion 444. In yet another embodiment, a portion of the electrode cover 446 may be formed by the inner surface of the tank 52 (or the tank 72 or the tank 352), and the remaining portion of the electrode cover 446 may be seamlessly and integrally formed with the upper plate portion 440, the enlarged diameter portion 442, and the side plate portion 444. In this case, too, the electrode cover 446 may cover the entire periphery of the high water level electrode 54a (or a single water level electrode 754a) when viewed from below.

[0111] In the water heating device 2 (or water heating device 2B) described above, the electrode cover 446 covers only the high water level electrode 54a. In another embodiment, the electrode cover 446 may cover at least one of the high water level electrode 54a, the low water level electrode 54b, and the ground electrode 54c. For example, the electrode cover 446 may cover both the high water level electrode 54a and the low water level electrode 54b.

[0112] In the water heating device 2A described above, the electrode cover 446 covers only the single water level electrode 754a. In another embodiment, the electrode cover 446 may cover both the single water level electrode 754a and the ground electrode 754b.

[0113] In the above-mentioned water heating device 2 (or water heating device 2A, water heating device 2B), water level electrodes for detecting the water level in the tank 52 (or tank 72, tank 352) may be provided other than the high water level electrode 54a and the low water level electrode 54b (or a single water level electrode 754a).

[0114] The lengths of the high water level electrode 54a and the low water level electrode 54b (or the single water level electrode 754a) in the above-described water heating device 2 (or the water heating device 2A, the water heating device 2B) may be changed as appropriate. That is, the first water level and the second water level (or the third water level) in the above-described water heating device 2 may be changed as appropriate.

[0115] In the above-described water heating device 2 (or water heating device 2A), the gas introduction mechanism 96 is disposed upstream of the tank circulation pump 94 in the tank circulation path 92. In another embodiment, the gas introduction mechanism 96 may be disposed downstream of the tank circulation pump 94 in the tank circulation path 92.

[0116] In the above-described hot water device 2 (or hot water device 2A), the downstream end of the tank circulation path 92 is connected to the tank return path 74 downstream of the second pressure pump 90. In another embodiment, the downstream end of the tank circulation path 92 does not have to be connected to the tank return path 74, and may be provided separately from the tank return path 74 for the tank 52 (or tank 72).

[0117] In the above-described water heating device 2 (or water heating device 2A, water heating device 2B), during the bath filling operation, a set amount of water is stored in bathtub 130 based on the cumulative water volume detected by water volume sensor 28. In another embodiment, water heating device 2 (or water heating device 2A, water heating device 2B) may be configured to be provided with a water level sensor that can detect the water level in bathtub 130, and during the bath filling operation, water up to the set level is stored in bathtub 130 based on the water level in bathtub 130 detected by the water level sensor.

[0118] In the water heating apparatus 2 (or the water heating apparatus 2A, the water heating apparatus 2B) described above, the user may be able to switch via the remote control 154 whether or not to perform the fine bubble generating operation in conjunction with the execution of the water filling operation.

[0119] In the above-described water heating apparatus 2 (or water heating apparatus 2A, water heating apparatus 2B), the control device 150 terminates the fine bubble generating operation when the operating time of the fine bubble generating operation reaches the set time (YES in S16 of FIG. 13, YES in S16 of FIG. 19, or YES in S66 of FIG. 21). In another embodiment, the control device 150 may terminate the fine bubble generating operation even if the operating time of the fine bubble generating operation has not reached the set time. For example, the control device 150 may terminate the fine bubble generating operation when the user instructs the end of the fine bubble generating operation via the remote control 154.

[0120] The first predetermined time period in the water heating device 2A and the set time period for stopping the fine bubble operation in the water heating device 2 (or the water heating device 2A, the water heating device 2B) may be changed as appropriate.

[0121] (Correspondence) As described above, in one or more embodiments, the water heater 2 (or the water heater 2A or the water heater 2B) (an example of a micro-bubble generator) includes the tank 52 (or the tank 72 or the tank 352) having the first water supply port 74a and the second water supply port 74b (or the third water supply port 374) (an example of a supply port) and the drain port 64a (an example of a drain port), the mixing case 4 that is accommodated in the tank 52 (or the tank 72 or the tank 352) and that pressurizes and dissolves air (an example of gas) in the tank 52 (or the tank 72 or the tank 352) in water (an example of a liquid), and the first water supply port 74a. a tank return path 74 (an example of a supply path) that supplies water to the first water inlet 74a and the second water inlet 74b (or the third water inlet 374), an inlet pipe 46 (an example of an inlet path) that introduces the water supplied to the first water inlet 74a and the second water inlet 74b (or the third water inlet 374) into the mixing case 4, a tank outward path 64 (an example of a discharge path) that discharges water stored in the tank 52 (or the tank 72, the tank 352) from the drain port 64a to the bathtub 130 (an example of a liquid tank), and a micro-bubble generating nozzle 142 that is provided in the tank outward path 64 and generates micro-bubbles by decompressing the water in which air has been pressurized and dissolved. The tank 52 (or the tank 72, the tank 352) has a substantially cylindrical inner surface centered on an axis A (an example of a first axis) that runs in the vertical direction. The case body 40 of the mixing case 4 comprises a first bottom plate portion 400 (an example of a bottom plate portion) having an approximately circular plate shape extending horizontally, a first side wall portion 402 (an example of a side wall portion) extending upward from the peripheral portion of the first bottom plate portion 400 and having an approximately cylindrical outer surface centered on axis A (an example of a second axis that is approximately the same axis as the first axis), a stirring portion 42 that stirs water and air introduced into the case body 40 of the mixing case 4, a first outlet portion 404a (an example of an outlet portion) formed by cutting out the upper end portion of the first side wall portion 402, and a plate-like member 406 provided in a part of the first side wall portion 402 along the circumferential direction of axis A and protruding from the outer surface of the first side wall portion 402 radially outward of axis A. Water supplied to the first water inlet 74a and the second water inlet 74b (or the third water inlet 374) is introduced into the mixing case 4, flows out of the mixing case 4 from the first outlet 404a, and is then guided to the drain outlet 64a. The plate-shaped member 406 is disposed below the first outlet 404a and above the drain outlet 64a.

[0122] According to the above configuration, the water flowing out from the first outlet 404a of the mixing case 4 flows downward along the outer surface of the mixing case 4 and hits the plate-shaped member 406. The water that hits the plate-shaped member 406 changes direction so that it flows approximately horizontally along the plate-shaped member 406. The change in direction of the water by the plate-shaped member 406 slows the water down. When the water slows down, undissolved air (an example of undissolved gas) contained in the water is separated from the water. This makes it possible to reduce the amount of undissolved air contained in the water that is guided to the drain outlet 64a.

[0123] In one or more embodiments, when the case body 40 of the mixing case 4 is viewed from above along the axis A, the distance in the circumferential direction of the axis A from the centroid of the plate-shaped member 406 to the centroid of the first outlet portion 404a is less than the distance in the circumferential direction of the axis A from the centroid of the plate-shaped member 406 to the centroid of the drain outlet 64a.

[0124] When the case body 40 of the mixing case 4 is viewed from above along the axis A, if the distance in the circumferential direction of the axis A from the centroid of the plate-shaped member 406 to the centroid of the first outlet portion 404a is greater than the distance in the circumferential direction of the axis A from the centroid of the plate-shaped member 406 to the centroid of the drain outlet 64a, there is a possibility that the water flowing out from the first outlet portion 404a of the mixing case 4 will be guided to the drain outlet 64a without colliding with the plate-shaped member 406. According to the above configuration, the water flowing out from the first outlet portion 404a of the mixing case 4 can be made to more reliably collide with the plate-shaped member 406. Therefore, the amount of undissolved air contained in the water guided to the drain outlet 64a can be more reliably reduced.

[0125] In one or more embodiments, when the case body 40 of the mixing case 4 is viewed from above along the axis A, the portion of the first side wall portion 402 where the plate-like member 406 is provided overlaps the entire portion (at least some examples) of the first side wall portion 402 where the first outlet portion 404a is provided.

[0126] Normally, most of the water flowing out from the first outlet 404a of the mixing case 4 flows directly below the first outlet 404a due to gravity. With the above configuration, all of the water flowing directly below the first outlet 404a can be made to collide with the plate-shaped member 406. This makes it possible to efficiently reduce the amount of undissolved air contained in the water led to the drain port 64a.

[0127] In one or more embodiments, when the case body 40 of the mixing case 4 is viewed from above along the axis A, the portion of the first side wall portion 402 where the plate-like member 406 is provided overlaps the entire portion of the first side wall portion 402 where the first outlet portion 404a is provided.

[0128] According to the above configuration, all of the water flowing directly below the first outlet portion 404a can be caused to collide with the plate-shaped member 406. Therefore, the amount of undissolved air contained in the water guided to the drain outlet 64a can be more efficiently reduced.

[0129] In one or more embodiments, when the lower tank portion 522 of the tank 52 (or tank 72, tank 352) is viewed from above along the axis A, the drain port 64a is positioned so as not to overlap with the axis A.

[0130] The first outlet 404a of the mixing case 4 is provided at a position that does not overlap with the axis A. Therefore, when the drain outlet 64a is arranged at a position that does not overlap with the axis A, water from which undissolved air has been separated by the plate-shaped member 406 is more likely to be guided to the drain outlet 64a. According to the above configuration, water from which undissolved air has been separated by the plate-shaped member 406 is more likely to be guided to the drain outlet 64a. Therefore, the amount of undissolved air contained in the water guided to the drain outlet 64a can be efficiently reduced.

[0131] In one or more embodiments, the tank 52 (or the tank 72) further includes a circulation opening 92a that is provided separately from the drain opening 64a. The water heater 2 (or the water heater 2A) further includes a tank circulation path 92 that sends water stored in the tank 52 (or the tank 72) from the circulation opening 92a to the second water supply port 74b. The tank circulation path 92 includes a Venturi tube 102 (an example of a pressure reducing section) that reduces the pressure of the water and allows it to pass through, and a gas inlet 104a that introduces air by using the negative pressure of the water in the Venturi tube 102. The plate-like member 406 is positioned above the circulation opening 92a.

[0132] The water heating apparatus 2 (or the water heating apparatus 2A) may be configured to introduce air into the tank 52 (or the tank 72) by providing a tank circulation path 92 that circulates water in the tank 52 (or the tank 72), and by introducing air by using the negative pressure of the water in a Venturi tube 102 of the tank circulation path 92. In this case, if undissolved air is introduced into the circulation opening 92a together with the water, the negative pressure of the water in the Venturi tube 102 may decrease, and the amount of introduced air may decrease. For this reason, in the water heating apparatus 2 (or the water heating apparatus 2A), it may be desirable to reduce the amount of undissolved air contained in the water introduced into the circulation opening 92a. With the above configuration, the undissolved air contained in the water flowing out from the first outlet 404a of the mixing case 4 is decelerated by the plate-shaped member 406. When the water is decelerated, the undissolved air contained in the water is separated from the water. Therefore, the amount of undissolved air contained in the water introduced into the circulation opening 92a can be reduced.

[0133] In one or more embodiments, when the tank lower portion 522 of the tank 52 (or tank 72) is viewed from above along the axis A, the circulation opening 92a is positioned so as not to overlap with the axis A.

[0134] When the circulation opening 92a is positioned so as not to overlap with the axis A, the water from which undissolved air has been separated by the plate-shaped member 406 is more likely to be guided to the circulation opening 92a. According to the above configuration, the water from which undissolved air has been separated by the plate-shaped member 406 is more likely to be guided to the circulation opening 92a. This makes it possible to efficiently reduce the amount of undissolved air contained in the water guided to the circulation opening 92a.

[0135] In one or more embodiments, when the tank lower portion 522 of the tank 52 (or tank 72) and the case body 40 of the mixing case 4 are viewed from above along the axis A, a portion of the circulation opening 92a is positioned between the inner surface of the tank 52 (or tank 72) and the outer surface of the first side wall portion 402.

[0136] The plate-shaped member 406 is provided between the inner surface of the tank 52 (or tank 72) and the outer surface of the first side wall portion 402. According to the above configuration, the water from which undissolved air has been separated by the plate-shaped member 406 is more easily guided to the circulation opening 92a. Therefore, the amount of undissolved air contained in the water guided to the circulation opening 92a can be more efficiently reduced.

[0137] In one or more embodiments, the plate-like member 406 is seamlessly and integrally formed with the first sidewall portion 402 .

[0138] In the manufacturing process of the hot water device 2 (or the hot water device 2A, the hot water device 2B), there are cases where it is desired to reduce the number of parts that make up the mixing case 4. According to the above configuration, the number of parts that make up the mixing case 4 can be reduced compared to when the plate-shaped member 406 is separately attached to the first side wall portion 402.

[0139] In one or more embodiments, the liquid is water. The liquid reservoir is a bathtub 130 that a user uses to bathe.

[0140] According to the above configuration, in the hot water device 2 (or the hot water device 2A, the hot water device 2B) that generates fine bubbles in the water of the bathtub 130 used by the user for bathing, the amount of undissolved air contained in the water led to the drain outlet 64a can be reduced.

[0141] Although the embodiments have been described in detail above, they are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives alone has technical utility. [Explanation of symbols]

[0142] 2, 2A, 2B: Hot water device 4: Mixed case 10: Heat source unit 12: 1st heat source machine 14:Second heat source machine 16: Water supply channel 18: Hot water outlet 18a: Outlet water temperature thermistor 20: Bypass road 22: Bypass servo 24: Pouring channel 26: Valve 28: Water volume sensor 30: Circulation route 30a: Circulation outward thermistor 32: Circulation return route 32a: Circulation return thermistor 34: Bathtub circulation pump 36: Water flow switch 40: Case body 42: Stirring section 44: Case lid 46:Introduction tube 50: Air pressure dissolving unit 52, 72, 352: Tank 54, 754: Electrode unit 54a: High water level electrode 54b: Low water level electrode 54c, 754b: Earth electrode 60: Return route to heat source 62: First bathtub waterway 64:Tank outbound 64a: Drain port 66:Communication path 68:Heat source outward route 70: Second bathtub waterway 74: Tank return trip 74a: 1st water supply port 74b: 2nd water supply port 80: First three-way valve 82: Second three-way valve 84: Check valve 86: Tank water supply valve 88: First pressure pump 90: Second pressure pump 92: Tank circulation path 92a: Circulation opening 94: Tank circulation pump 96: Gas introduction mechanism 98: Water inlet pipe 100: Outlet pipe 102: Venturi tube 104: Gas introduction path 104a: Gas inlet 106: Gas introduction valve 130: Bathtub 130a: Wall part 132: Bathtub adapter 132a:Front 132b: Bottom surface 134a: 1st discharge port 134b: First intake port 134c: Second intake port 134d: 2nd discharge port 136: 1st waterway 136a: 1st discharge path 136b: First intake passage 138: 2nd waterway 138a: Second discharge path 138b: Second intake passage 140a, 140b, 140c, 140d: check valves 142: Microbubble generating nozzle 150: Control device 152: Memory 154: Remote control 200: Water source 250: Karan 300: Gas introduction path 300a: Gas inlet 302: Air pump 374: 3rd water supply port 400: 1st bottom plate part 402: First side wall portion 404: Multiple Outlets 404a: First outflow section 404b:Second outlet 404c: 3rd outlet 404d: 4th outlet 406: Plate-shaped members 408: Multiple mounting members 408a: First mounting member 408b: Second mounting member 408c: Third mounting member 420: 2nd bottom plate part 422: Second side wall 424: Insertion tube 425: spout 426: Fitting member 428: Flange part 440: Upper plate 442: Expanded diameter part 444: Side plate part 446: Electrode cover 520, 720: Top of tank 522: Lower part of tank 540, 740: Electrode installation part 550: Case installation section 754a: Single water level electrode

Claims

1. a tank having a supply inlet and a discharge outlet; a mixing case accommodated in the tank and dissolving the gas in the tank into the liquid under pressure; a supply channel for supplying the liquid to the supply port; an introduction path that introduces the liquid supplied to the supply port into the mixing case; a discharge path that discharges the liquid stored in the tank from the discharge port to a liquid tank; a micro-bubble generating nozzle provided in the discharge path for generating micro-bubbles by decompressing the liquid in which the gas is pressurized and dissolved, The tank has a substantially cylindrical inner surface centered on a first axis along a vertical direction, The mixed case is A bottom plate portion having a substantially circular plate shape that extends horizontally; a sidewall portion extending upward from a peripheral edge portion of the bottom plate portion and having a substantially cylindrical outer surface centered on a second axis that is substantially the same as the first axis; a mixing unit that mixes the liquid and the gas introduced into the mixing case; an outflow portion formed by cutting out an upper end portion of the side wall portion; a plate-like member provided on a part of the side wall portion along the circumferential direction of the second shaft and protruding from an outer surface of the side wall portion toward the outside in the radial direction of the second shaft, The liquid supplied to the supply port is introduced into the mixing case, flows out of the mixing case from the outflow portion, and is guided to the discharge port, The micro-bubble generating device, wherein the plate-like member is disposed below the outflow portion and above the discharge port.

2. When the mixing case is viewed from above along the second axis, 2. The micro-bubble generating device of claim 1, wherein the distance in the circumferential direction of the second axis from the centroid of the plate-like member to the centroid of the outflow portion is smaller than the distance in the circumferential direction of the second axis from the centroid of the plate-like member to the centroid of the discharge port.

3. 3. The fine-bubble generating device of claim 1, wherein, when the mixing case is viewed from above along the second axis, the portion of the side wall where the plate-like member is provided overlaps with at least a portion of the portion of the side wall where the outflow portion is provided.

4. 4. The micro-bubble generating device of claim 3, wherein when the mixing case is viewed from above along the second axis, the portion of the side wall where the plate-like member is provided overlaps the entire portion of the side wall where the outflow portion is provided.

5. 5. The micro-bubble generating device according to claim 1, wherein the outlet is positioned so as not to overlap with the second axis when the tank is viewed from above along the second axis.

6. The tank further includes a circulation opening provided separately from the discharge port, a circulation path that sends the liquid stored in the tank from the circulation opening to the supply port, The circulation path is a pressure reducing section that reduces the pressure of the liquid and passes it through; a gas inlet port that introduces the gas by negative pressure of the liquid in the pressure reducing section, The micro-bubble generating device according to claim 1 , wherein the plate-like member is disposed above the circulation opening.

7. 7. The micro-bubble generating device according to claim 6, wherein the circulation opening is disposed at a position that does not overlap with the second axis when the tank is viewed from above along the second axis.

8. 8. The fine-bubble generating device of claim 6, wherein when the tank and the mixing case are viewed from above along the second axis, a portion of the circulation opening is positioned between the inner surface of the tank and the outer surface of the side wall portion.

9. The micro-bubble generating device according to claim 1 , wherein the plate-like member is formed seamlessly and integrally with the side wall portion.

10. the liquid is water, The fine-bubble generator according to claim 1 , wherein the liquid tank is a bathtub used by a user for bathing.

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