KR20230112534A - Fine bubble generating device - Google Patents

Abstract

[Problem] To reduce the amount of information on the liquid level in a tank, and to provide a technique capable of ensuring speedy judgment processing regarding opening and closing of a gas introduction valve.
[Solution] The microbubble generating device disclosed in this specification includes a tank, a tank supply passage, a pressure pump, a tank discharge passage, a microbubble generating nozzle, a tank circulation passage, a tank circulation pump, a gas introducing mechanism, a liquid level electrode, and a control device. The gas introduction mechanism includes a gas introduction port, a pressure reducing portion, and a gas introduction valve that opens and closes the gas introduction port. The control device may perform a micro-bubbling operation in which a pressurized pump is driven to pressurize and supply the liquid to the tank, and the liquid in which gas is dissolved under pressure is supplied from the tank to the liquid tank. While the microbubble generating operation is being executed, 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 from the gas inlet to the tank, and controlling the opening and closing operation of the gas introduction valve based on the information as to whether or not the liquid level in the tank detected by the liquid level electrode is equal to or higher than a predetermined liquid level.

Description

Fine bubble generating device {FINE BUBBLE GENERATING DEVICE}

[0001] The present specification relates to a device for generating microbubbles.

[0002] In Patent Document 1, a tank for dissolving gas under pressure in a liquid, a tank supply passage for supplying the liquid to the tank, a pressurization pump installed in the tank supply passage, a tank discharge passage for discharging the liquid in which the gas is dissolved under pressure from the tank to a liquid tank, a microbubble generating nozzle installed in the tank discharge passage and generating microbubbles by decompressing the liquid in which the gas is dissolved under pressure, and installed separately from the tank discharge passage, the tank Disclosed is a micro-bubble generator comprising a tank circulation path for sending the liquid from an outlet connected to the tank to an inlet connected to the tank, a tank circulation pump installed in the tank circulation path, a gas introducing mechanism installed in the tank circulation path, two liquid level electrodes capable of detecting whether or not the liquid level in the tank is equal to or higher than a predetermined liquid level, and a control device. The gas introduction mechanism includes a decompression portion through which the liquid is reduced and passed therethrough, a gas inlet through which the gas is introduced by negative pressure of the liquid in the decompression portion, and a gas introduction valve which opens and closes the gas inlet. The control device drives the pressure pump to pressurize and supply the liquid from the tank supply passage to the tank, and at the same time supply the liquid in which the gas is dissolved under pressure from the tank to the liquid tank through the tank discharge passage. While the micro-bubble generating operation is being executed, the control device supplies the gas introduced from the gas inlet to the tank by driving the tank circulation pump to circulate the liquid in the tank through the tank circulation path, and information regarding whether or not the liquid level in the tank detected by one of the two liquid level electrodes is above the lower liquid level, and whether or not the liquid level in the tank detected by the other of the two liquid level electrodes is above the upper liquid level Based on the information about, the opening and closing operation of the gas introduction valve is controlled.

[0003] 1. Japanese Patent Laid-Open No. 2015-127052

[0004] In a micro-bubble generator, in order to ensure the speed of the determination process regarding opening and closing of the gas introduction valve, there are cases where it is desired to reduce the amount of information on the liquid level in the tank. In the microbubble generator of Patent Literature 1, the control device is configured to control the opening and closing operation of the gas introduction valve based on information on whether or not the liquid level in the tank is equal to or higher than the lower liquid level and information on whether or not the liquid level in the tank is equal to or higher than the upper liquid level. In such a micro-bubble generating device, since the amount of information on the liquid level in the tank is relatively large, there is a possibility that the speed of the determination process regarding opening and closing of the gas introduction valve may be lacking. In this specification, a technique capable of reducing the amount of information on the liquid level in a tank and ensuring the speed of the judgment process regarding opening and closing of the gas introduction valve is provided. In addition, in this specification, regarding a micro-bubble generating device provided with two liquid-level electrodes, the two liquid-level electrodes are sometimes described as "lower liquid-level electrode" and "upper liquid-level electrode". Here, the "lower liquid level" is a liquid level lower than the "upper liquid level".

[0005] A microbubble generator disclosed in the present specification includes a tank for dissolving gas under pressure in a liquid, a tank supply passage for supplying the liquid to the tank, a pressurization pump installed in the tank supply passage, a tank discharge passage for discharging the liquid in which the gas is dissolved under pressure from the tank into a liquid tank, a microbubble generating nozzle installed in the tank discharge passage and generating micro bubbles by decompressing the liquid in which the gas has been dissolved under pressure, and connected to the tank, and connected to the tank A tank circulation path for sending the liquid from an outlet port connected to the tank to an inlet connected to the tank, a tank circulation pump installed in the tank circulation path, a gas introducing mechanism installed in the tank circulation path, a liquid level electrode capable of detecting whether or not the liquid level in the tank is equal to or higher than a predetermined liquid level, and a control device. The gas introduction mechanism includes a depressurization portion through which the liquid is reduced and passed therethrough, a gas inlet through which the gas is introduced by the negative pressure of the liquid in the decompression portion, and a gas introduction valve which opens and closes the gas inlet. The control device drives the pressure pump to pressurize and supply the liquid from the tank supply passage to the tank, and at the same time supply the liquid in which the gas is dissolved under pressure from the tank to the liquid tank through the tank discharge passage. While the micro-bubble generating operation is being executed, 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 from the gas inlet to the tank, and controlling the opening and closing operation of the gas introduction valve based on information as to whether or not the liquid level in the tank detected by the liquid level electrode is equal to or higher than a predetermined liquid level.

[0006] Another microbubble generating device disclosed in the present specification includes a tank for dissolving gas under pressure in a liquid, a tank supply passage for supplying the liquid to the tank, a pressurization pump installed in the tank supply passage, a tank discharge passage for discharging the liquid in which the gas is dissolved under pressure from the tank to a liquid tank, a microbubble generating nozzle installed in the tank discharge passage and generating micro bubbles by decompressing the liquid in which the gas is dissolved under pressure, and installed separately from the tank discharge passage, the tank; A tank circulation path for sending the liquid from a connected outlet to an inlet connected to the tank, a tank circulation pump installed in the tank circulation path, a gas introducing mechanism installed in the tank circulation path, a single liquid level electrode capable of detecting whether or not the liquid level in the tank is above a predetermined level, and a control device. The gas introduction mechanism includes a depressurization portion through which the liquid is reduced and passed therethrough, a gas inlet through which the gas is introduced by the negative pressure of the liquid in the decompression portion, and a gas introduction valve which opens and closes the gas inlet. The control device drives the pressure pump to pressurize and supply the liquid from the tank supply passage to the tank, and at the same time supply the liquid in which the gas is dissolved under pressure from the tank to the liquid tank through the tank discharge passage. While the micro-bubble generating operation is being executed, the control device drives the tank circulation pump to circulate the liquid in the tank in the tank circulation path, thereby supplying the gas introduced from the gas inlet to the tank, and controlling the opening and closing operation of the gas introduction valve based on information as to whether or not the liquid level in the tank detected by the single liquid level electrode is equal to or higher than a predetermined liquid level.

[0007] According to the above configuration, the control device is configured to control the opening and closing operation of the gas introduction valve based on information about whether or not the liquid level in the tank is equal to or higher than a predetermined liquid level, which is detected by one liquid level electrode. For this reason, it is possible to reduce the amount of information on the liquid level in the tank and to ensure the speed of the judgment process on opening and closing of the gas introduction valve.

[0008] In one or more embodiments, the control device may close the gas introduction valve when the liquid level electrode detects that the liquid level in the tank is lower than the predetermined liquid level while the gas introduction valve is open while the micro-bubble generating operation is being executed, keep the gas introduction valve closed until a first predetermined time period elapses after the gas introduction valve is closed, and open the gas introduction valve after the first predetermined time period has elapsed.

[0009] In the microbubble generating device, liquid droplets scattered from the liquid surface of the tank adhere to the liquid level electrode, which may cause slime to form on the liquid level electrode. If slime is formed on the liquid level electrode, there is a risk of erroneous detection of the liquid level in the tank. For example, when the microbubble generating device includes a lower liquid level electrode and an upper liquid level electrode, and the controller controls the opening and closing operation of the gas introduction valve so that the liquid level in the tank transitions between the lower liquid level and the upper liquid level, the upper liquid level electrode is hardly immersed in the liquid. For this reason, the generation of slime in the upper liquid level electrode cannot be suppressed, and the liquid level in the tank may be erroneously detected. According to the above configuration, by frequently immersing the liquid level electrode in the liquid while the microbubble generating operation is being executed, generation of slime in the liquid level electrode can be suppressed. For this reason, erroneous detection of the liquid level in the tank can be suppressed.

[0010] In one or more embodiments, the control device may specify, as an intake time, an elapsed time from opening the gas introduction valve in the closed state to detecting by the liquid level electrode that the liquid level in the tank is lower than the predetermined liquid level and closing the gas introduction valve while the microbubble generating operation is being executed, as an intake time, and reducing the rotational speed of the pressure pump when the pressure pump is subsequently driven when the intake time exceeds an upper limit intake time.

[0011] When the intake time is too long, it is assumed that the amount of liquid supplied to the tank is too large or the amount of gas introduced by the gas introducing mechanism is too small. In addition, as the rotational speed of the pressure pump increases, the amount of liquid supplied to the tank increases, and as the rotational speed of the pressure pump decreases, the amount of liquid supplied to the tank decreases. According to the configuration described above, when the intake time exceeds the upper limit intake time, that is, when the intake time is too long, the amount of liquid supplied to the tank is reduced by reducing the rotational speed of the pressure pump, thereby reducing the intake time.

[0012] In one or more embodiments, the control device may specify, as an intake time, an elapsed time from opening the gas introduction valve in the closed state to closing the gas introduction valve by detecting by the liquid level electrode that the liquid level in the tank is lower than the predetermined liquid level, while the microbubble generating operation is being executed, and when the intake time is less than a lower limit intake time, increase the rotational speed of the pressure pump when the pressure pump is subsequently driven.

[0013] When the intake time is too short, it is assumed that the amount of liquid supplied to the tank is too small, or the amount of gas introduced by the gas introduction mechanism is too large. According to the configuration described above, when the intake time is less than the lower limit intake time, that is, when the intake time is too short, the rotational speed of the pressure pump is increased to increase the amount of liquid supplied to the tank, thereby extending the intake time.

[0014] In one or more embodiments, the control device specifies, as an intake time, an elapsed time from opening the gas introduction valve in the closed state to closing the gas introduction valve by detecting with the liquid level electrode that the liquid level of the tank is lower than the predetermined liquid level, while the micro-bubble generating operation is being executed, and when the intake time exceeds an upper limit intake time, the tank circulation pump when the tank circulation pump is subsequently driven with the gas introduction valve open You may increase the number of revolutions.

[0015] When the intake time is too long, it is assumed that the amount of liquid supplied to the tank is too large or the amount of gas introduced by the gas introducing mechanism is too small. Further, with the gas introduction valve open, the amount of gas introduced by the gas introduction mechanism increases as the rotational speed of the tank circulation pump increases, and the amount of gas introduced by the gas introduction mechanism decreases as rotational speed of the tank circulation pump decreases. According to the configuration described above, when the intake time exceeds the upper limit intake time, that is, when the intake time is too long, the amount of gas introduced by the gas introduction mechanism can be increased by increasing the rotational speed of the tank circulation pump, thereby reducing the intake time.

[0016] In one or more embodiments, the control device specifies, as an intake time, an elapsed time from opening the gas introduction valve in the closed state to closing the gas introduction valve by detecting with the liquid level electrode that the liquid level in the tank is lower than the predetermined liquid level during the micro-bubble generating operation is being executed, and when the intake time is less than a lower limit intake time, the tank circulation pump when driving the tank circulation pump with the gas introduction valve open thereafter The number of revolutions may be reduced.

[0017] When the intake time is too short, it is assumed that the amount of liquid supplied to the tank is too small, or the amount of gas introduced by the gas introduction mechanism is too large. According to the configuration described above, when the intake time is less than the lower limit intake time, i.e., when the intake time is too short, the amount of gas introduced by the gas introduction mechanism can be reduced by reducing the rotational speed of the tank circulation pump, thereby extending the intake time.

[0018] In one or more embodiments, the control device may determine whether or not a stop condition for stopping the micro-bubble generating operation is satisfied while the micro-bubble generating operation is being executed, and if the stop condition is satisfied, a stop process for stopping the micro-bubble generating operation may be executed. When the stop processing is executed, the control device opens the gas introduction valve while the pressurization pump and the tank circulation pump are driven, closes the gas introduction valve when the liquid level electrode detects that the liquid level in the tank is lower than the predetermined liquid level while the gas introduction valve is open, keeps the gas introduction valve closed after the gas introduction valve is closed, until a second predetermined time period longer than the first predetermined time period elapses, and after the second predetermined time period has elapsed Alternatively, the microbubble generation operation may be stopped by stopping the pressure pump and the tank circulation pump.

[0019] According to the configuration described above, the microbubble generating operation can be stopped in a state where the liquid level electrode is immersed in the liquid. Accordingly, it is possible to suppress generation of slime in the liquid level electrode and suppress erroneous detection of the liquid level in the tank. Further, according to the above configuration, when the microbubble generation operation is stopped, the liquid level electrode is immersed in the liquid up to a portion above the portion immersed in the liquid during normal operation. Therefore, the generation of slime in the liquid-level electrode can be suppressed more appropriately.

[0020] In one or more embodiments, the control device may open the gas introduction valve, keep the gas introduction valve open until a third predetermined time period elapses after the gas introduction valve is opened, and close the gas introduction valve after the third predetermined time period has elapsed, when the liquid level electrode detects that the liquid level in the tank is equal to or higher than the predetermined liquid level while the gas introduction valve is closed while the microbubble generating operation is being executed.

[0021] For example, when the microbubble generating device includes a lower liquid level electrode and an upper liquid level electrode, and the controller controls the opening and closing operation of the gas introduction valve so that the liquid level in the tank transitions between the lower liquid level and the upper liquid level, the length of the lower liquid level electrode needs to be relatively long. In this case, there is a possibility of leading to weight increase of the entire device. According to the above configuration, the length of the liquid level electrode can be relatively shortened. For this reason, the weight reduction of the whole apparatus can be aimed at.

[0022] In one or more embodiments, the liquid may be water. The liquid tank may be a bathtub used by the user for bathing.

[0023] According to the configuration described above, in the microbubble generating device that generates microbubbles in the water of a bathtub used for bathing by a user, the amount of information about the water level in the tank is reduced, and the speed of judgment processing on opening and closing of the gas introduction valve can be ensured.

[0024] FIG. 1 is a diagram schematically showing the configuration of a hot water device 2 of Examples 1 to 3. As shown in FIG.
2 is a diagram schematically showing an example of the flow of water in the bathtub adapter 132 of the hot water device 2 of Examples 1 to 3. As shown in FIG.
3 is a diagram schematically showing another example of the flow of water in the bathtub adapter 132 of the hot water device 2 of Examples 1 to 3. As shown in FIG.
4 is a diagram schematically showing an example of the flow of water in the hot water device 2 of Examples 1 to 3. As shown in FIG.
5 is a diagram schematically showing another example of the flow of water in the hot water device 2 of Examples 1 to 3. As shown in FIG.
6 is a diagram schematically showing another example of the flow of water in the hot water device 2 of Examples 1 to 3. As shown in FIG.
Fig. 7 is a flow chart of processing executed by the control device 150 in the micro-bubble generating operation of the hot water device 2 according to the first embodiment.
FIG. 8 is a flow chart of a stop process executed by the controller 150 among the process shown in FIG. 7, the process shown in FIG. 9, or the process shown in FIG.
Fig. 9 is a flow chart of processes executed by the control device 150 in the fine-bubble generating operation of the hot water device 2 according to the second embodiment.
Fig. 10 is a flow chart of processes executed by the control device 150 in the fine-bubble generating operation of the hot water apparatus 2 according to the third embodiment.

[0025] (Example 1)

As shown in FIG. 1 , the hot water system 2 of the present embodiment includes a heat source unit 10, an air pressure melting unit 50, a bathtub adapter 132, and a control device 150. The hot water device 2 can heat water supplied from a water supply source 200 such as tap water and supply the heated water to a desired temperature to a faucet 250 installed in a kitchen or the like or a bathtub 130 installed in a bathroom. In addition, the hot water device 2 may generate fine bubbles in the water of the bathtub 130 used for bathing by the user.

[0026] (Configuration of heat source unit 10)

The heat source unit 10 includes a first heat source device 12, a second heat source device 14, a water supply path 16, a hot water path 18, a bypass path 20, a bypass servo 22, a hot water path 24, a hot water supply valve 26 for a bathtub, a water quantity sensor 28, and a circulation path ( 30), a circulation return path 32, a bathtub circulation pump 34, and a water flow switch 36.

[0027] The upstream end of the water supply passage 16 is connected to the water supply source 200, and the downstream end of the water supply passage 16 is connected to the first heat source device 12. In addition, the upstream end of the hot water path 18 is connected to the first heat source device 12, and the downstream end of the hot water path 18 is connected to the faucet 250. The first heat source device 12 is a combustion heat source device that heats water by burning gas, for example. The first heat source device 12 heats the water flowing from the water supply path 16 and sends the heated water to the tap path 18 .

[0028] 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 passage 18. The bypass servo 22 is installed in a portion where the bypass path 20 is connected to the water supply path 16 . The bypass servo 22 can adjust the ratio of the flow rate of water flowing from the water supply passage 16 to the tap passage 18 via the first heat source device 12 and the flow rate of water flowing from the water supply passage 16 to the tap 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 high-temperature water flowing from the first heat source device 12 and the low-temperature water flowing from the bypass furnace 20 are mixed in a desired ratio to the hot water furnace 18 on the downstream side of the portion to which the bypass furnace 20 is connected, and water temperature-controlled to a desired temperature is supplied. A hot water temperature thermistor 18a for detecting the temperature of water in the hot water path 18 is provided in the hot water path 18 on the downstream side of the portion to which the bypass path 20 is connected.

[0029] The upstream end of the pouring furnace 24 is connected to the hot water furnace 18 on the downstream side of the portion to which the bypass furnace 20 is connected, and the downstream end of the pouring furnace 24 is connected to the circulation return path 32. The hot water supply valve 26 for the bathtub is installed in the pouring furnace 24 and opens and closes the pouring furnace 24 . The hot water supply valve 26 for the bathtub is normally closed. The water quantity sensor 28 is installed in the pouring furnace 24 and detects the quantity of water flowing through the pouring furnace 24 .

[0030] The upstream end of the circulation return path 32 is connected to the heat source return path 60 (details will be described later) of the air pressure melting unit 50, and the downstream end of the circulation return path 32 is connected to the second heat source machine 14. Further, the upstream end of the circulation path 30 is connected to the second heat source device 14, and the downstream end of the circulation path 30 is connected to the heat source path 68 of the air pressure melting unit 50 (details will be described later). The second heat source device 14 is a combustion heat source device that heats water by burning gas, for example. The second heat source device 14 heats the water flowing from the circulation return passage 32 and sends the heated water to the circulation advance passage 30 . Near the upstream end of the return circuit 32, a thermistor 32a for detecting the temperature of water in the return circuit 32 is provided. Near the downstream end of the circulation passage 30, a circulation passage thermistor 30a for detecting the temperature of water in the circulation passage 30 is provided.

[0031] The bathtub circulation pump 34 is installed in the circulation return passage 32 on the downstream side of the connecting portion of the pouring furnace 24, and sends water in the circulation return passage 32 toward the second heat source device 14. The water flow switch 36 is installed between the bathtub circulation pump 34 and the second heat source device 14 in the return circulation path 32, and detects whether or not water is flowing in the return circulation path 32.

[0032] (Configuration of air pressure melting unit 50)

The air pressure melting unit 50 includes a tank 52, a heat source return passage 60, a heat source passage passage 68, a tank return passage 74, a tank passage passage 64, a communication passage 66, a first three-way valve 80, a second three-way valve 82, a check valve 84, a tank water supply valve 86, a first pressure pump 88, and a second pressure pump. 90, a tank circulation path 92, a tank circulation pump 94, and a gas introduction mechanism 96 are provided.

[0033] The tank 52 is used to generate air dissolved water by pressurizing and dissolving air into water. The tank 52 can store water therein. Inside the tank 52, a water level electrode 54 for detecting the water level in the tank 52 and a ground electrode (not shown) are provided. When the water level electrode 54 contacts the surface of the water stored in the tank 52, current flows between the water level electrode 54 and the ground electrode, and an ON signal is output to the controller 150. That is, the water level electrode 54 is configured to be able to detect whether or not the water level in the tank 52 is equal to or higher than a predetermined water level. Hereinafter, the water level in the tank 52 detected by the water level electrode 54 may be referred to as "boundary water level".

[0034] One end of the heat source return passage 60 is connected to the communication passage 66, and the other end of the heat source return passage 60 is connected to the circulation return passage 32 of the heat source unit 10. The communication path 66 connects the first three-way valve 80 and the second three-way valve 82 . To the first three-way valve 80, a communication passage 66, a first bathtub water passage 62, and a tank travel passage 64 are connected. The first three-way valve 80 has a first communication state in which the tank passage 64 and the first bathtub passage 62 communicate (see FIG. 6 ), a second communication state in which the tank passage 64 communicates with the communication passage 66 (see FIG. 1 ), and a third communication state in which the first bathtub passage 62, the tank passage 64, and the communication passage 66 communicate (see FIG. 4 and FIG. 4 ). 5) can be switched. The upstream end of the tank travel path 64 is connected to the lower portion of the tank 52, and the downstream end of the tank travel path 64 is connected to the first three-way valve 80. A check valve 84 that allows water to flow from the tank 52 toward the first three-way valve 80 and prohibits water from flowing from the first three-way valve 80 toward the tank 52 is provided in the tank travel path 64. One end of the first bathtub water line 62 is connected to the first three-way valve 80, and the other end of the first bathtub water line 62 is connected to the bathtub adapter 132.

[0035] One end of the heat source passage 68 is connected to the circulation passage 30 of the heat source unit 10, and the other end of the heat source passage 68 is connected to the second three-way valve 82. The communication path 66, the heat source travel path 68, and the second bathtub water path 70 are connected to the second three-way valve 82. The second three-way valve 82 can switch between a fourth communication state in which the second bathtub water passage 70 communicates with the communication passage 66 (see FIG. 6) and a fifth communication state in which the heat source travel passage 68 communicates with the second bathtub passage 70 (see FIGS. 1, 4, and 5). One end of the second bathtub water line 70 is connected to the second three-way valve 82, and the other end of the second bathtub water line 70 is connected to the bathtub adapter 132.

[0036] The upstream end of the tank return path 74 is connected to the heat source travel path 68, and the downstream end of the tank return path 74 is connected to the tank 52 via the water supply port 74a. The tank water supply valve 86 is installed in the tank return passage 74 and opens and closes the tank return passage 74 . The tank water supply valve 86 is normally closed. The first pressure pump 88 and the second pressure pump 90 are installed between the tank water supply valve 86 and the tank 52 in the tank return path 74 . The first pressure pump 88 and the second pressure pump 90 pressurize the water in the tank return passage 74 and send it toward the tank 52 . In the tank return passage 74, the first pressure pump 88 is disposed upstream of the second pressure pump 90.

[0037] The upstream end of the tank circulation passage 92 (hereinafter also referred to as an outlet 92a) is connected to the bottom of the tank 52, and the downstream end of the tank circulation passage 92 is connected to the tank return passage 74 on the downstream side of the second pressure pump 90. The water level of the portion where the outlet 92a of the tank circulation passage 92 is connected to the tank 52 is lower than the boundary water level. A tank circulation pump 94 is installed in the tank circulation path 92 . The tank circulation pump 94 sucks water in the tank 52 into the tank circulation path 92 through the outlet 92a, and at the same time discharges the water in the tank circulation path 92 into the tank 52 through the water supply port 74a at the downstream end of the tank return path 74.

[0038] The gas introduction mechanism 96 is installed in the tank circulation path 92 on the upstream side of the tank circulation pump 94. The gas introduction mechanism 96 includes an inlet pipe 98, a water outlet pipe 100, a Venturi pipe 102, a gas introduction passage 104, and a gas introduction valve 106. Water flows into the inlet pipe 98 from the upstream side of the tank circulation path 92 . The water outlet pipe 100 discharges water to the downstream side of the tank circulation path 92 . The venturi pipe 102 connects the inlet pipe 98 and the outlet pipe 100. The diameter of the venturi pipe 102 is smaller than the diameters of the inlet pipe 98 and the outlet pipe 100. Water flowing through the gas introduction mechanism 96 is reduced to a pressure lower than atmospheric pressure when flowing from the inlet pipe 98 to the venturi pipe 102, and is increased to the original pressure when flowing from the venturi pipe 102 to the water outlet pipe 100. The upstream end of the gas introduction passage 104 (hereinafter also referred to as the gas introduction port 104a) is open to the atmosphere, and the downstream end is connected to the Venturi tube 102. The gas introduction valve 106 is installed in the gas introduction passage 104 and opens and closes the gas introduction passage 104 . When water flows through the gas introduction mechanism 96, when 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. Air introduced through the gas introduction path 104 flows into the tank 52 together with water flowing through the tank circulation path 92 . The gas introduction valve 106 is normally closed.

[0039] (Configuration of bathtub adapter 132)

Subsequently, with reference to FIGS. 2 and 3 , the bathtub adapter 132 installed on the wall portion 130a of the bathtub 130 will be described. 2 shows the flow of water in the bathtub adapter 132 in a state where water flows from the first bathtub water line 62 toward the bathtub 130 and water flows from the bathtub 130 toward the second bathtub water path 70 (e.g., the state of FIG. 6). 3 shows the flow of water in the bathtub adapter 132 in a state where water flows from the bathtub 130 toward the first bathtub waterway 62 and water flows from the second bathtub waterway 70 toward the bathtub 130 (e.g., the state of FIG. 5).

[0040] The bathtub adapter 132 includes a first water channel 136 and a second water channel 138. The first water passage 136 communicates with the first bathtub water passage 62, and the second water passage 138 communicates with the second bathtub water passage 70. The first water passage 136 is branched into a first discharge passage 136a and a first suction passage 136b. The first discharge path 136a communicates with the first discharge port 134a formed on the front surface 132a of the bathtub adapter 132 . Water discharged from the first discharge port 134a into the bathtub 130 is discharged forward of the wall part 130a of the bathtub 130, that is, in a direction perpendicular to the wall part 130a of the bathtub 130. In the first discharge passage 136a, a backflow preventer 140a for preventing the flow of water from the bathtub 130 toward the first bathtub waterway 62, and a micro-bubble generating nozzle 142 disposed upstream of the backflow preventer 140a (on the side of the first bathtub waterway 62) are provided. The micro-bubble generating nozzle 142 depressurizes the water passing through the micro-bubble generating nozzle 142 . The first intake passage 136b communicates with the first intake port 134b formed on the front surface 132a of the bathtub adapter 132 . A backflow preventer 140b for preventing the flow of water from the first bathtub waterway 62 toward the bathtub 130 is provided in the first suction passage 136b.

[0041] The second water passage 138 is branched into a second discharge passage 138a and a second suction passage 138b. The second intake passage 138b communicates with the second intake port 134c formed on the front surface 132a of the bathtub adapter 132. A backflow preventer 140c for preventing the flow of water from the second bathtub waterway 70 toward the bathtub 130 is provided in the second suction passage 138b. The second discharge path 138a communicates with the second discharge port 134d formed 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 . In the second discharge passage 138a, a backflow preventer 140d for preventing the flow of water from the bathtub 130 toward the second bathtub water passage 70 is provided.

[0042] (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 pressure melting unit 50 . The control device 150 is configured to be communicable with a remote control 154 that can be operated by a user. The control device 150 has a memory 152, and can store various settings input by the user, such as a set temperature or a set water quantity in the bathtub hot water supply operation, and a set temperature in the reheating (reheating) operation. Through the remote controller 154, the user may instruct the start or end of a hot water supply operation for a bathtub, a reheating operation, or a micro-bubble generating operation, which will be described later.

[0043] (hot water supply operation for bathtub)

The hot water supply operation for the bathtub starts when the user instructs the start of the hot water supply operation for the bathtub through the remote controller 154 . Alternatively, the hot water supply operation for the bathtub may be started when the user sets the start time of the hot water supply operation for the bathtub through the remote controller 154 and the controller 150 determines that the start time for the hot water supply operation for the bathtub has arrived. When the hot water supply operation for the bathtub is started, the controller 150 puts the first three-way valve 80 and the second three-way valve 82 into the third communication state and the fifth communication state, respectively (see FIGS. 4 and 5 ). When the hot water supply operation for the bathtub is started, the control device 150 opens the hot water supply valve 26 for the bathtub and starts heating by the first heat source device 12 . As a result, as shown in FIG. 4 , water temperature-controlled to a set temperature flows from the tap furnace 18 through the pour furnace 24 to the circulation return path 32 . The water flowing into the circulation return path 32 is branched into a flow toward the upstream side (ie, the heat source return path 60) and a flow toward the downstream side (ie, the second heat source device 14). Water flowing from the circulation return passage 32 to the heat source return passage 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. Water flowing from the circulation return path 32 to the second heat source unit 14 flows into the bathtub 130 via the circulation path 30, the heat source path 68, the second three-way valve 82, the second bathtub water line 70, and the bathtub adapter 132. The controller 150 waits until the accumulated water quantity detected by the water quantity sensor 28 reaches the set water quantity in the hot water supply operation for the bathtub. Incidentally, the integrated water quantity here means the integrated water quantity detected by the water quantity sensor 28 after the hot water supply operation for the bathtub was started. When the accumulated amount of water reaches the set amount, the control device 150 closes the hot water supply valve 26 for the bathtub and ends the heating of the water by the first heat source device 12 . After that, the control device 150 notifies the user through the remote controller 154 that the hot water supply operation for the bathtub has been completed, and ends the hot water supply operation for the bathtub.

[0044] (reheat operation)

The reheating operation starts when the user instructs the start of the reheating operation through the remote controller 154 . Alternatively, the reheating operation may be started when the control device 150 judges that the temperature detected by the thermistor 32a does not meet the set temperature by returning the circulation after the heating of the water by the first heat source device 12 is finished in the hot water supply operation for the bathtub. When starting the reheating operation, the control device 150 puts the first three-way valve 80 into a third communication state and also puts the second three-way valve 82 into a fifth communication state (see FIGS. 4 and 5 ). From this state, the controller 150 starts heating the water by the second heat source device 14 while driving the bathtub circulation pump 34 . Accordingly, as shown in FIG. 5 , water in the bathtub 130 is sent to the second heat source device 14 via the bathtub adapter 132, the first bathtub water line 62, the first three-way valve 80, the communication path 66, the heat source return path 60, and the circulation return path 32. The water heated by the second heat source device 14 is returned to the bathtub 130 via the circulation path 30, the heat source path 68, the second three-way valve 82, the second bathtub water line 70, and the bathtub adapter 132. When the temperature detected by the thermistor 32a at the return of circulation becomes equal to or higher than the set temperature, the controller 150 stops the bathtub circulation pump 34 and ends the water heating by the second heat source device 14. After that, the control device 150 notifies the user through the remote controller 154 that the reheating operation has been completed, and ends the reheating operation.

[0045] (Microbubble generation operation)

The micro-bubble generating operation starts when the user instructs the start of the micro-bubble generating operation through the remote controller 154. Further, in the hot water apparatus 2 of the present embodiment, after the hot water supplying operation for the bathtub described above is completed, the microbubble generation operation is also started automatically. That is, the micro-bubble generation operation is executed in conjunction with the execution of the hot water supply operation for the bathtub. When starting the micro-bubble generation 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 FIGS. 4 and 5 ). In addition, the control device 150 sets the tank water supply valve 86 to an open state. From this state, the control device 150 executes the processing shown in FIG. 7 .

[0046] In S2, the control device 150 drives the tank circulation pump 94. Accordingly, water circulates between the tank 52 and the tank circulation path 92 .

[0047] In S4, the control device 150 opens the gas introduction valve 106. In this way, air is introduced into the water flowing through the gas introducing mechanism 96 of the tank circulation path 92 .

[0048] In S6, the control device 150 starts the supply of air dissolved water from the tank 52 to the bathtub 130. Specifically, as shown in FIG. 6 , the controller 150 sets the first three-way valve 80 to the first communication state and the second three-way valve 82 to the fourth communication state, and then drives the bathtub circulation pump 34, the first pressure pump 88, and the second pressure pump 90. Accordingly, 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 passage 60, the circulation return passage 32, the second heat source machine 14, the circulation passage passage 30, the heat source passage passage 68, and the tank return passage 74. At this time, water pressurized by the first pressure pump 88 and the second pressure pump 90 is supplied to the tank 52 from the tank return path 74 . In this way, in the inside of the tank 52, the air is pressurized and dissolved in the water. Then, the water in which the air is pressurized and dissolved is supplied to the bathtub 130 from the tank 52 via the tank passage 64, the first three-way valve 80, the first bathtub water line 62, and the bathtub adapter 132. At this time, when the water in which the air is dissolved under pressure passes through the microbubble generating nozzle 142 of the first discharge passage 136a of the bathtub adapter 132, the pressure is reduced to less than atmospheric pressure, and when ejected into the bathtub 130, the pressure is increased to atmospheric pressure, and microbubbles are generated in the water in the bathtub 130.

[0049] In S8, the control device 150 determines whether or not the water level in the tank 52 is below the boundary water level based on the presence or absence of an ON signal output from the water level electrode 54. In the present embodiment, in the gas introduction mechanism 96, the amount of air introduced when the gas introduction valve 106 is opened is greater than the amount of air in the microbubbles generated in the water in the bathtub 130. For this reason, in the state where the gas introduction valve 106 is opened, the amount of air in the tank 52 increases and the water level in the tank 52 goes down. When the water level in the tank 52 is equal to or higher than the boundary water level (NO), the process repeats S8. If the water level in the tank 52 is below the boundary water level (YES), the process proceeds to S10.

[0050] In S10, the control device 150 closes the gas introduction valve 106. Accordingly, the introduction of air to the water flowing through the gas introducing mechanism 96 of the tank circulation passage 92 is stopped. In the state where the gas introduction valve 106 is closed, since air is not supplied to the tank 52, the amount of air in the tank 52 decreases and the water level in the tank 52 rises. Also, in this embodiment, even while the gas introduction valve 106 is closed, the driving of the tank circulation pump 94 continues as it is. In this way, the flow of water in the tank 52 is promoted, and dissolution by pressure of the air into the water in the tank 52 is promoted.

[0051] In S12, the control device 150 starts measuring the water level rise time using a built-in timer (not shown).

[0052] In S14, the control device 150 determines whether or not the water level rise time at which the measurement was started in S12 exceeds the first predetermined time period (for example, 90 seconds). When the water level rising time is equal to or shorter than the first predetermined time (NO), the process repeats S14. If the water level rising time exceeds the first predetermined time (YES), the process proceeds to S16.

[0053] In S16, the control device 150 ends the measurement of the water level rise time by the built-in timer (not shown).

[0054] In S18, the control device 150 opens the gas introduction valve 106. Accordingly, introduction of air to the water flowing through the gas introducing mechanism 96 of the tank circulation path 92 is resumed.

[0055] In S20, the control device 150 starts measuring the intake time using a built-in timer (not shown).

[0056] In S22, the control device 150 determines whether or not the water level in the tank 52 is below the boundary water level based on the presence or absence of an ON signal output from the water level electrode 54. When the water level in the tank 52 is equal to or higher than the boundary water level (NO), the process repeats S22. If the water level in the tank 52 is below the boundary water level (YES), the process proceeds to S24.

[0057] In S24, the control device 150 closes the gas introduction valve 106. Accordingly, the introduction of air to the water flowing through the gas introducing mechanism 96 of the tank circulation passage 92 is stopped.

[0058] In S26, the control device 150 ends the measurement of the intake time by the built-in timer (not shown). In addition, the control device 150 stores the intake time in the memory 152 when the measurement is finished.

[0059] In S28, the control device 150 determines whether or not the intake time stored in the memory 152 in S26 exceeds a predetermined upper limit intake time (for example, 120 seconds). If the intake time exceeds the upper limit intake time (if YES), the process proceeds to S30. If the intake time is equal to or less than the upper limit intake time (NO), the process proceeds to S32.

[0060] In S30, the control device 150 reduces the rotation speed of the first pressure pump 88 and the second pressure pump 90 by a predetermined value (for example, 10 Hz). Accordingly, when the first pressure pump 88 and the second pressure pump 90 are driven later, the amount of water supplied to the tank 52 is reduced. After S30, processing proceeds to S32.

[0061] In S32, the control device 150 determines whether or not the intake time stored in the memory 152 in S26 is less than a predetermined lower limit intake time (for example, 60 seconds). If the intake time is less than the lower limit intake time (YES), the process proceeds to S34. If the intake time is equal to or greater than the lower limit intake time (NO), the process proceeds to S36.

[0062] In S34, the control device 150 increases the rotation speed of the first pressure pump 88 and the second pressure pump 90 by a predetermined value (for example, 10 Hz). Accordingly, when the first pressure pump 88 and the second pressure pump 90 are driven later, the amount of water supplied to the tank 52 increases. After S34, processing proceeds to S36.

[0063] In S36, the control device 150 determines whether a stop condition for stopping the micro-bubble generating operation is satisfied. In this embodiment, the stop condition is that the operating time of the micro-bubble generation operation has reached the set time. The operating time of the micro-bubble generating operation is the elapsed time from the start of the micro-bubble generating operation. In the hot water apparatus 2 of the present embodiment, when the micro-bubble generation operation is executed alone without interlocking with the execution of the hot water supply operation for the bathtub, the set time is set to, for example, 10 minutes. Contrary to this, in the case where the micro-bubble generation operation is executed in conjunction with the hot water supply operation for the bathtub, the set time is set to, for example, 30 minutes. If the stop condition is not satisfied (NO), the process returns to S12. If the stop condition is satisfied (if YES), the processing proceeds to S38.

[0064] In S38, the control device 150 executes a stop process for stopping the micro-bubble generating operation (see FIG. 8). After S38, the process of Fig. 7 ends.

[0065] In the above, it has been described that the control device 150 determines whether or not the stop condition is satisfied in the process of S36. However, the control device 150 can determine whether or not the stop condition is satisfied even while the processing of S2 to S34 is being executed. And, even if the process of S2-S34 is being executed, if it is judged that the stop condition is satisfied, control device 150 is configured to stop the process in execution and execute the process of S38 (ie, stop process).

[0066] (stop processing)

As shown in FIG. 8 , in S52 , when the gas introduction valve 106 is closed, the control device 150 opens the gas introduction valve 106 . Accordingly, introduction of air to the water flowing through the gas introducing mechanism 96 of the tank circulation path 92 is resumed.

[0067] In S54, the control device 150 determines whether or not the water level in the tank 52 is below the boundary water level based on the presence or absence of an ON signal output from the water level electrode 54. When the water level in the tank 52 is equal to or higher than the boundary water level (NO), the process repeats S54. If the water level in the tank 52 is below the boundary water level (YES), the process proceeds to S56.

[0068] In S56, the control device 150 closes the gas introduction valve 106. Accordingly, the introduction of air to the water flowing through the gas introducing mechanism 96 of the tank circulation passage 92 is stopped.

[0069] In S58, the control device 150 starts measuring the water level rise time using a built-in timer (not shown).

[0070] In S60, the control device 150 determines whether or not the water level rise time at which the measurement was started in S58 exceeds a second predetermined time (eg, 180 seconds) longer than the first predetermined time. When the water level rise time is equal to or less than the second predetermined time (NO), the process repeats S60. If the water level rising time exceeds the second predetermined time (YES), the process proceeds to S62.

[0071] In S62, the control device 150 ends the measurement of the water level rising time by the built-in timer (not shown).

[0072] In S64, the control device 150 stops the bathtub circulation pump 34, the first pressure pump 88, and the second pressure pump 90 to end the supply of air dissolved water from the tank 52 to the bathtub 130.

[0073] In S66, the control device 150 stops the tank circulation pump 94. Accordingly, the circulation of water between the tank 52 and the tank circulation path 92 is terminated. After S66, the processing in Fig. 8 ends.

[0074] In this way, in the stop process, the control device 150 can stop the micro-bubble generation operation in a state where the water level electrode 54 is immersed in water. At this time, since the water level in the tank 52 at the time of completion of the processing in FIG. 8 is higher than the water level in the tank 52 at the time of opening the gas introduction valve 106 in S18 of FIG. Thereby, generation of slime in the water level electrode 54 can be appropriately suppressed.

[0075] (Example 2)

The hot water device 2 of this embodiment has substantially the same configuration as that of the hot water device 2 of the first embodiment. In the hot water apparatus 2 of the present embodiment, when executing the fine-bubble generating operation, the control device 150 executes the process shown in FIG. 9 instead of executing the process shown in FIG. 7 . The processing shown in FIG. 9 is different from the processing shown in FIG. 7 below.

[0076] In the process shown in Fig. 9, if the intake time stored in the memory 152 exceeds the upper limit intake time in S26 (YES in S28), the process proceeds to S70. In S70, the controller 150 increases the rotational speed of the tank circulation pump 94 by a predetermined value (for example, 10 Hz). Accordingly, when the tank circulation 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 S70, processing proceeds to S32.

[0077] On the other hand, if the intake time stored in the memory 152 is lower than the lower limit intake time in S26 (YES in S32), the process proceeds to S72. In S72, the controller 150 reduces the rotational speed of the tank circulation pump 94 by a predetermined value (for example, 10 Hz). Accordingly, when the tank circulation pump 94 is subsequently driven with the gas introduction valve 106 open, the amount of air introduced by the gas introduction mechanism 96 is reduced. After S72, processing proceeds to S36.

[0078] Further, in S70 of the process shown in FIG. 9 , the controller 150 increases the rotational speed of the tank circulation pump 94 when the tank circulation pump 94 is driven with the gas introduction valve 106 open, but may be structured not to increase the rotational 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 S72 of the process shown in FIG. 9 , the controller 150 reduces the rotational speed of the tank circulation pump 94 when the tank circulation pump 94 is driven with the gas introduction valve 106 open, but may not reduce the rotational speed of the tank circulation pump 94 when the tank circulation pump 94 is subsequently driven with the gas introduction valve 106 closed.

[0079] (Example 3)

The hot water device 2 of this embodiment has substantially the same configuration as that of the hot water device 2 of the first embodiment. In the hot water apparatus 2 of the present embodiment, when executing the fine-bubble generating operation, the control device 150 executes the process shown in FIG. 10 instead of executing the process shown in FIG. 7 .

[0080] In S82, the control device 150 drives the tank circulation pump 94. Accordingly, water circulates between the tank 52 and the tank circulation path 92 .

[0081] In S84, the control device 150 starts the supply of air dissolved water from the tank 52 to the bathtub 130. At this time, the control device 150 performs processing similar to S8 in FIG. 7 .

[0082] In S86, the control device 150 determines whether or not the water level in the tank 52 is equal to or higher than the boundary water level based on the presence or absence of an ON signal output from the water level electrode 54. If the water level in the tank 52 is below the boundary water level (NO), the process repeats S86. If the water level in the tank 52 is equal to or higher than the boundary water level (YES), the process proceeds to S88.

[0083] In S88, the control device 150 opens the gas introduction valve 106. In this way, introduction of air into the water flowing through the gas introducing mechanism 96 of the tank circulation path 92 is started.

[0084] In S90, the control device 150 starts measuring the water level lowering time using a built-in timer (not shown).

[0085] In S92, the control device 150 determines whether or not the water level lowering time at which the measurement was started in S90 exceeds a third predetermined time period (for example, 90 seconds). When the water level lowering time is equal to or less than the third predetermined time (NO), the process repeats S92. If the water level lowering time exceeds the third predetermined time (YES), the process proceeds to S94.

[0086] In S94, the control device 150 ends the measurement of the water level lowering time by the built-in timer (not shown).

[0087] In S96, the control device 150 closes the gas introduction valve 106. Accordingly, the introduction of air to the water flowing through the gas introducing mechanism 96 of the tank circulation passage 92 is stopped.

[0088] In S98, the control device 150 starts measuring the exhaust time using a built-in timer (not shown).

[0089] In S100, the control device 150 determines whether or not the water level in the tank 52 is equal to or higher than the boundary water level based on the presence or absence of an ON signal output from the water level electrode 54. When the water level in the tank 52 is below the boundary water level (NO), the process repeats S100. If the water level in the tank 52 is equal to or higher than the boundary water level (YES), the process proceeds to S102.

[0090] In S102, the control device 150 opens the gas introduction valve 106. Accordingly, introduction of air to the water flowing through the gas introducing mechanism 96 of the tank circulation path 92 is resumed.

[0091] In S104, the control device 150 ends the measurement of the exhaust time by the built-in timer (not shown). In addition, the control device 150 stores in the memory 152 the exhaust time at the end of the measurement.

[0092] In S106, the control device 150 determines whether or not the exhaust time stored in the memory 152 in S104 exceeds a predetermined upper limit exhaust time (for example, 120 seconds). If the exhaust time exceeds the upper limit exhaust time (if YES), the process proceeds to S108. If the exhaust time is equal to or less than the upper limit exhaust time (NO), the process proceeds to S110.

[0093] In S108, the control device 150 increases the rotation speed of the first pressure pump 88 and the second pressure pump 90 by a predetermined value (for example, 10 Hz). Accordingly, when the first pressure pump 88 and the second pressure pump 90 are driven later, the amount of water supplied to the tank 52 increases. After S108, processing proceeds to S110.

[0094] In S110, the control device 150 determines whether or not the exhaust time stored in the memory 152 in S104 is less than a predetermined lower limit exhaust time (for example, 60 seconds). If the exhaust time is less than the lower limit exhaust time (if YES), the process proceeds to S112. If the exhaust time is equal to or greater than the lower limit exhaust time (NO), the process proceeds to S114.

[0095] In S112, the control device 150 reduces the rotation speed of the first pressure pump 88 and the second pressure pump 90 by a predetermined value (for example, 10 Hz). Accordingly, when the first pressure pump 88 and the second pressure pump 90 are driven later, the amount of water supplied to the tank 52 is reduced. After S112, the process proceeds to S114.

[0096] In S114, the control device 150 determines whether a stop condition for stopping the micro-bubble generating operation is satisfied. If the stop condition is not satisfied (NO), the process returns to S90. If the stop condition is satisfied (if YES), the processing proceeds to S116.

[0097] In S116, the control device 150 executes a stop process for stopping the micro-bubble generating operation (see FIG. 8). After S116, the process of Fig. 10 ends.

[0098] In the above, it has been described that the control device 150 determines whether or not the stop condition is satisfied in the process of S114. However, the control device 150 can determine whether or not the stop condition is satisfied even while executing the processing from S82 to S112. Then, even if the process of S82 to S112 is being executed, if it is determined that the stop condition is met, the control device 150 is configured to stop the process in execution and execute the process of S116 (ie, stop process).

[0099] In S108 of the process shown in FIG. 10 , the controller 150 may be configured to decrease the rotation speed of the tank circulation pump 94 by a predetermined value (e.g., 10 Hz) instead of increasing the rotation speed of the first pressure pump 88 and the second pressure pump 90 by a predetermined value. Accordingly, when the tank circulation pump 94 is subsequently driven with the gas introduction valve 106 open, the amount of air introduced by the gas introduction mechanism 96 is reduced. Similarly, in S112 of the process shown in FIG. 10 , the controller 150 may be configured to increase the rotation speed of the tank circulation pump 94 by a predetermined value (e.g., 10 Hz) instead of reducing the rotation speed of the first pressure pump 88 and the second pressure pump 90 by a predetermined value. Accordingly, when the tank circulation pump 94 is subsequently driven with the gas introduction valve 106 open, the amount of air introduced by the gas introduction mechanism 96 increases.

[0100] (modified example)

In the above hot water system 2, air is introduced into the tank 52, but instead of air, gases such as carbon dioxide, hydrogen, and oxygen may be introduced into the tank 52. In this case, a gas filling tank (not shown) filled with gas may be configured to be connected to the gas introduction port 104a of the gas introduction path 104 .

[0101] In the hot water apparatus 2 described above, a set amount of water is received in the bathtub 130 based on the accumulated amount of water detected by the water quantity sensor 28 in the hot water supply operation for the bathtub. In another embodiment, the hot water system 2 may have a configuration in which, for example, a water level sensor capable of detecting the water level of the bathtub 130 is provided, and water of a set water level is received in the bathtub 130 based on the water level of the bathtub 130 detected by the water level sensor in hot water supply operation for the bathtub.

[0102] In the hot water device 2 described above, the heat source unit 10 is connected to the faucet 250 and the air pressure melting unit 50 is connected to the bathtub 130. In another embodiment, the heat source unit 10 may be connected to another heat utilization part, and the air pressure melting unit 50 may be connected to another liquid tank.

[0103] In the above-mentioned hot water device 2, in the tank circulation path 92, the gas introduction mechanism 96 is disposed upstream of the tank circulation pump 94. In another embodiment, in the tank circulation path 92, the gas introduction mechanism 96 may be disposed downstream of the tank circulation pump 94.

[0104] In the hot water device 2 described above, the downstream end of the tank circulation path 92 is connected to the tank return path 74 on the downstream side of the second pressure pump 90. In another embodiment, the downstream end of the tank circulation path 92 does not have to be connected to the tank return path 74 and may be provided separately from the tank return path 74 for the tank 52 .

[0105] In the hot water device 2 described above, only one water level electrode 54 is provided as the water level electrode for detecting the water level in the tank 52. In another embodiment, a plurality of water level electrodes for detecting the water level in the tank 52 may be provided.

[0106] In the above-described hot water device 2, the user may be able to switch via the remote controller 154 whether or not to execute the micro-bubble generation operation in conjunction with the execution of the hot water supply operation for the bathtub.

[0107] In the above-described hot water device 2, when the intake time exceeds the upper limit intake time (YES in S28 in FIG. 7 or FIG. 9 ), the controller 150 reduces the rotation speed of the first pressure pump 88 and the second pressure pump 90 by a predetermined value (S30 in FIG. 7 ) or increases the rotation speed of the tank circulation pump 94 by a predetermined value (S70 in FIG. 9 ) It consists of In another embodiment, when the intake time exceeds the upper limit intake time, the controller 150 may be configured to reduce the rotation speed of the first pressure pump 88 and the second pressure pump 90 by a predetermined value and increase the rotation speed of the tank circulation pump 94 by a predetermined value. In another embodiment, when the intake time exceeds the upper limit intake time, the controller 150 may be configured to shorten the first predetermined time in S14 of FIG. 7 or FIG. 9 instead of correcting the rotation speeds of the first pressure pump 88, the second pressure pump 90, and the tank circulation pump 94. Accordingly, when the water level in the tank 52 is subsequently detected to be below the boundary water level and the water level in the tank 52 is raised (YES in S8), the time for raising the water level in the tank 52 (time for repeatedly executing S14) is shortened.

[0108] In the above-described hot water system 2, when the intake time is less than the lower limit intake time (YES in S32 in FIG. 7 or FIG. 9 ), the controller 150 increases the rotation speed of the first pressure pump 88 and the second pressure pump 90 by a predetermined value (S34 in FIG. 7 ) or decreases the rotation speed of the tank circulation pump 94 by a predetermined value (S72 in FIG. 9 ). It consists of In another embodiment, when the intake time is less than the lower limit intake time, the control device 150 may be configured to increase the rotation speed of the first pressure pump 88 and the second pressure pump 90 by a predetermined value and decrease the rotation speed of the tank circulation pump 94 by a predetermined value. In another embodiment, when the intake time is less than the lower limit intake time, the controller 150 may be configured to extend the first predetermined time in S14 of FIG. 7 or FIG. 9 instead of correcting the rotation speeds of the first pressure pump 88, the second pressure pump 90, and the tank circulation pump 94. Accordingly, when the water level in the tank 52 is subsequently detected to be below the boundary water level and the water level in the tank 52 is raised (YES in S8), the time for raising the water level in the tank 52 (time for repeatedly executing S14) is extended.

[0109] In the above-described hot water apparatus 2, the stop condition for stopping the micro-bubble generating operation is that the operation time of the micro-bubble generating operation has reached the set time. In another embodiment, the stop condition may not be that the operation time of the micro-bubble generation operation has reached the set time. For example, the stop condition may be that the user via the remote controller 154 is instructed to end the microbubble generating operation.

[0110] The length of the water level electrode 54 in the hot water device 2 may be appropriately changed. That is, the boundary water level in the hot water device 2 may be appropriately changed.

[0111] Each of the first predetermined time, the second predetermined time, the third predetermined time, the upper limit intake time, the lower limit intake time, the correction value of the rotation speed of the first pressure pump 88 and the second pressure pump 90, the correction value of the rotation speed of the tank circulation pump 94, and the set time period for stopping the microbubble operation in the hot water device 2 described above may be appropriately changed.

[0112] (correspondence relationship)

As described above, in one or more embodiments, the hot water device 2 (example of a microbubble generating device) includes a tank 52 for dissolving air (a gas example) in water (a liquid example) under pressure, a tank return passage 74 (example of a tank supply passage) for supplying water to the tank 52, a first pressure pump 88 installed in the tank return passage 74, a second pressure pump 90 (example of a pressure pump), and a tank 52 The tank passage 64 for discharging the water in which air is dissolved under pressure from the bathtub 130 (an example of a liquid tank), the first bathtub water passage 62, the bathtub adapter 132 (an example of a tank discharge passage), the microbubble generating nozzle 142 installed in the bathtub adapter 132 and generating fine bubbles by depressurizing the air dissolved under pressure, the tank passage 64, the first bathtub waterway 62, and the bathtub adapter 132 are A tank circulation path 92 that is separately installed and sends water from an outlet port 92a connected to the tank 52 to a water supply port 74a connected to the tank 52 (example of an inlet), a tank circulation pump 94 installed on the tank circulation path 92, a gas introducing mechanism 96 installed on the tank circulation path 92, and whether or not the water level in the tank 52 is above the boundary water level (a predetermined liquid level example) or not can be detected A water level electrode 54 (an example of a liquid level electrode) and a control device 150 are provided. The gas introduction mechanism 96 includes a Venturi tube 102 (an example of a pressure reducing unit) through which water is reduced and passed therethrough, a gas introduction port 104a through which air is introduced by the negative pressure of water in the Venturi tube 102, and a gas introduction valve 106 which opens and closes the gas introduction port 104a. The control device 150 drives the first pressurization pump 88 and the second pressurization pump 90 to pressurize and supply water from the tank return path 74 to the tank 52, and at the same time supply water in which air is pressurized and dissolved from the tank 52 to the bathtub 130 via the tank forward path 64, the first bathtub waterway 62, and the bathtub adapter 132. The control device 150 drives the tank circulation pump 94 to circulate water in the tank 52 through the tank circulation path 92, thereby supplying air introduced from the gas inlet 104a to the tank 52, and controlling the opening and closing operation of the gas introduction valve 106 based on the presence or absence of an ON signal output from the water level electrode 54 (an example of information relating to whether or not the liquid level in the tank detected by the liquid level electrode is equal to or higher than a predetermined liquid level).

[0113] In one or more embodiments, the hot water device 2 (example of a microbubble generating device) includes a tank 52 for pressure dissolving air (a gas example) in water (a liquid example), a tank return path 74 (example of a tank supply path) for supplying water to the tank 52, a first pressure pump 88 installed in the tank return path 74, a second pressure pump 90 (example of a pressure pump), and a tank 5 2) a tank passage 64 for discharging air dissolved water under pressure from the bathtub 130 (example of a liquid tank), a first bathtub passage 62, a bathtub adapter 132 (an example of a tank discharge passage), and a microbubble generating nozzle 142 installed in the bathtub adapter 132 and generating fine bubbles by decompressing air dissolved water under pressure, the tank passage 64, the first bathtub passage 62, and the bathtub adapter 132 A tank circulation path 92 installed separately from the outlet port 92a connected to the tank 52 to a water supply port 74a connected to the tank 52 (example of inlet), a tank circulation pump 94 installed on the tank circulation path 92, a gas introduction mechanism 96 installed on the tank circulation path 92, and detecting whether the water level in the tank 52 is equal to or higher than the boundary water level (predetermined liquid level example). A single water level electrode 54 (an example of a liquid level electrode) capable of being used, and a control device 150 are provided. The gas introduction mechanism 96 includes a Venturi tube 102 (an example of a pressure reducing unit) through which water is reduced and passed therethrough, a gas introduction port 104a through which air is introduced by the negative pressure of water in the Venturi tube 102, and a gas introduction valve 106 which opens and closes the gas introduction port 104a. The control device 150 drives the first pressurization pump 88 and the second pressurization pump 90 to pressurize and supply water from the tank return path 74 to the tank 52, and at the same time supply water in which air is pressurized and dissolved from the tank 52 to the bathtub 130 via the tank forward path 64, the first bathtub waterway 62, and the bathtub adapter 132. The control apparatus 150, the tank circulation pump 94 is driven to circulate the water of the tank 52 in the tank circulation route 92, supplying air introduced from the gas entrance 104a to the tank 52, and is detected by the ON signal that is output from the single water electrode 54 Essence of information about whether the tank's fluid is more than a predetermined amount), the opening and closing operation of the gas introduction valve 106 is controlled.

[0114] According to the above configuration, the control device 150 is configured to control the opening and closing operation of the gas introduction valve 106 based on the presence or absence of an ON signal output from one water level electrode 54. For this reason, it is possible to reduce the amount of information on the water level in the tank 52, and to ensure the speed of the judgment process regarding the opening and closing of the gas introduction valve 106.

[0115] In one or more embodiments, the control device 150 closes the gas introduction valve 106 when the water level in the tank 52 is detected by the water level electrode 54 while the gas introduction valve 106 is open while the microbubble generating operation is being executed, and until a first predetermined time elapses after the gas introduction valve 106 is closed, the gas introduction valve 106 is closed. is maintained, and after the first predetermined time has elapsed, the gas introduction valve 106 is opened.

[0116] In the hot water device 2, water droplets scattered from the water surface of the tank 52 adhere to the water level electrode 54, so mucus may be formed on the water level electrode 54. If mucus forms on the water level electrode 54, there is a risk of erroneous detection of the water level in the tank 52. For example, when the hot water device 2 includes a lower water level electrode and an upper water level electrode, and the controller 150 controls the opening and closing operation of the gas introduction valve 106 so that the water level in the tank 52 transitions between the lower water level and the upper water level, the upper water level electrode is hardly immersed in water. For this reason, the generation of slime cannot be suppressed at the upper water level electrode, and there is a possibility that the water level in the tank 52 may be erroneously detected. According to the above structure, by frequently immersing the water level electrode 54 in water while the microbubble generating operation is being executed, the generation of slime in the water level electrode 54 can be suppressed. For this reason, erroneous detection of the water level in the tank 52 can be suppressed.

[0117] In one or more embodiments, the control device 150 specifies, as the intake time, an elapsed time from opening the gas introduction valve 106 in the closed state to closing the gas introduction valve 106 by detecting by the water level electrode 54 that the water level in the tank 52 is lower than the threshold water level after the gas introduction valve 106 is closed while the microbubble generating operation is being executed, and when the intake time exceeds the upper limit intake time, then the first pressure pump 88 , the number of revolutions of the first pressure pump 88 and the second pressure pump 90 when the second pressure pump 90 is driven is reduced.

[0118] When the intake time is too long, it is assumed that the amount of water supplied to the tank 52 is too large or the amount of air introduced by the gas introducing mechanism 96 is too small. In addition, as the rotational speed of the first pressure pump 88 and the second pressure pump 90 increases, the amount of water supplied to the tank 52 increases, and as the rotational speed of the first pressure pump 88 and the second pressure pump 90 decreases, the amount of water supplied to the tank 52 decreases. According to the configuration described above, when the intake time exceeds the upper limit intake time, i.e., when the intake time is too long, the rotation speed of the first pressure pump 88 and the second pressure pump 90 is reduced, thereby reducing the amount of water supplied to the tank 52, thereby shortening the intake time.

[0119] In one or more embodiments, the control device 150 specifies, as the intake time, an elapsed time from opening the gas introduction valve 106 in the closed state to closing the gas introduction valve 106 by detecting, by the water level electrode 54, that the water level in the tank 52 is lower than the threshold water level, while the microbubble generating operation is being executed, and when the intake time is less than the lower limit intake time, then the first pressure pump 88 , the number of revolutions of the first pressure pump 88 and the second pressure pump 90 when the second pressure pump 90 is driven is increased.

[0120] If the intake time is too short, it is assumed that the amount of water supplied to the tank 52 is too small or the amount of air introduced by the gas introduction mechanism 96 is too large. According to the configuration described above, when the intake time is less than the lower limit intake time, that is, when the intake time is too short, the rotation speed of the first pressure pump 88 and the second pressure pump 90 is increased to increase the amount of water supplied to the tank 52, thereby extending the intake time.

[0121] In one or more embodiments, the control device 150 specifies, as the intake time, an elapsed time from opening the gas introduction valve 106 in the closed state to closing the gas introduction valve 106 by detecting, by the water level electrode 54, that the water level in the tank 52 is lower than the threshold water level, while the microbubble generating operation is being executed, and when the intake time exceeds the upper limit intake time, the gas introduction valve 106 thereafter The number of revolutions of the tank circulation pump 94 when the tank circulation pump 94 is driven in an open state is increased.

[0122] When the intake time is too long, it is assumed that the amount of water supplied to the tank 52 is too large or the amount of air introduced by the gas introduction mechanism 96 is too small. Further, with the gas introduction valve 106 open, the higher the rotational speed of the tank circulation pump 94, the higher the amount of air introduced by the gas introduction mechanism 96, and the lower the lower the rotational speed of the tank circulation pump 94, the lower the amount of air introduced by the gas introduction mechanism 96. According to the configuration described above, when the intake time exceeds the upper limit intake time, i.e., when the intake time is too long, by increasing the rotational speed of the tank circulation pump 94, the amount of air introduced by the gas introduction mechanism 96 can be increased and the intake time can be shortened.

[0123] In one or more embodiments, the control device 150 specifies, as the intake time, an elapsed time from opening the gas introduction valve 106 in the closed state to closing the gas introduction valve 106 by detecting, by the water level electrode 54, that the water level in the tank 52 is lower than the threshold water level, while the microbubble generating operation is being executed, and when the intake time is less than the lower limit intake time, the gas introduction valve 106 thereafter The number of revolutions of the tank circulation pump 94 when the tank circulation pump 94 is driven in the open state is reduced.

[0124] If the intake time is too short, it is assumed that the amount of water supplied to the tank 52 is too small or the amount of air introduced by the gas introducing mechanism 96 is too large. According to the configuration described above, when the intake time is less than the lower limit intake time, that is, when the intake time is too short, the rotation speed of the tank circulation pump 94 is reduced, thereby reducing the amount of air introduced by the gas introduction mechanism 96, thereby extending the intake time.

[0125] In one or more embodiments, the control device 150 may determine whether or not a stop condition for stopping the micro-bubble generating operation is satisfied while the micro-bubble generating operation is being executed, and if the stop condition is satisfied, a stop process for stopping the micro-bubble generating operation is executed. When the stop processing is executed, the control device 150 opens the gas introduction valve 106 with the first pressurization pump 88, the second pressurization pump 90 and the tank circulation pump 94 driven, and when the water level electrode 54 detects that the water level in the tank 52 is lower than the boundary water level while the gas introduction valve 106 is open, closes the gas introduction valve 106 and closes the gas introduction valve 106, then , the gas introduction valve 106 is kept closed until the second predetermined time period, which is longer than the first predetermined time period, has elapsed, and after the second predetermined time period has elapsed, the first pressure pump 88, the second pressure pump 90, and the tank circulation pump 94 are stopped to stop the micro-bubble generating operation.

[0126] According to the configuration described above, the microbubble generating operation can be stopped in a state where the water level electrode 54 is immersed in water. Thereby, generation of slime in the water level electrode 54 can be suppressed, and erroneous detection of the water level in the tank 52 can be suppressed. Further, according to the configuration described above, when the microbubble generation operation is stopped, the water level electrode 54 is immersed in water up to a portion above the portion immersed in water during normal operation. Therefore, the generation of slime in the water level electrode 54 can be suppressed more appropriately.

[0127] In one or more embodiments, the control device 150 opens the gas introduction valve 106 when the water level in the tank 52 is detected by the water level electrode 54 while the gas introduction valve 106 is closed while the microbubble generating operation is being executed, and maintains the gas introduction valve 106 open until a third predetermined time elapses after the gas introduction valve 106 is opened. and the gas introduction valve 106 is closed after a third predetermined time has elapsed.

[0128] For example, when the hot water device 2 includes a lower water level electrode and an upper water level electrode, and the controller 150 controls the opening and closing operation of the gas introduction valve 106 so that the water level in the tank 52 transitions between the lower water level and the upper water level, the length of the lower water level electrode needs to be relatively long. In this case, there is a possibility that the weight of the whole hot water device 2 is increased. According to the above configuration, the length of the water level electrode 54 can be relatively shortened. For this reason, the weight reduction of the whole hot water apparatus 2 can be aimed at.

[0129] In one or more embodiments, the liquid is water. The liquid tank is a bathtub 130 that the user uses for bathing.

[0130] According to the configuration described above, in the hot water apparatus 2 that generates fine bubbles in the water of the bathtub 130 used for bathing by the user, it is possible to reduce the amount of information about the water level in the tank 52 and ensure the speed of the judgment process regarding the opening and closing of the gas introduction valve 106.

[0131] Although the examples have been described in detail above, these are merely examples and are not intended to limit the scope of claims. The technology described in the claims includes various modifications and changes of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of application. In addition, the technology exemplified in this specification or drawings can simultaneously achieve a plurality of objects, and has technical usefulness in itself by achieving one of the objects.

[0132] 2: hot water device
10: heat source unit
12: first heat source
14: second heat source
16: water supply
18: tapping road
18a: tapping temperature thermistor
20: Bypass
22: bypass servo
24: casting furnace
26: hot water supply valve for bathtub
28: quantity sensor
30: Circular Progress
30a: thermistor with circulation progress
32: return to circulation
32a: thermistor with return to circulation
34: bathtub circulation pump
36: water flow switch
50: air pressure melting unit
52: tank
54: water level electrode
60: to heat source return
62: first bathtub waterway
64: Tank Progress
66: communication path
68: heat source path
70: second bathtub waterway
74: tank return
74a: water inlet
80: first three-way valve
82: second three-way valve
84: check valve
86: tank water supply valve
88: first pressure pump
90: second pressure pump
92: tank circuit
92a: outlet
94: tank circulation pump
96: gas introduction mechanism
98: intake pipe
100: outlet pipe
102: venturi tube
104: gas introduction path
104a: gas inlet
106: gas introduction valve
130: bathtub
130a: wall part
132: bathtub adapter
132a: front
132b: if
134a: first discharge port
134b: first inlet
134c: second inlet
134d: second discharge port
136: first waterway
136a: first discharge path
136b: first suction path
138: second waterway
138a: second discharge path
138b: second suction passage
140a, 140b, 140c, 140d: Backflow prevention unit
142: fine bubble generating nozzle
150: control device
152: memory
154: remote control
200: water source
250: faucet

Claims (10)

A tank for dissolving a gas in a liquid under pressure;
a tank supply passage for supplying the liquid to the tank;
A pressure pump installed in the tank supply passage;
a tank discharge path for discharging the liquid in which the gas is dissolved under pressure from the tank to a liquid tank;
A micro-bubble generating nozzle installed in the tank discharge passage and generating micro-bubbles by decompressing the liquid in which the gas is dissolved under pressure;
a tank circulation path provided separately from the tank discharge path and sending the liquid from an outlet connected to the tank to an inlet connected to the tank;
a tank circulation pump installed in the tank circulation passage;
a gas introduction mechanism installed in the tank circulation path;
a liquid level electrode capable of detecting whether or not the liquid level in the tank is above a predetermined liquid level;
Equipped with a control device,
The gas introduction mechanism,
A decompression unit for depressurizing and passing the liquid;
a gas inlet for introducing the gas by negative pressure of the liquid in the pressure reducing section;
Equipped with a gas introduction valve that opens and closes the gas inlet,
The control device,
By driving the pressurized pump to pressurize and supply the liquid from the tank supply passage to the tank, at the same time supplying the liquid in which the gas is pressurizedly dissolved from the tank to the liquid tank through the tank discharge passage, performing a fine bubble generation operation,
While the fine bubble generation operation is being executed,
supplying the gas introduced from the gas inlet to the tank by driving the tank circulation pump to circulate the liquid in the tank in the tank circulation path;
The micro-bubble generating device controls the opening and closing operation of the gas introduction valve based on information on whether or not the liquid level in the tank detected by the liquid level electrode is equal to or higher than a predetermined liquid level. According to claim 1,
The control device,
While the fine bubble generation operation is being executed,
Close the gas introduction valve when the liquid level electrode detects that the liquid level in the tank is lower than the predetermined liquid level while the gas introduction valve is open;
The gas introduction valve remains closed until a first predetermined time elapses after the gas introduction valve is closed;
The micro-bubble generating device, wherein the gas introduction valve is opened after the first predetermined time has elapsed. According to claim 2,
The control device,
While the fine bubble generation operation is being executed,
An elapsed time from opening the gas inlet valve in the closed state to when the liquid level in the tank is lower than the predetermined liquid level is detected by the liquid level electrode and the gas inlet valve is closed is specified as an intake time;
The micro-bubble generating device, wherein, when the intake time exceeds an upper limit intake time, the rotational speed of the pressure pump when the pressure pump is subsequently driven is reduced. According to claim 2 or 3,
The control device,
While the fine bubble generation operation is being executed,
An elapsed time from opening the gas inlet valve in the closed state to when the liquid level in the tank is lower than the predetermined liquid level is detected by the liquid level electrode and the gas inlet valve is closed is specified as an intake time;
and increasing the rotational speed of the pressure pump when the pressure pump is subsequently driven when the intake time is less than the lower limit intake time. According to any one of claims 2 or 3,
The control device,
While the fine bubble generation operation is being executed,
An elapsed time from opening the gas inlet valve in the closed state to when the liquid level in the tank is lower than the predetermined liquid level is detected by the liquid level electrode and the gas inlet valve is closed is specified as an intake time;
and increasing the rotational 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 an upper limit intake time. According to any one of claims 2 or 3,
The control device,
While the fine bubble generation operation is being executed,
An elapsed time from opening the gas inlet valve in the closed state to when the liquid level in the tank is lower than the predetermined liquid level is detected by the liquid level electrode and the gas inlet valve is closed is specified as an intake time;
and reducing the rotational speed of the tank circulation pump when the tank circulation pump is subsequently driven with the gas introduction valve open, when the intake time is less than the lower limit intake time. According to any one of claims 2 or 3,
The control device,
While the fine bubble generation operation is being executed,
It is possible to determine whether a stop condition for stopping the micro-bubble generating operation is satisfied,
When the stop condition is satisfied, execute stop processing for stopping the fine-bubble generating operation;
When the above stop processing is executed,
Opening the gas introduction valve in a state in which the pressure pump and the tank circulation pump are driven,
Close the gas introduction valve when the liquid level electrode detects that the liquid level in the tank is lower than the predetermined liquid level while the gas introduction valve is open;
The gas introduction valve maintains a closed state from closing the gas introduction valve until a second predetermined time period longer than the first predetermined time period elapses,
The micro-bubble generating device stops the micro-bubble generating operation by stopping the pressure pump and the tank circulation pump after the second predetermined time has elapsed. According to claim 1,
The control device,
While the fine bubble generation operation is being executed,
When the liquid level in the tank is detected by the liquid level electrode in a state where the gas introduction valve is closed, the gas introduction valve is opened;
The gas introduction valve is maintained in an open state until a third predetermined time elapses after the gas introduction valve is opened;
After the third predetermined time has elapsed, the gas introduction valve is closed. A tank for dissolving a gas in a liquid under pressure;
a tank supply passage for supplying the liquid to the tank;
A pressure pump installed in the tank supply passage;
a tank discharge passage for discharging the liquid in which the gas is dissolved under pressure from the tank to the liquid tank;
A micro-bubble generating nozzle installed in the tank discharge passage and generating micro-bubbles by decompressing the liquid in which the gas is dissolved under pressure;
a tank circulation path provided separately from the tank discharge path and sending the liquid from an outlet connected to the tank to an inlet connected to the tank;
a tank circulation pump installed in the tank circulation passage;
a gas introduction mechanism installed in the tank circulation path;
A single liquid level electrode capable of detecting whether the liquid level in the tank is above a predetermined liquid level;
Equipped with a control device,
The gas introduction mechanism,
A decompression unit for depressurizing and passing the liquid;
a gas inlet for introducing the gas by the negative pressure of the liquid in the pressure reducing section;
Equipped with a gas introduction valve that opens and closes the gas inlet,
The control device,
By driving the pressurized pump to pressurize and supply the liquid from the tank supply passage to the tank, at the same time supplying the liquid in which the gas is dissolved under pressure from the tank to the liquid tank through the tank discharge passage, performing a micro-bubble generating operation,
While the fine bubble generation operation is being executed,
supplying the gas introduced from the gas inlet to the tank by driving the tank circulation pump to circulate the liquid in the tank in the tank circulation path;
wherein the opening and closing operation of the gas introduction valve is controlled based on information on whether the liquid level in the tank detected by the single liquid level electrode is equal to or higher than a predetermined liquid level. According to any one of claims 1, 2, 3, 8, 9,
The liquid is water,
The apparatus for generating microbubbles, wherein the liquid tank is a bathtub used by a user for bathing.