Detection system

Abstract

A detection system 1 comprises a thermoelectric conversion element 2 that generates an electromotive force by a temperature difference, and a processing device 6. The processing device 6 executes a reference value acquisition step (S1) for acquiring a reference value of the electromotive force generated in the thermoelectric conversion element 2, and a calculation step (S3) for calculating the ratio Rn of the measured value of the electromotive force generated in the thermoelectric conversion element 2 to the acquired reference value.

Description

Detection system

[0001] The present invention relates to a detection system.

[0002] Conventionally, a sensor module including a thermoelectric conversion member that generates an electromotive force due to a temperature difference, a conversion circuit that converts the electromotive force of the thermoelectric conversion member into a signal, and a control device that can record the signal converted by the conversion circuit is known (see Patent Document 1 below).

[0003] International Publication No. 2023 / 127590

[0004] When attempting to detect a temperature change of an object using a sensor module as described in Patent Document 1, it is considered to monitor the measured value of the electromotive force of the thermoelectric conversion member.

[0005] However, the electromotive force of the thermoelectric conversion member may vary, for example, due to non-uniformity in the quality of the thermoelectric conversion member and non-uniformity in the distance between the object and the thermoelectric conversion member. Therefore, for example, when the attachment state of the sensor module to the object changes, the measured value of the electromotive force of the thermoelectric conversion member changes, and it may become difficult to accurately detect the temperature change of the object.

[0006] The present invention provides a detection system capable of accurately detecting a temperature change of an object.

[0007] The present invention [1] includes a thermoelectric conversion element that generates an electromotive force due to a temperature difference and a processing device, and the processing device executes a reference value acquisition step of acquiring a reference value of the electromotive force generated in the thermoelectric conversion element and a calculation step of calculating a ratio of the measured value of the electromotive force generated in the thermoelectric conversion element to the acquired reference value.

[0008] According to such a configuration, by calculating the ratio of the measured value to the reference value, the degree of change in the electromotive force can be surely detected.

[0009] As a result, a temperature change of an object can be accurately detected.

[0010] The present invention [2] includes the detection system of [1], wherein the processing device further performs a determination step of determining whether the ratio of the measured value to the reference value is less than a threshold.

[0011] With this configuration, if the processing unit determines that the ratio of the measured value to the reference value is smaller than the threshold, it can be inferred that a temperature change (specifically, a decrease in the temperature difference) is occurring in the target that causes a decrease in the electromotive force of the thermoelectric conversion element.

[0012] The present invention [3] includes the detection system of [1] or [2] above, wherein the detection system comprises a plurality of thermoelectric conversion elements, and in the calculation step, for each of the plurality of thermoelectric conversion elements, the ratio of the measured value to the reference value is calculated based on the same reference value.

[0013] With this configuration, temperature changes at the locations where each of the multiple thermoelectric conversion elements is located can be accurately detected based on the same reference value.

[0014] The present invention [4] includes one of the detection systems described in [1] to [3] above, wherein the thermoelectric conversion element comprises an insulating material having a predetermined thickness and a thermoelectric conversion member that is thread-like, disposed inside the insulating material, has a predetermined length in the thickness direction of the insulating material, and generates an electromotive force in the thickness direction of the insulating material due to a temperature difference.

[0015] This configuration comprises an insulating material having a predetermined thickness and a thermoelectric conversion member. The thermoelectric conversion member is thread-like and has a portion that is placed inside the insulating material. The portion placed inside the insulating material has a predetermined length in the thickness direction.

[0016] Therefore, thermoelectric conversion components can generate electromotive force by utilizing the temperature difference in the thickness direction of the insulating material.

[0017] The present invention [5] includes any one of the above [1] to [4] detection systems, wherein the detection system further comprises a conversion circuit that converts the electromotive force generated in the thermoelectric conversion element into an electrical signal, a transmitting module that transmits the electrical signal converted by the conversion circuit, and a receiving module that receives the electrical signal transmitted by the transmitting module, and the processing device performs the calculation step based on the electrical signal received by the receiving module.

[0018] With this configuration, the electromotive force of the thermoelectric conversion element can be converted into a signal by the conversion circuit and transmitted to the processing unit via the transmitting module and the receiving module.

[0019] According to the detection system of the present invention, temperature changes of the target can be accurately detected.

[0020] Figure 1 shows a block diagram of a detection system as one embodiment of the present invention. Figure 2 shows a pipe insulation structure as an example of an application of the detection system shown in Figure 1. Figure 3 is a perspective view of the insulation material shown in Figure 2. Figure 4 is a cross-sectional view taken along line A-A of the insulation material shown in Figure 3. Figure 5 is a flowchart of the detection process performed by the processing device shown in Figure 1. Figure 6 is a perspective view showing a first modified example of the thermoelectric conversion element. Figure 7 is a cross-sectional view showing a second modified example of the thermoelectric conversion element. Figure 8 is a cross-sectional view showing a third modified example of the thermoelectric conversion element. Figure 9 is a cross-sectional view showing a fourth modified example of the thermoelectric conversion element.

[0021] 1. Detection System As shown in Figure 1, the detection system 1 comprises a thermoelectric conversion element 2, a conversion circuit 3, a transmitting module 4, a receiving module 5, and a processing unit 6. The detection system 1 detects temperature changes of an object. The object is not limited. As shown in Figure 2, an example of an object is the insulation material 100 of a pipe P. The insulation material 100 covers the pipe P. The insulation material 100 may be covered by a metal exterior member C. As shown in Figure 3, the insulation material 100 has, for example, a cylindrical shape.

[0022] (1) Thermoelectric Conversion Elements In this embodiment, the detection system 1 includes a plurality of thermoelectric conversion elements 2A, 2B, and 2C. The thermoelectric conversion elements 2A, 2B, and 2C are independent of each other. The thermoelectric conversion elements 2A, 2B, and 2C are arranged at intervals from each other. The thermoelectric conversion elements 2A, 2B, and 2C are arranged, for example, in the direction in which the pipe P extends. Each of the thermoelectric conversion elements 2A, 2B, and 2C utilizes a portion of the insulation material 100 of the pipe P.

[0023] More specifically, as shown in Figure 4, the thermoelectric conversion element 2A includes a thermal insulation material 100 as an example of an insulating material, and a thermoelectric conversion member 21. In other words, the thermoelectric conversion element 2A utilizes a portion of the thermal insulation material 100 of the piping P as an insulating material.

[0024] (1-1) Insulation material The insulation material 100 has a predetermined thickness. The insulation material 100 has one surface S1 and the other surface S2 in the thickness direction of the insulation material 100. In the following description, the thickness direction of the insulation material 100 will be referred to as the "thickness direction". The one surface S1 and the other surface S2 extend in the surface direction. The surface direction intersects with the thickness direction. Preferably, the surface direction is perpendicular to the thickness direction.

[0025] The thermal insulation material 100 has both insulating properties and thermal insulation properties. The insulating properties of the thermal insulation material 100 can be defined by the resistance value of the thermal insulation material 100. The thermal insulation properties of the thermal insulation material 100 can be defined by the thermal conductivity of the thermal insulation material 100.

[0026] The resistance value of the thermal insulation material 100 is not limited as long as it prevents short circuits in the thermoelectric conversion member 21.

[0027] The thermal conductivity of the insulating material 100 is, for example, 1 W / m·K or less, preferably 0.5 W / m·K or less. When the thermal conductivity of the insulating material 100 is below the above upper limit, a temperature difference can be secured in the thickness direction, and the resulting electromotive force can be increased.

[0028] The lower limit of the thermal conductivity of the insulation material 100 is not limited. The thermal conductivity of the insulation material 100 is, for example, 0.01 W / m·K or higher.

[0029] Examples of materials for the thermal insulation material 100 include glass wool, rock wool, calcium silicate, polystyrene, polyethylene, urethane resin, melamine resin, phenolic resin, foamed glass, perlite, cellulose fiber, alumina fiber, ceramic fiber, carbon fiber, fumed silica, and alkali earth silicate. Preferably, the thermal insulation material 100 is glass wool, rock wool, and calcium silicate, and more preferably glass wool.

[0030] The thermal insulation material 100 may consist of only one of the materials described above. The thermal insulation material 100 may contain two or more of the materials described above. The thermal insulation material 100 includes at least one of glass wool, rock wool, and calcium silicate. When the thermal insulation material 100 includes at least one of glass wool, rock wool, and calcium silicate, the thermal insulation performance of the thermal insulation material 100 can be improved. This makes it possible to secure a temperature difference in the thickness direction and increase the electromotive force obtained. Preferably, the thermal insulation material 100 includes a layer made of at least one of glass wool, rock wool, and calcium silicate. More preferably, the thermal insulation material 100 consists of glass wool.

[0031] The thickness of the thermal insulation material 100 is, for example, 10 mm or more, preferably 30 mm or more. If the thickness of the thermal insulation material 100 is greater than or equal to the above lower limit, a temperature difference can be secured in the thickness direction, and the resulting electromotive force can be increased.

[0032] There is no upper limit to the thickness of the insulation material 100. The thickness of the insulation material 100 is, for example, 300 mm or less.

[0033] (1-2) Thermoelectric Conversion Member The thermoelectric conversion member 21 generates an electromotive force due to the temperature difference in the thickness direction. As a result, the thermoelectric conversion element 2 generates an electromotive force due to the temperature difference. The thermoelectric conversion member 21 has a plurality of P-type portions 211A, 211B and a plurality of N-type portions 212A, 212B.

[0034] The P-type portion 211A behaves as a P-type semiconductor. The P-type portion 211A extends in the thickness direction. In this embodiment, the P-type portion 211A penetrates the thermal insulation material 100. The P-type portion 211A has one end 2111A, another end 2112A, and a main body portion 2113A. The one end 2111A is located outside the thermal insulation material 100. The one end 2111A is located on one surface S1 of the thermal insulation material 100. The other end 2112A is located outside the thermal insulation material 100. The other end 2112A is located on the other surface S2 of the thermal insulation material 100. The main body portion 2113A is located between the one end 2111A and the other end 2112A. The main body portion 2113A is located inside the thermal insulation material 100. In other words, at least a portion of the thermoelectric conversion member 21 (the main body portion 2113A) is placed inside the thermal insulation material 100. The main body portion 2113A has the same length as the thickness of the thermal insulation material 100 in the thickness direction. In other words, the thermoelectric conversion member 21 has a predetermined length in the thickness direction. Note that the main body portion 2113A does not have to extend along the thickness direction. The main body portion 2113A may be inclined with respect to the thickness direction.

[0035] The N-type portion 212A behaves as an N-type semiconductor. The N-type portion 212A extends in the thickness direction. In this embodiment, the N-type portion 212A penetrates the thermal insulation material 100. The N-type portion 212A has one end 2121A, another end 2122A, and a main body portion 2123A. The one end 2121A is located outside the thermal insulation material 100. The one end 2121A is located on one surface S1 of the thermal insulation material 100. The other end 2122A is located outside the thermal insulation material 100. The other end 2122A is located on the other surface S2 of the thermal insulation material 100. The main body portion 2123A is located between the one end 2121A and the other end 2122A. The main body portion 2123A is located inside the thermal insulation material 100. The main body portion 2123A has the same length in the thickness direction as the thickness of the thermal insulation material 100.

[0036] Then, one end 2121A of the N-type portion 212A is electrically connected to one end 2111A of the P-type portion 211A. As a result, one cell structure 21A of the π-type thermoelectric conversion element is formed from one P-type portion 211A and one N-type portion 212A. The connection portion between the P-type portion 211A and the N-type portion 212A is placed on the surface S1 of the thermal insulation material 100.

[0037] Furthermore, similar to the cell structure 21A, one cell structure 21B of the π-type thermoelectric conversion element is formed from one P-type portion 211B and one N-type portion 212B. The connection portion between the P-type portion 211B and the N-type portion 212B is placed on the surface S1 of the thermal insulation material 100.

[0038] Then, the other end 2122A of the N-type portion 212A is electrically connected to the other end 2112B of the P-type portion 211B. This connects the cell structure 21A and the cell structure 21B in series. The connection portion between the N-type portion 212A and the P-type portion 212B is placed on the surface S2 of the thermal insulation material 100.

[0039] In this embodiment, the thermoelectric conversion member 21 is thread-like. The thermoelectric conversion member 21 is sewn into the heat insulating material 100.

[0040] The diameter of the thermoelectric conversion member 21 is, for example, 150 μm or more, preferably 300 μm or more. If the diameter of the thermoelectric conversion member 21 is greater than or equal to the above lower limit, the electromotive force of the thermoelectric conversion member 21 can be increased.

[0041] The "diameter of the thermoelectric conversion member 21" refers to the minimum length of the thermoelectric conversion member 21 in the direction perpendicular to the direction in which the thermoelectric conversion member 21 extends (the radial direction of the thermoelectric conversion member 21). Specifically, if the cross-section of the thermoelectric conversion member 21 in the radial direction is circular, the "diameter of the thermoelectric conversion member 21" refers to the diameter of the circle. If the cross-section of the thermoelectric conversion member 21 in the radial direction is elliptical, the "diameter of the thermoelectric conversion member 21" refers to the length of the minor axis of the ellipse. If the thermoelectric conversion member 21 is ribbon-shaped, the "diameter of the thermoelectric conversion member 21" refers to the thickness of the thermoelectric conversion member 21.

[0042] The diameter of the thermoelectric conversion member 21 is, for example, 3000 μm or less, preferably 1500 μm or less, and more preferably 1000 μm or less. When the diameter of the thermoelectric conversion member 21 is not more than the above upper limit value, a decrease in the heat insulation performance of the heat insulating material 100 can be suppressed.

[0043] The thermoelectric conversion member 21 contains a conductive material, a binder, and, if necessary, a dopant.

[0044] The conductive material has conductivity. The conductive material imparts conductivity to the thermoelectric conversion member 21. Examples of the conductive material include semiconductor materials, carbon materials, and conductive polymers.

[0045] Examples of the semiconductor material include bismuth (Bi), tellurium (Te), antimony (Sb), cobalt (Co), zinc (Zn), silicon (Si), germanium (Ge), iridium (Ir), lead (Pb), and alloys thereof, skutterudite, and constantan. Note that the semiconductor material may contain a metal element, but has a higher resistance value than a metal due to its crystal structure or the combination of elements in the alloy, etc., and behaves as a semiconductor. The semiconductor material may be a semiconductor whisker.

[0046] Examples of the carbon material include carbon nanotubes, carbon nanofibers, graphene, graphene nanoribbons, and fullerene nanowhiskers.

[0047] Examples of the conductive polymer include polyacetylene, poly(p-phenylene vinylene), polypyrrole, polythiophene, polyaniline, poly(p-phenylene sulfide), a composite of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid (PEDOT:PSS), a composite of poly(3,4-ethylenedioxythiophene) and methylsiloxane polypropylsulfonic acid (PEDOT:PSiPS), and a composite of poly(3,4-ethylenedioxythiophene) and p-toluenesulfonic acid (PEDOT:Tos).

[0048] Preferably, the conductive material is a carbon material, and more preferably, carbon nanotubes. In other words, the thermoelectric conversion member 21 preferably contains carbon nanotubes, a binder, and optionally, a dopant. When the conductive material is carbon nanotubes, the thermoelectric conversion member 21 can be efficiently manufactured by utilizing the electrical properties of carbon nanotubes as a P-type semiconductor.

[0049] The proportion of conductive material in the thermoelectric conversion member 21 is, for example, 30% by mass or more, preferably 40% by mass or more, and more preferably 50% by mass or more. If the proportion of conductive material is above the above lower limit, the conductivity of the thermoelectric conversion member 21 can be ensured.

[0050] The proportion of conductive material in the thermoelectric conversion member 21 is, for example, 70% by mass or less, preferably 60% by mass or less. When the proportion of conductive material is below the above upper limit, the proportion of binder can be ensured, and the tensile strength of the thermoelectric conversion member 21 can be ensured.

[0051] The proportion of conductive material in the thermoelectric conversion member 21 is, for example, 40 parts by mass or more, preferably 60 parts by mass or more, per 100 parts by mass of binder. If the proportion of conductive material is above the above lower limit, the conductivity of the thermoelectric conversion member 21 can be ensured.

[0052] The proportion of conductive material in the thermoelectric conversion member 21 is, for example, 250 parts by mass or less, preferably 150 parts by mass or less, per 100 parts by mass of binder. When the proportion of conductive material is below the above upper limit, the proportion of binder can be maintained and the tensile strength of the thermoelectric conversion member 21 can be ensured.

[0053] The binder binds the conductive material. If the conductive material is carbon nanotubes, the binder binds the carbon nanotubes. Examples of binders include insulating resins and conductive resins.

[0054] Examples of insulating resins include polyethylene glycol, epoxy resin, acrylic resin, urethane resin, polystyrene resin, polyvinyl resin, and sodium carboxymethylcellulose (CMC-Na). Examples of polyvinyl resins include polyvinyl chloride, polyvinylpyrrolidone, polyvinyl alcohol, and polyvinyl acetate.

[0055] Examples of conductive resins include polyacetylene, poly(p-phenylenevinylene), polypyrrole, polythiophene, polyaniline, poly(p-phenylene sulfide), and poly(3,4-ethylenedioxythiophene).

[0056] Preferably, the binder is an insulating resin, and more preferably, polyethylene glycol.

[0057] The proportion of binder in the thermoelectric conversion member 21 is, for example, 30% by mass or more, preferably 40% by mass or more. If the proportion of binder is above the lower limit, the tensile strength of the thermoelectric conversion member 21 can be ensured.

[0058] The proportion of binder in the thermoelectric conversion member 21 is, for example, 70% by mass or less, preferably 60% by mass or less. When the proportion of binder is below the above upper limit, the proportion of conductive material can be ensured, and the conductivity of the thermoelectric conversion member 21 can be ensured.

[0059] The proportion of binder in the thermoelectric conversion member 21 is, for example, 40 parts by mass or more, preferably 60 parts by mass or more, per 100 parts by mass of conductive material. If the proportion of binder is above the above lower limit, the tensile strength of the thermoelectric conversion member 21 can be ensured.

[0060] The proportion of binder in the thermoelectric conversion member 21 is, for example, 250 parts by mass or less, preferably 150 parts by mass or less, per 100 parts by mass of conductive resin. When the proportion of binder is below the above upper limit, the proportion of conductive material can be ensured, and the conductivity of the thermoelectric conversion member 21 can be ensured.

[0061] The dopant imparts semiconductor electrical properties to the thermoelectric conversion member 21. Examples of dopants include P-type dopants and N-type dopants. The P-type dopant imparts P-type semiconductor electrical properties to the thermoelectric conversion member 21. Note that if the conductive material is carbon nanotubes, the thermoelectric conversion member 21 does not need to contain a P-type dopant because carbon nanotubes have P-type semiconductor electrical properties. The N-type dopant imparts N-type semiconductor electrical properties to the thermoelectric conversion member 21. An example of an N-type dopant is 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF). ６), polyethyleneimine (PEI), ethylenediaminetetrakis(propoxylate-block-ethoxylate) tetrol (trade name: Tetronic® 1107), reduced benzyl viologen (reduced BV), diphenylphosphine (dpp), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,4-bis(diphenylphosphino)butane (dppb), bis(diphenylphosphinomethyl)phenylphosphine (dppp), bis(diphenylphosphinoethyl)phenylphosphine (ppmdp), bis[(diphenylphosphinomethyl)phenylphosphino]methane (dppmpm), triphenylphosphine (tpp), tris(p-fluorophenyl)phosphine (F-tpp), tris(p-chlorophenyl)phosphine (Cl-tpp), tris(p-methoxy) Examples include phenyl)phosphine (MeO-tpp), tris(4-methoxy-3,5-dimethylphenyl)phosphine (tmdp), indole (Id), polyvinylpyrrole (PVPy), polyvinylpyrrolidone (PVP), 1,3-dimethyl-2-(o-methoxyphenyl)benzimidazole (o-MeO-DMBI), hydrazine monohydrate (HH), phenylhydrazine (MPH), 1,2-diphenylhydrazine (DPH), diazabicycloundecene (DBU), 1,5,7-triazabicyclo[4.4.0]deca-5-ene (TBD), and 7-methyl-1,5,7-triazabicyclo[4.4.0]deca-5-ene (MTBD). Triphenylphosphine is preferred as the N-type dopant.

[0062] The surface of the thermoelectric conversion member 21 may be coated. In other words, the thermoelectric conversion member 21 may have a core containing a conductive material, a binder, and a dopant, and a coating layer that coats the surface of the core. Examples of materials for the coating layer include resins, carbon fibers, metals, metal oxides, and silicon compounds. Examples of resins include epoxy resins, acrylic resins, urethane resins, fluororesins, polyvinyl alcohol, ethylene vinyl alcohol, polybutylene terephthalate, polyamides, polyimides, polyvinyl acetals, polysilsesquioxanes, polysilazanes, and parylenes. Examples of carbon fibers include carbon nanofibers. Examples of metals include aluminum and chromium. Examples of metal oxides include smectite, indium tin oxide (ITO), indium zinc oxide (IZO), aluminum zinc oxide (AZO), and zinc tin oxide (ZTO). Examples of silicon compounds include silica nanoparticles, silicon dioxide, and silicon nitride. The coating layer improves the strength and wear resistance of the thermoelectric conversion member 21. Furthermore, the coating layer suppresses the deterioration of the thermoelectric conversion member 21 due to oxygen and moisture.

[0063] Note that thermoelectric elements 2B and 2C have the same structure as thermoelectric element 2A. Therefore, the explanation of thermoelectric elements 2B and 2C is omitted.

[0064] (2) Conversion Circuit As shown in the diagram 1, the conversion circuit 3 converts the electromotive force generated in each of the thermoelectric conversion elements 2A, 2B, and 2C into an electrical signal. More specifically, the conversion circuit 3 converts the electromotive force of each of the thermoelectric conversion elements 2A, 2B, and 2C into a digital signal. The conversion circuit 3 is electrically connected to each of the thermoelectric conversion elements 2A, 2B, and 2C. The conversion circuit 3 includes an AFE (analog front-end) circuit and an analog-to-digital conversion circuit. The conversion circuit 3 adjusts the electromotive force of each of the thermoelectric conversion elements 2A, 2B, and 2C by the AFE circuit and converts it into a digital signal by the analog-to-digital conversion circuit.

[0065] (3) Transmitting Module The transmitting module 4 transmits the electrical signal converted by the conversion circuit 3. The transmitting module 4 has at least a transmitting antenna. The conversion circuit 3 and the transmitting module 4 may be mounted on the transmitter 10.

[0066] (4) Receiving module The receiving module 5 receives electrical signals transmitted by the transmitting module 4. The receiving module 5 has at least a receiving antenna. The communication standard between the transmitting module 4 and the receiving module 5 is not limited.

[0067] (5) Processing Unit The processing unit 6 performs a detection process (see Figure 5) described later based on the electrical signal received by the receiving module 5. The processing unit 6 is not limited as long as it can perform the detection process described later. The processing unit 6 includes, for example, a processor and memory. The processing unit 6 may be installed in a personal computer together with the receiving module 5.

[0068] 2. Detailed Detection Process As shown in Figure 5, the processing device 6 performs a process (detection process) to detect temperature changes of the target. In this embodiment, the processing device 6 detects a decrease in the temperature difference between the temperature of the insulation material 100 on the side of the pipe P and the temperature of the insulation material 100 on the opposite side of the pipe P.

[0069] For example, if the insulation material 100 gets wet, its thermal insulation performance decreases. When the thermal insulation performance of the insulation material 100 decreases, the temperature difference between the insulation material 100 on the side of the pipe P and the insulation material 100 on the opposite side of the pipe P decreases. As a result, the electromotive force of the thermoelectric conversion element 2 decreases.

[0070] Furthermore, even if the insulation material 100 is not wet, if water penetrates between the insulation material 100 and the pipe P, the surface temperature of the pipe P will decrease due to the penetrated water. When the surface temperature of the pipe P decreases, the temperature difference between the insulation material 100 on the pipe P side and the insulation material 100 on the opposite side of the pipe P decreases. As a result, the electromotive force of the thermoelectric conversion element 2 decreases.

[0071] The detection system 1 detects the intrusion of water into the insulating structure of the piping P by detecting a decrease in the electromotive force of the thermoelectric conversion element 2.

[0072] The detection process includes a reference value acquisition step (S1), a calculation step (S3), and a judgment step (S4). In other words, the processing device 6 performs the reference value acquisition step (S1), the calculation step (S3), and the judgment step (S4).

[0073] (1) Reference Value Acquisition Step In the reference value acquisition step (S1), the processing unit 6 acquires a reference value of the electromotive force generated in the thermoelectric conversion element 2. The reference value may be stored in advance in the memory of the processing unit 6. The reference value is set according to the object. If the object is the insulation material 100 of the pipe P, for example, the electromotive force when the insulation material 100, which has the thermoelectric conversion element 2 and is in a dry state, is installed on the pipe P may be used as the reference value. The processing unit 6 may acquire different reference values ​​depending on the ambient temperature. For example, a data table of reference values ​​according to ambient temperature may be stored in the memory of the processing unit 6, and the processing unit 6 may acquire a reference value according to ambient temperature from the data table. The processing unit 6 may also acquire different reference values ​​depending on the temperature difference between the temperature of the fluid (liquid or gas) flowing inside the pipe P and the ambient temperature, or the temperature difference between the surface temperature of the pipe P and the ambient temperature. For example, a data table of reference values ​​according to temperature difference may be stored in the memory of the processing unit 6, and the processing unit 6 may acquire a reference value according to the temperature difference between the temperature of the fluid (liquid or gas) flowing inside the pipe P and the ambient temperature.

[0074] (2) Calculation step Next, the processing unit 6 performs a calculation step (S3) based on the electrical signals received by the receiving module 5 (see Figure 1). Specifically, the processing unit 6 obtains the values ​​of the electromotive force generated in each of the thermoelectric conversion elements 2A, 2B, and 2C (measured values) based on the electrical signals received by the receiving module 5 (see Figure 1) (S2).

[0075] Next, the processing unit 6 performs a calculation step (S3). In the calculation step (S3), the processing unit 6 calculates the ratio Rn of the measured value of the electromotive force generated in the thermoelectric conversion element 2 to the acquired reference value. In the calculation step (S3), for each of the multiple thermoelectric conversion elements 2A, 2B, and 2C, the ratio Rn of the measured value to the reference value is calculated based on the same reference value. Specifically, the processing unit 6 calculates the ratio Rn of the measured value of the electromotive force generated in the thermoelectric conversion element 2A to the same reference value. １ The ratio of the measured electromotive force generated in the thermoelectric conversion element 2B is R. ２ , and the ratio R of the measured electromotive force generated in the thermoelectric conversion element 2C ３ Calculate each of these.

[0076] (3) Judgment step Next, in the judgment step (S4), the processing device 6 determines whether the ratio Rn of the measured value to the reference value is smaller than the threshold.

[0077] If the ratio Rn of the measured value to the reference value is smaller than the threshold (S4: YES), the processing unit 6 performs an alert process (S5). In the alert process, the processing unit 6 displays a warning on a predetermined display that, for example, water has entered the insulation structure of the piping P. More specifically, the processing unit 6 performs an alert when the ratio Rn of the measured value to the reference value is smaller than the threshold (S4: YES). １ If it is determined that the value is smaller than the threshold, a warning indicating that water has entered the insulating structure of the piping P near the thermoelectric conversion element 2A (see Figure 3) is displayed on a designated display.

[0078] Note that the alert processing (S5) is not limited to the process of displaying a warning on the display. In the alert processing (S5), the processing device 6 may sound an alarm through a predetermined speaker. In addition, the processing device 6 may stop the supply of liquid to the piping P together with the alert processing (S5), or in place of the alert processing (S5).

[0079] On the other hand, if the ratio Rn of the measured value to the reference value is greater than or equal to the threshold (S4: NO), the processing unit 6 does not perform an alert process (S5).

[0080] While the detection system 1 is running (S6: NO), the processing unit 6 repeats the acquisition of measured values ​​(S2), the calculation step (S3), the decision step (S4), and, if necessary, the alert processing (S5).

[0081] 3. Effects (1) The detection system 1 comprises a thermoelectric conversion element 2 and a processing unit 6, as shown in Figure 1. The processing unit 6 calculates the ratio Rn of the measured value to the reference value in the calculation step (S3), as shown in Figure 5.

[0082] By calculating the ratio Rn of the measured value to the reference value, the degree of change in the electromotive force of the thermoelectric conversion element 2 can be reliably detected.

[0083] As a result, temperature changes in the target can be accurately detected.

[0084] For example, if the object is the insulation material 100 of a pipe P (see Figures 2 and 3), when the insulation material 100 gets wet, the insulation performance of the insulation material 100 decreases. As a result, the temperature difference between the insulation material 100 on the side of the pipe P and the insulation material 100 on the opposite side of the pipe P decreases.

[0085] Furthermore, even if the insulation material 100 is not wet, if water penetrates between the insulation material 100 and the pipe P, the surface temperature of the pipe P will decrease due to the penetrated water. When the surface temperature of the pipe P decreases, the temperature difference between the insulation material 100 on the side facing the pipe P and the insulation material 100 on the opposite side of the pipe P also decreases.

[0086] As the temperature difference decreases, the electromotive force of the thermoelectric conversion element 2 decreases.

[0087] Here, the detection system 1 calculates the ratio Rn of the measured value to the reference value, as described above. In other words, the detection system 1 can reliably detect how much the electromotive force of the thermoelectric conversion element 2 has decreased relative to the reference value (i.e., the degree of change in the electromotive force of the thermoelectric conversion element 2).

[0088] As a result, temperature changes in the insulation material 100 (specifically, the decrease in temperature due to water infiltration) can be accurately detected.

[0089] (2) According to the detection system 1, as shown in Figure 5, the processing device 6 determines in the judgment step (S4) whether the ratio Rn of the measured value to the reference value is smaller than the threshold.

[0090] Therefore, if the processing unit 6 determines that the ratio Rn of the measured value to the reference value is smaller than the threshold, it can be inferred that a temperature change (specifically, a decrease in the temperature difference) is occurring in the target that causes a decrease in the electromotive force of the thermoelectric conversion element 2.

[0091] (3) According to the detection system 1, as shown in Figure 3, the detection system 1 includes a plurality of thermoelectric conversion elements 2A, 2B, and 2C.

[0092] Then, in the calculation step (S3), for each of the thermoelectric conversion elements 2A, 2B, and 2C, the ratio Rn of the measured value to the reference value is calculated based on the same reference value.

[0093] This allows for accurate detection of temperature changes at the locations where each of the thermoelectric conversion elements 2A, 2B, and 2C is located, based on the same reference value.

[0094] (4) According to the detection system 1, as shown in Figure 3, the thermoelectric conversion element 2 comprises a thermal insulation material 100 having a predetermined thickness and a thermoelectric conversion member 21. As shown in Figure 4, the thermoelectric conversion member 21 is thread-like and has a portion that is placed inside the thermal insulation material 100. The portion that is placed inside the thermal insulation material 100 has a predetermined length in the thickness direction.

[0095] Therefore, the thermoelectric conversion member 21 can generate electromotive force by utilizing the temperature difference in the thickness direction of the insulating material 100.

[0096] (5) The detection system 1 further comprises a conversion circuit 3, a transmission module 4, and a receiving module 5, as shown in Figure 1. The processing unit 6 performs a calculation step (S3) based on the electrical signal received by the receiving module 5.

[0097] Therefore, the electromotive force of the thermoelectric conversion element 2 can be converted into a signal by the conversion circuit 3 and transmitted to the processing unit 6 via the transmitting module 4 and the receiving module 5.

[0098] 4. Modified Examples Modified examples will be described. In the modified examples, the same reference numerals are used for components similar to those in the embodiments described above, and their descriptions are omitted.

[0099] (1) The detection system 1 is not limited to the insulation material 100 of the piping P. Examples of objects that the detection system 1 can detect include insulation materials for the roofs and exterior walls of houses, vacuum insulation materials, insulation materials for cooler boxes, insulation materials for liquefied gas tanks, and insulation materials for fermentation culture tanks.

[0100] (2) As shown in Figure 6, the detection system 1 may have a P-type thermoelectric conversion member 200A consisting only of a P-type portion 211 and an N-type thermoelectric conversion member 200B consisting only of an N-type portion 212. A part of the P-type thermoelectric conversion member 200A and a part of the N-type thermoelectric conversion member 200B may be electrically connected by a conductive paste 213 or the like.

[0101] In this case, the P-type thermoelectric conversion member 200A and the N-type thermoelectric conversion member 200B may each be thread-like and sewn into the insulation material 100.

[0102] The detection system 1 may also include a metal wire instead of the P-type thermoelectric conversion member 200A. In other words, the detection system 1 may have a cell structure consisting of an N-type thermoelectric conversion member and a metal wire electrically connected to the N-type thermoelectric conversion member.

[0103] Furthermore, the detection system 1 may be equipped with a metal wire instead of the N-type thermoelectric conversion member 200B. In other words, the detection system 1 may have a cell structure consisting of a P-type thermoelectric conversion member and a metal wire electrically connected to the P-type thermoelectric conversion member.

[0104] (3) As shown in Figure 7, the thermoelectric conversion element 300 may have cover layers 110A and 110B that cover the connection portion between the P-type portion 211 and the N-type portion 212. The thermoelectric conversion element 300 may consist only of the heat insulating material 100, the thermoelectric conversion member 21 and the cover layers 110A and 110B. As the material for the cover layers 110A and 110B, for example, the material of the heat insulating material 100 described above can be cited. The cover layers 110A and 110B may have a coating layer. As the material for the coating layer, for example, the material of the coating layer of the thermoelectric conversion member 21 described above can be cited.

[0105] Furthermore, as shown in Figure 8, the entire thermoelectric conversion member 21 may be placed inside the thermal insulation material 100. In other words, the thermoelectric conversion member 21 may consist only of the portion placed inside the thermal insulation material 100.

[0106] (4) The insulating material is not limited to the thermal insulation material 100 described above. As shown in Figure 9, the thermoelectric conversion element 400 may have a resin body 401 as an example of an insulating material and a thermoelectric conversion member 21. In this case, the thermoelectric conversion element 400 may be embedded in the thermal insulation material 100 described above. Examples of materials for the resin body 401 include thermoplastic resins and thermosetting resins.

[0107] Examples of thermoplastic resins include polyvinyl chloride (PVC), polystyrene (PS), styrene-based resins (HIPS, SAN, ABS), acrylic resin (PMMA), polyethylene (PE), polypropylene (PP), polycarbonate (PC), modified polyetherphenyl (m-PPE), polyacetal (POM), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyamide (PA), polyarylate (PAR), polysulfone (PSU), polyethersulfone (PES), thermoplastic polyimide (TPI, PEI, PAI), polyphenylene sulfide (PPS), polyetheretherketone (PEEK), liquid crystal polymer (LCP), and fluororesins (PTFE, PFA, PVDF, ETFE).

[0108] Examples of thermosetting resins include epoxy resin (EP), silicone resin (SI), diallyl phthalate resin (PDAP), phenolic resin (PF), unsaturated polyester resin (UP), polyimide resin (PI), polyurethane resin (PUR), melamine resin (MF), urea resin (UF), and thermosetting acrylic resin (PAR).

[0109] Preferably, the material for the resin base 401 is a thermosetting resin, and more preferably, an epoxy resin.

[0110] (5) The same effects and advantages as in the embodiment can be obtained in the modified examples (1) to (4) described above.

[0111] The above invention is provided as an illustrative embodiment of the present invention, but this is merely illustrative and should not be interpreted restrictively. Modifications of the present invention that are obvious to those skilled in the art are included in the claims below.

[0112] The detection system of the present invention can be used, for example, to detect temperature changes in insulation material around piping.

[0113] 1. Detection system 2. Thermoelectric conversion element 3. Conversion circuit 4. Transmitting module 5. Receiving module 6. Processing unit 21. Thermoelectric conversion component 100. Thermal insulation material (an example of an insulating material)

Claims

1. A detection system comprising a thermoelectric conversion element that generates an electromotive force due to a temperature difference, and a processing device, wherein the processing device performs a reference value acquisition step of acquiring a reference value of the electromotive force generated in the thermoelectric conversion element, and a calculation step of calculating the ratio of the measured value of the electromotive force generated in the thermoelectric conversion element to the acquired reference value.

2. The detection system according to claim 1, wherein the processing device further performs a determination step of determining whether the ratio of the measured value to the reference value is smaller than a threshold.

3. The detection system according to claim 1, wherein the detection system comprises a plurality of thermoelectric conversion elements, and in the calculation step, for each of the plurality of thermoelectric conversion elements, the ratio of the measured value to the reference value is calculated based on the same reference value.

4. The detection system according to claim 1, wherein the thermoelectric conversion element comprises an insulating material having a predetermined thickness, and a thermoelectric conversion member that is thread-like, disposed inside the insulating material, has a predetermined length in the thickness direction of the insulating material, and generates an electromotive force due to a temperature difference in the thickness direction of the insulating material.

5. The detection system according to claim 1, further comprising: a conversion circuit that converts the electromotive force generated in the thermoelectric conversion element into an electrical signal; a transmitting module that transmits the electrical signal converted by the conversion circuit; and a receiving module that receives the electrical signal transmitted by the transmitting module, wherein the processing device performs the calculation step based on the electrical signal received by the receiving module.

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