Patent Application
20140034106
The embodiments discussed herein are related to a thermoelectric generator for converting thermal energy into an electric energy by using a temperature difference.
Various types of clean energies have been paid attention along with high level of interest on environment-related issue. One of clean energies is thermoelectric generation converting thermal energy into electric energy by using a temperature difference.
A thin film thermoelectric generating device having thermoelectric conversion material formed on an insulating film having flexibility is known. By attaching materials having high thermal conductivity on the insulating film in such a manner that the materials are mutually shifted in in-plane direction, a temperature difference in an in-plane direction is generated from a temperature difference in the thickness direction. Thermoelectric conversion is performed by using a temperature difference in the in-plane direction.
A thermoelectric generating device is known having a structure that thermoelectric conversion material is disposed from one surface of a film to the other surface of the film. In this thermoelectric generating device, thermoelectric conversion is performed by a temperature difference in the thickness direction.
A thermoelectric conversion device is known having film-shaped thermoelectric conversion elements and thermal insulating plates which are alternately stacked. Thermoelectric generation is performed by using a temperature difference in the direction perpendicular to the lamination direction.
Since the thermal insulating plates are sandwiched, thermal conduction from a high temperature side to a low temperature side is able to be suppressed. [Patent Document 1] Japanese Laid-open Patent Publication No. 2006-186255 [Patent Document 2] Japanese Laid-open Patent Publication No. HEI 8-153898 [Non-Patent Document] J. Micromech. Microeng. Vol.15 (2005) S233-S238
It is an object of the present invention to provide a thermoelectric generator capable of improving an electric power generation ability compared to a conventional thermoelectric generator.
According to one aspect of the embodiments, there is provided a thermoelectric generator including:
thermoelectric generating parts having a plate-shape or film-shape and stacked in a thickness direction, each of the thermoelectric generating parts generating an electric power as a temperature difference is generated in the thickness direction;
thermal conducting members disposed between two of the thermoelectric generating parts adjacent in a stacked direction and on outer surfaces of outermost two thermoelectric generating parts;
a first thermal coupling member connected to and thermally coupled to the every other thermal conducting members disposed in the stacked direction; and
a second thermal coupling member connected to and thermally coupled to the thermal conducting members not connected to the first thermal coupling member.
The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed.
FIG. 3Aa, FIGS. 3Ab to FIG. 3Ea, FIG. 3Eb are planar views and cross sectional views of the thermoelectric generator of the second embodiment at intermediate stages of manufacturing process.
By referring to the accompanying drawings, description will be made on first to twentieth embodiments.
A first thermal coupling member 22 is connected to every other thermal conducting members 21 disposed in the stacked direction. A second thermal coupling member 23 is connected to the thermal conducting members 21 not connected to the first thermal coupling member 22. The first thermal coupling member 22 is thermally coupled to the thermal conducting members 21 connected thereto, and the second thermal coupling member 23 is thermally coupled to the thermal conducting members 21 connected thereto.
An interlayer wiring 24 electrically connects the adjacent thermoelectric generating devices 20 in the stacked direction to each other. For example, a plurality of thermoelectric generating devices 20 are serially connected. One of outermost thermoelectric generating devices 20 is connected to a terminal 25, and the other is connected to a terminal 26. A generated electric power is extracted from the terminals 25 and 26.
The number of stacked thermoelectric generating devices 20 is odd, whereas the number of stacked thermal conducting embers 21 is even. One of the outermost thermal conducting members 21 is therefore connected to the first thermal coupling member 22, and the other is connected to the second thermal coupling member 23. The first thermal coupling member 22, the second thermal coupling member 23 and the thermal conducting member 21 are made of material having a higher thermal conductivity than that of the thermoelectric generating devices 20.
One of the outermost thermal conducting members 21, e.g., the thermal conducting member 21 connected to the first thermal conducting member 22 takes a higher temperature, and the other of the outermost thermal conducting member 21, e.g., the thermal conducting member 21 connected to the second thermal coupling member 23 takes a lower temperature. As this temperature difference is generated, a temperature of all the thermal conducting members 21 connected to the first thermal coupling member 22 becomes higher than a temperature of the thermal conducting members 21 connected to the second thermal coupling member 23. A temperature difference is therefore generated at each thermoelectric generating device 20 in the thickness direction. This temperature difference generates an electric power. Temperature gradients in the thickness direction of the adjacent thermoelectric generating devices 20 in the stacked direction are opposite in direction. Although a temperature difference given to each thermoelectric generating device 20 becomes slightly lower than a temperature difference between the uppermost surface and lowermost surface of the stacked structure, it is sufficiently higher than a temperature difference when the temperature difference between the uppermost surface and lowermost surface is equally divided to the plurality of thermoelectric generating devices 20. By stacking the thermoelectric generating devices 20, it becomes therefore possible to improve an electric power generating ability per unit area.
Each thermoelectric generating device 20 includes a first good thermal conductor 37 disposed on an outer surface of the first flexible film 30, a second good thermal conductor 38 disposed on an outer surface of the second flexible film 31, and a thermoelectric conversion pattern 32 sandwiched between the first flexible film 30 and the second flexible film 31. The first good thermal conductor 37 and the second good thermal conductor 38 are made of material having a higher thermal conductivity than that of the first flexible film 30 and the second flexible film 31. For the first flexible film 30 and the second flexible film 31, for example, insulating material such as polyimide, kapton (registered trademark), polycarbonate, polyethylene, polyethyleneterephthalate (PET), polysulfone (PSF), polyetherethylketone (PEEK), and polyphenylenesulfide (PPS) may be used. From these materials, proper materials are selected by considering a film forming condition of thermoelectric conversion material, a use condition of the thermoelectric generator, and the like. For the first good thermal conductor 37 and the second good thermal conductor 38, for example, metal such as copper may be used.
The first good thermal conductor 37 and the second good thermal conductor 38 are displaced at positions different from each other in an in-plane direction. For example, in
A plate-shaped thermal conducting member 21 is disposed between the thermoelectric generating devices 20. A first thermal coupling member 22 is connected to every other thermal conducting members 21. In
A folded portion 33 of the folded stacked structure appears at mutually opposing two side walls (left and right side walls as viewed in
Next, description will be made on a manufacture method for the thermoelectric generator of the second embodiment.
As illustrated in FIG. 3Aa, five thermoelectric generating parts 34 are defined on the band-like first flexible film 30. The thermoelectric generating parts 34 are disposed in one line on the first flexible film 30 in the longitudinal direction. Folded portions 33 are defined between adjacent thermoelectric generating parts 34. FIG. 3Ab is a cross sectional view taken along one-dot chain line 3Ab-3Ab in FIG. 3Aa. For the first flexible film 30, for example, a polyimide film having a thickness of 50 μm and a width of 100 mm is used. A size of each of the thermoelectric generating parts 34 in the longitudinal direction of the first flexible film 30 is, e.g., within a range of 3 mm to 50 mm. The number of thermoelectric generating parts 34 may be an odd number other than “5”.
One first good thermal conductor 37 is fabricated on one surface of each of the thermoelectric generating parts 34 of the first flexible film 30. For the first good thermal conductor 37, for example, a copper foil having a thickness of 25 μm is used. The first good thermal conductor 37 is fabricated in the first flexible film 30 by burying the first good thermal conductor 37 in a recess formed by grinding a partial area of the surface of the first flexible film 30. The first good thermal conductor 37 is disposed in each inner region of the thermoelectric generating part 34 at a position displaced toward one side in the longitudinal direction. In the second embodiment, the first good thermal conductors 37 are disposed at positions displaced toward the same side (on the left side in FIG. 3Aa and FIG. 3Ab) in all thermoelectric generating parts 34.
The first flexible film 30 having the first good thermal conductors 37 may be formed by the following process. Copper foils are arranged on a work table. Polyimide precursor solution may be coated on the work table and the copper foils. Thereafter, the solution is imidized.
As illustrated in FIG. 3Ba, a plurality of p-type thermoelectric conversion patterns 32P are formed on the surface of the first flexible film 30 opposite to the surface where the first good thermal conductors 37 are fabricated. FIG. 3Bb is a cross sectional view taken along one-dot-chain line 3Bb-3Bb in FIG. 3Ba. Each p-type thermoelectric conversion pattern 32P is disposed in the thermoelectric generating part 34, and has a planar shape elongated in the longitudinal direction of the first flexible film 30. A plurality (three in FIG. 3Ba) of p-type thermoelectric conversion patterns 32P are disposed in the width direction of the first flexible film 30.
For example, chromel is used for the p-type thermoelectric conversion patterns 32P. Its film thickness is about 1 μm and width is 1 mm. The p-type thermoelectric conversion patterns 32P may be formed by sputtering using a metal mask 40 having openings corresponding to areas where the p-type thermoelectric conversion patterns 32P are to be formed.
As illustrated in FIG. 3Ca, a plurality of n-type thermoelectric conversion patterns 32N are formed on the surface of the first flexible film 30. FIG. 3Cb is a cross sectional view taken along one-dot chain line 3Cb-3Cb in FIG. 3Ca. Each n-type thermoelectric conversion pattern 32N has a planar shape almost the same as that of the p-type thermoelectric conversion pattern 32P, and is disposed between the p-type thermoelectric conversion patterns 32P.
For example, constantan is used for the n-type thermoelectric conversion patterns 32N. Its film thickness is about 1 μm. The n-type thermoelectric conversion patterns 32N may be formed by sputtering using a metal mask 41 having openings corresponding to areas where the n-type thermoelectric conversion patterns 32N are to be formed.
As illustrated in FIG. 3Da, a plurality of intra-layer wirings 27 and interlayer wirings 24 are formed on the first flexible film 30. FIG. 3Db is a cross sectional view taken along one-dot-chain line 3Db-3Db in FIG. 3Da. The intra-layer wring 27 interconnects the end portion of the n-type thermoelectric pattern 32N and the end portion of the p-type thermoelectric pattern 32P adjacent to each other in the width direction. In one thermoelectric generating part 34, one serial circuit is formed, the serial circuit having the n-type thermoelectric conversion patterns 32N and the p-type thermoelectric conversion patterns 32P alternately connected.
The interlayer wirings 24 interconnects the end portions of the serial circuits in adjacent thermoelectric generating parts 34. In FIG. 3Da, the end portions of the p-type thermoelectric generator patterns 32P are connected by the interlayer wiring 24. The interlayer wirings 24 serially connect the serial circuits formed in a plurality of thermoelectric generating parts 34.
For example, copper (Cu) is used for the interlayer wirings 24 and the intra-layer wirings 27, thicknesses of which are, e.g., about 0.3 μm. Silver (Ag) or aluminum (Al) may be used instead of copper. The interlayer wirings 24 and the intra-layer wirings 27 may be formed by sputtering using a metal mask 42 having openings corresponding to areas where the interlayer wirings 24 and the intra-layer wirings 27 are to be formed.
As illustrated in FIG. 3Ea and FIG. 3Eb, the second flexible film 31 is bonded to the first flexible film 30 with adhesive or the like. FIG. 3Eb is a cross sectional view taken along one-dot-chain line 3Eb-3Eb in FIG. 3Ea. The second flexible film 31 has almost the same planar shape as that of the first flexible film 30. The p-type thermoelectric conversion patterns 32P, the n-type thermoelectric conversion patterns 32N, the intra-layer wirings 27 and the interlayer wirings 24 are sandwiched between the first flexible film 30 and the second flexible film 31.
A second good thermal conductors 38 are being fabricated on the outer surface of the second flexible film 31. The second good thermal conductors 38 may be fabricated in the second flexible film 31 using the same method as that of fabricating the first good thermal conductors 37 in the first flexible film 30. A polyimide film having a thickness of, e.g., 50 μm is used for the second flexible film 31. Copper foils having a thickness of, e.g., 25 μm is used for the second good thermal conductors 38.
The second good thermal conductor 38 is disposed in the thermoelectric generating part 34 at a position displaced from the first good thermal conductor 37 in the longitudinal direction of the second flexible film 31 (at a position displaced to the right in FIG. 3Ea and FIG. 3Eb). Each of the p-type thermoelectric conversion patterns 32P and the n-type thermoelectric conversion patterns 32N extends from a position overlapping the first good thermal conductor 37 to a position overlapping the second good thermal conductor 38.
As illustrated in
As illustrated in
The first good thermal conductors 37 are in contact with the thermal conducting members 21 connected to the second thermal coupling member 23, and the second good thermal conductors 38 are in contact with the thermal conducting members 21 connected to the first thermal coupling member 22. For example, the outermost (lowermost in
A thermal conductivity of the first thermal coupling member 22, the second thermal coupling member 23 and the thermal conducting members 21 is higher than that of the first flexible film 30 and the second flexible film 31. The thermal conducting members 21 connected to the first thermal coupling member 22 take therefore a higher temperature than the thermal conducting members 21 connected to the second thermal coupling member 23. A thermal conductivity of the first good thermal conductor 37 and the second good thermal conductor 38 is higher than that of the first flexible film 30 and the second flexible film 31. A thermal path is therefore formed from the higher temperature thermal conducting members 21 to the lower temperature thermal conducting members 21 via the second good thermal conductor 38, the second flexible film 31, the first flexible film 30 and the first good thermal conductor 37. A temperature gradient lowering a temperature from the second good thermal conductor 38 toward the first good thermal conductor 37 is generated in each thermoelectric generating device 20. Each of the first good thermal conductors 37 and the second good thermal conductors 38 generates a temperature difference in the in-plane direction from a temperature difference in the thickness direction of the thermoelectric generating device 20.
As an in-plane temperature difference is generated, temperature difference in a longitudinal direction is generated in each of the p-type thermoelectric conversion patterns 32P and the n-type thermoelectric conversion patterns 32N. This temperature difference generates a thermoelectromotive force due to the thermoelectric effects. As in the case of the first embodiment, the thermoelectric generator of the second embodiment is able to improve an electric power generation ability per unit area.
An in-plane direction displacement amount of the first good thermal conductor 37 and the second good thermal conductor 38 is set so that a temperature difference in the in-plane direction is generated efficiently. For example, the first good thermal conductor 37 and the second good thermal conductor 38 are disposed in such a manner that vertical projected images of the first good thermal conductor 37 and the second good thermal conductor 38 onto a virtual flat plane perpendicular to the stacked direction are not overlapped with each other. The first good thermal conductor 37 and the second good thermal conductor 38 may be disposed in such a manner that edges facing to each other of the vertical projected images of the first good thermal conductor 37 and the second good thermal conductor 38 become coincident.
The thermoelectric generator of the second embodiment has a multi-layer structure having a plurality of thermoelectric generating devices 20 which are stacked. The interlayer wirings 24 electrically interconnecting the thermoelectric generating devices 20 are formed at the same time when the intra-layer wirings 27 in one thermoelectric generating device 20 are formed in the process illustrated in FIG. 3Da and FIG. 3Db. The manufacture processes are able to be simplified more than the method of interconnecting the thermoelectric generating devices 20 after a plurality of thermoelectric generating devices 20 are stacked.
Next, description will be made on the reliability of the folded portions 33. As a curvature of the folded portion 33 is made small, it is apprehended that the reliability lowers. In the second embodiment, design was performed on the basis of R=0.38 mm in conformity with the specifications of a flexible print board, JIS C5016 Folding Endurance Test. Raw material for the flexible film adopted satisfies the criterion of the number of bending times of 70 or more under the conditions of a bending angle of 135° and a bending speed of 170 times/min. The thermoelectric generator of the second embodiment will not be bent repetitively during use after it is bend once during manufacture. It is therefore possible to maintain sufficient reliability by using a flexible film satisfying the above-described criterion.
Since the first thermal coupling member 22 and the second thermal coupling member 23 are disposed outside the folded portions 33, it is possible to prevent an external force from directly acting upon the folded portions 33. It is therefore possible to suppress wearing and the like of the folded portions 33 to be caused by an external force.
Further, the thermoelectric generator of the second embodiment does not have the structure of hindering curvature of the thermoelectric generator, in a direction (horizontal direction in
In the second embodiment, although chromel and constantan are used as the thermoelectric conversion material, other materials may also be used. It is possible to use, e.g., BiTe based material, PbTe based material, Si—Ge based material, silicide based material, skutterudite based material, transition metal oxide based material, zinc antimonide based material, boron compound, cluster solid, zinc oxide based material, carbon nanotube and the like.
Examples of the BiTe based material include BiTe, SbTe, BiSe and their compounds. Examples of the PbTe based material include PbTe, SnTe, AgSbTe, GeTe and their compounds. Examples of the Si—Ge based magerial include Si, Ge, SiGe and the like. Examples of the silicide based material include FeSi, MnSi, CrSi and the like. Examples of the sutterudite based material is represented by a general expression MX3 or RM4X12 where M represents Co, Rh or Ir, X represents As, P or Sb, and R represents La, Yb, or Ce. Examples of the transition metal oxide material include NaCoO, CaCoO, ZnInO, SrTiO, BiSrCoO, PbSrCoO, CaBiCoO, BaBiCo0 and the like. An example of the zinc antimonide based material includes ZnSb. Examples of the boron compound include CeB, BaB, SrB, CaB, MgB, VB, NiB, CuB, LiB and the like. Examples of the cluster solid include B cluster, Si cluster, C cluster, AlRe, AlReSi and the like. An example of the zinc oxide based material includes ZnO.
In the second embodiment, in all thermoelectric generating parts 34, the second good thermal conductor 38 is displaced from the first good thermal conductor 37 toward the same side. In the state that the first flexible film 30 and the second flexible film 31 are folded, a direction from the first good thermal conductor 37 toward the second good thermal conductor 38 in the thermoelectric generating device 20 is opposite to that in the adjacent thermoelectric generating device 20.
In the third embodiment, as illustrated in
It is sufficient that the thermal conducting members 21 connected to the first thermal coupling member 22 are inserted to a depth in such a manner that the thermal conducting members 21 are in contact with the second good thermal conductor 38. Similarly, it is sufficient that the thermal conducting members 21 connected to the second thermal coupling member 23 is inserted to a depth in such a manner that the thermal conducting members 21 are in contact with the first good thermal conductor 37.
An example of a temperature distribution is illustrated in
In the third embodiment, an insertion depth of the thermal conducting member 21 is possible to be shallower than that of the second embodiment as illustrated in
In the second embodiment, the thermal conducting members 21 are inserted between the thermoelectric generating devices 20 from the side wall on which the folded portions 33 appear. In the fourth embodiment, the thermal conducting members 21 are inserted between the thermoelectric generating devices 20 from side walls adjacent to the side walls on which the folded portions 33 appear. Also in the fourth embodiment, an electric power generation ability per unit area can be improved as in the case of the second embodiment.
The thermoelectric generator of the second embodiment has high flexibility in a direction (easy curvature direction) from one side wall on which the folded portions 33 appears toward the other side wall. On the other hand, in the direction perpendicular to the easy curvature direction, flexibility is low because the folded portions 33, the first thermal coupling members 22 and the second thermal coupling members 23 hinder bending the stacked structure. In the fourth embodiment, this bending feasibility is less dependent upon directivity because the side walls on which the folded portions 33 appear are different from the side walls along which the first thermal coupling member 22 and the second thermal coupling member 23 are disposed.
In the fourth embodiment, as in the case of the second embodiment, temperature gradients in the in-plane direction in the thermoelectric generating devices 20 are opposite to each other in two adjacent thermoelectric generating devices 20 in the stacked direction. In the fifth embodiment, as in the case of the third embodiment, in all the thermoelectric generating devices 20, the direction of the temperature gradient is the same. More specifically, as illustrated in
The thermal conducting members 21 connected to the first thermal coupling member 22 have a size sufficient for being in contact with the second good thermal conductor 38, and does not disposed in the whole in-plane are of the thermoelectric generating device 20. Similarly, the thermal conducting members 21 connected to the second thermal coupling member 23 have a size sufficient for being in contact with the first good thermal conductor 37, and does not disposed in the whole in-plane are of the thermoelectric generating device 20. As compared to the thermoelectric generator of the fourth embodiment, it is possible to reduce the volume of the first thermal coupling member 22, the second thermal coupling member 23 and the thermal conducting members 21. It is also possible to efficiently generate a temperature difference in the in-plane direction as in the case of the third embodiment.
In the sixth embodiment, slits 45 are formed is the folded portions 33 of the first flexible film 30 and the second flexible film 31, and in areas where the interlayer wirings 24 are not formed. The structure in the thermoelectric generating parts 34 are the same as that of the second embodiment. Namely, a width of the folded portion 33 of the first flexible film 30 and the second flexible film 31 is narrower than a width of the thermoelectric generating part 34. The slits 45 may be formed after the first flexible film 30 and the second flexible film 31 are bonded, or the a first flexible film 30 and the a second flexible film 31 each having slits 45 in advance may be used.
In the sixth embodiment, at the side wall on which the folded portions 33 appears, the folded portions 33 and the first thermal coupling member 22 are not be overlapped to each other, and the folded portions 33 and the second thermal coupling member 23 are not be overlapped to each other. Flexibility of the side wall on which the folded portions 33 appear is therefore improved so that the thermoelectric generator is easy to be bended in a direction perpendicular to a direction from one side wall on which the folded portions 33 appear toward the other side wall. It is also possible to trim weight of the thermoelectric generator.
In the second embodiment, the folded portions 33 are superimposed in the stacked direction, and disposed at the same position in the in-plane direction. In the seventh embodiment, two adjacent folded portions 33 in the stacked direction are displaced in the in-plane direction (lateral direction in
In the second embodiment, metal plates are used as the first thermal coupling member 22, the second thermal coupling member 23 and the thermal 10 conducting members 21. In the seventh embodiment, material obtained by solidifying conductive paste, e.g., silver (Ag) paste is used. Description will be made on a manufacture method for the thermoelectric generator.
In a state (a state illustrated in FIG. 3Eb) that the second flexible film 31 is bonded to the first flexible film 20, Ag paste is coated on the outer surfaces of the first flexible film 30 and the second flexible film 31. Before the coated Ag paste is solidified, the first flexible film 30 and the second flexible film 31 are folded up. As the films are folded up, the structure that the Ag paste is filled between the thermoelectric elements 20 is obtained. The outer surfaces of the outermost thermoelectric generating devices 20 in the stacked direction and the outer surfaces of the folded portions 33 are in the state that the surfaces are covered with Ag paste.
In this state, the Ag paste is solidified by performing a heat process for about 30 minutes at a temperature of, e.g., 200° C. As the Ag paste is solidified, a thermal conducting film 51 covering the surface of the first flexible film 30 and a thermal conducting film 50 covering the surface of the second flexible film 31 are formed. The thermal conducting films 50 and 51 obtained through solidification of the Ag paste have a higher thermal conductivity than that of the first flexible film 30 and the second flexible film 31. A portion of the thermal conducting films 50 and 51 disposed between the thermoelectric generating devices 20 serves as the thermal conducting member 21 of the second embodiment illustrated in
The Ag paste coated on the first flexible film 30 and the second flexible film 31 easily deforms as the flexible films are deformed. It is therefore easy to manufacture even a thermoelectric generator of a complicated shape displacing the positions of the folded portions 33 in the in-plane direction. Even in the complicated shape, high tight contact between the first good thermal conductor 37 and the thermal conducting film 51 and high tight contact between the second good thermal conductor 38 and the thermal conducting film 50 are able to be maintained.
After the second flexible film 31 is bonded to the first flexible film 30 (after the state illustrated in FIG. 3Eb of the second embodiment), a thermal conducting film 56 made of material having a high thermal conductivity such as copper is bonded on the outer surface of the first flexible film 30 using an two-sided adhesive sheet 55. Similarly, a thermal conducting film 58 is bonded on the outer surface of the second flexible film 31 using an two-sided adhesive sheet 57. In bonding the thermal conducting films 56 and 58, a pressure bonding method using a pair of roles 60 and 61 may be adopted. Instead, a heating adhesion method using heating adhesive may also be used. The thermal conducting films 56 and 58 are able to be deformed depending upon deformation of the first flexible film 30 and the second flexible film 31.
As illustrated in
Different portions of the thermal conducting film 56 are made in tight contact with each other, the different portions being located between two portions of the first flexible film 30 facing each other. Similarly, different portions of the thermal conducting film 58 are made in tight contact with each other, the different portions being located between two portions of the second flexible film 31 facing each other.
Adhesive may be used to improve tight contact between the different portions of the thermal conducting film 56 and between the different portions of the thermal conducting film 58.
Portions of the thermal conducting films 56 and 58 sandwiched between the thermoelectric generating devices 20 serve as the thermal conducting members 21 illustrated in
In the thermoelectric generating device of the eighth embodiment, a mounting process for the thermal conducting members 21 and the like is not required to be executed after the first flexible film 30 and the second flexible film 31 are folded up.
In the second embodiment, a plurality of p-type thermoelectric conversion patterns 32P illustrated in FIGS. 3Da and the like are all made of the same thermoelectric conversion material, and a plurality of n-type thermoelectric conversion patterns 32N are also all made of the same thermoelectric conversion material. In the ninth embodiment, the material or composition of the p-type thermoelectric conversion patterns 32P and the n-type thermoelectric conversion patterns 32N is different for each of thermoelectric generating devices 20.
Consider for example the case in which the lowermost thermal conducting member 21 of the stacked structure illustrated in
A thermoelectric conversion efficiency of thermoelectric conversion material generally depends on an operating temperature. As illustrated in
For example, an optimum operating temperature of n-type thermoelectric conversion material doped with Se , namely (Bi2Te3)0.95 (Bi2Se3)0.05, is about 300 K. An optimum operating temperature of n-type thermoelectric conversion material doped with Se, namely (Bi0.7Te0.3)2Te3, is about 220 K. An optimum operating temperature of p-type thermoelectric conversion material doped with Sb, namely (Bi2Te3)0.25 (Sb2Te3)0.75 is equal to or higher than 340 K. An optimum operating temperature of p-type thermoelectric conversion material doped with Sb and Se, namely Bi0.8Sb1.2Te3+7%BiSe3 is about 240 K. An optimum operating temperature is able to be adjusted by adjusting a composition, dopant, a dopant concentration and the like of the thermoelectric conversion material. The optimum operating temperature means an average temperature between high temperature end and low temperature end.
In the ninth embodiment, a suitable thermoelectric conversion material is selected in accordance with an operating temperature of each layer. It is therefore possible to improve an electric power generation efficiency.
In the thermoelectric generator of the second embodiment, as illustrated in FIG. 3Ea, the interlayer wirings 24 interconnects the circuits in adjacent thermoelectric generating parts 34. In the tenth embodiment, the circuit in each of the thermoelectric generating parts 34 is lead to an external terminal 29 by a lead wiring 28.
In the tenth embodiment, by interconnecting the external terminals 29, the circuits in the thermoelectric generating parts 34 may be connected in series or in parallel. If the circuit in one thermoelectric generating part 34 is broken, only the circuits in other good thermoelectric generating parts 34 may be connected excluding the circuit in the broken thermoelectric generating part 34.
The first thermal coupling member 22 is connected to every other thermal conducting members 21. A second thermal coupling member 23 is connected to the thermal conducting members 21 not connected to the first thermal coupling member 22.
Also in the eleventh embodiment, an electric power generation efficiency per unit area is able to be improved as in the case of the first to tenth embodiments.
In the first embodiment, a thickness of each of the thermal conducting members 21, the first thermal coupling member 22 and the second thermal coupling members 23 is uniform. In the twelfth embodiment, both of the first thermal coupling member 22 and the second thermal coupling member 23 are made gradually thicker with distance from the end portion connected to the outermost thermal conducting member 21. For example, in
Namely, a cross sectional area of a thermal path constituted of the first thermal coupling member 22 becomes larger toward a first side in a stacked direction (upward in
The layout of the first good thermal conductors 37 and the second good thermal conductors 38 is the same as the layout of the second embodiment illustrated in
A temperature of the first thermal coupling member 22 is highest at the position connected to the lowermost thermal conducting member 21 directly coupled to the heat generation source, and gradually lowers with distance from this connected position. A temperature of the second thermal coupling member 23 is lowest at the position connected to the uppermost thermal conducting member 21 directly coupled to the heat absorber, and gradually rises with distance from this connected position.
In the twelfth embodiment, a cross sectional area of a thermal path constituted of the first thermal coupling member 22 becomes larger with distance from the heat generation source. As the cross sectional area becomes larger, a thermal resistance lowers. A temperature distribution slope of the first thermal coupling member 22 is able to be made smaller particularly in a portion remoter from the heat generation source and a portion where heat from the heat generation source is hard to be transferred. Similarly, a temperature distribution slope of the second thermal coupling member 23 is able to be made smaller in a portion remoter from the heat absorber and a portion where a cooling effect is mild.
It is therefore possible to make small a difference between the operating temperature of the thermoelectric generating device 20 nearest to the heat generation source and the operating temperature of the thermoelectric generating device 20 nearest to the heat absorber.
Further, in the twelfth embodiment, each of the inner thermal conducting members 21 other than the outermost thermal conducting members 21 becomes gradually thicker from the end connected to the first thermal coupling member 22 or the second thermal coupling member 23 toward the distal end. It is therefore possible to make gentle a temperature gradient near at the distal end of the inner thermal conducting member 21. It is therefore possible to suppress a temperature difference in the in-plane direction from being made small. An average thickness of each thermal conducting member 21 connected to the first thermal coupling member 22 becomes thicker with distance from the heat generation source. Similarly, an average thickness of each thermal conducting member 21 connected to the second thermal coupling member 23 becomes thicker with distance from the heat absorber.
In the twelfth embodiment, although a thickness of the inner thermal conducting member 21 is changed, a thickness of only the first thermal coupling member 22 and the second thermal coupling member 23 may be changed and a thickness of the inner thermal conducting member 21 may be made uniform. Also in the twelfth embodiment, although the thicknesses (cross sectional areas of thermal paths) of the first thermal coupling member 22 and the second thermal coupling member 23 are changed gradually and continuously, the thicknesses may be changed stepwise. If the thicknesses are changed stepwise, the number of steps may be equal to or larger than two.
Six thermal conducting members 21A to 21F are disposed from a heat generation source 70 toward a heat absorber 71 such as a heat sink. A thermoelectric generating device 20 is sandwiched between adjacent thermal conducting members. First, third and fifth thermal conducting members 21A, 21C and 21E are connected to the first thermal coupling member 22, and second, fourth and sixth thermal conducting members 21B, 21D and 21F are connected to the second thermal coupling member 23.
In the thirteenth embodiment, the first thermal coupling member 22 includes a relatively thin portion 22A and a relatively thick portion 22B, which are continuous to each other. The thin portion 22A is connected to the first thermal conducting member 21A and the third thermal conducting member 21C, and the thick portion 22B is connected to the third thermal conducting member 21C and the fifth thermal conducting member 21E.
The second thermal coupling member 23 also includes a relatively thin portion 23A and a relatively thick portion 23B, which are continuous to each other. The thin portion 23A is connected to the sixth thermal conducting member 21F and the fourth thermal conducting member 21D, and the thick portion 23B is connected to the fourth thermal conducting member 21D and the second thermal conducting member 21B.
The first thermal coupling member 22 and the second thermal coupling member 23 of the thirteenth embodiment corresponds to the first thermal coupling member 22 and the second thermal coupling member 23 of the twelfth embodiment illustrated in
The fifth thermal conducting member 21E is thicker than the other first and third thermal conducting members 21A and 21C connected to the first thermal coupling member 22. The second thermal conducting member 21B is thicker than the other fourth and sixth thermal conducting members 21D and 21F connected to the second thermal coupling member 23.
For example, the thicknesses of the thin portion 22A of the first thermal coupling member 22, the thin portion 23A of the second thermal coupling member 23, the first, third, fourth and sixth thermal conducting members 21A, 21C, 21D and 21F are 100 pm. The thicknesses of the thick portion 22B of the first thermal coupling member 22, the thick portion 23B of the second thermal coupling member 23, the second and fifth thermal conducting members 21B and 21E are 180 μm.
Each of the first thermal coupling member 22 and the second thermal coupling member 23 is formed by press bonding or welding a thin steel plate for the thin portion and a thick steel plate for the thick portion.
The thicknesses of the thermal conducting members 21A to 21F, the first thermal coupling member 22 and the second thermal coupling member 23 of the sample illustrated in
For all samples, temperatures were calculated through simulations at the center P1 of the thermoelectric generating device between the fourth thermal conducting member 21D and the fifth thermal conducting member 21E, at the center P2 of the thermoelectric generating device between the third thermal conducting member 21C and the fourth thermal conducting member 21D, and at the center P3 of the thermoelectric generating device between the second thermal conducting member 21B and the third thermal conducting member 21C. The simulations were conducted under the conditions that aluminum is disposed in a space occupied by the thermal conducting members 21A to 21F, the first thermal coupling member 22 and the second thermal coupling member 23, and polyimide is disposed in a space occupied by the thermoelectric generating device among the thermal conducting members 21A to 21F. For the temperature boundary conditions, an outer surface temperature of the first thermal conducting member 21A was set to 100° C., an outer surface temperature of the sixth thermal conducting member 21F was set to 0° C.
Simulation results are illustrated in
It is seen that the sample illustrated in
In the thirteenth embodiment, paying attention to the thermal conducting members connected to the first thermal coupling member 22, the first thermal conducting member 21A and the third thermal conducting member 21C are set to have the same thickness, and only the fifth thermal conducting member 21E is made thicker. However, the third thermal conducting member 21C may be set to have a thickness intermediate between a thickness of the first thermal conducting member 21A and a thickness of the fifth thermal conducting member 21E.
More generally, paying attention to the thermal conducting members 21A, 21C and 21E connected to the first thermal coupling member 22, the thermal conducting member disposed at a first end in the stacked direction of thermoelectric generating devices is thinnest, and the thermal conducting member becomes thicker with distance from the thermal conducting member at the first end. Paying attention to the thermal conducting members 21B, 21D and 21F connected to the second thermal coupling member 23, the thermal conducting member disposed at a second end opposite to the first end in the stacked direction is thinnest, and the thermal conducting member becomes thicker with distance from the thermal conducting member at the second end.
In the eighth embodiment, the thicknesses of the thermal conducting films 56 and 58 are uniform. The thicknesses of the thermal conducting films 56 and 58 of the fourteenth embodiment are monotonously changes in the direction (folding direction) in which the thermoelectric generating parts 34 and the folded parts 33 are arranged. One thermal conducting film 56 becomes gradually thicker from one end (left end in
Of the thermal conducting film 58, a portion in tight contact with the outer surface of the outermost thermoelectric generating device 20 serves as the first thermal conducting member 21A. Of the thermal conducting film 58, portions sandwiched between the thermoelectric generating devices 20 serve as the third and fifth thermal conducting members 21C and 21E. Of the other thermal conducting film 58, a portion in tight contact with the outer surface of the outermost thermoelectric generating device 20 serves as the sixth thermal conducting member 21F. Of the thermal conducting film 56, portions sandwiched between the thermoelectric generating devices 20 serve as the second and fourth thermal conducting members 21B and 21D.
Of the thermal conducting films 58 and 56, portions in tight contact with the folded portion 33 (
The first thermal coupling member 22 and the second thermal coupling member 23 of the thermoelectric generator of the fourteenth embodiment have a thickness distribution tendency similar to that of the first thermal coupling member 22 and the second thermal coupling member 23 of the twelfth embodiment illustrated in
Paying attention to the first, third and fifth thermal conducting members 21A, 21C and 21E connected to the first thermal coupling member 22, the first thermal conducting member 21A being in contact with the heat generation source is thinnest, and the thermal conducting member becomes thicker with distance from first thermal conducting member 21A. Similarly, paying attention to the second, fourth and sixth thermal conducting members 21B, 21D and 21F connected to the second thermal coupling member 23, the sixth thermal conducting member 21F being in contact with the heat absorber is thinnest, and the thermal conducting member becomes thicker with distance from the sixth thermal conducting member 21F.
In the fifteenth embodiment, three thermal conducting films 56A, 56B and 56C are bonded to the surface of a first flexible film 30 with two-sided adhesive sheets 55. The first thermal conducting film 56A is bonded to an area from the thermal electric generating part 34 at one end (left end in
Three heat conductive films 58A, 58B and 58C are also bonded to the second flexible film 31 with a two-sided adhesive sheets 57. The order of the number of thermal conducting films bonded to each thermoelectric generating part 34 of the first flexible film 30 and the order of the number of thermal conducting films bonded to each thermoelectric generating part 34 of the second flexible film 31 have a mutually reversed relation.
More generally, the numbers of thermal conducting films bonded to the first flexible film 30 increase from one end (left end in
The first thermal conducting member 21A is constituted of one thermal conducting film 56A. The second thermal conducting member 21B is constituted of three thermal conducting films 58A, 58B and 58C, and has a lamination structure of six thermal conducting films folded together. Similarly, each of the third and fourth thermal conducting members 21C and 21D has the lamination structure of four thermal conducting films. The fifth thermal conducting member 21E has a lamination structure of six thermal conducting films. The sixth thermal conducting member 21F is constituted of one thermal conducting film 58A.
Paying attention to the first, third and fifth thermal conducting members 21A, 21C and 21E, the thermal conducting members become therefore thicker with distance from the heat generation source being in contact with the first thermal conducting member 21A. Similarly, paying attention to the second, fourth, and sixth thermal conducting members 21B, 21D and 21F, the thermal conducting members become therefore thicker with distance from the heat absorber being in contact with the sixth thermal conducting member 21F.
In the fifteenth embodiment, it is not necessary to prepare a thermal conducting film used in the fourteenth embodiment whose thickness gradually changes, but it is sufficient to prepare a thermal conducting film having a uniform thickness.
In the sixteenth embodiment, each of the second thermal conducting member 21B and the fifth thermal conducting member 21E is constituted of five thermal conducting films. Further, each of the third thermal conducting member 21C and the fourth thermal conducting member 21D is constituted of three thermal conducting films.
Also in the sixteenth embodiment, paying attention to the first, third and fifth thermal conducting members 21A, 21C and 21E, the thermal conducting members become therefore thicker with distance from the heat generation source being in contact with the first thermal conducting member 21A. Similarly, paying attention to the second, fourth, and sixth thermal conducting members 21B, 21D and 21F, the thermal conducting members become therefore thicker with distance from the heat absorber.
As in the case of the fifteenth embodiment, it is not necessary to prepare a thermal conducting film used in the fourteenth embodiment whose thickness gradually changes, but it is sufficient to prepare a thermal conducting film having a uniform thickness.
Next, a thermoelectric generator of the seventeenth embodiment will be described, by paying attention to the different points from the thermoelectric generator of the fourth embodiment illustrated in
The manufacture processes for the thermoelectric generator of the fourth embodiment illustrated in FIG. 3Aa, FIG. 3Ab to FIG. 3Ea, FIG. 3Eb are common to the manufacture processes for the thermoelectric generator of the seventeenth embodiment. Description will be made on the processes after the state illustrated in FIG. 3Ea and FIG. 3Eb.
Of three first thermal conducting members 21A, first thermal conducting columns (first thermal conducting structure) 81A are mounted on the inner surface of the outermost first thermal conducting member 21A. Similarly, of three second thermal conducting members 21B, second thermal conducting columns (second thermal conducting structure) 81B are mounted on the inner surface of the outermost second thermal conducting member 21B. As in the case of the thermal conducting member 21, material having a high thermal conductivity such as copper, aluminum and the like is used for the first and second thermal conducting columns 81A and 81B.
First through holes 82A and second through holes 82B are formed through the first thermal conducting members 21A and the second thermal conducting members 21B, respectively. When the first thermal conducting member 21A is inserted between thermoelectric generating parts 34, the first through holes 82A overlap with the through holes 80 formed in the thermoelectric generating parts 34. Similarly, when the second thermal conducting member 21B is inserted between thermoelectric generating parts 34, the second through holes 82B overlap with the through holes 80. First through holes 82A and the second through holes 82B do not overlap with each other.
In assembling the thermoelectric generator, the second thermal conducting column 81B passes through the through hole 80 and the first through hole 82A and reaches the middle second thermal conducting member 21B. The first thermal conducting column 81A passes through the through hole 80 and the second through hole 82B and reaches the middle first thermal conducting member 21A.
The first thermal conducting member 81A sequentially passes through the through hole 80, the second through hole 82B and the through hole 80 and reaches the middle first thermal conducting member 21A. The first thermal conducting column 81A is fixed to, and thermally coupled to, the middle first thermal conducting member 21A by, e.g., solder 85. Similarly, the second thermal conducting member 81B sequentially passes through the through hole 80, the second through hole 82A and the through hole 80 and reaches the middle second thermal conducting member 21B. The second thermal conducting column 81B is fixed to, and thermally coupled to, the middle second thermal conducting member 21B by, e.g., solder 85.
The solder 85 is provided at the top ends of the first thermal conducting column 21A and the second thermal conducting column 21B in advance before assembly. After the assembly, the first thermal conducting member 21A and the second thermal conducting member 21B are heated to a temperature equal to or higher than the solder melting point, and thereafter cooled to fix the first thermal conducting column 81A to the first thermal conducting member 21A via the solder 85, and to fix the second thermal conducting column 81B to the second thermal conducting member 21B via the solder 85.
The first thermal conducting column 81A is not in contact with the second thermal conducting member 21B at the position passing through the second through hole 82B to be thermally separated from the second thermal conducting member 21B. Similarly, the second thermal conducting column 81B is also thermally separated from the first thermal conducting member 21A. “Being thermally separated” does not mean a perfect heat shielding condition, but means that the thermal conducting column is not coupled via a member having a higher thermal conductivity than that of the first flexible film 30 and the second flexible film 31.
A distance from the first thermal coupling member 22 to the first thermal conducting column 81A is longer than a distance from the first thermal coupling member 22 to the second thermal conducting column 81B. Similarly, a distance from the second thermal coupling member 23 to the second thermal conducting column 81B is longer than a distance from the second thermal coupling member 23 to the first thermal conducting column 81A.
Consider the case in which the outermost first thermal conducting member 21A is in contact with a heat generation source, and the outermost second thermal conducting member 21B is in contact with a heat absorber. Heat is transferred from the outermost first thermal conducting member 21A to the inner first thermal conducting member 21A via the first thermal coupling member 22 and the first thermal conducting column 81A. Heat is transferred to the outermost second thermal conducting member 21B from the inner second thermal conducting member 21B via the second thermal coupling member 23 and the second thermal conducting column 81B.
As compared to the case in which the first and second thermal conducting columns 81A and 81B are not provided, it becomes possible to efficiently heat the inner first thermal conducting member 21A and efficiently cool the inner second thermal conducting member 21B. It is therefore possible to improve an electric power generation efficiency.
Heat is more difficult to be transferred to the region of the first thermal conducting member 21A with distance from the first thermal coupling member 22. It is therefore preferable to dispose the first thermal conducting column 81A in the region where heat is difficult to be transferred. For example, the first thermal conducting column 81A is preferably disposed at a position remoter than the middle point of the first thermal conducting member 21A as viewed from the first thermal coupling member 22. The preferable position where the second thermal conducting member 21B is disposed is similar to the preferable position of the first thermal conducting member 21A.
Next, with reference to
An outer surface temperature of the outermost first thermal conducting member 21A was set to 100° C., and an outer surface temperature of the outermost second thermal conducting member 21B was set to 0° C. Under this condition, temperatures at positions in the thermoelectric generator were calculated by three-dimensional model simulation.
It is therefore possible to generate a larger temperature difference by disposing the first and second thermal conducting columns 81A and 81B. It becomes therefore possible to improve an electric power generation efficiency.
Generally, an electric power generation is proportional to a square of a temperature difference. An electric power generated by the sample corresponding to the seventeenth embodiment is about 1.5 times the electric power generated by the sample according to the comparative example illustrated in
In the seventeenth embodiment, the first and second thermal conducting columns 81A and 81B are provided in the thermoelectric generator of the fourth embodiment. The first and second thermal conducting columns 81A and 81B may be provided also in the thermoelectric generator of the second embodiment illustrated in
As in the case of the thermoelectric generator of the seventeenth embodiment, the through holes 80 are formed through a thermoelectric generating device 20, the first through holes 82A are formed through the first thermal conducting members 21A, and the second through holes 82B are formed through the second thermal conducting members 21B. The first and second thermal conducting columns 81A and 81B (
As illustrated in
The first thermal conducting pin 90A is in contact with the first thermal conducting member 21A so that both are thermally coupled. By covering the side wall of the first thermal conducting pin 90A with solder in advance, and after the first thermal conducting pin 90A is inserted, the solder may be melted and solidified to improve thermal transfer efficiency between the first thermal conducting pin 90A and the first thermal conducting member 21A. Similarly, the side wall of the second thermal conducting pin 90B may be covered with solder in advance.
The first thermal conducting pin 90A is not in contact with the second thermal conducting member 21B, and the second thermal conducting pin 90B is not in contact with the first thermal conducting member 21A.
The first thermal conducting pin 90A and the second thermal conducting pin 90B have the same function as that of the first thermal conducting column (first thermal conducting structure) 81A and the second thermal conducting column (second thermal conducting structure) 81B of the seventeenth embodiment, respectively. Also in the eighteenth embodiment, an electric power generation efficiency is improved as in the case of the seventeenth embodiment.
In the eighteenth embodiment, the thermoelectric generating parts 34, the first thermal conducting member 21A and the second thermal conducting member 21B are assembled to be a stacked structure, and thereafter, the first and second thermal conducting pins 90A and 90B are inserted. As compared to the seventeenth embodiment, assembly is therefore easy.
The through holes 80 which are the same as those of the seventeenth embodiment are formed through a thermoelectric generating device 20. First convex thermal conducting columns (jointing members) 93A are formed on the inner surface of the outermost first thermal conducting members 21A, and first concave thermal conducting columns (jointing members) 94A are formed on an inner surface of the middle first thermal conducting member 21A at positions corresponding to the first convex thermal columns 93A. The tip of the first convex thermal conducting columns 93A and the tip of the first concave thermal conducting columns 94A have geometric shapes which are jointed with each other. By jointing the tip of the first convex thermal conducting column 93A with the first concave thermal conducting column 94A, it is possible to fix the first convex thermal conducting column 93A to the first concave thermal conducting column 94A.
Similarly, the second convex thermal conducting columns (jointing members) 93B and the second concave thermal conducting columns (jointing members) 94B are provided in the second thermal conducting member 21B. As in the case of the seventeenth embodiment, the first through holes 82A and the second through holes 82B are formed through the first thermal conducting member 21A and the second thermal conducting member 21B.
As illustrated in
The first convex thermal conducting member 93A and the first concave thermal conducting member 94A which are jointed with each other have the same function as that of the first thermal conducting column (first thermal conducting structure) 81A of the seventeenth embodiment illustrated in
In the nineteenth embodiment, a heating process for melting solder is not necessary for assembly.
With reference to
As illustrated in
Portions of the two first thermal conducting members 21A face each other via the through hole 80 and the second through hole 82B. The facing portions are pressure bonded together using pressure bonding instruments 100. Similarly, portions of the two second thermal conducting members 21B facing each other via the through holes 80 and the first through hole 82A are pressure bonded together using pressure bonding instruments 100.
As illustrated in
Portions of the outermost first thermal conducting member 21A face the middle first thermal conducting member 21A via a through holes 80 and the second through hole 82B. The facing portions are pressure bonded with each other using pressure bonding instruments 100. Similarly, portions of the outermost thermal conducting member 21B face the middle second thermal conducting member 21B via the through holes 80 and the first through hole 82A. The facing portions are pressure bonded with each other using pressure bonding instruments 100.
As illustrated in
The pressure bonded portion of the first thermal conducting members 21A has the same function as that of the first thermal conducting column (first thermal conducting structure) 81A of the seventeenth embodiment illustrated in
In the twentieth embodiment, since no thermal conducting column is used, the number of components is able to be reduced to realize low cost. Since the thermal conducting members are strongly bonded by pressure bonding, reliability of the thermoelectric generator is able to be improved.
All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-050829 | Mar 2010 | JP | national |
| 2010-203426 | Sep 2010 | JP | national |
| 2011-010795 | Jan 2011 | JP | national |
This application is a Divisional Application of prior application Ser. No. 13/038,761 filed on Mar. 2, 2011, which is based upon and claims the benefit of priority of the prior Japanese Patent Applications No. JP 2010-050829, filed on Mar. 8, 2010, No. JP 2010-203426 filed on Sep. 10, 2010, and No. JP2011-010795 filed on Jan. 21, 2011, the entire contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13038761 | Mar 2011 | US |
| Child | 13959306 | US |
