Monitoring devices, monitoring systems, and damage assessment systems

Abstract

Even with a small storage capacity, it continuously monitors the target object without batteries and without maintenance. [Solution] The monitoring device 10 is a device that uses a thermoelectric battery 20, which has a thermoelectric element that outputs a voltage corresponding to the temperature difference between the temperature of the atmosphere surrounding the object to be monitored and the temperature of the contact part of the object to be monitored, as a sensor, and comprises a boost circuit 11 that outputs a boosted voltage obtained by boosting the voltage input from the thermoelectric battery, a storage element 12 connected to the output terminal 112 of the boost circuit that stores the power supplied from the thermoelectric battery 20, which is the sensor, and boosted by the boost circuit 11, a voltage detection circuit 13 that outputs a control signal including a signal level corresponding to whether or not the detected boosted voltage exceeds a predetermined voltage, and a switch 14 that opens and closes a path connecting a first terminal and a second terminal connected to the output terminal 112.

Description

Technical Field

[0001] The present invention relates to a monitoring device, a monitoring system, and a damage evaluation system.

Background Art

[0002] There has been proposed a monitoring device (hereinafter referred to as "conventional battery - less monitoring device") that monitors the temperature of a wire connection part without a battery (see, for example, Patent Document 1). The conventional battery - less monitoring device includes a power supply unit having a solar cell, a power storage device, and a power management unit (see, for example, FIG. 2 of Patent Document 1). In the power supply unit, the solar cell generates electricity by sunlight. The power storage device is charged by the solar cell and supplies power by discharging. The power management circuit controls the charging and discharging of the power storage device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The conventional battery - less monitoring device uses the generated power from the solar cell to charge the power storage device. The solar cell cannot generate electricity at night, on rainy days when there is no sunlight. Also, due to dirt on the surface of the solar cell, etc., the original power generation amount of the solar cell may not be obtained, so maintenance such as cleaning the surface of the solar cell occurs as needed.

[0005] For these reasons, conventional battery-less monitoring devices are equipped with a configuration that allows them to operate stably for extended periods. Examples of configurations that allow the monitoring device to operate stably for a desired period include configurations that do not use a battery, such as those that use a separate primary battery as an auxiliary power source, or configurations that use a capacitor with a larger capacity than other capacitors, such as an electric double-layer capacitor.

[0006] However, the configuration required to operate the monitoring device stably for the desired period can be reduced if a stable power generation can be obtained, indicating room for improvement toward a battery-less monitoring device. Furthermore, since conventional battery-less monitoring devices require maintenance of the solar cells that power the device, there is room for improvement in terms of maintainability. In addition, if the configuration required to operate the monitoring device stably for the desired period becomes unnecessary, there is the secondary benefit of contributing to further miniaturization of the device.

[0007] The present invention was made to solve the above-mentioned problems, and aims to provide a monitoring device, monitoring system, and damage assessment system that can continuously monitor a target object in a battery-less and maintenance-free manner, even with a small energy storage capacity. [Means for solving the problem]

[0008] To solve the above-mentioned problems, the monitoring device according to the present invention is a monitoring device that uses a thermoelectric cell, which is attached to the object to be monitored and has a thermoelectric element that outputs a voltage corresponding to the temperature difference between the temperature of the atmosphere surrounding the object to be monitored and the temperature of a contact part that is in contact with the object to be monitored, as a sensor, and monitors the object to be monitored based on the voltage corresponding to the temperature difference, and is characterized by comprising: a boost circuit including an input terminal that receives a voltage from the thermoelectric cell and an output terminal that outputs a boosted voltage obtained by boosting the voltage input from the input terminal; an energy storage element connected to the output terminal of the boost circuit that stores power supplied from the thermoelectric cell, which is the sensor, and boosted by the boost circuit; a voltage detection circuit that detects the boosted voltage and outputs a control signal from the output terminal including a signal level corresponding to when the boosted voltage exceeds a predetermined voltage and when it does not, respectively; and a switch including a first terminal and a second terminal connected to the output terminal of the boost circuit, which opens and closes a path connecting the first terminal and the second terminal based on the control signal.

[0009] To solve the above-mentioned problems, the monitoring system according to the present invention is a damage evaluation system that uses a thermoelectric cell, which is attached to a target to be monitored and has a thermoelectric element that outputs a voltage corresponding to the temperature difference between the temperature of the atmosphere surrounding the target to be monitored and the temperature of the contact part with the target to be monitored, as a sensor, and evaluates the degree of damage to the target to be monitored based on the voltage corresponding to the temperature difference, and is characterized by comprising a boost circuit including an input terminal that receives a voltage from the thermoelectric cell and an output terminal that outputs a boosted voltage obtained by boosting the voltage input from the input terminal; a storage element connected to the output terminal of the boost circuit that stores power supplied from the thermoelectric cell, which is the sensor, and boosted by the boost circuit; a voltage detection circuit that detects the boosted voltage and outputs a control signal from the output terminal that includes a signal level corresponding to when the boosted voltage exceeds a predetermined voltage and when it does not, respectively; and a transmission circuit connected to the voltage detection circuit via a switch that is controlled to open and close based on the control signal, which transmits to an evaluation device that evaluates the degree of damage to the target to be monitored based on a monitoring signal including identification information of the thermoelectric cell.

[0010] The damage evaluation system according to the present invention solves the above-mentioned problems and uses a thermoelectric cell as a sensor, which is attached to a target to be monitored and has a thermoelectric element that outputs a voltage corresponding to the temperature difference between the temperature of the atmosphere surrounding the target and the temperature of the contact part with the target to be monitored, and transmits a monitoring signal including identification information of the thermoelectric cell from a monitoring device that monitors the target based on the voltage corresponding to the temperature difference to an evaluation device that evaluates the degree of damage to the target, and is characterized by comprising a boost circuit including an input terminal that receives a voltage from the thermoelectric cell and an output terminal that outputs a boosted voltage obtained by boosting the voltage input from the input terminal, an energy storage element connected to the output terminal of the boost circuit that stores power supplied from the thermoelectric cell which is the sensor and boosted by the boost circuit, a voltage detection circuit that detects the boosted voltage and outputs a control signal from the output terminal including a signal level corresponding to when the boosted voltage exceeds a predetermined voltage and when it does not, respectively, and a transmitting circuit connected to the voltage detection circuit via a switch that is opened and closed based on the control signal and transmits to an evaluation device that evaluates the degree of damage to the target based on the monitoring signal including identification information of the thermoelectric cell. [Effects of the Invention]

[0011] According to the present invention, even with a small energy storage capacity, the target of monitoring can be continuously monitored without a battery and without maintenance. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram showing an example configuration of a monitoring device and monitoring system according to an embodiment of the present invention. [Figure 2] This is a schematic diagram showing an example of the configuration of a thermal battery, which is a sensor for the monitoring device according to this embodiment. [Figure 3] This is an explanatory diagram showing the power generation characteristics (power output in relation to temperature difference) of the thermoelectric element contained in a thermal cell. [Figure 4] This is an explanatory diagram showing the boost characteristics (boost time relative to generated voltage) of the boost circuit provided in the monitoring device according to this embodiment. [Figure 5]It is a schematic diagram showing a configuration example of a damage evaluation system according to this embodiment. [Figure 6] It is a schematic diagram showing an application example of a damage evaluation system according to this embodiment.

Mode for Carrying Out the Invention

[0013] Hereinafter, a monitoring device, a monitoring system, and a damage evaluation system according to an embodiment of the present invention will be described with reference to the drawings.

[0014] FIG. 1 is a schematic diagram showing a configuration example of a monitoring device 10 and a monitoring system 50 which are an example of the monitoring device and the monitoring system according to this embodiment.

[0015] The monitoring system 50 is configured to include at least one monitoring device 10 and a receiving device 30 communicably connected to the monitoring device 10.

[0016] The monitoring device 10 includes a boosting circuit 11, a power storage element 12, a voltage detection circuit 13, a switch 14, and a transmission circuit 15, and is configured to be connectable to a thermoelectric battery 20. Here, the connection point between the thermoelectric battery 20 and the monitoring device 10 is referred to as an input node 101.

[0017] The boosting circuit 11 includes an input terminal 111 which is the same node as the input node 101 and an output terminal 112. The power storage element 12 includes a first terminal connected to the output terminal 112 and a second terminal connected to a GND terminal 2 which is a node for supplying a ground voltage GND which is an example of a power supply voltage.

[0018] The voltage detection circuit 13 includes an input terminal 131 connected to a node N1 which is a connection point between the output terminal 112 and the first terminal of the power storage element 12, and an output terminal 132 which outputs a control signal including a signal level corresponding to whether or not the boosted voltage supplied to the input terminal 131 exceeds a predetermined voltage.

[0019] Switch 14 includes a first terminal connected to output terminal 112, a second terminal, and a control terminal connected to output terminal 132. According to the signal level of the control signal, the first terminal and the second terminal are switched and controlled (opened and closed) between an open state (open state) and a short-circuit state (closed state). In the following description, the first terminal and the second terminal of switch 14 are simply referred to as both terminals.

[0020] Transmission circuit 15 is a circuit capable of communicating a monitoring signal to the outside of monitoring device 10 such as receiving device 30. Transmission circuit 15 includes input terminal 151 connected to the second terminal of switch 14. For example, transmission circuit 15 capable of wireless transmission transmits a monitoring signal wirelessly to receiving device 30 outside monitoring device 10.

[0021] FIG. 2 is a schematic diagram showing a configuration example of thermoelectric battery 20. FIG. 3 is an explanatory diagram illustrating the power generation characteristics (power generation output with respect to temperature difference) of thermoelectric power generation elements 21 and 22 included in thermoelectric battery 20, with the horizontal axis being temperature difference T [°C] and the vertical axis being power generation voltage Vout [V].

[0022] Thermoelectric battery 20 as a sensor connected to monitoring device 10 is configured to have at least one thermoelectric power generation element 21, 22, for example, two. Thermoelectric power generation elements 21, 22 are elements that connect a p-type semiconductor element and an n-type semiconductor element in series and generate a voltage proportional to the temperature difference between the surface on the high-temperature side and the surface on the low-temperature side (see FIG. 3).

[0023] The thermoelectric battery 20 illustrated in FIG. 2 has two thermoelectric power generation elements 21, 22 connected in series by connection conductor 23. Connection conductor 23 can be any object that can electrically connect thermoelectric power generation element 21 and thermoelectric power generation element 22, that is, a conductor. However, if importance is attached to the degree of freedom when attaching thermoelectric power generation element 21 and thermoelectric power generation element 22, that is, ease of attachment, it is preferably a conductor having appropriate flexibility and length.

[0024] Subsequently, the operations and effects of monitoring device 10 and monitoring system 50 will be described. The thermoelectric elements 21 and 22 that make up the thermal cell 20 generate electricity in proportion to the temperature difference between the surface to which they are attached to the object being monitored (hereinafter referred to as the "mounting surface") and the surface to which they are not attached, i.e., the surface exposed to the atmosphere covering the thermoelectric elements 21 and 22 (hereinafter referred to as the "exposed surface"). If the high temperature side is 50 [°C] and the low temperature side is 30 [°C], the temperature difference is 20 [°C], so if the power generation capacity of one thermoelectric element 21 (or 22) is 10 [mV / °C], it will generate 200 [mV].

[0025] The power generated by the thermal battery 20 is supplied to the connected monitoring device 10 (more specifically, the boost circuit 11). The voltage generated by the thermal battery 20 is low, on the order of 100 mV / unit or less, when the power generation capacity is small, such as in the example described above where the temperature difference is less than 10°C, and therefore cannot directly drive the transmitting circuit 15. The boost circuit 11 boosts the voltage supplied from the input terminal 111 to a voltage that allows the transmitting circuit 15 to operate as desired (e.g., 2.0 V). The energy supplied by the thermal battery 20 and boosted by the boost circuit 11 is stored in the energy storage element 12.

[0026] Figure 4 is an explanatory diagram illustrating the boost characteristics (boost time relative to generated voltage) of the boost circuit 11, with the horizontal axis representing the generated voltage Vout [V] of the thermal battery 20 and the vertical axis representing the boost time t [seconds].

[0027] The boost time t [seconds] of the boost circuit 11 depends on the voltage supplied to the boost circuit 11, i.e., the generated voltage Vout [V] of the thermal battery 20. As shown in Figure 4, the boost time t [seconds] is longer when the generated voltage Vout [V] is low, and shorter when the generated voltage Vout [V] is high.

[0028] The voltage detection circuit 13 detects whether the voltage at the output terminal 112 of the boost circuit 11, the first terminal of the energy storage element 12, and the input terminal 131 of the voltage detection circuit 13, i.e., node N1, exceeds a predetermined voltage set as a threshold voltage, and outputs a control signal from the output terminal 132 that includes a signal level corresponding to the detection result. The threshold voltage of the voltage detection circuit 13 is set to be, for example, a voltage that can supply enough energy for the transmission circuit 15 to transmit a monitoring signal once, as the amount of charge in the energy storage element 12.

[0029] The voltage detection circuit 13 outputs a control signal of a first signal level, such as a low level, from its output terminal 132 when the voltage at node N1 is below the threshold voltage of the voltage detection circuit 13. On the other hand, when the boosting of the supplied generated power begins and the voltage at node N1 rises and eventually exceeds the threshold voltage of the voltage detection circuit 13, it outputs a control signal of a second signal level, such as a high level, from its output terminal 132.

[0030] Switch 14 opens a path connecting both ends when it receives a control signal of a first signal level at its control terminal, and closes a path connecting both ends when it receives a control signal of a second signal level at its control terminal. Switch 14 remains open at both ends until the voltage at node N1 exceeds the threshold voltage of the voltage detection circuit 13, i.e., when it receives a control signal of a first signal level at its control terminal. When the voltage at node N1 exceeds the threshold voltage of the voltage detection circuit 13, i.e., when it receives a control signal of a second signal level at its control terminal, it becomes closed with both ends short-circuited.

[0031] Therefore, when the voltage at node N1 rises and exceeds the threshold voltage of the voltage detection circuit 13, the switch 14 transitions from the open state to the closed state, and the input terminal 151 of the transmitting circuit 15 is short-circuited with node N1. With node N1 short-circuited, the transmitting circuit 15 has a voltage supplied to its input terminal 151 that allows it to transmit a monitoring signal to the external receiving device 30, and therefore transmits the monitoring signal to the receiving device 30. The monitoring signal includes identification information that allows it to identify the thermal battery 20 connected to the monitoring device 10.

[0032] Here, we will explain the voltage at which the transmitting circuit 15 can transmit a monitoring signal once. When the transmitting circuit 15 is configured as a wireless transmitting circuit capable of wireless communication, the wireless communication method adopted is arbitrary as long as wireless communication between the monitoring device 10 and the receiving device 30 is possible. However, since the voltage and energy at which a monitoring signal can be transmitted once differ depending on the wireless communication method adopted, the capacity value of the energy storage element 12 and the boosted voltage of the boost circuit 11 are determined according to the wireless communication method adopted.

[0033] For example, comparing the case of using Bluetooth® Low Energy (hereinafter referred to as "BLE"), which is suitable for short communication distances, with the case of using LoRa WAN®, which is suitable for longer communication distances than BLE, the transmission circuit 15 using LoRa WAN® requires approximately 10 times the wireless communication energy of the transmission circuit 15 using BLE. Therefore, the capacity value of the energy storage element 12 of the monitoring device 10 equipped with a transmission circuit 15 using LoRa WAN® is configured to be approximately 10 times that of the energy storage element 12 of the monitoring device 10 equipped with a transmission circuit 15 using BLE.

[0034] The receiving device 30 receives monitoring signals from the monitoring device 10. The monitoring signals received by the receiving device 30 include identification information that allows for the identification of the thermal battery 20 connected to the monitoring device 10. Therefore, even in a monitoring system 50 equipped with multiple n monitoring devices 10, the receiving device 30 can individually grasp the status of n monitored objects.

[0035] As described above, with the monitoring device 10 and monitoring system 50, even if the supplied generated power is small, by providing the boost circuit 11, when the boost circuit 11 obtains a boosted voltage that exceeds the voltage at which a monitoring signal can be transmitted once in relation to the generated power obtained when an abnormality is expected to occur, the monitoring signal can be transmitted to an external device such as the receiving device 30.

[0036] The monitoring device 10 and monitoring system 50 employ a thermal battery 20 that can serve as both a power source and a sensor, thereby enabling the creation of a device and system that are not affected by weather and time of day, compared to conventional monitoring devices and systems that use solar cells as power sources. Furthermore, since maintenance such as surface cleaning, which is required for solar cells, is unnecessary, the burden of inspecting and maintaining the power source can be reduced compared to conventional monitoring devices and systems that use solar cells as power sources.

[0037] Furthermore, if the monitoring device 10 includes a storage element 12 with one end connected to the output terminal 112 of the boost circuit 11, energy will be stored in the storage element 12 as long as the power supply continues, even intermittently. This allows the minimum capacity of the storage element 12 to be reduced to a capacity that can store enough power for the transmission circuit 15 to transmit a monitoring signal once. Therefore, unlike conventional monitoring devices and systems that employ solar cells, it is not necessary to provide a separate primary battery as an auxiliary power source or to include a large-capacity storage element such as an electric double-layer capacitor. Consequently, a smaller monitoring device 10 can be provided than conventional monitoring devices.

[0038] In the monitoring device 10 and monitoring system 50, if the thermal battery 20 is configured with thermoelectric elements 21 and 22 connected in series, the generated voltage can be increased compared to the case with only one element, and the boosting time, i.e., the interval of the monitoring signal transmission time, can be shortened. Furthermore, when configured with thermoelectric elements 21 and 22, if one of the thermoelectric elements 21 or 22 is generating power, the monitoring operation can be continued, thus creating a monitoring device 10 that is more resistant to sensor failures.

[0039] Furthermore, the monitoring device 10 and monitoring system 50 can be configured as event-driven devices and systems that wirelessly transmit signals when an abnormality (temperature rise due to heat generation) occurs in the monitored object. In addition, since the thermal battery 20 of the monitoring device 10 and monitoring system 50 serves as both a power source and a sensor, monitoring of the monitored object can continue even without a battery, while receiving power supply. With the monitoring device 10 and monitoring system 50, the time interval for transmitting the monitoring signal becomes shorter as the temperature difference increases, and the time interval for transmitting the monitoring signal becomes longer as the temperature difference decreases.

[0040] Therefore, the monitoring device 10 and monitoring system 50 do not need to constantly monitor the temperature from wirelessly transmitted data, as in conventional monitoring devices and systems, as long as they monitor the transmission time interval of the monitoring signal from the transmission circuit 15, that is, the time interval of receiving the monitoring signal in the receiving device 30. Consequently, the power consumption required for the operation of the monitoring device 10 and monitoring system 50 can be reduced, contributing to battery-less operation.

[0041] Furthermore, using a thermal cell 20, which generates power output based on the temperature difference between the high-temperature and low-temperature sides, as a sensor is superior to simply using a temperature sensor that measures the temperature of the contact point, because it can take into account changes in the ambient temperature around the monitored object. For example, it can take into account changes in temperature that occur with the changing seasons, so it can detect abnormalities in the monitored object more accurately.

[0042] Thus, with the monitoring device 10 and monitoring system 50, it is sufficient to store enough energy to transmit a monitoring signal once, and even if the capacity value of the energy storage element 12 is small, the monitored object can be continuously monitored without a battery and without maintenance.

[0043] Next, we will describe a case in which the monitoring system according to this embodiment functions as a damage evaluation system for evaluating the degree of damage to the monitored object.

[0044] Figure 5 is a schematic diagram showing the configuration of a damage evaluation system 60, which is an example of a damage evaluation system according to this embodiment.

[0045] The damage evaluation system 60 is one embodiment of the monitoring system 50, in which the receiving device 30 of the monitoring system 50 functions as an evaluation device 300. That is, the damage evaluation system 60 is configured to include a monitoring device 10 and an evaluation device 300 having the function of receiving monitoring signals and the function of evaluating the degree of damage to the monitored object.

[0046] The evaluation device 300 is realized, for example, by having hardware such as a computer capable of executing programs (hereinafter referred to as "PG") execute the evaluation PG 31, which is software. If the receiving device 30 has a processor capable of executing PG, the processor executes the evaluation PG 31, thereby realizing in the hardware receiving device 30 a function to evaluate the degree of damage to the monitored object, as well as a function to receive monitoring signals. In other words, the evaluation PG 31 and the receiving device 30 work together to make the receiving device 30 function as an evaluation device 300 comprising a receiving unit 301 which is a means for receiving monitoring signals, an evaluation unit 303 which is a means for evaluating the degree of damage to the monitored object, and a control unit 302 which controls the receiving unit 301 and the evaluation unit 303.

[0047] The control unit 302 provides the monitoring signal received by the receiving unit 301 to the evaluation unit 303, which evaluates the degree of damage to the monitored object.

[0048] The evaluation unit 303 includes reception history information of the received monitoring signals and information representing the relationship between the time interval at which the monitoring signals are received, the resistance value of the monitored object, and the corresponding degree of damage. Based on the reception interval of the monitoring signals received from the receiving unit 301, the evaluation unit 303 evaluates the degree of damage to the monitored object to which the thermoelectric elements 21 and 22, which are sensors, are attached.

[0049] The time interval for receiving the monitoring signal corresponds to the time it takes for the voltage at node N1 to exceed the threshold voltage of the voltage detection circuit 13, i.e., the boosting time by the boost circuit 11. Therefore, the greater the power generated by the thermal battery 20, the shorter the time interval for receiving the monitoring signal, and the smaller the power generated by the thermal battery 20, the longer the time interval for receiving the monitoring signal.

[0050] Furthermore, there is a relationship between conductor damage and resistance: less damage results in lower resistance, and greater damage results in higher resistance. From this, it can be evaluated that the greater the Joule heat generated during conduction, that is, the higher the temperature of the contact area with the monitored object, the greater the conductor damage. Considering the above relationship, the evaluation unit 303 evaluates that the damage to the monitored object is small if the temperature difference corresponding to the voltage of the thermoelectric elements 21 and 22 attached to the monitored object is small, and evaluates that the damage to the monitored object is large if the temperature difference corresponding to the voltage of the thermoelectric elements 21 and 22 is large.

[0051] Here, information representing the relationship between the time interval for receiving the monitoring signal and the degree of damage to the monitored object can be obtained based on information representing the relationship between the time interval for receiving the monitoring signal and the voltage corresponding to the temperature difference between the thermoelectric elements 21 and 22, and information representing the voltage corresponding to the temperature difference between the thermoelectric elements 21 and 22 attached to the monitored object and the degree of damage to the monitored object. Furthermore, the type of information representing the relationship between the time interval for receiving the monitoring signal and the degree of damage to the monitored object is arbitrary, as long as the final result, the degree of damage to the monitored object, can be obtained.

[0052] To describe the evaluation device 300 in terms of procedure, the procedure by which the evaluation device 300 evaluates the degree of damage to the monitored object (hereinafter referred to as the "damage evaluation procedure") includes the steps of receiving a monitoring signal from the monitoring device 10, determining the time interval for receiving the monitoring signal, and evaluating the degree of damage to the monitored object based on information representing the relationship between the time interval for receiving the monitoring signal and the degree of damage to the monitored object. In other words, the evaluation PG 31 described above is a PG that causes program-executable hardware to execute the damage evaluation procedure.

[0053] Next, we will explain examples of the application of the damage assessment system 60. Figure 6 is a schematic diagram showing an example of the application of the damage assessment system 60, in which the monitoring device 10 and the thermoelectric elements 21 and 22, which are sensors, are attached to the electric wire 80, which is the object to be monitored for damage assessment.

[0054] As shown in Figure 6, the electric wire 80 is constructed by inserting two electric wires 81 and 82, which are multiple examples, into a metal connecting tube called a sleeve 83, compressing them, and mechanically and electrically connecting (crimping) the electric wires 81 and 82. In the electric wire 80, where electric wires 81 and 82 are mechanically and electrically connected by crimping, the sleeve 83, which is the connection point, is more prone to breakage than other parts. Therefore, by attaching thermoelectric elements 21 and 22, which are sensors, to the sleeve 83 at different positions (first position and second position), it is possible to estimate the temperature of the connection point and evaluate the degree of damage to the electric wire 80 based on the estimated temperature.

[0055] In the monitored device illustrated in Figure 6, current flows through the wire 80. If the sleeve 83 is damaged for any reason, its resistance increases, and the amount of Joule heat generated increases. This increase in Joule heat raises the temperature of the sleeve 83, causing the temperature of the high-temperature side of the thermoelectric elements 21 and 22, which are the mounting surfaces with the sleeve 83, to rise. As a result of the increased temperature on the high-temperature side, the temperature difference with the exposed surface (low-temperature side) widens, causing the generated voltage to increase.

[0056] According to the damage evaluation system 60, in which thermoelectric elements 21 and 22 are attached to the sleeve 83, the temperature of the sleeve 83, which is the connection point of the electric wire 80, can be continuously monitored, so that changes in Joule heat generated in the sleeve 83, i.e., changes in the resistance of the connection point, can be detected at an early stage. Therefore, even if an abnormality occurs at the connection point of the electric wire 80, which is the target of monitoring, where the temperature is higher than normal, the abnormality can be detected early, and the location where the abnormality is detected can be efficiently maintained.

[0057] As described above, with the monitoring device 10 and damage evaluation system 60, in addition to the effects of the monitoring device 10 and monitoring system 50, if the monitored object is an energized conductor such as an electric wire 80, the increase in resistance value due to the progression of damage can be detected as a temperature rise. Therefore, the degree of damage to the monitored object can be evaluated based on information representing the relationship between the time interval for receiving the monitoring signal and the degree of damage to the monitored object. In other words, with the monitoring device 10 and damage evaluation system 60, even if the capacity value of the energy storage element 12 is small, monitoring of the monitored object and evaluation of the degree of damage to the monitored object can be continued without a battery and without maintenance.

[0058] It should be noted that the present invention is not limited to the embodiments described above, and in practice, it can be implemented in various forms other than those described above, and various omissions, additions, substitutions, or modifications can be made without departing from the spirit of the invention.

[0059] For example, although a monitoring device 10 equipped with a transmission circuit 15 has been described, the monitoring device 10 may omit the transmission circuit 15 and be configured so that the input terminal 151 of the transmission circuit 15 can output a monitoring signal as an output node of the monitoring device 10. The thermal battery 20 only needs to be equipped with at least one thermoelectric element 21 (or 22), and is not limited to two. In other words, it is applicable even if the monitoring device 10 has two or more monitoring points.

[0060] The damage evaluation system 60 described above is an example where the evaluation device 300 is the same device as the receiving device 30, but the evaluation device 300 may be configured as a separate device from the receiving device 30.

[0061] The voltage detection circuit 13 may have a hysteresis function. The monitoring device 10 may also have a function to keep the switch 14 closed for a certain period of time (until communication ends) after the voltage detection circuit 13 detects that the voltage at node N1 exceeds the threshold voltage of the voltage detection circuit 13. The function to keep the switch 14 closed for a certain period of time may be provided by the voltage detection circuit 13, or by adding a circuit having such a function.

[0062] These embodiments and their variations are included within the scope and essence of the invention, as well as within the scope of the invention and its equivalents as described in the claims. [Explanation of Symbols]

[0063] 10 Monitoring equipment 11 Boost Circuit 12 Energy storage elements 13 Voltage detection circuit 14 switches 15. Transmitter Circuit 20 Thermal Cells 21,22 Thermoelectric elements 30 Receiving device 300 Evaluation device 301 Receiver 302 Control Unit 303 Evaluation Department 50 monitoring systems 60 Damage Assessment System

Claims

1. A monitoring device that uses a thermoelectric cell as a sensor, which is attached to the object being monitored and has a thermoelectric element that outputs a voltage corresponding to the temperature difference between the temperature of the atmosphere surrounding the object being monitored and the temperature of the contact part that is in contact with the object being monitored, and monitors the object being monitored based on the voltage corresponding to the temperature difference, A boost circuit including an input terminal that receives a voltage from the thermal cell and an output terminal that outputs a boosted voltage obtained by boosting the voltage input from the input terminal, A power storage element connected to the output terminal of the boost circuit, which stores power supplied from the thermal battery (which is the sensor) and boosted by the boost circuit, A voltage detection circuit that detects the boosted voltage and outputs a control signal from its output terminal that includes a signal level corresponding to whether the boosted voltage exceeds a predetermined voltage or not, A switch comprising a first terminal connected to the output terminal of the boost circuit and a second terminal, which opens and closes a path connecting the first terminal and the second terminal based on the control signal, A monitoring device characterized by being equipped with the following features.

2. The transmission circuit includes an input terminal connected to the second terminal of the switch, and when it receives a voltage from the same node as the output terminal of the boost circuit via the switch, it transmits a monitoring signal including identification information of the thermal battery. The monitoring device according to claim 1, wherein the predetermined voltage is set to be equal to or greater than the minimum voltage at which the transmission circuit can transmit the monitoring signal.

3. The monitoring device according to claim 2, wherein the transmission circuit is configured to wirelessly transmit the monitoring signal including identification information of the thermal battery.

4. The monitoring device according to claim 2, wherein the energy storage element has a capacity value capable of storing enough power for the transmitting circuit to transmit the monitoring signal once.

5. A monitoring system comprising a thermocell, which is attached to a target to be monitored and has a thermoelectric element that outputs a voltage corresponding to the temperature difference between the temperature of the atmosphere surrounding the target and the temperature of the contact area with the target, as a sensor, and transmitting a monitoring signal including identification information of the thermocell from a monitoring device that monitors the target based on the voltage corresponding to the temperature difference to a receiving device, A monitoring system characterized by comprising: a boost circuit including an input terminal that receives a voltage from the thermal battery and an output terminal that outputs a boosted voltage obtained by boosting the voltage input from the input terminal; a storage element connected to the output terminal of the boost circuit and storing power supplied from the thermal battery, which is the sensor, and boosted by the boost circuit; a voltage detection circuit that detects the boosted voltage and outputs a control signal from the output terminal including a signal level corresponding to when the boosted voltage exceeds a predetermined voltage and when it does not, respectively; and a transmission circuit connected to the output terminal of the boost circuit and the input terminal of the voltage detection circuit via a switch that is opened and closed based on the control signal.

6. A damage evaluation system comprising a thermocell, which is attached to a target to be monitored and has a thermoelectric element that outputs a voltage corresponding to the temperature difference between the temperature of the atmosphere surrounding the target and the temperature of the contact area with the target, as a sensor, and a monitoring device that monitors the target based on the voltage corresponding to the temperature difference, which transmits a monitoring signal including identification information of the thermocell to an evaluation device that evaluates the degree of damage to the target, A damage evaluation system characterized by comprising: a boost circuit including an input terminal for receiving a voltage from the thermal battery and an output terminal for outputting a boosted voltage obtained by boosting the voltage input from the input terminal; a storage element connected to the output terminal of the boost circuit for storing power supplied from the thermal battery, which is the sensor, and boosted by the boost circuit; a voltage detection circuit that detects the boosted voltage and outputs a control signal from the output terminal including a signal level corresponding to whether the boosted voltage exceeds a predetermined voltage or not; and a transmission circuit connected to the voltage detection circuit via a switch that is opened and closed based on the control signal, which transmits a monitoring signal including identification information of the thermal battery to an evaluation device that evaluates the degree of damage to the monitored object.

7. The evaluation device comprises the aforementioned evaluation device, A receiving unit that receives the monitoring signal transmitted from the transmission circuit, An evaluation unit estimates the voltage corresponding to the temperature difference based on the relationship between the time interval at which the receiving unit receives the monitoring signal and the voltage corresponding to the temperature difference, and evaluates the degree of damage to the monitored object. A control unit that controls the receiving unit and the evaluation unit, The damage evaluation system according to claim 6, characterized by comprising:

8. The aforementioned thermal cell is A first thermoelectric power generation element is attached to the first position of the object to be monitored, A second thermoelectric element is mounted at a second position that contacts the object being monitored at a position different from the first position, and is connected in series with the first thermoelectric element, A damage evaluation system according to claim 6 or claim 7, having the following features.

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