JPH11307828A - Thermoelectric conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of the durability of an O-ring provided on an insulating substrate by preventing the occurrence of delamination between the insulating substrate and electrodes and between the electrodes and a thermoelectric element. SOLUTION: A plurality of thin lower electrodes is arranged on a heat absorbing-side insulating substrate 1b having a circular surface in such a state that the electrodes 3 are stuck to the surface of the substrate 1b with a heat- resistance adhesive. Then a pair of p- and n-type thermoelectric elements 2a and 2b is bonded to each lower electrode 3 with solder layers. In addition, the upper ends of the elements 2a and 2b are respectively connected to p- and n-type thermoelectric elements 2a and 2b arranged on adjacent lower electrodes 3 by soldering upper electrodes to the elements 2a and 2b. In other words, the p- and n-type thermoelectric elements 2 and 2b are alternately connected to each other through the lower electrodes 3 and upper electrodes. In addition, a heat radiating-side insulating substrate 1a having a circular surface is stuck to the upper surfaces of the upper electrodes with a heat-resistant adhesive.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoelectric conversion device utilizing the Peltier effect, and more particularly to a thermoelectric conversion device in which peeling at a joint between an insulating substrate and an electrode due to thermal stress is prevented.

[0002]

2. Description of the Related Art When two materials of different types are joined to form a circuit having two joints, one of the joints is heated to a high temperature, and the other is cooled to a low temperature. An electromotive force is generated based on the difference. This phenomenon is called the Seebeck effect.

[0003] When a direct current is applied to two materials that are similarly joined, heat is absorbed at one joint and heat is generated at the other joint. This phenomenon is called the Peltier effect.

Further, when a temperature gradient is provided in a homogeneous substance and an electric current flows in a direction in which the temperature gradient is present, heat is absorbed or generated in the substance. This phenomenon is called the Thomson effect.

[0005] These Seebeck effect, Peltier effect and Thomson effect are reversible reactions called thermoelectric effects.
Contrast with irreversible phenomena such as Joule effect and heat conduction.
A combination of these reversible and irreversible processes is used for electronic cooling and heating.

FIG. 4 is a schematic diagram showing a conventional thermoelectric converter. In a conventional thermoelectric conversion device, a plurality of thin plate-like lower electrodes 13b are provided on a heat-dissipation-side insulating substrate 11b having a square plate surface and bonded by a heat-resistant adhesive (not shown). A pair of a p-type thermoelectric element 12a and an n-type thermoelectric element 12b are joined on each lower electrode 13b by a solder layer (not shown). Further, the upper end of the p-type thermoelectric element 12a is connected to the n-type thermoelectric element 12b disposed on the adjacent lower electrode 13b by joining the upper electrode 13a with a solder layer (not shown). The upper end of 12b is adjacent to another lower electrode 13b.
The upper electrode 13a is connected to the p-type thermoelectric element 12a disposed above by joining the upper electrode 13a with a solder layer. The p-type thermoelectric element 12a and the n-type thermoelectric element 12b are alternately connected in series by the lower electrode 13b and the upper electrode 13a. In this way, a Peltier element is constituted by the p-type thermoelectric element 12a, the n-type thermoelectric element 12b, the upper electrode 13a, and the lower electrode 13b. On the upper electrode 13a, a heat-absorbing-side insulating substrate 11a having a square plate surface is provided by being bonded with a heat-resistant adhesive (not shown). Further, the upper electrodes 13 disposed at both ends of the series connection body of the thermoelectric element
a or a lower electrode 13b is connected to a lead wire (not shown). As the heat-dissipating insulating substrate 11b and the heat-absorbing insulating substrate 11a, an alumina plate or an aluminum plate subjected to alumite treatment is used.

In the conventional thermoelectric converter configured as described above, when a current flows through the lead wire from a predetermined direction, heat is generated at the lower electrode 13b and absorbed by the upper electrode 13a. Thereby, the space or the object in contact with the outer surface of the heat-absorbing insulating substrate 11a is cooled, and the space or the object in contact with the outer surface of the heat-radiating insulating substrate 11b is heated.

[0008]

However, when the above-described conventional thermoelectric conversion device is used, the device is deformed due to thermal stress, and the junction between the insulating substrate and the electrode, and the junction between the electrode and the thermoelectric element is deformed. There is a problem that peeling occurs.

FIGS. 5A and 5B are views showing a modified conventional thermoelectric converter, in which FIG. 5A is a schematic view and FIG. 5B is a sectional view.
In the conventional thermoelectric conversion device, the heat radiation side insulating substrate 11b
In general, the heat-dissipating insulating substrate 11b expands and the heat-absorbing insulating substrate 11a contracts, although there is a difference depending on the linear expansion coefficient of the material of the heat-absorbing insulating substrate 11a. The displacement from the position before the deformation increases as the distance from the center increases, and the displacement at the corner becomes maximum. For this reason, peeling may occur at the joint between the insulating substrate and the electrode and between the electrode and the thermoelectric element.

In some cases, an O-ring for sealing is disposed on the outer surface of the insulating substrate on the radiating side in order to flow a coolant for cooling the insulating substrate on the radiating side.
An uneven load is applied to the ring, and the durability of the O-ring deteriorates. As described in JP-A-6-207762, an O-ring may be interposed between insulating substrates in order to prevent corrosion of the Peltier element due to dew condensation or the like. Easy to deteriorate. When the sealing O-ring is deteriorated, the refrigerant may flow out therefrom. The same may occur on the endothermic side.

The present invention has been made in view of such a problem, and can prevent the insulating substrate and the electrode, and the electrode and the thermoelectric element from peeling due to thermal stress, and can provide a durable O-ring provided on the insulating substrate. It is an object of the present invention to provide a thermoelectric conversion device capable of preventing deterioration of performance.

[0012]

A thermoelectric conversion device according to the present invention comprises a plurality of Peltier elements having a Peltier effect;
A heat-dissipation-side insulating substrate in the form of a disc or a polygonal plate having six or more corners disposed on the heat-dissipating side of the Peltier element; A heat absorbing side insulating substrate having a rectangular plate shape.

In the present invention, since the heat-dissipating-side insulating substrate and the heat-absorbing-side insulating substrate have a disk shape or a polygonal plate shape having six or more corners, the deformation of the thermoelectric converter is substantially reduced in the circumferential direction. It becomes uniform uniformly. Therefore, peeling is less likely to occur at the junction between the insulating substrate and the electrode and between the electrode and the thermoelectric element due to thermal stress. Also, when an O-ring is interposed between the insulating substrates or disposed on the outer surface of the insulating substrate,
The deterioration of the durability of the O-ring is prevented.

[0014] The polygonal plate may be a regular polygonal plate.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of intensive experiments and research conducted by the present inventors in order to solve the above-mentioned problems, the shape of an insulating substrate arranged on the heat radiation side or heat absorption side of a plurality of Peltier devices has been changed to a circular shape or a circular shape. By making the shape of a polygonal plate having six or more corners, as described above, peeling at the joint between the insulating substrate and the electrode, and between the electrode and the thermoelectric element is prevented, and the durability of the O-ring disposed on the insulating substrate is improved. It has been found that deterioration can be prevented.

Hereinafter, a thermoelectric converter according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing a thermoelectric converter according to an embodiment of the present invention.

In the thermoelectric converter according to the present embodiment,
A plurality of thin plate-like lower electrodes 3b are provided on a heat-dissipation-side insulating substrate 1b having a circular plate surface and bonded with a heat-resistant adhesive (not shown). A pair of a p-type thermoelectric element 2a and an n-type thermoelectric element 2b are joined on each lower electrode 3b by a solder layer (not shown). Further, the upper end of the p-type thermoelectric element 2a is connected to the n-type thermoelectric element 2b disposed on the adjacent lower electrode 3b by joining the upper electrode 3a with a solder layer (not shown). The upper end of 2b is connected to the p-type thermoelectric element 2a arranged on another adjacent lower electrode 3b by joining the upper electrode 3a with a solder layer. The p-type thermoelectric element 2a and the n-type thermoelectric element 2b are alternately connected in series by the lower electrode 3b and the upper electrode 3a. In this way, a Peltier element is constituted by the p-type thermoelectric element 2a, the n-type thermoelectric element 2b, the upper electrode 3a and the lower electrode 3b. On the upper electrode 3a, a heat-absorbing insulating substrate 1a having a circular plate surface is provided by being bonded with a heat-resistant adhesive (not shown). Further, a lead wire (not shown) is connected to the upper electrode 3a or the lower electrode 3b disposed at both ends of the series connection body of the thermoelectric elements.

In the thermoelectric converter of the present embodiment thus configured, when a current flows through the lead wire from a predetermined direction, heat is generated at the lower electrode 3b and absorbed by the upper electrode 3a. . As a result, the space or object that is in contact with the outer surface of the heat-absorbing insulating substrate 1a is cooled, and the space or the object that is in contact with the outer surface of the heat-radiating insulating substrate 1b is heated.

Then, the heat radiating side insulating substrate 1b expands, and the heat absorbing side insulating substrate 1a contracts. FIG. 2 is a schematic diagram showing a modified thermoelectric converter according to an embodiment of the present invention. In this embodiment, since the heat-radiating-side insulating substrate 1b and the heat-absorbing-side insulating substrate 1a are disk-shaped, the displacement from before the deformation increases toward the periphery in the radial direction, but is uniform in the circumferential direction. Become. Accordingly, peeling at the junction between the insulating substrate and the electrode and between the electrode and the thermoelectric element due to thermal stress, which has conventionally occurred, is prevented. Further, even when the O-ring is arranged between the heat-radiating-side insulating substrate 1b and the heat-absorbing-side insulating substrate 1a or on the surface of the heat-radiating-side insulating substrate 1b, the load applied to the O-ring becomes uniform. Deterioration of durability is prevented.

Next, a method of manufacturing the above-described thermoelectric converter of the present embodiment will be described. First, a thermoelectric element and an insulating substrate are separately manufactured.

The thermoelectric element is manufactured as follows.
First, a powder of an n-type semiconductor or a p-type semiconductor is hot-pressed to form a compact. Next, the molded body is cut into a thickness for maintaining a predetermined temperature difference when assembled into a Peltier element, for example, 1.6 mm. Next, a plating layer of, for example, Ni or the like is formed on both cut surfaces of the cut compact to improve solderability. And it cuts further in the direction perpendicular | vertical to both cut surfaces, and is processed into a desired shape, for example, a rectangular parallelepiped thermoelectric element whose side length is 1.4 mm.

On the other hand, the insulating substrate is manufactured by forming an alumina plate into a circular shape and then metallizing the alumina plate formed into a circular shape using a metal material such as a Mo—Mn alloy material or a Cu material. Is done.

Then, for example, a rectangular electrode made of Cu is formed at a predetermined position on the insulating substrate by patterning. The length of one side of the electrode is, for example, 1.6 mm,
The length of the other side is, for example, 7 mm. Further, cream solder is applied on the electrodes. Next, a thermoelectric element manufactured separately is sandwiched between the electrodes formed on the two insulating substrates. Each member is joined by being heated in a soldering furnace. Thereafter, necessary lead wires and the like are provided, and the thermoelectric conversion device is completed.

As the heat-dissipating insulating substrate and the heat-absorbing insulating substrate, the above-mentioned alumina plate, an aluminum plate subjected to anodizing by anodization, or a flexible substrate made of resin and the like can be used. . When anodized aluminum plate is used,
For example, a Cu electrode is bonded with an epoxy resin or the like.

Further, the shapes of the heat-radiating-side insulating substrate and the heat-absorbing-side insulating substrate are not limited to disk shapes, and the number of corners is six.
The above polygonal plate shape may be used. FIG. 3 is a schematic diagram showing a thermoelectric conversion device according to an embodiment in which a hexagonal plate-shaped insulating substrate is used. In the embodiment in which the hexagonal plate-shaped insulating substrate shown in FIG. 3 is used, the same components as those in the embodiment shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. In the present embodiment, the lower electrode 3b, the upper electrode 3a, and the like are arranged between the heat dissipation side insulating substrate 21a and the heat absorbing side insulating substrate 21a in the same manner as the embodiment shown in FIG. .

In the present embodiment thus constructed, the heat-dissipating insulating substrate 21b expands and the heat-absorbing insulating substrate 21a contracts due to use. However, since the number of corners is large, the displacement from before the deformation is limited. The direction is substantially uniform. Therefore, as described above, peeling due to thermal stress is prevented, and even when an O-ring is provided, deterioration of its durability is prevented.

As described above, even when the heat-radiating-side insulating substrate and the heat-absorbing-side insulating substrate are in the shape of a polygonal plate having six or more corners, the thermoelectric device is expanded due to the expansion of the heat-radiating-side insulating substrate and the contraction of the heat-absorbing-side insulating substrate. Even if the conversion device is deformed, the displacement in the circumferential direction from before the deformation becomes substantially uniform. For this reason, separation at the joint between the insulating substrate and the electrode and between the electrode and the thermoelectric element is prevented, and even when the O-ring is provided on the insulating substrate, deterioration of the durability is prevented. Especially,
When the polygonal plate is a regular polygonal plate, the effect is high.

Furthermore, the arrangement of the thermoelectric elements in the thermoelectric conversion device is not particularly limited. For example, as in the related art, the electrodes may be arranged orthogonally to each other, and the electrodes may be long, but a point-symmetrical arrangement with the center of the insulating substrate as the point of symmetry is also possible. Further, a thermoelectric element that forms a pair may be arranged in a spiral shape. In this case, if a cooling fan or the like is used for cooling the heat radiation side insulating substrate, the heat radiation effect is improved.

[0029]

As described in detail above, according to the present invention,
Since the shape of the heat-dissipating-side insulating substrate and the heat-absorbing-side insulating substrate is a disk shape or a polygonal plate shape having six or more corners, the deformation of the thermoelectric converter becomes substantially uniform in its circumferential direction,
Separation at the joint between the insulating substrate and the electrode and between the electrode and the thermoelectric element can be prevented. Further, even when the O-ring is interposed between the insulating substrates or is arranged on the outer surface of the insulating substrate, it is possible to prevent the durability of the O-ring from deteriorating.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a thermoelectric conversion device according to an embodiment of the present invention.

FIG. 2 is a schematic view showing a modified thermoelectric converter according to an embodiment of the present invention.

FIG. 3 is a schematic diagram illustrating a thermoelectric conversion device according to an embodiment using a hexagonal plate-shaped insulating substrate.

FIG. 4 is a schematic diagram showing a conventional thermoelectric converter.

5A and 5B are diagrams showing a modified conventional thermoelectric conversion device, wherein FIG. 5A is a schematic diagram and FIG. 5B is a cross-sectional view.

[Explanation of symbols]

1a, 11a, 21a; heat absorbing side insulating substrate, 1b, 11
b, 21b; heat radiation side insulating substrate, 2a, 12a; p-type thermoelectric element, 2b, 12b; n-type thermoelectric element, 3a, 13
a: upper electrode, 3b, 13b; lower electrode

Claims (4)

[Claims] 1. A plurality of Peltier elements having a Peltier effect, a disc-shaped heat-dissipating-side insulating substrate arranged on the heat-dissipating side of the Peltier element, and a disc-shaped insulating board disposed on the heat-absorbing side of the Peltier elements. A thermoelectric conversion device comprising: a heat absorbing side insulating substrate. 2. A plurality of Peltier elements having a Peltier effect, and six Peltier elements arranged on a heat radiation side of the Peltier element have a square number of six.
A thermoelectric conversion device comprising: the above-mentioned heat dissipation side insulating substrate in the shape of a polygonal plate; and the heat absorption side insulating substrate in the shape of a polygonal plate having a square number of 6 or more, which is arranged on the heat absorption side of the Peltier element. 3. A thermoelectric device comprising: a plurality of Peltier elements having a Peltier effect; a heat-dissipating-side insulating substrate disposed on a heat-dissipating side of the Peltier element; and a heat-absorbing-side insulating substrate disposed on a heat-absorbing side of the Peltier element. In the converter, one of the heat-radiating-side insulating substrate and the heat-absorbing-side insulating substrate has a disk shape, and the other has a polygonal plate shape having six or more corners. 4. The thermoelectric conversion device according to claim 2, wherein the polygonal plate is a regular polygonal plate.