Gas-liquid dissolution device and micro-bubble generation system

Abstract

To provide a technique capable of both accurately detecting a liquid level using an electrode and keeping the electrode clean.SOLUTION: A gas-liquid dissolution device may comprise: a gas-liquid dissolver that dissolves gas into a liquid; a tank that houses the gas-liquid dissolver and stores the liquid in which gas has been dissolved by the gas-liquid dissolver; an electrode that extends vertically inside the tank and detects a liquid level of the liquid stored in the tank; and a cover portion that covers the electrode. The cover portion is switched between a first state and a second state.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a gas-liquid dissolving device and a microbubble generating system. [Background technology]

[0002] Patent Document 1 discloses a gas-liquid dissolving device that includes a gas-liquid dissolver that dissolves gas in liquid, a tank that houses the gas-liquid dissolver and stores the liquid into which the gas has been dissolved by the gas-liquid dissolver, an electrode that extends vertically inside the tank and detects the level of the liquid stored inside the tank, and a cover that covers the electrode. The cover is fixed in position relative to the tank. [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] Suppressing rippling of the liquid surface near an electrode inside a tank allows the electrode to accurately detect the liquid level stored inside the tank. Meanwhile, rippling near the electrode washes away dirt near the electrode (dirt adhering to the electrode or dirt adhering to the inner wall of the tank near the electrode), thereby providing the advantage of keeping the area near the electrode clean. If dirt accumulates near the electrode, the dirt may cause electrical conduction between the electrode and the liquid, potentially resulting in an erroneous detection of the liquid level. Therefore, keeping the area near the electrode clean also helps prevent erroneous detection of the liquid level. In conventional gas-liquid dissolving devices, the likelihood of rippling near the electrode is generally constant, making it difficult to accurately detect the liquid level using the electrode and to keep the electrode clean. This specification provides a technology that enables both accurate detection of the liquid level using the electrode and keeping the electrode clean. [Means for solving the problem]

[0005] A gas-liquid dissolving device disclosed as a first aspect of the present technology may include a gas-liquid dissolver that dissolves gas in liquid, a tank that houses the gas-liquid dissolver and stores the liquid into which the gas has been dissolved by the gas-liquid dissolver, an electrode that extends vertically inside the tank and detects the level of the liquid stored inside the tank, and a cover that covers the electrode, wherein the cover is switchable between a first state and a second state.

[0006] According to the above configuration, by switching the state of the cover, it is possible to change the likelihood of rippling occurring near the electrode. As a result, for example, when liquid level detection by the electrode is required, by making it less likely that rippling will occur near the electrode, it is possible to accurately detect the liquid level by the electrode. When liquid level detection by the electrode is not required, by making it more likely that rippling will occur near the electrode, it is possible to actively wash away dirt near the electrode. Therefore, according to the above configuration, it is possible to accurately detect the liquid level by the electrode and keep the electrode clean at the same time.

[0007] In a second aspect of the present technology, in the first aspect, the space inside the tank covered by the cover part may be defined as a covered space. The cover part may be configured such that when the cover part is in the second state, it is more difficult for liquid to flow into the cover space from outside compared to when the cover part is in the first state.

[0008] According to the above configuration, when the cover unit is in the first state, liquid flows more easily from the outside of the cover space to the inside, making it easier for rippling to occur near the electrode. On the other hand, when the cover unit is in the second state, liquid flows less easily from the outside of the cover space to the inside, making it easier for rippling to occur near the electrode. Therefore, for example, when liquid level detection using an electrode is required, switching the cover unit to the second state can make it harder for rippling to occur near the electrode, allowing for accurate detection of the liquid level using the electrode. When liquid level detection using an electrode is not required, switching the cover unit to the first state can make it easier for rippling to occur near the electrode, making it easier to actively wash away dirt near the electrode. Furthermore, according to the above configuration, dirt near the electrode can also be washed away by liquid flowing from the outside of the cover space into the inside and splashing on the electrode. Therefore, according to the above configuration, it is possible to accurately detect the liquid level using the electrode and keep the electrode clean at the same time.

[0009] In a third aspect of the present technology, in the second aspect, the cover may include an inlet communicating the inside and the outside of the cover space, and the cover may be configured such that an opening area of ​​the inlet is smaller when the cover is in the second state than when the cover is in the first state.

[0010] According to the above configuration, when the cover unit is in the first state, the opening area of ​​the inlet is increased, making it easier for liquid to flow from the outside of the cover space to the inside, and making it easier for rippling to occur near the electrode. On the other hand, when the cover unit is in the second state, the opening area of ​​the inlet is reduced, making it harder for liquid to flow from the outside of the cover space to the inside, and making it easier for rippling to occur near the electrode. Therefore, for example, when liquid level detection using an electrode is required, switching the cover unit to the second state can make it easier for rippling to occur near the electrode, allowing for accurate detection of the liquid level using the electrode. When liquid level detection using an electrode is not required, switching the cover unit to the first state can make it easier for rippling to occur near the electrode, and dirt near the electrode can be actively washed away.

[0011] According to a fourth aspect of the present technology, in the third aspect, when the cover portion is in the first state, an upper end of the inlet may be disposed higher than a lower end of the electrode.

[0012] According to the above configuration, when the cover is in the first state, the liquid flowing into the inlet is more likely to splash onto the electrode, thereby more significantly washing away dirt near the electrode.

[0013] In a fifth aspect of the present technology, in the third or fourth aspect, the cover unit may include a cover member that covers the electrode, an opening formed by penetrating the cover member and functioning as the inlet, and a shielding unit whose attitude with respect to the opening is variable between a first attitude and a second attitude that shields the opening more than the first attitude and reduces the opening area of ​​the inlet. The first state may be a state in which the attitude of the shielding unit with respect to the opening is the first attitude. The second state may be a state in which the attitude of the shielding unit with respect to the opening is the second attitude.

[0014] According to the above configuration, the cover can increase or decrease the opening area of ​​the inlet by changing the attitude of the shielding part relative to the opening, thereby changing the ease with which liquid flows from the outside to the inside of the cover space and changing the ease with which rippling occurs near the electrode. In this way, the ease with which rippling occurs near the electrode can be changed using a relatively simple mechanism.

[0015] According to a sixth aspect of the present technology, in the fifth aspect, the shielding portion may be fixed in position relative to the tank. The cover member may be provided movable relative to the tank between a first position where the shielding portion has the first position relative to the opening and a second position where the shielding portion has the second position relative to the opening. The first state may be a state where the cover member moves to the first position. The second state may be a state where the cover member moves to the second position.

[0016] In order to change the position of the shielding part relative to the opening, it is possible to change the positions of both the cover member and the shielding part relative to the tank. However, in this case, the number of parts whose positions change relative to the tank increases, which may increase the restrictions on the layout and shape of each part inside the tank. With the above configuration, the position of the shielding part relative to the tank is fixed, so the layout of the shielding part relative to the opening can be changed simply by changing the position of the cover member relative to the tank. This reduces the number of parts whose positions change relative to the tank, and reduces the restrictions on the layout and shape of each part inside the tank.

[0017] In a seventh aspect of the present technology, in the sixth aspect, internal pressure of the tank may act on the cover member to urge the cover member toward one of the first position and the second position. When the internal pressure of the tank increases, the cover member may move to one of the first position and the second position. When the internal pressure of the tank decreases, the cover member may move to the other of the first position and the second position.

[0018] It is also possible to use an actuator such as a motor to change the position of the cover member relative to the tank. However, in this case, the number of electrical components installed in the gas-liquid dissolving device increases, which may increase the manufacturing cost of the gas-liquid dissolving device. With the above configuration, the position of the cover member relative to the tank can be changed by utilizing pressure fluctuations inside the tank. This reduces the number of electrical components installed in the gas-liquid dissolving device and reduces the manufacturing cost of the gas-liquid dissolving device.

[0019] In an eighth aspect of the present technology, in the fourth aspect, the cover unit may include a cover member that covers the electrode; an opening formed by penetrating the cover member and functioning as the inlet; and a shielding unit whose attitude with respect to the opening is displaced between a first attitude and a second attitude in which the shielding unit shields the opening more than the first attitude and reduces the opening area of ​​the inlet. The shielding unit may be fixed in position with respect to the tank. The cover member may be provided movable with respect to the tank between a first position where the attitude of the shielding unit with respect to the opening is the first attitude and a second position where the attitude of the shielding unit with respect to the opening is the second attitude. Pressure inside the tank may act on the cover member to urge the cover member toward one of the first position and the second position. The cover member may move to one of the first position and the second position when pressure inside the tank increases. The cover member may move to the other of the first position and the second position when pressure inside the tank decreases. The first state may be a state in which the cover member moves to the first position, and the second state may be a state in which the cover member moves to the second position.

[0020] According to the above configuration, the cover can increase or decrease the opening area of ​​the inlet by changing the position of the shielding part relative to the opening, thereby changing the ease with which liquid flows from the outside to the inside of the covered space and changing the likelihood of rippling near the electrode. In this way, the likelihood of rippling near the electrode can be changed using a relatively simple mechanism. It is also possible to change the position of both the cover member and the shielding part relative to the tank in order to change the position of the shielding part relative to the opening. However, this increases the number of components whose positions change relative to the tank, which may increase the constraints on the layout and shape of each component inside the tank. According to the above configuration, the position of the shielding part relative to the tank is fixed, so the position of the shielding part relative to the opening can be changed simply by changing the position of the cover member relative to the tank. This reduces the number of components whose positions change relative to the tank and reduces the constraints on the layout and shape of each component inside the tank. It is also possible to use an actuator such as a motor to change the position of the cover member relative to the tank. However, this increases the number of electrical components required in the gas-liquid dissolving device, which may increase the manufacturing cost of the device. According to the above configuration, the position of the cover member relative to the tank can be changed by utilizing pressure fluctuations inside the tank, which reduces the number of electrical components required in the gas-liquid dissolving device and reduces the manufacturing cost of the gas-liquid dissolving device.

[0021] A micro-bubble generating system disclosed as a ninth aspect of the present technology may include the gas-liquid dissolving device of any one of the first to eighth aspects, a first flow path for sending water stored in a liquid tank to the tank, a second flow path for sending water stored in the tank to the liquid tank, a pump provided in the first flow path for pressurizing water flowing through the first flow path toward the tank, a micro-bubble generating nozzle provided in the second flow path for generating micro-bubbles by depressurizing water containing dissolved gas, and a control device capable of executing a micro-bubble generating operation by operating the pump to send the water stored in the liquid tank to the tank via the first flow path and to send the water stored in the tank to the liquid tank via the second flow path. The control device may be configured to interrupt or terminate the micro-bubble generating operation when the electrode detects that the water level of the water stored in the tank is equal to or higher than a predetermined level during the micro-bubble generating operation. The cover may be in the second state while the micro-bubble generating operation is being performed.

[0022] During the micro-bubble generating operation, as gas dissolves in the water in the tank, the amount of gas in the tank may decrease, causing the water level in the tank to rise. In this case, continuing the micro-bubble generating operation may result in an insufficient amount of gas being dissolved in the water in the tank, resulting in a decrease in the amount of micro-bubbles generated by the micro-bubble generating nozzle. With the above configuration, when the electrode detects that the water level in the tank is above a predetermined level during the micro-bubble generating operation, the micro-bubble generating operation is interrupted or terminated, preventing a shortage of gas dissolved in the water in the tank. However, with this configuration, severe rippling may occur near the electrode, and if the electrode detects a water level that is excessively higher than the actual water level in the tank, the micro-bubble generating operation may be interrupted or terminated prematurely. In other words, the micro-bubble generating operation may be interrupted or terminated before a sufficient amount of micro-bubbles is supplied to the bathtub. According to the above configuration, the cover is in the second state during the micro-bubble generating operation, reducing the likelihood of rippling near the electrode. This prevents the electrodes from detecting a water level that is excessively higher than the actual water level in the tank, and prevents the micro-bubble generating operation from being interrupted or terminated prematurely, thereby allowing a sufficient amount of micro-bubbles to be supplied to the bathtub.

[0023] In a tenth aspect of the present technology, the micro-bubble generating system of the ninth aspect may further include a tank water supply line that sends water supplied from a water supply source to the tank, and a water supply mechanism provided in the tank water supply line that is switchable between a water supply allowable state that allows water to be supplied from the water supply source to the tank and a water supply prohibited state that prohibits water from being supplied from the water supply source to the tank. The control device may be capable of switching the water supply mechanism to the water supply allowable state to perform a tank cleaning operation in which water supplied from the water supply source is sent to the tank via the tank water supply line. When the tank cleaning operation is being performed, the cover may be in the first state.

[0024] According to the above configuration, by performing the tank cleaning operation, the inside of the tank can be cleaned using clean water supplied from the water supply source. Furthermore, according to the above configuration, during the tank cleaning operation, the cover is in the first state, which makes it easier for rippling to occur near the electrodes. This actively washes away dirt near the electrodes, thereby keeping the electrodes clean.

[0025] In an eleventh aspect of the present technology, in the ninth or tenth aspect, the micro-bubble generating system may further include a gas introduction device that introduces gas into the tank. The control device may be capable of operating the gas introduction device to perform a gas introduction operation that introduces gas into the tank. When the gas introduction operation is being performed, the cover may be in the first state.

[0026] During the gas introduction operation, the amount of gas in the tank increases as gas is introduced into the tank, which can cause the water level in the tank to drop. Therefore, in the above configuration, which uses an electrode to detect whether the water level in the tank is above a predetermined level, detecting the water level using the electrode is unnecessary during the gas introduction operation. According to the above configuration, when the cover unit is in the first state during the gas introduction operation, rippling is likely to occur near the electrode. This allows dirt near the electrode to be actively washed away when detecting the water level using the electrode is unnecessary. This allows the electrode to be kept clean. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a diagram showing a schematic configuration of a bath system 2 according to an embodiment. [Figure 2] FIG. 2 is an exploded view of a gas-liquid dissolving device 42 according to an embodiment. [Figure 3] 4 is a diagram schematically showing the flow of water in a tank 44 of a gas-liquid dissolving device 42 according to the embodiment. FIG. [Figure 4] FIG. 10 is a perspective view of a cover member 184 according to the embodiment. [Figure 5]10 is an enlarged cross-sectional view of the cover portion 186 according to the embodiment, showing a state in which the cover member 184 is in a lowered position. FIG. [Figure 6] 10 is an enlarged cross-sectional view of the cover portion 186 according to the embodiment, showing a state in which the cover member 184 is in a raised position. FIG. [Figure 7] 7 is a cross-sectional view taken along line VII-VII in FIG. 3, showing the cover portion 186 according to the embodiment with the cover member 184 in the lowered position. [Figure 8] 7 is a cross-sectional view taken along line VII-VII in FIG. 3, showing the cover portion 186 according to the embodiment with the cover member 184 in the raised position. [Figure 9] 1 is a diagram showing a schematic configuration of a bathtub adapter 132 according to an embodiment. [Figure 10] 10 is a diagram showing a schematic view of the flow of water when a bath filling operation is being performed in the bath system 2 according to the embodiment. FIG. [Figure 11] 10 is a diagram showing a schematic view of the flow of water when a reheating operation is being performed in the bath system 2 according to the embodiment. FIG. [Figure 12] 10 is a diagram showing a schematic view of the flow of water when a gas introduction operation is being performed in the bath system 2 according to the embodiment. FIG. [Figure 13] 10 is a diagram showing a schematic view of the flow of water when a fine bubble generating operation is being performed in the bath system 2 according to the embodiment. FIG. [Figure 14] 10 is a diagram showing a schematic view of the flow of water when a tank cleaning operation is being performed in the bath system 2 according to the embodiment. FIG. [Figure 15] This is a schematic diagram showing the inside of the tank 44 of a bath system 2 according to a modified example in horizontal cross section. [Figure 16] This is a schematic diagram showing the inside of the tank 44 of a bath system 2 according to another modified example, viewed in horizontal cross section. [Figure 17] FIG. 10 is a schematic diagram showing the interior of the tank 44 of a bath system 2 according to yet another modified example, viewed in horizontal cross section. DETAILED DESCRIPTION OF THE INVENTION

[0028] (Example: Bath System 2) As shown in Figure 1, the bath system 2 includes a heat source unit 10, a gas-liquid dissolving unit 40, a bathtub adapter 132, and a control device 150. The bath system 2 heats water supplied from a water supply source 4, such as a tap, and supplies the water heated to a desired temperature to a faucet 6 installed in a kitchen or the like, or to a bathtub 130 installed in a bathroom. The bath system 2 can also generate fine bubbles in the water in the bathtub 130 that a user uses for bathing.

[0029] (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 passage 16, a hot water outlet passage 18, a bypass passage 20, a bypass servo 22, a hot water inlet passage 24, a hot water filling valve 26, a water volume sensor 28, a forward circulation passage 30, a return circulation passage 32, a circulation pump 34, and a water flow switch 36.

[0030] The upstream end of water supply passage 16 is connected to water supply source 4, 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 6. 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.

[0031] 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, and water adjusted to a desired temperature is supplied. 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.

[0032] 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.

[0033] 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 gas-liquid dissolving unit 40, 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 gas-liquid dissolving unit 40. 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. An outgoing 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.

[0034] The circulation pump 34 is provided in the return circulation path 32 between the connection point of the molten metal pouring path 24 and the second heat source device 14, and sends the water in the return circulation path 32 toward the second heat source device 14. The water flow switch 36 is provided in the return circulation path 32 between the circulation pump 34 and the second heat source device 14, and detects whether water is flowing in the return circulation path 32.

[0035] (Configuration of the gas-liquid dissolving unit 40) The gas-liquid dissolution unit 40 includes a gas-liquid dissolution device 42 including a tank 44, a heat source return line 60, a heat source forward line 68, a tank return line 74, a tank forward line 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 pressure pump 88, and a second pressure pump 90.

[0036] 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 the first three-way valve 80 and the 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. 13) in which the tank outbound passage 64 and the first bathtub water passage 62 are connected and the tank outbound passage 64 is not connected to the communication passage 66; a second communication state (see FIGS. 12 and 14) in which the tank outbound passage 64 is connected to the communication passage 66 and the tank outbound passage 64 is not connected to the first bathtub water passage 62; and a third communication state (see FIGS. 1, 10, and 11) in which the first bathtub water passage 62, the tank outbound passage 64, and the communication passage 66 are connected. The upstream end of the tank outbound passage 64 is connected to a tank drain port 64a provided in the tank 44, and the downstream end of the tank outbound passage 64 is connected to the first three-way valve 80. The tank outbound line 64 is provided with a check valve 84 that allows water to flow from the tank 44 toward the first three-way valve 80 and prohibits water from flowing from the first three-way valve 80 toward the tank 44. One end of the first bathtub water line 62 is connected to the first three-way valve 80, and the other end of the first bathtub water line 62 is connected to the bathtub adapter 132.

[0037] 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 be switched between a fourth communication state (see Figures 13 and 14) in which the second bathtub water passage 70 is connected to the communication passage 66 and the second bathtub water passage 70 is not connected to the heat source outbound path 68, and a fifth communication state (see Figures 1, 10, 11, and 12) in which the second bathtub water passage 70 is connected to the heat source outbound path 68 and the second bathtub water passage 70 is not connected to the communication passage 66. 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 the bathtub adapter 132.

[0038] 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 a tank water supply port 74a provided in the tank 44. 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 44. 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 44. In the tank return line 74, the first pressurizing pump 88 is located upstream of the second pressurizing pump 90.

[0039] (Configuration of the gas-liquid dissolving device 42) The gas-liquid dissolving device 42 includes a tank 44, a gas introducing device 46 that introduces gas into the tank 44, a gas-liquid dissolver 48 that dissolves the gas in water, and electrodes 50a, 50b, and 50c that detect the water level in the tank 44.

[0040] The gas introduction device 46 includes a gas introduction path 52 and a gas introduction valve 54 that opens and closes the gas introduction path 52. One end of the gas introduction path 52 is open to the atmosphere, and the other end of the gas introduction path 52 is connected to the tank 44. Normally, the gas introduction valve 54 is closed, and the introduction of gas (air) into the tank 44 via the gas introduction path 52 is prohibited. When the gas introduction valve 54 is opened, the introduction of gas (air) into the tank 44 via the gas introduction path 52 is permitted.

[0041] Each of the electrodes 50a, 50b, and 50c extends vertically inside the tank 44. The electrodes 50a, 50b, and 50c include a low-water-level electrode 50a, a high-water-level electrode 50b, and an earth electrode 50c. Within the tank 44, the lower end of the earth electrode 50c is located lower than the lower ends of the low-water-level electrode 50a and the high-water-level electrode 50b. The lower end of the low-water-level electrode 50a is also located lower than the lower end of the high-water-level electrode 50b. Therefore, when the water level in the tank 44 rises, the water stored in the tank 44 first comes into contact with the earth electrode 50c, then with the low-water-level electrode 50a, and finally with the high-water-level electrode 50b.

[0042] The low water level electrode 50a can detect whether the water level in the tank 44 has reached or exceeded a predetermined low water level (the position of the lower end of the low water level electrode 50a). Specifically, when the water level in the tank 44 reaches or exceeded the low water level (the position of the lower end of the low water level electrode 50a), electrical continuity is established between the low water level electrode 50a and the earth electrode 50c via the water stored in the tank 44. This generates a low water level electrical signal between the low water level electrode 50a and the earth electrode 50c, indicating that the water level in the tank 44 has reached or exceeded the low water level. The low water level detection signal generated between the low water level electrode 50a and the earth electrode 50c (i.e., the detection result of the low water level electrode 50a) is output to the control device 150. Similarly, the high water level electrode 50b can detect whether the water level in the tank 44 has reached or exceeded a predetermined high water level (the position of the lower end of the high water level electrode 50b). Specifically, when the water level in the tank 44 reaches or exceeds the high water level (the position of the lower end of the high water level electrode 50b), electrical continuity is established between the high water level electrode 50b and the earth electrode 50c via the water stored in the tank 44. This generates a high water level electrical signal between the high water level electrode 50b and the earth electrode 50c, indicating that the water level in the tank 44 has reached or exceeded the high water level. The high water level detection signal generated between the high water level electrode 50b and the earth electrode 50c (i.e., the detection result at the high water level electrode 50b) is output to the control device 150.

[0043] As shown in FIG. 2, the tank 44 includes a tank upper portion 160 and a tank lower portion 162. The tank upper portion 160 and the tank lower portion 162 are fixed to each other with screws. The tank upper portion 160 is formed with a tank water supply port 74a to which the downstream end of the tank return path 74 (see FIG. 1) is connected. The tank lower portion 162 is formed with a tank drain port 64a to which the upstream end of the tank outward path 64 (see FIG. 1) is connected. The electrodes 50a, 50b, 50c and the gas introducing device 46 are attached to the tank upper portion 160. The gas-liquid dissolver 48 is housed inside the tank 44.

[0044] The gas-liquid dissolver 48 includes an inlet pipe 168, an inner case 170, an outer case 172, and a case lid 174. The inlet pipe 168 is attached to the inner case 170 by being inserted into an insertion pipe 176 formed in the inner case 170. The inlet pipe 168 introduces water supplied to the tank water supply port 74a in the tank upper portion 160 into the inner case 170. As shown in FIG. 3 , the inner case 170 is supported by the outer case 172 so as to be positioned inside the outer case 172. The case lid 174 is supported by the inner case 170 so as to cover the upper parts of the inner case 170 and the outer case 172.

[0045] (Water flow in tank 44) Water supplied from the tank water supply port 74a is introduced into the interior of the inner case 170 via the inlet pipe 168. The water introduced into the interior of the inner case 170 flows downward while swirling in a spiral within the interior of the inner case 170. When the water swirls within the interior of the inner case 170, a large negative pressure is generated near the center of the inner case 170. This negative pressure causes air within the tank 44 to be drawn into the interior of the inner case 170 through a communication hole 178 formed in the case lid 174. The air drawn into the interior of the inner case 170 is entrained in the water swirling within the interior of the inner case 170. This causes the air to dissolve in the water, producing aerated water. The aerated water produced within the interior of the inner case 170 is ejected downward from an ejection port 180 that vertically penetrates the bottom of the inner case 170. The aerated water ejected from the ejection port 180 hits the bottom of the outer case 172, changes direction so that it flows radially outward from the outer case 172, then hits the inner wall of the outer case 172, changes direction so that it flows upward, and flows upward along the inner wall of the outer case 172. The aerated water flowing upward along the inner wall of the outer case 172 flows out of the outer case 172 through multiple cutouts 182 formed in the side wall of the outer case 172. The aerated water that flows out from the multiple cutouts 182 is stored in the tank 44. The water stored in the tank 44 is discharged from the tank drain outlet 64a. Note that in FIG. 3, for the sake of explanation, the flow of water is indicated by solid arrows.

[0046] (Configuration of cover part 186) The gas-liquid dissolving device 42 further includes a cover member 184 that covers the high water level electrode 50b together with the cover surface 44a. The cover surface 44a is part of the inner surface of the tank 44. In this embodiment, the cover surface 44a and the cover member 184 are collectively referred to as a cover portion 186. The space covered by the cover portion 186 (i.e., the cover surface 44a and the cover member 184) is defined as a cover space 188.

[0047] 4, the cover member 184 includes a head portion 190 having a generally cylindrical shape, a cover body 192 extending downward from the head portion 190, and an opening 194 formed by penetrating the side wall of the cover body 192. The opening 194 is T-shaped. The head portion 190 also has an insertion hole 196 through which the high water level electrode 50b (see FIG. 3) is inserted, a circumferential groove 200 in which an O-ring 198 (see FIGS. 5 and 6) is attached, and a spring bearing surface 204 that receives a coil spring 202 (see FIGS. 5 and 6).

[0048] As shown in FIG. 5, the tank upper portion 160 is formed with a cylindrical portion 206 that receives the head portion 190 of the cover member 184 so that the head portion 190 can slide vertically, and a support surface 208 that supports the underside of the head portion 190. An electrode base 210 that supports the high water level electrode 50b is fixed to the upper end of the cylindrical portion 206. The high water level electrode 50b is inserted through an insertion opening 196 in the head portion 190 so that the lower portion of the high water level electrode 50b is positioned within the cover space 188. The insertion opening 196 slidably receives the high water level electrode 50b. This allows the cover member 184 to slide vertically relative to the high water level electrode 50b. The inner surface of the insertion opening 196 is in close contact with the high water level electrode 50b around the entire circumference, thereby sealing the gap between the insertion opening 196 and the high water level electrode 50b. An O-ring 198 attached to a circumferential groove 200 of the head 190 seals the gap between the outer surface of the head 190 and the inner surface of the tubular portion 206. This isolates an upper space 220, which the upper surface of the head 190 faces, from a lower space 222 (i.e., the interior of the tank 44), which the lower surface of the head 190 faces. As a result, a pressure difference occurs between the upper space 220 and the lower space 222 (the interior of the tank 44). The coil spring 202 is disposed between a spring bearing surface 204 of the head 190 and the lower surface of the electrode base 210. The coil spring 202 biases the cover member 184 downward relative to the electrode base 210. The biasing force of the coil spring 202 normally keeps the cover member 184 in a position where the lower surface of the head 190 abuts against the support surface 208 (also referred to as the lowered position). From this state, when the pressure in the lower space 222 (inside the tank 44) exceeds a predetermined pressure (for example, 200 kPa gauge pressure), the pressure difference between the upper space 220 and the lower space 222 causes the cover member 184 to rise against the biasing force of the coil spring 202. In this case, as shown in Fig. 6, the cover member 184 rises to a position (also referred to as a raised position) where the upper surface of the head 190 abuts against the support protrusion 212 formed on the lower surface of the electrode base 210.

[0049] A shielding wall 214 is formed in the tank upper portion 160, shielding an upper portion of the opening 194 of the cover member 184. A first inlet 216 is defined between the shielding wall 214 and the opening 194. The first inlet 216 communicates the interior and exterior of the covered space 188 and allows water to flow from the exterior of the covered space 188 to the interior of the covered space 188. As shown in FIGS. 7 and 8, when the cover member 184 moves from the lowered position (the position shown in FIG. 7) to the raised position (the position shown in FIG. 8), the opening 194 moves upward relative to the shielding wall 214, and the opening area of ​​the first inlet 216 decreases. In this case, it becomes difficult for water to flow from the exterior of the covered space 188 (see FIG. 3) to the interior through the first inlet 216. Conversely, when the cover member 184 moves from the raised position (the position shown in FIG. 8) to the lowered position (the position shown in FIG. 7), the opening 194 moves downward relative to the shielding wall 214, and the opening area of ​​the first inlet 216 increases. In this case, water can easily flow from the outside to the inside of the cover space 188 through the first inlet 216. This makes it easier for the water flowing into the first inlet 216 to splash on the high water level electrode 50b, making it easier to wash away dirt adhering to the high water level electrode 50b.

[0050] 3, a second inlet 218 is defined between the lower end of the cover member 184 and the cover surface 44a. The second inlet 218 communicates the inside and outside of the cover space 188 and allows water to flow from the outside to the inside of the cover space 188. The opening area of ​​the second inlet 218 is substantially constant regardless of the position of the cover member 184.

[0051] (Configuration of bathtub adapter 132) As shown in FIG. 9, 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.

[0052] 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.

[0053] (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 gas-liquid dissolving unit 40. 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 has a memory 152 and can store various settings input by the user, such as the set temperature and set water volume for the bath filling operation. The user can use the remote control 154 to instruct the start and end of the bath filling operation, reheating operation, and intermittent fine bubble supply operation, which will be described later. The remote control 154 has a speaker 156 that can output specified sounds. The bath filling operation, reheating operation, intermittent fine bubble supply operation (fine bubble generation operation and gas introduction operation), and tank cleaning operation, which are performed by the control device 150, are described below.

[0054] (Bath filling operation: Figure 10) The water filling operation starts when the user commands the start of the water filling operation using the remote control 154. Alternatively, the water filling operation starts when the user sets the start time of the water filling operation using the remote control 154 and 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. 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 FIG. 10 , 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 flowing into the circulation return path 32 branches into a flow toward the heat source return path 60 and a flow toward the second heat source unit 14. Water flowing from the return circulation 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 return circulation path 32 to the second heat source unit 14 flows into the bathtub 130 via the forward circulation path 30, the heat-source forward path 68, the second three-way valve 82, the second bathtub water passage 70, and the bathtub adapter 132. In the bathtub adapter 132 shown in FIG. 9, water from the first bathtub water passage 62 is discharged into the bathtub 130 via the first discharge passage 136a, and water from the second bathtub water passage 70 is discharged into the bathtub 130 via the second discharge passage 138a. The control device 150 shown in FIG. 10 waits until the accumulated water volume detected by the water volume sensor 28 reaches the set water volume for the bathtub filling operation. The accumulated water volume here refers to the accumulated water volume detected by the water volume sensor 28 since the bathtub filling operation began. When the accumulated water volume reaches the set water volume, the control device 150 closes the water filling valve 26 and stops heating the water by the first heat source unit 12. The control device 150 then notifies the user via the speaker 156 that the water filling operation has been completed, and ends the water filling operation.

[0055] (Reheating operation: Figure 11) The reheating operation is initiated when the user issues a command to start the reheating operation via the remote control 154. Alternatively, the reheating operation is initiated 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 and the second three-way valve 82 to the third and fifth communication states, respectively. From this state, the control device 150 drives the circulation pump 34 and starts heating water with the second heat source unit 14. As a result, as shown in FIG. 11 , water from 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 passage 60, and the circulation return passage 32. 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. In the bathtub adapter 132 shown in FIG. 9, water from the bathtub 130 is sucked into the first bathtub water passage 62 via the first suction passage 136b, and water from the second bathtub water passage 70 is discharged into the bathtub 130 via the second discharge passage 138a. When the temperature detected by the circulation return thermistor 32a reaches or exceeds the set temperature, the control device 150 shown in FIG. 11 stops the circulation pump 34 and terminates water heating by the second heat source unit 14. The control device 150 then notifies the user via the speaker 156 that the reheating operation has been completed, and terminates the reheating operation.

[0056] (Fine bubble intermittent supply operation) The intermittent fine bubble supply operation alternately performs a gas introduction operation, which introduces gas into the tank 44, and a fine bubble generation operation, which reduces the pressure of the water supplied from the tank 44 to the bathtub 130 to generate fine bubbles in the water in the bathtub 130. The intermittent fine bubble supply operation is started when the user issues a command to start the intermittent fine bubble supply operation using the remote control 154 while water is stored in the bathtub 130. Alternatively, the intermittent fine bubble supply operation is started in response to the completion of the bath filling operation. After the start of the intermittent fine bubble supply operation, when the number of times each of the gas introduction operation and the fine bubble generation operation has been performed reaches a predetermined number (e.g., five times), the control device 150 notifies the user via the speaker 156 that the intermittent fine bubble supply operation has been completed, and ends the intermittent fine bubble supply operation.

[0057] (Gas introduction operation: Figure 12) The gas introduction operation is initiated at the start of the intermittent fine-bubble supply operation and after the end of the fine-bubble generation operation. When starting the gas introduction operation, the control device 150 sets the first three-way valve 80 and the second three-way valve 82 to the second and fifth communication states, respectively. The control device 150 also opens the gas introduction valve 54, closes the tank water supply valve 86, and drives the circulation pump 34. As a result, as shown in FIG. 12 , water is sucked out of the tank 44 and air is introduced into the tank 44 via the gas introduction path 52. The water sucked out of the tank 44 flows into the bathtub 130 via the tank outflow path 64, the first three-way valve 80, the communication path 66, the heat source return path 60, the circulation return path 32, the second heat source unit 14, the circulation outflow path 30, the heat source outflow path 68, the second three-way valve 82, the second bathtub water path 70, and the bathtub adapter 132. In the bathtub adapter 132 shown in FIG. 9, water from the second bathtub water channel 70 is discharged into the bathtub 130 via the second discharge channel 138a. When the low water level detection signal from the low water level electrode 50a is no longer output (i.e., when the water level in the tank 44 falls below the low water level), the control device 150 shown in FIG. 12 closes the gas introduction valve 54 and opens the tank water supply valve 86. The control device 150 then ends the gas introduction operation. When the gas introduction operation ends, the circulation pump 34 remains driven. Note that while the gas introduction operation is being performed, the amount of air introduced into the tank 44 exceeds the amount of air dissolved in the water in the tank 44. Therefore, the water level in the tank 44 drops while the gas introduction operation is being performed.

[0058] (Fine bubble generation operation: Figure 13) The fine-bubble generating operation is initiated after the gas introduction operation is completed. When starting the fine-bubble generating operation, the control device 150 sets the first three-way valve 80 and the second three-way valve 82 to the first and fourth communication states, respectively. The control device 150 also opens the tank water supply valve 86 and drives the first pressurizing pump 88 and the second pressurizing pump 90 in addition to the circulation pump 34. As a result, as shown in FIG. 13 , water from the bathtub 130 is supplied to the tank 44 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 pressurizing pump 88 and the second pressurizing pump 90 is supplied to the tank 44 from the tank return path 74. As a result, air is pressurized and dissolved in the water inside the tank 44, producing aerated water. The aerated water is supplied from the tank 44 to the bathtub 130 via the tank outflow path 64, the first three-way valve 80, the first bathtub water passage 62, and the bathtub adapter 132. In the bathtub adapter 132 shown in FIG. 9, the water in the bathtub 130 is sucked into the second bathtub water passage 70 via the second suction passage 138b, and the water in the first bathtub water passage 62 (aerated water) passes through the first discharge passage 136a and is discharged into the bathtub 130. The aerated water is decompressed to below atmospheric pressure when passing through the fine-bubble generating nozzle 142 provided in the first discharge passage 136a, and is then pressurized to atmospheric pressure when discharged into the bathtub 130. As a result, fine bubbles are generated in the water in the bathtub 130. The control device 150 shown in FIG. 13 stops the first pressurizing pump 88 and the second pressurizing pump 90 when a high water level detection signal is output from the high water level electrode 50b (i.e., when the water level in the tank 44 reaches or exceeds the high water level). The control device 150 then ends the fine bubble generating operation. When the fine bubble generating operation ends, the circulation pump 34 remains driven. The circulation pump 34 is stopped when the intermittent fine bubble supply operation ends. Note that, since no air is introduced into the tank 44 during the fine bubble generating operation, the amount of air in the tank 44 decreases as air dissolves in the water in the tank 44. Therefore, the water level in the tank 44 rises during the fine bubble generating operation.

[0059] (Tank cleaning operation: Figure 14) The tank cleaning operation is an operation in which water from the water supply source 4 is supplied to the tank 44 and water stored in the tank 44 is discharged into the bathtub 130. The tank cleaning operation is started when the intermittent fine bubble supply operation ends. Alternatively, the tank cleaning operation is started every time a predetermined time (e.g., 40 hours) has elapsed since the end of the last tank cleaning operation. When starting the tank cleaning operation, 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 fourth communication state, respectively. The control device 150 also opens the water filling valve 26 and the tank water supply valve 86, and then starts heating using the first heat source unit 12. As a result, as shown in FIG. 14, water adjusted to the set temperature flows from the hot water outlet path 18 through the hot water filling path 24 and into the return circulation path 32. Water flowing into the circulation return path 32 branches into a flow toward the heat-source return path 60 and a flow toward 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 second three-way valve 82, the second bathtub water passage 70, and the bathtub adapter 132. Water flowing from the circulation return path 32 to the second heat source unit 14 is supplied to the tank 44 via the circulation outward path 30, the heat-source outward path 68, and the tank return path 74. Water from the tank 44 is discharged into the tank outward path 64 and then into the bathtub 130 via the first three-way valve 80, the connecting passage 66, the second three-way valve 82, the second bathtub water passage 70, and the bathtub adapter 132. In the bathtub adapter 132 shown in FIG. 9, water from the second bathtub water passage 70 is discharged into the bathtub 130 via the second discharge passage 138a. When the time that has elapsed since the start of the tank cleaning operation reaches a predetermined time (for example, 30 seconds), the control device 150 shown in Fig. 14 ends heating by the first heat source unit 12 and closes the water filling valve 26 and the tank water supply valve 86. Thereafter, the control device 150 ends the tank cleaning operation.

[0060] (Features of the Example) During the fine-bubble generating operation, the first pressurizing pump 88 and the second pressurizing pump 90 are driven, supplying high-pressure water into the tank 44. Furthermore, during the fine-bubble generating operation, a fine-bubble generating nozzle 142 with high flow resistance is disposed downstream of the tank 44. As a result, the pressure in the tank 44 increases during the fine-bubble generating operation, and as shown in FIGS. 6 and 8 , the cover member 184 moves to its raised position against the biasing force of the coil spring 202. In this case, the opening area of ​​the first inlet 216 decreases, making it difficult for water to flow from the outside to the inside of the cover space 188. This prevents severe rippling within the cover space 188. If severe rippling were to occur within the cover space 188 during the fine-bubble generating operation, the high-water-level electrode 50b would output a high-water-level detection signal even though the water level in the tank had not yet reached the high water level, potentially resulting in an early termination of the fine-bubble generating operation. In this case, there is a possibility that a sufficient amount of fine bubbles will not be supplied to the bathtub 130. In contrast, in this embodiment, the cover member 184 moves to the raised position during the fine bubble generating operation, thereby preventing the occurrence of severe rippling inside the cover space 188. This prevents the high water level electrode 50b from outputting a high water level detection signal even when the water level in the tank has not yet reached the high water level. This prevents the fine bubble generating operation from ending prematurely, allowing a sufficient amount of fine bubbles to be supplied to the bathtub 130.

[0061] On the other hand, during operations other than the microbubble generation operation (gas introduction operation and tank cleaning operation), the first pressurizing pump 88 and / or the second pressurizing pump 90 are stopped, and the pressure of the water supplied to the tank is relatively low. This causes the pressure inside the tank 44 to be low, and as shown in FIGS. 5 and 7 , the cover member 184 is held in the lowered position by the biasing force of the coil spring 202. In this case, the opening area of ​​the first inlet 216 increases, making it easier for water to flow from the outside to the inside of the cover space 188, which makes it easier for rippling to occur inside the cover space 188. Therefore, the water flowing from the outside to the inside of the cover space 188 and the rippling occurring inside the cover space 188 actively wash away dirt near the high water level electrode 50b (e.g., dirt adhering to the high water level electrode 50b, dirt adhering to the inner surface of the cover member 184, and dirt adhering to the cover surface 44a). This allows the high water level electrode 50b to be kept clean. In addition, in operations other than the fine bubble generation operation (gas introduction operation and tank cleaning operation), the control device 150 controls the bath system 2 regardless of the detection results at the high water level electrode 50b. Therefore, it is not a problem if severe rippling occurs inside the cover space 188 during operations other than the fine bubble generation operation (gas introduction operation and tank cleaning operation), which reduces the detection accuracy at the high water level electrode 50b.

[0062] (Variation) (See FIG. 1) The gas introducing device 46 may introduce a gas other than air (for example, carbon dioxide, hydrogen, or oxygen) into the tank 44. In this case, a gas tank filled with the gas may be connected to the gas introducing path 52.

[0063] As shown in Fig. 15, the cover section 186 may include, instead of the cover member 184, a cover member 284 that is rotatable around a predetermined axis (for example, the central axis of the high water level electrode 50b) relative to the tank 44. The cover member 284 may rotate between a position where an opening 294 formed in the cover member 284 is not covered (position (1) shown in Fig. 15) and a position where the opening 294 is covered by the cover surface 44a (position (2) shown in Fig. 15). This may change the ease with which water flows from the outside to the inside of the cover space 188 through the opening 294.

[0064] (See FIGS. 5 and 6) The gas-liquid dissolving device 42 may include an actuator (e.g., a motor, a solenoid) for moving the cover member 184 relative to the tank 44. In this case, the control device 150 may drive the actuator to move the cover member 184 to the raised position when starting the fine bubble generation operation. The control device 150 may also drive the actuator to move the cover member 184 to the lowered position when starting the gas introduction operation or the tank cleaning operation.

[0065] 16, the cover section 186 may include, instead of the cover member 184, a cover member 384 that is slidable in a direction other than downward (for example, horizontally) relative to the tank 44. The cover member 384 may slide between a position spaced apart from the cover surface 44a (position (1) shown in FIG. 16) and a position close to the cover surface 44a (position (2) shown in FIG. 16). This may change the ease with which water flows from the outside to the inside of the cover space 188.

[0066] As shown in Fig. 17, a shielding member 414 that is movable relative to the cover member 184 and the tank 44 may be disposed in a position facing the opening 194 of the cover member 184. The shielding member 414 may be movable between a position where it does not shield the opening 194 (position (1) shown in Fig. 17) and a position where it shields the opening 194 (position (2) shown in Fig. 17). This may change the ease with which water flows from the outside to the inside of the cover space 188 via the opening 194. In this case, the cover member 184 may be fixed to the tank 44.

[0067] (See FIG. 7) When the cover member 184 is in the lowered position, the upper end of the first inlet 216 (ie, the lower end of the shielding wall 214) may be positioned lower than the lower end of the high water level electrode 50b.

[0068] (See FIGS. 12 and 13) When a high water level detection signal is output from the high water level electrode 50b during the fine bubble generating operation, the control device 150 may reduce the output of the first pressurizing pump 88 and / or the second pressurizing pump 90 instead of stopping the first pressurizing pump 88 and / or the second pressurizing pump 90. In this case, the control device 150 may continue to drive the first pressurizing pump 88 and / or the second pressurizing pump 90 at low output during the gas introducing operation that is subsequently performed. Here, low output means an output that is sufficient to hold the cover member 184 in the lowered position.

[0069] The gas-liquid dissolving device 42 may further include a tank circulation path for circulating water in the tank 44, a tank circulation pump for pumping water through the tank circulation path, a Venturi tube provided midway through the tank circulation path, and an air introduction path connected to the Venturi tube. In this case, the control device 150 may further drive the tank circulation pump to circulate water in the tank 44 through the tank circulation path during the fine-bubble generation operation (see FIG. 13 ). As a result, during the fine-bubble generation operation, negative pressure generated when water flows through the Venturi tube may draw atmospheric air into the tank circulation path through the air introduction path, and the air may be sent into the tank 44 along with the water flowing through the tank circulation path. In the above configuration, air can be introduced into the tank 44 even during the fine-bubble generation operation, so the gas introduction operation described in the embodiment may be omitted. In other words, instead of performing the intermittent fine-bubble supply operation in which the fine-bubble generation operation and the gas introduction operation are alternately performed, the control device 150 may perform the continuous fine-bubble supply operation in which the fine-bubble generation operation is continuously performed.

[0070] The control device 150 does not have to be configured to be able to execute the tank cleaning operation.

[0071] (See FIG. 4) The opening 194 may be formed in a shape other than the T-shape (for example, an L-shape, a circle, or a rectangle).

[0072] (Correspondence) In the embodiments, the gas-liquid dissolving device 42 is an example of a "gas-liquid dissolving device." The gas-liquid dissolver 48 is an example of a "gas-liquid dissolver." The tank 44 is an example of a "tank." The high water level electrode 50b is an example of an "electrode." The cover portion 186 is an example of a "cover portion." The cover space 188 is an example of a "cover space." The first inlet 216 is an example of an "inlet." The cover members 184, 284, 384 are examples of "cover members." The openings 194, 294 are examples of "openings." The shielding wall 214 or the shielding member 414 is an example of a "shielding portion." The bath system 2 is an example of a "fine bubble generating system." The second bathtub water passage 70, the second three-way valve 82, the communication passage 66, the heat source return passage 60, the circulation return passage 32, the second heat source unit 14, the circulation outward passage 30, the heat source outward passage 68, and the tank return passage 74 are examples of a "first flow path." The tank outward passage 64, the first three-way valve 80, and the first bathtub water passage 62 are examples of a "second flow path." The first pressure pump 88 and the second pressure pump 90 are examples of a "pump." The fine bubble generating nozzle 142 is an example of a "fine bubble generating nozzle." The control device 150 is an example of a "control device." The water supply passage 16, the molten metal outlet passage 18, the molten metal pouring passage 24, the circulation return passage 32, the second heat source unit 14, the circulation outward passage 30, the heat source outward passage 68, and the tank return passage 74 are examples of a "tank water supply passage." The tank water supply valve 86 is an example of a "water supply mechanism." Gas introduction device 46 is an example of a "gas introduction device."

[0073] The technical elements described in this specification or drawings exhibit technical utility either alone or in various combinations, and are not limited to the combinations set forth in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of those objectives is itself technically useful. [Explanation of symbols]

[0074] 2: bath system, 4: water supply source, 6: faucet, 10: heat source unit, 12: first heat source unit, 14: second heat source unit, 16: water supply line, 18: hot water outlet line, 18a: hot water outlet temperature thermistor, 20: bypass line, 22: bypass servo, 24: hot water supply line, 26: valve, 28: water volume sensor, 30: circulation forward line, 30a: circulation forward line thermistor, 32: circulation return line, 32a: circulation return line thermistor, 34: circulation pump, 36: water flow switch, 40: gas-liquid dissolving unit, 42: gas-liquid dissolving device, 44: tank, 44a: cover surface, 46: gas introduction device, 48: gas-liquid dissolver, 50a : Low water level electrode, 50b: High water level electrode, 50c: Earth electrode, 52: Gas inlet path, 54: Gas inlet valve, 60: Heat source return path, 62: First bathtub water channel, 64: Tank outward path, 64a: Tank drain outlet, 66: Connecting passage, 68: Heat source return path, 70: Second bathtub water channel, 74: Tank return path, 74a: Tank 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, 130: Bathtub, 130a: Wall, 132: Bathtub adapter, 132a: Front surface, 132b: Bottom surface, 134a: First outlet, 134 b: first suction port, 134c: second suction port, 134d: second discharge port, 136: first water passage, 136a: first discharge passage, 136b: first suction passage, 138: second water passage, 138a: second discharge passage, 138b: second suction passage, 140a: non-return section, 140b: non-return section, 140c: non-return section, 140d: non-return section, 142: fine bubble generating nozzle, 150: control device, 152: memory, 154: remote control, 156: speaker, 160: upper tank section, 162: lower tank section, 168: introduction pipe, 170: inner case, 172: outer case, 174: case lid, 176: insertion pipe , 178: communication hole, 180: ejection port, 182: notch portion, 184: cover member, 186: cover portion, 188: cover space, 190: head portion, 192: cover body, 194: opening portion, 196: insertion hole, 198: O-ring, 200: circumferential groove, 202: coil spring, 204: spring receiving surface, 206: cylindrical portion, 208: support surface, 210: electrode base, 212: support protrusion, 214: shielding wall, 216: first inlet, 218: second inlet, 220: upper space, 222: lower space, 284: cover member, 294: opening portion, 384: cover member, 414: shielding member

Claims

1. a gas-liquid dissolver for dissolving a gas in a liquid; a tank that houses the gas-liquid dissolver and stores the liquid into which the gas has been dissolved by the gas-liquid dissolver; an electrode extending vertically inside the tank and configured to detect the level of the liquid stored inside the tank; a cover portion that covers the electrode, The gas-liquid dissolving device, wherein the cover portion is switchable between a first state and a second state.

2. The space inside the tank covered by the cover portion is defined as a cover space, The gas-liquid dissolving device of claim 1, wherein the cover portion is configured so that when the cover portion is in the second state, it is less likely for liquid to flow from the outside to the inside of the cover space than when the cover portion is in the first state.

3. The cover portion has an inlet that communicates the inside and the outside of the cover space, The gas-liquid dissolving device of claim 2, wherein the cover portion is configured such that the opening area of ​​the inlet is reduced when the cover portion is in the second state compared to when the cover portion is in the first state.

4. The gas-liquid dissolving apparatus according to claim 3 , wherein when the cover portion is in the first state, an upper end of the inlet is positioned higher than a lower end of the electrode.

5. The cover portion is a cover member that covers the electrode; an opening formed by penetrating the cover member and functioning as the inlet; a shielding portion whose attitude with respect to the opening is displaced between a first attitude and a second attitude in which the shielding portion shields the opening more than the first attitude and reduces the opening area of ​​the inlet, the first state is a state in which the attitude of the shielding part with respect to the opening is the first attitude, The gas-liquid dissolving device according to claim 3 , wherein the second state is a state in which the position of the shielding part relative to the opening is the second position.

6. The shielding portion is fixed in position relative to the tank, the cover member is provided to be movable with respect to the tank between a first position where the attitude of the shielding part with respect to the opening is the first attitude and a second position where the attitude of the shielding part with respect to the opening is the second attitude, the first state is a state in which the cover member moves to the first position, The gas-liquid dissolving device according to claim 5 , wherein the second state is a state in which the cover member moves to the second position.

7. pressure inside the tank acts on the cover member to urge the cover member toward one of the first position and the second position; When the pressure inside the tank increases, the cover member moves to one of the first position and the second position; 7. The gas-liquid dissolving device according to claim 6, wherein the cover member moves to the other of the first position and the second position when the pressure inside the tank decreases.

8. The cover portion is a cover member that covers the electrode; an opening formed by penetrating the cover member and functioning as the inlet; a shielding portion whose attitude with respect to the opening is displaced between a first attitude and a second attitude that shields the opening more than the first attitude and reduces the opening area of ​​the inlet, The shielding portion is fixed in position relative to the tank, the cover member is provided to be movable with respect to the tank between a first position where the attitude of the shielding part with respect to the opening is the first attitude and a second position where the attitude of the shielding part with respect to the opening is the second attitude, pressure inside the tank acts on the cover member to urge the cover member toward one of the first position and the second position; When the pressure inside the tank increases, the cover member moves to one of the first position and the second position; When the pressure inside the tank decreases, the cover member moves to the other of the first position and the second position, the first state is a state in which the cover member moves to the first position, The gas-liquid dissolving device according to claim 4 , wherein the second state is a state in which the cover member is moved to the second position.

9. The gas-liquid dissolving device according to any one of claims 1 to 8, a first flow path for sending water stored in a liquid tank to the tank; a second flow path that sends water stored inside the tank to the liquid tank; a pump provided in the first flow path to pump water flowing through the first flow path toward the tank; a microbubble generating nozzle provided in the second flow path, which generates microbubbles by reducing the pressure of water having gas dissolved therein; a control device capable of executing a microbubble generating operation by operating the pump to send the water stored in the liquid tank to the tank via the first flow path and to send the water stored inside the tank to the liquid tank via the second flow path, the control device is configured to interrupt or terminate the fine bubble generating operation when the electrode detects that the water level stored in the tank is equal to or higher than a predetermined water level during the fine bubble generating operation; A fine bubble generating system, wherein the cover portion is in the second state when the fine bubble generating operation is being performed.

10. a tank water supply line for delivering water supplied from a water supply source to the tank; a water supply mechanism that is provided in the tank water supply passage and that is switchable between a water supply permitted state that permits the supply of water from the water supply source to the tank and a water supply prohibited state that prohibits the supply of water from the water supply source to the tank, the control device is capable of switching the water supply mechanism to the water supply permitted state and executing a tank cleaning operation in which water supplied from the water supply source is sent to the tank via the tank water supply line, The fine bubble generating system according to claim 9, wherein the cover portion is in the first state when the tank cleaning operation is being performed.

11. The apparatus further includes a gas introduction device that introduces gas into the tank, the control device is capable of operating the gas introduction device to perform a gas introduction operation to introduce gas into the tank, The fine bubble generating system according to claim 9 , wherein the cover portion is in the first state when the gas introduction operation is being performed.

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