Microbubble generators and plumbing equipment

Abstract

The objective is to provide a microbubble generating device and plumbing equipment capable of efficiently generating microbubbles. [Solution] A microbubble generating device is provided, comprising an electrolytic cell having a water inlet and outlet and electrodes provided inside, and a control unit that generates microbubbles in the electrolytic cell by controlling the supply of current to the electrodes, wherein the control unit supplies current to the electrodes when water is flowing into the electrolytic cell from the inlet and out from the outlet.

Description

TECHNICAL FIELD

[0001] Aspects of the present invention generally relate to a fine bubble generating apparatus and plumbing-related equipment.

BACKGROUND ART

[0002] Electrolyzing water containing chloride ions generates bubbles in the water. In fine bubble generating apparatuses, it is desired to efficiently generate fine bubbles.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0003]

NON-PATENT DOCUMENT 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] The present invention has been made on the basis of recognition of such problems, and an object thereof is to provide a fine bubble generating apparatus and plumbing-related equipment capable of efficiently generating fine bubbles.

MEANS FOR SOLVING THE PROBLEMS

[0005] A first aspect of the invention is a fine bubble generating apparatus comprising: an electrolytic cell having a water inlet and a water outlet and having an electrode disposed therein; and a control unit that generates fine bubbles in the electrolytic cell by controlling energization to the electrode, wherein the control unit energizes the electrode while water flows into the electrolytic cell from the inlet and flows out from the outlet.

[0006] According to this fine bubble generating apparatus, fine bubbles can be efficiently generated by energizing the electrode while water flows inside the electrolytic cell.

[0007] The second invention is a microbubble generating device characterized in that, in the first invention, it further comprises a flow rate adjustment unit for adjusting the flow rate of water in the electrolytic cell.

[0008] This microbubble generator allows the flow velocity in the electrolytic cell to be set to a flow velocity that facilitates the generation of microbubbles in the water.

[0009] The third invention is a microbubble generating device in which, in the second invention, the flow velocity adjustment unit adjusts the water flow velocity between the electrodes to 0.28 meters per second or more when the control unit is energized to the electrodes.

[0010] This microbubble generator makes it easier to generate more microbubbles in water.

[0011] The fourth invention is a microbubble generating device in which, in the third invention, the flow velocity adjustment unit adjusts the average flow velocity of water between the electrodes to 0.28 meters per second or more and 0.84 meters per second or less when the control unit is energized to the electrodes.

[0012] This microbubble generator makes it easier to generate more microbubbles in water.

[0013] The fifth invention is a microbubble generating device characterized in that, in the second invention, the flow rate adjustment unit is a pressure regulating valve located upstream of the electrolytic cell.

[0014] This microbubble generator can suppress fluctuations in the flow rate of water supplied to the electrolytic cell.

[0015] The sixth invention is a microbubble generating device characterized in that, in any one of the first to third inventions, the control unit sets the effective chlorine concentration in the water electrolyzed in the electrolytic cell to 0.1 ppm or more and 5.0 ppm or less.

[0016] According to this fine bubble generator, the number of bubbles can be easily changed by controlling the current of the electrodes. Furthermore, for example, it is possible to satisfy the standards in the WHO Guidelines for Drinking-Water Quality and the standards based on the Water Supply Act.

[0017] A seventh aspect of the invention is the fine bubble generator according to any one of the first to third aspects, wherein the electrolytic cell has an electrode including a base material containing at least one of titanium and a titanium alloy, and a catalyst layer provided on the base material and containing a platinum group element, and the control unit generates water containing the fine bubbles and hypochlorous acid by electrolyzing the water through energization of the electrode.

[0018] According to this fine bubble generator, a bactericidal effect by hypochlorous acid can be obtained.

[0019] An eighth aspect of the invention is a plumbing fixture comprising: the fine bubble generator according to any one of the first to third aspects; and a water discharge unit that discharges water flowing out from the outflow port in a mist form, wherein in the control by the control unit, the bubbles contained in the water electrolyzed in the electrolytic cell are only bubbles having a volume-equivalent diameter smaller than the average particle diameter of the mist-like water discharged by the water discharge unit.

[0020] According to this plumbing fixture, it is expected that the mist-like water discharge from the water discharge unit becoming unstable due to, for example, large bubbles can be suppressed. Effects of the Invention

[0021] According to aspects of the present invention, a fine bubble generator and a plumbing fixture capable of efficiently generating fine bubbles are provided. Brief Description of the Drawings

[0022] [Figure 1] Figure 1 is a block diagram illustrating a plumbing fixture according to an embodiment. [Figure 2] Figures 2(a) to 2(c) are schematic diagrams for explaining a method of evaluating the number of bubbles. [Figure 3]Figure 3 is a schematic diagram for explaining the method for evaluating the number of bubbles. [Figure 4] Figure 4 is a graph illustrating the relationship between effective chlorine concentration and number concentration as an example. [Figure 5] Figure 5 is a graph illustrating the relationship between flow rate and number concentration as an example. [Figure 6] Figure 6 is a histogram illustrating the particle size distribution of bubbles in electrolyzed water as an example. [Figure 7] Figure 7 is a histogram illustrating the particle size distribution of bubbles in electrolyzed water as an example. [Figure 8] Figure 8 is a histogram illustrating the particle size distribution of bubbles in electrolyzed water as an example. [Figure 9] Figure 9 is a histogram illustrating the particle size distribution of bubbles in electrolyzed water as an example. [Figure 10] Figure 10 is a histogram illustrating the particle size distribution of bubbles in electrolyzed water as an example. [Figure 11] Figure 11 is a schematic diagram showing the vicinity of the electrode surface of an electrolytic cell in electrolysis. [Figure 12] Figure 12 is a graph comparing the evaluation methods for bubbles. [Figure 13] Figure 13 is a graph illustrating the particle sizes of bubbles obtained by the image analysis method and the laser diffraction·scattering method as examples. [Figure 14] Figure 14(a) and Figure 14(b) are histograms illustrating the particle size distribution of bubbles in electrolyzed water as examples. [Figure 15] Figure 15(a) and Figure 15(b) are histograms illustrating the particle size distribution of bubbles in electrolyzed water as examples. [Figure 16] Figure 16(a) and Figure 16(b) are histograms illustrating the particle size distribution of bubbles in electrolyzed water as examples. [Figure 17] Figure 17(a) and Figure 17(b) are histograms illustrating the particle size distribution of bubbles in electrolyzed water as examples. [Figure 18] Figure 18(a) and Figure 18(b) are histograms illustrating the particle size distribution of bubbles in electrolyzed water as examples. [Modes for carrying out the invention]

[0023] Embodiments of the present invention will be described below with reference to the drawings. In each drawing, similar components are denoted by the same reference numerals, and detailed descriptions are omitted as appropriate. Figure 1 is a block diagram illustrating a plumbing fixture according to an embodiment. As shown in Figure 1, the plumbing equipment 100 according to this embodiment includes a microbubble generator 20 and a water discharge unit 16. The microbubble generator 20 includes a solenoid valve 12, a flow velocity adjustment unit 13, an electrolytic cell 15, and a control unit 17. The plumbing equipment 100 is a device that generates functional water from water supplied from the upstream side of the stopcock 11 and discharges the generated functional water from the water discharge unit 16.

[0024] Furthermore, the components of the plumbing equipment 100 do not necessarily have to be located within the same enclosure; they may be located separately. For example, the water outlet 16 may be located separately from the housing in which the electrolytic cell 15 is located.

[0025] Specifically, plumbing fixtures include urinals, fixtures installed in bathrooms or bathtubs (such as modular bathrooms), automatic faucets, washbasins, modular kitchens, toilets, or sanitary washing devices installed in toilets.

[0026] The water discharge unit 16 is, for example, a device having a water outlet, and may include a nozzle. For example, cleaning is performed by the water discharged from the water discharge unit 16. For example, if the plumbing fixture 100 is a urinal, the water discharge unit 16 discharges functional water into the urinal as cleaning water to clean the inside of the urinal. For example, if the plumbing fixture 100 is a fixture installed in a bathroom or bathtub, the water discharge unit 16 discharges water onto the washing area floor, etc. The water discharge unit 16 may include a shower head. For example, if the plumbing fixture 100 is a vanity unit, the water discharge unit 16 discharges water onto the bowl. For example, if the plumbing fixture 100 is a system kitchen, the water discharge unit 16 discharges water into the sink. For example, if the plumbing fixture 100 is a toilet unit, the water discharge unit 16 discharges functional water into the toilet as cleaning water to clean the inside of the toilet.

[0027] As shown in Figure 1, in the water flow path 18 discharged from the water outlet 16, the water source (not shown), stopcock 11, solenoid valve 12, flow velocity adjustment unit 13, electrolytic cell 15, and water outlet 16 are arranged in this order from upstream.

[0028] The shut-off valve 11 opens and closes the flow path 18 between the water source and the solenoid valve 12. The shut-off valve 11 switches between supplying water to the solenoid valve 12 and shutting off the water flow. The water source is, for example, tap water. That is, tap water is supplied to the solenoid valve 12, the flow rate adjustment unit 13, and the electrolytic cell 15. Water containing chloride ions is supplied to the solenoid valve 12, the flow rate adjustment unit 13, and the electrolytic cell 15.

[0029] The solenoid valve 12 opens and closes the flow path 18 between the shut-off valve 11 and the flow velocity adjustment unit 13. The solenoid valve 12 switches between supplying water to the flow velocity adjustment unit 13 and the electrolytic cell 15 and shutting off the water flow. Water is supplied to the electrolytic cell 15 from the solenoid valve 12 via the flow velocity adjustment unit 13.

[0030] The electrolytic cell 15 is a device that converts water supplied from upstream into functional water. The functional water produced by the electrolytic cell 15 is water containing microbubbles. The functional water produced by the electrolytic cell 15 may also be water containing microbubbles and having a sterilizing function. For example, the electrolytic cell 15 has a microbubble generation function that generates microbubbles in water, and a sterilizing function generation function that imparts a sterilizing function to water through electrolysis. The sterilizing function generation function is, for example, a function that generates water with a sterilizing function (sterilized water) by electrolyzing tap water. The water discharge unit 16 discharges the functional water produced by the electrolytic cell 15.

[0031] The sterilizing function improves, for example, the chemical cleaning action. The microbubbles improve, for example, the physical cleaning action. By discharging water containing microbubbles and possessing a sterilizing function from the water outlet 16, cleaning performance can be improved by both the sterilizing function and the action of the microbubbles.

[0032] Sterilizing water may contain, for example, a sterilizing component. Specifically, sterilizing water may be ozonated water, hypochlorous acid-containing water, hydrogen peroxide-containing water, or silver ion-containing water.

[0033] For example, water containing chloride ions, such as tap water, is transformed into water containing hypochlorous acid by electrolysis. The electrolytic cell 15 generates hypochlorous acid-containing water by electrolyzing, for example, tap water.

[0034] Alternatively, the electrolytic cell 15 may have electrodes that dissolve bactericidal metal ions (e.g., silver ions) into tap water by electrolyzing the tap water. For example, by applying a voltage between an anode containing silver (or a silver-containing metal) and a cathode, the water flowing between the anode and cathode is electrolyzed, and silver ions are released from the anode into the water.

[0035] The microbubbles generated by the microbubble generation function of the electrolytic cell 15 are bubbles with a volume-equivalent diameter of less than 100 μm. Here, bubbles with a volume-equivalent diameter of less than 100 μm are called fine bubbles (registered trademark; hereinafter omitted). Fine bubbles are classified into microbubbles and ultrafine bubbles (registered trademark; hereinafter omitted). Microbubbles are fine bubbles with a volume-equivalent diameter of 1 μm or more and less than 100 μm. Ultrafine bubbles are fine bubbles with a volume-equivalent diameter of less than 1 μm. The definition of a bubble is as in JIS B 8741-1:2019. The microbubble generation function may generate both microbubbles and ultrafine bubbles.

[0036] In this example, the disinfectant water is hypochlorous acid-containing water. The electrolytic cell 15 has a pair of electrodes. The pair of electrodes are, for example, flat plates arranged parallel to each other and facing each other. The arithmetic mean height Sa (as defined in ISO 25178) of the electrode surfaces is approximately 0.2 μm (0.15 μm or more and 0.25 μm or less) in this example. The electrodes of the electrolytic cell 15 include, for example, a substrate containing at least one of titanium and a titanium alloy, and a catalyst layer provided on the substrate containing a platinum group element. In this example, the catalyst layer is iridium oxide, etc. A voltage is applied between the pair of electrodes to energize the electrodes and electrolyze the tap water flowing between the electrodes. Hypochlorous acid is generated from chloride ions in the tap water. The disinfectant action of hypochlorous acid can improve cleaning performance.

[0037] Furthermore, the microbubble generation function of the electrolytic cell 15 generates microbubbles by electrolyzing water containing chloride ions, such as tap water. For example, the electrolytic cell 15 generates microbubbles in the liquid inside the electrolytic cell 15 by electrolyzing tap water. In the electrolysis that generates hypochlorous acid as described above, gases such as H2 and O2 are generated on the surface of the electrodes. The generated gases separate from the electrodes and become microbubbles in the water.

[0038] Thus, in this example, the electrolytic cell 15 generates sterilized water by electrolyzing tap water and also generates fine bubbles, thereby producing sterilized water containing fine bubbles.

[0039] The control unit 17 is a control circuit that includes, for example, a CPU. The control unit 17 controls the operation of the solenoid valve 12 and the electrolytic cell 15. Specifically, the control unit 17 controls the opening and closing of the solenoid valve 12. The control unit 17 switches between energizing and stopping the energization of the electrodes of the electrolytic cell 15. By controlling the energization of the electrodes of the electrolytic cell 15, the control unit 17 electrolyzes the water in the electrolytic cell 15 to generate fine bubbles in the electrolytic cell 15.

[0040] The electrolytic cell 15 has an inlet 15a through which water flows in from upstream and an outlet 15b through which water flows out downstream from the electrolytic cell 15. The water that flows in from the inlet 15a passes through the electrodes that perform electrolysis to generate hypochlorous acid and fine bubbles, and flows out from the outlet 15b. The control unit 17 controls the solenoid valve 12, etc., to electrolyze the water by applying current to the electrodes of the electrolytic cell 15 when water is flowing in from the inlet 15a and flowing out from the outlet 15b, thereby generating hypochlorous acid and fine bubbles in the water.

[0041] According to the inventors' findings, it has been found that by applying current to the electrodes while water is flowing through the electrolytic cell 15, it is possible to efficiently generate microbubbles. For example, the force from the water flow in the electrolytic cell 15 makes it easier for bubbles generated on the electrode surface of the electrolytic cell 15 to detach from the electrode surface. For example, bubbles detach from the electrode surface before they grow to a diameter of 100 μm or more, becoming microbubbles in the water.

[0042] The flow velocity adjustment unit 13 adjusts the flow velocity of water in the electrolytic cell 15. The flow velocity adjustment unit 13 may also be a flow rate adjustment unit that adjusts the flow rate in the electrolytic cell 15. The flow rate adjustment unit may be a flow rate adjustment valve, such as a throttle valve. The flow velocity adjustment unit 13 may have a flow rate adjustment valve (such as a solenoid valve) that can be controlled by the control unit 17. In addition, the flow velocity adjustment unit 13 may be any device capable of adjusting the flow velocity of water in the electrolytic cell 15 by any method.

[0043] The flow rate adjustment unit 13 adjusts the flow rate between the electrodes (near the electrode surface) of the electrolytic cell 15. For example, by providing the flow rate adjustment unit 13, it is possible to achieve water discharge at an optimal flow rate for generating fine bubbles. In this example, the flow rate adjustment unit 13 is provided upstream of the electrolytic cell 15, but it may also be provided downstream of the electrolytic cell 15.

[0044] The water discharge section 16 sprays (discharges in a mist) water containing fine bubbles and possessing sterilizing properties. Because the sterilizing water containing fine bubbles is discharged in a mist, for example, splashing can be suppressed. The average particle size of the misted water can be, for example, approximately 200 μm to 1500 μm. The average particle size referred to here is the Sauter mean (total volume / total surface area) based on the particle size distribution obtained by the Fraunhoherr analysis method using a He-Ne laser, and is equivalent to the diameter.

[0045] The concentration of the sterilizing component (effective chlorine concentration) in functional water can be adjusted, for example, by the current value applied to the electrodes of the electrolytic cell 15. For example, a higher current value results in a higher effective chlorine concentration. Furthermore, as explained below, by adjusting the flow rate between the electrodes of the electrolytic cell 15 (near the electrode surface) and the effective chlorine concentration in the functional water, the concentration of microbubbles (number of microbubbles per unit volume) and the size of the microbubbles can be adjusted.

[0046] This paper describes how to evaluate the number of bubbles generated by electrolysis in an electrolytic cell. Figures 2(a) to 2(c) and Figure 3 are schematic diagrams illustrating the method for evaluating the number of bubbles. Figure 2(a) is a front view, Figure 2(b) is a side view, and Figure 2(c) is a top view. Although not shown in the diagram, tube 22 is connected to the outlet 15b of the electrolytic cell 15. Electrolysis in the electrolytic cell 15 produces water containing bubbles and hypochlorous acid (electrolyzed water). The electrolyzed water produced in the electrolytic cell 15 is supplied to the water tank 21 via tube 22. Tube 23 has an intake port to draw electrolyzed water from the water tank 21 in order to maintain the water level in the water tank 21.

[0047] A black board 24 is placed inside the water tank 21. The outlet of the tube 22 discharges electrolyzed water between the black board 24 and the wall (front glass) of the water tank 21. A light source 25 is provided below the water tank 21 to illuminate the inside of the water tank 21.

[0048] The camera captures bubbles passing through the gap (1.1 mm) between the black plate 24 and the water tank 21. Specifically, the camera 26 captures the shooting range 29 between the black plate 24 and the wall of the water tank 21 through the wall of the water tank 21. Images of bubbles located within the shooting range 29 can be captured. By analyzing the captured images, the number (concentration) of bubbles in the electrolyzed water is evaluated. Figure 3 is an example of a captured image.

[0049] The more detailed evaluation criteria are as follows: <1.Device configuration> A glass aquarium with internal dimensions of 94mm wide x 140mm high x 61mm deep was used. A black board was prepared by painting the back of a soda-lime glass plate black. This will serve as the background for the photographs. • The blackboard is attached to another smooth board that will serve as the frame for the blackboard. A 0.28mm thick brass plate was used as a spacer and placed between the flat plate of the structure and the glass aquarium. The number of spacers was adjusted so that the gap between the glass aquarium and the black board (unpainted surface) was approximately 1.1 mm. The waterway consisted of a polyurethane tube with an inner diameter of 2.99 mm and a total length of approximately 2800 mm, a small pump, and an electrolytic cell (TOTO part number: TCM1451). • Distilled water was poured into a 5L plastic container, and an amount of sodium chloride corresponding to the desired effective chlorine concentration was dissolved in it. The small pump and electrolytic cell were each powered by a stabilized power supply. The glass aquarium was illuminated from below with a panel light. A digital camera (Olympus Tough TG-6) was used. Camera shooting settings Shooting mode: Microscope mode (macro photography) ISO sensitivity: 12800 Aperture value: F4.5 Focal length: 9mm Photometry method: -2.0, Shutter speed: 160 / 200 / 250 / 320 (*Automatically determined by the camera's specifications based on the subject's brightness) Pixel size: 4000 x 3000 Compression ratio: 1 / 2.7 During filming, the glass aquarium and digital camera setup were covered with a light-blocking cloth to minimize the influence of light other than the panel light. <2. Preparation> • Since generated bubbles can adhere to the glass tank and blackboard and interfere with photography, pre-cleaning is performed. The surface was polished with alumina (2000 grit), cleaned with an alkaline cleaning agent, and then the remaining water was replaced with purified water. This resulted in a highly hydrophilic surface. After cleaning, the black board was fixed in place on the front of the glass aquarium using foam material, clips, and spacers. The spout was secured using foam material and clips. The water outlet was positioned so that it would directly discharge water into the gap between the glass tank and the black board, within the shooting range. The water intake was secured with a clip so that it was located approximately 30 mm from the top edge of the glass aquarium. <3. Shooting conditions> The shooting angle of view is approximately 11.1mm wide x 8.4mm high (calculated value). • Because bubbles would appear in the image when the water was flowing, the water flow was stopped instantaneously and the image was taken immediately. Each condition was photographed three times. <4. Electrolysis> The voltage and current values ​​of the stabilized power supply connected to the small pump were set to achieve the specified flow rate. The voltage and current values ​​of the stabilized power supply connected to the electrolytic cell were set to achieve the specified effective chlorine concentration. The small pump on the intake side, used to maintain the water level, continued to operate with sufficient voltage / current values ​​set to prevent overflow. <5. Image Analysis> We performed image analysis of the captured images using a custom-made program (Python) capable of calculating the number and size of particles. The program imports an image file (4000 x 3000 pixels) in grayscale and converts the pixel information into a numerical sequence. Grayscale is a format that represents brightness levels using values ​​from 0 to 255 (black to white). • Perform binarization with a threshold of 70. The morphological transform is performed twice, closing off the extremely small noisy regions (white) and filling in the defects (black) within the bubble regions. • Regions where two or more bubbles overlap (white) are distinguished as different particles using a watershed algorithm. • Count each bubble particle. By outputting the number of pixels for each bubble particle, the particle diameter can be calculated from its size within the image. • Outputs the number of bubbles and particle size distribution within the image as analysis results. <6. Processing of analysis results> A straight ruler conforming to JIS Class 1 was photographed separately at the same angle of view, and the particle size of the bubbles was calculated by matching the scale. The volume of the imaging area was converted to 1 mL, and the number concentration per 1 mL was calculated.

[0050] Figures 4 to 10 show the evaluation of electrolyzed water using the method described above with respect to Figures 2 to 3. Figure 4 is a graph illustrating the relationship between available chlorine concentration and number concentration. The effective chlorine concentration (ppm (mg / L)) corresponds to the concentration of hypochlorous acid in the electrolyzed water. The effective chlorine concentration was measured using the DPD method. A pocket residual chlorine detector DR300 (manufactured by Toa DTK Co., Ltd.) was used as the measuring instrument, and a free chlorine reagent (manufactured by HACH) was used as the measuring reagent. The number concentration is the number of bubbles in a unit volume of electrolyzed water. Figure 4 shows the results of electrolysis performed with water flowing through the electrolytic cell 15 at flow rates of 200 cc / min, 500 cc / min, and 1000 cc / min. Figure 4 shows the data for effective chlorine concentrations of 0 ppm, 0.3 ppm, 1 ppm, 5 ppm, and 10 ppm.

[0051] As can be seen from Figure 4, the number concentration of bubbles is higher at lower flow rates. Also, when the effective chlorine concentration is greater than 0 ppm but less than or equal to 5.0 ppm, the number concentration of bubbles tends to increase with increasing effective chlorine concentration. On the other hand, when the effective chlorine concentration is greater than 5.0 ppm, the increase in the number concentration in response to an increase in effective chlorine concentration tends to become somewhat slower.

[0052] For example, in one embodiment, the control unit 17 energizes the electrodes of the electrolytic cell 15 so that the effective chlorine concentration in the water electrolyzed in the electrolytic cell 15 is greater than 0 ppm (e.g., 0.1 ppm or more) and 5.0 ppm or less. This makes it easy to change the number of bubbles by controlling the current value of the electrodes, for example. That is, for example, when the effective chlorine concentration is greater than 0 ppm and 5.0 ppm or less, the number of fine bubbles (e.g., microbubbles) in the electrolyzed water changes linearly with respect to the effective chlorine concentration. Furthermore, it is possible to satisfy standards such as those in the WHO drinking water quality guidelines. For example, it is possible to satisfy the standard based on the enforcement regulations of the Waterworks Act, which states that the effective chlorine concentration at the end tap must be 0.1 ppm or more.

[0053] Figure 5 is a graph illustrating the relationship between flow rate and number concentration. Figure 5 shows the cases where the effective chlorine concentration in the electrolyzed water produced in the electrolytic cell 15, through which water was passed at each flow rate, is 3 ppm and 5 ppm.

[0054] At the maximum flow rate of 70 cc / min, the number concentration of bubbles is lowest. The number concentration of bubbles tends to be highest when the flow rate is around 100 cc / min. As the flow rate increases from 100 cc / min, the number concentration of bubbles tends to decrease. It is thought that as the flow rate increases, the electrolysis efficiency decreases and the amount of bubbles per unit volume decreases. The flow rate in the electrolytic cell 15 is preferably between 100 cc / min and 600 cc / min. For example, the microbubble generator 20 produces functional water with a microbubble concentration of 5000 (bubbles / ml) or more, preferably 10000 (bubbles / ml) or more. The microbubble concentration of the functional water may be 35000 (bubbles / ml) or less.

[0055] Figures 6 to 10 are histograms illustrating the distribution of bubble particle sizes in electrolyzed water. The histogram shows the number of bubbles (particles) for every 10 μm of bubble particle diameter. For example, the number of particles at 40 μm on the horizontal axis represents the number of bubbles with a particle diameter greater than 30 μm and less than or equal to 40 μm. Note that particle diameter can be considered to correspond to the diameter equivalent to the volume, assuming a spherical shape.

[0056] Figure 6 shows the case where the flow rate in the electrolytic cell 15 is 70 cc / min. Figure 7 shows the case where the flow rate in the electrolytic cell 15 is 100 cc / min. Figure 8 shows the case where the flow rate in the electrolytic cell 15 is 300 cc / min. Figure 9 shows the case where the flow rate in the electrolytic cell 15 is 500 cc / min. Figure 10 shows the case where the flow rate in the electrolytic cell 15 is 1000 cc / min. The flow velocity between the electrodes of the electrolytic cell 15 can be calculated by dividing the flow rate between the electrodes of the electrolytic cell 15 by the cross-sectional area of ​​the flow path. For example, when the flow rate is 100 cc / min, the flow velocity is calculated to be 0.28 m / s. For example, when the flow rate is 300 cc / min, the flow velocity is calculated to be 0.84 m / s.

[0057] Figures 6 to 10 show the cases where the effective chlorine concentration in the electrolyzed water produced in the electrolytic cell 15, at different flow rates, is 3 ppm and 5 ppm, respectively. The mode diameter is the most frequent value of the particle number.

[0058] As can be seen from Figures 6 and 7, the number of particles increases sharply when the flow rate increases from 70 cc / min to 100 cc / min. For example, a flow rate of 100 cc / min or more is desirable. This allows for the generation of more microbubbles in the water.

[0059] Assuming the total number of particles remains constant, an increase in flow rate would lead to an increase in water volume, thus tending to decrease the number of bubbles per unit volume of water. However, at flow rates of 100 cc / min or higher, the number of particles increases compared to 70 cc / min. Furthermore, as shown in Figure 6, at a flow rate of 70 cc / min, the mode diameter is 50-60 μm (or 60-70 μm), whereas at a flow rate of 100 cc / min or higher, the mode diameter is relatively smaller at 30-40 μm, as shown in Figure 7. Thus, in the range of flow rates less than 100 cc, for example, as the flow rate increases, the mode diameter becomes relatively smaller and the total number of particles increases.

[0060] On the other hand, as shown in Figures 8 to 10, when the flow rate is 100 cc / min or higher (300 cc / min, 500 cc / min, and 1000 cc / min), the mode diameter remains, for example, around 30 to 40 μm. In the range of flow rates above 100 cc / min, a relatively large number of particles, for example, around 30 to 40 μm, can be generated.

[0061] Furthermore, as shown in Figure 5 above, it can be seen that the number concentration decreases when the flow rate exceeds 300 cc / min. For example, a flow rate of 100 cc / min or more and 300 cc / min or less is more desirable. In other words, a flow velocity of 0.28 m / s or more and 0.84 m / s or less is more desirable.

[0062] For example, the flow velocity adjustment unit 13 adjusts the average water flow velocity between the electrodes to 0.28 m / sec or more and 0.84 m / sec or less when the control unit 17 is energizing the electrodes of the electrolytic cell 15. This makes it possible to generate more fine bubbles in the water.

[0063] For example, a pressure regulating valve can be used as the flow velocity adjustment unit 13. As explained with respect to Figure 1, the flow velocity adjustment unit 13 is located upstream of the electrolytic cell 15. By using such a flow velocity adjustment unit 13, fluctuations in the flow velocity of water supplied to the electrolytic cell 15 can be suppressed even if the primary pressure fluctuates. For example, the supply flow velocity to the electrolytic cell 15 can be maintained at a stable predetermined value regardless of fluctuations in the primary pressure. Also, for example, since the primary pressure is applied upstream of the flow velocity adjustment unit 13, damage to the electrolytic cell 15 can be suppressed. However, the flow velocity adjustment unit 13 is not necessarily upstream of the electrolytic cell 15, and may be located downstream of the electrolytic cell 15.

[0064] Figure 11 is a schematic diagram showing the area near the electrode surface of an electrolytic cell during electrolysis. By electrolyzing tap water in the electrolytic cell 15, bubbles 40 are generated on the surface of the electrode 15e. As the bubbles 40 grow larger, they tend to detach from the electrode 15e. For example, bubbles 40 are thought to detach easily from the electrode 15e when their particle size reaches about 40 μm. Furthermore, the detachment of bubbles 40 from the electrode 15e can be adjusted by adjusting the flow rate (flow velocity). For example, if the flow rate (flow velocity) is high, bubbles 40 tend to detach easily from the electrode 15e. For example, it is thought that bubbles 40 stably detach easily from the electrode 15e at a flow velocity of about 0.28 m / sec or higher. The size and concentration of bubbles in the electrolyzed water change depending on the flow velocity. Note that, for example, if bubbles 40 do not detach easily from the electrode 15e or if the growth of bubbles 40 is too fast, bubbles 40 will become larger than fine bubbles, and the number of microbubbles will not increase easily. If the flow rate is too high, the amount of water increases, so the number of bubbles per unit volume of water may decrease.

[0065] For example, in the control system where the control unit 17 controls the electrolytic cell 15 to generate functional water, the bubbles contained in the water electrolyzed in the electrolytic cell 15 (water flowing out from the outlet 15b) only need to be bubbles with a particle size smaller than the average particle size of the mist-like water discharged by the water discharge unit 16. This is expected to suppress the instability of the mist-like water discharged by the water discharge unit 16 caused by, for example, large bubbles.

[0066] Regarding the evaluation method for bubbles, in addition to the evaluation method described above with respect to Figures 2 and 3 (hereinafter referred to as the image analysis method), there is also the laser diffraction and scattering method. The laser diffraction and scattering method is a measurement technique in accordance with ISO standards. A comparison of the measurement methods will be explained with reference to Figures 12 to 18. In both measurement methods, the water flow rate conditions of the electrolytic cell are kept the same, and the electrolyzed water that generates bubbles is evaluated under the same effective chlorine concentration conditions (0 ppm, 0.3 ppm, 1 ppm, 5 ppm, 10 ppm). For the laser diffraction and scattering method, a Shimadzu SALD7500nano is used.

[0067] Figure 12 is a graph comparing different methods for evaluating bubbles. Figure 12 compares the number of microbubbles evaluated by image analysis and by laser diffraction / scattering. The correlation coefficient (R) of the data from the two measurement methods is shown. 2 The correlation was 0.944, indicating a very high correlation. This suggests that the image analysis method is consistent with the trend of number concentrations obtained by the commonly used laser diffraction / scattering method. The image analysis method is considered to have sufficient measurement accuracy.

[0068] Figure 13 is a graph illustrating the particle size of bubbles obtained by image analysis and laser diffraction / scattering methods. Figures 14(a), 15(a), 16(a), 17(a), and 18(a) are histograms illustrating the distribution of bubble particle sizes in electrolyzed water obtained by laser diffraction and scattering methods. Figures 14(b), 15(b), 16(b), 17(b), and 18(b) are histograms illustrating the distribution of bubble particle sizes in electrolyzed water obtained by image analysis.

[0069] Figures 14(a) and 14(b) show the case of electrolyzed water with an effective chlorine concentration of 0.3 ppm, Figures 15(a) and 15(b) show the case of electrolyzed water with an effective chlorine concentration of 1 ppm, Figures 16(a) and 16(b) show the case of electrolyzed water with an effective chlorine concentration of 3 ppm, Figures 17(a) and 17(b) show the case of electrolyzed water with an effective chlorine concentration of 5 ppm, and Figures 18(a) and 18(b) show the case of electrolyzed water with an effective chlorine concentration of 10 ppm. The flow rate of the electrolytic cell is 200 cc / min.

[0070] As can be seen from Figure 13, the mean and median values ​​are approximately 40 μm in all measurement methods. Furthermore, as can be seen from Figures 14(a) to 18(b), the mode diameter (most frequent value) is 30-40 μm in all measurement methods, showing a similar trend. The image analysis method is considered to provide measurement accuracy equivalent to that of the laser diffraction / scattering method.

[0071] The embodiment may include the following configurations. (Composition 1) An electrolytic cell having a water inlet and outlet, and electrodes provided inside, A control unit that generates fine bubbles in the electrolytic cell by controlling the supply of current to the electrodes, Equipped with, The control unit is characterized by energizing the electrodes when water is flowing in from the inlet to the electrolytic cell and out from the outlet. (Configuration 2) The microbubble generating apparatus according to configuration 1, further comprising a flow rate adjustment unit for adjusting the flow rate of water in the electrolytic cell. (Composition 3) The microbubble generating apparatus according to configuration 2, characterized in that the flow velocity adjustment unit adjusts the average flow velocity of water between the electrodes to 0.28 meters per second or more when the control unit is energized to the electrodes. (Composition 4) The microbubble generating apparatus according to configuration 3, characterized in that the flow velocity adjustment unit adjusts the average flow velocity of water between the electrodes to 0.28 meters per second or more and 0.84 meters per second or less when the control unit is energized to the electrodes. (Composition 5) The microbubble generating apparatus according to configuration 2, characterized in that the flow rate adjustment unit is a pressure regulating valve located upstream of the electrolytic cell. (Composition 6) The control unit is characterized in that it sets the effective chlorine concentration in the water electrolyzed in the electrolytic cell to 0.1 ppm or more and 5.0 ppm or less, as described in any one of configurations 1 to 5. (Composition 7) The electrolytic cell has electrodes comprising a substrate containing at least one of titanium and a titanium alloy, and a catalyst layer provided on the substrate containing a platinum group element. The microbubble generating device according to any one of configurations 1 to 6, characterized in that the control unit generates water containing microbubbles and hypochlorous acid by electrolysis of the water by applying current to the electrodes. (Composition 8) A microbubble generator described in any one of configurations 1 to 7, A water discharge unit that discharges water flowing out from the aforementioned outlet in a mist form, Equipped with, In the control of the control unit, the bubbles contained in the water electrolyzed in the electrolytic cell are characterized in that they are only bubbles with a diameter equivalent to their volume smaller than the average particle size of the mist-like water discharged from the water outlet.

[0072] Embodiments of the present invention have been described above. However, the present invention is not limited to these descriptions. Modifications made by those skilled in the art to the above-described embodiments are also included within the scope of the present invention, as long as they retain the features of the present invention. For example, the shape, dimensions, material, arrangement, and installation configuration of each element are not limited to those exemplified and can be modified as appropriate. Furthermore, the elements of each of the embodiments described above can be combined to the extent technically possible, and these combinations are also included within the scope of the present invention insofar as they include the features of the present invention. [Explanation of Symbols]

[0073] 11: Shut-off valve 12: Solenoid valve 13: Flow rate adjustment part 15: Electrolytic cell 15a: Inlet 15b: Outlet 15e: Electrode 16: Water outlet 17: Control Unit 18: Flow Channel 20: Microbubble Generator 21: Aquarium 22, 23: Tube 24: Blackboard 25: Light source 26: Camera 29: Shooting range 40: Bubbles 100: Plumbing fixtures

Claims

1. An electrolytic cell having a water inlet and outlet, and electrodes provided inside, A control unit that generates fine bubbles in the electrolytic cell by controlling the supply of current to the electrodes, Equipped with, The control unit is characterized by energizing the electrodes when water is flowing in from the inlet to the electrolytic cell and out from the outlet.

2. The microbubble generating apparatus according to claim 1, further comprising a flow rate adjustment unit for adjusting the flow rate of water in the electrolytic cell.

3. The microbubble generating apparatus according to claim 2, characterized in that the flow velocity adjustment unit adjusts the average flow velocity of water between the electrodes to 0.28 meters per second or more when the control unit is energized to the electrodes.

4. The microbubble generating apparatus according to claim 3, characterized in that the flow velocity adjustment unit adjusts the average flow velocity of water between the electrodes to 0.28 meters per second or more and 0.84 meters per second or less when the control unit is energized to the electrodes.

5. The microbubble generating apparatus according to claim 2, characterized in that the flow rate adjustment unit is a pressure regulating valve located upstream of the electrolytic cell.

6. The microbubble generating apparatus according to any one of claims 1 to 3, characterized in that the control unit sets the effective chlorine concentration in the water electrolyzed in the electrolytic cell to 0.1 ppm or more and 5.0 ppm or less.

7. The electrolytic cell has electrodes comprising a substrate containing at least one of titanium and a titanium alloy, and a catalyst layer provided on the substrate containing a platinum group element. The microbubble generating apparatus according to any one of claims 1 to 3, characterized in that the control unit generates water containing microbubbles and hypochlorous acid by electrolysis of the water by applying current to the electrodes.

8. A microbubble generating device according to any one of claims 1 to 3, A water discharge unit that discharges water flowing out from the aforementioned outlet in a mist form, Equipped with, In the control of the control unit, the bubbles contained in the water electrolyzed in the electrolytic cell are characterized in that they are only bubbles with a diameter equivalent to their volume smaller than the average particle size of the mist-like water discharged from the water outlet.

Images