JPH07142768A - Thermoelectric conversion element - Google Patents

Abstract

PURPOSE:To improve the power generating capability by providing a thermal conduction metal plate consisting of titanium or titanium alloy between a pair of semiconductors and brazing these elements with a copper system brazing material to form the PN junction. CONSTITUTION:A thermal conduction metal plate 13 is provided between a P-type semiconductor 11 and an N-type semiconductor 12 and these semiconductors 11, 12 and thermal conduction metal plate 13 are brazed into an integrated element by a copper system brazing material 14. Meanwhile, a copper plate 15 which works as an electrode plate and a heat sink is brazed in the side of open ends of the semiconductors 11, 12 with a brazing material to form an integrated element. Therefore, since only the PN junction is heated, a temperature difference can also be obtained even at the area near the cold contact point, internal resistance becomes small and a stabilized power can be extracted from the open ends side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention relates to iron sulfide (FeSi
₍₂ ) A thermoelectric conversion element comprising a P-type semiconductor and an N-type semiconductor mainly composed of ₂ ) and having a PN junction structure. The PN junction part is made of titanium (Ti) or a titanium (Ti) alloy. The present invention relates to a thermoelectric conversion element which is brazed with a copper (Cu) -based brazing material with the interposition of, to improve the power generation capacity (conversion efficiency) and facilitate manufacturing.

[0002]

2. Description of the Related Art A thermoelectric conversion element is a device which is highly demanded in recent industry and is expected to be put into practical use from the viewpoint of effective utilization of thermal energy. For example, exhaust heat is used to convert it into electric energy. A very wide range of applications are being investigated, such as systems, small portable power generators for easily obtaining electricity outdoors, and flame sensors for gas appliances. However, thermoelectric conversion elements that have been known so far are generally high in price of semiconductors that constitute the thermoelectric conversion element, and instead have a narrow operating temperature range, low conversion efficiency, and a complicated manufacturing method. For this reason, it has not been widely used.

As a thermoelectric conversion element for solving these problems, there has been proposed a thermoelectric conversion element having a structure in which a P-type semiconductor mainly composed of iron silicide (FeSi ₂ ) and an N-type semiconductor are PN-junctioned, Attention is paid to the fact that the semiconductor is made of a relatively inexpensive material, has a wide operating temperature range, and has high heat resistance of about 900 ° C.

In this thermoelectric conversion element, as shown in FIG. 10, usually, a P-type semiconductor 2 and an N-type semiconductor 3 in which an appropriate impurity such as manganese (Mn) or cobalt (Co) is added to iron silicide (FeSi ₂ ). And a U-shape formed by PN-joining at one end side. In the thermoelectric conversion element 1 having such a configuration, when the PN junction 4 is heated, thermal energy is supplied to the PN junction 4 and the Seebeck effect causes the open ends (low temperature ends) of the respective semiconductors 2 and 3. Positive (+) and negative (-) voltages are generated in the electric field, and electric power can be taken out from the open end.

Further, it is known that the thermoelectric conversion element 1 having this U-shaped shape is manufactured by the steps described below. That is, 1) An alloy for P-type semiconductor and an alloy for N-type semiconductor having a predetermined composition of Fe _1-X Mn _X Si ₂ and Fe _1-Y Co _Y Si ₂ are obtained by melt casting. 2) Each of the above semiconductor alloys is crushed to a predetermined particle size (about 1.5 μm) by a crusher such as a stamp mill or a ball mill. 3) A predetermined amount of binder (PVA) is kneaded and granulated. 4) Each of the above semiconductor alloy powders is filled in a die having a U-shaped through hole. However, when the alloy powder is filled, the lower punch is arranged in advance in the die, and the partition plate is arranged at the position to be the PN junction.
After filling a predetermined amount of each alloy powder for semiconductors, the partition plate is removed so that the alloy powders for semiconductors contact each other at the PN junction. 5) Pressure compression molding is performed with the upper punch and the lower punch arranged in the die to obtain a molded body having a U-shape. 6) The molded body is debindered in the atmosphere and then sintered at a predetermined temperature in vacuum (for example, 1150).
C x 3 hours). 7) The sintered body is subjected to semiconductor heat treatment at a predetermined temperature in the atmosphere (for example, 750 ° C. × 50 to 200 hours).

[0006]

A U-shape in which a P-type semiconductor 2 and an N-type semiconductor 3 mainly composed of iron silicate (FeSi ₂ ) obtained by the above-described manufacturing method are joined to form a PN junction. The type thermoelectric conversion element 1 is superior to other conventionally known thermoelectric conversion elements in terms of price, heat resistance, etc. However, on the other hand, the following problems are caused by the PN junction configuration, the manufacturing method, and the like. Have a point. In the structure shown in FIG. 10, when the PN junction 4 is heated, an electron-hole pair that is a source of a current is generated by supplying thermal energy to the PN junction 4. At the same time, when the electron-hole pair is generated, Due to the so-called Peltier effect that robs thermal energy, the temperature of the PN junction 4 is lowered, and as a result, the frequency of generation of electron-hole pairs is reduced, and the semiconductors 2 and 3 can be taken out from the open end side (low temperature end side). Electric power is reduced, and the required power generation capacity (conversion efficiency) has not been realized.

In the manufacturing method described above, U
In order to obtain a shaped body of the V-shaped thermoelectric conversion element, it is necessary to simultaneously fill two dies, which are an alloy powder for P-type semiconductor and an alloy powder for N-type semiconductor, in one die without mixing them. Therefore, the filling work becomes very complicated. Further, since the two types of powders are integrated by pressure compression molding and sintering, the shape of the molded body is necessarily limited, and it may be a factor that hinders the expansion of applications of this thermoelectric conversion element. Has become.

Furthermore, even if great care is taken during the above-mentioned filling work, it is difficult to completely prevent the mixing of the powders at the joint portions of the alloy powders for semiconductors,
A good PN junction cannot be obtained depending on the junction state, which is a factor causing electrical characteristic deterioration and variation.

The present invention solves the above problems and provides a thermoelectric conversion element having a structure in which a P-type semiconductor mainly composed of iron silicide (FeSi ₂ ) and an N-type semiconductor are PN-junctioned. The purpose of the present invention is to provide a structure capable of improving the conversion efficiency) and an easy manufacturing method, and to greatly expand the application range of the thermoelectric conversion element.

[0010]

According to the present invention, as a result of repeating various investigations in order to achieve the above-mentioned object, a P-type semiconductor and an N-type semiconductor mainly containing iron silicide (FeSi ₂ ) are prepared in advance. After being prepared separately, each of these semiconductors is made of titanium (Ti) or titanium (T) with a copper (Cu) -based brazing material.
i) It is known and proposed that the object can be achieved by brazing and integrating with a metal plate for heat conduction such as an alloy.

That is, in order to facilitate manufacture, the present inventor can completely prevent the alloy powder for semiconductors from being mixed in the PN junction portion, and can arbitrarily select the shape of each semiconductor, the P type It was determined that it was essential to create the semiconductor and the N-type semiconductor separately. In order to efficiently supply the thermal energy to the PN junction in order to prevent the reduction of the generation of electron-hole pairs due to the Peltier effect, the inventor of the present application uses the PN junction in the conventional configuration in which the PN junction is directly heated. There is a limit in terms of the shape of the parts, etc., and it is effective to dispose a heat conducting metal plate capable of efficiently conducting the heat energy from the heat source to the PN junction at each of the semiconductor junctions. It was confirmed that titanium (Ti) or titanium (Ti) alloy, which has excellent oxidation resistance, is effective as a metal plate for heat conduction in order to prevent oxidation due to high temperature heating.

Further, various studies have been made on means for joining and integrating these separately prepared semiconductor and metal plate for heat conduction. In the conventionally known solder, the melting point is low even though the joining and integration are possible. Therefore, it is difficult to use at high temperature, and iron sulfide (FeSi ₂ ) when used at low temperature
The characteristics originally possessed by the semiconductor mainly composed of were not fully expressed, and the target output power could not be obtained.

Since the silver (Ag) brazing material which has been widely used as a brazing material has a poor bonding strength with the oxide film (SiO ₂ ) formed on the surface of each semiconductor, the bonding strength is low, especially in a high temperature atmosphere. If a brazing strength that does not withstand the use of the above is not obtained, and after brazing with silver (Ag) brazing after removing the oxide film (SiO ₂ ), silver (Ag) diffuses inside each semiconductor, It was confirmed that not only the electrical characteristics of the semiconductor are deteriorated, but also the mechanical characteristics are deteriorated (becomes brittle).

Therefore, each of the above semiconductors and titanium (T
As a result of various studies on the brazing integration with i) or titanium (Ti) alloy, copper (Cu) is the main component (the content of Cu is 5
When the copper (Cu) -based brazing filler metal (0 at% or more) was used for the joining and integration, an extremely good joining could be obtained without removing the oxide film (SiO ₂ ) on the semiconductor surface.

The present invention completed on the basis of various findings as described above is, in short, iron sulfide (FeSi).
₂ ) In a thermoelectric conversion element having a structure in which a P-type semiconductor and an N-type semiconductor mainly composed of ₂ ) are PN-junctioned, a metal plate for heat conduction made of titanium (Ti) or a titanium (Ti) alloy is provided between the pair of semiconductors. The thermoelectric conversion element is characterized in that a PN junction is formed by interposing it and brazing it with a copper (Cu) brazing material.

[0016]

FIG. 1 is a schematic explanatory view showing an embodiment of the thermoelectric conversion element of the present invention. That is, iron silicide (FeSi
₂ ) The P-type semiconductor 11 and the N-type semiconductor 12 which are mainly composed of P are formed through a metal plate 13 for heat conduction made of titanium (Ti).
In order to form an N-junction and join the semiconductors 11, 1
2 and the metal plate 13 for heat conduction, a copper (Cu) -based brazing material 14,
The thermoelectric conversion element 10 has a structure in which it is brazed and integrated at 14. Reference numerals 15 and 15 are copper (Cu) bonded to the open ends of the semiconductors 11 and 12, respectively, which also serve as an electrode plate and a heat dissipation plate.
Since it is a plate and the temperature of the joint is lower than that of the PN joint, a brazing material 16 having a low melting point such as zinc-tin (Zn-Sn) solder without using a copper (Cu) brazing material 16 , 1
The thermoelectric conversion element 10 having the desired characteristics can be obtained by joining and unifying at 6.

In the above structure, when the heat conducting metal plate 13 made of titanium (Ti) is brought close to a heat source (not shown), thermal energy from the heat source is passed through the heat conducting metal plate 13 to form an iron silicide ( P-type semiconductor composed mainly of FeSi ₂ 1
1 and the N-type semiconductor 12 are conducted and supplied to each of the semiconductors 11 and 12 by the Seebeck effect as described above.
A plus (+) voltage and a minus (-) voltage are generated on the open end side (low temperature end side), and electric power can be taken out from the open end.

In this structure, each semiconductor 11,
Titanium (T
The metal plate 13 for heat conduction consisting of i) is arranged, and thermal energy is constantly efficiently supplied from a heat source (not shown) located outside each of the semiconductors 11 and 12, so that electron holes due to the Peltier effect are generated. The generation of pairs can be prevented from decreasing, and power generation efficiency can be improved. In addition, since the P-type semiconductor 11 and the N-type semiconductor 12 are manufactured separately and are bonded to each other via the heat conduction metal plate 13, it is stable without mixing of the alloy powder for semiconductor in the PN junction. Electricity can be taken out.

Further, a heat dissipation plate made of a copper (Cu) plate is joined to the open ends of the semiconductors 11 and 12, respectively, so that the temperature difference between the heating portion (PN junction portion) and the open end of the semiconductors 11 and 12 is reduced. It will be possible to expand and further improve the power generation efficiency. Since the temperature sensitive portions of the semiconductors 11 and 12 are substantially only the joint portion with the metal plate 13 for heat conduction, the total length (L) of the semiconductors 11 and 12 can be shortened. , 12 can also reduce the electrical resistance, which contributes to the improvement of power generation efficiency. Besides, the thermoelectric conversion element 10 of the present invention has various characteristics, and the specific characteristics thereof will be described in detail in combination with other embodiments described later.

Each member constituting the thermoelectric conversion element 10 of the present invention will be described in more detail below. Each of the semiconductors 11 and 12 constituting the thermoelectric conversion element 10 is separately filled in a die having a molding space (through hole) having a predetermined shape and press-compressed, and the conventional semiconductors described above are used. It can be obtained by a method substantially similar to the manufacturing method. That is, Fe _1-X Mn _X Si obtained by melt casting
_In a die having a molding space (through hole) having a predetermined shape after crushing and granulating a P-type semiconductor alloy and an N-type semiconductor alloy having a predetermined composition of ₂ and Fe _{1 -Y} Co _Y Si ₂ P, as a separate individual product through the processes of pressure compression molding, binder removal processing, and sintering.
The type semiconductor 11 and the N-type semiconductor 12 are obtained.

In the thermoelectric conversion element of the present invention, the brazing temperature of the heat conductive metal plate 13 and the semiconductors 11 and 12 using the copper (Cu) type brazing material is usually 800 ° C. to 9 ° C.
Since it is carried out at about 00 ° C., the semiconductor heat treatment is performed after the end of the brazing process. That is, heating after the heat treatment for semi-conductor heating above the heat treatment temperature deteriorates the original characteristics of the semiconductor and makes it impossible to obtain the desired power generation effect.

The heat-conducting metal plate 13 arranged at the joint between the P-type semiconductor 11 and the N-type semiconductor 12 can efficiently conduct and supply the heat energy from the heat source to the semiconductor, and heat the surface of the material. Either titanium (Ti) or titanium (Ti) alloy is selected and used in order to prevent oxidation due to, but especially when a titanium (Ti) alloy is used,
From the viewpoint of desired oxidation resistance and familiarity with the copper (Cu) brazing filler metal 14, the titanium (Ti) content in the alloy is set to 70.
It is preferably at% or more. For example, Ti-N
Compositions such as i and Ti-Zr can be used.

The shape and dimensions of the heat conducting metal plate 13 are preferably selected in consideration of the mechanical strength thereof and the distance between the semiconductor and the heat source. For example, as heat sources, various heat sources such as exhaust heat of automobiles and boilers, internal combustion such as residual heat of stoves, energy of external combustion equipment, and natural energy such as geothermal heat and solar heat can be assumed. When using devices or jigs that efficiently collect heat, the heat energy from these devices or jigs can be efficiently conducted and supplied to the semiconductor, depending on the device or jig, or integrated with them. Since the material, shape, etc. of the metal plate for heat conduction are appropriately selected to realize the above, the metal plate for heat conduction can take various forms. Of course, even when the thermoelectric conversion element itself is configured to be adapted to a heat collecting device or the like, the heat conducting metal plate can take various forms.

As the copper (Cu) -based brazing material 14 for joining and integrating the semiconductors 11 and 12 and the heat conducting metal plate 13, respectively, copper (Cu) or copper (Cu) containing 50 at% or more of copper (Cu) is used. Cu) -based alloy (for example, Cu-Ni alloy, Cu
-Ni-Zr alloy, etc.) is a so-called foil band brazing material made into a foil band by rolling or a liquid quenching method, and copper (Cu) is used as a core material and nickel (Ni) or nickel-copper (Ni-C) is provided on both main surfaces thereof.
u) A so-called three-layer composite foil brazing material made by pressure-bonding an alloy foil, a so-called powdered brazing material made of copper (Cu) powder or an alloy powder containing copper (Cu) as a main component, using these powders and an organic binder It is possible to use a copper (Cu) -based brazing material having various known forms such as a so-called paste-like brazing material formed into a paste. In any case, the copper (Cu) -based brazing material 14 is
P-type semiconductor 11, N-type semiconductor 12, and metal plate 1 for heat conduction
In order to improve the familiarity with 3 and to obtain the bonding strength to withstand use at high temperature, when the brazing filler metal having the above-mentioned various forms is melted, it is melted with the metal plate 13 for heat conduction. It is necessary that the function as a brazing filler metal is exhibited by diffusion, and in particular, in order to effectively realize mutual melting and diffusion, the thickness of the copper (Cu) -based brazing filler metal 14 at the time of interposing is 0. It is desirable to set it to 1 mm or less.

The thermoelectric conversion elements shown in FIGS. 2 to 8 are schematic explanatory views showing another embodiment of the present invention. In the thermoelectric conversion element of the present invention, since the semiconductors forming the thermoelectric conversion element are individually and independently manufactured, it is possible to make them into various shapes. FIG. 1 shows a structure in which each semiconductor is formed into a substantially prismatic shape, and is joined through a metal plate for heat conduction to form a substantially U-shaped thermoelectric conversion element, but in FIGS. 2 to 5, a cube is shown. Alternatively, the thermoelectric conversion element is configured by arranging semiconductors of rectangular parallelepiped (substantially cubic).

FIG. 2 shows an iron silicate (FeSi) composed of a rectangular parallelepiped.
₂ ), a P-type semiconductor 21 and an N-type semiconductor 22 are formed to form a PN junction through a heat conduction metal plate 23 made of a titanium (Ti) plate, and are joined to form a thermoelectric conversion element 20. There is. Reference numerals 25 and 25 are copper (C) which is bonded to the low temperature end side of the P-type semiconductor and the N-type semiconductor, respectively, and which also functions as a heat sink.
u) An electrode plate composed of a plate. The electrode plates 25, 25 have the thermoelectric conversion element 2 as in the embodiment shown in FIGS.
In order to facilitate electrical connection in a structure in which a plurality of 0s are connected, the open ends are joined so as to open at a predetermined angle. In this thermoelectric conversion element 20,
The P-type semiconductor 21 and the N-type semiconductor 22 and the heat conduction metal plate 23 are brazed and integrated with a copper (Cu) -based brazing material 24, and the power generation mechanism thereof is the thermoelectric conversion element 10 shown in FIG. It is similar to the case of. The P-type semiconductor 21
When the N-type semiconductor 22 and the electrode plates 25, 25 are joined, the temperature of the junction is relatively close to the PN junction and is relatively high compared to the configuration shown in FIG. A system active brazing material 26, 26 or the like is used.

When the heat source covers a relatively wide range, a larger amount of electric power can be obtained by connecting a plurality of the thermoelectric conversion elements 20 in series or in parallel. For example,
In the configuration shown in FIG. 3, the thermoelectric conversion elements 20a, 20b, 20c having the same configuration as the configuration shown in FIG. Electric power corresponding to the sum of the thermal energies conducted and supplied from the metal plates 23a, 23b, 23c can be taken out from both ends of the electrode plates 25a and 25c. In the figure, reference numeral 26 is a connecting member such as a rivet that electrically connects the electrode plates 25a, 25b, 25c of the thermoelectric conversion elements 20a, 20b, 20c.

In the configuration shown in FIG. 4, thermoelectric conversion elements 20d, 20e, 20f having the same configuration as the configuration shown in FIG.
Are vertically connected in a so-called vertical arrangement, and are in close proximity to or in contact with a heat source (not shown).
Electric power corresponding to the sum of the thermal energy conducted and supplied from e and 23f can be taken out from both ends of the electrode plates 25d and 25f.

In the thermoelectric conversion element 50 having the structure shown in FIG. 5, the thermoelectric conversion elements described so far are arranged so that the P-type semiconductor and the N-type semiconductor are vertically laminated with the metal plate for heat conduction interposed therebetween. In contrast to the configuration, a P-type semiconductor and an N-type semiconductor are provided on the same plane of a single heat conduction metal plate.
This is a configuration in which the type semiconductors are joined and arranged, and the same effects as those of the thermoelectric conversion element of the present invention described so far can be obtained. That is, one end of the single metal plate 53 for heat conduction has a narrow rectangular shape so as to efficiently approach or contact a heat source (not shown), and the P-type semiconductor 51.
The other end where the N-type semiconductor 52 and the N-type semiconductor 52 are joined and arranged has a wide square shape, and copper that also serves as a heat sink is provided on the low temperature end side (upper surface of the drawing) of the P-type semiconductor 51 and the N-type semiconductor 52, respectively. The electrode plates 55, 55 made of (Cu) plates are arranged in a joined state.

Also in this thermoelectric conversion element 50, a copper (Cu) -based brazing material 54 is used for joining the P-type semiconductor 51 and the N-type semiconductor 52 to the metal plate 53 for heat conduction, as in the configuration of FIG.
Further, the P-type semiconductor 51 and the N-type semiconductor 52 are joined to the electrode plates 55, 55 by brazing and integrating with a known titanium (Ti) -based active brazing material 56, 56. The thermal energy supplied from the heat source (not shown) is
It is conducted and supplied to the P-type semiconductor 51 and the N-type semiconductor 52 through the heat conduction metal plate 53, respectively. At this time, the semiconductors 51, 52 are bonded and arranged on the same plane of the heat conduction metal plate 53, and the PN is interposed via the heat conduction metal plate 53.
Since they are joined to form a junction, each semiconductor 5
It is possible to extract electric power from the low temperature end side of 1,52 (the upper surface in the drawing).

In any of the configurations shown in FIGS. 2 to 5,
The area of the electrode plate joined to the low temperature end side of the semiconductor is made relatively large so that it also serves as a heat sink.
Similar to the electrode plate 15 in the above configuration, the purpose is to increase the temperature difference between the heating portion (PN junction portion) and the open end of each semiconductor to improve the power generation efficiency. Further, by arranging the forced cooling means on these electrode plates, the effect can be further improved. 2 to 5
In the above configuration, the example in which the titanium (Ti) -based active brazing material is used for connecting the semiconductor and the electrode plate has been described, but the temperature on the open end side of each semiconductor is sufficiently increased due to the arrangement effect of the electrode plate. When the temperature is low, a brazing material having a low melting point such as zinc-tin (Zn-Sn) solder may be used as in the configuration of FIG.

The thermoelectric conversion element 60 having the structure shown in FIG. 6 is composed mainly of a ring-shaped iron sulfide (FeSi ₂ ).
Type semiconductors 61a, 61b, 61c and N type semiconductors 62a,
Heat conduction metal plates 63a, 63b, 63c, 63d, 63e made of ring-shaped titanium (Ti) plates alternately arranged on the inner and outer peripheral portions of 62b and 62c, respectively.
A PN junction is formed and joined through the above to form a cylindrical thermoelectric conversion element as a whole. 64a, 64b,
Reference numerals 64c, 64d, and 64e are copper (Cu) -based brazing materials for joining the semiconductor and the heat conductive metal base plate. Also, 6
5 and 65 are P-type semiconductors 61 located at the upper ends, respectively.
a, titanium (T
i) An electrode member joined by the active brazing filler metal 66.

In the cylindrical thermoelectric conversion element 60 having such a structure, the cylindrical member 67 arranged on the inner circumference thereof.
(For example, a ring-shaped heat-conducting metal plate that comes into contact with the outer peripheral surface of the cylindrical member 67 by using the temperature of the exhaust gas or the like that passes through the inside of an aluminum (Al) tube whose surface has been oxidized to improve electrical insulation) as a heat source. 63a, 63b, 63c to P-type semiconductor 61
a, 61b, 61c and N-type semiconductors 62a, 62b, 6
Electric power can be generated from the electrode members 65, 65 by generating electric power according to the thermal energy conducted and supplied to the 2c. In this structure, the ring-shaped heat conduction metal plate 63
Each of d and 63e does not directly contribute to the thermal energy supply to the semiconductor, but each plays the role of electrically connecting the electric power generated in the semiconductor in series.

The thermoelectric conversion element 70 having the structure shown in FIG. 7 is composed mainly of iron sulfide (FeSi ₂ ) having a rectangular plate shape.
Type semiconductors 71a, 71b, 71c and N type semiconductors 72a,
72b and 72c and metal plates 73a, 73b, 73c, 73d and 73 for heat conduction, which are rectangular plate-like titanium (Ti) plates alternately arranged at both ends at opposite positions.
A PN junction is formed via e and joined to form a rectangular parallelepiped thermoelectric conversion element as a whole. 74a, 74 in the figure
Reference numerals b, 74c, 74d, and 74e are copper (Cu) -based brazing materials for joining the semiconductor and the heat conduction metal plate. Further, 75 and 75 are electrode members joined to the P-type semiconductor 71a located at the upper end and the N-type semiconductor 72c located at the lower end by a titanium (Ti) -based active brazing material 76, respectively.

In the rectangular parallelepiped thermoelectric conversion element 70 having such a structure, a heat source (not shown) located on one outer peripheral surface side of the thermoelectric conversion element 70 (right side of the thermoelectric conversion element 70 in the drawing) is used. Of the heat energy from the metal plates 73a, 73b, 73c for heat conduction to the P-type semiconductors 71a, 71
b, 71c and the N-type semiconductors 72a, 72b, 72c can be conducted and supplied, electric power can be generated according to the thermal energy, and electric power can be taken out from the electrode members 75, 75. In this configuration, the heat conduction metal plates 73d and 73e do not directly contribute to the thermal energy supply to the semiconductors, but each plays a role of electrically connecting the electric power generated in the semiconductors in series.

The thermoelectric conversion element 80 shown in FIG. 8 has a structure in which a plurality of thermoelectric conversion elements 10 basically having the structure shown in FIG. 1 are arranged in parallel. That is, the P-type semiconductor 81a mainly composed of a plurality of iron sulfides (FeSi ₂ ),
...... 81z and N-type semiconductors 82a, ... 82z are made of titanium (Ti) plates, respectively, and are metal plates 83a for heat conduction.
A PN junction is formed and joined via 83z, and they are fixed by a heat radiating plate 86 and a heat receiving plate 87 to form a flat thermoelectric conversion element as a whole. 84a in the figure ... 8
4z is a copper (Cu) -based brazing material that joins the semiconductor and the metal plate for heat conduction. Also, 85 and 85 are heat sinks 8.
6 is an electrode member made of a copper (Cu) plate which is joined and integrated to the end portion of 6 with zinc-tin (Zn-Sn) solder. further,
Reference numeral 89 in the figure is a conductor wire for electrically connecting each P-type semiconductor 81a, ... 81z and N-type semiconductor 82a ,.

Heat sink 8 constituting this thermoelectric conversion element 80
Reference numeral 6 increases the temperature difference between the heating portion (PN junction portion) side and the open end side of the P-type semiconductors 81a, ... 81z and the N-type semiconductors 82a ,. .. 81z and N-type semiconductor 8 respectively
2a, ... 82z has a function of arranging and fixing at a predetermined position. For example, a material having good thermal conductivity such as an Al plate is subjected to alumite treatment in consideration of electric insulation and heat resistance. Use the applied one. Further, the heat receiving plate 87 causes heat energy supplied from a heat source (not shown) to efficiently act on the heat conducting metal plates 83a ... 83z, and through the heat conducting metal plates 83a. 81z and P-type semiconductors 81a, ... 81z and N-type semiconductors 82a ,.
Has a function of arranging and fixing at a predetermined position, and for example, a predetermined ceramic plate or the like is used in consideration of electrical insulation and heat resistance. In particular, the space portion 88 formed between the heat radiation plate 86 and the heat receiving plate 87 has a PN junction portion with the heat receiving portion (the tips of the heat conduction metal plates 83a ... 83z) by improving the air flow. It is possible to increase the temperature difference between and, and it is possible to improve the power generation efficiency. A known refrigerant can be passed through the space 88, if necessary.

Also in the thermoelectric conversion element 80 described above, the heat energy supplied from the heat source (not shown) is
.. 81z and N type semiconductors 82a, .. .8 through the heat conducting metal plates 83a ..
2z is conducted and supplied to the P-type semiconductors 81a, ... 8 respectively.
It is possible to extract electric power from the low temperature end side (upper surface of the drawing) of the 1z and the N-type semiconductors 82a, ... 82z. Since this thermoelectric conversion element 80 electrically connects a large number of P-type semiconductors 81a, ... 81z and N-type semiconductors 82a ,. The configuration of the present invention can be effectively utilized by disposing it on the wall surface of a chimney or the like for dust disposal, the muffler of an automobile, or the like.

[0039]

EXAMPLE A thermoelectric conversion element 10 of the present invention shown in FIG.
By measuring the load characteristics with the conventional thermoelectric conversion element 1 shown in FIG. 9, it was confirmed that the thermoelectric conversion element 10 of the present invention was excellent. In order to obtain the thermoelectric conversion element 10 of the present invention shown in FIG. 1, the following constituent members were prepared. Sintered body for P-type semiconductor 11 and sintered body for N-type semiconductor 12 mainly composed of iron silicide (FeSi ₂ ) Composition (wt%): P type → Fe _43.5 Mn ₄ Si _52.5 N
Mold → Fe _44.5 Co _3.5 Si _51.5 Dimensions: height 4 mm x width 4 mm x length 20 mm Heat conduction metal plate 13 Material: Titanium (Ti) plate Dimensions: Thickness 0.5 mm x width 5 mm x length 10 mm Copper (Cu ) System brazing material 14 Structure: Cu Dimensions: Thickness 0.08 mm x width 3 mm x length 5 mm Melting point: 900 ° C Electrode 15 Material: Copper (Cu) plate Dimensions: thickness 0.5 mm x width 3 mm x length 10 mm

The above-mentioned sintered bodies for semiconductors 11 and 12 and the metal plate 13 for heat conduction are provided with a copper (Cu) -based brazing material 14 in between.
In a state of being positioned by applying a predetermined pressure,
They were integrated by brazing under the condition of 00 ° C. × 15 min. After that, a predetermined temperature (750 ° C. × 10
(0 hr), semiconductor treatment was performed, and after cooling, the electrode 15 was joined with Zn—Sn solder at 250 ° C. to obtain the thermoelectric conversion element 10 of the present invention.

As the conventional thermoelectric conversion element 1, a pair of semiconductors integrally molded by the conventional powder metallurgy method has the same composition and the same dimensions as the thermoelectric conversion element 10 of the present invention. As shown in FIGS. 1 and 10, an ammeter 5, a voltmeter 6, and a variable resistor 7 are connected to each thermoelectric conversion element 10 and 1, and in the thermoelectric conversion element 10 of the present invention, the metal plate 13 for heat conduction is Further, in the conventional thermoelectric conversion element 1, the semiconductor PN junction is heated by the torch (about 800 ° C.).
By doing so, the respective load characteristics were measured, and the characteristics shown in FIG. 9 were obtained. It is clear from FIG. 9 that the load characteristics of the thermoelectric conversion element 10 of the present invention are superior to the load characteristics of the conventional thermoelectric conversion element 1, and the power generation capacity (conversion efficiency) of the thermoelectric conversion element 10 of the present invention is It was confirmed to be high.

[0042]

According to the thermoelectric conversion element of the present invention, a P-type semiconductor mainly composed of iron silicide (FeSi ₂ ) and an N-type semiconductor are used.
A metal plate for heat conduction made of titanium (Ti) or a titanium (Ti) alloy is arranged as a heat energy supply source at the junction of the semiconductors, and heat energy is continuously and efficiently supplied from heat sources located outside each semiconductor. Therefore, it is possible to prevent the generation of electron-hole pairs from being reduced due to the Peltier effect, and it is possible to improve power generation efficiency. In the case of the conventional direct heating type, since the elements other than the joint portion are heated, the element becomes longer to separate the cold junction portion and the internal resistance increases, but in the thermoelectric conversion element of the present invention, the heat is a metal for heat conduction. Since it is supplied by heating the plate and only the PN junction is heated, a temperature difference is obtained near the cold junction, the internal resistance is reduced, and the power generation capacity is significantly improved.

Further, since the P-type semiconductor and the N-type semiconductor are manufactured separately and are joined through the metal plate for heat conduction, mixing of the alloy powder for semiconductor in the PN junction as in the conventional structure occurs. In this way, stable electric power can be taken out without deterioration of characteristics or variation of electric characteristics at the PN junction. Furthermore, since it is possible to manufacture the P-type semiconductor and the N-type semiconductor separately, the manufacturing method (filling-molding step) becomes easy,
The configuration has excellent mass productivity. Further, since individual shapes of the P-type semiconductor and the N-type semiconductor can be arbitrarily manufactured according to the application, it is possible to provide the thermoelectric conversion element having various configurations as shown in the examples. Therefore, the applications of these thermoelectric conversion elements can be further expanded.

In the thermoelectric conversion element of the present invention, a heat radiating plate made of a copper (Cu) plate or the like is joined to the low temperature end side of each semiconductor to form a semiconductor heating portion (PN junction portion) and a low temperature end side. It is possible to widen the temperature difference and the power generation efficiency is further improved. Since each member constituting the thermoelectric conversion element is joined and integrated with a copper (Cu) -based brazing material having a relatively high melting point, it can withstand use in a high temperature atmosphere and is mainly composed of iron silicide (FeSi ₂ ). It is also one of the great effects that the heat resistance characteristic of semiconductors can be effectively utilized, and is particularly effective as a thermal sensor in the temperature range of 400 ° C. to 900 ° C. and as a power source.

As described above, the thermoelectric conversion element of the present invention has many advantages. For example, by disposing the thermoelectric conversion element in the vicinity of the stove or the stove, the fan motor can be rotated based on these operations, By using the exhaust heat energy of the car to operate the linear actuator to drive various parts, for example, the thermoelectrically converted electric power is stored in a battery or the like and the battery is used as the power source, or the generated power is used directly. It can be used to operate electronic devices and be used for many purposes. In addition to the exhaust heat of automobiles and boilers, the residual heat of the stove, it is also possible to utilize natural energy such as geothermal heat and solar heat as the heat source, and high heat can be generated by using various heat collecting jigs and devices. It is possible to operate many electronic devices by transferring heat to the high thermal conductive metal plate of.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional explanatory view showing one structural example of a thermoelectric conversion element of the present invention.

2A and 2B are explanatory views showing another configuration example of the thermoelectric conversion element of the present invention, in which a is a top view and b is a longitudinal section.

FIG. 3 is an explanatory top view showing another configuration example of the thermoelectric conversion element of the present invention.

FIG. 4 is a vertical cross-sectional explanatory view showing another configuration example of the thermoelectric conversion element of the present invention.

5A and 5B are explanatory views showing another configuration example of the thermoelectric conversion element of the present invention, in which a is a top view and b is a longitudinal section.

FIG. 6 is a transverse cross-sectional view showing another configuration example of the thermoelectric conversion element of the present invention.

FIG. 7 is a vertical cross-sectional explanatory view showing another configuration example of the thermoelectric conversion element of the present invention.

8A and 8B are explanatory views showing another configuration example of the thermoelectric conversion element of the present invention, in which a is a top view and b is a longitudinal section.

FIG. 9 is a load characteristic curve diagram showing the results of measuring the load characteristics of the thermoelectric conversion element of the present invention and the conventional thermoelectric conversion element.

FIG. 10 is a schematic explanatory diagram of a conventional thermoelectric conversion element.

[Explanation of symbols]

1, 10, 20, 20a, 20b, 20c, 20d, 2
0e, 20f, 50, 60, 70, 80 Thermoelectric conversion element 2, 11, 21, 51, 61a, 61b, 61c, 71
a, 71b, 71c, 81a P-type semiconductor 3, 12, 22, 52, 62a, 62b, 62c, 72
a, 72b, 72c, 82a N-type semiconductor 4 PN junction part 5 Ammeter 6 Voltmeter 7 Variable resistance 13, 23, 23a, 23b, 23c, 23d, 23
e, 23f, 53, 63a, 63b, 63c, 63d,
63e, 73a, 73b, 73c, 73d, 73e, 8
3a Metal plate for heat conduction 14, 24, 54, 64a, 64b, 64c, 64d,
64e, 74, 74a, 74b, 74c, 74d, 74
e, 84a Copper (Cu) brazing material 15, 25, 25a, 25c, 25d, 25f, 55,
65,75,85 Electrode plate 16,26,56,66,76 Brazing material 26 Connection member 67 Cylindrical member 86 Radiating plate 87 Heat receiving plate 88 Space part

Claims (1)

[Claims] 1. A P containing iron sulfide (FeSi ₂ ) as a main component.
In a thermoelectric conversion element having a structure in which a p-type semiconductor and an n-type semiconductor are pn-junctioned, titanium (T
A thermoelectric conversion element characterized in that a PN junction is formed by brazing a copper (Cu) -based brazing material with a metal plate for heat conduction made of i) or a titanium (Ti) alloy interposed.