Control method for water electrolysis apparatus, and water electrolysis system and hot-water supply system

Abstract

To stabilize the concentration of functional water produced by a water electrolysis apparatus.SOLUTION: A water electrolysis apparatus 50 generates functional water by electrolyzing the hot water that flows through areas 61, 62 between oppositely arranged plate-shaped cathode 52 and anode 53 and a polymer electrolytic film 55, in parallel with the electrodes, by an energization current Iz generated by a voltage Vz applied between the cathode 52 and anode 53. The energization current Iz is controlled to a higher current value as the detection temperature of the hot water introduced into an inflow entrance 51 increases.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a control method for a water electrolysis device, a water electrolysis system, and a hot water supply system. [Background technology]

[0002] Functional water such as ozone water having a sterilizing effect is generated by electrolysis of water and used for cleaning, etc. For example, Japanese Patent No. 7010529 (Patent Document 1) describes a water electrolysis device that is small but capable of generating a large amount of functional water. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7010529 Summary of the Invention [Problem to be solved by the invention]

[0004] The water electrolysis device is configured to electrolyze the incoming hot water to obtain functional water such as ozonated water as electrolytic water. Therefore, if the condition parameters of the electrolysis are inappropriate, there is a concern that the concentration of the substance having a sterilizing effect in the functional water (hereinafter, also simply referred to as the concentration of the functional water), represented by the ozone concentration in the ozonated water, cannot be stabilized.

[0005] This raises the concern that if the concentration of functional water falls below the target value, the expected sterilization effect will not be obtained, whereas if the concentration of functional water exceeds the target value, there is a concern that the risk of corrosion of the components to which the functional water is supplied will increase in cases where the functional water is used for cleaning pipes, for example.

[0006] The present invention has been made to solve the above problems, and an object of the present invention is to stabilize the concentration of functional water produced by a water electrolysis device. [Means for solving the problem]

[0007] In one aspect of the present invention, there is provided a method for controlling a water electrolysis device. The water electrolysis device has plate-shaped anodes and cathodes arranged opposite to each other, and an electrolyte membrane disposed between the anodes and cathodes, and is configured to generate functional water by electrolysis of hot water in a flow path formed between the anodes and cathodes and the electrolyte membrane and parallel to the anodes and cathodes. The control method includes the steps of detecting the temperature of hot water introduced into the flow path, and controlling a current flowing between the anodes and cathodes when the water electrolysis device is energized, in accordance with the temperature detected in the detection step. The current flowing is controlled to a larger current value as the detected temperature increases.

[0008] In another aspect of the present invention, a water electrolysis system is provided. The water electrolysis system includes a water electrolysis device and a control device. The water electrolysis device has plate-shaped anodes and cathodes arranged opposite each other and an electrolyte membrane disposed between the anodes and cathodes, and is configured to generate functional water by electrolysis of hot water in a flow path formed between the anodes and cathodes and the electrolyte membrane and parallel to the anodes and cathodes. The control device is configured to control the current flowing between the anodes and cathodes when the water electrolysis device is energized. The control device controls the current flowing based on a detected temperature of the hot water introduced into the flow path so that the higher the detected temperature, the higher the current flowing.

[0009] In yet another aspect of the present invention, there is provided a hot water supply system. The hot water supply system includes a hot water supply circuit, the water electrolysis system, and an on-off valve. The hot water supply circuit has a heating unit that heats incoming water and outputs it to a hot water outlet path, and a control unit that controls heating by the heating unit to be turned on and off. The on-off valve is connected between the hot water outlet path and an inlet of a flow path of the water electrolysis device. The hot water supply circuit further has a first water temperature sensor provided in the hot water outlet path, and a second water temperature sensor provided on the input side of the heating unit. The control unit of the hot water supply circuit opens the on-off valve and controls the heating unit to stop heating during operation to produce functional water by the water electrolysis system. In the water electrolysis system, the control device controls the current flow based on a detected temperature of the hot water introduced from the hot water outlet path to the water electrolysis device. Effect of the Invention

[0010] According to the present invention, an object of the present invention is to stabilize the concentration of functional water generated by a water electrolysis device by controlling the current used for electrolysis in accordance with the temperature of the hot water being electrolyzed. [Brief description of the drawings]

[0011] [Figure 1] 1 is a block diagram illustrating a schematic configuration of a functional water production system using a water electrolysis device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram of the configuration of the water electrolysis unit shown in FIG. [Diagram 3] FIG. 4 is a conceptual diagram showing the characteristics of the relationship between the inlet water temperature and the ozone concentration of the water electrolysis device. [Figure 4] FIG. 2 is a conceptual diagram showing the behavior of ozone concentration when a water electrolysis device is operated at a constant current. [Diagram 5] 4 is a flowchart illustrating an operation control process of the water electrolysis apparatus according to the present embodiment. [Figure 6] FIG. 4 is a conceptual diagram illustrating setting of a current reference value for a water electrolysis device. [Figure 7] FIG. 6 is a conceptual diagram showing the behavior of ozone concentration when the water electrolysis apparatus is operated according to the control process of FIG. 5. [Figure 8]FIG. 2 is a block diagram illustrating a schematic configuration of a functional water production system configured using a hot water supply system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, the same or corresponding parts in the drawings are given the same reference characters, and their description will not be repeated in principle.

[0013] FIG. 1 is a block diagram illustrating the schematic configuration of a functional water generating system 100a including a water electrolysis system according to this embodiment.

[0014] As shown in FIG. 1, the functional water generating system 100a includes a supply circuit 10 for hot and cold water to be electrolyzed, a temperature sensor 15, an on-off valve 20, a flow rate sensor 30, and a water electrolysis system 40.

[0015] The supply circuit 10 supplies hot water to be introduced into the water electrolysis device 50 and subjected to electrolysis. The temperature sensor 15 detects the temperature of the hot water introduced into the water electrolysis device 50 (hereinafter also referred to as the inlet water temperature Tw).

[0016] The temperature sensor 15 is disposed, for example, in an output path of hot and cold water supplied from the supply circuit 10 to the water electrolysis device 50. The temperature sensor 15 may be disposed in any location as long as it is capable of measuring the temperature of the hot and cold water flowing into the water electrolysis device 50; however, by disposing the temperature sensor 15 so as to be built into the supply circuit 10 as shown in Fig. 1, the temperature sensor disposed in the supply circuit 10 can be reused, making it unnecessary to dispose a new temperature sensor for operation control of the water electrolysis device 50, which will be described later.

[0017] The on-off valve 20 is disposed between the supply circuit 10 and the input side of the water electrolysis apparatus 50. For example, the opening and closing of the on-off valve 20 is controlled by a controller (not shown) of the functional water production system 100a in conjunction with the on-off operation of the water electrolysis apparatus 50.

[0018] The flow rate sensor 30 detects the flow rate of hot and cold water flowing into the water electrolysis device 50. The flow rate sensor 30 is configured, for example, by an impeller-type flow meter, and detects the flow rate per unit time (for example, liters / minute).

[0019] The water electrolysis system 40 includes a water electrolysis device 50, a power supply board 70, and a controller 80. The controller 80 controls the supply of electricity to the water electrolysis device 50 by the power supply board 70 in accordance with commands from a higher-level controller (e.g., a controller (not shown) of the functional water production system 100a). The power supply board 70 supplies a voltage and current for electrolysis to the water electrolysis device 50 in accordance with commands from the controller 80.

[0020] When the water electrolysis device 50 is turned on, the voltage and current supplied from the power supply board 70 are used to electrolyze hot water introduced from the supply circuit 10, and functional water containing a substance having a sterilizing effect is discharged. In the present embodiment, the control of the ozone concentration when ozone water is generated as functional water by the water electrolysis device 50 will be described below as a representative example.

[0021] The water electrolysis device 50 may be provided with a flow rate adjustment mechanism 60 for adjusting the flow rate. The flow rate adjustment mechanism 60 may be, for example, a constant flow rate valve that limits the flow rate above a certain upper limit flow rate. Alternatively, a servo valve or the like may be provided as the flow rate adjustment mechanism 60 so that the upper limit flow rate can be variably adjusted. Since there is a limit to the flow rate at which an ozone concentration can be ensured relative to the electrolysis capacity of the water electrolysis device 50 (the flow rate through the water electrolysis device 50), providing the flow rate adjustment mechanism 60 can ensure that the ozone concentration is ensured.

[0022] Fig. 2 is a schematic diagram of the configuration of the water electrolysis device 50 shown in Fig. 1. For example, the water electrolysis device 50 may be any of the water electrolysis devices described in Patent Document 1.

[0023] 2, the water electrolysis device 50 has an inlet 51, a cathode 52, an anode 53, an outlet 54, a polymer electrolyte membrane 55, a diamond electrode 56, a cathode-side mesh electrode 57, and an anode-side mesh electrode 58. The cathode 52 and the anode 53 are formed, for example, in a plate shape.

[0024] Hot and cold water input to inlet 51 is introduced so as to form a flow path in a direction along the electrode surfaces (direction parallel to the electrodes) of cathode 52 and anode 53. For example, as described in Patent Document 1, the flow can be generated in a direction from the outer periphery to the inner periphery of the cylindrical structure.

[0025] The polymer electrolyte membrane 55 is made of Nafion (registered trademark) or the like, and is disposed between the cathode 52 and the anode 53. The diamond electrode 56 is provided as a catalyst electrode integral with the polymer electrolyte membrane 55. Note that the polymer electrolyte membrane 55 can be made of any of various solid electrolyte membranes.

[0026] The anode-side mesh electrode 58 is disposed in the anode-side electric field region 61 between the polymer electrolyte membrane 55 and the diamond electrode 56, and the anode 53. The anode-side mesh electrode 58 is disposed so that one end surface (the lower surface in FIG. 2) contacts the anode 53, and the other end surface (the upper surface in FIG. 2) contacts the diamond electrode 56 (polymer electrolyte membrane 55).

[0027] The cathode side mesh electrode 57 is formed in the cathode side electric field region 62 between the polymer electrolyte membrane 55 and the diamond electrode 56, and the cathode 52. The cathode side mesh electrode 57 is disposed so that one end side (upper surface in FIG. 2) surface is in contact with the cathode 52, and the other end side surface (lower surface in FIG. 2) surface is in contact with the polymer electrolyte membrane 55. Each of the cathode side mesh electrode 57 and the anode side mesh electrode 58 may be configured so that two or more mesh electrodes are in contact with each other in the electrode thickness direction.

[0028] As described in Patent Document 1, the materials for the cathode mesh electrode 57 and the anode mesh electrode 58 can be selected depending on the type of functional water to be generated.

[0029] An output voltage Vz of a DC power supply 71 on a power supply board 70 is applied between the cathode 52 and the anode 53. The DC power supply 71 can variably control the output voltage Vz, and is configured, for example, by a switching regulator of an arbitrary circuit configuration.

[0030] A potential difference between the cathode 52 and the anode 53 generates a current Iz between the cathode 52 and the anode 53, electrolyzing hot and cold water flowing through the anode-side electric field region 61 and the cathode-side electric field region 62 between the cathode 52 and the anode 53. A current sensor 72 for detecting the current Iz is disposed on the power supply board 70.

[0031] As the current flows, hydrogen ions (H + The ozone (O3), gases such as oxygen, and hydrogen peroxide (HO) generated by water electrolysis accompanied by the elimination of ions (O2) are dissolved in the flowing hot water to generate electrolyzed water on the anode side. The ozone, gases such as oxygen, and hydrogen peroxide are turned into fine bubbles on the anode side mesh electrode 58 to generate electrolyzed water on the anode side.

[0032] In the cathode-side electric field region 62, hydrogen gas is generated by the hydrogen ions that have passed through the polymer electrolyte membrane 55, and is dissolved in the flowing hot and cold water to generate cathode-side electrolyzed water. The hydrogen gas is turned into fine bubbles by the cathode-side mesh electrode 57, to generate cathode-side electrolyzed water.

[0033] The anode-side electrolyzed water generated in the anode-side electric field region 61 and the cathode-side electrolyzed water generated in the cathode-side electric field region 62 are guided to the outlet 54. Functional water (ozone water) obtained by mixing the two is output from the outlet 54 toward a functional water supply destination 150 (FIG. 1).

[0034] The amount of ozone generated by water electrolysis increases or decreases according to the current Iz. Therefore, the concentration (ozone concentration) of the functional water (ozone water) can be adjusted by adjusting the current Iz. The current Iz is controlled by adjusting the output voltage Vz of the DC power supply 71 by the power supply board 70.

[0035] The following describes the characteristics of the ozone concentration of the ozone water produced by the water electrolysis device 50 obtained by the inventors.

[0036] Fig. 3 is a conceptual diagram showing the relationship between the inlet water temperature Tw and the ozone concentration of the water electrolysis device 50. That is, the horizontal axis of Fig. 3 represents the inlet water temperature Tw, while the vertical axis represents the ozone concentration.

[0037] Fig. 3 shows a schematic diagram of the results of an actual machine test in which the ozone concentration was measured against the inlet water temperature Tw while the water electrolysis device 50 was operating in constant current operation in which the output voltage Vz of the DC power supply 71 was feedback-adjusted so as to keep the current flow Iz constant. In Fig. 3, the constant current operation was performed with different current flow currents Iz, and the change in ozone concentration against the inlet water temperature Tw was obtained for each of a plurality of levels of the current flow Iz.

[0038] As shown in Fig. 3, the ozone concentration has a temperature dependency in that, at the same current Iz, the lower the inlet water temperature Tw, the higher the ozone concentration. Also, at the same inlet water temperature Tw, the larger the current Iz, the higher the ozone concentration.

[0039] Assuming that tap water is introduced into the water electrolysis apparatus 50, the inlet water temperature Tw varies with the season and may also vary depending on the location of the supply circuit 10. For this reason, if the setting of the current Iz passed through the water electrolysis apparatus 50 is fixed, the ozone concentration will vary with the season or depending on the location, making it impossible to obtain an expected ozone concentration. As a result, there is concern that problems such as an insufficient sterilization effect or an increased risk of corrosion of the components to which the ozone is supplied may occur.

[0040] Fig. 4 shows the transient behavior of the ozone concentration when the water electrolysis apparatus 50 is operated at a constant current. The horizontal axis of Fig. 4 is the time axis, and the vertical axis shows the output voltage Vz (plotted by a solid line) adjusted to keep the current Iz constant, and the ozone concentration (plotted by a dotted line). Fig. 4 shows the transient behavior of the ozone concentration immediately after the start of current flow.

[0041] 4, when the current starts at time t0, the output voltage Vz required to obtain a predetermined current Iz becomes higher in the initial period after the start of current flow than in the steady state (for example, after time tx) in which the output voltage Vz is stable. Similarly to the behavior of the output voltage Vz, the ozone concentration becomes higher in the initial period (t0 to tx) than in the steady state (time tx).

[0042] 2, in the water electrolysis apparatus 50, hydrogen ions pass from the anode-side electric field region 61 through the polymer electrolyte membrane 55 to reach the cathode-side electric field region 62, generating a flow current Iz. Therefore, after the start of current flow, as the polymer electrolyte membrane 55 is filled with hydrogen ions, the electrical resistance between the cathode 52 and the anode 53, through which the flow current Iz flows, is equivalently reduced.

[0043] In other words, immediately after the start of current flow (time t0 to tx), before hydrogen ions are filled into the polymer electrolyte membrane 55, a state of high electrical resistance is formed between the cathode 52 and the anode 53, and it is therefore considered that the output voltage Vz required to generate the same current Iz remains large even after the steady state (time tx) in which the polymer electrolyte membrane 55 is filled with hydrogen ions is reached.

[0044] For this reason, if the water electrolysis apparatus 50 is operated simply by constant current operation after the start of energization, there is a concern that the ozone concentration may temporarily become higher than expected.

[0045] As described above, based on the characteristics shown in Figs. 3 and 4 that the inventors obtained through actual machine testing, in the present embodiment, the operation of the water electrolysis apparatus 50 is controlled as described below.

[0046] Fig. 5 is a flowchart illustrating the operation control process of the water electrolysis apparatus according to the present embodiment. In the following, the control process shown in Fig. 5 will be described as being mainly executed by the controller 80 (Fig. 2), but part of the process by the controller 80 described below may be executed by the power supply board 70.

[0047] 5, in step (hereinafter simply referred to as "S") 110, the controller 80 determines whether or not an operation start command for the water electrolysis device 50 has been input from a higher-level controller, and when the operation start command has been input (YES in S110), the controller 80 starts processing from S120 onwards. Until the operation start command is input, NO is determined in S110, and processing from S120 onwards is not started.

[0048] At this time, the operation time Tz for generating ozone water by the water electrolysis device 50 may be input together with the operation start command from the upper controller. Alternatively, the operation start command and the operation end command may be input separately from the upper controller.

[0049] After the operation start command is issued, the upper controller opens the on-off valve 20. When the controller 80 detects the opening of the on-off valve 20 by a signal from the upper controller, the controller 80 executes an initial setting process in S125 to check whether the flow rate Q and the inlet water temperature Tw are within a predetermined operable range. In the initial setting process, an initial value of the current reference value Iref, which is a target value of the energizing current Iz, is set according to the acquired inlet water temperature Tw.

[0050] FIG. 6 is a conceptual diagram illustrating how the current reference value Iref of the water electrolysis device is set.

[0051] As shown in Fig. 6, the current reference value Iref is set according to the inlet water temperature Tw. As shown in Fig. 3, the lower the inlet water temperature Tw and the larger the current Iz, the higher the ozone concentration, so the current reference value Iref corresponding to the inlet water temperature Tw can be determined by determining the current Iz at each inlet water temperature Tw to obtain a desired ozone concentration. As can be seen from Fig. 3, the higher the inlet water temperature Tw, the higher the current reference value Iref is set to.

[0052] 6, the current reference value Iref can be determined by a linear function with the inlet water temperature Tw as a variable. However, the current reference value Iref can also be set by any function expression for changes in the inlet water temperature Tw, or by table values ​​and their interpolation.

[0053] 5 again, in S130, the controller 80 instructs the power supply board 70 to turn on the power supply. In the power supply board 70, an initial value of the output voltage Vz from the DC power supply 71 is determined in accordance with the current reference value Iref set in S125.

[0054] When the current supply starts, the controller 80 detects the inlet water temperature Tw in S140, and executes a process of setting a current reference value Iref in accordance with the detected inlet water temperature Tw (S130) in S150. In the power supply board 70, a current feedback control (S160) is executed to set the output voltage Vz of the DC power supply 71 so that the supply current Iz detected by the current sensor 72 is controlled to the current reference value Iref set by the controller 80.

[0055] The power supply board 70 determines whether the output voltage Vz set by current feedback control exceeds a preset upper limit voltage Vmax (S170). When the output voltage Vz is lower than the upper limit voltage Vmax (YES in S170), the output voltage Vz set in S160 is set as is and applied between the cathode 52 and the anode 53 of the water electrolysis device 50 (S180). That is, constant current operation is performed to make Iz=Iref.

[0056] In contrast, when the output voltage Vz is equal to or higher than the upper limit voltage Vmax (determination of NO in S170), it is limited to Vz=Vmax (S190). Therefore, the upper limit voltage Vmax is applied between the cathode 52 and the anode 53 of the water electrolysis device 50. In other words, when Vz>Vmax, constant voltage operation is performed in which Vz=Vmax is maintained.

[0057] In S200, the controller 80 determines whether or not the operation end condition is satisfied. If the operation time Tz has been input in S110, when the elapsed time from the start of power supply (S120) reaches Tz, a YES determination is made in S200, and an instruction to turn off power supply is issued in S210 to the power supply board 70. As a result, the output voltage Vz of the DC power supply 71 becomes 0, and Iz becomes 0. This causes the generation of ozone water by the water electrolysis device 50 to stop.

[0058] Until the operation end condition is met (NO at S200), the processes of S140 to S190 are repeated while the current is maintained, and the power supply board 70 executes constant current operation (S180) or constant voltage operation (S190).

[0059] Fig. 7 shows the behavior of the ozone concentration when the water electrolysis apparatus is operated according to the control process shown in Fig. 5. The horizontal and vertical axes in Fig. 7 are the same as those in Fig. 4, and Fig. 7 also shows the transient behavior of the ozone concentration immediately after the start of current flow, as in Fig. 4.

[0060] 7, during the period immediately after the start of energization when the electrical resistance between the cathode 52 and the anode 53 is equivalently high, constant voltage operation is performed with Vz maintained at Vmax (time t0 to ty). After time ty, constant current operation is performed to adjust the output voltage Vz so as to maintain the energizing current Iz at the current reference value Iref set based on the inlet water temperature Tw.

[0061] In contrast, the waveforms in Fig. 4 correspond to the case where the processes of S170 and S180 are omitted from Fig. 5 and only constant current operation is performed from the start of current flow. As described above, in Fig. 4 (constant current operation only), the output voltage Vz rises in the period immediately after the start of current flow, causing the ozone concentration to overshoot and then converge to a steady value.

[0062] In contrast, in Fig. 7, between times t0 and ty, the output voltage Vz is suppressed to equal to or lower than the upper limit voltage Vmax by constant voltage operation, and it can be seen that an overshoot in the ozone concentration does not occur as occurs between times t0 and tx in Fig. 4. Furthermore, with regard to the ozone concentration in the steady state after time tx, a desired concentration can be achieved by setting the current reference value Iref in constant current control based on the inlet water temperature Tw.

[0063] In this way, the water electrolysis apparatus according to the present embodiment controls the ozone concentration to be stable for different inlet water temperatures Tw by setting the current reference value Iref in accordance with the inlet water temperature Tw, or to be stable even if the inlet water temperature Tw changes over time.

[0064] Furthermore, by combining constant voltage operation for limiting the output voltage Vz so as not to exceed a certain upper limit voltage Vmax with constant current operation according to the current reference value Iref as a base, it is possible to suppress a temporary increase in the ozone concentration, particularly during the period immediately after the start of current flow when the electrical resistance between the cathode 52 and the anode 53 is equivalently high. This makes it possible to stabilize the ozone concentration in a transient state as well.

[0065] The upper limit voltage Vmax during constant voltage operation can also be variably set in conjunction with the detected value of the inlet water temperature Tw. Specifically, like the current reference value Iref, the upper limit voltage Vmax can be set to be higher as the inlet water temperature Tw is higher. In this way, the dependency of the ozone concentration on the inlet water temperature Tw during constant voltage operation can be suppressed, thereby further stabilizing the ozone concentration.

[0066] Furthermore, by limiting the maximum voltage applied between the cathode 52 and the anode 53, deposition of minerals at the cathode 52 can be suppressed, and the durability of the water electrolysis device 50 can be improved.

[0067] FIG. 8 is a block diagram illustrating a schematic configuration of a functional water production system formed by the hot water supply system 100b.

[0068] 8, a hot water supply system 100b is configured by using the hot water supply circuit 11 in the water heater of the functional water production system 100a of Fig. 1 as the supply circuit 10. In the hot water supply system 100b, a supply destination 150 of the functional water can be a pipe leading to a bathtub (not shown), a mist shower in a bathroom (not shown), or a home facility such as a washroom, kitchen, or toilet that is to be cleaned with the functional water.

[0069] The hot water supply circuit 11 includes a burner 12 that burns a fuel such as gas, a heat exchanger 13, and a controller 14. The heat exchanger 13 receives heat from the burner 12 to heat the hot water flowing therethrough, and outputs the heat to a hot water outlet path 19 that leads to a hot water tap (not shown) or the like.

[0070] Controller 14 controls the on / off of combustion in burner 12 and the amount of heat generated during combustion (e.g., the flow rate of gas as fuel, etc.). For example, when the operation switch of a water heater including hot water supply circuit 11 is on and a flow rate exceeding the minimum operating flow rate (MOQ) occurs in heat exchanger 13, controller 14 turns on combustion in burner 12 and controls the amount of heat generated by burner 12 so that the temperature detected by temperature sensor 15 arranged in hot water outlet path 19 becomes the hot water supply set temperature. In hot water supply circuit 11, generally, temperature sensor 16 for detecting the water temperature before heating by heat exchanger 13 is arranged together with the above-mentioned temperature sensor 15 for detecting the outlet hot water temperature.

[0071] The on-off valve 20 is provided in a path branched off from the hot water outlet path 19, for supplying hot water to the water electrolysis device 50. For example, the on-off valve 20 is provided in a hot water supply path for supplying hot water from the hot water supply circuit 11 to a bathtub. Furthermore, the hot water supply path may be provided with a three-way valve 120 for selecting between path P1 that passes through the water electrolysis device 50 and path P2 that bypasses the water electrolysis device 50.

[0072] In this way, when the functional water supply destination 150 is piping for pouring hot water into a bathtub, the three-way valve 120 selects path P1, making it possible to execute a pipe cleaning operation using the ozone water (functional water) generated by the water electrolysis device 50. On the other hand, the three-way valve 120 selects path P2, making it possible to supply hot water for filling the bathtub, etc., via a high flow rate path that bypasses the water electrolysis device 50 and the flow rate adjustment mechanism 60.

[0073] Similarly, even if the destination 150 of the functional water is the mist shower described above or a home appliance to be cleaned, by installing a three-way valve 120 to enable switching between paths P1 and P2, the user can select whether or not to use the functional water, thereby improving marketability.

[0074] The controller 14 can operate as a host controller of the controller 80 of the water electrolysis system 40. For example, the controller 14 can operate the water electrolysis system 40 to perform a pipe cleaning operation by operating the water electrolysis device 50 when drainage from the bathtub is detected based on a detection value of a water level sensor (not shown) provided in the bathtub.

[0075] In this case, by opening on-off valve 20 and selecting path P1 by three-way valve 120, hot water is supplied to water electrolysis device 50 from hot water supply circuit 11 (hot water outlet path 19), and then turning on electricity to water electrolysis device 50, it becomes possible to clean the pipes using ozone water (functional water) produced by water electrolysis device 50. At this time, the temperature detected by temperature sensor 15 in hot water outlet path 19 is used as the inlet water temperature Tw to the water electrolysis device 50 in hot water supply system 100b in Figure 8 as well, so that the control of the water electrolysis device described with reference to Figures 5 to 7 can be applied.

[0076] 3, the lower the inlet water temperature Tw, the higher the ozone concentration, and therefore, in the pipe cleaning operation, the combustion of burner 12 is turned off in hot water supply circuit 11. That is, the water entering hot water supply circuit 11 is supplied to water electrolysis device 50 without being heated. Therefore, inlet water temperature Tw in water electrolysis device 50 can be detected by temperature sensor 16 in addition to temperature sensor 15 in hot water outlet path 19. That is, temperature sensor 15 corresponds to an example of a "first water temperature sensor," and temperature sensor 16 corresponds to an example of a "second temperature sensor."

[0077] For this reason, in controlling the water electrolysis apparatus in the hot water supply system 100b, the inlet water temperature Tw can be detected using both of the temperature sensors 15 and 16. Therefore, for example, by setting the current reference value Iref using the minimum value (lowest temperature) of the temperatures detected by the temperature sensors 15 and 16, it is possible to prevent the energizing current Iz from becoming excessively large with respect to the actual inlet water temperature even when the temperature detected by the temperature sensor 16 becomes abnormal.

[0078] This makes it possible to stabilize the ozone concentration, in particular to suppress an increase in the ozone concentration caused by an abnormality in the temperature sensor 16, compared to when the current reference value Iref is set using only the temperature detected by the temperature sensor 16.

[0079] In the present embodiment, an example has been described in which ozone water is produced as functional water by electrolysis of hot and cold water using the water electrolysis device 50, but as described in Patent Document 1, by appropriately changing the materials of the cathode side mesh electrode 57 and the anode side mesh electrode 58, it is possible to produce functional water having a sterilizing effect other than ozone water using the water electrolysis device 50. In this case, too, functional water with a stable concentration can be produced by applying the control of the output voltage Vz that combines the current flowing in constant current operation and constant voltage operation as described in Fig. 5.

[0080] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0081] 10 supply circuit, 11 hot water supply circuit, 12 burner, 13 heat exchanger, 14, 80 controller, 15, 16 temperature sensor, 19 hot water outlet path, 20 on-off valve, 30 flow sensor, 40 water electrolysis system, 50 water electrolysis device, 51 inlet, 52 cathode, 53 anode, 54 outlet, 55 polymer electrolyte membrane, 56 diamond electrode, 57 cathode mesh electrode, 58 anode mesh electrode, 60 flow rate adjustment mechanism, 61 anode electric field region, 62 cathode electric field region, 70 power supply board, 71 DC power supply, 72 current sensor, 100a functional water generation system, 100b hot water supply system, 120 three-way valve, 150 functional water supply destination, Iref current reference value, Iz current flow, P1, P2 path, Q flow rate, Tw inlet water temperature, Tz Operating time, Vmax upper limit voltage, Vz output voltage (DC power supply).

Claims

1. A method for controlling a water electrolysis device comprising: plate-shaped anodes and cathodes disposed opposite to each other; and an electrolyte membrane disposed between the anodes and the cathodes; and configured to generate functional water by electrolysis of hot and cold water in a flow path formed between the anodes and the cathodes and the electrolyte membrane, the flow path being parallel to the anodes and the cathodes, the method comprising the steps of: Detecting the temperature of the hot and cold water introduced into the flow path; and controlling, in response to the temperature detected in the detecting step, a current flowing between the anode and the cathode during energization of the water electrolysis device; A method for controlling a water electrolysis apparatus, wherein the energizing current is controlled to a larger current value as the detected temperature increases.

2. The controlling step includes: setting a current reference value based on the detected temperature so that the energizing current has a large current value; 2. The method for controlling a water electrolysis apparatus according to claim 1, further comprising the step of: setting a voltage applied between the anode and the cathode to control the energizing current to the current reference value.

3. The controlling step includes:

3. The method of controlling a water electrolysis apparatus according to claim 2, further comprising the step of comparing a set value of the applied voltage with an upper limit voltage, and applying the upper limit voltage between the anode and the cathode when the set value is higher than the upper limit voltage.

4. The method for controlling a water electrolysis apparatus according to claim 3 , wherein the upper limit voltage is set to a higher voltage value as the detected temperature increases.

5. a water electrolysis device including plate-like anode and cathode disposed opposite to each other and an electrolyte membrane disposed between the anode and the cathode, the water electrolysis device being configured to generate functional water by electrolysis of hot and cold water in a flow path formed between the anode and the cathode and the electrolyte membrane in parallel with the anode and the cathode; a control device for controlling a current flowing between the anode and the cathode when the water electrolysis device is energized, The control device controls the energizing current based on a detected temperature of hot water introduced into the flow path so that the energizing current has a larger current value as the detected temperature increases.

6. The control device includes: a DC power supply configured to apply a variable output voltage between the anode and the cathode; a controller for controlling the output voltage of the DC power supply; 6. The water electrolysis system according to claim 5, wherein the controller sets a current reference value based on a detected temperature of the hot water introduced into the flow path such that the higher the detected temperature, the larger the current value, and sets the output voltage to control the energizing current to the set current reference value.

7. The water electrolysis system according to claim 6 , wherein the controller compares a set value of the output voltage with an upper limit voltage, and sets the output voltage to the upper limit voltage when the set value is higher than the upper limit voltage.

8. The controller variably sets the upper limit voltage in response to the detected temperature, The water electrolysis system according to claim 7 , wherein the upper limit voltage is set to a higher voltage value as the detected temperature increases.

9. A hot water supply circuit having a heating unit that heats incoming water and outputs the water to a hot water outlet path and a control unit that controls on / off of heating by the heating unit; The water electrolysis system according to any one of claims 5 to 8, an on-off valve connected between the hot water outlet path and an inlet of the flow path of the water electrolysis device; The hot water supply circuit includes: the control unit controls the heating unit to open the on-off valve and stop heating during an operation in which the functional water is produced by the water electrolysis system; and In the water electrolysis system, the control device controls the energizing current based on a detected temperature of the hot water introduced from the hot water outlet path to the water electrolysis device.

10. The hot water supply circuit includes: A first water temperature sensor provided in the hot water outlet path; A second water temperature sensor is provided on the input side of the heating unit, 10. The hot water supply system according to claim 9, wherein in the water electrolysis system, the control device determines the detected temperature used for controlling the energization current in accordance with a lowest temperature among detected temperatures of the first water temperature sensor and the second water temperature sensor.

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