JP4801466B2 - Thermal stress relaxation pad, thermoelectric conversion system using the same, and Peltier cooling system - Google Patents

Description

  The present invention relates to a thermal stress relaxation pad, a thermoelectric conversion system using the same, and a Peltier cooling system that absorbs heat using the Peltier effect. More specifically, the present invention relates to a thermal stress relaxation pad suitable for use in a thermoelectric conversion system that uses waste heat as a heat source, such as various industrial equipment, having large heating means / cooling means (for example, heating duct / cooling duct). And a thermoelectric conversion system and a Peltier cooling system using the thermal stress relaxation pad.

  As a thermal stress relaxation pad that is sandwiched between a high temperature side member and a low temperature side member having a temperature difference to transmit heat and also relieve thermal stress, there is one disclosed in Japanese Patent Application Laid-Open No. 2001-194022, for example. This thermal stress relaxation pad is shown in FIGS. The thermal stress relaxation pad 101 is sandwiched between a high temperature side member 102 and a low temperature side member 103 having a temperature difference to transmit heat and relax thermal stress. The porous material 104 is used as a matrix to empty the thermal stress relaxation pad 101. The hole 104a is impregnated with a heat transfer material 105 having a high thermal conductivity and a melting point close to the temperature of the low temperature side member 103 during operation.

  The heat transfer material 105 impregnated in the porous material 104 is melted or softened by the heat transferred from the high temperature side member 102 and spreads between the high temperature side member 102 or the low temperature side member 103 by the wettability to fill these gaps. For this reason, contact thermal resistance can be reduced and heat conduction characteristics can be improved. Further, the deformation of the porous material 104 can absorb the difference in thermal deformation amount between the high temperature side member 102 and the low temperature side member 103. The heat transfer material 105 impregnated in the porous material 104 is prevented from leaking from the fine pores 104a of the porous material 104 by the action of the surface tension.

  In this thermal stress relaxation pad 101, the contact thermal resistance can be reduced by filling the gap between the high temperature side member 102 and the low temperature side member 103 with the heat transfer material 105, so that, for example, when used in a thermoelectric conversion system In addition, it is not necessary to assemble each member 102, 103 while strongly pressing the thermal stress relaxation pad 101, so that workability can be improved and damage can be prevented.

JP-A-2001-194022

However, in the above-described thermal stress relaxation pad 101, the porous material 104 is impregnated with the heat transfer material 105, and leakage is prevented by the surface tension. For example, the wettability of the heat transfer material 105 and the porous material 104 is improved. If bad, can not be denied completely that there is a fear that the heat transfer material 105 leaks from the pores 104a of the porous material 104, thermal stress relieving pad can be prevented by Ri確 indeed the leakage of heat transfer material 105 The development of was requested.

The present invention, the leakage of the material to transfer heat to fill the gap between the contact surfaces, as compared with the case of impregnating a porous material, yo Ri確 providing thermal stress relief pad that can indeed be prevented, and An object of the present invention is to provide a thermoelectric conversion system and a Peltier cooling system using the thermal stress relaxation pad.

In order to achieve this object, the invention according to claim 1 is a thermal stress relaxation pad which is sandwiched between a high temperature side member and a low temperature side member having a temperature difference to transfer heat and to relieve thermal stress. And a pad body made of a eutectic alloy of Sn, and either one of the surface facing the high temperature side member and the surface facing the low temperature side member of the pad body is in non-bonding contact with the counterpart member The other surface is covered with the frame member and joined to the mating member, and the Sn component of the pad body is melted or softened by the transmitted heat and leaks between the non-joining mating member. it is shall fill the gap Te.

Therefore, Sn of the pad main body is melted or softened by the heat transmitted from the high temperature side member, and bleeds out into the gap between the mating member on the surface that is in non-bonding contact with the mating member and the gap is formed. fill in. Moreover, the frame member which covers a pad main body is joined with respect to the other party member by the surface on the other side (the other surface), and the space between these is filled. As described above, since there is no gap between the pad main body and the high temperature side member or the low temperature side member, the heat of the high temperature side member is transferred to the low temperature side member through the thermal stress relaxation pad. Is called. Further, the difference in the amount of thermal deformation between the high temperature side member and the low temperature side member is absorbed by the occurrence of slippage between the surface on the side that is not joined to the counterpart member and the counterpart member. A pad body made of a eutectic alloy of Al and Sn can transfer heat well. Compared with the case where a heat transfer material is impregnated into a porous material as in the thermal stress relaxation pad of FIG. 13, the eutectic alloy of Al and Sn constituting the pad body is Sn (heat transfer) in the eutectic reaction state. material) is not the difficulty leaked to separate from Al.

According to a second aspect of the present invention, there is provided a thermal stress relaxation pad which is sandwiched between a high temperature side member and a low temperature side member having a temperature difference to transfer heat and to relieve thermal stress. A pad body made of an alloy is provided. The pad body is in non-bonding contact with the high temperature side member and the low temperature side member, and the Sn component is melted or softened by the transmitted heat, so that it is between the high temperature side member and the low temperature side member. leakage to a shall fill in the gap.

Therefore, Sn transmitted from the high-temperature side member melts or softens, and the pad body oozes into the gap between the high-temperature side member and the low-temperature side member to fill these gaps. As described above, the heat of the high temperature side member is transferred to the low temperature side member through the thermal stress relaxation pad with no gap between the pad main body and the high temperature side member and between the pad main body and the low temperature side member. Is done well. Further, since the pad main body is not joined to the high temperature side member and the low temperature side member, that is, is not joined and is capable of relative movement in the surface direction, the amount of thermal deformation of the high temperature side member and the low temperature side member is reduced. The difference is absorbed by slippage between the pad body and the high temperature side member or the low temperature side member. A pad body made of a eutectic alloy of Al and Sn can transfer heat well. Compared with the case where a heat transfer material is impregnated into a porous material as in the thermal stress relaxation pad of FIG. 13, the eutectic alloy of Al and Sn constituting the pad body is Sn (heat transfer) in the eutectic reaction state. material) is not the difficulty leaked to separate from Al.

  According to a third aspect of the present invention, the thermal stress relaxation pad includes a frame member that covers a side surface of the pad main body. Therefore, the side surface of the pad main body is prevented from being exposed, and Sn is prevented from bleeding into the exposed surface (side surface).

  In the thermal stress relaxation pad according to claim 4, the frame member is made of Al. Therefore, the material compatibility between the pad main body and the frame member is improved.

  The invention according to claim 5 is a thermoelectric conversion system in which a thermoelectric conversion element is disposed between a heating unit and a cooling unit, and between the heating unit and the thermoelectric conversion element, and between the cooling unit and the thermoelectric conversion element, The thermal stress relaxation pad according to any one of claims 1 to 4 is interposed in at least one of them.

  Therefore, for example, when a thermal stress relaxation pad is interposed on both sides of the thermoelectric conversion element, the heating surface of the thermoelectric conversion element is heated by the heat transmitted from the heating means through the thermal stress relaxation pad, and the cooling surface is the thermal stress relaxation pad. Heat is released to the cooling means through and is cooled. Since the thermal stress relaxation pad conducts heat well as described above, a large temperature difference is formed on both sides of the thermoelectric conversion element without applying a large pressure and sandwiching the thermoelectric conversion element between the heating means and the cooling means. A large electromotive force is generated. Further, it is not necessary to interpose the thermal stress relaxation pads on both sides of the thermoelectric conversion element as described above, and the thermal stress relaxation pad may be interposed only between the thermoelectric conversion element and the heating means, or the thermoelectric conversion element and the cooling means. A thermal stress relaxation pad may be interposed only between the two.

  Furthermore, the invention described in claim 6 is a Peltier cooling system in which a Peltier element is disposed between a heat dissipation member and a cooling member, and is at least one of a space between the heat dissipation member and the Peltier element, and between the cooling member and the Peltier element. The thermal stress relaxation pad according to any one of claims 1 to 4 is interposed on one side.

  Therefore, the generation or absorption of heat by the Peltier element is transmitted to the heat radiating member and the cooling member through the thermal stress relaxation pad. Since the thermal stress relaxation pad transfers heat well as described above, it is not necessary to apply a large pressure to sandwich the Peltier element between the heat dissipation member and the cooling member. In addition, a thermal stress relaxation pad may be interposed on both sides of the Peltier element, or a thermal stress relaxation pad may be interposed only between the Peltier element and the heat dissipation member or only between the Peltier element and the cooling member. .

The thermal stress relaxation pad according to claim 1, comprising a pad main body made of an eutectic alloy of Al and Sn, wherein one of the surface facing the high temperature side member and the surface facing the low temperature side member of the pad main body is Since the other side is in non-joining contact with the mating member and the other surface is covered with the frame member and joined to the mating member, the side in non-joining contact with the mating member The gap generated between the surface of the member and the counterpart member can be filled by causing Sn to ooze out using the heat to be transferred. For this reason, even if it does not pinch with big force, the contact thermal resistance of a pad main body, a high temperature side member, or a low temperature side member can be reduced, and a favorable heat conductive characteristic can be acquired. Further, since the surface that is in non-bonding contact with the mating member can cause slippage between the mating member, the difference in the amount of thermal deformation between the high temperature side member and the low temperature side member In addition, thermal expansion displacement due to temperature changes of the high temperature side member and the low temperature side member can be absorbed. Further, compared to the case where a heat transfer material is impregnated into a porous material as in the thermal stress relaxation pad of FIG. 13, the eutectic metal of Al and Sn constituting the pad main body is Sn from Al in the eutectic reaction situation. separation to have difficulty leaked. For this reason, it is possible to extend the life of the product by suppressing the loss of Sn, which is a heat transfer material that fills the gap and improves heat transfer, and it is possible to improve the reliability of heat transfer.

The thermal stress relaxation pad according to claim 2 includes a pad body made of a eutectic alloy of Al and Sn, and the pad body is in non-bonding contact with the high temperature side member and the low temperature side member. The gap between the main body and the high temperature side member and the gap between the pad main body and the low temperature side member can be filled by causing Sn to ooze out using the transmitted heat. For this reason, even if it does not pinch with big force, the contact thermal resistance of a pad main body, a high temperature side member, or a low temperature side member can be reduced, and a favorable heat conductive characteristic can be acquired. Further, since slip can be generated between the pad main body and the high temperature side member or the low temperature side member, the difference in the amount of thermal deformation between the high temperature side member and the low temperature side member, the high temperature side member or the low temperature side member It is possible to absorb thermal expansion displacement due to temperature changes. Further, compared to the case where a heat transfer material is impregnated into a porous material as in the thermal stress relaxation pad of FIG. 13, the eutectic metal of Al and Sn constituting the pad main body is Sn from Al in the eutectic reaction situation. separation to have difficulty leaked. For this reason, it is possible to extend the life of the product by suppressing the loss of Sn, which is a heat transfer material that fills the gap and improves heat transfer, and it is possible to improve the reliability of heat transfer.

  Further, in the thermal stress relaxation pad according to claim 3, since the frame member covering the side surface of the pad main body is provided, the side surface of the pad main body can be prevented from being exposed, and Sn can be prevented from bleeding on the exposed surface. be able to.

  In the thermal stress relaxation pad according to claim 4, since the frame member is formed of Al, the material compatibility between the pad main body and the frame member can be improved.

  Further, in the thermoelectric conversion system according to claim 5, at least one of the heating means and the thermoelectric conversion element and the cooling means and the thermoelectric conversion element is described in any one of claims 1 to 4. Since the thermal stress relaxation pad is interposed, heat transfer and thermal stress relaxation can be performed using the thermal stress relaxation pad described above. For this reason, the joining of the element and the heating means and / or the joining of the element and the cooling means can be made unnecessary, and the system assembly work and the element replacement work are simplified. In addition, since a small pressing force sandwiching the thermoelectric conversion element is sufficient, adjustment of the pressing force is not necessary, and the life of the thermoelectric conversion element and the like can be extended. Furthermore, since the thermal conduction characteristics of the thermal stress relaxation pad are good, the power generation efficiency and the heating / cooling efficiency can be improved.

  Furthermore, in the Peltier cooling system according to claim 6, the heat according to any one of claims 1 to 4 is provided in at least one of the heat dissipation member and the Peltier element and between the cooling member and the Peltier element. Since the stress relaxation pad is interposed, heat transfer and thermal stress relaxation can be performed using the above-described thermal stress relaxation pad. For this reason, it becomes unnecessary to join the element to the heat radiating member or the cooling member, or the number of joints can be reduced, and the system assembly work and the element replacement work are simplified. In addition, since a small pressing force for sandwiching the Peltier element is sufficient, adjustment of the pressing force is not necessary, and the life of the Peltier element can be extended. Furthermore, since the thermal conduction characteristics of the thermal stress relaxation pad are good, the power generation efficiency and the heating / cooling efficiency can be improved.

  Hereinafter, the configuration of the present invention will be described in detail based on the best mode shown in the drawings.

  1 to 3 show an example of an embodiment of the thermal stress relaxation pad of the present invention. 1 is a cross-sectional view taken along the line II of FIG. The thermal stress relaxation pad 1 is sandwiched between a high temperature side member 2 and a low temperature side member 3 having a temperature difference to transmit heat and relax thermal stress, and is made of Al (aluminum) and Sn (tin). A pad body 4 made of a eutectic alloy is provided, and one of the surface 4a facing the high temperature side member 2 and the surface 4b facing the low temperature side member 3 of the pad body 4 is not bonded to the counterpart member. The other surface is covered with the frame member 5 and joined to the counterpart member. In the present embodiment, the surface 4 a facing the high temperature side member 2 is in non-bonding contact with the counterpart member, that is, the high temperature side member 2, and the surface 4 b facing the low temperature side member 3 is covered with the frame member 5. Are joined to the counterpart member, that is, the low temperature side member 3. Here, as a joining means, for example, there is brazing using an AlSi brazing material. Further, the thermal stress relaxation pad 1 includes a frame member 6 that covers the side surface 4 c of the pad main body 4. The frame member 5 and the frame member 6 are integrally formed. That is, the frame member 5 and the frame member 6 constitute a cup-shaped member, and the pad main body 4 is formed in the cup-shaped member. The frame members 5 and 6 are made of, for example, Al.

  The pad body 4 is made of a eutectic alloy of Al and Sn (hereinafter referred to as an Al—Sn alloy). The composition ratio of the Al—Sn alloy is, for example, 10 to 80%, preferably 30 to 50%, more preferably 40% in terms of the Sn weight ratio. In the present embodiment, the composition ratio of the Al—Sn alloy is set to 40% by weight of Sn (the Al—Sn alloy in such a state is referred to as Al-40 wt% Sn. The same applies hereinafter). The reason why the lower limit of the Sn weight ratio is set to 10% is that, when the Sn weight ratio is less than 10%, it is considered difficult to secure the leakage amount of the Sn component that reduces the contact thermal resistance R. Further, the preferable lower limit is set to 30% when the Sn weight ratio is 30% or more, and it becomes easy to secure a sufficient amount of Sn component leakage to satisfactorily reduce the contact thermal resistance R. It is possible. On the other hand, the upper limit of the Sn weight ratio is set to 80% because it is considered that when the Sn weight ratio exceeds 80%, the Al component becomes too small and it is difficult to maintain the Sn component well. The reason why the preferable upper limit value is 50% is that, if the Sn weight ratio is 50% or less, it is considered that it is easy to ensure the amount of Al component suitable for good holding of the Sn component. . Further, the reason why the more preferable value is 40% is that it is considered that both the amount of leakage of Sn and the amount of Al component suitable for retention of Sn can be secured at a high level with a good balance.

  The planar shape of the thermal stress relaxation pad 1 is, for example, a circle. However, the shape is not limited to this shape, and the planar shape may be, for example, a rectangle or a square. In particular, when used in the thermoelectric conversion system 7 as described later, the shape of the thermal stress relaxation pad 1 may be determined in accordance with the shape of the thermoelectric conversion module 12.

  FIG. 4 is a photomicrograph showing the structure of the thermal stress relaxation pad 1 and is at the position indicated by the symbol A in FIG. 4A shows the internal structure of the boundary portion between the frame members 5 and 6 and the pad main body 4, and FIG. 4B shows the internal structure of the pad main body 4 (Al-40 wt% Sn).

  The thermal stress relaxation pad 1 can be manufactured as follows. For example, an Al cup-shaped member is manufactured and heated to, for example, 500 ° C. The peripheral wall of the cup-shaped member becomes the frame member 6, and the bottom plate becomes the frame member 5. Next, for example, an Al—Sn alloy heated to 680 ° C. and melted is poured into the cup-shaped member, and pressurized, for example, at 100 MPa (1000 atm) for 5 minutes. By pressurizing in this way, it is possible to prevent the generation of bubbles that increase the thermal resistance in the Al—Sn alloy. And after making it cool, machining, such as cutting, cutting, and grinding | polishing, is performed and the shape of the pad main body 4 is prepared. However, the manufacturing method of the thermal stress relaxation pad 1 is not limited to the above-described method, and the temperature, pressure, time, and the like can be changed even with the same manufacturing method.

  For example, a thermoelectric conversion system 7 can be configured by using the thermal stress relaxation pad 1. FIG. 5 shows an example of the thermoelectric conversion system 7. The thermoelectric conversion system 7 arranges the thermoelectric conversion element 10 between the heating means 8 and the cooling means 9, and is between the heating means 8 and the thermoelectric conversion element 10 and between the cooling means 9 and the thermoelectric conversion element 10. The thermal stress relaxation pad 1 is interposed in at least one of them. In the present embodiment, the thermal stress relaxation pad 1 is interposed between the heating means 8 and the thermoelectric conversion element 10. The thermoelectric conversion element 10 is sandwiched between, for example, ceramic electrical insulating plates 11 to form a thermoelectric conversion module 12. The thermal stress relaxation pad 1 is not bonded to the heating means 8, that is, in a state in which it can be relatively displaced without being bonded, and is bonded to the thermoelectric conversion module 12.

  The heating means 8 is, for example, a heating duct (hereinafter referred to as a heating duct 8). The cooling means 9 is, for example, a cooling duct (hereinafter referred to as a cooling duct 9). That is, for the thermal stress relaxation pad 1, the heating duct 8 is the high temperature side member 2, and the thermoelectric conversion module 12 is the low temperature side member 3. The cooling duct 9 is joined to the electrical insulating plate 11 of the thermoelectric conversion module 12.

  The thermoelectric conversion system 7 is operated at a heating duct 8 temperature of, for example, 500 ° C. and a cooling duct 9 temperature of, for example, 100 ° C.

  When the thermoelectric conversion system 7 is operated, the Sn component of the pad body 4 of the thermal stress relaxation pad 1 is melted or softened by the heat transmitted from the heating duct 8, and between the heating duct 8 and the thermal stress relaxation pad 1. It oozes out and fills in the gaps. Therefore, even if the facing surface of the heating duct 8 is not flat and the surface roughness is large, the contact thermal resistance between the heating duct 8 and the thermal stress relaxation pad 1 on the high temperature side is reduced and the adhesion is improved. Good heat transfer. For this reason, a large temperature difference close to the temperature difference between the heating duct 8 and the cooling duct 9 can be created on both surfaces of the thermoelectric conversion unit, and the power generation performance of the thermoelectric conversion element 10 can be improved. Note that the thermal stress relaxation pad 1 and the thermoelectric conversion module 12 and the thermoelectric conversion module 12 and the cooling duct 9 are joined, and heat transfer is performed well.

  In addition, a difference in deformation amount due to a temperature difference occurs between the heating duct 8 and the cooling duct 9 due to the operation of the thermoelectric conversion system 7. The difference in the deformation amount is caused by the displacement of the heating means 8 with respect to the thermal stress relaxation pad 1. Can be absorbed. That is, the non-joined surfaces are shifted according to the difference in deformation amount between the heating duct 8 and the cooling duct 9, so that the heat duct 8 and the thermoelectric conversion module 12 are kept in close contact with each other, and deformation or cracking due to generation of thermal stress is maintained. Etc. can be prevented. In FIG. 5, an arrow S indicates a state in which the thermal expansion of the heating duct 8 is allowed by sliding.

  As described above, the thermal stress relaxation pad 1 and the heating duct 8 can be brought into close contact with each other by filling the gap with Sn that transfers heat using the heat transmitted from the heating duct 8, so that the assembly process of the thermoelectric conversion system 7 is performed. Therefore, there is no need to bother the heating duct 8 and the thermoelectric conversion module 12 together. For this reason, joint locations are reduced, the assembly of the thermoelectric conversion system 7 is simplified, and the replacement work of the thermoelectric conversion module 12 during maintenance and the like is also simplified. In addition, the requirements for the flatness and surface roughness of the facing surfaces of the heating duct 8 and the thermoelectric conversion module 12 are alleviated, and the manufacturing is easy and the cost can be reduced. In addition, since the cooling duct 9 and the thermoelectric conversion module 12 are joined, the requirements for the flatness and surface roughness of these facing surfaces are also eased.

  In addition, since the thermoelectric conversion module 12 and the heating duct 8 can be brought into close contact with each other by spreading Sn into the above-described gap as a material (heat transfer material) for transferring Sn, the thermoelectric conversion system 7 is used in order to improve the adhesion. Therefore, it is not necessary to apply a large pressing force when assembling the thermoelectric conversion module 12 between the heating duct 8 and the cooling duct 9 and keep them in close contact with each other. That is, since the thermal stress relaxation pad 1 having excellent adhesion can be obtained, the contact thermal resistance can be reduced even with a small applied pressure. Accordingly, it is not necessary to adjust the pressure applied from above the heating duct 8. Furthermore, since it can be operated with a small applied pressure, the life of the thermoelectric conversion system 7 and the Peltier cooling system described later can be extended.

  Further, since the sliding in the surface direction is possible between the thermal stress relaxation pad 1 and the heating duct 8, it is possible to allow the thermal expansion displacement due to the temperature difference during operation / stop of the heating duct 8. In particular, when the thermoelectric conversion system 7 is increased in size or used at a higher temperature, the thermal expansion displacement of the heating duct 8 increases, but the thermal stress relaxation pad 1 of the present invention can tolerate the thermal expansion displacement. Therefore, the thermoelectric conversion system 7 can be increased in size and temperature. In addition, the temperature difference that can be applied to the thermoelectric conversion module 12 is increased by reducing the contact thermal resistance described above and enabling the sliding in the surface direction between the thermal stress relaxation pad 1 and the heating duct 8. can do. Since the generated power of the thermoelectric conversion module 12 is substantially proportional to the square of the temperature difference, the generated power of the thermoelectric conversion module 12 can be improved even if the same thermoelectric conversion module 12 is used. That is, substantial energy conversion efficiency can be improved. Moreover, this can also reduce the power generation unit price of the thermoelectric conversion system 7.

  In addition, the material which reacts with Sn can be used for the other party member by providing the frame member 5. For example, when the counterpart member is a duct made of Cu, Cu and Sn react with each other, so that it is not appropriate to directly contact the pad main body 4. In such a case, the surface on which the frame member 5 is provided may be joined to the Cu duct. In this way, even if the counterpart member is made of Cu, for example, the thermal stress relaxation pad 1 Can be applied.

  Moreover, for example, a Peltier cooling system can be configured using the thermal stress relaxation pad 1. That is, as shown in FIG. 6, in the Peltier cooling system 16 in which the Peltier element 15 is arranged between the heat dissipation member 13 and the cooling member 14, between the heat dissipation member 13 and the Peltier element 15, and between the cooling member 14 and the Peltier element 15. You may make it interpose the thermal stress relaxation pad 1 in at least any one among them. Also in the Peltier cooling system 16, the same effect as that of the thermoelectric conversion system 7 can be obtained by using the thermal stress relaxation pad 1.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention. For example, in the above description, the surface 4 a facing the high temperature side member 2 of the pad body 4 is in non-bonding contact with the counterpart member, and the surface 4 b facing the low temperature side member 3 is covered by the frame member 5. However, the present invention is not necessarily limited to this configuration, and the surface 4b of the pad main body 4 facing the low temperature side member 3 is brought into non-bonding contact with the counterpart member so that the temperature is high. The surface 4a facing the side member 2 may be covered with the frame member 5 and bonded to the counterpart member.

  Further, in the above description, either one surface of the pad body 4 is covered with the frame member 5 and joined to the counterpart member. However, the both surfaces 4a and 4b of the pad body 4 are connected to the high temperature side member 2 or the low temperature side. You may make it contact with the member 3 by non-joining. That is, for example, as shown in FIG. 7, a thermal stress relaxation pad 1 that is sandwiched between a high temperature side member 2 and a low temperature side member 3 having a temperature difference to transfer heat and relieve thermal stress. A pad body 4 made of a eutectic alloy of Sn and Sn may be provided, and the pad body 4 may be brought into non-bonding contact with the high temperature side member 2 and the low temperature side member 3. In FIG. 7, the same members as those shown in FIGS. 1 to 3 are denoted by the same reference numerals, and detailed description thereof is omitted. In this case, since both sides of the thermal stress relaxation pad 1 need not be joined, the assembly to the high temperature side member 2, the low temperature side member 3, the heating means 8, the cooling means 9, the heat radiating member 13, and the cooling member 14 is more possible. Can be simple. Note that this type of thermal stress relaxation pad 1 can be manufactured, for example, by cutting and removing the frame member 5 formed of the bottom plate portion of the cup-shaped member and exposing the Al—Sn alloy to the bottom surface of the cup-shaped member. .

  In the above description, the frame members 5 and 6 are made of Al. However, the frame members 5 and 6 may be made of a metal other than Al, and the frame member 5 may be made of a material other than metal, such as ceramics. , 6 may be formed.

  In the above description, the frame member 6 that covers the side surface 4c of the pad main body 4 is provided. However, as shown in FIGS. 8 and 9, for example, the frame member 6 is omitted and the pad main body 4 is replaced with the high temperature side member 2. It may be exposed between the low temperature side member 3. This type of thermal stress relaxation pad 1 can be manufactured by, for example, a casting method in which an Al—Sn alloy melted in a mold or the like is poured. 8 is a cross-sectional view taken along line VIII-VIII in FIG. Moreover, the same code | symbol is attached | subjected to the member same as the member shown in FIGS. 1-3.

  In the description of the thermoelectric conversion system 7 described above, the thermal stress relaxation pad 1 is interposed between the heating means 8 and the thermoelectric conversion element 10 (thermoelectric conversion module 12). However, the present invention is not necessarily limited to this configuration. The thermal stress relaxation pad 1 may be interposed between the cooling means 9 and the thermoelectric conversion element 10, and heat is applied between both the heating means 8 and the thermoelectric conversion element 10 and between the cooling means 9 and the thermoelectric conversion element 10. A stress relaxation pad 1 may be interposed. In this case, in the thermal stress relaxation pad 1 interposed between the cooling means 9 and the thermoelectric conversion element 10, the surface on the cooling means 9 side may be a non-bonding surface and the surface on the thermoelectric conversion element 10 side may be a bonding surface. The surface on the conversion element 10 side may be a non-bonding surface, the surface on the cooling means 9 side may be a bonding surface, or both the surface on the cooling means 9 side and the surface on the thermoelectric conversion element 10 side may be non-bonding surfaces. For the thermal stress relaxation pad 1 interposed between the cooling duct 9 and the thermoelectric conversion element 10, the thermoelectric conversion module 12 is the high temperature side member 2, and the cooling duct 9 is the low temperature side member 3.

  In the description of the thermoelectric conversion system 7 described above, the heating unit 8 is a heating duct, for example. However, the heating unit 8 is not limited to the heating duct, and may be a heat source such as a heating surface. In the description of the thermoelectric conversion system 7 described above, the cooling means 9 is, for example, a cooling duct. However, the cooling means 9 is not limited to the cooling duct, and may be any means capable of cooling.

An experiment was conducted to confirm that the contact thermal resistance can be reduced by using the thermal stress relaxation pad 1 of the present invention. In the experiment, the thermal stress relieving pad 1 is sandwiched between the high temperature side member 2 and the low temperature side member 3 so that the contact thermal resistance R (m ² K between the high temperature side member 2 and the low temperature side member 3 is reached. / W) was calculated. The calculation method of the contact thermal resistance R is as follows.

The temperature difference between both surfaces 4a and 4b of the pad body 4 is ΔT (K), and the temperature difference between the contact surface of the high temperature side member 2 with the thermal stress relaxation pad 1 and the contact surface of the low temperature side member 3 with the thermal stress relaxation pad 1 Is ΔT _CP (K), the thickness of the thermal stress relaxation pad 1 is x (m), and the thermal conductivity of the thermal stress relaxation pad 1 is λ (W / mK), the thermal flow rate q (W / m ² ) is It is calculated | required by Numerical formula 1.
(Equation 1)
q = (ΔT × λ) / x

Then, the contact thermal resistance R (m ² K / W) is obtained by Equation 2.
(Equation 2)
R = ΔT _CP / q

  The thermal stress relaxation pad 1 was of a type having frame members 5 and 6 as shown in FIGS. The total thickness of the thermal stress relaxation pad 1 was 10 mm, and the thickness of the pad body 4 was 5 mm. The diameter of the contact surface between the thermal stress relaxation pad 1 and the high temperature side member 2 was 25 mm, and the diameter of the pad body 4 on the contact surface was 21 mm. A heating duct 8 was used as the high temperature side member 2.

The result of the experiment is shown in FIG. The horizontal axis of FIG. 10 is the temperature of the surface 4 a on the high temperature side member 2 side of the thermal stress relaxation pad 1, and the vertical axis is the contact thermal resistance R between the high temperature side member 2 and the thermal stress relaxation pad 1. The temperature T _Sn indicates the melting point (232 ° C.) of Sn. In the figure, measurement was started from point A, heated to point B, then cooled, and measured to point C. As is apparent from the figure, when the temperature of the thermal stress relaxation pad 1 rises and approaches the melting point of Sn, the contact thermal resistance R starts to decrease rapidly, and when the temperature of the thermal stress relaxation pad 1 exceeds the melting point of Sn. It was found that the contact thermal resistance R was reduced to about 1/5. This is because the Sn component softens due to the temperature rise of the pad body 4 made of an Al—Sn alloy and begins to fill the gap between the high temperature side member 2 and the thermal stress relaxation pad 1, and the temperature of the pad body 4 is the melting point of Sn. This is considered to be because the Sn component of the pad main body 4 melts and the gap between the high temperature side member 2 and the thermal stress relaxation pad 1 is satisfactorily filled. Thus, it was confirmed that the contact thermal resistance R can be reduced by using the thermal stress relaxation pad 1 of the present invention.

  An experiment was conducted to confirm the leakage of Sn in the Al—Sn alloy. In the experiment, three types of samples having different composition ratios, namely, Al-10 wt% Sn, Al-20 wt% Sn, Al-40 wt% Sn (composition ratio of Sn, 10%, 20%, 40%) are used. did.

  The sample was made by adding pure tin to a molten aluminum at about 700 ° C. As a mold, a 20 ° C. copper block with a steel tube preheated to 600 ° C. was used. A molten aluminum with tin added thereto was poured into a steel tube as a mold and cooled with a copper block at 20 ° C. to produce a cylinder-shaped sample. The manufactured sample was divided into two along the cylinder axis, and a leakage experiment was performed using one of the two. The divided sample was heated to 400 ° C. in air and left for 2 hours. At this time, the Al-20 wt% Sn sample was placed on a stainless steel plate, and the Al-10 wt% Sn sample and the Al-40 wt% Sn sample were placed on a carbon steel plate.

  The result is shown in FIG. (A) is a sample of Al-10 wt% Sn, (B) is a sample of Al-20 wt% Sn, and (C) is a sample of Al-40 wt% Sn. For any sample, leakage of Sn component could be confirmed. However, the leakage amount of the Sn component increased in the order of Al-10 wt% Sn, Al-20 wt% Sn, and Al-40 wt% Sn. As a result, any of Al-10 wt% Sn, Al-20 wt% Sn, and Al-40 wt% Sn can be used as the pad body 4 of the thermal stress relaxation pad 1, and the use of Al-40 wt% Sn among the three types of samples. Has been confirmed to be most suitable in terms of securing the amount of leakage of the Sn component.

  An experiment was conducted to confirm the bonding between the Al—Sn alloy and the Al frame member. In the experiment, a sample of Al-40 wt% Sn (composition ratio 40% by weight of Sn) was used. The sample was made by adding pure tin to a molten aluminum at about 700 ° C. A steel tube preheated to 550 ° C is mounted on an aluminum plate preheated to 550 ° C, and a molten aluminum (700 ° C) containing tin is poured into the steel tube to produce a cylinder sample of an Al-Sn alloy. did. After cooling, the cylindrical sample was divided into two along the cylinder axis, and one of the samples was used to observe the boundary between the Al—Sn alloy and the aluminum plate with a microscope.

  The result is shown in FIG. (A) is a 50-fold photomicrograph, and (B) is a 100-fold photomicrograph. It was observed that the Al—Sn alloy and the Al plate were completely integrated. Note that the interface between the Al—Sn alloy and the Al plate is wavy, indicating that the aluminum plate has melted. As a result of this experiment, the thermal stress relaxation pad 1 having the frame member 5 or the thermal stress relaxation pad 1 having the frame members 5 and 6 is obtained by pouring molten Al-Sn alloy into the pre-heated Al cup-shaped member. It was confirmed that it could be manufactured.

It is sectional drawing which shows 1st Embodiment of the thermal stress relaxation pad of this invention. It is a top view of the same thermal stress relaxation pad. It is a side view which shows the state which pinched | interposed the thermal stress relaxation pad between the high temperature side member and the low temperature side member. The internal structure of a thermal stress relaxation pad is shown, (A) is a frame member (Al), a pad main body (Al-40 wt% Sn), and the micrograph of a boundary part, (B) is a pad main body (Al-40 wt% Sn). It is a micrograph. It is a side view which shows an example of embodiment of the thermoelectric conversion system of this invention. It is a side view which shows an example of embodiment of the Peltier cooling system of this invention. It is sectional drawing which shows 2nd Embodiment of the thermal stress relaxation pad of this invention. It is sectional drawing which shows 3rd Embodiment of the thermal stress relaxation pad of this invention. It is a top view of the same thermal stress relaxation pad. It is a graph which shows the contact thermal resistance of the thermal stress relaxation pad (pad main body: Al-40 wt% Sn) of FIG. The experimental result for confirming the leak of Sn component is shown, (A) is the figure about the sample of Al-10 wt% Sn, (B) is the figure about the sample of Al-20 wt% Sn, (C) is Al- It is a figure about the sample of 40 wt% Sn. The result of the experiment for confirming that an Al-Sn alloy and Al are satisfactorily integrated is shown, (A) is a micrograph (50 times) of the boundary part of an Al-Sn alloy and an Al plate, (B ) Is a photomicrograph (100 ×) of the boundary portion between the Al—Sn alloy and the Al plate. It is a side view of the conventional thermal stress relaxation pad. FIG. 14 is a partially enlarged view of the thermal stress relaxation pad of FIG. 13.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermal stress relaxation pad 2 High temperature side member 3 Low temperature side member 4 Pad main body 5 The other surface of a pad main body is a frame member 6 The frame member which covers the side surface of a pad main body 7 Thermoelectric conversion system 8 Heating means 9 Cooling means 10 Thermoelectric conversion element 13 Heat dissipation member 14 Cooling member 15 Peltier element 16 Peltier cooling system

Claims (6)

A thermal stress relaxation pad which is sandwiched between a high temperature side member and a low temperature side member having a temperature difference and transmits heat and also relieves thermal stress, comprising: a pad body made of a eutectic alloy of Al and Sn; Either the surface of the main body facing the high temperature side member or the surface facing the low temperature side member is in direct contact with the mating member in a non-bonded manner, and the other surface is covered with a frame member. The Sn component of the pad body is melted or softened by the transmitted heat and leaks between the non-joining counterpart member to fill the gap. Thermal stress relaxation pad. A thermal stress relaxation pad which is sandwiched between a high temperature side member and a low temperature side member having a temperature difference and transmits heat and also relieves thermal stress, comprising: a pad body made of a eutectic alloy of Al and Sn; The main body contacts the high temperature side member and the low temperature side member in a non-bonded state, and the Sn component is melted or softened by the transmitted heat and leaks between the high temperature side member and the low temperature side member to form a gap. A thermal stress relief pad characterized by filling .   The thermal stress relaxation pad according to claim 1, further comprising a frame member that covers a side surface of the pad main body.   The thermal stress relaxation pad according to claim 1, wherein the frame member is made of Al.   In a thermoelectric conversion system in which a thermoelectric conversion element is disposed between a heating unit and a cooling unit, at least one of the heating unit and the thermoelectric conversion element and between the cooling unit and the thermoelectric conversion element is claimed. Item 5. A thermoelectric conversion system comprising the thermal stress relaxation pad according to any one of Items 1 to 4.   In the Peltier cooling system which arrange | positions a Peltier device between a heat radiating member and a cooling member, it is at least any one among the said heat radiating member and the said Peltier device, and between the said cooling member and the said Peltier device. 5. A Peltier cooling system, wherein the thermal stress relaxation pad according to any one of 4 is interposed.