JP5065077B2 - Thermoelectric generator - Google Patents

Description

  The present invention relates to a thermoelectric power generation apparatus that generates power using a temperature difference by using a thermoelectric conversion element.

  Conventionally, thermoelectric power generation is known in which a thermoelectric conversion element is disposed between a high temperature side heat exchanger and a low temperature side heat exchanger to generate electric power. The thermoelectric conversion element applies a thermoelectric effect called the Peltier effect, Thomson effect, or Seebeck effect. When a semiconductor material is used, a P-type thermoelectric conversion element and an N-type thermoelectric conversion element are combined. Thus, a thermoelectric conversion module is configured. Such a thermoelectric conversion module has a simple structure, is easy to handle, and can maintain stable characteristics. Therefore, the thermoelectric conversion module can generate heat using heat in gas discharged from an engine of an automobile or a furnace of a factory. Research is being advanced toward the application of.

  In the application to thermoelectric power generation, not only the performance improvement of the high temperature side heat exchanger and the low temperature side heat exchanger is required, but also between the high temperature side heat exchanger or the low temperature side heat exchanger and the thermoelectric conversion module. It is known that the contact thermal resistance also greatly affects the temperature difference between both sides of the thermoelectric conversion module. In particular, in a thermoelectric conversion module, when deformation occurs due to a temperature difference between the two sides and contact thermal resistance increases, the thermoelectric conversion efficiency is significantly reduced.

  Further, from the viewpoint of durability of the thermoelectric conversion module, an environment where the thermoelectric conversion module does not come into contact with oxygen is desirable. Some thermoelectric conversion modules are completely sealed. However, when such a thermoelectric conversion module is used, a multilayer structure is formed between the high temperature side heat exchanger or the low temperature side heat exchanger and the thermoelectric conversion module. Therefore, there is a drawback that the contact thermal resistance increases.

  As a related technique, Patent Literature 1 discloses a thermoelectric generator that aims to properly hold a thermoelectric generator between a heating unit and a cooling unit. The thermoelectric generator includes a plurality of thermoelectric modules that generate an electromotive force due to a temperature difference between a high temperature side and a low temperature side, a high temperature side heat exchanger that contacts the high temperature side of the plurality of thermoelectric modules, and a high temperature side heat exchange A low temperature side heat exchanger that is in contact with the low temperature side of the plurality of thermoelectric generation modules so that the plurality of thermoelectric generation modules are sandwiched between them, and the plurality of thermoelectric generation modules are connected to the high temperature side heat exchanger and the low temperature side heat exchanger. There are provided a disc spring for applying a load to be sandwiched between the disc springs and a load adjusting mechanism capable of independently adjusting the holding load by the disc spring for each of the plurality of thermoelectric modules.

Specifically, the load adjustment mechanism includes a weld nut fixed to a common bracket (housing), a load adjustment bolt screwed to the weld nut, and a tip between the load adjustment bolt and the disc spring. The sandwiched spring retainer plate is the main component. However, such a mechanism is complicated and cannot be made into a stack structure, and is not suitable for downsizing a thermoelectric generator.
Japanese Unexamined Patent Publication No. 2007-149841 (first and eighth pages, FIG. 1)

  Therefore, in view of the above points, the present invention reduces the contact thermal resistance between the heat exchanger and the thermoelectric conversion module, and has high thermoelectric conversion efficiency, excellent durability and reliability, compact, space efficiency, and An object of the present invention is to provide a thermoelectric generator having good maintainability.

  In order to solve the above problems, a thermoelectric power generation device according to one aspect of the present invention is a thermoelectric power generation device that generates power using a temperature difference between a high-temperature gas and a low-temperature coolant, and is disposed so as to face each other. And the first and second low-temperature side heat exchangers into which the coolant is introduced and the first and second low-temperature side heat exchangers that are distributed between the first and second surfaces facing each other. A plurality of springs, at least one first thermoelectric conversion module attached to a surface opposite to the first surface of the first low temperature side heat exchanger, and a second low temperature side heat exchanger And sandwiching at least one first thermoelectric conversion module between at least one second thermoelectric conversion module attached to a surface opposite to the second surface of the first heat exchanger and the first low temperature side heat exchanger. Between the first high temperature side heat exchanger arranged and gas introduced and the second low temperature side heat exchanger Without even being disposed so as to sandwich one second thermoelectric conversion module, and second high-temperature-side heat exchanger the gas is introduced.

  According to the present invention, by connecting the first and second high temperature side heat exchangers while contracting a plurality of springs between the first and second low temperature side heat exchangers, the heat exchanger and the thermoelectric conversion By reducing the contact thermal resistance between the modules, a thermoelectric power generator having high thermoelectric conversion efficiency, excellent durability and reliability, compact, good space efficiency and maintainability can be provided.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. The same constituent elements are denoted by the same reference numerals, and the description thereof is omitted.
FIG. 1 is a plan view showing a structural unit of a thermoelectric generator according to a first embodiment of the present invention. 2 is an exploded perspective view showing components of the thermoelectric generator shown in FIG. 1, and FIG. 3 is a perspective view showing a state in which the components shown in FIG. 2 are combined. As shown in FIGS. 1 to 3, this thermoelectric power generation apparatus includes two high temperature side heat exchangers (high temperature ducts) 10 and two low temperature side heat exchangers each having at least one thermoelectric conversion module 20 attached thereto. (Cooling plate) 30.

  High temperature exhaust gas from an automobile engine, a factory furnace, or the like is introduced into the high temperature side heat exchanger 10. In addition, a coolant (for example, water) is introduced into the low temperature side heat exchanger 30. As shown in FIG. 2, each low temperature side heat exchanger 30 has a flow path 30a for flowing water in a first direction (downward in FIG. 2) and a second direction (upward in FIG. 2). The flow paths 30a of the upper and lower two low-temperature side heat exchangers 30 are connected to each other through a sealing material (for example, an O-ring) 30b.

  In this embodiment, the two low temperature side heat exchangers 30 are stacked in two upper and lower stages. A plurality of springs 40 are distributed and arranged in a plurality of openings of a positioning member (for example, punching metal) 41 fixed to one low temperature side heat exchanger 30 in the upper and lower two stages. The low temperature side heat exchanger 30 is arranged to face each other with the plurality of springs 40 interposed therebetween. By disposing the plurality of springs 40 in this manner, the contact thermal resistance between the high temperature side heat exchanger 10 or the low temperature side heat exchanger 30 and the thermoelectric conversion module 20 can be reduced, and the thermoelectric The vibration resistance of the conversion module 20 can be improved.

  Here, the inlet / outlet of the coolant of the low temperature side heat exchanger 30 has a laminated structure by the flow path 30a having rigidity, so that the inlet of the coolant of the low temperature side heat exchanger 30 that is continuously stacked up and down and Each of the outlets can be connected to a single pipe. Moreover, since the thermoelectric conversion module 20 and the low temperature side heat exchanger 30 are integrated and sealed, there is no need to seal the thermoelectric conversion module 20 alone, so the thermoelectric conversion module 20 and the low temperature side heat exchanger 30 are sealed. It becomes possible to completely seal the thermoelectric conversion module 20 without increasing the contact thermal resistance between them.

  The high temperature side heat exchanger 10 is made of stainless steel, for example, and has high rigidity. On the other hand, the low temperature side heat exchanger 30 is formed of, for example, aluminum or an aluminum alloy and has flexibility. Further, in order to give flexibility to the low temperature side heat exchanger 30, the thickness of the plate of the low temperature side heat exchanger 30 is reduced to, for example, about 1 mm, or the height of the internal flow path is reduced to, for example, about 2 mm. Or as shown in FIGS. 5-7, you may make it divide the low temperature side heat exchanger 30 itself long and thinly in the direction orthogonal to the flow direction of gas. If it does so, the low temperature side heat exchanger 30 will become flexible like one thin board.

  As shown in FIG. 3, when two high-temperature side heat exchangers 10 are fastened and connected from above and below using multi-stage bolts 50 that penetrate the low-temperature side heat exchanger 30, In the meantime, the plurality of springs 40 are contracted and the low temperature side heat exchanger 30 is deformed, and the thermoelectric conversion module 20 is pressed against the high temperature side heat exchanger 10 to be in close contact therewith. At the same time, the flow paths 30a of the two low temperature side heat exchangers 30 in the upper and lower stages are connected. As a result, the contact thermal resistance is reduced, and a significant improvement in thermoelectric conversion efficiency can be expected. Further, since no auxiliary part for pushing the spring 40 is required, the structure of the thermoelectric generator can be simplified.

  Here, as shown in FIG. 4A, the multi-stage bolt 50 penetrating the low-temperature side heat exchanger 30 and the high-temperature side heat exchanger 10 may be brought into direct contact with each other. As illustrated, a collar 51 or the like may be sandwiched between the multistage bolt 50 and the high temperature side heat exchanger 10 so that the distance between the high temperature side heat exchangers 10 can be adjusted. In FIG. 3, only the multi-stage bolt 50 attached to one location of each high temperature side heat exchanger 10 is shown, but actually, a plurality of locations (see FIG. 1) of each high temperature side heat exchanger 10. The multi-stage bolt 50 is attached through the low temperature side heat exchanger 30 at 20 places). As shown in FIG. 5, when the low-temperature side heat exchanger 30 is divided into elongated portions, the multi-stage bolts 50 may be attached between the elongated low-temperature side heat exchangers 30.

  Furthermore, by using the multistage bolt 50 penetrating the low temperature side heat exchanger 30, the structural units as shown in FIG. 3 can be stacked to form a stack structure, so that the compactness of the thermoelectric generator is improved. In that case, the layer of the high temperature side heat exchanger 10, the layer of the thermoelectric conversion module 20, the layer of the low temperature side heat exchanger 30, the layer of the spring 40, the layer of the low temperature side heat exchanger 30, the layer of the thermoelectric conversion module 20 The layers are arranged in the order of layers of the high-temperature side heat exchanger 10, the layer of the thermoelectric conversion module 20, the layer of the low-temperature side heat exchanger 30, and so on.

  FIG. 5 is a plan view showing a structural unit of a thermoelectric generator according to a modification of the first embodiment of the present invention. 6 is an exploded perspective view showing the components of the thermoelectric generator shown in FIG. 5, and FIG. 7 is a perspective view showing a state in which the components shown in FIG. 6 are combined. In the modified example of the first embodiment, the low-temperature side heat exchanger 30 is elongated in a direction orthogonal to the gas flow direction, and a plurality of rows in the horizontal direction (three rows in FIGS. 5 to 7). ) Low temperature side heat exchangers 30 are stacked in two upper and lower stages. The other points are the same as those of the first embodiment of the present invention.

  Referring to FIGS. 2 and 6, a large number of heat transfer fins having a pin shape are provided at least in a region corresponding to the position of the thermoelectric conversion module 20 in the high temperature side heat exchanger 10 and the low temperature side heat exchanger 30. It has been.

  The heat transfer fin provided in the high temperature side heat exchanger 10 is made of, for example, stainless steel, and the cross-sectional shape of the fin is various. However, by reducing the equivalent diameter to, for example, about 1 mm, the flow resistance against the gas flow is reduced. Not only improves heat transfer performance but also makes it difficult for soot to adhere. Further, since the gas temperature in the gas flow direction decreases with heat transfer, the power generation output of the thermoelectric conversion module 20 decreases in the gas flow direction. In order to avoid this and maximize the power generation output of each thermoelectric conversion module 20, the density is lowered near the exhaust gas inlet and increased as it approaches the exhaust gas outlet, and the thermoelectric conversion is performed in the gas flow direction. The pitch of the heat transfer fins may be different in the direction in which the exhaust gas flows so that the temperature difference generated in the module 20 becomes substantially uniform. The heat transfer fin provided in the low temperature side heat exchanger 30 is formed of, for example, aluminum or an aluminum alloy, and the cross-sectional shape of the fin is various. The equivalent diameter is, for example, about 1 mm to 2 mm, and the pitch is, for example, 2 mm to 4 mm. Degree.

  FIG. 8 is a perspective view illustrating an example of the thermoelectric conversion module illustrated in FIGS. 1 to 3 and FIGS. 5 to 7. The thermoelectric conversion module 20 includes a P-type element (P-type semiconductor) 21 and an N-type element (N-type semiconductor) 22. As a material of the P-type element 21 and the N-type element 22, for example, a bismuth (Bi) -tellurium (Te) -based compound is used. The thermoelectric conversion module 20 includes an electrode 23, terminals 24 and 25, and electrically insulating substrates 26 and 27.

  In the thermoelectric conversion module 20, a PN element pair is formed by joining a P-type element 21 and an N-type element 22 via an electrode 23. In a plurality of PN element pairs connected in series, a terminal 24 is connected to the N-type element at one end, and a terminal 25 is connected to the P-type element at the other end. When a temperature difference is applied between the electrical insulating substrate 26 and the electrical insulating substrate 27, an electromotive force is generated between the terminal 24 and the terminal 25.

  In the present embodiment, a metal electrode is used as the electrode 23, but a bonding layer or a diffusion prevention layer may be provided between the electrode 23 and the element 21 or 22. The electrically insulating substrates 26 and 27 are, for example, ceramic plates such as alumina, or aluminum nitride plates, and ensure electrical insulation between the electrode 23 and the high temperature side heat exchanger 10 or the low temperature side heat exchanger 30. Moreover, it has a low thermal resistance, and heat between the high temperature side heat exchanger 10 and the high temperature side of the thermoelectric conversion module 20 and between the low temperature side heat exchanger 30 and the low temperature side of the thermoelectric conversion module 20. Resistance is minimized.

  Alternatively, by electrically spraying ceramic on one surface of the high temperature side heat exchanger 10 shown in FIG. 2 or 6 to form an insulating region, an electrical insulating substrate attached to the high temperature side heat exchanger 10 side can be omitted. Can do. A high thermal conductive resin is pressure-bonded to one surface of the low temperature side heat exchanger 30, or when the low temperature side heat exchanger 30 is made of aluminum, an alumite treatment is applied to one surface of the low temperature side heat exchanger 30. By forming the insulating region, the electrically insulating substrate attached to the low temperature side heat exchanger 30 side may be omitted.

  FIG. 9 is a diagram for explaining an example of a wiring method of the thermoelectric conversion module. 9 shows a plurality of thermoelectric conversion modules 20 arranged in three rows, and three or more (four in FIG. 9) thermoelectric conversion modules 20 are arranged in each row. In this example, wiring is performed for each row of thermoelectric conversion modules.

  As shown in FIG. 9, in each row of thermoelectric conversion modules, wiring of a plurality of thermoelectric conversion modules 20 is performed alternately using electric wires 28 having conductive wires covered with vinyl or the like. That is, in each row, the two terminals of the odd-numbered thermoelectric conversion modules are arranged to face the first direction (front in FIG. 9) orthogonal to the row, and the two terminals of the even-numbered thermoelectric conversion modules However, it arrange | positions so that it may face the 2nd direction (FIG. 9 back) opposite to a 1st direction, and one terminal of every other thermoelectric conversion module is electrically connected.

  For example, in the second row of thermoelectric conversion modules M (2,1) to M (2,4), one terminal of the thermoelectric conversion module M (2,1) is one of the thermoelectric conversion modules M (2,3). And one terminal of the thermoelectric conversion module M (2, 2) is connected to one terminal of the thermoelectric conversion module M (2, 4). Furthermore, the other terminal of the thermoelectric conversion module M (2,1) is connected to the other terminal of the thermoelectric conversion module M (2,2), and the other terminal 83 of the thermoelectric conversion module M (2,3) is The first external connection terminal or the thermoelectric conversion module M (3, 4) is connected to the terminal 84, and the other terminal 82 of the thermoelectric conversion module M (2, 4) is connected to the second external connection terminal or thermoelectric conversion module M. It is connected to the terminal 81 of (1, 3). The same applies to the thermoelectric conversion modules M (1,1) to M (1,4) in the first row and the thermoelectric conversion modules M (3,1) to M (3,4) in the third row. Thereby, the several thermoelectric conversion module 20 can be arrange | positioned adjacently, making a clearance gap as small as possible.

Next, a second embodiment of the present invention will be described.
FIG. 10 is a perspective view showing a thermoelectric generator according to the second embodiment of the present invention. In the second embodiment, highly rigid plates 60 and 70 are disposed at both ends of the stack structure. Accordingly, the plate 60, the spring 40 layer, the low temperature side heat exchanger 30 layer, the thermoelectric conversion module 20 layer, the high temperature side heat exchanger 10 layer,..., The thermoelectric conversion module 20 layer, the low temperature side heat exchange. The layers are arranged in the order of the container 30 layer, the spring 40 layer, and the plate 70. The other points are the same as in the first embodiment. According to the second embodiment, the same effect as in the first embodiment can be obtained.

Next, a third embodiment of the present invention will be described.
FIG. 11 is a perspective view showing a thermoelectric generator according to the third embodiment of the present invention. In the third embodiment, a highly rigid plate 60 is disposed at one end of the stack structure. Therefore, the layer of the plate 60, the spring 40, the layer of the low temperature side heat exchanger 30, the layer of the thermoelectric conversion module 20, the layer of the high temperature side heat exchanger 10, the layer of the thermoelectric conversion module 20, and the layer of the low temperature side heat exchanger 30 ..., each layer is arranged in the order of the layers of the high temperature side heat exchanger 10. The other points are the same as in the first embodiment. According to the third embodiment, the same effect as in the first embodiment can be obtained.

  INDUSTRIAL APPLICABILITY The present invention can be used in a thermoelectric power generation apparatus that generates power using a temperature difference by using a thermoelectric conversion element.

It is a top view which shows the structural unit of the thermoelectric power generating apparatus which concerns on the 1st Embodiment of this invention. It is a perspective view which decomposes | disassembles and shows the component of the thermoelectric power generator shown in FIG. FIG. 3 is a perspective view showing a state in which the components shown in FIG. 2 are combined. It is a figure which shows the connection structure of a multistage volt | bolt and a high temperature side heat exchanger. It is a top view which shows the structural unit of the thermoelectric generator which concerns on the modification of the 1st Embodiment of this invention. It is a perspective view which decomposes | disassembles and shows the component of the thermoelectric power generator shown in FIG. FIG. 7 is a perspective view showing a state where the components shown in FIG. 6 are combined. It is a perspective view which shows an example of the thermoelectric conversion module shown in FIGS. 1-3 and FIGS. It is a figure for demonstrating the example of the wiring method of a thermoelectric conversion module. It is a perspective view which shows the thermoelectric power generator which concerns on the 2nd Embodiment of this invention. It is a perspective view which shows the thermoelectric generator which concerns on the 3rd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... High temperature side heat exchanger, 20 ... Thermoelectric conversion module, 21 ... P-type element, 22 ... N-type element, 23 ... Electrode, 24, 25 ... Terminal, 26, 27 ... Electrical insulation board, 28 ... Electric wire, 30 ... Low temperature side heat exchanger, 30a ... flow path, 30b ... sealing material, 40 ... spring, 41 ... positioning member, 50 ... multi-stage bolt, 60, 70 ... plate, 80-85 ... terminal

Claims (7)

A thermoelectric power generator that generates power using a temperature difference between a high-temperature gas and a low-temperature coolant,
First and second low temperature side heat exchangers disposed oppositely and into which a coolant is introduced;
A plurality of springs arranged in a distributed manner between the first and second opposed surfaces of the first and second low temperature side heat exchangers;
At least one first thermoelectric conversion module attached to a surface opposite to the first surface of the first low temperature side heat exchanger;
At least one second thermoelectric conversion module attached to a surface opposite to the second surface of the second low temperature side heat exchanger;
A first high temperature side heat exchanger arranged to sandwich the at least one first thermoelectric conversion module between the first low temperature side heat exchanger and a gas to be introduced;
A second high temperature side heat exchanger arranged to sandwich the at least one second thermoelectric conversion module with the second low temperature side heat exchanger, and gas is introduced;
A thermoelectric generator comprising:   The thermoelectric generator according to claim 1, wherein the first and second high temperature side heat exchangers have higher rigidity than the first and second low temperature side heat exchangers.   The thermoelectric generator according to claim 2, wherein the plurality of springs are arranged at positions corresponding to positions of the at least one first thermoelectric conversion module and positions of the at least one second thermoelectric conversion module.   Inside the first and second high temperature side heat exchangers, a plurality of heat transfer fins having a pin shape are positioned at the position of the at least one first thermoelectric conversion module and the at least one second thermoelectric conversion module. The thermoelectric power generator according to any one of claims 1 to 3, wherein the region corresponding to the position of the thermoelectric generator is provided so as to have a different pitch in a gas flow direction.   The at least one first thermoelectric conversion module includes three or more thermoelectric conversion modules arranged in one row, and the at least one second thermoelectric conversion module is three or more arranged in one row. In each row, the two terminals of the odd-numbered thermoelectric conversion modules are arranged to face the first direction orthogonal to the row, and the two terminals of the even-numbered thermoelectric conversion modules are It arrange | positions so that it may face the 2nd direction opposite to a 1st direction, and one terminal of every other thermoelectric conversion module is electrically connected. Thermoelectric generator.   A positioning member attached to the first or second low temperature side heat exchanger is further provided to fix the plurality of springs to the first or second low temperature side heat exchanger. The thermoelectric generator according to any one of the above.   A plurality of multi-stage bolts for connecting the first and second high temperature side heat exchangers while contracting the plurality of springs between the first and second low temperature side heat exchangers. Item 7. The thermoelectric generator according to any one of items 1 to 6.

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