Power conversion device

Abstract

To provide a power conversion device capable of efficiently cooling a heat-generating component.SOLUTION: A power conversion device 10 includes a first heat dissipation material 31 and a second heat dissipation material 41. The thermal conductivity of the second heat dissipation material 41 in the planar direction X is higher than the thermal conductivity of the first heat dissipation material 31 in the planar direction X. A metal cover 14 includes a bead 15 that defines an air layer 22 between the metal cover 14 and the second heat dissipation material 41 in the stacking direction Z.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a power conversion device. [Background technology]

[0002] As an example of a power conversion device, a heat dissipation structure is disclosed in Patent Document 1. The heat dissipation structure in Patent Document 1 includes a heat generating element as a heat generating member, a substrate to which the heat generating element is fixed, a heat diffusion film, a support to support the heat diffusion film facing the heat generating element, and a thermally conductive material layer in contact with the heat generating element and the heat diffusion film. The heat diffusion film includes a graphite film having a thermal conductivity of 200 W / mK or more in the surface direction X and a thermal conductivity of 60 W / mK or less in the thickness direction, and a thickness of 350 μm or less, a protective film, and an adhesive layer between the two. The thermal conductivity of the thermally conductive material layer is 0.9 W / mK or more.

[0003] The heat generated by the heating element is transferred to the thermal diffusion film. The thermal diffusion film spreads the heat generated by the heating element in the planar direction and then releases it to the support, thereby cooling the heating element. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-19085 A Summary of the Invention [Problem to be solved by the invention]

[0005] In a power conversion device, it is always desirable to efficiently cool heat-generating components. [Means for solving the problem]

[0006] A power conversion device for solving the above problems comprises a housing including a housing main body that defines an internal space and a metal cover that closes the internal space, a heat-generating component that is accommodated in the internal space and mounted on the housing main body, a first heat dissipation material that covers a part of the heat-generating component, and a second heat dissipation material that is laminated on a surface of the first heat dissipation material other than the surface of the first heat dissipation material facing the heat-generating component, the second heat dissipation material extending outward more than the first heat dissipation material along a surface direction perpendicular to the laminated direction of the first heat dissipation material and the second heat dissipation material, the second heat dissipation material being laminated on the inner surface side of the metal cover, the thermal conductivity of the second heat dissipation material in the surface direction being higher than the thermal conductivity of the first heat dissipation material in the surface direction, and the metal cover having an air layer defining portion that defines an air layer between the second heat dissipation material in the laminated direction of the metal cover and the second heat dissipation material.

[0007] In the power conversion device, heat generated in the heat generating component is transferred to a first heat dissipation material that is in contact with the heat generating component. The heat transferred to the first heat dissipation material is transferred to a second heat dissipation material that is in contact with the first heat dissipation material. Since the thermal conductivity of the second heat dissipation material in the surface direction is higher than that of the first heat dissipation material, the heat transferred to the second heat dissipation material is efficiently transferred in the surface direction of the second heat dissipation material. Furthermore, an air layer is provided between the metal cover and the second heat dissipation material. The air layer makes it difficult for the heat transferred to the second heat dissipation material to be transferred to the metal cover in the stacking direction. As a result, compared to the case where there is no air layer defining portion, the heat is transferred widely in the surface direction of the second heat dissipation material. In other words, the heat transfer area from the second heat dissipation material in the metal cover is expanded in the surface direction. As a result, the heat dissipation area in the metal cover can be expanded, and the heat generating component can be efficiently cooled.

[0008] In the power conversion device, the air layer defining portion may be a bead recessed from an inner surface of the metal cover in the stacking direction of the metal cover and the second heat dissipation material and protruding from an outer surface of the metal cover.

[0009] According to this, the air layer defining portion can be easily formed in the metal cover, and the metal cover can be reinforced by the bead. The power conversion device may include a plurality of the heat generating components, and a plurality of the first heat dissipation materials covering the metal cover side of each heat generating component.

[0010] This allows a reduction in the amount of first heat dissipation material used compared to the case where one first heat dissipation material is provided in contact with all of the plurality of heat generating components. The power conversion device may include one second heat dissipation material laminated on all of the surfaces of the plurality of first heat dissipation materials other than the surface on the heat generating component side.

[0011] According to this, compared to a case where multiple second heat dissipation materials are scattered corresponding to multiple first heat dissipation materials, a single second heat dissipation material can spread heat more widely in the surface direction of the second heat dissipation material, so that the heat transfer area from the second heat dissipation material in the metal cover can be expanded in the surface direction. As a result, the heat dissipation area of ​​the metal cover can be expanded, and the heat-generating components can be cooled efficiently.

[0012] The power conversion device may further include the second heat dissipation material laminated one by one on each of the surfaces of the plurality of first heat dissipation materials different from the surface on the heat generating component side. This allows a reduction in the amount of second heat dissipation material used compared to the case where one second heat dissipation material is provided in contact with all of the plurality of first heat dissipation materials. Effect of the Invention

[0013] According to the present invention, heat-generating components can be cooled efficiently. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is an exploded perspective view showing a power conversion device. [Diagram 2] FIG. 2 is a cross-sectional view showing the power conversion device. [Diagram 3] FIG. 3 is a plan view showing the power conversion device. [Figure 4] FIG. 4 is an enlarged cross-sectional view showing the bead and the air layer. [Diagram 5]FIG. 5 is an enlarged cross-sectional view showing a comparative example. [Figure 6] FIG. 6 is a cross-sectional view showing a power converter according to another embodiment. [Figure 7] FIG. 7 is a cross-sectional view showing another example of the air layer defining portion. [Figure 8] FIG. 8 is a cross-sectional view showing another example of a power converter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, a specific embodiment of a power conversion device will be described with reference to Figs. <Power conversion device> As shown in FIGS. 1 and 2, the power converter 10 includes a housing 11, a plurality of heat generating components 21, a plurality of first heat dissipation materials 31, and one second heat dissipation material 41.

[0016] <Case> The housing 11 includes a housing body 12 that defines an internal space S, and a metal cover 14 that closes the internal space S.

[0017] <Main unit> The housing body 12 is made of metal. Examples of metals that form the housing body 12 include aluminum alloys and aluminum. The housing body 12 includes a bottom wall 12a and a peripheral wall 12b that stands upright from the bottom wall 12a. An internal space S of the housing body 12 is defined by the bottom wall 12a and the peripheral wall 12b. A female screw hole 12c is formed in the tip surface of the peripheral wall 12b. A plurality of bosses 13 are provided on the bottom wall 12a.

[0018] A substrate 16 is accommodated in the internal space S of the housing body 12, and is fastened to the housing body 12. The substrate 16 has a first main surface 16a and a second main surface 16b which are opposite to each other in the plate thickness direction. The first main surface 16a and the second main surface 16b are parallel to each other. The substrate 16 is fastened to the boss 13 with the second main surface 16b in contact with the tip surface of the boss 13.

[0019] An example of the metal forming the metal cover 14 is iron. The metal cover 14 is in the shape of a flat plate on which a bead 15 is formed. The metal cover 14 has an inner surface 14a and an outer surface 14b which are opposite to each other in the plate thickness direction. The metal cover 14 is placed on the peripheral wall 12b with the inner surface 14a in contact with the tip surface of the peripheral wall 12b. A screw 19 penetrating the metal cover 14 from the outer surface 14b to the inner surface 14a is screwed into the female screw hole 12c. In this way, the metal cover 14 is integrally assembled with the housing main body 12 to form the housing 11. The internal space S is closed by the metal cover 14.

[0020] The metal cover 14 has a plurality of beads 15 as air layer defining portions. Each bead 15 is formed by pressing the metal cover 14 from the inner surface 14a to the outer surface 14b. Each bead 15 is recessed from the inner surface 14a of the metal cover 14 and protrudes outward from the outer surface 14b of the metal cover 14 in an elongated shape. The metal cover 14 has the same number of beads 15 as the number of heat-generating components 21.

[0021] The inner surface 14 a of the metal cover 14 other than the bead 15 is parallel to the first main surface 16 a and the second main surface 16 b of the substrate 16 . <Heat generating components> The heat-generating component 21 is mounted on the first main surface 16a of the substrate 16. Thus, the heat-generating component 21 is housed in the internal space S and is mounted on the housing body 12. The heat-generating component 21 is one of various components constituting the power conversion device 10, and is an electronic component such as a capacitor or a semiconductor element, or a metal pattern. The heat-generating component 21 may be any component that generates heat when current is applied.

[0022] The heat generating component 21 has a first surface 21a and a second surface 21b that are opposite to each other in the thickness direction of the heat generating component 21, and a side surface 21c that connects the first surface 21a and the second surface 21b. The heat generating component 21 is mounted on the board 16 with the second surface 21b facing the first main surface 16a of the board 16. A plurality of heat generating components 21 are arranged on the first main surface 16a of the board 16 at intervals in the planar direction of the first main surface 16a. Thus, the power conversion device 10 has a plurality of heat generating components 21.

[0023] <1st heat dissipation material> The first heat dissipation material 31 is provided corresponding to each of the plurality of heat generating components 21. Therefore, the power conversion device 10 includes a plurality of first heat dissipation materials 31 that cover the metal cover 14 side of each heat generating component 21. The first heat dissipation material 31 covers the entire surface of the heat generating component 21 on the first main surface 16a side of the substrate 16 so as not to contact the heat generating component 21 with the air. The first heat dissipation material 31 is in contact with the entire surface of the heat generating component 21 on the first main surface 16a side. In detail, the first heat dissipation material 31 is in contact with the first surface 21a of the heat generating component 21 and also with the side surface 21c. Therefore, the heat generated in the heat generating component 21 is transferred to the first heat dissipation material 31 from the entire first surface 21a and side surface 21c of the heat generating component 21. The first heat dissipation material 31 is bonded to the first main surface 16a so as to surround the heat generating component 21. Each of the first heat dissipation materials 31 extends from the corresponding heat generating component 21 toward the metal cover 14. Therefore, each of the first heat dissipation materials 31 contacts the heat generating component 21 and extends toward the metal cover 14. The extension direction Z of the first heat dissipation material 31 from the heat generating component 21 toward the metal cover 14 coincides with the plate thickness direction of the metal cover 14, the plate thickness direction of the heat generating component 21, and the plate thickness direction of the substrate 16.

[0024] The first heat dissipation material 31 is a viscoelastic body made of a material with high thermal conductivity. The thermal conductivity of the first heat dissipation material 31 in the planar direction X is preferably 0.8 to 10 W / mk, more preferably 1 to 5 W / mk. Examples of the first heat dissipation material 31 include a silicon heat dissipation gap filler and a silicon heat dissipation sheet. The planar direction X of the first heat dissipation material 31 is a direction perpendicular to the extension direction Z and coincides with the direction along the inner surface 14a of the metal cover 14. The planar direction X exists in all directions centered on an axis extending in the extension direction Z.

[0025] <Second heat dissipation material> The second heat dissipation material 41 is in the form of a thin sheet. The second heat dissipation material 41 is thinner than the first heat dissipation material 31. The second heat dissipation material 41 has a first sheet surface 41a and a second sheet surface 41b which are opposite to each other in the thickness direction. The thickness direction of the second heat dissipation material 41 coincides with the extension direction Z. The first sheet surface 41a and the second sheet surface 41b are parallel to each other. The second heat dissipation material 41 is laminated on the inner surface 14a side of the metal cover 14. Specifically, the first sheet surface 41a of the second heat dissipation material 41 is bonded to the inner surface 14a of the metal cover 14, so that the second heat dissipation material 41 is laminated on the inner surface 14a side of the metal cover 14. As a result, the second heat dissipation material 41 is in surface contact with the inner surface 14a at a portion other than the bead 15 of the metal cover 14, and the second heat dissipation material 41 and the metal cover 14 are laminated. The thickness direction of the second heat dissipation material 41 and the plate thickness direction of the metal cover 14 are the stacking direction of the metal cover 14 and the second heat dissipation material 41. Since the stacking direction coincides with the extension direction Z, it will hereinafter also be referred to as the stacking direction Z. Note that the surface direction X of the second heat dissipation material 41 coincides with the direction along the inner surface 14a of the metal cover 14 and coincides with the surface direction X of the first heat dissipation material 31.

[0026] 2 and 3, the second heat dissipation material 41 is large enough to cover the entire first main surface 16a of the substrate 16. The size of the second heat dissipation material 41 may be smaller or larger than the size required to cover the entire first main surface 16a of the substrate 16. The periphery of the second heat dissipation material 41 is located slightly inside the inner periphery of the peripheral wall 12b of the housing main body 12. In other words, the periphery of the second heat dissipation material 41 is located as close to the periphery of the metal cover 14 as possible.

[0027] In each of the first heat dissipation materials 31, the surface opposite to the contact surface with the first surface 21a of the heat generating component 21 is in contact with the second sheet surface 41b of the second heat dissipation material 41 by being adhered thereto. The second heat dissipation material 41 is laminated on the contact surface 31a, which is a surface different from the surface of the first heat dissipation material 31 on the heat generating component 21 side. Thus, the first heat dissipation material 31 and the second heat dissipation material 41 are laminated. The second heat dissipation material 41 is in contact with the tip surface of the first heat dissipation material 31 in the extension direction Z from the heat generating component 21 toward the metal cover 14, that is, the contact surface 31a, and is in contact with the inner surface 14a of the metal cover 14. Thus, the power conversion device 10 includes one second heat dissipation material 41 laminated on all of the contact surfaces 31a, which are surfaces different from the surface on the heat generating component 21 side of the multiple first heat dissipation materials 31. Further, the second heat dissipation material 41 extends outward from each of the first heat dissipation materials 31 along a plane direction X perpendicular to the stacking direction of the first heat dissipation material 31 and the second heat dissipation material 41. The stacking direction of the first heat dissipation material 31 and the second heat dissipation material 41 coincides with the stacking direction Z of the metal cover 14 and the second heat dissipation material 41.

[0028] The second heat dissipation material 41 is a viscoelastic body made of a material having higher thermal conductivity than the first heat dissipation material 31. The thermal conductivity of the second heat dissipation material 41 in the planar direction X is higher than the thermal conductivity of the first heat dissipation material 31 in the planar direction X. The thermal conductivity of the second heat dissipation material 41 in the planar direction X is preferably 10 times or more the thermal conductivity of the first heat dissipation material 31 in the planar direction X.

[0029] The thermal conductivity of the second heat dissipation material 41 in the plane direction X is preferably 8 to 100 W / mk, and more preferably 10 to 50 W / mk. The material of the second heat dissipation material 41 may be a material having thermal conductivity anisotropy in the plane direction X and the thickness direction, such as a natural graphite film produced by an expanding method, or a synthetic graphite film produced by high-temperature firing of a polymer film.

[0030] <Heat dissipation structure of power conversion device> As shown in FIG. 4, the first sheet surface 41a of the second heat dissipation material 41 is bonded to the inner surface 14a of the metal cover 14 other than the bead 15, and is not bonded to the inner surface of the bead 15. Therefore, in the stacking direction Z of the metal cover 14 and the second heat dissipation material 41, a gap is defined between the first sheet surface 41a of the second heat dissipation material 41 and the inner surface of the bead 15. This gap is an air layer 22 that insulates the heat of the second heat dissipation material 41 from being transferred to the metal cover 14. Therefore, the metal cover 14 has a bead 15 that is recessed from the inner surface 14a of the metal cover 14 and protrudes from the outer surface 14b of the metal cover 14 in the stacking direction Z of the metal cover 14 and the second heat dissipation material 41. This bead 15 is an air layer defining portion that defines the air layer 22 between the second heat dissipation material 41 in the stacking direction Z of the metal cover 14 and the second heat dissipation material 41. The bead 15 is disposed on the opposite side to the first heat dissipation material 31 in the stacking direction Z of the metal cover 14 and the second heat dissipation material 41, with the second heat dissipation material 41 interposed therebetween.

[0031] 3, when the outer shape of the bead 15 is projected onto the first heat dissipation material 31 in the stacking direction Z, the bead 15 is located inside the outer shape of the first heat dissipation material 31. Therefore, the bead 15 is disposed so as to overlap the first heat dissipation material 31 in the stacking direction Z, with the second heat dissipation material 41 sandwiched therebetween.

[0032] Furthermore, when the outer shape of the bead 15 is projected onto the heat generating component 21 in the stacking direction Z, the outer shape of the bead 15 is located inside the outer shape of the heat generating component 21. Therefore, the bead 15 is arranged so as to overlap the heat generating component 21 in the stacking direction Z, sandwiching the first heat dissipation material 31 and the second heat dissipation material 41. Therefore, the air layer 22 overlaps the heat generating component 21, sandwiching the second heat dissipation material 41 and the first heat dissipation material 31, in the stacking direction Z of the metal cover 14 and the second heat dissipation material 41. Therefore, when heat generated in the heat generating component 21 rises, it travels through the first heat dissipation material 31 and the second heat dissipation material 41 to reach the air layer 22.

[0033] <Operation of the embodiment> First, a comparative example will be described. 5, the metal cover 14 of the comparative example does not include the beads 15. Therefore, in the power conversion device 10 of the comparative example, the air layer 22 is not provided between the metal cover 14 and the second heat dissipation material 41 in the stacking direction Z of the metal cover 14 and the second heat dissipation material 41.

[0034] 4, in the power converter 10 of the embodiment, heat generated in the heat generating component 21 on the first main surface 16a side of the substrate 16 is transferred from the entire first surface 21a and side surface 21c of the heat generating component 21 to the first heat dissipation material 31 as shown by the arrow Y1. The heat transferred to the first heat dissipation material 31 rises toward the second heat dissipation material 41.

[0035] Then, the heat of the first heat dissipation material 31 is transferred to the second heat dissipation material 41. Since the second heat dissipation material 41 has a higher thermal conductivity in the plane direction X than the first heat dissipation material 31, the heat transferred to the second heat dissipation material 41 is efficiently transferred in the plane direction X of the second heat dissipation material 41. Here, an air layer 22 is provided between the metal cover 14 and the second heat dissipation material 41. Therefore, the heat transferred to the second heat dissipation material 41 is less likely to be transferred to the metal cover 14 in the stacking direction Z due to the insulation by the air layer 22. Therefore, the heat transferred from the first heat dissipation material 31 to the second heat dissipation material 41 spreads further in the plane direction X of the second heat dissipation material 41 as shown by the arrow Y2.

[0036] 5, the heat transferred from the first heat dissipation material 31 to the second heat dissipation material 41 rises directly in the stacking direction Z and is transferred to the metal cover 14. Therefore, as shown by the arrow Y2, the heat transferred from the first heat dissipation material 31 to the second heat dissipation material 41 does not easily spread in the planar direction X of the second heat dissipation material 41.

[0037] As a result, in the power converter 10 of the embodiment, heat is transferred widely in the planar direction X of the second heat dissipation material 41 as shown by the arrow Y2, compared to the comparative example. As a result, in the metal cover 14 to which heat is transferred from the second heat dissipation material 41, the heat transfer area from the second heat dissipation material 41 is wider than in the comparative example. Therefore, as shown by the arrow Y3, the heat dissipation area in the metal cover 14 can be widened, and the heat-generating component 21 can be cooled efficiently.

[0038] According to the above embodiment, the following effects can be obtained. (1) The bead 15 provides an air layer 22 between the metal cover 14 and the second heat dissipation material 41. When heat is transferred from the first heat dissipation material 31 to the second heat dissipation material 41, the air layer 22 allows the heat to be transferred widely in the surface direction X of the second heat dissipation material 41. As a result, the heat dissipation area of ​​the metal cover 14 can be expanded, and the heat-generating component 21 can be cooled efficiently.

[0039] (2) By providing the air layer 22 between the metal cover 14 and the second heat dissipation material 41, the heat dissipation area of ​​the metal cover 14 can be increased. This allows heat to be efficiently dissipated from the metal cover 14 without increasing the thermal conductivity of the metal cover 14, and therefore the heat-generating components 21 can be efficiently cooled. As a result, the metal cover 14 can be made of iron, which reduces the manufacturing cost of the metal cover 14.

[0040] (3) When the outer shape of the bead 15 is projected onto the heat-generating component 21, the outer shape of the bead 15 is located inside the outer shape of the heat-generating component 21 and, by extension, the first heat dissipation material 31. For this reason, the air layer 22 defined by the bead 15 does not become excessively large relative to the heat-generating component 21 and the first heat dissipation material 31. As a result, it is possible to suppress a decrease in heat transfer to the metal cover 14 and a decrease in heat dissipation performance due to an increase in insulation caused by an excessive increase in the air layer 22.

[0041] (4) The beads 15 are provided one for each heat-generating component 21. Therefore, heat can be released to the metal cover 14 for each heat-generating component 21, so that each heat-generating component 21 can be efficiently cooled.

[0042] (5) One first heat dissipation material 31 is provided for each heat-generating component 21. For example, compared to a case where one first heat dissipation material 31 is provided in contact with all of the heat-generating components 21, the amount of first heat dissipation material 31 used can be reduced, which can reduce the manufacturing cost of the power conversion device 10 and contribute to reducing the weight of the power conversion device 10.

[0043] Furthermore, if the first heat dissipation material 31 is large enough to cover all of the heat-generating components 21, the first heat dissipation material 31 needs to be deformed in order to bring the first heat dissipation material 31 into surface contact with the second heat dissipation material 41. In this case, there is a risk that the substrate 16 will be distorted when the metal cover 14 is pressed against the first heat dissipation material 31 in order to deform the first heat dissipation material 31, which is not preferable. In contrast, since the first heat dissipation material 31 is divided into multiple pieces, the occurrence of the above-mentioned distortion of the substrate 16 can be suppressed.

[0044] (6) The air layer 22 is formed by using the bead 15 formed on the metal cover 14. The bead 15 can be easily formed by pressing the metal cover 14. Therefore, the air layer defining portion can be easily formed, and the bead 15 can reinforce the metal cover 14.

[0045] This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction. As shown in Fig. 6, the power converter 10 may include a plurality of second heat dissipation materials 41. In this case, the plurality of second heat dissipation materials 41 are laminated one by one on each of the contact surfaces 31a, which are surfaces of the plurality of first heat dissipation materials 31 that are different from the surfaces on the heat generating component 21 side. In this configuration, the size of the second heat dissipation material 41 is made larger so as to extend in the planar direction X beyond the contact surface 31a of the first heat dissipation material 31. Then, an air layer 22 is defined between the first sheet surface 41a of the second heat dissipation material 41 and the inner surface of the bead 15.

[0046] When configured in this manner, the amount of second heat dissipation material 41 used can be reduced compared to when a single second heat dissipation material 41 is provided that contacts all of the contact surfaces 31a of the multiple first heat dissipation materials 31, thereby reducing the manufacturing costs of the power conversion device 10.

[0047] As shown in Fig. 7, the air layer 22 does not have to be defined by the bead 15. The metal cover 14 is recessed from the inner surface 14a toward the outer surface 14b in the stacking direction Z of the metal cover 14 and the second heat dissipation material 41 to form a recess 14c within the plate thickness of the metal cover 14. In this configuration, when the second heat dissipation material 41 is stacked on the inner surface 14a side of the metal cover 14, the air layer 22 is defined between the defining surface of the recess 14c in the metal cover 14 and the first sheet surface 41a in the stacking direction Z of the metal cover 14 and the second heat dissipation material 41. Therefore, the recess 14c is an air layer defining portion.

[0048] 8, the heat generating component 21 does not have to be mounted on the substrate 16. The first heat dissipation material 31 may be provided so as to be in contact with only the first surface 21a of the heat generating component 21. In this case, the first heat dissipation material 31 covers a portion of the heat generating component 21.

[0049] The bead 15 may be continuous so as to span multiple heat-generating components 21. In this case, one air layer 22 is provided so as to be stacked on multiple first heat dissipation materials 31 with the second heat dissipation material 41 sandwiched therebetween in the stacking direction Z of the metal cover 14 and the second heat dissipation material 41.

[0050] When the outer shape of the bead 15 is projected onto the heat-generating component 21 , the outer shape of the bead 15 may be larger than the outer shape of the heat-generating component 21 so that the bead 15 extends outside the outer shape of the heat-generating component 21 . The shape of the bead 15 may be any shape as long as an air layer 22 can be defined between the inner surface of the bead 15 and the first sheet surface 41a of the second heat dissipation material 41 in the stacking direction Z of the metal cover 14 and the second heat dissipation material 41.

[0051] The first heat dissipation material 31 does not have to be adhered to the substrate 16, and the second heat dissipation material 41 does not have to be adhered to the contact surface 31a of the first heat dissipation material 31. Furthermore, the second heat dissipation material 41 does not have to be adhered to the inner surface 14a of the metal cover 14.

[0052] The metal cover 14 may be made of an aluminum alloy or aluminum. [Explanation of symbols]

[0053] S...internal space, X...surface direction, Z...stacking direction, 11...housing, 12...housing body, 14...metal cover, 14a...inner surface, 14c...recess as air layer defining portion, 15...bead as air layer defining portion, 21...heat generating component, 22...air layer, 31...first heat dissipation material, 41...second heat dissipation material.

Claims

1. A housing including a housing body defining an internal space and a metal cover closing the internal space; a heat generating component housed in the internal space and mounted on the housing body; A first heat dissipation material that covers a portion of the heat generating component; a second heat dissipation material laminated on a surface of the first heat dissipation material different from the surface of the first heat dissipation material on the heat generating component side, the second heat dissipation material extending outward from the first heat dissipation material along a surface direction perpendicular to a lamination direction of the first heat dissipation material and the second heat dissipation material; the second heat dissipation material is laminated on the inner surface side of the metal cover, The thermal conductivity of the second heat dissipation material in the surface direction is higher than the thermal conductivity of the first heat dissipation material in the surface direction, The power conversion device according to claim 1, wherein the metal cover has an air layer defining portion that defines an air layer between the metal cover and the second heat dissipation material in a stacking direction of the metal cover and the second heat dissipation material.

2. The power conversion device according to claim 1 , wherein the air layer defining portion is a bead that is recessed from an inner surface of the metal cover in the stacking direction of the metal cover and the second heat dissipation material and that protrudes from an outer surface of the metal cover.

3. The power conversion device according to claim 1 or 2, further comprising a plurality of the heat generating components, the first heat dissipation materials each covering a side of the metal cover of each of the heat generating components being a plurality of first heat dissipation materials.

4. The power conversion device according to claim 3 , further comprising a single second heat dissipation material laminated on all of the surfaces of the plurality of first heat dissipation materials other than the surfaces on the heat generating component side.

5. The power conversion device according to claim 3 , further comprising the second heat dissipation material laminated one by one on each of the surfaces of the plurality of first heat dissipation materials that are different from the surfaces on the heat generating component side.

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