JP6368860B2 - Thermoelectric conversion module and vehicle exhaust pipe - Google Patents

Description

  The present invention relates to a thermoelectric conversion module that can be used as a high-temperature heat source and has flexibility, and an exhaust pipe for a vehicle that uses the thermoelectric conversion module.

Thermoelectric conversion materials that can mutually convert thermal energy and electrical energy are used for thermoelectric conversion elements such as power generation elements and Peltier elements that generate electricity by heat.
The thermoelectric conversion element can convert heat energy directly into electric power, and has an advantage that a movable part is not required. For this reason, a thermoelectric conversion module (power generation device) formed by connecting a plurality of thermoelectric conversion elements is provided in a portion where heat is exhausted, such as an incinerator or various equipment in a factory, so that it is not necessary to incur operation costs and is simple. Can get power.

As such a thermoelectric conversion element, a so-called π-type thermoelectric conversion element is known.
A π-type thermoelectric conversion element includes a pair of lower electrodes spaced apart from each other on a substrate, an n-type thermoelectric conversion layer made of an n-type thermoelectric conversion material on one lower electrode, and an upper surface on the other lower electrode. P-type thermoelectric conversion layers made of a p-type thermoelectric conversion material are provided separately from each other, and the upper surfaces of both thermoelectric conversion layers are connected by an upper electrode.
Further, a plurality of π-type thermoelectric conversion elements are arranged on the substrate so that the n-type thermoelectric conversion layers and the p-type thermoelectric conversion layers are alternately arranged, and the n-type thermoelectric conversion layers of the adjacent thermoelectric conversion elements are arranged. And a p-type thermoelectric conversion layer are connected to connect a plurality of thermoelectric conversion elements in series to form a thermoelectric conversion module.

  For example, in Patent Document 1, in a thermoelectric conversion module using a π-type thermoelectric conversion element, an aluminum plate or the like is used as a substrate to act as a heat exchange member, and the heat exchange member is insulated with an aluminum anodic oxide film or the like. In addition, a metal plating layer of the same pattern as the electrode is provided on the insulating layer, and the electrode is joined to this metal plating layer, thereby greatly increasing the thermal resistance between the substrate as the heat exchange member and the metal electrode or thermoelectric conversion layer. To improve the heat exchange capacity.

By the way, in the thermoelectric conversion module described in Patent Document 1, no consideration is given to the flexibility (flexibility) of the thermoelectric conversion module.
On the other hand, as a use of a thermoelectric conversion module, it is considered that it is mounted on a drain pipe for discharging hot water (hot water) or an exhaust pipe of an automobile and used as a power generation device in a factory or the like.
In these applications, it is necessary to mount a thermoelectric conversion module on the curved surface. In response to this, various thermoelectric conversion modules having flexibility have been proposed.

For example, in Patent Document 2, as a thermoelectric conversion module mounted on the outer surface of a pipe, a thermoelectric conversion element (thermoelectric element chip) is mounted on a mounting land on a substrate made of a resin thin film, and the substrate is bent between the mounting lands. The thermoelectric conversion module satisfying “a ≦ 0.14D ^1/2 [mm]” when the outer diameter of the pipe is D and the dimension of the thermoelectric conversion element in the outer peripheral direction is a. Have been described.

  Patent Document 3 includes a thermoelectric conversion element including a p-type thermoelectric conversion element and an n-type thermoelectric conversion element, and a flexible wiring connected to the p-type thermoelectric conversion element and the n-type thermoelectric conversion element. The wiring can be expanded and contracted with displacement of the p-type thermoelectric conversion element and / or the n-type thermoelectric conversion element by including the conductive particles and the silicone resin, and the thermoelectric conversion element is expanded and contracted including the silicone resin. Describes a thermoelectric conversion module that is sandwiched between a flexible substrate having heat resistance and a heat-resistant substrate containing polyimide.

JP 2003-332642 A Japanese Patent No. 5228160 Japanese Patent No. 5626830

Since the thermoelectric conversion modules described in Patent Document 2 and Patent Document 3 have flexibility, they can follow the shape of the mounting position.
Therefore, it can be suitably used for a power generation device mounted on a curved surface such as a pipe such as a factory drain pipe or an automobile exhaust pipe.

Here, as the temperature of the heat source is higher, the thermoelectric conversion module easily obtains a larger amount of power generation. Therefore, it is preferable that the thermoelectric conversion module has sufficient heat resistance even when it is attached to a heat source having a high temperature exceeding 300 ° C., for example.
However, in the conventional flexible thermoelectric conversion module described in Patent Document 2 and Patent Document 3, since a resin material is used for the substrate and the wiring, it is possible to use a high-temperature heat source exceeding 300 ° C. Stable use is difficult.

  That is, a thermoelectric conversion module that achieves both flexibility that can be attached to a curved surface such as a pipe and good heat resistance that can be stably used with a high-temperature heat source exceeding 300 ° C. is not known.

  An object of the present invention is to solve such problems of the prior art, and is used in a heat source having a high temperature exceeding 300 ° C. that can be mounted on a high-temperature pipe such as an exhaust pipe of an automobile. An object of the present invention is to provide a thermoelectric conversion module that has both heat resistance that can be achieved and good flexibility, and a vehicle exhaust pipe that uses this thermoelectric conversion module.

In order to achieve such an object, the thermoelectric conversion module of the present invention includes a flexible aluminum substrate having an anodized film on at least one surface,
Two lower electrodes provided on the surface of the anodic oxide film of the substrate, the p-type thermoelectric conversion layer electrically connected to one lower electrode provided on the surface of one lower electrode, and the surface of the other lower electrode A thermoelectric conversion layer composed of an n-type thermoelectric conversion layer electrically connected to the other lower electrode provided, and an upper electrode connecting the p-type thermoelectric conversion layer and the n-type thermoelectric conversion layer in series with the lower electrode A plurality of connected thermoelectric conversion elements, and
Provided is a thermoelectric conversion module in which an upper electrode has flexibility and further connects a p-type thermoelectric conversion layer and an n-type thermoelectric conversion layer with bending.

In such a thermoelectric conversion module of the present invention, it is mounted on a curved surface, the curvature radius of the curved surface is L [mm], the height of the thermoelectric conversion layer is a [mm], and the p-type thermoelectric conversion of the thermoelectric conversion layer When the distance between the layer and the n-type thermoelectric conversion layer is b [mm], the length c [mm] of the upper electrode between the p-type thermoelectric conversion layer and the n-type thermoelectric conversion layer is b + (ab / L) <c and c <(4a ² + b ² ) ^1/2 are preferably satisfied.
The upper electrode is preferably a metal foil.
Moreover, it is preferable that the thickness of a board | substrate is 120 micrometers or less.
Moreover, it is preferable that a board | substrate has an aluminum base material which has an anodized film in one surface, and a metal base material laminated | stacked on the surface of the side in which the anodized film of an aluminum base material is not formed.
Moreover, it is preferable that at least one of the p-type thermoelectric conversion layer and the n-type thermoelectric conversion layer is bonded to at least one of the upper electrode and the lower electrode by a conductive adhesive layer.
The conductive adhesive layer preferably contains nickel.
Moreover, it is preferable that it is an air layer between adjacent thermoelectric conversion elements.
Moreover, it is preferable that the space between the p-type thermoelectric conversion layer and the n-type thermoelectric conversion layer of the thermoelectric conversion element is an air layer.
Moreover, it is preferable to cover a plurality of thermoelectric conversion elements and to have a flexible protective layer.
Moreover, it is preferable that the p-type thermoelectric conversion layer and the n-type thermoelectric conversion layer are each made of a silicide-based material doped p-type or n-type.
Further, it is preferably attached to a curved surface, and the curvature radius of the curved surface is preferably 30 mm or more.

  The vehicle exhaust pipe of the present invention is an exhaust pipe for a vehicle, and the thermoelectric conversion module of the present invention is mounted on the outer surface with the surface on which no thermoelectric conversion element is formed facing inward. A vehicle exhaust pipe is provided.

According to the present invention, a thermoelectric conversion module having both good flexibility that can be attached to a pipe or the like and high heat resistance that can be stably used even with a high-temperature heat source exceeding 300 ° C. is obtained. be able to.
Moreover, the exhaust pipe for vehicles of the present invention uses the thermoelectric conversion module of the present invention having good flexibility and high heat resistance, so that the high-temperature heat of the exhaust pipe that has conventionally been exhaust heat can be obtained. By using it, a large amount of power generation can be obtained.

FIG. 1 is a diagram conceptually illustrating an example of the thermoelectric conversion module of the present invention. FIG. 2 is a diagram conceptually showing the thermoelectric conversion element of the thermoelectric conversion module shown in FIG. 3 (A) and 3 (B) are diagrams conceptually showing another example of a substrate used in the thermoelectric conversion module of the present invention. FIG. 4 is a diagram conceptually illustrating a usage state of the thermoelectric conversion module illustrated in FIG. 1. FIG. 5 (A) to FIG. 5 (E) are conceptual diagrams for explaining an example of the method for manufacturing the thermoelectric conversion module of the present invention.

  Hereinafter, the thermoelectric conversion module and the vehicle exhaust pipe of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

FIG. 1 conceptually shows an example of the thermoelectric conversion module of the present invention. 2 conceptually shows the thermoelectric conversion element 14 constituting the thermoelectric conversion module 10 shown in FIG.
As shown in FIG. 1, the thermoelectric conversion module 10 is formed by arranging a plurality of thermoelectric conversion elements 14 on a flexible substrate 12 and connecting them in series.

As shown in FIGS. 1 and 2, the substrate 12 includes an aluminum base 18 and an insulating layer 20. The insulating layer 20 is made of an anodized film of aluminum formed by anodizing one surface of the aluminum base 18.
On the other hand, the thermoelectric conversion element 14 connects the lower electrode 24, the thermoelectric conversion layer 28 composed of the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n, and the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n. And an upper electrode 30. This thermoelectric conversion element 14 is the aforementioned π-type thermoelectric conversion element. In the thermoelectric conversion element 14, the p-type thermoelectric conversion layer 28 p and the n-type thermoelectric conversion layer 28 n are bonded and fixed to the lower electrode 24 by the lower adhesive layer 26. On the other hand, the upper electrode 30 is bonded to the upper surfaces of the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n by the upper adhesive layer 32.
In the thermoelectric conversion module 10, the thermoelectric conversion element 14 is formed on the insulating layer 20 (surface) and is connected in series with the adjacent thermoelectric conversion element 14 by the lower electrode 24.

As described above, the flexible substrate 12 includes the aluminum base 18 and the insulating layer 20. The insulating layer 20 is made of an anodized film of aluminum formed by anodizing one surface of the aluminum substrate 18.
As will be described in detail later, the thermoelectric conversion module 10 of the present invention uses a flexible substrate 12 formed by forming an insulating layer 20 by anodizing aluminum on the surface of an aluminum base 18. It has both good flexibility and heat resistance against a high-temperature heat source exceeding 300 ° C.

The aluminum base material 18 is a plate material (sheet-like material) mainly composed of aluminum, and various types made of aluminum or an aluminum alloy can be used.
The aluminum substrate 18 preferably has few impurities. In particular, the aluminum purity of the aluminum substrate is preferably 99.5% by mass or more, more preferably 99.9% by mass or more, and particularly preferably 99.99% by mass or more.
In addition to high-purity aluminum, industrial aluminum can also be used for the aluminum substrate 18. Use of industrial aluminum is advantageous in terms of cost.

  The insulating layer 20 is an anodized aluminum film formed by anodizing the surface of the aluminum substrate 18. The insulating layer 20 is for making the formation surface of the thermoelectric conversion element 14 of the aluminum base 18 having conductivity insulative.

What is necessary is just to set the thickness of the insulating layer 20 suitably that can ensure sufficient insulation.
According to the study by the present inventors, the thickness of the insulating layer 20 is preferably 0.1 to 20 μm, more preferably 1 to 15 μm, and particularly preferably 2 to 10 μm.
By setting the thickness of the insulating layer 20 to 0.1 μm or more, it is possible to sufficiently ensure the strength of the insulating layer 20 against impacts and scratches, and to prevent the insulating layer 20 from being cracked during handling. Further, the insulating layer 20 which is an anodic oxide film of aluminum is hard and brittle, but when the thickness of the insulating layer 20 is 20 μm or less, when the thermoelectric conversion module 10 is bent by mounting on a curved surface or the like, It is possible to prevent the insulating layer 20 from being cracked.

The insulating layer 20, that is, the anodic oxidation film of aluminum can be formed by a known anodic oxidation treatment.
The following method is illustrated as an example.

First, prior to the anodizing treatment of the aluminum substrate 18, the aluminum substrate 18 may be pretreated. An example of the pretreatment is heat treatment.
Moreover, it is preferable to perform a degreasing process and a mirror finishing process in advance on the surface of the aluminum substrate 18 to be anodized.

<Heat treatment>
The heat treatment is preferably performed at 200 to 350 ° C. for about 30 seconds to 2 minutes. As a specific method, for example, a method of putting the aluminum base material 18 in a heating oven can be mentioned. By performing such heat treatment, the regularity of the arrangement of micropores formed on the surface of the anodized film is improved.
Moreover, it is preferable to cool the aluminum base material 18 after heat processing rapidly. As a method for cooling, for example, a method in which the aluminum substrate 18 is directly poured into water or the like can be mentioned.

<Degreasing treatment>
The degreasing process is a process of dissolving and removing organic components such as dust, fat, and resin attached to the surface of the aluminum base 18 using an acid, an alkali, an organic solvent, or the like. This is performed for the purpose of preventing the occurrence of defects caused by organic components in each treatment described below.
A normal degreasing agent can be used for the degreasing treatment. Specifically, for example, various commercially available degreasing agents can be used by a predetermined method.

<Mirror finish processing>
The mirror finishing process eliminates irregularities on the surface of the aluminum substrate 18, for example, rolling streaks generated during the rolling of the aluminum substrate 18, and improves the uniformity and reproducibility of the sealing treatment by an electrodeposition method or the like. Done.
The mirror finish processing is not particularly limited, and a normal method can be used. Examples thereof include mechanical polishing, chemical polishing, and electrolytic polishing.

  Examples of the mechanical polishing include a method of polishing with various commercially available polishing cloths, a method of combining various commercially available abrasives (for example, diamond, alumina) and a buff. Specifically, when an abrasive is used, a method in which the abrasive used is changed from coarse particles to fine particles over time is preferably exemplified. In this case, the final polishing agent is preferably # 1500.

As the chemical polishing, for example, “Aluminum Handbook”, 6th edition, edited by Japan Aluminum Association, 2001, p. Examples thereof include various methods described in 164 to 165.
As chemical polishing, phosphoric acid-nitric acid method, Alupol I method, Alupol V method, Alcoa R5 method, H ₃ PO ₄ —CH ₃ COOH—Cu method, H ₃ PO ₄ —HNO ₃ —CH ₃ COOH method are also used. Preferably mentioned. Among these, the phosphoric acid-nitric acid method, the H ₃ PO ₄ —CH ₃ COOH—Cu method, and the H ₃ PO ₄ —HNO ₃ —CH ₃ COOH method are preferable.

  Examples of the electrolytic polishing include “Aluminum Handbook”, 6th edition, edited by Japan Aluminum Association, 2001, p. 164-165; various methods described in US Pat. No. 2,708,655; “Practical Surface Technology”, vol. 33, no. 3, 1986, p. The method described in 32-38;

  These methods can be used in combination as appropriate. Specifically, for example, a method of performing mechanical polishing in which the abrasive is changed from coarse particles to fine particles with time, and then performing electrolytic polishing is preferable.

[Anodizing treatment of aluminum substrate 18]
The anodizing treatment of the aluminum substrate 18 can be performed by a normal method.
For example, a self-ordering method can be used. The self-ordering method is a method for improving the regularity by utilizing the property that the micropores formed in the anodic oxide film are regularly arranged and removing a factor that disturbs the regular arrangement. Specifically, a high-purity aluminum substrate 18 is used, and an anodized film is formed at a low speed over a long period of time (for example, several hours to several tens of hours) at a voltage corresponding to the type of the electrolytic solution. In this method, since the pore diameter depends on the voltage, a desired pore diameter can be obtained to some extent by controlling the voltage.

Specifically, the anodizing treatment in the present invention can be performed by the following anodizing treatment (a-1). In addition to the anodizing treatment (a-1), the film removal treatment (a-2), It is preferable to perform re-anodizing treatment (a-3) together. The anodizing treatment (a-1), the film removal treatment (a-2), and the reanodizing treatment (a-3) may each be performed a plurality of times.
For example, it is preferable to repeat the anodization treatment (a-1) and the film removal treatment (a-2) several times in this order, and then perform the reanodization treatment (a-3). Further, the film removal treatment (a-2) may be performed after the reanodization treatment (a-3).

Anodizing treatment (a-1)
The anodizing treatment is a treatment in which an aluminum substrate 18 is used as an anode in an electrolyte solution to oxidize the substrate surface to form a porous aluminum oxide film on the surface.
As an example of the anodizing electrolyte solution, an electrolyte solution containing an organic acid is used. Examples of the organic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, maleic acid, itaconic acid, tartaric acid, malic acid, citric acid, glycolic acid, sulfamic acid, benzenesulfonic acid, amidosulfonic acid and the like. These acids can be used alone or in combination of two or more. Among these organic acids, oxalic acid, malonic acid, succinic acid, glutaric acid, maleic acid, itaconic acid, tartaric acid, malic acid, and citric acid are preferable, and oxalic acid is particularly preferable.

What is necessary is just to set the anodizing process conditions suitably according to the electrolyte solution to be used.
The anodizing conditions are generally as follows: electrolyte concentration (acid concentration): 0.01 to 5 mol / L, liquid temperature: −10 to 30 ° C., current density: 0.01 to 20 A / dm ² , voltage: It is preferable that they are 3-300V and electrolysis time: 0.5-30 hours. The anodizing treatment conditions were as follows: electrolytic solution concentration: 0.05 to 3 mol / L, liquid temperature: −5 to 25 ° C., current density: 0.05 to 15 A / dm ² , voltage: 5 to 250 V, electrolysis time: More preferably, it is 1 to 25 hours. Furthermore, the anodizing conditions were: electrolyte concentration: 0.1 to 1 mol / L, liquid temperature: 0 to 20 ° C., current density: 0.1 to 10 A / dm ² , voltage: 10 to 200 V, electrolysis time: 1 It is particularly preferred that it is ˜20 hours.

The average flow rate during the anodizing treatment is preferably 0.5 to 20.0 m / min, more preferably 1.0 to 15.0 m / min, and 2.0 to 10.0 m / min. Particularly preferred is min. By performing the anodic oxidation treatment at a flow rate in the above range, micropores having uniform and high regularity can be formed.
Moreover, the method of flowing the electrolytic solution is not particularly limited, but for example, a method using a general stirring device such as a stirrer is used. In particular, it is preferable to use a stirrer that can control the stirring speed by digital display because the average flow rate can be controlled. Examples of such a stirrer include “Magnetic Stirrer HS-50D (manufactured by AS ONE)” and the like.

  The anodizing treatment can be performed by changing the voltage intermittently or continuously in addition to being performed under a constant voltage. In this case, it is preferable to decrease the voltage sequentially. This makes it possible to reduce the resistance of the anodic oxide film, and fine micropores are generated in the anodic oxide film, which is preferable in terms of improving uniformity, particularly when sealing treatment is performed by electrodeposition. .

Film removal treatment (a-2)
The film removal process is a process for dissolving and removing the anodic oxide film formed on the surface of the aluminum base 18 by the anodic oxidation process. In the film removal process, the aluminum substrate 18 is not dissolved, but only the anodized film made of aluminum oxide (alumina) is dissolved.
Since the anodic oxide film becomes more regular as it is closer to the aluminum base material 18, the anodic oxide film is once removed by film removal treatment, and the bottom portion of the anodic oxide film remaining on the surface of the aluminum base material 18 is made the surface. It can be exposed to obtain regular depressions.

The film removal treatment is performed by bringing the aluminum substrate 18 on which the anodized film is formed into contact with the alumina solution. The alumina solution may be any solution that dissolves alumina and does not substantially dissolve aluminum.
An acid solution or an alkali solution can be used as the alumina solution. Specific examples of the alumina solution include aqueous solutions of acids such as sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid or mixtures thereof, and aqueous solutions of alkalis such as sodium hydroxide, potassium hydroxide, and lithium hydroxide. As the alumina solution, chromium compounds, zirconium compounds, titanium compounds, lithium salts, cerium salts, magnesium salts, sodium fluorosilicate, zinc fluoride, manganese compounds, molybdenum compounds, magnesium compounds, barium compounds, halogens alone An aqueous solution containing the above can also be used.

Specific examples of the chromium compound include chromium oxide (III) and chromium (VI) anhydride.
Examples of the zirconium-based compound include zircon ammonium fluoride, zirconium fluoride, and zirconium chloride.
Examples of the titanium compound include titanium oxide and titanium sulfide.
Examples of the lithium salt include lithium fluoride and lithium chloride.
Examples of the cerium salt include cerium fluoride and cerium chloride.
Examples of the magnesium salt include magnesium sulfide.
Examples of the manganese compound include sodium permanganate and calcium permanganate.
Examples of the molybdenum compound include sodium molybdate.
Examples of magnesium compounds include magnesium fluoride pentahydrate.
Examples of barium compounds include barium oxide, barium acetate, barium carbonate, barium chlorate, barium chloride, barium fluoride, barium iodide, barium lactate, barium oxalate, barium perchlorate, barium selenate, selenite. Examples thereof include barium, barium stearate, barium sulfite, barium titanate, barium hydroxide, barium nitrate, and hydrates thereof. Among the barium compounds, barium oxide, barium acetate, and barium carbonate are preferable, and barium oxide is particularly preferable.
Examples of halogen alone include chlorine, fluorine, and bromine.

Especially, it is preferable to use the aqueous solution containing an acid for the film removal process. Moreover, as an acid, a sulfuric acid, phosphoric acid, nitric acid, and hydrochloric acid are preferable.
The acid concentration of the acid aqueous solution is preferably 0.01 mol / L or more, more preferably 0.05 mol / L or more, and particularly preferably 0.1 mol / L or more. Although there is no particular upper limit, it is generally preferably 10 mol / L or less, more preferably 5 mol / L or less, and particularly preferably 1 mol / L or less. An unnecessarily high concentration is not economical, and if it is higher, the aluminum substrate 18 may be dissolved.

The temperature of the alumina solution is preferably −10 ° C. or higher, more preferably −5 ° C. or higher, and particularly preferably 0 ° C. or higher. In addition, since the starting point of ordering will be destroyed and disturb | disturbed if it processes using the boiling alumina solution, it is preferable to use without boiling.
When using an acid aqueous solution as an alumina solution, the temperature of the acid aqueous solution is preferably 20 to 60 ° C.

The method for bringing the aluminum substrate 18 on which the anodized film is formed into contact with the alumina solution is not particularly limited, and examples thereof include an immersion method and a spray method. Of these, the dipping method is preferred.
The dipping method is a process of immersing the aluminum base material 18 on which the anodized film is formed in an alumina solution. It is preferable to perform stirring during the dipping process because a uniform process is performed.
The time for the immersion treatment is preferably 8 to 120 minutes, more preferably 10 to 90 minutes, and particularly preferably 15 to 60 minutes.
The dissolution amount of the anodic oxide film is preferably 0.001 to 50% by mass of the whole anodic oxide film, more preferably 0.005 to 30% by mass, and 0.01 to 15% by mass. It is particularly preferred. When the dissolution amount is in the above range, the irregular portion of the surface of the anodic oxide film can be dissolved to increase the regularity of the micropore arrangement, and the anodic oxide film is formed at the bottom of the micropore. Thus, the starting point of the anodizing treatment performed in the re-anodizing treatment (a-3) can be left.

Re-anodizing treatment (a-3)
The anodic oxide film having a higher degree of ordering of micropores is obtained by removing the anodic oxide film by the film removal process and forming regular depressions on the surface of the aluminum base 18 and then performing the anodic oxidation process again. Can be formed.
The re-anodizing treatment can be performed by a normal method, but is preferably performed under the same conditions as the above-described anodizing treatment (a-1). When performing re-anodization treatment, the organic acid used as the electrolyte solution in re-anodization treatment also needs to be decomposed and removed by the annealing treatment described later. It is preferably the same as that used in a-1).
Also, a method of repeatedly turning on and off the current intermittently while keeping the DC voltage constant, and a method of repeatedly turning on and off the current while intermittently changing the DC voltage can be suitably used. According to these methods, fine micropores are generated in the anodic oxide film, which is preferable in terms of improving the uniformity of the pore diameter.

  When the re-anodizing treatment is performed at a low temperature, the arrangement of micropores becomes regular and the pore diameter becomes uniform. On the other hand, by performing the re-anodizing treatment at a relatively high temperature, the arrangement of the micropores can be disturbed, and the pore diameter variation can be within a predetermined range. Also, the pore diameter variation can be controlled by the processing time.

  By the method as described above, the anodic oxide film, that is, the insulating layer 20 can be formed on the aluminum substrate 18.

[Substrate annealing]
The aluminum base material 18 on which the insulating layer 20 is formed by anodic oxidation, that is, the substrate 12 is preferably subjected to an annealing treatment before the thermoelectric conversion element 14 is formed.
Prior to the annealing treatment, the substrate 12 may be cut into a desired size by a normal method such as dicing, laser processing, or a guillotine cutter.
For the annealing treatment, an electric furnace, a lamp annealing furnace, an oven, an inert oven, or the like can be used.

The annealing temperature is at least one of the boiling point, decomposition temperature, and sublimation temperature of the organic acid used in the anodizing electrolyte solution. The anodizing treatment here includes not only the above-described anodizing treatment (a-1) but also the reanodizing treatment (a-3). For example, as an organic acid in the electrolyte solution, (1) when oxalic acid is used, the sublimation temperature is 150 ° C. or higher, and (2) when malonic acid is used, the decomposition temperature is 134 ° C. or higher, (3) When succinic acid is used, annealing is performed at a temperature of 235 ° C. or higher, which is a boiling point, and (4) when glutaric acid is used, annealing is performed at a temperature of 302 ° C. or higher, which is a boiling point. When the electrolyte solution contains multiple organic acids, or when different organic acids are used in the electrolyte solution for anodizing treatment and re-anodizing treatment, the temperature exceeds the temperature at which all the organic acids used can be decomposed and sublimated. To do.
Further, in order to reduce the warpage and elongation of the substrate 12, it is preferable to anneal at a temperature higher than 250 ° C. to 350 ° C. which is the softening temperature of aluminum. In addition, as an upper limit of annealing treatment temperature, less than 400 degreeC which is the recrystallization temperature of aluminum is preferable. That is, the annealing temperature of the substrate 12 is preferably 134 ° C. or higher and lower than 400 ° C., more preferably 250 ° C. or higher and lower than 400 ° C., and further preferably 350 ° C. or higher and lower than 400 ° C. .

The annealing time is preferably 1 minute to 2 hours.
The atmosphere for performing the annealing treatment may be in the air or in an inert gas such as nitrogen or argon.

It is considered that the organic acid used in the electrolyte solution for the anodizing treatment is taken into the oxide film and remains in the substrate 12. After the anodizing treatment, the substrate is heated at a temperature equal to or higher than the boiling point, decomposition or sublimation temperature of the acid. By annealing, the acid residue remaining on the substrate can be removed.
Note that an acid solution may be used for pretreatment (eg, degreasing treatment) of the anodizing treatment or film removal treatment performed during or after the anodizing treatment. The acid used in these treatments is on the substrate 12. Therefore, it is considered that the thermoelectric conversion layer is not affected. Therefore, in the annealing treatment, it is only necessary to remove only the organic acid contained in the electrolyte solution used for the anodic oxidation.

[Organic acid decomposition treatment of substrate 12]
In the present invention, in order to make the decomposition and removal of the organic acid used in the anodic oxidation process more complete, the organic acid decomposition process of the substrate 12 may be performed in addition to the annealing process. By this treatment, the decomposition of the organic acid remaining on the substrate 12 after the anodization treatment can be promoted, and the adhesion of the thermoelectric conversion layer 28 and the like is improved by the cleaning effect on the surface of the substrate 12. As a result, it is possible to obtain the thermoelectric conversion module 10 that can further reduce cracks and cracks in the thermoelectric conversion layer 28 and that exhibits excellent thermoelectric conversion performance.

The organic acid decomposition treatment of the substrate 12 can be performed by corona treatment, UV ozone treatment, plasma treatment such as atmospheric pressure plasma treatment or low pressure plasma treatment, electron beam irradiation treatment, or the like. In the corona treatment and UV ozone treatment, the organic acid is decomposed by ozone or OH radical generated by discharge or ultraviolet irradiation. In the atmospheric pressure plasma treatment and the low pressure plasma treatment, a single or mixed gas composed of nitrogen, argon, helium, oxygen, hydrogen or the like is brought into a plasma state, and the organic acid is decomposed by ions, radicals, and electrons generated therefrom. In the electron beam irradiation, the organic acid is decomposed by the electron beam.
Specifically, the substrate 12 is subjected to corona treatment described in JP-A-57-11931, JP-A-5-339397, JP-A-10-67869, JP-A-11-169806, JP-A-2009. UV ozone treatment described in each publication such as JP-A-6262646, atmospheric pressure plasma treatment described in JP-A Nos. 2000-250017 and 2006-272319, JP-A No. 2001-237213, 2010- Low-pressure plasma treatment described in each publication such as 89014, and electron beam irradiation treatment described in each publication such as JP-A-5-74750 and JP-A-2004-53563 can be performed.
These treatments can be performed in the atmosphere, in an inert gas atmosphere, or in a vacuum depending on the treatment method.

  Such an organic acid decomposition treatment may be performed at any time before the thermoelectric conversion layer is formed on the substrate 12. For example, it can be performed before or after the annealing treatment of the aluminum substrate 18 on which the anodic oxide film (insulating layer 20) is formed, or simultaneously with the annealing treatment. Preferably, the decomposition process of the organic acid is performed after the annealing process of the substrate 12. In addition, the organic acid decomposition treatment step may be performed a plurality of times, for example, twice before and after the annealing treatment.

  The substrate 12 shown in FIGS. 1 and 2 has the insulating layer 20 on only one surface of the aluminum base 18. In the present invention, the substrate 12 has the insulating layer 20 on both sides of the aluminum base 18. You may have.

In the thermoelectric conversion module of the present invention, the substrate 12 is formed by laminating a metal base material, which is a plate material (sheet-like material) formed of a metal excluding aluminum, on the surface of the aluminum base material 18 where the insulating layer 20 is not formed. May be good.
That is, in the thermoelectric conversion module of the present invention, the substrate has an aluminum base 18 on the metal base 16 (surface) like the substrate 12a conceptually shown in FIG. The insulating layer 20 made of the anodized film of the aluminum substrate 18 may be provided on the material 18.
Or in the thermoelectric conversion module of this invention, the board | substrate has the aluminum base material 18 on both surfaces of the metal base material 16 like the board | substrate 12b shown conceptually in FIG.3 (B), and both aluminum base materials 18 are used. Further, an insulating layer 20 made of an anodic oxide film of the aluminum base 18 may be provided thereon. In such a configuration having the aluminum base 18 on both surfaces of the metal base 16, the insulating layer 20 may be formed only on one aluminum base 18.
By using the substrate having such a metal base material 16, the aluminum base material 18 or the insulating layer 20, that is, the substrate is deformed or damaged by heating the aluminum base material 18 or the insulating layer 20 with a high-temperature heat source. Therefore, a thermoelectric conversion module with higher heat resistance can be obtained.

The metal substrate 16 can be made of various metal materials. Preferably, those composed of steel, iron-based alloy, and Ti (including Ti alloy) are exemplified. The iron-based alloy means an alloy (special steel) whose main constituent element such as stainless steel is Fe.
More specifically, examples of the steel and iron-based alloy that can be used as the metal substrate 16 include carbon steel, austenitic stainless steel, ferritic stainless steel, 36 invar alloy, 42 invar alloy, and kovar alloy. . Further, Ti can be used as a Ti material that can be used as the metal base material 16, but is not limited to pure Ti, and Ti-6Al-4V and Ti-15V-3Cr-3Al-3Sn, which are alloys for extending. Etc. are also available.

In addition, when using the board | substrate which has the metal base material 16 in the thermoelectric conversion module of this invention, normally, the joining material which joined the metal base material 16 and the aluminum base material 18, what is called a clad material (clad steel) is used. Then, the anodizing treatment as described above is performed on the aluminum base 18 of the bonding material to form the insulating layer 20.
What is necessary is just to produce the joining material of the metal base material 16 and the aluminum base material 18 by well-known methods, such as joining by pressurization and joining by rolling. Moreover, the commercial item can also be utilized for the joining material which joined the metal base material 16 and the aluminum base material 18. FIG.

  In the thermoelectric conversion module 10 of the present invention, a silicon oxide layer or the like may be formed on the insulating layer 20 (anodized film) of the substrate 12, that is, on the surface on which the thermoelectric conversion element 14 is formed, if necessary. Good.

In the thermoelectric conversion module 10 of the present invention, the thickness of the substrate 12 (substrate 12a and substrate 12b) may be set as appropriate according to the size of the thermoelectric conversion module. According to the study by the present inventors, the thickness of the substrate 12 is preferably 120 μm or less, and more preferably 100 μm or less.
By setting the thickness of the substrate 12 to 120 μm or less, it is preferable in that the thermoelectric conversion module 10 having good flexibility can be obtained, heat can be prevented from accumulating on the substrate 12, and efficient power generation can be performed. .

  As described above, in the thermoelectric conversion module 10, the thermoelectric conversion element 14 includes the lower electrode 24, the lower adhesive layer 26, the thermoelectric conversion layer 28 including the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n, p And an upper electrode 30 connecting the n-type thermoelectric conversion layer 28n and the n-type thermoelectric conversion layer 28n.

A lower electrode 24 is formed on the insulating layer 20 (surface) of the substrate 12.
In one thermoelectric conversion element 14, two lower electrodes 24 are provided apart from each other. A lower adhesive layer 26 and a p-type thermoelectric conversion layer 28p are provided on one lower electrode 24, and a lower adhesive layer 26 and an n-type thermoelectric conversion layer 28n are provided on the other lower electrode.
Moreover, the thermoelectric conversion module 10 connects the lower electrode 24 in which the p-type thermoelectric conversion layer 28p is formed and the lower electrode 24 in which the n-type thermoelectric conversion layer 28n is formed in the adjacent thermoelectric conversion elements 14. The thermoelectric conversion elements 14 are connected in series. In other words, the thermoelectric conversion module 10 connects the thermoelectric conversion elements 14 in series by sharing the lower electrode 24 between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n in the adjacent thermoelectric conversion elements 14. ing.

As the lower electrode 24, various types of known materials used in π-type thermoelectric conversion elements can be used as long as they have sufficient conductivity and heat resistance.
Specifically, examples of the lower electrode 24 include those made of a metal material such as silver, gold, copper, nickel, and aluminum. A lower electrode 24 formed by coating a base material having sufficient heat resistance with such a metal material can also be used.

  Such a lower electrode 24 uses a method using a metal paste such as silver nanopaste (silver brazing), or a gas phase film forming method such as plasma CVD (Chemical Vapor Deposition), thermal CVD, CVD, sputtering, or vacuum deposition. What is necessary is just to form by a well-known method according to the formation material of the lower electrode 24, such as a method.

  What is necessary is just to set suitably the magnitude | size, thickness, shape, etc. of the lower electrode 24 according to the structure of the thermoelectric conversion module 10, the magnitude | size, shape, etc. of the thermoelectric conversion element 14. FIG.

An adhesion layer may be provided between the lower electrode 24 and the insulating layer 20 to improve the adhesion of the lower electrode 24 as necessary.
As the adhesion layer, various types of materials can be used depending on the forming material and the forming method of the lower electrode 24. For example, when the lower electrode 24 is formed by depositing gold by a vapor deposition method, a chromium layer or the like is exemplified as the adhesion layer. The adhesion layer may be formed by a known method such as a vacuum deposition method depending on the forming material.

  A lower adhesive layer 26 is formed on the lower electrode 24. The lower adhesive layer 26 adheres and fixes the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n to the lower electrode 24, and electrically connects the lower electrode 24 and the thermoelectric conversion layer.

  The lower adhesive layer 26 is formed of the lower electrode 24, the p-type thermoelectric conversion layer 28p, and the n-type thermoelectric conversion according to the formation material of the lower electrode 24 and the formation material of the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n. Any material made of various known materials can be used as long as it can adhere to the layer 28n and has sufficient conductivity and heat resistance.

  For example, the lower adhesive layer 26 is dispersed in the lower adhesive layer 26 formed by a metal paste such as a silver nano paste, a copper nano paste, a nickel nano paste, or a paste made of an alloy thereof, that is, a metal paste. The lower adhesive layer 26 made of a metal material (metal particles) is exemplified. The lower adhesive layer 26 may be made of solder or the like.

Among these, the lower adhesive layer 26 is preferably formed of silver nano paste or nickel nano paste, and particularly preferably formed of nickel nano paste. The lower adhesive layer 26 is preferably formed of nickel nano paste corresponding to both the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n. However, the lower adhesive layer 26 may be formed of nickel nano paste corresponding to only one of the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n.
Nickel has a very high melting point of 1455 ° C. (silver is 961 ° C.). Therefore, the thermoelectric conversion module 10 that can be used even at high temperatures can be obtained by forming the lower adhesive layer 26 using nickel nanopaste.

Further, it is known that silver nano-paste and nickel nano-paste are almost similar to physical properties of each bulk metal after firing.
Here, the temperature expansion coefficient (thermal expansion coefficient) of nickel is 13.3 ppm / K, and the temperature expansion coefficient of silver is 19.7 ppm / K. On the other hand, as will be shown later in Examples, the temperature expansion coefficient of the substrate 12 which is an aluminum material having an anodized film, the temperature expansion coefficient of a substrate 12a which is a clad material of stainless steel and an aluminum material having an anodized film, and The temperature expansion coefficient of the material used for the thermoelectric conversion layer is generally smaller than 13.3 ppm / K.
That is, nickel has a smaller difference in temperature expansion coefficient from the material for forming the substrate 12 and the thermoelectric conversion layer than silver. Therefore, by forming the lower adhesive layer 26 with nickel nanopaste, even if it is exposed to high temperatures to generate heat, the difference in thermal expansion between the materials forming the adjacent members such as the substrate 12 and the thermoelectric conversion layer Can be reduced. Therefore, by forming the lower adhesive layer 26 with nickel nanopaste, it is possible to suppress the occurrence of microcracks in the lower adhesive layer 26 due to the difference in thermal expansion, separation at the interface of each member, and the like. It is possible to prevent a decrease in output due to an increase in resistance.

In addition, the nickel nanopaste is (1) heated at a temperature of about 300 ° C. in an inert gas such as nitrogen gas or argon gas, or (2) reduced formic acid or hydrogen gas using a reflow apparatus. It can be fired by a known method such as heating in an atmosphere. Therefore, the lower adhesive layer 26 can be formed under a condition that the anodized aluminum material and the thermoelectric conversion layer used for the substrate 12 in the present invention can sufficiently withstand.
Furthermore, nickel is cheaper than silver, and the cost of the thermoelectric conversion module 10 can be reduced by using nickel nano paste as the lower adhesive layer 26.

The size, thickness, shape, etc. of the lower adhesive layer 26 are appropriately set according to the shape, size, etc. of the adhesive surface between the lower electrode 24 and the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n. That's fine.
When the lower electrode 24 is formed of a metal paste such as silver paste, the lower electrode 24 may also serve as the lower adhesive layer 26. That is, when the lower electrode 24 is formed of a metal paste such as silver paste, the lower adhesive layer 26 may not be provided.

In the thermoelectric conversion element 14, a p-type thermoelectric conversion layer 28 p is bonded and fixed on the lower adhesive layer 26 on the one lower electrode 24. On the lower adhesive layer 26 on the other lower electrode 24, an n-type thermoelectric conversion layer 28n is bonded and fixed.
The p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n constitute a thermoelectric conversion layer 28. The thermoelectric conversion layer 28 generates electric power according to the temperature difference when a temperature difference occurs between the substrate 12 side and the upper electrode 30 side.
In the thermoelectric conversion module 10, p-type thermoelectric conversion layers 28 p and n-type thermoelectric conversion layers 28 n of the thermoelectric conversion elements 14 are alternately arranged on the substrate 12. Further, as described above, in the thermoelectric conversion module 10, in the adjacent thermoelectric conversion element 14, the p-type thermoelectric conversion layer 28 p and the n-type thermoelectric conversion layer 28 n share the lower electrode 24. Connected in series.

The p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n may be made of various known p-type thermoelectric conversion materials and n-type thermoelectric conversion materials as long as they have sufficient heat resistance.
Here, in consideration of heat resistance against a high-temperature heat source exceeding 300 ° C., an inorganic material is preferably used as the thermoelectric conversion material. Specifically, silicon-germanium material, cobalt-antimony material, zinc-antimony material, aluminum-manganese-silicon material, silver-antimony-germanium-tellurium material, strontium titanium oxide, sodium cobalt oxide, oxidation Examples include those made of a material obtained by doping a p-type or n-type thermoelectric conversion material such as calcium cobalt, zinc oxide, or silicide-based material.
Among them, materials that are doped with p-type or n-type silicide materials such as manganese silicide, magnesium silicide, iron silicide, etc. in that they are inexpensive, have high safety, and can be used for versatile materials. Preferably used. In particular, a material obtained by doping iron silicide into p-type or n-type is preferably used.

Such p-type thermoelectric conversion layer 28p and n-type thermoelectric conversion layer 28n may be formed by a known method according to the forming material.
In addition, the size, shape, and the like of the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n may be appropriately set according to the configuration of the thermoelectric conversion module 10, the size, shape, and the like of the thermoelectric conversion element 14.

By the way, in general, a thermoelectric conversion module using the π-type thermoelectric conversion element 14 is used by contacting the substrate 12 side with a heat source.
Therefore, in the thermoelectric conversion module 10, the substrate 12, the lower electrode 24 close to the substrate 12, the lower adhesive layer 26, the p-type thermoelectric conversion layer 28p, the n-type thermoelectric conversion layer 28n, and the like are easily heated. Therefore, if the difference in the coefficient of thermal expansion of these members is large, cracks in the lower adhesive layer 26 are generated due to thermal expansion due to heating, the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n are peeled off, etc. May occur.
Considering this point, it is preferable that the temperature expansion coefficients of the substrate 12, the lower electrode 24, the lower adhesive layer 26, the p-type thermoelectric conversion layer 28p, and the n-type thermoelectric conversion layer 28n are small in difference. In this respect, as described above, it is preferable to form the lower adhesive layer 26 using a nickel nano paste.

The thermoelectric conversion element 14 in the illustrated example has an air layer between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n as a preferred mode.
The thermoelectric conversion element 14 insulates the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n by this air layer, and is unnecessary for the p-type thermoelectric conversion layer 28p and the n-type thermoelectric other than the connection by the upper electrode 30. The conversion layer 28n is prevented from being connected.
Further, by insulating the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n with an air layer, it is possible to easily mount the upper electrode 30 having a later-described bending, and further, the flexibility of the thermoelectric conversion module 10 is improved. Improvement, weight reduction, simplification of the configuration of the thermoelectric conversion element 14 and the like can also be achieved.

The illustrated thermoelectric conversion module 10 is also an air layer between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n of the adjacent thermoelectric conversion elements 14.
The thermoelectric conversion module 10 prevents the adjacent thermoelectric conversion elements 14 from being unnecessarily connected in addition to the connection by the lower electrode 24 by insulating the adjacent thermoelectric conversion elements 14 by the air layer.
Further, by insulating the adjacent thermoelectric conversion elements 14 with an air layer, it is possible to improve the flexibility and weight of the thermoelectric conversion module 10, simplify the configuration of the thermoelectric conversion module 10, and the like.

  The thermoelectric conversion module of the present invention is not limited to this configuration, and an adhesive having sufficient heat resistance between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n in the thermoelectric conversion element 14 or the like. An insulating layer made of may be formed.

  In the thermoelectric conversion element 14, the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n are connected to each other by the upper electrode 30 on the upper surface in the same manner as a normal π-type thermoelectric conversion element. In the illustrated example, the upper electrode 30 is bonded to the upper surface of the p-type thermoelectric conversion layer 28p and the upper surface of the n-type thermoelectric conversion layer 28n by the upper adhesive layer 32.

The upper electrode 30 may be made of various materials used in π-type thermoelectric conversion elements as long as it has sufficient conductivity and heat resistance. Specifically, the upper electrode 30 is made of a metal material such as gold, silver, copper, nickel, or an alloy thereof.
As will be described later, in the thermoelectric conversion module 10 of the present invention, the substrate 12 including the aluminum base 18 and the insulating layer 20 obtained by anodizing the aluminum base 18 is used, and the upper electrode 30 has flexibility. In addition, the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n are connected with bending to realize the thermoelectric conversion module 10 having excellent flexibility and heat resistance. Considering this point, the upper electrode 30 is preferably formed of a metal foil made of these metal materials.

The upper adhesive layer 32 is formed of the upper electrode 30, the p-type thermoelectric conversion layer 28p, and the n-type according to the formation material of the upper electrode 30, and the formation material of the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n. Any material can be used as long as it can adhere to the thermoelectric conversion layer 28n and has sufficient conductivity and heat resistance.
Examples of the upper adhesive layer 32 include, as an example, the upper adhesive layer 32 formed of a metal paste such as silver nano paste or nickel nano paste, solder, conductive adhesive, and the like exemplified in the lower adhesive layer 26. The thing of is illustrated.
Among these, for the same reason as the lower adhesive layer 26 described above, the upper adhesive layer 32 formed using nickel nanopaste is suitable. The upper adhesive layer 32 is preferably formed of nickel nano paste corresponding to both thermoelectric conversion layers, but may be formed of nickel nano paste corresponding to only one of the lower adhesive layers. Similar to layer 26.

  As described above, the upper electrode 30 side becomes the cooling side when the thermoelectric conversion module 10 is used. Therefore, the upper electrode 30 and the upper adhesive layer 32 do not require high heat resistance like the lower electrode 24 and the lower adhesive layer 26.

The size, thickness, shape, etc. of the upper adhesive layer 32 are appropriately set according to the shape, size, etc. of the adhesive surface between the upper electrode 30 and the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n. That's fine.
The upper electrode 30 and the upper adhesive layer 32 may be formed by a known method according to the forming material.

Here, in the thermoelectric conversion module 10 of the present invention, the upper electrode 30 that connects the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n of the thermoelectric conversion element 14 has flexibility and bends. In this state, the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n are connected.
The thermoelectric conversion module 10 of the present invention includes a flexible substrate having an aluminum base 18 and an insulating layer 20 made of an anodized aluminum film formed by anodizing the surface of the aluminum base 18. 12 is used.
The thermoelectric conversion module 10 of the present invention has such a configuration, and thus has excellent flexibility (flexibility) and excellent heat resistance that enables use in a high-temperature heat source exceeding 300 ° C. Is realized.

As shown in Patent Document 2 and Patent Document 3 described above, the conventional flexible thermoelectric conversion module uses a resin material for a substrate or wiring in order to achieve good flexibility. Therefore, it is difficult to stably use a conventional thermoelectric conversion module having flexibility with respect to a heat source having a high temperature exceeding 300 ° C.
On the other hand, in the thermoelectric conversion module of the present invention, a flexible substrate 12 having an aluminum base 18 and an insulating layer 20 made of an anodized aluminum film is used. Aluminum is a metal, and an anodic oxide film (aluminum oxide) of aluminum has a very high heat resistance compared to a resin material or the like.
Therefore, the thermoelectric conversion module 10 of the present invention can prevent the substrate 12 from being damaged by heat even when used in a heat source having a high temperature exceeding 300 ° C.

  However, in a thermoelectric conversion module, sufficient heat resistance and a high-temperature heat source can be obtained by using a flexible and highly heat-resistant substrate and forming each member with a material having high heat resistance. It is not possible to realize sufficient flexibility corresponding to the above.

The thermoelectric conversion module 10 of the present invention has good flexibility, and is therefore mounted on a curved surface such as a pipe. Preferably, the thermoelectric conversion module 10 of the present invention is mounted on a curved surface having a radius of curvature of 30 mm or more by taking advantage of its good flexibility.
Here, as described above, the thermoelectric conversion module 10 is mounted on the heat source with the substrate 12 facing the heat source. Therefore, when mounted on a curved heat source, as conceptually shown in FIG. 4, the distance between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n increases on the upper electrode 30 side.
Therefore, if the length of the upper electrode 30 between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n is only an interval between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n, the thermoelectric conversion When the module 10 is mounted on a curved surface, the upper electrode 30 may be broken or the upper electrode 30 may be peeled off from either the p-type thermoelectric conversion layer 28p or the n-type thermoelectric conversion layer 28n.

On the other hand, the thermoelectric conversion module 10 is curved by connecting the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n in a state where the upper electrode 30 has flexibility and is bent. Even when the distance between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n is widened, the deflection of the upper electrode 30 absorbs this spread as shown in FIG. Breakage of the upper electrode 30 and peeling from the thermoelectric conversion layer can be prevented.
Moreover, according to this configuration, it is not necessary to form the upper electrode 30 with a special resin composition having stretchability and conductivity.

Moreover, although it is small compared with the board | substrate 12, the lower electrode 24, the lower adhesive layer 26, etc. which are close to a heat source, when the thermoelectric conversion module 10 is mounted | worn with a high temperature heat source, the upper electrode 30 is also by heat of a heat source. It expands thermally and repeats returning to its original length due to a temperature drop of the heat source.
If the length of the upper electrode 30 is only the distance between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n, the upper electrode 30 is tensioned when the thermoelectric conversion module 10 is mounted on a curved surface. It becomes a state. Repeated thermal expansion and contraction in a tensioned state is a heavy burden on the upper electrode 30, and even if the upper electrode 30 is formed of a stretchable material, it may cause disconnection or peeling of the upper electrode 30. Become.
On the other hand, by making the upper electrode 30 flexible and having a bend, even when the thermoelectric conversion module 10 is mounted on a high-temperature curved surface, it is applied to the upper electrode 30 by repeated thermal expansion and contraction. The load can be greatly reduced, and disconnection and peeling of the upper electrode 30 can be prevented. That is, not only the flexibility of the thermoelectric conversion module but also the heat resistance of the thermoelectric conversion module can be improved by making the upper electrode 30 flexible to bend.

  Therefore, according to this invention, the thermoelectric conversion module 10 which implement | achieved sufficient heat resistance corresponding to a high temperature heat source and sufficient flexibility is obtained.

The length of the upper electrode 30 between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n depends on the curvature radius of the curved surface on which the thermoelectric conversion module 10 is assumed to be mounted, etc. What is necessary is just to set suitably the length which can prevent the fracture | rupture of this, etc. reliably.
In addition, the length of the upper electrode 30 between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n is, in other words, the upper electrode in a region not in contact with the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n. 30, that is, in the illustrated example, the length of the upper electrode 30 excluding the bonding portion between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n.

Here, according to the study by the present inventors, the radius of curvature of the curved surface on which the thermoelectric conversion module 10 is mounted is L [mm], and the height of the thermoelectric conversion layer 28 of the thermoelectric conversion element 14 is a [mm], p When the distance between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n is b [mm], the length c [mm] of the upper electrode between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n ]But,
b + (ab / L) <c and c <(4a ² + b ² ) ^1/2
It is preferable to satisfy.
The height a of the thermoelectric conversion layer 28 is the height including the lower electrode 24 and the lower adhesive layer 26, that is, the height from the surface of the insulating layer 20 to the upper end of the thermoelectric conversion layer 28. When the height is not uniform at the upper part (upper surface) of the p-type thermoelectric conversion layer 28p and / or the n-type thermoelectric conversion layer 28n, the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n face each other. The height to the upper end of the surface to be performed is defined as the height a of the thermoelectric conversion layer 28.

When the length c of the upper electrode 30 satisfies “b + (ab / L) <c”, even when the thermoelectric conversion module 10 is mounted on a curved surface having a small radius of curvature, the deflection of the upper electrode 30 has a margin. Thus, the spread of the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n can be absorbed, and breakage of the upper electrode 30 can be prevented more reliably.
When the upper electrode 30 contacts the insulating layer 20, the upper electrode 30 contacts the p-type thermoelectric conversion layer 28p, the n-type thermoelectric conversion layer 28n, the lower electrode 24, the lower adhesive layer 26, etc. May cause instability. On the other hand, when the length of the upper electrode 30 satisfies “c <(4a ² + b ² ) ^1/2 ”, the upper electrode 30 is prevented from becoming unnecessarily long and coming into contact with the insulating layer 20. Thus, stable power generation can be performed.

The thermoelectric conversion module 10 of the present invention preferably covers all the thermoelectric conversion elements 14 and has a flexible protective layer. Thereby, damage to the thermoelectric conversion element 14 can be prevented and durability of the thermoelectric conversion module can be improved.
As the protective layer, various sheets can be used as long as they have sufficient heat resistance and flexibility and can ensure insulation with respect to the upper electrode 30, the p-type thermoelectric conversion layer 28p, and the n-type thermoelectric conversion layer 28n. Things are available. Moreover, as a protective layer, Preferably, the sheet | seat (heat conductive sheet) which has favorable heat conductivity is utilized.
Specifically, as the protective layer, a graphite sheet on which an insulating layer similar to the substrate 12 is formed, a metal sheet on which an insulating layer such as an aluminum sheet having an anodized film is formed, a silicone resin sheet, a heat-resistant aramid film, etc. A resin film etc. are illustrated. In addition, a metal sheet such as an aluminum sheet having an anodized film may have a backing layer such as a stainless steel layer as necessary.

Moreover, even if the thermoelectric conversion module 10 of this invention has the adhesion layer for sticking the thermoelectric conversion module 10 on the surface on the opposite side to the formation surface of the thermoelectric conversion element 14 of the board | substrate 12 to a heat source. Good. Hereinafter, the surface of the substrate 12 opposite to the surface on which the thermoelectric conversion elements 14 are formed is also referred to as “back surface”.
By having a bonding adhesive layer on the back surface of the substrate 12, the thermoelectric conversion module 10 is securely adhered to a heat source, efficient power generation becomes possible, and the thermoelectric conversion module 10 is simply attached to a curved surface such as a pipe. It becomes possible to install.

As the adhesive layer for sticking, various known materials can be used as long as they have sufficient heat resistance and flexibility. For example, a commercially available heat conductive adhesive sheet or a heat conductive adhesive can be used. it can.
As an example of the heat conductive adhesive sheet, TC-50TXS2 manufactured by Shin-Etsu Silicone Co., Ltd., Hypersoft heat dissipation material 5580H manufactured by Sumitomo 3M Co., Ltd., BFG20A manufactured by Denki Kagaku Kogyo Co., Ltd., TR5912F manufactured by Nitto Denko Corporation, etc. can be used. . In addition, the heat conductive adhesive sheet which consists of silicone type adhesives from a heat resistant viewpoint is preferable. On the other hand, examples of the thermally conductive adhesive include Scotch Weld EW 2070 manufactured by 3M, TA-01 manufactured by Inex, TCA-4105, TCA-4210, HY-910 manufactured by Cima Electronics, and Satsuma Research Institute. SST2-RSMZ, SST2-RSCSZ, R3CSZ, R3MZ, etc. made from manufacture can be used.
In addition, when the temperature of the assumed heat source is high and the heat resistance is insufficient with these heat conductive adhesive sheets and heat conductive adhesives, without using the heat conductive adhesive sheet or the heat conductive adhesive, What is necessary is just to attach the thermoelectric conversion module 10 to a heat source using a volt | bolt / nut, a metal member, etc.

  In addition, the thermoelectric conversion module of the present invention has an insulating film such as an aramid film attached so as to cover the above-described protective layer or all the thermoelectric conversion elements 14, and a cooling fin such as an aluminum fin thereon. May be laminated.

  The thermoelectric conversion module 10 of the present invention can be basically manufactured according to the manufacture of a thermoelectric conversion module using a π-type thermoelectric conversion element. The following method is illustrated as an example.

  First, a substrate 12 is prepared in which an aluminum anodic oxide film is formed as an insulating layer 20 on an aluminum base 18 obtained by anodizing the surface of the aluminum base 18 as described above.

On the insulating layer 20 of the substrate 12, a rectangular adhesive layer is formed in a pattern as shown in FIG. 5A, which is arranged at equal intervals in two orthogonal directions, and on this adhesive layer. The lower electrode 24 (shaded line) is formed in the same pattern. Note that, as shown in FIG. 5A, the lower electrodes 24 are arranged with the longitudinal direction aligned with the horizontal direction in the figure.
Here, the lower electrode 24 at the left end in the uppermost row and the lowermost row also serves as a lead electrode for taking out the electric power generated by the thermoelectric conversion module 10. Therefore, the lower electrode 24 is longer in the horizontal direction in the figure than the other lower electrodes.
In the following description, “in the drawing” is omitted, and is simply expressed as “vertical and horizontal”, “up and down”, and “left and right”.

Next, as shown in FIG. 5B, two lower adhesive layers 26 (fine dots) are formed on each lower electrode 24 in a pattern that is spaced apart in the horizontal direction. As shown in FIG. 5B, a lower adhesive layer 26 is formed only on the right end of the lower electrode 24 that also serves as an extraction electrode.
Next, on the lower adhesive layer 26, a p-type thermoelectric conversion layer 28p (white) and an n-type thermoelectric conversion layer 28n (black coating) are arranged in both the vertical and horizontal directions as shown in FIG. The p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n are bonded to the lower electrode 24 by placing them alternately and performing heat treatment or baking treatment as necessary.
Next, as shown in FIG. 5D, the upper adhesive layer 32 (fine dots) is formed on the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n.

  Further, as shown in FIG. 5E, the upper electrode 30 (coarse) is connected to the upper adhesive layer 32 so as to connect the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n that are not connected by the lower electrode 24. The upper electrode 30 is adhered and connected to the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n by placing a dot) and performing heat treatment or baking treatment as necessary, and the thermoelectric conversion element 14 Is made.

Here, as described above, the upper electrode 30 is made of metal foil and has flexibility, and the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n are connected with bending. To do.
Preferably, the curvature radius L of the curved surface on which the thermoelectric conversion module 10 is mounted, the height a of the thermoelectric conversion layer 28, the interval b between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n, and the p-type thermoelectric conversion The length c of the upper electrode between the layer 28p and the n-type thermoelectric conversion layer 28n is
b + (ab / L) <c and c <(4a ² + b ² ) ^1/2
The upper electrode 30 connects the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n so as to satisfy the above.

In the illustrated example, as shown in FIG. 5E, the lateral direction includes a p-type thermoelectric conversion layer 28p and an n-type thermoelectric conversion layer 28n that are adjacent to each other in the lateral direction and are not connected by the lower electrode 24. The upper electrode 30 is connected.
Further, the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n adjacent in the vertical direction are connected by the upper electrode 30 at the end in the horizontal direction. Here, as shown in FIG. 5E, the vertical connection is made so that the left end and the right end are staggered one by one.
As a result, the thermoelectric conversion module of the present invention is produced, in which a plurality of thermoelectric conversion elements arranged two-dimensionally are connected in series so that one line is folded a plurality of times.

In the illustrated example, a lower adhesive layer 26 is provided on the lower electrode 24, and a p-type thermoelectric conversion layer 28p and an n-type thermoelectric conversion layer 28n are placed thereon and bonded.
However, the present invention is not limited to this, and when the lower electrode 24 is formed of a metal paste such as silver paste, the adhesive layer is formed by causing the metal paste to be the lower electrode 24 to act as an adhesive. As described above, the p-type thermoelectric conversion layer 28p and the like may be directly bonded to the lower electrode 24 without doing so. This is the same for the upper electrode 30.

The vehicle exhaust pipe of the present invention is obtained by mounting the thermoelectric conversion module 10 of the present invention on the outer surface of an exhaust pipe mounted on a vehicle such as a motorcycle or an automobile, with the back surface inside.
As is well known, the exhaust pipe becomes hottest while the vehicle is running. Further, during traveling of the vehicle, the upper electrode 30 side serving as a cooling side is air-cooled by wind generated by traveling of the vehicle. Therefore, according to such an exhaust pipe for a vehicle of the present invention, the thermoelectric conversion module 10 is not provided with heat radiation fins or the like, and the substrate 12 side of the thermoelectric conversion module 10 on the heat source side and the upper electrode on the cooling side. A large temperature difference is provided on the 30 side, and a large amount of power generated by the thermoelectric conversion module 10 is obtained.

  In addition, the exhaust pipe for vehicles of this invention includes what attached the thermoelectric conversion module 10 of this invention to the catalyzer (exhaust gas purification apparatus) and the muffler (silencer / silencer).

  As described above, the thermoelectric conversion module and the vehicle exhaust pipe of the present invention have been described in detail. However, the present invention is not limited to the above-described example, and various improvements and modifications are made without departing from the gist of the present invention. Of course, it's also good.

  Hereinafter, the thermoelectric conversion module of the present invention will be described in more detail with reference to specific examples of the present invention. However, the present invention is not limited to the following examples.

[Example 1]
<Fabrication of first substrate>
(A) Pretreatment (electropolishing)
A high-purity aluminum substrate (manufactured by Sumitomo Metals Co., Ltd., purity 99.99% by mass, thickness 100 μm) was cut so as to be anodized in an area of 10 cm square, and an electropolishing liquid having the following composition was used, and a voltage of 25 V, Electropolishing was performed under conditions of a liquid temperature of 65 ° C. and a liquid flow rate of 3.0 m / min.
The cathode was a carbon electrode, and the power source was GP0110-30R (manufactured by Takasago Seisakusho). The flow rate of the electrolytic solution was measured using a vortex flow monitor FLM22-10PCW (manufactured by AS ONE).
<< Composition of electrolytic polishing liquid >>
85% by mass phosphoric acid (reagent manufactured by Wako Pure Chemical Industries, Ltd.) 660 ml
160ml of pure water
150ml sulfuric acid
Ethylene glycol 30ml

(B) Anodizing treatment (treatment liquid: oxalic acid (sublimation temperature 150 ° C.))
An electrolytically polished aluminum substrate was anodized with 0.50 mol / L (liter) oxalic acid electrolyte at a voltage of 40 V, a liquid temperature of 15 ° C., and a liquid flow rate of 3.0 ml / min for 1 hour. Was given. Further, the substrate after the anodizing treatment was immersed in a mixed solution of 0.5 mol / L phosphoric acid for 25 minutes at 40 ° C. to perform film removal treatment. The above process was repeated 4 times in this order.
Thereafter, the substrate was reanodized with an electrolyte of 0.50 mol / L oxalic acid for 4 hours under the conditions of a voltage of 40 V, a liquid temperature of 15 ° C., and a liquid flow rate of 3.0 ml / min. Further, using a mixed aqueous solution of 0.5 mol / L phosphoric acid, it was immersed for 25 minutes at 40 ° C. for film removal treatment, and micropores were arranged in a straight tubular and honeycomb shape on the surface of the aluminum substrate. An anodic oxide film having a thickness of 10 μm was formed.
In both the anodizing treatment and the re-anodizing treatment, a stainless steel electrode was used as the cathode and GP0110-30R (manufactured by Takasago Seisakusho) was used as the power source. Moreover, NeoCool BD36 (made by Yamato Kagaku) was used for the cooling device, and Pear Stirrer PS100 (made by EYELA) was used for the stirring and heating device. The flow rate of the electrolyte was measured using a vortex flow monitor FKM22-10PCW (AS ONE).

(C) Annealing treatment The aluminum substrate on which the anodized film was formed was cut by a dicing method, annealed in an electric furnace at 350 ° C. for 2 hours, and then cooled to room temperature in the electric furnace.
Thereby, the 1st board | substrate which has the aluminum base material 18 and the insulating layer 20 which consists of an anodic oxide film of aluminum as the board | substrate 12 was produced. The thickness of the aluminum substrate 18 was 90 μm, and the thickness of the insulating layer 20 was 10 μm.

<Production of thermoelectric conversion module>
In the same manner as the example shown in FIGS. 5A to 5E, the thermoelectric conversion element 14 was formed on the insulating layer 20 of the substrate 12 to produce a thermoelectric conversion module.
(A) Formation of Lower Electrode A 50 nm thick chromium layer was formed in the pattern shown in FIG. 5A as an adhesion layer on the first substrate by a vacuum deposition method using a metal mask. Next, a rectangular lower electrode 24 (hatched line) made of gold having a thickness of 500 nm was formed by a vacuum deposition method using a metal mask with a pattern shown in FIG. 5A in which two orthogonal directions were arranged at equal intervals. .

(B) Formation of lower adhesive layer, p-type thermoelectric conversion layer, and n-type thermoelectric conversion layer Silver nano paste (fine dots) to be the lower adhesive layer 26 on the lower electrode 24 in the pattern shown in FIG. Was applied in a thickness of about 30 μm.
Next, on the silver nanopaste, the p-type thermoelectric conversion layer 28p (outlined) and the n-type thermoelectric conversion layer 28n (blacked out) are respectively placed as shown in FIG. 5C. did.
The p-type thermoelectric conversion layer 28p is made of a manganese silicide-based material, the n-type thermoelectric conversion layer 28n is made of a magnesium silicide-based material, and the size thereof is 2 mm × 1.5 mm × 1.5 mm. (Vertical × horizontal × height).
Further, the silver nanopaste was baked, and the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n were bonded to the lower adhesive layer 26 made of silver.
The thickness of the adhesion layer and the lower adhesive layer 26 after firing is extremely small compared to the height of the thermoelectric conversion layer 28 of 1.5 mm, and is negligible. Therefore, the height a of the thermoelectric conversion layer 28 in the thermoelectric conversion element 14 can be regarded as 1.5 mm. The interval b between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n in each thermoelectric conversion element 14 was 1.0 mm.

(C) Formation of Upper Electrode As shown in FIG. 5D, a silver nanopaste to be the upper adhesive layer 32 is formed on the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n with a thickness of about 30 μm. Applied.
Further, as shown in FIG. 5E, a copper foil having a thickness of 18 μm is attached to the silver nano paste as the upper electrode 30, and the silver nano paste is baked to form the upper electrode 30 in the p-type thermoelectric conversion layers 28p and n. The thermoelectric conversion module 10 in which 59 thermoelectric conversion elements 14 were connected in series was bonded to the thermoelectric conversion layer 28n.
Note that the length c of the upper electrode 30 between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n was 1.5 mm. Therefore, the upper electrode 30 connects the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n in a state of being bent.

[Example 2]
<Production of second substrate>
A clad material was prepared by laminating and integrating a 30 μm thick aluminum plate (purity 99.99%) on both surfaces of a 50 μm thick SUS430 plate.
An aluminum substrate was prepared in the same manner as in the production of the first substrate of Example 1, except that this clad material was used instead of a high purity aluminum substrate (manufactured by Sumitomo Metals, purity 99.99 mass%, thickness 100 μm). An insulating layer 20 made of an anodic oxide film of aluminum was formed on the surface of the material 18, and a substrate 12b as shown in FIG. 3B was produced as a second substrate. That is, this second substrate has a 20 μm thick aluminum substrate 18 on both surfaces of a 50 μm thick SUS430 metal substrate 16, and an insulating layer 10 μm thick on both aluminum substrates 18. 20 having a thickness of 110 μm.
<Production of thermoelectric conversion module>
A thermoelectric conversion module was produced by forming the thermoelectric conversion element 14 on the insulating layer 20 on one surface in the same manner as in Example 1 except that this second substrate was used instead of the first substrate. .

[Example 3]
A thermoelectric conversion module was produced in the same manner as in Example 1 except that the length c of the upper electrode between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n was 1.05 mm.

[Example 4]
A thermoelectric conversion module was produced in the same manner as in Example 2 except that the lower adhesive layer 26 and the upper adhesive layer 32 were formed of nickel nano paste instead of silver nano paste.

[Comparative Example 1]
<Preparation of substrate>
A double-sided copper-clad polyimide substrate having a copper thickness of 18 μm and a polyimide thickness of 25 μm was prepared.
<Production of thermoelectric conversion module>
A thermoelectric conversion module was produced by forming the thermoelectric conversion element 14 on one surface of the substrate in the same manner as in Example 1 except that this double-sided copper-clad polyimide substrate was used instead of the first substrate. The lower electrode 24 was formed by pattern etching of a copper foil so as to have the same pattern as in FIG. That is, in this example, the polyimide film also acts as an insulating layer.

[Comparative Example 2]
The length c of the upper electrode between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n is made the same as the distance b between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n of the thermoelectric conversion element. A thermoelectric conversion module was produced in the same manner as Example 1 except for the above.
That is, in this thermoelectric conversion module, the upper electrode of the thermoelectric conversion element is not bent.

[Heat resistance evaluation]
Regarding each of the thermoelectric conversion modules of Examples 1 to 4 and Comparative Examples 1 and 2 produced in this manner, the thermoelectric conversion elements 14 were covered and the upper electrode 30 was covered with a thickness of about 1 mm for insulation. A 4 μm heat-resistant aramid film was bonded.
Furthermore, each thermoelectric conversion module was wound around a pipe-shaped heater having a diameter of 40 mm with the substrate side facing inside, and aluminum fins for air cooling were laminated on the aramid film.

As described above, in Examples 1, 2 and 4, and Comparative Example 1, the height a of the thermoelectric conversion element 14 is about 1.5 mm, and the distance b between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n is The length c of the upper electrode 30 between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n is 1.5 mm.
Moreover, the diameter of the pipe-shaped heater around which the thermoelectric conversion module is wound is 40 mm. Accordingly, the curvature radius L of the curved surface around which the module is wound is 20 mm.
Therefore, Examples 1, 2, and 4 and Comparative Example 1 have c = 1.5,
b + (ab / L) = 1 + ([1.5 × 1.0] / 20) = 1.075, and
Since (4a ² + b ² ) ^1/2 = (4 × 1.5 ² +1.0 ² ) ^1/2 = 3.16,
b + (ab / L) <c and c <(4a ² + b ² ) ^1/2
Meet.
On the other hand, Example 3 is different from Example 1 only in that the length c of the upper electrode 30 between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n is 1.05 mm.
Therefore, the upper electrode 30 between the p-type thermoelectric conversion layer 28p and the n-type thermoelectric conversion layer 28n is bent and satisfies c <(4a ² + b ² ) ^1/2 , but b + (ab / L ) <C is not satisfied.
In Comparative Example 2, the upper electrode has no deflection.

In this state, the surface temperature of the pipe-shaped heater was heated to 200 ° C.
A lead electrode and a source meter (source meter 2450, manufactured by Keithley) were connected, open circuit voltage and short circuit current were measured, and the amount of power generation was determined from the following formula.
(Power generation amount) = 0.25 × (open circuit voltage) × (short circuit current)
This power generation was measured immediately after reaching 200 ° C. and 1 hour later. Further, the same measurement was performed with the surface temperature of the pipe-shaped heater being 300 ° C. and 400 ° C.
Table 1 below shows the power generation [mW] of each thermoelectric conversion module.

As shown in Table 1, the thermoelectric conversion modules of Example 1 and Example 3 using a substrate 12 having high heat resistance composed of an aluminum base 18 and an insulating layer 20 made of an aluminum anodic oxide film are polyimide substrates. Compared with the thermoelectric conversion module of the comparative example 1 using this, the electric power generation amount is high. Furthermore, there is little drop in the amount of power generated after 1 hour.
This is because the thermoelectric conversion module of Comparative Example 1 using polyimide for the substrate uses the substrate 12 with high heat resistance, whereas the substrate is deformed by heating and the amount of power generation is reduced due to the deformation of the substrate. The thermoelectric conversion module of the present invention is considered to be because the deformation of the substrate is small even with a high-temperature heat source. In Comparative Example 1, it was considered that the wiring was disconnected due to the deformation of the substrate at 400 ° C., and the amount of power generation could not be measured.
The thermoelectric conversion modules of Example 2 and Example 4 have a higher power generation amount than the thermoelectric conversion modules of Example 1 and Example 3, and there is less drop in the power generation amount after 1 hour at 300 ° C. or higher. This is presumably because Example 2 and Example 4 use a clad material in which stainless steel plates are laminated as a substrate, so that the substrate is less deformed than Example 1 and Example 3.
On the other hand, in Comparative Example 2 in which the upper electrode was not bent, it was considered that the upper electrode was disconnected due to being attached to the pipe-shaped heater, and the amount of power generation could not be measured.

[Heat cycle test]
For the thermoelectric conversion modules of Examples 1 to 4 and Comparative Example 1 and Comparative Example 2, the surface temperature of the pipe-shaped heater was heated to 400 ° C. and maintained for 1 hour in the same manner as in the previous heat resistance evaluation. The surface temperature of the pipe-shaped heater is lowered to 50 ° C. over 30 minutes and maintained at this temperature for 1 hour, and then the surface temperature of the pipe-shaped heater is again increased to 400 ° C. and maintained for 1 hour. The heat generation amount of each thermoelectric conversion module was measured in the same manner as in the previous heat resistance evaluation, immediately after 20 times and immediately after reaching the 20th 400 ° C.
Table 2 below shows the power generation amount of each thermoelectric conversion module.

As shown in Table 2, the thermoelectric conversion module of the present invention maintains a high power generation amount even when heating and cooling are repeated between 50 ° C. and 400 ° C. In particular, the thermoelectric conversion modules of Example 2 and Example 4 using a clad material in which a stainless steel plate is laminated on a substrate are resistant to thermal deformation and maintain a high power generation amount even after repeated severe temperature fluctuations. Yes.
Further, the power generation amount of the third embodiment is higher than that of the first embodiment, in which the upper electrode is bent and c <(4a ² + b ² ) ^1/2 is satisfied but b + (ab / L) <c is not satisfied. Was slightly smaller. This is thought to be due to the fact that there was no allowance for the deflection of the upper electrode, and defects such as microcracks were formed in the joint due to the heat cycle, and the resistance increased, so the power generation amount was reduced.
In addition, as for the thermoelectric conversion module of the comparative example 1, it was thought that wiring was disconnected by deformation | transformation of a board | substrate at 400 degreeC like the previous, and electric power generation amount was not measurable. Further, similarly to the thermoelectric conversion module of Comparative Example 2, it was considered that the upper electrode was disconnected due to being attached to the pipe-shaped heater, and the power generation amount could not be measured.

Moreover, when Example 2 and Example 4 which use the clad material which laminated | stacked the stainless plate as a board | substrate are both seen, regarding heat resistance evaluation, the lower adhesive layer 26 and the upper adhesive layer 32 were formed with the silver nano paste. From Example 2, Example 4 in which the lower adhesive layer 26 and the upper adhesive layer 32 are formed of nickel nanopaste is after 1 hour at 200 ° C., and immediately after 1 hour at 300 ° C. and 400 ° C. The amount of power generation was high.
In addition, also in the heat cycle test, Example 4 in which the lower adhesive layer 26 and the upper adhesive layer 32 were formed of nickel nanopaste obtained a result that the power generation amount was remarkably high.

As described above, it is known that silver nano-paste and nickel nano-paste are almost similar to physical properties of each bulk metal after firing.
Here, the temperature expansion coefficient of nickel is 13.3 ppm / K, and the temperature expansion coefficient of silver is 19.7 ppm / K. Further, the temperature expansion coefficient of the substrate 12a, which is a clad material of stainless steel and an aluminum material having an anodized film, is 10 ppm / K, and the temperature expansion coefficient of the n-type thermoelectric conversion layer 28n (Mg ₂ Si) is 7.5 ppm / K. is there.
When the thermal expansion coefficients of the respective materials are arranged in the order of [thermoelectric conversion layer / adhesion layer metal / substrate], Example 2 is [7.5 / 19.7 / 10] and Example 4 is [7.5 / 13.3 / 10]. In addition, since the temperature expansion coefficient of the board | substrate 12 which is an aluminum material which has an anodized film is 5 ppm / K, the temperature expansion coefficient of Example 1 is [7.5 / 19.7 / 5].

That is, the difference in the temperature expansion coefficient between the adjacent members is the smallest in Example 4, and therefore the difference in thermal expansion between the adjacent members at high temperatures is small in Example 4.
As a result, as described above, in Example 4, the occurrence of microcracks in the lower adhesive layer 26 and the upper adhesive layer 32 due to the difference in thermal expansion, peeling at the interface of each member, and the like can be suppressed. As a result, it is considered that a rise in resistance or the like was suppressed and a high output was obtained.
From the above results, the effects of the present invention are clear.

DESCRIPTION OF SYMBOLS 10 Thermoelectric conversion module 12 Board | substrate 14 Thermoelectric conversion element 16 Metal base material 18 Aluminum base material 20 Insulating layer 24 Lower electrode 26 Lower adhesion layer 28 Thermoelectric conversion layer 28p P-type thermoelectric conversion layer 28n N-type thermoelectric conversion layer 30 Upper electrode 32 Upper adhesion layer

Claims (11)

A flexible substrate having an aluminum base material having an anodized film on one surface and a metal base material laminated on the surface of the aluminum base on which the anodized film is not formed ;
Two lower electrodes provided on the surface of the anodic oxide film of the substrate and spaced apart from each other, a p-type thermoelectric conversion layer electrically connected to the one lower electrode provided on the surface of one of the lower electrodes, and the other lower portion A thermoelectric conversion layer composed of an n-type thermoelectric conversion layer electrically connected to the other lower electrode provided on the surface of the electrode, and an upper electrode connecting the p-type thermoelectric conversion layer and the n-type thermoelectric conversion layer A plurality of thermoelectric conversion elements connected in series with the lower electrode, and
The thermoelectric conversion module, wherein the upper electrode is a metal foil, has flexibility, and further connects the p-type thermoelectric conversion layer and the n-type thermoelectric conversion layer with bending. It is attached to the curved surface,
The radius of curvature of the curved surface is L [mm], the height of the thermoelectric conversion layer is a [mm], and the distance between the p-type thermoelectric conversion layer and the n-type thermoelectric conversion layer of the thermoelectric conversion layer is b [mm]. In this case, the length c [mm] of the upper electrode between the p-type thermoelectric conversion layer and the n-type thermoelectric conversion layer is
b + (ab / L) <c and c <(4a ² + b ² ) ^1/2
The thermoelectric conversion module according to claim 1, wherein: The thermoelectric conversion module according to claim 1 or 2 , wherein the thickness of the substrate is 120 µm or less. 4. The device according to claim 1 , wherein at least one of the p-type thermoelectric conversion layer and the n-type thermoelectric conversion layer is bonded to at least one of the upper electrode and the lower electrode by an adhesive layer having conductivity. The thermoelectric conversion module as described. The thermoelectric conversion module according to claim 4 , wherein the conductive adhesive layer contains nickel. The thermoelectric conversion module according to any one of claims 1 to 5 , wherein a space between the adjacent thermoelectric conversion elements is an air layer. The thermoelectric conversion module according to any one of claims 1 to 6, wherein a space between the p-type thermoelectric conversion layer and the n-type thermoelectric conversion layer of the thermoelectric conversion element is an air layer. The thermoelectric conversion module according to claim 1 , wherein the thermoelectric conversion module has a flexible protective layer so as to cover the plurality of thermoelectric conversion elements. The thermoelectric conversion module according to any one of claims 1 to 8 , wherein each of the p-type thermoelectric conversion layer and the n-type thermoelectric conversion layer is made of a silicide-based material doped to be p-type or n-type. The thermoelectric conversion module according to any one of claims 1 to 9 , wherein the thermoelectric conversion module is attached to a curved surface, and a curvature radius of the curved surface is 30 mm or more. An exhaust pipe for a vehicle,
An exhaust pipe for a vehicle, wherein the thermoelectric conversion module according to any one of claims 1 to 10 is mounted on an outer surface with a surface on which the thermoelectric conversion element is not formed being inward.