JP2002084005A - Thermoelectric module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoelectric module using an N-type thermoelectric element which has superior characteristic when the ambient temperature is in a medium high temperature range about 500 deg.C, and improve the conversion efficiency of a thermoelectric module by combining superior P-type thermoelectric material and superior N-type thermoelectric material. SOLUTION: This thermoelectric module is provided with an N-type thermoelectric element 60 containing compound having a skutterudite structure and a P-type thermoelectric element 59 which is connected with the N-type thermoelectric element directly or via metal member and contains Mn-Si based compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoelectric module that generates electric power by utilizing a temperature difference and, conversely, generates a temperature difference according to an applied electric power.

[0002]

2. Description of the Related Art A thermoelectric module is constructed by combining P-type and N-type thermoelectric elements utilizing thermoelectric effects such as a Thomson effect, a Peltier effect, and a Seebeck effect, such as a thermocouple and an electronic cooling element. . Thermoelectric module
Due to its simple structure, easy handling and the ability to maintain stable properties, widespread use has attracted attention. In particular, as the electronic cooling element, since local cooling and precise temperature control near room temperature are possible, temperature control of devices for optoelectronics and semiconductor lasers, and
Research and development are being widely pursued for application to small refrigerators and the like.

A performance index Z representing the performance of a thermoelectric element is expressed by the following equation using a specific resistance (resistivity) ρ, a thermal conductivity κ, and a Seebeck coefficient (thermoelectric power) α. Z = α ² / ρκ (1) Here, the Seebeck coefficient α has a positive value in a P-type element and a negative value in an N-type element. A thermoelectric element having a large figure of merit Z is desired.

Also, the maximum value η _max of the conversion efficiency of the thermoelectric element
Is represented by the following equation.

(Equation 1) Here, _Th is the temperature on the high temperature side, _Tc is the temperature on the low temperature side, and the temperature difference ΔT is represented by the following equation. _{ΔT = T h -T c ··· (} 3) Further, M, is defined by the following (4) to (7).

(Equation 2)

(Equation 3)

(Equation 4)

(Equation 5)

[0005]

By the way, as the material used for the P-type thermoelectric element, V.I. K. Zaitsev's paper "Thermoelectric properties of anisotropic MnSi _1.75 (Termoel
electric Properties of Anis
Otropic MnSi _1.75 ) "(Thermoelectric Engineering Handbook, published by CRC, pp. 299-309, published in 1995) is a 650 ° C.
Has a high conversion efficiency of about 11%. Matsubara's paper, "Research Status of Skutterudite-Based Thermoelectric Materials" (Thermoelectric Conversion Symposium '97 (TEC '97) Collection of Papers, Thermoelectric Conversion Workshop, July 25, 1997) includes the materials for P-type devices. It discloses that a compound having a skutterudite structure is used. Skutterudite is derived from the Norwegian place name skutteru
It is derived from the mineral CoAs ₃ produced in d). According to this document, CoSb having a skutterudite structure is used.
₃ , RhSb ₃ and IrSb ₃ are P-type semiconductors having a unique band structure and carrier transport characteristics, and are described as being characterized by a hole mobility as large as 2000 to 3000 cm ² / Vs at room temperature. I have. The P-type Zn ₄ Sb ₃ conventionally used is brittle and has a low usable temperature.
Ce (FeCo) ₄ Sb ₁₂ is also fragile and has a
If the temperature is 0 ° C. or higher, it is easily oxidized. In addition, SiGe and Fe
Si-based materials have a problem that the figure of merit is low.

On the other hand, in order to construct an excellent thermoelectric module, not only an excellent P-type thermoelectric element but also an excellent N-type thermoelectric element are required. Conventionally, N-type thermoelectric elements include Mg-Si-Sn-based, SiGe-based, and FeSi.
System, Pb-Te system or Pb-Se system materials have been used.

However, N-type Mg ₂ (Si—S
n) is easily oxidized when the temperature becomes 500 ° C. or more in the atmosphere. Pb-Te-based or Pb-Se-based materials are feared to have an adverse effect on the environment. In addition, SiGe and FeS
The i-type material has a problem that the figure of merit is low.

[0008] In view of the above, the present invention provides a thermoelectric module using an N-type thermoelectric element having excellent characteristics even in a temperature range of about 500 ° C in the middle to high temperatures in the atmosphere. Furthermore, an excellent P-type thermoelectric material and an excellent N
An object of the present invention is to improve the conversion efficiency of a thermoelectric module by combining with a thermoelectric material of a mold type.

[0009]

Means for Solving the Problems To solve the above problems, a thermoelectric module according to a first aspect of the present invention comprises an N-type thermoelectric element containing a compound having a skutterudite structure, and an N-type thermoelectric element. A P-type thermoelectric element that is connected to the thermoelectric element directly or via a metal member and includes a Mn-Si-based compound.

A thermoelectric module according to a second aspect of the present invention includes: an insulator having a plurality of openings formed in a lattice;
An N-type thermoelectric element disposed in the first opening of the insulator and including a compound having a skutterudite structure; and a P-type thermoelectric element disposed in the second opening of the insulator and including a Mn-Si-based compound
And a metal member for connecting the N-type thermoelectric element and the P-type thermoelectric element.

According to the present invention, by using a compound having a skutterudite structure for an N-type thermoelectric element, excellent characteristics can be obtained even at a temperature around 500 ° C. in the atmosphere. As a material of the N-type thermoelectric element, for example, a Co-Sb-based compound can be used. Further, by using an Mn-Si-based compound as a material for a P-type thermoelectric element, a combination of an excellent P-type thermoelectric material and an excellent N-type thermoelectric material to improve the conversion efficiency of a thermoelectric module. Is possible.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a thermoelectric module according to a first embodiment of the present invention. Thermoelectric module 1
Are, for example, two ceramic substrates 3 as heat exchange substrates.
Includes 0 and 40. Two ceramic substrates 30 and 4
By joining a P-type element (P-type semiconductor) 50 and an N-type element (N-type semiconductor) 60 via a metal member, for example, an electrode 70 between 0 and 0, a PN element pair is formed.
In addition, as a metal member, an electrode of copper or nickel, a stress relaxation layer, a bonding layer, a diffusion prevention layer, or the like is applicable. In order to join the thermoelectric element and the metal member, soldering can be used in the case of a low-temperature thermoelectric module using copper as the metal member, but in other cases, brazing,
It is necessary to use thermal spraying, solid phase bonding (sintering), vapor deposition, mechanical fastening, or the like.

A lead wire 80 is connected to the N-type element at one end of the PN element pair and the P-type element at the other end. Cool the ceramic substrate 40 side with cooling water or the like,
When heat is applied to the ceramic substrate 30 side, an electromotive force is generated and a current flows as shown in FIG. That is, power can be taken out by providing a temperature difference between both sides (up and down in the figure) of the thermoelectric module 1.

In FIG. 1, the P-type element and the N-type element are connected by using electrodes formed on two ceramic substrates. However, as described below, all or part of the electrodes and the substrate are connected. It can be omitted. This will be described with reference to FIG. FIG. 2A shows a P-type element 51.
An example is shown in which the N-type element 61 and the N-type element 61 are connected without using an electrode. As shown in the figure, a P-type element 51 and an N-type element 61
By forming a notch in a part of the current, a current is prevented from forming a minor loop and short-circuiting and flowing.
In this case, electrodes on both sides or one side can be omitted, and substrates on both sides or one side can be omitted.

FIG. 2B shows one side (the lower side in the figure).
, The P-type element 52 and the N-type element 62 are connected using a metal member, for example, an electrode 72, and the other side (upper side in the figure)
1 shows an example in which a P-type element 52 and an N-type element 62 are connected without using electrodes. Again, the P-type element 52
And a cutout is provided in a part of the N-type element 62. In this case, the electrode on one side can be omitted, and the substrate on one side can be omitted.

FIG. 2C also shows that the P-type element 53 and the N-type element 63 are connected on one side using a metal member, for example, an electrode 73, and the P-type element 53 and the N-type element are connected on the other side. 63 is connected without using an electrode.
Here, the P-type element 53 and the N-type element 63 have a curved shape. Also in this case, the electrode on one side can be omitted, and the substrate on one side can be omitted. Note that FIG.
In the description of (a) to (c), when a P-type element and an N-type element are connected without using an electrode, a case where these elements are directly connected to each other, and a case where a bonding layer is provided between these elements. Or the case where the connection is made via a diffusion prevention layer.

Next, a case where a thermoelectric module is manufactured by thermal spraying will be described with reference to FIGS. FIG. 3 is an assembly diagram of a thermoelectric module manufactured by thermal spraying. As shown in FIG. 4, a P-type element 54 and an N-type element 64 are arranged in a stepped insulator lattice 100. The metal members 74 and 90 are sprayed thereon.

The manufacturing process of the thermoelectric module by thermal spraying will be described with reference to FIG. First, as shown in FIG. 5A, a grid 100 having a step is made of an insulator such as alumina ceramic. Next, as shown in FIG. 5 (b), P
The mold element 54 and the N-type element 64 are arranged. Next, as shown in FIG. 5C, adjacent elements are connected.
The metal member 90 is thermally sprayed. Further, as shown in FIG. 5D, a single layer or a plurality of metal layers are formed by spraying the metal member 74 from above the metal member 90. In such a thermoelectric module, adjacent elements are connected by a metal member sprayed as shown in FIG. 5C by providing steps in the grid as shown in FIG. 5A.

When the thermoelectric module as described above is used as a power generation unit, for example, as shown in FIG. 6, a cooling pipe 2 is arranged on one ceramic substrate (low-temperature ceramic substrate) of the thermoelectric module 1. Set up. The cross section perpendicular to the longitudinal direction of the cooling pipe 2 is circular or rectangular, and cools the low-temperature side ceramic substrate by flowing cooling water through the pipe. On the other hand, the other ceramic substrate of the thermoelectric module 1 (high-temperature-side ceramic substrate)
Is provided with a metal plate 3 for absorbing heat. The heat collecting effect can be enhanced by integrally forming the heat collecting fins 4 on the metal plate 3 or by separately forming and connecting them. Further, a plurality of thermoelectric modules 1 are connected to lead wires 5.
Connect with Electric power can be extracted from the thermoelectric module due to the temperature difference between the high temperature side and the low temperature side.

In the present invention, a compound having a skutterudite structure is used as a material for the N-type element. In particular, a compound having the following composition is suitable as a material for an N-type element. _{(1) M 1-A M} 'A represented by X _B compounds where, M represents Co, Rh, either of Ir, M' is a dopant for the N-type, P
d, Pt, or PdPt, wherein X is A
s, P, or Sb, where 0 <A ≦
Those satisfying the condition of 0.2 and 2.9 ≦ B ≦ 4.2 are suitable. In particular, if B = 3, a compound having a simple composition ratio can be obtained. As a specific example, a Co—Sb-based compound, for example, Co _0.9 (PdPt) _0.1 Sb ₃ can be given. Here, Co _0.9 (PdPt) _0.1 Sb
Instead of _3, it will be described with Figure 7 shows the crystal structure of CoSb ₃ having the same structure as this. This crystal structure is called a skutterudite structure. As shown in FIG. 7, the unit cell of CoSb ₃ is a cubic lattice including a total of 32 atoms of 8 Co atoms and 24 Sb atoms.
The Co atom is located at the center of the octahedron of Sb atoms created by six Sb atoms. Eight octahedrons of Sb atoms exist in one unit cell. These eight octahedrons form an icosahedron of Sb atoms. Empty baskets without atoms are formed at the center and corners of the unit cell.

(2) Compound represented by M (X _1-A X ′ _A ) ₃ wherein M represents any one of Co, Rh and Ir, and X represents As, P, Sb X ′
Represents any of Te, Ni, and Pd, and 0
Those satisfying the condition of <A ≦ 0.1 are suitable. (3) Compound represented by M _1-A M ′ _A (X _1-B X ′ _B ) _C Here, M represents any one of Co, Rh and Ir, and M ′ is N-type And a dopant for
d, Pt, or PdPt, wherein X is A
represents any one of s, P and Sb, and X ′ is Te, N
i, Pd, and 0 <A ≦ 0.
Those satisfying the conditions of 2, 0 ≦ B ≦ 0.1 and C = 3 are suitable.

By using the above-mentioned materials, even if the temperature becomes about 500 ° C. in the atmosphere, the material itself is hardly oxidized, has relatively high strength, and is relatively environmentally friendly. Can be realized. Of these materials, Co-Sb compounds are difficult to produce because a single phase cannot be easily obtained as judged from the phase diagram of FIG. 8, and it is difficult to obtain satisfactory characteristics. In consideration of this point, a manufacturing method was devised in manufacturing the thermoelectric element according to the present embodiment. As a result of trying many production methods, it was found that the solid-phase reaction, explosion welding, MA
(Mechanical alloying), SPS (spark plasma sintering), HP (hot press), annealing, plastic working, etc., in several ways.

By the way, between the thermoelectric element and the thermoelectric element or between the thermoelectric element and the metal member, one or more diffusion preventing layers are provided as intermediate layers in order to prevent the diffusion of atoms. It is desirable to provide. In general, since the coefficient of linear expansion is different between the thermoelectric element and the material used as the electrode, when used in a medium to high temperature region around 500 ° C., one of them expands significantly, generating thermal stress and causing a joint surface to be formed. There is a high possibility that the thermoelectric element will be peeled or cracked. Therefore,
It is desirable that the material used for the diffusion prevention layer is selected in consideration of the coefficient of linear expansion.

For example, when a Co-Sb-based material is used for the N-type element and copper is used for the electrode, the linear expansion coefficient of the diffusion prevention layer is 8 × 10 ⁻⁶ / Co-Sb-based material. K (at 8
00K) or more, the coefficient of linear expansion of copper is 20 × 10 ⁻⁶ / K
(At 800 K) or less, a diffusion preventing layer is provided. Factors other than the linear expansion coefficient include diffusion coefficient, thermal conductivity, specific resistance,
Considering Young's modulus, etc., Nb, V, Cr, Ti, Rh, and P are used as the first intermediate layer (the layer immediately above the thermoelectric element).
t, Zr, W, Ta, Mo, Ni, Cu, Fe, Ag,
It is preferable to use Au, Sb, an alloy containing these, and the like. Among these, Mo, Ta, and Cr are particularly suitable.

The intermediate layer such as the diffusion preventing layer may be a single layer or a multilayer. When providing a multilayer intermediate layer, the thermal stress can be relaxed by gradually increasing the linear expansion coefficient from the thermoelectric element toward the electrode.

The electrodes electrically connected to the N-type element include Ag, Al, Au, Co, Cu, Fe, Pt, T
It is preferable to use i, Zn, Ni, an alloy containing these, and the like. Particularly desirable are Cu, Ni and Fe. Each of these has a linear expansion coefficient of 1 at room temperature.
6.5 × 10 ^-6 /K,13.3×10 ^-6 /K,11.7
× 10 ^-6 / K, for example, the coefficient of linear expansion of Al (23.9
(× 10 ⁻⁶ / K), which is close to the linear expansion coefficient of the thermoelectric element.

Further, an electrode holding layer may be provided on the surface of the electrode opposite to the thermoelectric element. This electrode holding layer is desirably formed of a material having a small coefficient of linear expansion.
By sandwiching the electrode between the intermediate layer having a small coefficient of linear expansion and the electrode holding layer having a small coefficient of linear expansion, thermal stress can be reduced. As a material of the electrode holding layer, Al ₂
Ceramics made from O ₃ or AlN, SiO ₂
From glass, Cr, Nb, Pt, Rh, Si,
It is possible to use Ta, Ti, V, Mo, W, Zr, and alloys containing these.

The thickness of the intermediate layer is desirably about the same as the thickness of the electrode (1: 1). Specifically, the thickness of the intermediate layer and the electrode is preferably 5 μm to 1000 μm, and more preferably 50 μm to 300 μm.
As described above, the intermediate layer may have a multilayer structure, and the electrode may be sandwiched between the intermediate layer and the electrode holding layer.

On the other hand, as the material of the P-type element, a Mn-Si compound is used in the present embodiment. In particular, a compound having the following composition is suitable as a material for a P-type device. (1) MnSi _A Here, 1.72 ≦ A ≦ 1.75. (2) Ge, Sn, MnSi _A as dopants
A compound in which at least one of Mo and Al is attached at 0 to 5 atm%, for example, Mn _1-B Mo _B Si _AC — _D Ge _C Al _D. Here, 0 <B, C, D ≦ 0.1 may be satisfied.

Mn-S used as a material for a P-type element
The i-type compound also has difficulty in producing a single phase as judged from the phase diagram of FIG. 9, so that it is difficult to produce and it is difficult to obtain satisfactory characteristics. Therefore, when manufacturing the material of the P-type element, solid-state reaction, explosion welding, MA, SPS, HP, annealing,
Several manufacturing methods combining methods such as plastic working are effective. Further, as in the case of the N-type element, it is desirable to provide one or more diffusion prevention layers between the thermoelectric element and the thermoelectric element or between the thermoelectric element and the metal member also in the P-type element.

For example, when using a Mn-Si-based material for the P-type element and using copper for the electrode, the linear expansion coefficient of the diffusion prevention layer is 12 × 10 ⁻⁶ / Mn-Si-based material. Above the vicinity of K (at 800 K), the coefficient of linear expansion of copper is 20 × 10 ⁻⁶ /
A diffusion prevention layer below K (at 800 K) is provided. Taking into account the diffusion coefficient, thermal conductivity, specific resistance, Young's modulus, and the like as factors other than the linear expansion coefficient, Nb, V, Cr, Ti are used as the material of the first intermediate layer (the layer immediately above the thermoelectric element). ,
Rh, Pt, Zr, W, Ta, Mo, Ni, Cu, F
e, Ag, Au, Si, and alloys containing them are preferred. Among these, in particular, Nb, Mo, Ta, P
t and Cr are suitable.

The intermediate layer such as the above-mentioned diffusion preventing layer is
It may be a single layer or a multilayer. When providing a multilayer intermediate layer, the thermal stress can be relaxed by gradually increasing the linear expansion coefficient from the thermoelectric element toward the electrode.

The electrodes electrically connected to the P-type element are made of Ag, Al, Au, C, as in the case of the N-type element.
o, Cu, Fe, Pt, Ti, Zn, Ni, and alloys containing these, etc., particularly, Cu, Ni, and Fe are particularly preferable.

The shapes of the P-type and N-type thermoelectric elements are as follows.
By using a columnar shape, a cylindrical shape, or a trapezoidal shape, thermal stress can be reduced. In addition, cylindrical, cylindrical,
By chamfering the edge of a thermoelectric element having a trapezoidal or rectangular parallelepiped shape, thermal stress can be reduced.

Further, an electrode holding layer may be provided on the surface of the electrode opposite to the surface connected to the thermoelectric element. This electrode holding layer is desirably formed of a material having a small coefficient of linear expansion. By sandwiching the electrode between the intermediate layer having a small coefficient of linear expansion and the electrode holding layer having a small coefficient of linear expansion, thermal stress can be reduced. As the material of the electrode holding layer, ceramics made of Al ₂ O ₃ or AlN, glass made of SiO ₂ , Cr, Nb, Pt,
Rh, Si, Ta, Ti, V, Mo, W, Zr, and
Alloys containing these can be used.

The thickness of the intermediate layer is desirably about the same as the thickness of the electrode (1: 1). Specifically, the thickness of the intermediate layer and the electrode is preferably 5 μm to 1000 μm, and more preferably 50 μm to 300 μm.
As described above, the intermediate layer may have a multilayer structure, and the electrode may be sandwiched between the intermediate layer and the electrode holding layer.

When a diffusion preventing layer of the same element is formed in the P-type element and the N-type element, the diffusion preventing layer can be simultaneously formed on the P-type element and the N-type element by thermal spraying or the like. Manufacturing is simplified. For example, if the N-type element is Co
When Sb ₃ is used and MnSi _1.73 is used for the P-type element, V, Cr, Ti, Nb, Fe,
It is preferable to use Cu, Ni, Ta, W, Zr, Mo, or the like, and to use Cu, Ni, Fe, or the like as an electrode.

As a method of joining a thermoelectric element to an electrode or the like, thermal spraying is particularly excellent. Co-S as thermoelectric element
The joining method in the case of using the b-type compound was studied including brazing, thermal spraying, solid phase joining, and vapor deposition. As a result, according to the vapor deposition, there is a problem that the degree of adhesion is reduced. In the case of brazing, a brazing material having a melting point of about 600 ° C. is desirable for a Co—Sb-based compound,
There is very little brazing material in such a temperature range. further,
Since the melting point of the Co-Sb-based compound used as the N-type element is different from that of the Mn-Si-based compound used as the P-type element, a low melting point Co-Sb-based compound (for example, CoSb
_If a brazing material is selected according to ₃ ), the result is that the efficiency of the Mn-Si-based compound cannot be exhibited. Solid-phase bonding is suitable when using materials having similar strengths and melting points as N-type and P-type thermoelectric elements, but both a Co-Sb-based compound and a Mn-Si-based compound having different strengths and melting points. It is difficult to find a joining condition that suits the requirements. On the other hand, according to thermal spraying, a large amount of thermoelectric elements and electrodes and the like can be joined at a time in a low-temperature environment, and a high degree of adhesion can be obtained.

On the other hand, when assembling a thermoelectric module using brazing or solid-state bonding, a diffusion preventing layer of a different element can be formed between the P-type element and the N-type element. In this case, the diffusion preventing layer is formed by plating or the like. For example, CoSb ₃ is used for the N-type element, and MnS is used for the P-type element.
When i _1.73 is used, Nb, Ni, Fe, Cr, Sb, Ti, M
It is preferable to use o, Zr, Cu, W, Ta, and alloys containing these, and to use Cu, Ni, Fe, etc. as the electrode. On the other hand, in the P-type element, it is preferable to use Cr, Ni, Fe, Si, Mo, and an alloy containing them as the diffusion prevention layer, and to use Cu, Ni, Fe, or the like as the electrode. In this case, as in the case of thermal spraying,
An intermediate layer such as a diffusion prevention layer or the like may have a multilayer structure, or a structure in which an electrode is sandwiched between the intermediate layer and the electrode holding layer.

Next, a second embodiment of the present invention will be described. In the present embodiment, each of the N-type and P-type thermoelectric elements is formed into a segment type as a multilayer structure.
FIG. 10 shows a thermoelectric module according to the present embodiment. FIG. 10 shows an example in which each of the N-type and P-type thermoelectric elements has a two-layer structure. As the N-type thermoelectric element 65 on the high temperature side, CoSb to which an N-type dopant is added is used.
_3, and an N-type Bi-Te-based compound is used as the low-temperature-side N-type thermoelectric element 66. On the other hand, a P-type dopant-added Mn-Si-based compound is used as the high-temperature-side P-type thermoelectric element 55, and a P-type Bi-Te-based compound is used as the low-temperature-side P-type thermoelectric element 56. Used.
When connecting the high-temperature-side thermoelectric element and the low-temperature-side thermoelectric element, these elements may be directly connected to each other, or may be connected between these elements via a bonding layer or a diffusion prevention layer.

As described above, different materials are used on the high-temperature side and the low-temperature side because, as shown in FIG. 11, the temperature characteristics of the figure of merit Z differ depending on the material, and there is an appropriate material at each temperature. It is. By doing so, the thermoelectric conversion efficiency of the thermoelectric module can be improved as compared with the case where the entire thermoelectric element is formed of one material.

The high-temperature side N-type thermoelectric element 65 and the high-temperature side P
The mold thermoelectric element 55 is connected via an electrode 71.
When the low-temperature-side N-type thermoelectric element 66 and the low-temperature-side P-type thermoelectric element 56 are connected to the load resistor R via the electrode 72, power corresponding to the temperature difference between the high-temperature side and the low-temperature side can be taken out. it can. The connection between the thermoelectric element and the electrode is the same as that described in the first embodiment.

Next, a third embodiment of the present invention will be described. In this embodiment, the unit of the thermoelectric module is a cascade type having a multilayer structure. FIG. 12 shows a thermoelectric module according to the present embodiment. FIG. 12 shows an example in which the unit of the thermoelectric module has a two-layer structure. In the module unit on the high temperature side, as the N-type thermoelectric element 67, CoSb added with an N-type dopant is used.
_3, and a P-type thermoelectric element 57 is a Mn-Si-based compound to which a P-type dopant is added. On the other hand, in the module unit on the low-temperature side, an N-type Bi-Te-based compound is used as the N-type thermoelectric element 68, and a P-type Bi-Te-based compound is used as the P-type thermoelectric element 58. The reason why different materials are used on the high temperature side and the low temperature side for the same reason as in the second embodiment.

In the module unit on the high-temperature side, the N-type thermoelectric element 67 and the P-type thermoelectric element 57 are arranged between the ceramic substrates 110 and 120 and are connected via the electrodes 73. Also, in the module unit on the low temperature side, N
The thermoelectric element 68 and the P-type thermoelectric element 58 on the low-temperature side are disposed between the ceramic substrates 120 and 130, and the electrodes 7
4. The connection between the thermoelectric element and the electrode is the same as that described in the first embodiment.

When these module units are respectively connected to the load resistors R1 and R2, it is possible to extract electric power corresponding to the temperature difference in each module unit. Alternatively, these module units may be connected in series or in parallel.

Next, the characteristics of the N-type element and the P-type element used in the above embodiment will be described. FIG.
FIG. 3 is a diagram showing the thermoelectric conversion efficiency at the element level of a Co-Sb-based N-type element and a Mn-Si-based P-type element. The horizontal axis indicates the temperature on the high temperature side, and the temperature on the low temperature side is room temperature (27
° C). The thermoelectric conversion efficiency of the Co-Sb-based N-type element shows a good value of about 11% at a temperature difference of 550 ° C. In addition, the thermoelectric conversion efficiency of the Mn-Si-based P-type element shows a favorable value of about 11% at a temperature difference of 650 ° C.

Further, as in the above embodiment, C
When a thermoelectric module is configured by combining an o-Sb-based N-type element and a Mn-Si-based P-type element, 600
The thermoelectric conversion efficiency of the thermoelectric module is about 10.
It was 5%. The thermoelectric conversion efficiency is determined by the thermoelectric conversion efficiency of the Si-Ge thermoelectric module (4.
6%) and the thermoelectric conversion efficiency of the Si-Ge-based and PbTe-GeTe-based cascade modules (9.9% at a temperature difference of 687 ° C.). In addition, a Co-Sb-based N-type device and a Mn-Si-based P-type
Thermoelectric modules combined with die elements have the advantages of being environmentally friendly and of low cost.

[0048]

As described above, according to the present invention, it is possible to provide a thermoelectric module using an N-type thermoelectric element having excellent characteristics even in a temperature around 500 ° C. in the atmosphere. . Further, by combining the excellent P-type thermoelectric material and the excellent N-type thermoelectric material, it is possible to improve the conversion efficiency of the thermoelectric module.

[Brief description of the drawings]

FIG. 1 is a diagram showing a thermoelectric module according to a first embodiment of the present invention.

FIG. 2 is a view showing a modification of the thermoelectric module according to the first embodiment of the present invention.

FIG. 3 is an assembly view of a thermoelectric module manufactured by thermal spraying.

FIG. 4 is a perspective view showing an example of the arrangement of P-type elements and N-type elements in the thermoelectric module of FIG.

FIG. 5 is a perspective view showing a part of the thermoelectric module of FIG. 3 along a manufacturing process.

FIG. 6 is a diagram showing a power generation unit using the thermoelectric module according to the first embodiment of the present invention.

FIG. 7 shows the Co used in the first embodiment of the present invention.
Is a diagram showing the crystal structure of sb _3.

FIG. 8 is a phase diagram of a Co—Sb-based compound used in an N-type element.

FIG. 9 is a phase diagram of a Mn—Si-based compound used in a P-type device.

FIG. 10 is a diagram showing a thermoelectric module according to a second embodiment of the present invention.

FIG. 11 is a diagram showing a figure of merit of a thermoelectric element used in a thermoelectric module according to a second embodiment of the present invention.

FIG. 12 is a view showing a thermoelectric module according to a third embodiment of the present invention.

FIG. 13 shows a P-type element and N used in each embodiment of the present invention.
It is a figure showing the thermoelectric conversion efficiency of a model element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermoelectric module 2 Cooling pipe 3 Metal plate 4 Heat collecting fin 5 Lead wire 30, 40, 110, 120, 130 Ceramic substrate 50-58 P-type thermoelectric element 60-68 N-type thermoelectric element 70-74 Electrode 72-74 , 90 Metal member 80 Lead wire 100 Insulator lattice

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenichi Tomita 1200 Manda, Hiratsuka-shi, Kanagawa Prefecture Inside Komatsu Seisakusho Research Headquarters (72) Inventor Koichi Ishida 1200 Manda, Hiratsuka-shi, Kanagawa Komatsu Seisakusho Research Headquarters Inside

Claims (10)

[Claims] An N-type thermoelectric element including a compound having a skutterudite structure, and a P-type thermoelectric element connected to the N-type thermoelectric element directly or via a metal member and including a Mn-Si-based compound. And a device. 2. The N-type thermoelectric element and the P-type thermoelectric element are directly connected in a first region, and are connected via a metal member in a second region. The thermoelectric module according to claim 1. 3. An N-type thermoelectric element, comprising: an insulator having a plurality of openings formed in a lattice pattern; an N-type thermoelectric element including a compound having a skutterudite structure disposed in the first opening of the insulator; A P-type thermoelectric element disposed in the second opening of the object and containing a Mn-Si-based compound; and a metal member for connecting the N-type thermoelectric element and the P-type thermoelectric element. Thermoelectric module. 4. The thermoelectric module according to claim 1, wherein the N-type thermoelectric element contains a Co—Sb-based compound. 5. At least one supporting said N-type thermoelectric element and said P-type thermoelectric element directly or via a metal member.
The thermoelectric module according to any one of claims 1 to 4, further comprising two heat exchange boards. 6. The thermoelectric module according to claim 1, wherein the metal member includes one of Cu, Ni, and Fe. 7. At least one of an intermediate layer formed between the N-type thermoelectric element and the metal member and an intermediate layer formed between the P-type thermoelectric element and the metal member. The thermoelectric module according to claim 1, further comprising one of them. 8. When the intermediate layer is formed between the N-type thermoelectric element and the metal member, the intermediate layer is
o, Ta, or Cr, and when the intermediate layer is formed between the P-type thermoelectric element and the metal member, the intermediate layer is formed of Nb, Mo, Ta, Pt, The thermoelectric module according to any one of claims 1 to 7, wherein the thermoelectric module includes any one of Cr. 9. The thermoelectric module according to claim 7, wherein the intermediate layer is formed by thermal spraying. 10. The thermoelectric module according to claim 1, wherein said metal member is formed by thermal spraying.