Water leakage sensor, water leakage detection system, and power storage device

Abstract

In a water leakage sensor 10 constituted of a printed circuit board on which a first electrode pattern 11p and a second electrode pattern 12p are formed, the second electrode pattern 12p is formed at an arrangement position in a B-layer pattern Bb of the printed circuit board, said arrangement position partially overlapping the arrangement position of the first electrode pattern 11p formed inside an A-layer pattern Bt of the printed circuit board. A plurality of through-holes H1 are formed penetrating, in a non-conductive manner, the first electrode pattern 11p formed inside the A-layer pattern Bt of the printed circuit board and the second electrode pattern 12p formed inside the B-layer pattern Bb of the printed circuit board. A plurality of the through-holes H1 are formed penetrating, in a non-conductive manner, the second electrode pattern 12p formed inside the A-layer pattern Bt of the printed circuit board and the first electrode pattern 11p formed inside the B-layer pattern Bb of the printed circuit board.

Description

Water Leakage Sensor, Water Leakage Detection System, Power Storage Device

[0001] The present disclosure relates to a water leakage sensor mounted on a printed circuit board, a water leakage detection system, and a power storage device.

[0002] A common water leakage sensor detects water leakage by arranging two electrodes, detecting that a conductive liquid such as water enters between the electrodes to form a conductive path, and the resistance between the electrodes decreases.

[0003] Fans are often used to cool heat-generating objects such as storage batteries and loads. When a fan is used in a high-humidity environment, or a water cooling system is installed near the fan, water may intrude from the air supply inlet of the fan. Since water that has intruded into the fan is sprayed in the form of mist, if a water leakage sensor is disposed parallel to the fan to face the fan, it is easy to detect water leakage from the fan.

[0004] When using the linear water leakage sensor 10 as shown in FIG. 1, it is difficult to install the water leakage sensor parallel to the fan so as to face the fan, and when installing the water leakage sensor parallel to the fan, a special holder for routing and fixing the linear water leakage sensor 10 is required. In addition, it is difficult to connect the linear water leakage sensor 10 to a circuit board, and additional processing is required for termination treatment. Preparing a dedicated holder and a connector compatible with the linear water leakage sensor 10 leads to an increase in cost. In addition, the processing cost for termination treatment also increases.

[0005] Patent Document 1 discloses a water leakage sensor formed by disposing a pair of comb-shaped electrodes oppositely on an insulator. This water leakage sensor uses a plate-shaped insulator, but if the plate-shaped insulator is installed parallel to the fan so as to face the fan, the cooling air blown from the fan to the heat-generating object is blocked by the plate-shaped insulator, and the cooling effect for the heat-generating object is greatly reduced.

[0006] Japanese Unexamined Patent Application Publication No. 2014-66533

[0007] The present disclosure has been made in view of such circumstances, and an object of the present disclosure is to provide a technique that allows a water leakage sensor to be installed on a wide range of planes at low cost.

[0008] To solve the above problems, a water leak sensor according to one aspect of the present disclosure is a water leak sensor comprising a printed circuit board on which a first electrode pattern and a second electrode pattern are formed, wherein the first electrode pattern is formed on at least one A layer which is a layer of the printed circuit board, the first electrode pattern is formed on at least one B layer which is separate from the A layer of the printed circuit board and is in electrical contact with the first electrode pattern formed on the A layer, the second electrode pattern is formed on the A layer of the printed circuit board, the second electrode pattern is formed on the B layer which is in electrical contact with the second electrode pattern formed on the A layer, and the second electrode pattern is formed at an arrangement position on the B layer of the printed circuit board which partially overlaps with the arrangement position of the first electrode pattern formed on the A layer of the printed circuit board, and the printed circuit board The first electrode pattern is formed at a position in the B layer of the printed circuit board that partially overlaps with the position of the second electrode pattern formed in the A layer of the printed circuit board, and there are multiple through holes that allow the first electrode pattern formed in the A layer of the printed circuit board and the second electrode pattern formed in the B layer of the printed circuit board to pass through without conducting electricity, and the first electrode pattern is conductive to a first fixed potential, and the second electrode pattern is conductive to a second fixed potential, and when a conductive liquid enters between the first electrode pattern and the second electrode pattern, the insulation resistance between the first electrode pattern and the second electrode pattern decreases.

[0009] According to this disclosure, leak sensors can be installed on a wide range of flat surfaces at low cost.

[0010] This figure shows a cross-sectional view of a linear water leak sensor. This figure shows the A-layer pattern and B-layer pattern of the water leak sensor according to the embodiment. This figure shows the circuit configuration of a water leak detection system using the water leak sensor according to the embodiment. This figure illustrates an example of using the water leak sensor according to the embodiment. This figure shows the three-layer patterns of a modified water leak sensor.

[0011] Figure 1 shows a cross-sectional view of a linear water leak sensor 10. The linear water leak sensor 10 is highly flexible and can be installed in various shapes and sizes. The linear water leak sensor 10 comprises a first electrode 11, a second electrode 12, a first internal braid 13a, a second internal braid 13b, and an external braid 13c. For example, soft copper stranded wire is used for the first electrode 11 and the second electrode 12. The first electrode 11 is covered by the first internal braid 13a, the second electrode 12 is covered by the second internal braid 13b, and furthermore, the first internal braid 13a and the second internal braid 13b are covered by the external braid 13c. For example, special water-absorbing plastic fibers are used for the first internal braid 13a, the second internal braid 13b, and the external braid 13c. The first internal braid 13a, the second internal braid 13b, and the external braid 13c have sufficient insulating performance when dry. The first electrode 11, covered by the first internal braid 13a, and the second electrode 12, covered by the second internal braid 13b, are arranged spirally within the external braid 13c.

[0012] Because the linear water leak sensor 10 has a certain thickness, it is difficult to install it on a wide area of ​​flat surface. Also, as mentioned above, the linear water leak sensor 10 has a high cost for the connection part to the circuit board.

[0013] Figure 2 shows the A-layer pattern and B-layer pattern of the leak sensor 10 according to the embodiment. The leak sensor 10 according to the embodiment is composed of a printed circuit board on which a first electrode pattern 11p and a second electrode pattern 12p are formed. In Figure 2, the A-layer pattern Bt of the A-layer, which is the surface layer of the printed circuit board, and the B-layer pattern Bb of the B-layer, which is the back surface of the printed circuit board, are drawn symmetrically with respect to a vertical center line.

[0014] Printed circuit boards are often coated with moisture-resistant coatings or solder resist to protect against humidity. For the first electrode pattern 11p and the second electrode pattern 12p, copper wires plated with tin, gold, nickel, or palladium are used to protect against humidity.

[0015] A first electrode pattern 11p is formed within the A-layer pattern Bt of the printed circuit board. A second electrode pattern 12p is formed in the B-layer pattern Bb of the printed circuit board, which is electrically connected to the first electrode pattern 11p formed in the A-layer pattern Bt via a first through-hole a1. A second electrode pattern 12p is formed within the A-layer pattern Bt of the printed circuit board. A second electrode pattern 12p is formed in the B-layer pattern Bb of the printed circuit board, which is electrically connected to the second electrode pattern 12p formed in the A-layer pattern Bt via a second through-hole b1.

[0016] The first through-hole a1 and the second through-hole b1 are plated with a conductive material, and electrically connect the electrode patterns of the A-layer pattern Bt and the B-layer pattern Bb of the printed circuit board.

[0017] The first electrode pattern 11p and the second electrode pattern 12p are each formed in a comb shape, and their respective multiple electrode fingers are arranged opposite each other so as to interlock with one another.

[0018] A second electrode pattern 12p is formed at the position in the B layer pattern Bb of the printed circuit board corresponding to the position in the first electrode pattern 11p formed in the A layer pattern Bt of the printed circuit board. Similarly, a first electrode pattern 11p is formed at the position in the B layer pattern Bb of the printed circuit board corresponding to the position in the second electrode pattern 12p formed in the A layer pattern Bt of the printed circuit board. Viewed from the A layer pattern Bt of the printed circuit board, the second electrode pattern 12p is formed on the back surface of the first electrode pattern 11p, and the first electrode pattern 11p is formed on the back surface of the second electrode pattern 12p.

[0019] Multiple through-holes H1 are provided that allow a non-conductive connection between the first electrode pattern 11p formed in the A-layer pattern Bt of the printed circuit board and the second electrode pattern 12p formed in the B-layer pattern Bb of the printed circuit board. Similarly, multiple through-holes H1 are provided that allow a non-conductive connection between the second electrode pattern 12p formed in the B-layer pattern Bb of the printed circuit board and the first electrode pattern 11p formed in the B-layer pattern Bb of the printed circuit board. Note that, in order to simplify the drawing, only one through-hole is labeled with a reference numeral.

[0020] The through-holes H1 are spaced equally apart in the first electrode pattern 11p and the second electrode pattern 12p. However, the spacing of the through-holes H1 does not necessarily have to be equal. Each through-hole H1 is not plated with a conductive material and does not conduct electricity between the electrode patterns of the A-layer pattern Bt and the B-layer pattern Bb of the printed circuit board. The size, shape, number, and spacing of the through-holes H1 can be arbitrarily determined by the designer. For example, the shape of the through-holes H1 is not limited to round; it may be square, hexagonal, or octagonal.

[0021] A connector CN1 is installed on the A-layer pattern Bt of the printed circuit board. The connector CN1 is a component for connecting the first electrode pattern 11p to a first external wiring connected to a first fixed potential (e.g., power supply potential VDD), and for connecting the second electrode pattern 12p to a second external wiring connected to a second fixed potential (e.g., ground potential GND). The connector CN1 may also be installed on the B-layer pattern Bb of the printed circuit board.

[0022] Figure 3 shows the circuit configuration of a water leak detection system 1 using a water leak sensor 10 according to an embodiment. The water leak detection system 1 comprises a water leak sensor 10 and a water leak detection circuit 20. The water leak detection circuit 20 comprises an external resistor R1 and a control unit 21.

[0023] The first electrode pattern 11p of the water leak sensor 10 is installed to conduct to the power supply potential VDD. The second electrode pattern 12p of the water leak sensor 10 is installed to conduct to the ground potential GND. The first electrode pattern 11p and the second electrode pattern 12p are connected via connector CN1 to wiring connected to the circuit board on which the water leak detection circuit 20 is mounted.

[0024] An external resistor R1 is connected between the power supply potential VDD and the first electrode pattern 11p. The insulation resistance between the first electrode pattern 11p and the second electrode pattern 12p, along with the external resistor R1, constitute a resistive voltage divider circuit. When a conductive liquid such as water enters between the first electrode pattern 11p and the second electrode pattern 12p, the insulation resistance decreases. The greater the amount of water dripped in, the greater the decrease in insulation resistance between the electrodes. The voltage division point N1 between the external resistor R1 and the insulation resistance is connected to the AD port of the control unit 21.

[0025] The control unit 21 is composed of a microcontroller. The microcontroller has a built-in A / D converter, which converts the analog voltage input to the AD port into a digital value. The A / D converter may also be external. In that case, the voltage of the first electrode pattern 11p (hereinafter referred to as the detected voltage V1), which is the voltage at the voltage divider point N1, is converted into a digital value by the external A / D converter and then input to the microcontroller.

[0026] The control unit 21 determines whether or not there is a water leak based on the detected voltage V1. If the detected voltage V1 is lower than a preset water leak detection threshold voltage Vth1, the control unit 21 determines that there is a water leak, and if the detected voltage V1 is equal to or greater than the water leak detection threshold voltage Vth1, it determines that it is normal (no water leak).

[0027] In the example shown in Figure 3, a resistor R2 is installed on the A-layer pattern Bt of the printed circuit board to electrically connect the first electrode pattern 11p and the second electrode pattern 12p. The resistor R2 is connected to detect a physical break in the first electrode pattern 11p or the second electrode pattern 12p, or a disconnection of connector CN1. Hereinafter, physical breaks and disconnections of connector CN1 will be collectively referred to simply as "breaks." When the resistor R2 is not connected, both the dry state and the break appear to the control unit 21 as the same high-impedance state. By connecting the resistor R2, the impedance of the dry state can be reduced to the impedance of the break.

[0028] When resistor R2 is connected, current flows through resistor R2, so it is desirable to use a high resistance resistor for R2. Alternatively, a switch may be connected in series with an external resistor R1, and the control unit 21 may operate the switch intermittently.

[0029] When resistor R2 is connected, the wire break detection threshold voltage Vth2 is set to a value higher than the water leak detection threshold voltage Vth1. The control unit 21 determines that there is a water leak if the detected voltage V1 is lower than the water leak detection threshold voltage Vth1. The control unit 21 determines that it is normal (no water leak) if the detected voltage V1 is within the range between the water leak detection threshold voltage Vth1 and the wire break detection threshold voltage Vth2. The control unit 21 determines that there is a wire break in the water leak sensor 10 if the detected voltage V1 is higher than the wire break detection threshold voltage Vth2.

[0030] In the water leak detection system 1 shown in Figure 3, the water leak sensor 10 is positioned below the resistive voltage divider circuit. However, the water leak sensor 10 may also be positioned above the resistive voltage divider circuit. In that case, the second electrode pattern 12p of the water leak sensor 10 is installed to conduct to the power supply potential VDD. An external resistor R1 is connected between the first electrode pattern 11p of the water leak sensor 10 and the ground potential GND. The wire break detection threshold voltage Vth2 is set to a value lower than the water leak detection threshold voltage Vth1.

[0031] The control unit 21 determines that there is a water leak if the detected voltage V1 is higher than the water leak detection threshold voltage Vth1. The control unit 21 determines that it is normal (no water leak) if the detected voltage V1 is within the range between the water leak detection threshold voltage Vth1 and the wire break detection threshold voltage Vth2. The control unit 21 determines that a wire break has occurred in the water leak sensor 10 if the detected voltage V1 is lower than the wire break detection threshold voltage Vth2.

[0032] The cases where the water leak sensor 10 is positioned below the resistor voltage divider circuit and where it is positioned above it can be summarized as follows: The first electrode pattern 11p conducts to the first fixed potential via the external resistor R1. The second electrode pattern 12p conducts to the second fixed potential. The control unit 21 determines that there is a water leak if the detected voltage V1 is located on the second fixed potential side of the water leak detection threshold voltage Vth1. The control unit 21 determines that it is normal (no water leak) if the detected voltage V1 is within the range between the water leak detection threshold voltage Vth1 and the wire break detection threshold voltage Vth2. The control unit 21 determines that there is a wire break in the water leak sensor 10 if the detected voltage V1 is located on the first fixed potential side of the wire break detection threshold voltage Vth2.

[0033] Figure 4 is a diagram illustrating an example of the use of the water leak sensor 10 according to the embodiment. The example shown in Figure 4 shows an example in which the water leak sensor 10 according to the embodiment is installed inside the energy storage device 5. The energy storage device 5 is composed of a BBU (Battery Backup Unit) and includes a battery pack 30, a fan 40, and the water leak sensor 10. The energy storage device 5 is used, for example, as a backup power supply system for a data center and is used as a power source during a power outage until the emergency generator starts up.

[0034] The battery pack 30 includes a battery pack containing multiple cells connected in series. The cells can be lithium-ion battery cells, nickel-metal hydride battery cells, lead-acid battery cells, etc. The battery pack 30 is connected to a DC bus to which numerous servers and storage devices are connected, and in the event of a power outage, it supplies DC power to the numerous servers and storage devices via the DC bus. An AC / DC converter connected to the commercial power grid is connected to the DC bus, and under normal circumstances, DC power is supplied from the AC / DC converter to the numerous servers and storage devices via the DC bus.

[0035] Multiple energy storage devices 5 are used in sets. Multiple energy storage devices 5 are connected in parallel and housed in a first shelf, which is then installed in a rack. A second shelf, which houses multiple AC / DC converters connected in parallel, is installed on the upper shelf of the rack.

[0036] The battery pack 30, fan 40, and water leak sensor 10 are housed in a metal casing Ho. The fan 40 is positioned opposite the battery pack 30 and blows cooling air onto the battery pack 30 to air cool it.

[0037] Since the AC / DC converter is basically always in operation, a water cooling system is used to cool it. If the second shelf, which houses the water-cooled AC / DC converter, is installed on the upper shelf of the rack, water droplets may drip from the second shelf. The housing Ho of the energy storage device 5 and the first shelf are provided with air intakes for the fan 40, and water may enter the air intakes of the fan 40. In that case, the fan 40 will spray the invading water over a wide area.

[0038] The water leak sensor 10, according to an embodiment mounted on a printed circuit board, is positioned between the battery pack 30 and the fan 40. Specifically, the A-layer pattern Bt of the printed circuit board is positioned to face the fan 40 at a predetermined distance, and the B-layer pattern Bb of the printed circuit board is positioned to face the battery pack 30 without contact. As shown in Figure 4, when the battery pack 30 and the fan 40 are arranged horizontally, the printed circuit board on which the water leak sensor 10 is mounted is positioned vertically between them. When the battery pack 30 and the fan 40 are arranged vertically, the printed circuit board on which the water leak sensor 10 is mounted is positioned horizontally between them. The printed circuit board on which the water leak sensor 10 is mounted is fixed to the housing Ho by screws or the like without contacting the battery pack 30. The housing Ho may have a protrusion 50 formed in the direction of the water leak sensor. In this configuration, the printed circuit board can be fixed to this protrusion 50.

[0039] The printed circuit board on which the water leak sensor 10 is mounted is sized to cover the airflow range of the fan 40 and receives the cooling air from the fan 40. However, because the printed circuit board on which the water leak sensor 10 is mounted has many through holes H1, the cooling air from the fan 40 reaches the battery pack 30.

[0040] When water is sprayed from the fan 40, water accumulates in the through-holes H1 of the printed circuit board. This reduces the insulation resistance between the first electrode pattern 11p in the A-layer pattern Bt and the second electrode pattern 12p in the B-layer pattern Bb of the printed circuit board, or between the second electrode pattern 12p in the A-layer pattern Bt and the first electrode pattern 11p in the B-layer pattern Bb of the printed circuit board. In addition, if sufficient water adheres to the insulating region between the first electrode pattern 11p and the second electrode pattern 12p in the A-layer pattern Bt of the printed circuit board, the insulation resistance will also decrease. The same applies to the B-layer pattern Bb of the printed circuit board. As a result, water can be detected not only by a decrease in the insulation resistance between electrode patterns in the A-layer pattern Bt, but also by a decrease in the insulation resistance between electrode patterns in the A-layer pattern and the B-layer pattern, enabling more precise detection of water leaks. Furthermore, because the water is held in the through-holes, accurate water detection is possible even when the water leak sensor is placed vertically, without the water sliding off.

[0041] As described above, according to this embodiment, the water leak sensor 10 can be manufactured at low cost by constructing the water leak sensor 10 on a printed circuit board on which the first electrode pattern 11p and the second electrode pattern 12p are formed. General-purpose parts can be used for the printed circuit board, connector CN1, and resistor R2, which reduces manufacturing costs. Additional processing for termination of connections, which is required in conventional linear water leak sensors, is also unnecessary, which reduces processing costs.

[0042] Furthermore, unlike linear leak sensors 10, the electrode pattern can be made thin and narrow, making it easy to install on a wide area of ​​flat surface. In addition, by providing multiple through holes H1, even when mounting the leak sensor 10 on a large printed circuit board, the leak sensor 10 can be installed while maintaining airflow to the object to be cooled.

[0043] Next, a modified example is shown with reference to Figure 5. The printed circuit board in Figure 5 has a three-layer structure, with the A-layer pattern Bt drawn on the surface layer A1 and the back layer A2, and the B-layer pattern Bb drawn on the inner layer B. This makes it possible to narrow the gap between the A-layer and B-layer, allowing for the detection of even smaller amounts of water droplets.

[0044] The present disclosure has been described above based on the embodiments. The embodiments are illustrative, and it is understood by those skilled in the art that various modifications can be made to the combinations of the respective constituent elements and processing processes, and such modifications also fall within the scope of the present disclosure.

[0045] In the above-described embodiments, an example has been described in which the first electrode pattern 11p and the second electrode pattern 12p are each formed in a comb shape in the A-layer pattern Bt or the B-layer pattern Bb of a printed circuit board. In this regard, the first electrode pattern 11p and the second electrode pattern 12p do not necessarily need to be formed in a comb shape. Any arrangement is acceptable as long as the first electrode pattern 11p and the second electrode pattern 12p are comprehensively arranged without contacting each other in the A-layer pattern Bt or the B-layer pattern Bb of the printed circuit board. For example, the first electrode pattern 11p and the second electrode pattern 12p may each be formed in a spiral shape, and the spiral-shaped second electrode pattern 12p may be arranged in the gap between the spiral-shaped first electrode pattern 11p.

[0046] As shown in Fig. 4, the water leakage sensor 10 configured with the printed circuit board according to the embodiment is not limited to the application to the power storage device 5, and can be applied to any application as long as there is a space where the printed circuit board can be installed.

[0047] Note that the embodiments may also be specified by the following items.

[0048] [Item 1] A water leak sensor (10) comprising a printed circuit board having a first electrode pattern (11p) and a second electrode pattern (12p) formed on it, wherein the first electrode pattern (11p) is formed on at least one A layer which is a layer of the printed circuit board, and the first electrode pattern (11p) which is electrically connected to the first electrode pattern (11p) formed on the A layer (Bt) is formed on at least one B layer (Bb) which is separate from the A layer of the printed circuit board, and the second electrode pattern (12p) which is electrically connected to the second electrode pattern (12p) formed on the A layer (Bt) is formed on the B layer (Bb) of the printed circuit board, and the second electrode pattern (12p) which is electrically connected to the second electrode pattern (12p) formed on the A layer (Bt) is formed at an arrangement position on the B layer (Bb) of the printed circuit board that partially overlaps with the arrangement position of the first electrode pattern (11p) formed on the A layer (Bt) of the printed circuit board, The first electrode pattern (11p) is formed at a position on the B layer (Bb) of the printed circuit board that partially overlaps with the position of the second electrode pattern (12p) formed on the A layer (Bt) of the printed circuit board, and there are a plurality of through holes (H1) that pass through the first electrode pattern (11p) formed on the A layer (Bt) of the printed circuit board and the second electrode pattern (12p) formed on the B layer (Bb) of the printed circuit board in a non-conductive manner, and the first electrode pattern (11p) is conductive to a first fixed potential, and the second electrode pattern (12p) is conductive to a second fixed potential, A water leak sensor (10) in which the insulation resistance between the first electrode pattern (11p) and the second electrode pattern (12p) decreases when a conductive liquid enters between them. This allows the water leak sensor (10) to be installed on a wide range of planes at low cost.[Item 2] The water leak sensor (10) according to Item 1, wherein the first electrode pattern (11p) and the second electrode pattern (12p) are each formed in a comb shape, and the multiple electrode fingers of each are arranged opposite each other so as to intersect each other. With this, the first electrode pattern (11p) and the second electrode pattern (12p) can be comprehensively arranged on the A layer (Bt) and B layer (Bb) of the printed circuit board, respectively. [Item 3] The water leak sensor (10) according to Item 1, wherein a resistor (R2) is installed on the printed circuit board to electrically connect the first electrode pattern (11p) and the second electrode pattern (12p). With this, a dry state and a broken wire can be clearly distinguished simply by monitoring the voltage of the first electrode pattern (11p). [Item 4] A water leak sensor (10) according to Item 1, wherein the first electrode pattern (11p) and a first external wiring connected to the first fixed potential are connected on the printed circuit board, and a connector (CN1) for connecting the second electrode pattern (12p) and a second external wiring connected to the second fixed potential is installed. This allows for easy connection to a circuit board that determines the presence or absence of water leakage. [Item 5] A water leak detection system (1) comprising: the water leak sensor (10) according to any one of Items 1 to 4; an external resistor (R1) connected between the first electrode pattern (11p) and the first fixed potential; and a control unit (21) that detects the voltage of the first electrode pattern (11p) and determines that there is water leakage if the detected voltage of the first electrode pattern (11p) is located on the second fixed potential side of a threshold voltage. This allows for the construction of a water leak detection system (1) that can detect water leakage over a wide area of ​​a plane at low cost. [Item 6] Energy storage device (5) comprising: a battery pack (30); a fan (40) positioned opposite the battery pack (30) for cooling the battery pack (30); and a water leak sensor (10) positioned between the battery pack (30) and the fan (40) as described in any one of items 1 to 4, wherein the A layer (Bt) of the printed circuit board on which the water leak sensor (10) is mounted is positioned opposite the fan (40) at a predetermined distance, and the B layer (Bb) of the printed circuit board is positioned opposite the battery pack (30) in a non-contact manner.According to this, the water leakage sensor (10) in the power storage device (5) can be installed on a wide range of flat surfaces at low cost.

[0049] The present disclosure is applicable to a water leakage sensor used in a power storage device.

[0050] 1 Water leakage detection system, 10 Water leakage sensor, 11 First electrode, 12 Second electrode, 11p First electrode pattern, 12p Second electrode pattern, 13a First inner braid, 13b Second inner braid, 13c Outer braid, Bt A-layer pattern of printed circuit board, Bb B-layer pattern of printed circuit board, H1 Through hole, R2 Resistor, a1 First through hole, b1 Second through hole, CN1 Connector, 20 Water leakage detection circuit, 21 Control unit, R1 External resistor, 5 Power storage device, Ho Housing, 30 Battery pack, 40 Fan, 50 Protruding portion.

Claims

1. A water leak sensor comprising a printed circuit board having a first electrode pattern and a second electrode pattern formed on it, wherein the first electrode pattern is formed on at least one A layer of the printed circuit board, the first electrode pattern is formed on at least one B layer of the printed circuit board that is electrically connected to the first electrode pattern formed on the A layer, the second electrode pattern is formed on the A layer of the printed circuit board, the second electrode pattern is formed on the B layer of the printed circuit board that is electrically connected to the second electrode pattern formed on the A layer, the second electrode pattern is formed at a position on the B layer of the printed circuit board that partially overlaps with the position on the first electrode pattern formed on the A layer of the printed circuit board, the first electrode pattern is formed at a position on the B layer of the printed circuit board that partially overlaps with the position on the second electrode pattern formed on the A layer of the printed circuit board, and there are a plurality of through holes that allow the first electrode pattern formed on the A layer of the printed circuit board and the second electrode pattern formed on the B layer of the printed circuit board to pass through without electrical connection. A leak sensor comprising a second electrode pattern formed in layer A of the printed circuit board and a plurality of through holes that pass through the first electrode pattern formed in layer B of the printed circuit board in a non-conductive manner, wherein the first electrode pattern is conductive to a first fixed potential, the second electrode pattern is conductive to a second fixed potential, and when a conductive liquid enters between the first electrode pattern and the second electrode pattern, the insulation resistance between the first electrode pattern and the second electrode pattern decreases.

2. The leak sensor according to claim 1, wherein the first electrode pattern and the second electrode pattern are each formed in a comb shape, and the plurality of electrode fingers of each are arranged opposite each other so as to intersect each other.

3. The leak sensor according to claim 1, wherein a resistor is installed on the printed circuit board to electrically connect the first electrode pattern and the second electrode pattern.

4. The leak sensor according to claim 1, wherein a connector is installed on the printed circuit board for connecting the first electrode pattern to a first external wiring connected to the first fixed potential, and for connecting the second electrode pattern to a second external wiring connected to the second fixed potential.

5. A water leak detection system comprising: a water leak sensor according to any one of claims 1 to 4; an external resistor connected between the first electrode pattern and the first fixed potential; and a control unit that detects the voltage of the first electrode pattern and determines that there is a water leak if the detected voltage of the first electrode pattern is located on the second fixed potential side of a threshold voltage.

6. An energy storage device comprising: a battery pack; a fan disposed opposite the battery pack for cooling the battery pack; and a water leak sensor according to any one of claims 1 to 4 disposed between the battery pack and the fan, wherein the A layer of the printed circuit board on which the water leak sensor is mounted is disposed opposite the fan at a predetermined distance, and the B layer of the printed circuit board is disposed opposite the battery pack in a non-contact manner.

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