JP5499238B2 - Thermoelectric converter - Google Patents

Description

  The present invention relates to a thermoelectric conversion device used as, for example, an electronic cooling device, and more particularly to a thermoelectric device having a structure in which a heat absorption side heat conductor sandwiching a thermoelectric conversion element and a heat radiation side heat conductor are integrally connected at both ends of a rigid frame. The present invention relates to a conversion device.

  FIG. 14 is a cross-sectional view of a thermoelectric conversion device conventionally proposed in Patent Document 1 and the like. In this thermoelectric conversion device, a block-like heat-absorption-side heat conductor 52 and a plate-like heat-dissipation-side heat conductor 53 are arranged in the vertical direction (stacking direction) with a thermoelectric conversion element 51 in between.

  The heat absorption side heat conductor 52 is fitted inside the peripheral wall 55 of the synthetic resin frame body 54, and the upper end portion 56 of the frame body 54 and the flange portion 57 of the heat absorption side heat conductor 52 are integrally connected by an adhesive 58. Yes. On the other hand, the outer peripheral portion of the heat radiation side thermal conductor 53 and the base end portion 59 extending outward from the peripheral wall 55 of the frame body 54 are integrally connected by an adhesive 60. 61 is an elastic thin film interposed between the thermoelectric conversion element 51 and the heat absorption side heat conductor 52.

  This thermoelectric conversion device is hermetically sealed with a frame 54 so as to surround the thermoelectric conversion element 51 so as to be joined to the heat absorption side heat conductor 52 and the heat dissipation side heat conductor 53 arranged above and below the thermoelectric conversion element 51. The thermoelectric conversion element 51 is interposed so that the heat conductors 52 and 53 are not screwed together.

Japanese Patent No. 3241270

  In the case of the thermoelectric conversion device having this structure, the upper flange portion 57 of the heat absorption side heat conductor 52 is fixed to the upper end portion 56 of the frame body 54 by the adhesive 58, but the lower portion is the peripheral wall of the frame body 54. Although it is surrounded by 55, it is not fixed to the frame body 54. Accordingly, as shown by the vertical arrow 62 in FIG. 14, the space from the lower side of the flange portion 57 of the heat absorption side heat conductor 52 to the upper surface of the heat dissipation side heat conductor 53 is inside the frame body 54, It is a part that causes thermal expansion and contraction without being constrained.

  When the thermoelectric conversion element 51 is in operation, the boundary region between the cooling region and the heat generation region is the substantially central part 63 in the thickness direction of the thermoelectric conversion element 51. Therefore, thermal expansion and thermal contraction occur at the central part 63 as a boundary. To do.

For this reason, as shown in FIG. 14, in the structure in which only one side of the heat conductor (in this conventional example, the heat absorption side heat conductor 52) protrudes inside the frame body 54, the expansion / contraction changes on both sides of the cooling region and the heat generation region. There is a difference in amount, and either shrinkage or expansion becomes larger (in this conventional example, the heat-absorbing side heat conductor 5 protrudes, so the amount of change in shrinkage becomes larger).
Since the heat-absorption-side heat conductor 52 and the heat-dissipation-side heat conductor 53 are fixed to the frame body 54 with the thermoelectric conversion element 51 sandwiched therebetween, stress is applied to the thermoelectric conversion element 51 due to the difference in expansion / contraction displacement described above. Therefore, excellent performance cannot be maintained for a long time, and there is a problem in reliability.

  An object of the present invention is to provide a thermoelectric conversion device that can eliminate such drawbacks of the prior art and ensure reliability over a long period of time.

In order to achieve the object, the invention according to claim 1 is a thermoelectric conversion device in which a heat absorption side heat conductor sandwiching a thermoelectric conversion element and a heat dissipation side heat conductor are integrally connected at both ends of a rigid frame body.
The thickness D from the central portion of the thermoelectric conversion element to the end surface of the portion of the heat absorption side thermal conductor that is not constrained by the frame is determined by the frame body among the heat absorption side thermal conductor, the thermoelectric conversion element, and the heat radiation side thermal conductor. It is characterized by being restricted to a range of + 20% to −40% which is half of the thickness L of the laminated portion of the unconstrained portion.

  This invention is comprised as mentioned above and can provide the thermoelectric conversion apparatus which can ensure reliability over a long period of time.

  The present invention relates to a thermoelectric conversion device having a structure in which a laminated body of a heat absorption side heat conductor, a thermoelectric conversion element and a heat radiation side heat conductor is surrounded by a rigid frame, and the stress generated inside the frame during the cooling operation is Since it differs depending on conditions, various tests and simulations were repeated under different conditions such as refrigeration and freezing, and a thermoelectric conversion device capable of ensuring reliability over a long period of time under various conditions could be obtained.

[Configuration of thermoelectric converter]
Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a thermoelectric conversion device according to a first embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view in the vicinity of a thermoelectric conversion element of the thermoelectric conversion device.

  As shown in FIG. 1, the thermoelectric conversion device according to the embodiment includes a block-like heat absorption side heat conductor 1, a thermoelectric conversion element 2, a plate-like heat radiation side heat conductor frame protrusion 3, and a plate-like heat radiation side. The heat conductor base 4 is sequentially laminated. The heat radiation side heat conductor frame convex portion 3 and the heat radiation side heat conductor base 4 constitute a heat radiation side heat conductor. Although the heat radiation side heat conductor frame in-convex portion 3 and the heat radiation side heat conductor base portion 4 can be formed as a single unit, the heat radiation side heat conductor frame in-convex portion 3 and the heat radiation side heat conductor base portion 4 should be separated. Production efficiency is good and inexpensive.

  Reference numeral 5 denotes a rigid synthetic resin frame body, a base end portion 7 that is integrally joined to the outer peripheral portion of the upper surface of the heat radiation side heat conductor base portion 4 via an adhesive 6, and an inner peripheral portion of the base end portion 7 A peripheral wall 8 standing in the stacking direction of the multilayer body, and a joint that is further narrowed inward from the upper end portion of the peripheral wall 8 and integrally joined to the outer peripheral surface of the heat-absorbing side heat conductor 1 via an adhesive 9 The part 10 is formed continuously and has a step shape as a whole.

  A portion below the dotted line that is not joined to the joining portion 10 of the heat absorption side heat conductor 1 protrudes toward the inside of the frame 5 to constitute a heat absorption side heat conductor frame convex portion 11. The peripheral wall 8 of the frame 5 is spaced apart from the outer peripheral surfaces of the heat-radiating-side heat conductor frame convex portion 3, the thermoelectric conversion element 2, and the heat-absorbing-side heat conductor frame convex portion 11, thereby forming a space portion 12. This space portion 12 is formed to minimize the return of heat during operation.

  As described above, the thermoelectric conversion device adheres the base end portion 7 of the frame body 5 to the outer peripheral surface of the upper surface of the heat dissipating side heat conductor base 4 and bonds the joint portion 10 of the frame body 5 to the outer peripheral surface of the heat absorbing side heat conductor 1. As a result, the inside of the frame 5 is hermetically sealed, and the thermoelectric conversion element 2 has a structure that is sandwiched between the heat-radiating-side thermal conductor frame convex portion 3 and the heat-absorbing-side thermal conductor frame convex portion 11.

  The thermoelectric conversion element 2, the heat radiation side heat conductor frame in-convex portion 3 and the heat absorption side heat conductor frame in the convex portion 11 are portions that are not restrained by the frame body 5, and in FIG. The thickness is represented by A, the thickness of the radiating side heat conductor frame protrusion 3 is represented by B, and the thickness of the thermoelectric conversion element 2 is represented by C. Reference numeral 21 in the figure denotes a temperature boundary line during operation of the apparatus, which corresponds to a substantially central portion in the thickness direction of the thermoelectric conversion element 2.

  As shown in FIG. 2, the thermoelectric conversion element 2 includes a heat absorption side ceramic substrate 13, a stress relaxation layer 14 made of a rubber elastic film, a heat absorption side electrode 15, and a large number of n-type and p-type thermoelectric semiconductors 16 arranged in parallel. And the heat radiation side electrode 17 and the heat radiation side ceramic substrate 18.

  A stress relaxation layer 19 made of a rubber elastic film is provided between the thermoelectric conversion element 2 and the protrusion 11 in the heat absorption side heat conductor frame. In addition, an adhesive 20 made of an elastic body is provided between the thermoelectric conversion element 2 and the projection 3 in the heat radiation side thermal conductor frame.

[Configuration of each part]
FIG. 3 is a diagram collectively showing the material, thickness, and thermal expansion coefficient of each component. In the figure, PPS is polyphenylene sulfide, and GF is glass fiber. In addition, although copper, magnesium, etc. can be used as the heat-radiation-side heat conductor frame in-convex portion 3 and the heat-absorption-side heat conductor frame in-convex portion 11, aluminum is preferable in terms of workability and price.
In this embodiment, ceramic substrates 13 and 18 such as alumina are used for electrical insulation, but there are cases where ceramic substrates are not used by utilizing other insulating means.

The bismuth-tellurium-based semiconductor used as the thermoelectric semiconductor 16 includes a crystal body and a sintered body, and the crystal body has different expansion coefficients in the direction of the crystal axis. Use the high-performance a-axis direction. The expansion coefficient in the a-axis direction is 22 × 10 ⁻⁶ / ° C. (in FIG. 3, this is expressed as 22 ppm / ° C., and the same applies to other components). The expansion coefficient is 16 ppm / ° C. The sintered body is obtained by pulverizing and solidifying a crystal body, and has an expansion coefficient of 18 ppm / ° C.

  The frame 5 needs to use a highly rigid material that is difficult to deform. As a material having high rigidity, a reinforced resin material in which a filler such as glass fiber is mixed into a synthetic resin to increase the elastic modulus and mechanical strength is used. Generally, a synthetic resin mixed with 30 to 60% by weight of glass fiber has an expansion coefficient of about 10 to 40 ppm / ° C. because the physical properties of the glass fiber are strong. As the material of the frame 5, since it has low moisture permeability, high mechanical strength and dimensional accuracy, heat resistance, and excellent workability such as adhesion, GF (polyphenylene sulfide resin) GF ( Glass fiber) reinforced grades are preferred.

  The grade in which GF is mixed in this PPS has different linear expansion coefficients between the flow direction of the resin at the time of injection molding and its orthogonal direction because GF is a fiber. Although depending on the amount of GF filled, the expansion coefficient is about 10 to 20 ppm / ° C. in the direction of resin flow during injection molding. Although the value in the flow direction is 50 to 100% larger and depends on the design of the frame body 5, the expansion coefficient in the stacking direction (vertical direction shown in FIG. 1) of the thermal conductor and thermoelectric conversion element is about 20 to 30 ppm / ° C. is there.

  Silicone rubber-like elastic bodies are used for the stress relaxation layers 14 and 19, and the elongation percentage is 100% or more. Usually, when the thermoelectric conversion element 2 is mounted in a thermoelectric conversion device, as shown in FIG. 2, an adhesive 20 having elasticity is interposed at the interface and assembled. The thickness variation of the adhesive 20 appears as expansion and contraction during the operation of the thermoelectric conversion device, and the stress relaxation layers 14 and 19 are used to absorb the generation of stress associated therewith. Each of the stress relaxation layers 14 and 19 may be one layer or two layers. The total thickness of the stress relaxation layers is suitably 10 to 30 μm, and if it exceeds 30 μm, the thermal resistance increases, which is not preferable in terms of performance.

  The thermoelectric conversion device is assembled through the stress relaxation layers 14 and 19 at room temperature (20 to 25 ° C.). After being fixed by the frame 5 as described above, the stress relaxation layers 14 and 19 absorb the transition accompanying the expansion or contraction of each component that occurs during the operation of the thermoelectric converter. It can be seen that the amount of displacement that can be absorbed stably for a long period of time without degrading the heat conduction performance by the stress relaxation layers 14 and 19 is about ± 10% of the film, and therefore the amount of displacement that can be absorbed is about ± 3 μm.

The material and thermal conductivity of the thermal conductor and stress relaxation layer used in this example are as follows.
Material Thermal conductivity (W / m · K)
Thermal conductor Aluminum 120-130
Stress relaxation layer Silicone elastic body 1

[Operating conditions of thermoelectric converter]
Next, the operating conditions of the thermoelectric converter will be described.

General refrigerator conditions (a: refrigerator operating conditions) are conditions for cooling the interior to 5 ° C. when the outside air is 25 ° C. At this time, the heat-absorbing side heat conductor 1 of the thermoelectric conversion device is around 0 ° C. and dissipates heat. The side heat conductor base portion 4 is around 40 ° C., the heat absorption side heat conductor frame convex portion 11 is also around 0 ° C., and the heat radiation side heat conductor frame convex portion 3 is also around 40 ° C. As shown in FIG. 1, the intermediate region of the temperature is a temperature boundary line 21 at the center of the thermoelectric conversion element 2 in the thickness direction, and the heat absorption side becomes a low temperature and the heat dissipation side becomes a high temperature.
In addition, the operating condition when the outside air is low (b: the low temperature operating condition of the refrigerator outside air) is the case where the outside air is kept at 10 ° C. and the inside of the cabinet is kept at 5 ° C., and the convex portion 11 on the heat absorption side heat conductor frame is about 0 ° C. The heat-radiating-side heat conductor frame protrusion 3 is about 15 ° C.

When the interior is maintained at −18 ° C. when the outside air is 25 ° C. under freezing conditions (c: freezer operating conditions), the heat-absorbing side heat conductor frame convex portion 11 is about −23 ° C., and the heat radiation side heat conductor frame convex portion. 3 is about 50 ° C.
FIG. 4 is a diagram summarizing these operating conditions and the temperature of each component.

[Calculation method of displacement]
Since the thermoelectric converter is assembled at normal temperature (25 ° C.), the amount of change due to internal expansion / contraction during cooling and heating operations is calculated based on the state.
The amount of displacement is calculated by the following equation based on the thermal expansion coefficient of the component, the thickness of the component in the stacking direction (transition direction), and the temperature difference obtained by subtracting 25 ° C. from the temperature during operation of the component.
Displacement = [Thermal expansion coefficient of the part] × [Thickness of the part in the transition direction] × [Temperature difference (attainable temperature−25 ° C.)]
Since the amount of change of the frame 5 is firmly joined to the heat-absorbing-side heat conductor 1 and the heat-dissipating-side heat conductor base 4, it can be regarded as substantially the same temperature. In addition, the intermediate temperature region between cooling and heating is the central portion in the thickness direction of the thermoelectric conversion element 2 as described above.

  The amount of expansion / contraction change during operation of a component located inside the portion where the movement is restricted by adhesion to the frame 5 and the expansion / contraction change of the L part (see FIG. 1) of the frame 5 The amount was calculated, and the stress applied to the thermoelectric conversion element 2 sandwiched between the heat-radiation-side heat conductor frame convex portion 3 and the heat-absorption-side heat conductor frame convex portion 11 was calculated from the subtraction.

[Specific example of calculation of displacement]
a: Refrigerator condition (heat-absorbing side heat conductor frame convex part 11: 0 ° C., heat radiation side heat conductor frame convex part 3: 40 ° C.)
The central portion in the thickness direction of the thermoelectric conversion element 2 becomes a boundary region between cooling and heating, and the upper and lower ends of the thermoelectric conversion element 2 can be regarded as 0 ° C./40° C. Therefore, the heat-absorbing-side heat conductor frame convex portion 11, the heat-absorbing-side ceramic substrate 13 and the heat-absorbing-side electrode 15 are 0 ° C., and the heat-dissipation side electrode 17, the heat-dissipation-side ceramic substrate 18 and the heat-radiation-side heat conductor frame convex portion 3 are 40 ° C. calculate.

The amount of change X inside the frame is the sum of the amount of change of each part. The amount of shift Y of the L part of the frame is obtained by adding Y1 and Y2 calculated by dividing the thickness of the frame in the stacking direction into two (Y = Y1 + Y2).
Displacement amount Y1 of the endothermic frame portion = [thermal expansion coefficient of the frame body] × [thickness 1/2 of the frame body] × [temperature difference on the endothermic side (operation part temperature−25 ° C.)]
Heating side frame portion displacement amount Y2 = [thermal expansion coefficient of frame body] × [frame body thickness ½] × [temperature difference on heating side (operation part temperature−25 ° C.)]
Then, the [total shift amount Z] obtained by subtracting the [frame shift amount Y] from the [internal shift amount X] is calculated. If the value of the calculation result is negative, the peeling stress is applied to the thermoelectric conversion element. If the value of the calculation result is positive, a compressive stress is generated on the thermoelectric conversion element.
[Total shift amount Z] = [Internal shift amount X]-[Frame shift amount Y]

This total shift amount Z needs to be within the absorption range of the stress relaxation layers 14 and 19 provided for stress absorption.
From the assembly state of the thermoelectric conversion device, the amount of absorption of the internal displacement amount X is about ± 10% of the thickness of the stress relaxation layer from the viewpoint of heat transfer performance, and is about ± 3 μm when converted to the actual thickness.

  Although the expansion coefficient of the frame containing glass fibers varies depending on the fiber flow direction, it is in the range of about 10 to 40 ppm / ° C. depending on the glass fiber filling amount and filler shape. And in the case of PPS with 40% by weight of glass fiber, which is considered optimal from the water absorption rate, mechanical strength, and heat resistance, it is considered to be about 20 to 30 ppm / ° C. because the horizontal direction and the vertical direction are combined from the frame structure.

  As the dimensional configuration of the in-frame convex portions of the heat absorption side heat conductor and the heat radiation side heat conductor, configurations as shown in FIGS. FIG. 5 shows a case where the thickness of the heat conductor A is larger than that of the heat conductor B, FIG. 6 shows a case where the heat conductor A and the heat conductor B are substantially equal, and FIG. The case where the thickness of is larger than that of the heat conductor A is shown. The thermoelectric conversion element C is usually 2.0 to 4.5 mm, and here, the calculation is made with 4 mm as a general element thickness.

  When the heat conductor on the upper surface is considered as the heat absorption side, the upper side from the temperature boundary line contracts and the lower side expands. The thermoelectric converter has a symmetrical structure, and expansion and contraction occur at the central part, so it can be seen that the transition is canceled out. It is considered that the thickness and ratio of the upper and lower thermal conductors strongly influence the stress generated in the thermoelectric conversion element.

  On the other hand, when the thermoelectric conversion element is incorporated in the apparatus, the thermoelectric conversion element is incorporated via a heat conductive material having rubber elasticity for the purpose of relaxing the generated stress. Since this thermal conductive material has a thermal resistance when it is too thick, it is as thin as possible about 10 to 20 μm, and the amount of transition that can be absorbed by this elastic thin film is about 1 μm or less. In the case of a transition beyond this, the heat transfer performance is affected, or a large stress is applied to the thermoelectric conversion element, causing the performance to deteriorate rapidly.

  For this reason, the amount of change in the stacking direction necessary for maintaining the reliability of the thermoelectric converter for a long period of time must be within a range of about ± 3 μm.

  In order to protect the thermoelectric conversion element from mechanical external force and to reduce the stress on the thermoelectric conversion element installed inside in the structure surrounding the outer periphery using the frame for the purpose of moisture prevention, It is desirable that the displacement due to expansion / contraction and the displacement of the constituent members are substantially equal. Therefore, a highly reliable thermoelectric conversion device can be obtained by keeping the thickness and vertical ratio of the internal heat conductor within an appropriate range and combining the expansion coefficient in the stacking direction of the frame and the expansion coefficient of the internal heat conductor. This was confirmed by repeating calculations and various tests.

That is,
(A) The expansion coefficient in the stacking direction of the frame is set to 20 to 30 ppm / ° C.
(B) The thickness L of the laminated portion not constrained by the internal frame is 25 mm or less, preferably 15 mm or less.
(C) The thickness D from the central portion of the thermoelectric conversion element to the end face of the heat absorption side heat conductor is in the range of + 20% to −40% of the half (1/2 L) of the laminated portion thickness L.
(D) The expansion coefficient of the frame in the stacking direction is made substantially equal to the expansion coefficient of the internal heat conductor.
That is.

Next, the examination result of the shift amount will be described.
Operating conditions of thermoelectric converter: outside air 25 ° C, inside chamber 0 ° C. Heat conductor A (heat-absorbing side heat conductor frame convex portion 11) 0 ° C., heat conductor B (heat radiation side heat conductor frame convex portion 3) 40 ° C. Heat conductor A portion (heat absorption side heat conductor frame convex portion 11) ) And the heat conductor B (the heat-radiating-side heat conductor frame protrusion 3) were variously changed to obtain the amount of displacement.
The relationship between the heat conductor A portion (the heat absorption side heat conductor frame convex portion 11) and the half ratio K = (A + 1 / 2C) / (L / 2) -1 of the total thickness L was determined.

  These examination results are shown in FIGS. FIGS. 8 and 9 show the thickness and shift amount under various conditions, and FIGS. 10 to 13 show the relationship between the ratio K and the shift amount when the condition of the total thickness L is changed. 8 to 13, the α2 frame 17 is a frame body having an expansion coefficient of 17 ppm / ° C, the α2 frame 20 is a frame body having an expansion coefficient of 20 ppm / ° C, and the α2 frame 23 is a frame body. This shows a case where a frame having an expansion coefficient of 23 ppm / ° C. is used. Further, the frame lines shown in FIGS. 10 to 13 indicate the range of ± 3 μm targeted for the shift amount. The numbers with circles on the columns of FIGS. 8 and 9 correspond to the numbers with circles in FIGS. 10 to 13.

  As is clear from these results, the end face of the portion that is not constrained from the central portion of the thermoelectric conversion element by the frame of the heat absorption side heat conductor in order to be within the range of ± 3 μm that is targeted for the shift amount (within the frame). Thickness D (see FIG. 1) is + 20% to half of the thickness L (see FIG. 1) of the layered portion of the heat-absorbing-side heat conductor, thermoelectric conversion element, and heat-radiating-side heat conductor that is not constrained by the frame. In the range of −40%, that is, in FIG. 8 to FIG. 13, it is necessary to regulate the ratio K to be in the range of + 20% to −40%.

  As shown in FIG. 13, the thickness L of the laminated portion of the heat absorption side heat conductor, the thermoelectric conversion element, and the heat radiation side heat conductor, which is not constrained by the frame, is as thick as 29 mm. Since the thickness of the side heat conductor or (and) the heat radiation side heat conductor is increased, as a result, the range of ± 3 μm is narrowed and is easily deviated from the above range due to dimensional errors in manufacturing. It is better to regulate to 25 mm or less.

  FIG. 15 is a front view, partly in section, of a thermoelectric conversion device according to a second embodiment of the present invention. This embodiment is different from the first embodiment shown in FIG. 1 as follows.

The first difference is that the frame 5 is integrally formed on the outer peripheral portion of the block-like heat absorption side heat conductor 1. Therefore, one groove is formed on the outer periphery of the heat absorption side heat conductor 1, and the resin for the frame body enters the groove during the injection molding of the frame body 5, thereby forming the annular protrusion 22. Therefore, the portion of the heat absorption side heat conductor 1 below the engagement portion (dotted line portion in the figure) between the groove of the heat absorption side heat conductor 1 and the protrusion 22 of the frame 5 is the protrusion 11 in the heat absorption side heat conductor frame. It becomes.
The second difference is that a screw hole 23 is formed in the base end portion 7 of the frame body 5, and a screw (not shown) inserted into the screw hole 23 causes the outer peripheral portion of the heat radiation side heat conductor base portion 4 and the frame body. 5 base end portions 7 are integrally connected.
The third difference is that the heat radiation fins 24 are integrally attached below the heat radiation side heat conductor base 4.

  FIG. 16 is a front view, partly in section, of a thermoelectric conversion device according to a third embodiment of the present invention. This embodiment is different from the second embodiment shown in FIG. 15 as follows.

The first difference is that the center portion of the metal plate is drawn upward to form the heat radiation side heat conductor frame convex portion 3, and the outer peripheral portion thereof is the heat radiation side heat conductor base 4. . Accordingly, in this embodiment, the heat radiation side heat conductor frame convex portion 3 and the heat radiation side heat conductor base 4 are integrated.
The second difference is that a water-cooling jacket 25 is attached to the lower part of the heat-radiating-side heat conductor frame convex portion 3 and the heat-radiating-side heat conductor base 4. A flow path 26 extending in a meandering manner as viewed from above is formed in a portion of the water cooling jacket 25 facing the protrusion 3 in the heat radiation side heat conductor frame, and the cooling water 27 is circulated in the water cooling jacket 25. .

  FIG. 17 is a front view in which a part of the thermoelectric conversion device according to the fourth embodiment of the present invention is sectioned, and FIG. 18 is a front view in which a part of the thermoelectric conversion device according to the comparative example is sectioned.

  Usually, the outer peripheral portion of the thermoelectric converter is covered with a heat insulating layer 28. When the outer peripheral portion of the heat radiation side heat conductor base portion 4 and the base end portion 7 of the frame body 5 are mechanically connected with screws or the like, it is necessarily between the base end portion 7 of the frame body 5 and the lower surface of the heat insulating layer 28. Thus, a gap 29 is formed. Further, when the outer peripheral portion of the heat radiation side heat conductor base portion 4 and the base end portion 7 of the frame body 5 are connected by an adhesive, the base end portion 7 of the frame body 5 and A gap 29 is formed between the lower surface of the heat insulating layer 28.

Under such circumstances, as shown in FIG. 18, the thermoelectric conversion in which the thermoelectric conversion element 2 is placed directly on the plate-like heat radiation side heat conductor base 4 without the heat radiation side heat conductor frame convex portion 3. In the case of a device, or in the case of a thermoelectric conversion device having a very thin thickness even if the heat-radiating-side heat conductor frame convex portion 3 is used, the temperature boundary line 21 located at the central portion in the thickness direction of the thermoelectric conversion element 2 The lower end portion of the heat-absorbing-side heat conductor frame convex portion 11 is located near the gap 29 because it is below the lower surface of the heat insulating layer 28.
Therefore, there is heat leakage from the gap 29 through the peripheral wall 8 of the frame body 5, which causes a decrease in performance of the thermoelectric conversion device.

  On the other hand, as shown in FIG. 17, the temperature boundary line 21 (central portion in the thickness direction) of the thermoelectric conversion element 2 is above the lower surface of the heat insulating layer 28, that is, the temperature boundary line 21 (central portion in the thickness direction). ) Is in the heat insulating layer 28, the heat absorption side region is completely blocked by the heat insulating layer 28, heat leakage from the gap 29 can be prevented, and the performance of the thermoelectric conversion device can be kept high. .

Thus, in order to bring the temperature boundary line 21 (the central portion in the thickness direction) of the thermoelectric conversion element 2 to the upper side of the lower surface of the heat insulating layer 28, a heat radiation side heat conductor frame having a certain thickness is provided. It was found that the inner convex portion 3 is necessary, and the thickness L of the laminated portion needs to be 8 mm or more from various experimental results of the present inventors.
As described above, in order to prevent the heat leakage from the gap 29 and to ensure that the amount of change is within ± 3 μm, the thickness L of the laminated portion is restricted within the range of 8 to 25 mm, preferably 8 to 15 mm. Good.

In FIG. 17 and FIG. 18, reference numeral 30 denotes a heat absorption side auxiliary heat conductor that contacts the heat absorption side heat conductor 1.
The above-described configuration in which the temperature boundary line 21 at the center in the thickness direction of the thermoelectric conversion element 2 is located inside the heat insulating layer 28 is also applicable to the first to third embodiments.
Moreover, in the said 2nd-4th Example, thickness D1 from the center site | part of the thermoelectric conversion element 2 to the end surface of the part which is not restrained by the frame 5 of the heat absorption side heat conductor 1, and the heat radiation side heat from the center site | part of the thermoelectric conversion element 2 The thickness D2 up to the end face of the portion not constrained by the conductor frame 5 is D1≈D2.

It is sectional drawing of the thermoelectric conversion apparatus which concerns on 1st Example of this invention. It is an expanded sectional view near the thermoelectric conversion element of the thermoelectric conversion device. It is the figure which represented collectively the material, thickness, and thermal expansion coefficient of each component which comprise a thermoelectric conversion apparatus. It is the figure which represented collectively the operating condition of the thermoelectric converter, and the temperature of each component. It is a figure which shows the dimension structure of the convex part in a frame of a heat absorption side heat conductor and a heat radiation side heat conductor. It is a figure which shows the dimension structure of the convex part in a frame of a heat absorption side heat conductor and a heat radiation side heat conductor. It is a figure which shows the dimension structure of the convex part in a frame of a heat absorption side heat conductor and a heat radiation side heat conductor. It is the figure which showed collectively the thickness and the variation | change_quantity in various conditions. It is the figure which showed collectively the thickness and the variation | change_quantity in various conditions. It is the characteristic view which showed the relationship between the ratio K at the time of changing the conditions of the total thickness L, and the amount of displacement. It is the characteristic view which showed the relationship between the ratio K at the time of changing the conditions of the total thickness L, and the amount of displacement. It is the characteristic view which showed the relationship between the ratio K at the time of changing the conditions of the total thickness L, and the amount of displacement. It is the characteristic view which showed the relationship between the ratio K at the time of changing the conditions of the total thickness L, and the amount of displacement. It is sectional drawing of the conventional thermoelectric conversion apparatus. It is the front view which made a part of thermoelectric conversion device concerning the 2nd example of the present invention a section. It is the front view which made a part of thermoelectric conversion device concerning the 3rd example of the present invention a section. It is the front view which made a part of thermoelectric conversion device concerning the 4th example of the present invention a section. It is the front view which made a part of thermoelectric conversion device concerning a comparative example a section.

1. . . 1. Heat absorption side heat conductor . . 2. Thermoelectric conversion element . . 3. Convex part on heat dissipation side heat conductor frame . . 4. Radiation side heat conductor base . . Frame 6. . . 6. Adhesive . . Base end 8. . . Peripheral wall 9. . . Adhesive 10. . . Joint 11. . . 11. Convex part in heat absorption side heat conductor frame . . Space part 13. . . Endothermic ceramic substrate 14. . . Stress relaxation layer 15. . . Endothermic electrode 16. . . Thermoelectric semiconductor 17. . . Radiation side electrode 18. . . 18. Heat radiation side ceramic substrate . . Stress relaxation layer 20. . . Adhesive 21. . . Temperature boundary line 22. . . Projection 23. . . Screw hole 24. . . Radiating fin 25. . . Water cooling jacket 26. . . Flow path 27. . . Cooling water 28. . . Thermal insulation layer 29. . . Gap 30. . . Heat absorption side auxiliary heat conductor.

Claims (1)

In the thermoelectric conversion device in which the heat absorption side heat conductor holding the thermoelectric conversion element and the heat dissipation side heat conductor are integrally bonded and fixed at both ends of the rigid frame body,
The thickness D from the central portion of the thermoelectric conversion element to the end surface of the portion of the heat absorption side thermal conductor that is not constrained by the frame is determined by the frame body among the heat absorption side thermal conductor, the thermoelectric conversion element, and the heat radiation side thermal conductor. A thermoelectric conversion device, characterized by being restricted to a range of + 20% to −40%, which is half of the thickness L of the laminated portion of the unconstrained portion.

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