Thermoelectric conversion module

A thermoelectric conversion module according to the present disclosure includes a first substrate, a second substrate, and a peripheral thermoelectric conversion element group and a central thermoelectric conversion element group, each of which groups is disposed between the first substrate and the second substrate, and contains a plurality of thermoelectric conversion elements. The peripheral thermoelectric conversion element group is disposed in an area including peripheries of the first substrate and the second substrate, and the central thermoelectric conversion element group is disposed closer to a center of the first substrate and a center of the second substrate than the peripheral thermoelectric conversion element group. The plurality of thermoelectric conversion elements of the central thermoelectric conversion element group are disposed more densely than the plurality of thermoelectric conversion elements of the peripheral thermoelectric conversion element group.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to a thermoelectric conversion module included in various types of electronic devices.

2. Description of the Related Art

A conventional thermoelectric conversion, module is initially described with reference to the drawings.FIG. 7is an exploded perspective view illustrating a configuration of a conventional, thermoelectric conversion module, andFIG. 8is an outline view of the conventional thermoelectric conversion module. Thermoelectric conversion module1includes a plurality of thermoelectric conversion elements2arranged lengthwise and crosswise, and mounted on first substrate3and second substrate4. The plurality of thermoelectric conversion elements2are connected in series by wiring pattern5formed on first substrate3, and wiring pattern5formed on second substrate4. Thermoelectric conversion element6at one end of series connection, and thermoelectric conversion element7at the other end of series connection are connected with extension leads8and9, respectively.

As illustrated inFIG. 8, thermoelectric conversion module1disposed in contact with heat generator10converts heat generated from heat generator10into power, and outputs the thermoelectrically converted power to an outside of thermoelectric conversion module1via extension leads8and9.

Unexamined Japanese Patent Publication No. 2014-82403 is known as related art literature information concerning the disclosure of this application.

SUMMARY OF THE INVENTION

A thermoelectric conversion module according to the present disclosure comprises a first substrate, a second substrate, and a peripheral thermoelectric conversion element group and a central thermoelectric conversion element group, each of which groups is disposed between the first substrate and the second substrate, and contains a plurality of thermoelectric cc avers elements. The peripheral thermoelectric conversion element group is disposed in an area including peripheries of the first substrate and the second substrate, and the central thermoelectric conversion element group is disposed closer to a center of the first substrate and a center of the second substrate than the peripheral thermoelectric conversion element group. The plurality of thermoelectric conversion elements of the central thermoelectric conversion element group are disposed more densely than the plurality of thermoelectric conversion elements of the peripheral thermoelectric conversion element group.

Another thermoelectric conversion module according to the present disclosure comprises a plurality of thermoelectric conversion elements, a first metal substrate and a second metal substrate between which the plurality of thermoelectric conversion elements are sandwiched. The first metal substrate includes a plurality of divisional substrates. The plurality of divisional substrates are disposed with clearances left between each other.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A problem to be solved by an exemplary embodiment of the present disclosure is described below by usingFIG. 7andFIG. 8. According to conventional thermoelectric conversion module1, a temperature of first substrate3of thermoelectric conversion module1in contact with heat generator10increases when thermoelectric conversion module1is placed on heat generator10and receives heat from heat generator10. However, temperature distribution of first substrate3has irregularity. This irregularity of the temperature distribution is produced by radiation of heat to a surrounding environment from a side surface or other exposed portions of thermoelectric conversion module1. Accordingly, equivalent temperature lines of first substrate3, which lines have almost closed shapes as indicated by broken lines inFIG. 8, exhibit higher temperatures in a direction toward a center of thermoelectric conversion module1.

In this case, a temperature in peripheral portion la of thermoelectric conversion module1differs from a temperature in central portion1bof thermoelectric conversion module1, and thus power produced by respective thermoelectric conversion elements2varies for each of thermoelectric conversion elements2. In this situation, there arises such a problem from thermoelectric conversion module1that high efficiency in converting heat conducted from heat generator10to thermoelectric conversion elements2into power is not easily obtained.

For solving this problem, the present disclosure provides a thermoelectric conversion module capable of converting heat into power with high efficiency.

An exemplary embodiment according to the present disclosure is hereinafter described with reference to the drawings.

First Exemplary Embodiment

FIG. 1is an exploded perspective view illustrating a configuration of a thermoelectric conversion module according to a first exemplary embodiment, andFIG. 2is an outline perspective view of the thermoelectric conversion module according to the first exemplary embodiment. Thermoelectric conversion module11includes first substrate12, second substrate13, peripheral thermoelectric conversion element groups14, and central thermoelectric conversion element group15.

Peripheral thermoelectric conversion element groups14and central thermoelectric conversion element group15are sandwiched between first substrate12and second substrate13when mounted on first substrate12and second substrate13. Each of peripheral thermoelectric conversion element groups14and central thermoelectric conversion element group15contains a plurality of thermoelectric conversion elements16.

As illustrated inFIG. 1, each of thermoelectric conversion elements16provided to constitute that peripheral thermoelectric conversion element groups14and central thermoelectric conversion element group15has a rectangular parallelepiped shape. And each of thermoelectric conversion elements16is mounted on an upper surface of first substrate12, and on a lower surface of second substrate13(hereinafter, a surface of first substrate12on which thermoelectric conversion elements16are mounted is referred to as a first mounting surface, and a surface of second substrate13on which thermoelectric conversion elements16are mounted is referred to as a second mounting surface). More specifically, bottoms of respective thermoelectric conversion elements16are electrically connected with wiring pattern19aformed on the first mounting surface of first substrate12, and tops of respective thermoelectric conversion elements16are electrically connected with wiring pattern19bformed on the second mounting surface of second substrate13.

Peripheral thermoelectric conversion element groups14are positioned on first substrate12and second substrate13in areas containing peripheries of first substrate12and second substrate13. On the other hand, central thermoelectric conversion element group15on first substrate12and second substrate13is positioned closer to a center of first substrate12and a center of second substrate13than peripheral thermoelectric conversion element groups14. The plurality of thermoelectric conversion elements16included in central thermoelectric conversion element group15are disposed more densely than the plurality of thermoelectric conversion elements16included in peripheral thermoelectric conversion element groups14.

Central thermoelectric conversion element group15and peripheral thermoelectric conversion element groups14are disposed in rectangular areas arranged in rows. Central thermoelectric conversion element group15is sandwiched between two peripheral thermoelectric conversion element groups14.

Assuming herein that the plurality of thermoelectric conversion elements16constituting central thermoelectric conversion element group15are first thermoelectric conversion elements, and that the plurality of thermoelectric conversion elements16constituting peripheral thermoelectric conversion element groups14are second thermoelectric conversion elements, across-sectional area of each of the second thermoelectric conversion elements along a plane in parallel with the first mounting surface is larger than a cross-sectional area of each of the first thermoelectric conversion elements along a plane in parallel with the first mounting surface. In this case, thermoelectric conversion elements16each having a larger cross-sectional area are disposed on the periphery of thermoelectric conversion module11and an area around this periphery as areas requiring high mechanical strength. Accordingly, mechanical strength of thermoelectric conversion module11in a thickness direction, i.e., mechanical strength against a force generated in a direction from first substrate12to second substrate13increases.

The first thermoelectric conversion elements and the second thermoelectric conversion elements have uniform heights in a direction from first substrate12to second substrate13(direction perpendicular to the first mounting surface). This equalization of the heights of the first thermoelectric conversion elements and the second thermoelectric conversion elements having different cross-sectional areas allows direct connection between thermoelectric conversion elements16and wiring pattern19aor wiring pattern19b, even when thermoelectric conversion elements16have two different types of shape.

Central thermoelectric conversion element group15and peripheral thermoelectric conversion element groups14are disposed in parallel with each other on the first mounting surface of first substrate12. This structure decreases processing time required when thermoelectric conversion elements16constituting central thermoelectric conversion element group15are arranged on first substrate12, and when thermoelectric conversion elements16constituting peripheral thermoelectric conversion element groups14are arranged on first substrate12, during steps for manufacturing thermoelectric conversion module11.

The foregoing structure allows transmission of heat generated by heat generator17illustrated inFIG. 2to thermoelectric conversion module11, and highly efficient conversion of heat into power by a function of central thermoelectric conversion element group15disposed in central portion11bof thermoelectric conversion module11. Here, central portion11bof thermoelectric conversion module11is corresponding to a portion having a higher temperature than peripheral portion11aof thermoelectric conversion module11.

More specifically, central portion of thermoelectric conversion module11as a higher temperature portion includes central thermoelectric conversion element group15containing the plurality of thermoelectric conversion elements16mounted more densely than thermoelectric conversion elements16in peripheral portion11a. In this case, a large number of thermoelectric conversion elements16thermoelectrically convert high thermal energy, and thus heat generated by heat generator17can be converted into power in high efficiency while producing smaller losses.

Detailed configuration and operation of thermoelectric conversion module11are hereinafter described. Peripheral thermoelectric conversion element groups14and central thermoelectric conversion element group15are electrically connected with first substrate12and second substrate13when mounted between first substrate12and second substrate13. Peripheral thermoelectric conversion element groups14and central thermoelectric conversion element group15are mechanically fixed to first substrate12and second substrate13via resin layer18made of an adhesive or the like and disposed between first substrate12and second substrate13.

FIG. 3is a detail view illustrating a part of the configuration of the thermoelectric conversion module according to the first exemplary embodiment. As illustrated inFIG. 3, wiring pattern19aformed on first substrate12connects respective thermoelectric conversion elements16constituting P-type semiconductors or N-type semiconductors in series.FIG. 3does not show second substrate13provided on the upper side of wiring pattern19b. It is preferable that each of first substrate12and second substrate13is made of material having high thermal conductivity, such as copper. Though not shown in the figure, it is preferable that a thin resin layer having excellent insulation properties, such as polyimide resin, is formed on the first mounting surface of first substrate12and the second mounting surface of second substrate13. Wiring patterns19a, and19bare formed on this resin layer. This structure secures an insulated state of thermoelectric conversion elements16from first substrate12or second substrate13without lowering thermal conductivity from first substrate12to thermoelectric conversion elements16, or without lowering thermoelectric conductivity from second substrate13to thermoelectric conversion element16.

Extension leads20aand20bconnect with end thermoelectric conversion elements16aand16b, respectively, provided at both ends of the plurality of thermoelectric conversion elements16connected in series.

According to the example illustrated inFIG. 3, the plurality of thermoelectric conversion elements16constitute a single group. However, as noted above, the plurality of thermoelectric conversion elements16constitute peripheral thermoelectric conversion element groups14, and central thermoelectric conversion element group15according to the exemplary embodiment of the present disclosure. Peripheral thermoelectric conversion element groups14and central thermoelectric conversion element group15may be connected by extension leads20aand20b, or by inter-group connection wiring pattern (not shown). In addition, according to the example illustrated inFIG. 1, peripheral thermoelectric conversion element groups14and central thermoelectric conversion element group15are disposed on first substrate12with spaces formed between peripheral. thermoelectric conversion element groups14and central thermoelectric conversion element group15. These spaces are shown only for the purpose of illustration, and peripheral thermoelectric conversion element groups14and central thermoelectric conversion element group15may be disposed in tight contact with each other. In addition, peripheral thermoelectric conversion element groups14and central thermoelectric conversion element group15may have a boundary area containing a part of mixture of element groups14and15.

Thermoelectric conversion elements16provided within thermoelectric conversion module11are N-type thermoelectric conversion elements16all having equivalent characteristics, and P-type thermoelectric conversion elements16all having equivalent characteristics. Moreover, conversion characteristics of respective thermoelectric conversion elements16from heat into power are also equivalent for each. These conversion characteristics are dependent on specific constants of thermoelectric conversion elements16, and a temperature difference produced between both ends of thermoelectric conversion elements16. This temperature difference generally corresponds to a temperature difference between first substrate12and second substrate13.

However, there is a limitation to a conversion volume or conversion efficiency in heat-to-power conversion achieved by each of thermoelectric conversion elements16. Accordingly, for an area having a large heat capacity or producing a large temperature difference, it is preferable to provide a thermoelectric conversion element group which contains more densely disposed thermoelectric conversion elements16, rather than to raise each capability of thermoelectric conversion elements16. On the other hand, for an area having a small heat capacity or producing a small temperature difference, it is preferable to provide a thermoelectric conversion element group which contains less densely disposed thermoelectric conversion elements16.

FIG. 4is a chart illustrating temperature distribution of the thermoelectric conversion module according to the first exemplary embodiment. As illustrated inFIG. 4, temperature distribution of first substrate12of thermoelectric conversion module11as a substrate in contact with heat generator17is different from temperature distribution of second substrate13as a substrate not in contact with heat generator17. Concerning first substrate12in direct contact with heat generator17, a temperature of central portion11bnot exposed to the external environment easily rises in accordance with a temperature rise of heat generator17, while a temperature of peripheral portion11apartially exposed to the external environment does not easily rise in comparison with the temperature of central portion11b.

On the other hand, concerning second substrate13not in direct contact with heat generator17, a temperature difference between peripheral portion11aand central portion11bis hardly produced in comparison with a curve of temperature characteristics of first substrate12. This condition of second substrate13comes from a state that an entire surface of second substrate13on the side opposite to heat generator17is exposed to the external environment.

Accordingly, concerning thermoelectric conversion module11, temperature difference ΔTb between first substrate12and second substrate13in central portion11bis constantly larger than temperature difference ΔTa between first substrate12and second. substrate13in peripheral portion11a. In this case, temperature difference ΔTb in central portion11bbecomes a large value, and thus power generated by respective thermoelectric conversion elements16increases. However, the heat capacity of central portion11bin first substrate12simultaneously increases, and thus central portion11brequires a thermoelectric conversion element group matching with a large heat capacity so as to perform thermoelectric conversion with high efficiency.

Accordingly, it is preferable in thermoelectric conversion module11that central thermoelectric conversion element group15, which contains thermoelectric conversion elements16disposed highly densely, is provided on central portion11bwhich easily accumulates heat supplied from heat generator17and thus has a large heat capacity. On the other hand, it is preferable that peripheral thermoelectric conversion element groups14, which contains thermoelectric conversion elements16disposed less densely than thermoelectric conversion elements16of central thermoelectric conversion element group15, is provided on peripheral portion11awhich does not easily accumulate heat supplied from heat generator17and thus has a smaller heat capacity than the heat capacity of central portion11b.

According to this structure, a large number of highly densely disposed thermoelectric conversion elements16perform thermoelectric conversion in an area having a large capacity for heat received by thermoelectric conversion module11from heat generator17. As a result, thermoelectric conversion efficiency of thermoelectric conversion module11increases.

In addition, at least two types of solder having different melting points are used for manufacturing thermoelectric conversion module11. More specifically, thermoelectric conversion module11is manufactured by using first solder having a predetermined melting point, and second solder having a melting point lower than the melting point of the first solder.

Assuming that the plurality of thermoelectric conversion elements16in central thermoelectric conversion element group15are the first thermoelectric conversion elements, the first thermoelectric conversion elements are connected with first wiring pattern19aand second wiring pattern19bvia the first solder. On the other hand, assuming that the plurality of thermoelectric conversion elements16in peripheral thermoelectric conversion element groups14are the second thermoelectric conversion elements, the second thermoelectric conversion elements are connected with first wiring pattern19aand second wiring pattern19bvia the second solder.

As noted herein, at least two types of solder having different melting points are used. In this case, solder having a higher melting point is used for connection of central thermoelectric conversion element group15, while solder having a lower melting point is used for connection of peripheral thermoelectric conversion element groups14. This structure secures certain tolerance for melting of connection solder in accordance with temperature rises of the thermoelectric conversion elements groups. Moreover, the use of at least two types of solder having different melting points in manufacturing thermoelectric conversion module11allows separation of a step for attaching the first thermoelectric conversion elements to first wiring pattern19afrom a step for attaching the second thermoelectric conversion elements to first wiring pattern19a. This separation of the steps reduces manufacturing time required for each of the steps, and thus reduces the entire manufacturing time of thermoelectric conversion module11.

According to the description with reference toFIG. 1presented by way of example, peripheral thermoelectric conversion element groups14and central thermoelectric conversion element group15each disposed in a substantially rectangular area are positioned such that central thermoelectric conversion element group15is sandwiched between two peripheral thermoelectric conversion element groups14. However, peripheral thermoelectric conversion element groups14and central thermoelectric conversion element group15may be disposed in arrangement different from the arrangement of the structure illustrated inFIG. 1.FIG. 5is a perspective view illustrating a configuration of a thermoelectric conversion module according to a modified example of the first exemplary embodiment. As illustrated inFIG. 5, peripheral thermoelectric conversion element group14is disposed in a frame-shaped area on first substrate12, and central thermoelectric conversion element group15is disposed in an area inside the frame. Alternatively, peripheral thermoelectric conversion element group14may be disposed in a toroidal area on first substrate12, and central thermoelectric conversion element group15may be disposed inside the toroidal shape. In other words, peripheral thermoelectric conversion element group14and central thermoelectric conversion element group15may be concentrically disposed. When central thermoelectric conversion element group15is surrounded by peripheral thermoelectric conversion element group14as in these examples, mechanical strength of the periphery of thermoelectric conversion module11and an area around this periphery increases.

Furthermore, central thermoelectric conversion element group15may be configured to gradually decrease intervals of thermoelectric conversion elements16in a direction toward the center of the first mounting surface of first substrate12or the second mounting surface of second substrate13, i.e., toward the center of thermoelectric conversion module11. On the other hand, peripheral thermoelectric conversion element groups14may be configured to gradually increase intervals of thermoelectric conversion elements16in a direction toward the periphery of first substrate12or the second substrate13. According to this structure, shapes of thermoelectric conversion elements16constituting central thermoelectric conversion element group15, and shapes of thermoelectric conversion elements16constituting peripheral thermoelectric conversion element groups14are not required to be different shapes but may be uniform shapes. Accordingly, increase in a number of part types is not needed for manufacturing thermoelectric conversion module11arranged such that the plurality of thermoelectric conversion elements16are more densely disposed in central thermoelectric conversion element group15than in peripheral thermoelectric conversion element groups14.

FIG. 6is a schematic diagram illustrating electric connection of a thermoelectric conversion module according to another modified example of the first exemplary embodiment. As illustrated inFIG. 6, a connection state of thermoelectric conversion elements16of peripheral thermoelectric conversion element groups14disposed on first substrate12may be different from a connection state of thermoelectric conversion elements16of central thermoelectric conversion element group15disposed on first substrate12. For example, suppose that a number of thermoelectric conversion elements16constituting central thermoelectric conversion element group15is twice larger than a number of thermoelectric conversion elements16constituting each of peripheral thermoelectric conversion element groups14. In this case, all thermoelectric conversion elements16of peripheral thermoelectric conversion element groups14may be connected in series. On the other hand, each of thermoelectric conversion elements16of central thermoelectric conversion element group15may be divided into equal halves such that each cross-sectional area of thermoelectric conversion elements16of central thermoelectric conversion element group15becomes a half. Then, two series connection parts15acontaining the same number of equal halves of thermoelectric conversion elements16connected in series may be formed and connected in parallel.

In this case, voltage of central thermoelectric conversion element group15becomes half of voltage that is produced if all thermoelectric conversion elements16are connected in series. However, current allowed to be supplied becomes two times larger than current that is produced if all thermoelectric conversion elements16are connected in series. In other words, the connection state of thermoelectric conversion elements16of peripheral thermoelectric conversion element groups14, and the connection state of thermoelectric conversion elements16of central thermoelectric conversion element group15are allowed to vary in response to changes of wiring patterns19aand19bmade in accordance with necessary output voltage or output current. In addition, resistance between extension leads20aand20bis allowed to vary in accordance with changes of the connection state of thermoelectric conversion elements16of peripheral thermoelectric conversion element groups14and the connection state of thermoelectric conversion elements16of central thermoelectric conversion element group15similarly to above.

According to the example illustrated inFIG. 6, approximately the same number of equal halves of thermoelectric conversion elements16connected in series are disposed in parallel in central thermoelectric conversion element group15. According to this structure, power is generated from two series connection parts15aof central thermoelectric conversion element group15. In this case, circulating current is produced when electromotive force generated from respective series connection parts15abecomes unbalanced. It is therefore preferable that electromotive force generated from each of two series connection parts15abecomes substantially uniform so as not to produce circulating current.

It is also preferable that peripheral thermoelectric conversion element groups14and central thermoelectric conversion element group15have substantially equivalent impedance. In this exemplary embodiment, impedance of each of peripheral thermoelectric conversion element groups14and central thermoelectric conversion element group15is set to R. In this case, power losses produced by peripheral thermoelectric conversion element groups14and by central thermoelectric conversion element group15become substantially uniform, and thus generated output is not lowered by a rise of a power loss in a particular area.

As discussed above, temperature difference ΔTb between first substrate12and second substrate13in central portion11bincreases as well as rises of an absolute value of temperature and a heat capacity in this area, when compared with other areas as illustrated inFIG. 4. The plurality of thermoelectric conversion elements16are highly densely disposed in central portion11bbetween first substrate12and second substrate13, constituting central thermoelectric conversion element group15. The increase in temperature difference ΔTb, and the presence of a large number of thermoelectric conversion elements16raise power output from central thermoelectric conversion element group15. On the other hand, increase in temperature difference ΔTb raises heat conduction from first substrate12to second substrate13via thermoelectric conversion elements16in central portion11b. This heat conduction decreases temperature difference ΔTb between first substrate12and second substrate13. In this case, the heat conduction may prevent a rise of power output from thermoelectric conversion elements16.

It is therefore preferable that each cross-sectional area of the plurality of thermoelectric conversion elements16constituting central thermoelectric conversion element group15along the plane in parallel with the first mounting surface is smaller than each cross-sectional area of the plurality of thermoelectric conversion elements16constituting peripheral thermoelectric conversion element groups14along the plane in parallel with the first mounting surface. In this case, the heat conduction from first substrate12to second substrate13via thermoelectric conversion elements16in central thermoelectric conversion element group15decreases. As a result, decrease in temperature difference. ΔTb between first substrate12and second substrate13is avoidable, and thus thermoelectric conversion efficiency and power output in central thermoelectric conversion element group15both increase.

However, reduction of each cross-sectional area of thermoelectric conversion elements16increases each resistance of thermoelectric conversion elements16. The increase in resistance prevents a rise of power output from thermoelectric conversion elements16. In general, power generation amount P of thermoelectric conversion elements16is calculated as P=(S2·ΔTb2)/(4·Ri), where S is Seebeck coefficient and Ri is internal resistance of thermoelectric conversion elements16. Accordingly, for increasing power generation amount P, it is only required to obtain a larger increase rate of a square of temperature difference ΔTb than an increase rate of internal resistance Ri before and after reduction of each cross-sectional area of thermoelectric conversion elements16.

For example, a relation ((Rc−Re)/Re)<((ΔTb2−ΔTb1)2/ΔTb12) is only required to hold, where Re is internal resistance before reduction of each cross-sectional area of thermoelectric conversion elements16in peripheral thermoelectric conversion element groups14, Rc is internal resistance after reduction of each cross-sectional area of thermoelectric conversion elements16in central thermoelectric conversion element group15, ΔTb1 is temperature difference in central portion11bwhen the same thermoelectric conversion elements16are used for peripheral thermoelectric conversion element groups14and central thermoelectric conversion element group15, and ΔTb2 is temperature difference in central portion11bwhen thermoelectric conversion elements16each having a reduced cross-sectional area is used for central thermoelectric conversion element group15.

When this relation holds, thermoelectric conversion efficiency of central thermoelectric conversion element group15improves by reduction of each cross-sectional area of thermoelectric conversion elements16.

According to this exemplary embodiment, central thermoelectric conversion element group15is configured to maintain temperature difference ΔTb between first substrate12and second substrate13in the state of reduction of each cross-sectional area of thermoelectric conversion elements16of central thermoelectric conversion element group15. However, the plurality of thermoelectric conversion elements16in central thermoelectric conversion element group15are disposed more densely than the plurality of thermoelectric conversion elements16in peripheral thermoelectric conversion element groups14. In this case, heat conduction. from first substrate12to second substrate13via thermoelectric conversion elements16becomes larger in central thermoelectric conversion element group15than in peripheral thermoelectric conversion element groups14as noted above. Accordingly, highly dense positioning of thermoelectric conversion elements16in central thermoelectric conversion element group15can prevent or reduce enlargement of the difference between ΔTa and ΔTb, in comparison with positioning of the plurality of thermoelectric conversion elements16at equal density for central thermoelectric conversion element group15and peripheral thermoelectric conversion element groups14.

As a result, deformation and a warp produced in first substrate12by heat decreases, and mechanical stress applied to thermoelectric conversion elements16also decreases. Accordingly, reliability of thermoelectric conversion module11further improves.

Second Exemplary Embodiment

FIG. 9is an exploded perspective view illustrating a thermoelectric conversion module according to a second exemplary embodiment, andFIG. 10is a local cross-sectional view of the thermoelectric conversion module according to the second exemplary embodiment.

As illustrated inFIGS. 9 and 10, thermoelectric conversion module1003according to the second exemplary embodiment includes first metal substrate1010and second metal substrate1020facing to each other, and a plurality of thermoelectric conversion elements1005disposed between first metal substrates1010and second metal substrates1020. Thermoelectric conversion elements1005are disposed in a predetermined arrangement state in a horizontal direction, and constituted by a plurality of P-type thermoelectric conversion elements, and a plurality of N-type thermoelectric conversion elements. The P-type and N-type thermoelectric conversion elements have the same rectangular parallelepiped external shape.

First metal substrate1010is constituted by four divisional substrates1010A. On the other hand, second metal substrate1020is constituted by one substrate.

As illustrated inFIG. 10, each of divisional substrates1010A constituting first metal substrate1010includes insulation layer1014formed on one surface of copper plate1012, and first electrodes1016overlapped with insulation layer1014. First electrodes1016are made of copper. Insulation layer1014is made of polyimide resin or the like.

Similarly to first metal substrate1010, second metal substrate1020includes insulation layer1024formed on one surface of copper plate1022, and second electrodes1026overlapped with insulation layer1024. Second electrodes1026are made of copper. Insulation layer1024is made of polyimide resin or the like.

First electrodes1016and second electrodes1026are disposed on first metal substrate1010and second metal substrate1020, respectively, such that the P-type thermoelectric conversion elements and the N-type thermoelectric conversion elements are alternately connectable in series.

Thermoelectric conversion module1003is wired for each of respective divisional substrates1010A of first metal substrate1010, and respective areas of second metal substrate1020corresponding to respective divisional substrates1010A, such that the respective areas connect with one another on second metal substrate1020. In other words, four divisional units as divisions of thermoelectric conversion module1003formed for each of divisional substrates1010A and the areas of second metal substrate1020in correspondence with respective divisional substrates1010A connect with one another via wiring formed on second metal substrate1020.

Thermoelectric conversion module1003extracts power output through leads1040A and1040B connected with both end portions of one side of a rectangular shape of second metal substrate1020.

Thermoelectric conversion module1003may raise output voltage by connecting all the divisional units in series, or may raise output current by connecting all the divisional units in parallel. Alternatively, thermoelectric conversion module1003may be connected by a combination of series and parallel connections of the divisional units.

First metal substrate1010corresponds to a high temperature side substrate which is to be heated, and second metal substrate1020corresponds to a low temperature side substrate which is to be cooled. Accordingly, thermoelectric conversion module1003generates power by heating first metal substrate1010, and cooling second metal substrate1020. Conversely, supply of power to leads1040A and1040B of thermoelectric conversion module1003heats first metal substrate1010, and cools second metal substrate1020.

As noted above, first metal substrate1010is constituted by four divisional substrates1010A. Clearances1050are formed between adjoining divisional substrates1010A. In this case, even when a difference in volume between first metal substrate1010and second metal substrate1020is produced due to thermal expansion deformation as a result of heating of first metal substrate1010and cooling of second metal substrate1020for power generation from thermoelectric conversion module1003, this difference in deformation volume is absorbed by clearances1050between divisional substrates1010A. Accordingly, this structure prevents generation of deformation (warp) of first metal substrate1010and second metal substrate1020in the thickness direction, and therefore avoids damage to thermoelectric conversion module1003.

According to this exemplary embodiment, first metal substrate1010on the heating side is divided into the plurality of divisional substrates1010A. The thermal expansion deformation volume during power generation of thermoelectric conversion module1003is larger in first metal substrate1010than in second metal substrate1020. In this case, thermal stress applied to thermoelectric conversion elements becomes lower in a structure which divides first metal substrate1010into the plurality of divisional substrates1010A, than in a structure which divides second metal substrate1020into a plurality of divisional parts. It is therefore preferable that first metal substrate1010is divided into the plurality of divisional substrates1010A. However, the substrate to be divided is not limited to first metal substrate1010. Even when the cooled side metal substrate (second metal substrate1020in this exemplary embodiment) is divided into a plurality of divisional substrates, the thermal expansion deformation volume difference produced between first metal substrate1010and second metal substrate1020is absorbed by clearances1050between the divisional substrates of second metal substrate1020.

The number of divisions of divisional substrates1010A may be appropriately varied in accordance with a size of thermoelectric conversion module1003, and the thermal expansion deformation volumes of first metal substrate1010and second metal substrate1020.

While one of first metal substrate1010and second metal substrate1020is only required to be divided, such a configuration may be considered which divides both first metal substrate1010and second metal substrate1020into parts formed such that the parts of first metal substrate1010and the parts of second metal substrate1020are different in division size. However, it is preferable, in view of wiring and mechanical strength, that one of first metal substrate1010and second metal substrate1020is formed by not-divided one substrate for constituting thermoelectric conversion module1003by connection of respective divisional units.

According to thermoelectric conversion module1003in this exemplary embodiment, thermoelectric conversion elements1005are mounted on each of respective divisional substrates1010A of first metal substrate1010, for example. Then, respective divisional substrates1010A including thermoelectric conversion elements1005are disposed by use of a jig (not shown) at predetermined positions of second metal substrate1020constituted by one substrate. Thermoelectric conversion elements1005are arranged by the jig in matrix with a constant pitch. Each end surface of thermoelectric conversion elements1005is soldered to first electrode1016and second electrode1026. The respective divisional units of thermoelectric conversion module1003associated respective divisional substrates1010A, and with the respective areas of second metal substrate1020corresponding to respective divisional substrates1010A, are connected by wiring formed on second metal substrate1020, when respective substrates1010A containing thermoelectric conversion elements1005are positioned. on second metal substrate1020. This structure facilitates assembly of thermoelectric conversion module1003, and therefore increases productivity.

Thermoelectric conversion module1003thus constructed is applicable to a power generating device capable of extracting predetermined power from leads1040A and1040B based on seebeck effect by heating first metal substrate1010and cooling second metal substrate1020, for example, similarly to the conventional technology. Alternatively, when predetermined power is supplied to leads1040A and1040B, first metal substrate1010and second metal substrate1020come into a heated state and a cooled state, respectively, for example. In this case, thermoelectric conversion module1003is capable of functioning as a cooling device or the like.

Thermoelectric conversion mod1003is advantageous in increasing power extraction when applied to a power generating device.

More specifically, thermoelectric conversion module1003according to this exemplary embodiment includes first metal substrate1010constituted by the plurality of divisional substrates1010A disposed with clearances1050between one another. Even when a thermal expansion deformation volume of first metal substrate1010is different from a thermal expansion deformation volume of second metal substrate1020, deformation of first metal substrate1010and second metal substrate1020caused by the difference in the deformation volume is absorbed by clearances1050between divisional substrates1010A. This structure allows use of metal for substrates constituting thermoelectric conversion module1003between which thermoelectric conversion elements1005are sandwiched, and enlargement of areas of the metal substrates. In this case, the number of thermoelectric conversion elements1005allowed to be mounted on thermoelectric conversion module1003increases. In addition, thermoelectric conversion module1003is easily made into one piece body by using wiring formed on second metal substrate1020for connecting respective divisional substrates1010A of first metal substrate1010.

A division number and an area of first metal substrate1010, or size setting of clearances between respective divisional substrates1010A of first metal substrate1010may be appropriately determined in consideration of thermal expansion deformation volumes of first metal substrate1010and second metal substrate1020, working efficiency of respective divisional substrates1010A at the time of positioning of respective divisional substrates1010A.

Moreover, a difference in thermal expansion deformation volume between first metal substrate1010and second metal substrate1020is absorbable by clearances1050between divisional substrates1010A of first metal substrate1010even when thermoelectric conversion module1003having this configuration is applied for the purpose of cooling. Accordingly, thermoelectric conversion module1003is advantageous in size enlargement, and enhances cooling effect.

The exemplary embodiments described herein are presented only for easy understanding of the present disclosure. Any materials, shapes, and assembling methods of respective constituent elements of thermoelectric conversion modules11and1003described, in the exemplary embodiments may be modified or changed in various manners. It is therefore not intended that the present disclosure be limited to the exemplary embodiments in any way.