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

Abstract

To detect the conductivity by utilizing a structure of a water level sensor.SOLUTION: Disclosed is a water level and conductivity detecting device which includes a reference electrode (110) to be inserted into a tank in which the liquid should be stored and one or more detection electrodes, and detects the water level in the tank by detecting the presence or absence of continuity between the reference electrode and one or more detection electrodes. One or more detection electrodes includes an object detection electrode (111) covered with an insulator. An electrode portion (110a) other than the reference exposure part (110b) including the lower end of the reference electrode among the reference electrodes and an electrode portion (111a) other than a detection exposure part (111b) including the lower end of the object detection electrode among the object detection electrodes are covered with the insulator, and the conductivity of the liquid in the tank is detected using the reference electrode and the object detection electrode.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present 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. [Background technology]

[0002] Water level sensors are used to detect the water level in a tank. For example, in a hydrogen generator that produces hydrogen by electrolyzing water using an electrolytic cell, water level sensors are used to monitor the water level in the tank used for storing pure water.

[0003] On the other hand, it may be necessary to detect the conductivity of the liquid in the tank. For example, in the hydrogen generator described above, an increase in the conductivity of the water used for electrolysis accelerates the deterioration of the electrolytic cell. For this reason, monitoring of conductivity may be required. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Special Publication No. 2004-510151 [Overview of the project] [Problems that the invention aims to solve]

[0005] By installing a conductivity meter inside the tank in addition to the water level sensor used to detect the water level, it is possible to detect both the water level and conductivity (see Figure 15; Figure 15 will be explained later). However, this method requires space to install the conductivity meter inside the tank, and the cost increases due to the installation of the conductivity meter. Furthermore, ingenuity is required to accurately detect conductivity using the structure of the water level sensor.

[0006] On the other hand, temperature compensation is often necessary when detecting conductivity. While temperature compensation can be achieved by installing a temperature sensor inside the tank, there are concerns that components of the temperature sensor (such as metal ions) may leak into the liquid inside the tank.

[0007] The present invention aims to provide a water level and conductivity detection device that enables accurate detection of water level and conductivity while suppressing increases in installation space or cost, a hydrogen generator utilizing the same, and a method for detecting water level and conductivity. The present invention also aims to provide a conductivity detection device, a hydrogen generator utilizing the same, and a method for detecting conductivity that contribute to suppressing the above concerns. [Means for solving the problem]

[0008] The water level and conductivity detection device according to the present invention comprises a reference electrode inserted into a tank to contain a liquid and one or more detection electrodes, and detects the water level in the tank by detecting whether or not there is conductivity between the reference electrode and the one or more detection electrodes, wherein the one or more detection electrodes include target detection electrodes covered with an insulator, and the electrode portion of the reference electrode other than the reference exposed portion including the lower end of the reference electrode and the electrode portion of the target detection electrode other than the detection exposed portion including the lower end of the target detection electrode are covered with an insulator, and the conductivity of the liquid in the tank is detected using the reference electrode and the target detection electrodes.

[0009] The conductivity detection device according to the present invention is a conductivity detection device for detecting the conductivity of a liquid in a tank, and is equipped with a temperature sensor that measures the temperature of a measurement target location outside the tank, and performs temperature compensation for the detected conductivity based on the temperature measured by the temperature sensor. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a water level and conductivity detection device that enables accurate conductivity detection while suppressing an increase in installation space or cost, a hydrogen generator utilizing the same, and a water level and conductivity detection method. Furthermore, according to the present invention, it is possible to provide a conductivity detection device, a hydrogen generator utilizing the same, and a conductivity detection method that contribute to suppressing the above concerns. [Brief explanation of the drawing]

[0011] [Figure 1] This is an overall configuration diagram of a hydrogen generator according to the first embodiment of the present invention. [Figure 2] This is a schematic perspective view of an electrode unit according to the first embodiment of the present invention. [Figure 3] This figure illustrates the positional relationship between a reference electrode and a plurality of detection electrodes and the water level range according to a first embodiment of the present invention. [Figure 4] This figure shows the results of the experiment (Experiment 1) using a comparative configuration. [Figure 5] This is an explanatory diagram of the covering configuration according to the first embodiment of the present invention. [Figure 6] This figure shows the results of the experiment using the coating configuration (experiment 2). [Figure 7] This figure shows the covered portion and the exposed portion when no length is provided in the exposed portion in the vertical direction, according to the first embodiment of the present invention. [Figure 8] This figure shows the results of the experiment using the coating configuration (experiment 3). [Figure 9] This diagram illustrates the behavior of electrons when the exposed portion of the reference electrode and the exposed portion of the detection electrode face each other. [Figure 10] This diagram illustrates the behavior of electrons when there is no length provided for the exposed portion of the reference electrode and the exposed portion of the detection electrode in the vertical direction. [Figure 11] This figure shows a partial internal configuration of a detection circuit relating to Example EX1_1, which belongs to the first embodiment of the present invention. [Figure 12] This is a flowchart of the calibration process relating to Example EX1_1, which belongs to the first embodiment of the present invention. [Figure 13] This figure shows a partial internal configuration of a detection circuit relating to Example EX1_2, which belongs to the first embodiment of the present invention. [Figure 14] This figure illustrates the structure of a reference electrode and a plurality of detection electrodes, relating to Example EX1_3, which belongs to the first embodiment of the present invention. [Figure 15] This diagram shows how a conductivity meter is installed inside a tank, as per the reference method. [Figure 16] This diagram shows a configuration for performing temperature compensation of conductivity according to a second embodiment of the present invention. [Figure 17] This figure illustrates a second embodiment of the present invention, illustrating the structure of an electrolytic cell and a method for setting the measurement target position. [Figure 18] This diagram shows the configuration of an conductivity detection device according to Example EX2_2, which belongs to a second embodiment of the present invention. [Modes for carrying out the invention]

[0012] Hereinafter, examples of embodiments of the present invention will be specifically described with reference to the drawings. In each of the referenced figures, the same parts are denoted by the same reference numerals, and redundant descriptions relating to the same parts are omitted as a general rule. In this specification, for the sake of simplification of the description, symbols or reference numerals that refer to information, signals, physical quantities, or components may be used, and the names of the information, signals, physical quantities, or components corresponding to those symbols or reference numerals may be omitted or abbreviated. For example, the reference electrode referred to by "110" described later (see Figure 2) may be written as reference electrode 110 or abbreviated as electrode 110, but all of these refer to the same thing.

[0013] <<First Embodiment>> A first embodiment of the present invention will now be described. Figure 1 shows an overall configuration diagram of a hydrogen generator 1 according to the first embodiment of the present invention. The hydrogen generator 1 generates hydrogen by electrolyzing water using an electrolytic cell. The hydrogen generator 1 comprises a housing CS and parts referred to by reference numerals 10-14, 20, 30-33, 40-42, 50-59, 60-64 and 70-72. The parts referred to by reference numerals 10-14, 20, 30-33, 40-42, 50-57 and 60-64 are housed within the housing CS. The parts referred to by reference numerals 58, 59 and 70-72 are attached to the outer wall of the housing CS.

[0014] Water is contained within the tank 10. The tank 10 has a cylindrical or prismatic cavity on its inside as a water-containing space 10R, and water is contained within this water-containing space 10R. However, the shape of the water-containing space 10R shown here is merely an example, and its shape can be changed in various ways. In this embodiment, the containment of water in the tank 10 and the containment of water in the water-containing space 10R are synonymous. The water to be contained in the tank 10 is classified as pure water. A supply port 11 is provided at one end of the top of the tank 10, and water is supplied into the tank 10 through the supply port 11.

[0015] An electrode unit 12 is attached to the tank 10. The electrode unit 12 comprises a reference electrode to be inserted into the tank 10 and one or more detection electrodes (three detection electrodes in the example of Figure 1). The water level in the tank 10 (hereinafter simply referred to as the water level) can be detected by detecting whether or not there is conductivity between the electrodes. Furthermore, the conductivity of the water in the tank 10 can also be detected using the electrode unit 12, but the details of the electrode unit 12 will be described later. An exhaust trap 13 is also attached to the tank 10.

[0016] The bottom of tank 10 is connected to piping 30 via a check valve 14. Water in tank 10 is supplied to electrolytic cell 20 through piping 30 via check valve 14. Electrolytic cell 20 electrolyzes the water supplied through piping 30. Some of the oxygen and water produced by the electrolysis of electrolytic cell 20 is sent to the supply port 11 via piping 31. The hydrogen and other parts of the water produced by the electrolysis of electrolytic cell 20 are sent to water separation trap 40. The water sent to water separation trap 40 is sent back into tank 10 via piping 32 and exhaust trap 13. The hydrogen-containing gas sent to water separation trap 40 is sent to dryer 42 via hydrogen piping 41.

[0017] Hydrogen generated in the electrolytic cell 20 and purified in the dryer 42 is sent to the hydrogen piping 50. Hydrogen piping 50 is connected to hydrogen piping 51 via a water discharge prevention filter 54, and hydrogen piping 51 is connected to one end of hydrogen piping 52 via a solenoid valve 55. The other end of hydrogen piping 52 is connected to the hydrogen outlet 58. The solenoid valve 55 is controlled to be open or closed by the control display unit 60. Only when the solenoid valve 55 is open is hydrogen in hydrogen piping 51 sent to hydrogen piping 52, and as a result, hydrogen generated in the electrolytic cell 20 is output from the hydrogen outlet 58.

[0018] Furthermore, hydrogen piping 50 is connected to one end of hydrogen piping 53 via a safety valve 56, and the other end of hydrogen piping 53 is connected to a hydrogen outlet 59. When the pressure inside hydrogen piping 50 exceeds a predetermined value, the safety valve 56 connects hydrogen piping 50 to hydrogen piping 53 and releases the hydrogen inside hydrogen piping 50 from the hydrogen outlet 59. A pressure sensor 57 detects the hydrogen pressure in hydrogen piping 50. Note that the hydrogen in each hydrogen piping is gaseous hydrogen (hydrogen gas).

[0019] The power supply voltage V is supplied to the power port 71 from outside the hydrogen generator 1. POW The following is input: Power supply voltage V POW This is, for example, commercial AC voltage. The control display unit 60 is connected to the power port 71, and the power supply voltage V POWIt is driven based on the power supply voltage V. The control display unit 60 comprehensively controls the operation of the hydrogen generator 1. The control display unit 60 controls the power supply voltage V. POW Based on this, the hydrogen generator 1 is equipped with a power supply circuit that supplies the internal power supply voltage necessary for the operation of each component. The electrolytic cell power supply circuit 61 contained within the control unit 60 supplies a constant current to the electrolytic cell 20. The electrolytic cell 20 performs electrolysis of water based on the supplied current. The electrolytic cell 20 is made of a solid polymer membrane.

[0020] The control display unit 60 further 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 the signal port 70. An external device (not shown) can be connected to the signal port 70 outside the hydrogen generator 1, and in this case, various signals can be transmitted and received between the control display unit 60 and the external device via the signal port 70.

[0021] The display unit 62 consists of light-emitting diodes or the like. A display screen consisting of a liquid crystal display panel or the like may also be provided on the display unit 62.

[0022] The alarm output unit 63 outputs various alarms. The alarm output unit 63 outputs a water level alarm when the water level in the tank 10 falls below a predetermined lower limit (corresponding to a state where the water level belongs to the water level 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 cell alarm when an abnormality is detected in the cell voltage supplied to the electrolytic cell 20. Output of any alarm includes a predetermined alarm display on the display unit 62 and transmission of an alarm signal via the signal port 70. The alarm signal is transmitted to an external device via the signal port 70.

[0023] The water level and conductivity detection circuit 64 (hereinafter abbreviated as detection circuit 64) works in cooperation with the electrode unit 12 to detect the water level in the tank 10. Thus, the detection circuit 64 and the electrode unit 12 form a water level sensor. Furthermore, the detection circuit 64 also works in cooperation with the electrode unit 12 to detect the conductivity of the water in the tank 10. Therefore, it can 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).

[0024] The control display unit 60 can display the cell voltage or the pressure detected by the pressure sensor 57 on the display unit 62. The control display unit 60 can also display the water level and conductivity detected by the detection circuit 64 on the display unit 62.

[0025] Furthermore, the control display unit 60 may transmit a water replenishment request signal to an external device via the signal port 70 when the water level in the tank 10 falls below a predetermined lower limit. Also, 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 stops the generation of hydrogen (hydrogen gas) by the electrolytic cell 20 and stops the output of hydrogen from the hydrogen generator port 58 by switching the solenoid valve 55 to the closed state.

[0026] Furthermore, if necessary, the water in the tank 10 can be discharged to the outside via the drain pipe 33 and drain port 72.

[0027] Figure 2 is a schematic perspective view of the electrode unit 12. Figure 3 schematically shows the positional relationship between the tank 10 and the electrode unit 12 when viewed from the side. Note that the supply port 11 and exhaust trap 13 are not shown in Figure 3. The bottom surface of the tank 10 is referred to as “10B”. The bottom surface 10B corresponds to the bottom surface of the water storage space 10R of the tank 10. When the bottom surface 10B is viewed from the vertical direction, its shape is, for example, a circle or a polygon.

[0028] The electrode unit 12 comprises a reference electrode 110, detection electrodes 111 to 113, and an electrode support 120. The upper ends 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.

[0029] The electrode unit 12 is fixed in a predetermined position in the tank 10 by inserting the electrode support 120 into an electrode support housing opening (not shown) provided on the upper surface of the tank 10 and fixing the electrode support 120 within the electrode support housing opening. However, the electrode unit 12 is configured to be detachable from the tank 10. In this embodiment, unless otherwise specified, the electrode unit 12 is assumed to be fixed in a predetermined position in the tank 10, and the hydrogen generator 1 is assumed to be installed so that the bottom surface 10B is parallel to the horizontal plane. The electrodes 110 to 113 on the electrode support 120 may be distributed concentrically around an axis parallel to the vertical direction (this is schematically shown in Figure 2). However, the electrodes 110 to 113 on the electrode support 120 may be arranged in a single row in the horizontal direction. In some of the referenced drawings (for example, Figure 3), the electrodes 110 to 113 are shown arranged in the horizontal direction.

[0030] The reference electrode 110 and detection electrodes 111-113 are rod-shaped electrodes extending downward from the electrode support 120 and are inserted into the tank 10. The electrode support 120 supports the upper ends of the reference electrode 110 and detection electrodes 111-113 while insulating them from each other. A wiring group 130 for electrically connecting the reference electrode 110 and detection electrodes 111-113 to the detection circuit 64 is provided on the electrode unit 12. The wiring group 130 is routed as a cable from the top of the electrode support 120.

[0031] The outer shape of the electrode support 120 is a substantially cylindrical shape having a height in the vertical direction, and the lower surface 120B of the electrode support 120 is parallel to the horizontal plane. The reference electrode 110 and the detection electrodes 111 to 113 protrude downward from the lower surface 120B of the electrode support 120. When comparing the lengths of the reference electrode 110 and the detection electrodes 111 to 113 protruding from the lower surface 120B of the electrode support 120, their lengths are different from each other. Among these lengths, the length of the reference electrode 110 is the largest, the length of the detection electrode 111 is the second largest, the length of the detection electrode 112 is the third largest, and the length of the detection electrode 113 is the smallest. Therefore, "d0 < d1 < d2 < d3" holds. Here, d0, d1, d2, and d3 represent the distances from the bottom surface 10B to the lower ends of the reference electrode 110, the detection electrode 111, the detection electrode 112, and 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 the respective detection electrodes.

[0032] The reference electrode 110 and the detection electrodes 111 to 113 are rod-shaped electrodes made of titanium and having the same cross-sectional area as each other. In the present embodiment, the shape of each cross-section (a cross-section parallel to the horizontal plane) of the reference electrode 110 and the detection electrodes 111 to 113 is a circle with a diameter of 1.4 mm (millimeters). Also, in the present 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 to 113 can be variously deformed.

[0033] Referring to FIG. 3, the water level sensor including the electrode unit 12 and the detection circuit 64 detects which of the water level ranges WL0, WL1, WL2, and WL3 the water level in the tank 10 belongs to. This detection is realized by detecting the presence or absence of conduction between the reference electrode 110 and each of the detection electrodes 111 to 113. A state where conduction exists between any two electrodes is referred to as a conduction state, and a state where conduction does not exist between any two electrodes is referred to as a non-conduction state.

[0034] With respect to 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 a state in which the electrical resistance between the reference electrode 110 and the detection electrode of interest is less than or equal to a predetermined reference resistance value, and the non-conductive state between the reference electrode 110 and the detection electrode of interest refers to a state in which the electrical resistance between the reference electrode 110 and the detection electrode of interest exceeds a predetermined reference resistance value. Conduction 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 the water in the tank 10.

[0035] The water level in tank 10 refers to the height of the water surface inside tank 10 as viewed from the bottom surface 10B. Water level range WL3 is the range where the water surface height is greater than or equal to a distance d3. Water level range WL2 is the range where the water surface height is greater than or equal to a distance d2 and less than a distance d3. Water level range WL1 is the range where the water surface height is greater than or equal to a distance d1 and less than a distance d2. Water level range WL0 is the range where the water surface height is less than a distance d1.

[0036] When the water level in tank 10 is within the water level range WL3, a portion of the reference electrode 110 and a portion of the detection electrode 113 are submerged in water, resulting in conductivity between electrodes 110 and 113 via the water. When the water level in tank 10 is within the water level range WL2, the detection electrode 113 is not in contact with water, resulting in a non-conductive state between electrodes 110 and 113. Conversely, a portion of the reference electrode 110 and a portion of the detection electrode 112 are submerged in water, resulting in conductivity between electrodes 110 and 112 via the water. When the water level in tank 10 is within the water level range WL1, the detection electrodes 112 and 113 are not in contact with water, resulting in a non-conductive state between electrodes 110 and 112 and between electrodes 110 and 113. Conversely, a portion of the reference electrode 110 and a portion of the detection electrode 111 are submerged in water, resulting in conductivity between electrodes 110 and 111 via the water. When the water level in tank 10 falls within the water level range WL0, the detection electrodes 111-113 do not come into contact with the water, resulting in a non-conductive state between the reference electrode 110 and each of the detection electrodes 111-113.

[0037] Therefore, the detection circuit 64 can detect the water level in four stages by detecting whether or not there is continuity between the reference electrode 110 and each of the detection electrodes 111 to 113. In other words, the detection circuit 64 determines that the water level belongs to water level range WL3 when there is continuity between electrodes 110 and 113. The detection circuit 64 determines that the water level belongs to water level range WL2 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 belongs to water level range WL1 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 belongs to water level range WL0 when there is no continuity between electrodes 110 and 111. In this way, the water level sensor can detect whether or not the water level is higher than the height of the lower end of the detection electrode for each detection electrode.

[0038] Many hydrogen generators, which produce hydrogen using the electrolysis of water, detect the water level to ensure proper water replenishment. On the other hand, if the conductivity of the water supplied to the electrolytic cell (electrolytic cell 20 in hydrogen generator 1) is high, the deterioration of the electrolytic cell is accelerated, and depending on the conductivity, the electrolytic cell may fail after only a short period of operation. For this reason, detection of the water's conductivity is often required.

[0039] To detect conductivity, a reference method is considered in which a conductivity meter is installed separately from the water level sensor, as shown in Figure 15. In the reference method in Figure 15, the conductivity meter is installed in the tank separately from the electrode unit that forms the water level sensor. However, this reference method requires space to be provided in the tank for the conductivity meter, and the cost increases due to the installation of the conductivity meter.

[0040] Considering this, in this embodiment, both water level detection and conductivity detection are achieved using a water level sensor configuration. DetectionTo investigate the configuration for achieving good results, the following first, second, and third experiments were conducted. In this embodiment, in practice, a portion of the reference electrode 110 and the detection electrode 111 are covered with an insulator. However, in the first experiment, a comparative configuration was adopted in which the entire reference electrode 110 and the detection electrode 111 protruding from the electrode support 120 were not covered with any insulator.

[0041] In each experiment, several types of water with known conductivity were prepared, and the conductivity of the water between the reference electrode 110 and the detection electrode 111 was measured using an experimental conductivity meter, with a portion of each electrode in contact with the water. The experimental conductivity meter was a conductivity meter prepared specifically for the experiment.

[0042] Figure 4 shows the results of the first experiment. In the graph in Figure 4, the horizontal axis corresponds to the conductivity of the water in tank 10, and the conductivity on the horizontal axis can be understood to represent the true conductivity of the water in tank 10 (the same applies to the graphs in Figures 6(a) to (c) and Figures 8(a) to (c) described later). In the first experiment, an experimental conductivity meter was connected to a reference electrode 110 and a detection electrode 111, which were configured for comparison, 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 predetermined AC voltage is applied between electrodes 110 and 111. For convenience, the output value of the experimental conductivity meter is referred to here as the reference detected conductivity. In each experiment, the calibration of the experimental conductivity meter was insufficient, and therefore, the reference detected conductivity does not represent the true conductivity. However, the linearity of the experimental conductivity meter is sufficiently high. In other words, when the conductivity of water is multiplied by k in each experiment, the reference detected conductivity also becomes multiplied by k with sufficiently high accuracy (where k is any positive value).

[0043] Here, the distance from the lower end of the reference electrode 110 to the water surface in the tank 10 is defined as distance D. W This is referred to as [the term]. In the graph of Figure 4, the plots represented by black circles represent the distance D. W This shows the relationship between the true conductivity and the reference detected conductivity related to the comparison configuration when the distance is 10 cm. In the graph in Figure 4, the plots represented by white triangles represent the distance D WIt shows the relationship between the true conductivity and the reference detection conductivity related to the comparison configuration when it is 6 cm. In the graph of Fig. 4, the plots represented by white squares are the distance D W It shows the relationship between the true conductivity and the reference detection conductivity related to the comparison configuration when it is 3 cm.

[0044] In the comparison configuration, although linearity can be obtained at each water level, it can be seen that the reference detection conductivity changes depending on the water level. This is because the electrode area in contact with water changes as the water level changes. Since the detection conductivity by the conductivity meter depends on a constant (referred to as the cell constant) determined by the electrode area in contact with water and the electrode distance, if the above electrode area changes depending on the water level, the detection conductivity (here, the reference detection conductivity) also changes. For example, when the comparison configuration is adopted, in comparison with when the distance D W is 3 cm, when the distance D W is changed to 6 cm, the contact area between the reference electrode 110 and water and the contact area between the detection electrode 111 and water each become approximately twice, and as a result, the obtained reference detection conductivity also becomes approximately twice.

[0045] Therefore, it is difficult to detect the accurate conductivity when the comparison configuration is adopted. Thus, in the second experiment and the third experiment, a coating configuration in which a part of each of the reference electrode 110 and the detection electrode 111 protruding from the electrode support 120 is covered with an insulator was adopted.

[0046] Referring to Fig.  5, the structures of the reference electrode 110 and the detection electrode 111 related to the coating configuration will be described. In the hydrogen generator 1 according to the present embodiment, actually, a part of each of the detection electrodes 112 and 113 may also be covered with an insulator, but in Fig. 5, only the coating configuration related to the reference electrode 110 and the detection electrode 111 is shown.

[0047] <{ The electrode portion (the electrode portion made of titanium) of the reference electrode 110 protruding from the electrode support 120 is composed of a covered 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 covered 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 covered portion 110a is covered with an insulator. Therefore, the electrode portion in the covered portion 110a does not come into contact with the water in the tank 10 regardless of the water level, and does not function as an electrode in effect. In the covered configuration, there should be no gap between the lower surface 120B of the electrode support 120 and the covered portion 110a, and it is preferable that 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 is entirely covered with an insulator. On the other hand, the exposed portion 110b is not covered with an insulator, and the electrode portion of the exposed portion 110b is exposed to the water containment space 10R. Therefore, if the water level is greater than or equal to the distance d0, the electrode portion of the exposed portion 110b will come into contact with the water in the tank 10.

[0048] The electrode portion (the electrode portion made of titanium) of the detection electrode 111 protruding from the electrode support 120 is composed of a covered 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 covered 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 covered portion 111a is covered with an insulator. Therefore, the electrode portion in the covered portion 111a does not come into contact with the water in the tank 10 regardless of the water level, and does not function as an electrode in effect. In the covered configuration, there should be no gap between the lower surface 120B of the electrode support 120 and the covered portion 111a, and it is preferable that 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 is entirely covered with an insulator. On the other hand, the exposed portion 111b is not covered with an insulator, and the electrode portion of the exposed portion 111b is exposed to the water containment space 10R. Therefore, if the water level is greater than or equal to the distance d1, the electrode portion of the exposed portion 111b will come into contact with the water in the tank 10.

[0049] The length of the exposed portion 110b of the reference electrode 110 in the vertical direction is denoted by the symbol "Lb". 110 Refer to “Lb”. The length of the exposed portion 111b of the detection electrode 111 in the vertical direction is denoted by “Lb”. 111 See “ for reference. In the vertical direction, the length Lb of the exposed portion 110b 110 The length of the exposed portion 111b is sufficiently shorter than the length of the covered portion 110a, and the length of the exposed portion 111b is Lb 111 It is sufficiently shorter than the length of the covering portion 111a. Length Lb 110 and length Lb 111 These are basically the same as each other, but it is also possible to transform them so that they are different from each other.

[0050] The insulator in the covering portions 110a and 111a has an electrical resistivity that is sufficiently high so as not to affect the detection of water level and conductivity. For example, a heat-shrinkable tube made of silicone rubber or a fluororesin can be used as the insulator. In the second and third experiments, a heat-shrinkable tube was used as the insulator. However, the insulator in the covering portions 110a and 111a may be in the form of an insulating tube. Alternatively, for example, the covering portion 110a may be formed by coating a part of the reference electrode 110 with an insulator (the same applies to the detection electrode 111).

[0051] In the second experiment, the length Lb 110 and Lb 111 The length was set to approximately 2 mm (millimeters). Figures 6(a) to 6(c) show the results of the second experiment. In the second experiment, the coating configuration (however, the length Lb) was set. 110 and Lb 111 An experimental conductivity meter was connected to the reference electrode 110 and detection electrode 111, which were approximately 2 mm in diameter, and the output value of the experimental conductivity meter was read as the reference detected conductivity. In the graph of Figure 6(a), the plots represented by black circles represent the distance D W This shows the relationship between the true conductivity and the reference detected conductivity for the second experiment when the distance is 10 cm. In the graph in Figure 6(b), the plots represented by white triangles represent the distance D W This shows the relationship between the true conductivity and the reference detected conductivity for the second experiment when the distance is 6 cm. In the graph in Figure 6(c), the plots represented by white rectangles represent the distance DW This shows the relationship between the true conductivity and the reference detected conductivity related to the second experiment when the distance is 3 cm.

[0052] When each plot shown in Figures 6(a) to 6(c) is plotted on a single graph, the plots represented by black circles, white triangles, and white rectangles overlap and become indistinguishable from each other; therefore, they are shown on separate graphs. This indicates that the reference detected conductivity in the second experiment is not dependent on the water level at all or only slightly. Although not clear from Figures 6(a) to (c), the error in the reference detected conductivity due to the water level in the second experiment is about 1%. That is, when water with a certain conductivity is used in the second experiment, the distance D W First reference detected conductivity when the distance D is 10 cm. W The second reference detectable conductivity when the distance is 6 cm, and the distance D W We consider obtaining the third reference detectable conductivity when the distance is 3 cm by actual measurement, and then calculating the absolute value of the difference between the obtained conductivity values. This calculated absolute value is approximately 1% or less of the value of the first, second, or third reference detectable conductivity.

[0053] When a covered configuration is adopted, the area of ​​the electrode portion of the reference electrode 110 that is in contact with water, i.e., the surface area of ​​the exposed portion 110b, is constant regardless of the water level (however, the water level is (d0 + Lb 110 (Assuming that the water level is above 1100%). When a covered configuration is adopted, the area of ​​the part of the electrode portion of the detection electrode 111 that is in contact with water, i.e., the surface area of ​​the exposed portion 111b, is constant regardless of the water level (however, the height of the water level is (d1+Lb 111 (Assuming that the water level is above )). For this reason, the entire exposed parts 110b and 111b are in contact with water (i.e., the water level is (d1+Lb). 111 In the state where the value is above 20%, the reference detected conductivity does not depend on the water level.

[0054] Furthermore, in the coating configuration of the second experiment, good linearity is obtained in the reference detected conductivity over a wide conductivity range. That is, in the coating configuration of the second experiment, the true conductivity and the reference detected conductivity are proportional over a wide conductivity range.

[0055] In the third experiment, the length Lb 110 and Lb 111 This was effectively set to 0 mm (millimeters). In this case, as shown in Figure 7(a), the exposed portion 110b consists only of the lower surface of the reference electrode 110, and as shown in Figure 7(b), the exposed portion 111b consists only of the lower surface of the detection electrode 111.

[0056] Figures 8(a) to 8(c) show the results of the third experiment. In the third experiment, the covering configuration (however, length Lb) was used. 110 and Lb 111 An experimental conductivity meter was connected to the reference electrode 110 and the detection electrode 111, which were set to a value of 0 mm, and the output value of the experimental conductivity meter was read as the reference detected conductivity. In the graph of Figure 8(a), the plots represented by black circles represent the distance D W This shows the relationship between the true conductivity and the reference detected conductivity for the third experiment when the distance is 10 cm. In the graph in Figure 8(b), the plots represented by white triangles represent the distance D W This shows the relationship between the true conductivity and the reference detected conductivity for the third experiment when the distance is 6 cm. In the graph in Figure 8(c), the plots represented by white rectangles represent the distance D W This shows the relationship between the true conductivity and the reference detected conductivity for the third experiment when the length is 3 cm.

[0057] When each plot shown in Figures 8(a) to 8(c) is plotted on a single graph, the groups of plots represented by black circles, white triangles, and white rectangles overlap and become indistinguishable from each other. Therefore, they are shown on separate graphs. This indicates that the reference detected conductivity for the third experiment is not dependent on the water level at all or only slightly.

[0058] However, the linearity of the reference detected conductivity is broken in the coating configuration used in the third experiment. In particular, in the coating configuration used in the third experiment, the proportional relationship between the true conductivity and the reference detected conductivity is broken in the range of relatively high conductivity.

[0059] Therefore, LengthLb 110 and Lb 111It is desirable to make the length greater than zero, that is, to give length to the exposed parts 110b and 111b in the vertical direction. However, the length Lb 110 and Lb 111 If the value is made too large, the change in the cell constant due to the water level becomes significant enough that it cannot be ignored. Considering these factors, the length Lb 110 and Lb 111 It is desirable to make it greater than 0 and less than or equal to a predetermined length. Considering the experimental results, the length Lb 110 and Lb 111 It is desirable to set the length to a range of 2 mm to 3 mm, but the length Lb 110 and Lb 111 It may be less than 2 mm (for example, 1 mm) or slightly more than 3 mm. For example, the specified length may be 5 mm or 10 mm. Length Lb 110 and Lb 111 If set to a value greater than 0 and less than or equal to 10 mm, it is generally considered that no problems will occur in terms of the accuracy of conductivity detection. Also, in the vertical direction, the length Lb is the sum of the lengths of the covered portion 110a and the exposed portion 110b. 110 The ratio of the length Lb to the sum of the lengths of the covered portion 111a and the exposed portion 111b. 111 The ratio may be set to be greater than 0 and less than or equal to a predetermined value (for example, 5% or less or 3% or less).

[0060] Furthermore, in order to prevent false detection of water level due to condensation, a reference configuration in which only a small portion above the reference electrode and a small portion above the detection electrode are covered with an insulator is also considered. However, even if conductivity measurement is attempted with this reference configuration, it is difficult to obtain the desired linearity. At least in the vertical direction, the length Lb of the exposed portion 110b of the reference electrode 110 is... 110 The length of the exposed portion 111b of the detection electrode 111 is made shorter than the length of the covering portion 110a, and the length of the exposed portion 111b of the detection electrode 111 is Lb 111 By making the length shorter than the length of the covering portion 111a, it is possible to ensure a certain degree of linearity (better linearity than the reference configuration above can be obtained).

[0061] Here, length Lb 110 and Lb111 We will consider the behavior related to length Lb. Figure 9 shows the length Lb 110 and Lb 111 The current line distribution when a voltage is applied between electrodes 110 and 111, assuming the exposed portion has a suitable size (e.g., 2 mm), is schematically shown. In the state shown in Figure 9, a portion of the side surface of exposed portion 110b and a portion of the side surface of exposed portion 111b face each other. Therefore, when a voltage is applied between electrodes 110 and 111, the dominant current path is the one that connects exposed portions 110b and 111b by the shortest distance. In reality, curved current paths also exist, but in the state shown in Figure 9, the current line distribution between electrodes 110 and 111 is kept constant or easily kept constant regardless of the conductivity of water. Therefore, high linearity can be obtained with respect to conductivity measurement in the state shown in Figure 9. For technical data on current line distribution in conductivity measurement, see Non-Patent Literature "Commentary on General Rules of Conductivity Titration Methods," [online], [Retrieved September 9, 2021], Internet.<URL:https: / / www.jstage.jst.go.jp / article / revpolarography1955 / 10 / 3 / 10_3_102 / _pdf> " is one example.

[0062] Figure 10 shows the length Lb 110 and Lb 111 The current line distribution when a voltage is applied between electrodes 110 and 111 when the current is zero is schematically shown. In the state of Figure 10, the exposed portion 110b and the exposed portion 111b do not have opposing electrode portions. Therefore, when a voltage is applied between electrodes 110 and 111 in the state of Figure 10, current flows along a curved path between the exposed portion 110b, which corresponds to the lower surface of the reference electrode 110, and the exposed portion 111b, which corresponds to the lower surface of the detection electrode 111. In other words, in the state of Figure 10, a linear current distribution that satisfies Ohm's law is not formed, and the current line distribution fluctuates depending on the conductivity of water, so it is considered that the linearity related to conductivity measurement is likely to break down.

[0063] In this embodiment, unless otherwise specified, the above-described coating configuration is used for the reference electrode 110 and the detection electrode 111, and the length Lb 110 and Lb 111The length shall be set within the range of 2 mm to 3 mm.

[0064] Examples EX1_1 to EX1_6 below belong to the first embodiment. Examples EX1_1 to EX1_6 describe several specific configuration examples, operation examples, application technologies, modification technologies, etc., related to the hydrogen generator 1 (especially the water level sensor). In this embodiment, the matters described above apply to each of the following embodiments unless otherwise specified and without contradiction. In the event of any contradiction between the matters described above and each embodiment, the description in each embodiment may take precedence. Also, unless there is a contradiction, the matters described in any of the multiple embodiments shown below can be applied to any other embodiment (i.e., it is possible to combine any two or more embodiments from the multiple embodiments).

[0065] [Example EX1_1] Example EX1_1 will now be described. Figure 11 shows the internal configuration of the detection circuit 64 related to Example EX1_1. However, Figure 11 only shows the configuration related to electrodes 110 and 111 of the detection circuit 64 (the same applies to Figure 13, which will be described later).

[0066] In the configuration shown in Figure 11, the detection circuit 64 includes an AC voltage source 210, an IV conversion unit 220, a water level determination unit 230, and a conductivity conversion unit 240.

[0067] AC voltage source 210 provides an AC voltage V having a predetermined frequency. AC Generates and outputs AC voltage V AC AC voltage V is supplied between the reference electrode 110 and the detection electrode 111. AC The frequency is set to a range of several tens of Hz to several megaHz, for example. AC voltage V AC The amplitude is fixed at a predetermined value. AC voltage V AC The waveform is a sine wave, but other waveforms are also acceptable. An AC voltage V is applied between electrodes 110 and 111. AC With the current applied, the current flowing between electrodes 110 and 111 is current I. S It is called that.

[0068] The IV conversion unit 220 converts current I S The wiring has a shunt resistor inserted in series with the current I, and the current I is passed through the shunt resistor. S The amplitude is converted to a voltage. The voltage value obtained by this conversion is the detected voltage value V. S It is called [this]. Current I S As the amplitude increases, the detected voltage value V S It increases. Here, current I S Amplitude and detected voltage value V S The detected voltage value V should be such that a proportional relationship holds between it and the other. S It is assumed that the following will be generated.

[0069] The water level determination unit 230 detects the voltage value V S The detected voltage value V is compared with a predetermined threshold TH1, and a water level determination signal WD1 is generated and output according to the comparison result. S When the threshold TH1 is greater than or equal to the water level determination signal WD1 with a value of "1", the detected voltage value V S When the value 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 electrodes 110 and 111 are conducting, and therefore the water level in tank 10 is higher than the lower end of the detection electrode 111 (i.e., the water level belongs to one of the water level ranges WL1 to WL3). A water level determination signal WD1 of "0" indicates that electrodes 110 and 111 are not conducting, and therefore the water level in tank 10 is lower than the lower end of the detection electrode 111 (i.e., the water level belongs to the water level range WL0).

[0070] Although not specifically shown in the diagram, the detection circuit 64 uses an AC voltage V AC When the AC voltage V is applied between electrodes 110 and 112, a detection voltage value corresponding to the amplitude of the current flowing between electrodes 110 and 112 is generated, and a water level determination signal WD2 is generated based on the detection voltage value. The water level determination signal WD2 indicates whether the water level in the tank 10 is higher than the lower end of the detection electrode 112 (in other words, it indicates whether electrodes 110 and 112 are in a conductive or non-conductive state). Furthermore, the detection circuit 64 uses the AC voltage V ACWhen a current is applied between electrodes 110 and 113, a detection voltage value corresponding to the amplitude of the current flowing between electrodes 110 and 113 is generated, and a water level determination signal WD3 is generated based on this detection voltage value. The water level determination signal WD3 indicates whether the water level in the tank 10 is higher than the lower end of the detection electrode 113 (in other words, it indicates whether electrodes 110 and 113 are in a conductive or non-conductive state). The method for generating water level determination signals WD2 and WD3 is the same as the method for generating water level determination signal WD1. The water level determination signals WD1 to WD3 determine which of the water level ranges WL0 to WL3 the water level belongs to.

[0071] The conductivity conversion unit 240 uses a predetermined conversion algorithm to detect the voltage value V S The conductivity EC is detected by converting it to conductivity. DET To find the detected conductivity EC. DET This represents the conductivity of the water in tank 10 as detected by the detection circuit 64. However, the conductivity of the water in tank 10 cannot be correctly detected unless the exposed parts 110b and 111b are submerged in water. Therefore, the conductivity conversion unit 240 detects conductivity EC only when the water level determination signal WD1 has a value of "1". DET It is acceptable for the detection circuit 64 to determine the conductivity of the water in the tank 10 when the water level in the tank 10 is higher than the lower end of the detection electrode 111, and the detection result is the detected conductivity EC. DET To obtain as such.

[0072] A conversion algorithm can be pre-created by performing a calibration process using water with a known conductivity. Figure 12 shows a flowchart of the calibration process. In the calibration process, first, in step S11, the known conductivity EC P A standard solution having a pH (for example, 50 μS / cm) and a calibration container are prepared, and the calibration state is achieved by pouring the required amount of the standard solution into the calibration container. In the calibration state, the reference electrode 110 and the detection electrode 111 are immersed in the standard solution in the calibration container such that their exposed parts 110b and 111b are in contact with the standard solution. A tank 10 can be used as the calibration container, but any other container can also be used.

[0073] In the subsequent step S12, an AC voltage V is applied between the electrodes 110 and 111 in the calibration state to obtain a detected voltage value V AC . In the subsequent step S13, based on the detected voltage value V S obtained in step S12 and the conductivity EC S , a conversion algorithm that defines the relationship between the detected voltage value V P and the detected conductivity EC S is created. For the created conversion algorithm, if the detected voltage value V DET of step S12 is input, the conductivity EC S can be obtained as the detected conductivity EC DET . P

[0074] The conversion algorithm may be constituted by a mathematical formula that defines the relationship between the detected voltage value V S and the detected conductivity EC DET . In the design or manufacturing stage of the hydrogen generator 1, a program (software) including the conversion algorithm may be created. After the calibration process, the conductivity of the water in the tank 10 can be derived by calculation by executing the program with an arithmetic processing circuit (not shown) built in the detection circuit 64, and the calculation result can be obtained as the detected conductivity EC DET .

[0075] When the water level is higher than the lower end of the detection electrode 111, in the comparative configuration where the electrodes 110 and 111 are not covered with any insulator, the detected voltage value V S changes depending on the water level. Considering that the detected voltage value V S changes depending on the water level, it is also considered to perform a water level determination. However, the change in the detected voltage value V S that depends on the water level functions as an error factor and may lead to an incorrect detection of the water level. By adopting the above-described covering configuration, the detected voltage value V S ​Because changes in the water level are suppressed, false detections of the water level are reduced. In addition, the linearity resulting from the adoption of the above-described covering configuration makes it possible to accurately detect conductivity regardless of the water level. In other words, the water level sensor can accurately detect both the water level and conductivity (or, to put it another way, the structure of the water level sensor can be used to accurately detect not only the water level but also the conductivity). Furthermore, compared to the configuration in Figure 15, cost reductions and installation space reductions are achieved.

[0076] [Example EX1_2] Example EX1_2 will now be described. If the circuit constants of the IV conversion unit suitable for water level detection and the circuit constants of the IV conversion unit suitable for conductivity detection differ significantly, the detection circuit 64 may be provided with separate IV conversion units for water level detection and conductivity detection. That is, the detection circuit 64 may be configured as shown in Figure 13. Detection circuit 64a is the detection circuit 64 according to Example EX1_2.

[0077] The detection circuit 64a in Figure 13 is based on the detection circuit 64 in Figure 11, but 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 changeover switch 225 is added. Except for this replacement and addition, the detection circuit 64a in Figure 13 has the same configuration as the detection circuit 64 in Figure 11.

[0078] In the detection circuit 64a, the first detection state and the second detection state are alternately realized using the changeover switch 225. In both the first and second detection states, the AC voltage V AC A current is supplied between the reference electrode 110 and the detection electrode 111. However, in the first detection state, current I S The current flows through the IV conversion unit 221, and in the second detection state, current I S The current flows through the IV conversion unit 222.

[0079] The IV conversion unit 221, in the first detection state, receives current I S It has a first shunt resistor inserted in series on the wiring through which current I flows, and the current I is passed through the first shunt resistor. S The amplitude is converted into a voltage to detect the voltage value VS It generates and outputs the following. The IV conversion unit 222 generates and outputs the current I in the second detection state. S It has a second shunt resistor inserted in series on the wiring through which current I flows, and the current I is passed through the second shunt resistor. S The amplitude is converted into a voltage to detect the voltage value V S Generates and outputs.

[0080] In the first detection state, the water level determination unit 230 detects the voltage value V from the IV conversion unit 221. S Based on this, a water level determination signal WD1 is generated. Detected voltage value V S The method for generating the water level determination signal WD1 based on is as described in Example EX1_1. In the second detection state, the conductivity conversion unit 240 receives the detected voltage value V from the IV conversion unit 222. S The conductivity EC is detected based on this. DET Derive the detected voltage value V. S Detected conductivity EC based on DET The derivation method is as described in Example EX1_1.

[0081] [Example EX1_3] Example EX1_3 will now be described. The covering configuration may also be applied to each detection electrode other than detection electrode 111. That is, parts of detection electrodes 112 and 113 may be covered with an insulator. In this case, as shown in Figure 14, the electrode portion of detection electrode 112 protruding from the electrode support 120 (the electrode portion made of titanium) is composed of a covered portion 112a and an exposed portion 112b, and the electrode portion of detection electrode 113 protruding from the electrode support 120 (the electrode portion made of titanium) is composed of a covered portion 113a and an exposed portion 113b.

[0082] The exposed portion 112b is the electrode portion of the detection electrode 112 that includes the lower end of the detection electrode 112. The covered 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 covered portion 112a is covered with an insulator. There is no gap between the lower surface 120B of the electrode support 120 and the covered portion 112a, and it is preferable that 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 is entirely covered with an insulator. On the other hand, the exposed portion 112b is not covered with an insulator, and the electrode portion in the exposed portion 112b is exposed to the water containment space 10R.

[0083] The exposed portion 113b is the electrode portion of the detection electrode 113, including the lower end of the detection electrode 113. The covered portion 113a is the electrode portion of the detection electrode 113, from the lower surface 120B of the electrode support 120 to the exposed portion 113b. The covered portion 113a is covered with an insulator. There is no gap between the lower surface 120B of the electrode support 120 and the covered portion 113a, and it is preferable that the electrode portion of the detection electrode 113, from the lower surface 120B of the electrode support 120 to the exposed portion 113b, is entirely covered with an insulator. On the other hand, the exposed portion 113b is not covered with an insulator, and the electrode portion in the exposed portion 113b is exposed to the water containment space 10R.

[0084] As described above, by covering a portion of each electrode with an insulator, the detected voltage value based on the current between electrodes 110 and 111, as well as the detected voltage value based on the current between electrodes 110 and 112, and the detected voltage value based on the current between electrodes 110 and 113, become 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, and as a result, false detection of the water level is suppressed.

[0085] Furthermore, if we consider covering parts of the detection electrodes 112 and 113 with insulating material, not from the perspective of ensuring linearity related to conductivity detection, but from the perspective of suppressing false detection of water level, the lengths of the exposed parts 112b and 113b in the vertical direction are, exposed part 110b and 111bIt is acceptable for each of these lengths to be longer than the others (however, it is also possible to set all of these lengths to be the same).

[0086] [Example EX1_4] Example EX1_4 will now be described. The hydrogen generator 1 according to this embodiment is provided with three detection electrodes 111 to 113 as multiple detection electrodes.

[0087] Among multiple detection electrodes, the detection electrode used for detecting conductivity is referred to as the target detection electrode. In this embodiment, among the multiple detection electrodes, the detection electrode (111) that is closest to the bottom surface 10B of the tank 10 is set as the target detection electrode. This allows for the detection of conductivity even when the water level is lower, compared to when another detection electrode (112 or 113) is set as the target detection electrode. However, it is also possible to modify the system by using detection electrode 112 or 113 as the target detection electrode.

[0088] [ExampleEX1_5] Example EX1_5 will now be described. In Example EX1_5, the calibration process in hydrogen generator 1 (see Figure 12) will be explained in comparison with the configuration in Figure 15.

[0089] In the configuration shown in Figure 15, the following three steps are required to calibrate the conductivity meter. In the first step, a standard solution with a known conductivity is placed in a tank (for example, a tank with a volume of 2 liters). In the second step, calibration parameters are calculated based on the conductivity meter's measurement and the known conductivity. This completes the calibration of the conductivity meter. After that, in the third step, the tank is washed with sufficiently pure water. The washing in the third step requires more pure water than the volume of the tank (for example, more than 2 liters). Thus, calibrating the conductivity meter in the configuration shown in Figure 15 requires a large amount of standard solution and pure water. Furthermore, regarding the configuration shown in Figure 15, it is difficult (and burdensome) for the customer (the user of the hydrogen generator) to perform the calibration of the conductivity meter, and it basically needs to be done by the manufacturer.

[0090] In contrast, in the hydrogen generator 1 according to this embodiment, since the water level sensor includes a conductivity meter (in other words, the water level sensor and conductivity meter are integrated), a calibration container with a smaller volume than the tank 10 can be used for the calibration process (see Figure 12). For example, while the volume of the tank 10 (i.e., the volume of the water storage space 10R) is 2 liters, a cylinder 600 with a volume of about 100 milliliters can be used as a calibration container. Therefore, it is possible to significantly reduce the amount of standard solution and pure water required for calibration. Furthermore, calibration can be easily performed by the customer.

[0091] The hydrogen generator 1 has two operating modes: normal mode and calibration mode. In normal mode, the water level and conductivity in the tank 10 are detected by the configuration and operation shown in Example EX1_1 or EX1_2. For example, the operating mode of the hydrogen generator 1 is set to calibration mode by inputting a predetermined calibration execution instruction operation to the control unit 60 via the signal port 70 from an external device, or by inputting a predetermined calibration execution instruction signal from an external device to the control display unit 60. In calibration mode, the calibration process shown in Figure 12 is executed. At this time, the conductivity EC of the standard solution used in the calibration process is... P This is provided to the control display unit 60. The conversion algorithm itself may be created during the design or manufacturing stage of the hydrogen generator 1, and only the parameters of the conversion algorithm will be adjusted when calibration is performed by the customer.

[0092] [Example EX1_6] Example EX1_6 will be described. Example EX1_6 will describe supplementary information, applied techniques, or modified techniques for the above-described configuration.

[0093] Patent Document 1 (Japanese Patent Publication No. 2004-510151) discloses a method for estimating the water level in a tank based on the electrical resistance between the water level electrode and the reference electrode, and the electrical resistance between the reference electrode and the reference electrode (see Claim 1 of Patent Document 1). Let's compare Patent Document 1 with the configuration of this embodiment. First, the water level estimation method according to Patent Document 1 differs from the method in this embodiment which detects the water level based on the presence or absence of conductivity between the reference electrode and the detection electrode. Also, in Patent Document 1, the reference electrode (corresponding to electrode 143 in Figure 2 of Patent Document 1) is not covered with an insulator. For this reason, even if we try to measure conductivity with the water level sensor of Patent Document 1 as in this embodiment, it is difficult to measure conductivity accurately because linearity cannot be obtained. Furthermore, in the configuration of Patent Document 1, the upper region of the water level electrode (corresponding to the upper region 1412 in Figure 2 of Patent Document 1) is exposed, so there is a concern that the water level may be misdetected due to water droplets such as condensation forming there.

[0094] Although electrodes 110 to 113 are formed from titanium as described above, the constituent material of electrodes 110 to 113 is not limited to titanium. Electrodes 110 to 113 can be formed from a good conductive material having a conductivity sufficiently higher than that of the liquid (water) to be contained in tank 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 made from a material that does not dissolve in water.

[0095] In this embodiment, the electrode unit 12 is provided with three detection electrodes, but the number of detection electrodes n provided in the electrode unit 12 can be any number as long as it is 1 or more. For example, n can be set to "1" by omitting detection electrodes 112 and 113 from the electrode unit 12.

[0096] Although an example of applying the water level sensor according to the present invention to a hydrogen generator 1 has been described above, the water level sensor according to the present invention can be applied to any application requiring the detection of the water level and conductivity of the liquid in a tank. For example, the water level sensor according to the present invention may be applied to a functional water production apparatus that produces various types of functional water. Furthermore, the liquid in the tank may be something other than water.

[0097] <<Second Embodiment>> A second embodiment of the present invention will now be described. The second embodiment is an embodiment based on the first embodiment, and with respect to matters not described in the second embodiment, unless otherwise specified and without contradiction, the matters described in the first embodiment may be applied to the second embodiment. In the second embodiment, a temperature compensation technique for conductivity applicable to the hydrogen generator 1 according to the first embodiment will be described.

[0098] First, let me explain the significance of temperature compensation. The results of detecting the conductivity of the water in tank 10 include the detected conductivity without temperature compensation and the detected conductivity with temperature compensation.

[0099] The detected conductivity without temperature compensation represents the actual conductivity of the water in tank 10. The actual conductivity of the water in tank 10 increases as the liquid temperature rises through factors such as an increase in ion migration speed, and conversely decreases as the liquid temperature falls. In other words, the actual conductivity of the water in tank 10 depends on the liquid temperature. Here, liquid temperature refers to the temperature of the water in tank 10.

[0100] On the other hand, temperature-compensated detected conductivity refers to the detection result of the conductivity of the water in tank 10 when it is assumed that the liquid temperature is at a predetermined reference temperature. Converting the actual conductivity of the water in tank 10 to the conductivity at the reference temperature (the conductivity of the water in tank 10 when it is assumed that the liquid temperature is at the reference temperature) according to the liquid temperature constitutes temperature compensation. Since 25°C is generally adopted as the reference temperature, in this embodiment as well, the reference temperature is assumed to be 25°C. However, the reference temperature may be other than 25°C.

[0101] For example, even if the water sample in tank 10 is the same, if the liquid temperature is 50°C, the detection voltage value V described above will be the same. S (See Figure 11, etc.) has a relatively large value corresponding to the conductivity of water at 50°C, and if the liquid temperature is 10°C, the detected voltage value V S It has a relatively small value corresponding to the conductivity of water at 10°C. Therefore, the detected conductivity EC DET(See Figure 11, etc.) If the detected conductivity is uncompensated for temperature, the detected conductivity EC will change with increasing or decreasing liquid temperature, even if the water sample in tank 10 is the same. DET It also increases or decreases.

[0102] In the first embodiment, the detected conductivity EC DET The detected conductivity may be one without temperature compensation. In this case, the conductivity conversion unit 240 uses a predetermined conversion algorithm that is independent of liquid temperature to detect the voltage value V S By converting this to conductivity, the detected conductivity EC without temperature compensation is obtained. DET We just need to derive the following: Detected conductivity EC without temperature compensation. DET This represents the actual conductivity of the water in tank 10 and depends on the liquid temperature. The control display unit 60 displays the detected conductivity EC without temperature compensation. DET This may be displayed on the display unit 62, or transmitted to an external device (not shown) connected to the signal port 70.

[0103] In the first embodiment, the detected conductivity EC DET The detected conductivity may be temperature-compensated. In this case, the conductivity conversion unit 240 uses a predetermined conversion algorithm that depends on the liquid temperature to detect the voltage value V S By converting this to conductivity, the temperature-compensated detected conductivity EC is obtained. DET We just need to derive the following: Temperature-compensated detected conductivity EC DET This represents the conductivity of the water in tank 10, assuming the liquid temperature is at a reference temperature. The control display unit 60 displays the temperature-compensated detected conductivity EC. DET The result may be displayed on the display unit 62, or transmitted to an external device (not shown) connected to the signal port 70. The method of performing temperature compensation is publicly known, and a known temperature compensation method can be incorporated into the above conversion algorithm. Linear or nonlinear temperature compensation can be used.

[0104] In the second embodiment, the temperature-compensated detection conductivity is hereinafter referred to as the detection conductivity EC. DETIt is assumed that this will be derived as follows. In order to perform temperature compensation, it is necessary to measure the liquid temperature. For this reason, a temperature sensor 80, as shown in Figure 16, is added to the hydrogen generator 1.

[0105] The temperature sensor 80 has a temperature measuring element 81 installed at the measurement target location, and measures the temperature at the measurement target location using the temperature measuring element 81. The temperature measured by the temperature sensor 80 is called the measured temperature T DET It is called [this]. Measurement temperature T DET This represents the measured temperature at the measurement target location. Here, the temperature measuring element 81 is made of a platinum resistance thermometer, and the resistance value of the temperature measuring element 81 changes according to the temperature at the measurement target location. The temperature sensor 80 receives a signal corresponding to the resistance value of the temperature measuring element 81, and measures the measured temperature T DET The signal representing this is output to the conductivity conversion unit 240. The measurement temperature T is used as the temperature at the measurement target location. DET As long as the desired result can be obtained, the type of temperature measuring element 81 and the configuration of the temperature sensor 80 are arbitrary.

[0106] The conductivity conversion unit 240 in Figure 11 or Figure 13 can be used as the conductivity conversion unit 240 according to the second embodiment. The conductivity conversion unit 240 detects the voltage value V S and the measured temperature T DET Based on temperature-compensated detected conductivity EC DET Derive the following.

[0107] A simple method for measuring liquid temperature is to insert a metal temperature sensor, such as a sheathed thermocouple, into the water in tank 10. However, inserting a metal temperature sensor into the water in tank 10 raises concerns about the long-term leakage of metal ions due to component degradation. If metal ions leak into the water in tank 10, the water (pure) in tank 10 will deteriorate. This will lead to a reduction in the lifespan of the electrolytic cell 10. While introducing a resin temperature sensor can prevent the leakage of metal ions, introducing a resin temperature sensor would result in a significant increase in costs.

[0108] Taking these factors into consideration, in this embodiment, a location outside the tank 10 is set as the measurement target location, and the temperature of the measurement target location outside the tank 10 is used instead of the liquid temperature for temperature compensation. For this reason, it is preferable to set the measurement target location to a location where the temperature changes in the same way as the change in liquid temperature, and where the deviation from the liquid temperature is constant or as small as possible. Specifically, it is preferable to measure the temperature of the electrolytic cell 20 as the temperature of the measurement target location.

[0109] It is also possible to set the measurement target position on the outer wall of the tank 10. However, it is thought that setting the measurement target position on the electrolytic cell 20 will result in less difference from the liquid temperature. This is because, when the temperature sensing element 81 is installed on the outer wall of the tank 10, the temperature sensing element 81 is strongly affected by the ambient temperature, making it difficult to accurately reflect the liquid temperature. Measurement temperature T when the temperature sensing element 81 is installed on the electrolytic cell 20 DET The measurement temperature T is affected by the heat generated by the electrolytic cell 20 and the ambient temperature. DET The former influence (the effect of heat generation from the electrolytic cell 20) is greater when the temperature measuring element 81 is installed on the electrolytic cell 20 than when the temperature measuring element 81 is installed on the outer wall of the tank 10. On the other hand, the temperature of the water in the tank 10 is linked to the temperature of the water in the electrolytic cell 20, and rises / falls in accordance with the increase / decrease in the amount of heat generated by the electrolytic cell 20. For this reason, it is considered that the temperature of the water in the tank 10 can be estimated more accurately by installing the temperature measuring element 81 on the electrolytic cell 20, which is a position that well reflects the amount of heat generated by the electrolytic cell 20.

[0110] Furthermore, placing the temperature sensing element 81 closer to the center of the surface of the electrolytic cell 20 tends to result in a smaller difference between the temperature and the liquid temperature. One reason for this is that, firstly, placing the temperature sensing element 81 in the center of the surface of the electrolytic cell 20 (surface SF1 or SF2 described later) is less affected by ambient temperature and more affected by the heat generated by the electrolytic cell 20 than placing it at the edge of the surface of the electrolytic cell 20 (surface SF1 or SF2 described later). Also, it is thought that the electrolysis of water is relatively more active near the center of the surface than near the edges, and the heat generated by the electrolytic cell 20 is better reflected there. It is thought that placing the temperature sensing element 81 in a position that better reflects the heat generated by the electrolytic cell 20 allows for a more accurate estimation of the water temperature in the tank 10.

[0111] According to this embodiment, temperature compensation for conductivity is possible without directly measuring the liquid temperature. Since the sheathed thermocouple or the like is not immersed in the water in the tank 10 to directly measure the liquid temperature, there is no concern about the outflow of metal ions.

[0112] Examples EX2_1 to EX2_3 below belong to the second embodiment. In this embodiment, the matters described above apply to each of the following embodiments unless otherwise specified and unless otherwise contradictory. In the event of any inconsistency between the matters described above and those described in each embodiment, the description in each embodiment may take precedence. Furthermore, unless otherwise contradictory, the matters described in any of the multiple embodiments shown below may be applied to any other embodiment (i.e., any two or more embodiments from the multiple embodiments can be combined).

[0113] [Example EX2_1] Example EX2_1 will now be described. This embodiment is unique in that the temperature measuring element 81 is installed outside the tank 10 and temperature compensation is performed based on the measured temperature at a location outside the tank 10.

[0114] Therefore, the installation position of the temperature-sensing element 81 (i.e., the measurement target position) can be set to a position on the outer wall of the tank 10 or a position on the electrolytic cell 20. Furthermore, any other position that can accurately reflect the temperature of the water inside the tank 10 can also be set as the measurement target position.

[0115] However, as described above, it is preferable to install a temperature measuring element 81 in the electrolytic cell 20 and measure the temperature of the electrolytic cell 20 with a temperature sensor 80.

[0116] To explain how to set the measurement target position on the electrolytic cell 20, the structure of the electrolytic cell 20 will be described with reference to Figures 17(a) to (c). For the sake of detail, three mutually orthogonal X, Y, and Z axes are defined. The Z axis is parallel to the vertical direction. Figure 17(a) is a schematic external perspective view of the electrolytic cell 20. Figure 17(b) is a plan view of the electrolytic cell 20 as observed from a direction perpendicular to the X and Z axes. Figure 17(c) is a diagram of the components of the electrolytic cell 20, specifically the parts related to the electrolysis of water.

[0117] The electrolytic cell 20 comprises a solid polymer film 21 and two electrodes, a cathode 22 and an anode 23, that sandwich the solid polymer film 21. The solid polymer film 21, the cathode 22 and the anode 23 are housed within the case of the electrolytic cell 20. In this embodiment, the case of the electrolytic cell 20 has a cylindrical shape, and of the top and bottom surfaces of the cylinder as the case shape of the electrolytic cell 20, one is surface SF1 and the other is surface SF2. The bottom surface of the cylinder is also called the bottom surface. Surfaces SF1 and SF2 are opposing planes and are parallel to the X and Y axes. Here, it is assumed that surface SF1 is the top surface and surface SF2 is the bottom surface. The direction from the positive side to the negative side of the Z axis corresponds to downward (i.e., the direction of gravity), and therefore the top surface SF1 is located on the positive side of the Z axis than the bottom surface SF2. The outer shapes of the top surface SF1 and the bottom surface SF2 are circles of the same size.

[0118] Within the case of the electrolytic cell 20, a solid polymer film 21, a cathode 22, and an anode 23 are arranged between the upper surface SF1 and the lower surface SF2. In this case, the cathode 22 is positioned between the solid polymer film 21 and the upper surface SF1, and the anode 23 is positioned between the solid polymer film 21 and the lower surface SF1. SF2 They are positioned between them. Although not clear from Figure 17(c), the solid polymer film 21, cathode 22, and anode 23 may each have a disc shape with thickness in the Z-axis direction.

[0119] In the electrolytic cell 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 a pipe 30 (see Figure 1), and water is supplied from the tank 10 through the pipe 30. The electrolytic cell power supply circuit 61 (see Figure 1) can supply a constant current to the electrolytic cell 20 by applying a positive voltage to the anode 23 relative to the potential of the cathode 22. The electrolytic cell 20 electrolyzes the water supplied to the input port 24 based on the supplied current. Hydrogen generated at the cathode 22 by the electrolysis of water is output from the upper output port 25. Oxygen generated at the anode 23 by 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 water supplied to the input port 24 (water that was not electrolyzed) is output from the upper output port 25 or the lower output port 26.

[0120] The upper output port 25 is connected to a water separation trap 40 (see Figure 1), and the hydrogen and water output from the upper output port 25 are sent to the water separation trap 40. As described above, the water sent to the water separation trap 40 is returned to the tank 10 via piping 32 and exhaust trap 13. The lower output port 26 is connected to piping 31 (see Figure 1). The oxygen and water output from the lower output port 26 are sent to the replenishment port 11 via piping 31. As a result, the water output from the lower output port 26 is returned to the tank 10 through the replenishment port 11.

[0121] The installation position of the temperature-measuring element 81 (i.e., the measurement target position) may be set on the upper surface SF1 or on the lower surface SF2. Setting the measurement target position on the upper surface SF1 means installing and fixing the temperature-measuring element 81 to the measurement target position on the upper surface SF1 in a manner that it is in contact with the upper surface SF1, in which case the temperature-measuring element 81 is located on the upper side of the upper surface SF1. Setting the measurement target position on the lower surface SF2 means installing and fixing the temperature-measuring element 81 to the measurement target position on the lower surface SF2 in a manner that it is in contact with the lower surface SF2, in which case the temperature-measuring element 81 is located on the lower side of the lower surface SF2.

[0122] Furthermore, it is preferable to install the temperature measuring element 81 in the center of surface SF1 or SF2 rather than at the edge of surface SF1 or SF2. Refer to Figure 17(d) to explain the preferred position for measurement.

[0123] In Figure 17(d), distance d1 REF This represents the minimum distance from the center position 620 of the top surface SF1 to the edge of the top surface SF1. If the outer shape of the top surface SF1 is a circle (perfect circle), the distance d1 REF This coincides with the radius of the upper surface SF1. An electrolytic cell 20 whose outer shape of the upper surface SF1 differs from that of a circle may be provided in the hydrogen generator 1. For example, when the outer shape of the upper surface SF1 is a square, the distance between the midpoint of one side of the square and the center position 620 is distance d1. REF This is the case. On the upper surface SF1, a predetermined distance d1 from the center position 620 TH The area within is referred to as region 625. That is, the distance between any position within region 625 and the center position 620 is distance d1. TH The following applies: When the measurement target position is set on the upper surface SF1, it is preferable to set the measurement target position within region 625.

[0124] Here, “d1 TH / d1 REF The equation =M” holds true. Therefore, when the measurement target position is set within region 625 on the upper surface SF1, the distance d1 REF The distance from the center position 620 to the measurement target position (≤ d1 TH The ratio of ) is less than or equal to M. M has a value less than 1, for example, "M=1 / 2". The condition "M=1 / 2" is not mandatory; for example, "M=3 / 5" or "M=1 / 3" would also be acceptable, but it is preferable to set the measurement target position as close as possible to the center position 620.

[0125] In Figure 17(d), the distance d2 REF This represents the minimum distance from the center position 630 of the lower surface SF2 to the edge of the lower surface SF2. If the outer shape of the lower surface SF2 is a circle (perfect circle), the distance d2 REFThis coincides with the radius of the lower surface SF2. An electrolytic cell 20 in which the outer shape of the lower surface SF2 differs from that of a circle may be provided in the hydrogen generator 1. For example, when the outer shape of the lower surface SF2 is a square, the distance between the midpoint of one side of the square and the center position 630 is distance d2 REF This is the result. On the lower surface SF2, a predetermined distance d2 from the center position 630. TH The area within is referred to as region 635. That is, the distance between any position within region 635 and the center position 630 is distance d2. TH The following applies: When the measurement target position is set on the lower surface SF2, it is preferable to set the measurement target position within region 635.

[0126] Here, “d2 TH / d2 REF The equation =M” holds true. Therefore, when the measurement target position is set within region 635 on the lower surface SF2, the distance d2 REF The distance from the center position 630 to the measurement target position (≤ d2 TH The ratio of ) is less than or equal to M. As mentioned above, M has a value less than 1, for example, "M=1 / 2". The condition "M=1 / 2" is not mandatory; for example, "M=2 / 5" or "M=1 / 3" would also be acceptable, but it is preferable to set the measurement target position as close as possible to the center position 630.

[0127] Furthermore, as is mainly assumed in this embodiment, if the case of the electrolytic cell 20 has a cylindrical shape, then “d1 REF =d2 REF " and also "d1 TH =d2 TH "That's fine."

[0128] [Example EX2_2] Example EX2_2 will be described. The temperature-compensated detection conductivity EC is obtained using the electrode unit 12 (see Figure 5, etc.) according to the first embodiment. DET The temperature compensation technique according to the second embodiment was described on the premise that the following was derived. However, the temperature compensation technique according to the second embodiment is applicable to any conductivity detection device.

[0129] That is, the conductivity detection device according to the second embodiment, as shown in Figure 18, comprises a conductivity meter CM and a temperature sensor 80 including a temperature measuring element 81. The conductivity meter CM is connected to the temperature sensor 80, and the temperature sensor 80 measures the temperature T DET It receives a signal that represents this.

[0130] The conductivity meter CM may be any conductivity meter that detects (measures) the conductivity of the water in the tank 10. For example, the conductivity meter CM has first and second electrodes inserted into and spaced apart in the water in the tank 10, and detects the conductivity of the water in the tank 10 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. In this case, the conductivity meter CM uses the temperature sensor 80 to measure the temperature T DET Based on this, temperature compensation is performed for the detected conductivity. That is, the conductivity meter CM uses the amplitude of the AC current and the measurement temperature T DET Based on this, the conductivity of the water in tank 10, assuming that the liquid temperature is a predetermined reference temperature, may be determined as the conductivity with temperature compensation.

[0131] Furthermore, when using the configuration of the first embodiment, the conductivity meter CM will consist of an electrode unit 12 and a detection circuit 64 (Figure 11) or a detection circuit 64a (Figure 13).

[0132] [Example EX2_3] Example EX2_3 will be explained.

[0133] As previously mentioned, the external shapes of the upper surface SF1 and the lower surface SF2 are not limited to circles and are arbitrary. The external shapes of the upper surface SF1 and the lower surface SF2 may differ.

[0134] While it is assumed that surface SF1 is the upper surface and surface SF2 is the lower surface of surfaces SF1 and SF2, the positional relationship between surfaces SF1 and SF2 is not limited to this. For example, surface SF1 may be the lower surface and surface SF2 may be the upper surface. Surfaces SF1 and SF2 may be arranged side by side in the left-right direction. Furthermore, an anode 23 may be placed between surface SF1 and the solid polymer film 21, and a cathode 22 may be placed between surface SF2 and the solid polymer film 21.

[0135] Although an example of applying the conductivity detection device according to the present invention to a hydrogen generator 1 has been described above, the conductivity detection device according to the present invention can be applied to any application requiring the detection of the conductivity of a liquid in a tank. For example, the conductivity detection device according to the present invention may be applied to a functional water production apparatus that produces various types of functional water. Furthermore, the liquid in the tank may be something other than water.

[0136] The embodiments of the present invention can be modified in various ways as appropriate within the scope of the technical idea set forth in the claims. The embodiments described above are merely examples of embodiments of the present invention, and the meaning of the terms of the present invention or each constituent element is not limited to those described above. The specific numerical values ​​shown in the above description are merely examples and can, of course, be changed to various numerical values. [Explanation of Symbols]

[0137] 1. Hydrogen generator CS cabinet 10 tanks 10R Water-holding space 11 Supply port 12 Electrode Units 13 Exhaust trap 14. Check valve 20 electrolytic cells 21 Solid polymer membrane 22 Cathode 23 Anode 24 input ports 25. Upward output port 26 Downward output port SF1 top SF2 bottom side 30-32 Piping 33 Drain piping 40 Water Separation Traps 41 Hydrogen piping 42 Hair Dryer 50-53 Hydrogen piping 54 Water discharge prevention filter 55 Solenoid valve 56 Safety valve 57 Pressure Sensor 58 Hydrogen Generator 59 Hydrogen release port 60 Control Display Unit 61 Electrolytic Cell Power Supply Circuit 62 Display section 63 Alarm output section 64. Water level and conductivity detection circuit 70 signal ports 71 power ports 72 drain ports 80 Temperature Sensor 81 Temperature measuring element 110 Reference electrode 111-113 Detection electrodes 110a~113a Covered portion 110b~113b Exposed part 120 Electrode support 130 Wiring group 210 AC voltage source 220~222 IV conversion section 230 Water level determination section 240 Conductivity conversion section CM conductivity meter

Claims

1. A water level and conductivity detection device comprising a reference electrode inserted into a tank in which water is to be contained and one or more detection electrodes, wherein the water level in the tank is detected by detecting whether or not there is conductivity between the reference electrode and the one or more detection electrodes, The one or more detection electrodes include a target detection electrode covered with an insulator. Of the reference electrode, the electrode portion other than the reference exposed portion including the lower end of the reference electrode, and of the target detection electrode, the electrode portion other than the detection exposed portion including the lower end of the target detection electrode, are covered with an insulator. The water level and conductivity detection device is The conductivity of the water in the tank is detected using the reference electrode and the target detection electrode. The system includes a temperature sensor that measures the temperature of an electrolytic cell that generates hydrogen by electrolyzing water supplied from the tank, and performs temperature compensation for the detected conductivity based on the measured temperature of the electrolytic cell. , water level and conductivity detection device.

2. The lower end of the reference electrode is closer to the bottom surface of the tank than the lower end of the target detection electrode. A detection circuit is provided that detects whether the water level in the tank is higher than the lower end of the target detection electrode based on the current between the reference electrode and the target detection electrode when an AC voltage is applied between the reference electrode and the target detection electrode, and detects the conductivity of the water in the tank based on the current when the water level in the tank is higher than the lower end of the target detection electrode. The water level and conductivity detection device according to claim 1.

3. The one or more detection electrodes are provided, and each set of detection electrodes is at a different distance from the bottom surface of the tank. The lower end of the reference electrode is closer to the bottom surface of the tank than the lower end of each detection electrode. The detection circuit detects whether the water level in the tank is higher than the lower end of the 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, for each detection electrode. The water level and conductivity detection device according to claim 2.

4. The target detection electrode is the detection electrode among the plurality of detection electrodes that is closest to the bottom surface of the tank. The water level and conductivity detection device according to claim 3.

5. In the case of a detection electrode among the plurality of detection electrodes that is different from the target detection electrode, the electrode portion other than the exposed portion including the lower end of the detection electrode is covered with an insulator. The water level and conductivity detection device according to claim 3.

6. The reference electrode and the one or more detection electrodes extend downward from the electrode support that supports the reference electrode and the one or more detection electrodes. In the vertical direction, the reference exposed portion and the detection exposed portion have a length. The water level and conductivity detection device according to claim 1.

7. In the vertical direction, the length of the reference exposed portion and the length of the detected exposed portion are each greater than 0 and less than or equal to 10 mm. The water level and conductivity detection device according to claim 6.

8. The reference electrode has a reference exposed portion and a reference covered portion which is the electrode portion from the electrode support to the reference exposed portion. The aforementioned target detection electrode has a detection exposure portion and a detection covering portion which is the electrode portion from the electrode support to the detection exposure portion. The reference covering portion and the detection covering portion are covered with an insulator. In the vertical direction, the length of the reference exposed portion is shorter than the length of the reference covered portion, and the length of the detection exposed portion is shorter than the length of the detection covered portion. The water level and conductivity detection device according to claim 6.

9. A tank in which water is to be contained, An electrolytic cell that generates hydrogen by electrolyzing water supplied from the aforementioned tank, A water level and conductivity detection device according to any one of claims 1 to 8, A hydrogen generator comprising piping for circulating water between the tanks and between the electrolytic cells, The electrolytic cell has a first surface and a second surface facing each other, and the anode and cathode of the electrolytic cell are arranged between the first surface and the second surface. The temperature of the electrolytic cell is measured by installing the temperature-measuring element in the temperature sensor on the first or second surface. , hydrogen generator.

10. The anode, the cathode and the solid polymer film are housed in the case of the electrolytic cell, The two surfaces in the aforementioned case are the first surface and the second surface. The hydrogen generator according to claim 9.

11. In a conductivity detection device for detecting the conductivity of water in a tank, The system includes a temperature sensor that measures the temperature of an electrolytic cell that generates hydrogen by electrolyzing water supplied from the tank, and performs temperature compensation for the detected conductivity based on the measured temperature of the electrolytic cell. Conductivity detection device.

12. A tank in which water is to be contained, An electrolytic cell that generates hydrogen by electrolyzing water supplied from the aforementioned tank, The conductivity detection device according to claim 11, A hydrogen generator comprising piping for circulating water between the tanks and between the electrolytic cells, The electrolytic cell has a first surface and a second surface facing each other, and the anode and cathode of the electrolytic cell are arranged between the first surface and the second surface. The temperature of the electrolytic cell is measured by installing the temperature-measuring element in the temperature sensor on the first or second surface. , hydrogen generator.

13. The anode, the cathode, and the solid polymer film are housed within the case of the electrolytic cell. The two surfaces in the aforementioned case are the first surface and the second surface. The hydrogen generator according to claim 12.

14. A water level and conductivity detection method for detecting the water level in a tank by using a reference electrode inserted into a tank in which water is to be contained and one or more detection electrodes, and detecting whether or not there is conductivity between the reference electrode and the one or more detection electrodes, The one or more detection electrodes include a target detection electrode covered with an insulator, The electrode portion of the reference electrode, excluding the reference exposed portion including the lower end of the reference electrode, and the electrode portion of the target detection electrode, excluding the detection exposed portion including the lower end of the target detection electrode, are covered with an insulator. The conductivity of the water in the tank is detected using the reference electrode and the target detection electrode. The temperature of the electrolytic cell that generates hydrogen by electrolyzing water supplied from the tank is measured by a temperature sensor, and the detected conductivity is temperature-compensated based on the measured temperature of the electrolytic cell. A method for detecting water level and conductivity.

15. The water level and conductivity detection method is used in a hydrogen generator comprising the tank and the electrolytic cell and piping for circulating water between the tank and the electrolytic cell, The electrolytic cell has a first surface and a second surface facing each other, and the anode and cathode of the electrolytic cell are arranged between the first surface and the second surface. The temperature of the electrolytic cell is measured by installing the temperature-measuring element in the temperature sensor on the first or second surface. The method for detecting water level and conductivity according to claim 14.

16. In a conductivity detection method for detecting the conductivity of water in a tank, The temperature of the electrolytic cell that generates hydrogen by electrolyzing water supplied from the tank is measured by a temperature sensor, and the detected conductivity is temperature-compensated based on the measured temperature of the electrolytic cell. Conductivity detection method.

17. The conductivity detection method is used in a hydrogen generator comprising the tank and the electrolytic cell and piping for circulating water between the tank and the electrolytic cell, The electrolytic cell has a first surface and a second surface facing each other, and the anode and cathode of the electrolytic cell are arranged between the first surface and the second surface. The temperature of the electrolytic cell is measured by installing the temperature-measuring element in the temperature sensor on the first or second surface. The conductivity detection method according to claim 16.

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