Microbubble generator

Abstract

To provide a technology which can continue to generate fine air bubbles in liquid in a liquid tank stably.SOLUTION: A fine air bubble generator includes: a tank; a tank supply passage; pressure pumps; a tank discharge passage; a fine air bubble generating nozzle provided at the tank discharge passage; a tank circulation passage; a tank circulation pump; a gas introduction mechanism provided at the tank circulation passage; and a controller. The gas introduction mechanism includes: a decompression part which decompresses liquid and allows the liquid to pass therethrough; and a gas introduction port for introducing a gas by a negative pressure of the liquid in the decompression part. The controller can conduct a fine air bubble generation operation in which the pressure pumps are driven to compress the liquid, supply the liquid from the tank supply passage to the tank, and supply the liquid, into which the gas is compressively dissolved, from the tank to the liquid tank through the tank discharge passage. When the fine air bubble generation operation is conducted, the tank circulation pump is driven to circulate the liquid in the tank at the tank circulation passage to supply the gas introduced by the gas introduction mechanism to the tank.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a microbubble generating device. [Background technology]

[0002] Patent Document 1 discloses a fine bubble generator including a tank for pressurizing and dissolving a gas in a liquid, a tank supply path for supplying the liquid to the tank, a pressure pump provided in the tank supply path, a tank discharge path for discharging the liquid in which the gas has been pressurized and dissolved from the tank to a liquid tank, a fine bubble generating nozzle provided in the tank discharge path for reducing the pressure of the liquid in which the gas has been pressurized and dissolved to generate fine bubbles, a gas introduction mechanism provided in the tank, and a control device. The gas introduction mechanism includes a gas introduction port for introducing the gas, and a gas introduction valve for opening and closing the gas introduction port. The control device alternately performs a gas introduction operation in which the gas is introduced into the tank by supplying the liquid from the tank to the liquid tank with the gas introduction valve open, and a fine bubble generation operation in which, with the gas introduction valve closed, the pressure pump is driven to pressurize and supply liquid from the tank supply path to the tank, and the liquid in which the gas has been pressurized and dissolved is supplied from the tank to the liquid tank via the tank discharge path. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-18118 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the micro-bubble generator of Patent Document 1, gas is supplied to the tank in the gas introduction operation, and gas is consumed from the tank in the micro-bubble generation operation, so the gas introduction operation and the micro-bubble generation operation must be performed alternately. However, since micro-bubbles cannot be generated in the liquid supplied from the tank to the liquid vat during the gas introduction operation, the micro-bubbles generated in the liquid in the liquid vat during the micro-bubble generation operation disappear during the gas introduction operation, making it difficult to stably generate micro-bubbles in the liquid in the liquid vat. This specification provides a technology that can stably generate micro-bubbles in the liquid in the liquid vat. [Means for solving the problem]

[0005] The fine-bubble generating device disclosed in this specification includes a tank for pressurizing and dissolving a gas in a liquid, a tank supply path for supplying the liquid to the tank, a pressure pump provided in the tank supply path, a tank discharge path for discharging the liquid in which the gas is pressurized and dissolved from the tank to a liquid tank, a fine-bubble generating nozzle provided in the tank discharge path for reducing the pressure of the liquid in which the gas is pressurized and dissolved to generate fine bubbles, a tank circulation path provided separately from the tank discharge path for sending the liquid from an outlet connected to the tank to an inlet connected to the tank, a tank circulation pump provided in the tank circulation path, a gas introduction mechanism provided in the tank circulation path, and a control device. The gas introduction mechanism includes a pressure reduction section for reducing the pressure of the liquid and passing it through, and a gas introduction port for introducing the gas by the negative pressure of the liquid in the pressure reduction section. The control device is capable of executing a fine-bubble generating operation in which the pressurized pump is driven to pressurize and supply the liquid from the tank supply path to the tank, and the liquid in which the gas is pressurized and dissolved is supplied from the tank to the liquid vat via the tank discharge path. In the fine-bubble generating device, during the execution of the fine-bubble generating operation, the control device drives the tank circulation pump to circulate the liquid in the tank through the tank circulation path, thereby supplying the gas introduced by the gas introduction mechanism to the tank.

[0006] In the above-mentioned fine bubble generator, even during the fine bubble generating operation, the gas introduced by the gas introduction mechanism can be supplied to the tank by driving the tank circulation pump. Therefore, there is no need to interrupt the fine bubble generating operation to supply gas to the tank, and the fine bubble generating operation can be continued. With this configuration, fine bubbles can be stably generated continuously in the liquid in the liquid vat.

[0007] In the fine-bubble generating device, the gas introducing mechanism may be disposed upstream of the tank circulation pump in the tank circulation path.

[0008] According to the above configuration, the pressure of the liquid in the pressure reducing section can be lowered compared to when the gas introduction mechanism is disposed downstream of the tank circulation pump in the tank circulation path. With this configuration, the amount of gas introduced by the gas introduction mechanism can be increased. Furthermore, according to the above configuration, when the gas introduced by the gas introduction mechanism and the liquid flowing through the tank circulation path pass through the tank circulation pump, they are agitated by the impeller of the tank circulation pump, which can further promote dissolution of the gas into the liquid.

[0009] The fine-bubble generating device may further include a gas introduction valve that opens and closes the gas introduction port, a first level electrode capable of detecting whether the liquid level in the tank is equal to or higher than a first liquid level, and a second level electrode capable of detecting whether the liquid level in the tank is equal to or higher than a second liquid level that is higher than the first liquid level. The liquid level at a point where the outlet to the tank circulation path is connected to the tank may be lower than the first liquid level. The control device may be configured to close the gas introduction valve in the fine-bubble generating operation when the first level electrode detects that the liquid level in the tank is lower than the first liquid level with the gas introduction valve open, and to open the gas introduction valve in the fine-bubble generating operation when the second level electrode detects that the liquid level in the tank is higher than the second liquid level with the gas introduction valve closed.

[0010] During the execution of the fine bubble generating operation, if the amount of gas consumed from the tank is less than the amount of gas introduced by the gas introduction mechanism, the liquid level in the tank will drop, and if the amount of gas consumed from the tank is greater than the amount of gas introduced by the gas introduction mechanism, the liquid level in the tank will rise. On the other hand, when the tank circulation pump is driven, if the gas introduction valve is opened, gas is introduced by the gas introduction mechanism, and if the gas introduction valve is closed, gas is not introduced by the gas introduction mechanism. According to the above configuration, the control device switches the gas introduction valve between opening and closing depending on the liquid level in the tank, thereby making it possible to balance the amount of gas consumed from the tank and the amount of gas introduced by the gas introduction mechanism.

[0011] In the fine-bubble generating device, the control device may continue to drive the tank circulating pump even while the gas introduction valve is closed during the fine-bubble generating operation.

[0012] When the tank circulation pump is driven to circulate the liquid in the tank through the tank circulation path, the flow of the liquid in the tank becomes intense. In a pressurized dissolution type tank, the more intense the flow of the liquid in the tank, the more the pressurized dissolution of the gas in the liquid in the tank is promoted. According to the above configuration, in the fine bubble generating operation, the tank circulation pump continues to be driven even while the gas introduction valve is closed, so that the liquid in the tank flows intensely, and the pressurized dissolution of the gas in the liquid in the tank can be further promoted.

[0013] In the fine-bubble generating device, the control device may be configured to specify, during the fine-bubble generating operation, the elapsed time from when the second level electrode detects that the liquid level in the tank is higher than the second liquid level and the gas introduction valve is opened, to when the first level electrode detects that the liquid level in the tank is lower than the first liquid level and the gas introduction valve is closed, as an intake time, and to adjust the rotation speed of the tank circulating pump when driving the tank circulating pump with the gas introduction valve open thereafter, according to the intake time.

[0014] In the fine-bubble generating operation, when the gas introduction valve is open and the amount of gas introduced by the gas introduction mechanism is extremely large compared to the amount of gas consumed from the tank, the intake time is very short. Conversely, in the fine-bubble generating operation, when the gas introduction valve is open and the amount of gas introduced by the gas introduction mechanism is slightly larger than the amount of gas consumed from the tank, the intake time is very long. The amount of gas introduced by the gas introduction mechanism changes depending on the rotation speed of the tank circulation pump when the tank circulation pump is driven with the gas introduction valve open. According to the above configuration, the rotation speed of the tank circulation pump when the tank circulation pump is driven with the gas introduction valve open thereafter is adjusted according to the actual intake time in the fine-bubble generating operation, thereby maintaining an appropriate balance between the amount of gas consumed from the tank and the amount of gas introduced by the gas introduction mechanism, and fine bubbles can be stably generated in the liquid in the liquid tank.

[0015] In the fine-bubble generating device, the control device may be configured to increase the rotation speed of the tank circulation pump when the tank circulation pump is subsequently driven with the gas introduction valve open, when the intake time exceeds a first intake time, and to reduce the rotation speed of the tank circulation pump when the tank circulation pump is subsequently driven with the gas introduction valve open, when the intake time falls short of a second intake time that is shorter than the first intake time.

[0016] When the gas introduction valve is open, the higher the rotation speed of the tank circulation pump, the greater the amount of gas introduced by the gas introduction mechanism, and the lower the rotation speed of the tank circulation pump, the less the amount of gas introduced by the gas introduction mechanism. According to the above configuration, when the intake time is longer than the first intake time, i.e., when the amount of gas introduced by the gas introduction mechanism is less than expected, the rotation speed of the tank circulation pump can be increased to increase the amount of gas introduced by the gas introduction mechanism. Also, according to the above configuration, when the intake time is shorter than the second intake time, i.e., when the amount of gas introduced by the gas introduction mechanism is greater than expected, the rotation speed of the tank circulation pump can be reduced to reduce the amount of gas introduced by the gas introduction mechanism.

[0017] Alternatively, the fine-bubble generating device may further include a first level electrode capable of detecting whether the liquid level in the tank is equal to or higher than a first liquid level, and a second level electrode capable of detecting whether the liquid level in the tank is equal to or higher than a second liquid level higher than the first liquid level. The liquid level at a point where the outlet to the tank circulation path is connected to the tank may be lower than the first liquid level. The control device may be configured to reduce the number of revolutions of the tank circulation pump when the first level electrode detects that the liquid level in the tank is lower than the first liquid level during the fine-bubble generating operation, and to increase the number of revolutions of the tank circulation pump when the second level electrode detects that the liquid level in the tank is higher than the second liquid level during the fine-bubble generating operation.

[0018] During the execution of the fine bubble generating operation, if the amount of gas consumed from the tank is less than the amount of gas introduced by the gas introduction mechanism, the liquid level in the tank will drop, and if the amount of gas consumed from the tank is greater than the amount of gas introduced by the gas introduction mechanism, the liquid level in the tank will rise. On the other hand, when the tank circulation pump is driven, if the rotation speed of the tank circulation pump is increased, the amount of gas introduced by the gas introduction mechanism will increase, and if the rotation speed of the tank circulation pump is reduced, the amount of gas introduced by the gas introduction mechanism will decrease. According to the above configuration, the control device adjusts the rotation speed of the tank circulation pump according to the liquid level in the tank, thereby making it possible to balance the amount of gas consumed from the tank and the amount of gas introduced by the gas introduction mechanism.

[0019] In the fine-bubble generating device, the control device may be configured to identify an environmental parameter according to the environment in which the fine-bubble generating device is installed, and to adjust the rotation speed of the pressure pump during the fine-bubble generating operation according to the environmental parameter.

[0020] The state of the fine bubbles generated in the liquid in the liquid tank during the fine-bubble generating operation changes depending on the pressure in the tank when the fine-bubble generating operation is being performed. The pressure in the tank when the fine-bubble generating operation is being performed may differ depending on the environment in which the fine-bubble generator is installed, even if the pressure pump is driven in the same way. According to the above configuration, if the pressure in the tank when the fine-bubble generating operation is being performed is affected by the environment in which the fine-bubble generator is installed, the rotation speed of the pressure pump can be adjusted to counteract this effect, thereby stabilizing the pressure in the tank when the fine-bubble generating operation is being performed.

[0021] In the micro-bubble generating device, the environmental parameters may include an installation position of the liquid tank relative to the micro-bubble generating device, a piping diameter of at least a portion of the tank discharge path, a piping length of at least a portion of the tank discharge path, a piping diameter of at least a portion of the tank supply path, and / or a piping length of at least a portion of the tank supply path.

[0022] For example, if the liquid tank is installed at a higher position than the fine-bubble generator, the pressure in the tank when the fine-bubble generating operation is being performed will be high, and if the liquid tank is installed at a lower position than the fine-bubble generator, the pressure in the tank when the fine-bubble generating operation is being performed will be low. Also, if the pressure loss in the tank discharge path is large (for example, if the piping diameter of at least a part of the tank discharge path is small or the piping length is long), it becomes difficult to send the liquid from the tank to the tank discharge path, so the pressure in the tank when the fine-bubble generating operation is being performed will be high, and if the pressure loss in the tank discharge path is small (for example, if the piping diameter of at least a part of the tank discharge path is large or the piping length is short), it becomes easy to send the liquid from the tank to the tank discharge path, so the pressure in the tank when the fine-bubble generating operation is being performed will be low. Furthermore, when the pressure loss in the tank supply path is small (for example, when the piping diameter of at least a part of the tank supply path is large or the piping length is short), it becomes easier to send liquid from the tank supply path to the tank, so the pressure in the tank increases when the fine-bubble generating operation is being performed, and when the pressure loss in the tank supply path is large (for example, when the piping diameter of at least a part of the tank supply path is small or the piping length is long), it becomes harder to send liquid from the tank supply path to the tank, so the pressure in the tank decreases when the fine-bubble generating operation is being performed. According to the above configuration, the rotation speed of the pressure pump in the fine-bubble generating operation is adjusted in accordance with the environmental parameters that affect the pressure in the tank when the fine-bubble generating operation is being performed, so that the pressure in the tank can be stabilized when the fine-bubble generating operation is being performed.

[0023] Alternatively, the fine-bubble generating device may further include a tank pressure sensor provided in the tank for detecting the pressure inside the tank as a tank pressure. The control device may be configured to adjust the rotation speed of the pressure booster pump in response to the tank pressure detected by the tank pressure sensor during the fine-bubble generating operation.

[0024] According to the above configuration, even if the pressure inside the tank when the fine bubble generating operation is being performed is affected by the environment in which the fine bubble generating device is installed or other factors, the pressure inside the tank when the fine bubble generating operation is being performed can be stabilized by adjusting the rotation speed of the pressure booster pump in accordance with the actual tank pressure detected by the tank pressure sensor.

[0025] In the fine-bubble generating device, the control device may be configured to reduce the rotation speed of the pressurizing pump when the tank pressure detected by the tank pressure sensor exceeds a first tank pressure during the fine-bubble generating operation, and to increase the rotation speed of the pressurizing pump when the tank pressure falls below a second tank pressure lower than the first tank pressure.

[0026] According to the above configuration, the pressure inside the tank when the fine bubble generating operation is being performed can be maintained between the first tank pressure and the second tank pressure.

[0027] In the fine bubble generating device, the liquid may be water, and the liquid tank may be a bathtub used by a user for bathing.

[0028] According to the above configuration, fine bubbles can be stably generated continuously in the water of the bathtub used by the user for bathing. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a water heating device 2 of a first embodiment. [Diagram 2] 2 is a schematic cross-sectional view of a bathtub adaptor 132 of the water heating apparatus 2 of the first embodiment. FIG. [Diagram 3] 4 is a flowchart of a process executed by a control device 150 during a water filling operation of the hot water heating device 2 in the first embodiment. [Figure 4] 3 is a diagram illustrating an example of a water flow in the water heating device 2 of the first embodiment. FIG. [Diagram 5]5 is a diagram showing a schematic diagram of another example of the water flow in the water heating device 2 of the first embodiment. FIG. [Figure 6] 4 is a flowchart of a process executed by a control device 150 during a fine bubble generating operation of the hot water device 2 in the first embodiment. [Figure 7] 6 is a diagram showing a schematic diagram of still another example of the water flow in the water heating device 2 of the first embodiment. FIG. [Figure 8] 6 is a diagram showing a schematic diagram of still another example of the water flow in the water heating device 2 of the first embodiment. FIG. [Figure 9] 10 is a flowchart of a process executed by a control device 150 during a fine bubble generating operation of a water heating device 2 in a second embodiment. [Figure 10] 11 is a flowchart of a process executed by the control device 150 during a fine bubble generating operation of the water heating device 2 of the third embodiment. [Figure 11] 13 is a diagram showing an example of correction of the rotation speeds of a first pressurizing pump 88 and a second pressurizing pump 90 in a hot water device 2 of a fourth embodiment. FIG. [Figure 12] FIG. 13 is a diagram showing another example of correction of the rotation speeds of the first pressurizing pump 88 and the second pressurizing pump 90 in the hot water device 2 of the fourth embodiment. [Figure 13] FIG. 13 is a diagram showing yet another example of correction of the rotation speeds of the first pressurizing pump 88 and the second pressurizing pump 90 in the hot water device 2 of the fourth embodiment. [Figure 14] FIG. 11 is a diagram showing a schematic configuration of a water heating device 2 of a fifth embodiment. [Figure 15] 13 is a flowchart of a process executed by the control device 150 in parallel with the process shown in FIG. 6 during a fine bubble generating operation of the water heating device 2 of the fifth embodiment. [Figure 16] FIG. 10 is a diagram illustrating an example of the flow of water in a water heating device 2 according to another modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Example 1 1, the hot water device 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 hot water device 2 heats water supplied from a water supply source 200 such as a tap, and can supply 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 hot water device 2 can also generate fine air bubbles in the water in the bathtub 130 that a user uses for bathing.

[0031] (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 bathtub circulation pump 34, and a water flow switch 36.

[0032] The upstream end of the water supply passage 16 is connected to a water supply source 200, and the downstream end of the water supply passage 16 is connected to the first heat source unit 12. The upstream end of the hot water outlet passage 18 is connected to the first heat source unit 12, and the downstream end of the hot water outlet passage 18 is connected to a faucet 250. The first heat source unit 12 is a combustion heat source unit that heats water by, for example, burning gas. The first heat source unit 12 heats the water flowing in from the water supply passage 16 and sends the heated water to the hot water outlet passage 18.

[0033] 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. The bypass servo 22 is provided at the point where the bypass passage 20 connects to the water supply passage 16. The bypass servo 22 can adjust the ratio of the flow rate of water flowing from the water supply passage 16 to the hot water outlet passage 18 via the first heat source unit 12 and the flow rate of water flowing from the water supply passage 16 to the hot water outlet passage 18 via the bypass passage 20 by adjusting the opening degree of the built-in valve body. By adjusting the opening degree of the bypass servo 22, the hot water outlet passage 18 downstream of the point where the bypass passage 20 is connected is supplied with water whose temperature has been adjusted to a desired temperature by mixing high-temperature water flowing from the first heat source unit 12 and low-temperature water flowing from the bypass passage 20 at a desired ratio. The hot water outlet passage 18 downstream of the point where the bypass passage 20 is connected is provided with an outlet hot water temperature thermistor 18a that detects the temperature of the water in the hot water outlet passage 18.

[0034] The upstream end of the molten metal pouring passage 24 is connected to the molten metal outlet passage 18 downstream of the point where the bypass passage 20 is connected, and the downstream end of the molten metal pouring passage 24 is connected to the return circulation passage 32. The molten metal filling valve 26 is provided in the molten metal pouring passage 24 and opens and closes the molten metal pouring passage 24. The molten metal filling valve 26 is normally kept closed. The water volume sensor 28 is provided in the molten metal pouring passage 24 and detects the amount of water flowing through the molten metal pouring passage 24.

[0035] 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 forward circulation path 30 is connected to the second heat source device 14, and the downstream end of the forward circulation path 30 is connected to a heat source forward 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 from the return circulation path 32 and sends the heated water to the forward circulation path 30. A return circulation 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 thermistor 30a that detects the temperature of the water in the forward circulation path 30 is provided near the downstream end of the forward circulation path 30.

[0036] The bathtub circulation pump 34 is provided in the circulation return path 32 downstream of the connection point of the molten metal pouring path 24, and sends water in the circulation return path 32 toward the second heat source unit 14. The water flow switch 36 is provided in the circulation return path 32 between the bathtub circulation pump 34 and the second heat source unit 14, and detects whether water is flowing in the circulation return path 32.

[0037] (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.

[0038] The tank 52 can store water therein. A low water level electrode 52a, a high water level electrode 52b, and an earth electrode 52c are installed inside the tank 52 to detect the water level in the tank 52. The water level detected by the low water level electrode 52a (hereinafter also referred to as the lower limit water level) is lower than the water level detected by the high water level electrode 52b (hereinafter also referred to as the upper limit water level). When the low water level electrode 52a and the high water level electrode 52b come into contact with the water surface stored in the tank 52, a current flows between the low water level electrode 52a and the earth electrode 52c, and an ON signal is output to the control device 150. The tank 52 is used to generate air-dissolved water by pressurizing and dissolving air in water.

[0039] 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 outward line 64. The first three-way valve 80 can be switched between a first communication state (see Figures 7 and 8) in which the tank outward line 64 and the first bathtub water passage 62 are connected, a second communication state (see Figure 1) in which the tank outward line 64 and the communication passage 66 are connected, and a third communication state (see Figures 4 and 5) in which the first bathtub water passage 62, the tank outward line 64, and the communication passage 66 are connected. The upstream end of the tank outgoing passage 64 is connected to the bottom of the tank 52, and the downstream end of the tank outgoing passage 64 is connected to the first three-way valve 80. The tank outgoing passage 64 is provided with a check valve 84 that allows water to flow from the tank 52 to the first three-way valve 80 and prohibits water from flowing from the first three-way valve 80 to 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 the bathtub adapter 132.

[0040] One end of the heat source outgoing path 68 is connected to the circulation outgoing path 30 of the heat source unit 10, and the other end of the heat source outgoing path 68 is connected to the second three-way valve 82. The second three-way valve 82 is connected to the communication passage 66, the heat source outgoing path 68, and the second bathtub water passage 70. The second three-way valve 82 can switch between a fourth communication state (see Figures 7 and 8) in which the second bathtub water passage 70 and the communication passage 66 communicate with each other, and a fifth communication state (see Figures 1, 4, and 5) in which the heat source outgoing path 68 and the second bathtub water passage 70 communicate with each other. 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.

[0041] An upstream end of the tank return line 74 is connected to the heat source outgoing line 68, and a downstream end of the tank return line 74 is connected to the tank 52 via a 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.

[0042] An upstream end (hereinafter, also referred to as an outlet 92a) of the tank circulation path 92 is connected to the bottom of the tank 52, and a downstream end (hereinafter, also referred to as an inlet 92b) of the tank circulation path 92 is connected to the top of the tank 52. The water level at the point where the outlet 92a of the tank circulation path 92 is connected to the tank 52 is lower than the lower limit water level detected by the low water level electrode 52a, and the water level at the point where the inlet 92b of the tank circulation path 92 is connected to the tank 52 is higher than the upper limit water level detected by the high water level electrode 52b. The tank circulation pump 94 is provided in the tank circulation path 92. The tank circulation pump 94 draws water from the tank 52 into the tank circulation path 92 through the outlet 92a, and discharges water from the tank circulation path 92 into the tank 52 through the inlet 92b.

[0043] 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 causes water to flow out 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 pressurized to the 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 sucked 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.

[0044] Even if the gas introduction mechanism 96 as described above is provided in the tank return line 74, air can be introduced by the gas introduction mechanism 96 when water is supplied from the tank return line 74 to the tank 52. However, with such a configuration, the pressure loss in the tank return line 74 increases, and the pressure of the water sent to the tank 52 by the first pressure pump 88 and the second pressure pump 90 decreases. Also, with such a configuration, if the amount of air introduced by the gas introduction mechanism 96 is increased, the pressure of the water sent to the tank 52 decreases, and if the pressure of the water sent to the tank 52 is increased, the amount of air introduced by the gas introduction mechanism 96 decreases. In contrast, in this embodiment, the gas introduction mechanism 96 is provided in the tank circulation path 92 provided separately from the tank return line 74, so that the pressure loss in the tank return line 74 can be reduced. Also, a large amount of air can be introduced by the gas introduction mechanism 96 while sending water from the tank return line 74 to the tank 52 at high pressure.

[0045] (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 2(a) and (b). Figure 2(a) 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 of Figure 7). Figure 2(b) 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 of Figure 5).

[0046] The bathtub adaptor 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 adaptor 132. The water discharged from the first discharge port 134a into the bathtub 130 is discharged in front of the wall portion 130a of the bathtub 130, that is, in a direction perpendicular to the wall portion 130a of the bathtub 130. The first discharge passage 136a is provided with a backflow prevention portion 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 arranged upstream of the backflow prevention portion 140a (on the first bathtub water passage 62 side). 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 provided on the front surface 132a of the bathtub adapter 132. The first suction passage 136b is provided with a backflow prevention portion 140b that prevents water from flowing from the first bathtub water passage 62 toward the bathtub 130.

[0047] 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 portion 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 lower surface 132b of the bathtub adapter 132. Water discharged from the second discharge port 134d is discharged downward, that is, in a direction parallel to the wall portion 130a of the bathtub 130. The second discharge passage 138a is provided with a check portion 140d that prevents water from flowing from the bathtub 130 toward the second bathtub water passage 70.

[0048] (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 pressurized dissolution unit 50. The control device 150 is configured to be able to communicate with a remote control 154 that can be operated by a user. The control device 150 includes 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. Through the remote control 154, the user can give instructions to start and end the water filling operation, the fine bubble generation operation, and the reheating operation, which will be described later.

[0049] (Bath filling operation) The water filling operation starts when the user issues a command to start the water filling operation on the remote control 154. Alternatively, the water filling operation may start when the user sets the start time of the water filling operation on the remote control 154 and the control device 150 determines that the start time of the water filling operation 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 communication state and the fifth communication state, respectively (see Figures 4 and 5). From this state, the control device 150 executes the processing shown in Figure 3.

[0050] In S2, the control device 150 executes the air removal process. Specifically, the control device 150 opens the water filling valve 26 and starts heating the water by the first heat source unit 12. As a result, as shown in FIG. 4, water adjusted to the set temperature flows from the hot water outlet path 18 through the hot water supply path 24 into the circulation return path 32. The water that flows into the circulation return path 32 branches into a flow toward the upstream side (i.e., the heat source return path 60) and a flow toward the downstream side (i.e., the second heat source unit 14). The water that flows from the circulation return path 32 to the heat source return path 60 flows into the bathtub 130 via the communication path 66, the first three-way valve 80, the first bathtub water path 62, and the bathtub adapter 132. The water that flows 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 path 70, and the bathtub adapter 132. As a result, the first bathtub water channel 62 and the second bathtub water channel 70 are filled with water, and any air remaining inside the first bathtub water channel 62 and the second bathtub water channel 70 is expelled into the bathtub 130. When the accumulated water volume detected by the water volume sensor 28 reaches a predetermined value (e.g., 6 L), the control device 150 closes the water filling valve 26 and ends heating by the first heat source unit 12, thereby ending the air removal process.

[0051] In S4, the control device 150 executes a process for detecting remaining water in the bathtub 130. Specifically, as shown in FIG. 5, the control device 150 drives the bathtub circulation pump 34 and determines whether there is remaining water in the bathtub 130 based on whether the water flow switch 36 detects a water flow. If there is no remaining water in the bathtub 130 and the bathtub adapter 132 is not submerged in water, the water flow switch 36 does not detect a water flow even if the bathtub circulation pump 34 is driven. In contrast, if there is remaining water in the bathtub 130 and the bathtub adapter 132 is submerged in water, the water flow switch 36 detects a water flow when the bathtub circulation pump 34 is driven. If there is remaining water in the bathtub 130 in S4 (if YES), the process proceeds to S6. If there is no remaining water in the bathtub 130 in S4 (if NO), the process proceeds to S10.

[0052] In S6, the control device 150 performs a process to determine the amount of water remaining in the bathtub 130. Specifically, the control device 150 drives the bathtub circulation pump 34 and stores the temperature detected by the circulation return thermistor 32a as the pre-heating temperature. After that, the control device 150 starts heating the water with the second heat source unit 14. As a result, as shown in FIG. 5, the remaining 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 passage 60, and the circulation return passage 32. The remaining water heated by the second heat source unit 14 is returned to the bathtub 130 via the circulation outward passage 30, the heat source outward passage 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 becomes equal to or higher than the set temperature, the control device 150 stores the temperature detected by the circulation return thermistor 32a as the post-heating temperature, and then stops the bathtub circulation pump 34 and ends the heating of water by the second heat source unit 14. The control device 150 then calculates the amount of remaining water in the bathtub 130 from the temperature rise obtained by subtracting the pre-heating temperature from the post-heating temperature and the integrated amount of heat in the second heat source unit 14 in S6.

[0053] In S8, the control device 150 subtracts the amount of remaining water in the bathtub 130 determined in S6 from the set amount of water for the water filling operation to update the set amount of water for the water filling operation.

[0054] In S10, the control device 150 opens the water filling valve 26 and starts heating by the first heat source unit 12. As a result, as shown in Fig. 4, water adjusted to the set temperature flows from the hot water outlet line 18 through the hot water supply line 24 into the circulation return line 32. The water flowing into the circulation return line 32 branches into a flow toward the upstream side (i.e., the heat source return line 60) and a flow toward the downstream side (i.e., the second heat source unit 14). The water flowing from the circulation return line 32 to the heat source return line 60 flows into the bathtub 130 via the communication passage 66, the first three-way valve 80, the first bathtub water passage 62, and the bathtub adapter 132. The water flowing from the circulation return line 32 to the second heat source unit 14 flows into the bathtub 130 via the circulation outward line 30, the heat source outward line 68, the second three-way valve 82, the second bathtub water passage 70, and the bathtub adapter 132.

[0055] In S12, control device 150 waits until the accumulated water volume detected by water volume sensor 28 reaches the set water volume for the water filling operation. Note that the accumulated water volume here is the sum of the accumulated water volume detected by water volume sensor 28 in the air removal process in S2 and the accumulated water volume since the start of filling bathtub 130 with water in S10. When the accumulated water volume reaches the set water volume (YES), processing proceeds to S14.

[0056] In S14, the control device 150 closes the water filling valve 26 and terminates the heating of water by the first heat source unit 12.

[0057] In S16, the control device 150 drives the bathtub circulation pump 34 and obtains the temperature detected by the circulation return thermistor 32a as the bathtub water temperature. The control device 150 then determines whether the bathtub water temperature is equal to or higher than the set temperature. If the bathtub water temperature is lower than the set temperature (NO), the process proceeds to S18. If the bathtub water temperature is equal to or higher than the set temperature (YES), the process proceeds to S20.

[0058] In S18, the control device 150 performs a reheating process for the water in the bathtub 130. Specifically, the control device 150 drives the bathtub circulation pump 34 and starts the heating of the water by the second heat source unit 14. As a result, as shown in FIG. 5, the 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 becomes equal to or higher than the set temperature, the control device 150 stops the bathtub circulation pump 34 and ends the heating of the water by the second heat source unit 14.

[0059] In S20, the control device 150 notifies the user that the water filling operation has been completed via the remote control 154. After S20, the processing in FIG.

[0060] (Fine bubble generation operation) The fine bubble generating operation is started when the user issues a command to start the fine bubble generating operation via the remote control 154. In addition, in the hot water heater 2 of this embodiment, the fine bubble generating operation is also started automatically after the above-mentioned water filling operation is completed. In other words, the fine bubble generating operation is executed in conjunction with the execution of the water filling operation. 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 third communication state and the fifth communication state, respectively (see Figures 4 and 5). From this state, the control device 150 executes the process shown in Figure 6.

[0061] In S32, the control device 150 executes a cold water reduction process. Specifically, when the temperature detected by the circulation forward thermistor 30a or the circulation return thermistor 32a is equal to or lower than a predetermined temperature, the control device 150 drives the bathtub circulation pump 34 and starts heating the water by the second heat source unit 14. When low-temperature water remains inside the circulation forward path 30 or the circulation return path 32 due to this cold water reduction process, as shown in FIG. 5, the low-temperature water flows into the bathtub adapter 132 via the heat source forward path 68, the second three-way valve 82, and the second bathtub water path 70, and is discharged into the bathtub 130 from the second outlet 134d on the bottom surface 132b of the bathtub adapter 132. Therefore, even if the user is taking a bath in the bathtub 130, it is possible to prevent low-temperature water from being discharged directly toward the user's body. When a predetermined time has elapsed since the start of the cold water mitigation process, the control device 150 stops the bathtub circulation pump 34 and terminates the heating of water by the second heat source unit 14, thereby terminating the cold water mitigation process.

[0062] In S34, 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.

[0063] In S36, the control device 150 opens the gas introduction valve 106. This causes air to be introduced into the water flowing through the gas introduction mechanism 96 of the tank circulation path 92.

[0064] In S38, the control device 150 starts supplying the air-dissolved water from the tank 52 to the bathtub 130. Specifically, as shown in FIG. 7, the control device 150 sets the first three-way valve 80 to the first communication state, sets the second three-way valve 82 to the fourth communication state, and drives the bathtub circulation pump 34, the first pressurizing pump 88, and the second pressurizing pump 90. As a result, the water in 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 pressurizing pump 88 and the second pressurizing pump 90 is supplied from the tank return path 74 to the tank 52. As a result, air is pressurized and dissolved in the water inside the tank 52. The water in which the air has been pressurized and dissolved is then supplied to the bathtub 130 from the tank 52 via the tank outward path 64, the first three-way valve 80, the first bathtub water path 62, and the bathtub adapter 132. At this time, the water in which the air has been pressurized and dissolved is depressurized to below atmospheric pressure as it passes through the fine bubble generating nozzle 142 of the first discharge path 136a of the bathtub adapter 132, and is pressurized to atmospheric pressure as it is sprayed into the bathtub 130, generating fine bubbles in the water in the bathtub 130.

[0065] In S40, the control device 150 judges whether the water level of the tank 52 falls below the lower limit water level based on the detection signal from the low water level electrode 52a. 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 of 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 of the tank 52 drops. If the water level of the tank 52 falls below the lower limit water level (YES), the process proceeds to S42. If the water level of the tank 52 is equal to or greater than the lower limit water level (NO), the process proceeds to S44.

[0066] In S42, the control device 150 closes the gas introduction valve 106 if the gas introduction valve 106 is open. This stops the introduction of air into the water flowing through the gas introduction mechanism 96 of the tank circulation path 92. 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.

[0067] In S44, the control device 150 determines whether the water level of the tank 52 is equal to or higher than the upper water level based on the detection signal from the high water level electrode 52b. 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 of the tank 52 rises. If the water level of the tank 52 is equal to or higher than the upper water level (YES), the process proceeds to S46. If the water level of the tank 52 is below the upper water level (NO), the process proceeds to S48.

[0068] In S46, if the gas introduction valve 106 is closed, the control device 150 opens the gas introduction valve 106. This resumes the introduction of air into the water flowing through the gas introduction mechanism 96 of the tank circulation path 92.

[0069] In S48, the control device 150 judges whether the operation time of the fine bubble generating operation has reached the set time. Here, the operation time of the fine bubble generating operation is the time elapsed since the start of the fine bubble generating operation. In the hot water device 2 of this embodiment, when the fine bubble generating operation is performed independently without being linked to the execution of the water filling operation, the set time is set to, for example, 10 minutes. In contrast, when the fine bubble generating operation is performed in conjunction with the execution of the water filling operation, the set time is set to, for example, 30 minutes. If the operation time has not reached the set time (if NO), the process returns to S40. If the operation time has reached the set time (if YES), the process proceeds to S50.

[0070] In S50, the control device 150 stops the bathtub circulating pump 34, the first pressure pump 88, and the second pressure pump 90, and ends the supply of air-dissolved water from the tank 52 to the bathtub 130.

[0071] In S52, if the gas introduction valve 106 is open, the control device 150 closes the gas introduction valve 106. This ends the introduction of air into the water flowing through the gas introduction mechanism 96 of the tank circulation path 92.

[0072] In S54, the control device 150 executes a tank cleaning process. Specifically, the control device 150 opens the water filling valve 26 and starts heating the water by the first heat source unit 12. As a result, as shown in FIG. 8, water adjusted to the set temperature flows from the hot water outlet path 18 through the hot water supply path 24 into the circulation return path 32. The water that flows into the circulation return path 32 branches into a flow toward the upstream side (i.e., the heat source return path 60) and a flow toward the downstream side (i.e., the second heat source unit 14). The water that flows from the circulation return path 32 to the heat source return path 60 flows into the bathtub 130 via the communication path 66, the second three-way valve 82, the second bathtub water path 70, and the bathtub adapter 132. In addition, the 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 tank return path 74, the tank 52, the tank outward path 64, the first three-way valve 80, the first bathtub water path 62, and the bathtub adapter 132. This cleans the inside of the tank 52 and the tank circulation path 92.

[0073] In S56, the control device 150 stops the tank circulation pump 94. This ends the circulation of water between the tank 52 and the tank circulation path 92. After S56, the processing in FIG. 6 ends.

[0074] (Reheating operation) The reheating operation starts when the user instructs the start of the reheating operation with the remote control 154. 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 Fig. 4 and Fig. 5). From this state, the control device 150 drives the bathtub circulation pump 34 and starts heating the water by the second heat source unit 14. As a result, as shown in Fig. 5, the 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 passage 60, and the circulation return passage 32. The water heated by the second heat source unit 14 is returned to the bathtub 130 via the circulation outward passage 30, the heat source outward passage 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 becomes equal to or higher than the set temperature, the control device 150 stops the bathtub circulation pump 34 and ends 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 ends the reheating operation.

[0075] Example 2 The hot water device 2 of this embodiment has substantially the same configuration as the hot water device 2 of embodiment 1. In the hot water device 2 of this embodiment, when performing the fine bubble generating operation, the control device 150 performs the process shown in Fig. 9 instead of the process shown in Fig. 6. The following describes the process shown in Fig. 9 and the differences from the process shown in Fig. 6.

[0076] 9, if the water level of the tank 52 falls below the lower limit water level in S40 (YES), the process proceeds to S58. In S58, the control device 150 reduces the rotation speed of the tank circulation pump 94. This reduces the amount of air introduced into the water flowing through the gas introduction mechanism 96 of the tank circulation path 92. After S58, the process proceeds to S44.

[0077] 9, if the water level in the tank 52 is equal to or higher than the upper water level in S44 (YES), the process proceeds to S60. In S60, the control device 150 increases the rotation speed of the tank circulation pump 94. This increases the amount of air introduced into the water flowing through the gas introduction mechanism 96 of the tank circulation path 92. After S58, the process proceeds to S48.

[0078] Example 3 The hot water device 2 of this embodiment has a configuration substantially similar to that of the hot water device 2 of embodiment 1. In the hot water device 2 of this embodiment, when performing the fine bubble generating operation, the control device 150 performs the process shown in Fig. 10 instead of the process shown in Fig. 6. The following describes the process shown in Fig. 10 and the differences from the process shown in Fig. 6.

[0079] 10, after starting the supply of dissolved air water from tank 52 to bathtub 130 in S38, the process proceeds to S62. In S62, control device 150 determines whether the water level in tank 52 is below the lower limit water level based on the detection signal from low water level electrode 52a. If the water level in tank 52 is equal to or higher than the lower limit water level (NO), the process repeats S62. If the water level in tank 52 is below the lower limit water level (YES), the process proceeds to S64.

[0080] In S64, 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. 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.

[0081] In S66, the control device 150 determines whether the water level of the tank 52 is equal to or higher than the upper water level based on the detection signal from the high water level electrode 52b. If the water level of the tank 52 is equal to or higher than the upper water level (YES), the process proceeds to S68. If the water level of the tank 52 is lower than the upper water level (NO), the process proceeds to S72.

[0082] In S68, the control device 150 opens the gas introduction valve 106. This restarts the introduction of air into the water flowing through the gas introduction mechanism 96 of the tank circulation path 92.

[0083] In S70, the control device 150 starts timing the inspiration time using a built-in timer (not shown).

[0084] In S72, the control device 150 determines whether the water level of the tank 52 falls below the lower limit water level based on the detection signal from the low water level electrode 52a. If the water level of the tank 52 is equal to or higher than the lower limit water level (if NO), the process proceeds to S86. If the water level of the tank 52 falls below the lower limit water level (if YES), the process proceeds to S74.

[0085] In S74, 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.

[0086] In S76, the control device 150 ends the measurement of the inspiration time by a built-in timer (not shown).

[0087] In S78, the control device 150 judges whether the intake time measured in S70 and S76 is below a predetermined lower limit time (for example, 10 seconds). If the intake time is below the lower limit time (YES), the process proceeds to S80. If the intake time is equal to or greater than the lower limit time (NO), the process proceeds to S82.

[0088] In S80, the control device 150 reduces the rotational speed of the tank circulating pump 94 by a predetermined value (for example, 10 Hz). This reduces the amount of air introduced by the gas introduction mechanism 96 when the tank circulating pump 94 is subsequently driven with the gas introduction valve 106 open. After S80, the process proceeds to S82.

[0089] In S82, the control device 150 judges whether the inhalation time exceeds a predetermined upper limit time (for example, 20 seconds). If the inhalation time exceeds the upper limit time (YES), the process proceeds to S84. If the inhalation time is equal to or less than the upper limit time (NO), the process proceeds to S86.

[0090] In S84, the control device 150 increases the rotational speed of the tank circulating pump 94 by a predetermined value (for example, 10 Hz). As a result, when the tank circulating pump 94 is subsequently driven with the gas introduction valve 106 open, the amount of air introduced by the gas introduction mechanism 96 increases. After S84, the process proceeds to S86.

[0091] In S86, the control device 150 judges 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 (if NO), the process returns to S66. If the operation time has reached the set time (if YES), the process proceeds to S50.

[0092] 10, the control device 150 may be configured to reduce the rotation speed of the tank circulation pump 94 when the tank circulation pump 94 is subsequently driven with the gas introduction valve 106 open, but not to reduce the rotation speed of the tank circulation pump 94 when the tank circulation pump 94 is subsequently driven with the gas introduction valve 106 closed. Similarly, in S84 of the process shown in FIG 10, the control device 150 may be configured to increase the rotation speed of the tank circulation pump 94 when the tank circulation pump 94 is subsequently driven with the gas introduction valve 106 open, but not to increase the rotation speed of the tank circulation pump 94 when the tank circulation pump 94 is subsequently driven with the gas introduction valve 106 closed.

[0093] Example 4 The hot water device 2 of this embodiment has a configuration substantially similar to that of the hot water device 2 of embodiment 1. In the hot water device 2 of this embodiment, the control device 150 corrects the rotation speed when driving the first pressure pump 88 and the second pressure pump 90 in the fine bubble generating operation (see FIG. 6) according to the installation position of the bathtub 130, the pipe diameter and pipe length of the first bathtub water passage 62, and the pipe diameter and pipe length of the second bathtub water passage 70. The installation position of the bathtub 130, the pipe diameter and pipe length of the first bathtub water passage 62, and the pipe diameter and pipe length of the second bathtub water passage 70 are input to the control device 150 by a contractor, for example, via a dip switch (not shown) provided in the control device 150, when the hot water device 2 is installed in a house.

[0094] For example, as shown in Fig. 11, the control device 150 determines the correction amount for the rotation speed of the first pressurizing pump 88 and the second pressurizing pump 90 according to the installation position of the bathtub 130. In the example shown in Fig. 11, the control device 150 sets the correction amount to ±0 Hz when the installation position of the bathtub 130 (for example, the installation position of the bathtub adapter 132 attached to the bathtub 130) is at the same height (indicated as "horizontal" in Fig. 11) as the installation position of the air pressure dissolving unit 50 (for example, the connection position of the first bathtub water channel 62 and the second bathtub water channel 70 in the air pressure dissolving unit 50). In contrast, the control device 150 sets the correction amount to +5 Hz when the installation position of the bathtub 130 is located 1.5 m below the installation position of the air pressure dissolving unit 50 (indicated as "1.5 m below" in Fig. 11). In addition, when the installation position of bathtub 130 is 3 m above the installation position of air pressure dissolution unit 50 (indicated as "3 m above" in Figure 11), control device 150 sets the correction amount to -5 Hz, and when the installation position of bathtub 130 is 5 m above the installation position of air pressure dissolution unit 50 (indicated as "5 m above" in Figure 11), control device 150 sets the correction amount to -10 Hz.

[0095] If the installation position of the bath 130 is higher than that of the air pressurization dissolution unit 50, the pressure in the tank 52 during the fine bubble generation operation will be higher. Conversely, if the installation position of the bath 130 is lower than that of the air pressurization dissolution unit 50, the pressure in the tank 52 during the fine bubble generation operation will be lower. For this reason, as shown in Fig. 11, the rotation speeds of the first pressurization pump 88 and the second pressurization pump 90 are increased when the installation position of the bath 130 is high and are reduced when the installation position of the bath 130 is low, thereby suppressing the effect of the difference in the installation position of the bath 130 on the pressure in the tank 52.

[0096] 12, the control device 150 determines the amount of correction for the rotation speeds of the first pressurizing pump 88 and the second pressurizing pump 90 according to the pipe diameter and pipe length of the first bathtub water passage 62 (referred to as the "discharge side pipe" in FIG. 12). In the example shown in FIG. 12, when the pipe diameter of the first bathtub water passage 62 is 10 mm, if the pipe length of the first bathtub water passage 62 is less than 5 m, the correction amount is +5 Hz, if the pipe length of the first bathtub water passage 62 is 5 m or more and less than 10 m, the correction amount is ±0 Hz, and if the pipe length of the first bathtub water passage 62 is 10 m or more and less than 15 m, the correction amount is -5 Hz. In addition, when the piping diameter of the first bathtub water passage 62 is 13 mm, if the piping length of the first bathtub water passage 62 is less than 5 m, the correction amount is +10 Hz, if the piping length of the first bathtub water passage 62 is 5 m or more and less than 10 m, the correction amount is +5 Hz, and if the piping length of the first bathtub water passage 62 is 10 m or more and less than 15 m, the correction amount is ±0 Hz.

[0097] If the pressure loss in the first bathtub water passage 62 is large, it becomes difficult for air-dissolved water to flow out from the tank 52 toward the bathtub 130, so the pressure inside the tank 52 becomes higher when the fine-bubble generating operation is being performed. Conversely, if the pressure loss in the first bathtub water passage 62 is small, it becomes easier for air-dissolved water to flow out from the tank 52 toward the bathtub 130, so the pressure inside the tank 52 becomes lower when the fine-bubble generating operation is being performed. The pressure loss in the first bathtub water passage 62 becomes large when the piping diameter of the first bathtub water passage 62 is small or the piping length of the first bathtub water passage 62 is long, and becomes small when the piping diameter of the first bathtub water passage 62 is large or the piping length of the first bathtub water passage 62 is short. Therefore, as shown in FIG. 12, the rotation speeds of the first pressurizing pump 88 and the second pressurizing pump 90 are increased when the piping diameter of the first bathtub water passage 62 is large or the piping length of the first bathtub water passage 62 is short (i.e., when the pressure loss of the first bathtub water passage 62 is small), and are reduced when the piping diameter of the first bathtub water passage 62 is small or the piping length of the first bathtub water passage 62 is long (i.e., when the pressure loss of the first bathtub water passage 62 is large), thereby suppressing the effect that differences in the piping diameter and piping length of the first bathtub water passage 62 have on the pressure in the tank 52.

[0098] 13, the control device 150 determines the amount of correction for the rotation speeds of the first pressurizing pump 88 and the second pressurizing pump 90 according to the pipe diameter and pipe length of the second bathtub water passage 70 (referred to as "suction side pipe" in FIG. 13). In the example shown in FIG. 13, when the pipe diameter of the second bathtub water passage 70 is 10 mm, if the pipe length of the second bathtub water passage 70 is less than 5 m, the correction amount is -10 Hz, if the pipe length of the second bathtub water passage 70 is 5 m or more and less than 10 m, the correction amount is ±0 Hz, and if the pipe length of the second bathtub water passage 70 is 10 m or more and less than 15 m, the correction amount is +10 Hz. In addition, when the piping diameter of the second bathtub water passage 70 is 13 mm, if the piping length of the second bathtub water passage 70 is less than 5 m, the correction amount is -20 Hz, if the piping length of the second bathtub water passage 70 is 5 m or more and less than 10 m, the correction amount is -10 Hz, and if the piping length of the second bathtub water passage 70 is 10 m or more and less than 15 m, the correction amount is ±0 Hz.

[0099] If the pressure loss in the second bathtub water passage 70 is small, water will flow more easily from the bathtub 130 into the tank 52, and the pressure in the tank 52 will be higher when the fine-bubble generating operation is being performed. Conversely, if the pressure loss in the second bathtub water passage 70 is large, water will flow less easily from the bathtub 130 into the tank 52, and the pressure in the tank 52 will be lower when the fine-bubble generating operation is being performed. The pressure loss in the second bathtub water passage 70 is large when the piping diameter of the second bathtub water passage 70 is small or the piping length of the second bathtub water passage 70 is long, and is small when the piping diameter of the second bathtub water passage 70 is large or the piping length of the second bathtub water passage 70 is short. Therefore, as shown in FIG. 13, the rotation speeds of the first pressurizing pump 88 and the second pressurizing pump 90 are increased when the piping diameter of the second bathtub water passage 70 is small or the piping length of the second bathtub water passage 70 is long (i.e., when the pressure loss in the second bathtub water passage 70 is large), and are reduced when the piping diameter of the second bathtub water passage 70 is large or the piping length of the second bathtub water passage 70 is short (i.e., when the pressure loss in the second bathtub water passage 70 is small), thereby suppressing the effect that differences in the piping diameter and piping length of the second bathtub water passage 70 have on the pressure in the tank 52.

[0100] The correction of the rotation speed shown in FIG. 11, FIG. 12, and FIG. 13 may be performed for both the first pressurizing pump 88 and the second pressurizing pump 90, or may be performed for only one of them.

[0101] Example 5 The hot water device 2 of this embodiment has a configuration substantially similar to that of the hot water device 2 of the first embodiment. As shown in Fig. 14, in this embodiment, the pressurized air dissolution unit 50 has a tank pressure sensor 54. The tank pressure sensor 54 is provided at a position lower than the lower limit water level of the tank 52, and detects the pressure inside the tank 52 as the tank pressure. In the hot water device 2 of this embodiment, the control device 150 feedback-controls the rotation speed when driving the first pressurizing pump 88 and the second pressurizing pump 90 in the fine bubble generating operation (see Fig. 6) using the tank pressure detected by the tank pressure sensor 54.

[0102] Specifically, when the control device 150 starts the supply of air-dissolved water from the tank 52 to the bathtub 130 in S38 of the fine bubble generating operation shown in FIG. 6, the control device 150 executes the process shown in FIG. 15 in parallel with the process shown in FIG. 6.

[0103] In S92, the control device 150 determines whether the tank pressure detected by the tank pressure sensor 54 is below a predetermined lower limit tank pressure. If the tank pressure is below the lower limit tank pressure (YES), the process proceeds to S94. If the tank pressure is equal to or higher than the lower limit tank pressure (NO), the process proceeds to S96.

[0104] In S94, the control device 150 increases the rotation speeds of the first pressurizing pump 88 and the second pressurizing pump 90 by a predetermined rotation speed increment (for example, 1 Hz). This increases the tank pressure of the tank 52. After S94, the process proceeds to S96.

[0105] In S96, the control device 150 determines whether the tank pressure detected by the tank pressure sensor 54 is equal to or greater than a predetermined upper limit tank pressure that is greater than the lower limit tank pressure. If the tank pressure is equal to or greater than the upper limit tank pressure (YES), the process proceeds to S98. If the tank pressure is lower than the upper limit tank pressure (NO), the process proceeds to S100.

[0106] In S98, the control device 150 reduces the rotation speeds of the first pressurizing pump 88 and the second pressurizing pump 90 by a predetermined rotation speed width (for example, 1 Hz). This reduces the tank pressure of the tank 52. After S98, the process proceeds to S100.

[0107] In S100, the control device 150 determines whether the first pressurizing pump 88 and the second pressurizing pump 90 have stopped. The first pressurizing pump 88 and the second pressurizing pump 90 are stopped when the supply of air-dissolved water from the tank 52 to the bathtub 130 is terminated in S50 of the fine bubble generating operation shown in Fig. 6. If the first pressurizing pump 88 and the second pressurizing pump 90 have not stopped (if NO), the process returns to S92. If the first pressurizing pump 88 and the second pressurizing pump 90 have stopped (if YES), the process of Fig. 15 ends.

[0108] 15, the rotation speeds of the first pressurizing pump 88 and the second pressurizing pump 90 are adjusted so that the tank pressure detected by the tank pressure sensor 54 is equal to or greater than the lower limit tank pressure and less than the upper limit tank pressure. With this configuration, the pressure in the tank 52 can be maintained within a desired range even if the pressure in the tank 52 during the microbubble generating operation is affected by the installation position of the bathtub 130, the piping diameter and length of the first bathtub water passage 62, the piping diameter and length of the second bathtub water passage 70, or other factors.

[0109] The increase and decrease in the rotation speed in S94 and S98 in FIG. 15 may be performed for both the first pressurizing pump 88 and the second pressurizing pump 90, or for only one of them.

[0110] In the hot water device 2 of this embodiment, the control device 150 may be configured to calculate the difference between a preset target tank pressure and the actual tank pressure detected by the tank pressure sensor 54 instead of S92-S98 in the process of FIG. 15, and adjust the rotation speed of the first pressurizing pump 88 and / or the second pressurizing pump 90 by adding a correction amount obtained by multiplying the calculated tank pressure difference by a negative coefficient to the rotation speed of the first pressurizing pump 88 and / or the second pressurizing pump 90. With this configuration, the rotation speed of the first pressurizing pump 88 and / or the second pressurizing pump 90 is adjusted so that the actual tank pressure detected by the tank pressure sensor 54 approaches the target tank pressure. With this configuration, the pressure in the tank 52 can be maintained at the desired target tank pressure even if the pressure in the tank 52 during the fine bubble generating operation is affected by the installation position of the bathtub 130, the pipe diameter and pipe length of the first bathtub water passage 62, the pipe diameter and pipe length of the second bathtub water passage 70, etc., or by other factors.

[0111] (Other variations) In the above-described hot water device 2, in the fine bubble generating operation that is executed in conjunction with the execution of the hot water filling operation, the cold water reduction process of S32 in FIG. 6, FIG. 9, and FIG. 10 may be omitted.

[0112] In the above-described hot water device 2, the tank cleaning process in S54 in FIG. 6, FIG. 9, and FIG. 10 may be omitted.

[0113] In the above hot water device 2, even if the operation time reaches the set time in the operation time determination process of S48 in Fig. 6 or 9, the process may be configured to return to S40 and continue the fine bubble generating operation without proceeding to S50 until the user issues an instruction to end the fine bubble generating operation via the remote control 154. Similarly, in the above hot water device 2, even if the operation time reaches the set time in the operation time determination process of S86 in Fig. 10, the process may be configured to return to S66 and continue the fine bubble generating operation without proceeding to S50 until the user issues an instruction to end the fine bubble generating operation via the remote control 154.

[0114] In the above-mentioned hot water device 2, when the fine bubble generating operation is performed in conjunction with the execution of the water filling operation, the notification of the end of water filling in S20 of Fig. 3 may be performed while the fine bubble generating operation is being performed, rather than at the end of the water filling operation. More specifically, the notification of the end of water filling may be performed after the operation time of the fine bubble generating operation reaches a predetermined notification time (e.g., 2 minutes) that allows sufficient fine bubbles to be generated in the water of the bathtub 130. With this configuration, the user can delay the timing of entering the bathroom, and the user can be prevented from entering the bathroom before sufficient fine bubbles are generated in the water of the bathtub 130.

[0115] In the hot water apparatus 2 described above, the user may be able to switch, via the remote control 154, whether or not to execute the fine bubble generating operation in conjunction with the execution of the water filling operation.

[0116] In the above-described hot water device 2, air is introduced into the tank 52, but instead of air, gas such as carbon dioxide gas, hydrogen, oxygen, etc. may be introduced into the tank 52. In this case, a gas-filled tank (not shown) filled with gas may be connected to the gas inlet 104a of the gas introduction path 104.

[0117] In the above-described hot water heater 2, during the bath filling operation, a set amount of water is stored in bathtub 130 based on the accumulated water amount detected by water amount sensor 28. Alternatively, the hot water heater 2 may be configured to be provided with a water level sensor capable of detecting the water level of bathtub 130, and during the bath filling operation, water at the set water level is stored in bathtub 130 based on the water level of bathtub 130 detected by the water level sensor.

[0118] In the above-described hot water device 2, the heat source unit 10 is connected to the faucet 250, and the pressurized air dissolving unit 50 is connected to the bathtub 130. Alternatively, the heat source unit 10 may be connected to another heat utilization location, and the pressurized air dissolving unit 50 may be connected to another liquid tank.

[0119] In the hot water device 2 described above, the gas introduction mechanism 96 is disposed upstream of the tank circulation pump 94 in the tank circulation path 92. Alternatively, the gas introduction mechanism 96 may be disposed downstream of the tank circulation pump 94 in the tank circulation path 92.

[0120] In the hot water device 2 described above, the tank circulation path 92 and the tank return path 74 are provided separately. Alternatively, as shown in FIG. 16, the tank circulation path 92 downstream of the tank circulation pump 94 may be configured to merge with the tank return path 74 downstream of the second pressurizing pump 90. In this case, the water supply port 74a at the downstream end of the tank return path 74 also serves as the inlet 92b at the downstream end of the tank circulation path 92. Even in the configuration as shown in FIG. 16, the gas introduction mechanism 96 is provided in the tank circulation path 92 upstream of the point where the tank circulation path 92 and the tank return path 74 merge, so that the pressure loss of the tank return path 74 can be reduced. In addition, in the configuration as shown in FIG. 16, the vortexes inside the tank 52 are united, and the dissolution of air into the water in the tank 52 is further promoted.

[0121] The adjustment of the rotation speed of the first pressure pump 88 and / or the second pressure pump 90, which is performed by the control device 150 in the hot water device 2 of Example 4 or Example 5, may also be performed by the control device 150 of the hot water device 2 of Example 2 or Example 3.

[0122] As described above, in one or more embodiments, the hot water device 2 (an example of a fine-bubble generating device) includes the tank 52 that pressurizes and dissolves air (an example of a gas) in water (an example of a liquid), the tank return path 74 (an example of a tank supply path) that supplies water to the tank 52, a first pressure pump 88 and a second pressure pump 90 (an example of a pressure pump) provided in the tank return path 74, the tank outward path 64 that discharges the water in which air has been pressurized and dissolved from the tank 52 to the bathtub 130 (an example of a liquid tank), the first bathtub water path 62, the bathtub adapter 132 (a tank discharge path The apparatus includes a tank circulation path 92 that is provided separately from the tank outflow path 64, the first bathtub water path 62, and the bathtub adapter 132 and sends water from an outlet 92a connected to the tank 52 to an inlet 92b connected to the tank 52, a tank circulation pump 94 provided in the tank circulation path 92, a gas introduction mechanism 96 provided in the tank circulation path 92, and a control device 150. The gas introduction mechanism 96 includes a Venturi tube 102 (an example of a pressure reducing section) that reduces the pressure of the water before it passes through, and a gas introduction port 104a that introduces air by the negative pressure of the water in the Venturi tube 102. The control device 150 can perform a fine bubble generating operation in which the first pressurizing pump 88 and the second pressurizing pump 90 are driven to pressurize and supply water from the tank return line 74 to the tank 52, and water in which air has been pressurized and dissolved is supplied from the tank 52 to the bathtub 130 via the tank outward line 64, the first bathtub water line 62, and the bathtub adapter 132. In the hot water device 2, while the fine bubble generating operation is being performed, the control device 150 drives the tank circulation pump 94 to circulate the water in the tank 52 through the tank circulation line 92, thereby supplying air introduced by the gas introduction mechanism 96 to the tank 52.

[0123] In the above-described hot water device 2, even during the fine bubble generating operation, air introduced by the gas introduction mechanism 96 can be supplied to the tank 52 by driving the tank circulation pump 94. Therefore, it is not necessary to interrupt the fine bubble generating operation to supply air to the tank 52, and the fine bubble generating operation can be continued. With this configuration, fine bubbles can be stably generated continuously in the water of the bathtub 130.

[0124] In one or more embodiments, in the water heating device 2, the gas introducing mechanism 96 is disposed upstream of the tank circulation pump 94 in the tank circulation path 92.

[0125] According to the above configuration, the water pressure in the Venturi tube 102 can be lowered compared to when the gas introducing mechanism 96 is disposed downstream of the tank circulation pump 94 in the tank circulation path 92. With such a configuration, the amount of air introduced by the gas introducing mechanism 96 can be increased. Furthermore, according to the above configuration, when the air introduced by the gas introducing mechanism 96 and the water flowing through the tank circulation path 92 pass through the tank circulation pump 94, they are agitated by the impeller of the tank circulation pump 94, which can further promote dissolution of air into the water.

[0126] In one or more embodiments, the hot water device 2 further includes a gas inlet valve 106 that opens and closes the gas inlet 104a, a low water level electrode 52a (an example of a first liquid level electrode) capable of detecting whether the water level (an example of a liquid level) of the tank 52 is equal to or higher than a lower limit water level (an example of a first liquid level), and a high water level electrode 52b (an example of a second liquid level electrode) capable of detecting whether the water level of the tank 52 is equal to or higher than an upper limit water level (an example of a second liquid level) that is higher than the lower limit water level. The water level at the point where the outlet 92a to the tank circulation path 92 is connected to the tank 52 is lower than the lower limit water level. The control device 150 is configured to close the gas introduction valve 106 when the gas introduction valve 106 is open during fine bubble generating operation and detects by the low water level electrode 52a that the water level in the tank 52 is lower than the lower limit water level, and to open the gas introduction valve 106 when the gas introduction valve 106 is closed during fine bubble generating operation and detects by the high water level electrode 52b that the water level in the tank 52 is higher than the upper limit water level.

[0127] During the execution of the fine bubble generating operation, if the amount of air consumed from the tank 52 is less than the amount of air introduced by the gas introduction mechanism 96, the water level of the tank 52 drops, and if the amount of air consumed from the tank 52 is greater than the amount of air introduced by the gas introduction mechanism 96, the water level of the tank 52 rises. On the other hand, when the tank circulation pump 94 is driven, if the gas introduction valve 106 is opened, air is introduced by the gas introduction mechanism 96, and if the gas introduction valve 106 is closed, air is not introduced by the gas introduction mechanism 96. According to the above configuration, the control device 150 switches between opening and closing the gas introduction valve 106 depending on the water level of the tank 52, so that the amount of air consumed from the tank 52 and the amount of air introduced by the gas introduction mechanism 96 can be balanced.

[0128] In one or more embodiments, in the hot water device 2, the control device 150 continues to drive the tank circulating pump 94 during the fine bubble generating operation, even while the gas introduction valve 106 is closed.

[0129] When the tank circulation pump 94 is driven to circulate the water in the tank 52 through the tank circulation path 92, the flow of the water in the tank 52 becomes intense. In a pressurized dissolution type tank 52, the more intense the flow of the water in the tank 52, the more the pressurized dissolution of air in the water in the tank 52 is promoted. According to the above configuration, in the fine bubble generating operation, the tank circulation pump 94 continues to be driven even while the gas introduction valve 106 is closed, so that the water in the tank 52 is caused to flow intensely, and the pressurized dissolution of air in the water in the tank 52 can be further promoted.

[0130] In one or more embodiments, the control device 150 is configured to determine, during fine bubble generating operation, the elapsed time from when the high water level electrode 52b detects that the water level in the tank 52 is higher than the upper water level and opens the gas introduction valve 106 to when the low water level electrode 52a detects that the water level in the tank 52 is lower than the lower water level and closes the gas introduction valve 106 as the intake time, and to adjust the rotation speed of the tank circulation pump 94 when driving the tank circulation pump 94 with the gas introduction valve 106 open thereafter in accordance with the intake time.

[0131] In the fine-bubble generating operation, when the amount of air introduced by the gas introduction mechanism 96 is extremely large compared to the amount of air consumed from the tank 52 while the gas introduction valve 106 is open, the intake time is very short. Conversely, in the fine-bubble generating operation, when the amount of air introduced by the gas introduction mechanism 96 is slightly larger than the amount of air consumed from the tank 52 while the gas introduction valve 106 is open, the intake time is very long. The amount of air introduced by the gas introduction mechanism 96 changes depending on the rotation speed of the tank circulation pump 94 when the tank circulation pump 94 is driven with the gas introduction valve 106 open. According to the above configuration, the amount of air consumed from the tank 52 and the amount of air introduced by the gas introduction mechanism 96 can be kept in an appropriate balance by adjusting the rotation speed of the tank circulation pump 94 when the tank circulation pump 94 is driven with the gas introduction valve 106 open thereafter according to the actual intake time during the fine-bubble generating operation, thereby making it possible to keep fine bubbles stably generated in the water of the bathtub 130.

[0132] In one or more embodiments, the control device 150 is configured to increase the rotation speed of the tank circulation pump 94 when the tank circulation pump 94 is subsequently driven with the gas introduction valve 106 open if the intake time exceeds an upper limit time (an example of a first intake time), and to reduce the rotation speed of the tank circulation pump 94 when the tank circulation pump 94 is subsequently driven with the gas introduction valve 106 open if the intake time falls below a lower limit time (an example of a second intake time) that is shorter than the upper limit time.

[0133] With the gas introduction valve 106 open, the higher the rotation speed of the tank circulation pump 94, the greater the amount of air introduced by the gas introduction mechanism 96, and the lower the rotation speed of the tank circulation pump 94, the less the amount of air introduced by the gas introduction mechanism 96. According to the above configuration, when the intake time is longer than the upper limit time, i.e., when the amount of air introduced by the gas introduction mechanism 96 is less than expected, the rotation speed of the tank circulation pump 94 can be increased to increase the amount of air introduced by the gas introduction mechanism 96. Also, according to the above configuration, when the intake time is shorter than the lower limit time, i.e., when the amount of air introduced by the gas introduction mechanism 96 is greater than expected, the rotation speed of the tank circulation pump 94 can be reduced to reduce the amount of air introduced by the gas introduction mechanism 96.

[0134] Alternatively, in one or more embodiments, the hot water device 2 further includes a low water level electrode 52a (an example of a first liquid level electrode) capable of detecting whether the water level (an example of a liquid level) of the tank 52 is equal to or higher than a lower limit water level (an example of a first liquid level), and a high water level electrode 52b (an example of a second liquid level electrode) capable of detecting whether the water level of the tank 52 is equal to or higher than an upper limit water level (an example of a second liquid level) that is higher than the lower limit water level. The water level at the point where the outlet 92a to the tank circulation path 92 is connected to the tank 52 is lower than the lower limit water level. The control device 150 is configured to reduce the rotation speed of the tank circulation pump 94 when the low water level electrode 52a detects that the water level of the tank 52 is lower than the lower limit water level during the fine bubble generating operation, and to increase the rotation speed of the tank circulation pump 94 when the high water level electrode 52b detects that the water level of the tank 52 is higher than the upper limit water level during the fine bubble generating operation.

[0135] During the execution of the fine bubble generating operation, if the amount of air consumed from the tank 52 is less than the amount of air introduced by the gas introduction mechanism 96, the water level of the tank 52 drops, and if the amount of air consumed from the tank 52 is greater than the amount of air introduced by the gas introduction mechanism 96, the water level of the tank 52 rises. On the other hand, when the tank circulation pump 94 is driven, if the rotation speed of the tank circulation pump 94 is increased, the amount of air introduced by the gas introduction mechanism 96 increases, and if the rotation speed of the tank circulation pump 94 is reduced, the amount of air introduced by the gas introduction mechanism 96 decreases. According to the above configuration, the control device 150 adjusts the rotation speed of the tank circulation pump 94 according to the water level of the tank 52, so that the amount of air consumed from the tank 52 and the amount of air introduced by the gas introduction mechanism 96 can be balanced.

[0136] In one or more embodiments, the control device 150 is configured to identify environmental parameters according to the environment in which the hot water device 2 is installed, and to adjust the rotation speeds of the first pressure pump 88 and the second pressure pump 90 during fine bubble generation operation according to the environmental parameters.

[0137] The state of the fine bubbles generated in the water of the bathtub 130 during the fine-bubble generating operation changes depending on the pressure in the tank 52 when the fine-bubble generating operation is being performed. The pressure in the tank 52 when the fine-bubble generating operation is being performed may differ depending on the environment in which the hot water device 2 is installed, even if the first pressurizing pump 88 and the second pressurizing pump 90 are driven in the same manner. According to the above configuration, if the pressure in the tank 52 when the fine-bubble generating operation is being performed is affected by the environment in which the hot water device 2 is installed, the rotation speeds of the first pressurizing pump 88 and the second pressurizing pump 90 can be adjusted to counteract this effect, thereby stabilizing the pressure in the tank 52 when the fine-bubble generating operation is being performed.

[0138] In one or more embodiments, the environmental parameters include the installation position of the bathtub 130 relative to the water heater 2, the piping diameter of the first bathtub water line 62, the piping length of the first bathtub water line 62, the piping diameter of the second bathtub water line 70, and / or the piping length of the second bathtub water line 70.

[0139] According to the above configuration, the first pressure pump 88 and the second pressure pump 90 during the fine bubble generating operation are adjusted according to the environmental parameters that affect the pressure inside the tank 52 when the fine bubble generating operation is being performed, so that the pressure inside the tank 52 when the fine bubble generating operation is being performed can be stabilized.

[0140] Alternatively, in one or more embodiments, the hot water device 2 further includes a tank pressure sensor 54 that is provided in the tank 52 and detects the pressure inside the tank 52 as the tank pressure. The control device 150 is configured to adjust the rotation speeds of the first pressure pump 88 and the second pressure pump 90 in response to the tank pressure detected by the tank pressure sensor 54 during the fine bubble generating operation.

[0141] According to the above configuration, even if the pressure inside the tank 52 when the fine bubble generating operation is being performed is affected by the environment in which the hot water device 2 is installed or other factors, the pressure inside the tank 52 when the fine bubble generating operation is being performed can be stabilized by adjusting the rotation speeds of the first pressure booster pump 88 and the second pressure booster pump 90 in accordance with the actual tank pressure detected by the tank pressure sensor 54.

[0142] In one or more embodiments, the control device 150 is configured to reduce the rotation speeds of the first pressurizing pump 88 and the second pressurizing pump 90 when the tank pressure detected by the tank pressure sensor 54 exceeds an upper limit tank pressure (an example of a first tank pressure) during fine bubble generating operation, and to increase the rotation speeds of the first pressurizing pump 88 and the second pressurizing pump 90 when the tank pressure falls below a lower limit tank pressure (an example of a second tank pressure) that is lower than the upper limit tank pressure.

[0143] According to the above configuration, the pressure inside the tank 52 when the fine bubble generating operation is being performed can be maintained between the upper limit tank pressure and the lower limit tank pressure.

[0144] Although each embodiment has been described in detail above, these are merely examples 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. In addition, the technology exemplified in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives is itself technically useful. [Explanation of symbols]

[0145] 2: Hot water device 10: Heat source unit 12: 1st heat source machine 14:Second heat source machine 16: Water supply channel 18: Hot water outlet 18a: Hot water outlet temperature thermistor 20: Bypass road 22: Bypass servo 24: Pouring channel 26: Bath valve 28: Water level sensor 30:Circulation route 30a: Circulation forward thermistor 32: Circulation return route 32a: Circulation return thermistor 34: Bathtub circulation pump 36: Water flow switch 50: Air pressure dissolving unit 52: Tank 52a: Low water level electrode 52b: High water level electrode 52c: Earth electrode 54: Tank pressure sensor 60: Return to heat source 62: First bathtub waterway 64:Tank outbound 66:Communication path 68:Heat source outward route 70: Second bathtub waterway 74: Tank Return 74a: Water supply port 80: First three-way valve 82: 2nd three-way valve 84: Check valve 86: Tank water supply valve 88: First pressure pump 90: Second pressure pump 92: Tank circulation route 92a: Outlet 92b:Inlet 94: Tank Circulation Pump 96: Gas introduction mechanism 98: Water Inlet 100: Outlet pipe 102: Venturi tube 104: Gas inlet passage 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: Check valve 140b: Check valve 140c: Check valve 140d: Check valve 142: Microbubble generating nozzle 150: Control device 152: Memory 154: Remote control 200: Water supply source 250: Karan

Claims

1. A tank for dissolving gas under pressure in liquid; a tank supply line for supplying the liquid to the tank; a pressure pump provided in the tank supply line; a tank discharge passage for discharging the liquid in which the gas is pressurized and dissolved from the tank to a liquid tank; a fine bubble generating nozzle provided in the tank discharge path for generating fine bubbles by reducing the pressure of the liquid in which the gas is pressurized and dissolved; a tank circulation path that is provided separately from the tank discharge path and that sends the liquid from an outlet connected to the tank to an inlet connected to the tank; a tank circulation pump provided in the tank circulation path; a gas introduction mechanism provided in the tank circulation path; A control device is provided. The gas introduction mechanism includes: a pressure reducing section for reducing the pressure of the liquid and passing the liquid therethrough; a gas inlet port that introduces the gas by negative pressure of the liquid in the pressure reducing section, the control device is capable of executing a fine bubble generating operation in which the pressurizing pump is driven to pressurize and supply the liquid from the tank supply path to the tank, and the liquid in which the gas is pressurized and dissolved is supplied from the tank to the liquid tank via the tank discharge path, During the execution of the fine-bubble generating operation, the control device drives the tank circulation pump to circulate the liquid in the tank through the tank circulation path, thereby supplying the gas introduced by the gas introduction mechanism to the tank.

2. 2. The fine-bubble generating device according to claim 1, wherein the gas introducing mechanism is disposed upstream of the tank circulation pump in the tank circulation path.

3. a gas introduction valve for opening and closing the gas introduction port; a first liquid level electrode capable of detecting whether the liquid level in the tank is equal to or higher than a first liquid level; The liquid level detecting device further includes a second liquid level electrode capable of detecting whether the liquid level in the tank is equal to or higher than a second liquid level that is higher than the first liquid level, a liquid level at a point where the outlet to the tank circulation path is connected to the tank is lower than the first liquid level; The control device includes: during the fine bubble generating operation, when the first liquid level electrode detects that the liquid level in the tank is lower than the first liquid level with the gas introduction valve open, the gas introduction valve is closed; 3. The fine-bubble generating device of claim 1, wherein, during the fine-bubble generating operation, when the second liquid level electrode detects that the liquid level in the tank is higher than the second liquid level with the gas introduction valve closed, the gas introduction valve is opened.

4. 4. The fine-bubble generating device according to claim 3, wherein the control device continues to drive the tank circulating pump even while the gas introduction valve is closed during the fine-bubble generating operation.

5. The control device includes: during the fine bubble generating operation, a time elapsed from when the second level electrode detects that the liquid level in the tank is higher than the second liquid level and the gas introduction valve is opened until when the first level electrode detects that the liquid level in the tank is lower than the first liquid level and the gas introduction valve is closed is specified as an intake time; 5. The fine-bubble generating device according to claim 3 or 4, wherein the rotation speed of the tank circulating pump when the tank circulating pump is driven thereafter with the gas introduction valve open is adjusted according to the intake time.

6. The control device includes: When the intake time exceeds a first intake time, the rotation speed of the tank circulating pump is increased when the tank circulating pump is driven thereafter with the gas introduction valve open; 6. The fine-bubble generating device of claim 5, configured such that, when the intake time falls below a second intake time that is shorter than the first intake time, the rotation speed of the tank circulating pump is reduced when the tank circulating pump is subsequently driven with the gas introduction valve open.

7. a first liquid level electrode capable of detecting whether the liquid level in the tank is equal to or higher than a first liquid level; The liquid level detecting device further includes a second liquid level electrode capable of detecting whether the liquid level in the tank is equal to or higher than a second liquid level that is higher than the first liquid level, a liquid level at a point where the outlet to the tank circulation path is connected to the tank is lower than the first liquid level; The control device includes: In the fine bubble generating operation, when the first liquid level electrode detects that the liquid level in the tank is lower than the first liquid level, the rotation speed of the tank circulating pump is reduced; 3. The fine-bubble generating device of claim 1 or 2, configured to increase the rotation speed of the tank circulating pump when the second liquid level electrode detects that the liquid level in the tank is higher than the second liquid level during the fine-bubble generating operation.

8. The control device includes: Identifying environmental parameters according to the environment in which the micro-bubble generating device is installed; The fine-bubble generating device according to claim 1 , further comprising: a pressure pump configured to adjust a rotation speed of the pressure pump during the fine-bubble generating operation in accordance with the environmental parameter.

9. The fine-bubble generating device of claim 8, wherein the environmental parameters include an installation position of the liquid tank relative to the fine-bubble generating device, a piping diameter of at least a portion of the tank discharge path, a piping length of at least a portion of the tank discharge path, a piping diameter of at least a portion of the tank supply path, and / or a piping length of at least a portion of the tank supply path.

10. The tank pressure sensor is provided in the tank and detects the pressure in the tank as a tank pressure. The fine bubble generating device according to any one of claims 1 to 7, wherein the control device is configured to adjust the rotation speed of the pressure pump in accordance with the tank pressure detected by the tank pressure sensor during the fine bubble generating operation.

11. The fine-bubble generating device of claim 10, wherein the control device is configured to reduce the rotation speed of the pressurizing pump when the tank pressure detected by the tank pressure sensor exceeds a first tank pressure during the fine-bubble generating operation, and to increase the rotation speed of the pressurizing pump when the tank pressure falls below a second tank pressure lower than the first tank pressure.

12. the liquid is water, The fine bubble generating device according to claim 1 , wherein the liquid tank is a bathtub used by a user for bathing.

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