Microbubble generator

Abstract

To provide a technique that can continue to stably generate microbubbles in liquid in a liquid tank.SOLUTION: A control device for a microbubble generating apparatus can perform a microbubble generating operation that drives a pressurizing pump to pressurize and supply liquid to a tank through a tank supply passage, and supply liquid in which gas is dissolved by pressure from the tank to a liquid tank through a tank discharge passage. The control device can perform: a first tank circulation operation in which the liquid in the tank is circulated in a tank circulation path by a tank circulation pump with a gas introduction valve open during the microbubble generating operation; and a second tank circulation operation in which the liquid in the tank is circulated in the tank circulation path by the tank circulation pump with the gas introduction valve closed. The control device drives the tank circulation pump at a first rotation speed in the first tank circulation operation, and drives the tank circulation pump at a second rotation speed lower than the first rotation speed in the second tank circulation operation.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, the gas introduction operation and the micro-bubble generation operation cannot be performed simultaneously, and the gas introduction operation supplies gas to the tank, and the micro-bubble generation operation consumes gas from the tank, 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, a gas introduction port for introducing the gas by the negative pressure of the liquid in the pressure reduction section, and a gas introduction valve for opening and closing the gas introduction port. 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 vat via the tank discharge path. The control device is capable of executing a first tank circulation operation in which the tank circulation pump circulates the liquid in the tank through the tank circulation path with the gas introduction valve open, and a second tank circulation operation in which the tank circulation pump circulates the liquid in the tank through the tank circulation path with the gas introduction valve closed, during the fine bubble generating operation. The control device is configured to drive the tank circulation pump at a first rotation speed in the first tank circulation operation, and to drive the tank circulation pump at a second rotation speed lower than the first rotation speed in the second tank circulation operation.

[0006] In the above-mentioned fine-bubble generator, even when the fine-bubble generating operation is being performed, the first tank circulation operation is performed, so that the gas can be introduced by the gas introduction mechanism and the gas can be supplied to the tank. 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 performed continuously. With this configuration, fine bubbles can be stably generated continuously in the liquid in the liquid vat.

[0007] In addition, in the above-mentioned fine-bubble generating device, when the first tank circulation operation or the second tank circulation operation is performed during the fine-bubble generating operation, 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 into the liquid in the tank is promoted. According to the above-mentioned configuration, by performing the first tank circulation operation or the second tank circulation operation during the fine-bubble generating operation, the liquid in the tank flows intensely, and the pressurized dissolution of the gas into the liquid in the tank can be further promoted.

[0008] In the first tank circulation operation, gas is introduced into the pressure reducing section of the gas introduction mechanism, and the negative pressure of the liquid in the pressure reducing section is alleviated by mixing the gas with the liquid, but in the second tank circulation operation, gas is not introduced into the pressure reducing section of the gas introduction mechanism, and the negative pressure of the liquid in the pressure reducing section is not alleviated. For this reason, if the rotation speed of the tank circulation pump is the same in the first tank circulation operation and the second tank circulation operation, the pressure of the liquid in the pressure reducing section of the gas introduction mechanism will be lower in the second tank circulation operation than in the first tank circulation operation. If the pressure of the liquid in the pressure reducing section of the gas introduction mechanism becomes excessively low, cavitation may occur in the pressure reducing section, causing noise. According to the above configuration, by setting the rotation speed of the tank circulation pump during the second tank circulation operation lower than the rotation speed of the tank circulation pump during the first tank circulation operation, it is possible to prevent the pressure of the liquid in the pressure reduction section of the gas introduction mechanism from becoming excessively low during the second tank circulation operation. This makes it possible to prevent the occurrence of cavitation in the pressure reduction section of the gas introduction mechanism and to prevent noise from being generated during the second tank circulation operation.

[0009] Furthermore, when the first tank circulation operation is performed during the fine bubble generation operation, as the flow rate of the liquid flowing through the pressure reducing section of the gas introduction mechanism increases, the pressure of the liquid in the pressure reducing section decreases accordingly, and more gas can be introduced by the gas introduction mechanism. According to the above configuration, by making the rotation speed of the tank circulation pump in the first tank circulation operation higher than the rotation speed of the tank circulation pump in the second tank circulation operation, more gas can be introduced by the gas introduction mechanism in the first tank circulation operation.

[0010] In the fine-bubble generating device, the gas introducing mechanism may be disposed upstream of the tank circulation pump in the tank circulation path.

[0011] In the first tank circulation operation, when the gas introduction mechanism is disposed upstream of the tank circulation pump in the tank circulation path, the gas introduced by the gas introduction mechanism is mixed with the liquid and flows into the tank circulation pump. Therefore, compared to when the gas introduction mechanism is disposed downstream of the tank circulation pump in the tank circulation path, the efficiency of the tank circulation pump decreases, and the flow rate of the liquid flowing through the pressure reduction section of the gas introduction mechanism becomes smaller. In contrast, in the second tank circulation operation, even if the gas introduction mechanism is disposed upstream of the tank circulation pump in the tank circulation path, the gas introduction mechanism does not introduce gas, so compared to when the gas introduction mechanism is disposed downstream of the tank circulation path, the efficiency of the tank circulation pump does not decrease, and the flow rate of the liquid flowing through the pressure reduction section of the gas introduction mechanism does not become smaller. Therefore, if the rotation speed of the tank circulation pump is the same in the first tank circulation operation and the second tank circulation operation, the flow rate of the liquid flowing through the pressure reduction section of the gas introduction mechanism is larger in the second tank circulation operation than in the first tank circulation operation, and the pressure of the liquid in the pressure reduction section of the gas introduction mechanism becomes lower. This makes it easier for cavitation to occur in the pressure reducing section of the gas introduction mechanism, and makes it easier for noise to occur. According to the above configuration, by setting the rotation speed of the tank circulation pump in the second tank circulation operation lower than the rotation speed of the tank circulation pump in the first tank circulation operation, it is possible to suppress the occurrence of cavitation in the pressure reducing section and suppress the generation of noise in the second tank circulation operation.

[0012] In addition, when the gas introduction mechanism is disposed upstream of the tank circulation pump in the tank circulation path, the suction pressure of the tank circulation pump acts on the pressure reducing section of the gas introduction mechanism, so the pressure of the liquid in the pressure reducing section is lower than when the gas introduction mechanism is disposed downstream of the tank circulation pump in the tank circulation path. Therefore, the amount of gas introduced by the gas introduction mechanism can be increased in the first tank circulation operation. In addition, 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 in the first tank circulation operation, they are agitated by the impeller of the tank circulation pump, so that dissolution of the gas into the liquid can be further promoted.

[0013] 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 terminate the first tank circulation operation and start the second tank circulation operation when the fine-bubble generating operation is being performed and it is detected that the liquid level in the tank is lower than the first liquid level while the control device is performing the first tank circulation operation, and to terminate the second tank circulation operation and start the first tank circulation operation when the fine-bubble generating operation is being performed and it is detected that the liquid level in the tank is higher than the second liquid level while the control device is performing the second tank circulation operation.

[0014] 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 first tank circulation operation is executed while the tank circulation pump is driven, gas is introduced by the gas introduction mechanism, and when the second tank circulation operation is executed, gas is not introduced by the gas introduction mechanism. According to the above configuration, the control device selectively executes either the first tank circulation operation or the second tank circulation operation 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.

[0015] The gas introduction valve may be configured to receive a force in a direction to close the gas introduction valve by a negative pressure of the liquid in the pressure reducing section. When the first tank circulation operation is terminated and the second tank circulation operation is started, the control device may be configured to reduce a rotation speed of the tank circulation pump from the first rotation speed to the second rotation speed while continuing to drive the tank circulation pump, and thereafter close the gas introduction valve.

[0016] In the above configuration, the negative pressure of the liquid in the pressure reducing section acts on the gas introduction valve in a direction to close the gas introduction valve. Therefore, when the pressure of the liquid in the pressure reducing section is low, if the gas introduction valve is switched from an open state to a closed state, the valve element of the gas introduction valve will collide strongly against the valve seat, which may cause noise generation and damage to the gas introduction valve. In the above configuration, when the first tank circulation operation is ended and the second tank circulation operation is started, the control device reduces the rotation speed of the tank circulation pump to increase the pressure of the liquid in the pressure reducing section, and then switches the gas introduction valve from an open state to a closed state. This makes it possible to suppress noise generation and damage to the gas introduction valve caused by the valve element of the gas introduction valve colliding strongly against the valve seat.

[0017] The gas introduction valve may be configured to receive a force in a direction to close the gas introduction valve by a negative pressure of the liquid in the pressure reducing section. The control device may be configured to open the gas introduction valve while continuing to drive the tank circulation pump, when terminating the second tank circulation operation and starting the first tank circulation operation, and thereafter increase the rotation speed of the tank circulation pump from the second rotation speed to the first rotation speed.

[0018] In the above configuration, the negative pressure of the liquid in the pressure reducing section acts on the gas introduction valve in a direction to close the gas introduction valve. Therefore, when attempting to switch the gas introduction valve from a closed state to an open state while the pressure of the liquid in the pressure reducing section is low, the gas introduction valve may not operate smoothly. In the above configuration, when terminating the second tank circulation operation and starting the first tank circulation operation, the control device switches the gas introduction valve from a closed state to an open state, and then increases the rotation speed of the tank circulation pump to reduce the pressure of the liquid in the pressure reducing section. This allows the gas introduction valve to operate smoothly.

[0019] 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.

[0020] 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]

[0021] [Figure 1] FIG. 2 is a diagram showing a schematic configuration of a water heating device 2 of the embodiment. [Diagram 2] 2 is a schematic cross-sectional view of a bathtub adaptor 132 of the hot water heater 2 of the embodiment. FIG. [Diagram 3] 10 is a flowchart of the process executed by the control device 150 during the hot water filling operation of the hot water device 2 of the embodiment. [Figure 4] FIG. 2 is a diagram showing a schematic example of a water flow in the hot water device 2 of the embodiment. [Diagram 5]5 is a diagram showing a schematic diagram of another example of the water flow in the hot water device 2 of the 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 of the embodiment. [Figure 7] FIG. 10 is a diagram showing a schematic diagram of still another example of the water flow in the hot water device 2 of the embodiment. [Figure 8] FIG. 10 is a diagram showing a schematic diagram of still another example of the water flow in the hot water device 2 of the embodiment. [Figure 9] 13 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 modified example. [Figure 10] FIG. 11 is a diagram showing a schematic configuration of a water heating device 2 according to another modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] (Example) 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.

[0023] (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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] (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 connection path 76, a tank outward path 64, a communicating path 66, a first three-way valve 80, a second three-way valve 82, a check valve 84, a tank supply valve 86, a first pressurization pump 88, a second pressurization pump 90, a tank suction path 92, a tank circulation pump 94, and a gas introduction mechanism 96.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] The upstream end of the tank return line 74 is connected to the heat source outward line 68, and the downstream end of the tank return line 74 is connected to the upstream end of the tank connection line 76. The downstream end of the tank connection line 76 (hereinafter also referred to as the inlet 76a) is connected to the top of the tank 52. The water level at the point where the inlet 76a of the tank connection line 76 is connected to the tank 52 is higher than the upper limit water level detected by the high water level electrode 52b. The 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. The first pressurizing pump 88 and the second pressurizing pump 90 are provided downstream of the tank water supply valve 86 in the tank return line 74. The first pressurizing pump 88 and the second pressurizing pump 90 pressurize the water in the tank return line 74 and send it toward the tank connection line 76. In the tank return line 74, the first pressurizing pump 88 is provided upstream of the second pressurizing pump 90. The water sent from the tank return line 74 to the tank connecting line 76 flows into the tank 52 via the inlet 76a.

[0034] An upstream end of the tank suction passage 92 (hereinafter also referred to as an outlet 92a) is connected to the bottom of the tank 52. The water level at the point where the outlet 92a of the tank suction passage 92 is connected to the tank 52 is lower than the lower limit water level detected by the low water level electrode 52a. A downstream end of the tank suction passage 92 is connected to the upstream end of the tank connection passage 76. A tank circulation pump 94 is provided in the tank suction passage 92. The tank circulation pump 94 sucks water from the tank 52 into the tank suction passage 92 through the outlet 92a, and sends water from the tank suction passage 92 toward the tank connection passage 76. The water sent from the tank suction passage 92 to the tank connection passage 76 flows into the tank 52 through the inlet 76a.

[0035] The gas introduction mechanism 96 is provided in the tank suction passage 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 passage 104, and a gas introduction valve 106. Water flows into the water inlet pipe 98 from the upstream side of the tank suction passage 92. The water outlet pipe 100 causes water to flow out to the downstream side of the tank suction passage 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 passage 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. The gas introduction valve 106 is provided in the gas introduction passage 104 and opens and closes the gas introduction passage 104. The gas introduction valve 106 includes a valve body (not shown), a valve seat (not shown), a spring (not shown) that biases the valve body in a direction to seat on the valve seat, and a solenoid (not shown) that moves the valve body in a direction to move away from the valve seat. When the valve body is seated on the valve seat by the biasing force of the spring, the gas introduction valve 106 is closed. When the valve body is moved away from the valve seat by the drive of the solenoid, the gas introduction valve 106 is opened. When water flows through the gas introduction mechanism 96, if the gas introduction valve 106 is open, air is sucked into the gas introduction passage 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 passage 104 is mixed with the water flowing through the tank suction passage 92 and flows into the tank 52 through the tank connection passage 76. The gas introduction valve 106 is normally closed, and is opened when the solenoid is driven by the control device 150, which will be described later. The negative pressure of the water in the Venturi tube 102 acts on the gas introduction valve 106 in a direction to close the gas introduction valve 106.

[0036] 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 suction 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.

[0037] (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).

[0038] 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.

[0039] 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.

[0040] (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.

[0041] (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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] (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.

[0053] 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.

[0054] In S34, the control device 150 drives the tank circulation pump 94. This starts the circulation of water between the tank 52 and the tank suction path 92 and the tank connection path 76. When driving the tank circulation pump 94 in S34, the control device 150 controls the tank circulation pump 94 so that the rotation speed of the tank circulation pump 94 becomes a predetermined second rotation speed. The second rotation speed is a rotation speed lower than a first rotation speed described later, and is, for example, 80% of the first rotation speed.

[0055] 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 suction passage 92.

[0056] In S38, the control device 150 controls the tank circulating pump 94 so that the rotation speed of the tank circulating pump 94 becomes a predetermined first rotation speed.

[0057] In S40, the control device 150 starts supplying water containing dissolved air 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, water from the bathtub 130 is supplied to the tank 52 via the bathtub adapter 132, the second bathtub water passage 70, the second three-way valve 82, the communication passage 66, the heat source return passage 60, the circulation return passage 32, the second heat source unit 14, the circulation outward passage 30, the heat source outward passage 68, the tank return passage 74, and the tank connection passage 76. At this time, water pressurized by the first pressurizing pump 88 and the second pressurizing pump 90 is supplied 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.

[0058] In S42, 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 falls. If the water level of the tank 52 falls below the lower limit water level (if YES), the process proceeds to S44. If the water level of the tank 52 is equal to or greater than the lower limit water level (if NO), the process proceeds to S48.

[0059] In S44, the control device 150 controls the tank circulating pump 94 so that the rotation speed of the tank circulating pump 94 becomes the second rotation speed.

[0060] In S46, 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 suction passage 92. Note that in this embodiment, even while the gas introduction valve 106 is closed, the tank circulation pump 94 continues to be driven. This promotes the flow of water in the tank 52, and promotes the pressurized dissolution of air into the water in the tank 52.

[0061] In S48, 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 S50. If the water level of the tank 52 is below the upper water level (NO), the process proceeds to S54.

[0062] In S50, 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 suction passage 92.

[0063] In S52, the control device 150 controls the tank circulating pump 94 so that the rotation speed of the tank circulating pump 94 becomes the first rotation speed.

[0064] In S54, 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 S42. If the operation time has reached the set time (if YES), the process proceeds to S56.

[0065] In S56, the control device 150 stops the bathtub circulating pump 34, the first pressurizing pump 88, and the second pressurizing pump 90, and ends the supply of air-dissolved water from the tank 52 to the bathtub 130.

[0066] In S58, 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 suction passage 92.

[0067] In S60, 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 connection path 76, 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, the tank suction path 92, and the tank connection path 76.

[0068] In S62, the control device 150 stops the tank circulation pump 94. This ends the circulation of water between the tank 52 and the tank suction passage 92 and the tank connection passage 76. After S62, the processing in FIG. 6 ends.

[0069] (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.

[0070] (Modification) In the above-described hot water device 2, when performing the fine bubble generating operation, the control device 150 may execute the process shown in Fig. 9 instead of executing 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.

[0071] 9, after S40 and if NO in S54, the process proceeds to S64. In S64, the control device 150 waits until the time that has elapsed since the gas introduction valve 106 was opened in S36 or S50 reaches a first predetermined time. The first predetermined time is an estimated time for the water level of the tank 52 to drop from the upper limit water level to the lower limit water level with the gas introduction valve 106 open, and is shorter than the time set in S54. When the time that has elapsed since the gas introduction valve 106 was opened reaches the first predetermined time (YES), the process proceeds to S44.

[0072] 9, after S46, the process proceeds to S66. In S66, the control device 150 waits until the time that has elapsed since the gas introduction valve 106 was closed in S46 reaches a second predetermined time. The second predetermined time is an estimated time for the water level of the tank 52 to rise from the lower limit water level to the upper limit water level with the gas introduction valve 106 closed, and is shorter than the time set in S54. When the time that has elapsed since the gas introduction valve 106 was closed reaches the second predetermined time (YES), the process proceeds to S50.

[0073] According to the process shown in FIG. 9, the gas introduction valve 106 can be switched between open and closed states without using detection signals from the low water level electrode 52a and the high water level electrode 52b.

[0074] (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 or FIG. 9 may be omitted.

[0075] In the above-described hot water apparatus 2, the tank cleaning process of S60 in FIG. 6 or FIG. 9 may be omitted.

[0076] In the above-mentioned hot water device 2, even if the operating time reaches the set time in the operating time determination process of S54 in Figures 6 and 9, the process may be configured to return to S42 or S64 and continue the fine bubble generating operation without proceeding to S56 until the user instructs the end of the fine bubble generating operation via the remote control 154.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] In the above-described hot water device 2, a check valve (not shown) may be provided downstream of the tank circulation pump 94 in the tank suction passage 92 to allow water to flow from the upstream side to the downstream side of the tank suction passage 92 and to prohibit water from flowing from the downstream side to the upstream side of the tank suction passage 92. By providing a check valve in the tank suction passage 92, it is possible to prevent water pumped out from the tank return passage 74 by the first pressurizing pump 88 and the second pressurizing pump 90 from flowing back through the tank suction passage 92, even if the tank circulation pump 94 is stopped while the first pressurizing pump 88 and the second pressurizing pump 90 are being driven.

[0083] In the above-described hot water device 2, the gas introduction mechanism 96 is disposed in the tank suction passage 92 upstream of the tank circulation pump 94. Alternatively, the gas introduction mechanism 96 may be disposed in the tank suction passage 92 downstream of the tank circulation pump 94.

[0084] In the above-described hot water device 2, the downstream end of the tank return passage 74 and the downstream end of the tank suction passage 92 are connected to the tank 52 via a common tank connection passage 76. Alternatively, as shown in Fig. 10, the air pressurization dissolution unit 50 may not include the tank connection passage 76, and the downstream end of the tank return passage 74 (hereinafter also referred to as inlet 74a) and the downstream end of the tank suction passage 92 (hereinafter also referred to as inlet 92b) may be configured to be connected separately to the tank 52. In this case, the water flowing through the tank return passage 74 flows into the tank 52 via the inlet 74a, and the water flowing through the tank suction passage 92 flows into the tank 52 via the inlet 92b.

[0085] As described above, in one or more embodiments, the hot water device 2 (an example of a fine-bubble generating device) includes a tank 52 that pressurizes and dissolves air (an example of a gas) in water (an example of a liquid), a tank return path 74 that supplies water to the tank 52, a tank connection path 76 (an example of a tank supply path), a first pressure pump 88 and a second pressure pump 90 (an example of a pressure pump) provided in the tank return path 74, a tank outward path 64 that discharges the water in which air has been pressurized and dissolved from the tank 52 to a bathtub 130 (an example of a liquid tank), a first bathtub water path 62, and a bathtub adapter 132 (an example of a tank discharge path), The device is provided with a fine bubble generating nozzle 142 that is provided in the bathtub adaptor 132 and generates fine bubbles by reducing the pressure of water in which air is pressurized and dissolved, a tank suction passage 92 that is provided separately from the tank outflow passage 64, the first bathtub water passage 62, and the bathtub adaptor 132 and sends water from an outlet 92a connected to the tank 52 to an inlet 76a connected to the tank 52, a tank connection passage 76 (an example of a tank circulation passage), a tank circulation pump 94 provided in the tank suction passage 92, a gas introduction mechanism 96 provided in the tank suction passage 92, and a control device 150. The gas introduction mechanism 96 is provided with a Venturi tube 102 (an example of a pressure reducing section) that reduces the pressure of the water and passes it through, a gas introduction port 104a that introduces air by the negative pressure of the water in the Venturi tube 102, and a gas introduction valve 106 that opens and closes the gas introduction port 104a. The control device 150 can perform a fine bubble generating operation in which water is pressurized and supplied to the tank 52 from the tank return line 74 and the tank connection line 76 by driving the first pressurizing pump 88 and the second pressurizing pump 90, and water in which air is 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. During the fine bubble generating operation, the control device 150 can perform a first tank circulation operation in which the water in the tank 52 is circulated through the tank suction line 92 and the tank connection line 76 by the tank circulation pump 94 with the gas introduction valve 106 open, and a second tank circulation operation in which the water in the tank 52 is circulated through the tank suction line 92 and the tank connection line 76 by the tank circulation pump 94 with the gas introduction valve 106 closed. The control device 150 is configured to drive the tank circulation pump 94 at a first rotation speed in the first tank circulation operation, and to drive the tank circulation pump 94 at a second rotation speed lower than the first rotation speed in the second tank circulation operation.

[0086] In the above-described hot water device 2, even when the fine bubble generating operation is being performed, the first tank circulation operation is performed, so that air can be introduced by the gas introduction mechanism 96 and supplied to the tank 52. Therefore, there is no need to interrupt the fine bubble generating operation to supply air to the tank 52, and the fine bubble generating operation can be performed continuously. With this configuration, fine bubbles can be stably generated continuously in the water of the bathtub 130.

[0087] Furthermore, in the above-described hot water device 2, when the first tank circulation operation or the second tank circulation operation is performed while the fine bubble generation operation is being performed, the flow of water in the tank 52 becomes intense. In the pressurized dissolution type tank 52, the more intense the flow of 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-described configuration, by performing the first tank circulation operation or the second tank circulation operation while the fine bubble generation operation is being performed, 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.

[0088] In the first tank circulation operation, air is introduced into the Venturi tube 102 of the gas introduction mechanism 96, and the negative pressure of the water in the Venturi tube 102 is alleviated by mixing the air with the water. However, in the second tank circulation operation, air is not introduced into the Venturi tube 102 of the gas introduction mechanism 96, and the negative pressure of the water in the Venturi tube 102 is not alleviated. For this reason, if the rotation speed of the tank circulation pump 94 is the same in the first tank circulation operation and the second tank circulation operation, the water pressure in the Venturi tube 102 of the gas introduction mechanism 96 will be lower in the second tank circulation operation than in the first tank circulation operation. If the water pressure in the Venturi tube 102 of the gas introduction mechanism 96 becomes excessively low, cavitation may occur in the Venturi tube 102, causing noise. According to the above configuration, by setting the rotation speed of the tank circulation pump 94 during the second tank circulation operation lower than the rotation speed of the tank circulation pump 94 during the first tank circulation operation, it is possible to prevent the water pressure in the Venturi tube 102 of the gas introduction mechanism 96 from becoming excessively low during the second tank circulation operation. This makes it possible to prevent the occurrence of cavitation in the Venturi tube 102 of the gas introduction mechanism 96 and to prevent noise from being generated during the second tank circulation operation.

[0089] Furthermore, when the first tank circulation operation is performed during the fine bubble generation operation, as the flow rate of the water flowing through the Venturi tube 102 of the gas introduction mechanism 96 increases, the water pressure in the Venturi tube 102 decreases accordingly, and more air can be introduced by the gas introduction mechanism 96. According to the above configuration, by making the rotation speed of the tank circulation pump 94 in the first tank circulation operation higher than the rotation speed of the tank circulation pump 94 in the second tank circulation operation, more air can be introduced by the gas introduction mechanism 96 in the first tank circulation operation.

[0090] In one or more embodiments, the gas introduction mechanism 96 is disposed in the tank suction line 92 upstream of the tank circulation pump 94 .

[0091] In the first tank circulation operation, when the gas introduction mechanism 96 is disposed upstream of the tank circulation pump 94 in the tank suction path 92, the air introduced by the gas introduction mechanism 96 is mixed with the water and flows into the tank circulation pump 94. Therefore, compared to when the gas introduction mechanism 96 is disposed downstream of the tank circulation pump 94 in the tank suction path 92, the efficiency of the tank circulation pump 94 decreases and the flow rate of water flowing through the Venturi tube 102 of the gas introduction mechanism 96 decreases. In contrast, in the second tank circulation operation, even when the gas introduction mechanism 96 is disposed upstream of the tank circulation pump 94 in the tank suction path 92, air is not introduced by the gas introduction mechanism 96, so compared to when the gas introduction mechanism 96 is disposed downstream of the tank circulation pump 94 in the tank suction path 92, the efficiency of the tank circulation pump 94 does not decrease and the flow rate of water flowing through the Venturi tube 102 of the gas introduction mechanism 96 does not decrease. For this reason, if the rotation speed of the tank circulation pump 94 is the same in the first tank circulation operation and the second tank circulation operation, the flow rate of water flowing through the Venturi tube 102 of the gas introduction mechanism 96 is greater in the second tank circulation operation than in the first tank circulation operation, and the water pressure in the Venturi tube 102 of the gas introduction mechanism 96 is lower. This makes it easier for cavitation to occur in the Venturi tube 102 of the gas introduction mechanism 96, and makes it easier for noise to occur. According to the above configuration, by setting the rotation speed of the tank circulation pump 94 in the second tank circulation operation lower than the rotation speed of the tank circulation pump 94 in the first tank circulation operation, it is possible to suppress the occurrence of cavitation in the Venturi tube 102 and suppress the occurrence of noise in the second tank circulation operation.

[0092] Furthermore, when the gas introduction mechanism 96 is disposed upstream of the tank circulation pump 94 in the tank suction passage 92, the suction pressure of the tank circulation pump 94 acts on the Venturi tube 102 of the gas introduction mechanism 96, so the water pressure in the Venturi tube 102 is lower than when the gas introduction mechanism 96 is disposed downstream of the tank circulation pump 94 in the tank suction passage 92. Therefore, the amount of air introduced by the gas introduction mechanism 96 can be increased in the first tank circulation operation. Furthermore, according to the above configuration, when the air introduced by the gas introduction mechanism 96 and the water flowing through the tank suction passage 92 pass through the tank circulation pump 94 in the first tank circulation operation, they are agitated by the impeller of the tank circulation pump 94, so that dissolution of air into water can be further promoted.

[0093] 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) higher than the lower limit water level. The water level at the point where the outlet 92a to the tank suction passage 92 is connected to the tank 52 is lower than the lower limit water level. The control device 150 is configured to terminate the first tank circulation operation and start the second tank circulation operation when the fine bubble generating operation is being performed and the first tank circulation operation is being performed and it is detected that the water level of the tank 52 is lower than the lower limit water level, and to terminate the second tank circulation operation and start the first tank circulation operation when the fine bubble generating operation is being performed and the second tank circulation operation is being performed and it is detected that the water level of the tank 52 is higher than the upper limit water level, and to terminate the second tank circulation operation and start the first tank circulation operation.

[0094] 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 first tank circulation operation is executed while the tank circulation pump 94 is driven, air is introduced by the gas introduction mechanism 96, and when the second tank circulation operation is executed, air is not introduced by the gas introduction mechanism 96. According to the above configuration, the control device 150 selectively executes either the first tank circulation operation or the second tank circulation operation 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.

[0095] In one or more embodiments, the gas introduction valve 106 is configured to receive a force in a direction to close the gas introduction valve 106 due to the negative pressure of the water in the Venturi tube 102. When the first tank circulation operation is ended and the second tank circulation operation is started, the control device 150 is configured to reduce the rotation speed of the tank circulation pump 94 from the first rotation speed to the second rotation speed while continuing to drive the tank circulation pump 94, and then close the gas introduction valve 106.

[0096] In the above configuration, the negative pressure of the water in the Venturi tube 102 acts on the gas introduction valve 106 in a direction to close the gas introduction valve 106. Therefore, when the water pressure in the Venturi tube 102 is low, if the gas introduction valve 106 is switched from an open state to a closed state, the valve body of the gas introduction valve 106 may strongly collide with the valve seat, which may cause noise generation and damage to the gas introduction valve 106. In the above configuration, when the first tank circulation operation is ended and the second tank circulation operation is started, the control device 150 reduces the rotation speed of the tank circulation pump 94 to increase the water pressure in the Venturi tube 102, and then switches the gas introduction valve 106 from an open state to a closed state. This makes it possible to suppress noise generation and damage to the gas introduction valve 106 caused by the valve body of the gas introduction valve 106 strongly colliding with the valve seat.

[0097] In one or more embodiments, the gas introduction valve 106 is configured to receive a force in a direction to close the gas introduction valve 106 due to the negative pressure of the water in the Venturi tube 102. When terminating the second tank circulation operation and starting the first tank circulation operation, the control device 150 is configured to open the gas introduction valve 106 while continuing to drive the tank circulation pump 94, and then to increase the rotation speed of the tank circulation pump 94 from the second rotation speed to the first rotation speed.

[0098] In the above configuration, the negative pressure of the water in the Venturi tube 102 acts on the gas introduction valve 106 in a direction to close the gas introduction valve 106. For this reason, when the water pressure in the Venturi tube 102 is low, if the gas introduction valve 106 is switched from a closed state to an open state, the gas introduction valve 106 may not operate smoothly. In the above configuration, when the control device 150 ends the second tank circulation operation and starts the first tank circulation operation, the control device 150 switches the gas introduction valve 106 from a closed state to an open state, and then increases the rotation speed of the tank circulation pump 94 to reduce the water pressure in the Venturi tube 102. This allows the gas introduction valve 106 to operate smoothly.

[0099] 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]

[0100] 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 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:Inlet 76: Tank connection 76a:Inlet 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 suction passage 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 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; A gas introduction valve is provided for opening and closing the gas introduction port, 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, the control device is capable of executing a first tank circulation operation in which, during execution of the fine bubble generating operation, the liquid in the tank is circulated through the tank circulation path by the tank circulation pump with the gas introduction valve open, and a second tank circulation operation in which, during execution of the fine bubble generating operation, the liquid in the tank is circulated through the tank circulation path by the tank circulation pump with the gas introduction valve closed, The control device is configured to drive the tank circulation pump at a first rotation speed during the first tank circulation operation, and to drive the tank circulation pump at a second rotation speed lower than the first rotation speed during the second tank circulation operation.

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 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: when it is detected that the liquid level in the tank is lower than the first liquid level while the fine bubble generating operation is being performed and the first tank circulation operation is being performed, the first tank circulation operation is terminated and the second tank circulation operation is started; 3. The fine-bubble generating device of claim 1 or 2, configured to terminate the second tank circulation operation and start the first tank circulation operation when it is detected that the liquid level in the tank is higher than the second liquid level while the fine-bubble generating operation is being performed and the second tank circulation operation is being performed.

4. the gas introduction valve is configured to receive a force in a direction to close the gas introduction valve by a negative pressure of the liquid in the pressure reducing section, 4. The fine-bubble generating device of claim 1, wherein the control device is configured to, when terminating the first tank circulation operation and starting the second tank circulation operation, reduce the rotation speed of the tank circulation pump from the first rotation speed to the second rotation speed while continuing to drive the tank circulation pump, and then close the gas introduction valve.

5. the gas introduction valve is configured to receive a force in a direction to close the gas introduction valve by a negative pressure of the liquid in the pressure reducing section, 5. The fine-bubble generating device according to claim 1, wherein the control device is configured to, when terminating the second tank circulation operation and starting the first tank circulation operation, open the gas introduction valve while continuing to drive the tank circulation pump, and then increase the rotation speed of the tank circulation pump from the second rotation speed to the first rotation speed.

6. 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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