JP7004634B2 - Leakage detector - Google Patents

Description

The present invention relates to the structure of a liquid leakage detection device, particularly a structure of a liquid leakage detection device using a constant voltage element or a constant current element.

As a method of detecting the occurrence of liquid leakage from air conditioning equipment, etc., when a current is passed through a liquid leakage detection band in which two conductors are arranged in parallel in a non-conducting state, and liquid leaks enter between the two conductors. A method of detecting liquid leakage by detecting a short circuit is used.

However, with such a leak detection method, although the leak can be detected, the location where the leak occurs cannot be detected. Therefore, a method of identifying the leak location by using a leak sensor in which three electrode wires insulated so as to allow liquid to pass through are arranged in parallel and the resistance values per unit length of the two electrode wires are different. Have been proposed (see, for example, Patent Documents 1 and 2).

On the other hand, liquid leakage monitoring may target not only a partitioned plane such as under the floor of a server room but also a complicated shape having a large number of spatial branches such as an air conditioning pipe. In the conventional liquid leakage detection method as described in Patent Documents 1 and 2, the leakage location is specified based on the resistance value per unit length of the electrode wire, so that the equipment and piping arranged in parallel are used. It is difficult to arrange the leak sensors in parallel according to the arrangement. Therefore, a method has been proposed in which each electrode wire and the detector are connected by an electric wire via a changeover switch, and the connection between the detector and each electrode wire is switched by the changeover switch to detect a leak (for example). , Patent Document 3).

Japanese Unexamined Patent Publication No. 8-271461 Special Fair 2-43130 Gazette Special Fair 7-119664 Gazette

However, if a leak detection device arranged in parallel is configured by the conventional technique as described in Patent Document 3, there is a problem that the number of changeover switches becomes large and the structure becomes complicated.

Therefore, an object of the present invention is to enable leakage monitoring of devices arranged in parallel with a simple configuration.

The liquid leakage monitoring device of the present invention is composed of a pair of conductive wires, and is connected to a liquid leakage detection band in which a current flows when a leak comes into contact between the conductive wires and a liquid leakage detection band, and an applied voltage is predetermined. A node having a constant voltage element that conducts when the conduction voltage value is reached, a liquid leakage detection unit in which a plurality of liquid leakage detection units including the liquid leakage detection unit are connected in parallel by a parallel connection line, and a liquid leakage detection unit connected to the parallel connection line of the liquid leakage detection unit. A power supply, a current detection unit that detects the input current value of the parallel connection line of the liquid leakage detection unit, and a determination unit that determines the occurrence of liquid leakage from the input current value detected by the current detection unit. The leak detection unit has a characteristic that each leak detection unit conducts according to an input voltage value, and each current conduction voltage value of each constant voltage element of each leak detection unit has its own. It is characterized by being different.

This makes it possible to monitor leaks from devices arranged in parallel with a simple configuration.

In the liquid leakage detection device of the present invention, the node of the liquid leakage detection unit is connected to a pair of start end side terminals to which the parallel connection lines are connected and a pair of conductive wires of the liquid leakage detection unit. The constant voltage element includes a pair of end-side terminals and a pair of connection lines connecting the start-end side terminal and the end-side terminal in parallel, and the constant voltage element is arranged so as to be interposed between any one or both connection lines. It may be done.

In this way, since the arrangement of the constant voltage element of the node can be variously changed according to the liquid to be detected, it is possible to detect the leak according to the liquid to be detected.

In the liquid leakage detection device of the present invention, the power supply applies a standby voltage of a predetermined voltage value to the parallel connection line of the liquid leakage detection unit, and the determination unit uses the input current detected by the current detection unit. By comparing the value with a predetermined threshold value, the occurrence of liquid leakage in at least one liquid leakage detection unit may be determined.

As described above, with a simple configuration in which the standby voltage value is set to a predetermined voltage value, it is possible to determine the occurrence of liquid leakage in a short time.

In the liquid leakage detection device of the present invention, the power supply outputs a voltage corresponding to the voltage command value input from the determination unit, and the determination unit outputs the voltage command value to the power supply as the standby voltage value. The input voltage value of the leak detection unit is varied before and after the standby voltage value, and calculated from the voltage command value or the input voltage value and the input current value detected by the current detection unit. By comparing the conducted conduction or resistance value with a predetermined threshold value, it may be determined that a leak has occurred in at least one of the leak detection units.

In this way, the conductance or resistance value is calculated by fluctuating the input voltage value of the liquid leakage detection unit before and after the standby voltage value, and the leakage is determined by this. Therefore, the leakage is determined by a physical quantity different from the input current value. Can be determined.

In the liquid leakage detection device of the present invention, the power supply outputs a voltage corresponding to the voltage command value input from the determination unit, and the determination unit sweeps the voltage command value output to the power supply. The input voltage value of the leak detection unit is swept, and each of the leakage detection units is made conductive in ascending order of the conduction voltage value, and the voltage command value or the input voltage value and the input detected by the current detection unit are performed. By comparing the conductance or resistance value calculated from the current value with a predetermined threshold value, it is determined that a leak has occurred in at least one of the leak detecting units in a conducting state. You may.

In this way, the conductance or resistance value is calculated by sweeping the input voltage value of the liquid leakage detection unit, and the leakage is determined by this. Therefore, the leakage can be determined by a physical quantity different from the input current value. can.

In the liquid leakage detection device of the present invention, the power supply outputs a voltage corresponding to the voltage command value input from the determination unit, and the determination unit sweeps the voltage command value output to the power supply. The input voltage value of the liquid leakage detection unit is swept, and each of the liquid leakage detection units is made conductive in ascending order of the conduction voltage value, and the range up to the liquid leakage detection unit of one of the liquid leakage detection units is in a conductive state. When the range from the input current value detected by the current detection unit to the other leak detection unit having the next highest conduction voltage value after the one leak detection unit is set to the conduction state. By using the input current value detected by the current detection unit to calculate the conductance of one of the leak detection units and comparing the calculated conductance with a predetermined threshold value, the leaked liquid is generated. The leak detection unit may be specified.

In this way, the input voltage value of the leak detection unit is swept, the leak detection units are conducted in ascending order of conduction voltage value, the conductance of each leak detection unit is calculated, and the calculated conductance is set as a predetermined threshold value. By comparing, it is possible to identify the leak detection unit in which the leak has occurred. This makes it possible to improve the detection reliability of the leaked portion with a simple configuration.

The liquid leakage detection device of the present invention is composed of a pair of conductive wires, and is connected to a liquid leakage detection band in which a current flows when a leak comes into contact between the conductive wires and a liquid leakage detection band, and an applied voltage is predetermined. A leak detection unit in which a node having a constant voltage element that conducts when the conduction voltage value is reached and a plurality of leak detection units including the leakage detection unit are connected in parallel by a parallel connection line, and a resistor is connected between the conductive wires at the ends. The power supply connected to the parallel connection line of the liquid leakage detection unit, the voltage detection unit that detects the input voltage value of the parallel connection line of the liquid leakage detection unit, and the input detected by the voltage detection unit. A determination unit for determining the occurrence of liquid leakage from a voltage value is provided, and the liquid leakage detection unit has a characteristic that each liquid leakage detection unit conducts according to the input voltage value, and each liquid leakage detection unit is provided. It is characterized in that the conduction voltage value of each of the constant voltage elements of the unit is different.

This makes it possible to monitor leaks from devices arranged in parallel with a simple configuration.

In the liquid leakage detection device of the present invention, the power supply inputs a standby current of a predetermined current value to the liquid leakage detection unit, and the determination unit inputs the input voltage value detected by the voltage detection unit to a predetermined threshold value. The occurrence of leakage may be determined by comparison with.

As described above, with a simple configuration in which the standby current value is set to a predetermined current value, it is possible to determine the occurrence of liquid leakage in a short time.

The liquid leakage detection device of the present invention is composed of a pair of conductive wires, a liquid leakage detection band in which a current flows when a leak comes into contact between the conductive wires, and a liquid leakage detection band connected to the liquid leakage detection band. A liquid leakage detection unit in which a plurality of liquid leakage detection units including a node having a constant current element that limits the current current value of the current current value to the current limit value are connected in parallel by a parallel connection line, and the parallel connection of the liquid leakage detection unit. A power supply that is connected to a wire and applies a voltage to the leak detection unit, a current detection unit that detects the energization current value of the parallel connection line of the liquid leakage detection unit, and an energization current detected by the current detection unit. It is a leak detection device including a determination unit for determining the leak detection unit in which a leak has occurred from the value, and the current limit value of each constant current element of each leak detection unit is different. The determination unit is characterized in that the leakage detection unit in which the leakage has occurred is specified by comparing the energization current value detected by the current detection unit with the current limiting current value of the constant current element.

This makes it possible to monitor leaks from devices arranged in parallel with a simple configuration.

In the liquid leakage detection device of the present invention, the node of the liquid leakage detection unit is connected to a pair of start end side terminals to which the parallel connection lines are connected and a pair of conductive lines of the liquid leakage detection band. A pair of end-side terminals and a pair of connection lines connecting the start-end side terminal and the end-side terminal in parallel are included, and the constant current element is interposed in either one or both of the connection lines. It may be arranged.

In this way, since the arrangement of the constant current element of the node can be variously changed according to the liquid to be detected, it is possible to detect the leak according to the liquid to be detected.

In the liquid leakage detection device of the present invention, the determination unit has a difference between the energization current value detected by the current detection unit and the current limit value of the constant current element of one liquid leakage detection unit within a predetermined range. In this case, one said leak detection unit may be specified as a leak occurrence location.

As a result, even if there is a difference between the energizing current value detected by the current detector and the current limit value of one constant current element, the leaked part can be identified, and the detection reliability of the leaked part can be improved. Can be done.

In the liquid leakage detection device of the present invention, the determination unit may determine that liquid leakage is detected when the energization current value detected by the current detection unit is equal to or greater than a predetermined value.

As a result, it is possible to detect the occurrence of liquid leakage even when the difference between the energization current value detected by the current detection unit and the current limit value of the plurality of constant current elements is not within a predetermined range for some reason. ..

In the liquid leakage detection device of the present invention, when the determination unit determines that the liquid leakage is detected, the determination unit changes the output voltage of the power supply, and the current detection unit determines the amount of change in the energization current value of the liquid leakage detection unit. It may be detected and it may be determined whether it is possible to identify the leak detection unit in which the leak has occurred from the current current value based on the amount of change in the current current value. At this time, the determination unit determines that when the absolute value of the change amount of the energization current value is less than a predetermined first threshold value, it is possible to identify the leak detection unit in which the leakage has occurred from the energization current value. Alternatively, the slope of the voltage-current characteristic of the liquid leakage detection unit is calculated based on the amount of change in the output voltage of the power supply and the amount of change in the energization current value detected by the current detection unit, and the slope is predetermined. If it is less than the second threshold value, it may be determined that the leak detection unit in which the leak has occurred can be identified from the energization current value. Further, when the determination unit determines that the leak detection unit in which the leak has occurred can be identified from the energization current value detected by the current detection unit, the energization current value detected by the current detection unit is used. When the difference between the leakage detection unit and the current limit value of the constant current element is within a predetermined range, the leakage detection unit may be specified as a leakage occurrence location.

In this way, the output voltage of the power supply is changed, the current detection unit detects the energization current value of the liquid leakage detection unit, and the constant current of the liquid leakage detection unit is based on the amount of change in the energization current value detected by the current detection unit. After it is determined that the element is saturated and it is possible to identify the leak detection unit where the leak has occurred from the current current value, the current current value detected by the current detector and the determination of one leak detection unit. When the difference from the current limit value of the current element is within a predetermined range, one leak detection unit is specified as the leak occurrence location, so that it is possible to prevent the leakage occurrence location from being erroneously identified. ..

The present invention can enable leakage monitoring of devices arranged in parallel with a simple configuration.

It is a system diagram which shows the structure of the liquid leakage detection apparatus of embodiment which used the constant voltage element. It is a system diagram which shows the structure of the liquid leakage detection unit of the liquid leakage detection apparatus shown in FIG. It is a graph which shows the characteristic of the current with respect to the voltage of the constant voltage element which connected the ideal Zener diode in anti-series. It is a system diagram which shows the flow of the electric | current when the leakage occurs in the leakage detection unit _Um of the leakage detection apparatus shown in FIG. It is a graph which shows the voltage value applied to each liquid leakage detection unit when the input voltage value is raised in the liquid leakage detection apparatus shown in FIG. 1. It is a graph which shows the time change of three kinds of input voltage values input to the leakage detection apparatus shown in FIG. The change characteristic (VI characteristic) of the input current value with respect to the change of the input voltage value when the leak occurs and when the leak does not occur in the leak detection device shown in FIG. 1, and the input current value due to the occurrence of the leak. It is a graph which shows the change of. The change characteristic (VI characteristic) of the input current value with respect to the change of the input voltage value when the leak occurs and when the leak does not occur in the leak detection device shown in FIG. 1, and the input when the leak occurs. It is a graph which shows the change of the input current value when the voltage is changed before and after the standby voltage value. The change characteristic (VG characteristic) of the conductance with respect to the change of the input voltage value when the leak occurs and the case where the leak does not occur in the leak detection device shown in FIG. 1 and the change of the conductance due to the occurrence of the leak are shown. It is a graph which shows. The change characteristic (VI characteristic) of the input current value with respect to the change of the input voltage value when the leak occurs in the leak detection unit _Um of the leak detection device shown in FIG. 1 and when there is no leak, and the input. It is a graph which shows the change of the input current value with respect to the change of the input voltage value in each leak detection unit when the voltage value is swept, and the change of the conduction range. It is a graph which shows the change (VG characteristic) of conductance with respect to the input voltage value calculated based on the VI characteristic shown in FIG. It is a graph which shows the conductance of each leak detection unit obtained from the characteristic shown in FIG. It is a system diagram which shows the structure of the liquid leakage detection apparatus of another Embodiment using a constant voltage element. It is a system diagram which shows the flow of the electric | current when the leakage occurs in the leakage detection unit _Um of the leakage detection apparatus shown in FIG. The change characteristic (IV characteristic) of the input voltage value with respect to the change of the input current value when the leak occurs in the leak detection unit _Um of the leak detection device shown in FIG. 13 and when there is no leak, and the leak. It is a graph which shows the change of the input voltage value by the generation of a liquid. This is an example of a comparison table between the input voltage value detected by the voltage sensor and the leak detection unit number where the leak occurred. It is explanatory drawing which shows the other example of the node applied to the leakage detection apparatus shown in FIGS. It is a system diagram which shows the structure of the liquid leakage detection apparatus of embodiment which used the constant current element. It is a system diagram which shows the structure of the liquid leakage detection unit of the liquid leakage detection apparatus shown in FIG. It is a graph which shows the change of the terminal current and the terminal resistance with respect to the terminal voltage of an ideal constant current diode. It is a graph which shows the characteristic of the current with respect to the voltage of the constant current element which connected the constant current diode shown in FIG. 20 in anti-series. It is a graph which shows the characteristic of the current with respect to the voltage of the constant current element which connected the constant current diode shown in FIG. 20 in anti-series, and has different current limit values. It is a system diagram which shows the change of the current flow and voltage when the leakage is detected by the leakage detection apparatus shown in FIG. It is a flowchart which shows the operation of the liquid leakage detection apparatus shown in FIG. It is a graph which shows the time change of the detection current and the input voltage when the leakage is detected by the leakage detection apparatus shown in FIG. It is a system diagram which shows the change of the current flow and voltage at the time t3 shown in FIG. It is a graph which shows the operating point of each constant current element at time t3 shown in FIG. It is a graph which shows the change of the energization current value when the output voltage of a power source is changed in a constant current element in an unsaturated state. It is a graph which shows the change of the energization current value when the output voltage of a power source is changed in the saturated state of a constant current element. It is a figure which shows the example of the node applied to the leakage detection apparatus of the embodiment shown in FIG.

<Structure of the leak detection device 100 of the first embodiment>
Hereinafter, the leak detection device 100 of the embodiment will be described with reference to the drawings. As shown in FIG. 1, in the liquid leakage detection device 100, a liquid leakage detection unit 70 in which a plurality of liquid leakage detection units U ₁ to U ₃ are connected in parallel by a parallel connection line 64 and a liquid leakage detection unit 70 are connected in parallel. Leakage based on the power supply 81 connected to the wire 64, the current sensor 82 which is a current detection unit for detecting the energization current value of the parallel connection wire 64 of the liquid leakage detection unit 70, and the input current value detected by the current sensor 82. It is composed of a determination unit 90 that determines the liquid.

With reference to FIG. 2, the configuration of the liquid leakage detection unit U _m in which the liquid leakage detection unit numbers N of the liquid leakage detection units U ₁ to U ₃ are m (N = m) will be described. The number of leak detection units U constituting the leak detection unit 70 is not limited to three, and may be any number, one, or four or more.

As shown in FIG. 2, the liquid leakage detection unit U _m has a node ND _m including a constant voltage element D _m and a liquid leakage detection band 60 including a pair of conductive wires 61 and 62. The node ND _m has a pair of connection lines 12 connecting the pair of start end side terminals 13, 15 and the pair of end side terminals 14, 16 and the start end side terminals 13, 15 and the end side terminals 14, 16 in parallel. Includes. As shown in FIG. 2, a constant voltage element D _m is connected so as to be interposed in the middle of the connection line 12 connecting one of the start end side terminals 13 and the end side terminal 14. Further, the other start end side terminal 15 and the end end side terminal 16 are connected by a connection line 12, and the constant voltage element _Dm is not connected. A pair of conductive wires 61 and 62 of the liquid leakage detection band 60 are connected to the pair of terminal terminals 14 and 16, respectively, and the end portions 61e and 62e of the pair of conductive wires 61 and 62 on the terminal side are leaking liquid. It is the end of the detection unit _Um on the terminal side. Further, the pair of start end side terminals 13 and 15 are end portions on the start end side of the liquid leakage detection unit _Um .

As shown in FIG. 3, the constant voltage element D _m conducts when the absolute value of the applied voltage reaches a predetermined rising voltage value Vf, and does not reach the rising voltage value Vf when the absolute value of the applied voltage does not reach the rising voltage value Vf. It is an element that becomes conductive. The rising voltage value Vf corresponds to the conduction voltage value. In the liquid leakage detection device 100 of the present embodiment, the constant voltage element D _m is configured by connecting the Zener diodes 11a and 11b having a rising voltage value Vf in anti-series to form a constant voltage element D _m having the characteristics shown in FIG. is doing. In the liquid leakage detection device 100 of the present embodiment, the rising voltage values of the constant voltage elements D ₁ to D ₃ are all different, and are Vf, 2Vf, and 3Vf, respectively. The configuration of the constant voltage element D _m is not limited to this. This point will be described later.

The conductive wires 61 and 62 are non-conducting when there is no leakage, and are mutually conductive when the leakage comes into contact with the leakage. The conductive wires 61 and 62 may be made of, for example, twisted copper wires covered with a hygroscopic insulating film or the like.

As shown in FIG. 1, the start end side terminals 13 and 15 of the leak detection unit U ₁ constituting the start end 71 of the leak detection unit 70 are connected to the parallel connection line 64, respectively. The parallel connection line 64 is connected to the power supply 81 via the insulating coated wire 63. A current sensor 82 is connected between the power supply 81 and the parallel connection line 64. Further, the end 72 of the liquid leakage detection unit 70 is open.

The power supply 81 is an AC power supply. The power supply 81 may be, for example, an AC 100 Hz and an output voltage of about 10 V. The current sensor 82 is an alternating current detector that detects an alternating current value. The determination unit 90 is a computer including a CPU 91, a memory 92, an input interface 93 to which the power supply 81 and the current sensor 82 are connected, and an output interface 94 for outputting the calculation result of the CPU 91. The CPU 91, the memory 92, the input interface 93, and the output interface 94 are connected by a data bus 95. The power supply 81 outputs a voltage corresponding to the voltage command value input from the determination unit 90 of the determination unit 90. The configuration of the determination unit 90 is not limited to this, and may be configured by, for example, an analog circuit.

<Leakage determination operation of the leak detection device 100>
Hereinafter, the liquid leakage determination operation of the liquid leakage detection device 100 will be described with reference to FIGS. 4 to 9, but the input voltage value and the applied voltage of each liquid leakage detection unit U will be described first with reference to FIG. The conduction range A will be described. FIG. 4 is a generalization of the reference numerals of the system diagram shown in FIG. 1 for the purpose of explaining the liquid leakage determination operation of the liquid leakage detection device 100. In FIG. 4, the description of the determination unit 90 is omitted. The rising voltage values of the constant voltage elements D ₁ to D _m to D _Nend are all different. In the present embodiment, the rising voltage values of the constant voltage elements D ₁ to D _m to D _Nend increase by Vf each time the liquid leakage detection unit number N increases by one. Therefore, the rising voltage value of the constant voltage element D _m is m × Vf. Further, Nend indicates the total number of leak detection units U, and the rising voltage value of the leak detection unit U _Nend is Nend × Vf.

<Input voltage value and continuity range>
When the input voltage value is zero, all the constant voltage elements D are off and non-conducting. As shown in FIG. 5, when the input voltage value of the parallel connection line 64 is increased from zero to the rising voltage value Vf of the constant voltage element D ₁ of the liquid leakage detection unit U ₁ , the constant voltage element D of the liquid leakage detection unit U ₁ D. A voltage of Vf is applied to ₁ . Then, the constant voltage element D ₁ is turned on in the conduction region, that is, on. Since the voltage drop of the constant voltage element D ₁ is Vf, when the input voltage exceeds Vf, _a voltage starts to be applied between the conductive lines 61 and 62 of the liquid leakage detection unit U1. This enables the leak detection unit U ₁ to detect the leak. After that, as the input voltage is increased, the voltage between the conductive wires 61 and 62 gradually increases from zero. At this time, the conduction range A ₁ is only the liquid leakage detection unit U ₁ .

As shown in FIG. 5, when the input voltage value is raised to the rising voltage value 2Vf of the constant voltage element D ₂ of the liquid leakage detection unit U ₂ , the rising voltage value 2Vf is applied to the constant voltage element D ₂ of the liquid leakage detection unit U ₂ . Is applied. As a result, the constant voltage element D ₂ is turned on, voltage starts to be applied between the conductive wires 61 and 62 of the liquid leakage detection unit U ₂ , and the liquid leakage detection unit U ₂ can detect the liquid leakage. The continuity range A ₂ at this time is the liquid leakage detection units U ₁ and U ₂ .

Similarly, when the input voltage value is raised to V _m = mVf, the constant voltage element D _m of the leak detection unit U _m is turned on, and each leak from the leak detection unit U ₁ to the leak detection unit U _m is turned on. The liquid detection unit U conducts. The conduction range at this time is _Am . As the input voltage value is increased in this way, each leak detection unit U is sequentially conducted in ascending order of rising voltage value.

Then, when the input voltage value is raised to V _Nend = Nend × Vf, all the leak detection units U from the leak detection unit U ₁ to the leak detection unit U _Nend become conductive, and all the leak detection units U Can detect leaks. Therefore, by setting the input voltage value to a standby voltage value V ₀ higher than that of V _Nend , all the leak detection units U can detect the leak.

Hereinafter, the operation when the leakage is detected by setting the input voltage value to the standby voltage value V ₀ higher than that of V _Nend will be described. In this case, as shown by line a in FIG. 6, the input voltage value is set to a constant standby voltage value V ₀ (first determination operation), and as shown in line b in FIG. 6, the input voltage value is set to standby voltage. A method of varying before and after the value V ₀ (second judgment operation) and a method of sweeping the input voltage value between zero and the standby voltage value V ₀ as shown by line c in FIG. 6 (third judgment operation). There is. Hereinafter, the first determination operation will be described first, and then the second and third determination operations will be described.

<First judgment operation>
The determination unit 90 outputs a voltage command value that keeps the output voltage constant at the standby voltage value V ₀ to the power supply 81. As a result, the power supply 81 applies a voltage having a constant standby voltage value of _V0 to the parallel connection line 64.

As shown in FIG. 7, when no liquid leakage has occurred, no current flows between the conductive wires 61 and 62 of each liquid leakage detection unit U, so that the input current value detected by the current sensor 82 is zero. It has become.

On the other hand, as shown in FIG. 4, when a leak occurs in the m-th leak detection unit U _m , Im = G _m (V _{0 )} between the conductive wires 61 and 62 of the leak detection unit U _m . _-Vm ) current flows. Here, G _m is the conductance between the conductive wires 61 and 62 of the liquid leakage detection unit U _m .

Therefore, the determination unit 90 compares the input current value detected by the current sensor 82 with a predetermined threshold value, and determines that leakage has occurred when the input current value becomes larger than the predetermined threshold value. .. When the determination unit 90 determines that a leak has occurred, the determination unit 90 issues an alarm for the occurrence of the leak to the external device via the output interface 94.

Here, the predetermined threshold value can be freely set, but it may be determined by a test or the like according to the type of the liquid or the like.

<Second judgment operation>
As described above, when the input voltage value is increased to V _m = m × Vf, the constant voltage element D _m of the liquid leakage detection unit U _m is turned on, and the liquid leakage detection unit U ₁ to the liquid leakage detection unit U 1 turns on. Each leak detection unit U up to U _m conducts. In this case, if a leak has occurred in the _m -th leak detection unit Um, a current starts to flow between the conductive wires 61 and 62 of the leak detection unit _Um . At this time, the conductance of the leaked portion 65 is G _m . After that, when the input voltage value is increased, the voltage between the conductive lines 61 and 62 of the liquid leakage detection unit _Um increases, and the input current value gradually increases. Therefore, when a leak occurs in the leak detection unit _Um , the change characteristic of the input current value (hereinafter referred to as VI characteristic) with respect to the change of the input voltage value has an input voltage value of V as shown by a broken line in FIG. The input current value is zero up to _m , and when the input voltage value exceeds V _m , the input current value increases with a certain inclination. As shown by the broken line in FIG. 9, the conductance change characteristic (hereinafter referred to as VG characteristic) with respect to the change of the input voltage value is that the conductance G is zero and the input voltage value is V _m until the input voltage value is V _m . If the conductance G exceeds, the conductance of the leaked portion 65 is G _m .

Therefore, in the second determination operation, as shown in FIG. 8, the input voltage value is fluctuated by ΔV before and after the standby voltage value V ₀ , and the change amount ΔI of the input current value is changed from the change of the input current value detected by the current sensor 82. , The conductance G = ΔI / ΔV is calculated, and the calculated conductance G is compared with a predetermined threshold value to determine the leakage.

The determination unit 90 fluctuates the voltage command value output to the power supply 81 by ΔV before and after the standby voltage value V ₀ . The power supply 81 fluctuates the input voltage value applied to the start end 71 according to the voltage command value by _ΔV before and after the standby voltage value V0. The determination unit 90 detects the input current value by the current sensor 82. The determination unit 90 calculates the amount of change ΔI of the input current value from the two input current values corresponding to the two different voltage command values. Then, the determination unit 90 calculates conductance G = ΔI / ΔV and compares it with a predetermined threshold value. Then, as shown in FIG. 9, when the calculated conductance G is larger than a predetermined threshold value, it is determined that the liquid leakage has occurred.

The calculation of the change amount ΔI of the input current value is not limited to using two input current values corresponding to two different voltage command values, and the input current corresponding to three or more voltage command values. It may be calculated using a value. Further, in the second determination operation, the resistance value R = ΔV / ΔI may be calculated instead of the conductance G, and it may be determined that leakage occurs when the resistance value is smaller than a predetermined threshold value.

Further, in the above description, the change amount ΔI of the input current value is calculated from the two input current values corresponding to the two different voltage command values, but the voltage sensor 83 for detecting the input voltage value of the start end 71 is described. May be provided to detect the input voltage value, and the input voltage value detected by the voltage sensor 83 may be used instead of the voltage command value. In this case, the amount of change ΔI of the input current value is calculated from the two input current values corresponding to the two different input voltage values.

<Third judgment operation>
In the third determination operation, the determination unit 90 sweeps the voltage command value between zero and the standby voltage value V ₀ as shown by line c in FIG. 6, and corresponds to the two voltage command values changed by the sweep. The amount of change ΔI of the input current value is calculated from the two input current values. Then, as in the second determination operation, conductance G = ΔI / ΔV is calculated, and when the calculated conductance G is larger than a predetermined threshold value, it is determined that a liquid leak has occurred. In this case, the conductance G may be calculated using the input current value at the minimum voltage value and the input current value at the maximum voltage value.

Further, as in the second determination operation, the calculation of the change amount ΔI of the input current value is not limited to using the two input current values corresponding to the two voltage command values, and the voltage command is three or more. It may be calculated using the input current value corresponding to the value. Further, the resistance value R = ΔV / ΔI may be calculated instead of the conductance G, and it may be determined that leakage occurs when the resistance value is smaller than a predetermined threshold value. Further, as in the second determination operation described above, the change amount ΔI of the input current value may be calculated using the input voltage value detected by the voltage sensor 83 instead of the voltage command value.

Further, in the explanation of this operation, the voltage command value is swept between zero and the standby voltage value V ₀ , but if the maximum value of the voltage command value is larger than V _Nend = Nend × Vf, the standby voltage. It may be smaller than the value V ₀ or larger than the standby voltage value V ₀ .

As described above, in the first determination operation, it is possible to determine the occurrence of liquid leakage in a short time with a simple configuration in which the standby voltage value V ₀ is constant at a predetermined voltage value. Further, in the second and third determination operations, the conductance or resistance value is calculated by fluctuating the input voltage value before and after the standby voltage value V ₀ or sweeping the input voltage value, whereby the leakage of liquid is calculated. Since the determination is made, the leakage can be determined by the physical quantity different from the input current value.

<Specific operation of the leak detection unit where leak has occurred>
Hereinafter, the specific operation of the leak detection unit U in which the leak has occurred will be described with reference to FIGS. 10 to 12.

In the specific operation of the leak detection unit in which the leak has occurred, the voltage command value is swept between zero and the standby voltage value V ₀ as shown by line c in FIG. 6, and the leak detection unit U is raised to the voltage value. Conducts in ascending order, and conducts the total conductance [G ₁ + ... + G _m-1 ] with the liquid leakage detection units U ₁ to U _{m -1} in the conductive state, and the liquid leakage detection units U ₁ to U m. The conductance G _m of the liquid leakage detection unit U _m is calculated from the difference from the total conductance [G ₁ + ... + G _m ] in the state, and the calculated conductance G _m is compared with a predetermined threshold value to leak liquid. The leak detection unit U in which the above is generated is specified.

<Input voltage value, conductance and conduction range>
When the input voltage value is increased from zero to the standby voltage value V ₀ as shown by the line c in FIG. 6, each leak detection unit U has a rising voltage value as described above with reference to FIG. Conducts in ascending order. FIG. 10 is a graph in which the VI characteristic showing the change in the input current value with respect to the change in the input voltage value in each leak detection unit when the input voltage value is swept and the change in the conduction range are superimposed. The solid line in FIG. 10 shows the VI characteristics when no liquid leakage occurs, and the broken line shows the VI characteristics when liquid leakage occurs in the liquid leakage detection unit _Um .

As shown in FIG. 10, when the input voltage value is raised to between V _m and V _{m + 1} , the liquid leakage detection units U ₁ to U _m become conductive. When the input voltage value is fluctuated by ΔV in this state and the change amount ΔI of the input current value is calculated from the input current value detected by the current sensor 82, the conductance G calculated by ΔI / ΔV is shown in FIG. Is the _{total conductance} of the conductances G1 to _Gm of the leak detection units U1 to Um in the conductive state, as shown in the following equation ( ₁ ).

Similarly, when the input voltage value is raised to between V _m-1 and V _m , the leak detection units U ₁ to U _m-1 become conductive, so the conductance G calculated by ΔI / ΔV is as follows. As shown in the equation (2), it is the total conductance of the conductances G1 to _{Gm -1 of} the leak detection units U1 to Um- ₁ in the conductive state.

Therefore, as shown in FIG. 12, the conductance _Gm of the leak detection unit _Um can be calculated by subtracting the equation (2) from the equation (1). Then, by comparing the conductance _Gm with a predetermined threshold value, it is possible to determine whether or not the leakage is generated in the leakage detection unit _Um .

<Details of specific operation of the leak detection unit where leak has occurred>
Hereinafter, the details of the specific operation of the leak detection unit in which the leak has occurred will be described with reference to FIGS. 10 to 12. In the following description, it is assumed that a leak has occurred in the leak detection unit _Um .

The determination unit 90 sweeps the voltage command value from zero to the standby voltage value V ₀ along the line c in FIG. As a result, the power supply 81 sweeps the input voltage value applied to the parallel connection line 64 from _zero to the standby voltage value V0 according to the voltage command value. As described above, when the input voltage value reaches Vf, the leak detection unit _U1 can detect the leak.

The determination unit 90 sweeps the voltage command value from Vf to a value slightly smaller than 2 × Vf, and sweeps the input voltage value from Vf to a value slightly smaller than 2 × Vf. During this period, only the liquid leakage detection unit U ₁ is in the conduction range (conduction range A ₁ ). During this period, the determination unit 90 detects with the current sensor 82 two input current values corresponding to the two voltage command values in which the difference between the voltage command values is ΔV. Then, the change amount ΔI of the input current value is calculated from the detected input current value, and the conductance G ₁ = ΔI / ΔV is calculated. No leak has occurred in the leak detection unit U ₁ , and as shown in FIG. 12, the input current value remains zero while the input voltage value is between Vf and 2 × Vf. Therefore, conductance G ₁ = ΔI / ΔV = 0.

Next, the determination unit 90 sweeps the voltage command value from 2 × Vf to a value slightly smaller than 3 × Vf, and sweeps the input voltage value from 2 × Vf to a value slightly smaller than 3 × Vf. During this period, the liquid leakage detection units U ₁ and U ₂ are in the conduction range (conduction range A ₂ ). During this time, the determination unit 90 detects with the current sensor 82 two input current values corresponding to the two voltage command values in which the difference between the voltage command values is ΔV. Then, the change amount ΔI of the input current value is calculated from the detected input current value, and the total value [G ₁ + G ₂ ] = ΔI / ΔV of the conductances of the leak detection units U ₁ and U ₂ which are the conduction range is calculated.

No leak has occurred in the leak detection units U ₁ and U ₂ , and as shown in FIG. 10, the input current value remains zero while the input voltage value is between 2 × Vf and 3 × Vf. At = 0, the total value of conductance [G ₁ + G ₂ ] = ΔI / ΔV = 0. The determination unit 90 subtracts the previously calculated G ₁ from [G ₁ + G ₂ ] to obtain the result of G ₂ = 0.

Similarly, the determination unit 90 sweeps the voltage command value, calculates the total value ΣG of the conductance of the liquid leakage detection unit U in the conduction range every time the conduction range expands, and calculates the conductance in the previous conduction range. The conductance G of each leak detection unit U is calculated from the difference from the total value of. Since no liquid leakage has occurred in the liquid leakage detection units U ₁ to U _m-1 , as shown in FIG. 10, the input current value is zero until the input voltage value reaches V _m , and FIG. 11 shows. Each conductance G of each leak detection unit U calculated as shown is zero.

The determination unit 90 sweeps the voltage command value from m × Vf to a value slightly smaller than (m + 1) × Vf, and sweeps the input voltage value from m × Vf to a value slightly smaller than (m + 1) × Vf. During this period, the liquid leakage detection units U ₁ to U _m are in the conduction range (conduction range _Am ). During this time, the determination unit 90 detects with the current sensor 82 two input current values corresponding to the two voltage command values in which the difference between the voltage command values is ΔV. Then, the amount of change ΔI of the input current value is calculated from the detected input current value, and the total value of the conductance of the leak detection units U ₁ to U _m , which is the conduction range [G ₁ + _... + G _m ] = ΔI / ΔV. Is calculated.

Since liquid leakage has occurred in the liquid leakage detection unit _Um , as shown in FIG. 10, the change in the input current value while the input voltage value changes by ΔV is not zero. Therefore, [G ₁ + _... + G _m ] = ΔI / ΔV is a non-zero value. The determination unit 90 obtains the value of G _m by subtracting the previously calculated [G ₁ + _... + G _{m -1} ] from [G ₁ + _... + G m].

The determination unit 90 sweeps the voltage command value from (m + 1) × Vf to a value slightly smaller than (m + 2) × Vf, and sweeps the input voltage value from (m + 1) × Vf to a value slightly smaller than (m + 2) × Vf. do. During this period, the liquid leakage detection units U ₁ to U _{m + 1} are in the conduction range (conduction range _{Am + 1} ). During this time, the determination unit 90 detects with the current sensor 82 two input current values corresponding to the two voltage command values in which the difference between the voltage command values is ΔV. Then, the amount of change ΔI of the input current value is calculated from the detected input current value, and the total value of the conductance of the leak detection units U ₁ to U _{m + 1} which is the conduction range [G ₁ + _... + G _{m + 1} ] = ΔI / ΔV. Is calculated.

Since no liquid leakage has occurred in the liquid leakage detection unit U _{m + 1} , as shown in FIG. 10, the change in the input current value while the input voltage value changes by ΔV is conducted by the liquid leakage detection units U ₁ to U _m . It is the same as the case where it is in the range (conduction range _Am ), and the slope of the VI characteristic is also the same. Therefore, [G ₁ + _... + G _{m + 1} ] = ΔI / ΔV has the same value as G _m . The determination unit 90 subtracts [G ₁ + _... + G _m ] = G _m calculated earlier from [G ₁ + _... + G _{m + 1} ] = G _m to obtain a value of G _{m + 1} = 0.

Since no leak has occurred after the leak detection unit U _m , the slope of the VI characteristic shown in FIG. 10 does not change, and [G ₁ + _... + G _{m + 1} ] to [G ₁ + _... + G. All ΔI / ΔV up to [ _Nend ] are G _m , and as shown in FIG. 12, each conductance G _{m + 1} to G _Nend is all zero.

As shown in FIG. ₁₂ , in the conductances G1 to _GNend of the leak detection units U1 to _UNend calculated as described _above , only the leak detection unit _Um in which the leak has occurred is not 0. The value is G _m , and each conductance G of the other leak detection unit U is zero.

The determination unit 90 compares the calculated conductances G1 to _GNend of _each of the leak detection units U1 to _UNend with a predetermined threshold value, and determines the leak detection unit _Um having _a conductance G larger than the predetermined threshold value. It is specified as the leak detection unit U in which the leak has occurred.

<Structure of the leak detection device 200 of the second embodiment>
Next, the leak detection device 200 of the second embodiment will be described with reference to FIGS. 13 to 15. The same parts as those of the leak detection device 100 described above with reference to FIGS. 1 to 12 are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 13, the liquid leakage detection device 200 is provided with a voltage sensor 83, which is a voltage detection unit, in place of the current sensor 82 of the liquid leakage detection device 100 described above. Further, the power supply 81 outputs a current corresponding to the current command value input from the determination unit 90. Further, among the liquid leakage detection units 70, the terminal 72 of the liquid leakage detection unit U ₃ having the largest conduction voltage N = Nend is not open, and the conductive wire of the liquid leakage detection unit U ₃ constituting the terminal 72 is not opened. The end portions 61e and 62e on the terminal side of 61 and 62 are connected by a terminal resistor 79 which is a resistor. The resistance value of the terminal resistance 79 is a resistance value larger than the resistance value of the liquid that detects the leakage.

<Leakage determination operation of the leak detection device 200>
Hereinafter, the liquid leakage determination operation of the liquid leakage detection device 200 will be described with reference to FIGS. 14 to 16. The determination operation is performed with the input current value as the standby current value I ₀ constant.

<Input voltage value and continuity range>
When there is no leakage, as described above with reference to FIG. 5, when the input voltage value is increased from zero, each leakage detection unit U increases the input voltage value by Vf. Each time, the leakage detection units U ₁ to _{UN End} , which have smaller rising voltage values, are sequentially conducted in this order. Then, when the input voltage value reaches V _End = ( _Nend ) × Vf, all the leak detection units U from the leak detection unit U ₁ to the leak detection unit _{UN End} become conductive, and all the leak detection units U are detected. Leakage can be detected by the unit U.

When the input voltage value exceeds V _Nend , a current starts to flow in the terminal resistance 79. When the input current value is held at the standby current value I ₀ having a constant magnitude, the current value _IE flowing through the terminal resistance 79 becomes the standby current value I ₀ , and the voltage drop _ΔVE of the terminal resistance 79 at this time is the terminal. With the conductance of the resistance 79 as _GE , _ΔVE = I ₀ / _GE . Then, the input voltage value becomes V _Nend + _ΔVE .

The change characteristic of the input voltage value (hereinafter referred to as IV characteristic) with respect to the change of the input current value at this time is shown by the solid line in FIG. As shown by the solid line in FIG. 15, the input current value is zero and the current value flowing through the leak detection unit 70 is zero until the input voltage value reaches V _Nend . When the input current value exceeds V _Nend , the input current value also increases as the input current value increases, and when the input voltage value reaches V _Nend + _ΔVE , the input current value reaches the standby current value I ₀ .

As shown in FIG. 14, when a leak occurs in the leak detection unit U _m while the input current value is kept at the standby current value I ₀ , the conductance G _m of the leak detection unit U _m increases from zero. Then, a current I ₀ flows through the leak detection unit _Um . As a result, as shown in FIG. 15, the voltage of the liquid leakage detection unit _{Um drops to V m +} ΔV _W0 with the voltage drop of the liquid leakage portion 65 as ΔV _W0 . Here, the voltage drop ΔV _W0 of the leaked portion 65 is ΔV _W0 = I ₀ / G _m with the conductance of the leaked portion 65 as G _m , and if the standby current value I ₀ is set small, ΔV _W0 <Vf. can.

Further, in the liquid leakage detection units U _{m + 1} to _{UN End} , the input voltage drops to V _m + ΔV _W0 <V _{m + 1} , so that the constant voltage elements D _{m + 1} to D _Nend are non-conducting.

From the above, when the input current value is kept constant at the standby current value I ₀ , as shown in FIG. 15, the input voltage value detected by the voltage sensor 83 when there is no leakage is from V _Nend + _ΔVE . Due to the occurrence of liquid leakage, the voltage drops to _Vm + ΔV _W0 .

<Judgment operation>
The determination unit 90 outputs a current command value that makes the output current constant at the standby current value I ₀ to the power supply 81. At this time, the input voltage value is set to V _Nend + _ΔVE so that the standby current flows through the terminal resistance 79. As a result, the power supply 81 outputs a constant current with a standby current value of I ₀ , and the current value flowing through the terminal resistor 79 becomes a standby current value of I ₀ .

As described above, when no liquid leakage has occurred, the input voltage value detected by the voltage sensor 83 is V _Nend + _ΔVE .

When a leak occurs in the leak detection unit Um, the input voltage value detected by the voltage sensor 83 _drops from V _Nend + _ΔVE to V _m + ΔV _W0 . The determination unit 90 determines the occurrence of liquid leakage by comparing the input voltage value detected by the voltage sensor 83 with a predetermined threshold value. For example, the determination unit 90 may determine that leakage has occurred when the input voltage value drops by a predetermined voltage value from the input voltage value in the standby state.

Further, when liquid leakage occurs, the input voltage value detected by the voltage sensor 83 drops to _Vm + ΔV _W0 . Here, since V _m = (m) × Vf, the input voltage value detected by the voltage sensor 83 is (m) × Vf + ΔV _W0 . In this way, the input voltage value becomes a different value depending on the number of the leak detection unit U in which the leak has occurred. For example, when the leak detection unit in which the leak has occurred is U ₁ , the input voltage value is Vf + ΔV _{W 0} . Then, by selecting Vf and the standby current value I ₀ so that ΔV _W0 does not exceed Vf, the input voltage value (m) × Vf + ΔV _W0 when a leak occurs in the leak detection unit Um is set to ( _m ). ) × Vf and (m + 1) × Vf.

In this case, a comparison table of the input voltage value detected by the voltage sensor 83 as shown in FIG. 16 and the leak detection unit number N in which the leak has occurred is stored in the memory 92, and the determination unit 90 determines the voltage. By comparing the input voltage value detected by the sensor 83 with the range of the input voltage value in the comparison table, it is possible to determine the occurrence of leak and identify the leak detection unit U in which the leak has occurred.

In the liquid leakage detection devices 100 and 200 of the above-described embodiment, the rising voltage values of the constant voltage elements D ₁ to D _m to D _Nend increase by Vf each time the liquid leakage detection unit number N increases by one. However, as long as the rising voltage values of the constant voltage elements D ₁ to D _m to D _Nend are different, the order is not limited to the above, and any order may be used. For example, the liquid leakage detection unit number N is 1. The rising voltage value of each constant voltage element D ₁ to D _m to D _Nend may be increased by Vf each time the voltage becomes smaller.

<Variations of constant voltage elements>
A variation of the constant voltage element D _m will be described with reference to FIG. In the liquid leakage detection devices 100 and 200 described with reference to FIGS. 1 to 16, the constant voltage element _Dm is arranged so as to connect the Zener diodes 11a and 11b in anti-series series and to intervene in one of the connection lines 12. However, the present invention is not limited to this, and may be configured as shown in FIGS. 17 (a) to 17 (f).

As shown in FIG. 17A, the Zener diodes 11a and 11b may be connected in anti-series in the opposite direction to the state shown in FIG. Further, as shown in FIG. 17B, the connection line 12 may be arranged on the side opposite to the side shown in FIG. Further, as shown in FIGS. 17 (c) and 17 (d), one Zener diode 11a and 11b are arranged in the same direction on both connection lines 12, respectively, and a current flow when a liquid leak occurs. The two Zener diodes 11a and 11b may be in anti-series with respect to the above. Further, as shown in FIG. 17 (e), the Zener diode 11a may be interposed only in one of the connection lines 12. In this case, the power supply 81 may be configured by using a DC power supply. Further, instead of using the Zener diodes 11a and 11b, as shown in FIG. 17 (f), a constant voltage element circuit 18 in which an electric circuit having a voltage-current characteristic as shown in FIG. 3 is composed of an IC or the like may be used. ..

In this way, by variously changing the arrangement of the constant voltage element D _m of the node ND _m according to the liquid to be detected, it is possible to detect the leak according to the liquid to be detected.

<Structure of the leak detection device 300 of the third embodiment>
Hereinafter, the leak detection device 300 of the third embodiment will be described with reference to the drawings. The same parts as those of the leak detection device 100 described above with reference to FIGS. 1 to 12 are designated by the same reference numerals, and the description thereof will be omitted. As shown in FIGS. 18 and 19, in the liquid leakage detection device 300, the constant voltage element D _m of the liquid leakage detection unit Um of the liquid leakage detection device 100 described with reference to FIGS. 1 and 2 is _replaced with the constant current element _Em . It was. Further, the power supply 81 is used as an AC power supply that outputs a predetermined voltage value V0. Other configurations are the same as those of the leak detection device 100.

The constant current element _Em is an element that limits the _energizing current value of the liquid leakage detection unit Um to the limiting current value. The current limit value Ip _m of the constant current element _Em is different from each other, and the current limit values of the liquid leakage detection units U ₁ to U ₃ are Ip ₁ , Ip ₂ , and Ip ₃ (Ip ₁ > Ip ₂ > Ip, respectively. ₃ ). In the liquid leakage detection device 100 of the present embodiment, the constant current element Em is configured by connecting the _anodes of the constant current diodes 17a and 17b facing each other in anti-series.

<Characteristics of constant current diode>
As described above, the constant current element Em of the liquid leakage detection device 300 shown in FIG. 18 has two constant current diodes _17a and 17b connected in anti-series. Hereinafter, the characteristics of the terminal current and the terminal resistance with respect to the terminal voltage of the ideal constant current diode CRD (Current Regulative Diode) will be described with reference to FIG.

The constant current diode CRD is a semiconductor element that can always pass a constant current between the terminals even if the voltage value between the terminals between the cathode side terminal and the anode side terminal (hereinafter referred to as the voltage value between terminals) changes. Is. As shown in FIG. 20, when a forward voltage is applied between the anode side terminal and the cathode side terminal and the voltage value between the terminals is increased from zero, the pinch-off voltage is shown by the solid line in FIG. Until the value _Vpm is reached, the current value between terminals (hereinafter referred to as the current value between terminals) increases in proportion to the voltage value between terminals. The pinch-off voltage value _Vpm is a voltage value at which the inter-terminal current value becomes the pinch-off current value _Ipm described later. The region where the voltage value between terminals is from zero to the pinch-off voltage value _Vpm is called the unsaturated region. In the non-saturated region, as shown by the alternate long and short dash line in FIG. 20, the resistance value between terminals is small, and the resistance value RL is constant in magnitude.

As shown by the solid line in FIG. 20, when the voltage value between terminals reaches a certain voltage value, the current value between terminals becomes a constant current value. This current value is called a pinch-off current value _Ipm . Further, the voltage value between terminals at which the current value between terminals is the pinch-off current value _Ipm is referred to as the pinch-off voltage value _Vpm .

As shown by the solid line in FIG. 20, when the pinch-off voltage value exceeds the pinch-off voltage value _Vpm , the terminal-to-terminal current value is maintained at a constant pinch-off current value _Ipm . This region is called the saturation region. As shown by the alternate long and short dash line in FIG. 20, in the saturation region, the resistance value between terminals increases in substantially proportional to the voltage value between terminals, so that the current value between terminals is constantly pinched off even if the voltage value between terminals increases. The current value is kept at _Ipm .

Further, when a voltage in the opposite direction is applied between the cathode side terminal and the anode side terminal, a current flows in proportion to the absolute value of the voltage value between the terminals.

As described above, in the constant current diode CRD, when the terminal voltage is applied in the forward direction, the terminal current is limited to the pinch-off current value _Ipm , and when the terminal voltage is applied in the reverse direction, the current flows in the reverse direction. Has characteristics. Therefore, in a circuit using an AC power supply, in order to configure a constant current element _Em that limits the pinch-off current value between terminals to the pinch-off current value _Ipm in both directions, the same pinch-off is performed as shown in FIGS. It is necessary to connect a constant current diode CRD with a current value of _Ipm in anti-series. As shown in FIG. 21, the constant current element in which the constant current diode CRD is connected in anti-series can limit the current value between the terminals in both directions.

<Constituent current element configuration>
As described above, the limit current value _Ipm of the constant current element Em is different from each other, and becomes smaller as the detection unit numbers N of the liquid leakage detection units _U1 to U3 increase _{( Ipm} > Ip ₎ . It is configured as _{m + 1} ). Therefore, as shown in FIG. 22, the pinch-off current values Ip ₁ to Ip ₃ of the constant current elements E ₁ to E ₃ of the liquid leakage detection units U ₁ to U ₃ decrease in the order of Ip ₁ > Ip ₂ > Ip ₃ . There is. Similarly, the pinch-off voltage values Vp ₁ to Vp ₃ decrease in the order of Vp ₁ > Vp ₂ > Vp ₃ . When all the leak detection units Um of _Nend are connected, the pinch-off current values Ip ₁ to Ip _Nend of the constant current elements E ₁ to E _Nend of the leak detection units U ₁ to _UN Nend are As shown in FIG. 22, Ip ₁ >>...> Ip _Nend , and the pinch-off voltage values Vp ₁ to Vp _Nend are Vp ₁ >>...> Vp _Nend .

<Operating principle of the leak detection device>
Next, the operating principle of the liquid leakage detection device 300 when a liquid leakage occurs will be described with reference to FIG. 23. FIG. 23 is a generalization of the reference numerals of the system diagram shown in FIG. 18 for the purpose of explaining the liquid leakage determination operation of the liquid leakage detection device 300. In FIG. 23, the description of the determination unit 90 is omitted. In the following description, it is assumed that the leak has occurred in the leak detection unit Um having the detection unit number N = _m . Until the leakage occurs, the conductive wires 61 and 62 of the leakage detection unit U ₁ to _{UN End} are insulated from each other, so that a closed circuit is formed between the power supply 81 and the conductive wires 61 and 62. No current flows. In this case, the input voltage value of the parallel connection line 64 is V0, which is the output voltage value of the power supply 81.

As shown in FIG. 23, when the leaked liquid portion 65 is formed by the contact of the leaked liquid between the conductive wires 61 and 62 of the liquid leak detecting unit _Um , the conductive wire 61 through the liquid leaked portion 65, 62 conducts. As a result, the power supply 81, the parallel connection line 64, the constant current element _Em and the conductive line 61 of the liquid leakage detection unit _Um , the liquid leakage portion 65, the parallel connection line 64 from the liquid leakage detection unit _Um , and the closed circuit of the power supply 81. Is formed and current begins to flow in this closed circuit. However, the current value flowing through the closed circuit is limited to the _pinch -off current value _Ipm of the constant current element _Em of the liquid leakage detection unit Um. As described above with reference to FIG. 22, each pinch-off current value is different, and Ip ₁ >>...> Ip _Nend . Therefore, when the current value detected by the current sensor 82 is _Ipm , the leak detection unit _Um including the constant current element _Em can be specified as the leak generation location.

<Operation of leak detection device>
Next, the operation of the leak detection device 300 will be described with reference to FIGS. 24 to 29. After the liquid leakage detection operation shown in steps S101 to 104 of FIG. 24, the liquid leakage detecting device 300 performs a saturation determination operation of the constant current element Em shown in steps S105 and _S106 of FIG. 24 to saturate the constant current element. If this is the case, the leak detection unit in which the leak has occurred is specified in step S107 of FIG. 24. As described above, the liquid leakage detection device 300 detects the leakage of liquid based on the _pinch -off current value _Ipm when the constant current element _Em of the liquid leakage detection unit Um operates in the saturation region. It identifies the unit. However, even if a liquid leak occurs, the energizing current value does not immediately rise to the pinch-off current value _Ipm , but slowly rises from zero to the pinch-off current value _Ipm . At this time, the energizing current value rises through Ipm _{+ 1} , Ip _{m + 2} , etc., which are smaller than Ipm. Therefore, if the leak location is specified without determining saturation, other leak detection units U _{m + 1} and U _{m + 2} having a pinch-off current value smaller than that of the leak detection unit U _m where the leak actually occurred. May be mistakenly identified as the location of the leak. Therefore, the liquid leakage detection device 300 performs a saturation determination operation of the constant current element _Em , and determines that it is possible to identify the liquid leakage detection unit in which the liquid leakage has occurred when the constant current element _Em is saturated. Performs specific operation of the leak detection unit. The details of each operation will be described below.

As described above, until the leakage occurs, the conductive wires 61 and 62 of the leakage detection unit U1 to _UNend are insulated from _each other, so that a closed circuit is not formed and a current flows. do not have. Therefore, the voltage value between the conductive wires 61 and 62 is V0, which is the output voltage value of the power supply 81. As shown in FIG. 25, the energization current value detected by the current sensor 82 before the time t1 when the liquid leakage occurs is zero, and the input voltage value is V0, which is the voltage value of the power supply 81.

As shown in step S101 of FIG. 24, the determination unit 90 detects the energization current value of the parallel connection line 64 with the current sensor 82, and proceeds to step S102 of FIG. 24 to detect the energization current value of a predetermined value _Is or more. Determine if. Here, the predetermined value _Is is a threshold value for determining whether or not a liquid leak has occurred. The predetermined value _{Is may be a value smaller than the pinch-off current value Ip Nend of} the constant current element E _Nend of the liquid leakage detection unit UN End having the minimum pinch-off current value and larger than zero, for example, the _{predetermined} value _Is . May be a current value that is half that of Ip _Nend . Since no current is flowing at the time zero shown in FIG. 25, the determination unit 90 determines NO in step S102 and returns to step S101 in FIG. 24 as no leak is detected in step S103 of FIG. 24, and the energization current value. Continue to monitor.

When a leak occurs at time t1 shown in FIG. 25, the leak penetrates into the hygroscopic insulating film of the conductive wires 61 and 62. As a result, the conductive lines 61 and 62 of the liquid leakage detection unit _Um become conductive, and the energization current value of the parallel connection line 64 detected by the current sensor 82 increases. Since the infiltration of the leaked liquid into the conductive wires 61 and 62 progresses slowly, the conductance _Gm is initially small, and the energization current value between the conductive wires 61 and 62 of the liquid leakage detection unit _Um is small. .. Therefore, until the time t2 in FIG. 25, the energization current value of the parallel connection line 64 detected by the current sensor 82 does not _exceed the predetermined value Is, and the determination unit 90 determines NO in step S102. Steps S101 to S103 of FIG. 24 are repeatedly executed.

From time t1 to t2 in FIG. 25, the conductance _Gm between the conductive wires 61 and 62 increases as the amount of the leaked liquid permeating into the conductive wires 61 and 62 increases, and between the conductive wires 61 and 62. The energizing current value of is gradually increased. Then, when the energization current value of the parallel connection line 64 detected by the current sensor ₈₂ reaches the predetermined value Is at the time t2 in FIG. 25, the determination unit 90 determines YES in step S102 in FIG. 24 and shows FIG. 24. The process proceeds to step S104, and the leakage is detected. Then, the determination unit 90 proceeds to step _S105 in FIG. 24 and performs an operation of determining whether or not the constant current element Em of the liquid leakage detection unit _Um is saturated.

Hereinafter, a case where the determination unit 90 performs the saturation determination operation of the constant current element Em at the time _t3 in FIG. 25 will be described. At time t3 shown in FIG. 25, the conductance _Gm of the leaked portion 65 formed between the conductive wires 61 and 62 of the leak detection unit _Um due to the leak is still small, and the voltage drop of the leaked portion 65 is large. .. Therefore, the energizing current of the constant current element _Em of the liquid leakage detection unit U _m does not reach the pinch-off current value _Ipm , the constant current element _Em becomes unsaturated, and the current value I _W flowing through the liquid leakage portion 65 is a constant current. The pinch-off current value of the element _Em is smaller than Ip _m (I _W <Ip _m ).

At this time, the constant current element _Em operates at the point R shown in FIG. 27, and the VI characteristic of the liquid leakage detecting unit 70 is shown by the solid line a in FIG. 27. Therefore, when the voltage applied to the liquid leakage detection unit 70 is changed, the energization current value of the parallel connection line 64 changes along the solid line a in FIG. 27. That is, when the constant current element _Em of the liquid leakage detection unit _Um is in an unsaturated state, the energization current value changes when the input voltage to the parallel connection line 64 of the liquid leakage detection unit 70 is changed. On the other hand, when the constant current element Em of the liquid leakage detection unit _Um becomes saturated, the constant current element _{Em limits} the energization current value to _Ipm , so that even if the input voltage to the liquid leakage detection unit 70 is changed. The energization current value of the parallel connection line 64 does not change.

Therefore, when the constant current element _Em is in an unsaturated state, as shown in FIG. 28, when the applied voltage is changed by ΔV, the amount of change ΔI of the energization current value of the parallel connection line 64 becomes a value of a certain magnitude. It becomes. On the other hand, when the constant current element _Em is saturated, as shown in FIG. 29, even if the voltage applied to the leak detection unit 70 is changed by ΔV, the amount of change in the energization current value of the parallel connection line 64 is ΔI. Is zero.

Therefore, the determination unit 90 changes the output voltage of the power supply 81 to change the voltage applied to the liquid leakage detection unit 70 by ΔV, and detects the energization current value of the parallel connection line 64 at that time by the current sensor 82. Based on the change amount ΔI of the energization current value of the parallel connection line 64, it is determined whether or not the constant current element _Em of the leak detection unit _Um in which the leak has occurred is saturated.

In the determination unit 90, the absolute value of the change amount ΔI of the energization current value of the parallel connection line 64 when the output voltage of the power supply 81 is changed and the voltage applied to the liquid leakage detection unit 70 is changed by ΔV is the first threshold value. If it is less than, it is determined that the constant current element _Em is in a saturated state, and if it is equal to or more than the first threshold value, it is determined that the constant current element _Em is in an unsaturated state. The first threshold value may be, for example, about 5 to 10% of the pinch-off current value Ip _m , or the pinch-off current value Ip Nend of the constant current element E _Nend of the liquid leakage detection unit U _Nend that minimizes the pinch-off current value _Ip. It may be about 10% of.

Further, the determination unit 90 has an inclination of the voltage-current characteristic of the liquid leakage detection unit 70 based on the change amount ΔV of the voltage applied to the liquid leakage detection unit 70 and the change amount ΔI of the energization current value of the parallel connection line 64. ΔI / ΔV is calculated, and when this inclination is less than the second threshold value, it is determined that the constant current element _Em is in the saturated state, and when it is equal to or more than the second threshold value, it is determined that the constant current element _Em is in the unsaturated state. You may.

Further, the determination unit 90 may calculate the reciprocal ΔV / ΔI instead of ΔI / ΔV to determine the saturation of the constant current element _Em .

At time t3 in FIG. 25, the VI characteristic of the liquid leakage detection unit 70 is the state of the solid line a shown in FIG. 27, and when the voltage applied to the liquid leakage detection unit 70 is changed, the energization current value of the parallel connection line 64 changes. Change. Therefore, at time t3 in FIG. 25, the determination unit 90 determines NO in step S106 of FIG. 24, proceeds to step S109, returns to step S101 of FIG. 24 while determining the leak location, and is connected in parallel by the current sensor 82. Continue monitoring the energization current value of wire 64.

As time passes, the amount of the leaked liquid permeating into the conductive wires 61 and 62 increases, and the conductance _Gm between the conductive wires 61 and 62 increases. Then, the _energization current I _W of the constant current element Em shown in FIG. 26 gradually increases. When the energization current I _W of the constant current element _Em reaches the pinch-off current value _Ipm , the constant current element _Em becomes saturated, and the energization current value of the parallel connection line 64 is limited to the pinch-off current value _Ipm . .. After the constant current element _{Em is saturated, even if the conductance Gm between the conductive wires 61 and 62 becomes larger, the resistance value RH m of the} constant current element _Em changes and the energization current value is Ip. It is held at _m . Then, after the time t4 in FIG. 25, the constant current element _Em operates in the saturation region.

Therefore, during the time from t2 to t4 shown in FIG. 25, the determination unit 90 determines NO in step S106 of FIG. 24 and repeatedly executes steps S101, S102, S104 to S106, and S109 of FIG. 24. Then, the determination unit 90 determines YES in step S106 of FIG. 24 at time t4 of FIG. 25, determines that it is possible to identify the leak detection unit _Um in which the leak has occurred, and proceeds to step S107 of FIG. , Identify the leak detection unit where the leak occurred.

In step S107 of FIG. 24, the determination unit 90 uses the energization current value of the parallel connection line 64 acquired by the current sensor 82 and the pinch-off current values Ip ₁ to each of the constant current elements E ₁ to E _Nend stored in the memory 92. It is compared with Ip _Nend , and it is determined whether or not the difference between the energization current value of the parallel connection line 64 and one of the pinch-off current values Ip ₁ to Ip _Nend is ± ΔIp _s . ΔIp _s is a predetermined range, and may be, for example, about 5 to 10% of the pinch-off current value Ip _m , or pinch-off of the constant current element E _Nend of the liquid leakage detection unit UN _End that minimizes the pinch-off current value Ip. The current value may be about 10% of Ip _Nend .

Then, the determination unit 90 generates a leak in the leak detection unit U _m including the pinch-off current value _Ipm whose difference from the energization current value of the parallel connection line 64 detected by the current sensor 82 is in the range of ± _ΔIps . Identify it as a leak detection unit.

The determination unit 90 proceeds to step S108 shown in FIG. 24, and outputs the liquid leakage generation signal and the liquid leakage location signal to the outside via the output interface 94. On a display device (not shown) connected via the output interface 94, a display such as "leakage generation, leak location: detection unit number 3" is displayed. Further, a liquid leakage warning lamp (not shown) connected via the output interface 94 is turned on.

As described above, in the liquid leakage detection device 300 of the embodiment, a plurality of liquid leakage detection units U ₁ to _UN End including constant current elements E ₁ to E _Nend having different current limiting values are connected in parallel, and a current sensor 82 is connected. The current value of the parallel connection line 64 detected in the above is compared with the current limiting current values of the constant current elements E ₁ to E _Nend , Ip ₁ to Ip _Nend , to identify the leak detection unit in which the leak occurred, which is convenient. The configuration can improve the detection reliability of the leaked part.

<Variations of constant current elements>
In the liquid leakage detection device 300 of the above-described embodiment, as described with reference to FIG. 19, the constant current element _Em of the node ND _m faces the anodes and the pinch-off current value _Ipm is the same constant current. Although the description has been made assuming that the diodes 17a and 17b are connected in anti-series, the configuration of the constant current element Em is not limited to this, and as shown in FIG. _30A , the connection directions of the constant current diodes 17 and 17b are shown. Contrary to the state shown in 19, the cathodes may be faced to each other and connected in anti-series. Further, as shown in FIG. 30 (b), the connection line 12 may be arranged on the side opposite to the side shown in FIG. Further, as shown in FIGS. 30 (c) and 30 (d), one constant current diode 17a and one 17b are arranged in the same direction on each of the two connection lines 12, and the current when liquid leakage occurs. The two constant current diodes CRD may be in anti-series with respect to the flow of. Further, as shown in FIG. 30 (e), the constant current diode 17a may be interposed only in one of the connection lines 12. In this case, the power supply 81 may be configured by using a DC constant voltage power supply. Further, instead of using the constant current diodes 17a and 17b, as shown in FIG. 30 (f), a constant current element circuit 19 in which an electric circuit having voltage-current characteristics as shown in FIG. 21 is composed of an IC or the like may be used. ..

In this way, by variously changing the arrangement of the constant current element _Em of the node ND _m according to the liquid to be detected, it is possible to detect the leak according to the liquid to be detected.

Although the leak detection device 300 of the present embodiment has been described as being configured such that the limit current value _Ipm of the constant current element _Em becomes smaller as the detection unit number N becomes larger, the constant current is described. The limiting current value _Ipm of the element _Em may be different from each other. For example, conversely, the limiting current value may be configured to decrease as the detection unit number N decreases.

11a, 11b Zener diode, 12 connection line, 13,15 start end side terminal, 14,16 end side terminal, 17a, 17b constant current diode, 18 constant voltage element circuit, 19 constant current element circuit, 60 leak detection band, 61 , 62 Conductive wire, 61e, 62e end, 63 Insulated coated wire, 64 Parallel connection line, 65 Leakage part, 70 Leakage detector, 71 Start end, 72 end, 79 end resistance, 81 power supply, 82 current sensor, 83 Voltage sensor, 90 Judgment unit, 91 CPU, 92 memory, 93 input interface, 94 output interface, 95 data bus, 100, 200, 300 leak detector, CRD constant current diode, D, D ₁ to D ₅ , D _m Constant voltage element, E, E ₁ to E _Nend , Em constant current element, Ip ₁ to Ip _Nend , Ip _m Pinch-off current value (current limit value ₎ , _Is predetermined value, N Leakage detection unit number (detection unit number) ), ND, ND ₁ to ND _Nend , ND _m node, U, U ₁ to U _Nend , U _m leak detection unit, Vp ₁ to Vp _Nend , Vp _m pinch-off voltage value.

Claims (17)

It consists of a pair of conductive wires, a leak detection band in which a current flows when a leak comes into contact between the conductive wires, and a constant that conducts when the applied voltage reaches a predetermined conduction voltage value connected to the leak detection band. A leakage detection unit in which a node having a voltage element and a plurality of leakage detection units including the leakage detection unit are connected in parallel by a parallel connection line, and a leakage detection unit.
A power supply connected to the parallel connection line of the liquid leakage detection unit, and
A current detection unit that detects the input current value of the parallel connection line of the liquid leakage detection unit, and a current detection unit.
A determination unit for determining the occurrence of liquid leakage from the input current value detected by the current detection unit is provided.
The leak detection unit is
Each of the leak detection units has the characteristic of conducting conduction according to the input voltage value.
The conduction voltage value of each constant voltage element of each leak detection unit is different.
A leak detection device characterized by. The liquid leakage detection device according to claim 1.
The node of the leak detection unit
A pair of start end side terminals to which the parallel connection lines are connected,
A pair of terminal terminals to which the pair of conductive wires of the liquid leakage detection unit are connected, respectively.
Includes a pair of connecting wires that connect the start end side terminal and the end end side terminal in parallel.
The constant voltage element is arranged so as to be interposed between one or both connection lines.
A leak detection device characterized by. The liquid leakage detection device according to claim 1 or 2.
The power supply applies a standby voltage having a predetermined voltage value to the parallel connection line of the liquid leakage detection unit.
The determination unit determines the occurrence of liquid leakage in at least one liquid leakage detection unit by comparing the input current value detected by the current detection unit with a predetermined threshold value.
A leak detection device characterized by. The liquid leakage detection device according to claim 1 or 2.
The power supply outputs a voltage corresponding to the voltage command value input from the determination unit.
The determination unit fluctuates the voltage command value output to the power supply before and after the standby voltage value, and fluctuates the input voltage value of the liquid leakage detection unit before and after the standby voltage value.
At least one leak detection unit by comparing a conductance or resistance value calculated from the voltage command value or the input voltage value and the input current value detected by the current detector with a predetermined threshold value. To determine that a leak has occurred in
A leak detection device characterized by. The liquid leakage detection device according to claim 1 or 2.
The power supply outputs a voltage corresponding to the voltage command value input from the determination unit.
The determination unit sweeps the voltage command value output to the power supply, sweeps the input voltage value of the leak detection unit, and conducts each of the leak detection units in ascending order of the conduction voltage value.
By comparing the conductance or resistance value calculated from the voltage command value or the input voltage value with the input current value detected by the current detection unit and a predetermined threshold value, the liquid leakage detection unit in the conductive state is included. , Determining that a leak has occurred in at least one of the leak detection units.
A leak detection device characterized by. The liquid leakage detection device according to claim 1 or 2.
The power supply outputs a voltage corresponding to the voltage command value input from the determination unit.
The determination unit sweeps the voltage command value output to the power supply, sweeps the input voltage value of the leak detection unit, and conducts each of the leak detection units in ascending order of the conduction voltage value.
The input current value detected by the current detection unit when the range up to the liquid leakage detection unit of the liquid leakage detection unit is set to the conduction state, and the conduction voltage value next to the liquid leakage detection unit. The conductance of one of the leak detection units is calculated by using the input current value detected by the current detection unit when the range up to the other leak detection unit is made conductive.
By comparing the calculated conductance with a predetermined threshold value, the leak detection unit in which the leak has occurred can be identified.
A leak detection device characterized by. It consists of a pair of conductive wires, a leak detection band in which a current flows when a leak comes into contact between the conductive wires, and a constant that conducts when the applied voltage reaches a predetermined conduction voltage value connected to the leak detection band. A liquid leakage detection unit in which a node having a voltage element and a liquid leakage detection unit including the liquid leakage detection unit are connected in parallel by a parallel connection line and a resistor is connected between the conductive lines at the ends.
A power supply connected to the parallel connection line of the liquid leakage detection unit, and
A voltage detection unit that detects the input voltage value of the parallel connection line of the liquid leakage detection unit, and a voltage detection unit.
A determination unit for determining the occurrence of liquid leakage from the input voltage value detected by the voltage detection unit is provided.
The leak detection unit is
Each of the leak detection units has a characteristic of conducting conduction according to the input voltage value.
The conduction voltage value of each constant voltage element of each leak detection unit is different.
A leak detection device characterized by. The liquid leakage detection device according to claim 7.
The node of the leak detection unit
A pair of start end side terminals to which the parallel connection lines are connected,
A pair of terminal terminals to which the pair of conductive wires of the liquid leakage detection unit are connected, respectively.
Includes a pair of connecting wires that connect the start end side terminal and the end end side terminal in parallel.
The constant voltage element is arranged so as to be interposed between one or both connection lines.
A leak detection device characterized by. The liquid leakage detection device according to claim 7 or 8.
The power supply inputs a standby current having a predetermined current value to the liquid leakage detection unit, and receives the standby current.
The determination unit determines the occurrence of liquid leakage by comparing the input voltage value detected by the voltage detection unit with a predetermined threshold value.
A leak detection device characterized by. It consists of a pair of conductive wires, a leak detection band in which current flows when a leak comes into contact between the conductive wires, and a current limiting current value connected to the leak detection band. A node having a constant current element to limit, a leak detection unit in which a plurality of leak detection units including the leak detection unit are connected in parallel by a parallel connection line, and a leak detection unit.
A power supply that is connected to the parallel connection line of the liquid leakage detection unit and applies a voltage to the liquid leakage detection unit.
A current detection unit that detects the energization current value of the parallel connection line of the liquid leakage detection unit, and a current detection unit.
A liquid leakage detection device including a determination unit for determining the leak detection unit in which a leak has occurred from the energization current value detected by the current detection unit.
The current limit value of each constant current element of each leak detection unit is different.
The determination unit compares the energization current value detected by the current detection unit with the current limit value of the constant current element to identify the leak detection unit in which the leak has occurred.
A leak detection device characterized by. The liquid leakage detection device according to claim 10.
The node of the leak detection unit
A pair of start end side terminals to which the parallel connection lines are connected,
A pair of terminal terminals to which the pair of conductive wires of the leak detection band are connected, respectively.
Includes a pair of connecting wires that connect the start end side terminal and the end end side terminal in parallel.
The constant current element is arranged so as to be interposed between the connection line of either one or both.
A leak detection device characterized by. The liquid leakage detection device according to claim 10 or 11.
When the difference between the energization current value detected by the current detection unit and the current limiting current value of the constant current element of the leak detection unit is within a predetermined range, the determination unit is one of the leaks. Identifying the detection unit as the location of the leak,
A leak detection device characterized by. The liquid leakage detection device according to any one of claims 10 to 12.
The determination unit determines that liquid leakage is detected when the energization current value detected by the current detection unit is equal to or higher than a predetermined value.
A leak detection device characterized by. The liquid leakage detection device according to claim 13.
When the determination unit determines that the liquid leakage has been detected, the determination unit changes the output voltage of the power supply, and the current detection unit detects the amount of change in the energization current value of the liquid leakage detection unit.
Judging whether it is possible to identify the leak detection unit in which the leak has occurred from the current current value based on the amount of change in the current current value.
A leak detection device characterized by. The liquid leakage detection device according to claim 14.
When the absolute value of the amount of change in the energization current value is less than a predetermined first threshold value, the determination unit determines that the leak detection unit in which the leak has occurred can be identified from the energization current value.
A leak detection device characterized by. The liquid leakage detection device according to claim 14.
The determination unit
The slope of the voltage-current characteristic of the liquid leakage detection unit is calculated based on the change amount of the output voltage of the power supply and the change amount of the energization current value detected by the current detection unit.
When the inclination is less than a predetermined second threshold value, it is determined that the leak detection unit in which the leak has occurred can be identified from the energization current value.
A leak detection device characterized by. The liquid leakage detection device according to any one of claims 14 to 16.
The determination unit
When it is determined that the leak detection unit in which the leak has occurred can be identified from the energization current value detected by the current detection unit.
When the difference between the energization current value detected by the current detection unit and the current limit value of the constant current element of the leak detection unit is within a predetermined range, the leak detection unit is leaked. Identifying the location of occurrence,
A leak detection device characterized by.

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