Electrolyzed water generation device and control method therefor

Abstract

An electrolyzed water generation device 1 includes a water supply valve 2, an electrolysis unit 3, a tank 5, a water level detection unit 6, and a controller 8 for controlling the water supply valve 2 and the electrolysis unit 3. The controller 8 includes, as control modes, a water production mode in which the water supply valve 2 is opened and the electrolyzed water generated by the electrolysis unit 3 is supplied to the tank 5, and a standby mode in which the water supply valve 2 is closed and the electrolysis unit 3 stands by without performing the electrolysis. The water production mode and the standby mode are alternately and repeatedly executed. The controller 6 includes: a calculation unit that calculates a reduction speed of a water level in the tank 5 on the basis of an output from the water level detection unit 6; a determination unit that determines a timing for shifting from the water production mode to the standby mode; and a transition unit that shifts the control mode from the water production mode to the standby mode.

Description

Electrolyzed water generating device and its control method

[0001] The present invention relates to an electrolyzed water generating device.

[0002] In recent years, dialysis treatment using electrolyzed water generated by an electrolyzed water generator has attracted attention. For example, electrolyzed hydrogen water, which contains dissolved hydrogen gas generated by electrolyzing water, is known to contribute to reducing oxidative stress in patients (see, for example, Patent Document 1 below).

[0003] Japanese Patent Application Laid-Open No. 2015-139475

[0004] In large hospitals, dialysis treatment is performed on many patients at the same time, so electrolyzed water generators are equipped with tanks for storing large amounts of electrolyzed water.

[0005] On the other hand, dialysis treatment is not usually performed all the time, and there are times when the electrolyzed water in the tank is not consumed. During such times, in order to prevent an excessive increase in the dissolved hydrogen concentration of the electrolyzed water, the circulation of the electrolyzed water between the tank and the electrolysis unit and the electrolysis in the electrolysis unit are stopped, and the electrolyzed water in the tank remains in the tank and stands by without electrolysis.

[0006] However, as the dissolved hydrogen gas escapes from the electrolytic water in the standby state, the dissolved hydrogen concentration gradually decreases.

[0007] The present invention has been devised in consideration of the above-described circumstances, and its main object is to provide an electrolytic water generating device that can suppress a decrease in the dissolved hydrogen concentration of electrolytic water in a standby state.

[0008] The present invention provides an electrolyzed water generator comprising: a water supply valve for controlling the supply of raw water; an electrolysis unit for generating electrolyzed water by electrolyzing the raw water supplied from the water supply valve; a tank for storing the electrolyzed water generated by the electrolysis unit; a water level detection unit for detecting the water level in the tank; and a control unit for controlling the water supply valve and the electrolysis unit, wherein the control unit includes, as control modes, a fresh water production mode in which the water supply valve is opened and the electrolyzed water generated by the electrolysis unit is supplied to the tank; and a standby mode in which the water supply valve is closed and the electrolysis unit is on standby without performing electrolysis, the fresh water production mode and the standby mode being executed alternately and repeatedly, and the control unit includes: a calculation unit for calculating a rate of decrease of the water level in the tank based on an output from the water level detection unit; a determination unit for determining a first timing for transitioning from the fresh water production mode to the standby mode in accordance with the rate of decrease; and a transition unit for transitioning the control mode from the fresh water production mode to the standby mode based on the first timing.

[0009] In the electrolyzed water generating device of the present invention, the control unit determines the timing of transition from the fresh water production mode to the standby mode according to the rate of decrease of the water level in the tank, and transitions the control mode, thereby optimizing the water level in the tank and suppressing a decrease in the dissolved hydrogen concentration of the electrolyzed water in the standby state.

[0010] 1 is a block diagram showing a schematic configuration of the electrolyzed water generator of the present invention. FIG. 2 is a diagram showing the configuration of the electrolysis unit of FIG. 1. FIG. 3 is a flowchart showing the procedure of the electrolyzed water generating method of the present invention. FIG. 4 is a block diagram showing the configuration of the control unit of FIG. 1. FIG. 5 is a flowchart showing the procedure of transition from the standby mode to the fresh water production mode of FIG. 3. FIG. 6 is a graph showing an example of a table showing the relationship between the rate of decrease in water level and the first timing. FIG. 7 is a cross-sectional view showing a modified example of the water level detection unit of FIG. 1 together with the tank. FIG. 8 is a cross-sectional view showing a modified example of the water level detection unit of FIG. 7 together with the tank. FIG. 9 is a block diagram showing a modified example of the water level detection unit of FIG. 8 together with the tank. FIG. 10 is a block diagram showing a modified example of the electrolyzed water generator of FIG. 1. FIG. 11 is a block diagram showing another modified example of the electrolyzed water generator of FIG. 1.

[0011] An embodiment of the present invention will now be described with reference to the drawings. Fig. 1 shows a schematic configuration of an electrolyzed water generator 1 according to this embodiment. The electrolyzed water generator 1 is a device for generating electrolyzed water and is connected to a dialysis fluid preparation device 100 for preparing dialysis fluid. The electrolyzed water generator 1 supplies the generated electrolyzed water to the dialysis fluid preparation device 100.

[0012] The electrolyzed water generating device 1 comprises a water supply valve 2 for controlling the supply of raw water, an electrolysis unit 3 for generating electrolyzed water, a tank 5 for storing the electrolyzed water, a water level detection unit 6 for detecting the water level in the tank 5, and a control unit 8 for controlling the water supply valve 2, the electrolysis unit 3, etc.

[0013] The raw water supplied to the water feed valve 2 is generally tap water, but other sources such as well water and groundwater can also be used. The raw water is subjected to pretreatment such as softening before being supplied to the water feed valve 2. The raw water to be electrolyzed is then supplied to the electrolysis unit 3 via the water feed valve 2.

[0014] Figure 2 shows the electrolysis unit 3. The electrolysis unit 3 includes an electrolytic cell 4. When the dialysis solution prepared by the dialysis solution preparation device 100 is to be used for dialysis of a large number of patients, the electrolysis unit 3 is preferably configured to include multiple electrolytic cells 4, as shown in Figure 2. The multiple electrolytic cells 4 are connected in parallel to each other as flow paths. By operating such multiple electrolytic cells 4 simultaneously, a large amount of electrolyzed water can be rapidly produced.

[0015] The electrolytic cell 4 includes an electrolysis chamber 40, an anode power supply 41, a cathode power supply 42, and a diaphragm 43. The electrolysis chamber 40 is divided by the diaphragm 43 into an anode chamber 40a in which the anode power supply 41 is disposed and a cathode chamber 40b in which the cathode power supply 42 is disposed. Raw water is supplied to the anode chamber 40a and the cathode chamber 40b, for example, via a bifurcated flow path (not shown).

[0016] The voltage applied between the anode power supply 41 and the cathode power supply 42 is controlled by the control unit 8 .

[0017] The control unit 8 controls each part of the electrolyzed water generating device 1. The control unit 8 has, for example, a CPU (Central Processing Unit) that executes various arithmetic processing, information processing, etc., and a memory that stores programs that control the operation of the CPU and various information. The various functions of the control unit 8 are realized by the CPU, memory, and programs.

[0018] The control unit 8 feedback-controls the electrolysis voltage applied to the anode power supply 41 and the cathode power supply 42 so that the electrolysis current supplied to the anode power supply 41 and the cathode power supply 42 is a predetermined desired value. For example, if the electrolysis current is excessive, the control unit 8 reduces the voltage, and if the electrolysis current is too small, the control unit 8 increases the voltage. This allows the electrolysis current to be appropriately controlled. The electrolysis current is measured, for example, by a measuring unit provided in a circuit that supplies power to the anode power supply 41 and the cathode power supply 42.

[0019] Of the electrolyzed water electrolyzed in the electrolytic cell 4, the electrolyzed water produced in the cathode chamber 40b is sent to the tank 5 as cathode water. On the other hand, the electrolyzed water produced in the anode chamber 40a is discharged to the outside of the electrolyzed water production device 1 as anode water.

[0020] Water is electrolyzed in the electrolytic cell 4, whereby oxygen gas is generated in the anode chamber 40a and hydrogen gas is generated in the cathode chamber 40b.

[0021] The oxygen gas generated in the anode chamber 40 a dissolves in the electrolytic water in the anode chamber 40 a , is taken out of the anode chamber 40 a as anode water, and is discharged to the outside of the electrolytic water generating device 1 .

[0022] The hydrogen gas generated in the cathode chamber 40b dissolves in the electrolyzed water in the cathode chamber 40b, is extracted from the cathode chamber 40b as cathode water, and is sent to the tank 5. That is, the cathode water sent from the cathode chamber 40b to the tank 5 is electrolyzed hydrogen water in which hydrogen gas has been dissolved as a result of electrolysis in the cathode chamber 40b.

[0023] In Figure 1, the tank 5 stores electrolyzed water supplied from the electrolysis unit 3. This makes it possible to supply a large amount of electrolyzed water to the dialysis solution preparation device 100 at one time. When electrolyzed water is to be used for dialysis treatment, electrolyzed water generated in the cathode chamber 40b is supplied to the tank 5. When electrolyzed water is to be used for purposes other than dialysis treatment, electrolyzed water generated in the anode chamber 40a may be supplied to the tank 5.

[0024] The tank 5 is provided with a water level detection unit 6 for detecting the water level within the tank 5. The water level detection unit 6 detects the water level within the tank 5, for example, by optical means or buoyancy. In this embodiment, a light-transmitting window is provided in a part of the outer wall of the tank 5, and a sensor that detects the water level without coming into contact with the electrolyzed water using light that passes through the window is used as the water level detection unit 6. This can suppress the generation and proliferation of germs within the tank 5.

[0025] The water level detection unit 6 may be configured to directly detect the water level in the tank 5 using a sensor, or may be configured to indirectly detect the water level in the tank 5. One example of a configuration for indirectly detecting the water level in the tank 5 is a configuration that includes a first flow meter 11, which will be described later. The first flow meter 11 detects the amount of water flowing out of the tank 5 per unit time. Since the capacity of the tank 5 is constant, the water level in the tank 5 is calculated based on the amount of water flowing out of the tank 5 per unit time.

[0026] The water level detection unit 6 transmits a signal corresponding to the detected water level to the control unit 8. The control unit 8 determines the water level in the tank 5 based on the signal transmitted from the water level detection unit 6.

[0027] The dialysis solution preparation device 100 is a device for preparing dialysis solution by mixing a dialysis base agent with electrolyzed water supplied from the electrolyzed water generator 1. The dialysis base agent to be mixed with the electrolyzed water may be in liquid form or powder form. The tank 5 constituting the electrolyzed water generator 1 is connected to the dialysis solution preparation device 100 so as to be able to supply electrolyzed water. In this embodiment, a water channel 9 connecting the tank 5 and the dialysis solution preparation device 100 extends from the electrolyzed water generator 1.

[0028] The dialysis fluid prepared by the dialysis fluid preparation device 100 is sent to a dialysis device (not shown). The dialysis device includes a dialysis fluid supply device and a dialyzer. The dialysis fluid supply device sends the dialysis fluid supplied from the dialysis fluid preparation device 100 to the dialyzer. The dialyzer is an artificial kidney including a dialysis membrane formed of a porous membrane such as a hollow fiber membrane, and applies the dialysis fluid supplied from the dialysis fluid preparation device 100 through the dialysis membrane to the blood of a patient undergoing dialysis treatment to remove waste products and water from the blood.

[0029] FIG. 3 shows the procedure of a control method 200 for the electrolytic water generator 1, which is a method for generating electrolytic water using the electrolytic water generator 1.

[0030] The control method 200 includes a fresh water production mode M1 and a standby mode M2 ​​as control modes of the control unit 8. The fresh water production mode M1 and the standby mode M2 ​​are normally executed alternately and repeatedly, except when the consumption of electrolyzed water is extremely small.

[0031] The fresh water production mode M1 is a mode in which the water supply valve 2 is opened and electrolyzed water generated in the electrolysis unit 3 is supplied to the tank 5 to produce fresh water. When the electrolyzed water production device 1 starts operating, the fresh water production mode M1 is first executed. In the fresh water production mode M1, the water supply valve 2 is opened and electrolyzed water is produced in the electrolysis unit 3. The produced electrolyzed water is supplied to the tank 5 and stored.

[0032] Standby mode M2 ​​is a standby mode in which the water supply valve 2 is closed, electrolysis is not performed in the electrolysis unit 3, and electrolyzed water is retained in the tank 5. Due to the convenience of the patient and the hospital, there is usually a slight waiting time before dialysis treatment. During this waiting time, the electrolyzed water generator 1 enters standby mode M2 ​​and waits.

[0033] In standby mode M2, when a request signal for electrolyzed water is received from an external device such as the dialysis fluid preparation device 100, the electrolyzed water in the tank 5 is supplied to the dialysis fluid preparation device 100 via the water channel 9. As a result, the electrolyzed water in the tank 5 is consumed, and the water level in the tank 5 decreases. Even during dialysis treatment, the electrolyzed water generation device 1 waits in standby mode M2 ​​until the consumption of the electrolyzed water progresses.

[0034] Dialysis fluid is prepared immediately before dialysis treatment. On the other hand, electrolyzed water used to prepare dialysis fluid is prepared in advance, for example, when the hospital opens (e.g., in the morning). That is, the control unit 8 initially controls the electrolyzed water generator 1 in fresh water production mode M1. The electrolyzed water produced in fresh water production mode M1 is supplied to the tank 5 and stored in the tank 5 until dialysis treatment begins. When the electrolyzed water reaches the upper limit of the tank 5, the control unit 8 switches the control mode of the electrolyzed water generator 1 to standby mode M2 ​​and puts the device into standby mode.

[0035] If the standby mode M2 ​​continues for a long period of time thereafter, the dissolved hydrogen concentration of the electrolyzed water in the tank 5 gradually decreases. For this reason, the electrolyzed water may be discharged from the tank 5 and the fresh water production mode M1 executed to restore the dissolved hydrogen concentration of the electrolyzed water in the tank 5. In this case, the electrolyzed water discharged from the tank 5 may be returned to the electrolysis unit 3, and the electrolyzed water may be configured to circulate between the electrolysis unit 3 and the tank 5.

[0036] 4 shows the configuration of the control unit 8. The control unit 8 includes a calculation unit 81 that calculates the rate at which the water level in the tank 5 decreases, a determination unit 82 that determines the timing to transition from the fresh water production mode M1 to the standby mode M2, and a transition unit 83 that transitions the control mode. The calculation unit 81, the determination unit 82, and the transition unit 83 are realized by cooperation between the above-mentioned hardware such as the CPU and memory and a program (software), but may also be realized by individual hardware circuits.

[0037] The calculation unit 81 has a function of counting time, and calculates the decrease in the water level in the tank 5 per unit time, i.e., the rate of decrease in the water level, based on the signal output from the water level detection unit 6.

[0038] The determination unit 82 determines the first timing to transition from fresh water production mode M1 to standby mode M2, i.e., to end fresh water production mode M1, depending on the rate at which the water level in the tank 5 decreases. For example, when the rate at which the water level in the tank 5 decreases is slow, the dissolved hydrogen concentration of the electrolyzed water in the tank 5 gradually decreases. Therefore, the determination unit 82 estimates the dissolved hydrogen concentration of the electrolyzed water based on the rate at which the water level in the tank 5 decreases, and determines the first timing to transition from fresh water production mode M1 to standby mode M2. Note that the first timing to transition from fresh water production mode M1 to standby mode M2 ​​essentially corresponds to the water level in the tank 5 when the fresh water production mode M1 ends and the mode changes to standby mode M2.

[0039] The determination unit 82 may be configured to determine a second timing for transitioning from the standby mode M2 ​​to the fresh water production mode M1, as will be described later.

[0040] Then, the transition unit 83 transitions the control mode of the electrolyzed water generator 1 from the fresh water production mode M1 to the standby mode M2 ​​based on the first timing determined by the determination unit 82. That is, the transition unit 83 closes the water supply valve 2 and stops the supply of electrolytic current to the electrolysis unit 3, thereby stopping the supply of electrolyzed water into the tank 5.

[0041] 3, the rate of decrease in the water level is calculated when the electrolyzed water generator 1 is in standby mode M2. Therefore, based on the first timing determined by the determination unit 82, the transition unit 83 transitions the control mode of the electrolyzed water generator 1 from fresh water production mode M1 to standby mode M2 ​​in the second or subsequent cycles shown in FIG.

[0042] The electrolyzed water replenished in fresh water production mode M1 has a high dissolved hydrogen concentration and has just been produced by the electrolysis unit 3. Therefore, in fresh water production mode M1 in the second or subsequent cycles, the dissolved hydrogen concentration of the electrolyzed water that had decreased in the immediately preceding standby mode M2 ​​is increased by replenishment of the tank 5 with electrolyzed water produced by the electrolysis unit 3.

[0043] The concentration of dissolved hydrogen in the electrolyzed water in the tank 5 in standby mode M2 ​​depends on the rate at which the water level in the tank 5 decreases. In the electrolyzed water generating device 1, the transition unit 83 transitions the control mode from the fresh water production mode M1 to the standby mode M2 ​​based on the first timing determined by the determination unit 82 in accordance with the rate at which the water level in the tank 5 decreases calculated by the calculation unit 81, thereby optimizing the water level in the tank 5 in the second and subsequent cycles and making it possible to suppress a decrease in the concentration of dissolved hydrogen in the electrolyzed water in the standby state.

[0044] 5 shows the procedure for transitioning from the fresh water production mode M1 to the standby mode M2. The fresh water production mode M1 and the standby mode M2 ​​in the figure are the fresh water production mode M1 and the standby mode M2 ​​in the second and subsequent cycles in FIG. 3.

[0045] The transition from fresh water production mode M1 to standby mode M2 ​​is achieved by executing a first step S10 of calculating the rate at which the water level in tank 5 decreases, a second step S20 of determining the timing to transition from fresh water production mode M1 to standby mode M2, and a third step S30 of transitioning the control mode from fresh water production mode M1 to standby mode M2.

[0046] In the first step S10, the calculation unit 81 calculates the decrease in the water level in the tank 5 per unit time, i.e., the rate of decrease in the water level in the tank 5, based on the signal output from the water level detection unit 6.

[0047] In the second step S20, the determination unit 82 determines the first timing for transitioning from the fresh water production mode M1 to the standby mode M2, depending on the rate of decrease in the water level in the tank 5 calculated in the first step S10.

[0048] Then, in the third step S30, the transition unit 83 transitions the control mode of the electrolyzed water generator 1 from the fresh water production mode M1 to the standby mode M2 ​​based on the first timing determined in the second step S20. This stops the replenishment of electrolyzed water from the electrolysis unit 3 to the tank 5 even before the electrolyzed water level reaches the upper limit of the tank 5.

[0049] In FIG. 5, the first step S10 and the second step S20 are executed during the fresh water production mode M1, but depending on the processing capacity of the control unit 8, some or all of the first step S10 and the second step S20 may be executed before the fresh water production mode M1.

[0050] As already mentioned, the concentration of dissolved hydrogen in the electrolyzed water in the tank 5 depends on the rate at which the water level in the tank 5 decreases. In the control method 200 of the electrolyzed water generating device 1, the control mode is shifted from the fresh water production mode M1 to the standby mode M2 ​​in the third step S30 based on the first timing determined in the second step S20 in accordance with the rate at which the water level in the tank 5 decreases calculated in the first step S10, thereby optimizing the water level in the tank 5 in the second and subsequent cycles and making it possible to suppress a decrease in the concentration of dissolved hydrogen in the electrolyzed water in the standby state.

[0051] In the electrolyzed water generating apparatus 1, the determining unit 82 is preferably configured to determine the first timing by comparing the rate at which the water level in the tank 5 decreases with a predetermined threshold value. The threshold value is stored, for example, in the memory of the control unit 8. The threshold value is preferably rewritable depending on the usage status of the electrolyzed water and the specifications of the dialysis solution preparation device 100 connected to the electrolyzed water generating apparatus 1.

[0052] For example, if the rate of decrease in the water level is smaller than the threshold value, the first timing for transitioning from fresh water production mode M1 to standby mode M2 ​​is advanced relative to a predetermined reference value to prevent a large amount of electrolyzed water from being stored in the tank 5. This suppresses the decrease in the dissolved hydrogen concentration of the electrolyzed water in the standby state.

[0053] On the other hand, if the rate at which the water level decreases is greater than the threshold value, the first timing for transitioning from the water production mode M1 to the standby mode M2 ​​is delayed relative to a predetermined reference value to prevent the electrolyzed water in the tank 5 from running out.

[0054] In this case, it is desirable that the first timing be determined in accordance with the difference between the threshold value and the rate of decrease in the water level.

[0055] For example, if the deviation of the rate of decrease of the water level from the threshold value is small, the deviation of the first timing from the reference value is set small, and if the deviation of the rate of decrease of the water level from the threshold value is large, the deviation of the first timing from the reference value is set large, thereby enabling better control of the water level in tank 5.

[0056] Similarly, in the control method 200 for the electrolytic water generating device 1, the second step S2 is preferably configured to determine the first timing by comparing the rate of decrease with a predetermined threshold value.

[0057] In the electrolyzed water generating device 1, the decision unit 82 is preferably configured to set the first timing earlier as the rate of decrease in the water level decreases.

[0058] To achieve this configuration, the threshold value may be used, or a table showing the relationship between the rate of decrease in the water level and the first timing may be used. The table may be stored in the memory of the control unit 8, for example.

[0059] 6 shows an example of the table. The table in the figure shows a form in which the rate of decrease in the water level and the first timing have a proportional (linear) relationship. However, the rate of decrease in the water level and the first timing may have a relationship expressed by a curve such as a quadratic function, an exponential function, or a logarithmic function.

[0060] Similarly, in the control method 200 for the electrolyzed water generating device 1, the second step S2 is preferably configured to set the first timing earlier as the rate of decrease becomes smaller.

[0061] Due to hospital operations, the number of hemodialysis patients may temporarily increase, resulting in an increase in the amount of dialysis fluid used. In such cases, the rate at which the water level in the tank 5 decreases increases. Therefore, in the electrolyzed water generating apparatus 1, the determination unit 82 may be configured to set the first timing later as the rate at which the water level decreases increases. Similarly, in the control method 200 for the electrolyzed water generating apparatus 1, the second step S2 may be configured to set the first timing later as the rate at which the water level decreases increases.

[0062] To realize such a configuration, the above threshold value may be used, or a table showing the relationship between the rate of decrease in water level and the first timing may be used.

[0063] FIG. 7 shows the configuration of the water level detection unit 6 together with the tank 5.

[0064] The water level detection unit 6 includes a first sensor 61 for detecting an upper limit value of the water level in the tank 5 and a second sensor 62 for detecting a lower limit value of the water level in the tank 5 .

[0065] The first sensor 61 is disposed at the top of the tank 5. The position of the first sensor 61 is a position set as the upper limit of the water level in the tank 5, but is not limited to the upper end of the tank 5.

[0066] The fresh water production mode M1 in the first cycle in Fig. 3 is executed until the first sensor 61 detects that the electrolyzed water has reached the upper limit of the water level in the tank. When the first sensor 61 detects the electrolyzed water, the control unit 8 shifts the control mode from the fresh water production mode M1 to the standby mode M2 ​​(see Fig. 3). This causes the tank 5 to be filled with electrolyzed water up to its upper limit.

[0067] The second sensor 62 is disposed, for example, at the height of the lower part of the tank 5, although this depends on the specifications of the electrolyzed water generator 1, the capacity of the tank 5, and the specifications of the dialysis solution preparation device 100 connected to the electrolyzed water generator 1. The position of the second sensor 62 is a position set as the lower limit of the water level in the tank 5, but is not limited to the lower end of the tank 5.

[0068] More specifically, the height of the second sensor 62 from the inner bottom surface of the tank 5 is determined taking into consideration the capacity of the tank 5, the specifications of the dialysis solution preparation device 100, and the number of patients being treated simultaneously, so that the electrolyzed water does not run out even if the electrolyzed water in the tank 5 is rapidly consumed.

[0069] In this configuration, the calculation unit 81 can calculate the rate at which the water level in the tank 5 decreases based on the outputs from the first sensor 61 and the second sensor 62. More specifically, the calculation unit 81 can calculate the rate at which the water level in the tank 5 decreases in the standby mode M2 ​​by counting the time from when the first sensor 61 detects the water level to when the second sensor 62 detects the water level.

[0070] The detection by the second sensor 62 that the water level is at the lower limit can be used as a trigger to transition from standby mode M2 ​​to fresh water production mode M1. That is, the determination unit 82 determines the second timing for transitioning from standby mode M2 ​​to fresh water production mode M1 based on the output from the second sensor 62 in standby mode M2. Then, the transition unit 83 transitions the control mode from standby mode M2 ​​to fresh water production mode M1 based on the second timing determined by the determination unit 82. This makes it possible to prevent the electrolyzed water in the tank 5 from running out.

[0071] Fig. 8 is a cross-sectional view of a water level detection unit 6A, which is a modified example of the water level detection unit 6 in Fig. 7. The configuration of the water level detection unit 6 described above can be adopted for parts of the water level detection unit 6A that are not described below.

[0072] The water level detection unit 6A differs from the water level detection unit 6 in that it includes a third sensor 63. The third sensor 63 is a sensor for detecting the water level at an intermediate value between the upper limit and the lower limit. For this reason, the third sensor 63 is disposed at a height between the first sensor 61 and the second sensor 62.

[0073] In this configuration, the calculation unit 81 can calculate the rate at which the water level in the tank 5 is decreasing based on the outputs from the third sensor 63 and the second sensor 62. More specifically, the calculation unit 81 can calculate the rate at which the water level in the tank 5 is decreasing in the latter half of the standby mode M2 ​​(i.e., closer to the present) by counting the time from when the third sensor 63 detects the water level to when the second sensor 62 detects the water level.

[0074] In the water level detection unit 6A shown in FIG. 8, the transition unit 83 can transition the control mode from the fresh water production mode to the standby mode based on the output from the first sensor 61 or the third sensor 63 in the fresh water production mode M1.

[0075] For example, if the rate of decrease in the water level is smaller than the threshold value and the first timing is set early, the transition unit 83 transitions the control mode from the fresh water production mode M1 to the standby mode M2 ​​when the third sensor 63 detects the water level of the electrolyzed water in the fresh water production mode M1 (i.e., when water is produced up to the water level of the third sensor 63). This limits the amount of electrolyzed water stored in the tank 5, shortens the time in the standby state thereafter, and makes it possible to suppress a decrease in the concentration of dissolved hydrogen in the electrolyzed water.

[0076] On the other hand, if the rate of decrease in the water level is greater than the threshold and the first timing is set to be late, the transition unit 83 transitions the control mode from the fresh water production mode M1 to the standby mode M2 ​​when the first sensor 61 detects the water level of the electrolyzed water in the fresh water production mode M1 (i.e., when water is produced up to the water level of the first sensor 61). This makes it possible to prevent the electrolyzed water in the tank 5 from running out.

[0077] Fig. 9 is a cross-sectional view of a water level detection unit 6B, which is a modified example of the water level detection unit 6A in Fig. 8. The configuration of the water level detection unit 6 described above can be adopted for parts of the water level detection unit 6B that are not described below.

[0078] The water level detection unit 6B differs from the water level detection unit 6A in that it includes a plurality of third sensors 63. In the water level detection unit 6B of this embodiment, the third sensors 63 are configured by three third sensors 63a, 63b, and 63c. In the water level detection unit 6B, the number of third sensors 63 is not particularly limited as long as it is two or more.

[0079] The water level detection unit 6B can calculate the rate at which the water level in the tank 5 is decreasing based on the output from any one of the third sensors 63a, 63b, and 63c.

[0080] In this case, it is desirable that the calculation unit 81 calculates the rate of decrease of the water level in the tank 5 based on the outputs from the third sensor 63c at the height closest to the second sensor 62 and the second sensor 62. This allows the calculation unit 81 to calculate the most recent rate of decrease of the water level in the tank 5.

[0081] The water level detector 6B can acquire the electrolyzed water level in stages, which prevents shortages of electrolyzed water used to prepare dialysis fluid, even when multiple people are receiving dialysis treatment at the same time.

[0082] In addition, the calculation unit 81 calculates the rate at which the water level in the tank 5 decreases based on the outputs from the multiple third sensors 63a, 63b, 63c and the second sensor 62, thereby calculating the trend in the rate at which the water level decreases, and the determination unit 82 is able to determine the first timing based on the trend in the change in the rate at which the water level decreases.

[0083] In the water level detection unit 6B shown in Figure 9, the transition unit 83 can transition the control mode from the fresh water production mode M1 to the standby mode M2 ​​based on the output from the first sensor 61 or the third sensors 63a, 63b, 63c in the fresh water production mode M1.

[0084] For example, if the rate at which the water level decreases is extremely slow, the transition unit 83 can transition the control mode from fresh water production mode M1 to standby mode M2 ​​based on the output from the third sensor 63c, thereby reducing the amount of electrolyzed water stored in the tank 5. On the other hand, if the rate at which the water level decreases is somewhat fast, the transition unit 83 can transition the control mode from fresh water production mode M1 to standby mode M2 ​​based on the output from the third sensor 63a, thereby increasing the amount of electrolyzed water stored in the tank 5. In this way, the amount of electrolyzed water stored in the tank 5 can be adjusted in stages depending on the rate at which the water level decreases, i.e., the rate at which the electrolyzed water is consumed, thereby making it possible to further suppress the decrease in the dissolved hydrogen concentration of the electrolyzed water in the standby state.

[0085] In the electrolytic water generating device 1 to which the water level detection unit 6B is applied, the table shown in Figure 6 has a form in which the first timing increases in stages as the rate of decrease increases, and each stage corresponds to the timing at which the output of one of the third sensors 63a, 63b, or 63c is received.

[0086] Fig. 10 is a block diagram showing the configuration of an electrolyzed water generator 1A, which is a modified example of the electrolyzed water generator 1 in Fig. 1. The configuration of the electrolyzed water generator 1 described above can be adopted for parts of the electrolyzed water generator 1A that are not described below.

[0087] In the electrolyzed water generating apparatus 1A, the water level detection unit 6C is provided with a first flow meter 11 for detecting the amount of water flowing out per unit time from the tank 5. In this embodiment, the first flow meter 11 is disposed in the water channel 9 leading from the tank 5 to the dialysis solution preparation device 100, but is not limited to such an arrangement and may be disposed integrally with the tank 5, for example. The first flow meter 11 transmits a signal corresponding to the detected flow rate of water to the control unit 8.

[0088] The control unit 8 stores information about the specifications of the tank 5, particularly the capacity. Therefore, in the electrolyzed water generating device 1A, the calculation unit 81 can calculate the water level in the tank 5 and the rate of decrease thereof based on the signal input from the first flow meter 11. In this configuration, the first sensor 61 to the third sensor 63 shown in Figures 7 to 9 are not required to calculate the rate of decrease of the water level in the tank 5.

[0089] Fig. 11 is a block diagram showing the configuration of an electrolyzed water generator 1B, which is another modified example of the electrolyzed water generator 1 of Fig. 1. The configuration of the electrolyzed water generator 1 described above can be adopted for parts of the electrolyzed water generator 1B that are not described below.

[0090] The electrolyzed water generator 1B further includes a second flow meter 12 for detecting the amount of raw water supplied to the electrolysis unit 3. In this embodiment, the second flow meter 12 is disposed in the water passage between the water supply valve 2 and the electrolysis unit 3, but is not limited to such an arrangement and may, for example, be disposed integrally with the electrolysis unit 3. The second flow meter 12 transmits a signal corresponding to the detected amount of water supply to the controller 8.

[0091] In the electrolytic water generating device 1B, the water level detection unit 6 for detecting the water level in the tank 5 can be a first sensor 61, a second sensor 62, a third sensor 63, 63a, 63b, 63c, as well as a first flow meter 11.

[0092] In the electrolyzed water generating device 1B, the transition unit 83 calculates the water level in the tank 5 based on the output from the second flow meter 12. Then, the transition unit 83 transitions the control mode from the fresh water production mode M1 to the standby mode M2 ​​at a water level corresponding to the first timing determined by the determination unit 82. This makes it possible to adjust the amount of electrolyzed water stored in the tank 5 according to the rate of decrease in the water level, i.e., the rate of consumption of the electrolyzed water, and further suppress the decrease in the dissolved hydrogen concentration of the electrolyzed water in the standby state. Furthermore, since the amount of electrolyzed water stored in the tank 5 in the fresh water production mode M1 can be adjusted continuously, the decrease in the dissolved hydrogen concentration of the electrolyzed water can be suppressed more precisely.

[0093] In the electrolyzed water production device 1B, the first timing is controlled by the amount of raw water supplied to the electrolysis unit 3 in the table shown in FIG.

[0094] In the electrolyzed water generator 1B, the second flow meter 12 may be configured to detect the amount of electrolyzed water supplied from the electrolysis unit 3 to the tank 5. In this case, the second flow meter 12 is disposed, for example, between the electrolysis unit 3 and the tank 5.

[0095] Fig. 12 is a block diagram showing the configuration of an electrolyzed water generator 1C, which is yet another modification of the electrolyzed water generator 1 of Fig. 1. The configuration of the electrolyzed water generator 1 described above, etc., can be adopted for parts of the electrolyzed water generator 1C that are not described below.

[0096] The electrolyzed water generator 1C further includes a timer 13 that counts time. The timer 13 may have a clock function provided in the control unit 8. The timer 13 counts the time during which the water production mode M1 is executed, i.e., the water production time.

[0097] In the electrolyzed water generating device 1C, the water level detection unit 6 for detecting the water level in the tank 5 can be the first sensor 61 or the third sensors 63a, 63b, 63c, or the first flow meter 11.

[0098] A constant supply amount of raw water is supplied to the electrolysis unit 3. In this embodiment, the water supply valve 2 supplies a constant supply amount of raw water to the electrolysis unit 3.

[0099] In the electrolyzed water generator 1C, the amount of water supplied to the electrolysis unit 3 is constant, so the transition unit 83 can calculate the water level in the tank 5 based on the water production time counted by the timer 13. Then, the transition unit 83 transitions the control mode from the fresh water production mode M1 to the standby mode M2 ​​at a water level corresponding to the first timing determined by the determination unit 82. This makes it possible to adjust the amount of electrolyzed water stored in the tank 5 according to the rate of decrease in the water level, i.e., the rate of consumption of the electrolyzed water, and further suppress the decrease in the dissolved hydrogen concentration of the electrolyzed water in the standby state. Furthermore, because the amount of electrolyzed water stored in the tank 5 in the fresh water production mode M1 can be adjusted continuously, the decrease in the dissolved hydrogen concentration of the electrolyzed water can be more precisely suppressed.

[0100] In the electrolyzed water generating device 1C, in the table shown in FIG. 6, the first timing is controlled by the time when the fresh water production mode M1 is executed.

[0101] When the water level detection unit 6A is used as the water level detection unit 6 in the electrolyzed water generators 1B and 1C, the determination unit 82 determines the first timing so that the water level in the tank 5 is equal to or higher than the third sensor 63. This allows the rate of decrease in the water level to be calculated appropriately in the next cycle. Similarly, when the water level detection unit 6B is used as the water level detection unit 6 in the electrolyzed water generators 1B and 1C, the determination unit 82 determines the first timing so that the water level in the tank 5 is equal to or higher than the third sensor 63c.

[0102] The electrolytic water generating device 1 of the present invention has been described in detail above, but the present invention is not limited to the specific embodiment described above and can be modified and implemented in various forms.

[0103] For example, it is desirable that the dialysis solution preparation apparatus 100 be configured to be supplied with electrolyzed water purified by reverse osmosis. Examples of configurations for realizing such a configuration include a system in which a reverse osmosis treatment device including a reverse osmosis membrane module is disposed upstream of the electrolyzed water generator 1 or between the electrolyzed water generator 1 and the dialysis solution preparation apparatus 100, as shown in FIG. 1 . Alternatively, the reverse osmosis treatment device may be incorporated within the electrolyzed water generator 1 (for example, upstream of the electrolysis unit 3, between the electrolysis unit 3 and the tank 5, or downstream of the tank 5). Note that when reverse osmosis-treated water is used as raw water supplied to the electrolyzed water generator 1, the reverse osmosis treatment device described above may be unnecessary.

[0104] [Additional Notes] The present invention includes the following aspects.

[0105] [Invention 1] An electrolyzed water generator comprising: a water supply valve for controlling the supply of raw water; an electrolysis unit for producing electrolyzed water by electrolyzing the raw water supplied from the water supply valve; a tank for storing the electrolyzed water produced by the electrolysis unit; a water level detection unit for detecting the water level in the tank; and a control unit for controlling the water supply valve and the electrolysis unit, wherein the control unit has as control modes a fresh water production mode in which the water supply valve is opened to supply the electrolyzed water produced by the electrolysis unit to the tank; and a standby mode in which the water supply valve is closed to stand by without performing electrolysis in the electrolysis unit, the fresh water production mode and the standby mode being executed alternately and repeatedly, and the control unit comprises: a calculation unit for calculating a rate of decrease of the water level in the tank based on an output from the water level detection unit; a decision unit for deciding a first timing for transitioning from the fresh water production mode to the standby mode in accordance with the rate of decrease; and a transition unit for transitioning the control mode from the fresh water production mode to the standby mode based on the first timing. [Invention 2] The electrolyzed water generator according to Invention 1, wherein the determination unit determines the first timing by comparing the rate of decrease with a predetermined threshold. [Invention 3] The electrolyzed water generator according to Invention 1, wherein the determination unit sets the first timing earlier as the rate of decrease becomes smaller. [Invention 4] The electrolyzed water generator according to Invention 1, wherein the determination unit sets the first timing later as the rate of decrease becomes larger. [Invention 5] The electrolyzed water generator according to any one of Inventions 1 to 4, wherein the water level detection unit includes a first sensor for detecting an upper limit value of the water level and a second sensor for detecting a lower limit value of the water level. [Invention 6] The electrolyzed water generator according to Invention 5, wherein the transition unit transitions the control mode from the standby mode to the fresh water production mode based on an output from the second sensor in the standby mode.[Invention 7] The electrolyzed water generator of Invention 5, wherein the water level detection unit includes a third sensor for detecting the water level at an intermediate value between the upper limit and the lower limit, and the calculation unit calculates the rate of decrease of the water level in the tank based on outputs from the third sensor and the second sensor. [Invention 8] The electrolyzed water generator of Invention 7, wherein the water level detection unit includes a plurality of third sensors, and the calculation unit calculates the rate of decrease of the water level in the tank based on outputs from the third sensor and the second sensor, the third sensor being closest to the second sensor. [Invention 9] The electrolyzed water generator of Invention 7, wherein the transition unit transitions the control mode from the fresh water production mode to the standby mode based on output from the first sensor or the third sensor in the fresh water production mode. [Invention 10] The electrolyzed water generator of any of Inventions 1 to 4, wherein the water level detection unit includes a first flow meter for detecting the amount of water flowing out of the tank, and the calculation unit calculates the rate of decrease of the water level in the tank based on output from the first flow meter. [Invention 11] The electrolyzed water generator according to any one of Inventions 1 to 4, wherein the water level detection unit includes a first sensor for detecting an upper limit value of the water level, a second sensor for detecting a lower limit value of the water level, and a third sensor for detecting the water level at an intermediate value between the upper limit value and the lower limit value, and the transition unit transitions the control mode from the fresh water production mode to the standby mode based on an output from the first sensor or the third sensor in the fresh water production mode. [Invention 12] The electrolyzed water generator according to any one of Inventions 1 to 4, further comprising a second flow meter for detecting the supply amount of the raw water supplied to the electrolysis unit, and the transition unit transitions the control mode from the fresh water production mode to the standby mode based on an output from the second flow meter. [Invention 13] The electrolyzed water generator according to any one of Inventions 1 to 4, wherein the raw water is supplied to the electrolysis unit at a constant supply rate, the electrolysis unit further comprises a timer that counts time, and the transition unit transitions the control mode from the fresh water production mode to the standby mode based on the fresh water production time in the fresh water production mode counted by the timer.[Invention 14] A control method for an electrolyzed water generator, wherein the electrolyzed water generator comprises: a water supply valve for controlling the supply of raw water; an electrolysis unit for producing electrolyzed water by electrolyzing the raw water supplied from the water supply valve; a tank for storing the electrolyzed water produced by the electrolysis unit; a water level detection unit for detecting the water level in the tank; and a control unit for controlling the water supply valve and the electrolysis unit, wherein the control method includes a fresh water production mode in which the water supply valve is opened to supply the electrolyzed water produced by the electrolysis unit to the tank, and a standby mode in which the water supply valve is closed to stand by without performing electrolysis in the electrolysis unit, the fresh water production mode and the standby mode are executed alternately and repeatedly, and the control method includes: a first step of calculating a rate of decrease of the water level in the tank based on an output from the water level detection unit; a second step of determining a first timing for transitioning from the fresh water production mode to the standby mode in accordance with the rate of decrease; and a third step of transitioning from the fresh water production mode to the standby mode based on the first timing. [Invention 15] A control method for an electrolyzed water generator according to Invention 14, wherein the second step determines the first timing by comparing the rate of decrease with a predetermined threshold. [Invention 16] A control method for an electrolyzed water generator according to Invention 15, wherein the second step sets the first timing earlier as the rate of decrease becomes smaller. [Invention 17] A control method for an electrolyzed water generator according to Invention 15, wherein the second step sets the first timing later as the rate of decrease becomes larger. [Invention 18] A control method for an electrolyzed water generator according to any one of Inventions 14 to 17, wherein the water level detection unit includes a first sensor for detecting an upper limit value of the water level and a second sensor for detecting a lower limit value of the water level, and the third step transitions from the standby mode to the fresh water production mode based on an output from the second sensor in the standby mode.

[0106] 1: Electrolyzed water generator 1A: Electrolyzed water generator 1B: Electrolyzed water generator 1C: Electrolyzed water generator 2: Water supply valve 3: Electrolysis unit 5: Tank 6: Water level detection section 6A: Water level detection section 6B: Water level detection section 6C: Water level detection section 8: Control section 11: First flow meter 12: Second flow meter 13: Timer 61: First sensor 62: Second sensor 63: Third sensor 63a: Third sensor 63b: Third sensor 63c: Third sensor 81: Calculation section 82: Determination section 83: Transition section 200: Control method M1: Standby mode M1: Water production mode M2: Standby mode S10: First process S20: Second process S30: Third process

Claims

1. An electrolyzed water generating device comprising: a water supply valve for controlling the supply of raw water; an electrolysis unit for generating electrolyzed water by electrolyzing the raw water supplied from the water supply valve; a tank for storing the electrolyzed water generated by the electrolysis unit; a water level detection unit for detecting the water level in the tank; and a control unit for controlling the water supply valve and the electrolysis unit, wherein the control unit has control modes including a fresh water production mode in which the water supply valve is opened and the electrolyzed water generated by the electrolysis unit is supplied to the tank; and a standby mode in which the water supply valve is closed and the electrolysis unit is on standby without performing electrolysis, the fresh water production mode and the standby mode being executed alternately and repeatedly, and the control unit includes: a calculation unit for calculating a rate at which the water level in the tank decreases based on an output from the water level detection unit; a decision unit for deciding a first timing for transitioning from the fresh water production mode to the standby mode in accordance with the rate of decrease; and a transition unit for transitioning the control mode from the fresh water production mode to the standby mode based on the first timing.

2. The electrolytic water generating device according to claim 1, wherein the determination unit determines the first timing by comparing the rate of decrease with a predetermined threshold value.

3. The electrolytic water generating device according to claim 1, wherein the determination unit sets the first timing earlier as the rate of decrease becomes smaller.

4. The electrolytic water generating device according to claim 1, wherein the determination unit sets the first timing later as the rate of decrease increases.

5. An electrolytic water generating device as described in any one of claims 1 to 4, wherein the water level detection unit includes a first sensor for detecting an upper limit value of the water level and a second sensor for detecting a lower limit value of the water level.

6. The electrolytic water generating device according to claim 5, wherein the transition unit transitions the control mode from the standby mode to the water production mode based on the output from the second sensor in the standby mode.

7. The electrolytic water generating device of claim 5, wherein the water level detection unit includes a third sensor for detecting the water level at an intermediate value between the upper limit value and the lower limit value, and the calculation unit calculates the rate at which the water level in the tank decreases based on outputs from the third sensor and the second sensor.

8. The electrolytic water generating device of claim 7, wherein the water level detection unit includes a plurality of the third sensors, and the calculation unit calculates the rate at which the water level in the tank decreases based on the outputs from the third sensor and the second sensor that is closest in height to the second sensor.

9. The electrolytic water generating device as described in claim 7, wherein the transition unit transitions the control mode from the fresh water production mode to the standby mode based on the output from the first sensor or the third sensor in the fresh water production mode.

10. An electrolytic water generating device as described in any one of claims 1 to 4, wherein the water level detection unit includes a first flow meter for detecting the amount of water flowing out of the tank, and the calculation unit calculates the rate at which the water level in the tank decreases based on the output from the first flow meter.

11. An electrolytic water generating device as described in any one of claims 1 to 4, wherein the water level detection unit includes a first sensor for detecting an upper limit value of the water level, a second sensor for detecting a lower limit value of the water level, and a third sensor for detecting the water level at an intermediate value between the upper limit value and the lower limit value, and the transition unit transitions the control mode from the fresh water production mode to the standby mode based on an output from the first sensor or the third sensor in the fresh water production mode.

12. An electrolytic water generating device as described in any one of claims 1 to 4, further comprising a second flow meter that detects the supply amount of the raw water supplied to the electrolytic unit, and the transition unit transitions the control mode from the water production mode to the standby mode based on the output from the second flow meter.

13. An electrolytic water generating device as described in any one of claims 1 to 4, wherein the electrolytic unit is supplied with the raw water at a constant supply rate, and further comprises a timer that counts time, and the transition unit transitions the control mode from the fresh water production mode to the standby mode based on the fresh water production time in the fresh water production mode counted by the timer.

14. A control method for an electrolyzed water generating apparatus, the electrolyzed water generating apparatus comprising: a water supply valve for controlling the supply of raw water; an electrolysis unit for generating electrolyzed water by electrolyzing the raw water supplied from the water supply valve; a tank for storing the electrolyzed water generated by the electrolysis unit; a water level detection unit for detecting the water level in the tank; and a control unit for controlling the water supply valve and the electrolysis unit, the control method including a fresh water production mode in which the water supply valve is opened to supply the electrolyzed water generated by the electrolysis unit to the tank; and a standby mode in which the water supply valve is closed to wait without performing electrolysis in the electrolysis unit, the fresh water production mode and the standby mode being executed alternately and repeatedly, and including: a first step of calculating a rate at which the water level in the tank decreases based on an output from the water level detection unit; a second step of determining a first timing for transitioning from the fresh water production mode to the standby mode depending on the rate of decrease; and a third step of transitioning from the fresh water production mode to the standby mode based on the first timing.

15. A method for controlling an electrolytic water generating apparatus as described in claim 14, wherein the second step determines the first timing by comparing the rate of decrease with a predetermined threshold value.

16. The method for controlling an electrolytic water generating apparatus as described in claim 15, wherein the second step sets the first timing earlier as the rate of decrease becomes smaller.

17. A method for controlling an electrolytic water generating apparatus as described in claim 15, wherein the second step sets the first timing later as the rate of decrease increases.

18. A method for controlling an electrolytic water generating device as described in any one of claims 14 to 17, wherein the water level detection unit includes a first sensor for detecting an upper limit value of the water level and a second sensor for detecting a lower limit value of the water level, and the third step transitions from the standby mode to the fresh water production mode based on an output from the second sensor in the standby mode.

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