Thermoelectric conversion module

Abstract

The present disclosure provides a thermoelectric conversion module, wherein the thermoelectric conversion module (100) comprises a substrate (10H), a plurality of thermoelectric conversion element pairs (20) arranged on the substrate and electrically connected in series, a pair of external terminals (40) for inputting or outputting electric power, and a low-melting-point conductor (60), wherein the low-melting-point conductor has a melting point substantially equal to the heat-resistant temperature of a p-type thermoelectric conversion element (21P) or an n-type thermoelectric conversion element (20N), one of the pair of external terminals having a first connection portion (42) connected to the p-type thermoelectric conversion element, and the other of the pair of external terminals having a second connection portion (43) connected to the n-type thermoelectric conversion element, the first connection portion, the second connection portion, and the low-melting-point conductor being located in an inner region (51) of the substrate, at least a portion of the low-melting-point conductor being located between the pair of external terminals, and the low-melting-point conductor being electrically insulated from at least one of the pair of external terminals, thereby enabling the thermal power generation system to continue to be used even when a portion of the plurality of thermoelectric conversion modules is exposed to high temperatures and fails.

Description

Technical Field

[0001] The present disclosure relates to a thermoelectric conversion module. Background Art

[0002] A thermoelectric conversion element is an element that can convert heat into electricity or electricity into heat. A thermoelectric conversion element formed of a thermoelectric material that exhibits the Seebeck effect can obtain heat energy from a relatively low temperature (e.g., below 200°C) heat source and convert it into electricity. For example, according to the thermal power generation technology using such a thermoelectric conversion element, heat energy that was previously discharged directly to the surrounding environment in the form of steam, warm water, exhaust gas, etc. without being used can be recovered and effectively utilized.

[0003] A general thermoelectric conversion element has a pair of a p-type thermoelectric conversion element and an n-type thermoelectric conversion element with different electrical polarities of carriers, i.e., a so-called "π-type structure". This structure is disclosed, for example, in non-patent document 1. In a thermoelectric conversion element with a "π-type structure", the p-type thermoelectric conversion element and the n-type thermoelectric conversion element are electrically connected in series and thermally connected in parallel. In this specification, the symmetry of the p-type thermoelectric conversion element and the n-type thermoelectric conversion element is referred to as a "thermoelectric conversion element pair". A thermoelectric conversion module is formed by electrically connecting each pair of a plurality of thermoelectric conversion element pairs in series. The thermoelectric conversion module has, for example, dozens of thermoelectric conversion element pairs. By converting thermal energy into electricity, a voltage of, for example, several mV to several V can be obtained from the thermoelectric conversion module.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2016-9779

[0007] Patent Document 2: Japanese Patent Application Publication No. 2016-35882

[0008] Non-patent literature

[0009] Non-patent document 1: G. Jeffrey Snyder and Eric S. Toberer, “Complex thermoelectric materials”, Nature Materials, Vol. 7, No. 2, 2008, pp. 105-114 Summary of the invention

[0010] Problems to be solved by the invention

[0011] In order to obtain more power generation, a plurality of thermoelectric conversion modules are sometimes electrically connected in series to form a thermal power generation system. In this thermal power generation system, when a part of the plurality of thermoelectric conversion modules fails, the electrical conduction of the thermal power generation system as a whole is interrupted because the plurality of thermoelectric conversion modules are connected in series. It is expected that the thermal power generation system can continue to be used even in such a situation.

[0012] An exemplary embodiment of the present disclosure provides a thermoelectric conversion module that enables a thermal power generation system to continue to be used even when some of a plurality of thermoelectric conversion modules are exposed to high temperatures and fail.

[0013] Technical solutions to solve problems

[0014] The thermoelectric conversion module disclosed in the present invention comprises: a substrate; a plurality of thermoelectric conversion element pairs, which are arranged on the substrate and electrically connected in series; a pair of external terminals, which are arranged on the substrate and are used to input or output electric power; and a low-melting-point conductor, wherein each of the plurality of thermoelectric conversion element pairs has a p-type thermoelectric conversion element and an n-type thermoelectric conversion element, and the low-melting-point conductor has a melting point substantially equal to the heat-resistant temperature of the p-type thermoelectric conversion element or the n-type thermoelectric conversion element, one of the pair of external terminals has a first connection portion electrically connected to the p-type thermoelectric conversion element located on one end side of the plurality of thermoelectric conversion element pairs, and the other of the pair of external terminals has a There is a second connection portion electrically connected to the n-type thermoelectric conversion element located on the other end side of the plurality of thermoelectric conversion element pairs, the first connection portion and the second connection portion are located in an inner region surrounded by an outer region of the substrate, the outer region includes a region where a plurality of the p-type thermoelectric conversion elements and a plurality of the n-type thermoelectric conversion elements are located on the outermost sides of the surface of the substrate, the low-melting-point conductor is arranged in the inner region surrounded by the outer region of the substrate, and at least a portion of the low-melting-point conductor is located between the pair of external terminals when viewed from the normal direction of the substrate, and the low-melting-point conductor is electrically insulated from at least one of the pair of external terminals.

[0015] Effects of the Invention

[0016] According to an exemplary embodiment of the present disclosure, there is provided a thermoelectric conversion module that enables a thermal power generation system to continue to be used by using thermoelectric conversion modules that have not failed even if some of the plurality of thermoelectric conversion modules fail due to exposure to high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 1 is an oblique projection diagram schematically showing the structure of a thermoelectric conversion module 100 according to an exemplary embodiment.

[0018] Figure 2 1 is a plan view schematically showing the structure of a thermoelectric conversion module 100 according to an exemplary embodiment.

[0019] Figure 3 This is a schematic diagram showing, in an enlarged manner, a pair of external terminals 40 and p-type thermoelectric conversion element 21P and n-type thermoelectric conversion element 21N electrically connected thereto.

[0020] Figure 4A It is a schematic diagram which shows the low-melting-point conductor 60 provided on the substrate 10H in an enlarged manner.

[0021] Figure 4B It is a schematic diagram which shows the low-melting-point conductor 60 provided on the substrate 10H in an enlarged manner.

[0022] Figure 5 1 is a schematic diagram showing a low-melting-point conductor 60 supported by a support 61 provided between a pair of external terminals 40 .

[0023] Figure 6 1 is a schematic diagram showing a state in which the pair of external terminals 40 are short-circuited by the melted low-melting-point conductor 60 .

[0024] Figure 7 1 is a schematic diagram showing a groove 70 provided in the substrate 10H for guiding the molten low-melting-point conductor 60 .

[0025] Fig. 8A It is an oblique projection diagram schematically showing a typical structure of a conventional thermoelectric conversion module 200 .

[0026] Figure 8B 1 is a plan view schematically showing the structure of a conventional thermoelectric conversion module 200 .

[0027] Fig. 9 1 is a plan view schematically showing the structure of a thermoelectric conversion module 200 in which a switch SW for short-circuiting a pair of external terminals 40 is mounted. DETAILED DESCRIPTION

[0028] Before describing the embodiments of the present disclosure, the findings of the inventors of the present application which are the basis of the present disclosure will be described.

[0029] Fig. 8A A typical structure of a conventional thermoelectric conversion module 200 is schematically shown. Figure 8B The configuration and wiring of the plurality of thermoelectric conversion element pairs 20 on the substrate 10C on the low temperature heat source side when the thermoelectric conversion module 200 is viewed from the normal direction of the substrate (z direction of the drawing) is schematically shown. The structure of the conventional thermoelectric conversion module 200 is disclosed in, for example, non-patent document 1. In order to avoid complicating the drawings, Fig. 8AA portion of the substrate 10H on the high-temperature heat source side is omitted.

[0030] The thermoelectric conversion module 200 includes a substrate 10H on the high temperature heat source side, a substrate 10C on the low temperature heat source side, a plurality of thermoelectric conversion element pairs 20 sandwiched by the two substrates, and a pair of external terminals 40. Below, the substrate 10H on the high temperature heat source side and the substrate 10C on the low temperature heat source side are sometimes referred to as substrate 10H and substrate 10C, respectively. At least the surfaces of these substrates are formed of an insulating material. The thermoelectric conversion element pair 20 has a p-type thermoelectric conversion element 21P and an n-type thermoelectric conversion element 21N. For example, a plurality of p-type thermoelectric conversion elements 21P and a plurality of n-type thermoelectric conversion elements 21N are arranged in a grid-like manner on the substrate 10C on the low temperature heat source side. The plurality of thermoelectric conversion element pairs 20 are electrically connected in series to each other through wiring 30H provided on the substrate 10H and wiring 30C provided on the substrate 10C. The p-type thermoelectric conversion element 21P and the n-type thermoelectric conversion element 21N are bonded to the wiring 30H, 30C, for example, using solder or an adhesive.

[0031] The pair of external terminals 40 are terminals for inputting or outputting power to the thermoelectric conversion module 200. The pair of external terminals 40 are electrically connected to the plurality of thermoelectric conversion element pairs 20 connected in series. Considering the arrangement of the plurality of thermoelectric conversion element pairs 20 and the efficiency of wiring, the pair of external terminals 40 is preferably Fig. 8A As shown, they are typically arranged at the corners of the substrate 10C.

[0032] By heating the substrate 10H and cooling the substrate 10C, that is, heating the substrate 10H without heating the substrate 10C, a temperature difference is generated in the p-type thermoelectric conversion element 21P and the n-type thermoelectric conversion element 21N of the thermoelectric conversion element pair 20. Electromotive force is generated due to the Seebeck effect. The thermoelectric conversion module 200 converts thermal energy into electricity. The electricity generated inside the thermoelectric conversion module 200 can be taken out to the outside from a pair of external terminals 40.

[0033] When current is injected into the thermoelectric conversion module 200 from a pair of external terminals 40, heat absorption occurs on the surface of one substrate 10C and heat dissipation occurs on the surface of the other substrate 10H due to the Peltier effect. The thermoelectric conversion module 200 converts electric power into thermal energy. In this way, the thermoelectric conversion module 200 can also perform cooling and heating using electric power.

[0034] For example, due to a failure in the cooling function, the thermoelectric conversion module 200 may become a high temperature state compared to normal operation. In this case, due to thermal expansion, cracks are easily generated in the joint between the thermoelectric conversion element and the wiring. It is believed that this is caused by the difference in the thermal expansion coefficient of the material or the thermal expansion coefficient between the materials. Even when one of the multiple thermoelectric conversion element pairs 20 fails like this, the thermoelectric conversion module 200 will become an electrical disconnection state. As a result, the thermoelectric conversion module 200 will not be able to function.

[0035] For example, a thermal power generation system can be constructed using a plurality of thermoelectric conversion modules 200. In a thermal power generation system, a plurality of thermoelectric conversion modules are typically electrically connected in series with each other. By connecting more thermoelectric conversion modules, more power generation can be obtained.

[0036] Assume that a disconnection occurs in one of the plurality of thermoelectric conversion modules 200. In this case, even if a disconnection does not occur in the remaining thermoelectric conversion modules 200, the electrical conduction of the thermal power generation system as a whole will be interrupted. For example, when the thermoelectric conversion module 200 is exposed to a high temperature above a predetermined temperature, the thermal power generation system will not function.

[0037] In order to solve the above-mentioned problems, a technology has been designed to maintain the electrical conduction of the entire system by short-circuiting a pair of external terminals 40. Patent document 1 discloses a technology that uses an electrical conduction portion to short-circuit the current introduction terminal only in a high temperature state. When the thermoelectric conversion module reaches a high temperature state, the internal bonding material will melt. As a result, the thickness of the thermoelectric conversion module is reduced due to the sinking of the substrate. Utilizing this phenomenon, the current introduction terminal is short-circuited by electrical contact with the electrical conduction portion only when a high temperature state is reached. Patent document 2 discloses a temperature short-circuit element that operates in an atmosphere of temperature above the melting point of a fusible conductor that melts at high temperatures. By melting and solidifying the fusible conductor in an atmosphere of temperature above the melting point of the fusible conductor, two adjacent electrodes are short-circuited.

[0038] As described above, in the structure of the conventional thermoelectric conversion module 200, a pair of external terminals 40 are located in the outer region 50 of the module, particularly in the corner. In this specification, the outer region 50 refers to the region indicated by the dotted line where the group of thermoelectric conversion element pairs 20 arranged at the outermost sides among the plurality of thermoelectric conversion element pairs 20 arranged in a grid pattern in the entire region of the substrate exists.

[0039] Fig. 9 The structure of the thermoelectric conversion module 200 is schematically shown, in which a switch SW capable of short-circuiting a pair of external terminals 40 is installed. The switch SW may be a fusible conductor as in Patent Document 2. By replacing the thermoelectric conversion element pair 20 between the pair of external terminals 40 with the switch SW, Fig. 9In this structure, the switch SW is arranged between the pair of external terminals 40. In the case of such a simple replacement, the switch SW is inevitably arranged in the outer area 50 of the substrate 10C.

[0040] In fact, heat dissipation also occurs from the side of the thermoelectric conversion module 200, so the outer area 50 is less likely to become high temperature than near the center of the substrate 10C. Therefore, for example, due to a failure of the cooling function, the temperature near the center of the thermoelectric conversion module 200 reaches a temperature at which the electrical connection of the plurality of thermoelectric conversion element pairs 20 is disconnected. Even in this case, the outer area 50 may not reach this temperature. As a result, if only the switch SW is set for the previous structure, the switch SW that short-circuits a pair of external terminals 40 is likely to not function properly. In addition, in the previous structure, the pair of external terminals 40 are far apart. Therefore, it is considered that simply setting a switch SW between the terminals is insufficient for short-circuiting the terminals.

[0041] Furthermore, in the conventional structure, even if the switch SW is provided on the substrate 10C on the low-temperature heat source side, there is a problem that sufficient heat cannot be conducted to make it function. As shown in Non-Patent Document 1, a pair of external terminals 40 are usually provided on the substrate 10C on the low-temperature heat source side. One of the reasons is that if the external terminals are provided on the substrate 10H on the high-temperature heat source side, they will function as a heat sink and heat will be easily dissipated therefrom.

[0042] Based on the above findings, the inventors of the present application found that a low melting point conductor can be provided in the inner region surrounded by the outer region of the substrate on the high temperature heat source side, and thus obtained the present disclosure.

[0043] <Exemplary Implementation>

[0044] Hereinafter, embodiments of the thermoelectric conversion module of the present disclosure will be described with reference to the drawings.

[0045] Figure 1 The structure of the thermoelectric conversion module 100 of this embodiment is schematically shown. Figure 1 A portion of the substrate 10C on the low-temperature heat source side is omitted. Figure 2The configuration and wiring conditions of multiple thermoelectric conversion element pairs 20 on the substrate 10H on the high-temperature heat source side when the thermoelectric conversion module 100 is observed from the normal direction of the substrate 10H (z direction of the drawing) are schematically shown. In this specification, the thermoelectric conversion module 100 having two substrates 10H and 10C on the high-temperature heat source side and the low-temperature heat source side is taken as an example to illustrate the embodiment of the present disclosure. However, a thermoelectric conversion module that does not have a substrate 10C on the low-temperature heat source side is also known. Such a module is sometimes referred to as a "half skeleton type". A semi-skeleton type thermoelectric conversion module also falls within the scope of the present disclosure. Below, the description that is repeated with the above-mentioned previous structure is omitted.

[0046] The thermoelectric conversion module 100 includes a substrate 10H on the high temperature heat source side, a substrate 10C on the low temperature heat source side, a plurality of thermoelectric conversion element pairs 20, a pair of external terminals 40, and a low melting point conductor 60. The materials of the substrate 10H on the high temperature heat source side and the substrate 10C on the low temperature heat source side are not particularly limited as long as at least their surfaces have electrical insulation. However, a material with high thermal conductivity and high heat resistance is preferred. For example, aluminum oxide can be preferably used as a material.

[0047] A plurality of thermoelectric conversion element pairs 20, more specifically, a plurality of p-type thermoelectric conversion elements 21P and a plurality of n-type thermoelectric conversion elements 21N are typically arranged in a grid pattern on the substrate 10H on the high-temperature heat source side. The dimension of the substrates 10C and 10H in the x-direction is, for example, 1 cm to 6 cm. The dimension in the y-direction is, for example, 1 cm to 6 cm. The dimension in the x-direction of the p-type thermoelectric conversion element 21P and the n-type thermoelectric conversion element 21N is, for example, 1.0 mm to 3.0 mm. The dimension in the y-direction is, for example, 1.0 mm to 3.0 mm. The height in the z-direction is, for example, about 1.0 mm to 3.0 mm. It should be noted that the arrangement and wiring of the plurality of thermoelectric conversion element pairs 20 are not limited to the illustrated example.

[0048] The p-type thermoelectric conversion element 21P and the n-type thermoelectric conversion element 21N each contain at least a thermoelectric conversion material. The type of thermoelectric conversion material is not particularly limited. For example, the thermoelectric conversion material can be selected according to the temperature of the intended use. As an example, when the thermoelectric conversion module 100 is used in a temperature range of about room temperature to about 200°C, Bi-Te based materials are preferred. When the thermoelectric conversion module 100 is used in a temperature range of about 200°C to 500°C, Pb-Te based materials, Co-Sb based materials, Zn-Sb based materials or Mg-Sb based materials are preferred. When the thermoelectric conversion module 100 is used in a temperature range of about 500°C to 1000°C, Si-Ge based materials are preferred.

[0049] Figure 3A pair of external terminals 40 and the p-type thermoelectric conversion element 21P and the n-type thermoelectric conversion element 21N electrically connected thereto are shown in an enlarged manner. Figure 2 As shown, a pair of external terminals 40 are provided on the substrate 10H on the high temperature heat source side. The pair of external terminals 40 are terminals for taking out the power generated in the plurality of thermoelectric conversion element pairs 20 to the outside. The pair of external terminals 40 are arranged closely on the substrate 10H with a gap w therebetween. For example, the gap w is equal to the gap between the p-type thermoelectric conversion element 21P and the n-type thermoelectric conversion element 21N in the thermoelectric conversion element pair 20.

[0050] One of the pair of external terminals 40 includes a first connection portion 42 having a contact surface that contacts the p-type thermoelectric conversion element 21P. The first connection portion 42 is electrically connected to the p-type thermoelectric conversion element 21P located at one end side of the plurality of thermoelectric conversion element pairs 20 connected in series. The other of the pair of external terminals 40 includes a second connection portion 43 having a contact surface that contacts the n-type thermoelectric conversion element 21N. The second connection portion 43 is electrically connected to the n-type thermoelectric conversion element 21N located at the other end side of the plurality of thermoelectric conversion element pairs 20. Figure 2 As shown in FIG. 1 , the first connection portion 42 and the second connection portion 43 are located in the inner region 51 surrounded by the outer region 50 of the substrate 10H. Furthermore, the first connection portion 42 and the second connection portion 43 are close to each other near the center of the substrate 10H. The center of the substrate 10H refers to the intersection of the diagonal lines of the substrate in a substantially rectangular shape. However, the first connection portion 42 and the second connection portion 43 only need to be located in the inner region 51 of the substrate 10H, and do not necessarily need to be located near the center.

[0051] The materials of the wiring 30H, the wiring 30C, and the pair of external terminals 40 are not particularly limited. However, a material with high electrical conductivity and high heat resistance is preferred. For example, copper or silver wiring can be used as the material. The line widths of the wiring 30H, the wiring 30C, and the pair of external terminals 40 are appropriately determined based on the amount of current that may flow in the thermoelectric conversion module 100.

[0052] The low melting point conductor 60 is provided in the inner region 51 of the substrate 10H. At least a portion of the low melting point conductor 60 is disposed in the normal direction ( Figure 2 When viewed in the z direction, the low melting point conductor 60 can be located between the pair of external terminals 40. Figure 2 As shown, the low melting point conductor 60 is located between the pair of external terminals 40. The low melting point conductor 60 is preferably provided near the center of the substrate 10H. Thus, when the thermoelectric conversion module 100 is exposed to high temperature, heat is more effectively conducted to the low melting point conductor 60. As a result, the pair of external terminals 40 can be short-circuited more accurately.

[0053] Figure 4A ,4B The low melting point conductor 60 provided on the substrate 10H is shown in an enlarged manner. Figure 5 The low melting point conductor 60 supported by a support body 61 disposed between a pair of external terminals 40 is shown. The shape of the low melting point conductor 60 is, for example, a dome type or a prism. In a temperature atmosphere lower than the melting point of the low melting point conductor 60, the low melting point conductor 60 is electrically insulated from at least one of the pair of external terminals 40. For example, as shown in the figure, by providing a gap between the low melting point conductor 60 and the pair of external terminals 40, the low melting point conductor 60 can be electrically insulated. Alternatively, a gap can be provided between the low melting point conductor 60 and the other party while the low melting point conductor 60 is in contact with one of the pair of external terminals 40. In either case, the pair of external terminals 40 are not short-circuited. In this way, the low melting point conductor 60 will not affect the module operation, that is, the input or output of the current. The thermoelectric conversion module 100 operates in the same manner as the conventional thermoelectric conversion module 200 in a temperature atmosphere below the melting point of the low melting point conductor 60.

[0054] As a method of electrically insulating the low melting point conductor 60, Figure 5 As shown in FIG. 1 , a support body 61 may be provided between the pair of external terminals 40. The low-melting-point conductor 60 may be electrically insulated by providing, for example, a plate-shaped low-melting-point conductor 60 on the support body 61. In this case, at least a portion of the low-melting-point conductor 60 is provided in the normal direction ( Figure 2 When viewed in the z direction (in the z direction), the portion is located between the pair of external terminals 40, and the remaining portion overlaps the pair of external terminals 40. Alternatively, the low-melting-point conductor 60 may be electrically insulated by sandwiching an insulating film between the low-melting-point conductor 60 and the pair of external terminals 40 instead of a gap.

[0055] Low melting point conductor 60 has a melting point substantially equal to the heat resistance temperature of p-type thermoelectric conversion element 21P or n-type thermoelectric conversion element 21N. More specifically, the melting point of low melting point conductor 60 satisfies at least the following formula (I) or formula (II).

[0056] Tp×0.90≤Tm≤Tp×1.1 (I)

[0057] Tn×0.90≤Tm≤Tn×1.1 (II)

[0058] Here, Tm is the melting point of the low melting point conductor 60. Tp is the heat resistance temperature of the p-type thermoelectric conversion element 21P. Tn is the heat resistance temperature of the n-type thermoelectric conversion element 21N. The heat resistance temperature is the temperature at which the series connection of the plurality of thermoelectric conversion element pairs 20 is disconnected due to thermal expansion of at least one of the plurality of thermoelectric conversion element pairs 20.

[0059] The melting point of the low melting point conductor 60 needs to be a temperature higher than the maximum temperature expected when the thermoelectric conversion module 100 is normally used. Therefore, the melting point of the low melting point conductor 60 is preferably the same as the heat resistance temperature at which the module may be damaged. The low melting point conductor 60 is, for example, a low melting point metal. For example, consider the case where a Bi-Te system material is used as a material for a thermoelectric conversion element. In this case, usually, the thermoelectric conversion module 100 is mostly used in a temperature range of about 100°C or less, and is prone to damage when it becomes above 200°C. Therefore, as the low melting point conductor 60, for example, an In-Sn alloy or an In-Bi alloy is preferred. The melting point of the In-Sn alloy can be adjusted in the range of 117°C to 232°C by adjusting the mixing ratio of In and Sn. The melting point of the In-Bi alloy can be adjusted in the range of 72°C to 271°C by adjusting the mixing ratio of In and Bi.

[0060] For example, the heat resistance of the thermoelectric conversion module 100 can be improved by changing the thermoelectric conversion element to be used, so as to achieve use at a higher temperature. In this case, as the low melting point conductor 60, for example, a Sn-Sb alloy or a Sn-Cu alloy is preferred. The melting point of the Sn-Sb alloy can be adjusted in the range of 232°C to 630°C by adjusting the mixing ratio of Sn and Sb. The melting point of the Sn-Cu alloy can be adjusted in the range of 223°C to 1083°C by adjusting the mixing ratio of Sn and Cu.

[0061] In one embodiment, low melting point conductor 60 is an In—Sn alloy having a melting point of 200° C. to 232° C. P-type thermoelectric conversion element 21P and n-type thermoelectric conversion element 21N are each formed of a Bi—Te-based material.

[0062] Figure 6 The state where the pair of external terminals 40 are short-circuited by the melted low-melting-point conductor 60 is shown.

[0063] In an atmosphere with a temperature above the melting point of the low-melting-point conductor 60, a pair of external terminals 40 are short-circuited by the melted low-melting-point conductor 60. For example, when the cooling function on the low-temperature heat source side fails, more heat may be accumulated in the thermoelectric conversion module 100 than in normal use. Therefore, the module temperature may rise to a temperature near the heat resistance limit. Then, since the melting point of the low-melting-point conductor 60 is about the same as the heat resistance temperature, the low-melting-point conductor 60 may melt and diffuse. The melted low-melting-point conductor 60 is in electrical contact with both sides of the pair of external terminals 40, and as a result, the pair of external terminals 40 will short-circuit. The low-melting-point conductor 60 has conductivity regardless of whether it is in a liquid state or a solid state. Therefore, the state of the temporarily melted low-melting-point conductor 60 may be solid or liquid depending on the temperature in the module. In a thermal power generation system, although the damaged thermoelectric conversion module 100 can no longer function, the electrical conduction of multiple thermoelectric conversion modules 100 connected in series can be ensured. In this way, as long as the remaining thermoelectric conversion modules 100 are not damaged, the thermal power generation system can continue to be used.

[0064] According to the present embodiment, by providing the low melting point conductor 60 in the inner region 51 of the substrate 10H and arranging the pair of external terminals 40 close to each other, it is possible to reduce the influence of heat dissipation from the side of the thermoelectric conversion module 100. As a result, when the module temperature rises to near the heat resistance limit, the thermoelectric conversion module 100 operates more accurately than the conventional thermoelectric conversion module 200.

[0065] Figure 7 The groove 70 provided in the substrate 10H for guiding the molten low-melting-point conductor 60 is shown.

[0066] The substrate 10H may also have a groove 70 for guiding the melted low-melting-point conductor 60. In this case, at least a portion of the low-melting-point conductor 60 may be provided in the groove 70. By providing the groove 70, the range in which the low-melting-point conductor 60 spreads when melted can be limited to a range sufficient to meet the need to short-circuit the pair of external terminals 40. Thus, the thermoelectric conversion module 100 can be operated more accurately.

[0067] In this embodiment, a structure in which a single low-melting-point conductor 60 is provided on the substrate 10H is described. However, the present disclosure is not limited thereto. One or more other low-melting-point conductors (not shown) may be further provided between the pair of external terminals 40. Thus, even if one low-melting-point conductor does not function well, the other low-melting-point conductors function to more accurately short-circuit the pair of external terminals 40.

[0068] Thermoelectric conversion module 100 can be composed of the same elements as conventional thermoelectric conversion module 200 except low melting point conductor 60. Therefore, a wide range of known methods can be used to manufacture thermoelectric conversion module 100. Low melting point conductor 60 is mounted by, for example, soldering or printed wiring.

[0069] Industrial Applicability

[0070] The thermoelectric conversion module of the present disclosure can be preferably used in a thermoelectric conversion device that performs mutual conversion between thermal energy and electric power.

[0071] Description of symbols

[0072] 10H, 10C: substrate; 20: thermoelectric conversion element pair; 21P: p-type thermoelectric conversion element; 21N: n-type thermoelectric conversion element; 30H, 30C: wiring; 40: a pair of external terminals; 42: a first connection portion; 43: a second connection portion; 50: an outer region; 51: an inner region; 60: a low-melting-point conductor; 61: a support body; 70: a groove; 100: a thermoelectric conversion module.

Claims

1. A thermoelectric conversion module, comprising: substrate; a plurality of thermoelectric conversion element pairs disposed on the substrate and electrically connected in series; a pair of external terminals provided on the substrate for inputting or outputting electric power; and Low melting point conductor, Each of the plurality of thermoelectric conversion element pairs includes a p-type thermoelectric conversion element and an n-type thermoelectric conversion element. The low melting point conductor has a melting point substantially equal to the heat resistance temperature of the p-type thermoelectric conversion element or the n-type thermoelectric conversion element. One of the pair of external terminals has a first connection portion electrically connected to a p-type thermoelectric conversion element located at one end side of the plurality of thermoelectric conversion element pairs, and the other of the pair of external terminals has a second connection portion electrically connected to an n-type thermoelectric conversion element located at the other end side of the plurality of thermoelectric conversion element pairs. The first connection portion and the second connection portion are located in an inner region surrounded by an outer region of the substrate. The outer region includes a region where the plurality of the p-type thermoelectric conversion elements and the plurality of the n-type thermoelectric conversion elements disposed on the outermost sides of the substrate are present. The low melting point conductor is provided in an inner region surrounded by the outer region of the substrate, At least a portion of the low-melting-point conductor is located between the pair of external terminals when viewed from the normal direction of the substrate, and The low melting point conductor is electrically insulated from at least one of the pair of external terminals, The heat-resistant temperature is a temperature at which the series connection of the plurality of thermoelectric conversion element pairs is disconnected due to thermal expansion of at least one of the plurality of thermoelectric conversion element pairs.

2. The thermoelectric conversion module according to claim 1, The substrate is a substrate on the high temperature heat source side, and The pair of external terminals is provided on the substrate on the high-temperature heat source side.

3. The thermoelectric conversion module according to claim 1 or 2, The low melting point conductor is provided on the substrate between the pair of external terminals.

4. The thermoelectric conversion module according to claim 1 or 2, The melting point of the low melting point conductor at least satisfies the following mathematical formula (I) or mathematical formula (II), Tp×0.90≤Tm≤Tp×1.1(I) Tn×0.90≤Tm≤Tn×1.1(II) in, Tm is the melting point, Tp is the heat-resistant temperature of the p-type thermoelectric conversion element, and Tn is the heat-resistant temperature of the n-type thermoelectric conversion element.

5. The thermoelectric conversion module according to claim 1 or 2, The low melting point conductor is any one alloy selected from In-Sn alloy, In-Bi alloy, Sn-Sb alloy and Sn-Cu alloy.

6. The thermoelectric conversion module according to claim 1 or 2, The low melting point conductor has a melting point of 200° C. or higher and 232° C. or lower.

7. The thermoelectric conversion module according to claim 6, The p-type thermoelectric conversion element and the n-type thermoelectric conversion element are each formed of a Bi-Te system material, and The low melting point conductor is an In-Sn alloy.

8. The thermoelectric conversion module according to claim 1 or 2, The low melting point conductor is disposed at the center of the substrate.

9. The thermoelectric conversion module according to claim 2, It also has a substrate on the low-temperature heat source side. The plurality of thermoelectric conversion element pairs are sandwiched by the substrate on the high-temperature heat source side and the substrate on the low-temperature heat source side.

10. The thermoelectric conversion module according to claim 1 or 2, The distance between the pair of external terminals is equal to the distance between the thermoelectric conversion element pair of the p-type thermoelectric conversion element and the n-type thermoelectric conversion element.

11. The thermoelectric conversion module according to claim 1 or 2, Another low-melting-point conductor provided between the pair of external terminals is further provided.

12. The thermoelectric conversion module according to claim 1 or 2, In an atmosphere having a temperature lower than the melting point of the low-melting-point conductor, the low-melting-point conductor is electrically insulated from at least one of the pair of external terminals.

13. The thermoelectric conversion module according to claim 1 or 2, In an atmosphere of temperature equal to or higher than the melting point of the low-melting-point conductor, the pair of external terminals are short-circuited by the melted low-melting-point conductor.

14. The thermoelectric conversion module according to claim 1 or 2, The substrate has a groove for guiding the molten low-melting-point conductor. At least a portion of the low-melting-point conductor is disposed in the groove.

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