JP4288935B2 - Thermoelectric module - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermoelectric module that performs thermoelectric conversion.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, thermoelectric modules that perform heat conversion using the Peltier effect, which is one of thermoelectric conversions, have been used in heating / cooling devices and the like (for example, see Patent Document 1). In this thermoelectric module, a plurality of electrodes are formed at predetermined locations on opposite inner surfaces of a pair of insulating substrates, and the upper and lower end faces of the thermoelectric elements are soldered to the opposite electrodes, respectively. A plurality of thermoelectric elements are fixed between the substrates. In this case, the pair of insulating substrates are formed in a square plate shape, and the thermoelectric element is a thermoelectric element group composed of a plurality of thermoelectric elements between the pair of insulating substrates so that the outer periphery thereof is along the outer periphery of the insulating substrate. For example, they are arranged in a lattice pattern with a constant interval left and right.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-232028
[Problems to be solved by the invention]
In the thermoelectric module described above, one insulating substrate of the pair of insulating substrates expands by heating, and the other insulating substrate contracts by cooling. For this reason, the thermoelectric module may be deformed due to thermal stress, causing separation between the electrode and the thermoelectric element, or destroying the thermoelectric element, so that the thermoelectric module may not function.
[0005]
In order to avoid this problem, in conventional thermoelectric modules, the electrodes and thermoelectric elements are connected in parallel so that the thermoelectric modules can function even if some of the thermoelectric elements break down, or placed in a place where they are easily broken The thickness of the thermoelectric element to be set is made large so that it is difficult to break. However, this has a problem that the design and manufacture of the thermoelectric module becomes complicated.
[0006]
Summary of the Invention
The present invention has been made to address the above problems, and its purpose is to provide a thermoelectric module with improved durability by preventing the thermoelectric element from peeling or breaking from the insulating substrate by a simple method. It is to be.
[0007]
In order to achieve the above object, the constitutional feature of the thermoelectric module according to the present invention is that electrodes are formed at predetermined positions on both sides of a pair of square plate-like insulating substrates arranged to face each other, and the electrodes facing each other. the by fixing the end faces of the thermoelectric elements, respectively, in the thermoelectric module configured to place the thermoelectric element group including a plurality of thermoelectric elements between the pair of insulating substrates, a thermoelectric element group, the outer periphery of the insulating substrate It is arranged in a square shape along the outer periphery, and no thermoelectric elements are arranged in the four corner portions of the square shape .
[0008]
In the thermoelectric module of the present invention, a thermoelectric element group composed of a plurality of thermoelectric elements is disposed between a pair of insulating substrates formed in a square plate shape so that the outer periphery thereof is along the outer periphery of the insulating substrate, and the pair of insulating substrates Thermoelectric elements are not arranged at the four corners. In the thermoelectric module, as the distance from the central portion of the insulating substrate increases, the stress generated from the expansion of one insulating substrate and the contraction of the other insulating substrate increases.
[0009]
For this reason, the thermoelectric elements arranged at the four corners farthest from the center of the pair of insulating substrates are more likely to be peeled off or broken from the insulating substrate than the other thermoelectric elements, and the durability of the thermoelectric module is In many cases, it is determined by the breakage state of the thermoelectric element arranged in the portion. Therefore, by not disposing the thermoelectric elements at the four corner portions, there is no thermoelectric element that is most likely to be peeled off or broken, and the durability of the thermoelectric module can be improved. In this case, the number of thermoelectric elements that are not arranged at the four corners of the pair of insulating substrates is not limited to one for each corner, but may be plural.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 and 2 (a front view of FIG. 1) show a thermoelectric module 10 according to the present embodiment. The thermoelectric module 10 includes a pair of insulating substrates made of a rectangular lower plate insulating substrate 11 and an upper insulating substrate 12 made of alumina. Then, a plurality of lower electrodes 13 and 14 (see FIG. 3) are attached to the upper surface of the lower insulating substrate 11 at regular intervals, and a plurality of upper electrodes 15 are attached to the lower surface of the upper insulating substrate 12 at regular intervals. It has been.
[0011]
A plurality of thermoelectric elements 16 made of a bismuth-tellurium-based alloy formed in a rectangular parallelepiped are fixed to the lower electrodes 13 and 14 by soldering at the lower end surfaces and fixed to the upper electrode 15 by soldering, respectively. The lower insulating substrate 11 and the upper insulating substrate 12 are integrally connected.
[0012]
FIG. 3 shows a state in which the lower insulating substrate 11 to which the lower electrodes 13 and 14 and the thermoelectric element 16 are attached is viewed from above. As shown, the lower electrode 13 is formed in a rectangular shape, and the lower electrode 14 is formed in an L shape. An L-shaped lower electrode 14 is attached to two of the four corners of the lower insulating substrate 11 along the corner, and a rectangular lower electrode 13 is attached to the other part.
[0013]
Moreover, lead wires 17a and 17b are attached to one end of the lower electrode 13 provided at the remaining two corners of the four corners, and can be energized from the outside. And the lower end surface of one thermoelectric element 16 (16a) is joined to the other end of the lower electrode 13 attached to the corner of the lower insulating substrate 11, and the other lower electrodes 13 The lower end surfaces of the two thermoelectric elements 16 are joined.
[0014]
The upper electrodes 15 are all formed in the same rectangular shape as the lower electrode 13, and are attached to the upper insulating substrate 12 with a distance equal to approximately one thermoelectric element 16 from the lower electrode 13. Yes. Then, two upper end surfaces of the thermoelectric elements 16 are joined to each upper electrode 15 so that each thermoelectric element 16, the lower electrodes 13, 14 and the upper electrode 15 are connected in series. That is, the upper end surfaces of the thermoelectric elements 16a and 16b in FIG. 3 are joined to one upper electrode 15, and the upper end surfaces of the next thermoelectric elements 16c and 16d are joined to the adjacent upper electrode 15 in sequence. The adjacent thermoelectric elements 16 are joined to the upper electrode 15 every other piece.
[0015]
The thermoelectric element 16 (including the thermoelectric elements 16a, 16b, 16c, and 16d) is composed of a P-type thermoelectric element and an N-type thermoelectric element, and the P-type thermoelectric element and the N-type thermoelectric element are alternately arranged. Has been placed. The P-type thermoelectric element and the N-type thermoelectric element contain the same Bi or Te, but have slightly different compositions. However, as shown in FIG. 3, the thermoelectric elements 16 are not provided at the corners of the four corners of the lower insulating substrate 11 (and the upper insulating substrate 12). The thermoelectric module 10 has a vertical and horizontal length of 12 mm and a height of 1.65 mm, and the thermoelectric element 16 has a vertical and horizontal width of both upper and lower end surfaces set to 0.8 mm. Is set to 1 mm. The thermoelectric element 16 is composed of 30 pairs, one adjacent P-type thermoelectric element and one N-type thermoelectric element.
[0016]
Next, the results of a power cycle test performed on the thermoelectric module 10 configured as described above and the thermoelectric module 20 according to the comparative example illustrated in FIG. 4 will be described. FIG. 4 shows a state where the lower insulating substrate 21 to which the lower electrode 23 and the thermoelectric element 26 are attached is viewed from above. In the thermoelectric module 20, the lower electrode 23 and the upper electrode of the lower insulating substrate 21 are shown. All the upper electrodes (not shown) of the insulating substrate are formed in a rectangular shape. The lower electrode 23 and the upper electrode of the upper insulating substrate are attached to each other with a distance equal to approximately one thermoelectric element 26.
[0017]
Further, only one thermoelectric element 26 is joined to the lower electrode 23 to which the lead wires 27a and 27b are connected, and the other lower electrode 23 and the upper electrode are connected to the lower end surface or upper surface of the two thermoelectric elements 26. The end faces are joined. Further, in this thermoelectric module 20, the thermoelectric element 26 is not disposed at the corners of the lower insulating substrate 21 and the upper insulating substrate where the lower electrode 23 to which the lead wires 27a and 27b are connected is located. , 31 pairs.
[0018]
Moreover, the length of each part of the thermoelectric module 20 is set to the same length as each corresponding part of the thermoelectric module 10, and the thermoelectric module 20 has a length and width of 12 mm and a height of 1.65 mm. The thermoelectric element 26 is set such that the vertical and horizontal widths of the upper and lower end faces are both 0.8 mm and the height is 1 mm. The lower insulating substrate 21 and the upper insulating substrate are made of a plate made of alumina, and the thermoelectric element 26 is made of a bismuth-tellurium-based alloy formed in a rectangular parallelepiped.
[0019]
In the power cycle test, as shown in FIG. 5, the thermoelectric module 10 (or 20) is placed on a copper base 28 coated with grease on the surface, and the temperature of the base 28 is heated (not shown). This was performed while maintaining the temperature at 80 ° C. by the heating control. At that time, the operation of stopping the current for 4.5 minutes after passing the current of 3 amperes, which is the maximum current of the thermoelectric modules 10 and 20, to the thermoelectric modules 10 and 20 for 1.5 minutes. Repeatedly, the electric resistance change rate of the thermoelectric modules 10 and 20 before and after the power cycle test was compared.
[0020]
As a result, the electric resistance change rate of the thermoelectric module 10 was 2.4%, whereas the electric resistance change rate of the thermoelectric module 20 was 3.8%. From this result, it can be seen that the thermoelectric module 10 in which the thermoelectric elements 16 are not provided in all the four corners is more durable than the thermoelectric module 20 in which the thermoelectric elements 26 are not provided only in the two corners. Recognize. Note that the electrical resistance of the thermoelectric module 10 and the like changes from the initial stage so as to increase with deterioration due to use, high-temperature heating, or the like. Therefore, a thermoelectric module in which the electrical resistance does not change or does not change even after long-term use is superior in durability.
[0021]
Next, the dimensions of the thermoelectric modules 10 and 20 are changed, the vertical and horizontal lengths of the thermoelectric modules 10 and 20 are set to 8 mm, the height is set to 1.65 mm, and the vertical and horizontal surfaces at the upper and lower end faces of the thermoelectric elements 16 and 26 are set. Both of the widths were set to 0.6 mm and the height was set to 0.8 mm. That is, only the height of the thermoelectric modules 10 and 20 was set to be the same as that of the test sample used in the power cycle test described above, and all other dimensions were set to be small. And the power cycle test mentioned above was done by making these both thermoelectric modules 10 and 20 into a test sample.
[0022]
As a result, the rate of change in electrical resistance of the thermoelectric module 10 was 2.2%, and the rate of change in electrical resistance of the thermoelectric module 20 was 2.6%. From this result, it can be seen that the thermoelectric module 10 has higher durability than the thermoelectric module 20 according to the comparative example. It can also be seen that the durability is improved by reducing the dimensions of the thermoelectric modules 10 and 20.
[0023]
Next, the dimensions of the thermoelectric modules 10 and 20 are further changed, the vertical and horizontal lengths of the thermoelectric modules 10 and 20 are set to 8 mm, the height is set to 1.4 mm, and the upper and lower end faces of the thermoelectric elements 16 and 26 are set. Both the vertical and horizontal widths were set to 0.6 mm and the height was set to 0.6 mm. That is, the height of the thermoelectric modules 10 and 20 and the height of the thermoelectric elements 16 and 26 were set smaller than the test sample used in the second power cycle test described above, and the dimensions of the other portions were set to be the same. Then, a power cycle test similar to the power cycle test described above was performed using the thermoelectric modules 10 and 20 as test samples.
[0024]
As a result, the electric resistance change rate of the thermoelectric module 10 was 2.8%, and the electric resistance change rate of the thermoelectric module 20 was 4.8%. This result also shows that the thermoelectric module 10 has higher durability than the thermoelectric module 20 according to the comparative example. Moreover, it turns out that durability will worsen by setting the thickness of the thermoelectric module 10 and the height of the thermoelectric elements 16 and 26 small.
[0025]
Thus, in the thermoelectric module 10 according to this embodiment, the thermoelectric element 16 is not provided at any of the four corners of the lower insulating substrate 11 and the upper insulating substrate 12. Therefore, the thermoelectric elements 16 at the four corners that are most likely to be peeled or broken due to thermal stress are eliminated in the thermoelectric module 10, and the durability of the thermoelectric module 10 is improved. That is, since the thermoelectric element 16 that is most likely to be peeled or broken is eliminated, the thermoelectric module 16 that is likely to be peeled or broken next determines the durability of the thermoelectric module 10. The thermoelectric module 10 is a large thermoelectric module having a side length of 12 mm or more, or a thin thermoelectric module having a module height of about 1.4 mm, which is particularly effective.
[0026]
FIG. 6 shows a state in which the lower electrode 33 and the thermoelectric element 36 attached to the lower insulating substrate 31 of the thermoelectric module 30 according to another embodiment of the present invention are viewed from above. In this thermoelectric module 30, the lower electrodes 33 of the lower insulating substrate 31 are all formed in a rectangular shape, and are attached to portions other than the four corners of the lower insulating substrate 31 at regular intervals. On the upper insulating substrate (not shown), a rectangular upper electrode 34 having the same shape as the lower electrode 33 and an L-shaped upper electrode 35 (both shown by a two-dot chain line) are provided at regular intervals. The lower electrode 33 and the upper electrodes 34 and 35 are attached at a distance equal to approximately one thermoelectric element 36.
[0027]
Further, only one thermoelectric element 36 is joined to the lower electrode 33 to which the lead wires 37a and 37b are connected, and the other lower electrode 33 and upper electrodes 34 and 35 are connected to the lower electrodes 33 under the two thermoelectric elements 36. The end face or upper end face is joined. Further, in this thermoelectric module 30, the thermoelectric element 36 is not disposed in a space where three thermoelectric elements 36 can be disposed in the four corner portions of the lower insulating substrate 31 and the upper insulating substrate, respectively. It consists of
[0028]
Further, the thermoelectric module 30 has a vertical and horizontal length of 12 mm and a height of 1.65 mm, and the thermoelectric element 36 has a vertical and horizontal width of 0.8 mm and a height of 1 mm on the upper and lower end faces. Is set. The lower insulating substrate 31 and the upper insulating substrate are made of aluminum nitride plates, and the thermoelectric element 36 is made of a bismuth / tellurium alloy. About the structure of the other part of this thermoelectric module 30, it is the same as that of the thermoelectric module 10 mentioned above.
[0029]
Since it comprised in this way, the thermoelectric element 36 which will be easy to produce peeling and destruction is lose | eliminated, and durability of the thermoelectric module 30 improves more. About the other effect of this thermoelectric module 30, it is the same as that of the thermoelectric module 10 mentioned above. Further, the substrate in each of the embodiments described above is not limited to alumina or aluminum nitride, and may be a metal substrate such as silicon carbide, silicon nitride, or aluminum whose surface is insulated as long as it is an insulating substrate. Good.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a thermoelectric module according to an embodiment of the present invention.
FIG. 2 is a front view of the thermoelectric module shown in FIG.
3 is a plan view showing a state in which a lower electrode and a thermoelectric element are attached to the lower insulating substrate of the thermoelectric module shown in FIG. 1;
FIG. 4 is a plan view showing a state where a lower electrode and a thermoelectric element are attached to a lower insulating substrate of a thermoelectric module according to a comparative example.
FIG. 5 is a front view showing a state in which a thermocycle module is placed on a base and a power cycle test is performed.
FIG. 6 is a plan view illustrating a state in which a lower electrode and a thermoelectric element are attached to a lower insulating substrate of a thermoelectric module according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10,30 ... Thermoelectric module, 11, 31 ... Lower insulating substrate, 12 ... Upper insulating substrate, 13, 14, 33 ... Lower electrode, 15, 34, 35 ... Upper electrode, 16, 36 ... Thermoelectric element.

Claims (1)

A plurality of electrodes are formed between the pair of insulating substrates by forming electrodes at predetermined positions on both sides of the pair of square plate-like insulating substrates arranged to face each other and fixing the end faces of the thermoelectric elements to the facing electrodes, respectively. in the thermoelectric module constructed a thermoelectric element group consisting of thermoelectric elements and placed,
The thermoelectric module is characterized in that the thermoelectric element group is arranged in a square shape whose outer periphery is along the outer periphery of the insulating substrate, and the thermoelectric element is not arranged in the four corner portions of the square shape .

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