Water level and conductivity detection device and method, conductivity detection device and method, hydrogen generator

Abstract

This invention provides a water level and conductivity detection device and method, a conductivity detection device and method, and a hydrogen generator. The water level and conductivity detection device includes a reference electrode (110) inserted into a container containing liquid and one or more detection electrodes. The water level in the container is detected by detecting whether there is continuity between the reference electrode and the one or more detection electrodes. In this water level and conductivity detection device, the one or more detection electrodes include a target detection electrode (111) covered by an insulator. The electrode portion (110a) of the reference electrode, excluding the reference exposed portion (110b) at the lower end of the reference electrode, and the electrode portion (111a) of the target detection electrode, excluding the detection exposed portion (111b) at the lower end of the target detection electrode, are covered by an insulator. The conductivity of the liquid in the container is detected using the reference electrode and the target detection electrode.

Description

[Technical Field]

[0001] This invention relates to a water level and conductivity detection device, a conductivity detection device, a hydrogen generator, a water level and conductivity detection method, and a conductivity detection method. [Previous Technology]

[0002] A water level sensor is used to detect the water level in a container. For example, in a hydrogen generator that produces hydrogen by electrolyzing water through an electrolysis unit, a water level sensor is used to monitor the water level in a container for storing pure water.

[0003] On the other hand, it is sometimes required to detect the conductivity of the liquid inside the container. For example, in the hydrogen generator described above, an increase in the conductivity of the water used for electrolysis will accelerate the deterioration of the electrolysis unit. Therefore, it is sometimes required to monitor conductivity.

[0004] Existing technical documents

[0005] Patent Document 1: Japanese Patent Publication No. 2004-510151

[0006] If the conductivity meter and the water level sensor for detecting the water level are installed separately inside the container, both the water level and conductivity can be detected (see Figure 15; Figure 15 will also be explained later). However, in this method, space needs to be provided inside the container for installing the conductivity meter, and the cost increases accordingly. Furthermore, further research is needed to accurately detect conductivity using the structure of the water level sensor.

[0007] On the other hand, temperature compensation is often required in conductivity detection. Temperature compensation can be performed by installing a temperature sensor inside the container, but there is also a concern that components of the temperature sensor (such as metal ions) may leak into the liquid inside the container. [Summary of the Invention]

[0008] The object of the present invention is to provide a water level and conductivity detection device capable of suppressing the increase in installation space or cost and capable of high-precision detection of water level and conductivity, a hydrogen generator using the water level and conductivity detection device, and a water level and conductivity detection method. Furthermore, the object of the present invention is to provide a conductivity detection device, a hydrogen generator using the conductivity detection device, and a conductivity detection method that help to suppress the aforementioned concerns.

[0009] The water level and conductivity detection device of the present invention includes a reference electrode inserted into a container containing liquid and one or more detection electrodes. The water level in the container is detected by detecting whether there is continuity between the reference electrode and the one or more detection electrodes. In the water level and conductivity detection device, the one or more detection electrodes include an object detection electrode covered by an insulator. The electrode portion of the reference electrode, excluding the reference exposed portion at the lower end of the reference electrode, and the electrode portion of the object detection electrode, excluding the detection exposed portion at the lower end of the object detection electrode, are covered by an insulator. The conductivity of the liquid in the container is detected using the reference electrode and the object detection electrode.

[0010] The conductivity detection device of the present invention detects the conductivity of a liquid in a container, comprising a temperature sensor for measuring the temperature of a measurement object location outside the container, and performing temperature compensation of the detected conductivity based on the measured temperature of the temperature sensor.

[0011] According to the present invention, a water level and conductivity detection device that can suppress the increase in installation space or cost and perform high-precision conductivity detection, a hydrogen generator using the water level and conductivity detection device, and a water level and conductivity detection method can be provided. Furthermore, according to the present invention, a conductivity detection device that helps suppress the aforementioned concerns (the outflow of components of the temperature sensor (metal ions, etc.) into the liquid inside the container), a hydrogen generator using the conductivity detection device, and a conductivity detection method can be provided.

Implementation Method

[0013] Hereinafter, examples of embodiments of the present invention will be specifically described with reference to the accompanying drawings. In the referenced drawings, the same reference numerals are used to label the same parts, and in principle, repeated descriptions related to the same parts are omitted. In addition, in this specification, for the purpose of simplifying the description, the names of the information, signals, physical quantities, or components corresponding to the symbols or reference numerals are sometimes omitted or abbreviated. For example, the reference electrode referred to by "110" (see FIG2) can be described as reference electrode 110, or abbreviated as electrode 110, but these refer to the exact same electrode.

[0014] <<First Embodiment>>

[0015] A first embodiment of the present invention will be described. FIG1 shows an overall structural diagram of the hydrogen generator 1 according to the first embodiment of the present invention. The hydrogen generator 1 generates hydrogen by electrolyzing water using an electrolysis unit. The hydrogen generator 1 includes a housing CS and includes portions referred to by reference numerals 10-14, 20, 30-33, 40-42, 50-59, 60-64, and 70-72. The portions referred to by reference numerals 10-14, 20, 30-33, 40-42, 50-57, and 60-64 are housed inside the housing CS. The portions referred to by reference numerals 58, 59, and 70-72 are mounted on the outer wall of the housing CS.

[0016] Water is contained within the container 10. The container 10 has a cylindrical or prismatic cavity on its inner side as a water containing space 10R, within which water is contained. However, the shape of the water containing space 10R shown here is merely an example, and various modifications can be made to this shape. In this embodiment, the containment of water within the container 10 has the same meaning as the containment of water within the water containing space 10R. The water to be contained in the container 10 is classified as pure water. A supply port 11 is provided at one of the upper ends of the container 10, through which water is supplied to the container 10.

[0017] Electrode unit 12 is installed on container 10. Electrode unit 12 includes a reference electrode that should be inserted into container 10 and one or more detection electrodes (three detection electrodes in the example of Figure 1). The water level (hereinafter referred to as water level) in container 10 can be detected by checking for continuity between the detection electrodes. In addition, the conductivity of the water in container 10 can also be detected using electrode unit 12, the details of which will be described later. An exhaust trap 13 is also installed on container 10.

[0018] The bottom of container 10 is connected to piping 30 via check valve 14. Water in container 10 is supplied to electrolysis unit 20 via check valve 14 and piping 30. Electrolysis unit 20 electrolyzes the water supplied via piping 30. A portion of the oxygen and water generated by electrolysis in electrolysis unit 20 is transported to supply port 11 via piping 31. Another portion of the hydrogen and water generated by electrolysis in electrolysis unit 20 is transported to water separator 40. Water transported to water separator 40 is transported back into container 10 via piping 32 and exhaust gas collector 13. Hydrogen-containing gas transported to water separator 40 is transported to dryer 42 via hydrogen piping 41.

[0019] Hydrogen generated in electrolysis unit 20 and purified in dryer 42 is supplied to hydrogen piping 50. Hydrogen piping 50 is connected to hydrogen piping 51 via water spray preventer 54, and hydrogen piping 51 is connected to one end of hydrogen piping 52 via solenoid valve 55. The other end of hydrogen piping 52 is connected to hydrogen generation port 58. Solenoid valve 55 is controlled to be open or closed by control display unit 60. Only when solenoid valve 55 is open, hydrogen in hydrogen piping 51 is supplied to hydrogen piping 52, and as a result, hydrogen generated in electrolysis unit 20 is output from hydrogen generation port 58.

[0020] Furthermore, hydrogen piping 50 is connected to one end of hydrogen piping 53 via safety valve 56, and the other end of hydrogen piping 53 is connected to hydrogen release port 59. When the pressure in hydrogen piping 50 exceeds a predetermined value, safety valve 56 connects hydrogen piping 50 to hydrogen piping 53, releasing the hydrogen in hydrogen piping 50 from hydrogen release port 59. Pressure sensor 57 detects the pressure of hydrogen in hydrogen piping 50. Additionally, the hydrogen in each hydrogen piping is gaseous hydrogen (hydrogen gas).

[0021] A power supply voltage VPOW is input from outside the hydrogen generator 1 to the power port 71. The power supply voltage VPOW is, for example, commercial AC voltage. The control display unit 60 is connected to the power port 71 and is driven based on the power supply voltage VPOW. The control display unit 60 controls the overall operation of the hydrogen generator 1. The control display unit 60 includes a power supply circuit that supplies the internal power supply voltage required for the operation of each component of the hydrogen generator 1 based on the power supply voltage VPOW. The electrolysis unit power supply circuit 61, built into the control unit 60, supplies a fixed current to the electrolysis unit 20. The electrolysis unit 20 performs water electrolysis based on the supplied current. The electrolysis unit 20 is composed of a solid polymer membrane.

[0022] The control display unit 60 also includes a display unit 62, an alarm output unit 63, and a water level / conductivity detection circuit 64. The control display unit 60 is connected to a signal port 70. An external device (not shown) can be connected to the external device via the signal port 70, allowing for the transmission and reception of various signals between the control display unit 60 and the external device.

[0023] The display unit 62 is composed of light-emitting diodes or the like. A display screen composed of a liquid crystal display panel or the like may also be provided on the display unit 62.

[0024] The alarm output unit 63 outputs various alarms. The alarm output unit 63 outputs a water level alarm when the water level in the container 10 is below a predetermined lower limit (equivalent to a water level within the range WL0 described later; see Figure 3). The alarm output unit 63 outputs a pressure alarm when the pressure detected by the pressure sensor 57 deviates from a predetermined normal pressure range. The alarm output unit 63 outputs a unit alarm when an abnormality is detected in the unit voltage supplied to the electrolysis unit 20. The output of any alarm includes a predetermined alarm display on the display unit 62 and the transmission of an alarm signal via the signal port 70. The alarm signal is transmitted to an external device via the signal port 70.

[0025] The water level / conductivity detection circuit 64 (hereinafter referred to as the detection circuit 64) cooperates with the electrode unit 12 to detect the water level in the container 10. Therefore, the detection circuit 64 and the electrode unit 12 form a water level sensor. In addition, the detection circuit 64 also cooperates with the electrode unit 12 to detect the conductivity of the water in the container 10. Therefore, it can also be said that the detection circuit 64 and the electrode unit 12 form a water level sensor with conductivity detection function (water level and conductivity detection device).

[0026] The control display unit 60 enables the display unit 62 to display the unit voltage or the pressure detected by the pressure sensor 57. The control display unit 60 can also enable the display unit 62 to display the water level and conductivity detected by the detection circuit 64.

[0027] Furthermore, the control display unit 60 can also send a water replenishment request signal to an external device via the signal port 70 when the water level in the container 10 is lower than a predetermined lower limit water level. Additionally, when a predetermined emergency stop command signal is input to the control display unit 60 from an external device via the signal port 70, the control display unit 60 causes the electrolysis unit 20 to stop producing hydrogen (hydrogen gas) and stops outputting hydrogen from the hydrogen generation port 58 by switching the solenoid valve 55 to the closed state.

[0028] In addition, if necessary, the water in container 10 can also be discharged to the outside through drain pipe 33 and drain outlet 72.

[0029] Figure 2 is a simplified perspective view of the electrode unit 12. Figure 3 briefly shows the positional relationship between the container 10 and the electrode unit 12 when viewed from the side. Additionally, the supply port 11 and the exhaust trap 13 are omitted from Figure 3. The bottom surface of the container 10 is referred to as "10B" in the attached drawing. The bottom surface 10B corresponds to the bottom surface of the water containing space 10R of the container 10. The shape of the bottom surface 10B when viewed vertically is, for example, circular or polygonal.

[0030] The electrode unit 12 includes a reference electrode 110, detection electrodes 111 to 113 and an electrode support 120. The upper end of the reference electrode 110 and the upper ends of each of the detection electrodes 111 to 113 are supported by the electrode support 120.

[0031] By inserting the electrode support 120 into the electrode support receiving port (not shown) provided on the upper surface of the container 10 and fixing the electrode support 120 in the electrode support receiving port, the electrode unit 12 is fixed in a predetermined position in the container 10. However, the electrode unit 12 can be attached to and detached from the container 10. In this embodiment, unless otherwise specified, the electrode unit 12 is fixed in a predetermined position in the container 10, and the hydrogen generator 1 is arranged with its bottom surface 10B parallel to the horizontal plane. In addition, the electrodes 110 to 113 in the electrode support 120 may also be arranged concentrically around an axis parallel to the vertical direction (this is briefly shown in FIG. 2). However, the electrodes 110 to 113 in the electrode support 120 may also be arranged in a row in the horizontal direction. In some of the accompanying drawings (e.g., FIG. 3), the electrodes 110 to 113 are shown arranged in the horizontal direction.

[0032] The reference electrode 110 and the detection electrodes 111-113 are rod-shaped electrodes extending downward from the electrode support 120 and inserted into the container 10. The electrode support 120 supports the upper ends of the reference electrode 110 and the detection electrodes 111-113 insulated from each other. Furthermore, a wiring assembly 130 for electrically connecting the reference electrode 110 and the detection electrodes 111-113 to the detection circuit 64 is provided in the electrode unit 12. The wiring assembly 130 extends out as a cable from the upper part of the electrode support 120.

[0033] The electrode support 120 has a generally cylindrical shape with height in the vertical direction, and its lower surface 120B is parallel to the horizontal plane. The reference electrode 110 and detection electrodes 111-113 protrude downwards from the lower surface 120B of the electrode support 120. When comparing the lengths of the reference electrode 110 and the detection electrodes 111-113 protruding from the lower surface 120B of the electrode support 120, their lengths are different from each other. Among these lengths, the reference electrode 110 is the longest, the detection electrode 111 is the second longest, the detection electrode 112 is the third longest, and the detection electrode 113 is the shortest. Therefore, "d0 < d1 < d2 < d3" holds true. Here, d0, d1, d2, and d3 represent the distances from the bottom surface 10B to the lower end of the reference electrode 110, to the lower end of the detection electrode 111, to the lower end of the detection electrode 112, and to the lower end of the detection electrode 113, respectively. Therefore, the lower end of the reference electrode 110 is closer to the bottom surface 10B than the lower ends of each detection electrode.

[0034] The reference electrode 110 and the detection electrodes 111-113 are made of titanium and are rod-shaped electrodes with the same cross-sectional area. In this embodiment, the shape of each cross-section (the cross-section parallel to the horizontal plane) of the reference electrode 110 and the detection electrodes 111-113 is a circle with a diameter of 1.4 mm. Furthermore, in this embodiment, the lengths of the reference electrode 110, the detection electrodes 111, 112, and 113 protruding from the lower surface 120B of the electrode support 120 are 13 cm, 12 cm, 9 cm, and 5 cm, respectively. However, the shape, size, and length of each cross-section of the reference electrode 110 and the detection electrodes 111-113 can be varied.

[0035] Referring to Figure 3, the water level sensor, composed of electrode unit 12 and detection circuit 64, detects which of the water level ranges WL0, WL1, WL2, and WL3 the water level in container 10 belongs to. This detection is achieved by detecting whether the reference electrode 110 and the detection electrodes 111-113 are conductive. The state in which any two electrodes are conductive is called the conductive state, and the state in which any two electrodes are not conductive is called the non-conductive state.

[0036] Regarding the detection electrode of interest, which is any one of the detection electrodes 111 to 113, the conductive state between the reference electrode 110 and the detection electrode of interest refers to the state where the resistance between the reference electrode 110 and the detection electrode of interest is below a predetermined reference resistance value, and the non-conductive state between the reference electrode 110 and the detection electrode of interest refers to the state where the resistance between the reference electrode 110 and the detection electrode of interest exceeds the predetermined reference resistance value. The conductive state between the reference electrode 110 and the detection electrode of interest is achieved by electrically connecting the reference electrode 110 and the detection electrode of interest through water in the container 10.

[0037] The water level in container 10 refers to the height of the water surface inside container 10 as observed from the bottom surface 10B. Water level range WL3 is the range where the water surface height is above distance d3. Water level range WL2 is the range where the water surface height is above distance d2 and below distance d3. Water level range WL1 is the range where the water surface height is above distance d1 and below distance d2. Water level range WL0 is the range where the water surface height is below distance d1.

[0038] When the water level in container 10 is within the water level range WL3, a portion of the reference electrode 110 and a portion of the detection electrode 113 are immersed in the water, thereby making electrodes 110 and 113 conductive through the water. When the water level in container 10 is within the water level range WL2, the detection electrode 113 is not in contact with the water, thus making electrodes 110 and 113 non-conductive. On the other hand, a portion of the reference electrode 110 and a portion of the detection electrode 112 are immersed in the water, thereby making electrodes 110 and 112 conductive through the water. When the water level in container 10 is within the water level range WL1, the detection electrodes 112 and 113 are not in contact with the water, thus making electrodes 110 and 112, as well as electrodes 110 and 113, non-conductive. On the other hand, a portion of the reference electrode 110 and a portion of the detection electrode 111 are immersed in the water, thus making electrodes 110 and 111 conductive through the water. When the water level in container 10 is within the water level range WL0, the detection electrodes 111 to 113 are not in contact with the water, so the reference electrode 110 and the detection electrodes 111 to 113 are in a non-conductive state.

[0039] Therefore, the detection circuit 64 can detect the water level in four stages by detecting whether there is continuity between the reference electrode 110 and each of the detection electrodes 111-113. That is, when there is continuity between electrodes 110 and 113, the detection circuit 64 determines that the water level is in the water level range WL3. When there is no continuity between electrodes 110 and 113 and there is continuity between electrodes 110 and 112, the detection circuit 64 determines that the water level is in the water level range WL2. When there is no continuity between electrodes 110 and 112 and there is continuity between electrodes 110 and 111, the detection circuit 64 determines that the water level is in the water level range WL1. When there is no continuity between electrodes 110 and 111, the detection circuit 64 determines that the water level is in the water level range WL0. Thus, the water level sensor can detect whether the water level is higher than the height of the lower end of each detection electrode.

[0040] In most hydrogen generators that utilize the electrolysis of water to produce hydrogen, water level detection is performed to ensure proper water replenishment. On the other hand, if the conductivity of the water supplied to the electrolysis unit (electrolysis unit 20 in hydrogen generator 1) is high, it will accelerate the deterioration of the electrolysis unit, and the electrolysis unit may fail due to the short-term impact of high conductivity. Therefore, it is generally required to detect the conductivity of the water as well.

[0041] To detect conductivity, as shown in FIG15, a reference method in which a conductivity meter is installed separately from the water level sensor was also investigated. In the reference method of FIG15, the conductivity meter is installed separately from the electrode unit forming the water level sensor inside the container. However, in the reference method, space is required inside the container for installing the conductivity meter, and the cost increases accordingly.

[0042] Considering these factors, in this embodiment, a water level sensor structure is used to achieve both water level detection and conductivity detection. To investigate the structure for effectively detecting water level and conductivity, the following first, second, and third experiments were conducted. In this embodiment, actually, a portion of the reference electrode 110 and the detection electrode 111 are covered by an insulator. However, in the first experiment, a comparative structure was used in which the entire reference electrode 110 and detection electrode 111 protruded from the electrode support 120 without being covered by an insulator.

[0043] In each experiment, various types of water with known conductivity were prepared. With a portion of the reference electrode 110 and the detection electrode 111 in contact with the water, the conductivity of the water between the reference electrode 110 and the detection electrode 111 was measured using an experimental conductivity meter. The experimental conductivity meter was a conductivity meter prepared for the experiment.

[0044] Figure 4 shows the results of the first experiment. In the graph of Figure 4, the horizontal axis can be understood as corresponding to the conductivity of the water in container 10, and the conductivity on the horizontal axis represents the true conductivity of the water in container 10 (the same applies to the graphs in Figures 6A, 6B, 6C, 8A, 8B, and 8C described later). In the first experiment, an experimental conductivity meter was connected to a reference electrode 110 and a detection electrode 111, which adopted a comparison structure, and the output value of the experimental conductivity meter was read. The output value of the experimental conductivity meter is proportional to the magnitude of the current flowing between electrodes 110 and 111 when a specified AC voltage is applied between electrodes 110 and 111. Here, for convenience, the output value of the experimental conductivity meter is referred to as the reference detection conductivity. In each experiment, the calibration of the experimental conductivity meter was insufficient; therefore, the reference detection conductivity does not represent the true conductivity. However, the linearity of the experimental conductivity meter is sufficiently high. That is, in each experiment, when the conductivity of water is set to k times, the reference detection conductivity also has a sufficiently high accuracy of k times (k is any positive value).

[0045] Here, the distance from the lower end of the reference electrode 110 to the water surface inside the container 10 is called the distance DW. In the graph of Figure 4, the plot represented by black dots shows the relationship between the actual conductivity at a distance DW of 10 cm and the reference conductivity of the comparative structure. In the graph of Figure 4, the plot represented by hollow triangles shows the relationship between the actual conductivity at a distance DW of 6 cm and the reference conductivity of the comparative structure. In the graph of Figure 4, the plot represented by hollow quadrilaterals shows the relationship between the actual conductivity at a distance DW of 3 cm and the reference conductivity of the comparative structure.

[0046] In the comparative structure, it can be seen that although linearity is obtained at each water level, the reference detection conductivity varies with the water level. This is because the electrode area in contact with the water changes due to the change in water level. The detection conductivity of the conductivity meter depends on a constant (called the unit constant) determined by the electrode area in contact with the water and the distance between the electrodes. Therefore, if the electrode area changes with the water level, the detection conductivity (here, the reference detection conductivity) also changes. For example, in the case of using the comparative structure, compared with a distance DW of 3 cm, if the distance DW is set to 6 cm, the contact area between the reference electrode 110 and the water and the contact area between the detection electrode 111 and the water are approximately twice as large. As a result, the obtained reference detection conductivity is also approximately twice as large.

[0047] It is evident that if a comparative structure is used, it is difficult to detect accurate conductivity. Therefore, in the second and third experiments, a covering structure was adopted in which a portion of the reference electrode 110 and the detection electrode 111 protruding from the electrode support 120 are covered by an insulator.

[0048] Referring to FIG5, the structure of the reference electrode 110 and the detection electrode 111 of the covering structure will be described. In the hydrogen generator 1 of this embodiment, in reality, a portion of each of the detection electrodes 112 and 113 may also be covered by an insulator, but FIG5 shows the covering structure that is only related to the reference electrode 110 and the detection electrode 111.

[0049] The electrode portion (made of titanium) of the reference electrode 110 protruding from the electrode support 120 is composed of a cover portion 110a and an exposed portion 110b. The exposed portion 110b is the electrode portion of the reference electrode 110 that includes the lower end of the reference electrode 110. The cover portion 110a is the electrode portion of the reference electrode 110 that extends from the lower surface 120B of the electrode support 120 to the exposed portion 110b. The cover portion 110a is covered by an insulator. Therefore, the electrode portion in the cover portion 110a is independent of the water level and does not come into contact with the water in the container 10, and does not function as an electrode in practice. In the cover structure, there is no gap between the lower surface 120B of the electrode support 120 and the cover portion 110a, and the electrode portion of the reference electrode 110 that extends from the lower surface 120B of the electrode support 120 to the exposed portion 110b can be completely covered by an insulator. On the other hand, the exposed portion 110b is not covered by an insulator, and the electrode portion in the exposed portion 110b is exposed relative to the water containing space 10R. Therefore, if the water level is above the distance d0, the electrode portion in the exposed portion 110b comes into contact with the water in the container 10.

[0050] The electrode portion (made of titanium) of the detection electrode 111 protruding from the electrode support 120 consists of a cover portion 111a and an exposed portion 111b. The exposed portion 111b is the electrode portion of the detection electrode 111 that includes the lower end of the detection electrode 111. The cover portion 111a is the electrode portion of the detection electrode 111 that extends from the lower surface 120B of the electrode support 120 to the exposed portion 111b. The cover portion 111a is covered by an insulator. Therefore, the electrode portion in the cover portion 111a is independent of the water level, does not come into contact with the water in the container 10, and does not function as an electrode in practice. In the cover structure, there is no gap between the lower surface 120B of the electrode support 120 and the cover portion 111a, and the electrode portion of the detection electrode 111 that extends from the lower surface 120B of the electrode support 120 to the exposed portion 111b can be completely covered by an insulator. On the other hand, the exposed portion 111b is not covered by an insulator, and the electrode portion in the exposed portion 111b is exposed relative to the water containing space 10R. Therefore, if the water level is above the distance d1, the electrode portion in the exposed portion 111b comes into contact with the water in the container 10.

[0051] The length of the exposed portion 110b of the reference electrode 110 in the vertical direction is referred to by the symbol "Lb110". The length of the exposed portion 111b of the detection electrode 111 in the vertical direction is referred to by the symbol "Lb111". In the vertical direction, the length Lb110 of the exposed portion 110b is sufficiently shorter than the length of the covering portion 110a, and the length Lb111 of the exposed portion 111b is sufficiently shorter than the length of the covering portion 111a. The lengths Lb110 and Lb111 are substantially the same, but modifications that make them different are also possible.

[0052] The insulators in the cover portions 110a and 111a have sufficiently high resistivity to avoid affecting the detection of water level and conductivity. For example, heat-shrinkable tubes formed of silicone rubber or fluoropolymer resin can be used as insulators. In the second and third experiments, heat-shrinkable tubes were used as insulators. However, the insulators in the cover portions 110a and 111a can also be in the form of insulating tubes. Alternatively, for example, the cover portion 110a can be formed by coating a portion of the reference electrode 110 with an insulator (the same applies to the detection electrode 111).

[0053] In the second experiment, the lengths Lb110 and Lb111 were set to approximately 2 mm. Figures 6A, 6B, and 6C show the results of the second experiment. In the second experiment, an experimental conductivity meter was connected to a reference electrode 110 and a detection electrode 111, which employed a covered structure (where the lengths Lb110 and Lb111 are approximately 2 mm), and the output value of the experimental conductivity meter was read as a reference detected conductivity. In the graph of Figure 6A, the plot represented by black dots shows the relationship between the actual conductivity at a distance of 10 cm from DW and the reference detected conductivity of the second experiment. In the graph of Figure 6B, the plot represented by hollow triangles shows the relationship between the actual conductivity at a distance of 6 cm from DW and the reference detected conductivity of the second experiment. In the graph of Figure 6C, the plot represented by hollow quadrilaterals shows the relationship between the actual conductivity at a distance of 3 cm from DW and the reference detected conductivity of the second experiment.

[0054] When the plots shown in Figures 6A, 6B, and 6C are represented as single curves, the groups of plots represented by black dots, hollow triangles, and hollow quadrilaterals overlap and are indistinguishable. Therefore, they are represented by their respective curves. This indicates that the reference conductivity of the second experiment is completely or almost independent of the water level. Although it is not clear from Figures 6A, 6B, and 6C, the error in the reference conductivity due to the water level in the second experiment is about 1%. That is, in the second experiment, when water with a certain conductivity is used, the first reference conductivity at a distance of 10 cm from DW, the second reference conductivity at a distance of 6 cm from DW, and the third reference conductivity at a distance of 3 cm from DW are obtained by actual measurement, and the absolute value of the difference between the obtained conductivity is calculated. The calculated absolute value is about 1% or less of the value of the first, second, or third reference conductivity.

[0055] When a covering structure is used, the area of ​​the portion of the electrode part of the reference electrode 110 that is in contact with water, i.e., the surface area of ​​the exposed portion 110b, is fixed regardless of the water level (provided that the water level is (d0 + Lb110) or higher). When a covering structure is used, the area of ​​the portion of the electrode part of the detection electrode 111 that is in contact with water, i.e., the surface area of ​​the exposed portion 111b, is fixed regardless of the water level (provided that the water level is (d1 + Lb111) or higher). Therefore, when the exposed portions 110b and 111b are in contact with water as a whole (i.e., when the water level is (d1 + Lb111) or higher), the reference detection conductivity is independent of the water level.

[0056] Furthermore, in the coverage structure of the second experiment, the reference detection conductivity exhibits good linearity over a wide conductivity range. That is, in the coverage structure of the second experiment, the actual conductivity is proportional to the reference detection conductivity over a wide conductivity range.

[0057] In the third experiment, the lengths Lb110 and Lb111 were essentially set to 0 mm. In this case, as shown in FIG7A, the exposed portion 110b is composed only of the lower surface of the reference electrode 110, and as shown in FIG7B, the exposed portion 111b is composed only of the lower surface of the detection electrode 111.

[0058] Figures 8A, 8B, and 8C show the results of the third experiment. In the third experiment, an experimental conductivity meter was connected to a reference electrode 110 and a detection electrode 111, which employed a covered structure (where lengths Lb110 and Lb111 are essentially 0 mm), and the output value of the experimental conductivity meter was read as the reference detected conductivity. In the graph of Figure 8A, the plot represented by black dots shows the relationship between the actual conductivity at a distance of 10 cm from DW and the reference detected conductivity of the third experiment. In the graph of Figure 8B, the plot represented by hollow triangles shows the relationship between the actual conductivity at a distance of 6 cm from DW and the reference detected conductivity of the third experiment. In the graph of Figure 8C, the plot represented by hollow quadrilaterals shows the relationship between the actual conductivity at a distance of 3 cm from DW and the reference detected conductivity of the third experiment.

[0059] When the plots shown in Figures 8A, 8B, and 8C are represented as single curves, the groups of plots represented by black dots, hollow triangles, and hollow quadrilaterals overlap and are indistinguishable. Therefore, they are represented by different curves. This indicates that the reference conductivity of the third experiment is completely or almost independent of the water level.

[0060] However, in the coverage structure of the third experiment, the linearity of the reference detection conductivity is disrupted. In particular, in the coverage structure of the third experiment, the proportional relationship between the true conductivity and the reference detection conductivity is disrupted in the higher conductivity range.

[0061] Therefore, it is preferable that the lengths Lb110 and Lb111 are greater than zero, that is, that the exposed portions 110b and 111b have length in the vertical direction. However, if the lengths Lb110 and Lb111 are too large, the change in the unit constant caused by the water level will be too large to be ignored. Taking these factors into consideration, it is preferable that the lengths Lb110 and Lb111 are greater than 0 and less than a specified length. Referring to experimental results, it is preferable that the lengths Lb110 and Lb111 are set to a length in the range of 2 mm to 3 mm, but the lengths Lb110 and Lb111 can also be less than 2 mm (for example, 1 mm) or slightly more than 3 mm. For example, the specified lengths can be 5 mm or 10 mm. If the lengths Lb110 and Lb111 are set to be greater than 0 and less than 10 mm, it can be considered that there will be no major problems with the accuracy of conductivity detection. Alternatively, in the vertical direction, the ratio of length Lb110 to the total length of the covering portion 110a and the exposed portion 110b, and the ratio of length Lb111 to the total length of the covering portion 111a and the exposed portion 111b, may be greater than 0 and less than a specified value (e.g., less than 5% or less or less than 3%).

[0062] In addition, to prevent false water level detection caused by condensation, a reference structure was studied in which only a very small portion of the upper side of the reference electrode and a very small portion of the upper side of the detection electrode are covered by an insulator. However, even when conductivity measurement was attempted with this reference structure, it was difficult to obtain the desired linearity. At least in the vertical direction, by making the length Lb110 of the exposed portion 110b of the reference electrode 110 shorter than the length of the covered portion 110a, and by making the length Lb111 of the exposed portion 111b of the detection electrode 111 shorter than the length of the covered portion 111a, a certain degree of linearity can be ensured (superior linearity than the above-mentioned reference structure can be obtained).

[0063] Here, the behavior related to the lengths Lb110 and Lb111 is examined. Figure 9 briefly shows the current line distribution when a voltage is applied between electrodes 110 and 111, given that the lengths Lb110 and Lb111 have corresponding sizes (e.g., 2 mm). In the state of Figure 9, a portion of the side surface of the exposed portion 110b and a portion of the side surface of the exposed portion 111b are opposite each other. Therefore, when a voltage is applied between electrodes 110 and 111, the path connecting the exposed portions 110b and 111b with the shortest distance is dominant as the current path. In reality, there are also curved current paths, but in the state of Figure 9, the current line distribution between electrodes 110 and 111 remains fixed or easily remains fixed regardless of the conductivity of water. Therefore, in the state of Figure 9, a high linearity can be obtained with respect to conductivity measurements. In addition, as technical information related to the current line distribution in conductivity measurement, the following can be cited: non-patent literature "Explanation of General Rules for Conductivity Titration", [online], [searched on September 9, 2021 (Reiwa 3)], Internet <URL: https: / / www.jstage.jst.go.jp / article / revpolarography1955 / 10 / 3 / 10_3_102 / _pdf>.

[0064] Figure 10 briefly illustrates the current line distribution when a voltage is applied between electrodes 110 and 111 with lengths Lb110 and Lb111 being zero. In the state shown in Figure 10, the exposed portions 110b and 111b do not have opposing electrode portions. Therefore, in the state shown in Figure 10, when a voltage is applied between electrodes 110 and 111, the current flows along a curved path between the exposed portion 110b, corresponding to the lower surface of the reference electrode 110, and the exposed portion 111b, corresponding to the lower surface of the detection electrode 111. That is, it can be considered that in the state shown in Figure 10, a linear current distribution for which Ohm's law holds is not formed, and the current line distribution varies depending on the conductivity of water, thus the linearity associated with conductivity measurement is easily disrupted.

[0065] In this embodiment, unless otherwise specified, the reference electrode 110 and the detection electrode 111 adopt the above-described covering structure, and the lengths Lb110 and Lb111 are set to be within the range of 2 mm to 3 mm.

[0066] The following embodiments EX1_1 to EX1_6 belong to the first embodiment. In embodiments EX1_1 to EX1_6, some specific structural examples, operational examples, application technologies, and modification technologies related to the hydrogen generator 1 (especially the water level sensor) are described. In this embodiment, the above matters apply to the following embodiments unless otherwise specifically described and are not contradictory. In each embodiment, if there are matters that contradict the above matters, the description in each embodiment may take precedence. Furthermore, as long as there is no contradiction, the matters described in any of the several embodiments shown below may be applied to any other embodiment (that is, any two or more embodiments of the several embodiments may be combined).

[0067] [Example EX1_1]

[0068] Embodiment EX1_1 will be described. FIG11 shows the internal configuration of the detection circuit 64 of Embodiment EX1_1. However, FIG11 only shows the configuration of the detection circuit 64 related to electrodes 110 and 111 (the same is true in FIG13 described later).

[0069] In the configuration of FIG11, the detection circuit 64 includes: AC voltage source 210, IV conversion unit 220, water level judgment unit 230 and conductivity conversion unit 240.

[0070] The AC voltage source 210 generates and outputs an AC voltage VAC with a specified frequency. The AC voltage VAC is supplied between the reference electrode 110 and the detection electrode 111. The frequency of the AC voltage VAC is set, for example, to a frequency in the range of several tens of Hz to several megaHz. The amplitude of the AC voltage VAC is fixed at a specified value. The waveform of the AC voltage VAC is a sine wave, but it can also be a waveform other than a sine wave. The current flowing between electrodes 110 and 111 when the AC voltage VAC is applied is called the current IS.

[0071] The IV conversion unit 220 has a shunt resistor inserted in series on the wiring through which the current IS flows, and uses the shunt resistor to convert the amplitude of the current IS into a voltage. The voltage value obtained through this conversion is called the detection voltage value VS. The detection voltage value VS increases as the amplitude of the current IS increases. Here, the detection voltage value VS is generated in a manner that holds proportionally between the amplitude of the current IS and the detection voltage value VS.

[0072] The water level determination unit 230 compares the detected voltage value VS with a predetermined threshold TH1, and generates and outputs a water level determination signal WD1 corresponding to the comparison result. When the detected voltage value VS is above the threshold TH1, a water level determination signal WD1 with a value of "1" is generated; when the detected voltage value VS is less than the threshold TH1, a water level determination signal WD1 with a value of "0" is generated. A water level determination signal WD1 of "1" indicates that the electrodes 110 and 111 are in a conductive state, thus indicating that the water level in the container 10 is higher than the lower end of the detection electrode 111 (i.e., the water level belongs to any one of the water level ranges WL1 to WL3). A water level determination signal WD1 of "0" indicates that the electrodes 110 and 111 are in a non-conductive state, thus indicating that the water level in the container 10 is lower than the lower end of the detection electrode 111 (i.e., the water level belongs to the water level range WL0).

[0073] Although not specifically illustrated, the detection circuit 64 generates a detection voltage value corresponding to the amplitude of the current flowing between electrodes 110 and 112 when an AC voltage VAC is applied between electrodes 110 and 112, and generates a water level judgment signal WD2 based on this detection voltage value. The water level judgment signal WD2 indicates whether the water level in container 10 is higher than the lower end of detection electrode 112 (in other words, whether electrodes 110 and 112 are in a conducting or non-conducting state). Furthermore, the detection circuit 64 generates a detection voltage value corresponding to the amplitude of the current flowing between electrodes 110 and 113 when an AC voltage VAC is applied between electrodes 110 and 113, and generates a water level judgment signal WD3 based on this detection voltage value. The water level judgment signal WD3 indicates whether the water level in container 10 is higher than the lower end of detection electrode 113 (in other words, whether electrodes 110 and 113 are in a conducting or non-conducting state). The generation methods for water level judgment signals WD2 and WD3 are the same as those for water level judgment signal WD1. Based on water level judgment signals WD1 to WD3, determine which water level range (WL0 to WL3) the water level belongs to.

[0074] The conductivity conversion unit 240 converts the detection voltage value VS into conductivity using a predetermined conversion algorithm, and calculates the detection conductivity ECDET. The detection conductivity ECDET represents the conductivity of the water in the container 10 detected by the detection circuit 64. However, if the exposed portions 110b and 111b are not submerged in water, the conductivity of the water in the container 10 cannot be correctly detected. Therefore, the conductivity conversion unit 240 can calculate the detection conductivity ECDET only when the water level judgment signal WD1 has a value of "1". That is, the detection circuit 64 detects the conductivity of the water in the container 10 when the water level in the container 10 is higher than the lower end of the detection electrode 111, and uses this detection result as the detection conductivity ECDET.

[0075] By using a calibration process with water having a known conductivity, a conversion algorithm can be pre-programmed. Figure 12 shows a flowchart of the calibration process. In the calibration process, firstly, in step S11, a standard solution with a known conductivity ECP (e.g., 50 μS / cm) and a calibration container are prepared, and a calibration state is achieved by adding the necessary amount of the standard solution to the calibration container. In the calibration state, the reference electrode 110 and the detection electrode 111 are immersed in the standard solution so that the exposed portions 110b and 111b are in contact with the standard solution in the calibration container. Container 10 can be used as the calibration container, but any other arbitrary container can also be used.

[0076] In the next step S12, under the calibration state, an AC voltage VAC is applied between electrodes 110 and 111 to obtain a detection voltage value VS. In the next step S13, based on the detection voltage value VS obtained in step S12 and the conductivity ECP, a conversion algorithm is written that specifies the relationship between the detection voltage value VS and the detection conductivity ECDET. If the detection voltage value VS from step S12 is input into the written conversion algorithm, the conductivity ECP is obtained as the detection conductivity ECDET.

[0077] The conversion algorithm can be composed of a mathematical formula defining the relationship between the detection voltage value VS and the detection conductivity ECDET. During the design or manufacturing stage of the hydrogen generator 1, a program (software) containing the conversion algorithm can be written. After calibration, by executing the program in an arithmetic processing circuit (not shown) that can be built into the detection circuit 64, the conductivity of the water in the container 10 can be calculated and obtained as the detection conductivity ECDET.

[0078] When the water level is higher than the lower end of the detection electrode 111, in the comparison structure where electrodes 110 and 111 are not completely covered by the insulator, the detection voltage value VS varies depending on the water level. Although water level judgment has been studied based on considering the variation of the detection voltage value VS depending on the water level, the variation of the detection voltage value VS depending on the water level is the main cause of error, thus leading to false detection of the water level. By adopting the above-described covering structure, the variation of the detection voltage value VS depending on the water level is suppressed, thereby suppressing false detection of the water level. Furthermore, through the linearity obtained by adopting the above-described covering structure, conductivity can be detected with high accuracy regardless of the water level. That is, the water level and conductivity can be detected with high accuracy by the water level sensor (in other words, the structure using the water level sensor can detect not only the water level but also the conductivity with high accuracy). In addition, compared with the structure of FIG15, cost reduction and installation space reduction can be achieved.

[0079] [Example EX1_2]

[0080] Embodiment EX1_2 will be described. When the circuit constant of the IV converter suitable for water level detection is significantly different from the circuit constant of the IV converter suitable for conductivity detection, the IV converter for water level detection and the IV converter for conductivity detection can be respectively provided in the detection circuit 64. That is, the detection circuit 64 can also be configured as shown in FIG. 13. The detection circuit 64a is the detection circuit 64 of Embodiment EX1_2.

[0081] The detection circuit 64a in FIG13 is based on the detection circuit 64 in FIG11, except that the IV conversion unit 220 is replaced with an IV conversion unit 221 for water level detection and an IV conversion unit 222 for conductivity detection, and a switching switch 225 is added. Except for this replacement and addition, the detection circuit 64a in FIG13 has the same configuration as the detection circuit 64 in FIG11.

[0082] In the detection circuit 64a, a switching switch 225 is used to alternately implement the first detection state and the second detection state. In either the first or second detection state, an AC voltage VAC is supplied between the reference electrode 110 and the detection electrode 111. However, in the first detection state, the current IS flows through the IV converter 221, and in the second detection state, the current IS flows through the IV converter 222.

[0083] IV converter 221 has a first shunt resistor inserted in series on the wiring through which the current IS flows in the first detection state. By using the first shunt resistor, the amplitude of the current IS is converted into a voltage, and a detection voltage value VS is generated and output. IV converter 222 has a second shunt resistor inserted in series on the wiring through which the current IS flows in the second detection state. By using the second shunt resistor, the amplitude of the current IS is converted into a voltage, and a detection voltage value VS is generated and output.

[0084] In the first detection state, the water level determination unit 230 generates a water level determination signal WD1 based on the detection voltage value VS from the IV converter 221. The method for generating the water level determination signal WD1 based on the detection voltage value VS is as described in Example EX1_1. In the second detection state, the conductivity conversion unit 240 derives the detection conductivity ECDET based on the detection voltage value VS from the IV converter 222. The method for deriving the detection conductivity ECDET based on the detection voltage value VS is as described in Example EX1_1.

[0085] [Example EX1_3]

[0086] Example EX1_3 will be described. A covering structure may also be applied to each detection electrode other than detection electrode 111. That is, a portion of each of detection electrodes 112 and 113 may be covered by an insulator. In this case, as shown in FIG14, the electrode portion (made of titanium) of detection electrode 112 protruding from electrode support 120 is composed of a covering portion 112a and an exposed portion 112b, and the electrode portion (made of titanium) of detection electrode 113 protruding from electrode support 120 is composed of a covering portion 113a and an exposed portion 113b.

[0087] The exposed portion 112b is the electrode portion of the detection electrode 112 that includes the lower end of the detection electrode 112. The covering portion 112a is the electrode portion of the detection electrode 112 that extends from the lower surface 120B of the electrode support 120 to the exposed portion 112b. The covering portion 112a is covered by an insulator. Since there is no gap between the lower surface 120B of the electrode support 120 and the covering portion 112a, the electrode portion of the detection electrode 112 that extends from the lower surface 120B of the electrode support 120 to the exposed portion 112b can also be completely covered by an insulator. On the other hand, the exposed portion 112b is not covered by an insulator, and the electrode portion in the exposed portion 112b is exposed relative to the water containing space 10R.

[0088] The exposed portion 113b is the electrode portion of the detection electrode 113 that includes the lower end of the detection electrode 113. The covering portion 113a is the electrode portion of the detection electrode 113 that extends from the lower surface 120B of the electrode support 120 to the exposed portion 113b. The covering portion 113a is covered by an insulator. Since there is no gap between the lower surface 120B of the electrode support 120 and the covering portion 113a, the electrode portion of the detection electrode 113 that extends from the lower surface 120B of the electrode support 120 to the exposed portion 113b can also be completely covered by an insulator. On the other hand, the exposed portion 113b is not covered by an insulator, and the electrode portion in the exposed portion 113b is exposed relative to the water containing space 10R.

[0089] As described above, by covering a portion of each electrode with an insulator, not only is the detection voltage value based on the current between electrodes 110 and 111 independent of the water level, but also the detection voltage values ​​based on the current between electrodes 110 and 112, and the detection voltage values ​​based on the current between electrodes 110 and 113 are independent of the water level. Therefore, error factors are reduced not only in water level detection using detection electrode 111, but also in water level detection using detection electrodes 112 and 113, resulting in suppression of false water level detection.

[0090] In addition, if we consider covering a portion of the detection electrodes 112 and 113 with insulating material instead of ensuring linearity related to conductivity detection, the lengths of the exposed portions 112b and 113b in the vertical direction can be longer than the lengths of the exposed portions 110b and 111b (but their lengths can also be set to be the same).

[0091] [Example EX1_4]

[0092] Example EX1_4 will be described. In the hydrogen generator 1 of this embodiment, three detection electrodes 111 to 113 are provided as multiple detection electrodes.

[0093] The detection electrode used for conductivity detection among the multiple detection electrodes is referred to as the target detection electrode. In this case, in this embodiment, the detection electrode (111) with the shortest distance from the bottom surface 10B of the container 10 among the multiple detection electrodes is set as the target detection electrode. Therefore, compared with the case where other detection electrodes (112 or 113) are set as target detection electrodes, conductivity detection can be performed even when the water level is further reduced. However, variations can also be made in which detection electrode 112 or detection electrode 113 is used as the target detection electrode.

[0094] [Example EX1_5]

[0095] Example EX1_5 will be described. In Example EX1_5, the correction process in the hydrogen generator 1 (see Figure 12) will be further explained in comparison with the structure of FIG15.

[0096] In the structure shown in Figure 15, the following first to third steps are required to calibrate the conductivity meter. In the first step, a standard solution with a known conductivity is added to a container (e.g., a container with a volume of 2 liters). In the next second step, the parameters used for calibration are calculated based on the conductivity meter's measured value and the known conductivity. This completes the calibration of the conductivity meter. Subsequently, in the third step, the container is thoroughly rinsed with highly pure water. The rinsing in the third step requires more than the container's volume of pure water (e.g., more than 2 liters). Therefore, in the structure shown in Figure 15, a large amount of standard solution and pure water are required to calibrate the conductivity meter. Furthermore, in the structure shown in Figure 15, it is difficult (too burdensome) to perform conductivity meter calibration on the customer side (the user side of the hydrogen generator), and calibration essentially needs to be performed on the manufacturer's side.

[0097] In the hydrogen generator 1 of this embodiment, since the water level sensor includes a conductivity meter (in other words, the water level sensor and the conductivity meter are integrated), a calibration container with a volume smaller than that of the container 10 can be used in the calibration process (see FIG12). For example, a graduated cylinder 600 with a volume of about 100 ml can be used as the calibration container, with a volume of 2 liters relative to the volume of the container 10 (i.e., the volume of the water containing space 10R). Therefore, the amount of standard solution and pure water required for calibration can be significantly reduced. In addition, calibration at the customer's side is also easier to implement.

[0098] The hydrogen generator 1 operates in either a normal mode or a calibration mode. In normal mode, the water level and conductivity within the container 10 are detected using the configuration and operation shown in Examples EX1_1 or EX1_2. For example, the hydrogen generator 1 is set to calibration mode by inputting a prescribed calibration execution command into the operation unit (not shown) provided in the hydrogen generator 1, or by inputting a prescribed calibration execution command signal from an external device to the control display unit 60 via the signal port 70. In calibration mode, the calibration process shown in FIG12 is performed. At this time, the conductivity ECP of the standard solution used for calibration is provided to the control display unit 60. Furthermore, the conversion algorithm itself can be written during the design or manufacturing stage of the hydrogen generator 1, and thereafter, when the calibration process is performed on the customer side, only the parameters of the conversion algorithm are adjusted.

[0099] [Example EX1_6]

[0100] Example EX1_6 will be described. In Example EX1_6, supplementary matters, application techniques or modification techniques for the above structure will be described.

[0101] Patent Document 1 (Japanese Patent Publication No. 2004-510151) discloses a method for estimating the water level in a container based on the resistance between a water level electrode and a reference electrode, and the resistance between a reference electrode and a reference electrode (see claim 1 of Patent Document 1). Comparing the structures of Patent Document 1 and this embodiment, firstly, the water level estimation method of Patent Document 1 differs from the water level detection method in this embodiment based on whether there is a continuity between the reference electrode and the detection electrode. Furthermore, in Patent Document 1, the reference electrode (corresponding to electrode 143 in FIG. 2 of Patent Document 1) is not covered by an insulator. Therefore, even if one wants to measure conductivity using the water level sensor of Patent Document 1 as in this embodiment, it is difficult to perform accurate conductivity measurement because linearity cannot be obtained. In addition, in the structure of Patent Document 1, since the upper region of the water level electrode (corresponding to the upper region 1412 in FIG. 2 of Patent Document 1) is exposed, it is possible that condensation or other water droplets adhering to this area may lead to false detection of the water level.

[0102] The above describes the case where electrodes 110 to 113 are formed of titanium; however, the constituent material of electrodes 110 to 113 is not limited to titanium. Electrodes 110 to 113 may be formed of any material that is a good conductor with a conductivity sufficiently high than that of the liquid (water) to be contained in container 10. The constituent material of electrodes 110 to 113 may be a metal other than titanium, or a conductive resin. However, electrodes 110 to 113 should be formed of a material that is insoluble in water.

[0103] In this embodiment, three detection electrodes are provided in the electrode unit 12. However, the number n of detection electrodes provided in the electrode unit 12 is arbitrary as long as there is one or more. For example, detection electrodes 112 and 113 can be omitted from the electrode unit 12 and set to "n=1".

[0104] The above describes an example of applying the water level sensor of the present invention to the hydrogen generator 1. However, the water level sensor of the present invention can be applied to any application where it is necessary to detect the water level and conductivity of the liquid in a container. For example, the water level sensor of the present invention can also be applied in a functional water manufacturing apparatus that generates various types of functional water. Furthermore, the liquid in the container can also be a liquid other than water.

[0105] <<Second Embodiment>>

[0106] A second embodiment of the present invention will be described. The second embodiment is an embodiment based on the first embodiment. Regarding matters not described in the second embodiment, unless specifically stated otherwise and without contradiction, matters described in the first embodiment can be applied to the second embodiment. In the second embodiment, a temperature compensation technique for the conductivity of the hydrogen generator 1 applicable to the first embodiment will be described.

[0107] First, the significance of temperature compensation will be explained. As for the detection results of the conductivity of water in container 10, there are detection conductivity without temperature compensation and detection conductivity with temperature compensation.

[0108] The uncompensated conductivity measurement represents the measured result of the actual conductivity of the water within container 10. The actual conductivity of the water within container 10 increases with increasing liquid temperature due to factors such as increased ion mobility, and decreases with decreasing liquid temperature. In other words, the actual conductivity of the water within container 10 depends on the liquid temperature. Here, liquid temperature refers to the temperature of the water within container 10.

[0109] On the other hand, the temperature-compensated conductivity measurement represents the detection result of the conductivity of the water in container 10 when the liquid temperature is assumed to be a specified reference temperature. The actual conductivity of the water in container 10 corresponds to the conductivity of the liquid temperature converted to the reference temperature (the conductivity of the water in container 10 when the liquid temperature is assumed to be the reference temperature), which is equivalent to temperature compensation. 25°C is generally used as the reference temperature, so it is also considered to be 25°C in this embodiment. However, the reference temperature can also be a temperature other than 25°C.

[0110] For example, even if the water samples in container 10 are the same, if the liquid temperature is 50°C, the detection voltage value VS (refer to Figure 11, etc.) has a larger value corresponding to the conductivity of water at 50°C, and if the liquid temperature is 10°C, the detection voltage value VS has a smaller value corresponding to the conductivity of water at 10°C. Therefore, if the detection conductivity ECDET (refer to Figure 11, etc.) is a detection conductivity without temperature compensation, then even if the water samples in container 10 are the same, the detection conductivity ECDET will increase or decrease with the increase or decrease of the liquid temperature.

[0111] In the first embodiment, the detected conductivity ECDET can also be a temperature-uncompensated detected conductivity. In this case, the conductivity conversion unit 240 only needs to convert the detected voltage value VS into conductivity using a predetermined conversion algorithm that is independent of liquid temperature, and then derive the temperature-uncompensated detected conductivity ECDET. The temperature-uncompensated detected conductivity ECDET represents the actual conductivity of the water in the container 10, which depends on the liquid temperature. The control display unit 60 can display the temperature-uncompensated detected conductivity ECDET on the display unit 62, or transmit it to an external device (not shown) connected to the signal port 70.

[0112] In the first embodiment, the detected conductivity ECDET can also be a temperature-compensated detected conductivity. In this case, the conductivity conversion unit 240 only needs to convert the detected voltage value VS into conductivity using a predetermined conversion algorithm that depends on the liquid temperature, and then derive the temperature-compensated detected conductivity ECDET. The temperature-compensated detected conductivity ECDET represents the conductivity of the water in the container 10 assuming the liquid temperature has a reference temperature. The control display unit 60 can display the temperature-compensated detected conductivity ECDET on the display unit 62, or transmit it to an external device (not shown) connected to the signal port 70. The method of performing temperature compensation is known in itself; it is only necessary to add a known temperature compensation method to the above conversion algorithm. Linear temperature compensation or nonlinear temperature compensation can be used.

[0113] In the second embodiment, the temperature-compensated detection conductivity is derived as the detection conductivity ECDET. Temperature compensation requires liquid temperature measurement. Therefore, a temperature sensor 80 as shown in FIG16 is added to the hydrogen generator 1.

[0114] The temperature sensor 80 has a temperature sensing element 81 disposed at the location of the object being measured, and uses the temperature sensing element 81 to measure the temperature at the location of the object being measured. The temperature measured by the temperature sensor 80 is called the measured temperature TDET. The measured temperature TDET represents the measured value of the temperature at the location of the object being measured. Here, the temperature sensing element 81 is composed of a platinum thermoelectric resistor, and the resistance value of the temperature sensing element 81 changes according to the temperature of the location of the object being measured. The temperature sensor 80 outputs a signal corresponding to the resistance value of the temperature sensing element 81 as a signal representing the measured temperature TDET to the conductivity conversion unit 240. Furthermore, as long as the measured temperature TDET can be obtained, the type of temperature sensing element 81 and the structure of the temperature sensor 80 are arbitrary.

[0115] The conductivity conversion unit 240 of FIG11 or FIG13 can be used as the conductivity conversion unit 240 of the second embodiment. The conductivity conversion unit 240 derives a temperature-compensated detection conductivity ECDET based on the detection voltage value VS and the measurement temperature TDET.

[0116] As a simple method for measuring liquid temperature, one approach is to insert a metal temperature sensor, such as a sheathed thermocouple, into the water inside the container 10. However, if a metal temperature sensor is inserted into the water inside the container 10, there is a concern that over time, metal ions may leach out, leading to component degradation. If metal ions leach into the water inside the container 10, the water (pure water) inside the container 10 will deteriorate. This will reduce the lifespan of the electrolysis unit 10. Alternatively, if a resin temperature sensor is inserted, the leakage of metal ions can be prevented, but inserting a resin temperature sensor would result in a significant increase in cost.

[0117] Considering these factors, in this embodiment, the location outside the container 10 is set as the measurement target location, and the temperature of the measurement target location outside the container 10 is used for temperature compensation instead of the liquid temperature. Therefore, it is preferable to set the measurement target location as a location where the temperature changes in the same manner as the liquid temperature and has a temperature that deviates from the liquid temperature by a fixed or as small a deviation as possible. Specifically, it is preferable to measure the temperature of the electrolysis unit 20 as the temperature of the measurement target location.

[0118] The measurement target position can also be set on the outer wall of the container 10. However, it is considered that when the measurement target position is set on the electrolysis unit 20, it is not easy to generate a temperature difference with the liquid. This is because when the temperature sensing element 81 is set on the outer wall of the container 10, the temperature sensing element 81 is easily and strongly affected by the ambient temperature, making it difficult to accurately reflect the liquid temperature. When the temperature sensing element 81 is set on the electrolysis unit 20, the measured temperature TDET is affected by the heat generated by the electrolysis unit 20 and the ambient temperature. The former has a greater impact on the measured temperature TDET (the effect of the heat generated by the electrolysis unit 20) when the temperature sensing element 81 is set on the electrolysis unit 20 than when the temperature sensing element 81 is set on the outer wall of the container 10. On the other hand, the temperature of the water in the container 10 is linked to the temperature of the water in the electrolysis unit 20, rising / falling according to the increase / decrease of the heat generated by the electrolysis unit 20. Therefore, it is considered that setting the temperature sensing element 81 at a position that well reflects the heat generated by the electrolysis unit 20, i.e., on the electrolysis unit 20, can accurately estimate the temperature of the water in the container 10.

[0119] Furthermore, when the temperature sensing element 81 is positioned closer to the center of the surface of the electrolysis unit 20, the temperature difference with the liquid temperature tends to be smaller. The reasons for this are, firstly, that placing the temperature sensing element 81 at the center of the surface of the electrolysis unit 20 (surface SF1 or SF2, described later) is less susceptible to ambient temperature and more susceptible to the heat generated by the electrolysis unit 20 compared to placing it at the ends of the surface. Furthermore, it is believed that water electrolysis is more active near the center of the surface compared to near the ends, thus better reflecting the heat generated by the electrolysis unit 20. Therefore, placing the temperature sensing element 81 at a position that effectively reflects the heat generated by the electrolysis unit 20 allows for accurate estimation of the water temperature within the container 10.

[0120] According to this embodiment, conductivity temperature compensation can be performed without directly measuring the liquid temperature. Since the liquid temperature is not directly measured by immersing the sheathed thermocouple or the like in the water in container 10, there is no need to worry about the outflow of metal ions.

[0121] The following embodiments EX2_1 to EX2_3 belong to the second embodiment. In this embodiment, unless otherwise specifically described and not contradictory, the above matters are applied to the following embodiments. In each embodiment, when there are matters that contradict the above matters, the description in each embodiment may take precedence. Furthermore, as long as there is no contradiction, the matters described in any embodiment of the multiple embodiments shown below may be applied to any other embodiment (that is, any two or more embodiments of the multiple embodiments may be combined).

[0122] [Example EX2_1]

[0123] Example EX2_1 will be described. This embodiment is specific in that the temperature sensing element 81 is disposed outside the container 10 and temperature compensation is performed based on the measured temperature at the location outside the container 10.

[0124] Therefore, the location of the temperature sensing element 81 (i.e., the location of the object to be measured) can be set to a position on the outer wall of the container 10 or a position on the electrolysis unit 20. In addition, any other location that can well reflect the temperature of the water inside the container 10 can also be set as the location of the object to be measured.

[0125] However, as described above, it is preferable to provide a temperature sensing element 81 on the electrolysis unit 20 and to use a temperature sensor 80 to measure the temperature of the electrolysis unit 20.

[0126] To explain the method for setting the position of the measurement object in the electrolysis unit 20, the structure of the electrolysis unit 20 will be described with reference to Figures 17A, 17B, and 17C. For clarity, three mutually orthogonal axes—the X-axis, Y-axis, and Z-axis—are defined. The Z-axis is parallel to the vertical direction (i.e., the vertical direction). Figure 17A is a simplified perspective view of the electrolysis unit 20. Figure 17B is a top view of the electrolysis unit 20 as viewed from a direction orthogonal to the X-axis and Z-axis. Figure 17C is a structural diagram of the components of the electrolysis unit 20 related to the electrolysis of water.

[0127] The electrolysis unit 20 includes a solid polymer membrane 21 and two electrodes, namely a cathode 22 and an anode 23, separated by the solid polymer membrane 21. The solid polymer membrane 21, cathode 22, and anode 23 are housed within the casing of the electrolysis unit 20. In this embodiment, the casing of the electrolysis unit 20 is cylindrical, and one of the upper and lower surfaces of the cylinder, which forms the casing shape of the electrolysis unit 20, is surface SF1, and the other is surface SF2. The bottom surface of the cylinder is also referred to as the lower surface. Surfaces SF1 and SF2 are opposing planes, parallel to the X-axis and Y-axis, respectively. Here, surface SF1 is the upper surface, and surface SF2 is the lower surface. The direction from the positive side of the Z-axis to the negative side is equivalent to downward (i.e., the direction of gravity), so the upper surface SF1 is located closer to the positive side of the Z-axis than the lower surface SF2. The upper surface SF1 and the lower surface SF2 are circles of the same size.

[0128] Inside the shell of the electrolysis unit 20, a solid polymer film 21, a cathode 22, and an anode 23 are disposed between the upper surface SF1 and the lower surface SF2. At this time, the cathode 22 is disposed between the solid polymer film 21 and the upper surface SF1, and the anode 23 is disposed between the solid polymer film 21 and the lower surface SF2. Although not clearly visible in Figure 17C, the solid polymer film 21, the cathode 22, and the anode 23 can each be a disk shape with thickness in the Z-axis direction.

[0129] In the electrolysis unit 20, an upper output port 25 is provided on the upper surface SF1, and an input port 24 and a lower output port 26 are provided on the lower surface SF2. The input port 24 is connected to the piping 30 (see Figure 1), through which water is supplied from the container 10. The electrolysis unit power supply circuit 61 (see Figure 1) supplies a fixed current to the electrolysis unit 20 by applying a voltage that is positive with respect to the potential of the cathode 22 to the anode 23. The electrolysis unit 20 electrolyzes the water supplied to the input port 24 based on the supplied current. Hydrogen generated by the cathode 22 through the electrolysis of water is output from the upper output port 25. Oxygen generated by the anode 23 through the electrolysis of water is output from the lower output port 26. A portion of the water supplied to the input port 24 is electrolyzed and converted into hydrogen and oxygen. The remaining portion of the water supplied to the input port 24 (unelectrolyzed water) is output from either the upper output port 25 or the lower output port 26.

[0130] The upper outlet 25 is connected to the water separator 40 (see Figure 1), and hydrogen and water output from the upper outlet 25 are supplied to the water separator 40. Furthermore, as described above, the water supplied to the water separator 40 returns to the container 10 via piping 32 and the exhaust gas collector 13. The lower outlet 26 is connected to piping 31 (see Figure 1). Oxygen and water output from the lower outlet 26 are supplied to the supply port 11 through piping 31. As a result, the water output from the lower outlet 26 returns to the container 10 through the supply port 11.

[0131] The setting position of the temperature sensing element 81 (i.e., the measurement object position) can be set to the upper surface SF1 or the lower surface SF2. Setting the measurement object position to the upper surface SF1 means that the temperature sensing element 81 is set and fixed to the measurement object position on the upper surface SF1 in contact with it; in this case, the temperature sensing element 81 is located above the upper surface SF1. Setting the measurement object position to the lower surface SF2 means that the temperature sensing element 81 is set and fixed to the measurement object position on the lower surface SF2 in contact with it; in this case, the temperature sensing element 81 is located below the lower surface SF2.

[0132] Furthermore, it is preferable to provide a temperature measuring element 81 at the end of surface SF1 or surface SF2, closer to the center of surface SF1 or surface SF2. Referring to FIG17D, the preferred position for the measurement object will be explained.

[0133] In Figure 17D, distance d1REF represents the minimum distance from the center position 620 of the upper surface SF1 to the end of the upper surface SF1. When the shape of the upper surface SF1 is circular (perfect circle), distance d1REF is the same as the radius of the upper surface SF1. Electrolysis unit 20 with an upper surface SF1 shape different from a circle can also be provided in hydrogen generator 1. For example, when the shape of the upper surface SF1 is square, the distance from the midpoint of one side of the square to the center position 620 is distance d1REF. On the upper surface SF1, the area within a distance d1TH from the center position 620 is called region 625. That is, any position within region 625 is less than or equal to the center position 620. When the measurement object position is set on the upper surface SF1, the measurement object position can be set within region 625.

[0134] Here, "d1TH / d1REF=M" holds true. Therefore, when the position of the object to be measured is set within the region 625 of the upper surface SF1, the ratio of the distance from the center position 620 to the position of the object to be measured (≤d1TH) to the distance d1REF is M or less. M is a value less than 1, for example, "M=1 / 2". The statement "M=1 / 2" is not mandatory, for example, it could also be "M=3 / 5" or "M=1 / 3", but it is preferable to set the position of the object to be measured as close as possible to the center position 620.

[0135] In Figure 17D, distance d2REF represents the minimum distance from the center position 630 of the lower surface SF2 to the end of the lower surface SF2. When the lower surface SF2 has a circular shape (perfect circle), distance d2REF is the same as the radius of the lower surface SF2. Electrolysis unit 20 with a lower surface SF2 shape different from a circle can also be provided in hydrogen generator 1. For example, when the lower surface SF2 has a square shape, the distance from the midpoint of one side of the square to the center position 630 is distance d2REF. On the lower surface SF2, the area within a distance d2TH from the center position 630 is called region 635. That is, any position within region 635 is less than or equal to the center position 630. When the measurement object position is set on the lower surface SF2, the measurement object position can be set within region 635.

[0136] Here, "d2TH / d2REF=M" holds true. Therefore, when the position of the object being measured is set within region 635 of the lower surface SF2, the ratio of the distance from the center position 630 to the position of the object being measured (≤d2TH) to the distance d2REF is M or less. As mentioned above, M is a value less than 1, for example, "M=1 / 2". The statement "M=1 / 2" is not mandatory; for example, it could also be "M=2 / 5" or "M=1 / 3", but it is preferable to set the position of the object being measured as close as possible to the center position 630.

[0137] In addition, in this embodiment, it is mainly envisioned that if the shell of the electrolysis unit 20 is cylindrical, then "d1REF=d2REF", and it can also be "d1TH=d2TH".

[0138] [Example EX2_2]

[0139] Example EX2_2 will be described. The temperature compensation technique of the second embodiment is described based on deriving the temperature-compensated detection conductivity ECDET using the electrode unit 12 of the first embodiment (see Figure 5, etc.). However, the temperature compensation technique of the second embodiment can be applied to any conductivity detection device.

[0140] That is, as shown in FIG18, the conductivity detection device of the second embodiment includes a conductivity meter CM and a temperature sensor 80 including a temperature sensing element 81. The conductivity meter CM is connected to the temperature sensor 80 and receives a signal representing the measured temperature TDET from the temperature sensor 80.

[0141] The conductivity meter CM can be any conductivity meter that detects (measures) the conductivity of water in container 10. For example, the conductivity meter CM has first and second electrodes that are inserted into the water in container 10 and spaced apart. Based on the amplitude of the alternating current flowing between the first and second electrodes when a predetermined alternating voltage is applied between the first and second electrodes, the conductivity of the water in container 10 is detected. At this time, the conductivity meter CM performs temperature compensation based on the measured temperature TDET of the temperature sensor 80. That is, the conductivity meter CM calculates the conductivity of the water in container 10 when the liquid temperature is assumed to be a predetermined reference temperature, based on the amplitude of the alternating current and the measured temperature TDET, as the temperature-compensated conductivity.

[0142] In addition, when using the structure of the first embodiment, the conductivity meter CM is composed of an electrode unit 12 and a detection circuit 64 (FIG. 11) or a detection circuit 64a (FIG. 13).

[0143] [Example EX2_3]

[0144] Example EX2_3 will be described.

[0145] Although this has already been stated, it will be repeated here: the shapes of the upper surface SF1 and the lower surface SF2 are not limited to circles, but are arbitrary. The shapes of the upper surface SF1 and the lower surface SF2 may also be different.

[0146] Although it is assumed that surface SF1 is the upper surface and surface SF2 is the lower surface in surface SF1 and SF2, the positional relationship between surface SF1 and surface SF2 is not limited to this. For example, surface SF1 can be the lower surface and surface SF2 can be the upper surface. Surfaces SF1 and SF2 can also be arranged in the left-right direction. In addition, an anode 23 can be disposed between surface SF1 and the solid polymer film 21, and a cathode 22 can be disposed between surface SF2 and the solid polymer film 21.

[0147] The above describes an example of applying the conductivity detection device of the present invention to the hydrogen generator 1. However, the conductivity detection device of the present invention can be applied to any application where the conductivity of the liquid in a container needs to be detected. For example, the conductivity detection device of the present invention can be applied in a functional water manufacturing apparatus that generates various types of functional water. Furthermore, the liquid in the container can also be a liquid other than water.

[0148] Various modifications can be appropriately made within the scope of the technical concept shown in the claims. The above embodiments are merely examples of embodiments of the present invention, and the meaning of the terms of the present invention and its constituent elements is not limited to the contents described in the above embodiments. The specific numerical values ​​shown in the above specification are merely illustrative, and of course, they can be changed to various numerical values. [Simplified Explanation of the Diagram]

[0012] Figure 1 is an overall structural diagram of the hydrogen generator according to the first embodiment of the present invention. Figure 2 is a simplified perspective view of the electrode unit according to the first embodiment of the present invention. Figure 3 is a diagram illustrating the positional relationship and water level range between the reference electrode and the multiple detection electrodes in the first embodiment of the present invention. Figure 4 is a diagram showing the results of an experiment (first experiment) using a comparative structure. Figure 5 is an explanatory diagram of the covering structure according to the first embodiment of the present invention. Figures 6A, 6B, and 6C are diagrams showing the results of an experiment (second experiment) using the covering structure. Figures 7A and 7B are diagrams showing the covering and exposed portions in the first embodiment of the present invention when no length is provided in the exposed portion in the vertical direction. Figures 8A, 8B, and 8C are diagrams showing the results of an experiment (third experiment) using the covering structure. Figure 9 is a diagram illustrating the behavior of electrons when the exposed portions of the reference electrode and the exposed portions of the detection electrode are opposite each other. Figure 10 is a diagram illustrating the behavior of electrons in the vertical direction when no length is provided in the exposed portions of the reference electrode and the exposed portions of the detection electrode. Figure 11 is a diagram showing the internal configuration of a portion of the detection circuit in Embodiment EX1_1, which belongs to the first embodiment of the present invention. Figure 12 is a flowchart of the calibration process in Embodiment EX1_1, which belongs to the first embodiment of the present invention. Figure 13 is a diagram showing the internal configuration of a portion of the detection circuit in Embodiment EX1_2, which belongs to the first embodiment of the present invention. Figure 14 is a diagram illustrating the structure of the reference electrode and multiple detection electrodes in Embodiment EX1_3, which belongs to the first embodiment of the present invention. Figure 15 is a diagram showing the case where a conductivity meter is provided inside the container in the reference method. Figure 16 is a configuration diagram for temperature compensation of conductivity in the second embodiment of the present invention. Figures 17A, 17B, 17C, and 17D are diagrams illustrating the structure of the electrolysis unit and the method for setting the position of the measurement object in the second embodiment of the present invention. Figure 18 is a configuration diagram of the conductivity detection device in Embodiment EX2_2, which belongs to the second embodiment of the present invention.

Claims

1. A water level and conductivity detection device comprising a reference electrode inserted into a container containing water and one or more detection electrodes, wherein the water level in the container is detected by detecting whether there is continuity between the reference electrode and the one or more detection electrodes, the water level and conductivity detection device being characterized in that the one or more detection electrodes includes a target detection electrode covered by an insulator, the electrode portion of the reference electrode including a reference exposed portion at the lower end of the reference electrode and the electrode portion of the target detection electrode including a detection exposed portion at the lower end of the target detection electrode are covered by an insulator, the water level and conductivity detection device using the reference electrode and the target detection electrode to detect the conductivity of the water in the container, the water level and conductivity detection device including a temperature sensor for measuring the temperature of an electrolysis unit that generates hydrogen by electrolyzing water supplied from the container, and performing temperature compensation of the detected conductivity based on the measured temperature of the electrolysis unit.

2. The water level and conductivity detection device as described in claim 1, wherein, The lower end of the reference electrode is closer to the bottom surface of the container than the lower end of the object detection electrode. The water level and conductivity detection device is provided with a detection circuit. The detection circuit detects whether the water level in the container is higher than the lower end of the object detection electrode based on the current between the reference electrode and the object detection electrode when an AC voltage is applied between them. And when the water level in the container is higher than the lower end of the object detection electrode, the conductivity of the water in the container is detected based on the current.

3. The water level and conductivity detection device as described in claim 2, wherein, As one or more detection electrodes, multiple detection electrodes are provided at different distances from the bottom surface of the container. The lower end of the reference electrode is closer to the bottom surface of the container than the lower ends of each detection electrode. The detection circuit detects whether the water level in the container is higher than the lower end of the detection electrode for each detection electrode based on the current between the reference electrode and the detection electrode when the AC voltage is applied between the reference electrode and the detection electrode.

4. The water level and conductivity detection device as described in claim 3, wherein, The object detection electrode is the detection electrode among the plurality of detection electrodes that is the shortest distance from the bottom surface of the container.

5. The water level and conductivity detection device as described in claim 3, wherein, In the plurality of detection electrodes that are different from the object detection electrode, the electrode portion other than the exposed portion at the lower end of the detection electrode is also covered by an insulator.

6. The water level and conductivity detection device as described in claim 1, wherein, The reference electrode and the one or more detection electrodes extend downward from the electrode support body that supports the reference electrode and the one or more detection electrodes, and the reference exposed portion and the detection exposed portion have length in the vertical direction.

7. The water level and conductivity detection device as described in claim 6, wherein, In the vertical direction, the length of the reference exposed portion and the length of the detection exposed portion are both greater than 0 and less than or equal to 10 mm.

8. The water level and conductivity detection device as described in claim 6, wherein, The reference electrode has the reference exposed portion and a reference covering portion as the electrode portion extending from the electrode support to the reference exposed portion. The object detection electrode has the detection exposed portion and a detection covering portion as the electrode portion extending from the electrode support to the detection exposed portion. The reference covering portion and the detection covering portion are covered by an insulator. In the vertical direction, the length of the reference exposed portion is shorter than the length of the reference covering portion, and the length of the detection exposed portion is shorter than the length of the detection covering portion.

9. A hydrogen generator, wherein, include: Container, for holding water; An electrolysis unit that produces hydrogen by electrolyzing water supplied from the container; a water level and conductivity detection device as described in any one of claims 1 to 8; and piping for circulating water between the container and the electrolysis unit; the electrolysis unit having a first and a second face facing each other, with an anode and a cathode of the electrolysis unit disposed between the first and second faces, and a hydrogen generator measuring the temperature of the electrolysis unit by means of a temperature sensing element disposed in the temperature sensor on the first or second face.

10. The hydrogen generator as claimed in claim 9, wherein, The anode, the cathode, and the solid polymer membrane are housed within the casing of the electrolysis unit, with the first surface and the second surface being two surfaces within the casing.

11. A conductivity detection device for detecting the conductivity of water in a container, the conductivity detection device being characterized in that it includes a temperature sensor for measuring the temperature of an electrolysis unit that generates hydrogen by electrolyzing water supplied from the container, and performing temperature compensation of the detected conductivity based on the measured temperature of the electrolysis unit.

12. A hydrogen generator, wherein, include: Container, for holding water; An electrolysis unit produces hydrogen by electrolyzing water supplied from the container; The conductivity detection device as described in claim 11; And piping, for circulating water between the container and the electrolysis unit; the electrolysis unit has a first side and a second side facing each other, with the anode and cathode of the electrolysis unit disposed between the first side and the second side, and the hydrogen generator measures the temperature of the electrolysis unit by means of a temperature sensing element disposed in the temperature sensor on the first side or the second side.

13. The hydrogen generator as claimed in claim 12, wherein, The anode, the cathode, and the solid polymer membrane are housed within the casing of the electrolysis unit, with the first surface and the second surface being two surfaces within the casing.

14. A method for detecting water level and conductivity, using a reference electrode inserted into a container containing water and one or more detection electrodes, detecting the water level in the container by detecting whether there is continuity between the reference electrode and the one or more detection electrodes, characterized in that the one or more detection electrodes includes a target detection electrode covered by an insulator, the insulator covering the electrode portion of the reference electrode excluding the reference exposed portion at the lower end of the reference electrode and the electrode portion of the target detection electrode excluding the detection exposed portion at the lower end of the target detection electrode, using the reference electrode and the target detection electrode to detect the conductivity of the water in the container, measuring the temperature of an electrolysis unit that generates hydrogen by electrolyzing water supplied from the container using a temperature sensor, and performing temperature compensation of the detected conductivity based on the measured temperature of the electrolysis unit.

15. The water level and conductivity detection method as described in claim 14, used in a hydrogen generator, the hydrogen generator including a container, an electrolysis unit, and piping for circulating water between the container and the electrolysis unit, wherein the electrolysis unit has a first face and a second face facing each other, and an anode and a cathode of the electrolysis unit are disposed between the first face and the second face, the water level and conductivity detection method measuring the temperature of the electrolysis unit by means of a temperature sensing element disposed in the temperature sensor on the first face or the second face.

16. A conductivity detection method for detecting the conductivity of water in a container, the conductivity detection method being characterized in that a temperature sensor is used to measure the temperature of an electrolysis unit that generates hydrogen by electrolyzing water supplied from the container, and temperature compensation is performed on the detected conductivity based on the measured temperature of the electrolysis unit.

17. The conductivity detection method as described in claim 16, used in a hydrogen generator, the hydrogen generator including a container, an electrolysis unit, and piping for circulating water between the container and the electrolysis unit, wherein the electrolysis unit has a first face and a second face facing each other, and an anode and a cathode of the electrolysis unit are disposed between the first face and the second face, the conductivity detection method measuring the temperature of the electrolysis unit by means of a temperature sensing element disposed in the temperature sensor on the first face or the second face.

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