Sensor and detection method

Abstract

A normal state deviation detection sensor (1A) is formed by alternately connecting a string-shaped first material (2a1) and a string-shaped second material (3a1) at junctions, the second material having a Seebeck coefficient different from that of the first material. A hot region or a cold region of an object of interest spans across at least one of the junctions between the first material and the second material. The normal state deviation detection sensor detects that the condition of the object has deviated from a normal state on the basis of a voltage generated through thermoelectric conversion of heat or cold received or emitted by at least one portion of the object.

Description

Sensor and Detection Method

[0001] The present invention relates to a sensor and a detection method.

[0002] There are accidents, failures, disasters, etc. that originate from deviations from the normal state. For example, a fire caused by an increase in the internal temperature of stored sediments (biomass fuel, etc.) can be cited. Such accidents, failures, disasters, etc. may appear as changes in the temperature of the interior or surface, or both, of the object from the normal state. In that case, it becomes possible to detect deviations from the normal state in advance by measuring changes in the temperature of the interior or surface, or both, on a regular basis. As a temperature measurement sensor, there is, for example, a thermocouple.

[0003] However, the measurement location of the thermocouple is a point, and it can only detect deviations from the normal state at a specific point. Although it is possible to simulate a line by using a plurality of thermocouples for point measurement to measure a plurality of points, installation and disposal are difficult. On the other hand, there is thermography as a means of measuring temperature in a line or a plane, but the measurement target is limited to the surface temperature, and the internal temperature cannot be measured. Therefore, there is a need for a sensor that measures changes in the temperature of not only the surface of the object but also the interior in a line or a plane and detects deviations from the normal state.

[0004] Generally, global warming has brought various effects such as rising temperatures, rising sea levels, and frequent extreme weather phenomena. Therefore, it is urgent to build a system that reduces greenhouse gas emissions or promotes the use of renewable energy, or both. However, these systems have a short history, and management systems for stable maintenance or defense systems for early response to abnormalities are often immature.

[0005] Many of such management systems or defense systems mainly rely on visual inspection by surveillance cameras or thermal cameras, or both. There are also disadvantages at night or under a storm, and since it is only possible to recognize an abnormality after the situation has progressed to a degree that can be visually discriminated, the response may be delayed.

[0006] Patent Document 1 discloses a thermoelectric power generation module capable of achieving both heat insulation and power generation efficiency. The thermoelectric power generation module is 0.2 Wm－１ K －１ A thermoelectric power generation module is described which includes a thermoelectric material portion that is placed between a first main surface and a second main surface of an insulating member having the following thermal conductivity, and which generates an electromotive force corresponding to the temperature difference between the two main surfaces, and which has a thermoelectric power generation element configured to generate a current in a desired direction. Furthermore, Patent Document 1 discloses a thermoelectric conversion module with a configuration suitable for obtaining greater power from a constantly present heat source, such as by aligning the direction of the current within the element.

[0007] Japanese Patent Application Publication No. 2023-38800

[0008] The problem that this invention aims to solve is to prevent accidents, failures, and disasters, or minimize damage, by detecting the onset of accidents, failures, and disasters in artificial structures, sediments, or both, as early as possible. If artificial structures, sediments, or both maintain a stable state, that is, if their state remains unchanged over time, accidents, failures, and disasters are unlikely to occur due to intrinsic causes. Hereinafter, this state will be referred to as the stable state. However, if this stable state is disrupted by some factor, that is, if it deviates from the stable state, it can be considered almost equivalent to the onset of an accident, failure, or disaster.

[0009] The inventor then realized that the generation or change of heat or cold often mediated this deviation from the normal state. In other words, the inventor believed that by capturing the generation of heat or cold, and the significant change in temperature over time compared to the surrounding environment, it would be possible to detect a deviation from the normal state or a breakdown of the normal state. This detection would allow for the early detection of accidents, malfunctions, and disasters, and minimize damage.

[0010] As a primary example of an accident, spontaneous combustion of solid biomass fuel storage facilities is occasionally reported. This is thought to occur because the biomass fuel itself ferments and generates heat due to its own moisture content, ambient humidity, or temperature, and because the thermal conductivity of biomass is low, this heat does not dissipate, leading to heat accumulation and ignition. Currently, thermal cameras are used to monitor biomass fuel ignition, but if the fermentation occurs inside the stored biomass fuel, it is thought to be difficult to detect in the early stages, and by the time it is detected by a thermal camera, a fire may have already started.

[0011] In the context of biomass fuel storage sites, the conventional approach to detect and identify internal fermentation heat early on would theoretically involve the use of thermocouples, which are thermoelectric conversion elements. However, since thermocouples are solely for point measurement, hundreds of thermocouples would be needed in a vast storage site. Furthermore, because biomass fuel is transported from these sites according to power generation consumption, the thermocouples would need to be removed each time, making the thermocouple-based method impractical.

[0012] As a second specific example of an accident, flooding of road underpasses is occasionally reported during heavy rain disasters. In recent years, with the increasing frequency of heavy rain disasters, flooding of road underpasses at night, in particular, can lead to accidents involving loss of life. As an existing technology, some locations have systems that use electrode rods to gauge water levels and issue alarms or block traffic based on the detection results. The mechanism is that multiple electrode rods, installed at a distance from each other, are normally in an off state, but when rainwater comes into contact with these electrodes due to rising water levels caused by rainfall, they become electrically conductive and trigger an alarm. While such a system appears simple and easy to maintain, the electrode rods must be electrically conductive with rainwater, and malfunctions can occur due to deterioration of the electrode rod surface or the accumulation of dirt and mud. Furthermore, such electrode rods are valuable components, and theft is a concern when they are installed in underpasses in places that are difficult to monitor.

[0013] To solve the above problems, a sensor according to one aspect of the present invention is a string-shaped sensor formed by alternately connecting a string-shaped first material and a string-shaped second material having a different Seebeck coefficient from the first material at intersections, and detects that the state of the object deviates from its normal state based on a voltage generated by thermoelectric conversion of heat or cold received or emitted by at least one part of the object, where the heat or cold region of the object to be detected straddles at least one intersection of the first material and the second material.

[0014] To solve the above problems, a detection method according to one aspect of the present invention is a detection method using a string-shaped sensor formed by alternately connecting a string-shaped first material and a string-shaped second material having a different Seebeck coefficient from the first material at their intersections, wherein the thermal or cold region of the object to be detected straddles at least one of the intersections of the first material and the second material, and the sensor detects that the state of the object deviates from its normal state based on the voltage generated by thermoelectric conversion of heat or cold received or emitted by at least one part of the object.

[0015] According to the present invention, by measuring temperature changes not only on the surface of the object but also in a wide area inside, deviations from the normal state can be detected, enabling early detection of accidents, malfunctions, disasters, etc., and minimizing damage.

[0016] This figure schematically shows one embodiment of the normal state deviation detection sensor according to the present invention and the heating and cooling positions. The figure shows (1000) a schematic diagram of the positional relationship when the heating and cooling positions span two (even) connection points (boundaries) of the normal state deviation detection sensor, (1001) an experimental apparatus, and (1002) the relationship between the heating / cooling state and the electromotive force. The figure also shows (2000) a schematic diagram of the positional relationship when the heating and cooling positions span one (odd) connection point (boundary) of the normal state deviation detection sensor, (2001) an experimental apparatus, and (2002) the relationship between the heating / cooling state and the electromotive force. (3000) A schematic diagram of the positional relationship when the heating and cooling positions do not cross the connection part (boundary) of the normal deviation detection sensor, (3001) an experimental apparatus, and (3002) a diagram showing the relationship between the heating / cooling state and the electromotive force (comparative example). A diagram illustrating an example of a coaxial structure. A diagram illustrating an example of a case in which the normal deviation detection sensor according to the present invention is mounted on a predetermined base material. A diagram illustrating an example of a case in which the normal deviation detection sensor according to the present invention is mounted on a predetermined base material. A graph showing experimental results related to biomass fuel. A graph showing experimental results conducted in an environment simulating a fire occurring inside a building.

[0017] The embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the following embodiments, and modifications, alterations, and improvements may be made without departing from the scope of the invention.

[0018] In this embodiment, the notations "first" or "second," etc., are used to distinguish one component from another, and are not intended to limit the number, order, or priority of such components. For example, if there are descriptions of "first element" and "second element," it does not mean that only two elements, "first element" and "second element," will be adopted, nor does it mean that "first element" must precede "second element."

[0019] As shown in Figure 1, the normal deviation detection sensor 1A according to this embodiment is a string-shaped sensor formed by alternately connecting a string-shaped first material (shown by solid lines, 2a1, 2a2, 2a3, ...) and a string-shaped second material (shown by dashed lines, 3a1, 3a2, ...) which has a different Seebeck coefficient from the first material, at their intersections. The thermal or cold region of the object to be detected straddles at least one of the intersections between the first material 2a1, 2a2, 2a3, ... and the second material 3a1, 3a2, .... The normal deviation detection sensor 1A detects that the state of the object has deviated from its normal state based on the voltage generated by thermoelectric conversion of heat or cold received or emitted by at least one part of the object. With this configuration, accidents, malfunctions, disasters, etc. that originate from deviations from the normal state, which appear in temperature changes in a wide area not only on the surface but also inside the object, can be detected immediately after they occur. The details are explained below.

[0020] In the following, for the sake of explanation, the "normal deviation detection sensor 1A" may be simply referred to as "sensor 1A." Also, when it is not necessary to distinguish between the first materials 2a1, 2a2, 2a3, ... individually, they may be collectively referred to as "first material 2a1, etc." Also, when it is not necessary to distinguish between the second materials 3a1, 3a2, ... individually, they may be collectively referred to as "second material 3a1, etc."

[0021] Sensor 1A may also be defined as follows: Sensor 1A may be formed by alternately connecting a string-like first material 2a1 and a string-like second material 3a1 with different Seebeck coefficients at a pitch smaller than the length in the sensor installation direction of the expected thermal or cold region of the object to be detected. If sensor 1A is installed in a substantially straight line with respect to the object so that it is in contact with the object, the thermal or cold region will always be located across the string-like first material 2a1 and the string-like second material 3a1 with different Seebeck coefficients. Sensor 1A generates an electric current by thermoelectric conversion of thermal or cold. Both the string-like first material 2a1 and the string-like second material 3a1 function as string-like sensors. Consider a case where, at each intersection of the first material 2a1 and the second material 3a1, a first thermal region or a first cold region exists spanning one intersection, and a second thermal region or a second cold region exists spanning another intersection. Of course, the thermal or cold regions are not limited to two; there may be three or more. In such a case, sensor 1A generates an electric current at each intersection by thermoelectric conversion of the thermal or cold, but the direction of the generated current is not necessarily the same. If the generated currents are in the same direction, the sum of the currents is detected, while if the generated currents are in different directions, the difference between the currents is detected. In either case, when a thermal or cold region is generated, sensor 1A can detect the thermoelectrically converted current as an output, and based on this detection result, it can detect that the state of the object has deviated from its normal state.

[0022] Such a string-like sensor 1A can be applied to the biomass fuel storage facility described above. An example of an application method will be explained.

[0023] Multiple sensors 1A are installed in the biomass fuel storage area in the X direction, arranged as X1, X2, X3, ... By configuring the X plane in this way, the location of the heat source that causes the biomass fuel to spontaneously ignite or ferment can be identified as being on one of the lines X1, X2, X3, ... Also, multiple sensors 1A are installed in the biomass fuel storage area in the Y direction, arranged as Y1, Y2, Y3, ... without being connected to the aforementioned X1, X2, X3, ... By configuring the Y plane in this way, the location of the heat source that causes the biomass fuel to spontaneously ignite or ferment can be identified as being on one of the lines Y1, Y2, Y3, ... With this configuration, the location of the heat source that causes the biomass fuel to spontaneously ignite or ferment can be identified using X-Y coordinates.

[0024] Let's describe another application example. Sensor 1A may be installed on a 1X plane arranged in the X direction, a Y plane arranged in the Y direction with a certain height gap between sensors on the 1X plane, and a 2X plane arranged in the X direction with a certain height gap between sensors on the Y plane. Sensor 1A installed in this way will detect the heat generated when biomass fuel spontaneously ignites or ferments. If sensor 1A detects a deviation from the normal state on the 1X plane and the Y plane, heat generation between the 1X plane and the Y plane can be detected. Also, if sensor 1A detects a deviation from the normal state on the 2X plane and the Y plane, heat generation between the 2X plane and the Y plane can be detected. In other words, with this installation configuration of sensor 1A, the position in the Z direction can also be determined, enabling more accurate action.

[0025] Furthermore, while the X and Y planes are provided with a certain distance between them to enable detection in the Z direction, the X and Y planes may also be brought into contact without electrical conductivity, and the sensors 1A may be installed in a mesh-like pattern. This allows for the creation of a mesh-like pattern, which may be advantageous for the installation of the sensors 1A. Detection in the Z direction is achieved by stacking the mesh-like sensors 1A in the Z direction.

[0026] As explained above, the sensor 1A may be placed in close proximity to the solid fuel (for example, the biomass fuel mentioned above) by burying it in a linear or mesh pattern in a facility that stores solid fuel. The sensor 1A detects when the condition of the solid fuel deviates from its normal state based on the voltage generated by converting the heat emitted by the solid fuel into thermoelectric voltage.

[0027] As another example, the string-like sensor 1A can also be applied to the underpass mentioned above.

[0028] Sensor 1A is manufactured by connecting string-like first material 2a1 and string-like second material 3a1, etc., which have different Seebeck coefficients, at intervals shorter than the flood depth of the underpass that triggers the alarm. Sensor 1A is installed by attaching it vertically to the wall of the civil engineering structure of the underpass. Assume that rainwater flows into the underpass and does not discharge outside the system, causing flooding to progress until it reaches the flood depth of the underpass that triggers the alarm. As the water level rises across the string-like first material 2a1 and string-like second material 3a1, etc., which have different Seebeck coefficients, sensor 1A performs thermoelectric conversion due to the temperature difference between the water temperature and the wall surface of the civil engineering structure, thereby generating a current signal. This current signal allows the underpass system to issue an alarm.

[0029] Sensor 1A uses less expensive components compared to existing electrode rod systems, making it less valuable for resale and reducing the risk of theft. Furthermore, because Sensor 1A has a simpler structure than existing electrode rod systems, it can be used not only for underpasses but also for warning of flooded roads in low-lying areas, contributing to comprehensive monitoring of the area. By installing a comprehensive monitoring system, for example, at a local government security headquarters, it becomes possible to identify areas at risk of road flooding due to abnormal rainfall at night at a glance, thus preventing accidents such as secondary damage to patrol cars dispatched to rescue operations.

[0030] As explained above, the sensor 1A may be installed vertically or at a predetermined angle relative to the vertical within a structure in a location where submersion is anticipated. The sensor 1A detects submersion based on the voltage generated by thermoelectric conversion of the temperature difference between the water temperature of the target object and the temperature of the structure. The "predetermined angle" here is not particularly limited, but may be set to, for example, "a range of -5° to +5°" or "a range of -15° to +15°".

[0031] (Example) As the material and manufacturing method for the sensor 1A body according to this embodiment, the material and manufacturing method described in "Japanese Patent Publication No. 2023-38800," previously filed by the present inventor, can be applied.

[0032] (Example of a method for manufacturing sensor 1A) For example, the first material 2a1 can be manufactured by immersing fibers in a coating of a p-type thermoelectric material such as PEDOT:PSS and drying it. As the first material 2a1, cotton yarn was dyed with a conductive polymer (PEDOT:PSS aqueous dispersion "Organon® ICP-1050") and the pitch was made smaller than the size of the hot plate used (5 cm). Nickel wire was tied together as the second material 3a1 to prepare a string-shaped sensor. In this case, the Seebeck coefficient of the conductive polymer is larger than that of the nickel wire. As a heat source, a hot plate was used for temperatures of 30°C to 100°C, and a cooling plate was used for temperatures of 5°C to 20°C.

[0033] The case where the heating / cooling position (region) H / LA straddles two (even number) connection points (boundaries) of sensor 1A (where the heating / cooling position is defined as two intersection points) is shown in state 1000 of Figure 2. In state 1000 of Figure 2, "4a1" indicates the intersection point of the first material 2a1 and the second material 3a1. "4a2" indicates the intersection point of the first material 2a2 and the second material 3a1. "4a3" indicates the intersection point of the first material 2a2 and the second material 3a2. "4a4" indicates the intersection point of the first material 2a3 and the second material 3a2.

[0034] The electromotive force due to the Seebeck effect in state 1000 of Figure 2 was measured using the experimental apparatus shown in experimental setup 1001 of Figure 2. As shown in experimental setup 1001 of Figure 2, the heating / cooling position (region) H / LA straddles two connection points of the sensor 1A. These two points are "4a2" and "4a3". The first material (2a1, 2a2, 2a3, 2a4) and the second material (3a0, 3a1, 3a2, 3a3, 3a4) are alternately connected (coupled) at a pitch smaller than the installation direction length L of the heating / cooling position (region) H / LA. The first material (3a0, 3a4) at both ends of the sensor 1A were connected to a voltmeter via tweezers 52. Each component of the experimental apparatus was placed on a rubber sheet 51, which is an insulator. The heating / cooling location (region) H / LA indicates the heat source. As mentioned above, a hot plate was used for heating to a temperature of 30°C to 100°C, and a cooling plate was used for cooling to a temperature of 5°C to 20°C.

[0035] Let's explain the experimental results. As shown in experimental result 1002 in Figure 2, the generated voltage showed a fine sawtooth waveform. It can be seen that voltage is generated in the range from slightly less than 10°C to slightly more than 60°C. Voltage generation was confirmed even at a water temperature of slightly less than 10°C due to the difference in ambient temperature, demonstrating its function as a water level gauge.

[0036] The case where the heating / cooling position (region) H / LA crosses one (odd number) of the connection points (boundaries) of sensor 1A (with the intersection of the heating / cooling positions being considered as one point) is shown in state 2000 of Figure 3. The electromotive force due to the Seebeck effect in state 2000 of Figure 3 was measured using the experimental apparatus shown in experimental setup 2001 of Figure 3. As shown in experimental setup 2001 of Figure 3, the heating / cooling position (region) H / LA crosses one of the connection points of sensor 1A. This one point is "4a2" shown in state 2000 of Figure 3, although it is not shown in experimental setup 2001 of Figure 3. The first material (2a1, 2a2, 2a3, 2a4) and the second material (3a0, 3a1, 3a2, 3a3, 3a4) are alternately connected (joined) at a pitch smaller than the installation length L of the heating / cooling position. The first materials (3a0, 3a4) at both ends of sensor 1A were each connected to a voltmeter via tweezers 52. The components of the experimental apparatus were placed on a rubber sheet 51, which acts as an insulator.

[0037] Let's explain the experimental results. As shown in experimental result 2002 in Figure 3, the generated voltage showed a fine sawtooth waveform. It can be seen that voltage was generated in the range from 15°C to just under 70°C. Compared with experimental result 1002 in Figure 2, it can be seen that the voltage generation range in experimental result 2002 in Figure 3 is larger. This difference is thought to be because, since there is only one intersection point, the direction of the generated current is uniform and not attenuated, so almost all of the generated voltage could be detected.

[0038] (Comparative Example) As a comparative example, the case where the heating / cooling position (region) H / LA does not straddle the connection part (boundary) of sensor 1A (the state in which the heating / cooling position is set to intersection zero) is shown in state 3000 of Figure 4. In this case, as shown in experimental setup 3001 of Figure 4, the entire heating / cooling position (region) H / LA was installed in an almost straight line on the first material 2a1. The electromotive force due to the Seebeck effect was measured using the experimental apparatus shown in experimental setup 3001 of Figure 4. Both ends of the first material 2a1 were connected to a voltmeter via tweezers 52. Each component of the experimental apparatus was placed on a rubber sheet 51, which is an insulator.

[0039] Let me explain the experimental results. As shown in experimental result 3002 in Figure 4, the absence of an intersection (i.e., zero intersections) means that there are heating and cooling points in one of the materials. Here, a hot plate was applied to cotton yarn dyed with a conductive polymer, and the same temperature as in Figures 2 and 3 was applied, but no significant voltage output was found.

[0040] As described above, sensor 1A, formed by alternately connecting cotton yarn dyed with conductive polymers having different Seebeck coefficients and nickel wire, at a pitch smaller than the length in the direction of installation of the hot plate, is installed almost linearly on the hot plate. The experimental results show that sensor 1A was able to detect the heat and cold emitted by the hot plate by converting them into thermoelectric heat. Furthermore, it can be seen that sensor 1A was able to detect heating and cooling with high responsiveness.

[0041] (Other Embodiment Examples) The object to be observed by the sensor 1A, that is, the application (embodiment example) to which it is applied, is not limited to the above-mentioned biomass fuel and submersion. As other examples, the sensor 1A can be applied to a fire alarm, discovery and monitoring of lightning strike damage points on the blades of a wind turbine, early defect discovery before a river levee penetrates and collapses, monitoring of sudden rainwater inflow into the ground on a slope or a hillside, discovery of hot spots on a solar panel, or multi-point monitoring, etc. Each application (embodiment example) will be described below.

[0042] (Fire Alarm) In Aichi Prefecture, Japan, in multi-family housing such as apartments or condominiums, it is obligatory to install a residential fire alarm in every bedroom. Also, there is an obligation to regularly inspect (overall inspection once a year, equipment inspection once every six months) the installed equipment, etc. and report the results to the fire chief or the fire station chief. Regarding the penalty for violation of the obligation, a fine of up to 300,000 yen or a penalty of detention may be imposed based on Article 44 of the Fire Service Act. Similar measures are taken in many other local governments. However, due to the increasing concern for privacy protection and the diversification of individual living situations, it is extremely difficult to conduct an inspection by entering each room, and a situation has occurred where the reporting obligation has not been fully fulfilled.

[0043] Since the sensor 1A according to this embodiment can detect radiant heat, it can start measurement from the time when heat is generated, that is, it can monitor from the very beginning of the heat generation of the heat source. Specifically, the sensor 1A is installed in a way that it crawls on the ceiling of each room in a rental apartment, and a part of it is also extended to the common area outside the room and connected to the fire alarm main body installed outside the room. With such a configuration, a new type of fire alarm can be provided. As described above, the sensor 1A has a simple structure, little deterioration over time, and does not require replacement of a battery or the like, so the inspection load is almost non-existent.

[0044] Furthermore, since sensor 1A can continuously measure changes in radiant heat, it can significantly distinguish between, for example, radiant heat caused by a stove and radiant heat caused by a fire resulting from carelessly discarded cigarettes. That is, while the heat output of a stove is large, the radiant heat does not rise beyond a certain point, whereas in the case of a fire caused by carelessly discarded cigarettes, although the heat output itself is smaller compared to a stove, the radiant heat continues to rise. By applying this difference, it becomes possible to distinguish between radiant heat caused by a stove and radiant heat caused by a fire resulting from carelessly discarded cigarettes, not only based on the magnitude of the absolute heat output.

[0045] In addition, by bringing a heat source close to the extended sensor 1A in the common area and checking for the presence or absence of generated voltage, it is possible to confirm that the sensor 1A installed on the ceiling inside the room is not broken. Since the fire alarm is also located outside, the fire alarm system can be inspected without entering each room in principle. Furthermore, current fire alarms are required in each room, and current laws mandate their installation in bedrooms. Since sensor 1A can be installed in a continuous line around each room, there is no need to increase the number of sensors according to the number of rooms as with current fire alarms. It is sufficient to extend the length of the string-like sensor 1A according to the number of rooms, making it highly cost-effective.

[0046] As explained above, the sensor 1A may be installed at a predetermined height or higher within the building. The sensor 1A detects when the condition of a heat source deviates from its normal state based on the voltage generated by thermoelectric conversion of the heat emitted by the heat source, which is the object being tested. When using the sensor 1A as a fire alarm, the location where the sensor 1A is installed is not limited to the ceiling. That is, as mentioned above, the location where the sensor 1A is installed is "at a predetermined height or higher within the building," and the sensor 1A may be installed on a wall, column, beam, etc., in addition to the ceiling.

[0047] (Discovery and Monitoring of Lightning Strike Damage Points on Wind Turbine Blades) Regarding lightning strike damage to the blades of a wind turbine, if the turbine is operated with the damage left as it is, the damage will spread throughout the blade and cause significant damage. Therefore, it is necessary to stop the rotation of the blade and shut down the generator almost simultaneously with the lightning strike to prevent additional stress from being applied. To improve the operation rate, quickly detecting damage is an urgent issue.

[0048] Currently, as a method for detecting lightning strikes on the blade, a system that detects lightning strikes by winding a Rogowski coil around the tower base and detecting the lightning current flowing through the tower base is the mainstream. However, with this method, there are cases where electromagnetic noise generated at the tower base is misdetected as a lightning current, and improvements are being made. Also, the combined use of visual inspection (including drones, etc.) is a major means, but such operation becomes difficult under a storm. As described above, as a measure against global warming, in the future, as the investment target shifts to offshore wind power facilities, lightning strike detection has become a major problem.

[0049] Therefore, by attaching and installing a mesh-shaped sensor 1A on the surface of the blade, it is possible to identify the fact that there has been lightning strike damage and the location of the lightning strike. This makes it easier to stop the rotation of the wind turbine and quickly repair the lightning strike damaged area. Here, although the mode of installing the sensor 1A on the surface (pressure surface) of the blade has been described, it is not limited to this. The sensor 1A may be installed on the back surface (negative pressure surface) of the blade.

[0050] As described above, by installing the sensor 1A in a mesh shape on at least one of the pressure surface or the negative pressure surface of the blade of the wind turbine, it may be in a state of contacting the target blade. The sensor 1A detects that the condition of the blade has deviated from the normal state based on the voltage generated by thermoelectric conversion of the temperature difference caused by the temperature change generated by a lightning strike on the blade.

[0051] (Early Defect Detection Before River Embankment Seepage Failure) In the management of river embankments, damage caused by burrows of moles, foxes, etc. or digging by wild boars, etc. on the slope, etc. (hereinafter referred to as "burrow damage by small animals, etc.") has occurred, and there is a problem that it may lead to the decline of embankment vegetation and the weakening of the embankment.

[0052] When constructing river embankment slopes, by installing the sensor 1A according to this embodiment vertically and horizontally with a mesh size similar to the diameter of small animal burrows, it is possible to detect the presence and location of burrows by detecting the hollowing out of the burrow or temperature changes due to airflow, etc., when the burrow is formed. Currently, periodic visual inspection is the only method of detection, but the method using sensor 1A significantly improves the accuracy of identification, and at the same time, allows for early countermeasures to be taken, thereby preventing embankment collapse.

[0053] As explained above, the sensor 1A may be installed in a mesh pattern on the slope of the river embankment so that it is in contact with the river embankment, which is the target object. The sensor 1A detects when the condition of the river embankment deviates from the normal state based on the voltage generated by thermoelectric conversion of the temperature difference caused by temperature changes resulting from the formation of burrows or digging by small animals on the slope of the river embankment.

[0054] (Monitoring of rapid rainwater inflow into the ground on slopes and inclines) As another example aimed at early detection of defects before seepage failure occurs in river embankment slopes, the sensor 1A according to this embodiment may be installed by burying it during the construction of the river embankment slope as described above. Alternatively, the sensor 1A may be installed so as to be thrust into the slope of an existing slope or incline. This allows the inflow of rainwater into the constituent ground of the slope to be observed as a temperature change, and the observation results can be used to predict slope collapse.

[0055] As an example of how to install the sensor 1A on a slope, the following method can be used. For example, first, a pipe can be driven into the slope. Once the hole is complete, the sensor 1A can be lowered into the pipe, and once it is positioned at the target location, the pipe can be pulled out to install the sensor 1A.

[0056] As explained above, the sensor 1A may be installed in a direction that penetrates the slope of the river embankment. The sensor 1A detects when the condition of the river embankment, which is the target object, deviates from its normal state based on the voltage generated by thermoelectric conversion of the temperature difference caused by the temperature change resulting from the influence of rainwater flowing in from the slope into the interior.

[0057] (Discovery of hot spots on solar panels) If any of the cells in a solar panel are shaded by debris, fallen leaves, etc., the power generation of that cell will decrease, and resistance will be created in the circuit of the entire panel, generating heat. This heat leads to cell degradation, so power generation must be stopped and the debris removed. The current approach is to treat the decrease in power generation as an abnormality and take action accordingly. However, since heat generation has already occurred by the time the power generation decreases, this can only be described as a reactive measure.

[0058] By installing the sensor 1A according to this embodiment along each cell of the solar panel, it is possible to detect a situation where a shadow is created due to the accumulation of dust or other debris, causing the shadowed area to become colder than the surrounding area, and to issue an alarm as soon as possible. Furthermore, if the situation progresses and resistance heat is generated in the cell, it is possible to detect this and issue a higher-level alarm.

[0059] As explained above, the sensor 1A may be placed in contact with each cell that makes up the solar panel. The sensor 1A detects when the condition of a cell deviates from its normal state based on the voltage generated by thermoelectric conversion of the temperature difference caused by a temperature change in at least one cell.

[0060] (Multi-point monitoring) An example of multi-point monitoring using sensor 1A according to this embodiment is monitoring of overhead line hangers. Overhead line hangers are installed in countless numbers along railway lines, and occasionally the chain reaction of failure of these hangers causes railway disruptions, which makes headlines.

[0061] By attaching sensor 1A in series to each of these overhead line hangers, it is possible to detect heat generation caused by plastic deformation in any of the hangers and alert that plastic deformation has occurred in one of the sections connected in series, making it highly likely that fracture will occur next.

[0062] As explained above, the sensor 1A may be installed in series with each overhead line hanger so that it is in contact with the overhead line hanger, which is the object of the test. The sensor 1A detects when the condition of the overhead line hanger deviates from the normal state based on the voltage generated by converting the heat produced by the plastic deformation of the overhead line hanger into thermoelectric voltage.

[0063] As described above, the sensor 1A according to this embodiment is a thermoelectric power generation module on its own, and by properly calibrating it, it can also measure the absolute value of the temperature of an object.

[0064] A key feature of the sensor 1A according to this embodiment is that its sensing portion is a one-dimensional "line," unlike the zero-dimensional "point" of a typical thermocouple. Therefore, when measuring temperature changes over a certain length, a typical thermocouple requires a large number of "points" connected together. In contrast, the sensor 1A only requires a single string-like sensor. Furthermore, since the sensor 1A is one-dimensional, it can measure two dimensions by arranging them orthogonally.

[0065] While thermal cameras are commonly used for measuring the temperature of two-dimensional objects, they are limited to observing the surface and making it difficult to measure internal temperatures. In contrast, the sensor 1A according to this embodiment can be easily embedded and therefore can measure internal temperatures. By stacking two dimensions, it can be adapted to three dimensions. By utilizing these features, a wide variety of configurations are possible.

[0066] As another example, the sensor 1A may be configured as a coaxial structure. For example, as shown in Figure 5, the sensor 1A (first material and second material) may be covered with a first insulating layer 60. The first insulating layer 60 may be covered with a conductive material layer 61. The conductive material layer 61 may be covered with a second insulating layer 62. The conductive material layer 61 is not particularly limited, but may be composed of, for example, a metal layer, a conductive polymer, a carbon material, or a composite material containing these. By configuring the sensor 1A as a coaxial structure in this way, electrical noise can be significantly reduced.

[0067] As another example, considering handling, installation efficiency, mechanical durability, etc., the sensor 1A may be implemented in a form mounted on a predetermined base material. For example, as shown in Figure 6, a strong string-like sensor can be realized by using a strong string 70 as the base material and mounting the sensor 1A on the said base material. As yet another example, as shown in Figure 6, a sheet-like sensor can be realized by mounting the sensor 1A on a lightweight, bendable base material such as a cloth 80 having a predetermined strength. Such a sheet-like sensor can be installed simply by rolling it, thus improving installation efficiency.

[0068] Thus, the sensor 1A may be formed integrally with a predetermined base material. The shape of the predetermined base material may be sheet-like. In Figure 6, a configuration in which each of the sensors 1A is formed integrally with a sheet-like base material without being electrically connected is described, but the invention is not limited to this. For example, as shown in Figure 7, each of the sensors 1A may be formed integrally with a sheet-like base material while being electrically connected in series. In this series connection, the member used to electrically connect each of the sensors 1A is not particularly limited, but may be the first material, the second material, or both.

[0069] As another example, as shown in Figure 7, each of the sensors 1A may be integrally formed with a sheet-like base material while being electrically connected in series and parallel combinations. In this series-parallel connection, the components arranged horizontally in the drawing are exemplified as "sensors 1A," but are not limited to this. The components arranged horizontally in the drawing can be any components that can electrically connect the "sensors 1A arranged vertically in the drawing" to each other in series and parallel combinations.

[0070] (Experimental Results) Figure 8 is a graph showing the experimental results related to the biomass fuel described above. The experimental procedure is as follows: A predetermined amount of biomass fuel was sealed in a sample bag, and the sensor 1A according to this embodiment was placed inside the biomass fuel. Next, the biomass fuel was heated by a heat source (heater) placed on the bottom side of the sample bag. The distance between the heat source and the sensor 1A was set to two patterns, 2 cm and 10 cm, and the output voltage of the sensor 1A was measured in each pattern. The temperature of the heat source was measured by bringing a thermocouple into contact with the surface of the heat source. The temperature of the heat source was changed over time, and the responsiveness of the output voltage of the sensor 1A was evaluated.

[0071] In the graph shown in Figure 8, the horizontal axis represents time (min), the left side of the vertical axis represents the output voltage of sensor 1A (mV), and the right side of the vertical axis represents the temperature of the heat source (°C). As shown in Figure 8, when the distance between the heat source and sensor 1A was 2 cm, a response delay of approximately 0.2 to 0.6 minutes was observed in response to the temperature change of the heat source. On the other hand, when the distance between the heat source and sensor 1A was 10 cm, a response delay of approximately 2.5 to 2.9 minutes was observed.

[0072] This result is due to the low thermal conductivity of biomass fuel, indicating that the closer the distance from the heat source to the temperature measurement point, the earlier the fire can be detected. Since the sensor 1A according to this embodiment can be installed inside the biomass fuel, it has an advantage in early fire detection compared to a thermal camera that measures surface temperature.

[0073] Figure 9 is a graph showing the results of an experiment conducted under conditions simulating a fire inside a building. This experiment was conducted with the assumption that sensor 1A would be used as a fire alarm. The experimental procedure is as follows: A 1m long sensor 1A was installed along the surface of a rock wool ceiling material. Because rock wool has thermal insulation and non-combustible properties, it is suitable for evaluating the performance of sensor 1A even in a fire environment.

[0074] An electric heater was used as the heat source, and it was positioned perpendicular to the ceiling material at intervals. Specifically, the electric heater was placed at 30 cm, 120 cm, and 240 cm from the ceiling material, and the response of sensor 1A was measured at each distance. The electric heater operated as a heat source simulating a fire flame. The electric heater was switched on and off, and the change in the output voltage of sensor 1A during this switching was measured. In addition, to determine the temperature near sensor 1A, a thermocouple was placed near sensor 1A, and its temperature was recorded as the temperature near sensor 1A.

[0075] In the graph shown in Figure 9, the horizontal axis represents time (min), the left side of the vertical axis represents the output voltage of sensor 1A (mV), and the right side of the vertical axis represents the temperature near sensor 1A (°C). As is clear from the experimental results shown in Figure 9, the response of the output voltage of sensor 1A and the temperature near it decreases as the distance from the electric heater increases. However, even when the sensor was 240 cm away from the ceiling material (i.e., a distance equivalent to the distance between the floor and ceiling in a typical house), a clear output fluctuation corresponding to the on / off state of the electric heater was observed. This result indicates that sensor 1A according to this embodiment has sufficient sensitivity to function as a fire alarm mounted on a ceiling, wall, column, or beam.

[0076] An example of each combination of "heat or cold received or emitted by at least one part of the object" will be explained. An example of "heat received by at least one part of the object" is the heat (heat) received by the blades of the wind turbine when lightning strikes them, as described above. An example of "cold received by at least one part of the object" is the heat (cold) received by the river embankment when rainwater flows into it, as described above. An example of "heat emitted by at least one part of the object" is the heat (heat) emitted when the biomass fuel mentioned above ignites. An example of "cold emitted by at least one part of the object" is the heat (cold) emitted by the object, "water," when the underpass mentioned above is submerged in water.

[0077] According to the sensor 1A of this embodiment, accidents, malfunctions, disasters, etc. that originate from deviations from the normal state, manifested not only in temperature changes over a wide area inside the target surface, can be detected immediately after they occur. Specific examples of targets for detection include, as mentioned above, accidents such as fires caused by spontaneous combustion in biomass fuel storage facilities or house fires. Malfunctions such as lightning damage to wind turbine blades, fracture due to plastic deformation of railway overhead line hangers, or reduced power generation due to hot spots in solar panels. Disasters such as flooding of underpasses due to heavy rain, floods due to seepage failure of river embankments, or landslides due to rapid inflow of rainwater into the ground (slopes, embankments).

[0078] 1A: Normal deviation detection sensor (string-shaped sensor) 2a1, 2a2, 2a3, 2a4: First material 3a0, 3a1, 3a2, 3a3, 3a4: Second material 51: Rubber sheet 52: Tweezers 60: First insulating layer 61: Conductive material layer 62: Second insulating layer 70: String 80: Cloth H / LA: Heating / cooling position (area) L: Installation direction length of heating / cooling position

Claims

1. A string-shaped sensor formed by alternately connecting a string-shaped first material and a string-shaped second material having a different Seebeck coefficient from the first material at intersections, wherein the thermal or cold region of the object to be detected straddles at least one of the intersections of the first material and the second material, and the sensor detects that the state of the object deviates from its normal state based on the voltage generated by thermoelectric conversion of the heat or cold received or emitted by at least one part of the object.

2. The sensor according to claim 1, wherein the first material and the second material are covered with a first insulating layer, the first insulating layer is covered with a conductive material layer, and the conductive material layer is covered with a second insulating layer.

3. The sensor according to claim 1 or 2, wherein the first material and the second material are integrally formed with a predetermined base material.

4. The shape of the predetermined base material is sheet-like, and each of the sensors formed by the first material and the second material is formed in any of the following manner (1) to (3): (1) integrally formed with the base material in an electrically disconnected state, (2) integrally formed with the base material in an electrically connected series state, or (3) integrally formed with the base material in an electrically connected series and parallel combination state, as described in claim 3.

5. A detection method using a string-shaped sensor formed by alternately connecting a string-shaped first material and a string-shaped second material having a different Seebeck coefficient from the first material at their intersections, wherein the thermal or cold region of the object to be detected straddles at least one of the intersections of the first material and the second material, and the sensor detects that the state of the object deviates from its normal state based on a voltage generated by thermoelectric conversion of heat or cold received or emitted by at least one part of the object.

6. The detection method according to claim 5, wherein the sensor is embedded in a linear or mesh pattern in a facility for storing solid fuel, thereby bringing it into close proximity to the target object, the solid fuel, and the sensor detects that the condition of the solid fuel deviates from its normal state based on the voltage generated by thermoelectric conversion of the heat emitted by the solid fuel.

7. The detection method according to claim 5, wherein the sensor is installed in a structure in a location where submersion is expected to occur, either vertically or at a predetermined angle to the vertical direction, and the sensor detects submersion based on a voltage generated by thermoelectric conversion of the temperature difference between the water temperature of the target object and the temperature of the structure.

8. The detection method according to claim 5, wherein the sensor is installed at a predetermined height or higher inside the building, and the sensor detects that the condition of the heat source deviates from the normal state based on the voltage generated by thermoelectric conversion of the heat emitted by the heat source, which is the object in question.

9. The detection method according to claim 5, wherein the sensor is installed in a mesh pattern on at least one of the pressure surface or negative pressure surface of the blade of a wind turbine generator so as to be in contact with the blade, which is the object to be detected, and the sensor detects that the condition of the blade deviates from the normal state based on the voltage generated by thermoelectric conversion of the temperature difference caused by the temperature change resulting from a lightning strike on the blade.

10. The detection method according to claim 5, wherein the sensors are installed in a mesh pattern on the slope of the river embankment so as to be in contact with the target object, the river embankment, and the sensors detect that the condition of the river embankment deviates from the normal state based on a voltage generated by thermoelectric conversion of the temperature difference caused by temperature changes resulting from the formation of burrows or digging on the slope of the river embankment by small animals.

11. The detection method according to claim 5, wherein the sensor is installed in a direction that penetrates the slope of the river embankment, and the sensor detects that the condition of the target object, the river embankment, deviates from its normal state based on a voltage generated by thermoelectric conversion of the temperature difference caused by the temperature change resulting from the influence of rainwater flowing into the interior from the slope.

12. The detection method according to claim 5, wherein the sensor is installed in each cell constituting the solar panel so as to be in contact with each of the cells which are the target object, and the sensor detects that the condition of the cell in question has deviated from the normal state based on the voltage generated by thermoelectric conversion of the temperature difference caused by a temperature change occurring in at least one cell.

13. The detection method according to claim 5, wherein the sensors are installed in series with each overhead line hanger so as to be in contact with the overhead line hanger, which is the object of the detection, and the sensors detect that the condition of the overhead line hanger deviates from the normal state based on the voltage generated by thermoelectric conversion of the heat generated by the plastic deformation of the overhead line hanger.

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